101
|
Hwang HJ, Lynn SG, Vengellur A, Saini Y, Grier EA, Ferguson-Miller SM, LaPres JJ. Hypoxia Inducible Factors Modulate Mitochondrial Oxygen Consumption and Transcriptional Regulation of Nuclear-Encoded Electron Transport Chain Genes. Biochemistry 2015; 54:3739-48. [PMID: 26030260 PMCID: PMC5957085 DOI: 10.1021/bi5012892] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Hypoxia inducible factor-1 (HIF1) is a stress-responsive nuclear transcription factor that is activated with a decrease in oxygen availability. HIF1 regulates the expression of genes involved in a cell's adaptation to hypoxic stress, including those with mitochondrial specific function. To gain a more comprehensive understanding of the role of HIF1 in mitochondrial homeostasis, we studied the link between hypoxia, HIF1 transactivation, and electron transport chain (ETC) function. We established immortalized mouse embryonic fibroblasts (MEFs) for HIF1α wild-type (WT) and null cells and tested whether HIF1α regulates mitochondrial respiration by modulating gene expressions of nuclear-encoded ETC components. High-throughput quantitative real-time polymerase chain reaction was performed to screen nuclear-encoded mitochondrial genes related to the ETC to identify those whose regulation was HIF1α-dependent. Our data suggest that HIF1α regulates transcription of cytochrome c oxidase (CcO) heart/muscle isoform 7a1 (Cox7a1) under hypoxia, where it is induced 1.5-2.5-fold, whereas Cox4i2 hypoxic induction was HIF1α-independent. We propose that adaptation to hypoxic stress of CcO as the main cellular oxygen consumer is mediated by induction of hypoxia-sensitive tissue-specific isoforms. We suggest that HIF1 plays a central role in maintaining homeostasis in cellular respiration during hypoxic stress via regulation of CcO activity.
Collapse
Affiliation(s)
- Hye Jin Hwang
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824-1319, United States
- Center for Mitochondrial Science and Medicine, Michigan State University, East Lansing, Michigan 48824-1319, United States
| | - Scott G. Lynn
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824-1319, United States
- Center for Integrative Toxicology, Michigan State University, East Lansing, Michigan 48824-1319, United States
| | - Ajith Vengellur
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824-1319, United States
| | - Yogesh Saini
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824-1319, United States
- Center for Integrative Toxicology, Michigan State University, East Lansing, Michigan 48824-1319, United States
| | - Elizabeth A. Grier
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824-1319, United States
| | - Shelagh M. Ferguson-Miller
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824-1319, United States
- Center for Mitochondrial Science and Medicine, Michigan State University, East Lansing, Michigan 48824-1319, United States
| | - John J. LaPres
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824-1319, United States
- Center for Integrative Toxicology, Michigan State University, East Lansing, Michigan 48824-1319, United States
- Center for Mitochondrial Science and Medicine, Michigan State University, East Lansing, Michigan 48824-1319, United States
| |
Collapse
|
102
|
Abstract
Mitochondria are highly dynamic organelles comprising at least three distinct areas, the OMM (outer mitochondrial membrane), the IMS (intermembrane space) and the mitochondrial matrix. Physical compartmentalization allows these organelles to host different functional domains and therefore participate in a variety of important cellular actions such as ATP synthesis and programmed cell death. In a surprising homology, it is now widely accepted that the ubiquitous second messenger cAMP uses the same stratagem, compartmentalization, in order to achieve the characteristic functional pleiotropy of its pathway. Accumulating evidence suggests that all the main mitochondrial compartments contain segregated cAMP cascades; however, the regulatory properties and functional significance of such domains are not fully understood and often remain controversial issues. The present mini-review discusses our current knowledge of how the marriage between mitochondrial and cAMP compartmentalization is achieved and its effects on the biology of the cell.
Collapse
|
103
|
Covian R, French S, Kusnetz H, Balaban RS. Stimulation of oxidative phosphorylation by calcium in cardiac mitochondria is not influenced by cAMP and PKA activity. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2015; 1837:1913-1921. [PMID: 25178840 DOI: 10.1016/j.bbabio.2014.08.006] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Revised: 08/21/2014] [Accepted: 08/23/2014] [Indexed: 12/31/2022]
Abstract
Cardiac oxidative ATP generation is finely tuned to match several-fold increases in energy demand. Calcium has been proposed to play a role in the activation of ATP production via PKA phosphorylation in response to intramitochondrial cAMP generation. We evaluated the effect of cAMP, its membrane permeable analogs (dibutyryl-cAMP, 8-bromo-cAMP), and the PKA inhibitor H89 on respiration of isolated pig heart mitochondria. cAMP analogs did not stimulate State 3 respiration of Ca2 +-depleted mitochondria (82.2 ± 3.6% of control), in contrast to the 2-fold activation induced by 0.95 μM free Ca2 +, which was unaffected by H89. Using fluorescence and integrating sphere spectroscopy, we determined that Ca2 + increased the reduction of NADH (8%), and of cytochromes bH (3%), c1 (3%), c (4%), and a (2%), together with a doubling of conductances for Complex I + III and Complex IV. None of these changes were induced by cAMP analogs nor abolished by H89. In Ca2 +-undepleted mitochondria, we observed only slight changes in State 3 respiration rates upon addition of 50 μM cAMP (85 ± 9.9%), dibutyryl-cAMP (80.1 ± 5.2%), 8-bromo-cAMP (88.6 ± 3.3%), or 1 μM H89 (89.7 ± 19.9%) with respect to controls. Similar results were obtained when measuring respiration in heart homogenates. Addition of exogenous PKA with dibutyryl-cAMP or the constitutively active catalytic subunit of PKA to isolated mitochondria decreased State 3 respiration by only 5–15%. These functional studies suggest that alterations in mitochondrial cAMP and PKA activity do not contribute significantly to the acute Ca2 + stimulation of oxidative phosphorylation
Collapse
Affiliation(s)
- Raul Covian
- Laboratory of Cardiac Energetics, National Heart, Lung, and Blood Institute, National Institutes of Health, 10 Center Dr, Room B1D416, Bethesda, MD 20892, USA.
| | - Stephanie French
- Laboratory of Cardiac Energetics, National Heart, Lung, and Blood Institute, National Institutes of Health, 10 Center Dr, Room B1D416, Bethesda, MD 20892, USA
| | - Heather Kusnetz
- Laboratory of Cardiac Energetics, National Heart, Lung, and Blood Institute, National Institutes of Health, 10 Center Dr, Room B1D416, Bethesda, MD 20892, USA
| | - Robert S Balaban
- Laboratory of Cardiac Energetics, National Heart, Lung, and Blood Institute, National Institutes of Health, 10 Center Dr, Room B1D416, Bethesda, MD 20892, USA
| |
Collapse
|
104
|
Lee I, Hüttemann M, Kruger A, Bollig-Fischer A, Malek MH. (-)-Epicatechin combined with 8 weeks of treadmill exercise is associated with increased angiogenic and mitochondrial signaling in mice. Front Pharmacol 2015; 6:43. [PMID: 25821434 PMCID: PMC4358069 DOI: 10.3389/fphar.2015.00043] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Accepted: 02/18/2015] [Indexed: 11/13/2022] Open
Abstract
The purpose of this study was to conduct an 8 week endurance training program with and without (–)–epicatechin treatment and to determine whether there is a possible cumulative effect on protein markers of angiogenesis and mitochondrial biogenesis. Thirty-four 14-month old male mice (C57BL/6N) were randomized into four groups: control (C); (–)–epicatechin only ((–)–Epi); control with endurance training (CE); and (–)–epicatechin with endurance training ((–)–Epi-Ex). Mice in the training groups performed treadmill exercise for 8 weeks (5 × /week for 60 min/session), whereas mice in the (–)–epicatechin group received 1.0 mg/kg of body mass twice daily during the training period. At 8 weeks, distance ran on the treadmill increased by 46, 69, and 84% in the (–)–Epi, CE, and (–)–Epi-Ex groups, respectively compared to the control group (p < 0.001 for all comparisons). Furthermore, the (–)–Epi-Ex group had significantly higher exercise capacity than the (–)–Epi and CE group. For angiogenic regulators, the (–)–Epi-Ex group had significantly higher VEGF-R2 protein expression with a concomitant reduction in TSP-1 protein expression than the exercise group. Interestingly, FoxO1 protein expression was significantly reduced for all three experimental groups compared to the control group. Protein markers such as PGC-1β and TFAM were significantly higher in the (–)–Epi-Ex group compared to the three other groups. These findings suggest that (–)–epicatechin treatment combined with 8 weeks of endurance training provide a cumulative effect on a number of angiogenic and mitochondrial signaling which functionally translates to enhanced exercise tolerance.
Collapse
Affiliation(s)
- Icksoo Lee
- College of Medicine, Dankook University , Cheonan-si, South Korea
| | - Maik Hüttemann
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine , Detroit, MI, USA ; Cardiovascular Research Institute, Wayne State University School of Medicine , Detroit, MI, USA
| | - Adele Kruger
- Department of Obstetrics and Gynecology, Wayne State University , Detroit, MI, USA
| | | | - Moh H Malek
- Cardiovascular Research Institute, Wayne State University School of Medicine , Detroit, MI, USA ; Integrative Physiology of Exercise Laboratory, Department of Health Care Sciences, Wayne State University Eugene Applebaum College of Pharmacy and Health Sciences , Detroit, MI, USA
| |
Collapse
|
105
|
Targeting mitochondria metabolism for cancer therapy. Nat Chem Biol 2015; 11:9-15. [PMID: 25517383 DOI: 10.1038/nchembio.1712] [Citation(s) in RCA: 980] [Impact Index Per Article: 108.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Accepted: 11/04/2014] [Indexed: 01/02/2023]
Abstract
Mitochondria have a well-recognized role in the production of ATP and the intermediates needed for macromolecule biosynthesis, such as nucleotides. Mitochondria also participate in the activation of signaling pathways. Overall, accumulating evidence now suggests that mitochondrial bioenergetics, biosynthesis and signaling are required for tumorigenesis. Thus, emerging studies have begun to demonstrate that mitochondrial metabolism is potentially a fruitful arena for cancer therapy. In this Perspective, we highlight recent developments in targeting mitochondrial metabolism for the treatment of cancer.
Collapse
|
106
|
Abstract
Subunit 5 of Saccharomyces cerevisiae cytochrome c oxidase (CcO) is essential for assembly and has two isoforms, 5A and 5B. 5A is expressed under normoxic conditions, whereas 5B is expressed at very low oxygen tensions. As a consequence, COX5A-deleted strains (Δcox5A) have no or only low levels of CcO under normoxic conditions rendering them respiratory deficient. Previous studies have reported that respiratory growth could be restored by combining Δcox5A with mutations of ROX1 that encodes a repressor of COX5B expression. In these mutants, 5B isoenzyme expression level was 30–50% of wild-type (5A isoenzyme) and exhibited a maximum catalytic activity up to 3-fold faster than that of 5A isoenzyme. To investigate the origin of this effect, we constructed a mutant strain in which COX5B replaced COX5A downstream of the COX5A promoter. This strain expressed wild-type levels of the 5B isoenzyme, without the complication of additional effects caused by mutation of ROX1. When produced this way, the isoenzymes displayed no significant differences in their maximum catalytic activities or in their affinities for oxygen or cytochrome c. Hence the elevated activity of the 5B isoenzyme in the rox1 mutant is not caused simply by exchange of isoforms and must arise from an additional effect that remains to be resolved. Yeast cytochrome c oxidase isoenzymes with subunits 5A or 5B can exhibit different kinetic properties. We demonstrate that these differences are not induced by simple 5A/5B replacement and that the effect additionally requires expression level changes and/or undefined post-translational effects.
Collapse
|
107
|
Affiliation(s)
- Lonny R. Levin
- Department of Pharmacology, Weill Cornell Medical College, New York, NY 10065; ,
| | - Jochen Buck
- Department of Pharmacology, Weill Cornell Medical College, New York, NY 10065; ,
| |
Collapse
|
108
|
Torraco A, Peralta S, Iommarini L, Diaz F. Mitochondrial Diseases Part I: mouse models of OXPHOS deficiencies caused by defects in respiratory complex subunits or assembly factors. Mitochondrion 2015; 21:76-91. [PMID: 25660179 DOI: 10.1016/j.mito.2015.01.009] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Revised: 11/22/2014] [Accepted: 01/05/2015] [Indexed: 10/24/2022]
Abstract
Mitochondrial disorders are the most common inborn errors of metabolism affecting the oxidative phosphorylation system (OXPHOS). Because of the poor knowledge of the pathogenic mechanisms, a cure for these disorders is still unavailable and all the treatments currently in use are supportive more than curative. Therefore, in the past decade a great variety of mouse models have been developed to assess the in vivo function of several mitochondrial proteins involved in human diseases. Due to the genetic and physiological similarity to humans, mice represent reliable models to study the pathogenic mechanisms of mitochondrial disorders and are precious to test new therapeutic approaches. Here we summarize the features of several mouse models of mitochondrial diseases directly related to defects in subunits of the OXPHOS complexes or in assembly factors. We discuss how these models recapitulate many human conditions and how they have contributed to the understanding of mitochondrial function in health and disease.
Collapse
Affiliation(s)
- Alessandra Torraco
- Unit for Neuromuscular and Neurodegenerative Disorders, Laboratory of Molecular Medicine, Bambino Gesù Children's Hospital, IRCCS, Viale di San Paolo, 15-00146 Rome, Italy.
| | - Susana Peralta
- Department of Neurology, University of Miami, Miller School of Medicine, Miami, FL 33136, USA.
| | - Luisa Iommarini
- Department of Pharmacy and Biotechnology (FABIT), University of Bologna, Via Irnerio 42, 40126 Bologna, Italy.
| | - Francisca Diaz
- Department of Neurology, University of Miami, Miller School of Medicine, Miami, FL 33136, USA.
| |
Collapse
|
109
|
Kalaivani R, Srinivasan N. A Gaussian network model study suggests that structural fluctuations are higher for inactive states than active states of protein kinases. MOLECULAR BIOSYSTEMS 2015; 11:1079-95. [DOI: 10.1039/c4mb00675e] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Protein kinases participate extensively in cellular signalling. Using Gaussian normal mode analysis of kinases in active and diverse inactive forms, authors show that structural fluctuations are significantly higher in inactive forms and are localized in functionally sensitive sites.
Collapse
Affiliation(s)
- Raju Kalaivani
- Molecular Biophysics Unit
- Indian Institute of Science
- Bangalore 560012
- India
| | | |
Collapse
|
110
|
Wu D, Hu Q, Liu X, Pan L, Xiong Q, Zhu YZ. Hydrogen sulfide protects against apoptosis under oxidative stress through SIRT1 pathway in H9c2 cardiomyocytes. Nitric Oxide 2014; 46:204-12. [PMID: 25461268 DOI: 10.1016/j.niox.2014.11.006] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Revised: 10/31/2014] [Accepted: 11/10/2014] [Indexed: 10/24/2022]
Abstract
Oxidative stress plays a great role in the pathogenesis of heart failure (HF). Oxidative stress results in apoptosis, which can cause the damage of cardiomyocytes. Hydrogen sulfide (H2S), the third gasotransmitter, is a good reactive oxygen species (ROS) scavenger, which has protective effect against HF. Sirtuin-1 (SIRT1) is a highly conserved nicotinamide adenine dinucleotide (NAD)-dependent histone deacetylase that plays a critical role in promoting cell survival under oxidative stress. The purpose of this article is to investigate the interaction between H2S and SIRT1 under oxidative stress in H9c2 cardiomyocytes. Oxidative stress was induced by hydrogen peroxide (H2O2). Treatment with NaSH (25-100 µmol/L) dose-dependently increased the cell viability and improved the cell apoptosis induced by H2O2 in H9c2 cardiomyocytes. The protective effect of NaSH against the apoptosis could be attenuated by SIRT1 inhibitor Ex 527 (10 µmol/L). Treatment with NaSH (100 µmol/L) could increase the expression of SIRT1 in time dependent manner, which decreased by different concentration of H2O2. NaSH (100 µmol/L) increased the cellular ATP level and the expression of ATPase. These effects were attenuated by Ex 527 (10 µmol/L). After NaSH (100 µmol/L) treatment, the decrease in ROS production and the enhancement in SOD, GPx and GST expression were observed. Ex 527 (10 µmol/L) reversed these effects. In conclusion, for the first time, this article can identify antioxidative effects of H2S under oxidative stress through SIRT1 pathway in H9c2 cardiomyocytes.
Collapse
Affiliation(s)
- Dan Wu
- Department of Pharmacology, School of Pharmacy, Fudan University, Shanghai, China
| | - Qingxun Hu
- Department of Pharmacology, School of Pharmacy, Fudan University, Shanghai, China
| | - Xinhua Liu
- Department of Pharmacology, School of Pharmacy, Fudan University, Shanghai, China
| | - Lilong Pan
- Department of Pharmacology, School of Pharmacy, Fudan University, Shanghai, China
| | - Qinghui Xiong
- Department of Pharmacology, School of Pharmacy, Fudan University, Shanghai, China
| | - Yi Zhun Zhu
- Department of Pharmacology, School of Pharmacy, Fudan University, Shanghai, China; Department of Pharmacology, Loo Yong Lin School of Medicine, National University of Singapore, Singapore.
| |
Collapse
|
111
|
Hess KC, Liu J, Manfredi G, Mühlschlegel FA, Buck J, Levin LR, Barrientos A. A mitochondrial CO2-adenylyl cyclase-cAMP signalosome controls yeast normoxic cytochrome c oxidase activity. FASEB J 2014; 28:4369-80. [PMID: 25002117 PMCID: PMC4202101 DOI: 10.1096/fj.14-252890] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2014] [Accepted: 06/16/2014] [Indexed: 12/30/2022]
Abstract
Mitochondria, the major source of cellular energy in the form of ATP, respond to changes in substrate availability and bioenergetic demands by employing rapid, short-term, metabolic adaptation mechanisms, such as phosphorylation-dependent protein regulation. In mammalian cells, an intramitochondrial CO2-adenylyl cyclase (AC)-cyclic AMP (cAMP)-protein kinase A (PKA) pathway regulates aerobic energy production. One target of this pathway involves phosphorylation of cytochrome c oxidase (COX) subunit 4-isoform 1 (COX4i1), which modulates COX allosteric regulation by ATP. However, the role of the CO2-sAC-cAMP-PKA signalosome in regulating COX activity and mitochondrial metabolism and its evolutionary conservation remain to be fully established. We show that in Saccharomyces cerevisiae, normoxic COX activity measured in the presence of ATP is 55% lower than in the presence of ADP. Moreover, the adenylyl cyclase Cyr1 activity is present in mitochondria, and it contributes to the ATP-mediated regulation of COX through the normoxic subunit Cox5a, homologue of human COX4i1, in a bicarbonate-sensitive manner. Furthermore, we have identified 2 phosphorylation targets in Cox5a (T65 and S43) that modulate its allosteric regulation by ATP. These residues are not conserved in the Cox5b-containing hypoxic enzyme, which is not regulated by ATP. We conclude that across evolution, a CO2-sAC-cAMP-PKA axis regulates normoxic COX activity.
Collapse
Affiliation(s)
| | - Jingjing Liu
- Department of Biochemistry and Molecular Biology and
| | - Giovanni Manfredi
- Brain and Mind Research Institute, Weill Cornell Medical College, New York, New York, USA
| | | | | | | | - Antoni Barrientos
- Department of Biochemistry and Molecular Biology and Department of Neurology, University of Miami Miller School of Medicine, Miami, Florida, USA; and
| |
Collapse
|
112
|
Enriquez JA, Lenaz G. Coenzyme q and the respiratory chain: coenzyme q pool and mitochondrial supercomplexes. Mol Syndromol 2014; 5:119-40. [PMID: 25126045 DOI: 10.1159/000363364] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Two alternative models of organization of the mitochondrial electron transport chain (mETC) have been alternatively favored or questioned by the accumulation evidences of different sources, the solid model or the random collision model. Both agree in the number of respiratory complexes (I-IV) that participate in the mETC, but while the random collision model proposes that Complexes I-IV do not interact physically and that electrons are transferred between them by coenzyme Q and cytochrome c, the solid model proposes that all complexes super-assemble in the so-called respirasome. Recently, the plasticity model has been developed to incorporate the solid and the random collision model as extreme situations of a dynamic organization, allowing super-assembly free movement of the respiratory complexes. In this review, we evaluate the supporting evidences of each model and the implications of the super-assembly in the physiological role of coenzyme Q.
Collapse
Affiliation(s)
| | - Giorgio Lenaz
- Dipartimento di Scienze Biomediche e Neuromotorie, Università di Bologna, Bologna, Italy
| |
Collapse
|
113
|
Hofer A, Wenz T. Post-translational modification of mitochondria as a novel mode of regulation. Exp Gerontol 2014; 56:202-20. [DOI: 10.1016/j.exger.2014.03.006] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Revised: 03/01/2014] [Accepted: 03/04/2014] [Indexed: 12/26/2022]
|
114
|
Bremer K, Kocha K, Snider T, Moyes C. Energy metabolism and cytochrome oxidase activity: linking metabolism to gene expression. CAN J ZOOL 2014. [DOI: 10.1139/cjz-2013-0267] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Modification of mitochondrial content demands the synthesis of hundreds of proteins encoded by nuclear and mitochondrial genomes. The responsibility for coordination of this process falls to nuclear-encoded master regulators of transcription. DNA-binding proteins and coactivators integrate information from energy-sensing pathways and hormones to alter mitochondrial gene expression. In mammals, the signaling cascade for mitochondrial biogenesis can be described as follows: hormonal signals and energetic information are sensed by protein-modifying enzymes that in turn regulate the post-translational modification of transcription factors. Once activated, transcription-factor complexes form on promoter elements of many of the nuclear-encoded mitochondrial genes, recruiting proteins that remodel chromatin and initiate transcription. One master regulator in mammals, PGC-1α, is well studied because of its role in determining the metabolic phenotype of muscles, but also due to its importance in mitochondria-related metabolic diseases. However, relatively little is known about the role of this pathway in other vertebrates. These uncertainties raise broader questions about the evolutionary origins of the pathway and its role in generating the diversity in muscle metabolic phenotypes seen in nature.
Collapse
Affiliation(s)
- K. Bremer
- Department of Biology, Biosciences Complex, Queen’s University, Kingston, ON K7L 3N6, Canada
| | - K.M. Kocha
- Department of Biology, Biosciences Complex, Queen’s University, Kingston, ON K7L 3N6, Canada
| | - T. Snider
- Department of Biology, Biosciences Complex, Queen’s University, Kingston, ON K7L 3N6, Canada
| | - C.D. Moyes
- Department of Biology, Biosciences Complex, Queen’s University, Kingston, ON K7L 3N6, Canada
| |
Collapse
|
115
|
Valsecchi F, Konrad C, Manfredi G. Role of soluble adenylyl cyclase in mitochondria. Biochim Biophys Acta Mol Basis Dis 2014; 1842:2555-60. [PMID: 24907564 DOI: 10.1016/j.bbadis.2014.05.035] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Revised: 05/19/2014] [Accepted: 05/28/2014] [Indexed: 11/25/2022]
Abstract
The soluble adenylyl cyclase (sAC) catalyzes the conversion of ATP into cyclic AMP (cAMP). Recent studies have shed new light on the role of sAC localized in mitochondria and its product cAMP, which drives mitochondrial protein phosphorylation and regulation of the oxidative phosphorylation system and other metabolic enzymes, presumably through the activation of intra-mitochondrial PKA. In this review article, we summarize recent findings on mitochondrial sAC activation by bicarbonate (HCO(3)(-)) and calcium (Ca²⁺) and the effects on mitochondrial metabolism. We also discuss putative mechanisms whereby sAC-mediated mitochondrial protein phosphorylation regulates mitochondrial metabolism. This article is part of a Special Issue entitled: The role of soluble adenylyl cyclase in health and disease.
Collapse
Affiliation(s)
- Federica Valsecchi
- Brain and Mind Research Institute, Weill Medical College of Cornell University, New York, NY 10065, USA
| | - Csaba Konrad
- Brain and Mind Research Institute, Weill Medical College of Cornell University, New York, NY 10065, USA
| | - Giovanni Manfredi
- Brain and Mind Research Institute, Weill Medical College of Cornell University, New York, NY 10065, USA.
| |
Collapse
|
116
|
Abstract
PURPOSE This study addresses the effect of short myocardial ischemia on inhibitory effect of ATP for mitochondrial cytochrome c oxidase (CytOx) activity in myocardium and subsequent hemodynamic alterations. The activity of CytOx is inhibited by ATP (primary substrate control). This additional mechanism was proposed to be switched off at higher mitochondrial membrane potential values in case of stress. The ATP-dependent allosteric enzyme inhibition (second respiratory control) is suggested to reduce the formation of reactive oxygen species and thus is pivotal for cytoprotection. This report addresses the possible involvement of this mechanism in case of myocardial preconditioning. METHODS Rat hearts were perfused in a Langendorff system (n = 5 each group). The first two groups underwent short recurrent ischemic periods (three times 5 min) and subsequent high or low reperfusion for 40 min. Besides four control groups, hearts were exposed to an ischemia of 15 min and high flow reperfused for 30 min, in addition. Hemodynamic data were evaluated in parallel. Mitochondria were separated for the polarographic respiration measurements in the presence of ADP or ATP, respectively. Phosphorylation patterns of the CytOx subunits were studied by immunoblotting with P-Ser, P-Thr, and P-Tyr antibodies. RESULTS Short recurrent episodes of ischemia result in an ATP-dependent inhibition of CytOx. Electrophoretic analysis and blotting techniques reveal different phosphorylation patterns of the enzyme. Frequent short-lasting ischemic impacts and subsequent increased coronary flow seem to be essential for this effect. CONCLUSION The procedure of preconditioning is likely to be dependent on the mechanism of ATP-dependent inhibition of CytOx activity.
Collapse
|
117
|
Lanning NJ, Looyenga BD, Kauffman AL, Niemi NM, Sudderth J, DeBerardinis RJ, MacKeigan JP. A mitochondrial RNAi screen defines cellular bioenergetic determinants and identifies an adenylate kinase as a key regulator of ATP levels. Cell Rep 2014; 7:907-17. [PMID: 24767988 DOI: 10.1016/j.celrep.2014.03.065] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2013] [Revised: 03/01/2014] [Accepted: 03/26/2014] [Indexed: 12/25/2022] Open
Abstract
Altered cellular bioenergetics and mitochondrial function are major features of several diseases, including cancer, diabetes, and neurodegenerative disorders. Given this important link to human health, we sought to define proteins within mitochondria that are critical for maintaining homeostatic ATP levels. We screened an RNAi library targeting >1,000 nuclear-encoded genes whose protein products localize to the mitochondria in multiple metabolic conditions in order to examine their effects on cellular ATP levels. We identified a mechanism by which electron transport chain (ETC) perturbation under glycolytic conditions increased ATP production through enhanced glycolytic flux, thereby highlighting the cellular potential for metabolic plasticity. Additionally, we identified a mitochondrial adenylate kinase (AK4) that regulates cellular ATP levels and AMPK signaling and whose expression significantly correlates with glioma patient survival. This study maps the bioenergetic landscape of >1,000 mitochondrial proteins in the context of varied metabolic substrates and begins to link key metabolic genes with clinical outcome.
Collapse
Affiliation(s)
- Nathan J Lanning
- Laboratory of Systems Biology, Van Andel Research Institute, Grand Rapids, MI 49503, USA
| | - Brendan D Looyenga
- Laboratory of Systems Biology, Van Andel Research Institute, Grand Rapids, MI 49503, USA; Department of Chemistry and Biochemistry, Calvin College, Grand Rapids, MI 49546, USA
| | - Audra L Kauffman
- Laboratory of Systems Biology, Van Andel Research Institute, Grand Rapids, MI 49503, USA
| | - Natalie M Niemi
- Laboratory of Systems Biology, Van Andel Research Institute, Grand Rapids, MI 49503, USA
| | - Jessica Sudderth
- Department of Pediatrics, Children's Medical Center Research Institute, and McDermott Center for Human Growth and Development, University of Texas Southwestern Medical Center, Dallas, TX 75390-8502, USA
| | - Ralph J DeBerardinis
- Department of Pediatrics, Children's Medical Center Research Institute, and McDermott Center for Human Growth and Development, University of Texas Southwestern Medical Center, Dallas, TX 75390-8502, USA
| | - Jeffrey P MacKeigan
- Laboratory of Systems Biology, Van Andel Research Institute, Grand Rapids, MI 49503, USA.
| |
Collapse
|
118
|
Functional role of mitochondrial respiratory supercomplexes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2014; 1837:427-43. [DOI: 10.1016/j.bbabio.2013.11.002] [Citation(s) in RCA: 224] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Revised: 10/30/2013] [Accepted: 11/02/2013] [Indexed: 12/30/2022]
|
119
|
Chang JC, Oude-Elferink RPJ. Role of the bicarbonate-responsive soluble adenylyl cyclase in pH sensing and metabolic regulation. Front Physiol 2014; 5:42. [PMID: 24575049 PMCID: PMC3918592 DOI: 10.3389/fphys.2014.00042] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2013] [Accepted: 01/22/2014] [Indexed: 12/18/2022] Open
Abstract
The evolutionarily conserved soluble adenylyl cyclase (sAC, adcy10) was recently identified as a unique source of cAMP in the cytoplasm and the nucleus. Its activity is regulated by bicarbonate and fine-tuned by calcium. As such, and in conjunction with carbonic anhydrase (CA), sAC constitutes an HCO(-) 3/CO(-) 2/pH sensor. In both alpha-intercalated cells of the collecting duct and the clear cells of the epididymis, sAC is expressed at significant level and involved in pH homeostasis via apical recruitment of vacuolar H(+)-ATPase (VHA) in a PKA-dependent manner. In addition to maintenance of pH homeostasis, sAC is also involved in metabolic regulation such as coupling of Krebs cycle to oxidative phosphorylation via bicarbonate/CO2 sensing. Additionally, sAC also regulates CFTR channel and plays an important role in regulation of barrier function and apoptosis. These observations suggest that sAC, via bicarbonate-sensing, plays an important role in maintaining homeostatic status of cells against fluctuations in their microenvironment.
Collapse
Affiliation(s)
- Jung-Chin Chang
- Tytgat Institute for Liver and Intestinal Research, Academic Medical Center, University of Amsterdam Amsterdam, Netherlands
| | - Ronald P J Oude-Elferink
- Tytgat Institute for Liver and Intestinal Research, Academic Medical Center, University of Amsterdam Amsterdam, Netherlands
| |
Collapse
|
120
|
The oxygen paradox of neurovascular coupling. J Cereb Blood Flow Metab 2014; 34:19-29. [PMID: 24149931 PMCID: PMC3887356 DOI: 10.1038/jcbfm.2013.181] [Citation(s) in RCA: 91] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Revised: 09/12/2013] [Accepted: 09/22/2013] [Indexed: 01/09/2023]
Abstract
The coupling of cerebral blood flow (CBF) to neuronal activity is well preserved during evolution. Upon changes in the neuronal activity, an incompletely understood coupling mechanism regulates diameter changes of supplying blood vessels, which adjust CBF within seconds. The physiologic brain tissue oxygen content would sustain unimpeded brain function for only 1 second if continuous oxygen supply would suddenly stop. This suggests that the CBF response has evolved to balance oxygen supply and demand. Surprisingly, CBF increases surpass the accompanying increases of cerebral metabolic rate of oxygen (CMRO2). However, a disproportionate CBF increase may be required to increase the concentration gradient from capillary to tissue that drives oxygen delivery. However, the brain tissue oxygen content is not zero, and tissue pO2 decreases could serve to increase oxygen delivery without a CBF increase. Experimental evidence suggests that CMRO2 can increase with constant CBF within limits and decreases of baseline CBF were observed with constant CMRO2. This conflicting evidence may be viewed as an oxygen paradox of neurovascular coupling. As a possible solution for this paradox, we hypothesize that the CBF response has evolved to safeguard brain function in situations of moderate pathophysiological interference with oxygen supply.
Collapse
|
121
|
Rahman N, Buck J, Levin LR. pH sensing via bicarbonate-regulated "soluble" adenylyl cyclase (sAC). Front Physiol 2013; 4:343. [PMID: 24324443 PMCID: PMC3838963 DOI: 10.3389/fphys.2013.00343] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Accepted: 11/06/2013] [Indexed: 01/03/2023] Open
Abstract
Soluble adenylyl cyclase (sAC) is a source of the second messenger cyclic adenosine 3′, 5′ monophosphate (cAMP). sAC is directly regulated by bicarbonate (HCO−3) ions. In living cells, HCO−3 ions are in nearly instantaneous equilibrium with carbon dioxide (CO2) and pH due to the ubiquitous presence of carbonic anhydrases. Numerous biological processes are regulated by CO2, HCO−3, and/or pH, and in a number of these, sAC has been shown to function as a physiological CO2/HCO3/pH sensor. In this review, we detail the known pH sensing functions of sAC, and we discuss two highly-studied, pH-dependent pathways in which sAC might play a role.
Collapse
Affiliation(s)
- Nawreen Rahman
- Department of Pharmacology, Weill Cornell Medical College New York, NY, USA
| | | | | |
Collapse
|
122
|
Oxidative stress induced mitochondrial protein kinase A mediates cytochrome c oxidase dysfunction. PLoS One 2013; 8:e77129. [PMID: 24130844 PMCID: PMC3795003 DOI: 10.1371/journal.pone.0077129] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2013] [Accepted: 08/29/2013] [Indexed: 11/30/2022] Open
Abstract
Previously we showed that Protein kinase A (PKA) activated in hypoxia and myocardial ischemia/reperfusion mediates phosphorylation of subunits I, IVi1 and Vb of cytochrome c oxidase. However, the mechanism of activation of the kinase under hypoxia remains unclear. It is also unclear if hypoxic stress activated PKA is different from the cAMP dependent mitochondrial PKA activity reported under normal physiological conditions. In this study using RAW 264.7 macrophages and in vitro perfused mouse heart system we investigated the nature of PKA activated under hypoxia. Limited protease treatment and digitonin fractionation of intact mitochondria suggests that higher mitochondrial PKA activity under hypoxia is mainly due to increased sequestration of PKA Catalytic α (PKAα) subunit in the mitochondrial matrix compartment. The increase in PKA activity is independent of mitochondrial cAMP and is not inhibited by adenylate cyclase inhibitor, KH7. Instead, activation of hypoxia-induced PKA is dependent on reactive oxygen species (ROS). H89, an inhibitor of PKA activity and the antioxidant Mito-CP prevented loss of CcO activity in macrophages under hypoxia and in mouse heart under ischemia/reperfusion injury. Substitution of wild type subunit Vb of CcO with phosphorylation resistant S40A mutant subunit attenuated the loss of CcO activity and reduced ROS production. These results provide a compelling evidence for hypoxia induced phosphorylation as a signal for CcO dysfunction. The results also describe a novel mechanism of mitochondrial PKA activation which is independent of mitochondrial cAMP, but responsive to ROS.
Collapse
|
123
|
Zippin JH, Chen Y, Straub SG, Hess KC, Diaz A, Lee D, Tso P, Holz GG, Sharp GWG, Levin LR, Buck J. CO2/HCO3(-)- and calcium-regulated soluble adenylyl cyclase as a physiological ATP sensor. J Biol Chem 2013; 288:33283-91. [PMID: 24100033 DOI: 10.1074/jbc.m113.510073] [Citation(s) in RCA: 95] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The second messenger molecule cAMP is integral for many physiological processes. In mammalian cells, cAMP can be generated from hormone- and G protein-regulated transmembrane adenylyl cyclases or via the widely expressed and structurally and biochemically distinct enzyme soluble adenylyl cyclase (sAC). sAC activity is uniquely stimulated by bicarbonate ions, and in cells, sAC functions as a physiological carbon dioxide, bicarbonate, and pH sensor. sAC activity is also stimulated by calcium, and its affinity for its substrate ATP suggests that it may be sensitive to physiologically relevant fluctuations in intracellular ATP. We demonstrate here that sAC can function as a cellular ATP sensor. In cells, sAC-generated cAMP reflects alterations in intracellular ATP that do not affect transmembrane AC-generated cAMP. In β cells of the pancreas, glucose metabolism generates ATP, which corresponds to an increase in cAMP, and we show here that sAC is responsible for an ATP-dependent cAMP increase. Glucose metabolism also elicits insulin secretion, and we further show that sAC is necessary for normal glucose-stimulated insulin secretion in vitro and in vivo.
Collapse
|
124
|
Zou L, Wang M, Shen Y, Liao J, Li A, Wang M. PKIS: computational identification of protein kinases for experimentally discovered protein phosphorylation sites. BMC Bioinformatics 2013; 14:247. [PMID: 23941207 PMCID: PMC3765618 DOI: 10.1186/1471-2105-14-247] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Accepted: 08/06/2013] [Indexed: 02/03/2023] Open
Abstract
Background Dynamic protein phosphorylation is an essential regulatory mechanism in various organisms. In this capacity, it is involved in a multitude of signal transduction pathways. Kinase-specific phosphorylation data lay the foundation for reconstruction of signal transduction networks. For this reason, precise annotation of phosphorylated proteins is the first step toward simulating cell signaling pathways. However, the vast majority of kinase-specific phosphorylation data remain undiscovered and existing experimental methods and computational phosphorylation site (P-site) prediction tools have various limitations with respect to addressing this problem. Results To address this issue, a novel protein kinase identification web server, PKIS, is here presented for the identification of the protein kinases responsible for experimentally verified P-sites at high specificity, which incorporates the composition of monomer spectrum (CMS) encoding strategy and support vector machines (SVMs). Compared to widely used P-site prediction tools including KinasePhos 2.0, Musite, and GPS2.1, PKIS largely outperformed these tools in identifying protein kinases associated with known P-sites. In addition, PKIS was used on all the P-sites in Phospho.ELM that currently lack kinase information. It successfully identified 14 potential SYK substrates with 36 known P-sites. Further literature search showed that 5 of them were indeed phosphorylated by SYK. Finally, an enrichment analysis was performed and 6 significant SYK-related signal pathways were identified. Conclusions In general, PKIS can identify protein kinases for experimental phosphorylation sites efficiently. It is a valuable bioinformatics tool suitable for the study of protein phosphorylation. The PKIS web server is freely available at http://bioinformatics.ustc.edu.cn/pkis.
Collapse
Affiliation(s)
- Liang Zou
- Department of Electronic Science and Technology, University of Science and Technology of China, Hefei 230027, China.
| | | | | | | | | | | |
Collapse
|
125
|
Lefkimmiatis K, Leronni D, Hofer AM. The inner and outer compartments of mitochondria are sites of distinct cAMP/PKA signaling dynamics. ACTA ACUST UNITED AC 2013; 202:453-62. [PMID: 23897891 PMCID: PMC3734087 DOI: 10.1083/jcb.201303159] [Citation(s) in RCA: 119] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
FRET-based sensors for cAMP and PKA activity reveal that mitochondrial subcompartments host segregated cAMP cascades with distinct functional and kinetic signatures. Cyclic AMP (cAMP)-dependent phosphorylation has been reported to exert biological effects in both the mitochondrial matrix and outer mitochondrial membrane (OMM). However, the kinetics, targets, and effectors of the cAMP cascade in these organellar domains remain largely undefined. Here we used sensitive FRET-based sensors to monitor cAMP and protein kinase A (PKA) activity in different mitochondrial compartments in real time. We found that cytosolic cAMP did not enter the matrix, except during mitochondrial permeability transition. Bicarbonate treatment (expected to activate matrix-bound soluble adenylyl cyclase) increased intramitochondrial cAMP, but along with membrane-permeant cAMP analogues, failed to induce measureable matrix PKA activity. In contrast, the OMM proved to be a domain of exceptionally persistent cAMP-dependent PKA activity. Although cAMP signaling events measured on the OMM mirrored those of the cytosol, PKA phosphorylation at the OMM endured longer as a consequence of diminished control by local phosphatases. Our findings demonstrate that mitochondria host segregated cAMP cascades with distinct functional and kinetic signatures.
Collapse
Affiliation(s)
- Konstantinos Lefkimmiatis
- VA Boston Healthcare System and 2 Department of Surgery, Brigham and Women's Hospital, Harvard Medical School, West Roxbury, MA 02132, USA.
| | | | | |
Collapse
|
126
|
Di Benedetto G, Scalzotto E, Mongillo M, Pozzan T. Mitochondrial Ca²⁺ uptake induces cyclic AMP generation in the matrix and modulates organelle ATP levels. Cell Metab 2013; 17:965-975. [PMID: 23747252 DOI: 10.1016/j.cmet.2013.05.003] [Citation(s) in RCA: 152] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Revised: 03/08/2013] [Accepted: 04/08/2013] [Indexed: 01/09/2023]
Abstract
While the role of mitochondrial Ca²⁺ homeostasis in cell pathophysiology is widely accepted, the possibility that cAMP regulates mitochondrial functions has only recently received experimental support. The site of cAMP production, its targets, and its functions in the organelles remain uncertain. Using a variety of genetic/pharmacological tools, we here demonstrate that the mitochondrial inner membrane is impermeable to cytosolic cAMP, while an autonomous cAMP signaling toolkit is expressed in the matrix. We demonstrate that rises in matrix Ca²⁺ powerfully stimulate cAMP increases within mitochondria and that matrix cAMP levels regulate their ATP synthesizing efficiency. In cardiomyocyte cultures, mitochondrial cAMP can be increased by treatments that augment the frequency and amplitude of Ca²⁺ oscillations within the cytosol and organelles, revealing that mitochondria can integrate an oscillatory Ca²⁺ signal to increase cAMP in their matrix. The present data reveal the existence, within mitochondria, of a hitherto unknown crosstalk between Ca²⁺ and cAMP.
Collapse
Affiliation(s)
- Giulietta Di Benedetto
- Institute of Neuroscience, Italian National Research Council (CNR), Viale G. Colombo 3, 35121 Padova, Italy; Venetian Institute of Molecular Medicine (VIMM), Via Orus 2, 35129 Padova, Italy.
| | - Elisa Scalzotto
- Venetian Institute of Molecular Medicine (VIMM), Via Orus 2, 35129 Padova, Italy
| | - Marco Mongillo
- Institute of Neuroscience, Italian National Research Council (CNR), Viale G. Colombo 3, 35121 Padova, Italy; Venetian Institute of Molecular Medicine (VIMM), Via Orus 2, 35129 Padova, Italy; Department of Biomedical Sciences, University of Padova, Viale G. Colombo 3, 35121 Padova, Italy
| | - Tullio Pozzan
- Institute of Neuroscience, Italian National Research Council (CNR), Viale G. Colombo 3, 35121 Padova, Italy; Venetian Institute of Molecular Medicine (VIMM), Via Orus 2, 35129 Padova, Italy; Department of Biomedical Sciences, University of Padova, Viale G. Colombo 3, 35121 Padova, Italy
| |
Collapse
|
127
|
Abstract
Phosphorylation of mitochondrial proteins has emerged as a major regulatory mechanism for metabolic adaptation. cAMP signaling and PKA phosphorylation of mitochondrial proteins have just started to be investigated, and the presence of cAMP-generating enzymes and PKA inside mitochondria is still controversial. Here, we discuss the role of cAMP in regulating mitochondrial bioenergetics through protein phosphorylation and the evidence for soluble adenylyl cyclase as the source of cAMP inside mitochondria.
Collapse
Affiliation(s)
- Federica Valsecchi
- Department of Neurology and Neuroscience, Weill Medical College of Cornell University, New York, USA
| | | | | | | | | |
Collapse
|
128
|
Raval AP, Borges-Garcia R, Javier Moreno W, Perez-Pinzon MA, Bramlett H. Periodic 17β-estradiol pretreatment protects rat brain from cerebral ischemic damage via estrogen receptor-β. PLoS One 2013; 8:e60716. [PMID: 23593292 PMCID: PMC3625208 DOI: 10.1371/journal.pone.0060716] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2012] [Accepted: 03/01/2013] [Indexed: 12/17/2022] Open
Abstract
Although chronic 17β-estradiol (E2) has been shown to be a cognition-preserving and neuroprotective agent in animal brain injury models, concern regarding its safety was raised by the failed translation of this phenomenon to the clinic. Previously, we demonstrated that a single bolus of E2 48 hr prior to ischemia protected the hippocampus from damage in ovariectomized rats via phosphorylation of cyclic-AMP response element binding protein, which requires activation of estrogen receptor subtype beta (ER-β). The current study tests the hypothesis that long-term periodic E2-treatment improves cognition and reduces post-ischemic hippocampal injury by means of ER-β activation. Ovariectomized rats were given ten injections of E2 at 48 hr intervals for 21 days. Hippocampal-dependent learning, memory and ischemic neuronal loss were monitored. Results demonstrated that periodic E2 treatments improved spatial learning, memory and ischemic neuronal survival in ovariectomized rats. Additionally, periodic ER-β agonist treatments every 48 hr improved post-ischemic cognition. Silencing of hippocampal ER-β attenuated E2-mediated ischemic protection suggesting that ER-β plays a key role in mediating the beneficial effects of periodic E2 treatments. This study emphasizes the need to investigate a periodic estrogen replacement regimen to reduce cognitive decline and cerebral ischemia incidents/impact in post-menopausal women.
Collapse
Affiliation(s)
- Ami P Raval
- Cerebral Vascular Disease Research Laboratories, Department of Neurology, University of Miami, Miami, Florida, USA.
| | | | | | | | | |
Collapse
|
129
|
Raval AP, Borges-Garcia R, Diaz F, Sick TJ, Bramlett H. Oral contraceptives and nicotine synergistically exacerbate cerebral ischemic injury in the female brain. Transl Stroke Res 2013; 4:402-12. [PMID: 24323338 DOI: 10.1007/s12975-013-0253-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2012] [Revised: 01/24/2013] [Accepted: 01/28/2013] [Indexed: 02/06/2023]
Abstract
Oral contraceptives (OC) and smoking-derived nicotine (N) are known to synergistically increase the risk and severity of cerebral ischemia in women. Although it has been known for some time that long-term use of OC and nicotine will have an increased risk of peripheral thrombus formation, little is known about how the combination of OC and nicotine increases severity of brain ischemia. Recent laboratory studies simulating the conditions of nicotine exposure produced by cigarette smoking and OC regimen of women in female rats confirms that the severity of ischemic hippocampal damage is far greater in female rats simultaneously exposed to OC than to nicotine alone. These studies also demonstrated that the concurrent exposure of OC and nicotine reduces endogenous 17β-estradiol levels and inhibits estrogen signaling in the brain of female rats. The endogenous 17β-estradiol plays a key role in cerebrovascular protection in women during their pre-menopausal life and loss of circulating estrogen at reproductive senescence increases both the incidence and severity of cerebrovascular diseases. Therefore, OC and nicotine induced severe post-ischemic damage might be a consequence of lack of estrogen signaling in the brain. In the present review we highlight possible mechanisms by which OC and nicotine inhibits estrogen signaling that could be responsible for severe ischemic damage in females.
Collapse
Affiliation(s)
- Ami P Raval
- Cerebral Vascular Disease Research Center, Department of Neurology, Leonard M. Miller School of Medicine, University of Miami, Two Story Lab (TSL), Room # 230A, 1420 NW 9th Avenue, Miami, FL, 33101, USA,
| | | | | | | | | |
Collapse
|
130
|
Picard M, Shirihai OS, Gentil BJ, Burelle Y. Mitochondrial morphology transitions and functions: implications for retrograde signaling? Am J Physiol Regul Integr Comp Physiol 2013; 304:R393-406. [PMID: 23364527 DOI: 10.1152/ajpregu.00584.2012] [Citation(s) in RCA: 219] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
In response to cellular and environmental stresses, mitochondria undergo morphology transitions regulated by dynamic processes of membrane fusion and fission. These events of mitochondrial dynamics are central regulators of cellular activity, but the mechanisms linking mitochondrial shape to cell function remain unclear. One possibility evaluated in this review is that mitochondrial morphological transitions (from elongated to fragmented, and vice-versa) directly modify canonical aspects of the organelle's function, including susceptibility to mitochondrial permeability transition, respiratory properties of the electron transport chain, and reactive oxygen species production. Because outputs derived from mitochondrial metabolism are linked to defined cellular signaling pathways, fusion/fission morphology transitions could regulate mitochondrial function and retrograde signaling. This is hypothesized to provide a dynamic interface between the cell, its genome, and the fluctuating metabolic environment.
Collapse
Affiliation(s)
- Martin Picard
- Center for Mitochondrial and Epigenomic Medicine, Children’s Hospital of Philadelphia, University of Pennsylvania, Philadelphia, PA, USA
| | | | | | | |
Collapse
|
131
|
Balaban RS. Perspectives on: SGP symposium on mitochondrial physiology and medicine: metabolic homeostasis of the heart. ACTA ACUST UNITED AC 2013; 139:407-14. [PMID: 22641635 PMCID: PMC3362523 DOI: 10.1085/jgp.201210783] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Robert S Balaban
- Laboratory of Cardiac Energetics, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20817, USA.
| |
Collapse
|
132
|
Lu B, Lee J, Nie X, Li M, Morozov YI, Venkatesh S, Bogenhagen DF, Temiakov D, Suzuki CK. Phosphorylation of human TFAM in mitochondria impairs DNA binding and promotes degradation by the AAA+ Lon protease. Mol Cell 2012. [PMID: 23201127 DOI: 10.1016/j.molcel.2012.10.023] [Citation(s) in RCA: 232] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Human mitochondrial transcription factor A (TFAM) is a high-mobility group (HMG) protein at the nexus of mitochondrial DNA (mtDNA) replication, transcription, and inheritance. Little is known about the mechanisms underlying its posttranslational regulation. Here, we demonstrate that TFAM is phosphorylated within its HMG box 1 (HMG1) by cAMP-dependent protein kinase in mitochondria. HMG1 phosphorylation impairs the ability of TFAM to bind DNA and to activate transcription. We show that only DNA-free TFAM is degraded by the Lon protease, which is inhibited by the anticancer drug bortezomib. In cells with normal mtDNA levels, HMG1-phosphorylated TFAM is degraded by Lon. However, in cells with severe mtDNA deficits, nonphosphorylated TFAM is also degraded, as it is DNA free. Depleting Lon in these cells increases levels of TFAM and upregulates mtDNA content, albeit transiently. Phosphorylation and proteolysis thus provide mechanisms for rapid fine-tuning of TFAM function and abundance in mitochondria, which are crucial for maintaining and expressing mtDNA.
Collapse
Affiliation(s)
- Bin Lu
- Department of Biochemistry and Molecular Biology, New Jersey Medical School, University of Medicine and Dentistry of New Jersey, Newark, NJ 07103, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
133
|
Helling S, Hüttemann M, Ramzan R, Kim SH, Lee I, Müller T, Langenfeld E, Meyer HE, Kadenbach B, Vogt S, Marcus K. Multiple phosphorylations of cytochrome c oxidase and their functions. Proteomics 2012; 12:950-9. [PMID: 22522801 DOI: 10.1002/pmic.201100618] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Cytochrome c oxidase (COX), the terminal enzyme of the mitochondrial electron transport chain, is regulated by isozyme expression, allosteric effectors such as the ATP/ADP ratio, and reversible phosphorylation. Of particular interest is the "allosteric ATP-inhibition," which has been hypothesized to keep the mitochondrial membrane potential at low healthy values (<140 mV), thus preventing the formation of superoxide radical anions, which have been implicated in multiple degenerative diseases. It has been proposed that the "allosteric ATP-inhibition" is switched on by the protein kinase A-dependent phosphorylation of COX. The goal of this study was to identify the phosphorylation site(s) involved in the "allosteric ATP-inhibition" of COX. We report the mass spectrometric identification of four new phosphorylation sites in bovine heart COX. The identified phosphorylation sites include Tyr-218 in subunit II, Ser-1 in subunit Va, Ser-2 in subunit Vb, and Ser-1 in subunit VIIc. With the exception of Ser-2 in subunit Vb, the identified phosphorylation sites were found in enzyme samples with and without "allosteric ATP inhibition," making Ser-2 of subunit Vb a candidate site enabling allosteric regulation. We therefore hypothesize that additional phosphorylation(s) may be required for the "allosteric ATP-inhibition," and that these sites may be easily dephosphorylated or difficult to identify by mass spectrometry.
Collapse
Affiliation(s)
- Stefan Helling
- Medizinisches Proteom-Center, Funktionelle Proteomik, Ruhr-Universität Bochum, Bochum, Germany
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
134
|
Lam MPY, Lau E, Scruggs SB, Wang D, Kim TY, Liem DA, Zhang J, Ryan CM, Faull KF, Ping P. Site-specific quantitative analysis of cardiac mitochondrial protein phosphorylation. J Proteomics 2012; 81:15-23. [PMID: 23022582 DOI: 10.1016/j.jprot.2012.09.015] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2012] [Revised: 09/05/2012] [Accepted: 09/12/2012] [Indexed: 12/19/2022]
Abstract
We report the development of a multiple-reaction monitoring (MRM) strategy specifically tailored to the detection and quantification of mitochondrial protein phosphorylation. We recently derived 68 MRM transitions specific to protein modifications in the respiratory chain, voltage-dependent anion channel, and adenine nucleotide translocase. Here, we have now expanded the total number of MRM transitions to 176 to cover proteins from the tricarboxylic acid cycle, pyruvate dehydrogenase complex, and branched-chain alpha-keto acid dehydrogenase complex. We utilized the transition set to analyze endogenous protein phosphorylation in human heart, mouse heart, and mouse liver. The data demonstrate the potential utility of the MRM workflow for studying the functional details of mitochondrial phosphorylation signaling. This article is part of a Special Issue entitled: From protein structures to clinical applications.
Collapse
Affiliation(s)
- Maggie P Y Lam
- Department of Physiology, Division of Cardiology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
135
|
Srinivasan S, Avadhani NG. Cytochrome c oxidase dysfunction in oxidative stress. Free Radic Biol Med 2012; 53:1252-63. [PMID: 22841758 PMCID: PMC3436951 DOI: 10.1016/j.freeradbiomed.2012.07.021] [Citation(s) in RCA: 237] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/24/2012] [Revised: 07/14/2012] [Accepted: 07/17/2012] [Indexed: 12/22/2022]
Abstract
Cytochrome c oxidase (CcO) is the terminal oxidase of the mitochondrial electron transport chain. This bigenomic enzyme in mammals contains 13 subunits of which the 3 catalytic subunits are encoded by the mitochondrial genes. The remaining 10 subunits with suspected roles in the regulation, and/or assembly, are coded by the nuclear genome. The enzyme contains two heme groups (heme a and a3) and two Cu(2+) centers (Cu(2+) A and Cu(2+) B) as catalytic centers and handles more than 90% of molecular O(2) respired by the mammalian cells and tissues. CcO is a highly regulated enzyme which is believed to be the pacesetter for mitochondrial oxidative metabolism and ATP synthesis. The structure and function of the enzyme are affected in a wide variety of diseases including cancer, neurodegenerative diseases, myocardial ischemia/reperfusion, bone and skeletal diseases, and diabetes. Despite handling a high O(2) load the role of CcO in the production of reactive oxygen species still remains a subject of debate. However, a volume of evidence suggests that CcO dysfunction is invariably associated with increased mitochondrial reactive oxygen species production and cellular toxicity. In this paper we review the literature on mechanisms of multimodal regulation of CcO activity by a wide spectrum of physiological and pathological factors. We also review an array of literature on the direct or indirect roles of CcO in reactive oxygen species production.
Collapse
Affiliation(s)
- Satish Srinivasan
- Department of Animal Biology, School of Veterinary Medicine, University of Pennsylvania, 3800 Spruce Street, Philadelphia, PA 19104
| | - Narayan G. Avadhani
- Department of Animal Biology, School of Veterinary Medicine, University of Pennsylvania, 3800 Spruce Street, Philadelphia, PA 19104
| |
Collapse
|
136
|
Covian R, Balaban RS. Cardiac mitochondrial matrix and respiratory complex protein phosphorylation. Am J Physiol Heart Circ Physiol 2012; 303:H940-66. [PMID: 22886415 DOI: 10.1152/ajpheart.00077.2012] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
It has become appreciated over the last several years that protein phosphorylation within the cardiac mitochondrial matrix and respiratory complexes is extensive. Given the importance of oxidative phosphorylation and the balance of energy metabolism in the heart, the potential regulatory effect of these classical signaling events on mitochondrial function is of interest. However, the functional impact of protein phosphorylation and the kinase/phosphatase system responsible for it are relatively unknown. Exceptions include the well-characterized pyruvate dehydrogenase and branched chain α-ketoacid dehydrogenase regulatory system. The first task of this review is to update the current status of protein phosphorylation detection primarily in the matrix and evaluate evidence linking these events with enzymatic function or protein processing. To manage the scope of this effort, we have focused on the pathways involved in energy metabolism. The high sensitivity of modern methods of detecting protein phosphorylation and the low specificity of many kinases suggests that detection of protein phosphorylation sites without information on the mole fraction of phosphorylation is difficult to interpret, especially in metabolic enzymes, and is likely irrelevant to function. However, several systems including protein translocation, adenine nucleotide translocase, cytochrome c, and complex IV protein phosphorylation have been well correlated with enzymatic function along with the classical dehydrogenase systems. The second task is to review the current understanding of the kinase/phosphatase system within the matrix. Though it is clear that protein phosphorylation occurs within the matrix, based on (32)P incorporation and quantitative mass spectrometry measures, the kinase/phosphatase system responsible for this process is ill-defined. An argument is presented that remnants of the much more labile bacterial protein phosphoryl transfer system may be present in the matrix and that the evaluation of this possibility will require the application of approaches developed for bacterial cell signaling to the mitochondria.
Collapse
Affiliation(s)
- Raul Covian
- Laboratory of Cardiac Energetics, National Heart Lung and Blood Institute, Bethesda, Maryland 20817, USA
| | | |
Collapse
|
137
|
Hüttemann M, Lee I, Gao X, Pecina P, Pecinova A, Liu J, Aras S, Sommer N, Sanderson TH, Tost M, Neff F, Aguilar-Pimentel JA, Becker L, Naton B, Rathkolb B, Rozman J, Favor J, Hans W, Prehn C, Puk O, Schrewe A, Sun M, Höfler H, Adamski J, Bekeredjian R, Graw J, Adler T, Busch DH, Klingenspor M, Klopstock T, Ollert M, Wolf E, Fuchs H, Gailus-Durner V, Hrabě de Angelis M, Weissmann N, Doan JW, Bassett DJP, Grossman LI. Cytochrome c oxidase subunit 4 isoform 2-knockout mice show reduced enzyme activity, airway hyporeactivity, and lung pathology. FASEB J 2012; 26:3916-30. [PMID: 22730437 DOI: 10.1096/fj.11-203273] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Cytochrome c oxidase (COX) is the terminal enzyme of the mitochondrial electron transport chain. The purpose of this study was to analyze the function of lung-specific cytochrome c oxidase subunit 4 isoform 2 (COX4i2) in vitro and in COX4i2-knockout mice in vivo. COX was isolated from cow lung and liver as control and functionally analyzed. COX4i2-knockout mice were generated and the effect of the gene knockout was determined, including COX activity, tissue energy levels, noninvasive and invasive lung function, and lung pathology. These studies were complemented by a comprehensive functional screen performed at the German Mouse Clinic (Neuherberg, Germany). We show that isolated cow lung COX containing COX4i2 is about twice as active (88 and 102% increased activity in the presence of allosteric activator ADP and inhibitor ATP, respectively) as liver COX, which lacks COX4i2. In COX4i2-knockout mice, lung COX activity and cellular ATP levels were significantly reduced (-50 and -29%, respectively). Knockout mice showed decreased airway responsiveness (60% reduced P(enh) and 58% reduced airway resistance upon challenge with 25 and 100 mg methacholine, respectively), and they developed a lung pathology deteriorating with age that included the appearance of Charcot-Leyden crystals. In addition, there was an interesting sex-specific phenotype, in which the knockout females showed reduced lean mass (-12%), reduced total oxygen consumption rate (-8%), improved glucose tolerance, and reduced grip force (-14%) compared to wild-type females. Our data suggest that high activity lung COX is a central determinant of airway function and is required for maximal airway responsiveness and healthy lung function. Since airway constriction requires energy, we propose a model in which reduced tissue ATP levels explain protection from airway hyperresponsiveness, i.e., absence of COX4i2 leads to reduced lung COX activity and ATP levels, which results in impaired airway constriction and thus reduced airway responsiveness; long-term lung pathology develops in the knockout mice due to impairment of energy-costly lung maintenance processes; and therefore, we propose mitochondrial oxidative phosphorylation as a novel target for the treatment of respiratory diseases, such as asthma.
Collapse
Affiliation(s)
- Maik Hüttemann
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI 48201, USA.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
138
|
Ramírez-Torres A, Barceló-Batllori S, Fernández-Vizarra E, Navarro MA, Arnal C, Guillén N, Acín S, Osada J. Proteomics and gene expression analyses of mitochondria from squalene-treated apoE-deficient mice identify short-chain specific acyl-CoA dehydrogenase changes associated with fatty liver amelioration. J Proteomics 2012; 75:2563-75. [DOI: 10.1016/j.jprot.2012.02.025] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2012] [Revised: 02/06/2012] [Accepted: 02/20/2012] [Indexed: 02/07/2023]
|
139
|
Abstract
Since 1929, when it was discovered that ATP is a substrate for muscle contraction, the knowledge about this purine nucleotide has been greatly expanded. Many aspects of cell metabolism revolve around ATP production and consumption. It is important to understand the concepts of glucose and oxygen consumption in aerobic and anaerobic life and to link bioenergetics with the vast amount of reactions occurring within cells. ATP is universally seen as the energy exchange factor that connects anabolism and catabolism but also fuels processes such as motile contraction, phosphorylations, and active transport. It is also a signalling molecule in the purinergic signalling mechanisms. In this review, we will discuss all the main mechanisms of ATP production linked to ADP phosphorylation as well the regulation of these mechanisms during stress conditions and in connection with calcium signalling events. Recent advances regarding ATP storage and its special significance for purinergic signalling will also be reviewed.
Collapse
|
140
|
Abstract
Calcium is an important signaling molecule involved in the regulation of many cellular functions. The large free energy in the Ca(2+) ion membrane gradients makes Ca(2+) signaling inherently sensitive to the available cellular free energy, primarily in the form of ATP. In addition, Ca(2+) regulates many cellular ATP-consuming reactions such as muscle contraction, exocytosis, biosynthesis, and neuronal signaling. Thus, Ca(2+) becomes a logical candidate as a signaling molecule for modulating ATP hydrolysis and synthesis during changes in numerous forms of cellular work. Mitochondria are the primary source of aerobic energy production in mammalian cells and also maintain a large Ca(2+) gradient across their inner membrane, providing a signaling potential for this molecule. The demonstrated link between cytosolic and mitochondrial Ca(2+) concentrations, identification of transport mechanisms, and the proximity of mitochondria to Ca(2+) release sites further supports the notion that Ca(2+) can be an important signaling molecule in the energy metabolism interplay of the cytosol with the mitochondria. Here we review sites within the mitochondria where Ca(2+) plays a role in the regulation of ATP generation and potentially contributes to the orchestration of cellular metabolic homeostasis. Early work on isolated enzymes pointed to several matrix dehydrogenases that are stimulated by Ca(2+), which were confirmed in the intact mitochondrion as well as cellular and in vivo systems. However, studies in these intact systems suggested a more expansive influence of Ca(2+) on mitochondrial energy conversion. Numerous noninvasive approaches monitoring NADH, mitochondrial membrane potential, oxygen consumption, and workloads suggest significant effects of Ca(2+) on other elements of NADH generation as well as downstream elements of oxidative phosphorylation, including the F(1)F(O)-ATPase and the cytochrome chain. These other potential elements of Ca(2+) modification of mitochondrial energy conversion will be the focus of this review. Though most specific molecular mechanisms have yet to be elucidated, it is clear that Ca(2+) provides a balanced activation of mitochondrial energy metabolism that exceeds the alteration of dehydrogenases alone.
Collapse
Affiliation(s)
- Brian Glancy
- Laboratory of Cardiac Energetics, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland 20817, USA
| | | |
Collapse
|
141
|
Ball KA, Nelson AW, Foster DG, Poyton RO. Nitric oxide produced by cytochrome c oxidase helps stabilize HIF-1α in hypoxic mammalian cells. Biochem Biophys Res Commun 2012; 420:727-32. [PMID: 22450315 DOI: 10.1016/j.bbrc.2012.03.050] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2012] [Accepted: 03/10/2012] [Indexed: 01/29/2023]
Abstract
The mitochondrial respiratory chain has been reported to play a role in the stabilization of HIF-1α when mammalian cells experience hypoxia, most likely through the generation of free radicals. Although previous studies have suggested the involvement of superoxide catalyzed by complex III more recent studies raise the possibility that nitric oxide (NO) catalyzed by cytochrome c oxidase (Cco/NO), which functions in hypoxic signaling in yeast, may also be involved. Herein, we have found that HEK293 cells, which do not express a NOS isoform, possess Cco/NO activity and that this activity is responsible for an increase in intracellular NO levels when these cells are exposed to hypoxia. By using PTIO, a NO scavenger, we have also found that the increased NO levels in hypoxic HEK293 cells help stabilize HIF-1α. These findings suggest a new mechanism for mitochondrial involvement in hypoxic signaling in mammalian cells.
Collapse
Affiliation(s)
- Kerri A Ball
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309-0347, USA
| | | | | | | |
Collapse
|
142
|
Phillips D, Covian R, Aponte AM, Glancy B, Taylor JF, Chess D, Balaban RS. Regulation of oxidative phosphorylation complex activity: effects of tissue-specific metabolic stress within an allometric series and acute changes in workload. Am J Physiol Regul Integr Comp Physiol 2012; 302:R1034-48. [PMID: 22378775 DOI: 10.1152/ajpregu.00596.2011] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The concentration of mitochondrial oxidative phosphorylation complexes (MOPCs) is tuned to the maximum energy conversion requirements of a given tissue; however, whether the activity of MOPCs is altered in response to acute changes in energy conversion demand is unclear. We hypothesized that MOPCs activity is modulated by tissue metabolic stress to maintain the energy-metabolism homeostasis. Metabolic stress was defined as the observed energy conversion rate/maximum energy conversion rate. The maximum energy conversion rate was assumed to be proportional to the concentration of MOPCs, as determined with optical spectroscopy, gel electrophoresis, and mass spectrometry. The resting metabolic stress of the heart and liver across the range of resting metabolic rates within an allometric series (mouse, rabbit, and pig) was determined from MPOCs content and literature respiratory values. The metabolic stress of the liver was high and nearly constant across the allometric series due to the proportional increase in MOPCs content with resting metabolic rate. In contrast, the MOPCs content of the heart was essentially constant in the allometric series, resulting in an increasing metabolic stress with decreasing animal size. The MOPCs activity was determined in native gels, with an emphasis on Complex V. Extracted MOPCs enzyme activity was proportional to resting metabolic stress across tissues and species. Complex V activity was also shown to be acutely modulated by changes in metabolic stress in the heart, in vivo and in vitro. The modulation of extracted MOPCs activity suggests that persistent posttranslational modifications (PTMs) alter MOPCs activity both chronically and acutely, specifically in the heart. Protein phosphorylation of Complex V was correlated with activity inhibition under several conditions, suggesting that protein phosphorylation may contribute to activity modulation with energy metabolic stress. These data are consistent with the notion that metabolic stress modulates MOPCs activity in the heart.
Collapse
Affiliation(s)
- Darci Phillips
- Laboratory of Cardiac Energetics, NHLBI, NIH, Bethesda, MD 20892-1061, USA
| | | | | | | | | | | | | |
Collapse
|
143
|
Gratia S, Kay L, Michelland S, Sève M, Schlattner U, Tokarska-Schlattner M. Cardiac phosphoproteome reveals cell signaling events involved in doxorubicin cardiotoxicity. J Proteomics 2012; 75:4705-16. [PMID: 22348821 DOI: 10.1016/j.jprot.2012.02.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2011] [Revised: 02/02/2012] [Accepted: 02/03/2012] [Indexed: 10/14/2022]
Abstract
The successful use of anthracyclines like doxorubicin in chemotherapy is limited by their severe cardiotoxicity. Despite decades of clinical application, a satisfying description of the molecular mechanisms involved and a preventive treatment have not yet been achieved. Here we address doxorubicin-induced changes in cell signaling as a novel potential mediator of doxorubicin toxicity by applying a non-biased screen of the cardiac phosphoproteome. Two-dimensional gel electrophoresis, phosphospecific staining, quantitative image analysis, and MALDI-TOF/TOF mass spectrometry were combined to identify (de)phosphorylation events occurring in the isolated rat heart upon Langendorff-perfusion with clinically relevant (5 μM) and supraclinical concentrations (25 μM) of doxorubicin. This approach identified 22 proteins with a significantly changed phosphorylation status and these results were validated by immunoblotting for selected phosphosites. Overrepresentation of mitochondrial proteins (>40%) identified this compartment as a prime target of doxorubicin. Identified proteins were mainly involved in energy metabolism (e.g. pyruvate dehydrogenase and acyl-CoA dehydrogenase), sarcomere structure and function (e.g. desmin) or chaperone-like activities (e.g. α-crystallin B chain and prohibitin). Changes in phosphorylation of pyruvate dehydrogenase, regulating pyruvate entry into the Krebs cycle, and desmin, maintaining myofibrillar array, are relevant for main symptoms of cardiac dysfunction related to doxorubicin treatment, namely energy imbalance and myofibrillar disorganization. This article is part of a Special Issue entitled: Translational Proteomics.
Collapse
Affiliation(s)
- Séverine Gratia
- University Joseph Fourier, Laboratory of Fundamental and Applied Bioenergetics, Environmental and Systems Biology, Grenoble, France
| | | | | | | | | | | |
Collapse
|
144
|
Raval AP, Dave KR, Saul I, Gonzalez GJ, Diaz F. Synergistic inhibitory effect of nicotine plus oral contraceptive on mitochondrial complex-IV is mediated by estrogen receptor-β in female rats. J Neurochem 2012; 121:157-67. [DOI: 10.1111/j.1471-4159.2012.07661.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
145
|
Picard M, Burelle Y. Mitochondria: starving to reach quorum?: Insight into the physiological purpose of mitochondrial fusion. Bioessays 2012; 34:272-4. [PMID: 22290641 DOI: 10.1002/bies.201100179] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Martin Picard
- Department of Kinesiology, McGill University, Montreal, Canada.
| | | |
Collapse
|
146
|
Individual biochemical behaviour versus biological robustness: spotlight on the regulation of cytochrome c oxidase. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 748:265-81. [PMID: 22729862 DOI: 10.1007/978-1-4614-3573-0_11] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
During evolution from prokaryotes to eukaryotes, the main function of cytochrome c oxidase (COX), i.e., the coupling of oxygen reduction to proton translocation without the production of ROS (reactive oxygen species) remained unchanged demonstrating its robustness. A new regulation of respiration by the ATP/ADP ratio was introduced in eukaryotes based on nucleotide interaction with the added COX subunit IV. This allosteric ATP-inhibition was proposed to keep the mitochondrial membrane potential (ΔΨ(m)) at low healthy values and thus prevents the formation of ROS at complexes I and III. ROS have been implicated in various degenerative diseases. The allosteric ATP-inhibition of COX is reversibly switched on and off by phosphorylation of COX at a serine or threonine. In more than 100 individual preparations of rat heart and liver mitochondria, prepared under identical conditions, the extent of allosteric ATP-inhibition varied. This variability correlates with the variable inhibition of uncoupled respiration in intact isolated mitochondria by ATP. It is concluded that in higher organisms the allosteric ATP-inhibition is continually switched on and off by neuronal signalling in order to change oxidative phosphorylation from optimal efficiency with lower rate of ATP synthesis under resting conditions (low ΔΨ(m) and ROS production) to maximal rate of ATP synthesis under active (working, stress) conditions (elevated ΔΨ(m) and ROS production).
Collapse
|
147
|
Glanville EJ, Murray SA, Seebacher F. Thermal adaptation in endotherms: climate and phylogeny interact to determine population-level responses in a wild rat. Funct Ecol 2011. [DOI: 10.1111/j.1365-2435.2011.01933.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
148
|
Abstract
This review discusses the potential place of soluble adenylyl cyclase (sAC) in the framework of signaling in the cardiovascular system. cAMP has been studied as a critical and pleiotropic second messenger in cardiomyocytes, endothelial cells, and smooth muscle vascular cells for many years. It is involved in the transduction of signaling by catecholamines, prostaglandins, adenosine, and glucagon, just to name a few. These hormones can act via cAMP by binding to a G protein-coupled receptor on the plasma membrane with subsequent activation of a heterotrimeric G protein and its downstream effector, transmembrane adenylyl cyclase. This has long been the canonical standard for cAMP production in a cell. However, the relatively recent discovery of a unique source of cAMP, sAC, creates the potential for a shift in this signaling paradigm. In fact, sAC has been shown to play a role in apoptosis in coronary endothelial cells and cardiomyocytes. Additionally, it links nutrient utilization with ATP production in the liver and brain, which suggests one of many potential roles for sAC in cardiac function. The possibility of producing cAMP from a source distal to the plasma membrane provides a critical new building block for reconstructing the cellular signaling infrastructure.
Collapse
Affiliation(s)
- Jonathan Chen
- Department of Pharmacology, Weill Medical College of Cornell University, New York, NY 10065, USA
| | | | | |
Collapse
|
149
|
Heidler J, Al-Furoukh N, Kukat C, Salwig I, Ingelmann ME, Seibel P, Krüger M, Holtz J, Wittig I, Braun T, Szibor M. Nitric oxide-associated protein 1 (NOA1) is necessary for oxygen-dependent regulation of mitochondrial respiratory complexes. J Biol Chem 2011; 286:32086-93. [PMID: 21771794 DOI: 10.1074/jbc.m111.221986] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In eukaryotic cells, maintenance of cellular ATP stores depends mainly on mitochondrial oxidative phosphorylation (OXPHOS), which in turn requires sufficient cellular oxygenation. The crucial role of proper oxygenation for cellular viability is reflected by involvement of several mechanisms, which sense hypoxia and regulate activities of respiratory complexes according to available oxygen concentrations. Here, we focus on mouse nitric oxide-associated protein 1 (mNOA1), which has been identified as an important component of the machinery that adjusts OXPHOS activity to oxygen concentrations. mNOA1 is an evolutionary conserved GTP-binding protein that is involved in the regulation of mitochondrial protein translation and respiration. We found that mNOA1 is located mostly in the mitochondrial matrix from where it interacts with several high molecular mass complexes, most notably with the complex IV of the respiratory chain and the prohibitin complex. Knock-down of mNOA1 impaired enzyme activity I+III, resulting in oxidative stress and eventually cell death. mNOA1 is transcriptionally regulated in an oxygen-sensitive manner. We propose that oxygen-dependent regulation of mNOA1 is instrumental to adjusting OXPHOS activity to oxygen availability, thereby controlling mitochondrial metabolism.
Collapse
Affiliation(s)
- Juliana Heidler
- Department of Cardiac Development and Remodeling, Max-Planck-Institute for Heart and Lung Research, Ludwigstrasse 43, 61231 Bad Nauheim, Germany
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
150
|
García-Aguilar A, Cuezva JM. Immunocytochemistry: its applications and drawbacks for the study of gut neuroendocrinology. Front Physiol 1980; 9:1322. [PMID: 30283362 PMCID: PMC6156145 DOI: 10.3389/fphys.2018.01322] [Citation(s) in RCA: 56] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Accepted: 08/31/2018] [Indexed: 01/10/2023] Open
Abstract
The ATPase Inhibitory Factor 1 (IF1) is the physiological inhibitor of the mitochondrial ATP synthase. Herein, we summarize the regulation of the expression and activity of IF1 as a main driver of the activity of oxidative phosphorylation (OXPHOS) in mammalian tissues. We emphasize that the expression of IF1, which is a mitochondrial protein with very short half-life, is tissue-specifically expressed and primarily controlled at posttranscriptional levels. Inhibition of the activity of IF1 as inhibitor of the ATP synthase under normal physiological conditions is exerted by phosphorylation of S39 by a cAMP-dependent PKA-like activity of mitochondria in response to different physiological cues. Conditional tissue-specific transgenic mice overexpressing IF1 in colon, or a mutant active version of IF1 (IF1-H49K) in liver or in neurons, revealed the inhibition of the ATP synthase and the reprograming of energy metabolism to an enhanced glycolysis. In the IF1-H49K models, the assembly/activity of complex IV and the superassembly of complex V are also affected. Moreover, the IF1-mediated inhibition of the ATP synthase generates a reactive oxygen species (mtROS) signal that switches on the expression of nuclear genes that facilitate adaptation to a restrained OXPHOS. In contrast to normal mice, metabolically preconditioned animals are partially protected from the action of cytotoxic agents by upgrading the activation of stress kinases and transcription factors involved in resolving metabolic adaptation, the antioxidant response, cell survival, and the immune response of the tissue microenvironment. Altogether, we stress a fundamental physiological function for the ATP synthase and its inhibitor in mitohormesis.
Collapse
|