CREB Mediates Gq-Coupled Receptor Activation of Vmp1, a Switch for Autophagy in Pancreas Biology and Diseases

ROPOLO, A; LO RE, A; MOLEJON MI; BOGGIO, V; VACCARO, MI

Congreso; 43rd Meeting of the American Pancreatic Association and the 17th Meeting of the International Association of Pancreatology; 2012

Autophagy is an evolutionarily preserved degradation process of cytoplasmic cellular constituents, which participates in cell homeostasis as well as in response to disease. Our laboratory characterized VMP1 (Vacuole Membrane Protein 1) as an essential autophagy related-protein that mediates zymophagy,the selective degradation of altered secretory granules in acute pancreatitis.The aim of this work is to understand the regulatory pathways that control vmp1 gene expression and autophagy in pancreatic cells. Using a combination of luciferase assay, expression analysis, shRNA strategy and chromatin immunoprecipitation assay, we report the identification of the promoter region of the human vmp1 gene and the molecular pathways that lead to its activation. Here, we present the essential sequence required for this activation containing the TATA Box and several consensus binding sites for the transcription factors related to cellular stress. We show that Vmp1 promoter is activated by the hyperstimulation of Gq-coupled receptors using cerulein in AR42J cells. Besides, the transfection of these cells with a Gq constitutively activates protein induces VMP1 expression and activates the Vmp1 promoter.CREB, an effector of this axis, regulates the expression and promoter activity of VMP1 and chromatin immunoprecipitation assays demonstrated that CREB binds to VMP1 promoter. Moreover, we showed that the histone acetyltransferase p300 cooperates with CREB in VMP1 promoter regulation. Conversely, RNAi knockdown of p300 impairs CREB induced activation of this promoter.We demonstrate a transcriptional target of the Gq-coupled receptor signaling axis in pancreatic acinar cells. Together these data provide evidence of a new regulatory mechanism modulating autophagy and positions VMP1 as a switch for autophagy in pancreas biology and diseases.