Patent Application
20200405824
The instant application contains a Sequence Listing which has been submitted electronically in ASCII format and is hereby incorporated by reference in its entirety. Said ASCII copy, created on Jun. 26, 2020, is named 034186-095790USPT_SL.txt and is 3,439,088 bytes in size.
The technology described herein relates to methods of treating muscular dystrophy and related pathology.
Duchenne muscular dystrophy (DMD) is caused by mutations in the gene encoding dystrophin, a protein that links the cytoplasmic contractile components of muscle cells to the extracellular matrix. The clinical manifestations of disease progression include severe peripheral muscle weakness, respiratory insufficiency, and cardiomyopathy that advances to heart failure in many patients.
A need exists to rescue muscle function in subjects with muscular dystrophy, such as DMD.
The present disclosure relates to a cardiac function-enhancing gene therapy approach that targets myosin in contractile filaments by overexpressing the enzyme ribonucleotide reductase (RNR). RNR converts ADP to deoxy-ADP (dADP), which is rapidly converted to dATP in cells. In humans, RNRs may be encoded by the RRM1 and RRM2 genes. Duchenne muscular dystrophy (DMD) is caused by mutations in the gene encoding dystrophin, a protein that links the cytoplasmic contractile components of muscle cells to the extracellular matrix. When dystrophin is absent or aberrant, the compromised linkage function may cause membrane damage during muscle contraction, which may lead to progressive structural and functional deterioration in cardiomyocytes and skeletal muscle cells. The clinical manifestations of disease progression may include severe peripheral muscle weakness, respiratory insufficiency, and cardiomyopathy that may advance to heart failure in patients. Gene replacement approaches for DMD in animal models and patients can partially ameliorate muscle functional deficits, though given the progressive nature of the disease, it is unclear whether these approaches can adequately address the associated cardiomyopathy. In the present study, the relative cardiac responses in an advanced-age DMD cardiomyopathy mouse model following intravenously administered recombinant adeno-associated viral (rAAV) vectors carrying muscle-specific micro-dystrophin (μDys) or ribonucleotide reductase (RNR) were compared. The results in the working examples demonstrate that both μDys and RNR treatments of DMD hearts can rescue baseline cardiac dysfunction and high workload contractile performance in isolated heart preparations. Systolic function is significantly improved by striated muscle-specific expression of μDys, but only cardiac muscle-specific expression of RNR improved both systolic and diastolic function. It was unexpected that CK8, which is actually stronger in cardiac muscle cells than cTNT, did not work as well for driving RNR expression to improve diastole—that is strength of expression alone is not sufficient to provide the best improvement in diastole. Therefore, cardiac-specific RNR expression can provide a beneficial contractile augmentation therapy for muscular dystrophy. Combination of striated muscle-specific expression of μDys with cardiac muscle-specific expression of RNR can provide further therapeutic benefits.
In one aspect, described herein is a method of treating a subject having muscular dystrophy or DMD. In another aspect, described herein is a method of prophylactically treating a subject at risk of developing muscular dystrophy or DMD. In another aspect, described herein is a method of treating a subject diagnosed with muscular dystrophy or DMD that is at risk of developing cardiomyopathy.
In one embodiment of any of the aspects, the methods comprise administering a pharmaceutical composition including an RRM1 gene, an RRM2 gene, and a delivery vehicle to a subject. In another embodiment of any of the aspects, the methods comprise administering a pharmaceutical composition including an RRM1 gene and an RRM2 gene coupled to a regulatory cassette to a subject. In another embodiment of any of the aspects, the methods include administering a pharmaceutical composition including an RRM 1 gene, an RRM2 gene, a regulatory cassette, and a delivery vehicle to a subject.
In another embodiment of any of the aspects, the methods comprise administering a first pharmaceutical composition including an RRM1 gene in a first delivery vehicle and a second pharmaceutical composition including an RRM2 gene in a second delivery vehicle, such that the first delivery vehicle and the second delivery vehicle are not the same vehicle. In another embodiment of any of the aspects, the methods comprise administering a first pharmaceutical composition including an RRM1 gene coupled to a first regulatory cassette in a first delivery vehicle and a second pharmaceutical composition including an RRM2 gene coupled to a second regulatory cassette in a second delivery vehicle, such that the first delivery vehicle and the second delivery vehicle are not the same vehicle.
In another embodiment of any of the aspects, the methods comprise administering a pharmaceutical composition including (i) an RRM1 gene and/or an RRM2 gene, operably coupled to a first regulatory cassette; (ii) a micro-dystrophin gene encoding a protein, operably coupled to a second regulatory cassette; and (iii) one or more delivery vehicles. In some embodiments, the methods comprise administering a pharmaceutical composition including (i) an RRM 1 gene, operably coupled to a first regulatory cassette; (ii) an RRM2 gene, operably coupled to a second regulatory cassette; (iii) a micro-dystrophin gene encoding a protein, operably coupled to a third regulatory cassette; and (iv) one or more delivery vehicles.
In another embodiment of any of the aspects, the methods comprise administering (i) a first pharmaceutical composition including an RRM1 gene, an RRM2 gene, a first regulatory cassette, and a first delivery vehicle, and (ii) a second pharmaceutical composition including a micro-dystrophin gene, a second regulatory cassette, and a second delivery vehicle, such that the first delivery vehicle and the second delivery vehicle are separate delivery vehicles. In another embodiment of any of the aspects, the methods comprises administering (i) a first pharmaceutical composition including an RRM1 gene, a first regulatory cassette, and a first delivery vehicle, (ii) a second pharmaceutical composition including an RRM2 gene, a second regulatory cassette, and a second delivery vehicle; and (iii) a third pharmaceutical composition including a micro-dystrophin gene, a third regulatory cassette, and a third delivery vehicle, such that the first delivery vehicle, the second delivery vehicle, and the third delivery vehicles are separate delivery vehicles.
In another embodiment of any of the aspects, the regulatory cassettes are selected from the group consisting of: a cardiac troponin T (cTNT) regulatory cassette; a creatine kinase regulatory cassette; a muscle creatine kinase (MCK) regulatory cassette; a CK8 regulatory cassette; a MHCK7 regulatory cassette; CK7 regulatory cassette; and any fragment or combinations thereof.
In another embodiment of any of the aspects, the methods comprise administering (i) a first pharmaceutical composition including an RRM1 gene, an RRM2 gene, a cTnT regulatory cassette, and a first delivery vehicle, and (ii) a second pharmaceutical composition including a micro-dystrophin gene, a CK8 regulatory cassette, and a second delivery vehicle.
In another embodiment of any of the aspects, the methods comprise administering (i) a first pharmaceutical composition including an RRM1 gene, a cTnT regulatory cassette, and a first delivery vehicle, (ii) a second pharmaceutical composition including an RRM2 gene, a cTnT regulatory cassette, and a second delivery vehicle; and (iii) a third pharmaceutical composition including a micro-dystrophin gene, a CK8 regulatory cassette, and a third delivery vehicle.
DNA can be introduced into a subject's cells in several ways. There are transfection methods, including chemical methods such as calcium phosphate precipitation and liposome-mediated transfection, and physical methods such as electroporation. There are also methods that use recombinant viruses. Current viral-vector mediated gene delivery methods include, but are not limited to, retrovirus, lentivirus, adenovirus, herpes virus, pox virus, and adeno-associated virus (AAV) vectors.
In another embodiment of any of the aspects, the delivery vehicle includes an adeno-associated virus (AAV) vector or a recombinant adeno-associated virus vector (rAAV).
In another embodiment of any of the aspects, the pharmaceutical compositions is configured to reduce a pathological effect or symptom of a muscular dystrophy. In another embodiment of any of the aspects, the muscular dystrophy is selected from the group consisting of: myotonic muscular dystrophy, Duchenne muscular dystrophy, Becker muscular dystrophy, limb-girdle muscular dystrophy, facioscapulohumeral muscular dystrophy, congenital muscular dystrophy, oculopharyngeal muscular dystrophy, distal muscular dystrophy, Emery-Dreifuss muscular dystrophy, and/or another suitable muscular dystrophy.
In another aspect, described herein is a method of improving cardiac diastole in a subject in need thereof, the method comprising administering to the subject a therapeutically effective amount of a first pharmaceutical composition comprising an RRM1 gene and an RRM2 gene operably coupled to a first regulatory cassette, whereby cardiac diastole is improved in the subject.
In one embodiment of this or any aspect described herein, cardiac systole is also improved in the subject by said administering.
In another embodiment of this or any aspect described herein, the first regulatory cassette comprises a cardiac muscle-specific regulatory cassette.
In another embodiment of this or any aspect described herein, the cardiac muscle-specific regulatory cassette comprises a cTnT regulatory cassette.
In another embodiment of this or any aspect described herein, the method further comprises administering an effective amount of a second pharmaceutical composition comprising a μDys polypeptide operably coupled to a second regulatory cassette, wherein the second regulatory cassette is different from the first regulatory cassette.
In another embodiment of this or any aspect described herein, the first regulatory cassette comprises a cardiac muscle-specific regulatory cassette, and the second regulatory cassette comprises a striated muscle-specific regulatory cassette.
In another embodiment of this or any aspect described herein, the cardiac muscle-specific regulatory cassette comprises a cTNT regulatory cassette and the striated muscle-specific regulatory cassette comprises a CK8 regulatory cassette.
In another embodiment of this or any aspect described herein, the subject has muscular dystrophy.
In another embodiment of this or any aspect described herein, the subject's muscular dystrophy is a dystrophin-related muscular dystrophy.
For convenience, the meaning of some terms and phrases used in the specification, examples, and appended claims, are provided below. Unless stated otherwise, or implicit from context, the following terms and phrases include the meanings provided below. The definitions are provided to aid in describing particular embodiments, and are not intended to limit the claimed technology, because the scope of the technology is limited only by the claims. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this technology belongs. If there is an apparent discrepancy between the usage of a term in the art and its definition provided herein, the definition provided within the specification shall prevail.
Definitions of common terms in immunology and molecular biology can be found in The Merck Manual of Diagnosis and Therapy, 19th Edition, published by Merck Sharp & Dohme Corp., 2011 (ISBN 978-0-911910-19-3); Robert S. Porter et al. (eds.), The Encyclopedia of Molecular Cell Biology and Molecular Medicine, published by Blackwell Science Ltd., 1999-2012 (ISBN 9783527600908); and Robert A. Meyers (ed.), Molecular Biology and Biotechnology: a Comprehensive Desk Reference, published by VCH Publishers, Inc., 1995 (ISBN 1-56081-569-8); Immunology by Werner Luttmann, published by Elsevier, 2006; Janeway's Immunobiology, Kenneth Murphy, Allan Mowat, Casey Weaver (eds.), Taylor & Francis Limited, 2014 (ISBN 0815345305, 9780815345305); Lewin's Genes XI, published by Jones & Bartlett Publishers, 2014 (ISBN-1449659055); Michael Richard Green and Joseph Sambrook, Molecular Cloning: A Laboratory Manual, 4th ed., Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y., USA (2012) (ISBN 1936113414); Davis et al., Basic Methods in Molecular Biology, Elsevier Science Publishing, Inc., New York, USA (2012) (ISBN 044460149X); Laboratory Methods in Enzymology: DNA, Jon Lorsch (ed.) Elsevier, 2013 (ISBN 0124199542); Current Protocols in Molecular Biology (CPMB), Frederick M. Ausubel (ed.), John Wiley and Sons, 2014 (ISBN 047150338X, 9780471503385), Current Protocols in Protein Science (CPPS), John E. Coligan (ed.), John Wiley and Sons, Inc., 2005; and Current Protocols in Immunology (CPI) (John E. Coligan, ADA M Kruisbeek, David H Margulies, Ethan M Shevach, Warren Strobe, (eds.) John Wiley and Sons, Inc., 2003 (ISBN 0471142735, 9780471142737), the contents of which are all incorporated by reference herein in their entireties.
As used herein, the term “muscular dystrophy” refers to a class of inherited diseases involving progressive weakness and loss of muscle mass. Muscular dystrophies include various forms involving mutation or dysregulation of the expression of the dystrophin gene or its protein product; dystrophin-related muscular dystrophies include Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD), as well as DMD-associated dilated cardiomyopathy. Other non-limiting forms of muscular dystrophies include: myotonic muscular dystrophy, limb-girdle muscular dystrophy, facioscapulohumeral muscular dystrophy, congenital muscular dystrophy, oculopharyngeal muscular dystrophy, distal muscular dystrophy, and Emery-Dreifuss muscular dystrophy.
As used herein, the term “cardiac muscle-specific regulatory cassette” refers to a gene expression regulatory cassette that drives expression of an operatively linked gene sequence in cardiac muscle cells, but substantially not in other muscle cells (including skeletal muscle cells) or other non-muscle cells. By “substantially not” in this regard is meant that the expression of an operatively linked gene sequence is at least 20-fold lower in non-cardiac muscle cells, preferably at least 30-fold lower, at least 40-fold lower, at least 50-fold lower, at least 75-fold lower or at least 100-fold lower in non-cardiac muscle cells. Thus, a cardiac muscle-specific regulatory cassette will drive expression at least 20-fold, at least 30-fold, at least 40-fold, at least 50-fold, at least 75-fold or at least 100-fold more strongly than in non-cardiac muscle cells.
As used herein, the term “striated muscle-specific regulatory cassette” refers to a gene expression regulatory cassette that drives expression of an operatively linked gene sequence in striated muscle cells, but substantially not in non-striated muscle cells or other non-muscle tissues. By “substantially not” in this regard is meant that the expression of an operatively linked gene sequence is at least 20-fold lower in non-striated muscle cells, preferably at least 30-fold lower, at least 40-fold lower, at least 50-fold lower, at least 75-fold lower or at least 100-fold lower in non-striated muscle cells. Thus, a striated muscle-specific regulatory cassette will drive expression at least 20-fold, at least 30-fold, at least 40-fold, at least 50-fold, at least 75-fold or at least 100-fold more strongly than in non-striated muscle cells. It should be understood that cardiac muscle is a type of striated muscle—as such, a striated muscle-specific regulatory cassette will drive gene expression in cardiac, as well as in other striated muscle cells, e.g., skeletal muscle cells.
As used herein, the terms “treat,” “treatment,” “treating,” or “amelioration” refer to therapies, wherein the object is to reverse, alleviate, ameliorate, inhibit, slow down or stop the progression or severity of a condition associated with, a disease or disorder. The term “treating” includes reducing or alleviating at least one adverse effect or symptom of a condition, disease or disorder associated with a muscular dystrophy. Treatment is generally “effective” if one or more symptoms or clinical markers are reduced. Alternatively, treatment is “effective” if the progression of a disease is reduced or halted. That is, “treatment” includes not just the improvement of symptoms or markers, but also a cessation or at least slowing of progress or worsening of symptoms that would be expected in absence of treatment. Beneficial or desired clinical results include, but are not limited to, alleviation of one or more symptom(s), diminishment of extent of disease, stabilized (i.e., not worsening) state of disease, delay or slowing of disease progression, amelioration or palliation of the disease state, and remission (whether partial or total), whether detectable or undetectable. The term “treatment” of a disease also includes providing relief from the symptoms or side-effects of the disease (including palliative treatment).
As used herein “preventing” or “prevention” refers to any methodology where the disease state does not occur due to the actions of the methodology (such as, but not limited to, administration of a pharmaceutical composition or other therapeutic described herein). In one aspect, it is understood that prevention can also mean that the disease is not established to the extent that occurs in untreated controls. Accordingly, prevention of a disease encompasses a reduction in the likelihood that a subject can develop the disease, relative to an untreated subject (e.g. a subject who is not treated with the methods or compositions described herein) likely to develop the disease.
The terms “increased” or “increase” are used herein to mean an increase by a statically significant amount. In some embodiments, the terms “increased” or “increase” can mean an increase of at least 10% as compared to a reference level, for example an increase of at least about 20%, or at least about 30%, or at least about 40%, or at least about 50%, or at least about 60%, or at least about 70%, or at least about 80%, or at least about 90% or up to and including a 100% increase or any increase between 10-100% as compared to a reference level (e.g., the absence of an isolated nucleic acid molecule, polypeptide, vector, composition, or pharmaceutical composition described herein), or at least about a 2-fold, or at least about a 3-fold, or at least about a 4-fold, or at least about a 5-fold or at least about a 10-fold increase, or any increase between 2-fold and 10-fold or greater as compared to a reference level. In the context of a marker or symptom, an “increase” is a statistically significant increase in such level.
The terms “decrease”, “reduced”, “reduction”, or “inhibit” are all used herein to mean a decrease by a statistically significant amount. In some embodiments, “reduce,” “reduction” or “decrease” or “inhibit” typically means a decrease by at least 10% as compared to a reference level (e.g. the absence of an isolated nucleic acid molecule, polypeptide, vector, composition, or pharmaceutical composition described herein) and can include, for example, a decrease by at least about 10%, at least about 20%, at least about 25%, at least about 30%, at least about 35%, at least about 40%, at least about 45%, at least about 50%, at least about 55%, at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 95%, at least about 98%, at least about 99%, or more. As used herein, “reduction” or “inhibition” does not encompass a complete inhibition or reduction as compared to a reference level. “Complete inhibition” is a 100% inhibition as compared to a reference level.
As used herein, a “subject” means a human or animal. Usually the animal is a vertebrate such as a primate, rodent, domestic animal or game animal. Primates include, for example, chimpanzees, cynomolgus monkeys, spider monkeys, and macaques, e.g., Rhesus. Rodents include, for example, mice, rats, woodchucks, ferrets, rabbits and hamsters. Domestic and game animals include, for example, cows, horses, pigs, deer, bison, buffalo, feline species, e.g., domestic cat, canine species, e.g., dog, fox, wolf, avian species, e.g., chicken, emu, ostrich, and fish, e.g., trout, catfish and salmon. In some embodiments, the subject is a mammal, e.g., a primate, e.g., a human. The terms, “individual,” “patient” and “subject” are used interchangeably herein.
Preferably, the subject is a mammal. The mammal can be a human, non-human primate, mouse, rat, dog, cat, horse, or cow, but is not limited to these examples. Mammals other than humans can be advantageously used as subjects that provide animal models of disease e.g., cardiac disease or disorder, such as myocardial infarction or myocardial ischemia. A subject can be male or female.
A subject can be one who has been previously diagnosed with or identified as suffering from or having a condition in need of treatment (e.g., muscular dystrophy) or one or more complications related to such a condition, and optionally, have already undergone treatment for the condition or the one or more complications related to the condition. Alternatively, a subject can also be one who has not been previously diagnosed as having such condition or related complications. For example, a subject can be one who exhibits one or more risk factors for the condition or one or more complications related to the condition or a subject who does not exhibit risk factors.
A “subject in need” of treatment for a particular condition can be a subject having that condition (e.g., muscular dystrophy or a complication thereof), diagnosed as having that condition, or at risk of developing that condition. As non-limiting examples, a subject diagnosed with or suffering from a given condition, a subject determined to have a mutation predisposing to a given condition, and a subject whose parent or sibling is known to carry a mutation predisposing to a given condition are each subjects in need of treatment.
In some embodiments, a polypeptide described herein (or a nucleic acid encoding such a polypeptide) can be a functional fragment of one of the polypeptides described herein, e.g., a functional fragment of a dystrophin (including a μDys), RRM1 or RRM2 polypeptide.
The term “statistically significant” or “significantly” refers to statistical significance and generally means a two standard deviation (2SD) or greater difference.
As used herein the term “comprising” or “comprises” is used in reference to compositions, methods, and respective component(s) thereof, that are essential to the method or composition, yet open to the inclusion of unspecified elements, whether essential or not.
As used herein the term “consisting essentially of” refers to those elements required for a given embodiment. The term permits the presence of additional elements that do not materially affect the basic and novel or functional characteristic(s) of that embodiment of the invention.
The singular terms “a,” “an,” and “the” include plural referents unless context clearly indicates otherwise. Similarly, the word “or” is intended to include “and” unless the context clearly indicates otherwise.
Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of this disclosure, suitable methods and materials are described below. The abbreviation, “e.g.” is derived from the Latin exempli gratia, and is used herein to indicate a non-limiting example. Thus, the abbreviation “e.g.” is synonymous with the term “for example.”
The patent or application file contains at least one drawing executed in color. Copies of this patent application publication with color drawings will be provided by the Office upon request and payment of the necessary fee.
Duchenne Muscular Dystrophy (DMD) and its milder and allelic form, Becker muscular dystrophy (BMD), are the most frequent muscular dystrophies, occurring once in ˜5000 male births, and are due to mutations in the dystrophin gene (1). DMD patients typically die due to cardiac and respiratory muscle failure; thus, maintenance of adequate function in both cardiac and skeletal muscle is important for optimal DMD therapy. The primary function of dystrophin is to provide a structural role by mechanically linking the subsarcolemmal cytoskeleton to the extracellular matrix (ECM) through the dystrophin-glycoprotein complex (DGC) (2). This linkage transmits the forces of contraction to the extracellular matrix (ECM) and protects muscles from contraction-induced injury (3-7). In addition to a structural or mechanical role, the DGC also serves as a scaffold for cytoplasmic and membrane-associated signaling proteins and ion channels (8-11). The complete absence of dystrophin results in drastic reductions of all DGC components (12-14). Together, an absence of dystrophin and reduction in the DGC components causes membrane destabilization and permeability defects that lead to myofiber degeneration, repeated cycles of degeneration/regeneration, and the gradual replacement of muscle fibers with fibrotic, connective, and adipose tissue.
In contrast, some in-frame deletions, truncations, and missense mutations lead to reduced dystrophin expression associated with milder phenotypes. These pathologies are largely curtailed in mouse (mdx) and canine (cxmd) models of DMD following the vector mediated delivery of muscle-specific expression of highly functional miniaturized versions of dystrophin, micro-dystrophin (μDys) (15-24). In mdx mice, muscle pathology may be milder than in humans; however, the dystrophic phenotype may worsen with increasing age including the development of cardiac dysfunction (25-32). Administration of rAAV-mediated μDys therapy in mdx mice preceding the onset of cardiomyopathy may be highly cardioprotective (33-35). However, when mdx mice are treated with μDys at a late stage of cardiomyopathy, such as would be the case for a number of DMD patients, a full rescue of the dysfunctional cardiac phenotype is not achieved (30,35-37).
The present disclosure relates to a cardiac function-enhancing gene therapy approach that targets myosin in contractile filaments and overexpresses the enzyme ribonucleotide reductase (RNR). RNR converts ADP to deoxy-ADP (dADP), which can be rapidly converted to dATP in cells. In numerous in vitro studies, it has been shown that dATP can increase cross bridge binding and cycling, which results in stronger, faster contraction and faster relaxation (38-46). Furthermore, dATP can improve the contractile properties of the myocardium from end-stage human heart failure (HF) in vitro (43) and in dog models with end-stage idiopathic dilated cardiomyopathy (47). In normal rodent muscle, increases in cardiomyocyte and cardiac function can occur with as little as ˜1% of the ATP pool in the dATP form (40,48). Similarly, rAAV-mediated delivery of RNR under cardiac specific regulatory control can result in enzyme overexpression exclusively in cardiomyocytes and significantly improved left ventricular function without adverse cardiac remodeling in normal and infarcted rodent hearts (49). Thus, dATP can rescue the pre-load responsiveness of failing hearts, restoring the pressure and volume to normal.
In the working examples, the relative therapeutic capacity of muscle-specific microdystrophin (μDys) or ribonucleotide reductase (RNR), via intravenously administered recombinant adeno-associated viral (rAAV) vectors in an advanced age, DMD cardiomyopathy mouse model, were compared. A restoration of myocardial workload was demonstrated as indicated by rate pressure product (RPP), for baseline function in mdx4cv mice treated with RNR. This outcome was primarily attributed to the normalization of left ventricular developed pressure (LVDevP). Although mdx4cv mice treated with μDys appeared to normalize LVDevP, this did not result in a significant increase in RPP. Upon further evaluation of cardiac function, the pressure-volume relationship revealed that systolic pressure response with increased preload was significantly improved with the treatment of either RNR or μDys. However, only RNR treatment resulted in significant improvements in diastolic functional parameters, returning them to values that were similar to wild-type control hearts. As a further assessment of cardiac function, hearts were tested using a high workload challenge protocol. Both RNR and μDys treatments improved systolic function in mdx4cv hearts without compromising cardiac reserve. The results in the examples described herein demonstrate that targeted expression of RNR within the myocardium significantly improves contractile performance in an advanced age model of DMD cardiomyopathy and can be a valuable therapeutic for the prevention and treatment of muscular dystrophy and DMD patients. Surprisingly, cardiac-specific expression of RNR improved systolic and diastolic function of the heart to a greater extent than striated muscle-specific expression of RNR, despite the actual level of RNR driven in cardiac cells by a cardiac-specific regulatory cassette being lower than expression from the striated muscle-specific cassette.
Compositions and methods are provided herein for treating muscular dystrophy by delivering one or more constructs encoding ribonucleotide reductase (RNR) activity to muscle in a subject in need thereof. In some embodiments, the construct is delivered alone—i.e., no other therapeutic constructs are delivered, and the RNR improves muscle function, including but not limited to cardiac muscle function, in a manner effective to treat the muscular dystrophy. In other embodiments, the construct is delivered in combination with one or more additional constructs encoding one or more additional therapeutic polypeptides. In such embodiments, the additional therapeutic polypeptide can encode, for example, a microdystrophin. The combination of RNR and microdystrophin can together attack both structural (dystrophin-related) and functional (dATP supply) deficits that contribute to the pathology, thereby more significantly improving muscular function. Where the RNR is driven by a cardiac muscle specific regulatory element or cassette, the benefit in countering cardiomyopathy stemming from muscular dystrophy can be pronounced.
There are several types of muscular dystrophy, including but not limited to: (1) myotonic dystrophies, generally characterized by an inability to relax muscles following contractions; (2) facioscapulohumeral (FSHD) dystrophies, characterized by muscle weakness typically beginning in the face, hip and shoulders, onset of FSHD usually occurs in the teenage years but can begin in childhood or as late as age 50; (3) congenital muscular dystrophy, that affects boys and girls and is apparent at birth or before age 2; and (4) limb-girdle muscular dystrophies, generally characterized by hip and shoulder muscle weakness, difficulty lifting the foot, and frequent tripping. Complications of muscular dystrophy include for example, trouble walking, difficulty using arms or legs, shortening of muscles or tendons, breathing problems, scoliosis, cardiovascular failure and arrhythmias, and swallowing problems.
Duchenne muscular dystrophy (DMD) is a recessively-inherited muscular dystrophy that affects approximately 1 in 3500 males. DMD patients carry a mutation in the dystrophin gene that causes aberrant expression or loss of expression of the dystrophin protein. DMD patients experience progressive wasting of skeletal muscles and cardiac dysfunction, which leads to loss of ambulation and premature death, primarily due to cardiac or respiratory failure.
An absence of dystrophin and reduction in the dystrophoin-glycoprotein complex (DGC) components causes membrane destabilization and permeability defects that lead to myofiber degeneration, repeated cycles of degeneration/regeneration, and the gradual replacement of muscle fibers with fibrotic, connective, and adipose tissue. This effect can lead to decreased systolic and diastolic performance in DMD hearts.
Current available treatments for DMD are generally only able to slow the pathology of DMD (see Emery, A. E. H. and Muntoni, F., Duchenne Muscular Dystrophy, Third Edition (Oxford University Press, 2003)). Gene therapy approaches for DMD have been demonstrated in dystrophic animal models by either directly targeting a class of mutations, as with exon skipping, or replacing the mutated gene with viral-vector mediated delivery (see Koo, T. and Wood, M. J. Human Gene Therapy 24, (2013); Benedetti, S., et al., The FEBS Journal 280, 4263-4280, (2013); and Seto, J. T., et al., Current Gene Therapy 12, 139-151 (2012)). Recombinant adeno-associated virus (rAAV) vectors are a potential vehicle for gene therapy, being already tested in clinical trials for both DMD and limb-girdle muscular dystrophies (see Mendell, J. R., et al., The New England Journal of Medicine 363, 1429-1437, (2010); Mendell, J. R., et al., Annals of Neurology 68, 629-638 (2010); and Herson, S., et al., Brain: A Journal of Neurology 135, 483-492, (2012)). Several serotypes of adeno-associated virus (AAV) demonstrate a high degree of tropism for striated muscles (see Seto, J. T., et al., Current Gene Therapy 12, 139-151 (2012)).
Pre-clinical studies designing and testing newer generations of therapeutic constructs for DMD can be confined by the approximately 4.9 kb size of a single-stranded rAAV vector genome (see Dong, B., et al., Molecular Therapy: The Journal of the American Society of Gene Therapy 18, 87-92, (2010) and Wu, Z., et al., Molecular Therapy: The Journal of the American Society of Gene Therapy 18, 80-86, (2010)). Packaging the entire approximately 13.9 kb cDNA of the muscle-specific isoform of dystrophin into a single rAAV capsid cannot be achieved, accordingly, miniaturized, synthetic versions of the muscle-specific isoform of dystrophin cDNA may be used.
Although in vivo recombination of two and three rAAV vector genomes has been demonstrated to deliver a mini- or full-length dystrophin coding sequence (see, Odom, G. L., et al., Molecular Therapy: The Journal of the American Society of Gene Therapy 19, 36-45, (2011); Lostal, W., et al., Human Gene Therapy, (2014); and Koo, T., et al., Human Gene Therapy 25, 98-108, (2014)), the efficiency of delivering multiple vectors for reconstituting full-length dystrophin may be suboptimal and can increase the overall dose of viral capsid proteins needed for delivering vectors. However, beneficial rAAV-mediated gene therapy has been achieved using rationally-designed miniature versions of the dystrophin cDNA based in part on mRNA expressed in mild Becker muscular dystrophy patients carrying in-frame deletions within the gene (see Beggs, A. H., et al., American Journal of Human Genetics 49, 54-67 (1991); Koenig, M., et al., American Journal of Human Genetics 45, 498-506 (1989); Goldberg, L. R., et al., Annals of Neurology 44, 971-976, (1998); and England, S. B., et al., Nature 343, 180-182 (1990)). Studies in transgenic and vector treated dystrophic mice expressing various dystrophin truncations have identified several elements of the dystrophin gene that need to be present in a functional micro-dystrophin (μDys) (see Harper, S. Q., et al., Nature Medicine 8, 253-261, (2002)). See additional below re: microdystrophins.
The methods provided herein provide a cardiac function-enhancing approach to therapeutically treat muscular dystrophy by targeting myosin in contractile filaments via overexpression of ribonucleotide reductase (RNR) without adverse cardiac remodeling (see, e.g., Kolwicz et al. JACC Vol 4, No 7, 2019, which is incorporated herein by reference in its entirety).
The nucleic acid constructs provided herein affect the cardiac pressure-volume relationship by significantly improving systolic preload response. Accordingly, administration of RNR alone can improve diastolic (at rest) functional parameters of the dystrophic heart in animal models of DMD, a surprisingly beneficial effect of the compositions described herein. This is because current therapeutics targeting cardiovascular complications of DMD only improve structural and/or systolic (contraction) function of the heart and do not necessarily improve diastolic function or cardiovascular energetics. Where most therapies for muscle-related cardiac pathologies focus on improving contraction, a therapeutic approach that improves diastolic function or relaxation can improve the efficiency of the heart because improved relaxation permits a greater volume of blood to enter the chamber before contraction drives it out.
Methods of measuring cardiac function and energetics (e.g., pressure and volume) in a subject include, but are not limited to, echocardiography, magnetocardiogram, and a Langendorff perfusion in a test animal. See also, e.g., Kolwicz S C, Jr. and Tian R. Assessment of cardiac function and energetics in isolated mouse hearts using 31P NMR spectroscopy. J Vis Exp. 2010; 42: e2069.
Given that the RNR increases dATP in the heart, the nucleic acid constructs described herein can be used prophylactically to support cardiac function in subjects with muscular dystrophy and prevent or decrease the severity of cardiovascular complications. As shown in the working examples, RNR overexpression results in elevated dATP, which can be used by cardiac myosin (in place of ATP), and increases cross-bridge binding and cycling, resulting in stronger, faster contraction and faster relaxation in mouse models of DMD.
The full-length striated muscle isoform of dystrophin plays a role in transmitting contractile force through the sarcolemma and out to the extracellular matrix. In addition to maintaining the mechanical link between the intracellular cytoskeleton and the membrane bound dystrophin glycoprotein complex (DGC), dystrophin can also be a scaffold for signaling proteins (see e.g., Ozawa, E. in Myology (ed. Franzini-Armstrong C Engel A) 455-470 (McGraw-Hill, 2004); Winder, S. J. Journal of Muscle Research and Cell Motility 18, 617-629 (1997); and Campbell, K. P. and Kahl, S. D. Nature 338, 259-262, (1989)), which are incorporated herein by reference in their entireties. The amino-terminal domain of dystrophin can bind to F-actin filaments of the intracellular cytoskeleton (see e.g., Way, M., et al., FEBS Letters 301, 243-245 (1992); Hemmings, L., et al., The Journal of Cell Biology 116, 1369-1380 (1992); Fabbrizio, E., et al., Biochemistry 32, 10457-10463 (1993); and Pavalko, F. M. and Otey, C. A. Proceedings of the Society for Experimental Biology and Medicine 205, 282-293 (1994), which are incorporated herein by reference in their entireties). The human dystrophin gene, mRNA and polypeptide sequences is known in the art, see, e.g., SEQ ID NO: 31-33, or a variant thereof.
The middle, rod domain is the largest and is composed of 24 spectrin-like repeats (SRs) that are flanked and interspersed with at least four hinge sub-domains. The rod domain can give dystrophin elasticity and flexibility for maintaining the integrity of the sarcolemma during muscle contractility (see Winder, S. J. Journal of Muscle Research and Cell Motility 18, 617-629 (1997)). Various SRs provide unique regions that can serve as additional binding sites for the intracellular cytoskeleton, the sarcolemma, as well as members of the DGC (see Rybakova, I. N., et al., The Journal of Cell Biology 135, 661-672 (1996); Warner, L. E., et al., Human Molecular Genetics 11, 1095-1105 (2002); Metzinger, L., et al., Human Molecular Genetics 6, 1185-1191 (1997); Lai, Y., et al., The Journal of Clinical Investigation 119, 624-635, (2009)). In particular, the cysteine-rich domain and the adjacent Hinge 4 region form the (3-dystroglycan binding domain (Dg BD) (see Blake, D. J., et al., Physiological Reviews 82, 291-329, (2002); Ishikawa-Sakurai, M., et al., Human Molecular Genetics 13, 693-702, (2004)), while the carboxy-terminal domain is a scaffold for additional DGC components (see Abmayr S, in Molecular Mechanisms of Muscular Dystrophies (ed. Winder, S. J.) 14-34 (Landes Biosciences, 2006)).
Partially functional micro-dystrophins can improve the dystrophic pathology in striated muscle by protecting the sarcolemma from contraction-induced injury and increasing the capacity to generate force. These parameters can be achieved by binding to F-actin filaments and β-dystroglycan through the amino-terminal domain and the Dg BD (see Harper, S. Q., et al., Nature Medicine 8, 253-261, (2002); Warner, L. E., et al., Human Molecular Genetics 11, 1095-1105 (2002); Cox, G. A., et al., Nature Genetics 8, 333-339, (1994); Greenberg, D. S., et al., Nature Genetics 8, 340-344, (1994); Gardner, K. L., et al., Gene Therapy 13, 744-751, (2006); Corrado, K., et al., The Journal of Cell Biology 134, 873-884 (1996); and Rafael, J. A., et al., The Journal of Cell Biology 134, 93-102 (1996)). Without being bound by any one particular theory, prior studies indicate these two domains must be connected by at least four SRs from the central rod domain, but there are numerous ways in which miniaturized dystrophins containing at least four SRs can be constructed. While some combinations of SRs have been shown to improve the dystrophic pathophysiology, other combinations have not yielded proteins with significant functional capacity (see Harper, S. Q., et al., Nature Medicine 8, 253-261, (2002) and Abmayr S, in Molecular Mechanisms of Muscular Dystrophies (ed. Winder, S. J.) 14-34 (Landes Biosciences, 2006)). Selection of specific SRs in μDys design can restore additional DGC components to the sarcolemma. Neuronal nitric oxide synthase (nNOS) is a signaling protein that can be involved in vasodilation in response to muscle contractile activity (see Stamler, J. S. and Meissner, G. Physiological Reviews 81, 209-237 (2001); Brenman, J. E., et al., Cell 82, 743-752 (1995); Kobayashi, Y. M., et al., Nature 456, 511-515, (2008); and Torelli, S., et al., Neuropathology and Applied Neurobiology 30, 540-545, (2004)), and the presence of SRs 16 and 17 can be involved in proper association of nNOS with the DGC (see 28 Lai, Y. et al., The Journal of Clinical Investigation 119, 624-635, (2009) and Lai, Y., et al., Proceedings of the National Academy of Sciences of the United States of America 110, 525-530, (2013)).
Sequences within spectrin-like repeats 20-24 as well as Hinge 4 can play a role in proper association of dystrophin with microtubules, which can be important for maintaining the intracellular architecture and torque production in skeletal muscle (see Prins, K. W. et al., The Journal of Cell Biology 186, 363-369, (2009) and Belanto, J. J., et al., Proceedings of the National Academy of Sciences of the United States of America 111, 5723-5728, (2014)). Nonetheless, the carboxy-terminal domain and most of the SR domains have been found dispensable without severely compromising the health of striated muscles (see McCabe, E. R., et al., The Journal of Clinical Investigation 83, 95-99, (1989); Crawford, G. E., et al., The Journal of Cell Biology 150, 1399-1410 (2000); and Dunckley, M. G., et al., FEBS Letters 296, 128-134 (1992)).
Any micro-dystrophin (referred to herein as μDys or mDys) known in the art can be administered in combination with the RNR constructs described herein. By way of example only, the RNR constructs described herein can be administered in combination with any of the micro-dystrophins described in Ramos et al. “Development of novel micro-dystrophins with enhanced functionality.” Mol Ther 2019; 27:623-635; (2019) and/or the micro-dystrophins described in U.S. Pat. No. 10,479,821 B2, the contents of each of which is incorporated herein by reference in their entirety. In some embodiments, the micro-dystrophin comprises amino sequence SEQ ID NO: 34, a nucleic acid encoding SEQ ID NO: 34, a fragment, or a variant thereof.
Ribonucleotide reductase (RNR), also known as ribonucleotide diphosphate reductase (rNDP), is an enzyme that catalyzes the reaction of ribonucleotides to deoxyribonucleotides, which are essential components in the synthesis of DNA. RNR is conserved in all living organisms. The RNR enzyme catalyzes the de novo synthesis of dNDPs. Catalysis of ribonucleoside 5′-diphosphates (NDPs) involves a reduction at the 2′-carbon of ribose 5-phosphate to form the 2′-deoxy derivative-reduced 2′-deoxyribonucleoside 5′-diphosphates (dNDPs). This reduction is initiated with the generation of a free radical. Following a single reduction, RNR requires electrons donated from the dithiol groups of the protein thioredoxin, which is regenerated via NADPH mediated reduction of disulfide groups of thioredoxin.
Three classes of RNR have similar mechanisms for the reduction of NDPs. All classes use free-radical chemistry. Class I reductases use an iron center with ferrous to ferric conversion to generate a tyrosyl free radical. Reduction of NDP substrates occurs under aerobic conditions. Class I reductases are divided into IA and IB due to differences in regulation. Class IA reductases are distributed in eukaryotes, eubacteria, bacteriophages, and viruses. Class IB reductases are found in eubacteria. Class IB reductases can also use a radical generated with the stabilization of a binuclear manganese center. Class II reductases generate the free radical 5′-deoxyadenosyl radical from cobalamin (coenzyme B12) and have a simpler structure than class I and class III reductases. Reduction of NDPs or ribonucleotide 5′-triphosphates (NTPs) occurs under either aerobic or anaerobic conditions. Class II reductases are distributed in archaebacteria, eubacteria, and bacteriophages. Class III reductases use a glycine radical generated with the help of an S-adenosyl methionine and an iron sulphur center. Reduction of NTPs is limited to anaerobic conditions. Class III reductases are distributed in archaebacteria, eubacteria, and bacteriophages. Organisms are not limited to having one class of enzymes. For example, E. coli have both class I and class III RNR. The RNR complex consists of two subunits—RRM1 and RRM2. The larger RRM1 subunit contains the catalytic site and 2 allosteric sites that can bind dATP, whereas the smaller RRM2 subunit contains the free radical generator. The RNR complex is tightly allosterically regulated, with ≤5% of the ATP pool present as dATP. Each RNR1 monomer consists of three domains: (1) one mainly helical domain comprising the 220 N-terminal residues; (2) a second large ten-stranded α/β structure comprising 480 residues; and (3) a third small five-stranded α/β structure comprising 70 residues.
As used herein, “RRM1” or “ribonucleotide reductase catalytic subunit M1” or “an RRM1 construct” refers to the large, catalytic site containing, subunit of the RNR complex. Sequences for RRM1 are known for a number of species, e.g., human RRM1 (NCBI Gene ID: 6240) mRNA (NCBI Ref Seq: NM_001033.5) and polypeptide (NCBI Ref Seq: NP_001024.1). In some embodiments of any of the aspects, the RRM1 nucleic acid or polypeptide can be an isoform, ortholog, variant, and/or allele of SEQ ID NO: 1-SEQ ID NO: 12, respectively.
As used herein, “RRM2” or “ribonucleotide reductase catalytic subunit M2” or an “RRM2 construct” refers to the small subunit of the RNR complex. Sequences for RRM2 are known for a number of species, e.g., human RRM2 (NCBI Gene ID: 6241) mRNA (NCBI Ref Seq: NM_001034.4) and polypeptide (NCBI Ref Seq: NP_001025.1). In some embodiments of any of the aspects, the RRM2 nucleic acid or polypeptide can be an isoform, ortholog, variant, and/or allele of SEQ ID NO: 13-SEQ ID NO: 24, respectively. RRM1 and RRM2 proteins as described herein need to be capable of forming an active RNR complex. Brignole et al., eLife 2018; 7:e31502, which is incorporated herein by reference, describes a 3.3A resolution cryo-EM structure of human ribonucleotide reductase complexed with substrate and allosteric regulators (ATP and dATP)—this near-atomic resolution structure illustrates amino acids and structural domains in the two subunits that interact with each other and illustrates domains necessary for allosteric regulation.
One aspect described employs expression of an RNR complex comprising, consisting of, or consisting essentially of, wild type RRM1 and RRM2 proteins. As used herein, “RNR complex” refers to an RRM1 polypeptide and an RRM2 polypeptide in physical association with each other in the form that provides RNR activity. In this context, the RRM1 and/or RRM2 polypeptide can be a variant that differs in one or more amino acids from the wild-type yet retains the ability to complex with the respective RRM subunit and to catalyze the generation of dATP. One skilled in the art can assess whether the RNR complex is formed, for example, by sucrose gradient analysis or co-immunoprecipitation under non-denaturing conditions. In certain embodiments, it is contemplated that a variant of either or both of RRM1 and/or RRM2 is delivered in one or more therapeutic constructs. Variants include, for example, versions of either or both polypeptides that are rendered more stable, e.g., by modification of a cleavage substrate site for one or more degrading enzymes. Examples are described, for example in U.S. Ser. No. 16/457,441, which is incorporated herein by reference. The increased stability of, e.g., the RRM2 subunit can provide increased activity of the RNR complex.
Where it is important to maintain the function of a variant polypeptide, i.e., complex formation of a mutant RRM2 with RRM1 and/or ribonucleotide reductase activity in complex with RRM1, it can be beneficial to modify a site or sites via conservative amino acid substitution(s). In a conservative substitution, a given amino acid can be replaced by a residue having similar physicochemical characteristics, e.g., substituting one aliphatic residue for another (such as Ile, Val, Leu, or Ala for one another), or substitution of one polar residue for another (such as between Lys and Arg; Glu and Asp; or Gln and Asn). Other such conservative substitutions, e.g., substitutions of entire regions having similar hydrophobicity characteristics, are well known. Polypeptides comprising conservative amino acid substitutions can be tested in any one of the assays described herein to confirm that a desired activity, e.g., complex formation with Rrm1 and/or ribonucleotide reductase activity for the Rrm1/Rrm2 mutant polypeptide complex is retained.
Amino acids can be grouped according to similarities in the properties of their side chains (in A. L. Lehninger, in Biochemistry, second ed., pp. 73-75, Worth Publishers, New York (1975)): (1) non-polar: Ala (A), Val (V), Leu (L), Ile (I), Pro (P), Phe (F), Trp (W), Met (M); (2) uncharged polar: Gly (G), Ser (S), Thr (T), Cys (C), Tyr (Y), Asn (N), Gln (Q); (3) acidic: Asp (D), Glu (E); (4) basic: Lys (K), Arg (R), His (H). Alternatively, naturally occurring residues can be divided into groups based on common side-chain properties: (1) hydrophobic: Norleucine, Met, Ala, Val, Leu, Ile; (2) neutral hydrophilic: Cys, Ser, Thr, Asn, Gln; (3) acidic: Asp, Glu; (4) basic: His, Lys, Arg; (5) residues that influence chain orientation: Gly, Pro; (6) aromatic: Trp, Tyr, Phe. Non-conservative substitutions will entail exchanging a member of one of these classes for another class. Particular conservative substitutions include, for example; Ala into Gly or into Ser; Arg into Lys; Asn into Gln or into His; Asp into Glu; Cys into Ser; Gln into Asn; Glu into Asp; Gly into Ala or into Pro; His into Asn or into Gln; Ile into Leu or into Val; Leu into Ile or into Val; Lys into Arg, into Gln or into Glu; Met into Leu, into Tyr or into Ile; Phe into Met, into Leu or into Tyr; Ser into Thr; Thr into Ser; Trp into Tyr; Tyr into Trp; and/or Phe into Val, into Ile or into Leu.
In the various embodiments described herein, it is further contemplated that variants (naturally occurring or otherwise), alleles, homologs, conservatively modified variants, and/or conservative substitution variants of any of the particular polypeptides described are encompassed. As to amino acid sequences, one of ordinary skill will recognize that individual substitutions, deletions or additions to a nucleic acid, peptide, polypeptide, or protein sequence which alters a single amino acid or a small percentage of amino acids in the encoded sequence is a “conservatively modified variant” where the alteration results in the substitution of an amino acid with a chemically similar amino acid and retains the desired activity of the polypeptide. Such conservatively modified variants are in addition to and do not exclude polymorphic variants, interspecies homologs, and alleles consistent with the disclosure. Indeed, it can be helpful in determining whether a given region of a polypeptide is likely to tolerate mutation, whether conservative or not, by alignment of the polypeptide's sequence from one species, e.g., human, with the sequence of one or more homologous polypeptides from other species, e.g., the sequences of the homologous polypeptide from one or more of rat, mouse, chicken, bovine, porcine or other species in order to determine which regions of the polypeptide molecule are more highly conserved than others throughout evolution. Indeed, it can also help, for a polypeptide connected to a process as centrally important as dATP production, to consider alignments with Rrm2 sequences from more distantly-related eukaryotes, such as fish, reptiles or others. Those regions more highly conserved are more likely to be important for function, meaning that if a ubiquitination site occurs in such region, care should be taken when choosing mutations to introduce so as not to overly interfere with enzymatic function. In such instances, it can be helpful to try several different conservative substitutions at a chosen site—if the change is not marked enough to interfere sufficiently with ubiquitination, no benefit would be expected for such mutant, but a more dramatic change is more likely to interfere with other function(s) of the polypeptide. On the other hand, if a ubiquitination site or ubiquitin-binding degron occurs in a less conserved region of the polypeptide, the polypeptide may well tolerate substitution with one or more non-conservative amino acids to interfere with ubiquitination, as well as tolerating conservative substitution(s).
In some embodiments, a polypeptide described herein (or a nucleic acid encoding such a polypeptide) can be a functional fragment of one of the polypeptides described herein, e.g., a functional fragment of an RRM2 polypeptide. As used herein, a “functional fragment” is a fragment or segment of a peptide which retains at least 50% of the wildtype reference polypeptide's activity according to an assay known in the art or described below herein. For example, a functional fragment described herein would retain at least 50% of the RRM2 function, e.g., can form a complex with Rrm1 and together catalyze the reaction(s) catalyzed by RNR. One skilled in the art can assess the function of an RRM2 enzyme using standard techniques, for example those described herein below. A functional fragment can comprise conservative substitutions of the sequences disclosed herein.
Conservative substitution variants can be obtained by mutations of native nucleotide sequences, for example. A “variant,” as referred to herein, is a polypeptide substantially homologous to a native or reference polypeptide, but which has an amino acid sequence different from that of the native or reference polypeptide because of one or a plurality of deletions, insertions or substitutions. Variant polypeptide-encoding DNA sequences encompass sequences that comprise one or more additions, deletions, or substitutions of nucleotides when compared to a native or reference DNA sequence, but that encode a variant protein or fragment thereof that retains activity of the non-variant polypeptide. A wide variety of PCR-based site-specific mutagenesis approaches are known in the art and can be applied by the ordinarily skilled artisan.
A variant amino acid or DNA sequence can be at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or more, identical to a native or reference sequence. The degree of homology (percent identity) between a native and a mutant or other reference (e.g., homologue, variant, etc.) sequence can be determined, for example, by comparing the two sequences using freely available computer programs commonly employed for this purpose on the world wide web (e.g. BLASTp or BLASTn with default settings).
Alterations of the native amino acid sequence can be accomplished by any of a number of techniques known to one of skill in the art. Mutations can be introduced, for example, at particular loci by synthesizing oligonucleotides containing a mutant sequence, flanked by restriction sites permitting ligation to fragments of the native sequence. Following ligation, the resulting reconstructed sequence encodes an analog having the desired amino acid insertion, substitution, or deletion. Alternatively, oligonucleotide-directed site-specific mutagenesis procedures can be employed to provide an altered nucleotide sequence having particular codons altered according to the substitution, deletion, or insertion required. Techniques for making such alterations are well established and include, for example, those disclosed by Walder et al. (Gene 42:133, 1986); Bauer et al. (Gene 37:73, 1985); Craik (BioTechniques, January 1985, 12-19); Smith et al. (Genetic Engineering: Principles and Methods, Plenum Press, 1981); and U.S. Pat. Nos. 4,518,584 and 4,737,462, which are herein incorporated by reference in their entireties. Any cysteine residue not involved in maintaining the proper conformation of a polypeptide also can be substituted, generally with serine, to improve the oxidative stability of the molecule and prevent aberrant crosslinking. Conversely, cysteine bond(s) can be added to a polypeptide to improve its stability or facilitate oligomerization.
The compositions and methods described herein comprise a first pharmaceutical composition comprising an RRM1 gene operably linked to a regulatory cassette. In another aspect, the compositions and methods described herein comprise a first pharmaceutical composition comprising an RRM1-encoding gene sequence and an RRM2-encoding gene sequence operably coupled to a first regulatory cassette. It is preferred, but not absolutely necessary, that the gene sequences encoding RRM1 and RRM2 are encoded on a single construct—this arrangement provides for closer management of the stoichiometry of the two subunits of the active enzyme complex. However, in another aspect, the methods and compositions can comprise a first pharmaceutical composition comprising an RRM1 gene operably coupled to a first regulatory cassette in a first delivery vehicle, and a second pharmaceutical composition comprising an RRM2 gene operably coupled to a second regulatory cassette in a second delivery vehicle. It is also contemplated that delivery of just the catalytic subunit of RNR can be overexpressed as a way to increase cellular dATP overall; in this approach, the overexpression of RRM2 can balance the natural degradation of naturally-encoded RRM2, thereby leading to a higher level of RNR activity overall.
In one embodiment of any of the aspects described herein, variant RRM1 and/or RRM2 polypeptides and/or RNR complex provided herein comprise the same enzymatic function of a wild-type RRM1 and/or RNR complex, for example, catalyzing the formation of deoxyribonucleotides from ribonucleotides. Assays for assessing the enzymatic function of a complex provided herein include, but are not limited to nucleotide binding assays, for example, as described in Chimploy, K., and Mathews, C K. J of Biol Chem, 2001; Hendricks, S P, and Mathews C K. J of Biol Chem, 1997; and Hendricks, S P, and Mathews C K. J of Biol Chem, 1998; see also the ribonucleotide reductase assay described by Jong et al., J. Biomed. Sci. 5: 62-68 (1998), the content of each of which are incorporated herein by reference in their entireties.
In another embodiment of any of the aspects, the RRM2 and RRM1-encoding nucleic acids are encoded on the same vector, delivery vehicle, and/or under the control of the same promoter.
In some embodiments of any of the aspects, the RRM1 or RRM2 comprises a mutation that prevents ubiquitination. Mutations found within the ubiquitin binding domain (i.e., the site of ubiquitin addition or ubiquitination) of RRM2 are shown, e.g., in U.S. Ser. No. 16/457,441 to decrease ubiquitination of RRM2, increase RRM2 stability (e.g., half-life of RRM2), and result in increased dATP in the cell. Accordingly, provided herein is an isolated nucleic acid molecule encoding an RRM2 polypeptide that, together with RRM1 polypeptide comprises ribonucleotide reductase activity, the encoded RRM2 polypeptide comprising a mutation that increases the intracellular level of the polypeptide as compared to wild-type RRM2 polypeptide. In one embodiment, the mutation is in a ubiquitin binding degron of RRM2. In another embodiment, the ubiquitin binding degrons of RRM2 are found at nucleotides 88-96 (which encode amino acids that can associate with the APC/FZR1 proteasome) and nucleotides 97-99 and 145-153 (which can associate with the SCF/CyclinF proteasome) of wild-type RRM2 (SEQ ID NO: 13). In another embodiment, the ubiquitin binding degrons of RRM2 are found at amino acids 30-32 (which can associate with the APC/FZR1 proteasome) and amino acids 33 and 49-51 (which can associate with the SCF/CyclinF proteasome) of wild-type RRM2 (SEQ ID NO: 13).
A mutation described herein can be an amino acid substitution, deletion, or insertion. It is contemplated herein that a mutation can be any amino acid change within the ubiquitin binding domain that results in at least decreased ubiquitination of RRM2, increased stability of RRM2, and/or increased dATP levels in the cell. Considerations for mutating a ubiquitination site while maintaining RRM2 activity in terms of complex formation and ribonucleotide reductase activity with RRM1 are discussed herein above. In some embodiments, the mutation is found near a ubiquitin binding degron, e.g., within 1-10 nucleotides of a ubiquitin binding degron, i.e., nucleotides not encoding a ubiquitin binding degron. In some embodiments, the mutation is found near a ubiquitin binding degron, e.g., within 1-10 amino acids of a ubiquitin binding degron, i.e., amino acids not encoding a ubiquitin binding degron.
Alterations of the native amino acid sequence (e.g., of RRM1 or RRM2) can be accomplished by any of a number of techniques known in the art. Mutations can be introduced, for example, at particular loci by synthesizing oligonucleotides containing a mutant sequence, flanked by restriction sites permitting ligation to fragments of the native sequence. Following ligation, the resulting reconstructed sequence encodes an analog having the desired amino acid insertion, substitution, or deletion. Alternatively, oligonucleotide-directed site-specific mutagenesis procedures can be employed to provide an altered nucleotide sequence having particular codons altered according to the substitution, deletion, or insertion required. Techniques for making such alterations are well established and include, for example, those disclosed by Walder et al. (Gene 42:133, 1986); Bauer et al. (Gene 37:73, 1985); Craik (BioTechniques, January 1985, 12-19); Smith et al. (Genetic Engineering: Principles and Methods, Plenum Press, 1981); and U.S. Pat. Nos. 4,518,584 and 4,737,462, which are herein incorporated by reference in their entireties. Assays for detecting the stability and/or degradation of a protein are known in the art, and include, treating a cell lysate or an in vitro system having the protein of interest and components of the ubiquitin mediated degradation system with cyclohexamide to halt protein translation and measuring the level of the protein of interest over time (e.g., in a time course) via Western blotting. Alternatively, protein stability can be measured using a standard pulse-chase experiment.
The RNR described herein are expressed as a fusion protein in which the RRM1 and RRM2 polypeptides are joined by a linker peptide. The constructs described herein can thus further comprise a linker. Linkers can be configured according to a specific need, e.g., to have a sufficient length and flexibility such that it can allow for a cleavage at a target site. Methods of synthesizing fusion proteins and linkers are known in the art.
In some embodiments of any of the aspects, the RRM2-encoding nucleic acid is linked to the RRM1-encoding nucleic acid, e.g., through a type 2A peptide-encoding sequence, such as P2A. P2A is a non-limiting example of a 2A self-cleaving peptide, which can induce the cleavage of the recombinant protein when expressed in a cell. See, e.g., Kolwicz et al., Molecular Therapy 24: 240-250 (2016), which is incorporated herein by reference in its entirety. Non-limiting examples of 2A self-cleaving peptides include T2A, P2A, E2A, and F2A. Any self-cleaving peptide sequence known in the art can be used to link RRM1 to RRM2.
The RRM1, RRM2 and/or micro-dystrophin-coding sequences for the constructs described herein can be operably coupled to a regulatory cassette.
A regulatory cassette directs the expression of a gene (e.g., RRM1, RRM2, μDys). A regulatory cassette generally comprises a promoter element and other sequences necessary to direct the assembly of an active transcriptase complex in a desired cell type. A regulatory cassette can also include, for example, a 3′ untranslated sequence including a polyadenylation signal downstream of the region where an open reading frame encoding the desired polypeptide is or can be inserted. Exemplary promoters that can be used include, but are not limited to, constitutive promoters, repressible promoters, and/or inducible promoters, some non-limiting examples of which include viral promoters (e.g., CMV, SV40), tissue specific promoters (e.g., striated muscle CK8), cardiac muscle (e.g., cTnT), eye (e.g., MSK) and synthetic promoters (SP1 elements) and the chicken beta actin promoter (CB or CBA).
In some embodiments, the regulatory cassette can be positioned at the 5′ end of the RRM1, RRM2, or the micro-dystrophin described herein. In others, the cassette flanks the sequence to be encoded.
In some embodiments of any of the aspects, the regulatory cassette is a muscle-specific regulatory cassette. Exemplary muscle-specific regulatory cassettes include, but are not limited to, a cardiac troponin T (cTNT) regulatory cassette; a creatine kinase regulatory cassette; a muscle creatine kinase (MCK) regulatory cassette; a CK8 regulatory cassette; a MHCK7 regulatory cassette; CK7 regulatory cassette; and any fragment or combinations thereof. The nucleic acid constructs described herein can be prepared by synthetic and/or cloning methods known in the art.
In some embodiments of any of the aspects, the pharmaceutical compositions described herein includes a CK8 regulatory cassette. In some embodiments, the CK8 regulatory cassette has at least 80% sequence identity to the nucleic acid sequence of SEQ ID NO: 29.
The CK8 regulatory cassette can display strong, muscle-restricted expression. The CK8 regulatory cassette is less than 500 bps in size (see, e.g., Goncalves, M. A., et al., Molecular Therapy: The Journal of the American Society of Gene Therapy 19, 1331-1341, (2011) and Martari, M., et al., Human Gene Therapy 20, 759-766, (2009), which are incorporated herein by reference in its entirety.
In some embodiments of any of the aspects, the pharmaceutical compositions described herein includes a cTNT regulator cassette. In some embodiments, the cTNT regulatory cassette has at least 80% sequence identity to the nucleic acid sequence of SEQ ID NO: 30.
The human cTnT455 regulatory cassette (SEQ ID NO: 30) targets the transient expression of the pharmaceutical composition in wounded and/or regenerating cardiac muscle. cTnT455 can lead to high expression in the heart but little to no expression in other tissue. In some embodiments, expression of the pharmaceutical compositions disclosed herein prevents the loss of cardiac muscle and/or of cardiomyocytes. In some embodiments, expression of the pharmaceutical compositions disclosed herein regenerate skeletal muscle. In some embodiments, expression of the pharmaceutical compositions disclosed herein prevent muscle cell necrosis and/or wasting of skeletal muscle.
The methods and compositions described herein involve the introduction of sequences encoding therapeutic polypeptides to muscle cells in vivo, including, for example, cardiac muscle cells, among others. These methods permit practitioners to introduce DNA coding for a therapeutic polypeptide directly into a patient or subject (in vivo gene therapy) or into cells isolated from a patient, a subject, or a donor (ex vivo gene therapy). The introduced DNA then directs the patient's or subject's own cells or grafted cells to produce the desired protein product. Gene therapy can also permit practitioners to select specific organs or cellular targets (e.g., muscle, liver, blood cells, brain cells, etc.) for therapy. Sequences to be introduced to cells in vivo (or ex vivo, for that matter) can be cloned into an appropriate vector. Examples of mammalian expression vectors include pCDM8 (Seed, 1987. Nature 329: 840) and pMT2PC (Kaufman, et al., 1987. EMBO J. 6: 187-195), and are further described in, e.g., U.S. Pat. Nos. 8,187,836; 8,455,219; 8,980,626; 7,384,776; and 6,451,539; the contents of which are incorporated herein by reference in their entireties. When used in mammalian cells, the expression vector's control functions are typically provided by one or more regulatory elements. For example, commonly used promoters are derived from polyoma, adenovirus 2, cytomegalovirus, simian virus 40, and others disclosed herein and known in the art. For other suitable expression systems for both prokaryotic and eukaryotic cells see, e.g., Chapters 16 and 17 of Sambrook, et al., MOLECULAR CLONING: A LABORATORY MANUAL. 2nd ed., Cold Spring Harbor Laboratory, Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y., 1989; and Muller, D., et al. (2006) Microbial Cell Factories.
In some embodiments, the recombinant mammalian expression vector is capable of directing expression of the synthetic nucleic acid preferentially in a particular cell type (e.g., tissue-specific regulatory elements are used to express the nucleic acid in, for example, a cardiomyocyte). Tissue-specific regulatory elements are known in the art. Non-limiting examples of suitable cardiac tissue-specific promoters include the cTnT promoter, the NCX1 promoter (e.g., as described in Nicholas S B., et al. Am J Physiol. 1998), the MLC-2v (e.g., as described Griscelli, F., et al. C R Acad Sci III. 1997 February; 320(2):103-12); and the cardiac troponin-I proximal promoter (TNNI3) (e.g., as described in Gallo, P., et al. Gene Therapy. 15, pages 161-170 (2008). All citations provided herein are incorporated herein by reference in their entireties. The CK8 promoter described elsewhere herein is an example of a striated muscle-specific promoter.
The RRM1 and RRM2 constructs described herein can be administered to a subject in need in one vector, or in two vectors or delivery vehicles. In some embodiments of any of the aspects, a first delivery vehicle and a second delivery vehicle are separate delivery vehicles. In some embodiments of any of the aspects, the delivery vehicle is a viral vector.
Current viral-mediated gene delivery methods include, but are not limited to, retrovirus, adenovirus, herpes virus, pox virus, and adeno-associated virus (AAV) vectors.
AAV is a parvovirus which belongs to the genus Dependoparvovirus. AAV has several attractive features not found in other viruses. First, AAV can infect a wide range of host cells, including non-dividing cells. Second, AAV can infect cells from different species. Third, AAV has not been associated with any human or animal disease and does not appear to alter the biological properties of the host cell upon integration. Indeed, it is estimated that 80-85% of the human population has been exposed to the virus. Finally, AAV is stable at a wide range of physical and chemical conditions which lends itself to production, storage, and transportation requirements.
The AAV genome is a linear, single-stranded DNA molecule containing 4681 nucleotides. The AAV genome generally comprises an internal non-repeating genome flanked on each end by inverted terminal repeats (ITRs). The ITRs are approximately 145 base pairs (bp) in length. The ITRs have multiple functions, including as origins of DNA replication and as packaging signals for the viral genome.
The internal non-repeated portion of the genome includes two large open reading frames, known as the AAV replication (rep) and capsid (cap) genes. The rep and cap genes code for viral proteins that allow the virus to replicate and package the viral genome into a virion. In particular, a family of at least four viral proteins are expressed from the AAV rep region, Rep78, Rep68, Rep52, and Rep40, named according to their apparent molecular weight. The AAV cap region encodes at least three proteins, VP1, VP2, and VP3.
AAV is a helper-dependent virus; that is, it requires co-infection with a helper virus (e.g., adenovirus, herpesvirus, or vaccinia) in order to form AAV virions. In the absence of co-infection with a helper virus, AAV establishes a latent state in which the viral genome inserts into a host cell chromosome, but infectious virions are not produced. Subsequent infection by a helper virus “rescues” the integrated genome, allowing it to replicate and package its genome into infectious AAV virions. While AAV can infect cells from different species, the helper virus must be of the same species as the host cell. Thus, for example, human AAV will replicate in canine cells co-infected with a canine adenovirus.
An “AAV vector” comprises a vector derived from an adeno-associated virus serotype, including without limitation, AAV1, AAV2, AAV3, AAV4, AAV5, AAV6, AAV7, AAV8, and AAV9. AAV vectors can have one or more of the AAV wild-type genes deleted in whole or part, e.g., the rep and/or cap genes, but retain functional flanking ITR sequences. Functional ITR sequences are necessary for the rescue, replication, and packaging of the AAV virion. Thus, an AAV vector is defined herein to include at least those sequences required in cis for replication and packaging (e.g., functional ITRs) of the virus. The ITRs need not be the wild-type nucleotide sequences, and may be altered, e.g., by the insertion, deletion or substitution of nucleotides, so long as the sequences provide for functional rescue, replication and packaging.
A “recombinant AAV vector” or “rAAV vector” comprises an infectious, replication-defective virus composed of an AAV protein shell encapsulating a heterologous nucleotide sequence of interest that is flanked on both sides by AAV ITRs. An rAAV vector is produced in a suitable host cell comprising an AAV vector, AAV helper functions, and accessory functions. In this manner, the host cell is rendered capable of encoding AAV polypeptides that are required for packaging the AAV vector (containing a recombinant nucleotide sequence of interest) into infectious recombinant virion particles for subsequent gene delivery.
In various embodiments, the delivery vehicle may comprise an adeno-associated virus (AAV) vector or a recombinant adeno-associated virus (rAAV) vector. The AAV vector may be a serotype 6 AAV (AAV6). Likewise, the rAAV vector may be a serotype 6 rAAV (rAAV6). The AAV vector may be a serotype 8 AAV (AAV8). Likewise, the rAAV vector may be a serotype 8 rAAV (rAAV8). The AAV vector may be a serotype 9 AAV (AAV9). Likewise, the rAAV vector may be a serotype 9 rAAV (rAAV9). The rAAV vector may be comprised of AAV2 genomic inverted terminal repeat (ITR) sequences pseudotyped with capsid proteins derived from AAV serotype 6 (rAAV2/6). Other suitable serotypes of the AAV or rAAV known in the art can be used. AAV6 is particularly attractive due to efficient infection and transduction of muscle cells, including cardiac muscle cells.
One aspect provided herein is a pharmaceutical composition comprising, consisting of, or consisting essentially of any of the isolated nucleic acids, vectors, polypeptides, or RNR complexes described herein. As used herein, the term “pharmaceutical composition” refers to the active agent in combination with a pharmaceutically acceptable carrier e.g., a carrier commonly used in the pharmaceutical industry.
For clinical use of the methods and compositions described herein, administration of the RRM1, RRM2, and/or micro-dystrophin constructs described herein can include formulation into pharmaceutical compositions or pharmaceutical formulations for parenteral administration, e.g., intravenous; muscular e.g., intramuscular or intracardiac delivery; or other mode of administration. In some embodiments, the nucleic acid compositions described herein can be administered along with any pharmaceutically acceptable carrier compound, material, or composition which results in an effective treatment in the subject. Thus, a pharmaceutical formulation for use in the methods described herein can contain the RRM1 and/or RRM2 genes in combination with one or more pharmaceutically acceptable ingredients. The phrase “pharmaceutically acceptable” refers to those compounds, materials, compositions, and/or dosage forms which are, within the scope of sound medical judgment, suitable for use in contact with the tissues of human beings and animals without excessive toxicity, irritation, allergic response, or other problem or complication, commensurate with a reasonable benefit/risk ratio. The phrase “pharmaceutically acceptable carrier” as used herein means a pharmaceutically acceptable material, composition or vehicle, such as a liquid or solid filler, diluent, excipient, solvent, media, encapsulating material, or solvent encapsulating material, involved in maintaining the stability, solubility, or activity of, a nucleic acid or viral vector construct as described herein. Each carrier must be “acceptable” in the sense of being compatible with the other ingredients of the formulation and not injurious to the patient. The terms “excipient,” “carrier,” “pharmaceutically acceptable carrier” or the like are used interchangeably herein.
Suitable excipients are, for example, water, saline, dextrose, glycerol, ethanol or the like and combinations thereof. In addition, if desired, the composition can contain minor amounts of auxiliary substances such as pH buffering agents and the like which enhance the effectiveness of the active ingredient. The therapeutic composition of the present technology can include pharmaceutically acceptable salts of the components therein. Pharmaceutically acceptable salts include the acid addition salts (formed with the free amino groups of the polypeptide) that are formed with inorganic acids such as, for example, hydrochloric or phosphoric acids, or such organic acids as acetic, tartaric, mandelic and the like. Salts formed with the free carboxyl groups can also be derived from inorganic bases such as, for example, sodium, potassium, ammonium, calcium or ferric hydroxides, and such organic bases as isopropylamine, trimethylamine, 2-ethylamino ethanol, histidine, procaine and the like. Physiologically tolerable carriers are well known in the art. Exemplary liquid carriers are sterile aqueous solutions that contain no materials in addition to the active ingredients and water, or contain a buffer such as sodium phosphate at physiological pH value, physiological saline or both, such as phosphate-buffered saline. Still further, aqueous carriers can contain more than one buffer salt, as well as salts such as sodium and potassium chlorides, dextrose, polyethylene glycol and other solutes. Liquid compositions can also contain liquid phases in addition to and to the exclusion of water. Exemplary of such additional liquid phases are glycerin, vegetable oils such as cottonseed oil, and water-oil emulsions. The amount of an active agent used with the methods described herein that will be effective in the treatment of a particular disorder or condition will depend on the nature of the disorder or condition, and can be determined by standard clinical techniques.
Therapeutic pharmaceutical compositions described herein can also contain more than one active compound as necessary for the particular indication being treated, preferably those with complementary activities that do not adversely affect each other.
The RNR constructs and pharmaceutical compositions described herein can be formulated, dosed, and administered in a fashion consistent with good medical practice. Factors for consideration in this context include the particular muscular dystrophy or complication being treated, the particular subject being treated, the clinical condition of the individual subject, the cause of the disorder, the site of delivery of the pharmaceutical composition, the method of administration, the scheduling of administration, and other factors known to medical practitioners.
The therapeutic formulations to be used for in vivo administration, such as parenteral administration, in the methods described herein can be sterile, which is readily accomplished by filtration through sterile filtration membranes, or other methods known to those of skill in the art.
The RNR construct described herein and pharmaceutical compositions thereof can be administered to a subject in need thereof by any appropriate route which results in an effective treatment in the subject. As used herein, the terms “administering,” and “introducing” are used interchangeably and refer to the placement of a pharmaceutical composition, RRM1, RRM2, RNR, and/or micro-dystrophin construct, into a subject by a method or route which results in at least partial localization of such pharmaceutical compositions at a desired site, such that a desired effect(s) is produced. A pharmaceutical composition can be administered to a subject by any mode of administration that delivers the nucleic acid constructs systemically or to a desired surface or target, and can include, but is not limited to, injection, infusion, instillation, and inhalation administration. To the extent that RRM1, RRM2, and/or micro-dystrophin constructs described herein can be protected from inactivation in the gut, oral administration forms are also contemplated. “Injection” includes, without limitation, intravenous, intramuscular, intra-arterial, intrathecal, intraventricular, intracapsular, intraorbital, intracardiac, intradermal, intraperitoneal, transtracheal, subcutaneous, subcuticular, intraarticular, sub capsular, subarachnoid, intraspinal, intracerebro spinal, and intrasternal injection and infusion.
The phrases “parenteral administration” and “administered parenterally” as used herein, refer to modes of administration other than enteral and topical administration, usually by injection. The phrases “systemic administration,” “administered systemically”, “peripheral administration” and “administered peripherally” as used herein refer to the administration of a therapeutic agent other than directly into a target site, tissue, or organ, such as a site of cardiac dysfunction, such that it enters the subject's circulatory system and, thus, is subject to metabolism and other like processes. In other embodiments, the pharmaceutical composition is administered locally, e.g., by direct injections, and the injections can be repeated periodically.
In some embodiments, the compositions described herein are administered by intravenous injection, orally, intracardiac delivery, or intramuscular injection.
The term “effective amount” as used herein refers to the amount of a pharmaceutical composition needed to alleviate or prevent at least one or more symptoms of a muscular dystrophy, disease or disorder, and relates to a sufficient amount of pharmacological composition to provide the desired effect, e.g., increase cardiac output, reduce cardiomyopathy, reduce pathology, or any symptom associated with or caused by the loss of dystrophin. The term “therapeutically effective amount” therefore refers to an amount of a pharmaceutical composition described herein using the methods as disclosed herein, that is sufficient to effect a particular effect when administered to a typical subject. An effective amount as used herein would also include an amount sufficient to delay the development of a symptom of the disease, alter the course of a symptom disease (for example, but not limited to, slow the progression of a symptom of the disease), or reverse a symptom of the disease. Thus, it is not possible to specify the exact “effective amount.” However, for any given case, an appropriate “effective amount” can be determined by one of ordinary skill in the art using only routine experimentation.
Effective amounts, toxicity, and therapeutic efficacy can be determined by standard pharmaceutical procedures in cell cultures or experimental animals, e.g., for determining the LD50 (the dose lethal to 50% of the population) and the ED50 (the dose therapeutically effective in 50% of the population). The dosage can vary depending upon the dosage form employed and the route of administration utilized. The dose ratio between toxic and therapeutic effects is the therapeutic index and can be expressed as the ratio LD50/ED50. Compositions and methods that exhibit large therapeutic indices are preferred. A therapeutically effective dose can be estimated initially from cell culture assays. Also, a dose can be formulated in animal models to achieve a circulating plasma concentration range that includes the IC50 (i.e., the concentration of the RRM1, RRM2, or a combination thereof), which achieves a half-maximal inhibition of symptoms) as determined in cell culture, or in an appropriate animal model. Levels in plasma can be measured, for example, by high performance liquid chromatography. The effects of any particular dosage can be monitored by a suitable bioassay. The dosage can be determined by a physician and adjusted, as necessary, to suit observed effects of the treatment.
The pharmaceutical compositions described herein can be formulated, in some embodiments, with one or more additional therapeutic agents currently used to prevent or treat muscular dystrophy, for example. The effective amount of such other agents depends on the amount of the nucleic acid constructs in the formulation, the type of disorder or treatment, and other factors discussed above. These are generally used in the same dosages and with administration routes as used herein before or about from 1 to 99% of the heretofore employed dosages.
The dosage ranges for the pharmaceutical compositions described herein depend upon the potency, and encompass amounts large enough to produce the desired effect. The dosage should not be so large as to cause unacceptable adverse side effects. Generally, the dosage will vary with the age, condition, and sex of the patient and can be determined by one of skill in the art. The dosage can also be adjusted by the individual physician in the event of any complication. In some embodiments, the dosage ranges from 0.001 mg/kg body weight to 100 mg/kg body weight. In some embodiments, the dose range is from 5 μg/kg body weight to 100 μg/kg body weight. Alternatively, the dose range can be titrated to maintain serum levels between 1 μg/mL and 1000 μg/mL. For systemic administration, subjects can be administered a therapeutic amount, such as, e.g., 0.1 mg/kg, 0.5 mg/kg, 1.0 mg/kg, 2.0 mg/kg, 2.5 mg/kg, 5 mg/kg, 7.5 mg/kg, 10 mg/kg, 15 mg/kg, 20 mg/kg, 25 mg/kg, 30 mg/kg, 40 mg/kg, 50 mg/kg, or more. Dosages of viral vectors can also be expressed as numbers of viral genomes (vg) per kilogram. These doses can be administered by one or more separate administrations, or by continuous infusion. For repeated administrations over several days or longer, depending on the condition, the treatment is sustained until, for example, the muscular dystrophy is treated, as measured by the methods described above or known in the art. However, other dosage regimens can be useful.
While a goal of gene therapy is generally to introduce a therapeutic construct or sequence once or a limited number of times to effect a durable treatment, the duration of a therapy using the methods described herein can continue for as long as medically indicated or until a desired therapeutic effect (e.g., those described herein) is achieved. As will be appreciated by one of skill in the art, appropriate dosing regimens for a given composition can comprise a single administration or multiple ones. In certain embodiments, the administration of a pharmaceutical composition as described herein can be repeated, e.g., monthly, quarterly, biannually, yearly or over a more distantly separated period, depending upon duration of therapeutic effect.
The precise dose to be employed in a formulation will also depend on the route of administration and should be decided according to the judgment of the practitioner and each patient's circumstances. Ultimately, the practitioner or physician will decide the amount of the RNR, RRM1, RRM2, or mDys constructs or vectors to administer and how often to administer them based on desired effect and measured efficacies.
In some embodiments of these methods and all such methods described herein, the pharmaceutical compositions described herein are administered in an amount effective to provide cardioprotection, improve cardiac function, treat or prevent muscular dystrophy or complications thereof, and/or alleviate at least one symptom of a muscular dystrophy.
“Alleviating a symptom of a muscular dystrophy” is ameliorating any condition or symptom associated with the muscular dystrophy, e.g., cardiac dysfunction. Alternatively, alleviating a symptom of a muscular dystrophy can involve increasing contractile function, increasing systolic function, and/or increasing diastolic function in the subject relative to an untreated control. As compared with an equivalent untreated control, such reduction or degree of prevention is at least 5%, 10%, 20%, 40%, 50%, 60%, 80%, 90%, 95%, or 100% as measured by any standard technique.
The effects of the RNR pharmaceutical compositions described herein can be determined, for example, by detecting and measuring cardiac function in a subject, a test animal, or cell.
Methods for detecting, measuring, and determining cardiac function are known in the art. Non-limiting examples of clinical tests that can be used to assess cardiac functional parameters include echocardiography (with or without Doppler flow imaging), electrocardiogram (EKG), exercise stress test, Holter monitoring, or measurement of natriuretic peptide (e.g., atrial natriuretic peptide).
Where necessary or desired, animal models of muscular dystrophy can be used to gauge the effectiveness of a particular composition as described herein. For example, an mdx mouse model, or DMD canines can be used. Animal models of cardiac function are useful for monitoring infarct zones, coronary perfusion, electrical conduction, left ventricular end diastolic pressure, left ventricular ejection fraction, heart rate, blood pressure, degree of hypertrophy, diastolic relaxation function, cardiac output, heart rate variability, and ventricular wall thickness, etc.
In other embodiments, the nucleic acid constructs described herein may be used to treat a muscular dystrophy or a complication thereof, or improve survival, e.g., to reduce the onset, incidence of severity of a cardiovascular event. The efficacy of a therapeutic treatment can be assessed by the presence or absence of a symptom of a disease by functional output (e.g., measuring cardiac output or renal function), markers, levels or expression (e.g., serum levels of cardiac enzymes, markers of ischemia, renal function or insufficiency), and/or echocardiographic and electrographic means (e.g., an electrocardiogram or an echocardiogram). Further, as will be appreciated by a skilled physician, the ability to modify the nucleic acid constructs described herein can permit them to customize a treatment based on a subject's particular set of symptoms and/or severity of disease and further to minimize side effects or toxicity.
A patient who is being treated for a muscular dystrophy can be one whom a medical practitioner has diagnosed as having such a condition. Diagnosis can be by any suitable means. Diagnosis and monitoring can involve, for example, detecting the level of dystrophin in a biological sample (for example, a tissue biopsy, blood test, or urine test), detecting the level of creatine kinase (CK) in a biological sample, detecting symptoms associated with muscular dystrophy, or detecting the electrical activity of a muscle via electromyography (EMG) or an electrocardiogram (EKG). Genetic sequencing can also provide an indication of a mutation in one or more sequences involved in or linked to a congenital muscular dystrophy, including but not limited to a mutation that affects the structure or expression level of dystrophin. A patient in whom the development of a muscular dystrophy is being prevented may or may not have received a diagnosis of a muscular dystrophy. One of ordinary skill in the art will understand that these patients may have been subjected to the same standard tests as described above or may have been identified, without examination, as one at high risk due to the presence of one or more risk factors (such as family history of a muscular dystrophy).
All patents and other publications identified are expressly incorporated herein by reference for the purpose of describing and disclosing, for example, the methodologies described in such publications that might be used in connection with the present disclosure. These publications are provided solely for their disclosure prior to the filing date of the present application. Nothing in this regard should be construed as an admission that the inventors are not entitled to antedate such disclosure by virtue of prior disclosure or for any other reason. All statements as to the date or representation as to the contents of these documents are based on the information available to the applicants and do not constitute any admission as to the correctness of the dates or contents of these documents.
It should be understood that this disclosure is not limited to the particular methodology, protocols, and reagents, etc., provided herein and as such may vary. The terminology used herein is for the purpose of describing particular embodiments only, and is not intended to limit the scope of the present disclosure, which is defined solely by the claims. The invention is further illustrated by the following example, which should not be construed as further limiting.
The following examples are illustrative of disclosed methods and compositions. In light of this disclosure, those of ordinary skill in the art will recognize that variations of these examples and other examples of the disclosed methods and compositions would be possible without undue experimentation.
Male wild-type C57Bl/6J (The Jackson Laboratory, Bar Harbor, Me.) and mdx4cv (generated in house) mice were utilized for these studies (17). All animals were experimentally manipulated in accordance with the Institutional Animal Care and Use Committee (IACUC) of the University of Washington. Experimental mice were administered vector at 22-24 months of age via the retro-orbital sinus with a 200-μl bolus injection in Hanks Balanced Saline Solution (HBSS) at a dose of 2×1014 vg/kg. All mice were housed in a specific-pathogen free animal care facility using a 12-hr light/12-hr dark cycle with access to food and water ad libitum.
Recombinant AAV genomes containing the CK8 regulatory cassette (expressed exclusively in skeletal and cardiac muscle) and the human codon optimized (GenScript) μDys (ΔR2-15/ΔR18-22/ΔCT) (24), followed by the rabbit beta-globin poly-adenylation (pA) signal, were generated using standard cloning techniques. The rAAV genomes containing the cardiac-muscle specific cTnT455 regulatory cassette, the codon optimized human RNR transgene flanked by 100-bp UTR's, and the rabbit beta-globin pA were generated as previously described (49). The ‘dead’ rAAV genomes or promoter-less firefly luciferase followed by the human growth hormone (hGH) pA (kindly provided by JSC, University of Washington, Seattle Wash.) were used to generate the control rAAV genomes. The resulting constructs were co-transfected with the pDG6 packaging plasmid into HEK293 cells to generate rAAV vectors carrying serotype 6 capsids, that were harvested, enriched, and quantitated as previously described (50).
Total DNA was extracted from flash-frozen tissue samples with Tri-Reagent (MRC Inc.), according to manufacturer's instructions. All real-time PCR reactions were performed on a QuantStudio 3 Real Time PCR System (Applied Biosystems, Foster City, Calif.) in a total volume of 15 consisting of 5 μl sample DNA, 10.0 μl TaqMan Universal PCR Master Mix (Applied Biosystems, Foster City, Calif.), 0.2 μM of each primer, and 0.1 μM TaqMan custom probe (Applied Biosystems, Foster City, Calif.). Reaction conditions were 50° C. for 2 minutes, 95° C. for 10 minutes, and 40 cycles of 95° C. for 15 seconds followed by 60° C. for 1 minute. Each sample was analyzed in triplicate for concentration of total murine genomes and of total vector genomes. For vector genome detection by qPCR, the primers used to amplify either the rAAV6-cTnT455-RNR or rAAV6-CK8-μDys or rAAV6-ACMV-Luc (control vector) were unique to each vector. For the RNR vector the amplicon spanned from the distal region of the cTnT regulatory cassette, continuing into the proximal RNR1 subunit. For the μDys vector the amplicon was contained within the CK8 regulatory cassette, while the amplicon for the control vector resided within the human growth hormone (hGH) poly-adenylation. hGH Primers: 5′-CACAATCTTGGCTCACTGCAA-3′, 5′-GGAGGCTGAGGCAGGAGAA-3′, TaqMan Probe: 5′-6FAM-CTCCGCCTCCTGGGTTCAAGCG-MBGNQ-3′; CK8 RC Primers: 5′-CCCGAGATGCCTGGTTATAATT-3′, 5′-CGGGAACATGGCATGCA-3′, TaqMan Probe: 5′-6FAM-CCCCCCAACACCTGCTGCCTCT-MBGNQ-3′; cTnT455-RNR1 Primers: 5′-CCCAGTCCCCGCTGAGA-3′, 5′-AGGTTCCAGGCGCTGCT-3′, TaqMan Probe: 5′-6FAM-ACTCATCAATGTATCTTATCATG-MBGNQ-3′. Results were presented relative to DNA content in each 5 μl DNA tissue sample to determine vector genomes per ng DNA.
Tissues were collected and analyzed 5 months post-administration of vectors and compared with age-matched male control vector (rAAV6-ACMV-Luc) injected mdx4cv and wild-type (WT) mice. Hearts were either snap frozen in liquid nitrogen or were embedded in Optimal Cutting Temperature (O.C.T.) compound (VWR International) and flash frozen in liquid nitrogen cooled isopentane for histochemical or immunofluorescence analysis. The snap frozen samples were further processed by grinding to a powder under liquid nitrogen in a mortar kept on dry ice for subsequent extraction of nucleic acid and protein.
Heart cross-sections (10 μm) were co-stained with antibodies raised against alpha 2-laminin (Sigma, rat monoclonal, 1:200), the hinge-1 domain of dystrophin (alexa488 conjugated MANEX1011b, Developmental Studies Hybridoma Bank, University of Iowa, mouse monoclonal, 1:200), the human RRM1 (Abcam, rabbit monoclonal, 1:200), and the human RRM2 (Abcam, rabbit monoclonal, 1:200). Conjugated secondary antibodies (Jackson Immuno, Goat anti-Rabbit) were used at a 1:500 dilution. Slides were mounted using ProLong Gold with DAPI (Thermo Fisher Scientific) and imaged via a Leica SPV confocal microscope. Confocal micrographs covering a majority of the heart left ventricular muscle sections were acquired and montaged via the Fiji toolset (ImageJ) and InDesign (Adobe). For histology, Masson's trichrome staining was used to examine heart cross sections. Briefly, 10-μm muscle cryosections were sequentially stained in Wiegerts' iron hematoxylin (10 min), 1% Ponceau-acetic acid (5 min), and 1% aniline blue (5 s).
Radioimmunoprecipitation analysis buffer (RIPA) supplemented with 5 mM EDTA and 3% protease inhibitor cocktail (Sigma, Cat #P8340), was used to extract muscle proteins for 0.5 hour on ice with gentle agitation every 10 min. Total protein concentration was determined using Pierce BCA assay kit (ThermoFisher). Muscle lysates from WT, control mdx4cv and treated mdx4cv (30 μg) mice were denatured at 99 degrees Celsius for 10 min, quenched on ice, and separated via gel electrophoresis after loading onto Criterion 4-12% Bis-Tris polyacrylamide gels (BioRad). Overnight protein transfer to 0.45 mm PVDF membranes was performed at constant 43 volts at 4-degrees Celsius in Towbin's buffer containing 20% methanol. Blots were blocked for 1 hour at room temperature in 5% non-fat dry milk for 1 hour before overnight incubation with antibodies raised against the hinge-1 region of dystrophin (Developmental Studies Hybridoma Bank, University of Iowa, 1:300), anti-RRM1 (Abcam, rabbit monoclonal, 1:1,000), anti-RRM2 (Abcam, rabbit monoclonal 1:1,000), and anti-GAPDH (Sigma, Rabbit polyclonal, 1:50,000). Horseradish-peroxidase conjugated secondary antibody staining (1:50,000) was performed for 1 h at room temperature before signal development using Clarity Western ECL substrate (BioRad) and visualization using a Chemidoc MP imaging system (BioRad).
6. Quantification of Cardiac [dATP]
Approximately 25 pg of flash frozen, freshly ground ventricle cardiac tissue was used for direct quantification of intracellular dATP using the HPLC-MS/MS method previously described (51). Briefly, samples were extracted 1-3 days before measurement using a 50% methanol solution. The supernatant was stored at −20° C. until ready for injection into the HPLC-MS/MS system. A Water's Xevo-TQ-S mass spectrometer coupled with a Water's Acquity I-Class HPLC was used for the analysis (Milford, Mass., USA). Monitoring in negative mode via an electrospray ionization (ESI) was used to acquire MS-MS ions. dATP concentrations were quantified with standards and normalized to tissue weight.
Ex-vivo cardiac function was assessed in Langendorff isolated heart preparations as previously described (48,49,52). Hearts were perfused at a constant pressure of 80 mmHg with a modified Krebs-Henseleit (KH) buffer supplemented with glucose and pyruvate. The perfusate contained (in mmol/L): 118 NaCl, 25 NaHCO3, 5.3 KCl, 2.0 CaCl2, 1.2 MgSO4, 0.5 EDTA, 10.0 glucose, and 0.5 pyruvate, equilibrated with 95% 02 and 5% CO2 (pH 7.4). Temperature was maintained at 37.5° C. throughout the protocol. Left ventricular (LV) function was monitored via a water-filled balloon inserted into the LV and connected to a pressure transducer. LV systolic pressure (LVSP), end diastolic pressure (EDP), heart rate (HR), and minimum and maximum rate of pressure change in the ventricle (±dP/dt) were obtained from the attached data acquisition system (PowerLab, ADInstruments, Colorado Springs, Colo.). After 5 minutes of stabilization, hearts were equilibrated for 10 minutes at spontaneous heart rates and then fixed at a heart rate of ˜450 bpm with an electrical stimulator (Grass Technologies, Warwick, R.I.). Pressure-volume relationships (i.e., Frank-Starling curves) were assessed by gradually increasing the volume of the LV balloon. After a 5-minute recovery period, the perfusate was changed to an identical buffer as above except for the addition of 4.0 mmol/L CaCl2 to simulate a high workload (HWL) challenge for 20 minutes.
All values are reported as means±standard error of the mean (SEM). Starling curves and HWL function were analyzed by two-way repeated measures analysis of variance (ANOVA) followed by Tukey's post hoc analysis. End-point data was analyzed via one-way ANOVA or t-tests as appropriate. Mantel-Cox tests were used to analyze survival curves. Significance was tested at the P<0.05 level.
i. Improvements in Baseline Cardiac Function in Vector-Treated mdx4cv Hearts
As depicted in
2. Positive Changes in Frank-Starling Mechanics in Vector-Treated mdx4cv Hearts
To evaluate further systolic and diastolic function in vector treated-mdx4cv hearts, the pressure-volume relationship (i.e., Frank-Starling mechanism) in the isolated perfused heart preparation were examined. The left ventricular systolic pressure (LVSP) response to increased preload was significantly improved in both in mdx4cv+RNR and mdx4cv+μDys hearts compared to mdx4cv (
3. Augmented Response to Increased Cardiac Workload in Treated mdx4cv Hearts
It was previously reported that RNR overexpression in transgenic or vector-treated mouse hearts elevated baseline function but did not impair the response to an acute physiological increase in cardiac work (48,49). To verify that the improved systolic and diastolic function in RNR treated mdx4cv hearts at baseline was not associated with an inability to respond to an increased energetic demand, hearts were stressed with a combination of high calcium and elevated heart rates, via pacing stimulation. As shown in
To evaluate the localization of RNR and micro-dystrophin protein within the hearts of mice, immunofluorescence imaging was performed. As shown in
Provided herein are animal models used in pre-clinical research for DMD therapeutic development.
i. mdx
Mouse models have been used extensively to elucidate the pathogenic mechanisms of DMD, and have been indispensable in the development of therapeutic approaches. The mdx mouse is the most commonly used animal model for the analysis dystrophin expression and function. The mdx mouse contains a premature stop codon in exon 23 that leads to loss of full-length dystrophin, although smaller isoforms are still expressed.1,2 The mdx skeletal muscle shows moderate signs of dystrophy, young mice exhibit modest weakness and live ˜80% as long as controls, significantly more than that of DMD patients.3
Histological examination of mdx muscle during various stages of development reveals that muscle fiber necrosis and cellular infiltration begin at approximately 3 weeks of age. This is followed by a crisis period that peaks at approximately 4-6 weeks of age and is characterized by the presence of extensive necrosis, regenerating muscle fibers with centrally located nuclei, and elevated levels of serum creatine kinase (CK).1,4 After 12 weeks, the cycles of necrosis and regeneration begin to slow, although necrotic myofibers are present for the remainder of their lifespan. The fibrosis and infiltration of inflammatory cells in skeletal and cardiac muscle of the mdx are much milder than that observed in DMD patients.5,6 Similarly cardiomyopathy does not typically manifest until advanced age and often requires sensitive assays for functional deficit detection.7,8 In contrast, the mdx mouse diaphragm exhibits severe pathological changes and functional deficits comparable to that of DMD limb muscle.9,10 Four additional strains of mdx mice, mdx2cv-5cv, have been generated with N-ethylnitrosourea chemical mutagenesis.11 All these strains have point mutations that lead to loss of full-length dystrophin isoforms. The relative location of these mutations results in a series of mdx mouse mutants that vary in their expression of different dystrophin isoforms.12 Regardless of their differences, all five mdx strains display essentially identical muscle pathology as mdx mice, although additional phenotypes have been observed.11,13,14
2. mdx4cv
The mdx4cv strain displays a low background of reverent dystrophin containing fibers, making it a particularly useful strain in gene transfer studies exploring the feasibility of DMD therapy.14-16 Genetically, the mdx4cv mouse, has a point mutation that creates a stop codon in exon 53, and like other mdx strains displays a late-onset cardiomyopathy.17 Nonetheless, the mdx4cv was chosen as the model to demonstrate the robust benefits of AAV-mediated RNR & micro-dystrophin expression toward improvement of cardiac function.18
3. mdx:utrn−/− and mdx:utrn−/+
In efforts to make the mdx muscle phenotype more similar to that of patients, several additional mutations have been crossed onto the mdx background to generate double knockouts (DKOs). The most widely used is a dystrophin:utrophin DKO (mdx:utrn−/−).19,20 DKO mice display a severe phenotype including advanced cardiomyopathy, mild skeletal muscle fibrosis and an average lifespan of only ˜3 months. The severity of the phenotype supports the concept that utrophin upregulation in dystrophic muscles partially compensates for the absence of dystrophin. Further, the DKO mice have proved useful in gene therapy studies, where the phenotype can be largely eliminated by muscle-specific expression of utrophin, mini-utrophin, or mini- or micro-dystrophin.15,16,19-22 Additionally, the mdx:utrn+/−(het) mice have been quite useful, which display a normal (“mdx”) lifespan (˜2 yr) with severe skeletal muscle fibrosis and cardiomyopathy progression more similar to DMD patients making them an attractive model, particularly for cardiac studies.23,24
Generated by TALENs targeting exon 23, two lines of Dmdmdx rats both demonstrate undetectable levels of dystrophin.25 At 3-months of age the Dmdmdx hearts are notably dilated showing increased left ventricular (LV) diameter with LV wall thinning26 At 7 months, limb and respiratory muscles also showed severe fibrosis and some adipose tissue infiltration. Concomitment with the histopathology results, Dmdmdx rats also showed significant reduction in muscle strength and a decrease in locomotion.26 Demonstrating a more clinically relevant disease progression, particularly as it relates to cardiac function and histopathology, the Dmdmdx rat has gained momentum for the evaluation of gene therapies.
As a large animal model for DMD, spontaneous mutations causing dystrophinopathy have been identified in several breeds of dog.27,28 This led to the generation of multiple colonies of the golden retriever muscular dystrophy dog (GRMD) being created, and is the most extensively studied breed for this model.29,30 Due to prior use in research and its smaller size, the GRMD mutation has been bred onto the beagle background.31,32 Severe symptoms commonly appear at 6 months of age in the GRMD dog, but unlike the mdx mouse, the degree of severity and time of progression are quite variable. However, use of the GRMD model for potential therapies has gained much emphasis with its more clinically similar pathology than the mdx mouse model.
Recombinant adeno-associated viral vectors (rAAV) have received considerable attention as prospective gene delivery vectors for the treatment of genetic diseases1-6. In the case of severe neuromuscular conditions such as Duchenne muscular dystrophy, using rAAV for gene therapy for intervention would require the transduction of at least 40-50% of muscle fibers in the body7-10.
A number of recombinant AAV serotypes, in particular serotypes 1, 6, 8, and 9, have been shown to transduce striated muscle with high efficiency11-14. Indeed, our group has investigated numerous serotype comparisons over the past decade or so. As an example, in vitro myotube cultures (mouse (MM14), canine, & human) were grown, inoculated & compared for indicated reporter gene expression utilizing AAV6, AAV8, & AAV9 serotypes where each species demonstrates a preferential expression pattern with AAV6 transduction (
While previous reports have studied the dose response effects of rAAV in intramuscular injections, or in systemic injections of a vector encoding a secreted protein16-18 we sought to examine the relative expression levels of a non-secreted protein in various striated muscles following systemic rAAV6 administration at increasing doses. We observed an apparent dose-response threshold common to all striated muscles, as well as an individual muscle-specific transduction profile (
Finally, common methods of rAAV production typically generate a yield comprising 80-90% genome-devoid (or so-called “empty”) capsids that may be included or removed from the vector preparation prior to use, depending on purification/enrichment methods18,19 As empty capsids have been reported to decrease transduction in intramuscular injections18, we sought to test the hypothesis that a supplementary dose of empty capsids may affect transduction by “full” vectors when administered via systemic co-delivery. We found that empty capsids enhance transduction in striated muscles via intravenous administration, in a serotype-specific manner (
Various combinations of different promotors, an engineered version of the RNR enzyme that resists degradation, and an RNR construct that contains a different gene for the RRM2b subunit that also resists degradation were compared. Three separate studies were conducted in young and old mice. Mice received systemic injections of the AAV vectors and hearts were harvested one month later for analysis of dATP content (
It will be readily understood that the embodiments, as generally described herein, are exemplary. The following more detailed description of various embodiments is not intended to limit the scope of the present disclosure, but is merely representative of various embodiments. Moreover, the order of the steps or actions of the methods disclosed herein may be changed by those skilled in the art without departing from the scope of the present disclosure. In other words, unless a specific order of steps or actions is required for proper operation of the embodiment, the order or use of specific steps or actions may be modified.
Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member may be referred to and claimed individually or in any combination with other members of the group or other elements found herein. It is anticipated that one or more members of a group may be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is deemed to contain the group as modified thus fulfilling the written description of all Markush groups used in the appended claims.
Certain embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Of course, variations on these described embodiments will become apparent to those of ordinary skill in the art upon reading the foregoing description. The applicants expect skilled artisans to employ such variations as appropriate, and the applicants intend for the various embodiments of the disclosure to be practiced otherwise than specifically described herein. Accordingly, this disclosure includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the disclosure unless otherwise indicated herein or otherwise clearly contradicted by context.
Furthermore, numerous references have been made to patents and printed publications throughout this application. Each of the references and printed publications recited in this application are individually incorporated herein by reference in their entirety.
It is to be understood that the embodiments of the present disclosure are illustrative of the principles of the present disclosure. Other modifications that may be employed are within the scope of the disclosure. Thus, by way of example, but not of limitation, alternative configurations of the present disclosure may be utilized in accordance with the teachings herein. Accordingly, the present disclosure is not limited to that precisely as shown and described.
The particulars shown herein are by way of example and for purposes of illustrative discussion of the preferred embodiments of the present disclosure only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of various embodiments of the disclosure.
Definitions and explanations used in the present disclosure are meant and intended to be controlling in any future construction unless clearly and unambiguously modified in the examples or when application of the meaning renders any construction meaningless or essentially meaningless in cases where the construction of the term would render it meaningless or essentially meaningless, the definition should be taken from Webster's Dictionary, 3rd Edition or a dictionary known to those of ordinary skill in the art, such as the Oxford Dictionary of Biochemistry and Molecular Biology (Ed. Anthony Smith, Oxford University Press, Oxford, 2004).
It will be apparent to those having skill in the art that many changes may be made to the details of the above-described embodiments without departing from the underlying principles of the invention.
1990; 108(5): 748-52.
Science and Sports Exercise. 1994; 26(4): 432-9.
lupus familiaris]
lupus familiaris]
This application claims benefit under 35 U.S.C. § 119(e) of U.S. Provisional Application No. 62/866,986 filed Jun. 26, 2019, the contents of which are incorporated herein by reference in its entirety.
This invention was made with government support under Grant No. W81XWH-18-1-0624, awarded by the Department of Defense and Grant Nos. R01 HL122332 and R01 HL128368 and R56 AG055594, awarded by the National Institutes of Health. The government has certain rights in the invention.
| Number | Date | Country | |
|---|---|---|---|
| 62866986 | Jun 2019 | US |
