scholarly journals Mitochondrial Dysfunction and Alterations in Mitochondrial Permeability Transition Pore (mPTP) Contribute to Apoptosis Resistance in Idiopathic Pulmonary Fibrosis Fibroblasts

2021 ◽  
Vol 22 (15) ◽  
pp. 7870
Author(s):  
Erika Rubí Luis-García ◽  
Carina Becerril ◽  
Alfonso Salgado-Aguayo ◽  
Omar Emiliano Aparicio-Trejo ◽  
Yair Romero ◽  
...  
Keyword(s):  
Mitomycin C ◽  
Mitochondrial Membrane ◽  
Mitochondrial Permeability Transition Pore ◽  
Mitochondrial Permeability Transition ◽  
Permeability Transition Pore ◽  
Permeability Transition ◽  
Apoptosis Resistance ◽  
Mitochondrial Permeability ◽  
Mptp Opening ◽  
Induced Apoptosis

Idiopathic pulmonary fibrosis (IPF) is a devastating disease characterized by increased activation of fibroblasts/myofibroblasts. Previous reports have shown that IPF fibroblasts are resistant to apoptosis, but the mechanisms remain unclear. Since inhibition of the mitochondrial permeability transition pore (mPTP) has been implicated in the resistance to apoptosis, in this study, we analyzed the role of mitochondrial function and the mPTP on the apoptosis resistance of IPF fibroblasts under basal conditions and after mitomycin C-induced apoptosis. We measured the release of cytochrome c, mPTP opening, mitochondrial calcium release, oxygen consumption, mitochondrial membrane potential, ADP/ATP ratio, ATP concentration, and mitochondrial morphology. We found that IPF fibroblasts were resistant to mitomycin C-induced apoptosis and that calcium, a well-established activator of mPTP, is decreased as well as the release of pro-apoptotic proteins such as cytochrome c. Likewise, IPF fibroblasts showed decreased mitochondrial function, while mPTP was less sensitive to ionomycin-induced opening. Although IPF fibroblasts did not present changes in the mitochondrial membrane potential, we found a fragmented mitochondrial network with scarce, thinned, and disordered mitochondria with reduced ATP levels. Our findings demonstrate that IPF fibroblasts are resistant to mitomycin C-induced apoptosis and that altered mPTP opening contributes to this resistance. In addition, IPF fibroblasts show mitochondrial dysfunction evidenced by a decrease in respiratory parameters.

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 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.

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.

Protectors of the mitochondrial permeability transition pore activated by iron and doxorubicin

2021 ◽  
Vol 21 ◽  
Author(s):  
Tatiana A. Fedotcheva ◽  
Nadezhda I. Fedotcheva
Keyword(s):  
Mitochondrial Permeability Transition Pore ◽  
Mitochondrial Permeability Transition ◽  
Membrane Damage ◽  
Permeability Transition Pore ◽  
Permeability Transition ◽  
Selective Electrode ◽  
Mitochondrial Permeability ◽  
Isolated Mitochondria ◽  
Mptp Opening ◽  
Dependent Cell

Aim: The study of action of iron, DOX, and their complex on the mitochondrial permeability transition pore (MPTP) opening and the detection of possible protectors of MPTP in the conditions close to mitochondria-dependent ferroptosis. Background: The toxicity of doxorubicin (DOX) is mainly associated with the free iron accumulation and mitochondrial dysfunction. DOX can provoke ferroptosis, iron-dependent cell death driven by the membrane damage. The mitochondrial permeability transition pore (MPTP) is considered as a common pathway leading to the development of apoptosis, necrosis, and, possibly, ferroptosis. The influence of DOX on the Ca2+ -induced opening of MPTP in the presence of iron has not yet been studied. Objective: The study was conducted on isolated liver and heart mitochondria. MPTP and succinate-ubiquinone oxidoreductase were studied as targets of DOX in mitochondria-dependent ferroptosis. Methods: The study was conducted on isolated mitochondria of the liver and heart. Changes of threshold calcium concentrations required for MPTP opening were measured by a Ca2+ selective electrode, mitochondrial membrane potential was registered by tetraphenylphosphonium (TPP+)-selective electrode, and mitochondrial swelling was recorded as a decrease in absorbance at 540 nm. The activity of succinate dehydrogenase (SDH) was determined by the reduction of the electron acceptor DCPIP. Conclusion: MPTP and the respiratory complex II are identified as the main targets of the iron-dependent action of DOX on the isolated mitochondria. All MPTP protectors tested abolished or weakened the effect of iron and a complex of iron with DOX on Ca2+ -induced MPTP opening, acting in different stages of MPTP activation. These data open new approaches to the modulation of the toxic influence of DOX on mitochondria with the aim to reduce their dysfunction

Abstract 321: Obesity Causes Enhanced Sensitivity Of The Mitochondrial Permeability Transition Pore

2014 ◽  
Vol 115 (suppl_1) ◽  
Author(s):  
Judith Bernal-Ramírez ◽  
Adriana Riojas-Hernández ◽  
Flor E Morales-Marroquín ◽  
Elvía M Domínguez-Barragán ◽  
David Rodríguez-Mier ◽  
...  
Keyword(s):  
Cell Death ◽  
Cardiac Dysfunction ◽  
Mitochondrial Permeability Transition Pore ◽  
Mitochondrial Permeability Transition ◽  
Permeability Transition Pore ◽  
Permeability Transition ◽  
H2o2 Production ◽  
Mitochondrial Permeability ◽  
Removal Capacity ◽  
Mptp Opening

Several mechanisms have been implicated in heart failure (HF) development due to obesity, including altered Ca2+ homeostasis and mitochondrial increased reactive oxygen species (ROS). Besides their metabolic role, mitochondria are important cell death regulators, since their disruption induces apoptosis. The mitochondrial permeability transition pore (MPTP) formation is key in this process. Ca2+ and ROS are known inducers of MPTP, and mitochondria are the main ROS generators. However, it has not been demonstrated that MPTP formation is involved in cardiac cell death due to obesity. Therefore, the aim of this work was to determine whether Ca2+ alterations and/or MPTP opening underlie cardiac dysfunction. We used obese Zucker fa/fa rats (32 weeks old), displaying concentric hypertrophy and cardiac dysfunction. We measured: i) Systolic and diastolic Ca2+ signaling in isolated myocytes, in basal conditions and upon β-adrenergic stimulation (β-AS), and ii) in vitro mitochondrial function: respiration, ROS production and MPTP opening. We found that the main alteration in Ca2+ signaling in fa/fa myocytes was a decrease in SERCA Ca2+ removal capacity, since Ca2+ transient amplitude and spark frequency were unchanged. Furthermore, in fa/fa myocytes, β-AS response was preserved. On the other hand, fa/fa mitochondria respiration, in state 3 decreased, but was unchanged in state 4, when glutamate/malate were used as substrate, resulting in an small decrease in respiratory control. In addition, fa/fa mitochondria were more sensitive to MPTP opening, induced by Ca2+ and carboxyatractiloside (CAT). Moreover, fa/fa mitochondria showed increased H2O2 production, and in exposed thiol groups in the adenine nucleotide translocase, a regulatory MPTP component. Since Ca2+ signaling is relatively normal in fa/fa cells, it does not seem to be the main contributor to the cardiac contractile dysfunction. However, given that fa/fa mitochondria showed decrease respiratory performance, were more susceptible to MPTP opening, and showed enhanced H2O2 production. We conclude that fa/fa mitochondria were more vulnerable to enhanced oxidative stress, causing MPTP opening, which could be exacerbated by SERCA slower Ca2+ removal capacity, leading to myocyte apoptosis.

Silencing of cardiac mitochondrial NHE1 prevents mitochondrial permeability transition pore opening

2011 ◽  
Vol 300 (4) ◽  
pp. H1237-H1251 ◽  
Author(s):  
María C. Villa-Abrille ◽  
Eugenio Cingolani ◽  
Horacio E. Cingolani ◽  
Bernardo V. Alvarez
Keyword(s):  
Mitochondrial Permeability Transition Pore ◽  
Mitochondrial Permeability Transition ◽  
Ischemia Reperfusion ◽  
Permeability Transition Pore ◽  
Permeability Transition ◽  
Mitochondrial Swelling ◽  
Heart Mitochondria ◽  
Rat Cardiomyocytes ◽  
Mitochondrial Permeability ◽  
Mptp Opening

Inhibition of Na+/H+ exchanger 1 (NHE1) reduces cardiac ischemia-reperfusion (I/R) injury and also cardiac hypertrophy and failure. Although the mechanisms underlying these NHE1-mediated effects suggest delay of mitochondrial permeability transition pore (MPTP) opening, and reduction of mitochondrial-derived superoxide production, the possibility of NHE1 blockade targeting mitochondria has been incompletely explored. A short-hairpin RNA sequence mediating specific knock down of NHE1 expression was incorporated into a lentiviral vector (shRNA-NHE1) and transduced in the rat myocardium. NHE1 expression of mitochondrial lysates revealed that shRNA-NHE1 transductions reduced mitochondrial NHE1 (mNHE1) by ∼60%, supporting the expression of NHE1 in mitochondria membranes. Electron microscopy studies corroborate the presence of NHE1 in heart mitochondria. Immunostaining of rat cardiomyocytes also suggests colocalization of NHE1 with the mitochondrial marker cytochrome c oxidase. To examine the functional role of mNHE1, mitochondrial suspensions were exposed to increasing concentrations of CaCl2 to induce MPTP opening and consequently mitochondrial swelling. shRNA-NHE1 transduction reduced CaCl2-induced mitochondrial swelling by 64 ± 4%. Whereas the NHE1 inhibitor HOE-642 (10 μM) decreased mitochondrial Ca2+-induced swelling in rats transduced with nonsilencing RNAi (37 ± 6%), no additional HOE-642 effects were detected in mitochondria from rats transduced with shRNA-NHE1. We have characterized the expression and function of NHE1 in rat heart mitochondria. Because mitochondria from rats injected with shRNA-NHE1 present a high threshold for MPTP formation, the beneficial effects of NHE1 inhibition in I/R resulting from mitochondrial targeting should be considered.

scholarly journals SPG7 targets the m-AAA protease complex to process MCU for uniporter assembly, Ca2+ influx, and regulation of mitochondrial permeability transition pore opening

2019 ◽  
Vol 294 (28) ◽  
pp. 10807-10818 ◽  
Author(s):  
Stephen Hurst ◽  
Ariele Baggett ◽  
Gyorgy Csordas ◽  
Shey-Shing Sheu
Keyword(s):  
Mitochondrial Permeability Transition Pore ◽  
Mitochondrial Permeability Transition ◽  
Permeability Transition Pore ◽  
Permeability Transition ◽  
Cyclophilin D ◽  
Spastic Paraplegia ◽  
Mitochondrial Permeability ◽  
Mptp Opening ◽  
Permeability Transition Pore Opening ◽  
Pore Opening

The mitochondrial matrix ATPase associated with diverse cellular activities (m-AAA) protease spastic paraplegia 7 (SPG7) has been recently implicated as either a negative or positive regulatory component of the mitochondrial permeability transition pore (mPTP) by two research groups. To address this controversy, we investigated possible mechanisms that explain the discrepancies between these two studies. We found that loss of the SPG7 gene increased resistance to Ca2+-induced mPTP opening. However, this occurs independently of cyclophilin D (cyclosporine A insensitive) rather it is through decreased mitochondrial Ca2+ concentrations and subsequent adaptations mediated by impaired formation of functional mitochondrial Ca2+ uniporter complexes. We found that SPG7 directs the m-AAA complex to favor association with the mitochondrial Ca2+ uniporter (MCU) and MCU processing regulates higher order MCU-complex formation. The results suggest that SPG7 does not constitute a core component of the mPTP but can modulate mPTP through regulation of the basal mitochondrial Ca2+ concentration.

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