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Acevedo A, Jones AE, Danna BT, Turner R, Montales KP, Benincá C, Reue K, Shirihai OS, Stiles L, Wallace M, Wang Y, Bertholet AM, Divakaruni AS. The BCKDK inhibitor BT2 is a chemical uncoupler that lowers mitochondrial ROS production and de novo lipogenesis. J Biol Chem 2024; 300:105702. [PMID: 38301896 PMCID: PMC10910128 DOI: 10.1016/j.jbc.2024.105702] [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: 08/15/2023] [Revised: 01/12/2024] [Accepted: 01/23/2024] [Indexed: 02/03/2024] Open
Abstract
Elevated levels of branched chain amino acids (BCAAs) and branched-chain α-ketoacids are associated with cardiovascular and metabolic disease, but the molecular mechanisms underlying a putative causal relationship remain unclear. The branched-chain ketoacid dehydrogenase kinase (BCKDK) inhibitor BT2 (3,6-dichlorobenzo[b]thiophene-2-carboxylic acid) is often used in preclinical models to increase BCAA oxidation and restore steady-state BCAA and branched-chain α-ketoacid levels. BT2 administration is protective in various rodent models of heart failure and metabolic disease, but confoundingly, targeted ablation of Bckdk in specific tissues does not reproduce the beneficial effects conferred by pharmacologic inhibition. Here, we demonstrate that BT2, a lipophilic weak acid, can act as a mitochondrial uncoupler. Measurements of oxygen consumption, mitochondrial membrane potential, and patch-clamp electrophysiology show that BT2 increases proton conductance across the mitochondrial inner membrane independently of its inhibitory effect on BCKDK. BT2 is roughly sixfold less potent than the prototypical uncoupler 2,4-dinitrophenol and phenocopies 2,4-dinitrophenol in lowering de novo lipogenesis and mitochondrial superoxide production. The data suggest that the therapeutic efficacy of BT2 may be attributable to the well-documented effects of mitochondrial uncoupling in alleviating cardiovascular and metabolic disease.
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Affiliation(s)
- Aracely Acevedo
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, Los Angeles, California, USA
| | - Anthony E Jones
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, Los Angeles, California, USA
| | - Bezawit T Danna
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, Los Angeles, California, USA
| | - Rory Turner
- School of Agriculture and Food Science, University College Dublin, Dublin, Ireland
| | - Katrina P Montales
- Department of Medicine, University of California, Los Angeles, Los Angeles, California, USA
| | - Cristiane Benincá
- Department of Medicine, University of California, Los Angeles, Los Angeles, California, USA
| | - Karen Reue
- Department of Human Genetics, University of California, Los Angeles, Los Angeles, California, USA
| | - Orian S Shirihai
- Department of Medicine, University of California, Los Angeles, Los Angeles, California, USA
| | - Linsey Stiles
- Department of Medicine, University of California, Los Angeles, Los Angeles, California, USA
| | - Martina Wallace
- School of Agriculture and Food Science, University College Dublin, Dublin, Ireland
| | - Yibin Wang
- DukeNUS School of Medicine, Signature Research Program in Cardiovascular and Metabolic Diseases, Singapore, Singapore
| | - Ambre M Bertholet
- Department of Physiology, University of California, Los Angeles, Los Angeles, California, USA
| | - Ajit S Divakaruni
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, Los Angeles, California, USA.
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2
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Acevedo A, Jones AE, Danna BT, Turner R, Montales KP, Benincá C, Reue K, Shirihai OS, Stiles L, Wallace M, Wang Y, Bertholet AM, Divakaruni AS. The BCKDK inhibitor BT2 is a chemical uncoupler that lowers mitochondrial ROS production and de novo lipogenesis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.15.553413. [PMID: 37645724 PMCID: PMC10461965 DOI: 10.1101/2023.08.15.553413] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
Elevated levels of branched chain amino acids (BCAAs) and branched-chain α-ketoacids (BCKAs) are associated with cardiovascular and metabolic disease, but the molecular mechanisms underlying a putative causal relationship remain unclear. The branched-chain ketoacid dehydrogenase kinase (BCKDK) inhibitor BT2 is often used in preclinical models to increase BCAA oxidation and restore steady-state BCAA and BCKA levels. BT2 administration is protective in various rodent models of heart failure and metabolic disease, but confoundingly, targeted ablation of Bckdk in specific tissues does not reproduce the beneficial effects conferred by pharmacologic inhibition. Here we demonstrate that BT2, a lipophilic weak acid, can act as a mitochondrial uncoupler. Measurements of oxygen consumption, mitochondrial membrane potential, and patch-clamp electrophysiology show BT2 increases proton conductance across the mitochondrial inner membrane independently of its inhibitory effect on BCKDK. BT2 is roughly five-fold less potent than the prototypical uncoupler 2,4-dinitrophenol (DNP), and phenocopies DNP in lowering de novo lipogenesis and mitochondrial superoxide production. The data suggest the therapeutic efficacy of BT2 may be attributable to the well-documented effects of mitochondrial uncoupling in alleviating cardiovascular and metabolic disease.
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Affiliation(s)
- Aracely Acevedo
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, Los Angeles, CA, USA
| | - Anthony E Jones
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, Los Angeles, CA, USA
| | - Bezawit T Danna
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, Los Angeles, CA, USA
| | - Rory Turner
- School of Agriculture and Food Science, University College Dublin, Dublin, Ireland
| | - Katrina P Montales
- Department of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Cristiane Benincá
- Department of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Karen Reue
- Department of Human Genetics, University of California, Los Angeles, Los Angeles, CA, USA
| | - Orian S Shirihai
- Department of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Linsey Stiles
- Department of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Martina Wallace
- School of Agriculture and Food Science, University College Dublin, Dublin, Ireland
| | - Yibin Wang
- DukeNUS School of Medicine, Signature Research Program in Cardiovascular and Metabolic Diseases, 8 College Road, Mail Code 169857, Singapore
| | - Ambre M Bertholet
- Department of Physiology, University of California, Los Angeles, Los Angeles, CA, USA
| | - Ajit S Divakaruni
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, Los Angeles, CA, USA
- Lead contact
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3
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Qi X, Rusch NJ, Fan J, Mora CJ, Xie L, Mu S, Rabinovitch PS, Zhang H. Mitochondrial proton leak in cardiac aging. GeroScience 2023; 45:2135-2143. [PMID: 36856945 PMCID: PMC10651624 DOI: 10.1007/s11357-023-00757-x] [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: 01/10/2023] [Accepted: 02/16/2023] [Indexed: 03/02/2023] Open
Abstract
Age-associated diseases are becoming progressively more prevalent, reflecting the increased lifespan of the world's population. However, the fundamental mechanisms of physiologic aging are poorly understood, and in particular, the molecular pathways that mediate cardiac aging and its associated dysfunction are unclear. Here, we focus on certain ion flux abnormalities of the mitochondria that may contribute to cardiac aging and age-related heart failure. Using oxidative phosphorylation, mitochondria pump protons from the matrix to the intermembrane space to generate a proton gradient across the inner membrane. The protons are returned to the matrix by the ATPase complex within the membrane to generate ATP. However, a portion of protons leak back to the matrix and do not drive ATP production, and this event is called proton leak or uncoupling. Accumulating evidence suggests that mitochondrial proton leak is increased in the cardiac myocytes of aged hearts. In this mini-review, we discuss the measurement methods and major sites of mitochondrial proton leak with an emphasis on the adenine nucleotide transporter 1 (ANT1), and explore the possibility of inhibiting augmented mitochondrial proton leak as a therapeutic intervention to mitigate cardiac aging.
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Affiliation(s)
- Xingyun Qi
- Department of Biology, Rutgers University, Camden, USA
| | - Nancy J Rusch
- Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock, USA
| | - Jiaojiao Fan
- Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock, USA
| | - Christoph J Mora
- Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock, USA
| | - Lixin Xie
- Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock, USA
| | - Shengyu Mu
- Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock, USA
| | - Peter S Rabinovitch
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, USA.
| | - Huiliang Zhang
- Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock, USA.
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4
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Esparza-Perusquía M, Langner T, García-Cruz G, Feldbrügge M, Zavala G, Pardo JP, Martínez F, Flores-Herrera O. Deletion of the ATP20 gene in Ustilago maydis produces an unstable dimer of F 1F O-ATP synthase associated with a decrease in mitochondrial ATP synthesis and a high H 2O 2 production. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2023; 1864:148950. [PMID: 36509127 DOI: 10.1016/j.bbabio.2022.148950] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 11/07/2022] [Accepted: 12/02/2022] [Indexed: 12/13/2022]
Abstract
The F1FO-ATP synthase uses the energy stored in the electrochemical proton gradient to synthesize ATP. This complex is found in the inner mitochondrial membrane as a monomer and dimer. The dimer shows higher ATPase activity than the monomer and is essential for cristae folding. The monomer-monomer interface is constituted by subunits a, i/j, e, g, and k. The role of the subunit g in a strict respiratory organism is unknown. A gene knockout was generated in Ustilago maydis to study the role of subunit g on mitochondrial metabolism and cristae architecture. Deletion of the ATP20 gene, encoding the g subunit, did not affect cell growth or glucose consumption, but biomass production was lower in the mutant strain (gΔ strain). Ultrastructure observations showed that mitochondrial size and cristae shape were similar in wild-type and gΔ strains. The mitochondrial membrane potential in both strains had a similar magnitude, but oxygen consumption was higher in the WT strain. ATP synthesis was 20 % lower in the gΔ strain. Additionally, the mutant strain expressed the alternative oxidase in the early stages of growth (exponential phase), probably as a response to ROS stress. Dimer from mutant strain was unstable to digitonin solubilization, avoiding its isolation and kinetic characterization. The isolated monomeric state activated by n-dodecyl-β-D-maltopyranoside showed similar kinetic constants to the monomer from the WT strain. A decrease in mitochondrial ATP synthesis and the presence of the AOX during the exponential growth phase suggests that deletion of the g gene induces ROS stress.
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Affiliation(s)
- Mercedes Esparza-Perusquía
- Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México, Apartado Postal 70-159, Coyoacán, 04510 México, D. F., Mexico
| | - Thorsten Langner
- Institute for Microbiology, Cluster of Excellence on Plant Sciences, Department of Biology, Heinrich-Heine University Düsseldorf, Düsseldorf, Germany; The Sainsbury Laboratory, Norwich Research Park, Norwich NR4 7UH, United Kingdom
| | - Giovanni García-Cruz
- Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México, Apartado Postal 70-159, Coyoacán, 04510 México, D. F., Mexico
| | - Michael Feldbrügge
- The Sainsbury Laboratory, Norwich Research Park, Norwich NR4 7UH, United Kingdom
| | - Guadalupe Zavala
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001 Chamilpa, 62210 Cuernavaca, Morelos, Mexico
| | - Juan Pablo Pardo
- Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México, Apartado Postal 70-159, Coyoacán, 04510 México, D. F., Mexico
| | - Federico Martínez
- Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México, Apartado Postal 70-159, Coyoacán, 04510 México, D. F., Mexico
| | - Oscar Flores-Herrera
- Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México, Apartado Postal 70-159, Coyoacán, 04510 México, D. F., Mexico.
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5
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Goncalves RLS, Wang ZB, Inouye KE, Lee GY, Fu X, Saksi J, Rosique C, Parlakgul G, Arruda AP, Hui ST, Loperena MC, Burgess SC, Graupera I, Hotamisligil GS. Ubiquinone deficiency drives reverse electron transport to disrupt hepatic metabolic homeostasis in obesity. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.21.528863. [PMID: 36865319 PMCID: PMC9980148 DOI: 10.1101/2023.02.21.528863] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
Mitochondrial reactive oxygen species (mROS) are central to physiology. While excess mROS production has been associated with several disease states, its precise sources, regulation, and mechanism of generation in vivo remain unknown, limiting translational efforts. Here we show that in obesity, hepatic ubiquinone (Q) synthesis is impaired, which raises the QH 2 /Q ratio, driving excessive mROS production via reverse electron transport (RET) from site I Q in complex I. Using multiple complementary genetic and pharmacological models in vivo we demonstrated that RET is critical for metabolic health. In patients with steatosis, the hepatic Q biosynthetic program is also suppressed, and the QH 2 /Q ratio positively correlates with disease severity. Our data identify a highly selective mechanism for pathological mROS production in obesity, which can be targeted to protect metabolic homeostasis.
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6
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Acín-Pérez R, Montales KP, Nguyen KB, Brownstein AJ, Stiles L, Divakaruni AS. Isolation of Mitochondria from Mouse Tissues for Functional Analysis. Methods Mol Biol 2023; 2675:77-96. [PMID: 37258757 PMCID: PMC11105805 DOI: 10.1007/978-1-0716-3247-5_7] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Methods for isolating mitochondria from different rodent tissues have been established for decades. Although the general principles for crude mitochondrial preparations are largely shared across tissues - tissue disruption followed by differential centrifugation - critical differences exist for isolation from different tissues to optimize mitochondrial yield and function. This protocol offers a unified resource for preparations of isolated mitochondria from mouse liver, kidney, heart, brain, skeletal muscle, and brown and white adipose tissue suitable for functional analysis.
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Affiliation(s)
- Rebeca Acín-Pérez
- Department of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Katrina P Montales
- Department of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Kaitlyn B Nguyen
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, Los Angeles, CA, USA
| | | | - Linsey Stiles
- Department of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, Los Angeles, CA, USA
| | - Ajit S Divakaruni
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, Los Angeles, CA, USA.
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7
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Wu H, Wang Y, Ying M, Jin C, Li J, Hu X. Lactate dehydrogenases amplify reactive oxygen species in cancer cells in response to oxidative stimuli. Signal Transduct Target Ther 2021; 6:242. [PMID: 34176927 PMCID: PMC8236487 DOI: 10.1038/s41392-021-00595-3] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Revised: 03/11/2021] [Accepted: 03/30/2021] [Indexed: 12/21/2022] Open
Abstract
Previous studies demonstrated that superoxide could initiate and amplify LDH-catalyzed hydrogen peroxide production in aqueous phase, but its physiological relevance is unknown. Here we showed that LDHA and LDHB both exhibited hydrogen peroxide-producing activity, which was significantly enhanced by the superoxide generated from the isolated mitochondria from HeLa cells and patients’ cholangiocarcinoma specimen. After LDHA or LDHB were knocked out, hydrogen peroxide produced by Hela or 4T1 cancer cells were significantly reduced. Re-expression of LDHA in LDHA-knockout HeLa cells partially restored hydrogen peroxide production. In HeLa and 4T1 cells, LDHA or LDHB knockout or LDH inhibitor FX11 significantly decreased ROS induction by modulators of the mitochondrial electron transfer chain (antimycin, oligomycin, rotenone), hypoxia, and pharmacological ROS inducers piperlogumine (PL) and phenethyl isothiocyanate (PEITC). Moreover, the tumors formed by LDHA or LDHB knockout HeLa or 4T1 cells exhibited a significantly less oxidative state than those formed by control cells. Collectively, we provide a mechanistic understanding of a link between LDH and cellular hydrogen peroxide production or oxidative stress in cancer cells in vitro and in vivo.
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Affiliation(s)
- Hao Wu
- Cancer Institute (Key Laboratory for Cancer Intervention and Prevention, China National Ministry of Education, Zhejiang Provincial Key Laboratory of Molecular Biology in Medical Sciences), The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Yuqi Wang
- Cancer Institute (Key Laboratory for Cancer Intervention and Prevention, China National Ministry of Education, Zhejiang Provincial Key Laboratory of Molecular Biology in Medical Sciences), The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Minfeng Ying
- Cancer Institute (Key Laboratory for Cancer Intervention and Prevention, China National Ministry of Education, Zhejiang Provincial Key Laboratory of Molecular Biology in Medical Sciences), The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Chengmeng Jin
- Cancer Institute (Key Laboratory for Cancer Intervention and Prevention, China National Ministry of Education, Zhejiang Provincial Key Laboratory of Molecular Biology in Medical Sciences), The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Jiangtao Li
- Department of Surgery, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Xun Hu
- Cancer Institute (Key Laboratory for Cancer Intervention and Prevention, China National Ministry of Education, Zhejiang Provincial Key Laboratory of Molecular Biology in Medical Sciences), The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.
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8
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Lucero RA, Mercedes EP, Thorsten L, Giovanni GC, Michael F, Guadalupe Z, Pablo PJ, Federico M, Oscar FH. Deletion of the natural inhibitory protein Inh1 in Ustilago maydis has no effect on the dimeric state of the F 1F O-ATP synthase but increases the ATPase activity and reduces the stability. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2021; 1862:148429. [PMID: 33862003 DOI: 10.1016/j.bbabio.2021.148429] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 03/28/2021] [Accepted: 04/07/2021] [Indexed: 10/21/2022]
Abstract
Transduction of electrochemical proton gradient into ATP synthesis is performed by F1FO-ATP synthase. The reverse reaction is prevented by the regulatory subunit Inh1. Knockout of the inh1 gene in the basidiomycete Ustilago maydis was generated in order to study the function of this protein in the mitochondrial metabolism and cristae architecture. Deletion of inh1 gen did not affect cell growth, glucose consumption, and biomass production. Ultrastructure and fluorescence analyzes showed that size, cristae shape, network, and distribution of mitochondria was similar to wild strain. Membrane potential, ATP synthesis, and oxygen consumption in wild type and mutant strains had similar values. Kinetic analysis of ATPase activity of complex V in permeabilized mitochondria showed similar values of Vmax and KM for both strains, and no effect of pH was observed. Interestingly, the dimeric state of complex V occurs in the mutant strain, indicating that this subunit is not essential for dimerization. ATPase activity of the isolated monomeric and dimeric forms of complex V indicated Vmax values 4-times higher for the mutant strain than for the WT strain, suggesting that the absence of Inh1 subunit increased ATPase activity, and supporting a regulatory role for this protein; however, no effect of pH was observed. ATPase activity of WT oligomers was stimulated several times by dodecyl-maltoside (DDM), probably by removal of ADP from F1 sector, while DDM induced an inactive form of the mutant oligomers.
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Affiliation(s)
- Romero-Aguilar Lucero
- Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México, Apartado Postal 70-159, Coyoacán 04510, México, Mexico
| | - Esparza-Perusquía Mercedes
- Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México, Apartado Postal 70-159, Coyoacán 04510, México, Mexico
| | - Langner Thorsten
- Institute for Microbiology, Cluster of Excellence on Plant Sciences, Department of Biology, Heinrich-Heine University Düsseldorf, Düsseldorf, Germany
| | - García-Cruz Giovanni
- Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México, Apartado Postal 70-159, Coyoacán 04510, México, Mexico
| | - Feldbrügge Michael
- Institute for Microbiology, Cluster of Excellence on Plant Sciences, Department of Biology, Heinrich-Heine University Düsseldorf, Düsseldorf, Germany
| | - Zavala Guadalupe
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001 Chamilpa, 62210, Cuernavaca, Morelos, Mexico
| | - Pardo Juan Pablo
- Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México, Apartado Postal 70-159, Coyoacán 04510, México, Mexico
| | - Martínez Federico
- Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México, Apartado Postal 70-159, Coyoacán 04510, México, Mexico
| | - Flores-Herrera Oscar
- Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México, Apartado Postal 70-159, Coyoacán 04510, México, Mexico.
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9
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Cheng H, Munro D, Huynh K, Pamenter ME. Naked mole-rat skeletal muscle mitochondria exhibit minimal functional plasticity in acute or chronic hypoxia. Comp Biochem Physiol B Biochem Mol Biol 2021; 255:110596. [PMID: 33757832 DOI: 10.1016/j.cbpb.2021.110596] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Revised: 03/11/2021] [Accepted: 03/15/2021] [Indexed: 01/10/2023]
Abstract
Oxidative phosphorylation is compromised in hypoxia, but many organisms live and exercise in low oxygen environments. Hypoxia-driven adaptations at the mitochondrial level are common and may enhance energetic efficiency or minimize deleterious reactive oxygen species (ROS) generation. Mitochondria from various hypoxia-tolerant animals exhibit robust functional changes following in vivo hypoxia and we hypothesized that similar plasticity would occur in naked mole-rat skeletal muscle. To test this, we exposed adult subordinate naked mole-rats to normoxia (21% O2) or acute (4 h, 7% O2) or chronic hypoxia (4-6 weeks, 11% O2) and then isolated skeletal muscle mitochondria. Using high-resolution respirometry and a fluorescent indicator of ROS production, we then probed for changes in: i) lipid- (palmitoylcarnitine-malate), ii) carbohydrate- (pyruvate-malate), and iii) succinate-fueled metabolism, and also iv) complex IV electron transfer capacity, and v) H2O2 production. Compared to normoxic values, a) lipid-fueled uncoupled respiration was reduced ~15% during acute and chronic hypoxia, b) complex I-II capacity and the rate of ROS efflux were both unaffected, and c) complex II and IV uncoupled respiration were supressed ~16% following acute hypoxia. Notably, complex II-linked H2O2 efflux was 33% lower after acute hypoxia, which may reduce deleterious ROS bursts during reoxygenation. These mild changes in lipid- and carbohydrate-fueled respiratory capacity may reflect the need for this animal to exercise regularly in highly variable and intermittently hypoxic environments in which more robust plasticity may be energetically expensive.
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Affiliation(s)
- Hang Cheng
- Department of Biology, University of Ottawa, Ottawa, ON, Canada
| | - Daniel Munro
- Department of Biology, University of Ottawa, Ottawa, ON, Canada
| | - Kenny Huynh
- Department of Biology, University of Ottawa, Ottawa, ON, Canada
| | - Matthew E Pamenter
- Department of Biology, University of Ottawa, Ottawa, ON, Canada; University of Ottawa Brain and Mind Research Institute, Ottawa, ON, Canada.
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10
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Miller VJ, LaFountain RA, Barnhart E, Sapper TS, Short J, Arnold WD, Hyde PN, Crabtree CD, Kackley ML, Kraemer WJ, Villamena FA, Volek JS. A ketogenic diet combined with exercise alters mitochondrial function in human skeletal muscle while improving metabolic health. Am J Physiol Endocrinol Metab 2020; 319:E995-E1007. [PMID: 32985255 DOI: 10.1152/ajpendo.00305.2020] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Animal data indicate that ketogenic diets are associated with improved mitochondrial function, but human data are lacking. We aimed to characterize skeletal muscle mitochondrial changes in response to a ketogenic diet combined with exercise training in healthy individuals. Twenty-nine physically active adults completed a 12-wk supervised exercise program after self-selection into a ketogenic diet (KD, n = 15) group or maintenance of their habitual mixed diet (MD, n = 14). Measures of metabolic health and muscle biopsies (vastus lateralis) were obtained before and after the intervention. Mitochondria were isolated from muscle and studied after exposure to carbohydrate (pyruvate), fat (palmitoyl-l-carnitine), and ketone (β-hydroxybutyrate+acetoacetate) substrates. Compared with MD, the KD resulted in increased whole body resting fat oxidation (P < 0.001) and decreased fasting insulin (P = 0.019), insulin resistance [homeostatic model assessment of insulin resistance (HOMA-IR), P = 0.022], and visceral fat (P < 0.001). The KD altered mitochondrial function as evidenced by increases in mitochondrial respiratory control ratio (19%, P = 0.009), ATP production (36%, P = 0.028), and ATP/H2O2 (36%, P = 0.033) with the fat-based substrate. ATP production with the ketone-based substrate was four to eight times lower than with other substrates, indicating minimal oxidation. The KD resulted in a small decrease in muscle glycogen (14%, P = 0.035) and an increase in muscle triglyceride (81%, P = 0.006). These results expand our understanding of human adaptation to a ketogenic diet combined with exercise. In conjunction with weight loss, we observed altered skeletal muscle mitochondrial function and efficiency, an effect that may contribute to the therapeutic use of ketogenic diets in various clinical conditions, especially those associated with insulin resistance.
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Affiliation(s)
- Vincent J Miller
- OSU Interdisciplinary PhD Program in Nutrition, Department of Human Sciences, The Ohio State University, Columbus, Ohio
| | | | - Emily Barnhart
- Department of Human Sciences, The Ohio State University, Columbus, Ohio
| | - Teryn S Sapper
- Department of Human Sciences, The Ohio State University, Columbus, Ohio
| | - Jay Short
- Department of Human Sciences, The Ohio State University, Columbus, Ohio
| | - W David Arnold
- Department of Neurology, Wexner Medical Center, The Ohio State University, Columbus, Ohio
| | - Parker N Hyde
- Department of Human Sciences, The Ohio State University, Columbus, Ohio
| | | | - Madison L Kackley
- Department of Human Sciences, The Ohio State University, Columbus, Ohio
| | - William J Kraemer
- Department of Human Sciences, The Ohio State University, Columbus, Ohio
| | - Frederick A Villamena
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, Ohio
| | - Jeff S Volek
- OSU Interdisciplinary PhD Program in Nutrition, Department of Human Sciences, The Ohio State University, Columbus, Ohio
- Department of Human Sciences, The Ohio State University, Columbus, Ohio
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11
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Goncalves RLS, Schlame M, Bartelt A, Brand MD, Hotamışlıgil GS. Cardiolipin deficiency in Barth syndrome is not associated with increased superoxide/H 2 O 2 production in heart and skeletal muscle mitochondria. FEBS Lett 2020; 595:415-432. [PMID: 33112430 PMCID: PMC7894513 DOI: 10.1002/1873-3468.13973] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Revised: 09/29/2020] [Accepted: 10/11/2020] [Indexed: 12/11/2022]
Abstract
Barth syndrome (BTHS) is a rare X-linked genetic disorder caused by mutations in the gene encoding the transacylase tafazzin and characterized by loss of cardiolipin and severe cardiomyopathy. Mitochondrial oxidants have been implicated in the cardiomyopathy in BTHS. Eleven mitochondrial sites produce superoxide/hydrogen peroxide (H2 O2 ) at significant rates. Which of these sites generate oxidants at excessive rates in BTHS is unknown. Here, we measured the maximum capacity of superoxide/H2 O2 production from each site and the ex vivo rate of superoxide/H2 O2 production in the heart and skeletal muscle mitochondria of the tafazzin knockdown mice (tazkd) from 3 to 12 months of age. Despite reduced oxidative capacity, superoxide/H2 O2 production was indistinguishable between tazkd mice and wild-type littermates. These observations raise questions about the involvement of mitochondrial oxidants in BTHS pathology.
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Affiliation(s)
- Renata L S Goncalves
- Sabri Ülker Center for Metabolic Research and Department of Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Michael Schlame
- Departments of Anesthesiology and Cell Biology, New York University School of Medicine, New York, NY, USA
| | - Alexander Bartelt
- Sabri Ülker Center for Metabolic Research and Department of Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA, USA.,Institute for Cardiovascular Prevention (IPEK), Ludwig-Maximilians-University, Munich, Germany
| | | | - Gökhan S Hotamışlıgil
- Sabri Ülker Center for Metabolic Research and Department of Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA, USA.,Broad Institute of MIT and Harvard, Cambridge, MA, USA
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12
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Jones AE, Sheng L, Acevedo A, Veliova M, Shirihai OS, Stiles L, Divakaruni AS. Forces, fluxes, and fuels: tracking mitochondrial metabolism by integrating measurements of membrane potential, respiration, and metabolites. Am J Physiol Cell Physiol 2020; 320:C80-C91. [PMID: 33147057 DOI: 10.1152/ajpcell.00235.2020] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Assessing mitochondrial function in cell-based systems is a central component of metabolism research. However, the selection of an initial measurement technique may be complicated given the range of parameters that can be studied and the need to define the mitochondrial (dys)function of interest. This methods-focused review compares and contrasts the use of mitochondrial membrane potential measurements, plate-based respirometry, and metabolomics and stable isotope tracing. We demonstrate how measurements of 1) cellular substrate preference, 2) respiratory chain activity, 3) cell activation, and 4) mitochondrial biogenesis are enriched by integrating information from multiple methods. This manuscript is meant to serve as a perspective to help choose which technique might be an appropriate initial method to answer a given question, as well as provide a broad "roadmap" for designing follow-up assays to enrich datasets or resolve ambiguous results.
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Affiliation(s)
- Anthony E Jones
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, California
| | - Li Sheng
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, California
| | - Aracely Acevedo
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, California
| | - Michaela Veliova
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, California.,Department of Medicine, University of California, Los Angeles, California
| | - Orian S Shirihai
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, California.,Department of Medicine, University of California, Los Angeles, California
| | - Linsey Stiles
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, California.,Department of Medicine, University of California, Los Angeles, California
| | - Ajit S Divakaruni
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, California
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13
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Tamanna N, Munro D, Kroeker K, Banh S, Treberg JR. The effect of short-term methionine restriction on hydrogen peroxide metabolism in Fischer-344 rat skeletal muscle mitochondria. Mitochondrion 2020; 55:1-7. [PMID: 32882439 DOI: 10.1016/j.mito.2020.08.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 08/09/2020] [Accepted: 08/24/2020] [Indexed: 12/18/2022]
Abstract
Skeletal muscle, a significant contributor to resting energy expenditure and reactive oxygen species, may play a critical role in body-weight regulation and aging processes. Methionine restriction (MR) is a dietary intervention which extends lifespan, lowers body-weight and enhances energy expenditure in rodents, all of which have been linked to mitochondrial function in various tissues including liver, kidney, heart and brown adipose tissue; however, mitochondrial responses to MR in skeletal muscle is largely unknown. Given the importance of skeletal muscle on energy metabolism and aging-related processes, we investigated if there are changes in skeletal muscle mitochondrial energetics in response to MR. Although MR lowers body-weight in rats, neither respiration, proton leak nor hydrogen peroxide metabolism were altered in isolated skeletal muscle mitochondria. This suggests that mitochondrial function in skeletal muscle remains conserved while MR alters metabolism in other tissues.
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Affiliation(s)
- Nahid Tamanna
- Department of Biological Sciences, University of Manitoba, Canada.
| | - Daniel Munro
- Department of Biological Sciences, University of Manitoba, Canada.
| | - Kathryn Kroeker
- Department of Biological Sciences, University of Manitoba, Canada.
| | - Sheena Banh
- Department of Biological Sciences, University of Manitoba, Canada.
| | - Jason R Treberg
- Department of Biological Sciences, University of Manitoba, Canada; Centre on Aging, University of Manitoba, Canada.
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14
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Yurre ARDE, Martins EGL, Lopez-Alarcon M, Cabral B, Vera N, Lopes JA, Galina A, Takiya CM, Lindoso RS, Vieyra A, SÁenz OC, Medei E. Type 2 diabetes mellitus alters cardiac mitochondrial content and function in a non-obese mice model. AN ACAD BRAS CIENC 2020; 92:e20191340. [PMID: 32813865 DOI: 10.1590/0001-3765202020191340] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 03/06/2020] [Indexed: 11/21/2022] Open
Abstract
Type 2 diabetes mellitus (T2DM) is associated with an increase of premature appearance of several disorders such as cardiac complications. Thus, we test the hypothesis that a combination of a high fat diet (HFD) and low doses of streptozotocin (STZ) recapitulate a suitable mice model of T2DM to study the cardiac mitochondrial disturbances induced by this disease. Animals were divided in 2 groups: the T2DM group was given a HFD and injected with 2 low doses of STZ, while the CNTRL group was given a standard chow and a buffer solution. The combination of HFD and STZ recapitulate the T2DM metabolic profile showing higher blood glucose levels in T2DM mice when compared to CNTRL, and also, insulin resistance. The kidney structure/function was preserved. Regarding cardiac mitochondrial function, in all phosphorylative states, the cardiac mitochondria from T2DM mice presented reduced oxygen fluxes when compared to CNTRL mice. Also, mitochondria from T2DM mice showed decreased citrate synthase activity and lower protein content of mitochondrial complexes. Our results show that in this non-obese T2DM model, which recapitulates the classical metabolic alterations, mitochondrial function is impaired and provides a useful model to deepen study the mechanisms underlying these alterations.
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Affiliation(s)
- Ainhoa R DE Yurre
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Eduarda G L Martins
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Micaela Lopez-Alarcon
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Bruno Cabral
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Narendra Vera
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Jarlene A Lopes
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Antonio Galina
- Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Christina M Takiya
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Rafael S Lindoso
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Adalberto Vieyra
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Oscar C SÁenz
- Faculdade de Farmacia, Universidade do País Vasco (UPV-EHU), Vitoria-Gasteiz, Spain
| | - Emiliano Medei
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
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15
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Yurre ARD, Silva JDFD, Torres MKDS, Martins EL, Ramos IP, Silva WSFLD, Sarpa JDS, Guedes CCDS, Napoleão TH, Coelho LCBB, Paiva PMG, Medei E. Evaluation of the Cardiac Effects of a Water-Soluble Lectin (Wsmol) from Moringa Oleifera Seeds. Arq Bras Cardiol 2020; 114:1029-1037. [PMID: 32187285 PMCID: PMC8416120 DOI: 10.36660/abc.20190071] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Accepted: 06/23/2019] [Indexed: 12/26/2022] Open
Abstract
Fundsamento As sementes de Moringa oleifera , que são utilizadas para clarificação de água, contêm uma lectina chamada WSMoL que tem mostrado atividade antibacteriana e imunomoduladora in vitro . Devido ao seu valor nutritivo e potencial terapêutico, as folhas e as sementes dessa árvore são consumidas em algumas comunidades. Algumas lectinas de plantas não são tóxicas para mamíferos, mas tem sido relatado que outras são prejudiciais quando ingeridas ou administradas por outros meios. Objetivo Como um dos passos necessários para determinar a segurança de WSMoL, nós avaliamos os possíveis efeitos cardiotóxicos desta proteína purificada. Métodos Durante 21 dias consecutivos, a WSMoL foi administrada a camundongos por gavagem. Foram investigadas as funções eletrofisiológicas, mecânicas e metabólicas in vivo e ex vivo por meio de registros eletrocardiográficos, ressonância magnética nuclear e respirometria de alta resolução. Resultados O tratamento com WSMoL não induziu alterações nos níveis de glicose no sangue ou peso corporal em comparação com o grupo controle. Adicionalmente, as relações peso cardíaco/peso corporal e peso cardíaco/comprimento tibial estavam semelhantes em ambos os grupos. A ingestão de lectina também não modificou a tolerância à glicose ou resistência à insulina. Não foram observadas alterações nos parâmetros eletrocardiográficos ou na duração do potencial de ação cardíaco. Os corações dos camundongos dos grupos controle e WSMoL mostraram função ventricular esquerda preservada. Além disso, a WSMoL não induziu alterações na função mitocondrial (em todos os casos, p > 0,05). Conclusões A administração de WSMoL demonstrou ter um perfil de segurança cardíaca. Estes resultados contribuem à avaliação de segurança do uso de sementes de M. oleifera para tratar água, visto que essa lectina está presente na preparação empregada por algumas populações com esse fim. (Arq Bras Cardiol. 2020; [online].ahead print, PP.0-0)
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | - Emiliano Medei
- Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brasil
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16
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Dawson NJ, Millet C, Selman C, Metcalfe NB. Measurement of mitochondrial respiration in permeabilized fish gills. J Exp Biol 2020; 223:jeb216762. [PMID: 31974221 PMCID: PMC7044462 DOI: 10.1242/jeb.216762] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2019] [Accepted: 01/16/2020] [Indexed: 12/26/2022]
Abstract
Physiological investigations of fish gills have traditionally centred on the two principal functions of the gills: gas exchange and ion regulation. Mitochondrion-rich cells (MRCs) are primarily found within the gill filaments of fish, and are thought to proliferate in order to increase the ionoregulatory capacity of the gill in response to environmentally induced osmotic challenges. However, surprisingly little attention has been paid to the metabolic function of mitochondria within fish gills. Here, we describe and validate a simple protocol for the permeabilization of fish gills and subsequent measurement of mitochondrial respiration rates in vitro Our protocol requires only small tissue samples (8 mg), exploits the natural structure of fish gills, does not require mechanical separation of the gill tissue (so is relatively quick to perform), and yields accurate and highly reproducible measurements of respiration rates. It offers great potential for the study of mitochondrial function in gills over a wide range of fish sizes and species.
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Affiliation(s)
- Neal J Dawson
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow G12 8QQ, UK
| | - Caroline Millet
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow G12 8QQ, UK
| | - Colin Selman
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow G12 8QQ, UK
| | - Neil B Metcalfe
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow G12 8QQ, UK
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17
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Fisher-Wellman KH, Davidson MT, Narowski TM, Lin CT, Koves TR, Muoio DM. Mitochondrial Diagnostics: A Multiplexed Assay Platform for Comprehensive Assessment of Mitochondrial Energy Fluxes. Cell Rep 2019; 24:3593-3606.e10. [PMID: 30257218 DOI: 10.1016/j.celrep.2018.08.091] [Citation(s) in RCA: 84] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Revised: 06/23/2018] [Accepted: 08/29/2018] [Indexed: 12/17/2022] Open
Abstract
Chronic metabolic diseases have been linked to molecular signatures of mitochondrial dysfunction. Nonetheless, molecular remodeling of the transcriptome, proteome, and/or metabolome does not necessarily translate to functional consequences that confer physiologic phenotypes. The work here aims to bridge the gap between molecular and functional phenomics by developing and validating a multiplexed assay platform for comprehensive assessment of mitochondrial energy transduction. The diagnostic power of the platform stems from a modified version of the creatine kinase energetic clamp technique, performed in parallel with multiplexed analyses of dehydrogenase activities and ATP synthesis rates. Together, these assays provide diagnostic coverage of the mitochondrial network at a level approaching that gained by molecular "-omics" technologies. Application of the platform to a comparison of skeletal muscle versus heart mitochondria reveals mechanistic insights into tissue-specific distinctions in energy transfer efficiency. This platform opens exciting opportunities to unravel the connection between mitochondrial bioenergetics and human disease.
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Affiliation(s)
- Kelsey H Fisher-Wellman
- Departments of Medicine and Pharmacology and Cancer Biology, Sarah W. Stedman Nutrition and Metabolism Center and Duke Molecular Physiology Institute, Duke University, Durham, NC 27701, USA; East Carolina Diabetes and Obesity Institute, Brody School of Medicine, East Carolina University, Greenville, NC 27834, USA.
| | - Michael T Davidson
- Departments of Medicine and Pharmacology and Cancer Biology, Sarah W. Stedman Nutrition and Metabolism Center and Duke Molecular Physiology Institute, Duke University, Durham, NC 27701, USA
| | - Tara M Narowski
- Departments of Medicine and Pharmacology and Cancer Biology, Sarah W. Stedman Nutrition and Metabolism Center and Duke Molecular Physiology Institute, Duke University, Durham, NC 27701, USA
| | - Chien-Te Lin
- East Carolina Diabetes and Obesity Institute, Brody School of Medicine, East Carolina University, Greenville, NC 27834, USA
| | - Timothy R Koves
- Departments of Medicine and Pharmacology and Cancer Biology, Sarah W. Stedman Nutrition and Metabolism Center and Duke Molecular Physiology Institute, Duke University, Durham, NC 27701, USA
| | - Deborah M Muoio
- Departments of Medicine and Pharmacology and Cancer Biology, Sarah W. Stedman Nutrition and Metabolism Center and Duke Molecular Physiology Institute, Duke University, Durham, NC 27701, USA.
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18
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Gaudry MJ, Keuper M, Jastroch M. Molecular evolution of thermogenic uncoupling protein 1 and implications for medical intervention of human disease. Mol Aspects Med 2019; 68:6-17. [DOI: 10.1016/j.mam.2019.06.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Revised: 06/20/2019] [Accepted: 06/21/2019] [Indexed: 12/12/2022]
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19
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Munro D, Baldy C, Pamenter ME, Treberg JR. The exceptional longevity of the naked mole-rat may be explained by mitochondrial antioxidant defenses. Aging Cell 2019; 18:e12916. [PMID: 30768748 PMCID: PMC6516170 DOI: 10.1111/acel.12916] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Revised: 10/31/2018] [Accepted: 12/30/2018] [Indexed: 12/21/2022] Open
Abstract
Naked mole-rats (NMRs) are mouse-sized mammals that exhibit an exceptionally long lifespan (>30 vs. <4 years for mice), and resist aging-related pathologies such as cardiovascular and pulmonary diseases, cancer, and neurodegeneration. However, the mechanisms underlying this exceptional longevity and disease resistance remain poorly understood. The oxidative stress theory of aging posits that (a) senescence results from the accumulation of oxidative damage inflicted by reactive oxygen species (ROS) of mitochondrial origin, and (b) mitochondria of long-lived species produce less ROS than do mitochondria of short-lived species. However, comparative studies over the past 28 years have produced equivocal results supporting this latter prediction. We hypothesized that, rather than differences in ROS generation, the capacity of mitochondria to consume ROS might distinguish long-lived species from short-lived species. To test this hypothesis, we compared mitochondrial production and consumption of hydrogen peroxide (H2 O2 ; as a proxy of overall ROS metabolism) between NMR and mouse skeletal muscle and heart. We found that the two species had comparable rates of mitochondrial H2 O2 generation in both tissues; however, the capacity of mitochondria to consume ROS was markedly greater in NMRs. Specifically, maximal observed consumption rates were approximately two and fivefold greater in NMRs than in mice, for skeletal muscle and heart, respectively. Our results indicate that differences in matrix ROS detoxification capacity between species may contribute to their divergence in lifespan.
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Affiliation(s)
- Daniel Munro
- Department of Biological SciencesUniversity of ManitobaWinnipegManitobaCanada
- Department of BiologyUniversity of OttawaOttawaOntarioCanada
- Centre on AgingUniversity of ManitobaWinnipegManitobaCanada
| | - Cécile Baldy
- Department of BiologyUniversity of OttawaOttawaOntarioCanada
| | - Matthew E. Pamenter
- Department of BiologyUniversity of OttawaOttawaOntarioCanada
- University of Ottawa Brain and Mind Research InstituteOttawaOntarioCanada
| | - Jason R. Treberg
- Department of Biological SciencesUniversity of ManitobaWinnipegManitobaCanada
- Centre on AgingUniversity of ManitobaWinnipegManitobaCanada
- Department of food and Human Nutritional SciencesUniversity of ManitobaWinnipegManitobaCanada
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20
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Arhire LI, Mihalache L, Covasa M. Irisin: A Hope in Understanding and Managing Obesity and Metabolic Syndrome. Front Endocrinol (Lausanne) 2019; 10:524. [PMID: 31428053 PMCID: PMC6687775 DOI: 10.3389/fendo.2019.00524] [Citation(s) in RCA: 153] [Impact Index Per Article: 30.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Accepted: 07/16/2019] [Indexed: 12/26/2022] Open
Abstract
White adipose tissue (WAT) is an endocrine organ highly integrated in homeostasis and capable of establishing ways of communicating and influencing multiple metabolic processes. Brown adipose tissue promotes energy expenditure by incorporating the uncoupling protein 1 (UCP1), also known as thermogenin, which decouples cellular respiration and heat production, in the mitochondrial membranes. Recent data suggest the presence of a thermogenic cell formation from white adipocytes (beige or brite cells) with a potential role in preventing obesity and metabolic syndrome. The formation of these cells is influenced by physical exertion that induces expression of PPARγ coactivator-1 (PGC1) and downstream membrane protein, fibronectin type III domain-containing protein 5 (FNDC5) in skeletal muscle. Irisin, a thermogenic adipomyokine produced by FNDC5 cleavage is involved in the browning of adipose tissue. While animal studies are congruent with regard to the relationship between physical exertion and irisin release, the results from human studies are less than clear. Therefore, this review focuses on recent advances in our understanding of muscle and adipose tissue thermogenesis. Further, it describes the molecular mechanisms by which irisin impacts exercise, glucose homeostasis and obesity. Finally, the review discusses current gaps and controversies related to irisin release, its mode of action and its future potential as a therapeutic tool in managing obesity and metabolic syndrome.
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Affiliation(s)
- Lidia I. Arhire
- Department of Internal Medicine, “Grigore T. Popa” University of Medicine and Pharmacy, Iaşi, Romania
- Clinical Hospital “Sf. Spiridon”, Iaşi, Romania
| | - Laura Mihalache
- Department of Internal Medicine, “Grigore T. Popa” University of Medicine and Pharmacy, Iaşi, Romania
- Clinical Hospital “Sf. Spiridon”, Iaşi, Romania
| | - Mihai Covasa
- Department of Basic Medical Sciences, College of Osteopathic Medicine, Western University of Health Sciences, Pomona, CA, United States
- Department of Health and Human Development, University of Suceava, Suceava, Romania
- *Correspondence: Mihai Covasa
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21
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Treberg JR, Braun K, Selseleh P. Mitochondria can act as energy-sensing regulators of hydrogen peroxide availability. Redox Biol 2018; 20:483-488. [PMID: 30466061 PMCID: PMC6249968 DOI: 10.1016/j.redox.2018.11.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Revised: 10/26/2018] [Accepted: 11/06/2018] [Indexed: 01/04/2023] Open
Abstract
Mitochondria are widely recognized as sources of reactive oxygen species in animal cells, with H2O2 being of particular note because it can act not only in oxidative stress but also is important to several signalling pathways. Lesser recognized is that mitochondria can have far greater capacity to consume H2O2 than to produce it; however, the consumption of H2O2 may be kinetically constrained by H2O2 availability especially at the low nanomolar (or lower) concentrations that occur in vivo. The production of H2O2 is a function of many factors, not the least of which are respiratory substrate availability and the protonmotive force (Δp). The Δp, which is predominantly membrane potential (ΔΨ), can be a strong indicator of mitochondrial energy status, particularly if respiratory substrate supply is either not meeting or exceeding demand. The notion that mitochondria may functionally act in regulating H2O2 concentrations may be somewhat implicit but little evidence demonstrating this is available. Here we demonstrate key assumptions that are required for mitochondria to act as regulators of H2O2 by an integrated system of production and concomitant consumption. In particular we show the steady-state level of H2O2 mitochondria approach is a function of both mitochondrial H2O2 consumption and production capacity, the latter of which is strongly influenced by ΔΨ. Our results are consistent with mitochondria being able to manipulate extramitochondrial H2O2 as a means of signalling mitochondrial energetic status, in particular the Δp or ΔΨ. Such a redox-based signal could operate with some independence from other energy sensing mechanisms such as those that transmit information using the cytosolic adenylate pool.
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Affiliation(s)
- Jason R Treberg
- Department of Biological Sciences, University of Manitoba, Winnipeg, MB, Canada; Department of Food and Human Nutritional Sciences, University of Manitoba, Winnipeg, MB, Canada; Centre on Aging, University of Manitoba, Winnipeg, MB, Canada.
| | - Kristen Braun
- Department of Biological Sciences, University of Manitoba, Winnipeg, MB, Canada
| | - Parisa Selseleh
- Department of Biological Sciences, University of Manitoba, Winnipeg, MB, Canada
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22
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Treberg JR, Munro D, Jastroch M, Quijada-Rodriguez AR, Kutschke M, Wiens L. Comparing Electron Leak in Vertebrate Muscle Mitochondria. Integr Comp Biol 2018; 58:495-505. [DOI: 10.1093/icb/icy095] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Affiliation(s)
- Jason R Treberg
- Department of Biological Sciences, University of Manitoba, 50 Sifton Road, Winnipeg, Manitoba, Canada R3T2N2
- Department of Food and Human Nutritional Sciences, University of Manitoba, 50 Sifton Road, Winnipeg, Manitoba, Canada R3T2N2
- Centre on Aging, University of Manitoba, 50 Sifton Road, Winnipeg, Manitoba, Canada R3T2N2
| | - Daniel Munro
- Department of Biological Sciences, University of Manitoba, 50 Sifton Road, Winnipeg, Manitoba, Canada R3T2N2
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada K1N 6N5
| | - Martin Jastroch
- Department of Molecular Biosciences, The Wenner-Gren Institute, The Arrhenius Laboratories F3, Stockholm University, Stockholm SE-106 91, Sweden
| | - Alex R Quijada-Rodriguez
- Department of Biological Sciences, University of Manitoba, 50 Sifton Road, Winnipeg, Manitoba, Canada R3T2N2
| | - Maria Kutschke
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center at Helmholtz Zentrum München, Neuherberg D-85764, Germany
| | - Lilian Wiens
- Department of Biological Sciences, University of Manitoba, 50 Sifton Road, Winnipeg, Manitoba, Canada R3T2N2
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23
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Timurkaan S, Gür FM, Gençer Tarakçı B, Yalçın MH, Girgin M. Identification of irisin immunoreactivity in porcupine (Hystrix cristata) adrenal glands and kidneys. Anat Histol Embryol 2018; 47:405-409. [PMID: 29862553 DOI: 10.1111/ahe.12371] [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: 03/05/2018] [Accepted: 05/13/2018] [Indexed: 11/30/2022]
Abstract
Irisin, a novel peptide, was initially been shown to be expressed explicitly in the muscle tissues. We studied the presence of irisin immunoreactivity in porcupine adrenal glands and kidneys. Immunocytochemistry showed that irisin was localised both in the adrenal cortex and adrenal medulla. In organs, irisin immunoreactivity was found in the tubular and collecting system of the nephron. The functional role of irisin in the adrenal gland and kidney has not been precisely yet. However, irisin might have a paracrine and autocrine function as do other locally produced peptides.
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Affiliation(s)
- Sema Timurkaan
- Department of Histology and Embriyology, Faculty of Veterinary Medicine, Firat University, Elazıg, Turkey
| | - Fatih M Gür
- Department of Histology and Embryology, School of Medicine, Nigde Ömer Halisdemir University, Nigde, Turkey
| | - Berrin Gençer Tarakçı
- Department of Histology and Embriyology, Faculty of Veterinary Medicine, Firat University, Elazıg, Turkey
| | - Mehmet H Yalçın
- Department of Histology and Embriyology, Faculty of Veterinary Medicine, Firat University, Elazıg, Turkey
| | - Mustafa Girgin
- Department of Surgery, School of Medicine, Fırat University, Elazıg, Turkey
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24
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Drevytska T, Gonchar E, Okhai I, Lynnyk O, Mankovska I, Klionsky D, Dosenko V. The protective effect of Hif3a RNA interference and HIF-prolyl hydroxylase inhibition on cardiomyocytes under anoxia-reoxygenation. Life Sci 2018; 202:131-139. [PMID: 29660430 DOI: 10.1016/j.lfs.2018.04.021] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Revised: 03/27/2018] [Accepted: 04/12/2018] [Indexed: 12/29/2022]
Abstract
The aim of this study was to investigate the molecular mechanisms underlying the protective effects of hypoxia-inducible factor (HIF) signaling pathway activation in cardiomyocytes under anoxia-reoxygenation (A/R) injury. In this study, rat neonatal cardiomyocytes were pretreated with anti-Hif3A/Hif-3α siRNA or HIF-prolyl hydroxylase inhibitor prior to A/R injury. Our results showed that both HIF3A silencing and HIF-prolyl hydroxylase inhibition effectively increased the cell viability during A/R, led to changes in mRNA expression of HIF1-target genes, and reduced the loss of mitochondrial membrane potential (Δψm). Furthermore, application of anti-Hif3a siRNA led to an increase in mRNA expression of Epo, Igf1, Slc2a1/Glut-1, and Slc2a4/Glut-4. Similar results were observed with HIF-prolyl hydroxylase inhibition, which additionally upregulated the mRNA expression of Epor, Tert, and Pdk1. Hif3a RNA-interference and application of HIF-prolyl hydroxylase inhibitor during A/R modelling led to an increase of Δψm on 11.5 and 11.9 mV respectively, compared to the control groups. Thus, Hif3a RNA interference and HIF-prolyl hydroxylase inhibition protect cardiomyocytes against A/R injury via the HIF signaling pathway.
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Affiliation(s)
- T Drevytska
- Bogomoletz Institute of Physiology, National Academy of Science, Bogomoletz Street, 4, Kyiv 01024, Ukraine.
| | - E Gonchar
- Bogomoletz Institute of Physiology, National Academy of Science, Bogomoletz Street, 4, Kyiv 01024, Ukraine
| | - I Okhai
- Bogomoletz Institute of Physiology, National Academy of Science, Bogomoletz Street, 4, Kyiv 01024, Ukraine
| | - O Lynnyk
- Bogomoletz Institute of Physiology, National Academy of Science, Bogomoletz Street, 4, Kyiv 01024, Ukraine
| | - I Mankovska
- Bogomoletz Institute of Physiology, National Academy of Science, Bogomoletz Street, 4, Kyiv 01024, Ukraine
| | - D Klionsky
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
| | - V Dosenko
- Bogomoletz Institute of Physiology, National Academy of Science, Bogomoletz Street, 4, Kyiv 01024, Ukraine
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25
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Gür FM, Timurkaan S, Gençer Tarakçi B, Yalçin MH, Özkan ZE, Baygeldi SB, Yilmaz S, Eröksüz H. Identification of immunohistochemical localization of irisin in the dwarf hamster (Phodopus roborovskii
) tissues. Anat Histol Embryol 2018. [DOI: 10.1111/ahe.12345] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
- F. M. Gür
- Department of Histology-Embryology; Faculty of Medicine; Ömer Halisdemir University; Niğde Turkey
| | - S. Timurkaan
- Department of Histology-Embryology; Faculty of Veterinary Medicine; Fırat University; Elazığ Turkey
| | - B. Gençer Tarakçi
- Department of Histology-Embryology; Faculty of Veterinary Medicine; Fırat University; Elazığ Turkey
| | - M. H. Yalçin
- Department of Histology-Embryology; Faculty of Veterinary Medicine; Fırat University; Elazığ Turkey
| | - Z. E. Özkan
- Department of Anatomy; Faculty of Veterinary Medicine; Fırat University; Elazığ Turkey
| | - S. B. Baygeldi
- Department of Anatomy; Faculty of Veterinary Medicine; Fırat University; Elazığ Turkey
| | - S. Yilmaz
- Department of Anatomy; Faculty of Veterinary Medicine; Fırat University; Elazığ Turkey
| | - H. Eröksüz
- Department of Pathology; Faculty of Veterinary Medicine; Fırat University; Elazığ Turkey
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26
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Jastroch M, Oelkrug R, Keipert S. Insights into brown adipose tissue evolution and function from non-model organisms. ACTA ACUST UNITED AC 2018. [PMID: 29514888 DOI: 10.1242/jeb.169425] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Brown adipose tissue (BAT) enables adaptive thermoregulation through heat production that is catalyzed by mitochondrial uncoupling protein 1 (UCP1). BAT is frequently studied in rodent model organisms, and recently in adult humans to treat metabolic diseases. However, complementary studies of many non-model species, which have diversified to many more ecological niches, may significantly broaden our understanding of BAT regulation and its physiological roles. This Review highlights the research on non-model organisms, which was instrumental to the discovery of BAT function, and the unique evolutionary history of BAT/UCP1 in mammalian thermogenesis. The comparative biology of BAT provides a powerful integrative approach that could identify conserved and specialized functional changes in BAT and UCP1 by considering species diversity, ecology and evolution, and by fusing multiple scientific disciplines such as physiology and biochemistry. Thus, resolving the complete picture of BAT biology may fail if comparative studies of non-model organisms are neglected.
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Affiliation(s)
- Martin Jastroch
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center at Helmholtz Zentrum München, D-85764 Neuherberg, Germany .,German Center for Diabetes Research (DZD), D-85764 Neuherberg, Germany.,Department of Animal Physiology, Faculty of Biology, Philipps University of Marburg, D-35032 Marburg, Germany
| | - Rebecca Oelkrug
- Department of Molecular Endocrinology, Center of Brain, Behavior and Metabolism (CBBM), University of Lübeck, D-23562 Lübeck, Germany
| | - Susanne Keipert
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center at Helmholtz Zentrum München, D-85764 Neuherberg, Germany.,German Center for Diabetes Research (DZD), D-85764 Neuherberg, Germany
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27
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Wiens L, Banh S, Sotiri E, Jastroch M, Block BA, Brand MD, Treberg JR. Comparison of Mitochondrial Reactive Oxygen Species Production of Ectothermic and Endothermic Fish Muscle. Front Physiol 2017; 8:704. [PMID: 28966595 PMCID: PMC5605635 DOI: 10.3389/fphys.2017.00704] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 08/31/2017] [Indexed: 01/01/2023] Open
Abstract
Recently we demonstrated that the capacity of isolated muscle mitochondria to produce reactive oxygen species, measured as H2O2 efflux, is temperature-sensitive in isolated muscle mitochondria of ectothermic fish and the rat, a representative endothermic mammal. However, at physiological temperatures (15° and 37°C for the fish and rat, respectively), the fraction of total mitochondrial electron flux that generated H2O2, the fractional electron leak (FEL), was far lower in the rat than in fish. Those results suggested that the elevated body temperatures associated with endothermy may lead to a compensatory decrease in mitochondrial ROS production relative to respiratory capacity. To test this hypothesis we compare slow twitch (red) muscle mitochondria from the endothermic Pacific bluefin tuna (Thunnus orientalis) with mitochondria from three ectothermic fishes [rainbow trout (Oncorhynchus mykiss), common carp (Cyprinus carpio), and the lake sturgeon (Acipenser fulvescens)] and the rat. At a common assay temperature (25°C) rates of mitochondrial respiration and H2O2 efflux were similar in tuna and the other fishes. The thermal sensitivity of fish mitochondria was similar irrespective of ectothermy or endothermy. Comparing tuna to the rat at a common temperature, respiration rates were similar, or lower depending on mitochondrial substrates. FEL was not different across fish species at a common assay temperature (25°C) but was markedly higher in fishes than in rat. Overall, endothermy and warming of Pacific Bluefin tuna red muscle may increase the potential for ROS production by muscle mitochondria but the evolution of endothermy in this species is not necessarily associated with a compensatory reduction of ROS production relative to the respiratory capacity of mitochondria.
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Affiliation(s)
- Lilian Wiens
- Department of Biological Sciences, University of ManitobaWinnipeg, MB, Canada
| | - Sheena Banh
- Department of Biological Sciences, University of ManitobaWinnipeg, MB, Canada
| | - Emianka Sotiri
- Department of Biological Sciences, University of ManitobaWinnipeg, MB, Canada
| | - Martin Jastroch
- Helmholtz Diabetes Center at Helmholtz Zentrum München, Institute for Diabetes and ObesityMunich, Germany
| | - Barbara A Block
- Tuna Research and Conservation Center, Hopkins Marine Station, Stanford UniversityStanford, CA, United States
| | - Martin D Brand
- Buck Institute for Research on AgingNovato, CA, United States
| | - Jason R Treberg
- Department of Biological Sciences, University of ManitobaWinnipeg, MB, Canada.,Department of Human Nutritional Sciences, University of ManitobaWinnipeg, MB, Canada
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28
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Ates I, Arikan MF, Erdogan K, Kaplan M, Yuksel M, Topcuoglu C, Yilmaz N, Guler S. Factors associated with increased irisin levels in the type 1 diabetes mellitus. Endocr Regul 2017; 51:1-7. [PMID: 28222023 DOI: 10.1515/enr-2017-0001] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
OBJECTIVE The aim of the present study was to determine the irisin levels in patients with the type 1 diabetes mellitus (T1DM) and to examine the relation of irisin levels with the inflammation and autoimmunity. METHODS This study included 35 cases diagnosed with T1DM and 36 healthy volunteers. Antiglutamic acid decarboxylase (anti-GAD), islet cell antibody (ICA), and insulin autoantibody levels were measured in patients at the time when they were included into the study and recorded from the patient files. Serum irisin levels were measured by ELISA kit. RESULTS The median irisin levels were determined higher in T1DM group compared to the control one (6.8 ng/ml vs. 4.8 ng/ml, p=0.022; respectively). Median irisin levels were higher in anti-GAD (p=0.022) and ICA (p=0.044) positive groups compared to negative groups. In T1DM group, irisin levels displayed positive correlation with glycosylated hemoglobin (HbA1c) (r=0.377, p<0.001) and anti-GAD (r=0.392, p=0.020) and negative correlation with creatinine (r=-0390, p=0.021). In multivariate regression model, HbA1c (B±SE: 2.76±17683, p<0.001), and anti-GAD (B±SE: 2.311±0.610, p=0.001) were determined as independent predictors for predicting the irisin levels. CONCLUSION In patients with T1DM, which chronic inflammation and autoimmunity take part in their etiopathogenesis, anti-GAD levels were an independent risk factor for the irisin. Th is may suggest that factors such as inflammation and autoimmunity can be effective in the synthesis of irisin.
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29
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Uncoupling protein 1 controls reactive oxygen species in brown adipose tissue. Proc Natl Acad Sci U S A 2017; 114:7744-7746. [PMID: 28710335 DOI: 10.1073/pnas.1709064114] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
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30
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Moon Y, Balke JE, Madorma D, Siegel MP, Knowels G, Brouckaert P, Buys ES, Marcinek DJ, Percival JM. Nitric Oxide Regulates Skeletal Muscle Fatigue, Fiber Type, Microtubule Organization, and Mitochondrial ATP Synthesis Efficiency Through cGMP-Dependent Mechanisms. Antioxid Redox Signal 2017; 26:966-985. [PMID: 27393340 PMCID: PMC5467110 DOI: 10.1089/ars.2016.6630] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
AIM Skeletal muscle nitric oxide-cyclic guanosine monophosphate (NO-cGMP) pathways are impaired in Duchenne and Becker muscular dystrophy partly because of reduced nNOSμ and soluble guanylate cyclase (GC) activity. However, GC function and the consequences of reduced GC activity in skeletal muscle are unknown. In this study, we explore the functions of GC and NO-cGMP signaling in skeletal muscle. RESULTS GC1, but not GC2, expression was higher in oxidative than glycolytic muscles. GC1 was found in a complex with nNOSμ and targeted to nNOS compartments at the Golgi complex and neuromuscular junction. Baseline GC activity and GC agonist responsiveness was reduced in the absence of nNOS. Structural analyses revealed aberrant microtubule directionality in GC1-/- muscle. Functional analyses of GC1-/- muscles revealed reduced fatigue resistance and postexercise force recovery that were not due to shifts in type IIA-IIX fiber balance. Force deficits in GC1-/- muscles were also not driven by defects in resting mitochondrial adenosine triphosphate (ATP) synthesis. However, increasing muscle cGMP with sildenafil decreased ATP synthesis efficiency and capacity, without impacting mitochondrial content or ultrastructure. INNOVATION GC may represent a new target for alleviating muscle fatigue and that NO-cGMP signaling may play important roles in muscle structure, contractility, and bioenergetics. CONCLUSIONS These findings suggest that GC activity is nNOS dependent and that muscle-specific control of GC expression and differential GC targeting may facilitate NO-cGMP signaling diversity. They suggest that nNOS regulates muscle fiber type, microtubule organization, fatigability, and postexercise force recovery partly through GC1 and suggest that NO-cGMP pathways may modulate mitochondrial ATP synthesis efficiency. Antioxid. Redox Signal. 26, 966-985.
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Affiliation(s)
- Younghye Moon
- 1 Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine , Miami, Florida
| | - Jordan E Balke
- 1 Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine , Miami, Florida
| | - Derik Madorma
- 1 Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine , Miami, Florida
| | - Michael P Siegel
- 2 Department of Bioengineering, University of Washington , Seattle, Washington
| | - Gary Knowels
- 2 Department of Bioengineering, University of Washington , Seattle, Washington
| | - Peter Brouckaert
- 3 Department for Molecular Biomedical Research and Biomedical Molecular Biology, Ghent University , Ghent, Belgium
| | - Emmanuel S Buys
- 4 Department of Anesthesia, Critical Care and Pain Medicine, Anesthesia Center for Critical Care Research , Massachusetts General Hospital, Boston, Massachusetts
| | - David J Marcinek
- 2 Department of Bioengineering, University of Washington , Seattle, Washington.,5 Department of Radiology, University of Washington , Seattle, Washington
| | - Justin M Percival
- 1 Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine , Miami, Florida
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31
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Abstract
The pancreatic β-cell secretes insulin in response to elevated plasma glucose. This review applies an external bioenergetic critique to the central processes of glucose-stimulated insulin secretion, including glycolytic and mitochondrial metabolism, the cytosolic adenine nucleotide pool, and its interaction with plasma membrane ion channels. The control mechanisms responsible for the unique responsiveness of the cell to glucose availability are discussed from bioenergetic and metabolic control standpoints. The concept of coupling factor facilitation of secretion is critiqued, and an attempt is made to unravel the bioenergetic basis of the oscillatory mechanisms controlling secretion. The need to consider the physiological constraints operating in the intact cell is emphasized throughout. The aim is to provide a coherent pathway through an extensive, complex, and sometimes bewildering literature, particularly for those unfamiliar with the field.
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Affiliation(s)
- David G Nicholls
- Buck Institute for Research on Aging, Novato, California; and Department of Clinical Sciences, Unit of Molecular Metabolism, Lund University Diabetes Centre, Malmo, Sweden
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32
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Gür FM, Timurkaan S, Yalcin MH, Girgin A, Gençer Tarakçı B. Immunohistochemical localization of irisin in mole rats(Spalax leucodon). Biotech Histochem 2017; 92:245-251. [DOI: 10.1080/10520295.2017.1303194] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
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33
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Gerencser AA, Mookerjee SA, Jastroch M, Brand MD. Positive Feedback Amplifies the Response of Mitochondrial Membrane Potential to Glucose Concentration in Clonal Pancreatic Beta Cells. Biochim Biophys Acta Mol Basis Dis 2016; 1863:1054-1065. [PMID: 27771512 DOI: 10.1016/j.bbadis.2016.10.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2016] [Revised: 10/16/2016] [Accepted: 10/18/2016] [Indexed: 02/07/2023]
Abstract
Analysis of the cellular mechanisms of metabolic disorders, including type 2 diabetes mellitus, is complicated by the large number of reactions and interactions in metabolic networks. Metabolic control analysis with appropriate modularization is a powerful method for simplifying and analyzing these networks. To analyze control of cellular energy metabolism in adherent cell cultures of the INS-1 832/13 pancreatic β-cell model we adapted our microscopy assay of absolute mitochondrial membrane potential (ΔψM) to a fluorescence microplate reader format, and applied it in conjunction with cell respirometry. In these cells the sensitive response of ΔψM to extracellular glucose concentration drives glucose-stimulated insulin secretion. Using metabolic control analysis we identified the control properties that generate this sensitive response. Force-flux relationships between ΔψM and respiration were used to calculate kinetic responses to ΔψM of processes both upstream (glucose oxidation) and downstream (proton leak and ATP turnover) of ΔψM. The analysis revealed that glucose-evoked ΔψM hyperpolarization is amplified by increased glucose oxidation activity caused by factors downstream of ΔψM. At high glucose, the hyperpolarized ΔψM is stabilized almost completely by the action of glucose oxidation, whereas proton leak also contributes to the homeostatic control of ΔψM at low glucose. These findings suggest a strong positive feedback loop in the regulation of β-cell energetics, and a possible regulatory role of proton leak in the fasting state. Analysis of islet bioenergetics from published cases of type 2 diabetes suggests that disruption of this feedback can explain the damaged bioenergetic response of β-cells to glucose. This article is part of a Special Issue entitled: Oxidative Stress and Mitochondrial Quality in Diabetes/Obesity and Critical Illness Spectrum of Diseases - edited by P. Hemachandra Reddy.
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Affiliation(s)
- Akos A Gerencser
- Buck Institute for Research on Aging, 8001 Redwood Blvd, Novato, CA 94945, United States; Image Analyst Software, 43 Nova Lane, Novato, CA 94945, United States.
| | - Shona A Mookerjee
- Buck Institute for Research on Aging, 8001 Redwood Blvd, Novato, CA 94945, United States; Touro University California College of Pharmacy, 1310 Club Drive, Vallejo, CA 94592, United States
| | - Martin Jastroch
- Buck Institute for Research on Aging, 8001 Redwood Blvd, Novato, CA 94945, United States
| | - Martin D Brand
- Buck Institute for Research on Aging, 8001 Redwood Blvd, Novato, CA 94945, United States
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34
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Brand MD, Goncalves RLS, Orr AL, Vargas L, Gerencser AA, Borch Jensen M, Wang YT, Melov S, Turk CN, Matzen JT, Dardov VJ, Petrassi HM, Meeusen SL, Perevoshchikova IV, Jasper H, Brookes PS, Ainscow EK. Suppressors of Superoxide-H 2O 2 Production at Site I Q of Mitochondrial Complex I Protect against Stem Cell Hyperplasia and Ischemia-Reperfusion Injury. Cell Metab 2016; 24:582-592. [PMID: 27667666 PMCID: PMC5061631 DOI: 10.1016/j.cmet.2016.08.012] [Citation(s) in RCA: 152] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Revised: 07/12/2016] [Accepted: 08/21/2016] [Indexed: 12/11/2022]
Abstract
Using high-throughput screening we identified small molecules that suppress superoxide and/or H2O2 production during reverse electron transport through mitochondrial respiratory complex I (site IQ) without affecting oxidative phosphorylation (suppressors of site IQ electron leak, "S1QELs"). S1QELs diminished endogenous oxidative damage in primary astrocytes cultured at ambient or low oxygen tension, showing that site IQ is a normal contributor to mitochondrial superoxide-H2O2 production in cells. They diminished stem cell hyperplasia in Drosophila intestine in vivo and caspase activation in a cardiomyocyte cell model driven by endoplasmic reticulum stress, showing that superoxide-H2O2 production by site IQ is involved in cellular stress signaling. They protected against ischemia-reperfusion injury in perfused mouse heart, showing directly that superoxide-H2O2 production by site IQ is a major contributor to this pathology. S1QELs are tools for assessing the contribution of site IQ to cell physiology and pathology and have great potential as therapeutic leads.
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Affiliation(s)
- Martin D Brand
- Buck Institute for Research on Aging, Novato, CA 94945, USA.
| | | | - Adam L Orr
- Buck Institute for Research on Aging, Novato, CA 94945, USA
| | - Leonardo Vargas
- Genomics Institute of the Novartis Research Foundation, San Diego, CA 92121, USA
| | | | | | - Yves T Wang
- Department of Anesthesiology, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Simon Melov
- Buck Institute for Research on Aging, Novato, CA 94945, USA
| | - Carolina N Turk
- Genomics Institute of the Novartis Research Foundation, San Diego, CA 92121, USA
| | - Jason T Matzen
- Genomics Institute of the Novartis Research Foundation, San Diego, CA 92121, USA
| | - Victoria J Dardov
- Genomics Institute of the Novartis Research Foundation, San Diego, CA 92121, USA
| | - H Michael Petrassi
- Genomics Institute of the Novartis Research Foundation, San Diego, CA 92121, USA
| | - Shelly L Meeusen
- Genomics Institute of the Novartis Research Foundation, San Diego, CA 92121, USA
| | | | | | - Paul S Brookes
- Department of Anesthesiology, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Edward K Ainscow
- Genomics Institute of the Novartis Research Foundation, San Diego, CA 92121, USA
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35
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Bunik VI, Artiukhov A, Kazantsev A, Goncalves R, Daloso D, Oppermann H, Kulakovskaya E, Lukashev N, Fernie A, Brand M, Gaunitz F. Specific inhibition by synthetic analogs of pyruvate reveals that the pyruvate dehydrogenase reaction is essential for metabolism and viability of glioblastoma cells. Oncotarget 2016; 6:40036-52. [PMID: 26503465 PMCID: PMC4741878 DOI: 10.18632/oncotarget.5486] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Accepted: 10/02/2015] [Indexed: 02/04/2023] Open
Abstract
The pyruvate dehydrogenase complex (PDHC) and its phosphorylation are considered essential for oncotransformation, but it is unclear whether cancer cells require PDHC to be functional or silenced. We used specific inhibition of PDHC by synthetic structural analogs of pyruvate to resolve this question. With isolated and intramitochondrial PDHC, acetyl phosphinate (AcPH, KiAcPH = 0.1 μM) was a much more potent competitive inhibitor than the methyl ester of acetyl phosphonate (AcPMe, KiAcPMe = 40 μM). When preincubated with the complex, AcPH also irreversibly inactivated PDHC. Pyruvate prevented, but did not reverse the inactivation. The pyruvate analogs did not significantly inhibit other 2-oxo acid dehydrogenases. Different cell lines were exposed to the inhibitors and a membrane-permeable precursor of AcPMe, dimethyl acetyl phosphonate, which did not inhibit isolated PDHC. Using an ATP-based assay, dependence of cellular viability on the concentration of the pyruvate analogs was followed. The highest toxicity of the membrane-permeable precursor suggested that the cellular action of charged AcPH and AcPMe requires monocarboxylate transporters. The relevant cell-specific transcripts extracted from Gene Expression Omnibus database indicated that cell lines with higher expression of monocarboxylate transporters and PDHC components were more sensitive to the PDHC inhibitors. Prior to a detectable antiproliferative action, AcPH significantly changed metabolic profiles of the investigated glioblastoma cell lines. We conclude that catalytic transformation of pyruvate by pyruvate dehydrogenase is essential for the metabolism and viability of glioblastoma cell lines, although metabolic heterogeneity causes different cellular sensitivities and/or abilities to cope with PDHC inhibition.
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Affiliation(s)
- Victoria I Bunik
- A.N. Belozersky Institute of Physicochemical Biology, Lomonosov Moscow State University, 119234 Moscow, Russia.,Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, 119234 Moscow, Russia
| | - Artem Artiukhov
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, 119234 Moscow, Russia
| | - Alexey Kazantsev
- Faculty of Chemistry, Lomonosov Moscow State University, 119234 Moscow, Russia
| | | | - Danilo Daloso
- Max-Planck-Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Henry Oppermann
- Department of Neurosurgery, Medical Faculty of the University of Leipzig, 04103 Leipzig, Germany
| | - Elena Kulakovskaya
- Faculty of Biology, Lomonosov Moscow State University, 119234 Moscow, Russia
| | - Nikolay Lukashev
- Faculty of Chemistry, Lomonosov Moscow State University, 119234 Moscow, Russia
| | - Alisdair Fernie
- Max-Planck-Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Martin Brand
- Buck Institute for Research on Aging, Novato, CA 94945, USA
| | - Frank Gaunitz
- Department of Neurosurgery, Medical Faculty of the University of Leipzig, 04103 Leipzig, Germany
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36
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Podrabsky JE, Hand SC. Physiological strategies during animal diapause: lessons from brine shrimp and annual killifish. ACTA ACUST UNITED AC 2016; 218:1897-906. [PMID: 26085666 DOI: 10.1242/jeb.116194] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Diapause is a programmed state of developmental arrest that typically occurs as part of the natural developmental progression of organisms that inhabit seasonal environments. The brine shrimp Artemia franciscana and annual killifish Austrofundulus limnaeus share strikingly similar life histories that include embryonic diapause as a means to synchronize the growth and reproduction phases of their life history to favorable environmental conditions. In both species, respiration rate is severely depressed during diapause and thus alterations in mitochondrial physiology are a key component of the suite of characters associated with cessation of development. Here, we use these two species to illustrate the basic principles of metabolic depression at the physiological and biochemical levels. It is clear that these two species use divergent molecular mechanisms to achieve the same physiological and ecological outcomes. This pattern of convergent physiological strategies supports the importance of biochemical and physiological adaptations to cope with extreme environmental stress and suggests that inferring mechanism from transcriptomics or proteomics or metabolomics alone, without rigorous follow-up at the biochemical and physiological levels, could lead to erroneous conclusions.
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Affiliation(s)
- Jason E Podrabsky
- Department of Biology, Portland State University, P.O. Box 751, Portland, OR 97207-0751, USA
| | - Steven C Hand
- Department of Biological Sciences, Division of Cellular, Integrative and Comparative Biology, Louisiana State University, Baton Rouge, LA 70803, USA
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37
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Shoukry A, Shalaby SM, El-Arabi Bdeer S, Mahmoud AA, Mousa MM, Khalifa A. Circulating serum irisin levels in obesity and type 2 diabetes mellitus. IUBMB Life 2016; 68:544-56. [PMID: 27220658 DOI: 10.1002/iub.1511] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Accepted: 04/25/2016] [Indexed: 01/01/2023]
Abstract
Irisin is an exercise-regulated myokine inducing browning of white adipose tissue and has gained interest as a potential new strategy to combat obesity and its associated disorders, such as type 2 diabetes mellitus (T2DM). The aim of this study is to evaluate the circulating serum irisin levels in obesity and T2DM and also to elucidate possible relationships between serum irisin levels with anthropometric and metabolic parameters of obesity and T2DM. One hundred fifty newly diagnosed T2DM patients as well as 150 nondiabetic control subjects were enrolled in this study. Nondiabetic controls were then stratified according to their body mass index (BMI) into three subgroups; lean, overweight, and obese. Serum irisin levels were evaluated by enzyme-linked immunosorbent assay. Serum irisin levels were significantly decreased in T2DM patients compared with nondiabetic controls. Obese nondiabetic controls had significantly higher serum irisin levels compared with lean nondiabetic controls. In both nondiabetic controls and T2DM patients, serum irisin was significantly positively correlated with BMI (r = 0.985, P < 0.001 and r = 0.218, P = 0.007, respectively), fat mass (r = 0.959, P < 0.001 and r = 0.202, P = 0.013, respectively), fat-free mass (r = 0.606, P < 0.001 and r = 0.194, P = 0.017, respectively), fat-free mass index (r = 0.820, P < 0.001 and r = 0.179, P = 0.028, respectively), waist-to-hip ratio (r = 0.880, P < 0.001 and r = 0.194, P = 0.017, respectively), fasting insulin (r = 0.989, P < 0.001 and r = 0.207, P = 0.011, respectively), and HOMA-IR (r = 0.989, P < 0.001 and r = 0.185, P = 0.023, respectively), whereas; significantly negatively correlated with insulin sensitivity (r = -0.992, P < 0.001 and r = -0.187, P = 0.022, respectively). In this study, we demonstrated that circulating serum irisin levels were increased in obese nondiabetic subjects, while decreased in T2DM patients. Moreover, serum irisin levels were correlated with anthropometric and metabolic markers of obesity and T2DM. © 2016 IUBMB Life, 68(7):544-556, 2016.
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Affiliation(s)
- Amira Shoukry
- Internal Medicine Department, Faculty of Medicine, Zagazig University, Zagazig, Egypt
| | - Sally M Shalaby
- Medical Biochimistry Department, Faculty of Medicine, Zagazig University, Zagazig, Egypt
| | | | - Amira A Mahmoud
- Internal Medicine Department, Faculty of Medicine, Zagazig University, Zagazig, Egypt
| | - Mayada M Mousa
- Internal Medicine Department, Faculty of Medicine, Zagazig University, Zagazig, Egypt
| | - Ashraf Khalifa
- Internal Medicine Department, Faculty of Medicine, Zagazig University, Zagazig, Egypt
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Gençer Tarakçı B, Girgin A, Timurkaan S, Yalçın MH, Gür FM, Karan M. Immunohistochemical localization of irisin in skin, eye, and thyroid and pineal glands of the crested porcupine(Hystrix cristata). Biotech Histochem 2016; 91:423-7. [DOI: 10.1080/10520295.2016.1183820] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
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Abstract
Type two diabetes (T2D) is a challenging metabolic disorder for which a cure has not yet been found. Its etiology is associated with several phenomena, including significant loss of insulin-producing, beta cell (β cell) mass via progressive programmed cell death and disrupted cellular autophagy. In diabetes, the etiology of β cell death and the role of mitochondria are complex and involve several layers of mechanisms. Understanding the dynamics of those mechanisms could permit researchers to develop an intervention for the progressive loss of β cells. Currently, diabetes research has shifted toward rejuvenation and plasticity technology and away from the simplified approach of hormonal compensation. Diabetes research is currently challenged by questions such as how to enhance cell survival, decrease apoptosis and replenish β cell mass in diabetic patients. In this review, we discuss evidence that β cell development and mass formation are guided by specific signaling systems, particularly hormones, transcription factors, and growth factors, all of which could be manipulated to enhance mass growth. There is also strong evidence that β cells are dynamically active cells, which, under specific conditions such as obesity, can increase in size and subsequently increase insulin secretion. In certain cases of aggressive or advanced forms of T2D, β cells become markedly impaired, and the only alternatives for maintaining glucose homeostasis are through partial or complete cell grafting (the Edmonton protocol). In these cases, the harvesting of an enriched population of viable β cells is required for transplantation. This task necessitates a deep understanding of the pharmacological agents that affect β cell survival, mass, and function. The aim of this review is to initiate discussion about the important signals in pancreatic β cell development and mass formation and to highlight the process by which cell death occurs in diabetes. This review also examines the attempts that have been made to recover or increase cell mass in diabetic patients by using various pharmacological agents.
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Affiliation(s)
- Husnia I Marrif
- Department of Pharmacology, Faculty of Medicine, University of Benghazi Benghazi, Libya
| | - Salma I Al-Sunousi
- Department of Histology and Anatomy, Faculty of Medicine, University of Benghazi Benghazi, Libya
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Goncalves RLS, Bunik VI, Brand MD. Production of superoxide/hydrogen peroxide by the mitochondrial 2-oxoadipate dehydrogenase complex. Free Radic Biol Med 2016; 91:247-55. [PMID: 26708453 DOI: 10.1016/j.freeradbiomed.2015.12.020] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2015] [Revised: 10/28/2015] [Accepted: 12/16/2015] [Indexed: 01/12/2023]
Abstract
In humans, mutations in dehydrogenase E1 and transketolase domain containing 1 (DHTKD1) are associated with neurological abnormalities and accumulation of 2-oxoadipate, 2-aminoadipate, and reactive oxygen species. The protein encoded by DHTKD1 has sequence and structural similarities to 2-oxoglutarate dehydrogenase, and the 2-oxoglutarate dehydrogenase complex can produce superoxide/H2O2 at high rates. The DHTKD1 enzyme is hypothesized to catalyze the oxidative decarboxylation of 2-oxoadipate, a shared intermediate of the degradative pathways for tryptophan, lysine and hydroxylysine. Here, we show that rat skeletal muscle mitochondria can produce superoxide/H2O2 at high rates when given 2-oxoadipate. We identify the putative mitochondrial 2-oxoadipate dehydrogenase complex as one of the sources and characterize the conditions that favor its superoxide/H2O2 production. Rates increased at higher NAD(P)H/NAD(P)(+) ratios and were higher at each NAD(P)H/NAD(P)(+) ratio when 2-oxoadipate was present, showing that superoxide/H2O2 was produced during the forward reaction from 2-oxoadipate, but not in the reverse reaction from NADH in the absence of 2-oxoadipate. The maximum capacity of the 2-oxoadipate dehydrogenase complex for production of superoxide/H2O2 is comparable to that of site IF of complex I, and seven, four and almost two-fold lower than the capacities of the 2-oxoglutarate, pyruvate and branched-chain 2-oxoacid dehydrogenase complexes, respectively. Regulation by ADP and ATP of H2O2 production driven by 2-oxoadipate was very different from that driven by 2-oxoglutarate, suggesting that site AF of the 2-oxoadipate dehydrogenase complex is a new source of superoxide/H2O2 associated with the NADH isopotential pool in mitochondria.
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Affiliation(s)
| | - Victoria I Bunik
- A.N. Belozersky Institute of Physico-Chemical Biology and Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow 119991, Russia
| | - Martin D Brand
- The Buck Institute for Research on Aging, Novato, CA 94945, USA
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41
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Hey-Mogensen M, Gram M, Jensen MB, Lund MT, Hansen CN, Scheibye-Knudsen M, Bohr VA, Dela F. A novel method for determining human ex vivo submaximal skeletal muscle mitochondrial function. J Physiol 2015; 593:3991-4010. [PMID: 26096709 DOI: 10.1113/jp270204] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Accepted: 06/04/2015] [Indexed: 12/23/2022] Open
Abstract
The present study utilized a novel method aiming to investigate mitochondrial function in human skeletal muscle at submaximal levels and at a predefined membrane potential. The effect of age and training status was investigated using a cross-sectional design. Ageing was found to be related to decreased leak regardless of training status. Increased training status was associated with increased mitochondrial hydrogen peroxide emission. Despite numerous studies, there is no consensus about whether mitochondrial function is altered with increased age. The novelty of the present study is the determination of mitochondrial function at submaximal activity rates, which is more physiologically relevant than the ex vivo functionality protocols used previously. Muscle biopsies were taken from 64 old or young male subjects (aged 60-70 or 20-30 years). Aged subjects were recruited as trained or untrained. Muscle biopsies were used for the isolation of mitochondria and subsequent measurements of DNA repair, anti-oxidant capacity and mitochondrial protein levels (complexes I-V). Mitochondrial function was determined by simultaneous measurement of oxygen consumption, membrane potential and hydrogen peroxide emission using pyruvate + malate (PM) or succinate + rotenone (SR) as substrates. Proton leak was lower in aged subjects when determined at the same membrane potential and was unaffected by training status. State 3 respiration was lower in aged untrained subjects. This effect, however, was alleviated in aged trained subjects. H2 O2 emission with PM was higher in aged subjects, and was exacerbated by training, although it was not changed when using SR. However, with a higher manganese superoxide dismuthase content, the trained aged subjects may actually have lower or similar mitochondrial superoxide emission compared to the untrained subjects. We conclude that ageing and the physical activity level in aged subjects are both related to changes in the intrinsic functionality of the mitochondrion in skeletal muscle. Both of these changes could be important factors in determining the metabolic health of the aged skeletal muscle cell.
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Affiliation(s)
- Martin Hey-Mogensen
- Xlab, Center for Healthy Aging - Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark.,Present address: Diabetes Research Unit, Novo Nordisk A/S, Novo Nordisk Park, Måløv, Denmark
| | - Martin Gram
- Xlab, Center for Healthy Aging - Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Martin Borch Jensen
- Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark.,Present address: Buck Institute for Research on Aging, 8001 Redwood Blvd, Novato, CA, USA
| | - Michael Taulo Lund
- Xlab, Center for Healthy Aging - Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Christina Neigaard Hansen
- Xlab, Center for Healthy Aging - Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Morten Scheibye-Knudsen
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Vilhelm A Bohr
- Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark.,Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Flemming Dela
- Xlab, Center for Healthy Aging - Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
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Divakaruni AS, Paradyse A, Ferrick DA, Murphy AN, Jastroch M. Analysis and interpretation of microplate-based oxygen consumption and pH data. Methods Enzymol 2015; 547:309-54. [PMID: 25416364 DOI: 10.1016/b978-0-12-801415-8.00016-3] [Citation(s) in RCA: 323] [Impact Index Per Article: 35.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Breakthrough technologies to measure cellular oxygen consumption and proton efflux are reigniting the study of cellular energetics by increasing the scope and pace with which discoveries are made. As we learn the variation in metabolism between cell types is large, it is helpful to continually provide additional perspectives and update our roadmap for data interpretation. In that spirit, this chapter provides the following for those conducting microplate-based oxygen consumption experiments: (i) a description of the standard parameters for measuring respiration in intact cells, (ii) a framework for data analysis and normalization, and (iii) examples of measuring respiration in permeabilized cells to follow up results observed with intact cells. Additionally, rate-based measurements of extracellular pH are increasingly used as a qualitative indicator of glycolytic flux. As a resource to help interpret these measurements, this chapter also provides a detailed accounting of proton production during glucose oxidation in the context of plate-based assays.
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Affiliation(s)
- Ajit S Divakaruni
- Department of Pharmacology, University of California, San Diego, California, USA.
| | - Alexander Paradyse
- Department of Pharmacology, University of California, San Diego, California, USA
| | | | - Anne N Murphy
- Department of Pharmacology, University of California, San Diego, California, USA
| | - Martin Jastroch
- Institute for Diabetes and Obesity, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
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43
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Treberg JR, Munro D, Banh S, Zacharias P, Sotiri E. Differentiating between apparent and actual rates of H2O2 metabolism by isolated rat muscle mitochondria to test a simple model of mitochondria as regulators of H2O2 concentration. Redox Biol 2015; 5:216-224. [PMID: 26001520 PMCID: PMC4442692 DOI: 10.1016/j.redox.2015.05.001] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Revised: 04/29/2015] [Accepted: 05/05/2015] [Indexed: 01/01/2023] Open
Abstract
Mitochondria are often regarded as a major source of reactive oxygen species (ROS) in animal cells, with H2O2 being the predominant ROS released from mitochondria; however, it has been recently demonstrated that energized brain mitochondria may act as stabilizers of H2O2 concentration (Starkov et al. [1]) based on the balance between production and the consumption of H2O2, the later of which is a function of [H2O2] and follows first order kinetics. Here we test the hypothesis that isolated skeletal muscle mitochondria, from the rat, are able to modulate [H2O2] based upon the interaction between the production of ROS, as superoxide/H2O2, and the H2O2 decomposition capacity. The compartmentalization of detection systems for H2O2 and the intramitochondrial metabolism of H2O2 leads to spacial separation between these two components of the assay system. This results in an underestimation of rates when relying solely on extramitochondrial H2O2 detection. We find that differentiating between these apparent rates found when using extramitochondrial H2O2 detection and the actual rates of metabolism is important to determining the rate constant for H2O2 consumption by mitochondria in kinetic experiments. Using the high rate of ROS production by mitochondria respiring on succinate, we demonstrate that net H2O2 metabolism by mitochondria can approach a stable steady-state of extramitochondrial [H2O2]. Importantly, the rate constant determined by extrapolation of kinetic experiments is similar to the rate constant determined as the [H2O2] approaches a steady state.
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Affiliation(s)
- Jason R Treberg
- Department of Biological Sciences, University of Manitoba, 50 Sifton Road, Winnipeg, MB, Canada R3T 2N2; Department of Human Nutritional Sciences, University of Manitoba, Winnipeg, MB, Canada.
| | - Daniel Munro
- Department of Biological Sciences, University of Manitoba, 50 Sifton Road, Winnipeg, MB, Canada R3T 2N2
| | - Sheena Banh
- Department of Biological Sciences, University of Manitoba, 50 Sifton Road, Winnipeg, MB, Canada R3T 2N2
| | - Pamela Zacharias
- Department of Biological Sciences, University of Manitoba, 50 Sifton Road, Winnipeg, MB, Canada R3T 2N2
| | - Emianka Sotiri
- Department of Biological Sciences, University of Manitoba, 50 Sifton Road, Winnipeg, MB, Canada R3T 2N2
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Tsai S, Sitzmann JM, Dastidar SG, Rodriguez AA, Vu SL, McDonald CE, Academia EC, O'Leary MN, Ashe TD, La Spada AR, Kennedy BK. Muscle-specific 4E-BP1 signaling activation improves metabolic parameters during aging and obesity. J Clin Invest 2015; 125:2952-64. [PMID: 26121750 DOI: 10.1172/jci77361] [Citation(s) in RCA: 90] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Accepted: 05/26/2015] [Indexed: 12/22/2022] Open
Abstract
Eukaryotic translation initiation factor 4E-binding protein 1 (4E-BP1) is a key downstream effector of mTOR complex 1 (mTORC1) that represses cap-dependent mRNA translation initiation by sequestering the translation initiation factor eIF4E. Reduced mTORC1 signaling is associated with life span extension and improved metabolic homeostasis, yet the downstream targets that mediate these benefits are unclear. Here, we demonstrated that enhanced 4E-BP1 activity in mouse skeletal muscle protects against age- and diet-induced insulin resistance and metabolic rate decline. Transgenic animals displayed increased energy expenditure; altered adipose tissue distribution, including reduced white adipose accumulation and preserved brown adipose mass; and were protected from hepatic steatosis. Skeletal muscle-specific 4E-BP1 mediated metabolic protection directly through increased translation of peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) and enhanced respiratory function. Non-cell autonomous protection was through preservation of brown adipose tissue metabolism, which was increased in 4E-BP1 transgenic animals during normal aging and in a response to diet-induced type 2 diabetes. Adipose phenotypes may derive from enhanced skeletal muscle expression and secretion of the known myokine FGF21. Unlike skeletal muscle, enhanced adipose-specific 4E-BP1 activity was not protective but instead was deleterious in response to the same challenges. These findings indicate that regulation of 4E-BP1 in skeletal muscle may serve as an important conduit through which mTORC1 controls metabolism.
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45
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Pyruvate dehydrogenase complex and nicotinamide nucleotide transhydrogenase constitute an energy-consuming redox circuit. Biochem J 2015; 467:271-80. [PMID: 25643703 DOI: 10.1042/bj20141447] [Citation(s) in RCA: 97] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Cellular proteins rely on reversible redox reactions to establish and maintain biological structure and function. How redox catabolic (NAD+/NADH) and anabolic (NADP+/NADPH) processes integrate during metabolism to maintain cellular redox homoeostasis, however, is unknown. The present work identifies a continuously cycling mitochondrial membrane potential (ΔΨm)-dependent redox circuit between the pyruvate dehydrogenase complex (PDHC) and nicotinamide nucleotide transhydrogenase (NNT). PDHC is shown to produce H2O2 in relation to reducing pressure within the complex. The H2O2 produced, however, is effectively masked by a continuously cycling redox circuit that links, via glutathione/thioredoxin, to NNT, which catalyses the regeneration of NADPH from NADH at the expense of ΔΨm. The net effect is an automatic fine-tuning of NNT-mediated energy expenditure to metabolic balance at the level of PDHC. In mitochondria, genetic or pharmacological disruptions in the PDHC-NNT redox circuit negate counterbalance changes in energy expenditure. At the whole animal level, mice lacking functional NNT (C57BL/6J) are characterized by lower energy-expenditure rates, consistent with their well-known susceptibility to diet-induced obesity. These findings suggest the integration of redox sensing of metabolic balance with compensatory changes in energy expenditure provides a potential mechanism by which cellular redox homoeostasis is maintained and body weight is defended during periods of positive and negative energy balance.
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Zolfaghari PS, Carré JE, Parker N, Curtin NA, Duchen MR, Singer M. Skeletal muscle dysfunction is associated with derangements in mitochondrial bioenergetics (but not UCP3) in a rodent model of sepsis. Am J Physiol Endocrinol Metab 2015; 308:E713-25. [PMID: 25714676 PMCID: PMC4420898 DOI: 10.1152/ajpendo.00562.2014] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Accepted: 02/18/2015] [Indexed: 12/31/2022]
Abstract
Muscle dysfunction is a common feature of severe sepsis and multiorgan failure. Recent evidence implicates bioenergetic dysfunction and oxidative damage as important underlying pathophysiological mechanisms. Increased abundance of uncoupling protein-3 (UCP3) in sepsis suggests increased mitochondrial proton leak, which may reduce mitochondrial coupling efficiency but limit reactive oxygen species (ROS) production. Using a murine model, we examined metabolic, cardiovascular, and skeletal muscle contractile changes following induction of peritoneal sepsis in wild-type and Ucp3(-/-) mice. Mitochondrial membrane potential (Δψm) was measured using two-photon microscopy in living diaphragm, and contractile function was measured in diaphragm muscle strips. The kinetic relationship between membrane potential and oxygen consumption was determined using a modular kinetic approach in isolated mitochondria. Sepsis was associated with significant whole body metabolic suppression, hypothermia, and cardiovascular dysfunction. Maximal force generation was reduced and fatigue accelerated in ex vivo diaphragm muscle strips from septic mice. Δψm was lower in the isolated diaphragm from septic mice despite normal substrate oxidation kinetics and proton leak in skeletal muscle mitochondria. Even though wild-type mice exhibited an absolute 26 ± 6% higher UCP3 protein abundance at 24 h, no differences were seen in whole animal or diaphragm physiology, nor in survival rates, between wild-type and Ucp3(-/-) mice. In conclusion, this murine sepsis model shows a hypometabolic phenotype with evidence of significant cardiovascular and muscle dysfunction. This was associated with lower Δψm and alterations in mitochondrial ATP turnover and the phosphorylation pathway. However, UCP3 does not play an important functional role, despite its upregulation.
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Affiliation(s)
- Parjam S Zolfaghari
- Bloomsbury Institute for Intensive Care Medicine, University College London, London, United Kingdom; Department of Cell and Developmental Biology, University College London, London, United Kingdom
| | - Jane E Carré
- Bloomsbury Institute for Intensive Care Medicine, University College London, London, United Kingdom
| | - Nadeene Parker
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
| | - Nancy A Curtin
- National Heart and Lung Institute, Imperial College London, London, United Kingdom; and
| | - Michael R Duchen
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
| | - Mervyn Singer
- Bloomsbury Institute for Intensive Care Medicine, University College London, London, United Kingdom
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47
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Goncalves RLS, Quinlan CL, Perevoshchikova IV, Hey-Mogensen M, Brand MD. Sites of superoxide and hydrogen peroxide production by muscle mitochondria assessed ex vivo under conditions mimicking rest and exercise. J Biol Chem 2014; 290:209-27. [PMID: 25389297 DOI: 10.1074/jbc.m114.619072] [Citation(s) in RCA: 232] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The sites and rates of mitochondrial production of superoxide and H2O2 in vivo are not yet defined. At least 10 different mitochondrial sites can generate these species. Each site has a different maximum capacity (e.g. the outer quinol site in complex III (site IIIQo) has a very high capacity in rat skeletal muscle mitochondria, whereas the flavin site in complex I (site IF) has a very low capacity). The maximum capacities can greatly exceed the actual rates observed in the absence of electron transport chain inhibitors, so maximum capacities are a poor guide to actual rates. Here, we use new approaches to measure the rates at which different mitochondrial sites produce superoxide/H2O2 using isolated muscle mitochondria incubated in media mimicking the cytoplasmic substrate and effector mix of skeletal muscle during rest and exercise. We find that four or five sites dominate during rest in this ex vivo system. Remarkably, the quinol site in complex I (site IQ) and the flavin site in complex II (site IIF) each account for about a quarter of the total measured rate of H2O2 production. Site IF, site IIIQo, and perhaps site EF in the β-oxidation pathway account for most of the remainder. Under conditions mimicking mild and intense aerobic exercise, total production is much less, and the low capacity site IF dominates. These results give novel insights into which mitochondrial sites may produce superoxide/H2O2 in vivo.
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Affiliation(s)
| | - Casey L Quinlan
- From the Buck Institute for Research on Aging, Novato, California 94945
| | | | | | - Martin D Brand
- From the Buck Institute for Research on Aging, Novato, California 94945
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48
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Mookerjee SA, Goncalves RLS, Gerencser AA, Nicholls DG, Brand MD. The contributions of respiration and glycolysis to extracellular acid production. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2014; 1847:171-181. [PMID: 25449966 DOI: 10.1016/j.bbabio.2014.10.005] [Citation(s) in RCA: 233] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Revised: 10/20/2014] [Accepted: 10/22/2014] [Indexed: 12/13/2022]
Abstract
BACKGROUND The rate at which cells acidify the extracellular medium is frequently used to report glycolytic rate, with the implicit assumption that conversion of uncharged glucose or glycogen to lactate(-)+H(+) is the only significant source of acidification. However, another potential source of extracellular protons is the production of CO2 during substrate oxidation: CO2 is hydrated to H2CO3, which then dissociates to HCO3(-)+H(+). METHODS O2 consumption and pH were monitored in a popular platform for measuring extracellular acidification (the Seahorse XF Analyzer). RESULTS We found that CO2 produced during respiration caused almost stoichiometric release of H(+) into the medium. With C2C12 myoblasts given glucose, respiration-derived CO2 contributed 34% of the total extracellular acidification. When glucose was omitted or replaced by palmitate or pyruvate, this value was 67-100%. Analysis of primary cells, cancer cell lines, stem cell lines, and isolated synaptosomes revealed contributions of CO2-produced acidification that were usually substantial, ranging from 3% to 100% of the total acidification rate. CONCLUSION Measurement of glycolytic rate using extracellular acidification requires differentiation between respiratory and glycolytic acid production. GENERAL SIGNIFICANCE The data presented here demonstrate the importance of this correction when extracellular acidification is used for quantitative measurement of glycolytic flux to lactate. We describe a simple way to correct the measured extracellular acidification rate for respiratory acid production, using simultaneous measurement of oxygen consumption rate. SUMMARY STATEMENT Extracellular acidification is often assumed to result solely from glycolytic lactate production, but respiratory CO2 also contributes. We demonstrate that extracellular acidification by myoblasts given glucose is 66% glycolytic and 34% respiratory and describe a method to differentiate these sources.
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Affiliation(s)
- Shona A Mookerjee
- College of Pharmacy, Touro University California, 1310 Club Drive, Vallejo, CA 94592, USA; Buck Institute for Research on Aging, 8001 Redwood Blvd, Novato, CA 94945, USA.
| | | | - Akos A Gerencser
- College of Pharmacy, Touro University California, 1310 Club Drive, Vallejo, CA 94592, USA; Buck Institute for Research on Aging, 8001 Redwood Blvd, Novato, CA 94945, USA
| | - David G Nicholls
- Buck Institute for Research on Aging, 8001 Redwood Blvd, Novato, CA 94945, USA
| | - Martin D Brand
- College of Pharmacy, Touro University California, 1310 Club Drive, Vallejo, CA 94592, USA; Buck Institute for Research on Aging, 8001 Redwood Blvd, Novato, CA 94945, USA
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49
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Hey-Mogensen M, Goncalves RLS, Orr AL, Brand MD. Production of superoxide/H2O2 by dihydroorotate dehydrogenase in rat skeletal muscle mitochondria. Free Radic Biol Med 2014; 72:149-55. [PMID: 24746616 DOI: 10.1016/j.freeradbiomed.2014.04.007] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2014] [Revised: 04/01/2014] [Accepted: 04/05/2014] [Indexed: 10/25/2022]
Abstract
Dehydrogenases that use ubiquinone as an electron acceptor, including complex I of the respiratory chain, complex II, and glycerol-3-phosphate dehydrogenase, are known to be direct generators of superoxide and/or H2O2. Dihydroorotate dehydrogenase oxidizes dihydroorotate to orotate and reduces ubiquinone to ubiquinol during pyrimidine metabolism, but it is unclear whether it produces superoxide and/or H2O2 directly or does so only indirectly from other sites in the electron transport chain. Using mitochondria isolated from rat skeletal muscle we establish that dihydroorotate oxidation leads to superoxide/H2O2 production at a fairly high rate of about 300pmol H2O2·min(-1)·mg protein(-1) when oxidation of ubiquinol is prevented and complex II is uninhibited. This H2O2 production is abolished by brequinar or leflunomide, known inhibitors of dihydroorotate dehydrogenase. Eighty percent of this rate is indirect, originating from site IIF of complex II, because it can be prevented by malonate or atpenin A5, inhibitors of complex II. In the presence of inhibitors of all known sites of superoxide/H2O2 production (rotenone to inhibit sites in complex I (site IQ and, indirectly, site IF), myxothiazol to inhibit site IIIQo in complex III, and malonate plus atpenin A5 to inhibit site IIF in complex II), dihydroorotate dehydrogenase generates superoxide/H2O2, at a small but significant rate (23pmol H2O2·min(-1)·mg protein(-1)), from the ubiquinone-binding site. We conclude that dihydroorotate dehydrogenase can generate superoxide and/or H2O2 directly at low rates and is also capable of indirect production at higher rates from other sites through its ability to reduce the ubiquinone pool.
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Affiliation(s)
- Martin Hey-Mogensen
- Buck Institute for Research on Aging, Novato, CA 94945, USA; Department of Biomedical Sciences, Center for Healthy Aging, Copenhagen University, Copenhagen, Denmark
| | | | - Adam L Orr
- Buck Institute for Research on Aging, Novato, CA 94945, USA
| | - Martin D Brand
- Buck Institute for Research on Aging, Novato, CA 94945, USA.
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Robb EL, Christoff CA, Maddalena LA, Stuart JA. Mitochondrial reactive oxygen species (ROS) in animal cells: relevance to aging and normal physiology. CAN J ZOOL 2014. [DOI: 10.1139/cjz-2013-0131] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
In animal mitochondria, the four electron reduction of molecular oxygen to produce water at respiratory complex IV is the terminal step in substrate oxidation. However, respiratory complexes I, II, and III can participate in the single electron reduction of oxygen to produce the radical species superoxide. This progenitor reactive oxygen species (ROS) participates in a number of reactions that generate other ROS. These molecules may react with, and damage, intracellular macromolecules, leading to cellular dysfunction. Mitochondrial ROS production is often considered from this perspective of macromolecular damage and is central to the “oxidative damage theory of aging”, which suggests the accumulation of oxidative damage in animal cells underlies the aging phenotype and limits lifespan. In this review, we discuss some experimental results accumulated over the past decade that are inconsistent with this theory. A limitation of the theory is that it presupposes mitochondrial ROS are inherently harmful. However, it is increasingly apparent that some basic cellular functions are physiologically regulated by normal levels of mitochondrial ROS. For example, cell growth and division, the apoptotic pathway, and mitochondrial fusion–fission dynamics all appear to be redox-regulated by mitochondrial ROS and perhaps the matrix manganese superoxide dismutase (MnSOD). Therefore, it is less clear how the balance between ROS regulation of normal cellular activities and ROS-mediated macromolecular damage is maintained and how this relates to aging and longevity in animals.
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Affiliation(s)
- Ellen L. Robb
- Department of Biological Sciences, Brock University, St. Catharines, ON L2S 3A1, Canada
| | - Casey A. Christoff
- Department of Biological Sciences, Brock University, St. Catharines, ON L2S 3A1, Canada
| | - Lucas A. Maddalena
- Department of Biological Sciences, Brock University, St. Catharines, ON L2S 3A1, Canada
| | - Jeffrey A. Stuart
- Department of Biological Sciences, Brock University, St. Catharines, ON L2S 3A1, Canada
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