Study On The Function Of PiR-10555 In Regulating Cardiomyocyte Apoptosis

Objective The dynamic imbalance of cardiomyocyte apoptosis is closely related to the pathological process of myocardial injury caused by acute myocardial infarction and reperfusion.And cardiomyocyte apoptosis is often accompanied by morphological changes of mitochondria,such as mitochondrial fission.At present,the specific mechanism of cardiomyocyte apoptosis in the pathological process of myocardial ischemia-reperfusion（I/R）injury is not clear.Piwi interaction RNA（piRNA）is a new type of non-coding small RNA.It has been found that piRNA is involved in the process of cancer,aging and cardiovascular disease,but the roles of piRNA in heart diseases remains to be fully elucidated.The results of pre-experiment showed that compared with the sham-operated（Sham）group,there were significant differences in the expression of several piRNA in the hearts of C57BL/6J strain mice treated with I/R injury,in which the expression of piR-10555was significantly different and specifically expressed in the heart tissue.It is suggested that piR-10555 may be involved in the regulation of cardiomyocyte apoptosis.Therefore,in order to reveal whether piR-10555 regulates cardiomyocyte apoptosis,we intend to study the regulatory function of piR-10555 on cardiomyocyte apoptosis at cellular and animal level,so as to provide a theoretical basis for clinical application of piRNA.Methods The primary cardiomyocytes isolated from the heart of male and female suckling mice were used as the research object.Agomir-piR-10555 was transfected into the cardiomyocytes to overexpressing piR-10555.The apoptosis of cardiomyocytes was detected by Tunel staining,and the mitochondrial fission of cardiomyocytes was observed by mitochondrial staining.Cardiomyocyte apoptosis was induced by H₂O₂in vitro.Antagomir-piR-10555 was transfected into cardiomyocytes to knock down the expression of endogenous piR-10555.The apoptosis of cardiomyocytes and mitochondrial fission were detected.The expression of piR-10555 was detected by q RT-PCR technique.In vivo,piR-10555 was knocked down by injection of adenovirus and myocardial ischemia-reperfusion injury was induced by I/R operation.The changes of cardiomyocyte apoptosis were observed by Tunel staining.Result 1.In the heart,liver,spleen,kidney and stomach of C57 BL/6J mice,the expression level of piR-10555 was the highest in the heart;2.When primary cardiomyocytes were treated with H₂O₂for 0 h,6h,12 h and 24 h,respectively,it was found that the expression level of piR-10555 increased significantly at 24 h;3.In vitro,cardiomyocytes with overexpression of piR-10555,increased apoptosis and mitochondrial fission,while cardiomyocytes induced by knocking down piR-10555,H₂O₂decreased apoptosis and mitochondrial fission;4.In vivo,in mouse myocardial infarction model,piR-10555 knocked down inhibited the increase of cardiomyocyte apoptosis rate induced by I/R.Conclusion Results show that at the cellular level,overexpression of piR-10555 can promote cardiomyocyte apoptosis;knockdown of endogenous piR-10555 can inhibit cardiomyocyte apoptosis induced by H₂O₂;in vivo experiments confirmed that knockdown of piR-10555 inhibited cardiomyocyte apoptosis induced by I/R.The specific conclusions are as follows:1.In primary cardiomyocytes,H₂O₂induced up-regulation of piR-10555 expression,and overexpression of piR-10555 promoted cardiomyocyte apoptosis and mitochondrial fission;2.In primary cardiomyocytes,knockdown of the endogenous piR-10555 inhibits cardiomyocyte apoptosis and mitochondrial fission induced by H₂O₂;3.In vivo,in mouse myocardial ischemia-reperfusion injury model,knockdown of piR-10555 inhibited the cardiomyocyte apoptosis induced by I/R.