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Chen Y, Song W, Wang G, Wang Y, Dong S, Wu Y, Wang R, Ma C. Metabolic Engineering of High L-Lysine-Producing Escherichia coli for de Novo Production of L-Lysine-Derived Compounds. ACS Synth Biol 2024; 13:2948-2959. [PMID: 39158285 DOI: 10.1021/acssynbio.4c00356] [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] [Indexed: 08/20/2024]
Abstract
5-Aminovalerate (5-AVA), 5-hydroxyvalerate (5-HV), and 1,5-pentanediol (1,5-PDO) are l-lysine derivatives with extensive applications in the production of materials such as polyesters, polyurethane, plasticizers, inks, and coatings. However, their large-scale production is limited by the lack of efficient synthetic pathways. Here, we aimed to construct multiple synthetic pathways by screening the key enzymes involved in the synthesis of these compounds in Escherichia coli. The engineered pathway utilizing RaiP demonstrated a superior catalytic efficiency. The LER strain that overexpressed only raiP successfully synthesized 9.70 g/L 5-HV and 8.31 g/L 5-AVA, whereas the strain LERGY that overexpressed raiP, gabT, and yahK accumulated 9.72 g/L 5-HV and 7.95 g/L 5-AVA from 20 g/L glucose. The introduction of exogenous transaminases and dehydrogenases enhanced cell growth and fermentation efficiency with respect to 5-HV synthesis, albeit without significantly impacting the yield. Strain LE05, incorporating only two exogenous enzymes, RaiP and CaR, produced 1.87 g/L 1,5-PDO, 3.85 g/L 5-HV, and 4.78 g/L 5-hydroxyglutaraldehyde from 20 g/L glucose after 6 days. The strain LE02G, fortified with transaminase, dehydrogenase, and NADPH regeneration system, accumulated 7.82 g/L 1,5-PDO, whereas the aldp-knock out LE02G2 synthesized 10.98 g/L 1,5-PDO from 50 g/L glucose in fed-batch fermentation after 6 days, yielding 0.22 g/g glucose (0.37 mol/mol). Introducing the NADPH regeneration pathway and deleting the NADPH-consuming pathways increased the 1,5-PDO yield and decreased the precursor concentration. The proposed pathways and engineering strategies presented in this study can prove instrumental in developing biological routes for the practical production of 5-AVA, 5-HV, and 1,5-PDO.
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Affiliation(s)
- Yonghua Chen
- State Key Laboratory of Biobased Material and Green Papermaking (LBMP), Qilu University of Technology, Jinan, Shandong 250353, Republic of China
- School of Bioengineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250353, Republic of China
| | - Wenzhu Song
- State Key Laboratory of Biobased Material and Green Papermaking (LBMP), Qilu University of Technology, Jinan, Shandong 250353, Republic of China
- School of Bioengineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250353, Republic of China
| | - Guodong Wang
- State Key Laboratory of Biobased Material and Green Papermaking (LBMP), Qilu University of Technology, Jinan, Shandong 250353, Republic of China
- School of Bioengineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250353, Republic of China
| | - Yuanwei Wang
- State Key Laboratory of Biobased Material and Green Papermaking (LBMP), Qilu University of Technology, Jinan, Shandong 250353, Republic of China
- School of Bioengineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250353, Republic of China
| | - Shitong Dong
- State Key Laboratory of Biobased Material and Green Papermaking (LBMP), Qilu University of Technology, Jinan, Shandong 250353, Republic of China
- School of Bioengineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250353, Republic of China
| | - Yingshuai Wu
- State Key Laboratory of Biobased Material and Green Papermaking (LBMP), Qilu University of Technology, Jinan, Shandong 250353, Republic of China
- School of Bioengineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250353, Republic of China
| | - Ruiming Wang
- State Key Laboratory of Biobased Material and Green Papermaking (LBMP), Qilu University of Technology, Jinan, Shandong 250353, Republic of China
- School of Bioengineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250353, Republic of China
| | - Chunling Ma
- State Key Laboratory of Biobased Material and Green Papermaking (LBMP), Qilu University of Technology, Jinan, Shandong 250353, Republic of China
- School of Bioengineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250353, Republic of China
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2
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Mailloux RJ. The emerging importance of the α-keto acid dehydrogenase complexes in serving as intracellular and intercellular signaling platforms for the regulation of metabolism. Redox Biol 2024; 72:103155. [PMID: 38615490 PMCID: PMC11021975 DOI: 10.1016/j.redox.2024.103155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2024] [Revised: 04/04/2024] [Accepted: 04/09/2024] [Indexed: 04/16/2024] Open
Abstract
The α-keto acid dehydrogenase complex (KDHc) class of mitochondrial enzymes is composed of four members: pyruvate dehydrogenase (PDHc), α-ketoglutarate dehydrogenase (KGDHc), branched-chain keto acid dehydrogenase (BCKDHc), and 2-oxoadipate dehydrogenase (OADHc). These enzyme complexes occupy critical metabolic intersections that connect monosaccharide, amino acid, and fatty acid metabolism to Krebs cycle flux and oxidative phosphorylation (OxPhos). This feature also imbues KDHc enzymes with the heightened capacity to serve as platforms for propagation of intracellular and intercellular signaling. KDHc enzymes serve as a source and sink for mitochondrial hydrogen peroxide (mtH2O2), a vital second messenger used to trigger oxidative eustress pathways. Notably, deactivation of KDHc enzymes through reversible oxidation by mtH2O2 and other electrophiles modulates the availability of several Krebs cycle intermediates and related metabolites which serve as powerful intracellular and intercellular messengers. The KDHc enzymes also play important roles in the modulation of mitochondrial metabolism and epigenetic programming in the nucleus through the provision of various acyl-CoAs, which are used to acylate proteinaceous lysine residues. Intriguingly, nucleosomal control by acylation is also achieved through PDHc and KGDHc localization to the nuclear lumen. In this review, I discuss emerging concepts in the signaling roles fulfilled by the KDHc complexes. I highlight their vital function in serving as mitochondrial redox sensors and how this function can be used by cells to regulate the availability of critical metabolites required in cell signaling. Coupled with this, I describe in detail how defects in KDHc function can cause disease states through the disruption of cell redox homeodynamics and the deregulation of metabolic signaling. Finally, I propose that the intracellular and intercellular signaling functions of the KDHc enzymes are controlled through the reversible redox modification of the vicinal lipoic acid thiols in the E2 subunit of the complexes.
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Affiliation(s)
- Ryan J Mailloux
- School of Human Nutrition, Faculty of Agricultural and Environmental Sciences, McGill University, Ste-Anne-de-Bellevue, Quebec, Canada.
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3
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Vaglio-Garro A, Kozlov AV, Smirnova YD, Weidinger A. Pathological Interplay between Inflammation and Mitochondria Aggravates Glutamate Toxicity. Int J Mol Sci 2024; 25:2276. [PMID: 38396952 PMCID: PMC10889519 DOI: 10.3390/ijms25042276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2024] [Revised: 02/06/2024] [Accepted: 02/09/2024] [Indexed: 02/25/2024] Open
Abstract
Mitochondrial dysfunction and glutamate toxicity are associated with neural disorders, including brain trauma. A review of the literature suggests that toxic and transmission actions of neuronal glutamate are spatially and functionally separated. The transmission pathway utilizes synaptic GluN2A receptors, rapidly released pool of glutamate, evoked release of glutamate mediated by Synaptotagmin 1 and the amount of extracellular glutamate regulated by astrocytes. The toxic pathway utilizes extrasynaptic GluN2B receptors and a cytoplasmic pool of glutamate, which results from the spontaneous release of glutamate mediated by Synaptotagmin 7 and the neuronal 2-oxoglutarate dehydrogenase complex (OGDHC), a tricarboxylic acid (TCA) cycle enzyme. Additionally, the inhibition of OGDHC observed upon neuro-inflammation is due to an excessive release of reactive oxygen/nitrogen species by immune cells. The loss of OGDHC inhibits uptake of glutamate by mitochondria, thus facilitating its extracellular accumulation and stimulating toxic glutamate pathway without affecting transmission. High levels of extracellular glutamate lead to dysregulation of intracellular redox homeostasis and cause ferroptosis, excitotoxicity, and mitochondrial dysfunction. The latter affects the transmission pathway demanding high-energy supply and leading to cell death. Mitochondria aggravate glutamate toxicity due to impairments in the TCA cycle and become a victim of glutamate toxicity, which disrupts oxidative phosphorylation. Thus, therapies targeting the TCA cycle in neurological disorders may be more efficient than attempting to preserve mitochondrial oxidative phosphorylation.
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Affiliation(s)
- Annette Vaglio-Garro
- Ludwig Boltzmann Institute for Traumatology, The Research Center in Cooperation with AUVA, 1200 Vienna, Austria; (A.V.-G.); (Y.D.S.); (A.W.)
- Austrian Cluster for Tissue Regeneration, 1200 Vienna, Austria
| | - Andrey V. Kozlov
- Ludwig Boltzmann Institute for Traumatology, The Research Center in Cooperation with AUVA, 1200 Vienna, Austria; (A.V.-G.); (Y.D.S.); (A.W.)
- Austrian Cluster for Tissue Regeneration, 1200 Vienna, Austria
| | - Yuliya D. Smirnova
- Ludwig Boltzmann Institute for Traumatology, The Research Center in Cooperation with AUVA, 1200 Vienna, Austria; (A.V.-G.); (Y.D.S.); (A.W.)
- Laboratory of Metagenomics and Food Biotechnology, Voronezh State University of Engineering Technologies, 394036 Voronezh, Russia
| | - Adelheid Weidinger
- Ludwig Boltzmann Institute for Traumatology, The Research Center in Cooperation with AUVA, 1200 Vienna, Austria; (A.V.-G.); (Y.D.S.); (A.W.)
- Austrian Cluster for Tissue Regeneration, 1200 Vienna, Austria
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4
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Ravasz D, Bui D, Nazarian S, Pallag G, Karnok N, Roberts J, Marzullo BP, Tennant DA, Greenwood B, Kitayev A, Hill C, Komlódi T, Doerrier C, Cunatova K, Fernandez-Vizarra E, Gnaiger E, Kiebish MA, Raska A, Kolev K, Czumbel B, Narain NR, Seyfried TN, Chinopoulos C. Residual Complex I activity and amphidirectional Complex II operation support glutamate catabolism through mtSLP in anoxia. Sci Rep 2024; 14:1729. [PMID: 38242919 PMCID: PMC10798963 DOI: 10.1038/s41598-024-51365-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Accepted: 01/04/2024] [Indexed: 01/21/2024] Open
Abstract
Anoxia halts oxidative phosphorylation (OXPHOS) causing an accumulation of reduced compounds in the mitochondrial matrix which impedes dehydrogenases. By simultaneously measuring oxygen concentration, NADH autofluorescence, mitochondrial membrane potential and ubiquinone reduction extent in isolated mitochondria in real-time, we demonstrate that Complex I utilized endogenous quinones to oxidize NADH under acute anoxia. 13C metabolic tracing or untargeted analysis of metabolites extracted during anoxia in the presence or absence of site-specific inhibitors of the electron transfer system showed that NAD+ regenerated by Complex I is reduced by the 2-oxoglutarate dehydrogenase Complex yielding succinyl-CoA supporting mitochondrial substrate-level phosphorylation (mtSLP), releasing succinate. Complex II operated amphidirectionally during the anoxic event, providing quinones to Complex I and reducing fumarate to succinate. Our results highlight the importance of quinone provision to Complex I oxidizing NADH maintaining glutamate catabolism and mtSLP in the absence of OXPHOS.
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Affiliation(s)
- Dora Ravasz
- Department of Biochemistry, Semmelweis University, Budapest, 1094, Hungary
| | - David Bui
- Department of Biochemistry, Semmelweis University, Budapest, 1094, Hungary
| | - Sara Nazarian
- Department of Biochemistry, Semmelweis University, Budapest, 1094, Hungary
| | - Gergely Pallag
- Department of Biochemistry, Semmelweis University, Budapest, 1094, Hungary
| | - Noemi Karnok
- Department of Biochemistry, Semmelweis University, Budapest, 1094, Hungary
| | - Jennie Roberts
- Institute of Metabolism and Systems Research, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - Bryan P Marzullo
- Institute of Metabolism and Systems Research, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - Daniel A Tennant
- Institute of Metabolism and Systems Research, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK
| | | | | | | | - Timea Komlódi
- Department of Biochemistry, Semmelweis University, Budapest, 1094, Hungary
- Oroboros Instruments, Innsbruck, Austria
| | | | - Kristyna Cunatova
- Department of Biomedical Sciences, University of Padova, 35131, Padova, Italy
| | | | | | | | - Alexandra Raska
- Department of Biochemistry, Semmelweis University, Budapest, 1094, Hungary
| | - Krasimir Kolev
- Department of Biochemistry, Semmelweis University, Budapest, 1094, Hungary
| | - Bence Czumbel
- Department of Biochemistry, Semmelweis University, Budapest, 1094, Hungary
| | | | - Thomas N Seyfried
- Biology Department, Boston College, Chestnut Hill, Boston, MA, 02467, USA
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5
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Szabo E, Nagy B, Czajlik A, Komlodi T, Ozohanics O, Tretter L, Ambrus A. Mitochondrial Alpha-Keto Acid Dehydrogenase Complexes: Recent Developments on Structure and Function in Health and Disease. Subcell Biochem 2024; 104:295-381. [PMID: 38963492 DOI: 10.1007/978-3-031-58843-3_13] [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] [Indexed: 07/05/2024]
Abstract
The present work delves into the enigmatic world of mitochondrial alpha-keto acid dehydrogenase complexes discussing their metabolic significance, enzymatic operation, moonlighting activities, and pathological relevance with links to underlying structural features. This ubiquitous family of related but diverse multienzyme complexes is involved in carbohydrate metabolism (pyruvate dehydrogenase complex), the citric acid cycle (α-ketoglutarate dehydrogenase complex), and amino acid catabolism (branched-chain α-keto acid dehydrogenase complex, α-ketoadipate dehydrogenase complex); the complexes all function at strategic points and also participate in regulation in these metabolic pathways. These systems are among the largest multienzyme complexes with at times more than 100 protein chains and weights ranging up to ~10 million Daltons. Our chapter offers a wealth of up-to-date information on these multienzyme complexes for a comprehensive understanding of their significance in health and disease.
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Affiliation(s)
- Eszter Szabo
- Department of Biochemistry, Semmelweis University, Budapest, Hungary
| | - Balint Nagy
- Department of Biochemistry, Semmelweis University, Budapest, Hungary
| | - Andras Czajlik
- Department of Biochemistry, Semmelweis University, Budapest, Hungary
| | - Timea Komlodi
- Department of Biochemistry, Semmelweis University, Budapest, Hungary
| | - Oliver Ozohanics
- Department of Biochemistry, Semmelweis University, Budapest, Hungary
| | - Laszlo Tretter
- Department of Biochemistry, Semmelweis University, Budapest, Hungary
| | - Attila Ambrus
- Department of Biochemistry, Semmelweis University, Budapest, Hungary.
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6
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Piroli GG, Manuel AM, McCain RS, Smith HH, Ozohanics O, Mellid S, Cox JH, Cotham WE, Walla MD, Cascón A, Ambrus A, Frizzell N. Defective function of α-ketoglutarate dehydrogenase exacerbates mitochondrial ATP deficits during complex I deficiency. Redox Biol 2023; 67:102932. [PMID: 37883842 PMCID: PMC10618796 DOI: 10.1016/j.redox.2023.102932] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Revised: 09/27/2023] [Accepted: 10/11/2023] [Indexed: 10/28/2023] Open
Abstract
The NDUFS4 knockout (KO) mouse phenotype resembles the human Complex I deficiency Leigh Syndrome. The irreversible succination of protein thiols by fumarate is increased in select regions of the NDUFS4 KO brain affected by neurodegeneration. We report that dihydrolipoyllysine-residue succinyltransferase (DLST), a component of the α-ketoglutarate dehydrogenase complex (KGDHC) of the tricarboxylic acid (TCA) cycle, is succinated in the affected regions of the NDUFS4 KO brain. Succination of DLST reduced KGDHC activity in the brainstem (BS) and olfactory bulb (OB) of KO mice. The defective production of KGDHC derived succinyl-CoA resulted in decreased mitochondrial substrate level phosphorylation (SLP), further aggravating the existing oxidative phosphorylation (OXPHOS) ATP deficit. Protein succinylation, an acylation modification that requires succinyl-CoA, was reduced in the KO mice. Modeling succination of a cysteine in the spatial vicinity of the DLST active site or introduction of succinomimetic mutations recapitulates these metabolic deficits. Our data demonstrate that the biochemical deficit extends beyond impaired Complex I assembly and OXPHOS deficiency, functionally impairing select components of the TCA cycle to drive metabolic perturbations in affected neurons.
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Affiliation(s)
- Gerardo G Piroli
- Department of Pharmacology, Physiology & Neuroscience, School of Medicine, University of South Carolina, Columbia, SC, 29209, USA
| | - Allison M Manuel
- Department of Pharmacology, Physiology & Neuroscience, School of Medicine, University of South Carolina, Columbia, SC, 29209, USA
| | - Richard S McCain
- Department of Pharmacology, Physiology & Neuroscience, School of Medicine, University of South Carolina, Columbia, SC, 29209, USA
| | - Holland H Smith
- Department of Pharmacology, Physiology & Neuroscience, School of Medicine, University of South Carolina, Columbia, SC, 29209, USA
| | - Oliver Ozohanics
- Department of Biochemistry, Institute of Biochemistry and Molecular Biology, Semmelweis University, Budapest, Hungary
| | - Sara Mellid
- Hereditary Endocrine Cancer Group, Spanish National Cancer Research Centre (CNIO), 28029, Madrid, Spain
| | - J Hunter Cox
- Department of Pharmacology, Physiology & Neuroscience, School of Medicine, University of South Carolina, Columbia, SC, 29209, USA
| | - William E Cotham
- Mass Spectrometry Center, Department of Chemistry & Biochemistry, University of South Carolina, Columbia, SC, 29205, USA
| | - Michael D Walla
- Mass Spectrometry Center, Department of Chemistry & Biochemistry, University of South Carolina, Columbia, SC, 29205, USA
| | - Alberto Cascón
- Hereditary Endocrine Cancer Group, Spanish National Cancer Research Centre (CNIO), 28029, Madrid, Spain; Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), 28029, Madrid, Spain
| | - Attila Ambrus
- Department of Biochemistry, Institute of Biochemistry and Molecular Biology, Semmelweis University, Budapest, Hungary
| | - Norma Frizzell
- Department of Pharmacology, Physiology & Neuroscience, School of Medicine, University of South Carolina, Columbia, SC, 29209, USA.
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7
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Doczi J, Karnok N, Bui D, Azarov V, Pallag G, Nazarian S, Czumbel B, Seyfried TN, Chinopoulos C. Viability of HepG2 and MCF-7 cells is not correlated with mitochondrial bioenergetics. Sci Rep 2023; 13:10822. [PMID: 37402778 DOI: 10.1038/s41598-023-37677-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2022] [Accepted: 06/26/2023] [Indexed: 07/06/2023] Open
Abstract
Alterations in metabolism are a hallmark of cancer. It is unclear if oxidative phosphorylation (OXPHOS) is necessary for tumour cell survival. In this study, we investigated the effects of severe hypoxia, site-specific inhibition of respiratory chain (RC) components, and uncouplers on necrotic and apoptotic markers in 2D-cultured HepG2 and MCF-7 tumour cells. Comparable respiratory complex activities were observed in both cell lines. However, HepG2 cells exhibited significantly higher oxygen consumption rates (OCR) and respiratory capacity than MCF-7 cells. Significant non-mitochondrial OCR was observed in MCF-7 cells, which was insensitive to acute combined inhibition of complexes I and III. Pre-treatment of either cell line with RC inhibitors for 24-72 h resulted in the complete abolition of respective complex activities and OCRs. This was accompanied by a time-dependent decrease in citrate synthase activity, suggesting mitophagy. High-content automated microscopy recordings revealed that the viability of HepG2 cells was mostly unaffected by any pharmacological treatment or severe hypoxia. In contrast, the viability of MCF-7 cells was strongly affected by inhibition of complex IV (CIV) or complex V (CV), severe hypoxia, and uncoupling. However, it was only moderately affected by inhibition of complexes I, II, and III. Cell death in MCF-7 cells induced by inhibition of complexes II, III, and IV was partially abrogated by aspartate. These findings indicate that OXPHOS activity and viability are not correlated in these cell lines, suggesting that the connection between OXPHOS and cancer cell survival is dependent on the specific cell type and conditions.
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Affiliation(s)
- Judit Doczi
- Institute of Biochemistry and Molecular Biology, Department of Biochemistry, Semmelweis University, Budapest, 1094, Hungary
| | - Noemi Karnok
- Institute of Biochemistry and Molecular Biology, Department of Biochemistry, Semmelweis University, Budapest, 1094, Hungary
| | - David Bui
- Institute of Biochemistry and Molecular Biology, Department of Biochemistry, Semmelweis University, Budapest, 1094, Hungary
| | - Victoria Azarov
- Institute of Biochemistry and Molecular Biology, Department of Biochemistry, Semmelweis University, Budapest, 1094, Hungary
| | - Gergely Pallag
- Institute of Biochemistry and Molecular Biology, Department of Biochemistry, Semmelweis University, Budapest, 1094, Hungary
| | - Sara Nazarian
- Institute of Biochemistry and Molecular Biology, Department of Biochemistry, Semmelweis University, Budapest, 1094, Hungary
| | - Bence Czumbel
- Institute of Biochemistry and Molecular Biology, Department of Biochemistry, Semmelweis University, Budapest, 1094, Hungary
| | | | - Christos Chinopoulos
- Institute of Biochemistry and Molecular Biology, Department of Biochemistry, Semmelweis University, Budapest, 1094, Hungary.
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8
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Hansen GE, Gibson GE. The α-Ketoglutarate Dehydrogenase Complex as a Hub of Plasticity in Neurodegeneration and Regeneration. Int J Mol Sci 2022; 23:12403. [PMID: 36293260 PMCID: PMC9603878 DOI: 10.3390/ijms232012403] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Revised: 10/06/2022] [Accepted: 10/11/2022] [Indexed: 07/30/2023] Open
Abstract
Abnormal glucose metabolism is central to neurodegeneration, and considerable evidence suggests that abnormalities in key enzymes of the tricarboxylic acid (TCA) cycle underlie the metabolic deficits. Significant recent advances in the role of metabolism in cancer provide new insight that facilitates our understanding of the role of metabolism in neurodegeneration. Research indicates that the rate-limiting step of the TCA cycle, the α-ketoglutarate dehydrogenase complex (KGDHC) and its substrate alpha ketoglutarate (KG), serve as a signaling hub that regulates multiple cellular processes: (1) is the rate-limiting step of the TCA cycle, (2) is sensitive to reactive oxygen species (ROS) and produces ROS, (3) determines whether KG is used for energy or synthesis of compounds to support growth, (4) regulates the cellular responses to hypoxia, (5) controls the post-translational modification of hundreds of cell proteins in the mitochondria, cytosol, and nucleus through succinylation, (6) controls critical aspects of transcription, (7) modulates protein signaling within cells, and (8) modulates cellular calcium. The primary focus of this review is to understand how reductions in KGDHC are translated to pathologically important changes that underlie both neurodegeneration and cancer. An understanding of each role is necessary to develop new therapeutic strategies to treat neurodegenerative disease.
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Affiliation(s)
- Grace E. Hansen
- Department of Biology, University of Massachusetts, Lowell, MA 01852, USA
| | - Gary E. Gibson
- Weill Cornell Medicine, Brain and Mind Research Institute, Burke Neurological Institute, White Plains, NY 10605, USA
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9
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Divakaruni AS, Jastroch M. A practical guide for the analysis, standardization and interpretation of oxygen consumption measurements. Nat Metab 2022; 4:978-994. [PMID: 35971004 PMCID: PMC9618452 DOI: 10.1038/s42255-022-00619-4] [Citation(s) in RCA: 37] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Accepted: 06/17/2022] [Indexed: 12/14/2022]
Abstract
Measurement of oxygen consumption is a powerful and uniquely informative experimental technique. It can help identify mitochondrial mechanisms of action following pharmacologic and genetic interventions, and characterize energy metabolism in physiology and disease. The conceptual and practical benefits of respirometry have made it a frontline technique to understand how mitochondrial function can interface with-and in some cases control-cell physiology. Nonetheless, an appreciation of the complexity and challenges involved with such measurements is required to avoid common experimental and analytical pitfalls. Here we provide a practical guide to oxygen consumption measurements covering the selection of experimental models and instrumentation, as well as recommendations for the collection, interpretation and normalization of data. These guidelines are provided with the intention of aiding experimental design and enhancing the overall reputability, transparency and reliability of oxygen consumption measurements.
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Affiliation(s)
- Ajit S Divakaruni
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA.
| | - Martin Jastroch
- Department of Molecular Biosciences, The Wenner-Gren Institute, The Arrhenius Laboratories F3, Stockholm University, Stockholm, Sweden
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10
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Horváth G, Sváb G, Komlódi T, Ravasz D, Kacsó G, Doczi J, Chinopoulos C, Ambrus A, Tretter L. Reverse and Forward Electron Flow-Induced H2O2 Formation Is Decreased in α-Ketoglutarate Dehydrogenase (α-KGDH) Subunit (E2 or E3) Heterozygote Knock Out Animals. Antioxidants (Basel) 2022; 11:antiox11081487. [PMID: 36009207 PMCID: PMC9404749 DOI: 10.3390/antiox11081487] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Revised: 07/20/2022] [Accepted: 07/25/2022] [Indexed: 12/04/2022] Open
Abstract
α-ketoglutarate dehydrogenase complex (KGDHc), or 2-oxoglutarate dehydrogenase complex (OGDHc) is a rate-limiting enzyme in the tricarboxylic acid cycle, that has been identified in neurodegenerative diseases such as in Alzheimer’s disease. The aim of the present study was to establish the role of the KGDHc and its subunits in the bioenergetics and reactive oxygen species (ROS) homeostasis of brain mitochondria. To study the bioenergetic profile of KGDHc, genetically modified mouse strains were used having a heterozygous knock out (KO) either in the dihydrolipoyl succinyltransferase (DLST+/−) or in the dihydrolipoyl dehydrogenase (DLD+/−) subunit. Mitochondrial oxygen consumption, hydrogen peroxide (H2O2) production, and expression of antioxidant enzymes were measured in isolated mouse brain mitochondria. Here, we demonstrate that the ADP-stimulated respiration of mitochondria was partially arrested in the transgenic animals when utilizing α-ketoglutarate (α-KG or 2-OG) as a fuel substrate. Succinate and α-glycerophosphate (α-GP), however, did not show this effect. The H2O2 production in mitochondria energized with α-KG was decreased after inhibiting the adenine nucleotide translocase and Complex I (CI) in the transgenic strains compared to the controls. Similarly, the reverse electron transfer (RET)-evoked H2O2 formation supported by succinate or α-GP were inhibited in mitochondria isolated from the transgenic animals. The decrease of RET-evoked ROS production by DLST+/− or DLD+/− KO-s puts the emphasis of the KGDHc in the pathomechanism of ischemia-reperfusion evoked oxidative stress. Supporting this notion, expression of the antioxidant enzyme glutathione peroxidase was also decreased in the KGDHc transgenic animals suggesting the attenuation of ROS-producing characteristics of KGDHc. These findings confirm the contribution of the KGDHc to the mitochondrial ROS production and in the pathomechanism of ischemia-reperfusion injury.
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11
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Proline Oxidation Supports Mitochondrial ATP Production When Complex I Is Inhibited. Int J Mol Sci 2022; 23:ijms23095111. [PMID: 35563503 PMCID: PMC9106064 DOI: 10.3390/ijms23095111] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Revised: 05/02/2022] [Accepted: 05/02/2022] [Indexed: 02/01/2023] Open
Abstract
The oxidation of proline to pyrroline-5-carboxylate (P5C) leads to the transfer of electrons to ubiquinone in mitochondria that express proline dehydrogenase (ProDH). This electron transfer supports Complexes CIII and CIV, thus generating the protonmotive force. Further catabolism of P5C forms glutamate, which fuels the citric acid cycle that yields the reducing equivalents that sustain oxidative phosphorylation. However, P5C and glutamate catabolism depend on CI activity due to NAD+ requirements. NextGen-O2k (Oroboros Instruments) was used to measure proline oxidation in isolated mitochondria of various mouse tissues. Simultaneous measurements of oxygen consumption, membrane potential, NADH, and the ubiquinone redox state were correlated to ProDH activity and F1FO-ATPase directionality. Proline catabolism generated a sufficiently high membrane potential that was able to maintain the F1FO-ATPase operation in the forward mode. This was observed in CI-inhibited mouse liver and kidney mitochondria that exhibited high levels of proline oxidation and ProDH activity. This action was not observed under anoxia or when either CIII or CIV were inhibited. The duroquinone fueling of CIII and CIV partially reproduced the effects of proline. Excess glutamate, however, could not reproduce the proline effect, suggesting that processes upstream of the glutamate conversion from proline were involved. The ProDH inhibitors tetrahydro-2-furoic acid and, to a lesser extent, S-5-oxo-2-tetrahydrofurancarboxylic acid abolished all proline effects. The data show that ProDH-directed proline catabolism could generate sufficient CIII and CIV proton pumping, thus supporting ATP production by the F1FO-ATPase even under CI inhibition.
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Liu Y, Wang H, Shao M, Jin Y, Liao B. The functional role of OGDH for maintaining mitochondrial respiration and identity of primed human embryonic stem cells. Biochem Biophys Res Commun 2022; 612:30-36. [DOI: 10.1016/j.bbrc.2022.04.059] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Accepted: 04/13/2022] [Indexed: 11/02/2022]
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13
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Cell Energy Budget Platform for Multiparametric Assessment of Cell and Tissue Metabolism. Methods Mol Biol 2021; 2276:305-324. [PMID: 34060051 DOI: 10.1007/978-1-0716-1266-8_23] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Specific bioenergetic signature reports on the current metabolic state of the cell, which may be affected by metabolic rearrangement, dysfunction or dysregulation of relevant signaling pathways, altered physiological condition or energy stress. A combined analysis of respiration , glycolytic flux, Krebs cycle activity, ATP levels, and total biomass allows informative initial assessment. Such simple, high-throughput, multiparametric methodology, called cell energy budget (CEB ) platform, is presented here and demonstrated with particular cell and tissue models. The CEB uses a commercial fluorescent lanthanide probe pH-Xtra™ to measure extracellular acidification (ECA) associated with lactate (L-ECA) and combined lactate/CO2 (T-ECA), a phosphorescent probe MitoXpress®-Xtra to measure oxygen consumption rate (OCR), a bioluminescent ATP kit, and an absorbance-based total protein assay. All the assays are performed on a standard multi-label reader. Using the same readouts, the CEB approach can be extended to more detailed mechanistic studies, by targeting specific pathways in cell bioenergetics and measuring other cellular parameters, such as NAD(P)H, Ca2+, mitochondrial pH, membrane potential, redox state, with conventional fluorescent or luminescent probes.
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Chen H, Cross AC, Thakkar A, Xu H, Li A, Paull D, Noggle SA, Kruger L, Denton TT, Gibson GE. Selective linkage of mitochondrial enzymes to intracellular calcium stores differs between human-induced pluripotent stem cells, neural stem cells, and neurons. J Neurochem 2020; 156:867-879. [PMID: 32865230 DOI: 10.1111/jnc.15160] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 08/12/2020] [Accepted: 08/13/2020] [Indexed: 12/15/2022]
Abstract
Mitochondria and releasable endoplasmic reticulum (ER) calcium modulate neuronal calcium signaling, and both change in Alzheimer's disease (AD). The releasable calcium stores in the ER are exaggerated in fibroblasts from AD patients and in multiple models of AD. The activity of the alpha-ketoglutarate dehydrogenase complex (KGDHC), a key mitochondrial enzyme complex, is diminished in brains from AD patients, and can be plausibly linked to plaques and tangles. Our previous studies in cell lines and mouse neurons demonstrate that reductions in KGDHC increase the ER releasable calcium stores. The goal of these studies was to test whether the relationship was true in human iPSC-derived neurons. Inhibition of KGDHC for one or 24 hr increased the ER releasable calcium store in human neurons by 69% and 144%, respectively. The effect was mitochondrial enzyme specific because inhibiting the pyruvate dehydrogenase complex, another key mitochondrial enzyme complex, diminished the ER releasable calcium stores. The link of KGDHC to ER releasable calcium stores was cell type specific as the interaction was not present in iPSC or neural stem cells. Thus, these studies in human neurons verify a link between KGDHC and releasable ER calcium stores, and support the use of human neurons to examine mechanisms and potential therapies for AD.
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Affiliation(s)
- Huanlian Chen
- Burke Neurological Institute, Brain and Mind Research Institute, Weill Cornell Medicine, White Plains, NY, USA
| | - Abigail C Cross
- Burke Neurological Institute, Brain and Mind Research Institute, Weill Cornell Medicine, White Plains, NY, USA
| | - Ankita Thakkar
- Burke Neurological Institute, Brain and Mind Research Institute, Weill Cornell Medicine, White Plains, NY, USA
| | - Hui Xu
- Burke Neurological Institute, Brain and Mind Research Institute, Weill Cornell Medicine, White Plains, NY, USA
| | - Aiqun Li
- The New York Stem Cell Foundation Research Institute, New York, NY, USA.,Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Dan Paull
- The New York Stem Cell Foundation Research Institute, New York, NY, USA
| | - Scott A Noggle
- The New York Stem Cell Foundation Research Institute, New York, NY, USA
| | - Laken Kruger
- Department of Pharmaceutical Sciences, Washington State University, College of Pharmacy and Pharmaceutical Sciences, Spokane, WA, USA
| | - Travis T Denton
- Department of Pharmaceutical Sciences, Washington State University, College of Pharmacy and Pharmaceutical Sciences, Spokane, WA, USA
| | - Gary E Gibson
- Burke Neurological Institute, Brain and Mind Research Institute, Weill Cornell Medicine, White Plains, NY, USA
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15
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McGuire PJ. Chemical individuality in T cells: A Garrodian view of immunometabolism. Immunol Rev 2020; 295:82-100. [PMID: 32236968 DOI: 10.1111/imr.12854] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 02/28/2020] [Accepted: 03/01/2020] [Indexed: 02/06/2023]
Abstract
Metabolically quiescent T cells circulate throughout the body in search of antigen. Following engagement of their cognate receptors, T cells undergo metabolic reprogramming to support their activation, differentiation, and ultimately function. In the spirit of Sir Archibald Garrod, this metabolic reprogramming actually imparts a chemical individuality which confers advantage, while in others confers vulnerability, depending upon the milieu. Studying T cell immunometabolism in the context of inborn errors of metabolism allows one to define essential pathways of intermediary metabolism as well metabolic vulnerabilities and plasticity. Inborn errors of metabolism, a class of diseases first named by Garrod, have a long history of being informative for common physiologic and pathologic processes. This endeavor may be accomplished through the study of patients, animal models, and in vitro models of inborn errors of metabolism. In this review, the basics of intermediary metabolism and core metabolic pathways will be discussed, along with their relationship to T cell immunometabolism. Due to their pleiotropic nature, the reader will be specifically directed toward various inborn errors of metabolism which may be helpful for answering important questions about the role of metabolism in T cells.
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Affiliation(s)
- Peter J McGuire
- National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
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16
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Voloshchuk ON, Kopylchuk GP, Tazirova KA. The Features of Energy Metabolism in Hepatocytes of Rats that Receive Diets with Different Nutrient Contents. Biophysics (Nagoya-shi) 2020. [DOI: 10.1134/s000635092002027x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
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17
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Dobolyi A, Bago A, Palkovits M, Nemeria NS, Jordan F, Doczi J, Ambrus A, Adam-Vizi V, Chinopoulos C. Exclusive neuronal detection of KGDHC-specific subunits in the adult human brain cortex despite pancellular protein lysine succinylation. Brain Struct Funct 2020; 225:639-667. [PMID: 31982949 PMCID: PMC7046601 DOI: 10.1007/s00429-020-02026-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2019] [Accepted: 01/11/2020] [Indexed: 12/31/2022]
Abstract
The ketoglutarate dehydrogenase complex (KGDHC) consists of three different subunits encoded by OGDH (or OGDHL), DLST, and DLD, combined in different stoichiometries. DLD subunit is shared between KGDHC and pyruvate dehydrogenase complex, branched-chain alpha-keto acid dehydrogenase complex, and the glycine cleavage system. Despite KGDHC's implication in neurodegenerative diseases, cell-specific localization of its subunits in the adult human brain has never been investigated. Here, we show that immunoreactivity of all known isoforms of OGDHL, OGDH, and DLST was detected exclusively in neurons of surgical human cortical tissue samples identified by their morphology and visualized by double labeling with fluorescent Nissl, while being absent from glia expressing GFAP, Aldhl1, myelin basic protein, Olig2, or IBA1. In contrast, DLD immunoreactivity was evident in both neurons and glia. Specificity of anti-KGDHC subunits antisera was verified by a decrease in staining of siRNA-treated human cancer cell lines directed against the respective coding gene products; furthermore, immunoreactivity of KGDHC subunits in human fibroblasts co-localized > 99% with mitotracker orange, while western blotting of 63 post-mortem brain samples and purified recombinant proteins afforded further assurance regarding antisera monospecificity. KGDHC subunit immunoreactivity correlated with data from the Human Protein Atlas as well as RNA-Seq data from the Allen Brain Atlas corresponding to genes coding for KGDHC components. Protein lysine succinylation, however, was immunohistochemically evident in all cortical cells; this was unexpected, because this posttranslational modification requires succinyl-CoA, the product of KGDHC. In view of the fact that glia of the human brain cortex lack succinate-CoA ligase, an enzyme producing succinyl-CoA when operating in reverse, protein lysine succinylation in these cells must exclusively rely on propionate and/or ketone body metabolism or some other yet to be discovered pathway encompassing succinyl-CoA.
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Affiliation(s)
- Arpad Dobolyi
- MTA-ELTE Laboratory of Molecular and Systems Neurobiology, Department of Physiology and Neurobiology, Hungarian Academy of Sciences and Eotvos Lorand University, Budapest, 1117, Hungary
- Department of Anatomy, Histology and Embryology, Semmelweis University, Budapest, 1094, Hungary
| | - Attila Bago
- National Institute of Neurosurgery, Budapest, 1145, Hungary
| | - Miklos Palkovits
- MTA-ELTE Laboratory of Molecular and Systems Neurobiology, Department of Physiology and Neurobiology, Hungarian Academy of Sciences and Eotvos Lorand University, Budapest, 1117, Hungary
| | - Natalia S Nemeria
- Department of Chemistry, Rutgers University, Newark, NJ, 07102-1811, USA
| | - Frank Jordan
- Department of Chemistry, Rutgers University, Newark, NJ, 07102-1811, USA
| | - Judit Doczi
- Department of Medical Biochemistry, Semmelweis University, Tuzolto st. 37-47, Budapest, 1094, Hungary
| | - Attila Ambrus
- Department of Medical Biochemistry, Semmelweis University, Tuzolto st. 37-47, Budapest, 1094, Hungary
- MTA-SE Laboratory for Neurobiochemistry, Semmelweis University, Budapest, 1094, Hungary
| | - Vera Adam-Vizi
- Department of Medical Biochemistry, Semmelweis University, Tuzolto st. 37-47, Budapest, 1094, Hungary
- MTA-SE Laboratory for Neurobiochemistry, Semmelweis University, Budapest, 1094, Hungary
| | - Christos Chinopoulos
- Department of Medical Biochemistry, Semmelweis University, Tuzolto st. 37-47, Budapest, 1094, Hungary.
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Chinopoulos C. Acute sources of mitochondrial NAD + during respiratory chain dysfunction. Exp Neurol 2020; 327:113218. [PMID: 32035071 DOI: 10.1016/j.expneurol.2020.113218] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 01/24/2020] [Accepted: 01/30/2020] [Indexed: 01/07/2023]
Abstract
It is a textbook definition that in the absence of oxygen or inhibition of the mitochondrial respiratory chain by pharmacologic or genetic means, hyper-reduction of the matrix pyridine nucleotide pool ensues due to impairment of complex I oxidizing NADH, leading to reductive stress. However, even under these conditions, the ketoglutarate dehydrogenase complex (KGDHC) is known to provide succinyl-CoA to succinyl-CoA ligase, thus supporting mitochondrial substrate-level phosphorylation (mSLP). Mindful that KGDHC is dependent on provision of NAD+, hereby sources of acute NADH oxidation are reviewed, namely i) mitochondrial diaphorases, ii) reversal of mitochondrial malate dehydrogenase, iii) reversal of the mitochondrial isocitrate dehydrogenase as it occurs under acidic conditions, iv) residual complex I activity and v) reverse operation of the malate-aspartate shuttle. The concept of NAD+ import through the inner mitochondrial membrane as well as artificial means of manipulating matrix NAD+/NADH are also discussed. Understanding the above mechanisms providing NAD+ to KGDHC thus supporting mSLP may assist in dampening mitochondrial dysfunction underlying neurological disorders encompassing impairment of the electron transport chain.
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Affiliation(s)
- Christos Chinopoulos
- Department of Medical Biochemistry, Semmelweis University, Tuzolto st. 37-47, Budapest 1094, Hungary.
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Chinopoulos C. Quantification of mitochondrial DNA from peripheral tissues: Limitations in predicting the severity of neurometabolic disorders and proposal of a novel diagnostic test. Mol Aspects Med 2019; 71:100834. [PMID: 31740079 DOI: 10.1016/j.mam.2019.11.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Revised: 11/07/2019] [Accepted: 11/12/2019] [Indexed: 11/25/2022]
Abstract
Neurometabolic disorders stem from errors in metabolic processes yielding a neurological phenotype. A subset of those disorders encompasses mitochondrial abnormalities partially due to mitochondrial DNA (mtDNA) depletion. mtDNA depletion can be attributed to inheritance, spontaneous mutations or acquired from drug-related toxicities. In the armamentarium of diagnostic procedures, mtDNA quantification is a standard for disease classification. However, alterations in mtDNA obtained from peripheral tissues such as skin fibroblasts and blood cells do not often reflect the severity of the affected organ, in this case, the brain. The purpose of this review is to highlight the pitfalls of quantitating mtDNA from peripheral -and not limited to-tissues for diagnosing patients suffering from a variety of mtDNA depletion syndromes exhibiting neurologic abnormalities. In lieu, a qualitative test of mitochondrial substrate-level phosphorylation -even from peripheral tissues-reflecting the ability of mitochondria to rely on glutaminolysis in the presence of respiratory chain defects is proposed as a novel diagnostic assessment of mitochondrial functionality.
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Affiliation(s)
- Christos Chinopoulos
- Department of Medical Biochemistry, Semmelweis University, Tuzolto St. 37-47, Budapest, 1094, Hungary.
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Chinopoulos C, Seyfried TN. Mitochondrial Substrate-Level Phosphorylation as Energy Source for Glioblastoma: Review and Hypothesis. ASN Neuro 2019; 10:1759091418818261. [PMID: 30909720 PMCID: PMC6311572 DOI: 10.1177/1759091418818261] [Citation(s) in RCA: 72] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Glioblastoma multiforme (GBM) is the most common and malignant of the primary adult brain cancers. Ultrastructural and biochemical evidence shows that GBM cells exhibit mitochondrial abnormalities incompatible with energy production through oxidative phosphorylation (OxPhos). Under such conditions, the mitochondrial F0-F1 ATP synthase operates in reverse at the expense of ATP hydrolysis to maintain a moderate membrane potential. Moreover, expression of the dimeric M2 isoform of pyruvate kinase in GBM results in diminished ATP output, precluding a significant ATP production from glycolysis. If ATP synthesis through both glycolysis and OxPhos was impeded, then where would GBM cells obtain high-energy phosphates for growth and invasion? Literature is reviewed suggesting that the succinate-CoA ligase reaction in the tricarboxylic acid cycle can substantiate sufficient ATP through mitochondrial substrate-level phosphorylation (mSLP) to maintain GBM growth when OxPhos is impaired. Production of high-energy phosphates would be supported by glutaminolysis—a hallmark of GBM metabolism—through the sequential conversion of glutamine → glutamate → alpha-ketoglutarate → succinyl CoA → succinate. Equally important, provision of ATP through mSLP would maintain the adenine nucleotide translocase in forward mode, thus preventing the reverse-operating F0-F1 ATP synthase from depleting cytosolic ATP reserves. Because glucose and glutamine are the primary fuels driving the rapid growth of GBM and most tumors for that matter, simultaneous restriction of these two substrates or inhibition of mSLP should diminish cancer viability, growth, and invasion.
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Bui D, Ravasz D, Chinopoulos C. The Effect of 2-Ketobutyrate on Mitochondrial Substrate-Level Phosphorylation. Neurochem Res 2019; 44:2301-2306. [PMID: 30810978 PMCID: PMC6776489 DOI: 10.1007/s11064-019-02759-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 02/19/2019] [Accepted: 02/20/2019] [Indexed: 01/31/2023]
Abstract
The reaction catalyzed by succinate-CoA ligase in the mitochondrial matrix yields a high-energy phosphate when operating towards hydrolysis of the thioester bond of succinyl-CoA, known as mitochondrial substrate-level phosphorylation (mSLP). The catabolism of several metabolites converge to succinyl-CoA but through different biochemical pathways. Among them, threonine, serine and methionine catabolize to succinyl-CoA through the common intermediate, 2-ketobutyrate. During the course of this pathway 2-ketobutyrate will become succinyl-CoA through propionyl-CoA catabolism, obligatorily passing through an ATP-consuming step substantiated by propionyl-CoA carboxylase. Here, by recording the directionality of the adenine nucleotide translocase while measuring membrane potential we tested the hypothesis that catabolism of 2-ketobutyrate negates mSLP due to the ATP-consuming propionyl-CoA carboxylase step in rotenone-treated, isolated mouse liver and brain mitochondria. 2-Ketobutyrate produced a less negative membrane potential compared to NADH or FADH2-linked substrates, which was sensitive to inhibition by rotenone, atpenin and arsenate, implying the involvement of complex I, complex II and a dehydrogenase-most likely branched chain keto-acid dehydrogenase, respectively. Co-addition of 2-ketobutyrate with NADH- or FADH2-linked substrates yielded no greater membrane potential than in the presence of substrates alone. However, in the presence of NADH-linked substrates, 2-ketobutyrate prevented mSLP in a dose-dependent manner. Our results imply that despite that 2-ketobutyrate leads to succinyl-CoA formation, obligatory metabolism through propionyl-CoA carboxylase associated with ATP expenditure abolishes mSLP. The provision of metabolites converging to 2-ketobutyrate may be a useful way for manipulating mSLP without using pharmacological or genetic tools.
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Affiliation(s)
- David Bui
- Department of Medical Biochemistry, Semmelweis University, Tuzolto st. 37-47, Budapest, 1094, Hungary
| | - Dora Ravasz
- Department of Medical Biochemistry, Semmelweis University, Tuzolto st. 37-47, Budapest, 1094, Hungary
| | - Christos Chinopoulos
- Department of Medical Biochemistry, Semmelweis University, Tuzolto st. 37-47, Budapest, 1094, Hungary.
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Chinopoulos C. Succinate in ischemia: Where does it come from? Int J Biochem Cell Biol 2019; 115:105580. [PMID: 31394174 DOI: 10.1016/j.biocel.2019.105580] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Revised: 07/30/2019] [Accepted: 08/02/2019] [Indexed: 12/20/2022]
Abstract
During tissue ischemia succinate accumulates. Herein, literature spanning the past nine decades is reviewed leaning towards the far greater role of Krebs cycle's canonical activity yielding succinate through α-ketoglutarate -> succinyl-CoA -> succinate even in hypoxia, as opposed to reversal of succinate dehydrogenase. Furthermore, the concepts of i) a diode-like property of succinate dehydrogenase rendering it difficult to reverse, and ii) the absence of mammalian mitochondrial quinones exhibiting redox potentials in the [-60, -80] mV range needed for fumarate reduction, are discussed. Finally, it is emphasized that a "fumarate reductase" enzyme entity reducing fumarate to succinate found in some bacteria and lower eukaryotes remains to be discovered in mammalian mitochondria.
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Affiliation(s)
- Christos Chinopoulos
- Department of Medical Biochemistry, Semmelweis University, Tuzolto st. 37-47, Budapest, 1094, Hungary.
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Bunik VI. Redox-Driven Signaling: 2-Oxo Acid Dehydrogenase Complexes as Sensors and Transmitters of Metabolic Imbalance. Antioxid Redox Signal 2019; 30:1911-1947. [PMID: 30187773 DOI: 10.1089/ars.2017.7311] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
SIGNIFICANCE This article develops a holistic view on production of reactive oxygen species (ROS) by 2-oxo acid dehydrogenase complexes. Recent Advances: Catalytic and structural properties of the complexes and their components evolved to minimize damaging effects of side reactions, including ROS generation, simultaneously exploiting the reactions for homeostatic signaling. CRITICAL ISSUES Side reactions of the complexes, characterized in vitro, are analyzed in view of protein interactions and conditions in vivo. Quantitative data support prevalence of the forward 2-oxo acid oxidation over the backward NADH oxidation in feeding physiologically significant ROS production by the complexes. Special focus on interactions between the active sites within 2-oxo acid dehydrogenase complexes highlights the central relevance of the complex-bound thiyl radicals in regulation of and signaling by complex-generated ROS. The thiyl radicals arise when dihydrolipoyl residues of the complexes regenerate FADH2 from the flavin semiquinone coproduced with superoxide anion radical in 1e- oxidation of FADH2 by molecular oxygen. FUTURE DIRECTIONS Interaction of 2-oxo acid dehydrogenase complexes with thioredoxins (TRXs), peroxiredoxins, and glutaredoxins mediates scavenging of the thiyl radicals and ROS generated by the complexes, underlying signaling of disproportional availability of 2-oxo acids, CoA, and NAD+ in key metabolic branch points through thiol/disulfide exchange and medically important hypoxia-inducible factor, mammalian target of rapamycin (mTOR), poly (ADP-ribose) polymerase, and sirtuins. High reactivity of the coproduced ROS and thiyl radicals to iron/sulfur clusters and nitric oxide, peroxynitrite reductase activity of peroxiredoxins and transnitrosylating function of thioredoxin, implicate the side reactions of 2-oxo acid dehydrogenase complexes in nitric oxide-dependent signaling and damage.
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Affiliation(s)
- Victoria I Bunik
- 1 Belozersky Institute of Physicochemical Biology, Lomonosov Moscow State University, Moscow, Russian Federation.,2 Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, Russian Federation
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Flores RE, Brown AK, Taus L, Khoury J, Glover F, Kami K, Sarangarajan R, Walshe TE, Narain NR, Kiebish MA, Shelton LM, Chinopoulos C, Seyfried TN. Mycoplasma infection and hypoxia initiate succinate accumulation and release in the VM-M3 cancer cells. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2018; 1859:975-983. [DOI: 10.1016/j.bbabio.2018.03.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Accepted: 03/19/2018] [Indexed: 11/25/2022]
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Abstract
Mutations in mtDNA associated with OXPHOS defects preclude energy harnessing by OXPHOS. The work of Chen et al. (2018) is previewed, reporting flux pathways of glutamine catabolism in mtDNA mutant cells yielding high-energy phosphates through substrate-level phosphorylation and the influence exerted by the severity of OXPHOS impairment.
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Affiliation(s)
- Christos Chinopoulos
- Department of Medical Biochemistry, Semmelweis University, Budapest 1094, Hungary.
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26
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Xu Z, Jin X, Cai W, Zhou M, Shao P, Yang Z, Fu R, Cao J, Liu Y, Yu F, Fan R, Zhang Y, Zou S, Zhou X, Yang N, Chen X, Li Y. Proteomics Analysis Reveals Abnormal Electron Transport and Excessive Oxidative Stress Cause Mitochondrial Dysfunction in Placental Tissues of Early-Onset Preeclampsia. Proteomics Clin Appl 2018; 12:e1700165. [PMID: 29676857 DOI: 10.1002/prca.201700165] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Revised: 04/06/2018] [Indexed: 12/11/2022]
Abstract
PURPOSE Early-onset preeclampsia (EOS-PE) refers to preeclampsia that occurred before 34 gestation weeks. This study is conducted to explore the relationship between mitochondrial dysfunction and the pathogenesis of EOS-PE using proteomic strategy. EXPERIMENTAL DESIGN To identify altering expressed mitochondrial proteins between severe EOS-PE and healthy pregnancies, enrichment of mitochondria coupled with iTRAQ-based quantitative proteomic method is performed. Immunohistochemistry (IHC) and western blot are performed to detect the alteration of changing expression proteins, and confirmed the accuracy of proteomic results. RESULTS A total of 1372 proteins were quantified and 132 altering expressed proteins were screened, including 86 downregulated expression proteins and 46 upregulated expression proteins (p < 0.05). Bioinformatics analysis showed that differentially expressed proteins participated in numerous biological processes, including oxidation-reduction process, respiratory electron transport chain, and oxidative phosphorylation. Especially, mitochondria-related molecules, PRDX2, PARK7, BNIP3, BCL2, PDHA1, SUCLG1, ACADM, and NDUFV1, are involved in energy-production process in the matrix and membrane of mitochondria. CONCLUSIONS AND CLINICAL RELEVANCE Results of the experiment show that abnormal electron transport, excessive oxidative stress, and mitochondrion disassembly might be the main cause of mitochondrial dysfunction, and is related to the pathogenesis of EOS-PE.
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Affiliation(s)
- Zhongwei Xu
- Central Laboratory, Logistics University of Chinese People's Armed Police Force, Tianjin, 300309, China.,Tianjin Key Laboratory of Cardiovascular Remodeling & Target Organ Injury, Pingjin Hospital Heart Center, Tianjin, 300162, China
| | - Xiaohan Jin
- Central Laboratory, Logistics University of Chinese People's Armed Police Force, Tianjin, 300309, China.,Tianjin Key Laboratory of Cardiovascular Remodeling & Target Organ Injury, Pingjin Hospital Heart Center, Tianjin, 300162, China
| | - Wei Cai
- Tianjin Key Laboratory of Cardiovascular Remodeling & Target Organ Injury, Pingjin Hospital Heart Center, Tianjin, 300162, China
| | - Maobin Zhou
- Central Laboratory, Logistics University of Chinese People's Armed Police Force, Tianjin, 300309, China
| | - Ping Shao
- Women and Children Health Care Center, Tianjin, 300070, China
| | - Zhen Yang
- Central Laboratory, Logistics University of Chinese People's Armed Police Force, Tianjin, 300309, China
| | - Rong Fu
- Central Laboratory, Logistics University of Chinese People's Armed Police Force, Tianjin, 300309, China
| | - Jin Cao
- Central Laboratory, Logistics University of Chinese People's Armed Police Force, Tianjin, 300309, China
| | - Yan Liu
- Tianjin First Center Hospital, Tianjin, 300192, China
| | - Fang Yu
- Obstetrics and Gynecology Department, Pingjin Hospital, Tianjin, 300162, China
| | - Rong Fan
- Central Laboratory, Logistics University of Chinese People's Armed Police Force, Tianjin, 300309, China
| | - Yan Zhang
- Central Laboratory, Logistics University of Chinese People's Armed Police Force, Tianjin, 300309, China
| | - Shuang Zou
- Central Laboratory, Logistics University of Chinese People's Armed Police Force, Tianjin, 300309, China
| | - Xin Zhou
- Tianjin Key Laboratory of Cardiovascular Remodeling & Target Organ Injury, Pingjin Hospital Heart Center, Tianjin, 300162, China
| | - Ning Yang
- Tianjin Key Laboratory of Cardiovascular Remodeling & Target Organ Injury, Pingjin Hospital Heart Center, Tianjin, 300162, China
| | - Xu Chen
- Tianjin Central Hospital of Gynecology Obstetrics, Tianjin, 300100, China
| | - Yuming Li
- Tianjin Key Laboratory of Cardiovascular Remodeling & Target Organ Injury, Pingjin Hospital Heart Center, Tianjin, 300162, China
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Ravasz D, Kacso G, Fodor V, Horvath K, Adam-Vizi V, Chinopoulos C. Reduction of 2-methoxy-1,4-naphtoquinone by mitochondrially-localized Nqo1 yielding NAD + supports substrate-level phosphorylation during respiratory inhibition. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2018; 1859:909-924. [PMID: 29746824 DOI: 10.1016/j.bbabio.2018.05.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Revised: 04/26/2018] [Accepted: 05/03/2018] [Indexed: 01/07/2023]
Abstract
Provision of NAD+ for oxidative decarboxylation of alpha-ketoglutarate to succinyl-CoA by the ketoglutarate dehydrogenase complex (KGDHC) is critical for maintained operation of succinyl-CoA ligase yielding high-energy phosphates, a process known as mitochondrial substrate-level phosphorylation (mSLP). We have shown previously that when NADH oxidation by complex I is inhibited by rotenone or anoxia, mitochondrial diaphorases yield NAD+, provided that suitable quinones are present (Kiss G et al., FASEB J 2014, 28:1682). This allows for KGDHC reaction to proceed and as an extension of this, mSLP. NAD(P)H quinone oxidoreductase 1 (NQO1) is an enzyme exhibiting diaphorase activity. Here, by using Nqo1-/- and WT littermate mice we show that in rotenone-treated, isolated liver mitochondria 2-methoxy-1,4-naphtoquinone (MNQ) is preferentially reduced by matrix Nqo1 yielding NAD+ to KGDHC, supporting mSLP. This process was sensitive to inhibition by specific diaphorase inhibitors. Reduction of idebenone and its analogues MRQ-20 and MRQ-56, menadione, mitoquinone and duroquinone were unaffected by genetic disruption of the Nqo1 gene. The results allow for the conclusions that i) MNQ is a Nqo1-preferred substrate, and ii) in the presence of suitable quinones, mitochondrially-localized diaphorases other than Nqo1 support NADH oxidation when complex I is inhibited. Our work confirms that complex I bypass can occur by quinones reduced by intramitochondrial diaphorases oxidizing NADH, ultimately supporting mSLP. Finally, it may help to elucidate structure-activity relationships of redox-active quinones with diaphorase enzymes.
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Affiliation(s)
- Dora Ravasz
- Department of Medical Biochemistry, Semmelweis University, Budapest 1094, Hungary
| | - Gergely Kacso
- Department of Medical Biochemistry, Semmelweis University, Budapest 1094, Hungary
| | - Viktoria Fodor
- Department of Medical Biochemistry, Semmelweis University, Budapest 1094, Hungary
| | - Kata Horvath
- Department of Medical Biochemistry, Semmelweis University, Budapest 1094, Hungary
| | - Vera Adam-Vizi
- Department of Medical Biochemistry, Semmelweis University, Budapest 1094, Hungary
| | - Christos Chinopoulos
- Department of Medical Biochemistry, Semmelweis University, Budapest 1094, Hungary.
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28
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Abstract
Many potentially toxic electrophilic xenobiotics and some endogenous compounds are detoxified by conversion to the corresponding glutathione S-conjugate, which is metabolized to the N-acetylcysteine S-conjugate (mercapturate) and excreted. Some mercapturate pathway components, however, are toxic. Bioactivation (toxification) may occur when the glutathione S-conjugate (or mercapturate) is converted to a cysteine S-conjugate that undergoes a β-lyase reaction. If the sulfhydryl-containing fragment produced in this reaction is reactive, toxicity may ensue. Some drugs and halogenated workplace/environmental contaminants are bioactivated by this mechanism. On the other hand, cysteine S-conjugate β-lyases occur in nature as a means of generating some biologically useful sulfhydryl-containing compounds.
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Wollenman LC, Vander Ploeg MR, Miller ML, Zhang Y, Bazil JN. The effect of respiration buffer composition on mitochondrial metabolism and function. PLoS One 2017; 12:e0187523. [PMID: 29091971 PMCID: PMC5665555 DOI: 10.1371/journal.pone.0187523] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Accepted: 10/20/2017] [Indexed: 11/19/2022] Open
Abstract
Functional studies on isolated mitochondria critically rely on the right choice of respiration buffer. Differences in buffer composition can lead to dramatically different respiration rates leading to difficulties in comparing prior studies. The ideal buffer facilities high ADP-stimulated respiratory rates and minimizes substrate transport effects so that the ability to distinguish between various treatments and conditions is maximal. In this study, we analyzed a variety of respiration buffers and substrate combinations to determine the optimal conditions to support mitochondrial function through ADP-stimulated respiration and uncoupled respiration using FCCP. The buffers consisted of a standard KCl based buffer (B1) and three modified buffers with chloride replaced by the K-lactobionate, sucrose, and the antioxidant taurine (B2) or K-gluconate (B3). The fourth buffer (B4) was identical to B2 except that K-lactobionate was replaced with K-gluconate. The substrate combinations consisted of metabolites that utilize different pathways of mitochondrial metabolism. To test mitochondrial function, we used isolated cardiac guinea pig mitochondria and measured oxygen consumption for three respiratory states using an Oroboros Oxygraph-2k. These states were the leak state (energized mitochondria in the absence of adenylates), ADP-stimulated state (energized mitochondria in the presence of saturating ADP concentrations), and uncoupled state (energized mitochondria in the presence of FCCP). On average across all substrate combinations, buffers B2, B3, and B4 had an increase of 16%, 26%, and 35% for the leak state, ADP-simulated state, and uncoupled state, respectively, relative to rates using B1. The common feature distinguishing these buffers from B1 is the notable lack of high chloride concentrations. Based on the respiratory rate metrics obtained with the substrate combinations, we conclude that the adenine nucleotide translocase, the dicarboxylate carrier, and the alpha-ketoglutarate exchanger are partially inhibited by chloride. Therefore, when the goal is to maximize ADP-stimulated respiration, buffers containing K-lactobionate or K-gluconate are superior choices compared to the standard KCl-based buffers.
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Affiliation(s)
- Lucas C. Wollenman
- Department of Physiology, Michigan State University, East Lansing, MI, United States of America
- Vanderbilt University School of Medicine, Nashville, TN, United States of America
| | - Matthew R. Vander Ploeg
- Department of Physiology, Michigan State University, East Lansing, MI, United States of America
| | - Mackinzie L. Miller
- Biomedical Laboratory Diagnostics, Michigan State University, East Lansing, MI, United States of America
- Nephrology and Hypertension, Henry Ford Hospital, Detroit, MI, United States of America
| | - Yizhu Zhang
- Department of Physiology, Michigan State University, East Lansing, MI, United States of America
| | - Jason N. Bazil
- Department of Physiology, Michigan State University, East Lansing, MI, United States of America
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30
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The biological foundation of the genetic association of TOMM40 with late-onset Alzheimer's disease. Biochim Biophys Acta Mol Basis Dis 2017; 1863:2973-2986. [PMID: 28768149 DOI: 10.1016/j.bbadis.2017.07.031] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2017] [Revised: 07/13/2017] [Accepted: 07/28/2017] [Indexed: 02/06/2023]
Abstract
A variable-length poly-T variant in intron 6 of the TOMM40 gene, rs10524523, is associated with risk and age-of-onset of sporadic (late-onset) Alzheimer's disease. In Caucasians, the three predominant alleles at this locus are Short (S), Long (L) or Very long (VL). On an APOE ε3/3 background, the S/VL and VL/VL genotypes are more protective than S/S. The '523 poly-T has regulatory properties, in that the VL poly-T results in higher expression than the S poly-T in luciferase expression systems. The aim of the current work was to identify effects on cellular bioenergetics of increased TOM40 protein expression. MitoTracker Green fluorescence and autophagic vesicle staining was the same in control and over-expressing cells, but TOM40 over-expression was associated with increased expression of TOM20, a preprotein receptor of the TOM complex, the mitochondrial chaperone HSPA9, and PDHE1a, and increased activities of the oxidative phosphorylation complexes I and IV and of the TCA member α-ketoglutaric acid dehydrogenase. Consistent with the complex I findings, respiration was more sensitive to inhibition by rotenone in control cells than in the TOM40 over-expressing cells. In the absence of inhibitors, total cellular ATP, the mitochondrial membrane potential, and respiration were elevated in the over-expressing cells. Spare respiratory capacity was greater in the TOM40 over-expressing cells than in the controls. TOM40 over-expression blocked Ab-elicited decreases in the mitochondrial membrane potential, cellular ATP levels, and cellular viability in the control cells. These data suggest elevated expression of TOM40 may be protective of mitochondrial function.
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31
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Komlódi T, Tretter L. Methylene blue stimulates substrate-level phosphorylation catalysed by succinyl-CoA ligase in the citric acid cycle. Neuropharmacology 2017; 123:287-298. [PMID: 28495375 DOI: 10.1016/j.neuropharm.2017.05.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Revised: 05/05/2017] [Accepted: 05/07/2017] [Indexed: 10/19/2022]
Abstract
Methylene blue (MB), a potential neuroprotective agent, is efficient in various neurodegenerative disease models. Beneficial effects of MB have been attributed to improvements in mitochondrial functions. Substrate-level phosphorylation (SLP) results in the production of ATP independent from the ATP synthase (ATP-ase). In energetically compromised mitochondria, ATP produced by SLP can prevent the reversal of the adenine nucleotide translocase and thus the hydrolysis of glycolytic ATP. The aim of the present study was to investigate the effect of MB on mitochondrial SLP catalysed by succinyl-CoA ligase. Measurements were carried out on isolated guinea pig cortical mitochondria respiring on α-ketoglutarate, glutamate, malate or succinate. The mitochondrial functions and parameters like ATP synthesis, oxygen consumption, membrane potential, and NAD(P)H level were followed online, in parallel with the redox state of MB. SLP-mediated ATP synthesis was measured in the presence of inhibitors for ATP-ase and adenylate kinase. In the presence of the ATP-ase inhibitor oligomycin MB stimulated respiration with all of the respiratory substrates. However, the rate of ATP synthesis increased only with substrates α-ketoglutarate and glutamate (forming succinyl-CoA). MB efficiently stimulated SLP and restored the membrane potential in mitochondria also with the combined inhibition of Complex I and ATP synthase. ATP formed by SLP alleviated the energetic insufficiency generated by the lack of oxidative phosphorylation. Thus, the MB-mediated stimulation of SLP might be important in maintaining the energetic competence of mitochondria and in preventing the mitochondrial hydrolysis of glycolytic ATP. The mitochondrial effects of MB are explained by the ability to accept electrons from reducing equivalents and transfer them to cytochrome c bypassing the respiratory Complexes I and III.
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Affiliation(s)
- T Komlódi
- Department of Medical Biochemistry, MTA-SE Laboratory for Neurobiochemistry, Semmelweis University, 37-47 Tuzolto St., Budapest, 1094, Hungary
| | - L Tretter
- Department of Medical Biochemistry, MTA-SE Laboratory for Neurobiochemistry, Semmelweis University, 37-47 Tuzolto St., Budapest, 1094, Hungary.
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32
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Zhdanov AV, Andreev DE, Baranov PV, Papkovsky DB. Low energy costs of F1Fo ATP synthase reversal in colon carcinoma cells deficient in mitochondrial complex IV. Free Radic Biol Med 2017; 106:184-195. [PMID: 28189850 DOI: 10.1016/j.freeradbiomed.2017.02.025] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Revised: 02/08/2017] [Accepted: 02/08/2017] [Indexed: 10/20/2022]
Abstract
Mitochondrial polarisation is paramount for a variety of cellular functions. Under ischemia, mitochondrial membrane potential (ΔΨm) and proton gradient (ΔpH) are maintained via a reversal of mitochondrial F1Fo ATP synthase (mATPase), which can rapidly deplete ATP and drive cells into energy crisis. We found that under normal conditions in cells with disassembled cytochrome c oxidase complex (COX-deficient HCT116), mATPase maintains ΔΨm at levels only 15-20% lower than in WT cells, and for this utilises relatively little ATP. For a small energy expenditure, mATPase enables mitochondrial ΔpH, protein import, Ca2+ turnover, and supports free radical detoxication machinery enlarged to protect the cells from oxidative damage. Whereas in COX-deficient cells the main source of ATP is glycolysis, the ΔΨm is still maintained upon inhibition of the adenine nucleotide translocators with bongkrekic acid and carboxyatractyloside, indicating that the role of ANTs is redundant, and matrix substrate level phosphorylation alone or in cooperation with ATP-Mg/Pi carriers can continuously support the mATPase activity. Intriguingly, we found that mitochondrial complex III is active, and it contributes not only to free radical production, but also to ΔΨm maintenance and energy budget of COX-deficient cells. Overall, this study demonstrates that F1Fo ATP synthase can support general mitochondrial and cellular functions, working in extremely efficient 'energy saving' reverse mode and flexibly recruiting free radical detoxication and ATP producing / transporting pathways.
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Affiliation(s)
- Alexander V Zhdanov
- School of Biochemistry & Cell Biology, University College Cork, Cork, Ireland.
| | - Dmitry E Andreev
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Pavel V Baranov
- School of Biochemistry & Cell Biology, University College Cork, Cork, Ireland
| | - Dmitri B Papkovsky
- School of Biochemistry & Cell Biology, University College Cork, Cork, Ireland
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33
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Ravasz D, Kacso G, Fodor V, Horvath K, Adam-Vizi V, Chinopoulos C. Catabolism of GABA, succinic semialdehyde or gamma-hydroxybutyrate through the GABA shunt impair mitochondrial substrate-level phosphorylation. Neurochem Int 2017; 109:41-53. [PMID: 28300620 DOI: 10.1016/j.neuint.2017.03.008] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Revised: 03/06/2017] [Accepted: 03/09/2017] [Indexed: 10/20/2022]
Abstract
GABA is catabolized in the mitochondrial matrix through the GABA shunt, encompassing transamination to succinic semialdehyde followed by oxidation to succinate by the concerted actions of GABA transaminase (GABA-T) and succinic semialdehyde dehydrogenase (SSADH), respectively. Gamma-hydroxybutyrate (GHB) is a neurotransmitter and a psychoactive drug that could enter the citric acid cycle through transhydrogenation with α-ketoglutarate to succinic semialdehyde and d-hydroxyglutarate, a reaction catalyzed by hydroxyacid-oxoacid transhydrogenase (HOT). Here, we tested the hypothesis that the elevation in matrix succinate concentration caused by exogenous addition of GABA, succinic semialdehyde or GHB shifts the equilibrium of the reversible reaction catalyzed by succinate-CoA ligase towards ATP (or GTP) hydrolysis, effectively negating substrate-level phosphorylation (SLP). Mitochondrial SLP was addressed by interrogating the directionality of the adenine nucleotide translocase during anoxia in isolated mouse brain and liver mitochondria. GABA eliminated SLP, and this was rescued by the GABA-T inhibitors vigabatrin and aminooxyacetic acid. Succinic semialdehyde was an extremely efficient substrate energizing mitochondria during normoxia but mimicked GABA in abolishing SLP in anoxia, in a manner refractory to vigabatrin and aminooxyacetic acid. GHB could moderately energize liver but not brain mitochondria consistent with the scarcity of HOT expression in the latter. In line with these results, GHB abolished SLP in liver but not brain mitochondria during anoxia and this was unaffected by either vigabatrin or aminooxyacetic acid. It is concluded that when mitochondria catabolize GABA or succinic semialdehyde or GHB through the GABA shunt, their ability to perform SLP is impaired.
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Affiliation(s)
- Dora Ravasz
- Department of Medical Biochemistry, Semmelweis University, Budapest, 1094, Hungary; MTA-SE Lendület Neurobiochemistry Research Group, Hungary
| | - Gergely Kacso
- Department of Medical Biochemistry, Semmelweis University, Budapest, 1094, Hungary; MTA-SE Lendület Neurobiochemistry Research Group, Hungary
| | - Viktoria Fodor
- Department of Medical Biochemistry, Semmelweis University, Budapest, 1094, Hungary; MTA-SE Lendület Neurobiochemistry Research Group, Hungary
| | - Kata Horvath
- Department of Medical Biochemistry, Semmelweis University, Budapest, 1094, Hungary; MTA-SE Lendület Neurobiochemistry Research Group, Hungary
| | - Vera Adam-Vizi
- Department of Medical Biochemistry, Semmelweis University, Budapest, 1094, Hungary; MTA-SE Laboratory for Neurobiochemistry, Hungary
| | - Christos Chinopoulos
- Department of Medical Biochemistry, Semmelweis University, Budapest, 1094, Hungary; MTA-SE Lendület Neurobiochemistry Research Group, Hungary.
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34
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Sharikadze N, Jojua N, Sepashvili M, Zhuravliova E, Mikeladze DG. Mitochondrial Target of Nobiletin's Action. Nat Prod Commun 2016. [DOI: 10.1177/1934578x1601101215] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Nobiletin is an O-methylated flavonoid found in citrus peels that have anticancer, antiviral, neuroprotective, anti-inflammatory activities and depending on the cell types exhibits both pro- or anti-apoptotic properties. We have found that nobiletin decreases oxygen consumption by bovine brain isolated mitochondria in the presence of glutamate and malate and increases in the presence of succinate. In parallel, nobiletin increases NADH oxidation, a-ketoglutarate dehydrogenase activities and through matrix substrate-level phosphorylation elevates the a-ketoglutarate-dependent production of ATP. In addition, nobiletin reduces the production of peroxides in the presence of complex I substrates and slightly enhances succinate-driven H2O2 formation. Besides, nobiletin induces transient elevation of membrane potential followed by mild depolarization. Affinity purified nobiletin binding proteins revealed one major anti-NDUFV1 positive protein with 52kD and NADH: ubiquinone oxidoreductase activity. This fraction can produce peroxide that is inhibited by nobiletin. We propose that nobiletin may act as a mild “uncoupler”, which through activation of a-ketoglutarate dehydrogenase (a-KGDH)-complex and acceleration of matrix substrate-level phosphorylation maintains membrane potential at an abnormal level. This switch in mitochondrial metabolism could elevate succinate-driven oxygen consumption that may underlay in both pro- and anti-apoptotic effects of nobiletin.
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Affiliation(s)
- Nino Sharikadze
- Ilia State University, 3/5 Cholokashvili av., Tbilisi, 0162, Georgia
| | - Natia Jojua
- Ilia State University, 3/5 Cholokashvili av., Tbilisi, 0162, Georgia
| | - Maia Sepashvili
- Ilia State University, 3/5 Cholokashvili av., Tbilisi, 0162, Georgia
| | - Elene Zhuravliova
- Ilia State University, 3/5 Cholokashvili av., Tbilisi, 0162, Georgia
- I. Beritashvili Center of Experimental Biomedicine, 14 Gotua st, Tbilisi, 0160, Georgia
| | - David G Mikeladze
- Ilia State University, 3/5 Cholokashvili av., Tbilisi, 0162, Georgia
- I. Beritashvili Center of Experimental Biomedicine, 14 Gotua st, Tbilisi, 0160, Georgia
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35
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Two transgenic mouse models for β-subunit components of succinate-CoA ligase yielding pleiotropic metabolic alterations. Biochem J 2016; 473:3463-3485. [PMID: 27496549 PMCID: PMC5126846 DOI: 10.1042/bcj20160594] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Accepted: 08/05/2016] [Indexed: 12/14/2022]
Abstract
Succinate-CoA ligase (SUCL) is a heterodimer enzyme composed of Suclg1 α-subunit and a substrate-specific Sucla2 or Suclg2 β-subunit yielding ATP or GTP, respectively. In humans, the deficiency of this enzyme leads to encephalomyopathy with or without methylmalonyl aciduria, in addition to resulting in mitochondrial DNA depletion. We generated mice lacking either one Sucla2 or Suclg2 allele. Sucla2 heterozygote mice exhibited tissue- and age-dependent decreases in Sucla2 expression associated with decreases in ATP-forming activity, but rebound increases in cardiac Suclg2 expression and GTP-forming activity. Bioenergetic parameters including substrate-level phosphorylation (SLP) were not different between wild-type and Sucla2 heterozygote mice unless a submaximal pharmacological inhibition of SUCL was concomitantly present. mtDNA contents were moderately decreased, but blood carnitine esters were significantly elevated. Suclg2 heterozygote mice exhibited decreases in Suclg2 expression but no rebound increases in Sucla2 expression or changes in bioenergetic parameters. Surprisingly, deletion of one Suclg2 allele in Sucla2 heterozygote mice still led to a rebound but protracted increase in Suclg2 expression, yielding double heterozygote mice with no alterations in GTP-forming activity or SLP, but more pronounced changes in mtDNA content and blood carnitine esters, and an increase in succinate dehydrogenase activity. We conclude that a partial reduction in Sucla2 elicits rebound increases in Suclg2 expression, which is sufficiently dominant to overcome even a concomitant deletion of one Suclg2 allele, pleiotropically affecting metabolic pathways associated with SUCL. These results as well as the availability of the transgenic mouse colonies will be of value in understanding SUCL deficiency.
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36
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Voloshchuk ON, Kopylchuk GP. [Activity of liver mitochondrial NAD+-dependent dehydrogenases of the krebs cycle in rats with acetaminophen-induced hepatitis developed under conditions of alimentary protein deficiency]. BIOMEDIT︠S︡INSKAI︠A︡ KHIMII︠A︡ 2016; 62:169-72. [PMID: 27143375 DOI: 10.18097/pbmc20166202169] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Activity of isocitrate dehydrogenase, α-ketoglutarate dehydrogenase, malate dehydrogenase, and the NAD(+)/NADН ratio were studied in the liver mitochondrial fraction of rats with toxic hepatitis induced by acetaminophen under conditions of alimentary protein deprivation. Acetaminophen-induced hepatitis was characterized by a decrease of isocitrate dehydrogenase, α-ketoglutarate dehydrogenase and malate dehydrogenase activities, while the mitochondrial NAD(+)/NADН ratio remained at the control level. Modeling of acetaminophen-induced hepatitis in rats with alimentary protein caused a more pronounced decrease in the activity of NAD(+)-dependent dehydrogenases studied and a 2.2-fold increase of the mitochondrial NAD(+)/NADН ratio. This suggests that alimentary protein deprivation potentiated drug-induced liver damage.
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Affiliation(s)
- O N Voloshchuk
- Fedkovych Chernovtsi National University, Chernovtsi, Ukraine
| | - G P Kopylchuk
- Fedkovych Chernovtsi National University, Chernovtsi, Ukraine
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37
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Doczi J, Torocsik B, Echaniz-Laguna A, Mousson de Camaret B, Starkov A, Starkova N, Gál A, Molnár MJ, Kawamata H, Manfredi G, Adam-Vizi V, Chinopoulos C. Alterations in voltage-sensing of the mitochondrial permeability transition pore in ANT1-deficient cells. Sci Rep 2016; 6:26700. [PMID: 27221760 PMCID: PMC4879635 DOI: 10.1038/srep26700] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2015] [Accepted: 05/09/2016] [Indexed: 01/03/2023] Open
Abstract
The probability of mitochondrial permeability transition (mPT) pore opening is inversely related to the magnitude of the proton electrochemical gradient. The module conferring sensitivity of the pore to this gradient has not been identified. We investigated mPT’s voltage-sensing properties elicited by calcimycin or H2O2 in human fibroblasts exhibiting partial or complete lack of ANT1 and in C2C12 myotubes with knocked-down ANT1 expression. mPT onset was assessed by measuring in situ mitochondrial volume using the ‘thinness ratio’ and the ‘cobalt-calcein’ technique. De-energization hastened calcimycin-induced swelling in control and partially-expressing ANT1 fibroblasts, but not in cells lacking ANT1, despite greater losses of mitochondrial membrane potential. Matrix Ca2+ levels measured by X-rhod-1 or mitochondrially-targeted ratiometric biosensor 4mtD3cpv, or ADP-ATP exchange rates did not differ among cell types. ANT1-null fibroblasts were also resistant to H2O2-induced mitochondrial swelling. Permeabilized C2C12 myotubes with knocked-down ANT1 exhibited higher calcium uptake capacity and voltage-thresholds of mPT opening inferred from cytochrome c release, but intact cells showed no differences in calcimycin-induced onset of mPT, irrespective of energization and ANT1 expression, albeit the number of cells undergoing mPT increased less significantly upon chemically-induced hypoxia than control cells. We conclude that ANT1 confers sensitivity of the pore to the electrochemical gradient.
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Affiliation(s)
- Judit Doczi
- Department of Medical Biochemistry, Semmelweis University MTA-SE Laboratory for Neurobiochemistry, Budapest, 1094, Hungary.,MTA-SE Lendület Neurobiochemistry Research Group, Budapest, Hungary
| | - Beata Torocsik
- Department of Medical Biochemistry, Semmelweis University MTA-SE Laboratory for Neurobiochemistry, Budapest, 1094, Hungary
| | - Andoni Echaniz-Laguna
- Département de Neurologie, Hôpitaux Universitaires, Hôpital de Hautepierre, 67098 Strasbourg cedex, France
| | - Bénédicte Mousson de Camaret
- Service des Maladies Héréditaires du Métabolisme, Centre de Biologie et de Pathologie Est, CHU Lyon, 69677 Bron cedex, France
| | - Anatoly Starkov
- Feil Family Brain and Mind Research Institute, Weill Cornell Medical College, New York, NY 10065, USA
| | - Natalia Starkova
- Icahn School of Medicine at Mount Sinai, Department of Hematology and Medical Oncology, New York, NY 10029, USA
| | - Aniko Gál
- Institute of Genomic Medicine and Rare Disorders, Semmelweis University, Budapest, 1083, Hungary
| | - Mária J Molnár
- Institute of Genomic Medicine and Rare Disorders, Semmelweis University, Budapest, 1083, Hungary
| | - Hibiki Kawamata
- Feil Family Brain and Mind Research Institute, Weill Cornell Medical College, New York, NY 10065, USA
| | - Giovanni Manfredi
- Feil Family Brain and Mind Research Institute, Weill Cornell Medical College, New York, NY 10065, USA
| | - Vera Adam-Vizi
- Department of Medical Biochemistry, Semmelweis University MTA-SE Laboratory for Neurobiochemistry, Budapest, 1094, Hungary
| | - Christos Chinopoulos
- Department of Medical Biochemistry, Semmelweis University MTA-SE Laboratory for Neurobiochemistry, Budapest, 1094, Hungary.,MTA-SE Lendület Neurobiochemistry Research Group, Budapest, Hungary
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38
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Cancer Stem Cells in Small Cell Lung Cancer Cell Line H446: Higher Dependency on Oxidative Phosphorylation and Mitochondrial Substrate-Level Phosphorylation than Non-Stem Cancer Cells. PLoS One 2016; 11:e0154576. [PMID: 27167619 PMCID: PMC4863974 DOI: 10.1371/journal.pone.0154576] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Accepted: 04/15/2016] [Indexed: 02/07/2023] Open
Abstract
Recently, targeting cancer stem cells (CSCs) metabolism is becoming a promising therapeutic approach to improve cancer treatment outcomes. However, knowledge of the metabolic state of CSCs in small cell lung cancer is still lacking. In this study, we found that CSCs had significantly lower oxygen consumption rate and extracellular acidification rate than non-stem cancer cells. Meanwhile, this subpopulation of cells consumed less glucose, produced less lactate and maintained lower ATP levels. We also revealed that CSCs could produce more ATP through mitochondrial substrate-level phosphorylation during respiratory inhibition compared with non-stem cancer cells. Furthermore, they were more sensitive to suppression of oxidative phosphorylation. Therefore, oligomycin (inhibitor of oxidative phosphorylation) could severely impair sphere-forming and tumor-initiating abilities of CSCs. Our work suggests that CSCs represent metabolically inactive tumor subpopulations which sustain in a state showing low metabolic activity. However, mitochondrial substrate-level phosphorylation of CSCs may be more active than that of non-stem cancer cells. Moreover, CSCs showed preferential use of oxidative phosphorylation over glycolysis to meet their energy demand. These results extend our understanding of CSCs metabolism, potentially providing novel treatment strategies targeting metabolic pathways in small cell lung cancer.
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Succinate, an intermediate in metabolism, signal transduction, ROS, hypoxia, and tumorigenesis. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2016; 1857:1086-1101. [PMID: 26971832 DOI: 10.1016/j.bbabio.2016.03.012] [Citation(s) in RCA: 318] [Impact Index Per Article: 39.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Revised: 03/06/2016] [Accepted: 03/07/2016] [Indexed: 12/31/2022]
Abstract
Succinate is an important metabolite at the cross-road of several metabolic pathways, also involved in the formation and elimination of reactive oxygen species. However, it is becoming increasingly apparent that its realm extends to epigenetics, tumorigenesis, signal transduction, endo- and paracrine modulation and inflammation. Here we review the pathways encompassing succinate as a metabolite or a signal and how these may interact in normal and pathological conditions.(1).
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Nijland PG, Molenaar RJ, van der Pol SMA, van der Valk P, van Noorden CJF, de Vries HE, van Horssen J. Differential expression of glucose-metabolizing enzymes in multiple sclerosis lesions. Acta Neuropathol Commun 2015; 3:79. [PMID: 26637184 PMCID: PMC4670517 DOI: 10.1186/s40478-015-0261-8] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2015] [Accepted: 11/22/2015] [Indexed: 02/06/2023] Open
Abstract
Introduction Demyelinated axons in multiple sclerosis (MS) lesions have an increased energy demand in order to maintain conduction. However, oxidative stress-induced mitochondrial dysfunction likely alters glucose metabolism and consequently impairs neuronal function in MS. Imaging and pathological studies indicate that glucose metabolism is altered in MS, although the underlying mechanisms and its role in neurodegeneration remain elusive. We investigated expression patterns of key enzymes involved in glycolysis, tricarboxylic acid (TCA) cycle and lactate metabolism in well-characterized MS tissue to establish which regulators of glucose metabolism are involved in MS and to identify underlying mechanisms. Results Expression levels of glycolytic enzymes were increased in active and inactive MS lesions, whereas expression levels of enzymes involved in the TCA cycle were upregulated in active MS lesions, but not in inactive MS lesions. We observed reduced expression and production capacity of mitochondrial α-ketoglutarate dehydrogenase (αKGDH) in demyelinated axons, which correlated with signs of axonal dysfunction. In inactive lesions, increased expression of lactate-producing enzymes was observed in astrocytes, whereas lactate-catabolising enzymes were mainly detected in axons. Our results demonstrate that the expression of various enzymes involved in glucose metabolism is increased in both astrocytes and axons in active MS lesions. In inactive MS lesions, we provide evidence that astrocytes undergo a glycolytic shift resulting in enhanced astrocyte-axon lactate shuttling, which may be pivotal for the survival of demyelinated axons. Conclusion In conclusion, we show that key enzymes involved in energy metabolism are differentially expressed in active and inactive MS lesions. Our findings imply that, in addition to reduced oxidative phosphorylation activity, other bioenergetic pathways are affected as well, which may contribute to ongoing axonal degeneration in MS. Electronic supplementary material The online version of this article (doi:10.1186/s40478-015-0261-8) contains supplementary material, which is available to authorized users.
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Guo H, Madzak C, Du G, Zhou J. Mutagenesis of conserved active site residues of dihydrolipoamide succinyltransferase enhances the accumulation of α-ketoglutarate in Yarrowia lipolytica. Appl Microbiol Biotechnol 2015; 100:649-59. [PMID: 26428234 DOI: 10.1007/s00253-015-6995-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Revised: 08/30/2015] [Accepted: 09/08/2015] [Indexed: 11/30/2022]
Abstract
α-Ketoglutarate (α-KG) is an important intermediate in the tricarboxylic acid cycle and has broad applications. The mitochondrial ketoglutarate dehydrogenase (KGDH) complex catalyzes the oxidation of α-KG to succinyl-CoA. Disruption of KGDH, which may enhance the accumulation of α-KG theoretically, was found to be lethal to obligate aerobic cells. In this study, individual overexpression of dihydrolipoamide succinyltransferase (DLST), which serves as the inner core of KGDH, decreased overall activity of the enzyme complex. Furthermore, two conserved active site residues of DLST, His419, and Asp423 were identified. In order to determine whether these residues are engaged in enzyme reaction or not, these two conserved residues were individually mutated. Analysis of the kinetic parameters of the enzyme variants provided evidence that the catalytic reaction of DLST depended on residues His419 and Asp423. Overexpression of mutated DLST not only impaired balanced assembly of KGDH, but also disrupted the catalytic integrity of the enzyme complex. Replacement of the Asp423 residue by glutamate increased extracellular α-KG by 40 % to 50 g L(-1) in mutant strain. These observations uncovered catalytic roles of two conserved active site residues of DLST and provided clues for effective metabolic strategies for rational carbon flux control for the enhanced production of α-KG and related bioproducts.
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Affiliation(s)
- Hongwei Guo
- School of Biotechnology and Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, Jiangsu, China.,Synergetic Innovation Center of Food Safety and Nutrition, 1800 Lihu Road, Wuxi, 214122, Jiangsu, China
| | - Catherine Madzak
- UMR1238 Microbiologie et Génétique Moléculaire, INRA/CNRS/AgroPan's Tech, CBAI, BP 01, 78850, Thiverval-Grignon, France
| | - Guocheng Du
- School of Biotechnology and Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, Jiangsu, China.,Synergetic Innovation Center of Food Safety and Nutrition, 1800 Lihu Road, Wuxi, 214122, Jiangsu, China
| | - Jingwen Zhou
- School of Biotechnology and Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, Jiangsu, China. .,Synergetic Innovation Center of Food Safety and Nutrition, 1800 Lihu Road, Wuxi, 214122, Jiangsu, China.
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Németh B, Doczi J, Csete D, Kacso G, Ravasz D, Adams D, Kiss G, Nagy AM, Horvath G, Tretter L, Mócsai A, Csépányi-Kömi R, Iordanov I, Adam-Vizi V, Chinopoulos C. Abolition of mitochondrial substrate-level phosphorylation by itaconic acid produced by LPS-induced Irg1 expression in cells of murine macrophage lineage. FASEB J 2015; 30:286-300. [PMID: 26358042 DOI: 10.1096/fj.15-279398] [Citation(s) in RCA: 92] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Accepted: 08/31/2015] [Indexed: 01/28/2023]
Abstract
Itaconate is a nonamino organic acid exhibiting antimicrobial effects. It has been recently identified in cells of macrophage lineage as a product of an enzyme encoded by immunoresponsive gene 1 (Irg1), acting on the citric acid cycle intermediate cis-aconitate. In mitochondria, itaconate can be converted by succinate-coenzyme A (CoA) ligase to itaconyl-CoA at the expense of ATP (or GTP), and is also a weak competitive inhibitor of complex II. Here, we investigated specific bioenergetic effects of increased itaconate production mediated by LPS-induced stimulation of Irg1 in murine bone marrow-derived macrophages (BMDM) and RAW-264.7 cells. In rotenone-treated macrophage cells, stimulation by LPS led to impairment in substrate-level phosphorylation (SLP) of in situ mitochondria, deduced by a reversal in the directionality of the adenine nucleotide translocase operation. In RAW-264.7 cells, the LPS-induced impairment in SLP was reversed by short-interfering RNA(siRNA)-but not scrambled siRNA-treatment directed against Irg1. LPS dose-dependently inhibited oxygen consumption rates (61-91%) and elevated glycolysis rates (>21%) in BMDM but not RAW-264.7 cells, studied under various metabolic conditions. In isolated mouse liver mitochondria treated with rotenone, itaconate dose-dependently (0.5-2 mM) reversed the operation of adenine nucleotide translocase, implying impairment in SLP, an effect that was partially mimicked by malonate. However, malonate yielded greater ADP-induced depolarizations (3-19%) than itaconate. We postulate that itaconate abolishes SLP due to 1) a "CoA trap" in the form of itaconyl-CoA that negatively affects the upstream supply of succinyl-CoA from the α-ketoglutarate dehydrogenase complex; 2) depletion of ATP (or GTP), which are required for the thioesterification by succinate-CoA ligase; and 3) inhibition of complex II leading to a buildup of succinate which shifts succinate-CoA ligase equilibrium toward ATP (or GTP) utilization. Our results support the notion that Irg1-expressing cells of macrophage lineage lose the capacity of mitochondrial SLP for producing itaconate during mounting of an immune defense.
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Affiliation(s)
- Beáta Németh
- *Department of Medical Biochemistry and Department of Physiology, Semmelweis University, Budapest, Hungary; and Lendület Neurobiochemistry Research Group, Lendület Inflammation Physiology Research Group, Laboratory for Neurobiochemistry, and Lendület Ion Channel Research Group, Hungarian Academy of Sciences, Budapest, Hungary
| | - Judit Doczi
- *Department of Medical Biochemistry and Department of Physiology, Semmelweis University, Budapest, Hungary; and Lendület Neurobiochemistry Research Group, Lendület Inflammation Physiology Research Group, Laboratory for Neurobiochemistry, and Lendület Ion Channel Research Group, Hungarian Academy of Sciences, Budapest, Hungary
| | - Dániel Csete
- *Department of Medical Biochemistry and Department of Physiology, Semmelweis University, Budapest, Hungary; and Lendület Neurobiochemistry Research Group, Lendület Inflammation Physiology Research Group, Laboratory for Neurobiochemistry, and Lendület Ion Channel Research Group, Hungarian Academy of Sciences, Budapest, Hungary
| | - Gergely Kacso
- *Department of Medical Biochemistry and Department of Physiology, Semmelweis University, Budapest, Hungary; and Lendület Neurobiochemistry Research Group, Lendület Inflammation Physiology Research Group, Laboratory for Neurobiochemistry, and Lendület Ion Channel Research Group, Hungarian Academy of Sciences, Budapest, Hungary
| | - Dora Ravasz
- *Department of Medical Biochemistry and Department of Physiology, Semmelweis University, Budapest, Hungary; and Lendület Neurobiochemistry Research Group, Lendület Inflammation Physiology Research Group, Laboratory for Neurobiochemistry, and Lendület Ion Channel Research Group, Hungarian Academy of Sciences, Budapest, Hungary
| | - Daniel Adams
- *Department of Medical Biochemistry and Department of Physiology, Semmelweis University, Budapest, Hungary; and Lendület Neurobiochemistry Research Group, Lendület Inflammation Physiology Research Group, Laboratory for Neurobiochemistry, and Lendület Ion Channel Research Group, Hungarian Academy of Sciences, Budapest, Hungary
| | - Gergely Kiss
- *Department of Medical Biochemistry and Department of Physiology, Semmelweis University, Budapest, Hungary; and Lendület Neurobiochemistry Research Group, Lendület Inflammation Physiology Research Group, Laboratory for Neurobiochemistry, and Lendület Ion Channel Research Group, Hungarian Academy of Sciences, Budapest, Hungary
| | - Adam M Nagy
- *Department of Medical Biochemistry and Department of Physiology, Semmelweis University, Budapest, Hungary; and Lendület Neurobiochemistry Research Group, Lendület Inflammation Physiology Research Group, Laboratory for Neurobiochemistry, and Lendület Ion Channel Research Group, Hungarian Academy of Sciences, Budapest, Hungary
| | - Gergo Horvath
- *Department of Medical Biochemistry and Department of Physiology, Semmelweis University, Budapest, Hungary; and Lendület Neurobiochemistry Research Group, Lendület Inflammation Physiology Research Group, Laboratory for Neurobiochemistry, and Lendület Ion Channel Research Group, Hungarian Academy of Sciences, Budapest, Hungary
| | - Laszlo Tretter
- *Department of Medical Biochemistry and Department of Physiology, Semmelweis University, Budapest, Hungary; and Lendület Neurobiochemistry Research Group, Lendület Inflammation Physiology Research Group, Laboratory for Neurobiochemistry, and Lendület Ion Channel Research Group, Hungarian Academy of Sciences, Budapest, Hungary
| | - Attila Mócsai
- *Department of Medical Biochemistry and Department of Physiology, Semmelweis University, Budapest, Hungary; and Lendület Neurobiochemistry Research Group, Lendület Inflammation Physiology Research Group, Laboratory for Neurobiochemistry, and Lendület Ion Channel Research Group, Hungarian Academy of Sciences, Budapest, Hungary
| | - Roland Csépányi-Kömi
- *Department of Medical Biochemistry and Department of Physiology, Semmelweis University, Budapest, Hungary; and Lendület Neurobiochemistry Research Group, Lendület Inflammation Physiology Research Group, Laboratory for Neurobiochemistry, and Lendület Ion Channel Research Group, Hungarian Academy of Sciences, Budapest, Hungary
| | - Iordan Iordanov
- *Department of Medical Biochemistry and Department of Physiology, Semmelweis University, Budapest, Hungary; and Lendület Neurobiochemistry Research Group, Lendület Inflammation Physiology Research Group, Laboratory for Neurobiochemistry, and Lendület Ion Channel Research Group, Hungarian Academy of Sciences, Budapest, Hungary
| | - Vera Adam-Vizi
- *Department of Medical Biochemistry and Department of Physiology, Semmelweis University, Budapest, Hungary; and Lendület Neurobiochemistry Research Group, Lendület Inflammation Physiology Research Group, Laboratory for Neurobiochemistry, and Lendület Ion Channel Research Group, Hungarian Academy of Sciences, Budapest, Hungary
| | - Christos Chinopoulos
- *Department of Medical Biochemistry and Department of Physiology, Semmelweis University, Budapest, Hungary; and Lendület Neurobiochemistry Research Group, Lendület Inflammation Physiology Research Group, Laboratory for Neurobiochemistry, and Lendület Ion Channel Research Group, Hungarian Academy of Sciences, Budapest, Hungary
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Scheffler TL, Matarneh SK, England EM, Gerrard DE. Mitochondria influence postmortem metabolism and pH in an in vitro model. Meat Sci 2015. [PMID: 26209819 DOI: 10.1016/j.meatsci.2015.07.007] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Our objective was to determine the influence of mitochondria on metabolites and pH decline using an in vitro model of postmortem muscle metabolism. Mitochondria were isolated from porcine longissimus lumborum and added (0, 0.5, or 2.0mg) to powdered muscle in reaction media containing either a combination of inhibitors for mitochondria complexes (I, IV, and V) or diluent (without inhibitors). In the absence of inhibitors, adding mitochondria (0.5 and 2.0mg) reduced ATP loss from 30 to 120 min, but did not alter glycogen or lactate during this time. In reactions with mitochondria, inhibitors decreased ATP levels by 30 min and increased glycogen degradation by 60 min. Regardless of mitochondria content, inhibitors enhanced lactate accumulation from 15 to 240 min, and decreased pH from 15 min to 1440 min. In the in vitro model, mitochondria influence the maintenance of ATP, and inhibition of mitochondria enzyme activity contributes to accelerated metabolism and pH decline.
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Affiliation(s)
- Tracy L Scheffler
- Department of Animal and Poultry Sciences, Virginia Tech, Blacksburg, VA 24061, USA
| | - Sulaiman K Matarneh
- Department of Animal and Poultry Sciences, Virginia Tech, Blacksburg, VA 24061, USA
| | - Eric M England
- Department of Animal and Poultry Sciences, Virginia Tech, Blacksburg, VA 24061, USA
| | - David E Gerrard
- Department of Animal and Poultry Sciences, Virginia Tech, Blacksburg, VA 24061, USA.
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Chinopoulos C, Kiss G, Kawamata H, Starkov AA. Measurement of ADP-ATP exchange in relation to mitochondrial transmembrane potential and oxygen consumption. Methods Enzymol 2015; 542:333-48. [PMID: 24862274 DOI: 10.1016/b978-0-12-416618-9.00017-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
We have previously described a fluorometric method to measure ADP-ATP exchange rates in mitochondria of permeabilized cells, in which several enzymes that consume substantial amounts of ATP and other competing reactions interconverting adenine nucleotides are present. This method relies on recording changes in free extramitochondrial Mg(2+) with the Mg(2+)-sensitive fluorescent indicator Magnesium Green (MgGr)™, exploiting the differential affinity of ADP and ATP for Mg(2+). In particular, cells are permeabilized with digitonin in the presence of BeF3(-) and Na3VO4, inhibiting all ATP- and ADP-utilizing reactions but mitochondrial exchange of ATP with ADP catalyzed by the adenine nucleotide translocase. The rate of ATP appearing in the medium upon the addition of ADP to energized mitochondria is then calculated from the rate of change in free extramitochondrial Mg(2+) using standard binding equations. Here, we describe a variant of this method involving an improved calibration step. This step minimizes errors that may be introduced during the conversion of the MgGr™ signal into free extramitochondrial [Mg(2+)] and ATP. Furthermore, we describe an approach for combining this methodology with the measurement of mitochondrial membrane potential and oxygen consumption in the same sample. The method described herein is useful for the study of malignant cells, which are known to thrive in hypoxic environments and to harbor mitochondria with profound functional alterations.
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Affiliation(s)
| | - Gergely Kiss
- Department of Medical Biochemistry, Semmelweis University, Budapest, Hungary
| | - Hibiki Kawamata
- Brain and Mind Research Institute, Weill Medical College of Cornell University, New York, USA
| | - Anatoly A Starkov
- Brain and Mind Research Institute, Weill Medical College of Cornell University, New York, USA
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Bonora M, Wieckowski MR, Chinopoulos C, Kepp O, Kroemer G, Galluzzi L, Pinton P. Molecular mechanisms of cell death: central implication of ATP synthase in mitochondrial permeability transition. Oncogene 2015; 34:1475-86. [PMID: 24727893 DOI: 10.1038/onc.2014.96] [Citation(s) in RCA: 162] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Revised: 02/20/2014] [Accepted: 02/27/2014] [Indexed: 12/14/2022]
Abstract
The term mitochondrial permeability transition (MPT) is commonly used to indicate an abrupt increase in the permeability of the inner mitochondrial membrane to low molecular weight solutes. Widespread MPT has catastrophic consequences for the cell, de facto marking the boundary between cellular life and death. MPT results indeed in the structural and functional collapse of mitochondria, an event that commits cells to suicide via regulated necrosis or apoptosis. MPT has a central role in the etiology of both acute and chronic diseases characterized by the loss of post-mitotic cells. Moreover, cancer cells are often relatively insensitive to the induction of MPT, underlying their increased resistance to potentially lethal cues. Thus, intense efforts have been dedicated not only at the understanding of MPT in mechanistic terms, but also at the development of pharmacological MPT modulators. In this setting, multiple mitochondrial and extramitochondrial proteins have been suspected to critically regulate the MPT. So far, however, only peptidylprolyl isomerase F (best known as cyclophilin D) appears to constitute a key component of the so-called permeability transition pore complex (PTPC), the supramolecular entity that is believed to mediate MPT. Here, after reviewing the structural and functional features of the PTPC, we summarize recent findings suggesting that another of its core components is represented by the c subunit of mitochondrial ATP synthase.
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Affiliation(s)
- M Bonora
- Section of Pathology, Oncology and Experimental Biology, Laboratory for Technologies of Advanced Therapies (LTTA), Department of Morphology, Surgery and Experimental Medicine, Interdisciplinary Centre for the Study of Inflammation (ICSI), University of Ferrara, Ferrara, Italy
| | - M R Wieckowski
- Department of Biochemistry, Nencki Institute of Experimental Biology, Warsaw, Poland
| | - C Chinopoulos
- Department of Medical Biochemistry, Semmelweis University, Budapest, Hungary
| | - O Kepp
- 1] Equipe 11 labelisée par la Ligue Nationale contre le cancer, INSERM U1138, Centre de Recherche des Cordeliers, Paris, France [2] Université Paris Descartes/Paris 5, Sorbonne Paris Cité, Paris, France [3] Metabolomics and Cell Biology platforms, Gustave Roussy Comprehensive Cancer Center, Villejuif, France
| | - G Kroemer
- 1] Equipe 11 labelisée par la Ligue Nationale contre le cancer, INSERM U1138, Centre de Recherche des Cordeliers, Paris, France [2] Université Paris Descartes/Paris 5, Sorbonne Paris Cité, Paris, France [3] Metabolomics and Cell Biology platforms, Gustave Roussy Comprehensive Cancer Center, Villejuif, France [4] Pôle de Biologie, Hôpital Européen Georges Pompidou, AP-HP, Paris, France
| | - L Galluzzi
- 1] Equipe 11 labelisée par la Ligue Nationale contre le cancer, INSERM U1138, Centre de Recherche des Cordeliers, Paris, France [2] Université Paris Descartes/Paris 5, Sorbonne Paris Cité, Paris, France [3] Gustave Roussy Comprehensive Cancer Center, Villejuif, France
| | - P Pinton
- Section of Pathology, Oncology and Experimental Biology, Laboratory for Technologies of Advanced Therapies (LTTA), Department of Morphology, Surgery and Experimental Medicine, Interdisciplinary Centre for the Study of Inflammation (ICSI), University of Ferrara, Ferrara, Italy
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Diaz-Muñoz MD, Bell SE, Fairfax K, Monzon-Casanova E, Cunningham AF, Gonzalez-Porta M, Andrews SR, Bunik VI, Zarnack K, Curk T, Heggermont WA, Heymans S, Gibson GE, Kontoyiannis DL, Ule J, Turner M. The RNA-binding protein HuR is essential for the B cell antibody response. Nat Immunol 2015; 16:415-25. [PMID: 25706746 PMCID: PMC4479220 DOI: 10.1038/ni.3115] [Citation(s) in RCA: 112] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Accepted: 01/28/2015] [Indexed: 12/26/2022]
Abstract
Post-transcriptional regulation of mRNA by the RNA-binding protein HuR (encoded by Elavl1) is required in B cells for the germinal center reaction and for the production of class-switched antibodies in response to thymus-independent antigens. Transcriptome-wide examination of RNA isoforms and their abundance and translation in HuR-deficient B cells, together with direct measurements of HuR-RNA interactions, revealed that HuR-dependent splicing of mRNA affected hundreds of transcripts, including that encoding dihydrolipoamide S-succinyltransferase (Dlst), a subunit of the 2-oxoglutarate dehydrogenase (α-KGDH) complex. In the absence of HuR, defective mitochondrial metabolism resulted in large amounts of reactive oxygen species and B cell death. Our study shows how post-transcriptional processes control the balance of energy metabolism required for the proliferation and differentiation of B cells.
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Affiliation(s)
- Manuel D Diaz-Muñoz
- Laboratory of Lymphocyte Signalling and Development, The Babraham Institute, Cambridge, UK
| | - Sarah E Bell
- Laboratory of Lymphocyte Signalling and Development, The Babraham Institute, Cambridge, UK
| | - Kirsten Fairfax
- 1] Laboratory of Lymphocyte Signalling and Development, The Babraham Institute, Cambridge, UK. [2] The Walter and Eliza Hall Institute of Medical Research, Parkville, Australia
| | - Elisa Monzon-Casanova
- Laboratory of Lymphocyte Signalling and Development, The Babraham Institute, Cambridge, UK
| | - Adam F Cunningham
- MRC Centre for Immune Regulation, Institute of Microbiology and Infection, School of Immunity and Infection, University of Birmingham, Birmingham, UK
| | - Mar Gonzalez-Porta
- European Molecular Biology Laboratory, European Bioinformatics Institute, Wellcome Trust Genome Campus, Cambridge, UK
| | | | - Victoria I Bunik
- A. N. Belozersky Institute of PhysicoChemical Biology and Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, Russia
| | - Kathi Zarnack
- Buchmann Institute for Molecular Life Sciences, Frankfurt, Germany
| | - Tomaž Curk
- University of Ljubljana, Faculty of Computer and Information Science, Ljubljana, Slovenia
| | | | - Stephane Heymans
- 1] Center for Molecular and Vascular Biology, KU Leuven, Belgium. [2] Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, the Netherlands
| | - Gary E Gibson
- Weill Cornell Medical College, Brain and Mind Research Institute, Burke Medical Research Institute, White Plains, New York, USA
| | - Dimitris L Kontoyiannis
- Division of Immunology, Biomedical Sciences Research Center "Alexander Fleming", Vari, Greece
| | - Jernej Ule
- UCL Genetics Institute, Department of Genetics, Environment and Evolution, University College London, London, UK
| | - Martin Turner
- Laboratory of Lymphocyte Signalling and Development, The Babraham Institute, Cambridge, UK
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Mitochondrial engineering of the TCA cycle for fumarate production. Metab Eng 2015; 31:62-73. [PMID: 25708514 DOI: 10.1016/j.ymben.2015.02.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Revised: 12/08/2014] [Accepted: 02/11/2015] [Indexed: 01/07/2023]
Abstract
Microbial fumarate production from renewable feedstock is a promising and sustainable alternative to petroleum-based chemical synthesis. Here, mitochondrial engineering was used to construct the oxidative pathway for fumarate production starting from the TCA cycle intermediate α-ketoglutarate in Candida glabrata. Accordingly, α-ketoglutarate dehydrogenase complex (KGD), succinyl-CoA synthetase (SUCLG), and succinate dehydrogenase (SDH) were selected to be manipulated for strengthening the oxidative pathway, and the engineered strain T.G-K-S-S exhibited increased fumarate biosynthesis (1.81 g L(-1)). To further improve fumarate production, the oxidative route was optimized. First, three fusion proteins KGD2-SUCLG2, SUCLG2-SDH1 and KGD2-SDH1 were constructed, and KGD2-SUCLG2 led to improved fumarate production (4.24 g L(-1)). In addition, various strengths of KGD2-SUCLG2 and SDH1 expression cassettes were designed by combinations of promoter strengths and copy numbers, resulting in a large increase in fumarate production (from 4.24 g L(-1) to 8.24 g L(-1)). Then, through determining intracellular amino acids and its related gene expression levels, argininosuccinate lyase in the urea cycle was identified as the key factor for restricting higher fumarate production. Correspondingly, after overexpression of it, the fumarate production was further increased to 9.96 g L(-1). Next, two dicarboxylic acids transporters facilitated an improvement of fumarate production, and, as a result, the final strain T.G-KS(H)-S(M)-A-2S reached fumarate titer of 15.76 g L(-1). This strategy described here paves the way to the development of an efficient pathway for microbial production of fumarate.
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Localization of SUCLA2 and SUCLG2 subunits of succinyl CoA ligase within the cerebral cortex suggests the absence of matrix substrate-level phosphorylation in glial cells of the human brain. J Bioenerg Biomembr 2014; 47:33-41. [PMID: 25370487 DOI: 10.1007/s10863-014-9586-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Accepted: 09/21/2014] [Indexed: 10/24/2022]
Abstract
We have recently shown that the ATP-forming SUCLA2 subunit of succinyl-CoA ligase, an enzyme of the citric acid cycle, is exclusively expressed in neurons of the human cerebral cortex; GFAP- and S100-positive astroglial cells did not exhibit immunohistoreactivity or in situ hybridization reactivity for either SUCLA2 or the GTP-forming SUCLG2. However, Western blotting of post mortem samples revealed a minor SUCLG2 immunoreactivity. In the present work we sought to identify the cell type(s) harboring SUCLG2 in paraformaldehyde-fixed, free-floating surgical human cortical tissue samples. Specificity of SUCLG2 antiserum was supported by co-localization with mitotracker orange staining of paraformaldehyde-fixed human fibroblast cultures, delineating the mitochondrial network. In human cortical tissue samples, microglia and oligodendroglia were identified by antibodies directed against Iba1 and myelin basic protein, respectively. Double immunofluorescence for SUCLG2 and Iba1 or myelin basic protein exhibited no co-staining; instead, SUCLG2 appeared to outline the cerebral microvasculature. In accordance to our previous work there was no co-localization of SUCLA2 immunoreactivity with either Iba1 or myelin basic protein. We conclude that SUCLG2 exist only in cells forming the vasculature or its contents in the human brain. The absence of SUCLA2 and SUCLG2 in human glia is in compliance with the presence of alternative pathways occurring in these cells, namely the GABA shunt and ketone body metabolism which do not require succinyl CoA ligase activity, and glutamate dehydrogenase 1, an enzyme exhibiting exquisite sensitivity to inhibition by GTP.
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Kiss G, Konrad C, Pour-Ghaz I, Mansour JJ, Németh B, Starkov AA, Adam-Vizi V, Chinopoulos C. Mitochondrial diaphorases as NAD⁺ donors to segments of the citric acid cycle that support substrate-level phosphorylation yielding ATP during respiratory inhibition. FASEB J 2014; 28:1682-97. [PMID: 24391134 DOI: 10.1096/fj.13-243030] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Substrate-level phosphorylation mediated by succinyl-CoA ligase in the mitochondrial matrix produces high-energy phosphates in the absence of oxidative phosphorylation. Furthermore, when the electron transport chain is dysfunctional, provision of succinyl-CoA by the α-ketoglutarate dehydrogenase complex (KGDHC) is crucial for maintaining the function of succinyl-CoA ligase yielding ATP, preventing the adenine nucleotide translocase from reversing. We addressed the source of the NAD(+) supply for KGDHC under anoxic conditions and inhibition of complex I. Using pharmacologic tools and specific substrates and by examining tissues from pigeon liver exhibiting no diaphorase activity, we showed that mitochondrial diaphorases in the mouse liver contribute up to 81% to the NAD(+) pool during respiratory inhibition. Under these conditions, KGDHC's function, essential for the provision of succinyl-CoA to succinyl-CoA ligase, is supported by NAD(+) derived from diaphorases. Through this process, diaphorases contribute to the maintenance of substrate-level phosphorylation during respiratory inhibition, which is manifested in the forward operation of adenine nucleotide translocase. Finally, we show that reoxidation of the reducible substrates for the diaphorases is mediated by complex III of the respiratory chain.
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Affiliation(s)
- Gergely Kiss
- 1Department of Medical Biochemistry, Semmelweis University, 37-47 Tuzolto Street, Budapest 1094, Hungary.
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Dobolyi A, Ostergaard E, Bagó AG, Dóczi T, Palkovits M, Gál A, Molnár MJ, Adam-Vizi V, Chinopoulos C. Exclusive neuronal expression of SUCLA2 in the human brain. Brain Struct Funct 2013; 220:135-51. [PMID: 24085565 DOI: 10.1007/s00429-013-0643-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Accepted: 09/18/2013] [Indexed: 11/24/2022]
Abstract
SUCLA2 encodes the ATP-forming β subunit (A-SUCL-β) of succinyl-CoA ligase, an enzyme of the citric acid cycle. Mutations in SUCLA2 lead to a mitochondrial disorder manifesting as encephalomyopathy with dystonia, deafness and lesions in the basal ganglia. Despite the distinct brain pathology associated with SUCLA2 mutations, the precise localization of SUCLA2 protein has never been investigated. Here, we show that immunoreactivity of A-SUCL-β in surgical human cortical tissue samples was present exclusively in neurons, identified by their morphology and visualized by double labeling with a fluorescent Nissl dye. A-SUCL-β immunoreactivity co-localized >99 % with that of the d subunit of the mitochondrial F0-F1 ATP synthase. Specificity of the anti-A-SUCL-β antiserum was verified by the absence of labeling in fibroblasts from a patient with a complete deletion of SUCLA2. A-SUCL-β immunoreactivity was absent in glial cells, identified by antibodies directed against the glial markers GFAP and S100. Furthermore, in situ hybridization histochemistry demonstrated that SUCLA2 mRNA was present in Nissl-labeled neurons but not glial cells labeled with S100. Immunoreactivity of the GTP-forming β subunit (G-SUCL-β) encoded by SUCLG2, or in situ hybridization histochemistry for SUCLG2 mRNA could not be demonstrated in either neurons or astrocytes. Western blotting of post mortem brain samples revealed minor G-SUCL-β immunoreactivity that was, however, not upregulated in samples obtained from diabetic versus non-diabetic patients, as has been described for murine brain. Our work establishes that SUCLA2 is expressed exclusively in neurons in the human cerebral cortex.
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Affiliation(s)
- Arpád Dobolyi
- Department of Anatomy, Histology and Embryology, Semmelweis University, Budapest, 1094, Hungary
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