Patent Application
20240026320
This application contains, as a separate part of the disclosure, a Sequence Listing in computer readable form (Filename: 2020-154_Seqlisting.txt; Size: 13,124 bytes; Created: Dec. 2, 2021), which is incorporated by reference in its entirety.
The disclosure is directed to the use of genome editing to both modify expression of myosin heavy chain (MHC) genes associated with cardiomyopathy.
Cardiomyopathies are heart muscle disorders which represent a heterogeneous group of diseases that often lead to progressive heart failure with significant morbidity and mortality. Common symptoms include dyspnea, exercise and activity intolerance and peripheral oedema, and risks of having dangerous forms of irregular heart rate and sudden cardiac death are increased. The most common form of cardiomyopathy is dilated cardiomyopathy. Dilated cardiomyopathy is a heart muscle disorder characterized by dilatation and systolic dysfunction of the left or both ventricles (Elliott, P., Andersson, B., Arbustini. E., Bilinska, Z., Cecchi, F., Charron, P., Dubourg, O., Ktihl, U., Maisch, B., McKenna, W. J., et al. (2008) Classification of the cardiomyopathies: a position statement from the European society of cardiology working group on myocardial and pericardial diseases. Eur. Heart J., 29, 270-276). The ventricular walls become thin and stretched, compromising cardiac contractility and ultimately resulting in poor left ventricular function. Other forms of cardiomyopathy include hypertrophic, arrhythmogenic and restrictive. Chronic or acute coronary artery disease can also lead to ischemic cardiomyopathy and cause heart failure.
Protein coding mutations in over 100 genes have been linked to autosomal dominant cardiomyopathy, which leads to heart failure and significant burden1-3. A well-recognized clinical feature of genetic cardiomyopathy is its variable phenotypic expression. Genetic cardiomyopathy demonstrates an age-dependent penetrance, variable expressivity, and variable clinical presentations, even in patients sharing identical primary mutations4,5. Protein coding variants have been described as altering the phenotypic expression of primary cardiomyopathy-causing mutations5-7. However, the contribution of noncoding variation as modifiers of the clinical presentation of cardiomyopathy has been less well investigated.
Noncoding regions of the genome harbor important regulatory sequences that control the expression of genes through both distal enhancers and proximal gene promoters8. ChIP-seq, ATAC-seq, and CAGE-seq can mark genomic regions as having regulatory function, but do not provide information on their gene target. Chromatin conformation assays evaluate genomic three-dimensional organization and link enhancers to their target genes. However, as enhancer function is dependent on tissue-specific transcription factors, assays for enhancer function or targets require the context of relevant tissues/cells.
In one aspect, described herein is a method for editing the myosin heavy chain 7 (MHY7) gene in a cell comprising introducing into the cell one or more deoxyribonucleic acid (DNA) endonucleases to induce one or more double stranded breaks (DSBs) within chr14:23870150-23924866 as designated in the human genome browser, build 38 (hg38), of the MYH7 gene that results in deletion of an enhancer region of the MYH7 gene. In some embodiments, the method results in decreased MYH7 expression and increased MYH6 expression in the cell, relative to a cell into which the DNA endonuclease was not introduced.
In some embodiments, the enhancer region is upstream (e.g., within 500 bp) of the MYH6 gene. In some embodiments, the enhancer region is within the MYH6 gene. In some embodiments, the enhancer region is downstream (e.g., within 500 bp) of the MYH7 gene. In some embodiments, the enhancer region is MYH7-C6, MYH7-C3, MYH7-C4 or MYH7-C5. In some embodiments, the enhancer region MYH7-C3 is deleted from the MYH7 gene.
In some embodiments, the one or more DNA endonucleases is a Cas1, Cas1B, Cas2, Cas3, Cas4, Cas5, Cas6, Cas7, Cas8, Cas9 (also known as Csn1 and Csx12), Cas100, Csy1, Csy2, Csy3, Cse1, Cse2, Csc1, Csc2, Csa5, Csn2, Csm2, Csm3, Csm4, Csm5, Csm6, Cmr1, Cmr3, Cmr4, Cmr5, Cmr6, Csb1, Csb2, Csb3, Csx17, Csx14, Csx10, Csx16, CsaX, Csx3, Csx1, Csx15, Csf1, Csf2, Csf3, Csf4, or Cpf1 endonuclease; or a homolog thereof.
In some embodiments, the method comprises introducing into the cell one or more polynucleotides encoding the one or more DNA endonucleases.
In some embodiments, the method comprises introducing into the cell one or more ribonucleic acids (RNAs) encoding the one or more DNA endonucleases.
In some embodiments, the method further comprises introducing into the cell one or more guide ribonucleic acids (gRNAs). In some embodiments, the one or more guide RNAs (gRNAs) comprise a nucleotide sequence set forth in SEQ ID NOs: 1-68.
In some embodiments, the one or more DNA endonucleases is pre-complexed with one or more gRNAs. In some embodiments, the DNA endonuclease and one or more guide RNAs are delivered by a viral vector. Exemplary viral vectors include, but are not limited to, a herpes virus vector, an adeno-associated virus (AAV) vector, an adeno virus vector, or a lentiviral vector. In some embodiments, the viral vector is an adeno-associated virus (AAV) vector. In some embodiments, the AAV vector is recombinant AAV5, AAV6, AAV8, AAV9, or AAV7.
In another aspect, described herein is a method of improving heart function in a subject suffering from cardiomyopathy comprising administering to the subject an agent that both increases myosin heavy chain 6 (MYH6) gene expression and decreases myosin heavy chain 7 (MYH7) gene expression in a cardiac cell of the subject. In some embodiments, the agent is one or more deoxyribonucleic acid (DNA) endonucleases to effect one or more double stranded breaks (DSBs) within or near enhancer regions of the MYH7 gene of the MYH6 gene that results in deletion of one or more enhancer regions of the MYH7 gene.
In another aspect, described herein is a method for editing the LMNA gene in a cell by genome editing comprising introducing into the cell one or more deoxyribonucleic acid (DNA) endonucleases to effect one or more double stranded breaks (DSBs) within or near chr1:155937201-156100640 as designated in the human genome browser, build 38 (hg38) of the LMNA gene that results in deletion of one or more enhancer regions of the LMNA gene. In some embodiments, the one or more enhancer regions is LMNA-C1, LMNA-C2, LMNA-C3, LMNA-C4, LMNA-C5, or LMNA-C6.
In another aspect, described herein is a composition comprising one or more guide RNAs (gRNAs) comprise a nucleotide sequence set forth in SEQ ID NOs: 1-68 and a pharmaceutically acceptable carrier, diluent or adjuvant.
Inherited cardiomyopathy associates with a range of phenotypic expression. As described in the Examples, epigenomic profiling from multiple sources was superimposed, including promoter-capture chromatin conformation information, to identify candidate enhancer regions for two cardiomyopathy genes, MYH7 and LMNA. Enhancer function was validated in human cardiomyocytes derived from induced pluripotent stem cells and revealed enhancer regions implicated the switch of MYH6 and MYH7 expression. By querying human genomic variation, multiple sequence changes were identified that modified enhancer function by creating or interrupting transcription factor binding sites. rs875908, which is 2 KB 5′ of MYH7, associated with longitudinal clinical features of cardiomyopathy in a biobank with clinical imaging and genetic data.
Myosin Heavy Chain Genes, MYH7 and MYH6
Mutations in MYH7 are a common cause of hypertrophic cardiomyopathy while mutations in LMNA are a common cause of dilated cardiomyopathy with arrhythmias4,9. MYH7 encodes β-myosin heavy chain (MHC), which is the major left ventricular myosin heavy chain in the adult human.
In humans, both MYH7 (α-MHC) and MYH6 (β-MHC) are expressed in myocardium and cause cardiomyopathy when mutated (Carniel et al., Circulation 112:-54-59, 2005; Kamisago et al., NEJM, 343:1688-1696, 2000). These genes are in tandem on chromosome 14, with MYH6 located 5.3 kb downstream of MYH7, and their expression is developmentally regulated. MYH6 is mainly expressed in embryonic heart, whereas MYH7 becomes the predominant adult isoform (Lowes et al., J. Clin. Invest., 100:2315-2324, 1997).
An integrative analysis was used that relied on >20 publicly-available heart enhancer function and enhancer target datasets to identify MYH7 and LMNA left ventricle enhancer regions. The activity of these regions was confirmed using reporter assays and CRISPR-mediated deletion in human cardiomyocytes derived from induced pluripotent stem cells (iPSC-CMs). These regulatory regions contained sequence variants within transcription factor binding sites that altered enhancer function. Extending this strategy genome-wide, an enhancer modifying variant was identified upstream of MYH7. This common variant correlated with MYH7 expression in the GTEx eQTL dataset. Finally, the variant was also determined to be correlated with a more dilated left ventricle over time. These findings link noncoding enhancer variation to cardiomyopathy phenotypes and provide direct evidence of the importance of genetic background.
In one aspect, described herein is a method for editing the MHY7 gene in a cell comprising introducing into the cell one or more deoxyribonucleic acid (DNA) endonucleases to induce one or more double stranded breaks (DSBs) within or near chr14:23870150-23924866 as designated in the human genome browser, build 38 (hg38), that results in deletion of an enhancer region of the MYH7 gene. In some embodiments, the enhancer region is upstream (e.g., within 500 bps) of the MYH6 gene. In some embodiments, the enhancer region is upstream within 10 bp, 20 bp, 30 bp, 40 bp, 50 bp, 60 bp, 70 bp, 80 bp, 90 bp, 100 bp, 125 bp, 150 bp, 175 bp, 200 bp, 225 bp, 250 bp, 275 bp, 300 bp, 325 bp, 350 bp, 375 bp, 400 bp, 425 bp, 450 bp, 475 bp or 500 bp of the MYH6 gene. In some embodiments, the enhancer region is MYH7-C1 or MYH7-C2. In some embodiments, the enhancer region is downstream of the MYH7 gene (e.g., within 500 bps). In some embodiments, the enhancer region is downstream within 10 bp, 20 bp, 30 bp, 40 bp, 50 bp, 60 bp, 70 bp, 80 bp, 90 bp, 100 bp, 125 bp, 150 bp, 175 bp, 200 bp, 225 bp, 250 bp, 275 bp, 300 bp, 325 bp, 350 bp, 375 bp, 400 bp, 425 bp, 450 bp, 475 bp or 500 bp of the MYH7 gene. In some embodiments, the enhancer region is MYH7-C6, MYH7-C3, MYH7-C5 or MYH7-C4. In some embodiments, the enhancer region MYH7-C3 is deleted from the MYH7 gene. Locations of the various enhancer regions of the MYH7 gene are provided below in Table A.
In some embodiments, the methods result in decreased MYH7 expression and increased MYH6 expression in the cell, compared to a cell that does not comprise the endonuclease.
LMNA Gene
The LMNA gene encodes nuclear lamin A and nuclear lamin C, intermediate filament proteins that are components of the nuclear lamina. Most disease-causing LMNA mutations affect the heart, causing a dilated cardiomyopathy, with or without skeletal muscle involvement (Lu et al., Disease Models and Mechanisms, 4:562-568, 2011).
In another aspect, described herein is a method for editing the LMNA gene in a cell by genome editing comprising introducing into the cell one or more deoxyribonucleic acid (DNA) endonucleases to effect one or more double stranded breaks (DSBs) within or near chr1:155937201-156100640 as designated in the human genome browser, build 38 (hg38) of the LMNA gene that results in deletion of one or more enhancer regions of the LMNA gene. In some embodiments, the one or more enhancer regions is LMNA-C1, LMNA-C2, LMNA-C3, LMNA-C4, LMNA-C5, or LMNA-C6. Locations of the various enhancer regions of the LMNA gene are provided below in Table B.
CRISPR Endonuclease System
A CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) genomic locus can be found in the genomes of many prokaryotes (e.g., bacteria and archaea). In prokaryotes, the CRISPR locus encodes products that function as a type of immune system to help defend the prokaryotes against foreign invaders, such as virus and phage. There are three stages of CRISPR locus function: integration of new sequences into the locus, biogenesis of CRISPR RNA (crRNA), and silencing of foreign invader nucleic acid. Five types of CRISPR systems (e.g., Type I, Type II, Type III, Type U, and Type V) have been identified.
A CRISPR locus includes a number of short repeating sequences referred to as “repeats.” The repeats can form hairpin structures and/or comprise unstructured single-stranded sequences. The repeats usually occur in clusters and frequently diverge between species. The repeats are regularly interspaced with unique intervening sequences referred to as “spacers,” resulting in a repeat-spacer-repeat locus architecture. The spacers are identical to or have high homology with known foreign invader sequences. A spacer-repeat unit encodes a crisprRNA (crRNA), which is processed into a mature form of the spacer-repeat unit. A crRNA comprises a “seed” or spacer sequence that is involved in targeting a target nucleic acid (in the naturally occurring form in prokaryotes, the spacer sequence targets the foreign invader nucleic acid). A spacer sequence is located at the 5′ or 3′ end of the crRNA.
A CRISPR locus also comprises polynucleotide sequences encoding CRISPR Associated (Cas) genes. Cas genes encode endonucleases involved in the biogenesis and the interference stages of crRNA function in prokaryotes. Some Cas genes comprise homologous secondary and/or tertiary structures. In some embodiments, the DNA endonucleases is a Cas1, Cas1B, Cas2, Cas3, Cas4, Cas5, Cas6, Cas7, Cas8, Cas9 (also known as Csn1 and Csx12), Cas100, Csy1, Csy2, Csy3, Cse1, Cse2, Csc1, Csc2, Csa5, Csn2, Csm2, Csm3, Csm4, Csm5, Csm6, Cmr1, Cmr3, Cmr4, Cmr5, Cmr6, Csb1, Csb2, Csb3, Csx17, Csx14, Csx10, Csx16, CsaX, Csx3, Csx1, Csx15, Csf1, Csf2, Csf3, Csf4, or Cpf1 endonuclease; or a homolog thereof.
Examples of various Cas9 proteins and Cas9 guide RNAs (as well as information regarding requirements related to protospacer adjacent motif (PAM) sequences present in targeted nucleic acids) can be found in the art, for example, see Jinek et al., Science. 2012 Aug. 17; 337(6096):816-21; Chylinski et al., RNA Biol. 2013 May; 10(5):726-37; Ma et al., Biomed Res Int. 2013; 2013:270805; Hou et al., Proc Natl Acad Sci USA. 2013 Sep. 24; 110(39):15644-9; Jinek et al., Elife. 2013; 2:e00471; Pattanayak et al., Nat Biotechnol. 2013 September; 31(9):839-43; Qi et al., Cell. 2013 Feb. 28; 152(5):1173-83; Wang et al., Cell. 2013 May 9; 153(4):910-8; Auer et al., Genome Res. 2013 Oct. 31; Chen et al., Nucleic Acids Res. 2013 Nov. 1; 41(20):e19; Cheng et al., Cell Res. 2013 October; 23(10):1163-71; Cho et al., Genetics. 2013 November; 195(3):1177-80; DiCarlo et al., Nucleic Acids Res. 2013 April; 41(7):4336-43; Dickinson et al., Nat Methods. 2013 October; 10(10):1028-34; Ebina et al., Sci Rep. 2013; 3:2510; Fujii et al., Nucleic Acids Res. 2013 Nov. 1; 41(20):e187; Hu et al., Cell Res. 2013 November; 23(11):1322-5; Jiang et al., Nucleic Acids Res. 2013 Nov. 1; 41(20):e188; Larson et al., Nat Protoc. 2013 November; 8(11):2180-96; Mali et al., Nat Methods. 2013 October; 10(10):957-63; Nakayama et al., Genesis. 2013 December; 51(12):835-43; Ran et al., Nat Protoc. 2013 November; 8(11):2281-308; Ran et al., Cell. 2013 Sep. 12; 154(6):1380-9; Upadhyay et al., G3 (Bethesda). 2013 Dec. 9; 3(12):2233-8; Walsh et al., Proc Natl Acad Sci USA. 2013 Sep. 24; 110(39):15514-5; Xie et al., Mol Plant. 2013 Oct. 9; Yang et al., Cell. 2013 Sep. 12; 154(6):1370-9; Briner et al., Mol Cell. 2014 Oct. 23; 56(2):333-9; and U.S. patents and patent applications: U.S. Pat. Nos. 8,906,616; 8,895,308; 8,889,418; 8,889,356; 8,871,445; 8,865,406; 8,795,965; 8,771,945; 8,697,359; 20140068797; 20140170753; 20140179006; 20140179770; 20140186843; 20140186919; 20140186958; 20140189896; 20140227787; 20140234972; 20140242664; 20140242699; 20140242700; 20140242702; 20140248702; 20140256046; 20140273037; 20140273226; 20140273230; 20140273231; 20140273232; 20140273233; 20140273234; 20140273235; 20140287938; 20140295556; 20140295557; 20140298547; 20140304853; 20140309487; 20140310828; 20140310830; 20140315985; 20140335063; 20140335620; 20140342456; 20140342457; 20140342458; 20140349400; 20140349405; 20140356867; 20140356956; 20140356958; 20140356959; 20140357523; 20140357530; 20140364333; and 20140377868; all of which are hereby incorporated by reference in their entirety.
crRNA biogenesis in a Type II CRISPR system in nature requires a trans-activating CRISPR RNA (tracrRNA). The tracrRNA is modified by endogenous RNaseIII, and then hybridizes to a crRNA repeat in the pre-crRNA array. Endogenous RNaseIII is recruited to cleave the pre-crRNA. Cleaved crRNAs are subjected to exoribonuclease trimming to produce the mature crRNA form (e.g., 5′ trimming). The tracrRNA remains hybridized to the crRNA, and the tracrRNA and the crRNA associate with a site-directed polypeptide (e.g., Cas9). The crRNA of the crRNA-tracrRNA-Cas9 complex guides the complex to a target nucleic acid to which the crRNA can hybridize. Hybridization of the crRNA to the target nucleic acid activates Cas9 for targeted nucleic acid cleavage. The target nucleic acid in a Type II CRISPR system is referred to as a protospacer adjacent motif (PAM). In nature, the PAM facilitates binding of a site-directed polypeptide (e.g., Cas9) to the target nucleic acid. Type II systems (also referred to as Nmeni or CASS4) are further subdivided into Type II-A (CASS4) and II-B (CASS4a). Jinek et al., Science, 337(6096):816-821 (2012) showed that the CRISPR/Cas9 system is useful for RNA-programmable genome editing, and International Patent Application Publication Number WO2013/176772 (incorporated herein by reference) provides numerous examples and applications of the CRISPR/Cas endonuclease system for site-specific gene editing.
Exemplary CRISPR/Cas polypeptides include the Cas9 polypeptides in FIG. 1 of Fonfara et al., Nucleic Acids Research, 42: 2577-2590 (2014) (incorporated herein by reference). The CRISPR/Cas gene naming system has undergone extensive rewriting since the Cas genes were discovered.
Cas9 polypeptides can introduce double-strand breaks or single-strand breaks in nucleic acids, e.g., genomic DNA. The double-strand break can stimulate a cell's endogenous DNA-repair pathways (e.g., homology-dependent repair (HDR) or non-homologous end joining (NHEJ) or alternative non-homologous end joining (A-NHEJ) or microhomology-mediated end joining (MMEJ)). NHEJ can repair cleaved target nucleic acid without the need for a homologous template. This can sometimes result in small deletions or insertions (indels) in the target nucleic acid at the site of cleavage, and can lead to disruption or alteration of gene expression. HDR can occur when a homologous repair template, or exogenous nucleic acid, is available.
In some embodiments, the DNA endonuclease is introduced to the cell as a protein (i.e., a protein-based system). Typically, the cell is treated chemically, electrically, or mechanically to allow Cas9 nuclease entry into the cell. Alternatively, in some embodiments, the endonuclease is introduced to the cell as a nucleic acid (e.g., DNA or mRNA) under conditions which allow production of the nuclease. Guide RNA also is introduced into the cell.
In some embodiments, the methods described herein comprise introducing one or more guide RNAs into the cell. A genome-targeting RNA is referred to as a “guide RNA” or “gRNA” herein. A guide RNA comprises at least a spacer sequence that hybridizes to a target nucleic acid sequence of interest, and a CRISPR repeat sequence. In Type II systems, the gRNA also comprises a tracrRNA sequence. In the Type II guide RNA, the CRISPR repeat sequence and tracrRNA sequence hybridize to each other to form a duplex. The duplex binds a site-directed polypeptide, such that the guide RNA and site-direct polypeptide form a complex. The guide RNA provides target specificity to the complex by virtue of its association with the Cas9 nuclease. The guide RNA thus directs the activity of the Cas9 nuclease.
Exemplary gRNA for use in the methods described herein include, but are not limited to, the gRNAs provided in Table 1 in Example 1.
In some embodiments, the methods described herein comprise delivering the endonuclease and one or more gRNAs to the cell by a viral vector. Any of the expression vectors described herein may be used to deliver endonuclease-encoding nucleic acid into the cell; in many aspects, the expression vector is a plasmid. Non-limiting exemplary viral vectors include adeno-associated virus (AAV) vector, lentivirus vectors, adenovirus vectors, helper dependent adenoviral vectors (HDAd), herpes simplex virus (HSV-1) vectors, bacteriophage T4, baculovirus vectors, and retrovirus vectors. In some embodiments, the viral vector may be an AAV vector. In some embodiments, the viral vector is AAV2, AAV3, AAV3B, AAV5, AAV6, AAV6.2, AAV7, AAVrh.64R1, AAVhu.37, AAVrh.8, AAVrh.32.33, AAV8, AAV9, AAVrh10, or AAVLK03. In other embodiments, the viral vector may a lentivirus vector.
In some embodiments, a viral vector comprises one or more transcription and/or translation control elements. Depending on the host/vector system utilized, any of a number of suitable transcription and translation control elements, including constitutive and inducible promoters, transcription enhancer elements, transcription terminators, etc., may be used. In some embodiments, the promoter may be constitutive, inducible, or tissue-specific. In some embodiments, the promoter may be a constitutive promoter. Non-limiting exemplary constitutive promoters include cytomegalovirus immediate early promoter (CMV), simian virus (SV40) promoter, adenovirus major late (MLP) promoter, Rous sarcoma virus (RSV) promoter, mouse mammary tumor virus (MMTV) promoter, phosphoglycerate kinase (PGK) promoter, elongation factor-alpha (EF1a) promoter, ubiquitin promoters, actin promoters, tubulin promoters, immunoglobulin promoters, a functional fragment thereof, or a combination of any of the foregoing. In some embodiments, the promoter may be a CMV promoter. In some embodiments, the promoter may be a truncated CMV promoter. In other embodiments, the promoter may be an EF1a promoter. In some embodiments, the promoter may be an inducible promoter. Non-limiting exemplary inducible promoters include those inducible by heat shock, light, chemicals, peptides, metals, steroids, antibiotics, or alcohol. In some embodiments, the inducible promoter may be one that has a low basal (non-induced) expression level, such as, e.g., the Tet-On® promoter (Clontech).
The Cas9 nuclease-encoding nucleic acid is operably linked to a promoter that drives protein expression. For expressing small RNAs, including guide RNAs used in connection with Cas or Cpf1 endonuclease, promoters such as RNA polymerase III promoters, including for example U6 and H1, can be advantageous. Suitable promoters, as well as parameters for enhancing the use of such promoters, are known in art, and additional information and approaches are regularly being described; see, e.g., Ma, H. et al., Molecular Therapy—Nucleic Acids 3, e161 (2014) doi:10.1038/mtna.2014.12.
In some embodiments, the nucleotide sequence encoding the guide RNA may be located on the same vector comprising the nucleotide sequence encoding the endonuclease. In some embodiments, expression of the guide RNA and of the endonuclease may be driven by their own corresponding promoters. In some embodiments, expression of the guide RNA may be driven by the same promoter that drives expression of the endonuclease. In some embodiments, the guide RNA and the endonuclease transcript may be contained within a single transcript. For example, the guide RNA may be within an untranslated region (UTR) of the endonuclease transcript. In some embodiments, the guide RNA may be within the 5′ UTR of the transcript. In other embodiments, the guide RNA may be within the 3′ UTR of the transcript.
Treatment Methods
The Examples provided herein demonstrate that deletion of the MYH7-C3 enhancer region reduced MYH7 expression in iPSC-CMs, and, correspondingly, deletion of the MYH7-C3 enhancer increased MYH6 expression, resulting in an αMHC/βMHC ratio that increased heart function in engineered heart tissues. Thus, in another aspect, the disclosure provides a method for increasing heart function in a subject in need thereof comprising administering to the subject an agent that increases MYH6 and decreases MYH7 gene expression in a cell of the subject. In some embodiments, the subject is suffering from cardiomyopathy, heart failure, arrhythmia, ischemic heart disease, non-ischemic heart disease and exercise or activity intolerance.
As used herein, “cardiomyopathy” refers to any disease or dysfunction of the myocardium (heart muscle) in which the heart is abnormally enlarged, thickened and/or stiffened. As a result, the heart muscle's ability to pump blood is usually weakened and unable to meet the demands of the body, often leading to congestive heart failure. The disease or disorder can be, for example, inflammatory, metabolic, toxic, infiltrative, fibrotic, hematological, genetic, or unknown in origin. Such cardiomyopathies may result from a lack of oxygen. Other diseases include those that result from myocardial injury which involves damage to the muscle or the myocardium in the wall of the heart as a result of disease or trauma. Myocardial injury can be attributed to many things such as, but not limited to, cardiomyopathy, myocardial infarction, or congenital heart disease. The cardiac disorder may be pediatric in origin. Cardiomyopathy includes, but is not limited to, cardiomyopathy (dilated, hypertrophic, restrictive, arrhythmogenic, ischemic, genetic, idiopathic and unclassified cardiomyopathy), sporadic dilated cardiomyopathy, X-linked Dilated Cardiomyopathy (XLDC), acute and chronic heart failure, right heart failure, left heart failure, biventricular heart failure, congenital heart defects, myocardiac fibrosis, mitral valve stenosis, mitral valve insufficiency, aortic valve stenosis, aortic valve insufficiency, tricuspidal valve stenosis, tricuspidal valve insufficiency, pulmonal valve stenosis, pulmonal valve insufficiency, combined valve defects, myocarditis, acute myocarditis, chronic myocarditis, viral myocarditis, diastolic heart failure, systolic heart failure, diabetic heart failure and accumulation diseases. In some embodiments, the heart failure includes reduced ejection fraction. In further embodiments, the heart failure includes preserved ejection fraction.
In some embodiments, the methods described herein treat the cardiomyopathy in the subject. It will be appreciated that “treating cardiomyopathy” does not require complete amelioration of the disorder; “treating” includes any improvement in a symptom or manifestation of the disorder that confers a beneficial effect on the subject. Methods for measuring cardiac function (e.g., contractile function) are known in the art and are described, for example, in the Textbook of Medical Physiology, Tenth edition, (Guyton et al., W.B. Saunders Co., 2000). For example, cardiac ejection can be monitored using, e.g., echocardiography, nuclear or radiocontrast ventriculography, or magnetic resonance imaging. Other measures of cardiac function include, but are not limited to, myocardial contractility, resting stroke volume, resting heart rate, resting cardiac index, Doppler imaging, cardiovascular performance during stress/exercise. Optionally, cardiac function is increased by at least 5%, 10%, 15%, 20%, 25%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or even 100% relative to the cardiac function prior to treatment. In some embodiments, the method partially rescues or improves one or more of the following: ejection fraction; left ventricle wall thickness; right ventricle wall thickness; left ventricular wall stress; right ventricular wall stress; ventricular mass; contractile function; cardiac hypertrophy; end diastolic volume; end systolic volume; cardiac output; cardiac index; pulmonary capillary wedge pressure; pulmonary artery pressure; 6 minute walk distance or time, performance on exercise testing, increase in ambulatory activity as monitored remotely by an activity monitor; reduction in serum biomarkers such as N-terminal pro BNP or troponin; and improvement in kidney function as it related to improve blood flow to the kidney.
Treating cardiomyopathy or heart failure in this embodiment would be undertaken to eliminate or postpone need for mechanical support of heart function such as use of a ventricular assist device and/or cardiac transplantation.
All of the U.S. patents, U.S. patent application publications, U.S. patent applications, foreign patents, foreign patent applications and non-patent publications referred to in this specification, are incorporated herein by reference, in their entireties.
From the foregoing it will be appreciated that, although specific embodiments of the invention have been described herein for purposes of illustration, various modifications may be made without deviating from the spirit and scope of the invention.
Epigenetic Datasets: For histone ChIP-Seq datasets and ATAC-seq datasets, the “fold change over negative control” bigwig file was used. For transcription factor Chip-seq datasets, peak bed files were used. For Homer computational predictions, a bed file representing the location of the transcription factor motif genome-wide was used. Files were imported into the UCSC genome browser for visualization. When necessary, datasets from mouse cells/tissues or hg38 were overlaid to hg19 using the UCSC liftover tool. For pcHiC data, the CHiCAGO pipeline raw output of three replicates of IPSC-CM promoter capture Hi-C data were downloaded.1 Probe-probe interactions were filtered. 1 kb was added to both ends of regions interacting with gene promoters. Data from each replicate was intersected using bedtools and retained only genomic interactions that were present in at least two replicates.2 Bed files representing pcHi-C interactions were visualized in the UCSC genome browser.
Epigenetic Dataset Downloads and Visualization. Epigenetic datasets were identified from the Encode data repository or GEO. For histone ChIP-Seq datasets and ATAC-seq datasets, the “fold change over negative control” bigwig file was downloaded. For transcription factor Chip-seq datasets, peak bed files were downloaded. For Homer computational predictions, a bed file representing the location of the transcription factor motif genome-wide was downloaded. Files were imported into the UCSC genome browser for visualization. When necessary, datasets from mouse cells/tissues or hg38 were overlaid to hg19 using the UCSC liftover tool.
For pcHiC data, the CHiCAGO pipeline raw output of three replicates of IPSC-CM promoter capture Hi-C data were downloaded10. Probe-probe interactions were filtered. 1 kb was added to both ends of regions interacting with gene promoters. Data was intersected from each replicate using bedtools and retained only genomic interactions that were present in at least two replicates30. Bed files representing pcHi-C interactions were visualized in the UCSC genome browser.
Enhancer Region Cloning. Candidate enhancer regions were ligated into luciferase plasmids using a Gateway cloning strategy. Candidate enhancer regions were amplified from human genomic DNA using primers with a 5′-CACC overhang using Phusion High-Fidelity DNA polymerase (NEB). An aliquot of the PCR reaction was separated on a 1% agarose-TBE gel to confirm amplification, and the remaining reaction was purified using a PCR Purification Kit (Qiagen). In cases where PCR failed to generate an adequate product, the enhancer region sequence (matching hg19) was synthesized as a dsDNA gGlock gene fragment (IDT). Approximately 5 ng of PCR product or gBlock was ligated into the pENTR/D-TOPO vector following manufacturer's instructions (ThermoFisher). The enhancer region was recombined into pGL4.23-GW (Addgene #60323) using LR Clonase II Enzyme mix (Thermo) with 150 ng of each plasmid. EndoFree Maxipreps (Qiagen) were used to prepare DNA. Plasmids were confirmed using Sanger Sequencing.
Enhancer constructs: Candidate enhancer regions were amplified from human genomic DNA using primers with a 5′-CACC overhang using Phusion High-Fidelity DNA polymerase (NEB). An aliquot of the PCR reaction was separated on a 1% agarose-TBE gel to confirm amplification, and the remaining reaction was purified using a PCR Purification Kit (Qiagen). In cases where PCR failed to generate an adequate product, the enhancer region sequence (matching hg19) was synthesized as a dsDNA gGlock gene fragment (IDT). Approximately 5 ng of PCR product or gBlock was ligated into the pENTR/D-TOPO vector following manufacturer's instructions (ThermoFisher). The enhancer region was recombined into pGL4.23-GW (Addgene #60323) using LR Clonase II Enzyme mix (Thermo) with 150 ng of each plasmid. EndoFree Maxipreps (Qiagen) were used to prepare DNA. Plasmids were confirmed using Sanger Sequencing. In all candidate enhancer plasmids, the enhancer sequence was located 125 bp upstream of the minimal promoter sequence. PCR primers and the genomic regions amplified for each construct are shown in are shown in Table 1.
Luciferase Reporter Assay. HL-1 cardiomyocytes (Millipore Sigma Cat #SCC065) were cultured on fibronectin coated flasks in Claycomb media with 10% HL-1 qualified FBS as previously described.31 Twenty-four hours before transfection, 140,000 HL-1 cells per well were plated on to a 12-well plate. On the day of transfection, HL-1 cells were transfected using Lipofecamine 3000 (Thermo Fisher) following manufacturer's instructions. Each well was transfected with 6 μl of 0.15 μM enhancer firefly luciferase plasmid, 50 ng of pRL-SV40 (Promega), 2.5 μl of Lipofecamine3000, and 6 μl of P3000 in 100 μl of Opti-MEM. Cells were allowed to incubate for 6-8 hours, following which half the media was replaced with Claycomb media. Forty-eight hours after transfection, the luciferase assay was performed with the Dual-Glo luciferase assay kit (Promega) according to manufacturer's instructions. The firefly luciferase signal from each well was recorded from three separate replicates and internally normalized to Renilla luciferase signal. Each enhancer construct was tested in a minimum of two separate wells on three separate days.
Induced pluripotent stem cell (iPSC)-derived cardiomyocytes (iPSC-CMs) were generated according to standard protocols32. At approximately day 10 of differentiation, cardiomyocytes were re-plated on to white clear-bottom 96-well plates at 40,000 cells per well. The media was changed every two days and cells began to beat as a syncytium day 14-16. On day 18, cardiomyocytes were transfected with Lipofecamine3000 (Thermo Fisher) according to manufacturer's instructions. Each well was transfected with 0.2 μl of 0.15 μM enhancer firefly luciferase plasmid, 5 ng of pRL-SV40 (Promega), 0.15 μl Lipofecamine3000, and 0.2 μl of P3000 in 10 μl of Opti-MEM. Forty-eight hours after transfection, the luciferase assay was performed with the Dual-Glo luciferase assay kit (Promega) according to manufacturer's instructions. Firefly luciferase signal was read using 96-well plate reader and signals were internally normalized to the same well's Renilla luciferase signal. Each enhancer construct was tested in 8 separate wells on at least three separate cardiomyocyte differentiations.
IPSC Reprogramming, Culturing, and IPSC-CM Differentiation. Human skin fibroblasts were obtained from Coriell (sample name GM03348, 10 year old male) and cultured in DMEM containing 10% FBS. Fibroblasts were re-programmed into induced pluripotent stem cells (IPSCs) via electroporation with pCXLE-hOCT3/4-shp53-F (Addgene plasmid 27077), pCXLE-hSK (Addgene plasmid 27078), and pCXLE-hUL (Addgene plasmid 27080) as described previously33. IPSCs were maintained on Matrigel-coated 6-well plates with mTeSR-1 (Stem Cell technologies, Cat #85850) and passaged as colonies every 5-7 days using ReLeSR (Stem Cell technologies, Cat #05872).
IPSCs were differentiated into cardiomyocytes (iPSC-CMs) using Wnt modulation as previously described32. Differentiation was conducted in CDM3 (RPMI 1640 with L-glutamine, 213 μg/mL L-asorbic acid 2-phosphate, 500 μg/mL recombinant human albumin)32. Cells were grown to approximately 95% confluency and treated with 6 μM-10 μM CHIR99021 for 24 hours and allowed to recover for 24 hours. Cells were treated with 2 μM Wnt-C59 for 48 hours and then media was changed with CDM3 every two days until beating cardiomyocytes were obtained (approximately day 6-10). In order to prevent cell detachment, beating cardiomyocytes re-plated on to new plates using TrypLE (Thermo Fisher). Media was changed every two days until downstream assays were performed (˜day 20).
CRISPr Enhancer Deletion in IPSCs. To delete enhancer regions, guides targeting the 5′ and 3′ end of enhancer regions were designed using CRISPR34. The guides and primer sequence used in the experiments described herein are provided in Table 2 below.
Guides were ligated into pSpCas9(BB)-2A-Puro (Addgene plasmid #62988) after the U6 promoter using either Bbs1 digestion and ligation or Gibson assembly. DNA preparations of plasmid were prepared using an EndoFree plasmid kit (Qiagen), and plasmid sequences were confirmed with Sanger sequencing. IPSCs were nucleofected using the Neon transfection system (Thermo Fisher). Briefly, GM03348 IPSCs were grown to approximately 70% confluency and treated with mTeSR-1 containing 2 μM thiazovivin (TZV) for one hour. Cells were digested with TrypLE, collected and counted. 3.75 million IPSCs per nucleofection were pelleted at 300 g for 3 min. Cell pellets were resuspended in 125 μl of buffer R and added to an Eppendorf tube containing 1.5 μg or 2.5 μg of each plasmid. Cells were nucleofected in the Neon system in a 100 μl tip with the following settings: 1400 V, 20 ms, 2 pulses. Nucleofected cells were expelled into a single well of Matrigel-coated 6-well plate containing mTeSR-1 supplemented with ClonR (Stem Cell Technologies, Cat #05888) and 2 μM TZV. For each round, a pSpCas9(BB)-2A-GFP (Addgene plasmid #48138) control was included. Twenty-four hours later, cells were treated with mTeSR-1 containing 0.15 μg/mL puromycin. The next day, selection was continued with 0.2 μg/mL puromycin until no viable cells were seen in the GFP control (approximately 2-3 days). Cells were switched to mTeSR-1 supplemented with ClonR and 2 μM TZV and media was changed daily until colonies appeared (5-7 days). Colonies were picked on to 96-well plates, expanded, and split on to two duplicate plates. The first plate was used for cryopreservation in 50% mTeSR-1/ClonR/2 μM TZV and 50% KnockOut Serum replacement/25% DMSO. The second plate was processed for gDNA isolation using the DirectPCR lysis reagent (Viagen, Cat #301-C) following manufacturer's instructions. Colonies were screened for successful enhancer deletion using a 3-primer PCR approach. PCR products were cloned using the TOPO TA cloning kit (Thermo Fisher) and sequenced to determine alleles present. Positive colonies were thawed from the frozen plate, expanded, re-genotyped, and used for differentiation. In cases where no homozygous deletions were obtained, a heterozygous colony was treated with a second round of CRISPR editing.
IPSC Chromosome Analysis and CRIPSr-Off Target Analysis. IPSC Chromosome analysis was conducted using the hPSC genetic analysis kit (Stem Cell Technologies, Cat #07550) following manufacturer's instructions. IPSC lines must show no amplification or deletion in at least 8 of the 9 tested sites to pass our karyotypic quality control standards. The output from the CRISPOR34 guide design tool was used to identify the most likely off target cut sites. Any regions with <3 mismatches and additional off targets that were within or near genes important for cardiac function were selected. Primers were designed to amplify putative off target sites and regions were amplified from gene edited cell gDNA. PCR products were purified using ExoSAp-IT (Thermo) or Ampure XP beads (Beckman Coulter) and sequenced with sanger sequencing. Sanger traces from unedited IPSCs were compared to gene edited lines to identify any off-target changes. Genotype of enhancer deleted cells are shown in Table 2. Off-target analysis is shown in Table 3.
IPSC-CM RNA Extraction and qPCR. At ˜day 10 of differentiation, 1 million IPSC-derived cardiomyocytes were plated on a well of 12-well plate. At approximately day 20, cells were washed with PBS and 400 μl of TRIzol (Thermo Fisher) was added directly to the well. Cells were collected into an Eppendorf tube using a cell scraper. Trizol was kept at −80° C. until further processing. Six hundred μl of additional TRIzol was added to the cells and the entire sample was added to a tube containing 250 μl of silica-zirconium beads. Tubes were placed in a bead beater homogenizer (BioSpec) for 1 minute and immediately cooled on ice. Samples were incubated at room temperature for 5 min and then centrifuged at 12,000 g for 5 min to remove unhomogenized cell aggregates. Supernatant was transferred to a new tube and 200 μl of chloroform was added. After vigorous shaking for 30 seconds followed by 10 min incubation with periodic shaking, samples were centrifuged at 12,000 g for 15 min. The upper aqueous layer was added to an equal volume of fresh 70% ethanol and used an input to the Aurum Total RNA Mini Kit (Biorad). RNA was processed according to manufacturer's instructions including on-column DNase digestion. RNA was eluted twice with 30 μl of warmed water and the concentration was measured using a nanodrop spectrophotometer.
The qScript cDNA SuperMix (Quantabio) was used to generate a 100 ng cDNA library. A 1:10 dilution was used as a template in a 3-step SYBR-green qPCR region with a 57° C. annealing temperature. A panel of primers targeting cardiomyocyte references genes (TNNT2, MYBPC3, TNNI3, SLC8A1, MYOZ2 and GAPDH) that passed optimization studies confirming primer specificity and efficiency was used. For enhancer deletion measurements, changes in MYH6 and MYH7 expression were calculated using the delta-delta Cq method using the geometric mean expression of cardiomyocyte reference genes.
SDS-PAGE of Myosin Heavy Chain Isoforms. A 6.25% acrylamide/bis-acrylamide (99:1) resolving gel was prepared by combining 7.5 mL of 25% Acrylamide/bis-acrylamide (99:1), 5.65 mL of 2M Tris pH 8.8, 16.55 mL of ddH20, 300 μl of 10% SDS (w/v), 312 μl 10% ammonium persulfate, and 12.5 μl of TEMED. The resolving gel was allowed to polymerize for 1 hour at room temperature. A 5% acrylamide/bis-acrylamide (99:1) stacking gel was prepared by combining 2 mL of 25% Acrylamide/bis-acrylamide (99:1), 2.5 mL of 0.5M Tris pH 6.8, 5.325 mL of ddH20, 100 μl of 10% SDS (w/v), 90 μl 10% ammonium persulfate, and 6 μl of TEMED. The stacking gel was allowed to polymerize for 8 hours. Lysates of approximately day 20 iPSC-CMs were prepared and protein concentrations were quantified with the Quick-Start Bradford Protein Assay (Bio-Rad). approximately 7 μg of protein was mixed 1:1 with 2× Laemmli Sample Buffer containing β-mercaptoethanol. Samples were loaded into the SDS-polyacrylamide gel described above and separated at 13 mA for 20 min, and 15 mA for 21 hours. After electrophoresis, gels were fixed with a 7% acetic acid/50% methanol solution for 1 hour at room temperature. Protein was visualized with the Sypro Ruby Protein Gel Stain (Thermo Fisher) following manufacturer's instructions. Quantification of band intensities was done using Fiji35.
Engineered Heart Tissue Generation and Measurement of Contractile Properties. Engineered heart tissues (EHTs) were generated according to previously published methods36. iPSC-CMs were differentiated as previously described and when beating cells were present (approximately day 10), cells were washed with PBS and digested with TrypLE (Thermo). One million cells per EHT were centrifuged at 500 g for 5 min and resuspended in 65 μl of EHT media (CDM332, containing 10% of heat-inactivated FBS, 2 μM thiazovivin, 33 μg/mL aprotinin, and 5 U/mL penicillin/streptomycin), 25 μl of 25 mg/mL fibrinogen and 10 μl of Matrigel (Corning). 100 μl of this EHT mix was added to 3 μl of 100 U/mL thrombin and mixed. The whole mixture was pipetted between PDMS posts (EHT Technologies) in an EHT mold created from 2% agarose and a Teflon spacer in a 24-well Nunc plate (Thermo Fisher). Fibrin gel was allowed to polymerize for 2 hours and then 200 μl of CDM3 was added to the EHT to help detach it from the mold. After 30 min, the PDMS posts were lifted from the mold and the EHT was placed into a new 24 well plate containing 1.6 mL of RPMI containing B27 supplement (Thermo Fisher) and 33 μg/mL aprotinin. Media was changed every other day until further processing. After 20 days of culture, videos of EHT contraction were taken on a KEYENCE BZ-X microscope at 50 fps with 4×4 pixel binning. Videos were imported into Fiji and analyzed with MUSCLEMOTION macro with default settings37. The contraction parameters for each contraction were averaged to give an EHT level measurement.
Flow Cytometry Analysis of IPSC-CM Purity. At approximately day 20 of differentiation, iPSC-CMs were collected using TrypLE (Thermo Fisher). Cells were resuspended in 1 mL of PBS and added to 1 mL of 8% PFA in PBS for fixing. Cells were fixed at 37° C. for 10 min with shaking. Cells were collected by centrifugation at 600 g for 5 min and resuspended in 100 μl ice-cold 90% methanol in PBS per 500,000 starting cells. Cells were stored at −20° C. until further processing. On the day of flow, approximately 1 million cells were aliquoted into two tubes containing 2 mL of 0.5 mg/mL BSA in PBS and pelleted. One tube was resuspended in 100 μl of PBS containing 1:200 dilution of TNNT2-Alexa Fluor 694 (BD Pharmingen #565744) and 1:200 MYBPC3-Alexa Fluor 488 (Santa Cruz Biotechnology #sc-137180 AF488) and the other tube was suspended in PBS alone. Cells were stained for 1 hour at room temperature. Four mL of 0.5 mg/mL BSA in PBS was added to each tube and cells were pelleted. Cells were resuspended in 100 μl in PBS and analyzed on a flow cytometer. The percentage of TNNT2-positive cells was determined by using PBS only as a negative control.
Find Regulatory Variants Computational Pipeline.
In datasets where multiple replicates were available, a superset representing all peaks found was created. The pipeline finds variants that are predicted to disrupt or create transcription factor binding sites. In order to use find new transcription factor binding sites created by variants, we used the GATK FastaAlternateReferenceMaker to insert SNP variants into the reference genome38. Homer's scanMotifGenomeWide.pl was then used to search for GATA4 and TBX5 sites in the alternative reference and kept only sites that were new39. In the case of multi-allelic variants, one alternative allele was chosen at random. These additional sites were used in the pipeline alongside sites present in the unchanged reference. This pipeline was executed on variants that passed all quality filters from the gnomAD v.2.1 release.
Association of Enhancer Variant with Phenotypic Data. Phenotypic measurements of heart function and whole genome sequencing data were accessed as in21. Individual measures were obtained for left ventricular internal diameter-diastole (LVIDd) and left ventricular posterior wall thickness during diastole (LVPWd) from echocardiogram reports and spanned as much as 14 years of echocardiogram data. The diagnosis of heart failure was determined by ICD9 diagnosis codes 425 and all sub-codes, and ICD10 diagnostic codes 142 and all sub-codes. Trajectory analysis of echo measurements was conducted as in21. Briefly, PROC TRAJ in SAS 9.4 was used,40 which uses a likelihood function to assign a each individual a phenotypic cluster and probability of belonging to that cluster. An individual's variant status was regressed against cluster probability and was controlled for genetic race (PC1-3) and sex in R.
To find putative modifying regulatory variants associated with cardiomyopathy, the regulatory landscape of two of the most frequently involved genes with this pathology was characterized. Mutations in MYH7 and LMNA are common causes of inherited cardiomyopathy. While both genes have the potential to cause cardiomyopathy, they differ in expression patterns, with MYH7 expression demonstrating tissue restricted expression and LMNA having a broad expression distribution. To identify enhancer regions active in the human left ventricle, multiple datasets including human left ventricle-derived H3K27Ac ChIP-seq and ATAC-seq, as well as ChIP-seq data of genome-wide binding of the cardiogenic transcription factors GATA4, TBX3/5, and NKX2.5 were overlaid from multiple cell/tissue sources (complete list shown in Table 2). Promoter-capture Hi-C data from iPSC-CMs was used to identify genomic regions predicted to interact with promoters10. Intersection of these datasets identified two enhancer clusters for MYH7 and three for LMNA (
Next, using a luciferase reporter assay, the regulatory potential of the candidate enhancer regions identified in the MYH7 and LMNA loci was determined experimentally. Promoter-capture Hi-C data was used to define the boundaries of individual enhancers within clusters. Because of size, some enhancers were further dissected into smaller regions. Four of five MYH7 enhancer regions tested showed significant activity in iPSC-CMs compared to a negative control genomic desert region (
To test if candidate enhancers are required for target gene expression, regions of interest in iPSCs were deleted using gene editing. MYH7-C3 and MYH7-C4 were focused on due to their high activity in reporter assays and intergenic position. LMNA-C3 was not evaluated due to low activity and the potential to disrupt LMNA splicing. A dual cutting CRISPr-Cas9 strategy was employed to remove the candidate enhancer regions (
Enhancer-deleted iPSCs were differentiated into cardiomyocytes and measured MYH7 and MYH6 mRNA expression using qPCR. MYH7-C3+/− and −/−cells had a significant decrease in MYH7 expression and increase in MYH6 expression, with dose-dependency (
Next, the MYH7 enhancers were characterized for naturally occurring sequence variants using the gnomAD database and those that overlapped cardiac transcription factor binding motifs, and/or were correlated with MYH7 expression in the GTEx eQTL dataset15,16 were selected. Six unique variants within MYH7 enhancers that overlapped transcription factor binding motifs and were within or nearby ChIP-seq peaks showing transcription factor binding in cardiac cells were identified (
Next, a computational filtering pipeline to use publicly available data from iPSC-CMs to identify variants within enhancer regions that alter transcription factor binding was generated (
Next, the potential of these identified EMVs to act as modifiers of cardiomyopathy was determined. rs875908, which was predicted to regulate MYH6 by the computational pipeline, is an EMV located approximately 2 kb upstream of MYH7 (
To ascertain whether rs875908 correlates with cardiac outcomes, we evaluated trajectory probabilities of left ventricular dimensions over time using genomic and echocardiographic information derived from the Northwestern biobank. This approach assigns a probability of maintaining an echocardiographic change overtime21. The rs875908-G allele correlates with a more dilated left ventricle over time in participants selected with cardiomyopathy diagnosis codes (
Discussion
Cardiomyopathy gene enhancers. Epigenomic data was integrated to uncover candidate enhancers for a highly expressed and tissue restricted locus like the MYH6/7 genes. As demonstrated herein, this approach can be used on lower and more ubiquitously expressed genes like LMNA, a gene also important for cardiomyopathy. This data integration has the power to identify regulatory regions remote from the gene of interest and uncover human genetic variation that alters the activity of these regions.
An MYH7/6 Super-Enhancer. Promoter capture Hi-C data from human cardiomyocytes10 indicates that the MYH7 and MYH6 gene promoters contact each other within 3-dimensional space. Further, an enhancer cluster positioned approximately 7 kb upstream of MYH7 also interacts with the MYH7 gene promoter. Since multiple individual parts of this enhancer cluster have activity in human cardiomyocytes, it is likely this cluster represents a super-enhancer22. Super-enhancers are known to regulate genes critical for cell identity23. The Examples provided herein demonstrate that deletion of the MYH7-C3 enhancer region reduced MYH7 expression in iPSC-CMs, and, correspondingly, deletion of the MYH7-C3 enhancer increased MYH6 expression resulting in an αMHC/βMHC ratio and a faster rate of contraction in EHTs. Deletion of the MYH7-C3 promoter shifts expression from MYH7 to MYH6, akin to what has been described after thyroid hormone exposure or in the developing ventricle (Metzger et al., Circ Res. 1999; 84:1310-7; Cappelli et al., Circ Res. 1989; 65:446-57; Rundell et al., American journal of physiology Heart and circulatory physiology. 2005; 288:H896-903). The faster rate of contraction/relaxation from deleting MYH7-C3 is distinct from what occurs in hypertrophic cardiomyopathy EHTs, which better reflect the relaxation defects seen in hypertrophic cardiomyopathy (Prondzynski et al., EMBO molecular medicine. 2019; 11:e11115). These data favor a model where the MYH6 and MYH7 promoter regions form a 3-dimensional complex with the super enhancer upstream of MYH7 (
Integrated genomics to identify EMVs. The pipeline disclosed herein identified rs875908, a common variant with MAF ranging from 35% to 47% in various populations, as an EMV for cardiomyopathy. This variant correlated with altered MYH7 expression and with a more severe dilated cardiomyopathy phenotype over time, as marked by a more dilated, thinner walled ventricle. The MYH6/7 ratio is known to shift during heart failure, with end stage hearts exhibiting an increase in MYH7 and a decrease in MYH6. With prolonged shift of myosin expression, or a specific magnitude of shift, this change in myosin expression may actually contribute to heart failure25. Supporting this, the MYH6/7 ratio has previously been implicated in heart failure phenotypes26. A distinct contributory mechanism could involve variants within MYH6/7 enhancers, variants in linkage disequilibrium or even pathogenic coding mutations. Varied expression of pathogenic MYH7 mutations has been shown to affect cardiomyopathy phenotypes27,28. A region related to the C6 enhancer, containing the EMV rs875908, was previously deleted in a mouse. Mice missing this C6 orthologous region had reduced MYH7/β-MHC but no change in MYH6/α-MHC29, similar to what was shown here in human cells. This study measured MYH7 expression in the mouse embryonic heart, which differs from the human developing and mature heart. Consistent with the human genetic findings, mouse hearts lacking this enhancer region demonstrated reduced fractional shortening and higher amounts of myofiber disarray, which additionally support the functionality of this region.
A pipeline for EMVs. As deep sequencing data of intergenic regions becomes more available, the importance of noncoding annotation of disease genes will become vital and permit the integration of this information into clinical care. Collectively, the data provided herein provides a robust pipeline to identify genetic variants positioned to alter gene expression. The pipeline disclosed herein identified >1,700 putative EMVs in the gnomAD database, which were linked to multiple genes important for cardiac function like TNNT2, NPPA, GJA5, and MEF2A. Many of the predicted EMVs were infrequent in the population, further supporting the functional role of this type of expression-altering change. However, EMVs were identified at higher population frequency; higher frequency EMVs, because of their prevalence, are more likely to show population level clinical correlates, such as what we could detect using electronic health record data. Targeted assessment of EMVs annotated by specific epigenetic marks can have clinical utility.
This application claims the priority benefit under 35 U.S.C. § 119(e) of U.S. Provisional Patent Application No. 63/121,560, filed Dec. 4, 2020, which is incorporated herein by reference in its entirety.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US21/61750 | 12/3/2021 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 63121560 | Dec 2020 | US |
