Exocrine pancreatic zymogen activation

Yale University, New Haven CT

Investigators

Linked publications & trials

Abstract

DESCRIPTION (provided by applicant): Acute pancreatitis, an inflammatory disease of the pancreas, causes death in over 30% of those with severe disease. Specific therapies to prevent pancreatitis or reduce injury are lacking. The disease is thought to begin in the pancreatic acinar cell after exposure to insults that initiate pathologic changes in this cell's signaling. Subsequen pathologic acinar cell responses are followed by changes in blood flow, inflammation, and cell death. We propose to examine a previously undescribed mediator of intracellular signaling that modulates pancreatitis responses, AMP-regulated protein kinase (AMPK). The enzyme may be an attractive therapeutic target. Based on our preliminary findings and recent publication, we hypothesize that AMPK serves a protective role in pancreatitis within the acinar cell and does so by inhibiting key mediators of pancreatitis, including the vacuolar ATPase (vATPase). Further, its protective role appears to be reduced in the acinar cell during the early phases of pancreatiti when AMPK activity rapidly decreases in selective cellular compartments. In preliminary studies, the proposed protective role for AMPK was supported by findings in cellular and in vivo pancreatitis models which showed that: a) clinically used drugs that can activate AMPK reduce disease severity, b) genetically reducing AMPK using either siRNA in pancreatic acini (groups of 20-100 acinar cells) or a knockout mouse lacking the essential AMPK alpha-1 subunit, increases the severity of pancreatitis. Finally, preliminary studies indicate that human acinar cells contain AMPK and have an essential subunit isoform (beta-1) that is required for drug targeting. To examine the role of AMPK in pancreatitis, the following Specific Aims are planned: 1) Examine agents that activate AMPK in isolated pancreatic acini, 2) Examine agents that activate AMPK using in vivo models of pancreatitis, and 3) Determine the molecular and cellular targets of AMPK. Studies will be carried out with isolated groups of pancreatic acinar cells (acini) and in vivo pancreatitis models that produce mild and severe disease. Effects observed in isolated rodent acinar cells will be confirmed in a similar preparation of human acinar cells. Genetic knockdown of AMPK in acini has been performed and intact mice with deletions of AMPK's catalytic subunits are on hand and will be used to confirm AMPK's role in pancreatitis and to show that drugs found to reduce disease severity are acting through AMPK. The effects of AMPK activating drugs on AMPK translocation and downstream processes such as vATPase activation will be examined. We have identified AMPK activators that are currently available medications with safe profiles that also decrease the severity of acute pancreatitis in our models. Thus, the proposed studies have strong translational and therapeutic potential.