title: Enhancement of cyanide-induced mitochondrial dysfunction and cortical cell necrosis by uncoupling protein-2.
abstract: Uncoupling protein 2 (UCP-2) is expressed in the inner mitochondrial membrane and modulates mitochondrial function by partially uncoupling oxidative phosphorylation, and it has been reported to modulate cell death. Cyanide is a potent neurotoxin that inhibits complex IV to alter mitochondrial function to induce neuronal death. In primary rat cortical cells KCN produced an apoptotic death at 200-400 microM. Higher concentrations of potassium cyanide (KCN) (500-600 microM) switched the mode of death from apoptosis to necrosis. In necrotic cells, ATP levels were severely depleted as compared to cortical cells undergoing apoptosis. To determine if UCP-2 expression could alter KCN-induced cell death, cells were transiently transfected with full-length human UCP-2 cDNA (UCP-2+). Overexpression switched the mode of death produced by KCN (400 microM) from apoptosis to necrosis. The change in cell death was mediated by impaired mitochondrial function as reflected by a marked decrease of ATP levels and reduction in mitochondrial membrane potential. RNA interference or transfection with a dominant interfering mutant blocked the necrotic response observed in UCP-2+ cells. Additionally, treatment of UCP-2+ cells with cyclosporin A blocked necrosis, indicating the involvement of mitochondrial permeability pore transition in the necrotic death. These results show that increased expression of UCP-2 alters the response to a potent mitochondrial toxin by switching the mode of cell death from apoptosis to necrosis. It is concluded that UCP-2 levels influence cellular responses to cyanide-induced mitochondrial dysfunction.
authors.affiliation: Department of Medicinal Chemistry & Molecular Pharmacology, Purdue University, West Lafayette, Indiana 47907-1333, USA.
authors.forename: L
authors.initials: L
authors.lastname: Li
authors.forename: K
authors.initials: K
authors.lastname: Prabhakaran
authors.forename: E M
authors.initials: EM
authors.lastname: Mills
authors.forename: J L
authors.initials: JL
authors.lastname: Borowitz
authors.forename: G E
authors.initials: GE
authors.lastname: Isom
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology / Q000187:drug effects; D003486:Cyanides / Q000633:toxicity*; D008928:Mitochondria / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D003486:Cyanides