Cytokine-induced apoptosis and necrosis are preceded by disruption of the mitochondrial membrane potential (Deltapsi(m)) in pancreatic RINm5F cells: prevention by Bcl-2.
The mechanisms of cytokine-induced beta-cell death are poorly characterised. In rat insulin-producing RINm5F cells, the combination of interleukin-1beta, interferon-gamma and tumour necrosis factor-alpha presently induced disruption of the mitochondrial membrane potential (Deltapsi(m)) as demonstrated by reduced JC-1 fluorescence. The reduction of Deltapsi(m) was maximal after 8 h and was preceded by increased formation of reactive oxygen species (ROS), as assessed by dichlorofluorescein-diacetate (DCFH-DA) fluorescence. A nitric oxide synthase-, but not a ROS-inhibitor, prevented cytokine-induced loss of Deltapsi(m). Overexpression of the anti-apoptotic protein Bcl-2 increased both JC-1 and DCFH-DA fluorescence, which was paralleled by protection against cytokine-induced apoptosis and necrosis. It is concluded that cytokines induce a nitric oxide-dependent disruption of Deltapsi(m) and that this may be a necessary event for both beta-cell apoptosis and necrosis. Bcl-2 may prevent beta-cell death by counteracting mitochondrial permeability transition.
Barbu
Andreea
A
Department of Medical Cell Biology, Biomedical Centre, Uppsala University, PO Box 571, S-751 23, Sweden.
Welsh
Nils
N
Saldeen
Johan
J
D000818:Animals; D017209:Apoptosis; D001562:Benzimidazoles / Q000378:metabolism; D002232:Carbocyanines / Q000378:metabolism; D002374:Catalase / Q000378:metabolism; D002460:Cell Line; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005434:Flow Cytometry / Q000379:methods; D005452:Fluoresceins / Q000378:metabolism; D005456:Fluorescent Dyes / Q000378:metabolism; D007371:Interferon-gamma / Q000494:pharmacology*; D007375:Interleukin-1 / Q000494:pharmacology*; D007515:Islets of Langerhans / Q000187:drug effects / Q000502:physiology; D008564:Membrane Potentials / Q000187:drug effects*; D008928:Mitochondria / Q000187:drug effects* / Q000378:metabolism; D009336:Necrosis; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
D001562:Benzimidazoles; D002232:Carbocyanines; D004791:Enzyme Inhibitors; D005452:Fluoresceins; D005456:Fluorescent Dyes; D007375:Interleukin-1; D019253:Proto-Oncogene Proteins c-bcl-2; D017382:Reactive Oxygen Species; D014409:Tumor Necrosis Factor-alpha; C029569:diacetyldichlorofluorescein; C068624:5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolocarbocyanine; D007371:Interferon-gamma; D002374:Catalase; D019001:Nitric Oxide Synthase