| Diabetes is a disease caused by metabolic disorders which due to defects in insulin secretion or insulin dysfunction.Today,the mortality rate of diabetes is greater than the sum of AIDS,tuberculosis and malaria.With the rapid increase of diabetes incidence all over the world and the heavy financial burden caused by diabetes,to find a treatment which has high effect,low cost and side effects is still a serious problem.Diabetes are related to the number and function of islet ? cells.Pancreatic and duodenal homeobox1(Pdx1)is an improtant factor to regulate the proliferation,differentiation and function of islet ? cells.So,it is a new idea and strategy to target Pdx1 to screen anti-diabetes drugs with the purpose to protect and promote the function of islet ? cells.In our previous study,we have constructed a screening model using Pdx1 promoter to drive the expression of luciferase reporter gene and found that natural compound TI95,extracted from plants,could activate Pdx1 promoter and promote the expression of Pdx1 in islet ? cells.Here in this study,the purpose is to further study the effects of TI95 on Pdx1 and islet ? cells.The main results and conclusions are as follows:1.TI95 can promote the expression of the Pdx1 gene.By using real time RT-PCR and Western blot,TI95 was demonstrated to be able to enhance the expression of Pdx1 at both transcriptional and protein levels in islet ? cell line,RIN-m5 F and INS-1 cells respectively.2.TI95 promoted the expression of the Pdx1 in islet ? cells through activation of ERK signaling pathway.Upon T195 treatment,the level of phosphorylated ERK was upregulated at different time points in RIN-m5 F and INS-1 cells,indicating that T195 could activate ERK signaling.Then we found that U0126,an inhibitor of ERK signaling pathway could reverse the promotion effects of TI95 on the expression of Pdx1 in islet ? cells,suggesting that TI95 might enhance the expression of Pdx1 by activating ERK pathway.3.T195 can prevent islet ? cells from damage of high sugar and high fat.We first established the injury models of islet ? cells induced by high glucose and fatty acid through MTT.By using these models,we found that T195 could partially restore the viability of damaged islet ? cell lines induced by high glucose and high fatty acid.4.The mechanisms underlying the protective effects of T195 on islet ? cells were investigated.Flow cytometry was used to examine high fatty acid induced INS-1apoptosis which was further certificated by detecting apoptotic proteins such as caspase-3 and cleaved caspase-3 through Western Blot.However,T195 treatment could reduce the occurrence of INS-1 apoptosis induced by high fat.Then,we further examined the expression of Pdx1 and found that high fat could reduce the expression of Pdx1 in damaged INS-1 cells,but TI95 reversed the expression of Pdx1 to nearly normal level.Finally,we demonstrated that U0126 treatment abolished the protective effect of TI95 on high-fat injured INS-1 cells by using MTT cell viability assay.In conclusion,natural comound TI95 can increase the expression of Pdx1 in islet ? cells by activating ERK signaling pathway and it plays a protective role on glucotoxicity and lipotoxicity induced islet ? celldamagethrough inhibiting apopotosis,which is associated with its ability on Pdx1 expression promotion and ERK activation.Therefore,TI95 might be a new promising anti-diabetes drug with Pdx1 as the therapeutic target in future. |
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