Expression of SMAD signal transduction molecules in the pancreas

Members of the TGF-beta superfamily of cytokines have been implicated in pa ncreatic cancer, pancreatitis and in regulation and differentiation of panc reatic endocrine and exocrine cells. Different TGF-beta members signal thro ugh phosphorylation of different signal transduction proteins, which eventu ally form oligomers with SMAD 4 and translocate to the nucleus. Reverse tra nscriptase-polymerase chain reaction showed that SMADs 1, 2 and 4 are expre ssed in pancreatic islets. Immunostaining revealed that SMAD 1 and 4 predom inantly were expressed by islet insulin and glucagon cells. Since SMAD 1 is known to transduce signals from receptors binding bone morphogenetic prote in (BMP) these results indicate a previously unknown role of BMP-like ligan ds in islet function.