Project description:There is an emerging hypothesis that dilated cardiomyopathy (DCM) is a manifestation of end-stage heart failure (ESHF) resulting from “final common pathway” despite heterogeneous primary etiologies. We performed genome-wide expression profiling by means of high-density oligonucleotide microarrays using cardiac muscles from patients with DCM or specific cardiomyopathy as well as non-disease control hearts. Differentially expressed genes between ESHF and non-disease samples should include both genes reactive to heart failure (HF) and those responsible for ESHF. With the aid of samples with acute HF without DCM and those with DCM without HF (corrected with left ventricular assist device), we successfully distinguished ESHF genes from HF genes. Our findings implicate that transcriptional signature of cardiac muscle can be potentially applied as a diagnostic or prognostic tool for severe HF. Keywords: disease state analysis
Project description:Succinate dehydrogenase, which is known as mitochondrial complex II, has proven to be a fascinating machinery, attracting renewed and increased interest in its involvement in human diseases. Herein, we find that succinate dehydrogenase assembly factor 4 (SDHAF4) is downregulated in cardiac muscle in response to pathological stresses and in diseased hearts from human patients. Cardiac loss of Sdhaf4 suppresses complex II assembly and results in subunit degradation and complex II deficiency in fetal mice. These defects are exacerbated in young adults with globally impaired metabolic capacity and activation of dynamin-related protein 1, which induces excess mitochondrial fission and mitophagy, thereby causing progressive dilated cardiomyopathy and lethal heart failure in animals. Targeting mitochondria via supplementation with fumarate or inhibiting mitochondrial fission improves mitochondrial dynamics, partially restores cardiac function and prolongs the lifespan of mutant mice. Moreover, the addition of fumarate is found to dramatically improve cardiac function in myocardial infarction mice. These findings reveal a vital role for complex II assembly in the development of dilated cardiomyopathy and provide additional insights into therapeutic interventions for heart diseases.
Project description:Cardiac resident stem/progenitor cells are intensively studied as a potential therapeutic tool for cardiomyopathies. While surface marker expression and ability to generate cardiomyocytes have been characterized in some detail for several types of these progenitors, little is known on how their cardiac differentiation is regulated. Beta sarcoglycan null (bSG KO) mice are a model for limb girdle muscular dystrophy type 2E (LGMD2E), and are characterized by muscular dystrophy and progressive dilated cardiomyopathy. In the present study we isolated and characterized cardiac progenitors (mesoangioblasts) from the small vessels of neonatal hearts bSG KO mice and unexpectedly observed that they differentiate spontaneously into skeletal muscle fibers both in vitro and when transplanted in regenerating muscles and infarcted hearts. The micro array data showed that dystrophic cardiac progenitor and myogenic cells (C2C12) share similar gene expression profile. Keywords: Beta sarcoglycan null mice, muscular dystrophy, cardiac mesoangioblasts, myogenic differentiation Biological triplicates of cardiac wild-type and dystrophic mesoangioblasts isolated from different heart region (atrium, ventricle, aorta) were compared. C2C12 cells were used as positive control for myogenic differentiation.
Project description:There is an emerging hypothesis that dilated cardiomyopathy (DCM) is a manifestation of end-stage heart failure (ESHF) resulting from âfinal common pathwayâ despite heterogeneous primary etiologies. We performed genome-wide expression profiling by means of high-density oligonucleotide microarrays using cardiac muscles from patients with DCM or specific cardiomyopathy as well as non-disease control hearts. Differentially expressed genes between ESHF and non-disease samples should include both genes reactive to heart failure (HF) and those responsible for ESHF. With the aid of samples with acute HF without DCM and those with DCM without HF (corrected with left ventricular assist device), we successfully distinguished ESHF genes from HF genes. Our findings implicate that transcriptional signature of cardiac muscle can be potentially applied as a diagnostic or prognostic tool for severe HF. Experiment Overall Design: The expression profiles of approximately 20,227 genes were analyzed using a microarray, Human 1A ver.2 (Agilent Technologies). A total of 30 cardiac RNA samples (21 clinical samples and 9 purchased samples) were used in the hybridizations. 200ng of total RNA was used for T7 RNA polymerase-based cRNA labeling. The microarray experiments were then carried out using competitive hybridization experiments with Cy5-labeled heart RNAs as a test RNA and with Cy3-labeled pooled heart RNA (Sample N) as a template control for normalization. The glass slides were scanned using an Agilent G2565BA microarray scanner. Scanned images were then analyzed using Feature Extraction software. The average signal intensities were corrected for median background intensity and transferred with GenBank descriptors to a Microsoft Excel data spreadsheet (Microsoft, Redmond, WA). Experiment Overall Design: Data analysis was performed using Genespring software version 6.1 (Silicon Genetics, Redwood City, CA). To avoid âfalse positiveâ signals, we excluded certain genes from the analysis for which the average reference signal level constraints were under 70. After intensity dependent normalization (Lowess), the expression levels relative to the control were calculated as a ratio, and the expression profiles were then compared between each disease or normal sample. Statistical analysis was done using non-parametric tests. To order the samples according to the correlation coefficient, we applied âFind Similar Samplesâ algorithm using Spearman Correlation.
Project description:Cardiac resident stem/progenitor cells are intensively studied as a potential therapeutic tool for cardiomyopathies. While surface marker expression and ability to generate cardiomyocytes have been characterized in some detail for several types of these progenitors, little is known on how their cardiac differentiation is regulated. Beta sarcoglycan null (bSG KO) mice are a model for limb girdle muscular dystrophy type 2E (LGMD2E), and are characterized by muscular dystrophy and progressive dilated cardiomyopathy. In the present study we isolated and characterized cardiac progenitors (mesoangioblasts) from the small vessels of neonatal hearts bSG KO mice and unexpectedly observed that they differentiate spontaneously into skeletal muscle fibers both in vitro and when transplanted in regenerating muscles and infarcted hearts. The micro array data showed that dystrophic cardiac progenitor and myogenic cells (C2C12) share similar gene expression profile. Keywords: Beta sarcoglycan null mice, muscular dystrophy, cardiac mesoangioblasts, myogenic differentiation
Project description:Muscle-restricted coiled-coil protein (MURC)/Cavin-4, which is a component of caveolae, is involved in the pathophysiology of dilated cardiomyopathy and cardiac hypertrophy. We used microarrays to examine the gene expression of mouse hearts perturbed by MURC deficieny.
Project description:Cardiac metabolism is deranged in heart failure, but underlying mechanisms remain unclear. Lysine demethylase 8 (Kdm8) represses gene expression in the embryo and controls metabolism in cancer. However, its function in cardiac homeostasis is unknown. We show that Kdm8 maintains a mitochondrial gene network active by repressing Tbx15 to prevent dilated cardiomyopathy leading to lethal heart failure. Deletion of Kdm8 in mouse cardiomyocytes increased H3K36me2 with activation of Tbx15 and repression of target genes in the NAD+ pathway before dilated cardiomyopathy initiates. Moreover, NAD+ supplementation prevented dilated cardiomyopathy in Kdm8 mutant mice and TBX15 overexpression blunted NAD+-activated cardiomyocyte respiration. Furthermore, KDM8 was downregulated in human hearts affected by dilated cardiomyopathy and higher TBX15 expression defines a subgroup of affected hearts with the strongest downregulation of genes encoding mitochondrial proteins. Thus, KDM8 represses TBX15 to maintain cardiac metabolism. Our results suggest that epigenetic dysregulation of metabolic gene networks initiates myocardium deterioration towards heart failure and could underlie heterogeneity of dilated cardiomyopathy.
Project description:Cardiac metabolism is deranged in heart failure, but underlying mechanisms remain unclear. Lysine demethylase 8 (Kdm8) represses gene expression in the embryo and controls metabolism in cancer. However, its function in cardiac homeostasis is unknown. We show that Kdm8 maintains a mitochondrial gene network active by repressing Tbx15 to prevent dilated cardiomyopathy leading to lethal heart failure. Deletion of Kdm8 in mouse cardiomyocytes increased H3K36me2 with activation of Tbx15 and repression of target genes in the NAD+ pathway before dilated cardiomyopathy initiates. Moreover, NAD+ supplementation prevented dilated cardiomyopathy in Kdm8 mutant mice and TBX15 overexpression blunted NAD+-activated cardiomyocyte respiration. Furthermore, KDM8 was downregulated in human hearts affected by dilated cardiomyopathy and higher TBX15 expression defines a subgroup of affected hearts with the strongest downregulation of genes encoding mitochondrial proteins. Thus, KDM8 represses TBX15 to maintain cardiac metabolism. Our results suggest that epigenetic dysregulation of metabolic gene networks initiates myocardium deterioration towards heart failure and could underlie heterogeneity of dilated cardiomyopathy.
Project description:To establish changes in cardiac transcription profiles brought about by heart failure we collected myocardial samples from patients undergoing cardiac transplantation whose failure arises from different etiologies (e.g. idiopathic dilated cardiomyopathy, ischemic cardiomyopathy, alcoholic cardiomyopathy, valvular cardiomyopathy, and hypertrophic cardiomyopathy) and from "normal" organ donors whose hearts cannot be used for transplants. The transcriptional profile of the mRNA in these samples will be measured with gene array technology. Changes in transcriptional profiles can be correlated with the physiologic profile of heart-failure hearts acquired at the time of transplantation. Keywords: other
Project description:Changes in the gene expression in the heart of knock-in mouse model of dilated cardiomyopathy caused by delK210 mutation in cardiac troponin T.