[Show abstract] [Hide abstract]
ABSTRACT: MicroRNAs play regulatory role in cardiovascular disease. MicroRNA-223 (miR-223) was found to be expressed abundantly in myocardium. TNNI3K, a novel cardiac troponin I (cTnI)-interacting and cardiac hypertrophy related kinase, is computationally predicted as a potential target of miR-223. This study was designed to investigate the cellular and molecular effects of miR-223 on cardiomyoctye hypertrophy, focusing on the role of TNNI3K.
Neonatal rat cardiomyocytes (CMs) were cultured, and CMs hypertrophy was induced by endothelin-1 (ET-1). In vivo cardiac hypertrophy was induced by transverse aorta constriction (TAC) in rats. Expression of miR-223 in CMs and myocardium was detected by real-time PCR (RT-PCR). MiR-223 and TNNI3K were overexpressed in CMs via chemically modifed sense RNA (miR-223 mimic) transfection or recombinant adenovirus infection, respectively. Cell size was measured by surface area calculation using fluorescence microscopy after anti-α-actinin staining. Expression of hypertrophy-related genes was detected by RT-PCR. The protein expression of TNNI3K and cTnI was determined by Western blots. Luciferase assay was employed to confirm the direct binding of miR-223 to the 3'UTR of TNNI3K mRNA. Intracellular calcium was measured by sensitive fluorescent indicator (Furo-2). Video-based edge detection system was employed to measure cardiomyocyte contractility.
MiR-223 was downregulated in ET-1 induced hypertrophic CMs and in hypertrophic myocardium compared with respective controls. MiR-223 overexpression in CMs alleviated ET-1 induced hypertrophy, evidenced by smaller cell surface area and downregulated ANP, α-actinin, Myh6 and Myh7 expression. Luciferase reporter gene assay showed that TNNI3K serves as a direct target gene of miR-223. In miR-223-overexpressed CMs, the protein expression of TNNI3K was significantly downregulated. MiR-223 overexpression also rescued the upregulated TNNI3K expression in hypertrophic CMs. Furthermore, cTnI phosphorylation was downregulated post miR-223 overexpression. Ad.rTNNI3K increased intracellular Ca(2+) concentrations and cell shortening in CMs, while miR-223 overexpression significantly rescued these hypertrophic effects.
By direct targeting TNNI3K, miR-223 could suppress CMs hypertrophy via downregulating cTnI phosphorylation, reducing intracellular Ca(2+) and contractility of CMs. miR-223 / TNNI3K axis may thus be major players of CMs hypertrophy. © 2015 S. Karger AG, Basel.
Cellular Physiology and Biochemistry 03/2015; 35(4):1546-1556. DOI:10.1159/000373970 · 2.88 Impact Factor
[Show abstract] [Hide abstract]
ABSTRACT: Mechanism of cold induced myocardial injury remained unclear. Our study investigated the role of ERK5/Bim pathway in hypothermal stimulation-induced apoptosis or damage of cardiomyocytes (CMs). Results showed that in CMs which under hypothermal stimulation, ERK5 siRNA promoted expression of Bim protein. Bim siRNA did not influence ERK5 expression but attenuated production of p-ERK5. ERK5 siRNA induced higher apoptosis rate; intracellular Ca(2+) overload; ROS activity; ΔΨm damage in hypothermia stimulated CMs, when compared with hypothermal stimulation solely treated group, while Bim siRNA effected oppositely and canceled pro-apoptotic effect of ERK5 siRNA. In conclusion, ERK5 knock down releases inhibition to Bim expression, induces aggravated apoptosis in CMs under hypothermal stimulation, which related to higher intracellular Ca(2+) overload, ROS activity, and more severe ΔΨm damage. Results revealed regulative role of ERK5/Bim pathway in hypothermal stimulation-induced injure or apoptosis of cardiomyocytes.
07/2013; 36(2):724-731. DOI:10.1016/j.etap.2013.06.012
Sheng li ke xue jin zhan [Progress in physiology] 06/2010; 41(3):235-7.
Zhongguo ying yong sheng li xue za zhi = Zhongguo yingyong shenglixue zazhi = Chinese journal of applied physiology 11/2009; 25(4):475-7.