Caerulein-induced intracellular pancreatic zymogen activation is dependent on calcineurin.
Aberrant cytosolic Ca(2+) flux in pancreatic acinar cells is critical to the pathological pancreatic zymogen activation observed in acute pancreatitis, but the downstream effectors are not known. In this study, we examined the role of Ca(2+)-activated protein phosphatase 2B (or calcineurin) in zymogen activation. Isolated pancreatic acinar cells were stimulated with supraphysiological caerulein (100 nM) with or without the calcineurin inhibitors FK506 or cell-permeable calcineurin inhibitory peptide (CiP). Chymotrypsin activity was measured as a marker of zymogen activation, and the percent amylase secretion was used as a measure of enzyme secretion. Cytosolic Ca(2+) changes were recorded in acinar cells loaded with the intermediate Ca(2+)-affinity dye fluo-5F using a scanning confocal microscope. A 50% reduction in chymotrypsin activity was observed after pretreatment with 1 microM FK506 or 10 microM CiP. These pretreatments did not affect amylase secretion or the rise in cytosolic Ca(2+) after caerulein stimulation. These findings suggest that calcineurin mediates caerulein-induced intra-acinar zymogen activation but not enzyme secretion or the initial caerulein-induced cytosolic Ca(2+) signal.
Husain
Sohail Z
SZ
Dept. of Pediatrics, 333 Cedar St., FMP408, PO Box 208064, New Haven, CT 06520, USA. sohail.husain@yale.edu
Grant
Wayne M
WM
Gorelick
Fred S
FS
Nathanson
Michael H
MH
Shah
Ahsan U
AU
D000681:Amylases / Q000378:metabolism*; D000818:Animals; D019703:Calcineurin / Q000378:metabolism*; D065095:Calcineurin Inhibitors; D020013:Calcium Signaling / Q000187:drug effects*; D002478:Cells, Cultured; D002108:Ceruletide / Q000494:pharmacology*; D002614:Chelating Agents / Q000494:pharmacology; D002918:Chymotrypsin / Q000378:metabolism*; D002919:Chymotrypsinogen / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D008297:Male; D019319:Okadaic Acid / Q000494:pharmacology; D046790:Pancreas, Exocrine / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D010455:Peptides / Q000494:pharmacology; D010749:Phosphoprotein Phosphatases / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D020123:Sirolimus / Q000494:pharmacology; D016559:Tacrolimus / Q000494:pharmacology; D022021:Tacrolimus Binding Proteins / Q000378:metabolism
D065095:Calcineurin Inhibitors; D002614:Chelating Agents; D004791:Enzyme Inhibitors; D010455:Peptides; C070379:1,2-bis(2-aminophenoxy)ethane N,N,N',N'-tetraacetic acid acetoxymethyl ester; D019319:Okadaic Acid; D004533:Egtazic Acid; D002108:Ceruletide; D002919:Chymotrypsinogen; D019703:Calcineurin; D010749:Phosphoprotein Phosphatases; D000681:Amylases; D002918:Chymotrypsin; D022021:Tacrolimus Binding Proteins; D020123:Sirolimus; D016559:Tacrolimus