ARIP cells as a model for pancreatic beta cell growth and development

Pancreatic ductal epithelium contains the pluripotent cells that develop into pancreatic beta cells. However, little is known about intrinsic or extrinsic factors that enable this differentiation to occur. PDX-1 plays a critical role in pancreatic development and insulin secretion. Therefore we transfected the PDX-1 gene into ARIP cells, a rat pancreatic ductal cell line. The ARIP and ARIP/PDX-1 cells were treated with known growth and differentiation factors including hepatocyte growth factor, activin A, betacellulin, reg, INGAP, nicotinamide, and retinoic acid. Despite the ductal origin of these cells, no changes in expression of 24 pancreatic genes, as determined by semiquantitative reverse transcription-polymerase chain reaction (RT-PCR), occurred in either cell line. Western blot analysis confirmed the presence of the active phosphorylated form of the PDX-1 protein. To enhance PDX-1 phosphorylation, we cultured ARIP and ARIP/PDX-1 cells in a high-glucose medium; however, as with the other conditions, no differences in mRNA expression were noted on the RT-PCR assay. We conclude that other factors may be necessary for beta cell differentiation and/or that ARIP cells are a poor model of pancreatic development.