Overexpression of the reg gene in non-obese diabetic mouse pancreas during active diabetogenesis is restricted to exocrine tissue.

We demonstrated pancreatic reg gene overexpression in non-obese diabetic (NOD) mice during active diabetogenesis. The aim of this study was to determine in which part of the pancreas (endocrine and/or exocrine) the gene(s) and the protein(s) were expressed and if their localization changed with progression of the disease. In situ hybridization analysis and immunocytochemical studies were carried out on pancreas of female and male NOD mice. Both develop insulitis but diabetes develops only in females and in males only when treated by cyclophosphamide. Our results show that whatever the age, sex, and presence of insulitis and/or diabetes, the expression of reg mRNAs and of the corresponding protein(s) was restricted to exocrine tissue. Moreover, reg remains localized in acinar cells in the two opposite situations of (a) cyclophosphamide-treated males in a prediabetic stage presenting a high level of both insulin and reg mRNAs, and (b) the overtly diabetic females with no insulin but a high level of reg mRNA. These findings suggest that overexpression of the reg gene(s) might represent a defense of the acinar cell against pancreatic aggression.