Analysis of the transcription factor cascade that induces endocrine and exocrine cell lineages from pancreatic progenitor cells using a polyoma‐based episomal vector system

Aims/Introduction: We recently established a strategy for isolating multipotential duct‐like cells, called pdx‐1‐positive pancreatic cell‐derived (PPPD) cells, from the pancreas. To analyze the molecular mechanisms of pancreatic cell differentiation, we introduced a polyoma‐based episomal vector system into PPPD cells. Materials and Methods: PPPD cells were stably transfected with a polyoma large T (PLT)‐expressing plasmid vector, which included the polyoma origin of replication, to generate PLT‐PPPD cells. Various cDNA for pancreas‐related transcription factors were subcloned into the expression plasmid pPyCAG, which included the polyoma origin of replication. PLT‐PPPD cells were stably transfected with the resulting plasmid vectors and then subjected to gene and protein expression analyses. Results: The coexpression of Mafa, Neurod1 and Ipf1 induced Ins1 and Ins2 expression in PLT‐PPPD cells. The forced expression of Pax6 alone induced the expression of glucagon. The coexpression of Neurod1 and Isl1 induced Ins2 and Sst expression. In contrast, the expression of Ptf1a and Foxa2 induced the expression of exocrine markers Cpa1 and Amy2. Transfections with multiple transcription factors showed that Isl1 is required for the differentiation of both insulin‐positive cells and somatostatin‐positive cells. In addition, Foxa2 induced the differentiation of glucagon‐positive cells and inhibited the differentiation of insulin‐positive and somatostatin‐positive cells. PLT‐PPPD cells allow episomal vector‐based gene expression and should be useful for studying the transcription factor cascades involved in the differentiation of pancreatic cell types in vitro. Conclusions: Our coexpression study showed novel critical roles for Isl1 and Foxa2 in the differentiation of PPPD cells into endocrine cells. (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2011.00136.x, 2012)