Project description:We generated transgenic mice with cardiac myocyte-specific overexpression of the mitochondrial RNA regulating protein FASTKD1 We then harvested hearts from 3-month-old non-transgenic and transgenic mice (4 mice in each group) and conducted gene expression profiling using RNA seq
Project description:Aims A kinase interacting protein 1 (AKIP1) stimulates physiological growth in cultured cardiomyocytes and attenuates ischemia / reperfusion (I/R) injury in ex vivo perfused hearts. We aimed to determine whether AKIP1 modulates the cardiac response to acute and chronic cardiac stress in vivo. Methods and results Transgenic mice with cardiac-specific overexpression of AKIP1 (AKIP1-TG) were created. AKIP1-TG mice and their wild type (WT) littermates displayed similar cardiac structure and function. Likewise, cardiac remodeling in response to transverse aortic constriction or permanent coronary artery ligation was identical in AKIP1-TG and WT littermates, as evidenced by serial cardiac magnetic resonance imaging and pressure-volume loop analysis. Histological indices of remodeling, including cardiomyocyte cross-sectional diameter, capillary density and left ventricular fibrosis were also similar in AKIP1-TG mice and WT littermates. When subjected to 45 minutes of ischemia followed by 24 hours of reperfusion, AKIP1-TG mice displayed a significant 2-fold reduction in myocardial infarct size and reductions in cardiac apoptosis. In contrast to previous reports, AKIP1 did not co-immunoprecipitate with or regulate the activity of the signaling molecules NF-κB, protein kinase A or AKT. AKIP1 was, however, enriched in cardiac mitochondria and co-immunoprecipitated with a key component of the mitochondrial permeability transition (MPT) pore, ATP-synthase. Finally, mitochondria isolated from AKIP1-TG hearts displayed markedly reduced calcium induced swelling, indicative of reduced MPT pore formation. Conclusions In contrast to in vitro studies, AKIP1 overexpression does not influence cardiac remodeling in response to chronic cardiac stress. AKIP1 does, however, reduce myocardial I/R injury through stabilization of the MPT pore. These findings suggest that AKIP1 deserves further investigation as a putative treatment target for cardioprotection from I/R injury during acute myocardial infarction.
Project description:Tumor Necrosis Factor-α is greatly implicated in heart pathophysiology, while it is upregulated in the failing myocardium. A major target in TNF-α-induced heart failure is the muscle specific intermediate filament cytoskeleton, comprised by desmin. We analysed the effect of cardiac-specific overexpression of TNF-α in the Des-/- myocardium, which is a known model of dilated cardiomyopathy. Hearts of 3 months old mice (n=3) of Des-/- and TNFαDes-/- genotypes were used for whole genome microarray hybridization analysis.
Project description:The goal of this study is to understand the function of cardiac tbx20 during heart regeneration. By high-throughput sequencing, molecular variations of tbx20-cardiac specific inducing heart in response to heart injury compared with control hearts were demonstrated. We collected the injured heart apex tissue at 7 days post injury and sequenced the transcriptome.
Project description:VEGF family members are important regulators of vascular functions. Promoting VEGFA signalling in aged mice has been shown to delay various aging phenotypes and extend the survival of aged mice. Although there is profound knowledge on functions of VEGFA, VEGFB has not been investigated in the context of cardiac aging. Our RNA data of aged mouse hearts revealed significant downregulation of Vegfb in the heart, specifically in endothelial cells and cardiomyocytes, while VEGFB expression was reduced in endothelial cells, fibroblasts and cardiomyocytes in aged human hearts. By contrast, VEGFB expression was exclusively reduced in cardiomyocytes of patients with cardiac hypertrophy. Hence, we investigated whether Vegfb gene therapy can revert age-dependent cardiac pathologies. We overexpressed Vegfb186, the soluble VEGFB isoform, via AAV9 vector transduction into 18-month-old C57Bl/6J male mice. AAV9-Vegfb treatment prevented progression age-related diastolic dysfunction and decreased cardiac fibrosis. We further found a rescue of aging-related left ventricular denervation in the hearts of AVV9-Vegfb treated old mice which was associated with an increase in heart rate variability. However, heart to body weight ratio and cardiomyocyte hypertrophy were increased in the AAV9-Vegfb treated mouse hearts, without alteration of cardiac systolic or diastolic function. Histological and transcriptomic analyses revealed that VEGFB186 induces compensatory cardiac hypertrophy which was accompanied by a rescued length-width-ratio, reduced fibrosis and the absence of cardiac inflammation. Cardiac single-nuclei RNA sequencing further suggested that AAV9-Vegfb treatment affects cardiac hypertrophy putatively via STAT3 which was validated in vitro. In conclusion, our data reveals that Vegfb overexpression partially reverses pathological alterations in the aging heart. Despite the overall improvement of the age-related cardiac phenotype, the AAV9-Vegfb-mediated induced cardiac hypertrophy which might reflect protective hypertrophy.
Project description:The intercalated disc of cardiac myocytes is emerging as a crucial structure in the heart. Loss of intercalated disc proteins like N-cadherin causes lethal cardiac abnormalities, mutations in intercalated disc proteins cause human cardiomyopathy. A comprehensive screen for novel mechanisms in failing hearts demonstrated that expression of the lysosomal integral membrane protein-2 (LIMP-2) is increased in cardiac hypertrophy and heart failure in both rat and human myocardium. Complete loss of LIMP-2 in genetically engineered mice did not affect cardiac development; however these LIMP-2 null mice failed to mount a hypertrophic response to increased blood pressure but developed cardiomyopathy. Disturbed cadherin localization in these hearts suggested that LIMP-2 has important functions outside lysosomes. Indeed, we also find LIMP-2 in the intercalated disc, where it associates with cadherin. RNAi-mediated knockdown of LIMP-2 decreases the binding of phosphorylated b-catenin to cadherin, while overexpression of LIMP-2 has the opposite effect. Taken together, our data show that lysosomal integrated membrane protein-2 is crucial to mount the adaptive hypertrophic response to cardiac loading. We demonstrate a novel role for LIMP-2 as an important mediator of the intercalated disc. Keywords: heart failure, comparison
Project description:The intercalated disc of cardiac myocytes is emerging as a crucial structure in the heart. Loss of intercalated disc proteins like N-cadherin causes lethal cardiac abnormalities, mutations in intercalated disc proteins cause human cardiomyopathy. A comprehensive screen for novel mechanisms in failing hearts demonstrated that expression of the lysosomal integral membrane protein-2 (LIMP-2) is increased in cardiac hypertrophy and heart failure in both rat and human myocardium. Complete loss of LIMP-2 in genetically engineered mice did not affect cardiac development; however these LIMP-2 null mice failed to mount a hypertrophic response to increased blood pressure but developed cardiomyopathy. Disturbed cadherin localization in these hearts suggested that LIMP-2 has important functions outside lysosomes. Indeed, we also find LIMP-2 in the intercalated disc, where it associates with cadherin. RNAi-mediated knockdown of LIMP-2 decreases the binding of phosphorylated b-catenin to cadherin, while overexpression of LIMP-2 has the opposite effect. Taken together, our data show that lysosomal integrated membrane protein-2 is crucial to mount the adaptive hypertrophic response to cardiac loading. We demonstrate a novel role for LIMP-2 as an important mediator of the intercalated disc. Experiment Overall Design: overall design: Experiment Overall Design: 3 groups of rats, 1 sample per rat: Experiment Overall Design: - compensated = Ren2 rat, hypertensive, no heart failure (N=6) Experiment Overall Design: - failure = Ren2 rat, hypertensive, no heart failure (N=4) Experiment Overall Design: - SD = control group, non-hypertensive (N=4)