RESUMEN
Nemaline myopathy 8 (NEM8) is typically a severe autosomal recessive disorder associated with variants in the kelch-like family member 40 gene (KLHL40). Common features include fetal akinesia, fractures, contractures, dysphagia, respiratory failure and neonatal death. Here, we describe a 26-year-old man with relatively mild NEM8. He presented with hypotonia and bilateral femur fractures at birth, later developing bilateral Achilles' contractures, scoliosis, and elbow and knee contractures. He had walking difficulties throughout childhood and became wheelchair bound from age 13 after prolonged immobilization. Muscle magnetic resonance imaging at age 13 indicated prominent fat replacement in his pelvic girdle, posterior compartments of thighs and vastus intermedius. Muscle biopsy revealed nemaline bodies and intranuclear rods. RNA sequencing and western blotting of patient skeletal muscle indicated significant reduction in KLHL40 mRNA and protein, respectively. Using gene panel screening, exome sequencing and RNA sequencing, we identified compound heterozygous variants in KLHL40; a truncating 10.9 kb deletion in trans with a likely pathogenic variant (c.*152G > T) in the 3' untranslated region (UTR). Computational tools SpliceAI and Introme predicted the c.*152G > T variant created a cryptic donor splice site. RNA-seq and in vitro analyses indicated that the c.*152G > T variant induces multiple de novo splicing events that likely provoke nonsense mediated decay of KLHL40 mRNA explaining the loss of mRNA expression and protein abundance in the patient. Analysis of 3' UTR variants in ClinVar suggests variants that introduce aberrant 3' UTR splicing may be underrecognized in Mendelian disease. We encourage consideration of this mechanism during variant curation.
Asunto(s)
Contractura , Miopatías Nemalínicas , Masculino , Recién Nacido , Humanos , Niño , Adolescente , Adulto , Miopatías Nemalínicas/genética , Regiones no Traducidas 3'/genética , Proteínas Musculares/genética , Proteínas Musculares/metabolismo , Sitios de Empalme de ARN/genética , ARN Mensajero , Contractura/genética , MutaciónRESUMEN
Rhabdomyolysis is the acute breakdown of skeletal myofibres in response to an initiating factor, most commonly toxins and over exertion. A variety of genetic disorders predispose to rhabdomyolysis through different pathogenic mechanisms, particularly in patients with recurrent episodes. However, most cases remain without a genetic diagnosis. Here we present six patients who presented with severe and recurrent rhabdomyolysis, usually with onset in the teenage years; other features included a history of myalgia and muscle cramps. We identified 10 bi-allelic loss-of-function variants in the gene encoding obscurin (OBSCN) predisposing individuals to recurrent rhabdomyolysis. We show reduced expression of OBSCN and loss of obscurin protein in patient muscle. Obscurin is proposed to be involved in sarcoplasmic reticulum function and Ca2+ handling. Patient cultured myoblasts appear more susceptible to starvation as evidenced by a greater decreased in sarcoplasmic reticulum Ca2+ content compared to control myoblasts. This likely reflects a lower efficiency when pumping Ca2+ back into the sarcoplasmic reticulum and/or a decrease in Ca2+ sarcoplasmic reticulum storage ability when metabolism is diminished. OSBCN variants have previously been associated with cardiomyopathies. None of the patients presented with a cardiomyopathy and cardiac examinations were normal in all cases in which cardiac function was assessed. There was also no history of cardiomyopathy in first degree relatives, in particular in any of the carrier parents. This cohort is relatively young, thus follow-up studies and the identification of additional cases with bi-allelic null OBSCN variants will further delineate OBSCN-related disease and the clinical course of disease.
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Calcio , Rabdomiólisis , Adolescente , Humanos , Rabdomiólisis/genética , Rabdomiólisis/diagnóstico , Rabdomiólisis/patología , Mialgia/genética , Retículo Sarcoplasmático/metabolismo , Pérdida de Heterocigocidad , Proteínas Serina-Treonina Quinasas , Factores de Intercambio de Guanina Nucleótido Rho/genéticaRESUMEN
McArdle disease is a disorder of carbohydrate metabolism that causes painful skeletal muscle cramps and skeletal muscle damage leading to transient myoglobinuria and increased risk of kidney failure. McArdle disease is caused by recessive mutations in the muscle glycogen phosphorylase (PYGM) gene leading to absence of PYGM enzyme in skeletal muscle and preventing access to energy from muscle glycogen stores. There is currently no cure for McArdle disease. Using a preclinical animal model, we aimed to identify a clinically translatable and relevant therapy for McArdle disease. We evaluated the safety and efficacy of recombinant adeno-associated virus serotype 8 (rAAV8) to treat a murine model of McArdle disease via delivery of a functional copy of the disease-causing gene, Pygm. Intraperitoneal injection of rAAV8-Pygm at post-natal day 1-3 resulted in Pygm expression at 8 weeks of age, accompanied by improved skeletal muscle architecture, reduced accumulation of glycogen and restoration of voluntary running wheel activity to wild-type levels. We did not observe any adverse reaction to the treatment at 8 weeks post-injection. Thus, we have investigated a highly promising gene therapy for McArdle disease with a clear path to the ovine large animal model endemic to Western Australia and subsequently to patients.
Asunto(s)
Glucógeno Fosforilasa de Forma Muscular/metabolismo , Enfermedad del Almacenamiento de Glucógeno Tipo V/metabolismo , Glucógeno/metabolismo , Músculo Esquelético/metabolismo , Animales , Modelos Animales de Enfermedad , Femenino , Glucógeno Fosforilasa de Forma Muscular/genética , Enfermedad del Almacenamiento de Glucógeno Tipo V/genética , Inflamación/genética , Inflamación/metabolismo , Masculino , Ratones , Ratones Endogámicos C57BLRESUMEN
OBJECTIVES: Systemic lupus erythematosus (SLE; OMIM 152700) is characterised by the production of antibodies to nuclear antigens. We previously identified variants in complement receptor 2 (CR2/CD21) that were associated with decreased risk of SLE. This study aimed to identify the causal variant for this association. METHODS: Genotyped and imputed genetic variants spanning CR2 were assessed for association with SLE in 15 750 case-control subjects from four ancestral groups. Allele-specific functional effects of associated variants were determined using quantitative real-time PCR, quantitative flow cytometry, electrophoretic mobility shift assay (EMSA) and chromatin immunoprecipitation (ChIP)-PCR. RESULTS: The strongest association signal was detected at rs1876453 in intron 1 of CR2 (pmeta=4.2×10(-4), OR 0.85), specifically when subjects were stratified based on the presence of dsDNA autoantibodies (case-control pmeta=7.6×10(-7), OR 0.71; case-only pmeta=1.9×10(-4), OR 0.75). Although allele-specific effects on B cell CR2 mRNA or protein levels were not identified, levels of complement receptor 1 (CR1/CD35) mRNA and protein were significantly higher on B cells of subjects harbouring the minor allele (p=0.0248 and p=0.0006, respectively). The minor allele altered the formation of several DNA protein complexes by EMSA, including one containing CCCTC-binding factor (CTCF), an effect that was confirmed by ChIP-PCR. CONCLUSIONS: These data suggest that rs1876453 in CR2 has long-range effects on gene regulation that decrease susceptibility to lupus. Since the minor allele at rs1876453 is preferentially associated with reduced risk of the highly specific dsDNA autoantibodies that are present in preclinical, active and severe lupus, understanding its mechanisms will have important therapeutic implications.
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Anticuerpos Antinucleares/sangre , Lupus Eritematoso Sistémico/genética , Receptores de Complemento 3d/genética , Adolescente , Adulto , Subgrupos de Linfocitos B/inmunología , Estudios de Casos y Controles , ADN/inmunología , Predisposición Genética a la Enfermedad , Variación Genética , Genotipo , Haplotipos , Humanos , Lupus Eritematoso Sistémico/inmunología , Persona de Mediana Edad , Fenotipo , Polimorfismo de Nucleótido Simple , Receptores de Complemento 3b/biosíntesis , Medición de Riesgo/métodos , Factores de Transcripción/metabolismo , Adulto JovenRESUMEN
We used gene editing to introduce DNA sequences encoding the tdTomato fluorescent protein into the α -skeletal actin 1 (ACTA1) locus to develop an ACTA1-tdTomato induced pluripotent stem cell reporter line for monitoring differentiation of skeletal muscle. This cell line will be used to better understand skeletal muscle maturation and development in vitro as well as provide a useful tool for drug screening and the evaluation of novel therapeutics for the treatment of skeletal muscle disease.
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Sistemas CRISPR-Cas , Células Madre Pluripotentes Inducidas , Proteína Fluorescente Roja , Humanos , Sistemas CRISPR-Cas/genética , Células Madre Pluripotentes Inducidas/metabolismo , Actinas/genética , Actinas/metabolismo , Músculo Esquelético/metabolismoRESUMEN
Variants in MYH7 cause cardiomyopathies as well as myosin storage myopathy and Laing early-onset distal myopathy (MPD1). MPD1 is characterized by muscle weakness and atrophy usually beginning in the lower legs. Here, we generated iPSC lines from lymphoblastoid cells of three unrelated individuals heterozygous for the most common MPD1-causing variant; p.Lys1617del. iPSC lines showed typical morphology, expressed pluripotency markers, demonstrated trilineage differentiation potential, and had a normal karyotype. These lines represent the first iPSCs derived from MPD1 patients and complement existing MPD1 animal models. They can provide in vitro platforms to better understand and model MPD1 pathomechanisms and test therapies.
RESUMEN
RYR1 variants are a common cause of congenital myopathies, including multi-minicore disease (MmD) and central core disease (CCD). Here, we generated iPSC lines from two CCD patients with dominant RYR1 missense variants that affect the transmembrane (pore) and SPRY3 protein domains (p.His4813Tyr and p.Asn1346Lys, respectively). Both lines had typical iPSC morphology, expressed canonical pluripotency markers, exhibited trilineage differentiation potential, and had normal karyotypes. Together with existing RYR1 iPSC lines, these represent important tools to study and develop treatments for RYR1-related myopathies.
Asunto(s)
Células Madre Pluripotentes Inducidas , Mutación Missense , Canal Liberador de Calcio Receptor de Rianodina , Humanos , Canal Liberador de Calcio Receptor de Rianodina/genética , Canal Liberador de Calcio Receptor de Rianodina/metabolismo , Células Madre Pluripotentes Inducidas/metabolismo , Miopatía del Núcleo Central/genética , Miopatía del Núcleo Central/patología , Miopatía del Núcleo Central/metabolismo , Adulto , Línea Celular , Masculino , Diferenciación Celular , FemeninoRESUMEN
RYR1 variants are the most common genetic cause of congenital myopathies, and typically cause central core disease (CCD) and/or malignant hyperthermia (MH). Here, we generated iPSC lines from two patients with CCD and MH caused by dominant RYR1 variants within the central region of the protein (p.Val2168Met and p.Arg2508Cys). Both lines displayed typical iPSC morphology, uniform expression of pluripotency markers, trilineage differentiation potential, and had normal karyotypes. These are the first RYR1 iPSC lines from patients with both CCD and MH. As these are common CCD/MH variants, these lines should be useful to study these conditions and test therapeutics.
Asunto(s)
Células Madre Pluripotentes Inducidas , Hipertermia Maligna , Mutación Missense , Canal Liberador de Calcio Receptor de Rianodina , Humanos , Canal Liberador de Calcio Receptor de Rianodina/genética , Canal Liberador de Calcio Receptor de Rianodina/metabolismo , Hipertermia Maligna/genética , Células Madre Pluripotentes Inducidas/metabolismo , Miopatía del Núcleo Central/genética , Miopatía del Núcleo Central/patología , Masculino , Femenino , Línea Celular , Diferenciación CelularRESUMEN
Central core disease (CCD) is a congenital disorder that results in hypotonia, delayed motor development, and areas of reduced oxidative activity in the muscle fibre. Two induced pluripotent stem cell (iPSC) lines were generated from the lymphoblastoid cells of a 33-year-old male with CCD, caused by a previously unreported dominant c.14145_14156delCTACTGGGACA (p.Asn4715_Asp4718del) deletion in the RYR1 gene. Both lines demonstrated typical morphology, pluripotency, trilineage differentiation, and had a normal karyotype. As the first published iPSC model of CCD caused by an RYR1 variant these lines are a potential resource for further investigation of RYR1-related myopathies in a human context.
Asunto(s)
Células Madre Pluripotentes Inducidas , Miopatía del Núcleo Central , Masculino , Humanos , Adulto , Miopatía del Núcleo Central/genética , Miopatía del Núcleo Central/metabolismo , Células Madre Pluripotentes Inducidas/metabolismo , Canal Liberador de Calcio Receptor de Rianodina/genética , Canal Liberador de Calcio Receptor de Rianodina/metabolismo , MutaciónRESUMEN
Variants in the ACTA1 gene are a common cause of nemaline myopathy (NM); a muscle disease that typically presents at birth or early childhood with hypotonia and muscle weakness. Here, we generated an induced pluripotent stem cell line (iPSC) from lymphoblastoid cells of a 3-month-old female patient with intermediate NM caused by a dominant ACTA1 variant (c.515C > A (p.Ala172Glu)). iPSCs showed typical morphology, expressed pluripotency markers, demonstrated trilineage differentiation potential, and had a normal karyotype. This line complements our previously published ACTA1 iPSC lines derived from patients with typical and severe NM.
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Células Madre Pluripotentes Inducidas , Miopatías Nemalínicas , Actinas/genética , Actinas/metabolismo , Preescolar , Femenino , Humanos , Células Madre Pluripotentes Inducidas/metabolismo , Lactante , Recién Nacido , Músculo Esquelético/metabolismo , Mutación , Miopatías Nemalínicas/genéticaRESUMEN
Nemaline myopathy (NM) is a congenital skeletal muscle disorder that typically results in muscle weakness and the presence of rod-like structures (nemaline bodies) in the sarcoplasma and/or in the nuclei of myofibres. Two induced pluripotent stem cell (iPSC) lines were generated from the lymphoblastoid cells of a 1-month-old male with severe NM caused by a homozygous recessive mutation in the ACTA1 gene (c.121C > T, p.Arg39Ter). The iPSC lines demonstrated typical morphology, expressed pluripotency markers, exhibited trilineage differentiation potential and displayed a normal karyotype. These isogenic lines represent a potential resource to investigate and model recessive ACTA1 disease in a human context.
Asunto(s)
Células Madre Pluripotentes Inducidas , Miopatías Nemalínicas , Actinas/genética , Actinas/metabolismo , Homocigoto , Humanos , Células Madre Pluripotentes Inducidas/metabolismo , Lactante , Masculino , Músculo Esquelético/metabolismo , Mutación , Miopatías Nemalínicas/genética , Miopatías Nemalínicas/metabolismoRESUMEN
The Regulators of Complement Activation (RCA) gene cluster comprises several tandemly arranged genes with shared functions within the immune system. RCA members, such as complement receptor 2 (CR2), are well-established susceptibility genes in complex autoimmune diseases. Altered expression of RCA genes has been demonstrated at both the functional and genetic level, but the mechanisms underlying their regulation are not fully characterised. We aimed to investigate the structural organisation of the RCA gene cluster to identify key regulatory elements that influence the expression of CR2 and other genes in this immunomodulatory region. Using 4C, we captured extensive CTCF-mediated chromatin looping across the RCA gene cluster in B cells and showed these were organised into two topologically associated domains (TADs). Interestingly, an inter-TAD boundary was located within the CR1 gene at a well-characterised segmental duplication. Additionally, we mapped numerous gene-gene and gene-enhancer interactions across the region, revealing extensive co-regulation. Importantly, we identified an intergenic enhancer and functionally demonstrated this element upregulates two RCA members (CR2 and CD55) in B cells. We have uncovered novel, long-range mechanisms whereby autoimmune disease susceptibility may be influenced by genetic variants, thus highlighting the important contribution of chromatin topology to gene regulation and complex genetic disease.
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Cromatina , Elementos de Facilitación Genéticos , Cromatina/genética , Activación de Complemento , Regulación de la Expresión Génica , Familia de MultigenesRESUMEN
BACKGROUND: CRISPR/Cas9 is an invaluable tool for studying cell biology and the development of molecular therapies. However, delivery of CRISPR/Cas9 components into some cell types remains a major hurdle. Primary human myoblasts are a valuable cell model for muscle studies, but are notoriously difficult to transfect. There are currently no commercial lipofection protocols tailored for primary myoblasts, and most generic guidelines simply recommend transfecting healthy cells at high confluency. This study aimed to maximize CRISPR/Cas9 transfection and editing in primary human myoblasts. METHODS: Since increased cell proliferation is associated with increased transfection efficiency, we investigated two factors known to influence myoblast proliferation: cell confluency, and a basement membrane matrix, Matrigel. CRISPR/Cas9 editing was performed by delivering Cas9 ribonucleoprotein complexes via lipofection into primary human myoblasts, cultured in wells with or without a Matrigel coating, at low (~ 40%) or high (~ 80%) confluency. RESULTS: Cells transfected at low confluency on Matrigel-coated wells had the highest levels of transfection, and were most effectively edited across three different target loci, achieving a maximum editing efficiency of 93.8%. On average, editing under these conditions was >4-fold higher compared to commercial recommendations (high confluency, uncoated wells). CONCLUSION: This study presents a simple, effective and economical method of maximizing CRISPR/Cas9-mediated gene editing in primary human myoblasts. This protocol could be a valuable tool for improving the genetic manipulation of cultured human skeletal muscle cells, and potentially be adapted for use in other cell types.
Asunto(s)
Sistemas CRISPR-Cas , Edición Génica , Colágeno , Combinación de Medicamentos , Humanos , Laminina , Mioblastos , Proteoglicanos , TransfecciónRESUMEN
Nemaline myopathy (NM) is a congenital myopathy typically characterized by skeletal muscle weakness and the presence of nemaline bodies in myofibres. Approximately 25% of NM cases are caused by variants in ACTA1. We generated two induced pluripotent stem cell lines from lymphoblastoid cells of a 10-year-old female with typical NM harbouring a dominant pathogenic variant in ACTA1 (c.541C>A). The isogenic lines displayed typical iPSC morphology, expressed pluripotency markers, and could differentiate into each of the three germ layers. Although the lines have partial or complete X chromosome duplication, they may still prove useful as models of human ACTA1 disease.
Asunto(s)
Células Madre Pluripotentes Inducidas , Miopatías Nemalínicas , Actinas/genética , Niño , Femenino , Humanos , Músculo Esquelético , Mutación , Miopatías Nemalínicas/genéticaRESUMEN
Nemaline myopathy (NM) is a congenital myopathy typically characterized by skeletal muscle weakness and the presence of abnormal thread- or rod-like structures (nemaline bodies) in myofibres. Pathogenic variants in the skeletal muscle alpha actin gene, ACTA1, cause approximately 25% of all NM cases. We generated two induced pluripotent stem cell lines from lymphoblastoid cells of a 4-month-old female with severe NM harbouring a dominant variant in ACTA1 (c.553C > A). The isogenic lines displayed characteristic iPSC morphology, expressed pluripotency markers, differentiated into cells of all three germ layers, and possessed normal karyotypes. These lines could be useful models of human ACTA1 disease.
Asunto(s)
Células Madre Pluripotentes Inducidas , Miopatías Nemalínicas , Actinas/genética , Femenino , Humanos , Lactante , Músculo Esquelético , Mutación , Miopatías Nemalínicas/genéticaRESUMEN
During mammalian lymphoid development, Notch signaling is necessary at multiple stages of T lymphopoiesis, including lineage commitment, and later stages of T cell effector differentiation. In contrast, outside of a defined role in the development of splenic marginal zone B cells, there is conflicting evidence regarding whether Notch signaling plays functional roles in other B cell sub-populations. Complement receptor 2 (CR2) modulates BCR-signaling and is tightly regulated throughout differentiation. During B lymphopoiesis, CR2 is detected on immature and mature B cells with high surface expression on marginal zone B cells. Here, we have explored the possibility that Notch regulates human CR2 transcriptional activity using in vitro models including a co-culture system, co-transfection gene reporters and chromatin accessibility assays. We provide evidence that Notch signaling regulates CR2 promoter activity in a mature B cell line, as well as the induction of endogenous CR2 mRNA in a non-expressing pre-B cell line. The dynamics of endogenous gene activation suggests additional unidentified factors are required to mediate surface CR2 expression on immature and mature B lineage cells.
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Complemento C3d/genética , Células Precursoras de Linfocitos B/fisiología , Regiones Promotoras Genéticas/genética , Receptores de Complemento 3d/genética , Receptores Notch/genética , Transducción de Señal/genética , Transcripción Genética/genética , Linfocitos B/fisiología , Diferenciación Celular/genética , Línea Celular , Línea Celular Tumoral , Cromatina/genética , Técnicas de Cocultivo/métodos , Humanos , Células K562 , Activación de Linfocitos/genética , Linfopoyesis/genéticaRESUMEN
Ovine congenital progressive muscular dystrophy (OCPMD) was first described in Merino sheep flocks in Queensland and Western Australia in the 1960s and 1970s. The most prominent feature of the disease is a distinctive gait with stiffness of the hind limbs that can be seen as early as 3 weeks after birth. The disease is progressive. Histopathological examination had revealed dystrophic changes specifically in type I (slow) myofibres, while electron microscopy had demonstrated abundant nemaline bodies. Therefore, it was never certain whether the disease was a dystrophy or a congenital myopathy with dystrophic features. In this study, we performed whole genome sequencing of OCPMD sheep and identified a single base deletion at the splice donor site (+ 1) of intron 13 in the type I myofibre-specific TNNT1 gene (KT218690 c.614 + 1delG). All affected sheep were homozygous for this variant. Examination of TNNT1 splicing by RT-PCR showed intron retention and premature termination, which disrupts the highly conserved 14 amino acid C-terminus. The variant did not reduce TNNT1 protein levels or affect its localization but impaired its ability to modulate muscle contraction in response to Ca2+ levels. Identification of the causative variant in TNNT1 finally clarifies that the OCPMD sheep is in fact a large animal model of TNNT1 congenital myopathy. This model could now be used for testing molecular or gene therapies.
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Miotonía Congénita/patología , Miotonía Congénita/veterinaria , Enfermedades de las Ovejas/genética , Enfermedades de las Ovejas/patología , Troponina T/genética , Animales , Modelos Animales de Enfermedad , Músculo Esquelético/patología , OvinosRESUMEN
Nemaline myopathy (NM) caused by mutations in the gene encoding nebulin (NEB) accounts for at least 50% of all NM cases worldwide, representing a significant disease burden. Most NEB-NM patients have autosomal recessive disease due to a compound heterozygous genotype. Of the few murine models developed for NEB-NM, most are Neb knockout models rather than harbouring Neb mutations. Additionally, some models have a very severe phenotype that limits their application for evaluating disease progression and potential therapies. No existing murine models possess compound heterozygous Neb mutations that reflect the genotype and resulting phenotype present in most patients. We aimed to develop a murine model that more closely matched the underlying genetics of NEB-NM, which could assist elucidation of the pathogenetic mechanisms underlying the disease. Here, we have characterised a mouse strain with compound heterozygous Neb mutations; one missense (p.Tyr2303His), affecting a conserved actin-binding site and one nonsense mutation (p.Tyr935*), introducing a premature stop codon early in the protein. Our studies reveal that this compound heterozygous model, NebY2303H, Y935X, has striking skeletal muscle pathology including nemaline bodies. In vitro whole muscle and single myofibre physiology studies also demonstrate functional perturbations. However, no reduction in lifespan was noted. Therefore, NebY2303H,Y935X mice recapitulate human NEB-NM and are a much needed addition to the NEB-NM mouse model collection. The moderate phenotype also makes this an appropriate model for studying NEB-NM pathogenesis, and could potentially be suitable for testing therapeutic applications.
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Codón sin Sentido , Proteínas Musculares/genética , Mutación Missense , Miopatías Nemalínicas/genética , Miopatías Nemalínicas/patología , Animales , Modelos Animales de Enfermedad , Femenino , Masculino , Ratones Endogámicos C57BL , Músculo Esquelético/ultraestructuraRESUMEN
Name of the disease (synonyms) McArdle disease (glycogenosis type V; glycogen storage disease V (GSDV); PYGM deficiency; muscle glycogen phosphorylase deficiency; myophosphorylase deficiency). OMIM# of the disease #232600. Name of the analysed genes or DNA/chromosome segments Muscle glycogen phosphoryalse (PYGM). OMIM# of the gene(s) #608455.Review of the analytical and clinical validity as well as of the clinical utility of DNA-based testing for variants in the PYGM gene(s) inâ diagnostic,â predictive andâ prenatal settings and forâ risk assessment in relatives.
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Trastornos del Desarrollo Sexual/genética , Pruebas Genéticas , Enfermedad del Almacenamiento de Glucógeno Tipo V/genética , Trastornos del Desarrollo Sexual/fisiopatología , Enfermedad del Almacenamiento de Glucógeno Tipo V/fisiopatología , Humanos , Músculo Esquelético/patología , MutaciónRESUMEN
The pulmonary myocardium is a muscular coat surrounding the pulmonary and caval veins. Although its definitive physiological function is unknown, it may have a pathological role as the source of ectopic beats initiating atrial fibrillation. How the pulmonary myocardium gains pacemaker function is not clearly defined, although recent evidence indicates that changed transcriptional gene expression networks are at fault. The gene expression profile of this distinct cell type in situ was examined to investigate underlying molecular events that might contribute to atrial fibrillation. Via systems genetics, a whole-lung transcriptome data set from the BXD recombinant inbred mouse resource was analyzed, uncovering a pulmonary cardiomyocyte gene network of 24 transcripts, coordinately regulated by chromosome 1 and 2 loci. Promoter enrichment analysis and interrogation of publicly available ChIP-seq data suggested that transcription of this gene network may be regulated by the concerted activity of NKX2-5, serum response factor, myocyte enhancer factor 2, and also, at a post-transcriptional level, by RNA binding protein motif 20. Gene ontology terms indicate that this gene network overlaps with molecular markers of the stressed heart. Therefore, we propose that perturbed regulation of this gene network might lead to altered calcium handling, myocyte growth, and contractile force contributing to the aberrant electrophysiological properties observed in atrial fibrillation. We reveal novel molecular interactions and pathways representing possible therapeutic targets for atrial fibrillation. In addition, we highlight the utility of recombinant inbred mouse resources in detecting and characterizing gene expression networks of relatively small populations of cells that have a pathological significance.