Project description:Angiogenesis induced by placental growth factor (PlGF) in heart promotes myocardial hypertrophy through the paracrine action of endothelium-derived nitric oxide which triggers the degradation of RGS4 and subsequent the activation of Akt/mTORC1 pathway in cardiomyocytes. However, whether alterations in miRNAs contribute to the development of hypertrophy is largely undetermined. We found that miR-182 contributed to the hypertrophic response and activation of Akt/mTORC1 pathway by suppressing the expression of Bcat2, Pink1, Adcy6, Foxo3. miR-182 targeted genes were investigated in the mouse model of myocardial angiogenesis induced by conditional, cardiac specific expression of PlGF. We also induced angiogenesis, but blocked hypertrophy by concomitant expression of PlGF and RGS4 (PlGF/RGS4 mice). The mRNA expression profiling in PlGF and PlGF/RGS4 mice were assessed after 6 weeks of transgene expression, concurent with the development of myocardial hypertrophy.
Project description:Angiogenesis induced by placental growth factor (PlGF) in heart promotes myocardial hypertrophy through the paracrine action of endothelium-derived nitric oxide which triggers the degradation of RGS4 and subsequent activation of the Akt/mTORC1 pathway in cardiomyocytes. However, whether alterations in miRNAs contribute to the development of hypertrophy is largely undetermined. We found that miR-182 contributed to the hypertrophic response and activation of the Akt/mTORC1 pathway by suppressing the expression of Bcat2, Pink1, Adcy6, Foxo3. The expression of miRNAs and the effects of anti-miRs were investigated in the mouse model of myocardial angiogenesis induced by conditional, cardiac specific expression of PlGF. We also induced angiogenesis, but blocked hypertrophy by concomitant expression of PlGF and RGS4 (PlGF/RGS4 mice). Microarray profiling of miRNAs in LV myocardium was determined after 3 and 6 weeks of transgene expression.
Project description:Angiogenesis induced by placental growth factor (PlGF) in heart promotes myocardial hypertrophy through the paracrine action of endothelium-derived nitric oxide which triggers the degradation of RGS4 and subsequent activation of the Akt/mTORC1 pathway in cardiomyocytes. However, whether alterations in miRNAs contribute to the development of hypertrophy is largely undetermined. We found that miR-182 contributed to the hypertrophic response and activation of the Akt/mTORC1 pathway by suppressing the expression of Bcat2, Pink1, Adcy6, Foxo3.
Project description:Angiogenesis induced by placental growth factor (PlGF) in heart promotes myocardial hypertrophy through the paracrine action of endothelium-derived nitric oxide which triggers the degradation of RGS4 and subsequent the activation of Akt/mTORC1 pathway in cardiomyocytes. However, whether alterations in miRNAs contribute to the development of hypertrophy is largely undetermined. We found that miR-182 contributed to the hypertrophic response and activation of Akt/mTORC1 pathway by suppressing the expression of Bcat2, Pink1, Adcy6, Foxo3.
Project description:Aims: Mesenchymal stem cells (MSCs) gradually become attractive candidates for cardiac inflammation modulation, yet understanding of the mechanism remains elusive. Strikingly, recent studies indicated that exosomes secreted by MSCs might be a novel mechanism for the beneficial effect of MSCs transplantation after myocardial infarction. We therefore explored the role of MSC-derived exosomes (MSC-Exo) in the immunomodulation of macrophages after myocardial ischemia-reperfusion and its implications in cardiac injury repair. Methods and Results: Exosomes were isolated from the supernatant of MSCs using a gradient centrifugation method. Administration of MSC-Exo through intramyocardial injection after myocardial ischemia reperfusion reduced infarct size and alleviated inflammation level in heart and serum. Systemic depletion of macrophages with clodronate liposomes abolished the curative effects of MSC-Exo. MSC-Exo modified the polarization of M1 macrophages to M2 macrophages both in vivo and in vitro. miRNA-sequencing of MSC-Exo and bioinformatics analysis implicated miR-182 as a potent candidate mediator of macrophage polarization and TLR4 as a downstream target. Diminishing miR-182 in MSC-Exo partially attenuated its modulation of macrophage polarization. Likewise, knock down of TLR4 also conferred cardioprotective efficacy and reduced inflammation level in a mouse model of myocardial ischemia/reperfusion. Conclusion: Our data indicates that MSC-Exo attenuates myocardial ischemia/reperfusion injury via shuttling miR-182 that modifies the polarization state of macrophages. This study sheds new light on the application of MSC-Exo a potential therapeutic tool for myocardial ischemia/reperfusion injury.
Project description:To explore the pathogenesis of myocardial hypertrophy, Proteomic Analysis was performed to identify the differentially expressed proteins in the human myocardial tissues of non-hypertrophic control and myocardial hypertrophy patients. We used echocardiography to detect the thickness of the ventricular septum in patients undergoing heart valve replacement surgery .The thickness of the ventricular septum over 11mm is defined as myocardial hypertrophy of patients, those less than or equal to 11mm were considered as non-hypertrophic controls. We collected a total of 6 cases of non-hypertrophic controls and 6 cases of myocardial hypertrophy patients' myocardial tissues, and Proteomic Analysis was performed by mass spectrometry.
Project description:Myocardial hypertrophy develops when the heart is subjected to biomechanical stress, neurohormonal or hemodynamic stimuli. Isoprenaline-induced myocardial hypertrophy in mice exhibited abnormally elevated steroid receptor RNA activator (SRA) level in hypertrophic myocardium, suggesting SRA’s potential functions in hypertrophic pathogenesis. SRA knockout or cardiac-specific knockdown attenuated cardiac remodeling without impairing baseline cardiac function. RNA sequencing and mechanistic studies identified SRA as a transcriptional coactivator that enhances GR-mediated upregulation of HSP70, which in turn activates pro-hypertrophic Akt signaling. Adenoviral SRA overexpression in H9C2 cardiomyocytes amplified isoprenaline-triggered hypertrophic gene expression via this GR-HSP70-Akt axis. Those findings establish SRA as a stress-responsive regulator of maladaptive cardiac growth and propose SRA inhibition as a targeted therapeutic strategy for hypertrophy-related cardiomyopathy. This work bridges noncoding RNA biology with metabolic signaling in heart disease, offering both mechanistic insights and translational potential.
Project description:Background: Pathological upregulation of G protein-coupled receptor kinase 2 (GRK2) is a hallmark of heart failure and contributes to maladaptive signaling, hypertrophic remodeling, and cardiomyocyte death. MicroRNAs (miRNAs) are key post-transcriptional regulators of cardiac stress responses, however whether GRK2 is subject to miRNA targeting has not yet been fully established. Objective: We investigated potential miR-181a-mediated regulation of GRK2 in cardiomyocytes to better understand its effects on cardiac stress responses. Methods: miRNA microarray profiling was performed on mouse hearts two weeks after myocardial infarction. Bioinformatic target prediction analysis identified candidate miRNAs that are predicted to bind GRK2 in the 3’ untranslated region (UTR). Direct binding was assessed using luciferase reporter assays, and miR-181a was selected as the miRNA of interest to further pursue mechanistic and functional validation. miR-181a was overexpressed or inhibited in neonatal rat ventricular myocytes (NRVMs) and exposed to several modes of cellular stress to induce hypertrophy, hypoxia, and accumulation of reactive oxygen species. GRK2 expression, hypertrophic remodeling, oxidative stress, cell viability, and cyclic AMP (cAMP) signaling were assessed using quantitative PCR, immunoblotting, fluorescence imaging, and biochemical assays. Results: miR-181a directly targeted the GRK2 3′UTR and suppressed GRK2 expression at both mRNA and protein levels. miR-181a overexpression attenuated stress-induced hypertrophic gene expression, reduced cardiomyocyte cell size, decreased oxidative stress, improved survival under hypoxia, and enhanced cAMP production under β-AR stimulation. Conversely, inhibition of miR-181a resulted in sustained GRK2 expression, exacerbated hypertrophic signaling, and decreased cAMP production. Conclusion: These findings identify miR-181a as a functional post-transcriptional regulator of GRK2 that limits maladaptive signaling, hypertrophic remodeling, and cardiomyocyte injury. miR-181a-mediated GRK2 inhibition represents a potential therapeutic strategy for mitigating pathological signaling in heart failure.