Screening for novel pancreatic genes from in vitro-induced pancreas in Xenopus.

The processes of development and differentiation of the pancreas, an endoderm-derived vital organ that consists of both endocrine and exocrine cells, are highly conserved across most vertebrates. Recently, an in vitro system has been reported to induce embryonic pancreas using multipotent Xenopus ectodermal cells treated with activin and retinoic acid. In this study, this system was first modified to eliminate the mesoderm-derived pronephros. It was found that pronephros, which appeared with the use of low concentrations of activin, was eliminated at higher concentrations (400 ng/mL), while pancreas developed at a high frequency. Using this modified system, subtractive hybridization screening for novel pancreatic genes was done to better understand the molecular mechanisms of pancreas formation. Four novel genes were identified and characterized that were also found to be specifically expressed in the developing pancreas: carboxyl ester lipase, pancreatic elastase2, placental protein11 and protein disulfide isomerase A2 precursor. This in vitro pancreas-induction system may provide a useful model for analysis of the molecular mechanisms that function during pancreas development.