PDX-1 and Msx-2 expression in the regenerating and developing pancreas

We have observed pancreatic duct cell proliferation and islet regeneration in transgenic mice whose pancreata produce interferon gamma (IFNg mice). We have previously demonstrated that new islet cells derive from endocrine pr ogenitor cells in the pancreatic ducts of this model. The current study was initiated to define these endocrine progenitor cells further and to identi fy novel markers associated with pancreatic regeneration. Importantly, we h ave found that PDX-1, a transcription factor required for insulin gene tran scription as well as for pancreatic development during embryogenesis, is ex pressed in the duct cells of IFNg mice. This striking observation suggests an important role for PDX-1 in the marked regeneration observed in IFNg mic e, paralleling its critical function during ontogeny. Also demonstrated was elevated expression of the homeobox-containing protein Msx-2 in the pancre ata of fetal mice as well as in adult IFNg mice, identifying this molecule as a novel marker associated with pancreatic development and regeneration a s well. The identification of PDX-1 and Msx in the ducts of the IFNg transg enic pancreas but not in the ducts of the nontransgenic pancreas suggests t hat these molecules are associated with endocrine precursor cells in the du cts of the IFNg transgenic mouse.