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Boyman L, Coleman AK, Zhao G, Wescott AP, Joca HC, Greiser BM, Karbowski M, Ward CW, Lederer WJ. Dynamics of the mitochondrial permeability transition pore: Transient and permanent opening events. Arch Biochem Biophys 2019; 666:31-39. [PMID: 30930285 PMCID: PMC6538282 DOI: 10.1016/j.abb.2019.03.016] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Revised: 03/19/2019] [Accepted: 03/26/2019] [Indexed: 12/11/2022]
Abstract
A gentle optical examination of the mitochondrial permeability transition pore (mPTP) opening events was carried out in isolated quiescent ventricular myocytes by tracking the inner membrane potential (ΔΨM) using TMRM (tetramethylrhodamine methyl ester). Zeiss Airyscan 880 ″super-resolution" or "high-resolution" imaging was done with very low levels of illumination (0.009% laser power). In cellular areas imaged every 9 s (ROI or regions of interest), transient depolarizations of variable amplitudes occurred at increasing rates for the first 30 min. The time to first depolarization events was 8.4 min (±1.1 SEM n = 21 cells). At longer times, essentially permanent and irreversible depolarizations occurred at an increasing fraction of all events. In other cellular areas surrounding the ROI, mitochondria were rarely illuminated (once per 5 min) and virtually no permanent depolarization events occurred for over 1 h of imaging. These findings suggest that photon stress due to the imaging itself plays an important role in the generation of both the transient mPTP opening events as well as the permanent mPTP opening events. Consistent with the evidence that photon "stress" in mitochondria loaded with virtually any photon absorbing substance, generates reactive oxygen species (ROS) [1-5], we show that cyclosporine-A (CsA, 10 μM) and the antioxidant n-acetyl cysteine (NAC, 10 mM), reduced the number of events by 80% and 93% respectively. Furthermore, CsA and NAC treatment led to the virtual disappearance of permanent depolarization events. Nevertheless, all transient depolarization events in any condition (control, CsA and NAC) appeared to repolarize with a similar half-time of 30 ± 6 s (n = 478) at 37 °C. Further experiments showed quantitatively similar results in cerebral vascular smooth muscle cells, using a different confocal system, and different photon absorbing reagent (TMRE; tetramethylrhodamine ethyl ester). In these experiments, using modest power (1% laser power) transient depolarization events were seen in only 8 out of 23 cells while with higher power (8%), all cells showed transient events, which align with the level of photon stress being the driver of the effect. Together, our findings suggest that photon-induced ROS is sufficient to cause depolarization events of individual mitochondria in quiescent cells; without electrical or mechanical activity to stimulates mitochondrial metabolism, and without raising the mitochondrial matrix Ca2+. In a broad context, these findings neither support nor deny the relevance or occurrence of ΔΨM depolarization events in specific putatively physiologic mitochondrial behaviors such as MitoFlashes [6,7] or MitoWinks [8]. Instead, our findings raise a caution with regards to the physiological and pathophysiological functions attributed to singular ΔΨM depolarization events when those functions are investigated using photon absorbing substances. Nevertheless, using photon stress as a tool ("Optical Stress-Probe"), we can extract information on the activation, reversibility, permanency and kinetics of mitochondrial depolarization. These data may provide new information on mPTP, help identify the mPTP protein complex, and establish the physiological function of the mPTP protein complex and their links to MitoFlashes and MitoWinks.
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Affiliation(s)
- Liron Boyman
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, 111 Penn Street, Baltimore, MD, 21201, USA; Department of Physiology, University of Maryland School of Medicine, 111 Penn Street, Baltimore, MD, 21201, USA.
| | - Andrew K Coleman
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, 111 Penn Street, Baltimore, MD, 21201, USA; Department of Physiology, University of Maryland School of Medicine, 111 Penn Street, Baltimore, MD, 21201, USA
| | - Guiling Zhao
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, 111 Penn Street, Baltimore, MD, 21201, USA; Department of Physiology, University of Maryland School of Medicine, 111 Penn Street, Baltimore, MD, 21201, USA
| | - Andrew P Wescott
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, 111 Penn Street, Baltimore, MD, 21201, USA; Department of Physiology, University of Maryland School of Medicine, 111 Penn Street, Baltimore, MD, 21201, USA
| | - Humberto C Joca
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, 111 Penn Street, Baltimore, MD, 21201, USA; Department of Physiology, University of Maryland School of Medicine, 111 Penn Street, Baltimore, MD, 21201, USA
| | - B Maura Greiser
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, 111 Penn Street, Baltimore, MD, 21201, USA; Department of Physiology, University of Maryland School of Medicine, 111 Penn Street, Baltimore, MD, 21201, USA
| | - Mariusz Karbowski
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, 111 Penn Street, Baltimore, MD, 21201, USA; Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, 111 Penn Street, Baltimore, MD, 21201, USA
| | - Chris W Ward
- Department of Orthopedics, University of Maryland School of Medicine, Baltimore, MD, USA
| | - W J Lederer
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, 111 Penn Street, Baltimore, MD, 21201, USA; Department of Physiology, University of Maryland School of Medicine, 111 Penn Street, Baltimore, MD, 21201, USA.
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Abstract
Mitochondria play a crucial role in programmed cell death (PCD) in plants. In most cases of mitochondria-dependent PCD, cytochrome c (Cyt c) released from mitochondria due to the opening of mitochondrial permeability transition pore (MPTP) and the activation of caspase-like proteases. Here we describe the analytic methods of mitochondrial markers of PCD including mitochondria isolation, mitochondrial membrane permeability, mitochondrial inner membrane potential, Cytc release, ATP, and mitochondrial reactive oxygen species (ROS).
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Affiliation(s)
- Dong Xiao
- College of Agronomy, Guangxi University, Nanning, Guangxi, People's Republic of China
| | - Huyi He
- College of Agronomy, Guangxi University, Nanning, Guangxi, People's Republic of China
| | - Wenjing Huang
- College of Agronomy, Guangxi University, Nanning, Guangxi, People's Republic of China
| | - Thet Lwin Oo
- College of Agronomy, Guangxi University, Nanning, Guangxi, People's Republic of China
| | - Aiqin Wang
- College of Agronomy, Guangxi University, Nanning, Guangxi, People's Republic of China
| | - Long-Fei He
- College of Agronomy, Guangxi University, Nanning, Guangxi, People's Republic of China.
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Rogers C, Davis B, Neufer PD, Murphy MP, Anderson EJ, Robidoux J. A transient increase in lipid peroxidation primes preadipocytes for delayed mitochondrial inner membrane permeabilization and ATP depletion during prolonged exposure to fatty acids. Free Radic Biol Med 2014; 67:330-41. [PMID: 24269897 PMCID: PMC3935619 DOI: 10.1016/j.freeradbiomed.2013.11.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/08/2013] [Revised: 10/29/2013] [Accepted: 11/12/2013] [Indexed: 12/22/2022]
Abstract
Preadipocytes are periodically subjected to fatty acid (FA) concentrations that are potentially cytotoxic. We tested the hypothesis that prolonged exposure of preadipocytes of human origin to a physiologically relevant mix of FAs leads to mitochondrial inner membrane (MIM) permeabilization and ultimately to mitochondrial crisis. We found that exposure of preadipocytes to FAs led to progressive cyclosporin A-sensitive MIM permeabilization, which in turn caused a reduction in MIM potential, oxygen consumption, and ATP synthetic capacity and, ultimately, death. Additionally, we showed that FAs induce a transient increase in intramitochondrial reactive oxygen species (ROS) and lipid peroxide production, lasting roughly 30 and 120min for the ROS and lipid peroxides, respectively. MIM permeabilization and its deleterious consequences including mitochondrial crisis and cell death were prevented by treating the cells with the mitochondrial FA uptake inhibitor etomoxir, the mitochondrion-selective superoxide and lipid peroxide antioxidants MitoTempo and MitoQ, or the lipid peroxide and reactive carbonyl scavenger l-carnosine. FAs also promoted a delayed oxidative stress phase. However, the beneficial effects of etomoxir, MitoTempo, and l-carnosine were lost by delaying the treatment by 2h, suggesting that the initial phase was sufficient to prime the cells for the delayed MIM permeabilization and mitochondrial crisis. It also suggested that the second ROS production phase is a consequence of this loss in mitochondrial health. Altogether, our data suggest that approaches designed to diminish intramitochondrial ROS or lipid peroxide accumulation, as well as MIM permeabilization, are valid mechanism-based therapeutic avenues to prevent the loss in preadipocyte metabolic fitness associated with prolonged exposure to elevated FA levels.
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Affiliation(s)
- Carlyle Rogers
- Department of Pharmacology and Toxicology, East Carolina University, Greenville, NC 27834, USA
| | - Barbara Davis
- Department of Pharmacology and Toxicology, East Carolina University, Greenville, NC 27834, USA
| | - P Darrell Neufer
- Department of Physiology, East Carolina University, Greenville, NC 27834, USA; Department of Kinesiology, East Carolina University, Greenville, NC 27834, USA; East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC 27834, USA
| | - Michael P Murphy
- MRC Mitochondrial Biology Unit, Wellcome Trust/MRC Building, Cambridge CB2 0XY, UK
| | - Ethan J Anderson
- Department of Pharmacology and Toxicology, East Carolina University, Greenville, NC 27834, USA; Department of Kinesiology, East Carolina University, Greenville, NC 27834, USA; East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC 27834, USA
| | - Jacques Robidoux
- Department of Pharmacology and Toxicology, East Carolina University, Greenville, NC 27834, USA; East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC 27834, USA.
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