scholarly journals The role of the mitochondria in apoptosis induced by 7β-hydroxycholesterol and cholesterol-5β,6β-epoxide

2005 ◽  
Vol 94 (4) ◽  
pp. 519-525 ◽  
Author(s):  
Lisa Ryan ◽  
Yvonne C. O'Callaghan ◽  
Nora M. O'Brien
Keyword(s):  
Membrane Potential ◽  
Mitochondrial Membrane Potential ◽  
Mitochondrial Membrane ◽  
Mitochondrial Permeability Transition Pore ◽  
Mitochondrial Permeability Transition ◽  
Permeability Transition Pore ◽  
Permeability Transition ◽  
Apoptotic Pathways ◽  
Induced Apoptosis

Oxysterols are oxygenated derivatives of cholesterol that may be formed endogenously or absorbed from the diet. Significant amounts of oxysterols have frequently been identified in foods of animal origin, in particular highly processed foods. To date, oxysterols have been shown to possess diverse biological activities; however, recent attention has focused on their potential role in the development of atherosclerosis. Oxysterols have been reported to induce apoptosis in cells of the arterial wall, a primary process in the development of atheroma. The aim of the present study was to identify the role of the mitochondria in the apoptotic pathways induced by the oxysterols 7β-hydroxycholesterol (7β-OH) and cholesterol-5β,6β-epoxide (β-epoxide) in U937 cells. To this end, we investigated the effects of these oxysterols on mitochondrial membrane potential, caspase-8 activity, the mitochondrial permeability transition pore and cytochrome c release. 7β-OH-induced apoptosis was associated with a loss in mitochondrial membrane potential after 2 h, accompanied by cytochrome c release from the mitochondria into the cytosol after 16 h. Pre-treatment with a range of inhibitors of the mitochondrial permeability transition pore protected against 7β-OH-induced cell death. In contrast, β-epoxide induced a slight increase in caspase-8 activity but had no effect on mitochondrial membrane potential or cytochrome c release. The present results confirm that 7β-OH-induced apoptosis occurs via the mitochondrial pathway and highlights differences in the apoptotic pathways induced by 7β-OH and β-epoxide in U937 cells.

scholarly journals Antimicrobial peptide CGA-N12 decreases the Candida tropicalis mitochondrial membrane potential via mitochondrial permeability transition pore

2020 ◽  
Vol 40 (5) ◽  
Author(s):  
Ruifang Li ◽  
Jiarui Zhao ◽  
Liang Huang ◽  
Yanjie Yi ◽  
Aihua Li ◽  
...  
Keyword(s):  
Membrane Potential ◽  
Mitochondrial Membrane Potential ◽  
Candida Tropicalis ◽  
Mitochondrial Membrane ◽  
Mitochondrial Permeability Transition Pore ◽  
Mitochondrial Permeability Transition ◽  
Permeability Transition Pore ◽  
Permeability Transition ◽  
Mitochondrial Permeability ◽  
Mptp Opening

Abstract Amino acid sequence from 65th to 76th residue of the N-terminus of Chromogranin A (CGA-N12) is an antimicrobial peptide (AMP). Our previous studies showed that CGA-N12 reduces Candida tropicalis mitochondrial membrane potential. Here, we explored the mechanism that CGA-N12 collapsed the mitochondrial membrane potential by investigations of its action on the mitochondrial permeability transition pore (mPTP) complex of C. tropicalis. The results showed that CGA-N12 induced cytochrome c (Cyt c) leakage, mitochondria swelling and led to polyethylene glycol (PEG) of molecular weight 1000 Da penetrate mitochondria. mPTP opening inhibitors bongkrekic acid (BA) could contract the mitochondrial swelling induced by CGA-N12, but cyclosporin A (CsA) could not. Therefore, we speculated that CGA-N12 could induce C. tropicolis mPTP opening by preventing the matrix-facing (m) conformation of adenine nucleotide transporter (ANT), thereby increasing the permeability of the mitochondrial membrane and resulted in the mitochondrial potential dissipation.

scholarly journals The Myxoma Poxvirus Protein, M11L, Prevents Apoptosis by Direct Interaction with the Mitochondrial Permeability Transition Pore

2002 ◽  
Vol 196 (9) ◽  
pp. 1127-1140 ◽  
Author(s):  
Helen Everett ◽  
Michele Barry ◽  
Xuejun Sun ◽  
Siow Fong Lee ◽  
Christine Frantz ◽  
...  
Keyword(s):  
Membrane Potential ◽  
Mitochondrial Membrane Potential ◽  
Mitochondrial Membrane ◽  
Mitochondrial Permeability Transition Pore ◽  
Mitochondrial Permeability Transition ◽  
Permeability Transition Pore ◽  
Permeability Transition ◽  
Mitochondrial Permeability ◽  
Potential Loss ◽  
Mitochondrial Membrane Potential Loss

M11L, an antiapoptotic protein essential for the virulence of the myxoma poxvirus, is targeted to mitochondria and prevents the loss of mitochondrial membrane potential that accompanies cell death. In this study we show, using a cross-linking approach, that M11L physically associates with the mitochondrial peripheral benzodiazepine receptor (PBR) component of the permeability transition (PT) pore. Close association of M11L and the PBR is also indicated by fluorescence resonance energy transfer (FRET) analysis. Stable expression of M11L prevents the release of mitochondrial cytochrome c induced by staurosporine or protoporphyrin IX (PPIX), a ligand of the PBR. Transiently expressed M11L also prevents mitochondrial membrane potential loss induced by PPIX, or induced by staurosporine in combination with PK11195, another ligand of the PBR. Myxoma virus infection and the associated expression of early proteins, including M11L, protects cells from staurosporine- and Fas-mediated mitochondrial membrane potential loss and this effect is augmented by the presence of PBR. We conclude that M11L regulates the mitochondrial permeability transition pore complex, most likely by direct modulation of the PBR.

scholarly journals Erinacine Facilitates the Opening of the Mitochondrial Permeability Transition Pore Through the Inhibition of the PI3K/ Akt/GSK-3β Signaling Pathway in Human Hepatocellular Carcinoma

2018 ◽  
Vol 50 (3) ◽  
pp. 851-867 ◽  
Author(s):  
Li-Jie Zhou ◽  
Yan-Bo Mo ◽  
Xuan Bu ◽  
Jian-Jun Wang ◽  
Jing Bai ◽  
...  
Keyword(s):  
Membrane Potential ◽  
Signaling Pathway ◽  
Mitochondrial Membrane Potential ◽  
Colony Formation ◽  
Mitochondrial Membrane ◽  
Mitochondrial Permeability Transition ◽  
Permeability Transition Pore ◽  
Permeability Transition ◽  
Cyt C ◽  
Gsk 3Β

Background/Aims: Erinacine, which is extracted from the medicinal mushroom Hericium erinaceus, is known to play anticancer roles in human cancers. The following study aims to investigate the role of erinacine in the opening of the mitochondrial permeability transition pore (MPTP) in hepatocellular carcinoma (HCC) through the PI3K/Akt/GSK-3β signaling pathway and highlights the applicability of erinacine in HCC treatments. Methods: HCC and paracancerous tissues were obtained from 85 HCC patients who’ve undergone surgical resection. Immunohistochemistry was adopted to detect positive expression of PI3K, Akt, and GSK-3β. Treatment of HepG-2 with LY294002 (an inhibitor of the PI3K/Akt/GSK-3β signaling pathway) and different concentration of erinacine was performed to determine the involvement of LY294002 in erinacine action. The expressions of PI3K, Akt, GSK-3β, CyclinD1, Vimentin, β-catenin, Bcl-2, E-cadherin, Bax, and caspase-9 were determined by RT-qPCR and Western blot analysis. Cell viability, colony formation rate, migration, invasion, cycle, and apoptosis were detected by MTT, colony formation, wound healing assay, Transwell assay, and flow cytometry, respectively. The size and weight of xenograft tumors were observed in nude mice. Mitochondrial membrane potential in HepG-2 was determined using laser scanning confocal microscopy following JC-1 staining. Mitochondrial Ca2+ indicator Rhod-2, AM was used to detect the changes of mitochondrial Ca2+, while western blot analysis was employed to detect the presence levels of cytochrome C (cyt-C). Results: The results revealed that PI3K, Akt, and GSK-3β were up-regulated in HCC tissues. Erinacine or LY294002 led to a decrease in mitochondrial membrane potential, increase in intracellular mitochondrial Ca2+, and the release of cyt-C in mitochondria. In addition, Erinacine was found to decrease the mitochondrial membrane potential, expression of PI3K, Akt, GSK-3β, CyclinD1, Vimentin, β-catenin, and Bcl-2, cell proliferation, colony formation ability, migration, invasion, and xenograft tumor size, while E-cadherin, Bax, and caspase-9 expression, and cell apoptosis were elevated in a dose-dependent manner. Erinacine also stimulated the effects of LY294002 on the HCC. Following the addition of 500 μM Erinacine and MPTP opening inhibitor CsA, we found that the mitochondrial membrane potential level increased, while mitochondrial Ca2+ and Cyt-C decreased from the mitochondria. Conclusion: The results from the study demonstrated that erinacine induced MPTP opening, facilitates the release of cyt-C, and inhibited cell proliferation, migration, and invasion, while it promotes apoptosis by inactivating the PI3K/Akt/GSK-3β signaling pathway, preventing the progression of HCC.

Δ9-Tetrahydrocannabinol disrupts mitochondrial function and cell energetics

2003 ◽  
Vol 284 (2) ◽  
pp. L298-L306 ◽  
Author(s):  
Theodore A. Sarafian ◽  
Shaghig Kouyoumjian ◽  
Farnaz Khoshaghideh ◽  
Donald P. Tashkin ◽  
Michael D. Roth
Keyword(s):  
Membrane Potential ◽  
Mitochondrial Membrane Potential ◽  
Mitochondrial Function ◽  
Mitochondrial Membrane ◽  
Mitochondrial Permeability Transition ◽  
Permeability Transition Pore ◽  
Permeability Transition ◽  
Mitochondrial Inhibitors ◽  
Transformed Cell Line ◽  
Important Health

We have observed rapid and extensive depletion of cellular energy stores by Δ9-tetrahydrocannabinol (THC) in the pulmonary transformed cell line A549. ATP levels declined dose dependently with an IC50 of 7.5 μg/ml of THC after 24-h exposure. Cell death was observed only at concentrations >10 μg/ml. Studies using JC-1, a fluorescent probe for mitochondrial membrane potential, revealed diminished mitochondrial function at THC concentrations as low as 0.5 μg/ml. At concentrations of 2.5 or 10 μg/ml of THC, a decrease in mitochondrial membrane potential was observed as early as 1 h after THC exposure. Mitochondrial function remained diminished for at least 30 h after THC exposure. Flow cytometry studies on cells exposed to particulate smoke extracts indicate that JC-1 red fluorescence was fivefold lower in cells exposed to marijuana smoke extract relative to cells exposed to tobacco smoke extract. Comparison with a variety of mitochondrial inhibitors demonstrates that THC produced effects similar to that of carbonyl cyanide p-trifluoromethoxyphenylhydrazone, suggesting uncoupling of electron transport. Loss of red JC-1 fluorescence by THC was suppressed by cyclosporin A, suggesting mediation by the mitochondrial permeability transition pore. This disruption of mitochondrial function was sustained for at least 24 h after removal of THC by extensive washing. These results suggest that exposure of the bronchopulmonary epithelium to THC may have important health and physiological consequences.

scholarly journals Mechanisms of ER Stress-Mediated Mitochondrial Membrane Permeabilization

2010 ◽  
Vol 2010 ◽  
pp. 1-9 ◽  
Author(s):  
Sanjeev Gupta ◽  
Lorraine Cuffe ◽  
Eva Szegezdi ◽  
Susan E. Logue ◽  
Catherine Neary ◽  
...  
Keyword(s):  
Er Stress ◽  
Mitochondrial Membrane ◽  
Mitochondrial Permeability Transition Pore ◽  
Mitochondrial Permeability Transition ◽  
Permeability Transition Pore ◽  
Permeability Transition ◽  
Membrane Permeabilization ◽  
Caspase 9 ◽  
Mitochondrial Permeability ◽  
Induced Apoptosis

During apoptosis, the process of mitochondrial outer membrane permeabilization (MOMP) represents a point-of-no-return as it commits the cell to death. Here we have assessed the role of caspases, Bcl-2 family members and the mitochondrial permeability transition pore on ER stress-induced MOMP and subsequent cell death. Induction of ER stress leads to upregulation of several genes such as Grp78, Edem1, Erp72, Atf4, Wars, Herp, p58ipk, and ERdj4 and leads to caspase activation, release of mitochondrial intermembrane proteins and dissipation of mitochondrial transmembrane potential (ΔΨm). Mouse embryonic fibroblasts (MEFs) from caspase-9, -2 and, -3 knock-out mice were resistant to ER stress-induced apoptosis which correlated with decreased processing of pro-caspase-3 and -9. Furthermore, pretreatment of cells with caspase inhibitors (Boc-D.fmk and DEVD.fmk) attenuated ER stress-induced loss ofΔΨm. However, only deficiency of caspase-9 and -2 could prevent ER stress-mediated loss ofΔΨm. Bcl-2 overexpression or pretreatment of cells with the cell permeable BH4 domain (BH4-Tat) or the mitochondrial permeability transition pore inhibitors, bongkrekic acid or cyclosporine A, attenuated the ER stress-induced loss ofΔΨm. These data suggest a role for caspase-9 and -2, Bcl-2 family members and the mitochondrial permeability transition pore in loss of mitochondrial membrane potential during ER stress-induced apoptosis.

scholarly journals Inorganic polyphosphate is a potent activator of the mitochondrial permeability transition pore in cardiac myocytes

2012 ◽  
Vol 139 (5) ◽  
pp. 321-331 ◽  
Author(s):  
Lea K. Seidlmayer ◽  
Maria R. Gomez-Garcia ◽  
Lothar A. Blatter ◽  
Evgeny Pavlov ◽  
Elena N. Dedkova
Keyword(s):  
Mitochondrial Membrane ◽  
Mitochondrial Permeability Transition Pore ◽  
Mitochondrial Permeability Transition ◽  
Permeability Transition Pore ◽  
Permeability Transition ◽  
Inner Mitochondrial Membrane ◽  
Inorganic Polyphosphate ◽  
Mitochondrial Permeability ◽  
Mptp Opening

Mitochondrial dysfunction caused by excessive Ca2+ accumulation is a major contributor to cardiac cell and tissue damage during myocardial infarction and ischemia–reperfusion injury (IRI). At the molecular level, mitochondrial dysfunction is induced by Ca2+-dependent opening of the mitochondrial permeability transition pore (mPTP) in the inner mitochondrial membrane, which leads to the dissipation of mitochondrial membrane potential (ΔΨm), disruption of adenosine triphosphate production, and ultimately cell death. Although the role of Ca2+ for induction of mPTP opening is established, the exact molecular mechanism of this process is not understood. The aim of the present study was to test the hypothesis that the adverse effect of mitochondrial Ca2+ accumulation is mediated by its interaction with inorganic polyphosphate (polyP), a polymer of orthophosphates linked by phosphoanhydride bonds. We found that cardiac mitochondria contained significant amounts (280 ± 60 pmol/mg of protein) of short-chain polyP with an average length of 25 orthophosphates. To test the role of polyP for mPTP activity, we investigated kinetics of Ca2+ uptake and release, ΔΨm and Ca2+-induced mPTP opening in polyP-depleted mitochondria. polyP depletion was achieved by mitochondria-targeted expression of a polyP-hydrolyzing enzyme. Depletion of polyP in mitochondria of rabbit ventricular myocytes led to significant inhibition of mPTP opening without affecting mitochondrial Ca2+ concentration by itself. This effect was observed when mitochondrial Ca2+ uptake was stimulated by increasing cytosolic [Ca2+] in permeabilized myocytes mimicking mitochondrial Ca2+ overload observed during IRI. Our findings suggest that inorganic polyP is a previously unrecognized major activator of mPTP. We propose that the adverse effect of polyphosphate might be caused by its ability to form stable complexes with Ca2+ and directly contribute to inner mitochondrial membrane permeabilization.

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