Project description:Dysferlin is expressed in skeletal and cardiac muscle. However, dysferlin deficiency, namely limb girdle muscular dystrophy 2B (LGMD2B) and Myoshi myopathy, results in skeletal muscle weakness and spares the heart. This dichotomy could be caused by differential regulation of protective mechanisms. Therefore, we compared intraindividual mRNA expression profiles between cardiac and skeletal muscle in dysferlin-deficient SJL/J mice and normal C57BL/6 mice. Experiment Overall Design: 20 chips were analyzed. They represent 4 groups of 5 replicates each. Experiment Overall Design: The 4 groups are cardiac (LV) and skeletal muscle of normal and dysferlin deficient mice. Experiment Overall Design: Tissues from normal mice are the controls in comparison to tissues of dysferlin deficient mice.
Project description:Dysferlin is expressed in skeletal and cardiac muscle. However, dysferlin deficiency, namely limb girdle muscular dystrophy 2B (LGMD2B) and Myoshi myopathy, results in skeletal muscle weakness and spares the heart. This dichotomy could be caused by differential regulation of protective mechanisms. Therefore, we compared intraindividual mRNA expression profiles between cardiac and skeletal muscle in dysferlin-deficient SJL/J mice and normal C57BL/6 mice. Keywords: parallel sample
Project description:Adult-onset diseases can be associated with in utero events, but mechanisms for this remain unknown. The polycomb histone methyltransferase, Ezh2, stabilizes transcription by depositing repressive marks during development that persist into adulthood, but its function in postnatal organ homeostasis is unknown. We show that Ezh2 stabilizes cardiac gene expression and prevents cardiac pathology by repressing the homeodomain transcription factor Six1, which functions in cardiac progenitors but is stably silenced upon cardiac differentiation. Ezh2 deletion in cardiac progenitors caused postnatal myocardial pathology and destabilized cardiac gene expression with activation of Six1-dependent skeletal muscle genes. Six1 induced cardiomyocyte hypertrophy and skeletal muscle gene expression. Furthermore, genetically reducing Six1 levels rescued the pathology of Ezh2-deficient hearts. Thus, Ezh2-mediated repression of Six1 in differentiating cardiac progenitors is essential for stable postnatal heart gene expression and homeostasis. Our results suggest that epigenetic dysregulation in embryonic progenitor cells predisposes to adult disease and dysregulated stress responses. Four samples were analyzed. RNA was obtained from ventricles from two wild type and two Ezh2-deficient hearts.
Project description:During development of heart failure, capacity for cardiomyocyte fatty acid oxidation (FAO) and ATP production is progressively diminished contributing to pathologic cardiac hypertrophy and contractile dysfunction. Receptor interacting protein 140 (RIP140; Nrip1) has been shown to function as a transcriptional co-repressor of oxidative metabolism. Here we show that mice lacking RIP140 in striated muscle (strRIP140-/-) have increased expression of a broad array of involved in a broad array of mitochondrial energy metabolism and contractile function in heart and skeletal muscle. strRIP140-/- mice were resistant to the development of pressure overload-induced cardiac hypertrophy, and cardiomyocyte-specific RIP140 deficient (csRIP140-/-) mice were defended against development of heart failure caused by pressure overload combined with myocardial infarction. Genomic enhancers activated by RIP140 deficiency in cardiomyocytes were enriched in binding motifs for transcriptional regulators of mitochondrial function (estrogen-related receptor) and cardiac contractile proteins (myocyte enhancer factor 2). Consistent with a role in the control of cardiac fuel metabolism, loss of RIP140 in heart resulted in augmented triacylglyceride turnover and FA utilization. We conclude that RIP140 functions as a suppressor of a transcriptional regulatory network that controls cardiac fuel metabolism and contractile function, representing a potential therapeutic target for heart failure.
Project description:During development of heart failure, capacity for cardiomyocyte fatty acid oxidation (FAO) and ATP production is progressively diminished contributing to pathologic cardiac hypertrophy and contractile dysfunction. Receptor interacting protein 140 (RIP140; Nrip1) has been shown to function as a transcriptional co-repressor of oxidative metabolism. Here we show that mice lacking RIP140 in striated muscle (strRIP140-/-) have increased expression of a broad array of involved in a broad array of mitochondrial energy metabolism and contractile function in heart and skeletal muscle. strRIP140-/- mice were resistant to the development of pressure overload-induced cardiac hypertrophy, and cardiomyocyte-specific RIP140 deficient (csRIP140-/-) mice were defended against development of heart failure caused by pressure overload combined with myocardial infarction. Genomic enhancers activated by RIP140 deficiency in cardiomyocytes were enriched in binding motifs for transcriptional regulators of mitochondrial function (estrogen-related receptor) and cardiac contractile proteins (myocyte enhancer factor 2). Consistent with a role in the control of cardiac fuel metabolism, loss of RIP140 in heart resulted in augmented triacylglyceride turnover and FA utilization. We conclude that RIP140 functions as a suppressor of a transcriptional regulatory network that controls cardiac fuel metabolism and contractile function, representing a potential therapeutic target for heart failure.
Project description:Skeletal muscle dysfunction in survivors of pneumonia is a major cause of lasting morbidity that disproportionately affects older individuals. We found that skeletal muscle recovery was impaired in aged compared with young mice after influenza A virus-induced pneumonia. In young mice, recovery of muscle loss was associated with expansion of tissue-resident skeletal muscle macrophages and downregulation of MHC II expression, followed by a proliferation of muscle satellite cells. These findings were absent in aged mice and in mice deficient in Cx3cr1. Transcriptomic profiling of tissue-resident skeletal muscle macrophages from aged compared with young mice showed downregulation of pathways associated with phagocytosis and proteostasis, and persistent upregulation of inflammatory pathways. Consistently, skeletal muscle macrophages from aged mice failed to downregulate MHCII expression during recovery from influenza A virus induced pneumonia and showed impaired phagocytic function in vitro. Like aged animals, mice deficient in the phagocytic receptor Mertk showed no macrophage expansion, MHCII downregulation or satellite cell proliferation and failed to recover skeletal muscle function after influenza A pneumonia. Our data suggest that a loss of phagocytic function in a CX3CR1+ tissue-resident skeletal muscle macrophage population in aged mice precludes satellite cell proliferation and recovery of skeletal muscle function after influenza A pneumonia.
Project description:Adult-onset diseases can be associated with in utero events, but mechanisms for such temporally distant dysregulation of organ function remain unknown. The polycomb histone methyltransferase, Ezh2, stabilizes transcription by depositing repressive histone marks during development that persist into adulthood, but the function of Ezh2-mediated transcriptional stability in postnatal organ homeostasis is not understood. Here, we show that Ezh2 stabilizes the postnatal cardiac gene expression program and prevents cardiac pathology, primarily by repressing the homeodomain transcription factor Six1 in differentiating cardiac progenitors. Loss of Ezh2 in embryonic cardiac progenitors, but not in differentiated cardiomyocytes, resulted in postnatal cardiac pathology, including cardiomyocyte hypertrophy and fibrosis. Loss of Ezh2 caused broad derepression of skeletal muscle genes, including the homeodomain transcription factor Six1, which is expressed in cardiac progenitors but is normally silenced upon cardiac differentiation. Many of the deregulated genes are direct Six1 targets, implying a critical requirement for stable repression of Six1 in cardiac myocytes. Indeed, upon de-repression, Six1 promotes cardiac pathology, as it was sufficient to induce cardiac hypertrophy. Furthermore, genetic reduction of Six1 levels almost completely rescued the pathology of Ezh2-deficient hearts. Thus, repression of a single transcription factor in cardiac progenitors by Ezh2 is essential for stability of the adult heart gene expression program and homeostasis. Our results suggest that epigenetic dysregulation during discrete developmental windows can predispose to adult disease and dysregulated stress responses. Global gene expression profiles of Ezh2-deficient hearts. The right ventricle and the interventricular septum of five wild type (Ezh2f/f) and four Ezh2-deficient (Ezh2f/f;Mef2cAHF::Cre) mice were analyzed.
Project description:Rationale: We previously demonstrated that the transcription factor Sox6 regulates skeletal muscle biology by determining myofiber composition and muscle performance. Although the role of Sox6 and Sox5, its closest paralog, has not been ascertained in the heart, genome-wide association studies linked both Sox5 and Sox6 to cardiovascular disease. Objective: This study identifies the role of Sox5 and Sox6 in the adult mammalian heart under normal and stress conditions. Methods and Results: Using Sox5 and Sox6 cardiac-specific and Sox5 conduction system-specific knockout mice, we investigated the role of the two transcription factors in the heart under normal conditions and during cardiac stress. Sox5/6-deficient (DKO) mice displayed blunted cardiac contractility, which was present in Sox5 but not Sox6 single KO mice. DKO mice had a mild reduction in blood pressure, and conduction-specific knockout of Sox5 resulted in a reduced heart rate at baseline. After cardiac pressure overload, DKO mice showed increased lethality compared to control mice and were more prone to develop heart failure. We performed RNA deep sequencing in ventricles from DKO and control mice to identify potential Sox5/6 target genes and found altered expression of genes encoding regulators of calcium handling and cation transporters. Patch-clamping in isolated cardiomyocytes revealed shortened action potential duration in Sox5 KO cells. Conclusions: Unlike in skeletal muscle, our results suggest Sox5 but not Sox6 to be a major regulator of cardiac function and rhythm. Sox5 is essential to preserve cardiac function under normal conditions by maintaining contractility and to prevent cardiac failure after pressure overload.