Pancreatitis is a potentially fatal disease with significant morbidity and mortality, the pathogenesis of which remains obscure and for which no specific or effective treatment exists. Our findings indicate that lysosomal function is defective in pancreatitis, leading to impaired autophagy and key pathologic responses of pancreatitis such as the accumulation of active trypsin and vacuoles in acinar cells. The mechanisms of lysosomal/autophagic dysfunction in pancreatitis are not known. Rab proteins are small GTPases the principal function of which is to oversee vectorial transport of proteins and membranes between organelles. They coordinate all aspects of the endo-lysosomal system, and also regulate autophagy. Rab9, in particular, regulates trafficking of mannose-6-phosphate receptors (M6PRs) that control the delivery of newly synthesized hydrolases to the lysosome. Rabs are synthesized as soluble proteins and then undergo lipidation (prenylation), which is mediated by Rab escort protein (REP) and is necessary for Rab delivery to membranes and subsequent activation. Neither the effect of pancreatitis on Rab GTPases nor their roles in the pathogenesis of this disease have been investigated. Our preliminary results indicate that acinar cell Rab functioning is disordered in pancreatitis due to their decreased delivery to membranes caused by a decrease in REP1. In this application, we propose a novel concept for the mechanism of pancreatitis, namely, that global Rab dysfunction is a critical pathogenic event initiating pancreatitis. We hypothesize the following chain of events: REP1 decrease causes deficient Rab prenylation, resulting in a decrease in membrane-bound Rabs. The decrease in membrane Rab9 leads to decreased M6PR levels and ultimately, to the lysosomal/autophagic dysfunction. Thus, Rab dysfunction underlies pancreatitis pathologies. The hypothesis will be tested in three Specific Aims: 1). Investigate Rab dysfunction in pancreatitis and the role of Rab prenylation as the underlying mechanism. 2). Determine the roles of Rab prenylation and Rab9-M6PR pathway in the lysosomal/autophagic dysfunction in pancreatitis. 3). Determine the role of Rab dysfunction in key pancreatitis responses: trypsinogen activation, inflammation and acinar cell death. The proposal will use genetically modified mouse models, human and mouse acinar cells, and various biochemical and cell biological techniques to examine the mechanisms of Rab dysfunction in pancreatitis. Elucidation of these mechanisms will lead to identification of novel molecular targets, such as REP1 and Rab9, for therapeutic interventions to restore lysosomal/autophagic function and thus prevent or ameliorate pancreatitis. Importantly, similar pathogenic mechanisms are likely to operate in other disease states as well.

Public Health Relevance

Project 1: Narrative Acute pancreatitis is a potentially fatal disease of the exocrine pancreas, the pathogenesis of which remains unknown and specific treatments for which have not been developed. Our recent studies reveal that pancreatitis causes profound disordering of autophagy, the key cellular mechanism for protein degradation, and of lysosomes, the organelles that execute autophagy. This proposal will use experimental and genetic pancreatitis models in mice and isolated pancreatic cells to determine the molecular mechanisms underlying this defect. We propose that pancreatitis causes global dysfunction of Rab GTPases, an important class of proteins which control trafficking between various cellular organelles;and further, that Rab dysfunction leads to key pathologic responses of pancreatitis such as inflammation and cell death. Insights gained from proposed studies will advance our understanding of the mechanism of pancreatitis and lead to novel molecular targets for treatment of this disease.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Program Projects (P01)
Project #
1P01DK098108-01A1
Application #
8743017
Study Section
Special Emphasis Panel (ZDK1)
Project Start
Project End
Budget Start
2014-09-01
Budget End
2015-06-30
Support Year
1
Fiscal Year
2014
Total Cost
Indirect Cost
Name
University of California Los Angeles
Department
Type
DUNS #
City
Los Angeles
State
CA
Country
United States
Zip Code
90095
Eibl, Guido; Cruz-Monserrate, Zobeida; Korc, Murray et al. (2018) Diabetes Mellitus and Obesity as Risk Factors for Pancreatic Cancer. J Acad Nutr Diet 118:555-567
Zheng, Han; You, Yang; Hua, Meiyun et al. (2018) Chlorophyllin Modulates Gut Microbiota and Inhibits Intestinal Inflammation to Ameliorate Hepatic Fibrosis in Mice. Front Physiol 9:1671
Lew, Daniel; Wu, Bechien U; Pandol, Stephen J et al. (2018) Disease Course Differences in Acute Pancreatitis Based on Etiology Using the Pancreatitis Activity Scoring System. Pancreas 47:e40-e41
Waldron, Richard T; Su, Hsin-Yuan; Piplani, Honit et al. (2018) Ethanol Induced Disordering of Pancreatic Acinar Cell Endoplasmic Reticulum: An ER Stress/Defective Unfolded Protein Response Model. Cell Mol Gastroenterol Hepatol 5:479-497
Waldron, Richard T; Lugea, Aurelia; Gulla, Aiste et al. (2018) Proteomic Identification of Novel Plasma Biomarkers and Pathobiologic Pathways in Alcoholic Acute Pancreatitis. Front Physiol 9:1215
Buxbaum, James; Quezada, Michael; Chong, Bradford et al. (2018) The Pancreatitis Activity Scoring System predicts clinical outcomes in acute pancreatitis: findings from a prospective cohort study. Am J Gastroenterol 113:755-764
Zhao, Qinglan; Wei, Yi; Pandol, Stephen J et al. (2018) STING Signaling Promotes Inflammation in Experimental Acute Pancreatitis. Gastroenterology 154:1822-1835.e2
Biczo, Gyorgy; Vegh, Eszter T; Shalbueva, Natalia et al. (2018) Mitochondrial Dysfunction, Through Impaired Autophagy, Leads to Endoplasmic Reticulum Stress, Deregulated Lipid Metabolism, and Pancreatitis in Animal Models. Gastroenterology 154:689-703
Todoric, Jelena; Antonucci, Laura; Di Caro, Giuseppe et al. (2017) Stress-Activated NRF2-MDM2 Cascade Controls Neoplastic Progression in Pancreas. Cancer Cell 32:824-839.e8
Lugea, Aurelia; Gerloff, Andreas; Su, Hsin-Yuan et al. (2017) The Combination of Alcohol and Cigarette Smoke Induces Endoplasmic Reticulum Stress and Cell Death in Pancreatic Acinar Cells. Gastroenterology 153:1674-1686

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