The modulation effects of Lipopolysaccharide on miR-211/Siert1 to enhance cardiomyocytes apoptosis induced by hypoxia / 中华急诊医学杂志

ABSTRACT

Objective To study the effect of Sirtuin1 (Sirt1) on the pathological process through its activity of deacetylation to improve the clinical outcome of acute sepsis. After searching data base, microRNA-211 (miR-211) was found to have action potentially targeting at Sirt1.The present study aimed to find the interaction between miR-211 and Sirt1 in the pathogenesis of hypoxic injury to cardiomyocytes in the presence of lipopolysaccharide ( LPS ) . Methods Primary neonatal rat cardiomyocytes ( NRC ) isolated from neonatal SD rats and H9c2 ( cardiomyocytes after culture with 10% fetal serum of cattle and DMEM under 37 ℃ and 5% CO2 ) cell line were used in the experiments.The miR-211 expression was quantified by qRT-PCR after LPS exposure for 4 hours, and the changes in Sirt1 protein level were also detected in both NRC and H9c2 by western blot.At the same time, CCK-8 assay and TUNEL staining were also performed to measure cell proliferation and apoptosis activation when either treated with LPS alone or followed by exposure to hypoxia.Results Compared to the control group, the doses of 20μg/mL, 40μg/mL LPS treatment for 4 hours had no significant effects on H9c2 cell proliferation at 24 h, 48 h, 72 h, but it could significantly induce the cell apoptosis of neonatal rat cardiomyocytes and H9c2 cells after hypoxia, and the apoptosis rate increased all over 100% in both NRC and H9c2.At the same time, LPS treatment could significant up-regulate miR-211 expression which was closely associated with decrease in Sirt1 protein levels.Conclusions LPS enhanced cardiomyocytes injury after exposure to hypoxia which was closely associated with up-regulating miR-211 expression and in turn to suppress Sirt1 expression.