title: Cobalt induces oxidative stress in isolated liver mitochondria responsible for permeability transition and intrinsic apoptosis in hepatocyte primary cultures.
abstract: It is well established that cobalt mediates the occurrence of oxidative stress which contributes to cell toxicity and death. However, the mechanisms of these effects are not fully understood. This investigation aimed at establishing if cobalt acts as an inducer of mitochondrial-mediated apoptosis and at clarifying the mechanism of this process. Cobalt, in the ionized species Co(2+), is able to induce the phenomenon of mitochondrial permeability transition (MPT) in rat liver mitochondria (RLM) with the opening of the transition pore. In fact, Co(2+) induces mitochondrial swelling, which is prevented by cyclosporin A and other typical MPT inhibitors such as Ca(2+) transport inhibitors and bongkrekic acid, as well as anti-oxidant agents. In parallel with mitochondrial swelling, Co(2+) also induces the collapse of electrical membrane potential. However in this case, cyclosporine A and the other MPT inhibitors (except ruthenium red and EGTA) only partially prevent DeltaPsi drop, suggesting that Co(2+) also has a proton leakage effect on the inner mitochondrial membrane. MPT induction is due to oxidative stress, as a result of generation by Co(2+) of the highly damaging hydroxyl radical, with the oxidation of sulfhydryl groups, glutathione and pyridine nucleotides. Co(2+) also induces the release of the pro-apoptotic factors, cytochrome c and AIF. Incubation of rat hepatocyte primary cultures with Co(2+) results in apoptosis induction with caspase activation and increased level of expression of HIF-1alpha. All these observations allow us to state that, in the presence of calcium, Co(2+) is an inducer of apoptosis triggered by mitochondrial oxidative stress.
authors: Dipartimento di Chimica Biologica, Università degli Studi di Padova, Istituto di Neuroscienze del CNR, Padova, Italy.
authors: Valentina
authors: V
authors: Battaglia
authors: Alessandra
authors: A
authors: Compagnone
authors: Andrea
authors: A
authors: Bandino
authors: Marcantonio
authors: M
authors: Bragadin
authors: Carlo Alberto
authors: CA
authors: Rossi
authors: Filippo
authors: F
authors: Zanetti
authors: Sebastiano
authors: S
authors: Colombatto
authors: Maria Angelica
authors: MA
authors: Grillo
authors: Antonio
authors: A
authors: Toninello
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology; D051033:Apoptosis Inducing Factor / Q000235:genetics / Q000378:metabolism; D053148:Caspase 3 / Q000235:genetics / Q000378:metabolism; D002458:Cell Fractionation; D002478:Cells, Cultured; D003035:Cobalt / Q000032:analysis / Q000633:toxicity*; D045304:Cytochromes c / Q000032:analysis; D022781:Hepatocytes / Q000502:physiology* / Q000648:ultrastructure; D006861:Hydrogen Peroxide / Q000032:analysis; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics / Q000378:metabolism; D007425:Intracellular Membranes; D008297:Male; D053078:Membrane Potential, Mitochondrial; D008930:Mitochondria, Liver / Q000737:chemistry / Q000502:physiology*; D018384:Oxidative Stress / Q000502:physiology*; D010539:Permeability; D051381:Rats; D017208:Rats, Wistar
chemical_list: D051033:Apoptosis Inducing Factor; C497444:Hif1a protein, rat; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D003035:Cobalt; D045304:Cytochromes c; D006861:Hydrogen Peroxide; D053148:Caspase 3