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 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: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: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 damage caused for example by cardiac ischemia leads to ventricular volume overload resulting in increased stretch of the remaining myocardium. In adult mammals, these changes trigger an adaptive cardiomyocyte hypertrophic response which, if the damage is extensive, will ultimately lead to pathological hypertrophy and heart failure. Conversely, in response to extensive myocardial damage, cardiomyocytes in the adult zebrafish heart and neonatal mice proliferate and completely regenerate the damaged myocardium. We therefore hypothesized that in adult zebrafish, changes in mechanical loading due to myocardial damage may act as a trigger to induce cardiac regeneration. Based, on this notion we sought to identify mechanosensors which could be involved in detecting changes in mechanical loading and triggering regeneration. Here we show using a combination of knockout animals, RNAseq and in vitro assays that the mechanosensitive ion channel Trpc6a is required by cardiomyocytes for successful cardiac regeneration in adult zebrafish. Furthermore, using a cyclic cell stretch assay, we have determined that Trpc6a induces the expression of components of the AP1 transcription complex in response to mechanical stretch. Our data highlights how changes in mechanical forces due to myocardial damage can be detected by mechanosensors which in turn can trigger cardiac regeneration.
Project description:During brain wiring, mRNAs are trafficked into axons and growth cones where they are differentially translated in response to extrinsic signals. Differential control of local protein synthesis mediates neuronal compartment-specific behaviors that aid axon guidance. Yet little is understood about how specific mRNAs are selected for translation. Here we have investigated the local role of microRNAs (miRNAs) in mRNA-specific translation during axon pathfinding of Xenopus laevis retinal ganglion cell (RGC) axons. Profiling experiments revealed a rich repertoire of axonal miRNAs in developing RGC axons and identified miR-182 as one of the most abundant. Loss of miR182 impairs Slit2-induced growth cone repulsion and causes RGC axon targeting defects in vivo. To aid miRNA target prediction, we also profiled mRNA expression in RGC axons. Our results show that miR-182 targets cofilin1 mRNA in RGC growth cones and modulates its local translation in response to Slit2.