Cloning and expression of the rat vacuole membrane protein 1 (VMP1), a new gene activated in pancreas with acute pancreatitis, which promotes vacuole formation.

To characterize the emergency program set up by pancreatic cells in response to pancreatitis, we established the phenotype of the pancreatitis-affected pancreas by characterizing a large number of its transcripts. In this report, we describe the cloning, sequencing, and expression pattern of a new gene, named VMP1 (vacuole membrane protein 1). The VMP1 mRNA codes for a putative protein of 406 amino acids. In situ hybridization studies revealed that pancreatic expression of VMP1 mRNAs was restricted to the acinar cells. Interestingly, VMP1 mRNA was also overexpressed in kidney after transient ischemic injury. However, many healthy tissues express VMP1 mRNA. Structure analysis suggested that VMP1 is a transmembrane protein with six hydrophobic regions. VMP1/EGFP fusion protein was located to the Golgi apparatus and the endoplasmic reticulum area. Expression of this protein promoted the formation of intracytoplasmatic vacuoles and VMP1/EGFP was located to the membranes of these vacuoles. Cells overexpressing this protein died after 48 h. In conclusion, we have identified a new stress-induced gene which codes for a transmembrane protein that, when overexpressed, promotes formation of intracellular vacuoles followed by cell death.