This study aims to investigate the role of calreticulin in (CRT) pressure overload induced cardiac hypertrophy. In our study, cardiac hypertrophy was induced by left ventricular pressure overload in male SD rats subjected to transverse aortic constriction (TAC) operation. Expression of gene and protein of calreticulin, markers of cardiac hypertrophy and endoplasmic reticulum stress (ERS) were measured with real-time qPCR and Western blot respectively. Meanwhile, atorvastatin (a known ERS inhibitor) and calreticulin-specific small interference ribonucleic acid (siRNA) were used to inhibit the expression of ERS and calreticulin respectively. The experimental data demonstrated that the gene and protein levels of calreticulin, hypertrophic and ERS markers were increased significantly in the heart tissues of TAC rat models after 4 weeks. Moreover, atorvastatin administration improved the cardiac function and reduced the expression of calreticulin and ERS markers in TAC rats. In addition, cultured primary neonatal rat cardiomyocytes (NCMs) were treated with norepinephrine (NE), angiotensionⅡ (AngⅡ) or isoprenaline (ISO) to induce hypertrophic phenotype and ERS. The expression of hypertrophic markers was reduced in NCMs transfected with calreticulin-siRNA. The results suggested that calreticulin might be a promising target for the treatment of cardiac hypertrophy.
This study aimed to explore the role of miR-130a-3p in cardiomyocyte hypertrophy and its underlying mechanisms. Pressure-overload induced myocardial hypertrophy mice model was constructed by thoracic aortic constriction (TAC). In vitro, norepinephrine (NE) was used to stimulate neonatal rat cardiomyocytes (NRCMs) and H9c2 rat cardiomyocytes to induce hypertrophic phenotypes. The expression of miR-130a-3p was detected in mice hypertrophic myocardium, hypertrophic NRCMs and H9c2 cells. The mimics and inhibitors of miR-130a-3p were transfected into H9c2 cells to observe the role of miR-130a-3p on the hypertrophic phenotype change of cardiomyocytes separately. Furthermore, whether miR-130a-3p regulated hypertrophic related signaling pathways was explored. The results showed that the expression of miR-130a-3p was significantly decreased in hypertrophic myocardium, hypertrophic NRCMs and H9c2 cells. After transfection of miR-130a-3p mimics, the expression of hypertrophic marker genes, atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP) and β-myosin heavy chain (β-MHC), and the cell surface area were notably down-regulated compared with the control group (mimics N.C. + NE group). But after transfection of miR-130a-3p inhibitor, the expression of ANP, BNP and β-MHC in H9c2 cells increased significantly, and the cell area increased further. By Western blot, it was found that the protein phosphorylation level of Akt and mTOR were down-regulated after over-expression of miR-130a-3p. These results suggest that miR-130a-3p mimics may alleviate the degree of cardiomyocyte hypertrophy, meanwhile its inhibitor can further aggravate cardiomyocyte hypertrophy. Over-expression of miR-130a-3p may attenuate cardiomyocytes hypertrophy by affecting the Akt pathway.