Method for monitoring of mitochondrial cytochrome c release during cell death: Immunodetection of cytochrome c by flow cytometry after selective permeabilization of the plasma membrane

Background: Cytochrome c release from mitochondria to cytosol is a hallmark of apoptosis and is used to characterize the mutochondria-dependent pathway of this type of cell death. Techniques currently used to measure cytochrome c release, Western blot and fluorescence microscopy of imnumolabeled cells, are time-consuming and inaccurate. and the latter is still limited by sample size. Methods: We developed a rapid and reliable technique to detect cytochrome c release during drug-induced apoptosis, using flow cytometry. Plasma membrane of apoptotic HL-60 cells and thymocytes, treated with staurosporine and dexamethasone. respectively, were selectively permeabilized by digitonin at a low concentration. The released cytochrome c vas quickly washed out from cells and that which remained in the mitochondria was immunolabeled after fixing the cells. Results: The fraction of cells that retained their mitochondrial cytochrome c, or the highly fluorescent cells, gradually decreased so that after 4-8 h of drug treatment almost all the cells lost their cytochrome c and emerged as a population of low fluorescent cells. This was confirmed by parallel fluorescence microscopy of cells immunolabeled for cytochrome c. Conclusions: This technique allows the analysis of cytochrome c release from mitochondria of a large number of apoptotic cells in a short period of time and is proposed as an alternative to the methods Currently used for this same purpose.(c) 2006 International Society for Analytical Cytology.69A651552

Mangifera indica L. extract (Vimang (R)) and its main polyphenol mangiferin prevent mitochondrial oxidative stress in atherosclerosis-prone hypercholesterolemic mouse

Atherosclerosis is linked to a number of oxidative events ranging from low-density lipoprotein (LDL) oxidation to the increased production of intracellular reactive oxygen species (ROS). We have recently demonstrated that liver mitochondria isolated from the atherosclerosis-prone hypercholesterolemic LDL receptor knockout (LDLr-/-) mice have lower content of NADP(H)-linked substrates than the controls and, as consequence, higher sensitivity to oxidative stress and mitochondrial membrane permeability transition (MPT). In the present work, we show that oral supplementation with the antioxidants Mangifera indica L. extract (Vimang (R)) or its main polyphenol mangiferin shifted the sensitivity of LDLr-/- liver mitochondria to MPT to control levels. These in vivo treatments with Vimang (R) and mangiferin also significantly reduced ROS generation by both isolated LDLr-/- liver mitochondria and spleen lymphocytes. In addition, these antioxidant treatments prevented mitochondrial NAD(P)H-linked substrates depletion and NADPH spontaneous oxidation. In summary, Vimang (R) and mangiferin spared the endogenous reducing equivalents (NADPH) in LDLr-/- mice mitochondria correcting their lower antioxidant capacity and restoring the organelle redox homeostasis. The effective bioavailability of these compounds makes them suitable antioxidants with potential use in atherosclerosis susceptible conditions. (C) 2008 Elsevier Ltd. All rights reserved.57533233

Activation of the mitochondrial ATP-sensitive K+ channel reduces apoptosis of spleen mononuclear cells induced by hyperlipidemia

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Background: We have previously demonstrated that increased rates of superoxide generation by extramitochondrial enzymes induce the activation of the mitochondrial ATP-sensitive potassium channel (mitoK(ATP)) in the livers of hypertriglyceridemic (HTG) mice. The resulting mild uncoupling mediated by mitoK(ATP) protects mitochondria against oxidative damage. In this study, we investigate whether immune cells from HTG mice also present increased mitoK(ATP) activity and evaluate the influence of this trait on cell redox state and viability. Methods: Oxygen consumption (Clark-type electrode), reactive oxygen species production (dihydroethidium and H2-DCF-DA probes) and cell death (annexin V, cytocrome c release and Trypan blue exclusion) were determined in spleen mononuclear cells. Results: HTG mice mononuclear cells displayed increased mitoK(ATP) activity, as evidenced by higher resting respiration rates that were sensitive to mitoK(ATP) antagonists. Whole cell superoxide production and apoptosis rates were increased in HTG cells. Inhibition of mitoK(ATP) further increased the production of reactive oxygen species and apoptosis in these cells. Incubation with HTG serum induced apoptosis more strongly in WT cells than in HTG mononuclear cells. Cytochrome c release into the cytosol and caspase 8 activity were both increased in HTG cells, indicating that cell death signaling starts upstream of the mitochondria but does involve this organelle. Accordingly, a reduced number of blood circulating lymphocytes was found in HTG mice. Conclusions: These results demonstrate that spleen mononuclear cells from hyperlipidemic mice have more active mitoKATP channels, which downregulate mitochondrial superoxide generation. The increased apoptosis rate observed in these cells is exacerbated by closing the mitoK(ATP) channels. Thus, mitoK(ATP) opening acts as a protective mechanism that reduces cell death induced by hyperlipidemia.12Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)FAPESP [2006/53705-8, 2006/59786-0, 2011/50400-0]CNPq [304532/2010-0