Targeting protein kinase D in alcoholic pancreatitis

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Project Summary/Abstract Alcohol abuse is a major cause of pancreatitis. Despite numerous studies, the mechanisms of ethanol effects in pancreatitis remain poorly understood and no current therapies directed to the molecular pathogenesis of this serious medical disorder are available. Our previous work demonstrated that ethanol-sensitized inflammatory and cell death responses are key steps for the development of pathologic responses in both acute and chronic pancreatitis. We further showed that ethanol augments the activation of the pro-inflammatory transcription factors and necrosis death pathways in pancreatic acinar cells. However the mechanisms or signal transduction pathways mediating the modulatory effects of ethanol on inflammatory and cell death pathways have not been completely revealed. PKD/PKD1, PKD2, and PKD3, comprising a family of novel serine/ threonine protein kinase D, have recently emerged as important components in the signaling pathways initiated and transduced through G protein coupled receptors, phospholipase C, second messengers, and PKC-dependent and –independent mechanisms in a variety of cell types including pancreatic acinar cells. PKD is increasingly implicated in the regulation of multiple cellular functions. Of significant importance for pancreatitis, our studies demonstrated that PKD signaling is required for key pathological features of rodent experimental pancreatitis including NF-κB activation, acinar cell necrosis and inappropriate intracellular digestive enzyme activation. The necessary role of PKD in pancreatitis has been further confirmed with our recently developed mouse model of pancreas specific deletion of PKD isoform. In our preliminary studies with a rodent model of ethanol-induced pancreatitis, we found that ethanol feeding promoted PKD expression and enhances cerulein-induced PKD activation that was closely linked to ethanol-sensitized NF-κB activation and cell necrosis. These results indicate that ethanol sensitizes pancreatitis responses through mechanisms involving PKD. Thus, we hypothesize that PKD is potentially a novel therapeutic target in alcoholic pancreatitis. Potent and specific PKD inhibitors will have benefit in treating this disease by attenuating both the inflammatory and necrosis responses in this disease. To test this hypothesis, we will further determine the role of alcohol-induced effects on PKD in regulating key signals involved in inflammation and then determine the role of alcohol-induced effects on PKD in regulating cell death through non-mitochondrial and mitochondrial signal pathways. Both pharmacological and genetic loss-of-function approaches including selective deletion of the PKD gene in mice will be utilized to explore PKD functions. We will test currently available small molecule inhibitors of PKD and determine their therapeutic benefits in experimental models of alcoholic pancreatitis in animals and human pancreatic acinar cells.