Cardiac LXRα protects against pathological cardiac hypertrophy and dysfunction by enhancing glucose uptake and utilization
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE69355 | GEO | 2015/05/30
SECONDARY ACCESSION(S): PRJNA285288
REPOSITORIES: GEO
Similar Datasets
Project description:Pathological cardiac hypertrophy is characterized by a shift in metabolic substrate utilization from fatty acids to glucose, but the molecular events underlying the metabolic remodeling remain poorly understood. Here, we investigated the role of liver X receptors (LXRs), which are key regulators of glucose and lipid metabolism, in cardiac hypertrophic pathogenesis. Using a transgenic approach in mice, we show that overexpression of LXRα acts to protect the heart against hypertrophy, fibrosis, and dysfunction. Gene expression profiling studies revealed that genes regulating metabolic pathways were differentially expressed in hearts with elevated LXRα. Functionally, LXRα overexpression in isolated cardiomyocytes and murine hearts markedly enhanced the capacity for myocardial glucose uptake following hypertrophic stress. Conversely, this adaptive response was diminished in LXRα-deficient mice. Transcriptional changes induced by LXRα overexpression promoted energy-independent utilization of glucose via the hexosamine biosynthesis pathway, resulting in O-GlcNAc modification of GATA4 and Mef2c and the induction of cytoprotective natriuretic peptide expression. Our results identify LXRα as a key cardiac transcriptional regulator that helps orchestrate an adaptive metabolic response to chronic cardiac stress, and suggest that modulating LXRα may provide a unique opportunity for intervening in myocyte metabolism.
| S-EPMC4568954 | biostudies-literature
Project description:We aimed to determine the pathophysiological impact of heart rate (HR) slowing on cardiac function. We have recently developed a murine model in which it is possible to conditionally delete the stimulatory heterotrimeric G-protein (Gαs) in the sinoatrial (SA) node after the addition of tamoxifen using cre-loxP technology. The addition of tamoxifen leads to bradycardia. We used this approach to examine the physiological and pathophysiological effects of HR slowing. We first looked at the impact on exercise performance by running the mice on a treadmill. After the addition of tamoxifen, mice with conditional deletion of Gαs in the SA node ran a shorter distance at a slower speed. Littermate controls preserved their exercise capacity after tamoxifen. Results consistent with impaired cardiac capacity in the mutants were also obtained with a dobutamine echocardiographic stress test. We then examined if HR reduction influenced pathological cardiac hypertrophy using two models: ligation of the left anterior descending coronary artery for myocardial infarction and abdominal aortic banding for hypertensive heart disease. In littermate controls, both procedures resulted in cardiac hypertrophy. However, induction of HR reduction prior to surgical intervention significantly ameliorated the hypertrophy. In order to assess potential protein kinase pathways that may be activated in the left ventricle by relative bradycardia, we used a phospho-antibody array and this revealed selective activation of phosphoinositide-3 kinase. In conclusion, HR reduction protects against pathological cardiac hypertrophy but limits physiological exercise capacity.
| S-EPMC9761894 | biostudies-literature
Project description:The role of long noncoding RNA (lncRNA) in adult hearts is unknown; also unclear is how lncRNA modulates nucleosome remodelling. An estimated 70% of mouse genes undergo antisense transcription1, including myosin heavy chain 7 (Myh7), which encodes molecular motor proteins for heart contraction2. Here we identify a cluster of lncRNA transcripts from Myh7 loci and demonstrate a new lncRNA–chromatin mechanism for heart failure. In mice, these transcripts, which we named myosin heavy-chain-associated RNA transcripts (Mhrt), are cardiac-specific and abundant in adult hearts. Pathological stress activates the Brg1–Hdac–Parp chromatin repressor complex3 to inhibit Mhrt transcription in the heart. Such stress-induced Mhrt repression is essential for cardiomyopathy to develop: restoring Mhrt to the pre-stress level protects the heart from hypertrophy and failure. Mhrt antagonizes the function of Brg1, a chromatin-remodelling factor that is activated by stress to trigger aberrant gene expression and cardiac myopathy3. Mhrt prevents Brg1 from recognizing its genomic DNA targets, thus inhibiting chromatin targeting and gene regulation by Brg1. It does so by binding to the helicase domain of Brg1, a domain that is crucial for tethering Brg1 to chromatinized DNA targets. Brg1 helicase has dual nucleic-acid-binding specificities: it is capable of binding lncRNA (Mhrt) and chromatinized—but not naked—DNA. This dual-binding feature of helicase enables a competitive inhibition mechanism by which Mhrt sequesters Brg1 from its genomic DNA targets to prevent chromatin remodelling. A Mhrt–Brg1 feedback circuit is thus crucial for heart function. Human MHRT also originates from MYH7 loci and is repressed in various types of myopathic hearts, suggesting a conserved lncRNA mechanism in human cardiomyopathy. Our studies identify a cardioprotective lncRNA, define a new targeting mechanism for ATP-dependent chromatin-remodelling factors, and establish a new paradigm for lncRNA–chromatin interaction. Overexpression of murine non-coding RNAs in human cell line, comparison of RNA-sequencing with Ribosome Profiling
2014-08-05 | E-GEOD-49716 | biostudies-arrayexpress
Project description:In response to mechanical and pathological stress, adult mammalian hearts often undergo mal-remodeling, a process commonly characterized as pathological hypertrophy, which is associated with upregulation of fetal genes, increased fibrosis, and reduction of cardiac dysfunction. The molecular pathways that regulate this process are not fully understood.To explore the function of microRNA-155 (miR-155) in cardiac hypertrophy and remodeling.Our previous work identified miR-155 as a critical microRNA that repressed the expression and function of the myocyte enhancer factor 2A. In this study, we found that miR-155 is expressed in cardiomyocytes and that its expression is reduced in pressure overload-induced hypertrophic hearts. In mouse models of cardiac hypertrophy, miR-155 null hearts suppressed cardiac hypertrophy and cardiac remodeling in response to 2 independent pathological stressors, transverse aortic restriction and an activated calcineurin transgene. Most importantly, loss of miR-155 prevents the progress of heart failure and substantially extends the survival of calcineurin transgenic mice. The function of miR-155 in hypertrophy is confirmed in isolated cardiomyocytes. We identified jumonji, AT rich interactive domain 2 (Jarid2) as an miR-155 target in the heart. miR-155 directly represses Jarid2, whose expression is increased in miR-155 null hearts. Inhibition of endogenous Jarid2 partially rescues the effect of miR-155 loss in isolated cardiomyocytes.Our studies uncover miR-155 as an inducer of pathological cardiomyocyte hypertrophy and suggest that inhibition of endogenous miR-155 might have clinical potential to suppress cardiac hypertrophy and heart failure.
| S-EPMC4033580 | biostudies-literature
Project description:The role of long noncoding RNA (lncRNA) in adult hearts is unknown; also unclear is how lncRNA modulates nucleosome remodelling. An estimated 70% of mouse genes undergo antisense transcription1, including myosin heavy chain 7 (Myh7), which encodes molecular motor proteins for heart contraction2. Here we identify a cluster of lncRNA transcripts from Myh7 loci and demonstrate a new lncRNA–chromatin mechanism for heart failure. In mice, these transcripts, which we named myosin heavy-chain-associated RNA transcripts (Mhrt), are cardiac-specific and abundant in adult hearts. Pathological stress activates the Brg1–Hdac–Parp chromatin repressor complex3 to inhibit Mhrt transcription in the heart. Such stress-induced Mhrt repression is essential for cardiomyopathy to develop: restoring Mhrt to the pre-stress level protects the heart from hypertrophy and failure. Mhrt antagonizes the function of Brg1, a chromatin-remodelling factor that is activated by stress to trigger aberrant gene expression and cardiac myopathy3. Mhrt prevents Brg1 from recognizing its genomic DNA targets, thus inhibiting chromatin targeting and gene regulation by Brg1. It does so by binding to the helicase domain of Brg1, a domain that is crucial for tethering Brg1 to chromatinized DNA targets. Brg1 helicase has dual nucleic-acid-binding specificities: it is capable of binding lncRNA (Mhrt) and chromatinized—but not naked—DNA. This dual-binding feature of helicase enables a competitive inhibition mechanism by which Mhrt sequesters Brg1 from its genomic DNA targets to prevent chromatin remodelling. A Mhrt–Brg1 feedback circuit is thus crucial for heart function. Human MHRT also originates from MYH7 loci and is repressed in various types of myopathic hearts, suggesting a conserved lncRNA mechanism in human cardiomyopathy. Our studies identify a cardioprotective lncRNA, define a new targeting mechanism for ATP-dependent chromatin-remodelling factors, and establish a new paradigm for lncRNA–chromatin interaction.
2014-08-05 | GSE49716 | GEO
Project description:The heart adapts to increased workload through hypertrophic growth of cardiomyocytes. Although beneficial when induced physiologically by exercise, pathological cues including hypertension cause reexpression of fetal genes and dysfunctional hypertrophy, with lasting consequences for cardiac health. We hypothesised that these differences are driven by changes in chromatin-encoded cellular memory. We generated genome-wide maps of transcription and of two stable epigenetic marks, H3K9me2 and H3K27me3, specifically in hypertrophied cardiomyocytes, by selectively flow-sorting their nuclei. This demonstrated a pervasive loss of euchromatic H3K9me2 specifically upon pathological but not physiological hypertrophy, derepressing genes associated with pathological hypertrophy. Levels of the H3K9 methyltransferases, G9a and GLP, were correspondingly reduced. Importantly, pharmacological or genetic inactivation of these enzymes was sufficient to induce pathological hypertrophy and the dedifferentiation associated with it. These findings suggest novel therapeutic opportunities by defining an epigenetic state of cardiomyocytes, acquired during maturation, which is required for maintaining cardiac health.
2016-12-05 | GSE66653 | GEO
Project description:OBJECTIVE: The liver X receptor α (LXRα) is a ligand-dependent nuclear receptor and the major regulator of reverse cholesterol transport in macrophages. This makes it an interesting target for mechanistic study and treatment of atherosclerosis. METHODS AND RESULTS: We optimized a promising stilbenoid structure (STX4) in order to reach nanomolar effective concentrations in LXRα reporter-gene assays. STX4 displayed the unique property to activate LXRα effectively but not its subtype LXRβ. The potential of STX4 to increase transcriptional activity as an LXRα ligand was tested with gene expression analyses in THP1-derived human macrophages and oxLDL-loaded human foam cells. Only in foam cells but not in macrophage cells STX4 treatment showed athero-protective effects with similar potency as the synthetic LXR ligand T0901317 (T09). Surprisingly, combinatorial treatment with STX4 and T09 resulted in an additive effect on reporter-gene activation and target gene expression. In physiological tests the cellular content of total and esterified cholesterol was significantly reduced by STX4 without the undesirable increase in triglyceride levels as observed for T09. CONCLUSIONS: STX4 is a new LXRα-ligand to study transcriptional regulation of anti-atherogenic processes in cell or ex vivo models, and provides a promising lead structure for pharmaceutical development.
2013-09-05 | GSE39079 | GEO
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
2015-11-01 | E-GEOD-73597 | biostudies-arrayexpress
Project description:This project is the comparison of protein profiles for pathological and physiological mouse cardiac hypertrophy
2018-07-30 | PXD010165 | Pride
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.
2015-11-01 | GSE73597 | GEO