Study Role Of Pdx1and Its Mechanism In Activating Ngn3and Pax6to Induce Differentiation Of IPSCs Into Isletβ Cells

【Objective】To investigate role of pancreatic and duodenal homeobox factor1（Pdx1） and itsmechanism in differentiating induced pluripotent stem cell(iPSCs）into islet β cells.【Methods】iPSCs deriving from human skin fibroblasts were cultured in vitro and directionallyinduced to differentiate for20days by small molecule compounds. During these20days,the expression of insulin-related genes,which were MafA, insulin, Glut2, Nkx6.1,Glucokinase and Tcf1,was detected by Real Time-Polymerase Chain Reaction(RT-PCR)every2days. Then, the expression of some important transcription factors, which werePdx1, neurogenin3(Ngn3) and paired box gene6(Pax6), was compared by RT-PCRbefore and after the differentiation process. Specific sites of the promoter regions whichwere combined with Pdx1,the most pivotal transcription factor in the islet β cellsdevelopment process, were detected by Chromatin Immunoprecipitation(ChIP).【Results】iPSCs deriving from human skin fibroblasts were cultured successfully in vitro.Insulin-related genes that were MafA, insulin, Glut2, Nkx6.1, Glucokinase and Tcf1showed varying degrees of enhanced expression during the20-day-differentiation process,and the expression almost reached a peak on the20thday. After induced by small molecule compounds step by step, the expression of transcription factors Pdx1, Ngn3and Pax6in the experimental group was strengthened compared with that of control group. ChIPassay confirmed that Pdx1activates the expression of the downstream transcription factorsNgn3and Pax6by combined with Insulin-P、Ngn3-P、Pax6-P.【Conclusion】Pdx1is the agonist of insulin gene, and Pdx1activates downstream transcriptionfactors Ngn3and Pax6may be one of the mechanisms that promotes directional inducingdifferentiation of iPSCs deriving from human skin fibroblasts into islet β cells.