Pdxl and its role in activating Ngn3 and Pax6 to induce differentiation of iPSCs into islet β cells.

The pancreatic and duodenal homeobox factor 1 (Pdx1) protein is the most pivotal transcription factor in the development of islet β cells. This study investigated the role of Pdx1 and its mechanism in differentiating induced pluripotent stem cells (iPSCs) into islet β cells. iPSCs derived from human skin fibroblasts were cultured in vitro and directionally induced to differentiate for 20 days. The expression of insulin-related genes was then detected by RT-PCR, and the expression of several differentiation-related transcription factors was assessed both before and after the differentiation process. Lastly, the specific promoter regions where Pdx1 binds were detected by ChIP. The insulin-related genes, MafA, insulin, Glut2, Nkx6.1, GCK, and Tcf1, showed increased expression during differentiation, and nearly peaked on the 20th day. Similarly, the expression of transcription factors, Pdx1, Ngn3, and Pax6 showed enhanced expression during differentiation as compared with that of the control group. ChIP experiments confirmed that Pdx1 activates the expression of the downstream transcription factors, Ngn3 and Pax6, by combined with the promoter regions of insulin (Insulin-P), Ngn3 (Ngn3-P), and Pax6 (Pax6-P). In conclusion, Pdx1 activates downstream transcription factors Ngn3 and Pax6, and may be one of the mechanisms that promote differentiation of iPSCs into islet β cells.