title: Evidence that cyclophilin-A protects cells against oxidative stress.
abstract: Cyclophilin-A is the cytosolic isoform of a family of peptidylproline cis-trans-isomerases that bind cyclosporin A. This study investigates the role of cyclophilin-A in necrotic cell death, induced by 'chemical ischaemia' and by t-butylhydroperoxide. An 18-mer antisense phosphorothioate oligodeoxynucleotide was used to target a translated region of cyclophilin-A mRNA in rat neonatal cardiomyocytes. After a 24 h exposure to the oligonucleotide, the amount of cyclophilin-A in the cells was decreased by at least 93% as judged by immunological and enzymic criteria. For the enzyme assays, peptidyl proline cis-trans-isomerase activity was measured fluorimetrically in small (10 microl) volumes of cell extract. Immunoblots were developed with a polyclonal anti-cyclophilin-A antibody after sample isoelectric focusing and SDS/PAGE. Cyclophilin-A suppression had no effect on cyanide-plus-2-deoxyglucose-induced cell death. However, cyclophilin-A-suppressed cells were markedly more sensitive to t-butylhydroperoxide. Cyclosporin A conferred some resistance to the peroxide in both types of cell, but protection was greater in cyclophilin-A-suppressed cells, where cyclosporin A increased the survival time 2-fold. It is concluded that two cyclophilin isoforms are involved, in quite different ways, in peroxide-induced cell death. Cyclophilin-A has a protective role. Another isoform, possibly mitochondrial cyclophilin-D, has a deleterious role, such that blockade by cyclosporin A leads to protection.
authors.affiliation: Department of Biochemistry and Molecular Biology, University College London, Gower Street, London WC1E 6BT, UK.
authors.forename: V
authors.initials: V
authors.lastname: Doyle
authors.forename: S
authors.initials: S
authors.lastname: Virji
authors.forename: M
authors.initials: M
authors.lastname: Crompton
mesh_terms: D000818:Animals; D016923:Cell Death / Q000187:drug effects; D002478:Cells, Cultured; D003486:Cyanides / Q000633:toxicity; D000081406:Peptidyl-Prolyl Isomerase F; D021983:Cyclophilins; D015870:Gene Expression / Q000187:drug effects; D006321:Heart / Q000187:drug effects*; D020104:Immunophilins / Q000187:drug effects; D009206:Myocardium / Q000166:cytology; D020319:Oligodeoxyribonucleotides, Antisense / Q000494:pharmacology; D018384:Oxidative Stress / Q000502:physiology*; D019696:Peptidylprolyl Isomerase / Q000187:drug effects* / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D020122:tert-Butylhydroperoxide / Q000633:toxicity
chemical_list: D003486:Cyanides; D000081406:Peptidyl-Prolyl Isomerase F; D020319:Oligodeoxyribonucleotides, Antisense; D020122:tert-Butylhydroperoxide; D021983:Cyclophilins; D020104:Immunophilins; D019696:Peptidylprolyl Isomerase