MiR-29a mediates the apoptotic effects of TNF- on endothelial cells through inhibiting PI3K/AKT/BCL-2 axis

Endothelial cell apoptosis driven by inflammation (TNF-alpha) plays a critical role in the pathogenesis of atherosclerosis, but the exact molecular mechanisms are not clearly elucidated. MicroRNA (miR)-29 families (a/b/c) take important roles in pathophysiological processes of atherosclerosis, also the underlying mechanisms have not been fully clarified. The aims are to explore whether or not miR-29 families mediate the apoptotic effects of TNF-alpha on endothelial cells and uncover the underlying molecular mechanisms. In this study, MTT assay and flow cytometer analysis were employed respectively to determine the proliferation and apoptosis of human umbilical vascular endothelial cells (HUVECs) under TNF-alpha exposure. Real-time quantitative PCR and western blot were performed to detect the levels of target RNAs and proteins/their phosphorylation in HUVECs. TNF-alpha could inhibit HUVEC proliferation and induce HUVEC apoptosis in a positive dose-and time-dependent manner, with a similar way of miR-29a upregulation, but no effects on miR-29b/c. Upregulation of miR-29a with its mimics enhanced the apoptotic effect of TNF-alpha on HUVECs, but downregulation of miR-29a using anti-miR-29a blocked up its apoptotic effect. MiR-29a inhibited the expression of PI3Kp85 alpha and Bcl-2 and blocked up the signal transduction of PI3K/AKT/Bcl-2 axis to mediate the apoptotic effect of TNF-alpha on HUVECs. Mediating the inflammation-driven endothelial cell apoptosis is an important biology mechanism by which miR-29a promotes atherosclerosis and its complications. MiR-29a will be a potential diagnostic and therapeutic target for atherosclerotic cardiovascular diseases; it is worthwhile to further study.