microRNA-199a-5p mediates high glucose-induced reactive oxygen species production and apoptosis in INS-1 pancreatic beta-cells by targeting SIRT1

OBJECTIVE: Hyperglycemia-induced pancreatic a-cell loss is a pathologic hallmark of type 2 diabetes mellitus (T2DM). This study was conducted to clarify the function of microRNA (miR)-199a-5p in high glucose-elicited beta-cell toxicity and associated molecular mechanisms. MATERIALS AND METHODS: INS-1 rat pancreatic a-cells were cultured under normal (11 mM) or high (30 mM) glucose for 16-72 h and examined for miR-199a-5p expression. Gain and loss-of-function studies were performed to determine the role of miR-199a-5p in high glucoseinduced apoptosis and reactive oxygen species (ROS) production. Additionally, the involvement of SIRT1 in the action of miR-199a-5p was checked. RESULTS: High glucose caused a significant upregulation of miR-199a-5p in INS-1 cells compared to cells under normal glucose conditions. Pre-transfection with anti-miR-199a-5p inhibitors prevented the reduction in cell viability and inhibited ROS generation in INS-1 cells after high glucose treatment. In contrast, overexpression of miR-199a-5p significantly reduced cell viability and promoted apoptosis and ROS formation in INS-1 cells, which was coupled with a downregulation of SIRT1. Knockdown of SIRT1 led to apoptotic death in INS-1 cells. Moreover, enforced expression of SIRT1 blocked miR-199a5p-induced ROS generation and attenuated high glucose-mediated apoptosis in INS-1 cells. CONCLUSIONS: miR-199a-5p is upregulated in pancreatic a-cells in response to high glucose and promotes apoptosis and ROS generation by targeting SIRT1. The miR-199a-5p/SIRT1 axis may represent a promising target for the treatment of T2DM.