EXPRESSION OF REG GENE IN THE SYRIAN GOLDEN-HAMSTER PANCREATIC-ISLET REGENERATION MODEL

We have reported previously that cellophane wrapping of the hamster pa ncreas is a stimulus that leads to the induction of duct epithelial ce ll proliferation, followed by endocrine cell differentiation and new i slet formation. Reg is a candidate gene that has been reported to be e xpressed in regenerating pancreatic islets, suggesting a role in islet growth. We examined Reg gene expression in the cellophane-wrap model by isolating total RNA from hamster pancreata at various times after w rapping. Northern blot analysis using a rat cDNA Reg probe showed no e xpression of Reg in control non-wrapped hamster pancreas, whereas a st rong signal was detected in control wrapped rat pancreas. Using revers e transcription of RNA followed by polymerase chain reaction (PCR) we amplified, isolated and sequenced a 194 base pair product which showed homology to rat Reg in both control and wrapped hamster pancreas. Whe n the PCR product was used as a probe for Northern blot analysis, no s ignal was detected in control non-wrapped pancreata. In contrast, a st rong signal was detected 1 and 2 days after wrapping, which then retur ned to basal between 4 and 6 days after wrapping. A similar temporal p attern was observed using in situ hybridization to localize the Reg ge ne. One- and 2-day wrapped but not control pancreas expressed Reg in a cinar cells, but not in islets. In conclusion, (a) Reg expression is l ow in the control hamster pancreas (b) in the cellophane-wrap model of islet neogenesis, increased Reg mRNA is found within acinar tissue; ( c) Reg gene may thus be involved as an acinar paracrine effector of du ct cell proliferation in the initial step of islet neogenesis, but may also participate in the inflammatory response to traumatic stimuli.