Abnormal Expression of MST1 and YAP1 in Fetal Heart Tissue in a Hyperglycemic Environment and Their Roles in Mediating Apoptosis

Abstract Background：Gestational diabetes mellitus is a risk factor for congenital heart defects. The article aimed to investigate the expression and roles of Mst1, Yap1, Last1/2 and Survivin in modulating HG-induced cardiomyocyte apoptosis and maternal diabetes-induced heart abnormality. Methods：The gene and protein expression were assessed by quantitative PCR, western blot, and immunohistochemical staining. The protein phosphorylation level were analyzed by western blot .Knockdown of gene expression were assessed by RNA interference. Hoechst 33342 staining assay were performed to explore H9C2 apoptosis. Diabetes mellitus was induced in rats using streptozotocin.Results：Our results revealed that increased MST1 protein levels in the heart tissues of the offspring of diabetic rats in vivo occurred concomitantly with HG-induced apoptosis in H9C2 cardiomyocytes in vitro. Knockdown and overexpression experiments showed that MST1 played a key role in mediating HG-induced apoptosis in cardiomyocytes. Downregulation of YAP1 was associated with HG-induced, MST1-mediated cardiomyocyte apoptosis. Further study showed that MST1 downregulated the protein level of YAP1 through mediation of YAP1 phosphorylation on Ser127 and Ser397; this process also required LATS1/2 participation. MST1 overexpression increased the phosphorylation levels of LATS1/2, which were also shown to be increased in the heart tissues of diabetic offspring. We also found that YAP1 mediated the expression of Survivin during HG-induced apoptosis, and the Survivin-inhibitor YM155 partially inhibited the role of YAP1 in suppressing apoptosis induced by HG in cardiomyocytes. Conclusion：These findings reveal a regulatory mechanism of MST1/YAP1/Survivin signaling in modulating cardiomyocyte apoptosis in vitro and maternal diabetes-induced congenital heart defects in vivo.