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Neonatal mice adopt to pressure overload by inducing cardiomyocyte proliferation and angiogenesis

ABSTRACT: Backgound: Cardiac pressure overload, for example in patients with aortic stenosis, induces irreversible damage in the myocardium leading to cardiac dysfunction, cardiomyocyte hypertrophy and interstitial fibrosis. We therefore hypothesized that insufficient cardiac regeneration might contribute to the progression of pressure overload dependent disease. Here, we aimed to elucidate whether pressure overload in the regenerative stage shortly after birth could lead to a more adaptive cardiac response than in the non-regenerative stage in mice.nTAC in the non-regenerative stage induced cardiac dysfunction, myocardial fibrosis and cardiomyocyte hypertrophy. In contrast, during induction of nTAC in the regenerative stage, cardiac function remained intact and this was associated with enhanced myocardial angiogenesis and innervation as well as increased cardiomyocyte proliferation, but neither hypertrophy nor fibrosis. Mechanistically, inhibition of cardiomyocyte proliferation and angiogenesis in nTAC in the regenerative phase by rapamycin triggered mortality and myocardial fibrosis, which both also similarly occurred upon inhibition of angiogenesis by PTK787, suggesting that both processes are essential for the adaptive cardiac response to nTAC. A comparative genome-wide transcriptomic analysis between hearts after nTAC in the regenerative versus the non-regenerative stage defined differentially expressed functional gene classes, and a related bioinformatics analysis suggested the transcription factor GATA4 as master regulator of the regenerative gene-program. Indeed, cardiomyocyte specific deletion of GATA4 converted the regenerative nTAC into a non-regenerative, maladaptive response.tablished a new model of neonatal pressure-overload in mice, which when applied in the regenerative postnatal stage, triggers a purely adaptive myocardial response. Employing this model to identify new regulators might lead to novel therapeutic strategies to combat pressure overload induced myocardial disease.

ORGANISM(S): Mus musculus

PROVIDER: GSE121308 | GEO | 2019/07/26

REPOSITORIES: GEO

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Project description:Aims: Cardiomyocyte-specific nitric oxide synthase 3 (NOS3) overexpression reduces left ventricular (LV) remodelling after myocardial infarction in mice, but its effect on sustained LV pressure-overload remains incompletely understood. We investigated LV structural and functional adaptation to elevated afterload in mice with cardiomyocyte-restricted NOS3 overexpression (NOS3TG) and wild type littermates (WT). Methods and Results: Hemodynamic indices, cardiac hypertrophy and interstitial fibrosis were measured 10 weeks after transverse aortic constriction (TAC). After 10 weeks TAC, NOS3TG had better preserved systolic function (maximum rates of pressure development normalized to maximal pressure 77Â±6 versus 65Â±2 ms-1, P=0.05), reduced heart weight-body weight ratio (HW/BW, 5.0Â±0.3 versus 5.8Â±0.1, P<0.05), and cardiomyocyte width than WT (14.9Â±0.4 vs 16.7Â±0.2 ?m, P<0.05). After 10 weeks TAC, a 44k cDNA chip-based microarray analysis was validated using real time PCR and revealed significantly altered expression pattern of genes involved in cellular growth, matrix remodelling, and inflammation between genotypes. Conclusions: Cardiomyocyte-restricted NOS3 overexpression attenuates TAC-induced hypertrophy via autocrine inhibition of cardiomyocyte cell growth, but does not mitigate myocardial fibrosis. The subsequent diastolic dysfunction suggests that inhibition of matrix producing cells during hypertrophic stress is necessary to prevent functional and structural deterioration of the pressure-overloaded heart. Left ventricular mRNA expression profiles were compared between alpha-myosin heavy chain driven nitric oxide synthase 3 (alpha-MHC-NOS3) transgenic and wild type (WT) littermate mice at baseline and 10 weeks after transversal aortic constrcition-induced pressure-overload. Biological repeats: n=4, two males and two females, for each group and condition. Transgenic mice were backcrossed for seven generations (F7) to a C57Bl/6 N background and age and weight matched animals were used for microarray experiments.

Project description:Background: Pathological cardiac overload triggers maladaptive myocardial remodeling that predisposes to the development of heart failure. The contribution of long non-coding RNAs (lncRNAs) to intercellular signaling during cardiac remodeling is largely unknown. Methods: We analyzed the expression of Gadlor 1 and Gadlor2 lncRNAs in mouse hearts, mouse cardiac cells, extracellular vesicles (EVs), human failing hearts as well as patient serum. Gadlor knock-out (KO) mice were generated and analyzed. The effect of Gadlor knock-out and Gadlor overexpression during cardiac pressure overload induced by transverse aortic constriction (TAC) was analyzed by echocardiography, histological analyses and RNA sequencing in isolated cardiac cells. Gadlor1/2 interaction partners were identified by RNA antisense purification coupled with mass-spectrometry (RAP-MS). Results: In the heart, the related lncRNAs Gadlor1 and 2 are mainly expressed in endothelial cells and to a lesser extent in fibroblasts. Gadlor1/2 are upregulated in failing mouse hearts as well as in the myocardium and in serum of heart failure patients. Interestingly, Gadlor1 and 2 are secreted from endothelial cells within EVs, which are taken up by cardiomyocytes. Gadlor-KO mice exerted reduced cardiomyocyte hypertrophy, diminished myocardial fibrosis and improved cardiac function, but paradoxically suffered from sudden death during prolonged overload. Gadlor overexpression, in turn, triggered hypertrophy, fibrosis and cardiac dysfunction. Mechanistically, Gadlor1 and Gadlor2 inhibit angiogenic gene expression in endothelial cells, while promoting the expression of pro-fibrotic genes in cardiac fibroblasts. In cardiomyocytes, Gadlor1/2 upregulate mitochondrial genes, but downregulate angiogenesis genes, while interacting with the transcriptional regulator Glyr1 and the calcium/calmodulin-dependent protein kinase type II (CaMKII), entailing cardiomyocyte hypertrophy and perturbed cardiomyocyte calcium dynamics. Conclusions: We describe that Gadlor1 and 2, two related, novel lncRNAs, are upregulated in cardiac pathological overload and are secreted from endothelial cells within EVs. Gadlor1/2 induce cardiac dysfunction, cardiomyocyte hypertrophy and myocardial fibrosis by exerting heterocellular effects on cardiac cellular gene-expression and by affecting calcium dynamics in cardiomyocytes, which take up the Gadlor1/2 by EV mediated transfer from endothelial cells. Targeted inhibition of Gadlor lncRNAs in endothelial cells or fibroblasts might serve as therapeutic strategy in the future.

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Neonatal mice adopt to pressure overload by inducing cardiomyocyte proliferation and angiogenesis

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