Project description:Pathological cardiac hypertrophy, a dynamic remodeling process, is a major risk factor for heart failure. Although a number of key regulators and related genes have been identified, how the transcription factors (TFs) dynamically regulate the associated genes and control the morphological and electrophysiological changes during the hypertrophic process are still largely unknown. In this study, we obtained the time-course transcriptomes at five time points in four weeks from male murine hearts subjected to transverse aorta banding surgery. From a series of computational analyses, we identified three major co-expression modules of TF genes that may regulate the gene expression changes during the development of cardiac hypertrophy in mice. After pressure overload, the TF genes in Module 1 were up-regulated before the occurrence of significant morphological changes and one week later were down-regulated gradually, while those in Modules 2 and 3 took over the regulation as the heart size increased. Our analyses revealed that the TF genes up-regulated at the early stages likely initiated the cascading regulation and most of the well-known cardiac miRNAs were up-regulated at later stages for suppression. In addition, the constructed time-dependent regulatory network reveals some TFs including Egr2 as new candidate key regulators of cardiovascular-associated (CV) genes.
Project description:Pathological cardiac hypertrophy, a dynamic remodeling process, is a major risk factor for heart failure. Although a number of key regulators and related genes have been identified, how the transcription factors (TFs) dynamically regulate the associated genes and control the morphological and electrophysiological changes during the hypertrophic process are still largely unknown. In this study, we obtained the time-course transcriptomes at five time points in four weeks from male murine hearts subjected to transverse aorta banding surgery. From a series of computational analyses, we identified three major co-expression modules of TF genes that may regulate the gene expression changes during the development of cardiac hypertrophy in mice. After pressure overload, the TF genes in Module 1 were up-regulated before the occurrence of significant morphological changes and one week later were down-regulated gradually, while those in Modules 2 and 3 took over the regulation as the heart size increased. Our analyses revealed that the TF genes up-regulated at the early stages likely initiated the cascading regulation and most of the well-known cardiac miRNAs were up-regulated at later stages for suppression. In addition, the constructed time-dependent regulatory network reveals some TFs including Egr2 as new candidate key regulators of cardiovascular-associated (CV) genes.
Project description:Pressure overload-induced cardiac hypertrophy was examined in IL-18 knockout and littermate control mice. Experiment Overall Design: 4 groups with RNA pooled from 5-6 per group. Role of IL-18 on gene expression in cardiac hypertrophy induced by pressure overload (transaortic constriction)
Project description:Aims: Cardiac hypertrophy is a compensatory response to pressure overload, leading to heart failure. Recent studies have demonstrated that Rho is immediately activated in left ventricles after pressure overload, and that Rho signaling plays crucial regulatory roles in actin cytoskeleton rearrangement during cardiac hypertrophic responses. However, the mechanisms by which Rho and its downstream proteins control actin dynamics during hypertrophic responses remain not fully understood. In this study, we identified the pivotal roles of mammalian homologue of Drosophila diaphanous (mDia) 1, a Rho-effector molecule, in pressure overload-induced ventricular hypertrophy. Methods and Results: Male wild-type (WT) and mDia1-knockout (mDia1KO) mice (10–12 weeks old) were subjected to a transverse aortic constriction (TAC) or sham operation. The heart weight/tibia length ratio, cardiomyocyte cross-sectional area, left ventricular wall thickness, and expression of hypertrophy-specific genes were significantly decreased in mDia1KO mice 3 weeks after TAC, and the mortality rate was higher at 12 weeks. Echocardiography indicated that mDia1 deletion increased the severity of heart failure 8 weeks after TAC. Importantly, we could not observe apparent defects in cardiac hypertrophic responses in mDia3-knockout mice. Microarray analysis revealed that mDia1 was involved in the induction of hypertrophy related genes, including immediate early genes (IEGs), in pressure overloaded hearts. Loss of mDia1 attenuated activation of the mechanotransduction pathway in TAC-operated mice hearts. We also found that mDia1 was involved in stretch-induced activation of the mechanotransduction pathway and gene expression of c-fos in neonatal rat ventricular cardiomyocytes (NRVMs). mDia1 regulated the F/G-actin ratio in response to pressure overload in mice. Additionally, increases in nuclear myocardin-related transcription factors (MRTFs) and serum response factor (SRF) were perturbed in response to pressure overload in mDia1KO mice and to mechanical stretch in mDia1 depleted NRVMs. Conclusions: mDia1, through actin dynamics, is involved in compensatory cardiac hypertrophy in response to pressure overload.
Project description:Pressure overload (PO) leads first to cardiac hypertrophy and later to heart failure. In mice, PO leads to sex differences in cardiac morphology and function. However, early sex differences in gene regulation that precede sex differences in function have not yet been identified. To identify such changes, we developed a model of PO that is characterized by compensated hypertrophy without sex differences after 2 weeks and by heart failure with sex differences after 9 weeks. We used transverse aortic constriction (TAC) or sham-operation in male and female mice and analyzed gene expression by microarray experiments. Experiment Overall Design: The gene expression induced by pressure overload in female and male mice in comparison to sham operated control mice was investigated. For each of these four conditions four biological replicates were performed and the individual samples were hybridized seperately on Affymetrix RAE 430A GeneChip Arrays.
Project description:Atherosclerosis and pressure overload are major risk factors for the development of heart failure in patients. Cardiac hypertrophy often precedes the development of heart failure. However, underlying mechanisms are incompletely understood. To investigate pathomechanisms underlying the transition from cardiac hypertrophy to heart failure we used experimental models of atherosclerosis- and pressure overload-induced cardiac hypertrophy and failure, i.e. apolipoprotein E (apoE)-deficient mice, which develop heart failure at an age of 18 months, and non-transgenic C57BL/6J (B6) mice with heart failure triggered by 6 months of pressure overload induced by abdominal aortic constriction (AAC). The development of heart failure was monitored by echocardiography, invasive hemodynamics and histology. The microarray gene expression study of cardiac genes was performed with heart tissue from failing hearts relative to hypertrophic and healthy heart tissue, respectively. The microarray study revealed that the onset of heart failure was accompanied by a strong up-regulation of cardiac lipid metabolism genes involved in fat synthesis, storage and oxidation. Microarray gene expression profiling was performed with heart tissue isolated from (i) 18 month-old apoE-deficient mice relative to age-matched non-transgenic C57BL/6J (B6) mice, (ii) 6 month-old apoE-deficient mice with 2 months of chronic pressure overload induced by abdominal aortic constriction (AAC) relative to sham-operated apoE-deficient mice and nontransgenic B6 mice, (iii) 10 month-old B6 mice with 6 months of AAC relative to sham-operated B6 mice, and (iv) 5 month-old B6 mice with 1 month of AAC relative to age-matched B6 mice.