Patent Application
20240091383
The content of the ASCII text file of the sequence listing named “P2547US00-Sequence_listing_revised_2” which is 30.1 kb in size was created on Aug. 30, 2023 and electronically submitted herewith via EFS-Web is incorporated herein by reference.
The present application relates to the fields of biotechnology, virology, genetics, and molecular biology. More specifically, the present invention relates to an isolated nucleic acid for producing a gene therapy viral product, said isolated nucleic acid comprising a nucleic acid that encodes the SMN1 protein (survival motor neuron protein) having the amino acid sequence of SEQ ID NO: 1, and a nucleic acid that encodes the microRNA miR-23a, to an expression cassette and a vector based thereon, as well as to an AAV9 (adeno-associated virus serotype 9)-based recombinant virus for expressing the SMN1 gene in target cells, to a pharmaceutical composition that includes said recombinant virus, and to various uses of the above recombinant virus and the above composition.
Spinal muscular atrophy (SMA) relates to the group of neuromuscular diseases and is characterized by predominantly autosomal recessive inheritance pattern. Currently, the term SMA typically refers to the most common form of the disease that develops as a result of mutations and (or) deletions in the SMN1 (survival motor neuron 1) gene located on the long arm of chromosome 5 (5q11.2—q13.3) (Lefebvre et al., Cell (1995) 80:155-165). The disease is accompanied by motor neuron degeneration in the ventral (anterior) horn of the spinal cord, which leads to hypotonia of the proximal muscles responsible for gross motor skills, for example, crawling, walking, neck control, and also to swallowing disorder and breathing disorder (Sumner C. J., NeuroRx (2006) 3:235-245). Consequently, SMA patients present with increased tendencies for respiratory distress and superaddition of intercurrent diseases.
Gene therapy is a promising approach to treating spinal muscular atrophy.
Adeno-associated virus (AAV) vectors are considered effective in CNS gene therapy because they have suitable toxicity and immunogenicity profiles, they may be used in nerve cell transduction, and they are able to mediate long-term expression in the CNS.
Adeno-associated virus (AAV) is a small (20 nm), independent replication-defective, nonenveloped virus. Many different AAV serotypes have been described in human and primates. The adeno-associated virus genome is composed of (+ or −) single-stranded DNA (ssDNA) being about 4,700 nucleotides long. At the ends of a genomic DNA molecule, there are accommodated terminal inverted repeats (ITRs). The genome comprises two open reading frames (ORFs), Rep and Cap, comprising several alternative reading frames encoding various protein products. The rep products are essential for AAV replication, whereas three capsid proteins (VP1, VP2, and VP3), along with other alternative products, are encoded by the Cap gene. VP1, VP2, and VP3 are present at 1:1:10 ratio to form an icosahedral capsid (Xie Q. et al. The atomic structure of adeno-associated virus (AAV-2), a vector for human gene therapy. Proc Natl Acad Sci USA, 2002; 99:10405-10410). During recombinant AAV (rAAV) vector production, an expression cassette flanked by ITR is packaged into an AAV capsid. The genes required for AAV replication are not included in the cassette. Recombinant AAV is considered one of the safest and most widely used viral vectors for in vivo gene transfer. Vectors can infect cells of multiple tissue types to provide strong and sustained transgene expression. They are also non-pathogenic, and have a low immunogenicity profile (High K A et al., “rAAV human trial experience” Methods Mol Biol. 2011; 807:429-57).
International applications WO2017106354 (A1), WO2010129021 (A1), WO2015060722 (A1), WO2017066579 (A1), WO2015158749 (A2) disclose various variants of AAV comprising the SMN1 gene and uses thereof.
The authors of the invention have developed an isolated nucleic acid for producing a gene therapy viral product, said isolated nucleic acid comprising a nucleic acid that encodes the SMN1 protein having the amino acid sequence of SEQ ID NO: 1, and a nucleic acid that encodes the microRNA miR-23a, an expression cassette and a vector based thereon, as well as an AAV9-based recombinant virus for expressing the SMN1 gene in target cells, a pharmaceutical composition that includes said recombinant virus, and various uses of the above recombinant virus and the above composition. The authors of the invention surprisingly found that miR-23a enhances the functional effect of SMN1 in vitro and revealed the synergistic effect of SMN1 and miR-23a in treating SMA in an animal model of the disease
In one aspect, the present invention relates to an isolated nucleic acid for producing a gene therapy viral product, said isolated nucleic acid comprising a nucleic acid that encodes the SMN1 protein (survival motor neuron protein) having the amino acid sequence of SEQ ID NO: 1, and a nucleic acid that encodes the microRNA miR-23a.
In some embodiments, the isolated nucleic acid that encodes the SMN1 protein having the amino acid sequence of SEQ ID NO: 1 includes the nucleotide sequence of SEQ ID NO: 2.
In some embodiments, the isolated nucleic acid includes the microRNA miR-23a that has the nucleotide sequence of SEQ ID NO: 3.
In some embodiments, the isolated nucleic acid includes a nucleic acid encoding the microRNA miR-23a that includes the nucleotide sequence of SEQ ID NO: 4.
In some embodiments, the isolated nucleic acid includes the following elements in the 5′-end to 3′-end direction:
In one aspect, the present invention relates to an expression cassette comprising any of the above nucleic acids.
In some embodiments, the expression cassette includes the following elements in the 5′-end to 3′-end direction:
In some embodiments, the expression cassette includes a nucleic acid with SEQ ID NO: 6.
In one aspect, the present invention relates to an expression vector that includes any of the above nucleic acids or any of the above cassettes.
In one aspect, the present invention relates to an AAV9 (adeno-associated virus serotype 9)-based recombinant virus for the expression of the SMN1 gene in target cells, which includes a capsid and any of the above expression cassettes.
In some embodiments, the AAV9-based recombinant virus includes the AAV9 protein VP1.
In some embodiments, the AAV9-based recombinant virus includes the AAV9 protein VP1 having the amino acid sequence of SEQ ID NO: 7.
In some embodiments, the AAV9-based recombinant virus includes the AAV9 protein VP1 having the amino acid sequence of SEQ ID NO: 7 with one or more point mutations.
In some embodiments, the AAV9-based recombinant virus includes the AAV9 protein VP1 having the amino acid sequence of SEQ ID NO: 7 or the amino acid sequence of SEQ ID NO: 7 with one or more point mutations, and the expression cassette includes the following elements in the 5′-end to 3′-end direction:
In some embodiments, the AAV9-based recombinant virus includes the AAV9 protein VP1 having the amino acid sequence of SEQ ID NO: 7 or the amino acid sequence of SEQ ID NO: 7 with one or more point mutations, and the expression cassette comprises a nucleic acid with SEQ ID NO: 6.
In one aspect, the present invention relates to a pharmaceutical composition for delivering the SMN1 gene to target cells, which includes any of the above AAV9-based recombinant viruses in combination with one or more pharmaceutically acceptable excipients.
In one aspect, the present invention relates to the use of any of the above AAV9-based recombinant viruses or the above composition to deliver the SMN1 gene to target cells.
In one aspect, the present invention relates to the use of any of the above AAV9-based recombinant viruses or the above composition for survival of a subject that has spinal muscular atrophy and/or that does not have fully functional copies of the SMN1 gene.
In one aspect, the present invention relates to the use of any of the above AAV9-based recombinant viruses or the above composition for providing the SMN1 protein to a subject that has spinal muscular atrophy and/or that does not have fully functional copies of the SMN1 gene.
In one aspect, the present invention relates to the use of any of the above AAV9-based recombinant viruses or the above composition for treating spinal muscular atrophy in a subject that has spinal muscular atrophy.
In one aspect, the present invention relates to a method for modulating motor function in a subject having a motor neuron disorder, said method comprising administering a therapeutically effective amount of any of the above AAV9-based recombinant viruses or the above composition into the cells of the subject.
In one aspect, the present invention relates to a method for providing the SMN protein to a subject having spinal muscular atrophy, said method comprising administering a therapeutically effective amount of any of the above AAV9-based recombinant viruses or the above composition into the cells of the subject in need thereof.
In one aspect, the present invention relates to a method for delivering the SMN1 gene to the target cells of a subject having spinal muscular atrophy, said method comprising administering any of the above AAV9-based recombinant viruses or the above composition into the cells of the subject.
In one aspect, the present invention relates to a method for treating spinal muscular atrophy in a subject, said method comprising administering a therapeutically effective amount of any of the above AAV9-based recombinant viruses or the above composition into a subject having spinal muscular atrophy.
For
Unless defined otherwise herein, all technical and scientific terms used in connection with the present invention will have the same meaning as is commonly understood by those skilled in the art.
Furthermore, unless otherwise required by context, singular terms shall include plural terms, and the plural terms shall include the singular terms. Typically, the present classification and methods of cell culture, molecular biology, immunology, microbiology, genetics, analytical chemistry, organic synthesis chemistry, medical and pharmaceutical chemistry, as well as hybridization and chemistry of protein and nucleic acids described herein are well known by those skilled and widely used in the art. Enzyme reactions and purification methods are performed according to the manufacturer's guidelines, as is common in the art, or as described herein.
“Isolated” means altered or removed from the natural state. For example, a nucleic acid or a peptide naturally present in an animal is not “isolated”, but the same nucleic acid or peptide partially or completely separated from the coexisting materials of its natural state is “isolated”. An isolated nucleic acid or protein can exist in substantially purified form, or can exist in a non-native environment such as, for example, a genetically modified cell.
The terms “naturally occurring,” “native,” or “wild-type” are used to describe an object that can be found in nature as distinct from being artificially produced. For example, a protein or nucleotide sequence present in an organism (including a virus), which can be isolated from a source in nature and that has not been intentionally modified by a person in the laboratory, is naturally occurring.
The term “genome” refers to the complete genetic material of an organism.
As used in the present description and claims that follow, unless otherwise dictated by the context, the words “include” and “comprise,” or variations thereof such as “having,” “includes”, “including”, “comprises,” or “comprising,” will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.
As used in the present description, the terms “peptide”, “polypeptide” and “protein” are used interchangeably, and they refer to a compound consisting of amino acid residues that are covalently linked by peptide bonds. A protein or peptide must contain at least two amino acids, and no limitation is placed on the maximum number of amino acids that can comprise a protein's or peptide's sequence. Polypeptides include any peptide or protein comprising two or more amino acids joined to each other by peptide bonds. As used in the present description, the term refers to both short chains, which also commonly are referred to in the art, for example, as peptides, oligopeptides and oligomers, and to longer chains, which generally are referred to in the art as proteins, of which there are many types. “Polypeptides” include, inter alia, for example, biologically active fragments, substantially homologous polypeptides, oligopeptides, homodimers, heterodimers, variants of polypeptides, modified polypeptides, derivatives, analogs, fusion proteins. The polypeptides include natural peptides, recombinant peptides, synthetic peptides, or a combination thereof.
The terms “nucleic acid”, “nucleic sequence”, “nucleic acid sequence”, “polynucleotide”, “oligonucleotide”, “polynucleotide sequence” and “nucleotide sequence”, used interchangeably in the present description, mean a precise sequence of nucleotides, modified or not, determining a fragment or a region of a nucleic acid, containing unnatural nucleotides or not, and being either a double-strand DNA or RNA, a single-strand DNA or RNA, or transcription products of said DNAs.
As used in the present description, polynucleotides include, as non-limiting examples, all nucleic acid sequences which are obtained by any means available in the art, including, as non-limiting examples, recombinant means, i.e. the cloning of nucleic acid sequences from a recombinant library or a cell genome, using ordinary cloning technology and PCR and the like, and by synthetic means.
It should also be included here that the present invention does not relate to nucleotide sequences in their natural chromosomal environment, i.e. in a natural state. The sequences of the present invention have been isolated and/or purified, i.e., they were sampled directly or indirectly, for example by copying, their environment having been at least partially modified. Thus, isolated nucleic acids obtained by recombinant genetics, by means, for example, of host cells, or obtained by chemical synthesis should also be mentioned here.
Unless otherwise indicated, the term nucleotide sequence encompasses its complement. Thus, a nucleic acid having a particular sequence should be understood as one which encompasses the complementary strand thereof with the complementary sequence thereof.
Viruses of the Parvoviridae family are small DNA-containing animal viruses. The Parvoviridae family may be divided into two subfamilies: the Parvovirinae, which members infect vertebrates, and the Densovirinae, which members infect insects. By 2006, there have been 11 serotypes of adeno-associated virus described (Mori, S. ET AL., 2004, “Two novel adeno-associated viruses from cynomolgus monkey: pseudotyping characterization of capsid protein”, Virology, T. 330 (2): 375-83). All of the known serotypes can infect cells from multiple tissue types. Tissue specificity is determined by the capsid protein serotype; therefore, the adeno-associated virus-based vectors are constructed by assigning the desired serotype. Further information on parvoviruses and other members of the Parvoviridae is described in the literature (Kenneth I. Berns, “Parvoviridae: The Viruses and Their Replication”, Chapter 69 in Fields Virology (3d Ed. 1996)).
The genomic organization of all known AAV serotypes is very similar. The genome of AAV is a linear, single-stranded DNA molecule that is less than about 5000 nucleotides (nt) in length. Inverted terminal repeats (ITRs) flank the unique coding nucleotide sequences of replication of non-structural proteins (Rep) and structural proteins (Cap). The Cap gene encodes the VP proteins (VP1, VP2, and VP3) which form the capsid. The terminal 145 nucleotides are self-complementary and are organized such that an energetically stable intramolecular duplex forming a T-shaped hairpin may be formed. Such hairpin structures function as an origin for virus DNA replication, serving as primers for the cellular DNA polymerase complex. Following wild-type AAV (wtAAV) infection in mammalian cells, the Rep genes (e.g. Rep78 and Rep52) are expressed using the P5 promoter and the P19 promoter, respectively, and the both Rep proteins have a certain function in the replication of the viral genome. A splicing event in the Rep open reading frame (Rep ORF) results in the expression of actually four Rep proteins (e.g. Rep78, Rep68, Rep52, and Rep40). However, it has been shown that the unspliced mRNA encoding Rep78 and Rep52 proteins is sufficient for AAV vector production in mammalian cells.
The term “vector” as used herein means a nucleic acid molecule capable of transporting another nucleic acid to which it has been linked. Furthermore, the term “vector” herein refers to a viral particle capable of transporting a nucleic acid.
As used in the present description, the term “expression” is defined as the transcription and/or translation of a particular nucleotide sequence driven by its promoter.
“Gene therapy” is the insertion of genes into subject's cells and/or tissues to treat a disease, typically hereditary diseases, in which a defective mutant allele is replaced with a functional one.
“Treat”, “treating” and “treatment” refer to a method of alleviating or abrogating a biological disorder and/or at least one of its attendant symptoms. As used herein, to “alleviate” a disease, disorder or condition means reducing the severity and/or occurrence frequency of the symptoms of a disease, disorder, or condition. Further, references herein to “treatment” include references to curative, palliative and prophylactic treatment.
In one aspect, the subject of treatment, or patient, is a mammal, preferably a human subject. Said subject may be either male or female, of any age.
The term “disorder” means any condition that would benefit from treatment with the compound of the present invention.
“Disease” is a state of health of a subject where the subject cannot maintain homeostasis, and where if the disease is not ameliorated then the subject's health continues to deteriorate.
The terms “subject,” “patient,” “individual,” and the like are used interchangeably in the present description, and they refer to any animal which is amenable to the methods described in the present description. In certain non-limiting embodiments, the subject, patient or individual is a human. Said subject may be either male or female, of any age.
“Therapeutically effective amount” or “effective amount” refers to that amount of the therapeutic agent being administered which will relieve to some extent one or more of the symptoms of the disease being treated.
In one aspect, the present invention relates to an isolated nucleic acid for producing a gene therapy viral product, said isolated nucleic acid comprising a nucleic acid that encodes the SMN1 protein (survival motor neuron protein) having the amino acid sequence
and a nucleic acid that encodes the microRNA miR-23a;
In some embodiments, the above nucleic acid is used for producing a gene therapy viral product that is an expression vector of the invention or an AAV9-based recombinant virus of the invention.
An “isolated” nucleic acid molecule is one which is identified and separated from at least one nucleic acid molecule-impurity, which the former is typically bound to in the natural source of nuclease nucleic acid. An isolated nucleic acid molecule is different from the form or set in which it is found under natural conditions. Thus, an isolated nucleic acid molecule is different from a nucleic acid molecule that exists in cells under natural conditions.
In some embodiments, the isolated nucleic acid is DNA.
As would be appreciated by those skilled in the art, because of the redundancy of the genetic code, a variety of different DNA sequences can encode the SMN1 protein having the amino acid sequence of SEQ ID NO: 1. It is well within the skill of a person trained in the art to create these alternative DNA sequences encoding the same amino acid sequences. Such variant DNA sequences are within the scope of the present invention.
In some embodiments, the isolated nucleic acid that encodes the SMN1 protein having the amino acid sequence of SEQ ID NO: 1 includes the nucleotide sequence
In some embodiments, the isolated nucleic acid includes the microRNA miR-23a that has the nucleotide sequence
In some embodiments, the isolated nucleic acid includes a nucleic acid encoding the microRNA miR-23a that includes the nucleotide sequence
The above nucleic acid, which encodes the microRNA miR-23a, having the nucleotide sequence SEQ ID NO: 4 is a nucleic acid before processing.
Following processing, the nucleic acid, which encodes the microRNA miR-23a, has the nucleotide sequence
In some embodiments, the isolated nucleic acid includes the following elements in the 5′-end to 3′-end direction:
In one aspect, the present invention relates to an expression cassette comprising any of the above nucleic acids.
The term “expression cassette”, as used herein, refers in particular to a DNA fragment that is capable, in an appropriate setting, of triggering the expression of a polynucleotide encoding a polypeptide of interest that is included in said expression cassette. When introduced into a host cell, the expression cassette is, inter alia, capable of engaging cellular mechanisms to transcribe the polynucleotide encoding the polypeptide of interest into RNA that is then typically further processed and eventually translated into the polypeptide of interest. The expression cassette may be contained in an expression vector.
The term “cassette which expresses” or “expression cassette”, as used herein, refers in particular to a DNA fragment that is capable, in an appropriate setting, of triggering the expression of a polynucleotide encoding a polypeptide of interest that is included in said expression cassette. When introduced into a host cell, the expression cassette is, inter alia, capable of engaging cellular mechanisms to transcribe the polynucleotide encoding the polypeptide of interest into RNA that is then typically further processed and eventually translated into the polypeptide of interest. The expression cassette may be contained in an expression vector.
The expression cassette of the present invention comprises a promoter as an element. The term “promoter” as used herein refers in particular to a DNA element that promotes the transcription of a polynucleotide to which the promoter is operably linked. The promoter may further form part of a promoter/enhancer element. Although the physical boundaries between the “promoter” and “enhancer” elements are not always clear, the term “promoter” typically refers to a site on the nucleic acid molecule to which an RNA polymerase and/or any associated factors binds and at which transcription is initiated. Enhancers potentiate promoter activity temporally as well as spatially. Many promoters are known in the art to be transcriptionally active in a wide range of cell types. Promoters can be divided into two classes, those that function constitutively and those that are regulated by induction or derepression. The both classes are suitable for protein expression. Promoters that are used for high-level production of polypeptides in eukaryotic cells and, in particular, in mammalian cells, should be strong and preferably active in a wide range of cell types. Strong constitutive promoters which are capable of driving expression in many cell types are well known in the art and, therefore, it is not herein necessary to describe them in detail. In accordance with the idea of the present invention, it is preferable to use the cytomegalovirus (CMV) promoter. A promoter or promoter/enhancer derived from the immediate early (IE) region of human cytomegalovirus (hCMV) is particularly suitable as a promoter in the expression cassette of the present invention. Human cytomegalovirus (hCMV) immediate early (IE) region and functional expression-inducing and/or functional expression-enhancing fragments derived therefrom, for example, have been disclosed in EP0173177 and EP0323997, and are well known in the art. Thus, several fragments of the hCMV immediate early (IE) region may be used as a promoter and/or promoter/enhancer. According to one embodiment of the invention, the human CMV promoter is used in the expression cassette of the present invention.
In some embodiments, the expression cassette includes the following elements in the 5′-end to 3′-end direction:
In some embodiments, the left-hand (first) ITR (inverted terminal repeats) has the following nucleic acid sequence:
In some embodiments, the CMV (cytomegalovirus) enhancer has the following nucleic acid sequence:
In some embodiments, the CMV (cytomegalovirus) promoter has the following nucleic acid sequence:
In some embodiments, the intron of the hBG1 (hemoglobin subunit gamma 1) gene has the following nucleic acid sequence:
In some embodiments, the hGH1 (human growth hormone 1 gene) polyadenylation signal has the following nucleic acid sequence:
In some embodiments, the SV40 promoter (simian virus 40 promoter) has the following nucleic acid sequence:
In some embodiments, the SV40 polyadenylation signal (simian virus 40 polyadenylation signal) has the following nucleic acid sequence:
In some embodiments, the right-hand (second) ITR has the following nucleic acid sequence:
In some embodiments, the expression cassette includes a nucleic acid with the nucleotide sequence
In one aspect, the present invention relates to an expression vector that includes any of the above nucleic acids or any of the above cassettes.
In some embodiments, a vector is a plasmid, i.e., a circular double stranded piece of DNA into which additional DNA segments may be ligated.
In some embodiments, a vector is a viral vector, wherein additional DNA segments may be ligated into the viral genome.
In some embodiments, vectors are capable of autonomous replication in a host cell into which they are introduced (e.g. bacterial vectors having a bacterial origin site of replication and episomal mammalian vectors). In further embodiments, vectors (e.g. non-episomal mammalian vectors) may be integrated into the genome of a host cell upon introduction into a host cell, and thereby are replicated along with the host gene. Moreover, certain vectors are capable of directing the expression of genes to which they are operably linked. Such vectors are referred to herein as “recombinant expression vectors” (or simply, “expression vectors”).
Expression vectors include plasmids, retroviruses, adenoviruses, adeno-associated viruses (AAVs), plant viruses, such as cauliflower mosaic virus, tobacco mosaic virus, cosmids, YACs, EBV derived episomes, and the like. DNA molecules may be ligated into a vector such that transcriptional and translational control sequences within the vector serve their intended function of regulating the transcription and translation of the DNA. An expression vector and expression control sequences may be chosen to be compatible with the expression host cell used. DNA molecules may be introduced into the expression vector by standard methods (e.g. ligation of complementary restriction sites, or blunt end ligation if no restriction sites are present).
The recombinant expression vector may also encode a leader peptide (or a signal peptide) that facilitates the secretion of the protein of interest from a host cell. The gene of the protein of interest may be cloned into the vector such that the signal peptide is linked in-frame to the amino terminus of the protein of interest. The leader peptide (or signal peptide) may be an immunoglobulin leader peptide or other leader peptide (that is, a non-immunoglobulin protein leader peptide).
In addition to the SMN1 and microRNA miR-23a genes according to the present invention, the recombinant expression of the vectors according to the present invention may carry regulatory sequences that control the expression of the SMN1 gene and microRNA miR-23a gene in a host cell. It will be understood by those skilled in the art that the design of an expression vector, including the selection of regulatory sequences, may depend on such factors as the choice of a host cell to be transformed, the level of expression of a desired protein, and so forth. Preferred control sequences for an expression host cell in mammals include viral elements that ensure high levels of protein expression in mammalian cells, such as promoters and/or enhancers derived from a retroviral LTR, cytomegalovirus (CMV) (such as a CMV promoter/enhancer), simian virus 40 (SV40) (such as a SV40 promoter/enhancer), adenovirus, (e.g. the major late promoter adenovirus (AdMLP)), polyomavirus and strong mammalian promoters such as native immunoglobulin promoter or actin promoter.
The term “control sequences” refers to DNA sequences necessary for the expression of an operably linked coding sequence in a particular host organism. The control sequences that are suitable for prokaryotes are, for example, a promoter, optionally an operator sequence and a ribosome binding site. Eukaryotic cells are known to include promoters, polyadenylation signals, and enhancers.
As used in the present description, the term “promoter” or “transcription regulatory sequence” or “regulatory sequence” refers to a nucleic acid fragment that controls the transcription of one or more coding sequences, and that is located upstream with respect to the direction of reading relative to the direction of transcription from the transcription initiation site of the coding sequence, and is structurally identified by the presence of a binding site for DNA-dependent RNA polymerase, transcription initiation sites and any other DNA sequences, including, but not limited to, transcription factor binding sites, repressor and activator protein binding sites, and any other sequences of nucleotides known to one of skill in the art that directly or indirectly regulate the level of transcription with said promoter. A “constitutive” promoter is a promoter that is active in most tissues under typical physiological and developmental conditions. An “inducible” promoter is a promoter that is physiologically or developmentally regulated, e.g. under the influence of a chemical inducer. A “tissue specific” promoter is only active in specific types of tissues or cells.
The terms “enhancers” or “enhancer” as used herein may refer to a DNA sequence that is located adjacent to the DNA sequence that encodes a recombinant product. Enhancer elements are typically located in a 5′ direction from a promoter element or can be located downstream of or within a coding DNA sequence (e.g. a DNA sequence transcribed or translated into a recombinant product or products). Hence, an enhancer element may be located 100 base pairs, 200 base pairs, or 300 or more base pairs upstream of a DNA sequence that encodes a recombinant product, or downstream of said sequence. Enhancer elements may increase the amount of a recombinant product being expressed from a DNA sequence above the level of expression associated with a single promoter element. Multiple enhancer elements are readily available to those of ordinary skill in the art.
The term “expression control sequence” as used in the present description refers to polynucleotide sequences that are necessary to effect the expression and processing of coding sequences to which they are ligated. Expression control sequences include appropriate transcription initiation, termination, promoter and enhancer sequences; efficient RNA processing signals such as splicing and polyadenylation signals; sequences that stabilize cytoplasmic mRNA; sequences that enhance translation efficiency (i.e., Kozak consensus sequence); sequences that enhance protein stability; and when desired, sequences that enhance protein secretion. The nature of such control sequences differs depending upon the host organism; in prokaryotes, such control sequences generally include the promoter of ribosome binding site, and transcription termination sequences; in eukaryotes, typically, such control sequences include promoters and transcription termination sequences. The term “control sequences” includes at least all components, the presence of which is essential for expression and processing, and can also include additional components, the presence of which is advantageous, for example, leader sequences and fusion partner sequences.
In one embodiment of the present invention, “expression vector” relates to a vector comprising one or more polynucleotide sequences of interest, genes of interest, or “transgenes” that are flanked by parvoviral sequences or inverted terminal repeat (ITR) sequences.
Neither the cassette nor the vector of the invention comprises nucleotide sequences of genes encoding non-structural proteins (Rep) and structural proteins (Cap) of the adeno-associated virus.
In one aspect, the present invention relates to an AAV9 (adeno-associated virus serotype 9)-based recombinant virus for the expression of the SMN1 gene in target cells, which includes a capsid and any of the above expression cassettes.
The term “AAV-based recombinant virus” (or “AAV-based virus-like particle”, or “AAV recombinant virus strain”, or “AAV recombinant vector”, or “rAAV vector”) as used in this description refers to the above expression cassette (or the above expression vector), which is enclosed within the AAV capsid.
The Cap gene, among other alternative products, encodes 3 capsid proteins (VP1, VP2, and VP3). VP1, VP2, and VP3 are present at 1:1:10 ratio to form an icosahedral capsid (Xie Q. et al. The atomic structure of adeno-associated virus (AAV-2), a vector for human gene therapy. Proc Natl Acad Sci USA, 2002; 99:10405-10410). Transcription of these genes starts from a single promoter, p40. The molecular weights of the corresponding proteins (VP1, VP2 H VP3) are 87, 72, and 62 kDa, respectively. All of the three proteins are translated from a single mRNA. Following transcription, pre-mRNA may be spliced in two different manners, where either longer or shorter intron is excised to form mRNAs of various nucleotide lengths.
During the production of the AAV (rAAV)-based recombinant virus, an expression cassette flanked by ITR is packaged into an AAV capsid. The genes required for AAV replication, as mentioned above, are not included in the cassette.
The expression cassette DNA is packaged into a viral capsid in the form of a single stranded DNA molecule (ssDNA) being approximately 3000 nucleotides long. Once a cell is infected with the virus, the single-stranded DNA is converted to the form of double-stranded DNA (dsDNA). The dsDNA can only be used by the cell's proteins, which transcribe the present gene or genes into RNA.
In some embodiments, the AAV9-based recombinant virus has a capsid that includes the AAV9 protein VP1.
In some embodiments, the AAV9-based recombinant virus has a capsid that includes the AAV9 protein VP1 having the following amino acid sequence
In some embodiments, the AAV9-based recombinant virus has a capsid that includes the AAV9 protein VP1 having the amino acid sequence of SEQ ID NO: 7 with one or more point mutations.
In some embodiments, the AAV9-based recombinant virus has a capsid that includes the AAV9 protein VP2.
In some embodiments, the AAV9-based recombinant virus has a capsid that includes the AAV9 protein VP2 having the following amino acid sequence:
In some embodiments, the AAV9-based recombinant virus has a capsid that includes the AAV9 protein VP2 having the amino acid sequence of SEQ ID NO: 8 with one or more point mutations.
In some embodiments, the AAV9-based recombinant virus has a capsid that includes the AAV9 protein VP3.
In some embodiments, the AAV9-based recombinant virus has a capsid that includes the AAV9 protein VP3 having the following amino acid sequence
In some embodiments, the AAV9-based recombinant virus has a capsid that includes the AAV9 protein VP3 having the amino acid sequence of SEQ ID NO: 9 with one or more point mutations.
In some embodiments, the AAV9-based recombinant virus has a capsid that includes the AAV9 proteins VP1, VP2, and VP3.
In some embodiments, the AAV9-based recombinant virus has a capsid that includes the proteins VP1 having the amino acid sequence of SEQ ID NO: 7, VP2 having the amino acid sequence of SEQ ID NO: 8, and VP3 having the amino acid sequence of SEQ ID NO: 9.
In some embodiments, the AAV9-based recombinant virus has a capsid that includes the proteins VP1 having the amino acid sequence of SEQ ID NO: 7 with one or more point mutations, VP2 having the amino acid sequence of SEQ ID NO: 8 with one or more point mutations, and VP3 having the amino acid sequence of SEQ ID NO: 9 with one or more point mutations.
The phrase “more point mutations” refers to two, three, four, five, six, seven, eight, nine, or ten point substitutions.
Particularly preferred embodiments include substitutions (mutations) that are conservative in nature, i.e. substitutions that take place within a family of amino acids that are joined in their side chains. In particular, amino acids are typically divided into four families: (1) acidic amino acids are aspartate and glutamate; (2) basic amino acids are lysine, arginine, histidine; (3) non-polar amino acids are alanine, valine, leucine, isoleucine, proline, phenylalanine, methionine, tryptophan, and (4) uncharged polar amino acids are glycine, asparagine, glutamine, cysteine, serine, threonine, tyrosine. Phenylalanine, tryptophan, and tyrosine are sometimes classified as aromatic amino acids. For example, it is reasonably predictable that an isolated substitution of leucine for isoleucine or valine, an aspartate for a glutamate, a threonine for a serine, or a similar conservative substitution of an amino acid for a structurally related amino acid, will not have a major effect on the biological activity. For example, the polypeptide of interest may include up to about 5-10 conservative or non-conservative amino acid substitutions, so long as the desired function of the molecule remains intact.
An embodiment with point mutations in the sequences of AAV9 proteins VP1, VP2, or VP3 using amino acid substitutions is a substitution of at least one amino acid residue in the AAV9 protein VP1, VP2, or VP3 with another amino acid residue. Conservative substitutions are shown in Table A under “preferred substitutions”.
In some embodiments, the AAV9-based recombinant virus has a capsid that includes the AAV9 protein VP1 having the amino acid sequence of SEQ ID NO: 7 or the amino acid sequence of SEQ ID NO: 7 with one or more point mutations, and the expression cassette includes the following elements in the 5′-end to 3′-end direction:
In some embodiments, the AAV9-based recombinant virus has a capsid that includes the proteins VP1 having the amino acid sequence of SEQ ID NO: 7, VP2 having the amino acid sequence of SEQ ID NO: 8, and VP3 having the amino acid sequence of SEQ ID NO: 9, and the expression cassette includes the following elements in the 5′-end to 3′-end direction:
In some embodiments, the AAV9-based recombinant virus has a capsid that includes the proteins VP1 having the amino acid sequence of SEQ ID NO: 7 with one or more point mutations, VP2 having the amino acid sequence of SEQ ID NO: 8 with one or more point mutations, and VP3 having the amino acid sequence of SEQ ID NO: 9 with one or more point mutations, and the expression cassette includes the following elements in the 5′-end to 3′-end direction:
In some embodiments, the AAV9-based recombinant virus has a capsid that includes the AAV9 protein VP1 having the amino acid sequence of SEQ ID NO: 7 or the amino acid sequence of SEQ ID NO: 7 with one or more point mutations, and the expression cassette comprises a nucleic acid with SEQ ID NO: 6.
In some embodiments, the AAV9-based recombinant virus has a capsid that includes the proteins VP1 having the amino acid sequence of SEQ ID NO: 7, VP2 having the amino acid sequence of SEQ ID NO: 8, and VP3 having the amino acid sequence of SEQ ID NO: 9, and the expression cassette comprises a nucleic acid with SEQ ID NO: 6.
In some embodiments, the AAV9-based recombinant virus has a capsid that includes the proteins VP1 having the amino acid sequence of SEQ ID NO: 7 with one or more point mutations, VP2 having the amino acid sequence of SEQ ID NO: 8 with one or more point mutations, and VP3 having the amino acid sequence of SEQ ID NO: 9 with one or more point mutations, and the expression cassette comprises a nucleic acid with SEQ ID NO: 6.
In one aspect, the present invention relates to a pharmaceutical composition for delivering the SMN1 gene to target cells, which includes any of the above AAV9-based recombinant viruses in combination with one or more pharmaceutically acceptable excipients.
The active substance in the above composition is present in an effective amount, for example, in a biologically effective amount.
In particular embodiments, the present invention relates to a pharmaceutical composition comprising the AAV9-based recombinant virus of the invention in a pharmaceutically acceptable carrier or in other pharmaceutical agents, adjuvants, diluents, etc. For injection, the carrier will typically be a liquid carrier. For other methods of administration, the carrier may be either solid or liquid, such as sterile pyrogen-free water or sterile pyrogen-free phosphate-buffered saline solution. For inhalation administration, the carrier is respirable, and preferably is in a solid or liquid particulate form. As an injection medium, it is preferred to use water that contains the additives that are common for injection solutions, such as stabilizing agents, salts or saline, and/or buffers.
“Pharmaceutical composition” means a composition comprising the above AAV9-based recombinant virus of the invention and at least one of components selected from the group consisting of pharmaceutically acceptable and pharmacologically compatible excipients, such as fillers, solvents, diluents, carriers, auxiliary, distributing agents, delivery agents, preservatives, stabilizers, emulsifiers, suspending agents, thickeners, prolonged delivery controllers, the choice and proportions of which depend on the type and route of administration and dosage. Pharmaceutical compositions of the present invention and methods of preparation thereof will be undoubtedly apparent to those skilled in the art. The pharmaceutical compositions should preferably be manufactured in compliance with the GMP (Good Manufacturing Practice) requirements. The composition may comprise a buffer composition, tonicity agents, stabilizers and solubilizers.
“Pharmaceutically acceptable” means a material that does not have biological or other negative side effects, for example, the material can be administered to a subject without causing any undesirable biological effects. Thus, such pharmaceutical compositions may be used, for example, in transfection of a cell ex vivo or in administration in vivo of the AAV9-based recombinant virus of the invention directly to a subject.
The term “excipient” is used herein to describe any ingredient other than the above ingredients of the invention. These are substances of inorganic or organic nature which are used in the pharmaceutical manufacturing in order to give drug products the necessary physicochemical properties.
“Stabilizer” refers to an excipient or a mixture of two or more excipients that provide the physical and/or chemical stability of the active agent.
The term “buffer”, “buffer composition”, “buffering agent” refers to a solution, which is capable of resisting changes in pH by the action of its acid-base conjugate components, which allows the rAAV9 vector product to resist changes in pH. Generally, the pharmaceutical composition preferably has a pH in the range from 4.0 to 8.0. Examples of buffers used include, but are not limited to, acetate, phosphate, citrate, histidine, succinate, etc. buffer solutions.
The pharmaceutical composition is “stable” if the active agent retains physical stability and/or chemical stability and/or biological activity thereof during the specified shelf life at storage temperature, for example, of 2-8° C. Preferably, the active agent retains both physical and chemical stability, as well as biological activity. Storage period is adjusted based on the results of stability test in accelerated or natural aging conditions.
A pharmaceutical composition of the invention can be manufactured, packaged, or widely sold in the form of a single unit dose or a plurality of single unit doses in the form of a ready formulation. The term “single unit dose” as used herein refers to discrete quantity of a pharmaceutical composition containing a predetermined quantity of an active ingredient. The quantity of the active ingredient typically equals the dose of the active ingredient to be administered in a subject, or a convenient portion of such dose, for example, half or a third of such dose.
The authors of the invention surprisingly found that miR-23a enhances the functional effect of SMN1 in vitro and revealed the synergistic effect of SMN1 and miR-23a in treating SMA in an animal model of the disease.
In one aspect, the present invention relates to the use of any of the above AAV9-based recombinant viruses or the above composition to deliver the SMN1 gene to target cells.
In one aspect, the present invention relates to the use of any of the above AAV9-based recombinant viruses or the above composition for survival of a subject that has spinal muscular atrophy and/or that does not have fully functional copies of the SMN1 gene.
In one aspect, the present invention relates to the use of any of the above AAV9-based recombinant viruses or the above composition for providing the SMN1 protein to a subject that has spinal muscular atrophy and/or that does not have fully functional copies of the SMN1 gene.
In one aspect, the present invention relates to the use of any of the above AAV9-based recombinant viruses or the above composition for treating spinal muscular atrophy in a subject that has spinal muscular atrophy.
In one aspect, the present invention relates to a method for modulating motor function in a subject having a motor neuron disorder, said method comprising administering a therapeutically effective amount of any of the above AAV9-based recombinant viruses or the above composition into the cells of the subject.
In one aspect, the present invention relates to a method for providing the SMN protein to a subject having spinal muscular atrophy, said method comprising administering a therapeutically effective amount of any of the above AAV9-based recombinant viruses or the above composition into the cells of the subject in need thereof.
In one aspect, the present invention relates to a method for delivering the SMN1 gene to the target cells of a subject having spinal muscular atrophy, said method comprising administering any of the above AAV9-based recombinant viruses or the above composition into the cells of the subject.
In one aspect, the present invention relates to a method for treating spinal muscular atrophy in a subject, said method comprising administering a therapeutically effective amount of any of the above AAV9-based recombinant viruses or the above composition into a subject having spinal muscular atrophy.
The lack of fully functional copies of the SMN1 gene refers to inactivating mutations or deletions in all copies of the SMN1 gene in the genome, which result in the loss or defect of the function of the SMN1 gene.
Subject refers to any animal that is amenable to the techniques provided in the present description. In certain non-limiting embodiments, the subject is a human. Said subject may be either male or female, of any age.
A subject in need of delivering the SMN1 gene to target cells, or a subject in need of being provided with the SMN1 protein, or a subject in need of delivering the SMN1 gene to target cells refers to a subject who has spinal muscular atrophy or a subject who has inactivating mutations or deletions in the SMN1 gene that lead to loss or defect in the function of the SMN1 gene.
Exemplary modes of administration include topical application, intranasal, inhalation, transmucosal, transdermal, enteral (e.g. oral, rectal), parenteral (e.g. intravenous, subcutaneous, intradermal, intramuscular) administrations, as well as direct tissue or organ injections.
Injectables can be prepared in conventional forms, either as liquid solutions or suspensions, solid forms suitable for the preparation of solution or suspensions in liquid prior to injection, or as emulsions. Alternatively, one may administer the above AAV9-based recombinant virus of the present invention in a local rather than systemic manner, for example in a depot or sustained-release formulation.
The AAV9-based recombinant virus is introduced into an organism in an effective amount. The AAV9-based recombinant virus is preferably introduced into an organism in a biologically effective amount. A “biologically effective” amount of the recombinant virus is an amount that is sufficient to cause infection (or transduction) and expression of the nucleic acid sequence in the cell. If the virus is administered to a cell in vivo (e.g. the virus is administered to a subject, as described below), a “biologically-effective” amount of the viral vector is an amount that is sufficient to cause the transduction and expression of the nucleic acid sequence in the target cell.
Dosages of the above AAV9-based recombinant virus of the invention will depend on the mode of administration, the particular viral vector, and they can be determined in a routine manner. Exemplary doses for achieving therapeutic effects are viral titers of at least about 105, 106, 107, 108, 109, 1010, 1011, 1012, 10 13, 1014, 1015, 1016 transducing units or more, preferably about 109 to 1015 transducing units, yet more preferably 1014 transducing units per kilogram.
The cell for administering the above AAV9-based recombinant virus of the invention may be a cell of any type, including but not limited to motor neurons or other tissues of the nervous system, epithelial cells (e.g. skin, respiratory and gut epithelial cells), hepatic cells, muscle cells, pancreatic cells (including islet cells), hepatic cells, spleen cells, fibroblasts, endothelial cells, and the like.
The above AAV9-based recombinant virus of the invention is not used to modify the genetic integrity of human germ line cells.
The following examples are provided for better understanding of the invention. These examples are for purposes of illustration only and are not to be construed as limiting the scope of the invention in any manner.
All publications, patents, and patent applications cited in this specification are incorporated herein by reference. Although the foregoing invention has been described in some detail by way of illustration and example for purposes of clarity of understanding, it will be readily apparent to those of ordinary skill in the art in light of the teachings of this invention that certain changes and modifications may be made thereto without departing from the spirit or scope of the appended embodiments.
Standard methods were used to manipulate DNA as described in Sambrook, J. et al, Molecular cloning: A laboratory manual; Cold Spring Harbor Laboratory Press, Cold Spring Harbor, New York, 1989. The molecular biological reagents were used according to the manufacturer protocols. Briefly, plasmid DNA was produced for further manipulation in E. coli cells grown under selective antibiotic pressure so that the plasmids were not lost in the cell population. We isolated the plasmid DNA from cells using commercial kits, measured the concentration, and used it for cloning by restriction endonuclease treatment or PCR amplification. The DNA fragments were ligated to each other using ligases and transformed into bacterial cells for the selection of clones and further production. All resulting genetic constructs were confirmed by restriction patterns and complete Sanger sequencing.
Desired gene segments were prepared from oligonucleotides made by chemical synthesis. Gene segments of 300 to 1000 bp long, which were flanked by unique restriction sites, were collected by renaturing oligonucleotides on top of each other, followed by PCR amplification from border primers. As a result, a mixture of fragments was produced, including the desired one. The fragments were cloned at restriction sites into intermediate vectors, following which the DNA sequences of the subcloned fragments were confirmed by DNA sequencing.
DNA sequences were determined by Sanger sequencing. DNA and protein sequences were analyzed and sequence data was processed in SnapGene Viewer 4.2 or higher for sequence creation, mapping, analysis, annotation and illustration.
The experiments used HEK293 (Human Embryonic Kidney clone 293) and U-87 MG (human glioblastoma) cell lines. The cells were cultured under standard conditions at 37° C. and 5% CO2, on a DMEM complete culture medium supplemented with 10% FBS and an antibiotic. To culture HSMCs, the culture plastic was pre-coated with collagen (Gibco). Cells were subcultured upon reaching 80-90% confluence. Cell viability was assessed using either Trypan Blue stain and a hemocytometer or PI stain and flow cytometry.
A commercial siRNA specific for the SMN1 gene was ordered from the manufacturer (ThermoFisher Scientific) along with a non-specific control.
Cell lines were inoculated the day before transfection into 6-well plates such that they reached 70-80% confluence by the time of transfection. Transfection was performed using commercial lipofection kits according to the manufacturer's protocol. 24 h following transfection, transduction was performed (see below). 120 h following transduction, the cells were treated with trypsin solutions or similar, removed from the substrate, washed in a phosphate buffer, and collected for further analysis of expression of target genes and proteins. Enzyme immunoassay (ELISA) was performed to control the level of SMN protein knockdown.
All samples were analyzed with 3 experimental replicates.
Expression of SMN1 at the mRNA level and expression of miR-23a was measured using quantitative PCR. Briefly, we used primers and a sample that are specific for the nucleotide sequence encoding the SMN1 protein. For miR-23a, we used a commercial kit for quantitative PCR specific for processed miR-23a (Thermo Fisher Scientific). Primers and a sample specific for the GAPDH household gene were used to control the initial RNA levels. Calibration curves were plotted for each set of primers and samples using a known copy number of linearized plasmid DNA comprising the amplified sequence of the corresponding gene. Expression was analyzed by determining, using the calibration curves, the copy number of SMN1 and GAPDH in each sample, following which we normalized the copy number of SMN1 to 10,000 copies of GAPDH. The resulting values were compared for different samples within the same experiment.
Thermo Fisher Scientific kit was used to determine the amount of total protein. Cellular precipitates were lysed, the resulting lysates were introduced into microplate wells together with standard dilutions of BSA at a known concentration. A working reagent was added to the samples, and the samples were incubated. At the end of incubation, we measured absorption at a wavelength of 562 nm on a microplate reader. Concentration of total protein in test samples was calculated according to BSA standard curve. Next, the lysates were diluted to a total protein concentration of 10 μg/ml.
Content of SMN protein in cells was assessed by enzyme immunoassay (ELISA) using a commercial Abcam kit according to the manufacturer's instructions. Microplate wells coated with anti-SMN antibodies were loaded with test samples and standards at known concentrations. Following incubation and washing, SMN-specific polyclonal antibodies for detection were added to each well, the samples were incubated and washed. Secondary antibodies conjugated with horseradish peroxidase were added, and the samples were incubated. Excess of reagents was washed off and TMB substrate was added. Following a short-term incubation, the enzymatic reaction was stopped with stop reagent. Optical density of the yellow-colored product was measured by spectrophotometry at a wavelength of 450 nm. Amount of SMN in test samples was determined using the calibration plot of optical density versus concentration of SMN in the standards.
Senataxin protein is a polyfunctional enzyme involved in the resolution of DNA-RNA structures called R-loops, which occur during transcription in case of absent or underexpressed SMN protein. The literature has reported a direct correlation between SMN and Senataxin expression levels, and indirect activation of Senataxin is one of the functions of SMN. In this regard, change in Senataxin expression was used as a functional test for SMN.
Senataxin expression level was determined by Western blot. Briefly, cells were lysed with RIPA buffer supplemented with protease inhibitor cocktail following experimental exposure (transfection, transduction, incubation), thereby obtaining protein lysate samples. The samples were applied onto a 10% polyacrylamide denaturing gel, thereafter the proteins were transferred onto PVDF membrane.
Membrane was incubated for 1 hour in 5% bovine serum albumin (BSA) solution in TBS-T buffer, thereafter the BSA solution was replaced with 1% BSA solution in TBS-T supplemented with primary antibodies specific for Senataxin. After 2 hours of incubation, the membrane was washed 3 times with 1% BSA solution in TBS-T and secondary antibody solution in TBS-T supplemented with 1% BSA was added. We used secondary antibodies conjugated with enzyme horseradish peroxidase.
Secondary antibodies were washed 3 times with 1% BSA solution in TBS-T, thereafter the protein signal was detected at the membrane using a chemiluminescence substrate and a gel imaging system. Resulting images were saved in digital format and the signal intensity was analyzed using the software of the gel imaging system.
The protein signal of the vinculin household gene was used as a control for normalization. Staining was carried out in a similar fashion.
To assemble AAV particles containing the SMN1 gene or GFP control gene, we used HEK293 packaging cells, into which 3 plasmids were transfected using polyethylenimine as follows:
After 72 hours, the cells were lysed and the viral particles were purified and concentrated using filtration and chromatography methods. The titer of the viral particles was determined by quantitative PCR with primers and a sample that were specific for the region of the recombinant viral genome and expressed as the copy number of viral genomes per 1 ml.
U-87 cell line was inoculated similarly to transfection experiments, transfection with siRNA was carried out, following which the product with viral particles was added and, after 120 h, the cells were analyzed. Transduction efficiency was estimated by measuring the percentage of GFP+ cells.
The cultures being used were pre-tested with the check of the transduction efficiency. Briefly, the AAV9-GFP viral product was transduced into the cell lines in different ratios of cells and viral particles. The ratio of viral particle number to cell number is referred to as multiplicity of infection (MOI). The MOI of the AAV9-GFP virus ranged from 50,000 to 1,000,000. As a result, the optimal MOI of 400,000 was chosen for the U-87 line. Further U-87 transduction works were carried out at this MOI for all viruses.
Following transduction, gene and protein expression was analyzed as described above.
All samples were analyzed with 3 experimental replicates.
Viral particles AAV9-SMN1, AAV9-GFP, AAV9-SMN1-miR-23a and AAV9-GFP-miR-23a were used for injection into SMA model mice. These mice do not express the mouse Smn gene, but have in the genome thereof one copy of the human SMN2 gene and one copy of the human SMN1 gene with exon 7 missing (SMN1Δ7). Without intervention or with a placebo injection, such mice are born, but poorly gain weight after birth and die after an average of 21 days.
Mice of the model line were genotyped on day 1 following birth, thereafter mice that contained no copy of the Smn gene were injected systemically (in the tail vein) with either a placebo (a solution that does not contain viral particles, but contains a buffer for dilution thereof), or one of the viruses at a dose of 3.2×1014 vg/kg of body weight. Thereafter, the animals were kept under standard conditions and weighed daily, and survival curves were also plotted. 90 days following injection, survived animals were sacrificed for tissue analysis and the experiment was terminated.
SMN1 gene sequence was produced by amplification with specific primers with cDNA synthesized based on total RNA of HEK293 cells, or assembled from a series of oligonucleotides (see above). During the amplification process, the Kozak sequence and ClaI restriction site were added from the 5′-end of the gene, and the XbaI restriction site was added from the 3′-end. The sequence of the SMN1 gene was thereafter cloned by the restriction-ligase method at the ClaI and XbaI sites into a commercial construct pAAV-GFP Control plasmid (VPK-402) from CellBiolab (USA), with substitution of the GFP gene with SMN1, thereby producing the pAAV-SMN1 construct.
An additional miR-23a expression cassette was inserted into the plasmids pAAV-GFP and pAAV-SMN1 that were produced previously. The additional miR-23a expression cassette consists of a promoter, a gene of interest (miR-23a, produced using PCR from genomic DNA of Huh7 cell line), and a polyadenylation signal. Target vectors were produced by linearizing at the Pm1I site the recipient vectors (pAAV-GFP, pAAV-SMN1) followed by incorporation of the expression cassette with miR-23a at the cohesive ends.
The final vector contains all the necessary elements for expression and assembly of the gene as part of the recombinant AAV genome:
Plasmids pAAV-SMN1, pAAV-GFP, pAAV-SMN1-miR-23a, pAAV-GFP-miR-23a along with other plasmids required for producing recombinant AAV viral particles (see above) were used for the AAV production bioprocess. The serotype used was wild-type AAV9 or that having various mutations. In all cases, the properties of viral particles were compared only as long as the serotype used and capsid mutations, if any, were identical. All serotypes based on AAV9, either that of wild type or with mutations, are hereinafter referred to as AAV9 without specifying mutations.
Bioprocess resulted in recombinant viral particles designated as AAV9-SMN1, AAV9-GFP, AAV9-SMN1-miR-23a, AAV9-GFP-miR-23 a. Following determining the titers of viral particles, all 3 products having the same MOI of 400,000 were used to transduce permissive cells, U-87, pre-transfected (24 hours before) with siRNA against SMN1 or siRNA having a non-specific sequence. Further analysis was performed only as long as the GFP transduction efficiency was at least 70%.
Following successful transduction, the cells were removed from the substrate, washed in a phosphate buffer, and the expression of SMN1 was analyzed at the mRNA and SMN protein levels as described above. It was shown that when transducing with viruses AAV9-SMN1 and AAV9-SMN1-miR-23a, SMN1 expression exceeded the endogenous mRNA level (Table 1,
Also, we determined miR-23a expression level in samples post-transduction. A significant excess of miR-23a expression was shown in samples transduced with viruses AAV9-SMN1-miR-23a, AAV9-GFP-miR-23a. In other samples, miR-23a expression did not differ from endogenous one. Transfection of siRNA against SMN1 did not affect miR-23a expression (Table 3,
It should be noted that changes in SMN1 expression with knockdown or reconstitution using the viral product did not affect miR-23a expression. Also, miR-23a overexpression had no effect on SMN1 expression.
The above design of experiment of SMN1 knockdown and reconstitution of expression thereof using transduction with viral particles was used to evaluate the functional cooperation of SMN1 and miR-23a in vitro. Among the many functions of SMN1, the protein is responsible for correct resolution of DNA-RNA duplexes that occur during transcription. Further, the main protein involved in resolution of duplexes is Senataxin, which, according to the literature, is indirectly activated by SMN. Thus, activation of Senataxin may be considered a functional test of SMN activity in cells.
Senataxin expression level in samples was determined by Western blot. It was found that with knockdown of SMN expression, Senataxin expression was decreased by about 2 times, and with reconstitution of SMN expression with virus AAV9-SMN1, it reconstituted to endogenous level. We observed a trend towards a slight increase in Senataxin expression in the case of SMN knockdown during transduction with control virus AAV9-GFP-miR-23a, but it was not statistically significant. It is important to note that in case of transduction with virus AAV9-SMN1-miR-23a, Senataxin expression was not only reconstituted to the endogenous level against the background of endogenous SMN knockdown, but also increased statistically significantly by 1.5-2 times (Table 4,
This confirms the synergistic effect of SMN and miR- 23a on Senataxin expression, exceeding the effect of both miR-23a and SMN separately on the regulation of the gene.
Viral products AAV9-SMN1 and AAV9-SMN1-miR-23a were injected into the tail vein of SMA model mice on day 1 following birth at a dose of 3.6×1014 vg/kg. We used a solution without viral particles (placebo) and a group of wild-type sibling mice that did not have the SMA phenotype due to their expression of Smn. Next, survival functions of mice in all groups were built. Upon reaching the point where it was possible to determine the median survival times for all groups, the medians were calculated.
The SMA phenotype was most corrected in the group injected with the virus AAV9-SMN1-miR-23a. Median survival time for the group was 55 days. This result was significantly different from the group injected with the virus AAV9-SMN1, where the median survival time was 21 days. For placebo-injected mice, the median was 16 days following birth (
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021102051 | Jan 2021 | RU | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/RU2022/000025 | 1/28/2022 | WO |
