title: DPI induces mitochondrial superoxide-mediated apoptosis.
abstract: The iodonium compounds diphenyleneiodonium (DPI) and diphenyliodonium (IDP) are well-known phagocyte NAD(P)H oxidase inhibitors. However, it has been shown that at high concentrations they can inhibit the mitochondrial respiratory chain as well. Since inhibition of the mitochondrial respiratory chain has been shown to induce superoxide production and apoptosis, we investigated the effect of iodonium compounds on mitochondria-derived superoxide and apoptosis. Mitochondrial superoxide production was measured on both cultured cells and isolated rat-heart submitochondrial particles. Mitochondria function was examined by monitoring mitochondrial membrane potential. Apoptotic pathways were studied by measuring cytochrome c release and caspase 3 activation. Apoptosis was characterized by detecting DNA fragmentation on agarose gel and measuring propidium iodide- (PI-) stained subdiploid cells using flow cytometry. Our results showed that DPI could induce mitochondrial superoxide production. The same concentration of DPI induced apoptosis by decreasing mitochondrial membrane potential and releasing cytochrome c. Addition of antioxidants or overexpression of MnSOD significantly reduced DPI-induced mitochondrial damage, cytochrome c release, caspase activation, and apoptosis. These observations suggest that DPI can induce apoptosis via induction of mitochondrial superoxide. DPI-induced mitochondrial superoxide production may prove to be a useful model to study the signaling pathways of mitochondrial superoxide.
authors.affiliation: Purdue University, Department of Basic Medical Sciences, West Lafayette, IN 47907, USA.
authors.forename: Nianyu
authors.initials: N
authors.lastname: Li
authors.forename: Kathy
authors.initials: K
authors.lastname: Ragheb
authors.forename: Gretchen
authors.initials: G
authors.lastname: Lawler
authors.forename: Jennie
authors.initials: J
authors.lastname: Sturgis
authors.forename: Bartek
authors.initials: B
authors.lastname: Rajwa
authors.forename: J Andres
authors.initials: JA
authors.lastname: Melendez
authors.forename: J Paul
authors.initials: JP
authors.lastname: Robinson
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D003574:Cytochrome c Group / Q000378:metabolism; D053938:DNA Fragmentation; D004789:Enzyme Activation / Q000187:drug effects; D005354:Fibrosarcoma; D015870:Gene Expression; D018922:HL-60 Cells; D006801:Humans; D008564:Membrane Potentials / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects* / Q000378:metabolism* / Q000648:ultrastructure; D008929:Mitochondria, Heart / Q000648:ultrastructure; D009206:Myocardium / Q000648:ultrastructure; D009861:Onium Compounds / Q000494:pharmacology*; D051381:Rats; D013367:Submitochondrial Particles / Q000378:metabolism; D013482:Superoxide Dismutase / Q000235:genetics; D013481:Superoxides / Q000378:metabolism* / Q000494:pharmacology; D014407:Tumor Cells, Cultured
chemical_list: D000975:Antioxidants; D003574:Cytochrome c Group; D009861:Onium Compounds; D013481:Superoxides; C007517:diphenyleneiodonium; D013482:Superoxide Dismutase; C505407:CASP3 protein, human; C505410:Casp3 protein, rat; D053148:Caspase 3; D020169:Caspases