Pancreatic protease activation by alcohol metabolite depends on Ca2+ release via acid store IP3 receptors.
Toxic alcohol effects on pancreatic acinar cells, causing the often fatal human disease acute pancreatitis, are principally mediated by fatty acid ethyl esters (non-oxidative products of alcohol and fatty acids), emptying internal stores of Ca(2+). This excessive Ca(2+) liberation induces Ca(2+)-dependent necrosis due to intracellular trypsin activation. Our aim was to identify the specific source of the Ca(2+) release linked to the fatal intracellular protease activation. In 2-photon permeabilized mouse pancreatic acinar cells, we monitored changes in the Ca(2+) concentration in the thapsigargin-sensitive endoplasmic reticulum (ER) as well as in a bafilomycin-sensitive acid compartment, localized exclusively in the apical granular pole. We also assessed trypsin activity in the apical granular region. Palmitoleic acid ethyl ester (POAEE) elicited Ca(2+) release from both the ER as well as the acid pool, but trypsin activation depended predominantly on Ca(2+) release from the acid pool, that was mainly mediated by functional inositol 1,4,5- trisphosphate receptors (IP(3)Rs) of types 2 and 3. POAEE evoked very little Ca(2+) release and trypsin activation when IP(3)Rs of both types 2 and 3 were knocked out. Antibodies against IP(3)Rs of types 2 and 3, but not type 1, markedly inhibited POAEE-elicited Ca(2+) release and trypsin activation. We conclude that Ca(2+) release through IP(3)Rs of types 2 and 3 in the acid granular Ca(2+) store induces intracellular protease activation, and propose that this is a critical process in the initiation of alcohol-related acute pancreatitis.
Gerasimenko
Julia V
JV
Medical Research Council Group, Physiological Laboratory, School of Biomedical Sciences, University of Liverpool, Liverpool L69 3BX, United Kingdom.
Lur
György
G
Sherwood
Mark W
MW
Ebisui
Etsuko
E
Tepikin
Alexei V
AV
Mikoshiba
Katsuhiko
K
Gerasimenko
Oleg V
OV
Petersen
Ole H
OH
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D004986:Ether / Q000737:chemistry / Q000494:pharmacology*; D005229:Fatty Acids, Monounsaturated / Q000737:chemistry / Q000494:pharmacology*; D005260:Female; D005838:Genotype; D053496:Inositol 1,4,5-Trisphosphate Receptors / Q000235:genetics / Q000378:metabolism*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D010179:Pancreas / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D019837:Ryanodine Receptor Calcium Release Channel / Q000235:genetics / Q000378:metabolism; D014357:Trypsin / Q000378:metabolism*; D010738:Type C Phospholipases / Q000378:metabolism
D005229:Fatty Acids, Monounsaturated; D053496:Inositol 1,4,5-Trisphosphate Receptors; D019837:Ryanodine Receptor Calcium Release Channel; D004986:Ether; C008757:palmitoleic acid; D010738:Type C Phospholipases; D014357:Trypsin; D002118:Calcium