title: Inhibitors of Bcl-2 protein family deplete ER Ca2+ stores in pancreatic acinar cells.
abstract: Physiological stimulation of pancreatic acinar cells by cholecystokinin and acetylcholine activate a spatial-temporal pattern of cytosolic [Ca(+2)] changes that are regulated by a coordinated response of inositol 1,4,5-trisphosphate receptors (IP(3)Rs), ryanodine receptors (RyRs) and calcium-induced calcium release (CICR). For the present study, we designed experiments to determine the potential role of Bcl-2 proteins in these patterns of cytosolic [Ca(+2)] responses. We used small molecule inhibitors that disrupt the interactions between prosurvival Bcl-2 proteins (i.e. Bcl-2 and Bcl-xl) and proapoptotic Bcl-2 proteins (i.e. Bax) and fluorescence microfluorimetry techniques to measure both cytosolic [Ca(+2)] and endoplasmic reticulum [Ca(+2)]. We found that the inhibitors of Bcl-2 protein interactions caused a slow and complete release of intracellular agonist-sensitive stores of calcium. The release was attenuated by inhibitors of IP(3)Rs and RyRs and substantially reduced by strong [Ca(2+)] buffering. Inhibition of IP(3)Rs and RyRs also dramatically reduced activation of apoptosis by BH3I-2'. CICR induced by different doses of BH3I-2' in Bcl-2 overexpressing cells was markedly decreased compared with control. The results suggest that Bcl-2 proteins regulate calcium release from the intracellular stores and suggest that the spatial-temporal patterns of agonist-stimulated cytosolic [Ca(+2)] changes are regulated by differential cellular distribution of interacting pairs of prosurvival and proapoptotic Bcl-2 proteins.
authors.affiliation: The Physiological Laboratory, University of Liverpool, Liverpool, L69 3BX, UK.
authors.forename: Julia
authors.initials: J
authors.lastname: Gerasimenko
authors.forename: Pawel
authors.initials: P
authors.lastname: Ferdek
authors.forename: Lars
authors.initials: L
authors.lastname: Fischer
authors.forename: Anna S
authors.initials: AS
authors.lastname: Gukovskaya
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Pandol
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001549:Benzamides / Q000494:pharmacology; D001578:Benzopyrans / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D045744:Cell Line, Tumor; D004721:Endoplasmic Reticulum / Q000378:metabolism; D053496:Inositol 1,4,5-Trisphosphate Receptors / Q000037:antagonists & inhibitors / Q000502:physiology; D008297:Male; D051379:Mice; D009570:Nitriles / Q000494:pharmacology; D046790:Pancreas, Exocrine / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000037:antagonists & inhibitors*; D051381:Rats; D019837:Ryanodine Receptor Calcium Release Channel / Q000187:drug effects / Q000378:metabolism; D051028:bcl-2-Associated X Protein / Q000378:metabolism; D051020:bcl-X Protein / Q000037:antagonists & inhibitors
chemical_list: C474172:3-iodo-5-chloro-N-(2-chloro-5-((4-chlorophenyl)sulphonyl)phenyl)-2-hydroxybenzamide; C494812:Bcl2l1 protein, mouse; D001549:Benzamides; D001578:Benzopyrans; D053496:Inositol 1,4,5-Trisphosphate Receptors; D009570:Nitriles; D019253:Proto-Oncogene Proteins c-bcl-2; D019837:Ryanodine Receptor Calcium Release Channel; D051028:bcl-2-Associated X Protein; D051020:bcl-X Protein; C456800:ethyl 2-amino-6-bromo-4-(1-cyano-2-ethoxy-2-oxoethyl)-4H-chromene-3-carboxylate; D002118:Calcium