Rat pancreas with acute pancreatitis activates the expression of a new gene which promotes vacuole formation.

VACCARO MI; DUSETTI NJ; CALVO EL; ROPOLO A; GRASSO D; YONGFENG J; FIEDLER F; DAGORN JC; IOVANNA JL

Chicago, IL, USA.

Congreso; Joint Meeting of the American Pancreatic Association and the International Association of Pancreatology; 2000

American Pancreatic Association and International Association of Pancreatology

During the acute phase of pancreatitis, expression of the genes encoding pancreatic secretory enzymes, which are potentially harmful, are generally reduced, as part of a defense mechanism. Conversely, other genes are strongly activated. The aim of our research is to characterize at the molecular level the pancreatic emergency program set up in response to pancreatitis. In this report, we describe the cloning, sequencing, and expression pattern of a new gene, named VMP1 (Vacuole Membrane Protein 1). Sequence analysis of the VMP1 cDNA revealed a single open reading frame coding for a putative protein of 406 aminoacids. Although we failed to identify VMP1-related sequences, analysis of its structure suggested that VMP1 is a transmembrane protein with 6 hydrophobic regions. The VMP1 gene generated two major transcripts of 1.9 and 3.5 kb, both strongly induced in the inflamed pancreas. In situ hybridization studies revealed that pancreatic expression of VMP1 mRNAs was restricted to the acinar cells. Langerhans islet and ducts showed no signal of the transcript. Interestingly, VMP1 mRNA was also overexpressed in kidney and brain after transient ischemic injury. However, some healthy tissues expressed VMP1 mRNA. To identify the intracellular targets of this protein, we constructed a tetracycline-inducible plasmid encoding the VMP1/EGFP was localized into the membrane of the endoplasmic reticulum. Overexpression of this protein promoted the formation of intracytoplasmatic vacuoles in all 12 cell lines studies. VMP1/EGFP was localized in the membrane of these vacuoles. In conclusion, we have identified a new stress-activated transmembrane protein which is strongly induced during the acute phase of pancreatitis and promotes formation of intracellular vacuoles.