title: BCL-xL overexpression effectively protects against tetrafluoroethylcysteine-induced intramitochondrial damage and cell death.
abstract: S-(1,1,2,2-Tetrafluoroethyl)-L-cysteine (TFEC), a major metabolite of the industrial gas tetrafluoroethylene, has been shown to mediate nephrotoxicity by necrosis. TFEC-induced cell death is associated with an early covalent modification of specific intramitochondrial proteins; including aconitase, alpha-ketoglutarate dehydrogenase (KGDH) subunits, HSP60 and HSP70. Previous studies have indicated that the TAMH line accurately models TFEC-induced in vivo cell death with dose- and time-dependent inhibitions of both KGDH and aconitase activities. Here, we show that the molecular pathway leading to TFEC-mediated cell death is associated with an early cytosolic to mitochondrial translocation of BAX, a pro-apoptotic member of the BCL-2 family. Immunoblot analyses indicated movement of BAX (21 kDa) to the mitochondrial fraction after exposure to a cytotoxic concentration of TFEC (250 microM). Subsequent cytochrome c release from mitochondria was also demonstrated, but only a modest increase in caspase activities was observed, suggesting a degeneration of early apoptotic signals into secondary necrosis. Significantly, TAMH cells overexpressing BCL-xL preserved cell viability even to supratoxicological concentrations of TFEC (< or =600 microM), and this cytoprotection was associated with decreased HSP70i upregulation, indicating suppression of TFEC-induced proteotoxicity. Hence, TFEC-induced necrotic cell death in the TAMH cell line is mediated by BAX and antagonized by the anti-apoptotic BCL-2 family member, BCL-xL.
authors.affiliation: Department of Medicinal Chemistry, University of Washington, Box 357610, Seattle, WA 98195, USA. hankiat@u.washington.edu
authors.forename: Han K
authors.initials: HK
authors.lastname: Ho
authors.forename: Zhong-Hua
authors.initials: ZH
authors.lastname: Hu
authors.forename: Shie-Pon
authors.initials: SP
authors.lastname: Tzung
authors.forename: David M
authors.initials: DM
authors.lastname: Hockenbery
authors.forename: Nelson
authors.initials: N
authors.lastname: Fausto
authors.forename: Sidney D
authors.initials: SD
authors.lastname: Nelson
authors.forename: Sam A
authors.initials: SA
authors.lastname: Bruschi
mesh_terms: D016923:Cell Death / Q000187:drug effects / Q000235:genetics; D002460:Cell Line; D003545:Cysteine / Q000378:metabolism / Q000494:pharmacology; D005466:Fluorocarbons / Q000378:metabolism* / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology; D006801:Humans; D008928:Mitochondria / Q000187:drug effects* / Q000235:genetics; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis* / Q000502:physiology*; D051020:bcl-X Protein
chemical_list: C494811:BCL2L1 protein, human; D005466:Fluorocarbons; D019253:Proto-Oncogene Proteins c-bcl-2; D051020:bcl-X Protein; D003545:Cysteine; C015531:tetrafluoroethylene