Effects Of Reactive Oxygen Species On Expression Of PTENmRNA In INS-1 Cells

Diabetes causes metabolic disoder of glucose,fat and protein,leading to various clinical complications which causing disability and death of patients.Diabetes,with its high incidence,seriously threatens the health and life of patients,resulting in enormous suffering and burden of the family and society.Moreover,there has not been an effective way to eliminate diabetes until now.Therefore,understanding the mechanism and regulatory pathways of insulin secretion may play an important role in searching for the new target for improving insulin secretion and curing diabetes.ROS is now considered to function as a ubiquitous intracellular messenger at subtoxic concentrations.High glucose can stimulate insulin secretion in isolated mouse islet and 1NS-1 cells,accompanied by an increase of ROS.Low levels of ROS can also stimulate insulin secretion in isolated mouse islet and INS-1 cells.Taken together,these findings suggest that ROS derived from glucose metabolism is one of the metabolic singnals for insulin secretion.PTEN is a member of the PTP family.By negatively modulating the PI3-kinase-AKT signaling pathway,PTEN functions as an important tumor suppressor and regulates celluler activities.The essential Cys¹²⁴ residue of human PTEN,which is surrounded by three basic amino acid residues in the active site pocket,is readily oxidized by H₂O₂,resulting in the formation of an intramolecular disulfide with Cys⁷¹.It is reported that ROS,including H₂O₂ regulates many celluler activities through reversablely oxidized ande inhibited the activity of PTEN.However,questions remain unknown:Does ROS derived from glucose metabolism in beta-cells act as one of the metabolic signals for insulin secretion through regulating the expression of PTEN gene? In order to answer this question,the followings have been done.At first,the INS-1 cells were exposed to high glucose(0,3,7,11 and 20mmol/L)and low levels of concentration of H202(0,1,2,4,6 and 20umol/L) for 30 minites.Then, ELISA method was used to detect insulin secretion of the INS-1 cells.The DCFH-DA method was used to detect the concentration of ROS of the 1NS-1 cells.The RT-PCR method was used to detect the expression of PTENmRNA.We observed that the insulin secretion and the concentration of ROS in INS-1 cells increased as the concentration of glucose and H₂O₂ increased;The expression of PTENmRNA in cells exposed to high glucose and H₂O₂ decreased compared with that of the comparion cells.These results suggested that the increase of ROS stimulated by glucose in INS-1 cells may act as one of the metabolic singnals for insulin secretion through inhibiting the expression of PTEN gene.