Project description:In this study, we aim to characterize the developmental and hypertrophy-specific, or in vitro myocyte dedifferentiation-specific genes by combining the current data set of transcriptomes in fetal cardiomyocytes (ECM, E15.5), normal adult cardiomyocytes (ACM) and hypertrophic cardioymocytes (hypertrophy induced by trans-aortic constriction; TAC; 7-days post-op), with our other data set (GSE49448 -- Transcriptomic and Epigenetic Signatures of Mouse Cardiac Progenitor Cells). Differential gene expression analysis was performed to generate cell type-specific genes, including the subsets of genes important for maturity (versus dedifferentiation, immature) and cell cycle control.
Project description:Pressure overload induces a transition from cardiac hypertrophy to heart failure, but its underlying mechanisms remain elusive. Here we reconstruct a trajectory of cardiomyocyte remodeling and clarify distinct cardiomyocyte gene programs encoding morphological and functional signatures in cardiac hypertrophy and failure, by integrating single-cardiomyocyte transcriptome with cell morphology, epigenomic state and heart function. During early hypertrophy, cardiomyocytes activate mitochondrial translation/metabolism genes, whose expression is correlated with cell size and linked to ERK1/2 and NRF1/2 transcriptional networks. Persistent overload leads to a bifurcation into adaptive and failing cardiomyocytes, and p53 signaling is specifically activated in late hypertrophy. Cardiomyocyte-specific p53 deletion shows that cardiomyocyte remodeling is initiated by p53-independent mitochondrial activation and morphological hypertrophy, followed by p53-dependent mitochondrial inhibition, morphological elongation, and heart failure gene program activation. Human single-cardiomyocyte analysis validates the conservation of the pathogenic transcriptional signatures. Collectively, cardiomyocyte identity is encoded in transcriptional programs that orchestrate morphological and functional phenotypes.
Project description:Pressure overload induces a transition from cardiac hypertrophy to heart failure, but its underlying mechanisms remain elusive. Here we reconstruct a trajectory of cardiomyocyte remodeling and clarify distinct cardiomyocyte gene programs encoding morphological and functional signatures in cardiac hypertrophy and failure, by integrating single-cardiomyocyte transcriptome with cell morphology, epigenomic state and heart function. During early hypertrophy, cardiomyocytes activate mitochondrial translation/metabolism genes, whose expression is correlated with cell size and linked to ERK1/2 and NRF1/2 transcriptional networks. Persistent overload leads to a bifurcation into adaptive and failing cardiomyocytes, and p53 signaling is specifically activated in late hypertrophy. Cardiomyocyte-specific p53 deletion shows that cardiomyocyte remodeling is initiated by p53-independent mitochondrial activation and morphological hypertrophy, followed by p53-dependent mitochondrial inhibition, morphological elongation, and heart failure gene program activation. Human single-cardiomyocyte analysis validates the conservation of the pathogenic transcriptional signatures. Collectively, cardiomyocyte identity is encoded in transcriptional programs that orchestrate morphological and functional phenotypes.
Project description:: The adult heart develops hypertrophy to reduce ventricular wall stress and maintain cardiac function in response to an increased workload. Although pathological hypertrophy generally progresses to heart failure, physiological hypertrophy may be cardioprotective. Cardiac-specific overexpression of the lipid-droplet protein perilipin 5 (Plin5) promotes cardiac hypertrophy, but it is unclear if this response is beneficial. We analyzed human RNA-sequencing data from the left ventricle and showed that cardiac PLIN5 expression correlates with upregulation of cardiac contraction-related processes. To investigate how elevated cardiac Plin5 levels affect cardiac contractility, we generated mice with cardiac-specific overexpression of Plin5 (MHC-Plin5 mice). These mice displayed increased left ventricular mass and cardiomyocyte size but preserved heart function. Quantitative proteomics identified sarcoplasmic/endoplasmic reticulum Ca2+ ATPase 2 (SERCA2) as a Plin5-interacting protein. Phosphorylation of phospholamban, the master regulator of SERCA2, was increased in MHC-Plin5 versus wild-type cardiomyocytes. Live imaging showed increases in intracellular Ca2+ release during contraction, Ca2+ removal during relaxation, and SERCA2 function in MHC-Plin5 versus wild-type cardiomyocytes. These results identify a role for Plin5 in improving cardiac contractility through enhanced Ca2+ signaling.
Project description:PIWI-interacting RNAs (piRNAs) are abundantly expressed during cardiac hypertrophy development, but their influence on pathological hypertrophy and the underlying mechanisms remains to be elucidated. Here, we identified a cardiac-hypertrophy-associated piRNA (CHAPIR), and we found that it regulates pathological hypertrophy. To investigate the molecular mechanisms by which CHAPIR regulates cardiomyocyte hypertrophy, we transfected the biotinylated CHAPIR into cardiomyocytes and performed streptavidin bead pull down assay. The CHAPIR pull-down materials and its control were resolved using SDS-PAGE gel and stained with coomassie blue. Then the entire gel lanes of the CHAPIR pull-down materials and its control were excised and send for liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis.
Project description:Purpose: The physiological cardiac hypertrophy is an adaptive condition that does not associate with myocyte cell death while pathological hypertrophy is a maladaptive condition associated with myocyte cell death. Alpha-2 macroglobulin (α-2M) an acute phase protein induces cardiac hypertrophy via the ERK1,2 and PI3K/Akt signaling. This study is aimed at exploring the miRNome of α-2M induced hypertrophied cardiomyocytes and to understand the role of miRNAs in determination of pathological and physiological hypertrophy. Methods: Hypertrophy was induced in H9c2 cardiomyoblasts using alpha-2 macroglobulin. The induction of hypertrophy is confirmed by microscopy and gene expression studies. Subsequently, the total RNA was isolated and small RNA sequencing was executed in Illumina HiSeq 2000. Results: Analysis of small RNA reads revealed the differential expression of a large set of miRNAs during hypertrophy. Among the differentially expressed candidates, miR-99 family (miR-99a, miR-99b and miR-100) showed significant downregulation upon α-2M treatment while isoproterenol treatment (pathological hypertrophy) upregulated their expression. The binding site for Egr1 transcription factor was identified in the promoter region of miR-99 family, and interestingly all miRNAs with Egr1 binding site proven by ChIP-Seq were downregulated during physiological hypertrophy Conclusions: The results proved Egr-1 mediated regulation of miR-99 family determines the uniqueness of pathological and physiological hypertrophy. Upregulated miR-99 expression during pathological hypertrophy suggests that it can be a valuable diagnostic marker and potential therapeutic target for cardiac hypertrophy and heart failure. Small RNA profiles of control and hypertrophied cardiomyocyte H9c2 cells were generated by deep sequencing using Illumina HiSeq 2000
Project description:The study of the mechanisms leading to cardiac hypertrophy is essential to better understand cardiac development and regeneration. Pathological conditions such as ischemia or pressure overload can induce a release of extracellular nucleotides within the heart. We recently investigated the potential role of nucleotide P2Y receptors in cardiac development. We showed that adult P2Y4-null mice displayed microcardia resulting from defective cardiac angiogenesis. Here we show that loss of another P2Y subtype called P2Y6, a UDP receptor, was associated with a macrocardia phenotype and amplified pathological cardiac hypertrophy. Cardiomyocyte proliferation and size were increased in vivo in hearts of P2Y6-null neonates, resulting in enhanced post-natal heart growth. We then observed that loss of P2Y6 receptor enhanced pathological cardiac hypertrophy induced after isoproterenol injection. We identified an inhibitory effect of UDP on in vitro isoproterenol-induced cardiomyocyte hyperplasia and hypertrophy. The present study identifies mouse P2Y6 receptor as a regulator of cardiac development and cardiomyocyte function. P2Y6 receptor could constitute a therapeutic target to regulate cardiac hypertrophy.
Project description:Pathological cardiac hypertrophy is featured by enhanced protein synthesis. Translation inhibition is effective in treating cardiac hypertrophy, yet with systematic side effect. We identified a cardiac-enriched LncRNA CARDINAL, when over-expressed in cardiomyocyte using AAV9 driven by cTNT promoter, ameliorate transaortic constriction (TAC) induced hypertrophy.
Project description:Kinase-catalyzed phosphorylation plays crucial roles in numerous biological processes. CDC-like kinases (CLKs) are a group of evolutionarily conserved dual-specificity kinases that have been implicated in RNA splicing, glucose metabolism, diet-induced thermogenesis and so on. However, it is still largely unknown whether CLKs are involved in pathologic cardiac hypertrophy. This study aimed to investigate the role of CLKs in pathologic cardiac hypertrophy and the underlying mechanisms. Using small RNA interference, we discovered that defects in CLK4, but not CLK1, CLK2 or CLK3, were associated with the pathogenesis of pathological cardiomyocyte hypertrophy, while overexpression of CLK4 exerted resistance to isoproterenol-induced pathological cardiomyocyte hypertrophy. Moreover, the expression of CLK4 was significantly reduced in the failed myocardia of mice subjected to either transverse aortic constriction or isoproterenol infusion. Through the Cre/loxP system, we constructed cardiac-specific Clk4-knockout (Clk4-cKO) mice, which manifested pathological myocardial hypertrophy with progressive left ventricular systolic dysfunction and heart dilation. Phosphoproteomic analysis revealed significant changes in phosphorylation of sarcomere-related proteins in Clk4-cKO mice. Further experiments identified nexilin (NEXN), an F-actin binding protein, as the direct substrate of CLK4, and overexpression of a phosphorylation-mimic mutant of NEXN was sufficient to reverse the hypertrophic growth of cardiomyocytes induced by Clk4 knockdown. Importantly, restoring the phosphorylated NEXN significantly ameliorated the myocardial hypertrophy in Clk4-cKO mice. CLK4 phosphorylates NEXN to regulate the development of pathological cardiac hypertrophy. CLK4 may serve as a potential intervention target for the prevention and treatment of heart failure.