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Mitochondrial Permeabilization (mitochondrial + permeabilization)

Distribution by Scientific Domains

Medical Sciences	75%

Selected Abstracts

Mitochondrial protection by the JNK inhibitor leflunomide rescues mice from acetaminophen-induced liver injury,

HEPATOLOGY, Issue 2 2007
Calivarathan Latchoumycandane
Acetaminophen (APAP) is a widely used analgesic and antipyretic drug that is safe at therapeutic doses but which can precipitate liver injury at high doses. We have previously found that the antirheumatic drug leflunomide is a potent inhibitor of APAP toxicity in cultured human hepatocytes, protecting them from mitochondria-mediated cell death by inhibiting the mitochondrial permeability transition. The purpose of this study was to explore whether leflunomide protects against APAP hepatotoxicity in vivo and to define the molecular pathways of cytoprotection. Male C57BL/6 mice were treated with a hepatotoxic dose of APAP (750 mg/kg, ip) followed by a single injection of leflunomide (30 mg/kg, ip). Leflunomide (4 hours after APAP dose) afforded significant protection from liver necrosis as assessed by serum ALT activity and histopathology after 8 and 24 hours. The mechanism of protection by leflunomide was not through inhibition of cytochrome P450 (CYP),catalyzed APAP bioactivation or an apparent suppression of the innate immune system. Instead, leflunomide inhibited APAP-induced activation (phosphorylation) of c-jun NH2 -terminal protein kinase (JNK), thus preventing downstream Bcl-2 and Bcl-XL inactivation and protecting from mitochondrial permeabilization and cytochrome c release. Furthermore, leflunomide inhibited the APAP-mediated increased expression of inducible nitric oxide synthase and prevented the formation of peroxynitrite, as judged from the absence of hepatic nitrotyrosine adducts. Even when given 8 hours after APAP dose, leflunomide still protected from massive liver necrosis. Conclusion: Leflunomide afforded protection against APAP-induced hepatotoxicity in mice through inhibition of JNK-mediated activation of mitochondrial permeabilization. (HEPATOLOGY 2007.) [source]

Involvement of Ca2+ and ROS in ,-tocopheryl succinate-induced mitochondrial permeabilization

INTERNATIONAL JOURNAL OF CANCER, Issue 8 2010
Vladimir Gogvadze
Abstract Release of mitochondrial proteins such as cytochrome c, AIF, Smac/Diablo etc., plays a crucial role in apoptosis induction. A redox-silent analog of vitamin E, ,-tocopheryl succinate (,-TOS), was shown to stimulate cytochrome c release via production of reactive oxygen species (ROS) and Bax-mediated permeabilization of the outer mitochondrial membrane. Here we show that ,-TOS facilitates mitochondrial permeability transition (MPT) in isolated rat liver mitochondria, Tet21N neuroblastoma cells and Jurkat T-lymphocytes. In particular, in addition to ROS production, ,-TOS stimulates rapid Ca2+ entry into the cells with subsequent accumulation of Ca2+ in mitochondria,a prerequisite step for MPT induction. Alteration of mitochondrial Ca2+ buffering capacity was observed as early as 8 hr after incubation with ,-TOS, when no activation of Bax was yet detected. Ca2+ accumulation in mitochondria was important for apoptosis progression, since inhibition of mitochondrial Ca2+ uptake significantly mitigated the apoptotic response. Importantly, Ca2+ -induced mitochondrial destabilization might cooperate with Bax-mediated mitochondrial outer membrane permeabilization to induce cytochrome c release from mitochondria. [source]

Cell death: regulation by the Bcl-2 protein family

PSYCHOGERIATRICS, Issue 2006
Yoshihide TSUJIMOTO
Abstract An increase in mitochondrial membrane permeability is central to cell death including apoptosis and necrosis. During apoptosis, permeabilization of outer mitochondrial membrane leads to the release of several apoptogenic factors, such as cytochrome c and Smac/Diablo, into the cytoplasm that activate downstream death programs, including apoptotic proteases called caspases, although the detailed mechanism of outer mitochondrial membrane permeabilization remains elusive. Although the mitochondrial membrane permeability transition (MPT), resulting in ,, loss, mitochondrial swelling and rupture of the outer membrane has initially been proposed as a general mechanism for apoptotic permeabilization of outer mitochondrial membrane, the recent studies with cyclophilin D-deficient mice indicate that MPT regulates some forms of necrotic death, but not apoptotic death, and that MPT is involved in ischemia,reperfusion injury in heart and brain. Anti-apoptotic proteins, Bcl-2 and Bcl-xL, efficiently block not only apoptotic mitochondrial permeabilization but also MPT. The present paper focuses on the mechanisms by which Bcl-2 family members control the permeability of mitochondrial membrane during apoptosis and necrosis. [source]

BAK and BAX deletion using zinc-finger nucleases yields apoptosis-resistant CHO cells

BIOTECHNOLOGY & BIOENGINEERING, Issue 2 2010
Gregory J. Cost
Abstract Anoxic and metabolic stresses in large-scale cell culture during biopharmaceutical production can induce apoptosis. Strategies designed to ameliorate the problem of apoptosis in cell culture have focused on mRNA knockdown of pro-apoptotic proteins and over-expression of anti-apoptotic ones. Apoptosis in cell culture involves mitochondrial permeabilization by the pro-apoptotic Bak and Bax proteins; activity of either protein is sufficient to permit apoptosis. We demonstrate here the complete and permanent elimination of both the Bak and Bax proteins in combination in Chinese hamster ovary (CHO) cells using zinc-finger nuclease-mediated gene disruption. Zinc-finger nuclease cleavage of BAX and BAK followed by inaccurate DNA repair resulted in knockout of both genes. Cells lacking Bax and Bak grow normally but fail to activate caspases in response to apoptotic stimuli. When grown using scale-down systems under conditions that mimic growth in large-scale bioreactors they are significantly more resistant to apoptosis induced by starvation, staurosporine, and sodium butyrate. When grown under starvation conditions, BAX - and BAK -deleted cells produce two- to fivefold more IgG than wild-type CHO cells. Under normal growth conditions in suspension culture in shake flasks, double-knockout cultures achieve equal or higher cell densities than unmodified wild-type cultures and reach viable cell densities relevant for large-scale industrial protein production. Biotechnol. Bioeng. 2010; 105: 330,340. © 2009 Wiley Periodicals, Inc. [source]