scholarly journals Phosphate is not an absolute requirement for the inhibitory effects of cyclosporin A or cyclophilin D deletion on mitochondrial permeability transition

2012 ◽  
Vol 443 (1) ◽  
pp. 185-191 ◽  
Author(s):  
Allison M. McGee ◽  
Christopher P. Baines
Keyword(s):  
Cyclosporin A ◽  
Mitochondrial Permeability Transition ◽  
Permeability Transition Pore ◽  
Permeability Transition ◽  
Liver Mitochondria ◽  
Cyclophilin D ◽  
Wild Type ◽  
Inhibitory Effects ◽  
Mitochondrial Permeability ◽  
Pre Treatment

CypD (cyclophilin D) has been established as a critical regulator of the MPT (mitochondrial permeability transition) pore, and pharmacological or genetic inhibition of CypD attenuates MPT in numerous systems. However, it has recently been suggested that the inhibitory effects of CypD inhibition only manifest when Pi (inorganic phosphate) is present, and that inhibition is lost when Pi is replaced by Asi (inorganic arsenate) or Vi (inorganic vanadate). To test this, liver mitochondria were isolated from wild-type and CypD-deficient (Ppif−/−) mice and then incubated in buffer containing Pi, Asi or Vi. MPT was induced under both energized and de-energized conditions by the addition of Ca2+, and the resultant mitochondrial swelling was measured spectrophotometrically. For pharmacological inhibition of CypD, wild-type mitochondria were pre-incubated with CsA (cyclosporin A) before the addition of Ca2+. In energized and de-energized mitochondria, Ca2+ induced MPT regardless of the anion present, although the magnitude differed between Pi, Asi and Vi. However, in all cases, pre-treatment with CsA significantly inhibited MPT. Moreover, these effects were independent of mouse strain, organ type and rodent species. Similarly, attenuation of Ca2+-induced MPT in the Ppif−/− mitochondria was still observed irrespective of whether Pi, Asi or Vi was present. We conclude that the pharmacological and genetic inhibition of CypD is still able to attenuate MPT even in the absence of Pi.

scholarly journals Inhibition of mitochondrial permeability transition by deletion of the ANT family and CypD

2019 ◽  
Vol 5 (8) ◽  
pp. eaaw4597 ◽  
Author(s):  
Jason Karch ◽  
Michael J. Bround ◽  
Hadi Khalil ◽  
Michelle A. Sargent ◽  
Nadina Latchman ◽  
...  
Keyword(s):  
Mitochondrial Permeability Transition ◽  
Adenine Nucleotide ◽  
Permeability Transition Pore ◽  
Permeability Transition ◽  
Liver Mitochondria ◽  
Null Mouse ◽  
Cyclophilin D ◽  
Inner Membrane ◽  
Membrane Pore ◽  
Mitochondrial Permeability

The mitochondrial permeability transition pore (MPTP) has resisted molecular identification. The original model of the MPTP that proposed the adenine nucleotide translocator (ANT) as the inner membrane pore-forming component was challenged when mitochondria from Ant1/2 double null mouse liver still had MPTP activity. Because mice express three Ant genes, we reinvestigated whether the ANTs comprise the MPTP. Liver mitochondria from Ant1, Ant2, and Ant4 deficient mice were highly refractory to Ca2+-induced MPTP formation, and when also given cyclosporine A (CsA), the MPTP was completely inhibited. Moreover, liver mitochondria from mice with quadruple deletion of Ant1, Ant2, Ant4, and Ppif (cyclophilin D, target of CsA) lacked Ca2+-induced MPTP formation. Inner-membrane patch clamping in mitochondria from Ant1, Ant2, and Ant4 triple null mouse embryonic fibroblasts showed a loss of MPTP activity. Our findings suggest a model for the MPTP consisting of two distinct molecular components: The ANTs and an unknown species requiring CypD.

scholarly journals Chronic ethanol consumption enhances sensitivity to Ca2+-mediated opening of the mitochondrial permeability transition pore and increases cyclophilin D in liver

2010 ◽  
Vol 299 (4) ◽  
pp. G954-G966 ◽  
Author(s):  
Adrienne L. King ◽  
Telisha M. Swain ◽  
Dale A. Dickinson ◽  
Mathieu J. Lesort ◽  
Shannon M. Bailey
Keyword(s):  
Gene Expression ◽  
Mitochondrial Permeability Transition Pore ◽  
Mitochondrial Permeability Transition ◽  
Permeability Transition Pore ◽  
Permeability Transition ◽  
Liver Mitochondria ◽  
Cyclophilin D ◽  
Retention Capacity ◽  
Mitochondrial Permeability ◽  
Chronic Ethanol Consumption

Chronic ethanol consumption increases mitochondrial oxidative stress and sensitivity to form the mitochondrial permeability transition pore (MPTP). The mechanism responsible for increased MPTP sensitivity in ethanol-exposed mitochondria and its relation to mitochondrial Ca2+ handling is unknown. Herein, we investigated whether increased sensitivity to MPTP induction in liver mitochondria from ethanol-fed rats compared with controls is related to an ethanol-dependent change in mitochondrial Ca2+ accumulation. Liver mitochondria were isolated from control and ethanol-fed rats, and Ca2+-mediated induction of the MPTP and mitochondrial Ca2+ retention capacity were measured. Levels of proposed MPTP proteins as well as select pro- and antiapoptotic proteins were measured along with gene expression. We observed increased steatosis and TUNEL-stained nuclei in liver of ethanol-fed rats compared with controls. Liver mitochondria from ethanol-fed rats had increased levels of proapoptotic Bax protein and reduced Ca2+ retention capacity compared with control mitochondria. We observed increased cyclophilin D (Cyp D) gene expression in liver and protein in mitochondria from ethanol-fed animals compared with controls, whereas there was no change in the adenine nucleotide translocase and voltage-dependent anion channel. Together, these results suggest that enhanced sensitivity to Ca2+-mediated MPTP induction may be due, in part, to higher Cyp D levels in liver mitochondria from ethanol-fed rats. Therefore, therapeutic strategies aimed at normalizing Cyp D levels may be beneficial in preventing ethanol-dependent mitochondrial dysfunction and liver injury.

Abstract 168: Resveratrol Translocates Gsk-3β To Mitochondria And Protects The Heart At Reperfusion By Targeting The Mitochondrial Permeability Transition Pore

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Jinkun Xi ◽  
Huihua Wang ◽  
Guillaume Chanoit ◽  
Guang Cheng ◽  
Robert A Mueller ◽  
...  
Keyword(s):  
Reperfusion Injury ◽  
Mitochondrial Permeability Transition Pore ◽  
Mitochondrial Permeability Transition ◽  
Permeability Transition Pore ◽  
Permeability Transition ◽  
Cyclophilin D ◽  
Risk Zone ◽  
Mitochondrial Permeability ◽  
Mptp Opening ◽  
Gsk 3Β

Although resveratrol has been demonstrated to be cardioprotective, the detailed cellular and molecular mechanisms that mediate the protection remain elusive. We aimed to determine if resveratrol protects the heart at reperfusion by modulating the mitochondrial permeability transition pore (mPTP) opening through glycogen synthase kinase 3β (GSK-3β). Resveratrol (10μM) given at reperfusion reduced infarct size (12.2 ± 2.5 % of risk zone vs. 37.9 ± 3.1 % of risk zone in control, n = 6) in isolated rat hearts subjected to 30 min regional ischemia followed by 2 h of reperfusion, an effect that was abrogated by the mPTP opener atractyloside (30.9 ± 8.1 % of risk zone), implying that resveratrol may protect the heart at reperfusion by modulating the mPTP opening. To define the signaling mechanism underlying the action of resveratrol, we determined GSK-3β activity by measuring its phosphorylation at Ser 9 . Resveratrol significantly enhanced GSK-3β phosphorylation upon reperfusion (225.2 ± 30.0 % of control at 5 min of reperfusion). Further experiments showed that resveratrol induces translocation of GSK-3β to mitochondria and translocated GSK-3β interacts with the mPTP component cyclophilin D but not VDAC (the voltage-dependent anion channel) or ANT (the adenine nucleotide translocator) in cardiac mitochondria. Taken together, these data suggest that resveratrol prevents myocardial reperfusion injury by targeting the mPTP opening via GSK-3β. Translocation of GSK-3β to mitochondria and its interaction with the mPTP component cyclophilin D may serve as an essential mechanism that mediates the protective effect of resveratrol on reperfusion injury.

scholarly journals Bax-induced Cytochrome C Release from Mitochondria Is Independent of the Permeability Transition Pore but Highly Dependent on Mg2+ Ions

1998 ◽  
Vol 143 (1) ◽  
pp. 217-224 ◽  
Author(s):  
Robert Eskes ◽  
Bruno Antonsson ◽  
Astrid Osen-Sand ◽  
Sylvie Montessuit ◽  
Christoph Richter ◽  
...  
Keyword(s):  
Cytochrome C ◽  
Cyclosporin A ◽  
Mitochondrial Permeability Transition Pore ◽  
Mitochondrial Permeability Transition ◽  
Permeability Transition Pore ◽  
Permeability Transition ◽  
Cytochrome C Release ◽  
Mitochondrial Permeability ◽  
Isolated Mitochondria ◽  
Mammalian Homologue

Bcl-2 family members either promote or repress programmed cell death. Bax, a death-promoting member, is a pore-forming, mitochondria-associated protein whose mechanism of action is still unknown. During apoptosis, cytochrome C is released from the mitochondria into the cytosol where it binds to APAF-1, a mammalian homologue of Ced-4, and participates in the activation of caspases. The release of cytochrome C has been postulated to be a consequence of the opening of the mitochondrial permeability transition pore (PTP). We now report that Bax is sufficient to trigger the release of cytochrome C from isolated mitochondria. This pathway is distinct from the previously described calcium-inducible, cyclosporin A–sensitive PTP. Rather, the cytochrome C release induced by Bax is facilitated by Mg2+ and cannot be blocked by PTP inhibitors. These results strongly suggest the existence of two distinct mechanisms leading to cytochrome C release: one stimulated by calcium and inhibited by cyclosporin A, the other Bax dependent, Mg2+ sensitive but cyclosporin insensitive.

Chronic Tempol treatment restores pharmacological preconditioning in the senescent rat heart

2013 ◽  
Vol 304 (5) ◽  
pp. H649-H659 ◽  
Author(s):  
Jiang Zhu ◽  
Mario J. Rebecchi ◽  
Qiang Wang ◽  
Peter S. A. Glass ◽  
Peter R. Brink ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Mitochondrial Permeability Transition Pore ◽  
Mitochondrial Permeability Transition ◽  
Permeability Transition Pore ◽  
Permeability Transition ◽  
Cyclophilin D ◽  
Mitochondrial Permeability ◽  
Anesthetic Preconditioning ◽  
Permeability Transition Pore Opening ◽  
Pore Opening

Cardioprotective effects of anesthetic preconditioning and cyclosporine A (CsA) are lost with aging. To extend our previous work and address a possible mechanism underlying age-related differences, we investigated the role of oxidative stress in the aging heart by treating senescent animals with the oxygen free radical scavenger Tempol. Old male Fischer 344 rats (22–24 mo) were randomly assigned to control or Tempol treatment groups for 2 or 4 wk (T×2wk and T×4wk, respectively). Rats received isoflurane 30 min before ischemia-reperfusion injury or CsA just before reperfusion. Myocardial infarction sizes were significantly reduced by isoflurane or CsA in the aged rats treated with Tempol (T×4wk) compared with old control rats. In other experiments, young (4–6 mo) and old rats underwent either chronic Tempol or vehicle treatment, and the levels of myocardial protein oxidative damage, antioxidant enzymes, mitochondrial Ca2+ uptake, cyclophilin D protein, and mitochondrial permeability transition pore opening times were measured. T×4wk significantly increased MnSOD enzyme activity, GSH-to-GSSH ratios, MnSOD protein level, mitochondrial Ca2+ uptake capacity, reduced protein nitrotyrosine levels, and normalized cyclophilin D protein expression in the aged rat heart. T×4wk also significantly prolonged mitochondrial permeability transition pore opening times induced by reactive oxygen species in old cardiomyocytes. Our studies demonstrate that 4 wk of Tempol pretreatment restores anesthetic preconditioning and cardioprotection by CsA in the old rat and that this is associated with decreased oxidative stress and improved mitochondrial function. Our results point to a new protective strategy for the ischemic myocardium in the high-risk older population.

scholarly journals Bisindolylpyrrole triggers transient mitochondrial permeability transitions to cause apoptosis in a VDAC1/2 and cyclophilin D-dependent manner via the ANT-associated pore

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Masami Koushi ◽  
Yasunori Aoyama ◽  
Yoshiko Kamei ◽  
Rei Asakai
Keyword(s):  
Mitochondrial Permeability Transition ◽  
Permeability Transition ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Dependent Manner ◽  
Cyclophilin D ◽  
Cytoprotective Effect ◽  
Mitochondrial Permeability ◽  
Sirna Knockdown ◽  
Pkc Activation

Abstract Bisindolylpyrrole at 0.1 μM is cytoprotective in 2% FBS that is counteracted by cyclosporin-A (CsA), an inhibitor of cyclophilin-D (CypD). We hypothesized that the cytoprotective effect might be due to transient mitochondrial permeability transition (tPT). This study tested the hypothesis that bisindolylpyrrole can trigger tPT extensively, thereby leading to cell death under certain conditions. Indeed, CsA-sensitive tPT-mediated apoptosis could be induced by bisindolylpyrrole at > 5 μM in HeLa cells cultured in 0.1% FBS, depending on CypD and VDAC1/2, as shown by siRNA knockdown experiments. Rat liver mitochondria also underwent swelling in response to bisindolylpyrrole, which proceeded at a slower rate than Ca2+-induced swelling, and which was blocked by the VDAC inhibitor tubulin and the ANT inhibitor bongkrekate, indicating the involvement of the ANT-associated, smaller pore. We examined why 0.1% FBS is a prerequisite for apoptosis and found that apoptosis is blocked by PKC activation, which is counteracted by the overexpressed defective PKCε. In mitochondrial suspensions, bisindolylpyrrole triggered CsA-sensitive swelling, which was suppressed selectively by pretreatment with PKCε, but not in the co-presence of tubulin. These data suggest that upon PKC inactivation the cytoprotective compound bisindolylpyrrole can induce prolonged tPT causing apoptosis in a CypD-dependent manner through the VDAC1/2-regulated ANT-associated pore.

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