THE EFFECT OF MiRNA-29a AND MiRNA-21 ON ROS PRODUCTION IN PANCREATIC BETA CELLS BEARING ELEVATED LEVEL OF GLUCOSE

摘要

Type 2 Diabetes Mellitus (T2DM) is a complex, highly prevalent metabolic disease characterized by high levels of glucose, caused mainly by impairment in both insulin secretion and insulin action. The hallmarks of type 2 diabetes are beta cell dysfunction and insulin resistance. The resultant hyperglycemia leads to chronic oxidative stress for all tissues due to abnormally elevated concentrations of reactive oxygen species (ROS). The normal physiological level of ROS is important for cell signaling and defense from infections whereas pathologic increase in ROS cause oxidation of membrane lipids, modification of protein amino groups as well as deoxynucleotides leading to increased DNA mutation rate. The amount of data concerning the mechanism of mitochondrial ROS formation in β cells is limited and this issue is underexplored. MicroRNAs (miRNA) are post-transcriptional regulators of mRNA transcript and are suggested to have a significant role in the β cell function of sustaining glucose homeostasis. This project focuses on miRNA dependent ROS generation in order to elucidate the effects on mitochondrial function. For this purpose, we have used two miRNAs, which are glucose-related miR-29a and miR-21 to investigate production of ROS in the circumstances of elevated level of glucose. These miRNAs have already defined regulatory effect on pancreatic β cells function. In order to test the possible effect of miR-29a and miR-21 on the ROS level in different glucose environment, fluorescence activated cell sorter (FACS) analysis using INS-1E cells growing different glucose concentrations (5mM and 20mM) is performed. The results suggested that the over-expression of miR-29a trigger increase in ROS generation on INS-1E cell line where they were growing high level of glucose. However, even though over-expression of miR-21 exhibited decrease in ROS level profile, the results were not statistically significant compared to negative cells.