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Pan T, Yang B, Yao S, Wang R, Zhu Y. Exploring the multifaceted role of adenosine nucleotide translocase 2 in cellular and disease processes: A comprehensive review. Life Sci 2024; 351:122802. [PMID: 38857656 DOI: 10.1016/j.lfs.2024.122802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2024] [Revised: 05/04/2024] [Accepted: 06/04/2024] [Indexed: 06/12/2024]
Abstract
Adenosine nucleotide translocases (ANTs) are a family of proteins abundant in the inner mitochondrial membrane, primarily responsible for shuttling ADP and ATP across the mitochondrial membrane. Additionally, ANTs are key players in balancing mitochondrial energy metabolism and regulating cell death. ANT2 isoform, highly expressed in undifferentiated and proliferating cells, is implicated in the development and drug resistance of various tumors. We conduct a detailed analysis of the potential mechanisms by which ANT2 may influence tumorigenesis and drug resistance. Notably, the significance of ANT2 extends beyond oncology, with roles in non-tumor cell processes including blood cell development, gastrointestinal motility, airway hydration, nonalcoholic fatty liver disease, obesity, chronic kidney disease, and myocardial development, making it a promising therapeutic target for multiple pathologies. To better understand the molecular mechanisms of ANT2, this review summarizes the structural properties, expression patterns, and basic functions of the ANT2 protein. In particular, we review and analyze the controversy surrounding ANT2, focusing on its role in transporting ADP/ATP across the inner mitochondrial membrane, its involvement in the composition of the mitochondrial permeability transition pore, and its participation in apoptosis.
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Affiliation(s)
- Tianhui Pan
- Laboratory of Gastroenterology, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, Zhejiang 310009, PR China
| | - Bin Yang
- Laboratory of Gastroenterology, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, Zhejiang 310009, PR China
| | - Sheng Yao
- Laboratory of Gastroenterology, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, Zhejiang 310009, PR China
| | - Rui Wang
- Laboratory of Gastroenterology, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, Zhejiang 310009, PR China
| | - Yongliang Zhu
- Laboratory of Gastroenterology, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, Zhejiang 310009, PR China.
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Liu R, Liu R, Song G, Li Q, Cui Z, Long Y. Mitochondria Dysfunction and Cell Apoptosis Limit Resistance of Nile Tilapia (Oreochromis niloticus) to Lethal Cold Stress. Animals (Basel) 2022; 12:ani12182382. [PMID: 36139242 PMCID: PMC9495169 DOI: 10.3390/ani12182382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Revised: 09/09/2022] [Accepted: 09/09/2022] [Indexed: 11/16/2022] Open
Abstract
Simple Summary Sensitivity of Nile tilapia (Oreochromis niloticus) to cold stress represents a major concern for both aquaculture and theoretical study; however, the cellular and molecular mechanisms determining cold susceptibility of it remain largely unknown. In this study, we first estimated the median survival time of juvenile Nile tilapia under exposure to lethal cold stress (12 °C). The fish were classified as cold-sensitive or cold-tolerant based on their behavioral manifestation after exposed to 12 °C for 3 days. Subsequently, histological, biochemical and gene expression analyses were performed for the fish with different cold resistance to explore the cellular and molecular events underlying cold susceptibility of Nile tilapia. We found that exposure of Nile tilapia to lethal cold stress caused systemic tissue structure changes, mitochondrial swelling and dysfunction, induction of apoptosis and endoplasmic reticulum (ER) stress-related genes and cell apoptosis. The extent of these adverse cellular and molecular events determines an individual’s ability to survive cold stress. Our data indicate that mitochondria dysfunction and mitochondria-mediated cell apoptosis are the main factors limiting Nile tilapia’s cold resistance. Abstract Inability of Nile tilapia (Oreochromis niloticus) to withstand cold stress represents a major economic concern, which restricts the culture area, limits the growing period and even results in mass mortality in cold seasons. However, the cellular and molecular mechanisms determining cold susceptibility of Nile tilapia remain largely unknown. In this study, we characterized the ability of juvenile Nile tilapia to survive lethal cold stress (12 °C) and the median survival time (LT50) of the experimental fish under exposure to 12 °C cold stress was estimated as 3.14 d. After being exposed to 12 °C for 3 d, the survivors that lost equilibrium (LE) and those that swam normally (NO) were regarded as cold-sensitive and cold-tolerant, respectively. The untreated (Ctrl), NO and LE fish were subjected to histological, biochemical and gene expression analyses to explore the cellular and molecular events underlying cold susceptibility of Nile tilapia. Exposure of Nile tilapia to lethal cold stress caused systemic tissue structure changes, mitochondrial swelling and dysfunction, induction of apoptosis and endoplasmic reticulum (ER) stress-related genes and cell apoptosis. The extent of these adverse cellular and molecular events determines an individual’s ability to survive cold stress. Our data indicate that mitochondria dysfunction and mitochondria-mediated cell apoptosis are the main factors limiting Nile tilapia’s cold resistance.
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Affiliation(s)
- Ran Liu
- College of Fisheries and Life Science, Dalian Ocean University, Dalian 116023, China
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
| | - Renyan Liu
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
- College of Advanced Agricultural Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Guili Song
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
| | - Qing Li
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
| | - Zongbin Cui
- Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, State Key Laboratory of Applied Microbiology Southern China, Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou 510070, China
| | - Yong Long
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
- Correspondence: ; Tel.: +86-27-68780100
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Aklima J, Onchaiya S, Saotome T, Velmurugan P, Motoichi T, Naima J, Kuroda Y, Ohta Y. Direct Analysis of Mitochondrial Damage Caused by Misfolded/Destabilized Proteins. Int J Mol Sci 2022; 23:ijms23179881. [PMID: 36077279 PMCID: PMC9456338 DOI: 10.3390/ijms23179881] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 08/25/2022] [Accepted: 08/26/2022] [Indexed: 11/16/2022] Open
Abstract
Protein quality control is essential for cellular homeostasis. In this study, we examined the effect of improperly folded proteins that do not form amyloid fibrils on mitochondria, which play important roles in ATP production and cell death. First, we prepared domain 3 of the dengue envelope protein in wild type and four mutants with widely different biophysical properties in misfolded/aggregated or destabilized states. The effects of the different proteins were detected using fluorescence microscopy and Western blotting, which revealed that three of the five proteins disrupted both inner and outer membrane integrity, while the other two proteins, including the wild type, did not. Next, we examined the common characteristics of the proteins that displayed toxicity against mitochondria by measuring oligomer size, molten globule-like properties, and thermal stability. The common feature of all three toxic proteins was thermal instability. Therefore, our data strongly suggest that thermally unstable proteins generated in the cytosol can cause cellular damage by coming into direct contact with mitochondria. More importantly, we revealed that this damage is not amyloid-specific.
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Affiliation(s)
- Jannatul Aklima
- Division of Biotechnology and Life Sciences, Tokyo University of Agriculture and Technology, 2-24-16 Nakacho, Koganei, Tokyo 184-8588, Japan
- Department of Biochemistry and Molecular Biology, University of Chittagong, Chittagong 4331, Bangladesh
| | - Sawaros Onchaiya
- Division of Biotechnology and Life Sciences, Tokyo University of Agriculture and Technology, 2-24-16 Nakacho, Koganei, Tokyo 184-8588, Japan
| | - Tomonori Saotome
- Division of Biotechnology and Life Sciences, Tokyo University of Agriculture and Technology, 2-24-16 Nakacho, Koganei, Tokyo 184-8588, Japan
- Department of Bioengineering, Nagaoka University of Technology, Niigata 940-2188, Japan
| | - Punitha Velmurugan
- Division of Biotechnology and Life Sciences, Tokyo University of Agriculture and Technology, 2-24-16 Nakacho, Koganei, Tokyo 184-8588, Japan
| | - Taihei Motoichi
- Division of Biotechnology and Life Sciences, Tokyo University of Agriculture and Technology, 2-24-16 Nakacho, Koganei, Tokyo 184-8588, Japan
| | - Jannatul Naima
- Division of Biotechnology and Life Sciences, Tokyo University of Agriculture and Technology, 2-24-16 Nakacho, Koganei, Tokyo 184-8588, Japan
| | - Yutaka Kuroda
- Division of Biotechnology and Life Sciences, Tokyo University of Agriculture and Technology, 2-24-16 Nakacho, Koganei, Tokyo 184-8588, Japan
| | - Yoshihiro Ohta
- Division of Biotechnology and Life Sciences, Tokyo University of Agriculture and Technology, 2-24-16 Nakacho, Koganei, Tokyo 184-8588, Japan
- Correspondence:
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Yoneda M, Aklima J, Ohsawa I, Ohta Y. Effects of proton pumping on the structural rigidity of cristae in mitochondria. Arch Biochem Biophys 2022; 720:109172. [PMID: 35276212 DOI: 10.1016/j.abb.2022.109172] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Revised: 03/06/2022] [Accepted: 03/07/2022] [Indexed: 02/08/2023]
Abstract
Mitochondria change their morphology and inner membrane structure depending on their activity. Since mitochondrial activity also depends on their structure, it is important to elucidate the interrelationship between the activity and structure of mitochondria. However, the mechanism by which mitochondrial activity affects the structure of cristae, the folded structure of the inner membrane, is not well understood. In this study, the effect of the mitochondrial activity on the cristae structure was investigated by examining the structural rigidity of cristae. Taking advantage of the fact that unfolding of cristae induces mitochondrial swelling, we investigated the relationship between mitochondrial activity and the susceptibility to swelling. The swelling of individual isolated mitochondria exposed to a hypotonic solution was observed with an optical microscope. The presence of respiratory substrates (malate and glutamate) increased the percentage of mitochondria that underwent swelling, and the further addition of rotenone or KCN (inhibitors of proton pumps) reversed the increase. In the absence of respiratory substrates, acidification of the buffer surrounding the mitochondria also increased the percentage of swollen mitochondria. These observations suggest that acidification of the outer surface of inner membranes, especially intracristal space, by proton translocation from the matrix to the intracristal space, decreases the structural rigidity of the cristae. This interpretation was verified by the observation that ADP or CCCP, which induces proton re-entry to the matrix, suppressed the mitochondrial swelling in the presence of respiratory substrates. The addition of CCCP to the cells induced a morphological change in mitochondria from an initial elongated structure to a largely curved structure at pH 7.4, but there were no morphological changes when the pH of the cytosol dropped to 6.2. These results suggest that a low pH in the intracristal space may be helpful in maintaining the elongated structure of mitochondria. The present study shows that proton pumping by the electron transfer chain is the mechanism underlying mitochondrial morphology and the flexibility of cristae structure.
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Affiliation(s)
- Mayu Yoneda
- Division of Biotechnology and Life Sciences, Tokyo University of Agriculture and Technology, 2-24-16 Nakacho, Koganei, Tokyo, 184-8588, Japan
| | - Jannatul Aklima
- Division of Biotechnology and Life Sciences, Tokyo University of Agriculture and Technology, 2-24-16 Nakacho, Koganei, Tokyo, 184-8588, Japan; Department of Biochemistry & Molecular Biology, University of Chittagong, Chittagong, 4331, Bangladesh
| | - Ikuroh Ohsawa
- Biological Process of Aging, Tokyo Metropolitan Institute of Gerontology, Itabashi, Tokyo, 173-0015, Japan
| | - Yoshihiro Ohta
- Division of Biotechnology and Life Sciences, Tokyo University of Agriculture and Technology, 2-24-16 Nakacho, Koganei, Tokyo, 184-8588, Japan.
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Boyenle ID, Oyedele AK, Ogunlana AT, Adeyemo AF, Oyelere FS, Akinola OB, Adelusi TI, Ehigie LO, Ehigie AF. Targeting the mitochondrial permeability transition pore for drug discovery: Challenges and opportunities. Mitochondrion 2022; 63:57-71. [PMID: 35077882 DOI: 10.1016/j.mito.2022.01.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Revised: 12/22/2021] [Accepted: 01/17/2022] [Indexed: 12/29/2022]
Abstract
Several drug targets have been amenable to drug discovery pursuit not until the characterization of the mitochondrial permeability transition pore (MPTP), a pore with an undefined molecular identity that forms on the inner mitochondrial membrane upon mitochondrial permeability transition (MPT) under the influence of calcium overload and oxidative stress. The opening of the pore which is presumed to cause cell death in certain human diseases also has implications under physiological parlance. Different models for this pore have been postulated following its first identification in the last six decades. The mitochondrial community has witnessed many protein candidates such as; voltage-dependent anion channel (VDAC), adenine nucleotide translocase (ANT), Mitochondrial phosphate carrier (PiC), Spastic Paralegin (SPG7), disordered proteins, and F1Fo ATPase. However, genetic studies have cast out most of these candidates with only F1Fo ATPase currently under intense argument. Cyclophilin D (CyPD) remains the widely accepted positive regulator of the MPTP known to date, but no drug candidate has emerged as its inhibitor, raising concern issues for therapeutics. Thus, in this review, we discuss various models of MPTP reported with the hope of stimulating further research in this field. We went beyond the classical description of the MPTP to ascribe a 'two-edged sword property' to the pore for therapeutic function in human disease because its inhibition and activation have pharmacological relevance. We suggested putative proteins upstream to CyPD that can regulate its activity and prevent cell deaths in neurodegenerative disease and ischemia-reperfusion injury.
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Affiliation(s)
- Ibrahim Damilare Boyenle
- Membrane Biochemistry and Biophysics Research Laboratory, Department of Biochemistry, Ladoke Akintola University of Technology, Ogbomoso, Nigeria; Computational Biology/Drug Discovery Laboratory, Department of Biochemistry, Ladoke Akintola University of Technology, Ogbomoso, Nigeria
| | - Abdulquddus Kehinde Oyedele
- Computational Biology/Drug Discovery Laboratory, Department of Biochemistry, Ladoke Akintola University of Technology, Ogbomoso, Nigeria
| | - Abdeen Tunde Ogunlana
- Computational Biology/Drug Discovery Laboratory, Department of Biochemistry, Ladoke Akintola University of Technology, Ogbomoso, Nigeria
| | - Aishat Folashade Adeyemo
- Membrane Biochemistry and Biophysics Research Laboratory, Department of Biochemistry, Ladoke Akintola University of Technology, Ogbomoso, Nigeria
| | | | - Olateju Balikis Akinola
- Membrane Biochemistry and Biophysics Research Laboratory, Department of Biochemistry, Ladoke Akintola University of Technology, Ogbomoso, Nigeria
| | - Temitope Isaac Adelusi
- Computational Biology/Drug Discovery Laboratory, Department of Biochemistry, Ladoke Akintola University of Technology, Ogbomoso, Nigeria
| | - Leonard Ona Ehigie
- Computational Biology/Drug Discovery Laboratory, Department of Biochemistry, Ladoke Akintola University of Technology, Ogbomoso, Nigeria
| | - Adeola Folasade Ehigie
- Membrane Biochemistry and Biophysics Research Laboratory, Department of Biochemistry, Ladoke Akintola University of Technology, Ogbomoso, Nigeria.
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Comparative Analysis of the APOL1 Variants in the Genetic Landscape of Renal Carcinoma Cells. Cancers (Basel) 2022; 14:cancers14030733. [PMID: 35159001 PMCID: PMC8833631 DOI: 10.3390/cancers14030733] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Revised: 01/11/2022] [Accepted: 01/26/2022] [Indexed: 11/21/2022] Open
Abstract
Simple Summary Renal cell carcinoma (RCC) occurs at higher frequency in individuals of African ancestry, with well-recorded documentation in this community. This is most prominent in the context of chronic kidney disease. In turn, many forms of progressive chronic kidney disease are more common in populations of Sub-Saharan African ancestry. This disparity has been attributed to well-defined allelic variants and has risen in the parental populations to high frequency under evolutionary pressure. Mechanisms of increased kidney disease risk and cell injury, causally associated with these APOL1 gene variants, have been extensively studied. Most studies have compared the effects of ectopic overexpression of the parental non-risk APOL1 with the mutated risk variants in cellular and organismal platforms. In the current study, we have used CRISPR/Cas9 genetic engineering to knock out or modify the sequence of endogenous APOL1 in RCC to mimic and examine the effects of these naturally occurring kidney disease risk allelic variants. Remarkably, these modifications to endogenous APOL1 genes in RCC resulted in a set of prominent effects on mitochondrial integrity and metabolic pathways and disrupted tumorigenesis. These findings both clarify pathways of cell injury of APOL1 risk variants in cells of kidney origin and motivate further studies to examine the potential central role of APOL1 in the pathogenesis of renal cell carcinoma and its relation to chronic kidney disease in genotypically at-risk African ancestry individuals. Abstract Although the relative risk of renal cell carcinoma associated with chronic kidney injury is particularly high among sub-Saharan African ancestry populations, it is unclear yet whether the APOL1 gene risk variants (RV) for kidney disease additionally elevate this risk. APOL1 G1 and G2 RV contribute to increased risk for kidney disease in black populations, although the disease mechanism has still not been fully deciphered. While high expression levels of all three APOL1 allelic variants, G0 (the wild type allele), G1, and G2 are injurious to normal human cells, renal carcinoma cells (RCC) naturally tolerate inherent high expression levels of APOL1. We utilized CRISPR/Cas9 gene editing to generate isogenic RCC clones expressing APOL1 G1 or G2 risk variants on a similar genetic background, thus enabling a reliable comparison between the phenotypes elicited in RCC by each of the APOL1 variants. Here, we demonstrate that knocking in the G1 or G2 APOL1 alleles, or complete elimination of APOL1 expression, has major effects on proliferation capacity, mitochondrial morphology, cell metabolism, autophagy levels, and the tumorigenic potential of RCC cells. The most striking effect of the APOL1 RV effect was demonstrated in vivo by the complete abolishment of tumor growth in immunodeficient mice. Our findings suggest that, in contrast to the WT APOL1 variant, APOL1 RV are toxic for RCC cells and may act to suppress cancer cell growth. We conclude that the inherent expression of non-risk APOL1 G0 is required for RCC tumorigenicity. RCC cancer cells can hardly tolerate increased APOL1 risk variants expression levels as opposed to APOL1 G0.
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7
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Kruglov AG, Kharechkina ES, Nikiforova AB, Odinokova IV, Kruglova SA. Dynamics of the permeability transition pore size in isolated mitochondria and mitoplasts. FASEB J 2021; 35:e21764. [PMID: 34245631 DOI: 10.1096/fj.202100596r] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 05/28/2021] [Accepted: 06/14/2021] [Indexed: 11/11/2022]
Abstract
The size of the permeability transition pore (PTP) is accepted to be ≤1.5 kDa. However, different authors reported values from 650 to 4000 Da. The present study is focused on the variability of the average PTP size in and between mitochondrial samples, its reasons and relations with PTP dynamics. Measurement of PTP size by the standard method revealed its 500 Da-range variability between mitochondrial samples. Sequential measurements in the same sample showed that the PTP size tends to grow with time and Ca2+ concentration. Selective damage to the mitochondrial outer membrane (MOM) reduced the apparent PTP size by ~200-300 Da. Hypotonic and hypertonic osmotic shock and partial removal of the MOM with the preservation of the mitochondrial inner membrane intactness decreased the apparent PTP size by ~50%. We developed an approach to continuous monitoring of the PTP size that revealed the existence of stable PTP states with different pore sizes (~700, 900-1000, ~1350, 1700-1800, and 2100-2200 Da) and transitions between them. The transitions were accelerated by elevating the Ca2+ concentration, temperature, and osmotic pressure, which demonstrates an increased capability of PTP to accommodate to large molecules (plasticity). Cyclosporin A inhibited the transitions between states. The analysis of PTP size dynamics in osmotically shocked mitochondria and mitoplasts confirmed the importance of the MOM for the stabilization of PTP structure. Thus, this approach provides a new tool for PTP studies and the opportunity to reconcile data on the PTP size and mitochondrial megachannel conductance.
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Affiliation(s)
- Alexey G Kruglov
- Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino, Russia
| | - Ekaterina S Kharechkina
- Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino, Russia
| | - Anna B Nikiforova
- Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino, Russia
| | - Irina V Odinokova
- Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino, Russia
| | - Svetlana A Kruglova
- Institute of Basic Biological Problems, Russian Academy of Sciences, Pushchino, Russia
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Aklima J, Onojima T, Kimura S, Umiuchi K, Shibata T, Kuraoka Y, Oie Y, Suganuma Y, Ohta Y. Effects of Matrix pH on Spontaneous Transient Depolarization and Reactive Oxygen Species Production in Mitochondria. Front Cell Dev Biol 2021; 9:692776. [PMID: 34277637 PMCID: PMC8278022 DOI: 10.3389/fcell.2021.692776] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Accepted: 05/26/2021] [Indexed: 01/28/2023] Open
Abstract
Reactive oxygen species (ROS) oxidize surrounding molecules and thus impair their functions. Since mitochondria are a major source of ROS, suppression of ROS overproduction in the mitochondria is important for cells. Spontaneous transient depolarization of individual mitochondria is a physiological phenomenon widely observed from plants to mammals. Mitochondrial uncoupling can reduce ROS production; therefore, it is conceivable that transient depolarization could reduce ROS production. However, transient depolarization has been observed with increased ROS production. Therefore, the exact contribution of transient depolarization to ROS production has not been elucidated. In this study, we examined how the spontaneous transient depolarization occurring in individual mitochondria affected ROS production. When the matrix pH increased after the addition of malate or exposure of the isolated mitochondria to a high-pH buffer, transient depolarization was stimulated. Similar stimulation by an increased matrix pH was also observed in the mitochondria in intact H9c2 cells. Modifying the mitochondrial membrane potential and matrix pH by adding K+ in the presence of valinomycin, a K+ ionophore, clarified that an increase in the matrix pH is a major cause of ROS generation. When we added ADP in the presence of oligomycin to suppress the transient depolarization without decreasing the matrix pH, we observed the suppression of mitochondrial respiration, increased matrix pH, and enhanced ROS production. Based on these results, we propose a model where spontaneous transient depolarization occurs during increased proton influx through proton channels opened by increased matrix pH, leading to the suppression of ROS production. This study improves our understanding of mitochondrial behavior.
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Affiliation(s)
- Jannatul Aklima
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, Koganei, Japan.,Department of Biochemistry and Molecular Biology, University of Chittagong, Chittagong, Bangladesh
| | - Takumi Onojima
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, Koganei, Japan
| | - Sawako Kimura
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, Koganei, Japan
| | - Kanji Umiuchi
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, Koganei, Japan
| | - Takahiro Shibata
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, Koganei, Japan
| | - Yusho Kuraoka
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, Koganei, Japan
| | - Yoshiki Oie
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, Koganei, Japan
| | - Yoshiki Suganuma
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, Koganei, Japan
| | - Yoshihiro Ohta
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, Koganei, Japan
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9
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Strubbe-Rivera JO, Schrad JR, Pavlov EV, Conway JF, Parent KN, Bazil JN. The mitochondrial permeability transition phenomenon elucidated by cryo-EM reveals the genuine impact of calcium overload on mitochondrial structure and function. Sci Rep 2021; 11:1037. [PMID: 33441863 PMCID: PMC7806632 DOI: 10.1038/s41598-020-80398-8] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Accepted: 12/16/2020] [Indexed: 12/19/2022] Open
Abstract
Mitochondria have a remarkable ability to uptake and store massive amounts of calcium. However, the consequences of massive calcium accumulation remain enigmatic. In the present study, we analyzed a series of time-course experiments to identify the sequence of events that occur in a population of guinea pig cardiac mitochondria exposed to excessive calcium overload that cause mitochondrial permeability transition (MPT). By analyzing coincident structural and functional data, we determined that excessive calcium overload is associated with large calcium phosphate granules and inner membrane fragmentation, which explains the extent of mitochondrial dysfunction. This data also reveals a novel mechanism for cyclosporin A, an inhibitor of MPT, in which it preserves cristae despite the presence of massive calcium phosphate granules in the matrix. Overall, these findings establish a mechanism of calcium-induced mitochondrial dysfunction and the impact of calcium regulation on mitochondrial structure and function.
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Affiliation(s)
| | - Jason R Schrad
- Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, 48824, USA
| | - Evgeny V Pavlov
- Basic Science and Craniofacial Biology, New York University, New York, NY, 10010, USA
| | - James F Conway
- Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, 15261, USA
| | - Kristin N Parent
- Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, 48824, USA
| | - Jason N Bazil
- Physiology, Michigan State University, East Lansing, MI, 48824, USA.
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10
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Fei M, Zhang L, Wang H, Zhu Y, Niu W, Tang T, Han Y. Inhibition of Cathepsin S Induces Mitochondrial Apoptosis in Glioblastoma Cell Lines Through Mitochondrial Stress and Autophagosome Accumulation. Front Oncol 2021; 10:516746. [PMID: 33425712 PMCID: PMC7787074 DOI: 10.3389/fonc.2020.516746] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Accepted: 09/30/2020] [Indexed: 12/27/2022] Open
Abstract
Cathepsin S (CTSS), a lysosomal cysteine protease, is overexpressed in various cancers, including glioblastoma (GB). A high level of CTSS is associated with tumor progression and poor outcome in GB. However, the underlying mechanisms of its role in the biological characteristics of G5B remain to be elucidated. Here, we uncovered a potential role of CTSS in the lysosomes and mitochondria of GB cells (GBCs). Downregulation of CTSS in GBCs could increase the expression of autophagy-related proteins; however, there was no significant change in p62, suggesting autophagy blockade. Moreover, inhibition of CTSS increased the expression of mitochondrial calcium uniporter (MCU) and enhanced mitochondrial Ca2+ uptake ability, causing mitochondrial Ca2+ overload, the generation of copious reactive oxygen species (ROS) and eventual mitochondrial apoptosis. Additionally, elevated damage to mitochondria exacerbated the burden of autophagy. Finally, we found that silence of MCU could alleviate the inhibition of CTSS-induced autophagosome accumulation and mitochondrial stress. Collectively, these results demonstrate that CTSS plays an important role in the process of autophagic flux and mitochondrial functions in GBCs.
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Affiliation(s)
- Maoxing Fei
- Department of Neurosurgery, Jinling Hospital, Nanjing Medical University, Nanjing, China
| | - Li Zhang
- Department of Neurosurgery, Jinling Hospital, Medical School of Nanjing University, Nanjing, China
| | - Handong Wang
- Department of Neurosurgery, Jinling Hospital, Nanjing Medical University, Nanjing, China
| | - Yihao Zhu
- Department of Neurosurgery, Jinling Hospital, Medical School of Nanjing University, Nanjing, China
| | - Wenhao Niu
- Department of Neurosurgery, Jinling Hospital, School of Medicine, Southeast University, Nanjing, China
| | - Ting Tang
- Department of Neurosurgery, Jinling Hospital, Medical School of Nanjing University, Nanjing, China
| | - Yanling Han
- Department of Neurosurgery, Jinling Hospital, Nanjing, China
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Neginskaya MA, Strubbe JO, Amodeo GF, West BA, Yakar S, Bazil JN, Pavlov EV. The very low number of calcium-induced permeability transition pores in the single mitochondrion. J Gen Physiol 2020; 152:e202012631. [PMID: 32810269 PMCID: PMC7537349 DOI: 10.1085/jgp.202012631] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Revised: 06/22/2020] [Accepted: 07/24/2020] [Indexed: 12/12/2022] Open
Abstract
Mitochondrial permeability transition (PT) is a phenomenon of stress-induced increase in nonspecific permeability of the mitochondrial inner membrane that leads to disruption of oxidative phosphorylation and cell death. Quantitative measurement of the membrane permeability increase during PT is critically important for understanding the PT's impact on mitochondrial function. The elementary unit of PT is a PT pore (PTP), a single channel presumably formed by either ATP synthase or adenine nucleotide translocator (ANT). It is not known how many channels are open in a single mitochondrion during PT, which makes it difficult to quantitatively estimate the overall degree of membrane permeability. Here, we used wide-field microscopy to record mitochondrial swelling and quantitatively measure rates of single-mitochondrion volume increase during PT-induced high-amplitude swelling. PT was quantified by calculating the rates of water flux responsible for measured volume changes. The total water flux through the mitochondrial membrane of a single mitochondrion during PT was in the range of (2.5 ± 0.4) × 10-17 kg/s for swelling in 2 mM Ca2+ and (1.1 ± 0.2) × 10-17 kg/s for swelling in 200 µM Ca2+. Under these experimental conditions, a single PTP channel with ionic conductance of 1.5 nS could allow passage of water at the rate of 0.65 × 10-17 kg/s. Thus, we estimate the integral ionic conductance of the whole mitochondrion during PT to be 5.9 ± 0.9 nS for 2 mM concentration of Ca2+ and 2.6 ± 0.4 nS for 200 µM of Ca2+. The number of PTPs per mitochondrion ranged from one to nine. Due to the uncertainties in PTP structure and model parameters, PTP count results may be slightly underestimated. However, taking into account that each mitochondrion has ∼15,000 copies of ATP synthases and ANTs, our data imply that PTP activation is a rare event that occurs only in a small subpopulation of these proteins.
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Affiliation(s)
- Maria A. Neginskaya
- Department of Molecular Pathobiology, College of Dentistry, New York University, New York, NY
| | - Jasiel O. Strubbe
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI
- Department of Physiology, Michigan State University, East Lansing, MI
| | - Giuseppe F. Amodeo
- Department of Molecular Pathobiology, College of Dentistry, New York University, New York, NY
| | - Benjamin A. West
- Department of Physiology, Michigan State University, East Lansing, MI
| | - Shoshana Yakar
- Department of Molecular Pathobiology, College of Dentistry, New York University, New York, NY
| | - Jason N. Bazil
- Department of Physiology, Michigan State University, East Lansing, MI
| | - Evgeny V. Pavlov
- Department of Molecular Pathobiology, College of Dentistry, New York University, New York, NY
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