title: Activation of soluble adenylyl cyclase protects against secretagogue stimulated zymogen activation in rat pancreaic acinar cells.
abstract: An early feature of acute pancreatitis is activation of zymogens, such as trypsinogen, within the pancreatic acinar cell. Supraphysiologic concentrations of the hormone cholecystokinin (CCK; 100 nM), or its orthologue cerulein (CER), induce zymogen activation and elevate levels of cAMP in pancreatic acinar cells. The two classes of adenylyl cyclase, trans-membrane (tmAC) and soluble (sAC), are activated by distinct mechanisms, localize to specific subcellular domains, and can produce locally high concentrations of cAMP. We hypothesized that sAC activity might selectively modulate acinar cell zymogen activation. sAC was identified in acinar cells by PCR and immunoblot. It localized to the apical region of the cell under resting conditions and redistributed intracellularly after treatment with supraphysiologic concentrations of cerulein. In cerulein-treated cells, pre-incubation with a trans-membrane adenylyl cyclase inhibitor did not affect zymogen activation or amylase secretion. However, treatment with a sAC inhibitor (KH7), or inhibition of a downstream target of cAMP, protein kinase A (PKA), significantly enhanced secretagogue-stimulated zymogen activation and amylase secretion. Activation of sAC with bicarbonate significantly inhibited secretagogue-stimulated zymogen activation; this response was decreased by inhibition of sAC or PKA. Bicarbonate also enhanced secretagogue-stimulated cAMP accumulation; this effect was inhibited by KH7. Bicarbonate treatment reduced secretagogue-stimulated acinar cell vacuolization, an early marker of pancreatitis. These data suggest that activation of sAC in the pancreatic acinar cell has a protective effect and reduces the pathologic activation of proteases during pancreatitis.
authors: Section of Digestive Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, United States of America.
authors: Thomas R
authors: TR
authors: Kolodecik
authors: Christine A
authors: CA
authors: Shugrue
authors: Edwin C
authors: EC
authors: Thrower
authors: Lonny R
authors: LR
authors: Levin
authors: Jochen
authors: J
authors: Buck
authors: Fred S
authors: FS
authors: Gorelick
mesh_terms: D061354:Acinar Cells / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism*; D000262:Adenylyl Cyclases / Q000737:chemistry* / Q000378:metabolism*; D000681:Amylases / Q000378:metabolism; D000818:Animals; D001639:Bicarbonates / Q000494:pharmacology; D015415:Biomarkers / Q000378:metabolism; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002108:Ceruletide / Q000494:pharmacology; D002766:Cholecystokinin / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D004792:Enzyme Precursors / Q000737:chemistry* / Q000378:metabolism*; D008297:Male; D010179:Pancreas / Q000166:cytology*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D021381:Protein Transport / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D012995:Solubility
chemical_list: D001639:Bicarbonates; D015415:Biomarkers; D004792:Enzyme Precursors; D047428:Protein Kinase Inhibitors; D002108:Ceruletide; D002766:Cholecystokinin; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D000681:Amylases; D000262:Adenylyl Cyclases