Cyclophilin-A is involved in excitotoxin-induced caspase activation in rat neuronal B50 cells.
Glutamate and the NO donor, nitroprusside, synergistically induced the death of B50 cells from a rat CNS-derived neuroblastoma cell line. With low [nitroprusside] (10 microM) both nitroprusside and glutamate were required. Under these conditions, nuclei became pyknotic and caspases were activated. The activities of caspase-3 and caspase-6 (effector caspases) were higher than those of caspase-8 and caspase-9 (initiator caspases). The activation of all four caspases was inhibited by cyclosporin A, with the order of susceptibility caspase-8=caspase-9=caspase-6>caspase-3. To identify the possible locus of cyclosporin A action, we used an antisense oligodeoxynucleotide to suppress the level of cyclophilin-A to<5% of its control value. Cyclophilin-A suppression largely reproduced the inhibitory effects of cyclosporin A. These results provide the first indication that cyclophilin-A participates in the activation of the caspase cascade in neuronal cells, in particular in the form of cascade elicited by excitotoxic stimuli. It is concluded that neuroprotection by cyclosporin A against excitotoxin-induced apoptosis is, at least partly, due to inhibition of cyclophilin-A.
Capano
Michela
M
Department of Biochemistry and Molecular Biology, University College London, Gower Street, London WC1E 6BT, UK.
Virji
Sukaina
S
Crompton
Martin
M
D000818:Animals; D017209:Apoptosis; D053148:Caspase 3; D053178:Caspase 6; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism*; D016923:Cell Death; D002467:Cell Nucleus / Q000378:metabolism; D021984:Cyclophilin A / Q000378:metabolism* / Q000502:physiology*; D016572:Cyclosporine / Q000494:pharmacology; D053938:DNA Fragmentation; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016166:Free Radical Scavengers / Q000494:pharmacology; D005971:Glutamates / Q000494:pharmacology; D009474:Neurons / Q000378:metabolism*; D009498:Neurotoxins / Q000378:metabolism*; D009569:Nitric Oxide / Q000494:pharmacology; D009599:Nitroprusside / Q000494:pharmacology; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D018384:Oxidative Stress; D020033:Protein Isoforms; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D019311:Staurosporine / Q000494:pharmacology; D013997:Time Factors
D004791:Enzyme Inhibitors; D016166:Free Radical Scavengers; D005971:Glutamates; D009498:Neurotoxins; D016376:Oligonucleotides, Antisense; D020033:Protein Isoforms; D012333:RNA, Messenger; D009599:Nitroprusside; D009569:Nitric Oxide; D016572:Cyclosporine; C505410:Casp3 protein, rat; C505518:Casp6 protein, rat; C505528:Casp8 protein, rat; C506435:Casp9 protein, rat; D053148:Caspase 3; D053178:Caspase 6; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases; D021984:Cyclophilin A; D019311:Staurosporine