title: Differential effect of calmodulin antagonists on MG132-induced mitochondrial dysfunction and cell death in PC12 cells.
abstract: Defects in proteasome function have been suggested to be involved in the pathogenesis of neurodegenerative diseases. We examined the effect of calmodulin antagonists on proteasome inhibitor-induced mitochondrial dysfunction and cell viability loss in undifferentiated PC12 cells. Caspase inhibitors (z-IETD.fmk, z-LEHD.fmk and z-DQMD.fmk) and antioxidants attenuated cell death and decrease in GSH contents in PC12 cells treated with 20 microM MG132, a proteasome inhibitor. Calmodulin antagonists (trifluoperazine, W-7 and calmidazolium) had a differential inhibitory effect on the MG132-induced cell death and GSH depletion depending on concentration with a maximal inhibitory effect at 0.5-1 microM. Addition of trifluoperazine and W-7 reduced the MG132-induced nuclear damage, loss of the mitochondrial transmembrane potential followed by cytochrome c release, formation of reactive oxygen species and elevation of intracellular Ca(2+) levels in PC12 cells. Calmodulin antagonists at 5 microM exhibited a cytotoxic effect on PC12 cells but attenuated the cytotoxicity of MG132. The results suggest that the toxicity of MG132 on PC12 cells is mediated by activation of caspase-8, -9 and -3. Trifluoperazine and W-7 at the concentrations of 0.5-1 microM may attenuate the MG132-induced viability loss in PC12 cells by suppressing change in the mitochondrial membrane permeability and by lowering of the intracellular Ca(2+) levels as well as calmodulin inhibition.
authors.affiliation: Department of Pharmacology, College of Medicine, Chung-Ang University, Dong-jak Gu, Seoul 156-756, South Korea. leecs@cau.ac.kr
authors.forename: Chung Soo
authors.initials: CS
authors.lastname: Lee
authors.forename: Eun Sook
authors.initials: ES
authors.lastname: Han
authors.forename: Young Su
authors.initials: YS
authors.lastname: Han
authors.forename: Hyoweon
authors.initials: H
authors.lastname: Bang
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D002147:Calmodulin / Q000819:agonists*; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002452:Cell Count / Q000379:methods; D016923:Cell Death / Q000187:drug effects; D048429:Cell Size / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D045304:Cytochromes c / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005978:Glutathione / Q000378:metabolism; D007093:Imidazoles / Q000494:pharmacology*; D007976:Leupeptins; D028361:Mitochondrial Diseases / Q000139:chemically induced / Q000517:prevention & control*; D016716:PC12 Cells; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism; D013449:Sulfonamides / Q000494:pharmacology; D014268:Trifluoperazine / Q000494:pharmacology
chemical_list: D002147:Calmodulin; D004791:Enzyme Inhibitors; D007093:Imidazoles; D007976:Leupeptins; D017382:Reactive Oxygen Species; D013449:Sulfonamides; D014268:Trifluoperazine; C031938:calmidazolium; C017967:W 7; D045304:Cytochromes c; C505410:Casp3 protein, rat; D053148:Caspase 3; D020169:Caspases; D005978:Glutathione; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde; D002118:Calcium