title: Acute acinar pancreatitis blocks vesicle-associated membrane protein 8 (VAMP8)-dependent secretion, resulting in intracellular trypsin accumulation.
abstract: Zymogen secretory granules in pancreatic acinar cells express two vesicle-associated membrane proteins (VAMP), VAMP2 and -8, each controlling 50% of stimulated secretion. Analysis of secretion kinetics identified a first phase (0-2 min) mediated by VAMP2 and second (2-10 min) and third phases (10-30 min) mediated by VAMP8. Induction of acinar pancreatitis by supramaximal cholecystokinin (CCK-8) stimulation inhibits VAMP8-mediated mid- and late-phase but not VAMP2-mediated early-phase secretion. Elevation of cAMP during supramaximal CCK-8 mitigates third-phase secretory inhibition and acinar damage caused by the accumulation of prematurely activated trypsin. VAMP8-/-acini are resistant to secretory inhibition by supramaximal CCK-8, and despite a 4.5-fold increase in total cellular trypsinogen levels, are fully protected from intracellular trypsin accumulation and acinar damage. VAMP8-mediated secretion is dependent on expression of the early endosomal proteins Rab5, D52, and EEA1. Supramaximal CCK-8 (60 min) caused a 60% reduction in the expression of D52 followed by Rab5 and EEA1 in isolated acini and inin vivoThe loss of D52 occurred as a consequence of its entry into autophagic vacuoles and was blocked by lysosomal cathepsin B and L inhibition. Accordingly, adenoviral overexpression of Rab5 or D52 enhanced secretion in response to supramaximal CCK-8 and prevented accumulation of activated trypsin. These data support that acute inhibition of VAMP8-mediated secretion during pancreatitis triggers intracellular trypsin accumulation and loss of the early endosomal compartment. Maintaining anterograde endosomal trafficking during pancreatitis maintains VAMP8-dependent secretion, thereby preventing accumulation of activated trypsin.
authors.affiliation: From the Department of Nutritional Sciences, University of Wisconsin, Madison, Wisconsin 53706.
authors.forename: Scott W
authors.initials: SW
authors.lastname: Messenger
authors.affiliation: From the Department of Nutritional Sciences, University of Wisconsin, Madison, Wisconsin 53706.
authors.forename: Elaina K
authors.initials: EK
authors.lastname: Jones
authors.affiliation: From the Department of Nutritional Sciences, University of Wisconsin, Madison, Wisconsin 53706.
authors.forename: Conner L
authors.initials: CL
authors.lastname: Holthaus
authors.affiliation: From the Department of Nutritional Sciences, University of Wisconsin, Madison, Wisconsin 53706.
authors.forename: Diana D H
authors.initials: DDH
authors.lastname: Thomas
authors.affiliation: From the Department of Nutritional Sciences, University of Wisconsin, Madison, Wisconsin 53706.
authors.forename: Michelle M
authors.initials: MM
authors.lastname: Cooley
authors.affiliation: Molecular Oncology Laboratory, Children's Cancer Research Unit, The Children's Hospital at Westmead, New South Wales 2145, Australia, and.
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Byrne
authors.affiliation: Department of Veterans Affairs Greater Los Angeles Healthcare System and UCLA, Los Angeles, California 90073.
authors.forename: Olga A
authors.initials: OA
authors.lastname: Mareninova
authors.affiliation: Department of Veterans Affairs Greater Los Angeles Healthcare System and UCLA, Los Angeles, California 90073.
authors.forename: Anna S
authors.initials: AS
authors.lastname: Gukovskaya
authors.affiliation: From the Department of Nutritional Sciences, University of Wisconsin, Madison, Wisconsin 53706, groby@nutrisci.wisc.edu.
authors.forename: Guy E
authors.initials: GE
authors.lastname: Groblewski
mesh_terms: D000818:Animals; D011992:Endosomes / Q000378:metabolism; D005260:Female; D007700:Kinetics; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D010179:Pancreas / Q000378:metabolism; D010195:Pancreatitis / Q000378:metabolism*; D050683:R-SNARE Proteins / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014357:Trypsin / Q000737:chemistry*; D014362:Trypsinogen / Q000737:chemistry; D033921:Vesicular Transport Proteins / Q000378:metabolism; D020696:rab5 GTP-Binding Proteins / Q000378:metabolism
chemical_list: D050683:R-SNARE Proteins; C584678:Tpd52 protein, rat; C491831:Vamp8 protein, mouse; C491830:Vamp8 protein, rat; D033921:Vesicular Transport Proteins; C093846:early endosome antigen 1; D014362:Trypsinogen; D014357:Trypsin; D020696:rab5 GTP-Binding Proteins
keywords: SNARE proteins; autophagy; endosome; pancreas; trypsin; trypsinogen