Effect Of TNNI3K On The Expression Of SDF-1 In Cardiomyocytes After Myocardial Ischemic Injury And Its Mechanism

BackgroundMyocardial infarction is one of the most serious diseases that endangering the lives of human being.Although the treatment of acute myocardial infarction has been significantly improved,there are still a large amount of post-infarction patients eventually died of heart failure inevitably.TNNI3 K is a newly discovered cardiac specific kinase,which can be combined with cardiac troponin I(cTnI)and specifically expressed in cardiomyocytes.The new study has shown that the expression of TNNI3 K increased in anoxic myocardial cells,which promotes cardiac myogenesis,improves cardiac function and reduces ventricular remodeling.SDF-1 has a myocardial protective effect after ischemia or hypoxia,and can stimulate bone marrow-derived stem cells from the bone marrow to the ischemic heart,thereby promoting blood vessel regeneration and maintaining the survival of cardiomyocytes.However,whether TNNI3 K affects the expression of SDF-1 and its regulatory mechanism has not been reported.ObjectiveTo investigate the expression of TNNI3 K and SDF-1 in ischemia-reperfusion injury of heart,and to explore the mechanism of TNNI3 K on SDF-1.Methods(1)In vivo: The expression and location of TNNI3 K and SDF-1 in Myocardial cells after myocardial infarction was detected by immunohistochemistry.The model of ischemia and reperfusion injury for C57 BL / 6 mice was constructed,and then the mice were sacrificed at the first day,the third day,the fifth day and the seventh day respectively to detect the expression of TNNI3 K and SDF-1 around the border zone of myocardial infarction by Western Blot.The expression of TNNI3 K and SDF-1 in myocardial tissue around the infarcts was detected by Western Blot in the C57 BL / 6 adult mice,which has being treated with lentivirus for overexpression of TNNI3 K five days ago.(2)In vitro: After primary incubation of myocardial cells,the cells were treated with hypoxia incubator?siRNA for TNNI3 K and SB203580 respectively,and then the expression of TNNI3 K,p-P38 and SDF-1 protein was detected by Western Blot.The supernatant was used to detect the secretion of SDF-1 by ELISA.Western Blot and PCR were used to detect the protein and mRNA level of TNNI3 K and SDF-1 respectively after TNNI3 K been interfered by siRNA or overexpressed by lentivirus.Results1.The protein expression of TNNI3 K and SDF-1 was significantly increased in cardiomyocytes after myocardial infarction or hypoxia.In mouse model of ischemiareperfusion injury,TNNI3 K and SDF-1 were increased at the being and then declined with the time;Overexpression of TNNI3 K by lentivirus caused the expression of SDF-1 protein increased in the myocardial tissue around the infarcts,indicating that TNNI3 K can promote the accumulation of SDF-1 in the border zone after myocardial infarction.2.In hypoxic neonatal mice cardiomyocytes,after siRNA interfering or lentivirus overexpressing the TNNI3 K,SDF-1 decreased or increased at the protein level accordingly,but the change was not obvious at the PCR level,suggesting that maybe the regulation of SDF-1 by TNNI3 K was regulated by post-transcriptional level.Treating with SB203580,the inhibition of P38 phosphorylation,SDF-1 significantly reduced,indicating that TNNI3 k may regulate SDF-1 expression by the phosphorylation of P38 in ischemic heart diseases.Conclusions1.Hypoxia and ischemia can induce the upregulation of TNNI3 K and SDF-1 protein level,and overexpress or interference the expression of TNNI3 K,SDF-1 increased or decreased accordingly.2.In ischemic heart diseases,TNNI3 K may regulate the expression of SDF-1 by the phosphorylation of P38.