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Pan T, Yang B, Yao S, Wang R, Zhu Y. Exploring the multifaceted role of adenosine nucleotide translocase 2 in cellular and disease processes: A comprehensive review. Life Sci 2024; 351:122802. [PMID: 38857656 DOI: 10.1016/j.lfs.2024.122802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2024] [Revised: 05/04/2024] [Accepted: 06/04/2024] [Indexed: 06/12/2024]
Abstract
Adenosine nucleotide translocases (ANTs) are a family of proteins abundant in the inner mitochondrial membrane, primarily responsible for shuttling ADP and ATP across the mitochondrial membrane. Additionally, ANTs are key players in balancing mitochondrial energy metabolism and regulating cell death. ANT2 isoform, highly expressed in undifferentiated and proliferating cells, is implicated in the development and drug resistance of various tumors. We conduct a detailed analysis of the potential mechanisms by which ANT2 may influence tumorigenesis and drug resistance. Notably, the significance of ANT2 extends beyond oncology, with roles in non-tumor cell processes including blood cell development, gastrointestinal motility, airway hydration, nonalcoholic fatty liver disease, obesity, chronic kidney disease, and myocardial development, making it a promising therapeutic target for multiple pathologies. To better understand the molecular mechanisms of ANT2, this review summarizes the structural properties, expression patterns, and basic functions of the ANT2 protein. In particular, we review and analyze the controversy surrounding ANT2, focusing on its role in transporting ADP/ATP across the inner mitochondrial membrane, its involvement in the composition of the mitochondrial permeability transition pore, and its participation in apoptosis.
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Affiliation(s)
- Tianhui Pan
- Laboratory of Gastroenterology, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, Zhejiang 310009, PR China
| | - Bin Yang
- Laboratory of Gastroenterology, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, Zhejiang 310009, PR China
| | - Sheng Yao
- Laboratory of Gastroenterology, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, Zhejiang 310009, PR China
| | - Rui Wang
- Laboratory of Gastroenterology, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, Zhejiang 310009, PR China
| | - Yongliang Zhu
- Laboratory of Gastroenterology, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, Zhejiang 310009, PR China.
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2
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Patil YN, Gnaiger E, Landry AP, Leno ZJ, Hand SC. OXPHOS capacity is diminished and the phosphorylation system inhibited during diapause in an extremophile, embryos of Artemia franciscana. J Exp Biol 2024; 227:jeb245828. [PMID: 38099471 DOI: 10.1242/jeb.245828] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Accepted: 12/04/2023] [Indexed: 01/23/2024]
Abstract
Diapause exhibited by embryos of Artemia franciscana is accompanied by severe arrest of respiration. A large fraction of this depression is attributable to downregulation of trehalose catabolism that ultimately restricts fuel to mitochondria. This study now extends knowledge on the mechanism by revealing metabolic depression is heightened by inhibitions within mitochondria. Compared with that in embryo lysates during post-diapause, oxidative phosphorylation (OXPHOS) capacity P is depressed during diapause when either NADH-linked substrates (pyruvate and malate) for electron transfer (electron transfer capacity, E) through respiratory Complex I or the Complex II substrate succinate are used. When pyruvate, malate and succinate were combined, respiratory inhibition by the phosphorylation system in diapause lysates was discovered as judged by P/E flux control ratios (two-way ANOVA; F1,24=38.78; P<0.0001). Inhibition was eliminated as the diapause extract was diluted (significant interaction term; F2,24=9.866; P=0.0007), consistent with the presence of a diffusible inhibitor. One candidate is long-chain acyl-CoA esters known to inhibit the adenine nucleotide translocator. Addition of oleoyl-CoA to post-diapause lysates markedly decreased the P/E ratio to 0.40±0.07 (mean±s.d.; P=0.002) compared with 0.79±0.11 without oleoyl-CoA. Oleoyl-CoA inhibits the phosphorylation system and may be responsible for the depressed P/E in lysates from diapause embryos. With isolated mitochondria, depression of P/E by oleoyl-CoA was fully reversed by addition of l-carnitine (control versus recovery with l-carnitine, P=0.338), which facilitates oleoyl-CoA transport into the matrix and elimination by β-oxidation. In conclusion, severe metabolic arrest during diapause promoted by restricting glycolytic carbon to mitochondria is reinforced by depression of OXPHOS capacity and the phosphorylation system.
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Affiliation(s)
- Yuvraj N Patil
- Department of Biological Sciences, Division of Cellular, Developmental and Integrative Biology, Louisiana State University, Baton Rouge, LA 70803, USA
| | | | - Alexander P Landry
- Department of Biological Sciences, Division of Cellular, Developmental and Integrative Biology, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Zachary J Leno
- Department of Biological Sciences, Division of Cellular, Developmental and Integrative Biology, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Steven C Hand
- Department of Biological Sciences, Division of Cellular, Developmental and Integrative Biology, Louisiana State University, Baton Rouge, LA 70803, USA
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Bekeova C, Han JI, Xu H, Kerr E, Blackburne B, Lynch SC, Mesaros C, Murgia M, Vadigepalli R, Beld J, Leonardi R, Snyder NW, Seifert EL. Acyl-CoA thioesterase-2 facilitates β-oxidation in glycolytic skeletal muscle in a lipid supply dependent manner. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.27.546724. [PMID: 37425757 PMCID: PMC10327053 DOI: 10.1101/2023.06.27.546724] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/11/2023]
Abstract
Acyl-Coenzyme A (acyl-CoA) thioesters are compartmentalized intermediates that participate in in multiple metabolic reactions within the mitochondrial matrix. The limited availability of free CoA (CoASH) in the matrix raises the question of how the local acyl-CoA concentration is regulated to prevent trapping of CoASH from overload of any specific substrate. Acyl-CoA thioesterase-2 (ACOT2) hydrolyzes long-chain acyl-CoAs to their constituent fatty acids and CoASH, and is the only mitochondrial matrix ACOT refractory to inhibition by CoASH. Thus, we reasoned that ACOT2 may constitutively regulate matrix acyl-CoA levels. Acot2 deletion in murine skeletal muscle (SM) resulted in acyl-CoA build-up when lipid supply and energy demands were modest. When energy demand and pyruvate availability were elevated, lack of ACOT2 activity promoted glucose oxidation. This preference for glucose over fatty acid oxidation was recapitulated in C2C12 myotubes with acute depletion of Acot2 , and overt inhibition of β-oxidation was demonstrated in isolated mitochondria from Acot2 -depleted glycolytic SM. In mice fed a high fat diet, ACOT2 enabled the accretion of acyl-CoAs and ceramide derivatives in glycolytic SM, and this was associated with worse glucose homeostasis compared to when ACOT2 was absent. These observations suggest that ACOT2 supports CoASH availability to facilitate β-oxidation in glycolytic SM when lipid supply is modest. However, when lipid supply is high, ACOT2 enables acyl-CoA and lipid accumulation, CoASH sequestration, and poor glucose homeostasis. Thus, ACOT2 regulates matrix acyl-CoA concentration in glycolytic muscle, and its impact depends on lipid supply.
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Chen Y, Wu L, Liu J, Ma L, Zhang W. Adenine nucleotide translocase: Current knowledge in post-translational modifications, regulations and pathological implications for human diseases. FASEB J 2023; 37:e22953. [PMID: 37224026 DOI: 10.1096/fj.202201855rr] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 04/01/2023] [Accepted: 04/25/2023] [Indexed: 05/26/2023]
Abstract
Adenine nucleotide translocases (ANTs) are central to mitochondrial integrity and bioenergetic metabolism. This review aims to integrate the progresses and knowledge on ANTs over the last few years, contributing to a potential implication of ANTs for various diseases. Structures, functions, modifications, regulators and pathological implications of ANTs for human diseases are intensively demonstrated here. ANTs have four isoforms (ANT1-4), responsible for exchanging ATP/ADP, possibly composing of pro-apoptotic mPTP as a major component, and mediating FA-dependent uncoupling of proton efflux. ANT can be modified by methylation, nitrosylation and nitroalkylation, acetylation, glutathionylation, phosphorylation, carbonylation and hydroxynonenal-induced modifications. Compounds, including bongkrekic acid, atractyloside calcium, carbon monoxide, minocycline, 4-(N-(S-penicillaminylacetyl)amino) phenylarsonous acid, cardiolipin, free long-chain fatty acids, agaric acid, long chain acyl-coenzyme A esters, all have an ability to regulate ANT activities. ANT impairment leads to bioenergetic failure and mitochondrial dysfunction, contributing to pathogenesis of diseases, such as diabetes (deficiency), heart disease (deficiency), Parkinson's disease (reduction), Sengers Syndrome (decrease), cancer (isoform shifting), Alzheimer's Disease (coaggregation with Tau), Progressive External Opthalmoplegia (mutation), and Fascioscapulohumeral muscular dystrophy (overexpression). This review improves the understanding of the mechanism of ANT in pathogenesis of human diseases, and opens a window for novel therapeutic strategies targeted on ANT in diseases.
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Affiliation(s)
- Yingfei Chen
- Grade 2020, Capital Medical University, Beijing, China
| | - Leshuang Wu
- Grade 2019, Dalian Medical University, Dalian, China
| | - Jun Liu
- Department of Epidemiology, Dalian Medical University, Dalian, China
| | - Li Ma
- Department of Epidemiology, Dalian Medical University, Dalian, China
| | - Wenli Zhang
- Biochemistry and Molecular Biology Department of College of Basic Medical Sciences, Dalian Medical University, Dalian, China
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Yan A, Xie G, Ding X, Wang Y, Guo L. Effects of Lipid Overload on Heart in Metabolic Diseases. Horm Metab Res 2021; 53:771-778. [PMID: 34891207 PMCID: PMC8664556 DOI: 10.1055/a-1693-8356] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Metabolic diseases are often associated with lipid and glucose metabolism abnormalities, which increase the risk of cardiovascular disease. Diabetic cardiomyopathy (DCM) is an important development of metabolic diseases and a major cause of death. Lipids are the main fuel for energy metabolism in the heart. The increase of circulating lipids affects the uptake and utilization of fatty acids and glucose in the heart, and also affects mitochondrial function. In this paper, the mechanism of lipid overload in metabolic diseases leading to cardiac energy metabolism disorder is discussed.
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Affiliation(s)
- An Yan
- Tianjin University of Traditional Chinese Medicine, Tianjin,
China
| | - Guinan Xie
- Tianjin University of Traditional Chinese Medicine, Tianjin,
China
| | - Xinya Ding
- Tianjin University of Traditional Chinese Medicine, Tianjin,
China
| | - Yi Wang
- Tianjin University of Traditional Chinese Medicine, Tianjin,
China
- Correspondence Yi Wang Institute of Traditional Chinese MedicineTianjin University of Traditional Chinese Medicine300193 TianjinChina+86-22-59596555
| | - Liping Guo
- Tianjin Academy of Traditional Chinese Medicine, Tianjin,
China
- Liping Guo Tianjin Academy of Traditional Chinese Medicine300120 TianjinChina
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Kerr M, Dennis KMJH, Carr CA, Fuller W, Berridge G, Rohling S, Aitken CL, Lopez C, Fischer R, Miller JJ, Clarke K, Tyler DJ, Heather LC. Diabetic mitochondria are resistant to palmitoyl CoA inhibition of respiration, which is detrimental during ischemia. FASEB J 2021; 35:e21765. [PMID: 34318967 PMCID: PMC8662312 DOI: 10.1096/fj.202100394r] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Revised: 05/24/2021] [Accepted: 06/14/2021] [Indexed: 01/07/2023]
Abstract
The bioactive lipid intermediate palmitoyl CoA (PCoA) can inhibit mitochondrial ADP/ATP transport, though the physiological relevance of this regulation remains unclear. We questioned whether myocardial ischemia provides a pathological setting in which PCoA regulation of ADP/ATP transport would be beneficial, and secondly, whether the chronically elevated lipid content within the diabetic heart could make mitochondria less sensitive to the effects of PCoA. PCoA acutely decreased ADP‐stimulated state 3 respiration and increased the apparent Km for ADP twofold. The half maximal inhibitory concentration (IC50) of PCoA in control mitochondria was 22 µM. This inhibitory effect of PCoA on respiration was blunted in diabetic mitochondria, with no significant difference in the Km for ADP in the presence of PCoA, and an increase in the IC50 to 32 µM PCoA. The competitive inhibition by PCoA was localised to the phosphorylation apparatus, particularly the ADP/ATP carrier (AAC). During ischemia, the AAC imports ATP into the mitochondria, where it is hydrolysed by reversal of the ATP synthase, regenerating the membrane potential. Addition of PCoA dose‐dependently prevented this wasteful ATP hydrolysis for membrane repolarisation during ischemia, however, this beneficial effect was blunted in diabetic mitochondria. Finally, using 31P‐magnetic resonance spectroscopy we demonstrated that diabetic hearts lose ATP more rapidly during ischemia, with a threefold higher ATP decay rate compared with control hearts. In conclusion, PCoA plays a role in protecting mitochondrial energetics during ischemia, by preventing wasteful ATP hydrolysis. However, this beneficial effect is blunted in diabetes, contributing to the impaired energy metabolism seen during myocardial ischemia in the diabetic heart.
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Affiliation(s)
- M Kerr
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - K M J H Dennis
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - C A Carr
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - W Fuller
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, UK
| | - G Berridge
- Target Discovery Institute, University of Oxford, Oxford, UK
| | - S Rohling
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - C L Aitken
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - C Lopez
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - R Fischer
- Target Discovery Institute, University of Oxford, Oxford, UK
| | - J J Miller
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK.,Department of Physics, University of Oxford, Oxford, UK.,Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - K Clarke
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - D J Tyler
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK.,Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - L C Heather
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
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Morciano G, Vitto VAM, Bouhamida E, Giorgi C, Pinton P. Mitochondrial Bioenergetics and Dynamism in the Failing Heart. Life (Basel) 2021; 11:life11050436. [PMID: 34066065 PMCID: PMC8151847 DOI: 10.3390/life11050436] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Revised: 05/07/2021] [Accepted: 05/07/2021] [Indexed: 12/13/2022] Open
Abstract
The heart is responsible for pumping blood, nutrients, and oxygen from its cavities to the whole body through rhythmic and vigorous contractions. Heart function relies on a delicate balance between continuous energy consumption and generation that changes from birth to adulthood and depends on a very efficient oxidative metabolism and the ability to adapt to different conditions. In recent years, mitochondrial dysfunctions were recognized as the hallmark of the onset and development of manifold heart diseases (HDs), including heart failure (HF). HF is a severe condition for which there is currently no cure. In this condition, the failing heart is characterized by a disequilibrium in mitochondrial bioenergetics, which compromises the basal functions and includes the loss of oxygen and substrate availability, an altered metabolism, and inefficient energy production and utilization. This review concisely summarizes the bioenergetics and some other mitochondrial features in the heart with a focus on the features that become impaired in the failing heart.
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Affiliation(s)
- Giampaolo Morciano
- Maria Cecilia Hospital, GVM Care&Research, 48033 Cotignola, Italy
- Laboratory for Technologies of Advanced Therapies (LTTA), Section of Experimental Medicine, Department of Medical Sciences, University of Ferrara, 44121 Ferrara, Italy; (V.A.M.V.); (E.B.); (C.G.)
- Correspondence: (G.M.); (P.P.)
| | - Veronica Angela Maria Vitto
- Laboratory for Technologies of Advanced Therapies (LTTA), Section of Experimental Medicine, Department of Medical Sciences, University of Ferrara, 44121 Ferrara, Italy; (V.A.M.V.); (E.B.); (C.G.)
| | - Esmaa Bouhamida
- Laboratory for Technologies of Advanced Therapies (LTTA), Section of Experimental Medicine, Department of Medical Sciences, University of Ferrara, 44121 Ferrara, Italy; (V.A.M.V.); (E.B.); (C.G.)
| | - Carlotta Giorgi
- Laboratory for Technologies of Advanced Therapies (LTTA), Section of Experimental Medicine, Department of Medical Sciences, University of Ferrara, 44121 Ferrara, Italy; (V.A.M.V.); (E.B.); (C.G.)
| | - Paolo Pinton
- Maria Cecilia Hospital, GVM Care&Research, 48033 Cotignola, Italy
- Laboratory for Technologies of Advanced Therapies (LTTA), Section of Experimental Medicine, Department of Medical Sciences, University of Ferrara, 44121 Ferrara, Italy; (V.A.M.V.); (E.B.); (C.G.)
- Correspondence: (G.M.); (P.P.)
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8
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Dhar PK, Grupp IL, Schwartz A, Grupp G, Matlib MA. Reduction of Carnitine Content by Inhibition of Its Biosynthesis Results in Protection of Isolated Guinea Pig Hearts against Hypoxic Damage. J Cardiovasc Pharmacol Ther 2020; 1:235-242. [PMID: 10684422 DOI: 10.1177/107424849600100307] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Background3-(2,2,2-trimethylhydrazinium) propionate (THP or mildronate) is an inhibitor of carnitine biosynthesis. This study was carried out to determine whether feeding of guinea pigs with THP results in decreased myocardial-free carnitine content and, as a result, attenuates hypoxic damage in isolated and paced work-performing hearts.Methods and ResultsGuinea pigs were administered either distilled water or 100 mg THP/kg/day orally for 10 days. The treatment resulted in about a 50% decline in myocardial-free carnitine content, from 11.1 ± 0.2 (n = 5) to 5.6 ± 0.2 (n = 5) μM/g dry weight of the heart. The left ventricular contractile function of the hearts was measured during normoxic perfusion (PO2= 590 mmHg), hypoxic perfusion (PO2= 149 mmHg), and reperfusion (PO2= 590 mmHg). In both untreated and THP-treated groups, the rate of development of intraventricular pressure (+dP/dt) under normoxic perfusion was similar; however, +dP/dt declined to about 10% of the initial rate within 20 minutes of hypoxic perfusion. In the THP-treated group of hearts, the initial decline was slower than that of the untreated animal hearts. After 20 minutes of normoxic reperfusion following 60 minutes of hypoxic perfusion, the recovery of +dP/dt and -dP/dt was greater in the THP-treated group than in the untreated group. The elevation of end-diastolic pressure during hypoxia was completely reversed by normoxic reperfusion of the THP-treated group but not in the untreated group. Mitochondria isolated from hearts from the THP-treated group after normoxic reperfusion following hypoxic perfusion exhibited better respiratory function than those from untreated hearts.ConclusionThe data suggest that feeding guinea pigs with THP results in reduced myocardial-free carnitine content and attenuation of hypoxic and reperfusion injury in isolated hearts.
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Affiliation(s)
- PK Dhar
- Department of Pharmacology and Cell Biophysics, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA
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Lamhonwah AM, Tein I. Expression of the organic cation/carnitine transporter family (Octn1,-2 and-3) in mdx muscle and heart: Implications for early carnitine therapy in Duchenne muscular dystrophy to improve cellular carnitine homeostasis. Clin Chim Acta 2020; 505:92-97. [PMID: 32070725 DOI: 10.1016/j.cca.2020.02.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2019] [Revised: 02/13/2020] [Accepted: 02/14/2020] [Indexed: 10/25/2022]
Abstract
INTRODUCTION Carnitine is essential for long-chain fatty acid oxidation in muscle and heart. Tissue stores are regulated by organic cation/Cn transporter plasmalemmal Octn2. We previously demonstrated low carnitine in quadriceps/gluteus and heart of adult mdx mice. METHODS We studied protein and mRNA expression of Octn2, mitochondrial Octn1 and peroxisomal Octn3 in adult male C57BL/10ScSn-DMD mdx/J quadriceps, heart, and diaphragm compared to C57BL/10SnJ mice. RESULTS We demonstrated reduction in mOctn2 expression on Western blot and similar expression of mOctn1 and mOctn3 in mdx quadriceps, heart and diaphragm. There was a significant upregulation of mOctn1 and mOctn2 mRNA by qRT-PCR in mdx quadriceps and of mOctn2 and mOctn3 mRNA in mdx heart. We showed upregulation of mdx mOctn1 and mOctn3 mRNA but no increase in protein expression. DISCUSSION Dystrophin deficiency likely disrupts Octn2 expression decreasing muscle carnitine uptake thus contributing to membranotoxic long-chain acyl-CoAs with sarcolemmal and organellar membrane oxidative injury providing a treatment rationale for early L-carnitine in DMD.
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Affiliation(s)
- Anne-Marie Lamhonwah
- Department of Pediatrics, Division of Neurology, Hospital for Sick Children, University of Toronto, 555 University, Ave., Toronto, Ontario M5G 1X8, Canada; Genetics and Genome Biology Program, The Research Institute, Hospital for Sick Children, University of Toronto, Toronto, Ontario M5G 1X8, Canada
| | - Ingrid Tein
- Department of Pediatrics, Division of Neurology, Hospital for Sick Children, University of Toronto, 555 University, Ave., Toronto, Ontario M5G 1X8, Canada; Genetics and Genome Biology Program, The Research Institute, Hospital for Sick Children, University of Toronto, Toronto, Ontario M5G 1X8, Canada; Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario M5S 1A1, Canada.
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10
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Divakaruni AS, Hsieh WY, Minarrieta L, Duong TN, Kim KKO, Desousa BR, Andreyev AY, Bowman CE, Caradonna K, Dranka BP, Ferrick DA, Liesa M, Stiles L, Rogers GW, Braas D, Ciaraldi TP, Wolfgang MJ, Sparwasser T, Berod L, Bensinger SJ, Murphy AN. Etomoxir Inhibits Macrophage Polarization by Disrupting CoA Homeostasis. Cell Metab 2018; 28:490-503.e7. [PMID: 30043752 PMCID: PMC6125190 DOI: 10.1016/j.cmet.2018.06.001] [Citation(s) in RCA: 218] [Impact Index Per Article: 36.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Revised: 04/20/2018] [Accepted: 06/02/2018] [Indexed: 12/12/2022]
Abstract
Long-chain fatty acid (LCFA) oxidation has been shown to play an important role in interleukin-4 (IL-4)-mediated macrophage polarization (M(IL-4)). However, many of these conclusions are based on the inhibition of carnitine palmitoyltransferase-1 with high concentrations of etomoxir that far exceed what is required to inhibit enzyme activity (EC90 < 3 μM). We employ genetic and pharmacologic models to demonstrate that LCFA oxidation is largely dispensable for IL-4-driven polarization. Unexpectedly, high concentrations of etomoxir retained the ability to disrupt M(IL-4) polarization in the absence of Cpt1a or Cpt2 expression. Although excess etomoxir inhibits the adenine nucleotide translocase, oxidative phosphorylation is surprisingly dispensable for M(IL-4). Instead, the block in polarization was traced to depletion of intracellular free coenzyme A (CoA), likely resulting from conversion of the pro-drug etomoxir into active etomoxiryl CoA. These studies help explain the effect(s) of excess etomoxir on immune cells and reveal an unappreciated role for CoA metabolism in macrophage polarization.
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Affiliation(s)
- Ajit S Divakaruni
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, Los Angeles, CA 90095, USA.
| | - Wei Yuan Hsieh
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Lucía Minarrieta
- Institute of Infection Immunology, TWINCORE, Centre for Experimental and Clinical Infection Research, A Joint Venture Between the Medical School Hannover (MHH) and the Helmholtz Centre for Infection Research (HZI), Hannover, Germany
| | - Tin N Duong
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Kristen K O Kim
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Brandon R Desousa
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Alexander Y Andreyev
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Caitlyn E Bowman
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Kacey Caradonna
- Agilent Technologies, 5301 Stevens Creek Boulevard, Santa Clara, CA 95051, USA
| | - Brian P Dranka
- Agilent Technologies, 5301 Stevens Creek Boulevard, Santa Clara, CA 95051, USA
| | - David A Ferrick
- Agilent Technologies, 5301 Stevens Creek Boulevard, Santa Clara, CA 95051, USA
| | - Marc Liesa
- Department of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Linsey Stiles
- Department of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - George W Rogers
- Agilent Technologies, 5301 Stevens Creek Boulevard, Santa Clara, CA 95051, USA
| | - Daniel Braas
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, Los Angeles, CA 90095, USA; UCLA Metabolomics Center and Crump Institute for Molecular Imaging, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Theodore P Ciaraldi
- Veterans Affairs San Diego Healthcare System, La Jolla, CA 92161, USA; Department of Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Michael J Wolfgang
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Tim Sparwasser
- Institute of Infection Immunology, TWINCORE, Centre for Experimental and Clinical Infection Research, A Joint Venture Between the Medical School Hannover (MHH) and the Helmholtz Centre for Infection Research (HZI), Hannover, Germany
| | - Luciana Berod
- Institute of Infection Immunology, TWINCORE, Centre for Experimental and Clinical Infection Research, A Joint Venture Between the Medical School Hannover (MHH) and the Helmholtz Centre for Infection Research (HZI), Hannover, Germany
| | - Steven J Bensinger
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, Los Angeles, CA 90095, USA; Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Anne N Murphy
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, USA
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l -carnitine supplementation during vitrification or warming of in vivo -produced ovine embryos does not affect embryonic survival rates, but alters CrAT and PRDX1 expression. Theriogenology 2018; 105:150-157. [DOI: 10.1016/j.theriogenology.2017.09.022] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Revised: 09/12/2017] [Accepted: 09/17/2017] [Indexed: 01/01/2023]
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12
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Altered Carnitine Homeostasis in Children With Increased Pulmonary Blood Flow Due to Ventricular Septal Defects. Pediatr Crit Care Med 2017; 18:931-934. [PMID: 28723882 PMCID: PMC5628126 DOI: 10.1097/pcc.0000000000001275] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
OBJECTIVES Congenital heart disease with increased pulmonary blood flow results in progressive pulmonary vascular endothelial dysfunction and associated increased perioperative morbidity. Using our ovine model of congenital heart disease with increased pulmonary blood flow, we have previously demonstrated progressive endothelial dysfunction associated with disruption in carnitine homeostasis, mitochondrial dysfunction, decreased nitric oxide signaling, and enhanced reactive oxygen species generation. However, potential alterations in these parameters in patients with congenital heart disease have not been investigated. The objective of this study was to test the hypothesis that children with increased pulmonary blood flow will have evidence of altered carnitine homeostasis, mitochondrial dysfunction, decreased nitric oxide levels, and increased reactive oxygen species generation. DESIGN A prospective single-center cohort study. SETTING A tertiary care cardiac ICU/PICU. PATIENTS Arterial blood samples from 18 patients with congenital heart disease associated with increased pulmonary blood flow (ventricular septal defect), 20 with congenital heart disease without increased pulmonary blood flow (tetralogy of Fallot), and 10 without heart disease (controls) were obtained. INTERVENTIONS Plasma levels of total carnitine, free carnitine, acylcarnitine, and lactate-to-pyruvate ratios, an indicator of mitochondrial function, were determined and compared. In addition, levels of superoxide and hydrogen peroxide were determined and compared in patients with ventricular septal defect and controls. Statistical analysis was performed using an unpaired t test and analysis of variance. MEASUREMENTS AND MAIN RESULTS Baseline acylcarnitine levels (25.7 ± 13 vs 12.7 ± 8.3; p < 0.05), the acylcarnitine-to-free carnitine ratio (0.8 ± 0.1 vs 0.3 ± 0.05; p < 0.05), and the lactate-to-pyruvate ratio were higher in ventricular septal defect (27.5 ± 3.8 vs 11.1 ± 4.1, p < 0.05) than tetralogy of Fallot; there were no differences between tetralogy of Fallot and control. Superoxide and H2O2 levels were also higher in ventricular septal defect compared with controls, and NOx levels were lower in ventricular septal defect patients compared with tetralogy of Fallot and controls (p < 0.05). CONCLUSIONS These data suggest that increased pulmonary blood flow from ventricular septal defect results in altered carnitine and mitochondrial homeostasis, decreased nitric oxide signaling, and increased reactive oxygen species production. These data are consistent with our animal data demonstrating that altered carnitine homeostasis results in mitochondrial dysfunction, increased reactive oxygen species production, and decreased bioavailable nitric oxide. Since disruption of carnitine metabolism may contribute to endothelial dysfunction, carnitine supplementation may attenuate endothelial dysfunction associated with increased pulmonary blood flow and warrants further investigation.
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L-Carnitine and Acetyl-L-carnitine Roles and Neuroprotection in Developing Brain. Neurochem Res 2017; 42:1661-1675. [PMID: 28508995 DOI: 10.1007/s11064-017-2288-7] [Citation(s) in RCA: 151] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2017] [Revised: 04/27/2017] [Accepted: 04/28/2017] [Indexed: 12/30/2022]
Abstract
L-Carnitine functions to transport long chain fatty acyl-CoAs into the mitochondria for degradation by β-oxidation. Treatment with L-carnitine can ameliorate metabolic imbalances in many inborn errors of metabolism. In recent years there has been considerable interest in the therapeutic potential of L-carnitine and its acetylated derivative acetyl-L-carnitine (ALCAR) for neuroprotection in a number of disorders including hypoxia-ischemia, traumatic brain injury, Alzheimer's disease and in conditions leading to central or peripheral nervous system injury. There is compelling evidence from preclinical studies that L-carnitine and ALCAR can improve energy status, decrease oxidative stress and prevent subsequent cell death in models of adult, neonatal and pediatric brain injury. ALCAR can provide an acetyl moiety that can be oxidized for energy, used as a precursor for acetylcholine, or incorporated into glutamate, glutamine and GABA, or into lipids for myelination and cell growth. Administration of ALCAR after brain injury in rat pups improved long-term functional outcomes, including memory. Additional studies are needed to better explore the potential of L-carnitine and ALCAR for protection of developing brain as there is an urgent need for therapies that can improve outcome after neonatal and pediatric brain injury.
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14
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Ludzki A, Paglialunga S, Smith BK, Herbst EAF, Allison MK, Heigenhauser GJ, Neufer PD, Holloway GP. Rapid Repression of ADP Transport by Palmitoyl-CoA Is Attenuated by Exercise Training in Humans: A Potential Mechanism to Decrease Oxidative Stress and Improve Skeletal Muscle Insulin Signaling. Diabetes 2015; 64:2769-79. [PMID: 25845660 PMCID: PMC4876790 DOI: 10.2337/db14-1838] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Accepted: 03/28/2015] [Indexed: 12/11/2022]
Abstract
Mitochondrial ADP transport may represent a convergence point unifying two prominent working models for the development of insulin resistance, as reactive lipids (specifically palmitoyl-CoA [P-CoA]) can inhibit ADP transport and subsequently increase mitochondrial reactive oxygen species emissions. In the current study, we aimed to determine if exercise training in humans diminished P-CoA attenuation of mitochondrial ADP respiratory sensitivity. Six weeks of exercise training increased whole-body glucose homeostasis and skeletal muscle Akt signaling and reduced markers of oxidative stress without reducing maximal mitochondrial H2O2 emissions. To ascertain if enhanced mitochondrial ADP transport contributed to the improvement in the in vivo oxidative state, we determined mitochondrial ADP sensitivity in the presence and absence of P-CoA. In the absence of P-CoA, exercise training reduced mitochondrial ADP sensitivity. In contrast, exercise training increased mitochondrial ADP sensitivity with P-CoA present. We further show that P-CoA noncompetitively inhibits mitochondrial ADP transport and the ability of ADP to attenuate mitochondrial H2O2 emission. Altogether, the current data provide a potential mechanism for how P-CoA contributes to insulin resistance and highlight the ability of exercise training to diminish P-CoA attenuation in mitochondrial ADP transport.
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Affiliation(s)
- Alison Ludzki
- Department of Human Health & Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Sabina Paglialunga
- Department of Human Health & Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Brennan K Smith
- Department of Human Health & Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada Department of Medicine, McMaster University, Hamilton, Ontario, Canada
| | - Eric A F Herbst
- Department of Human Health & Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Mary K Allison
- Department of Human Health & Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | | | - P Darrell Neufer
- East Carolina Diabetes and Obesity Institute, Departments of Physiology and Kinesiology, East Carolina University, Greenville, NC
| | - Graham P Holloway
- Department of Human Health & Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
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15
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Habarou F, Brassier A, Rio M, Chrétien D, Monnot S, Barbier V, Barouki R, Bonnefont JP, Boddaert N, Chadefaux-Vekemans B, Le Moyec L, Bastin J, Ottolenghi C, de Lonlay P. Pyruvate carboxylase deficiency: An underestimated cause of lactic acidosis. Mol Genet Metab Rep 2014. [PMID: 28649521 PMCID: PMC5471145 DOI: 10.1016/j.ymgmr.2014.11.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Pyruvate carboxylase (PC) is a biotin-containing mitochondrial enzyme that catalyzes the conversion of pyruvate to oxaloacetate, thereby being involved in gluconeogenesis and in energy production through replenishment of the tricarboxylic acid (TCA) cycle with oxaloacetate. PC deficiency is a very rare metabolic disorder. We report on a new patient affected by the moderate form (the American type A). Diagnosis was nearly fortuitous, resulting from the revision of an initial diagnosis of mitochondrial complex IV (C IV) defect. The patient presented with severe lactic acidosis and pronounced ketonuria, associated with lethargy at age 23 months. Intellectual disability was noted at this time. Amino acids in plasma and organic acids in urine did not show patterns of interest for the diagnostic work-up. In skin fibroblasts PC showed no detectable activity whereas biotinidase activity was normal. We had previously reported another patient with the severe form of PC deficiency and we show that she also had secondary C IV deficiency in fibroblasts. Different anaplerotic treatments in vivo and in vitro were tested using fibroblasts of both patients with 2 different types of PC deficiency, type A (patient 1) and type B (patient 2). Neither clinical nor biological effects in vivo and in vitro were observed using citrate, aspartate, oxoglutarate and bezafibrate. In conclusion, this case report suggests that the moderate form of PC deficiency may be underdiagnosed and illustrates the challenges raised by energetic disorders in terms of diagnostic work-up and therapeutical strategy even in a moderate form.
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Affiliation(s)
- F Habarou
- Centre de Référence des Maladies Héréditaires du Métabolisme, Hôpital Necker, APHP, Paris, France.,INSERM U1124, Université Paris Descartes, Paris, France.,Service de Biochimie Métabolomique et Protéomique, Hôpital Necker, APHP, Paris, France
| | - A Brassier
- Centre de Référence des Maladies Héréditaires du Métabolisme, Hôpital Necker, APHP, Paris, France.,Université Paris Descartes, Paris, France
| | - M Rio
- Département de Génétique, Hôpital Necker, APHP, Paris, France
| | | | - S Monnot
- Département de Génétique, Hôpital Necker, APHP, Paris, France.,IHU Imagine, UMR1163, France
| | - V Barbier
- Centre de Référence des Maladies Héréditaires du Métabolisme, Hôpital Necker, APHP, Paris, France
| | - R Barouki
- Centre de Référence des Maladies Héréditaires du Métabolisme, Hôpital Necker, APHP, Paris, France.,INSERM U1124, Université Paris Descartes, Paris, France.,Service de Biochimie Métabolomique et Protéomique, Hôpital Necker, APHP, Paris, France
| | - J P Bonnefont
- Département de Génétique, Hôpital Necker, APHP, Paris, France.,INSERM U781, Paris, France
| | - N Boddaert
- Service de Radiologie Pédiatrique, Hôpital Necker, APHP, Paris, France
| | - B Chadefaux-Vekemans
- Centre de Référence des Maladies Héréditaires du Métabolisme, Hôpital Necker, APHP, Paris, France.,INSERM U1124, Université Paris Descartes, Paris, France.,Service de Biochimie Métabolomique et Protéomique, Hôpital Necker, APHP, Paris, France
| | - L Le Moyec
- INSERM U902, Université d'Evry Val d'Essonne, INSERM UBIAE U902, Boulevard François Miterrand, 91025 Evry, France
| | - J Bastin
- INSERM U1124, Université Paris Descartes, Paris, France
| | - C Ottolenghi
- Centre de Référence des Maladies Héréditaires du Métabolisme, Hôpital Necker, APHP, Paris, France.,INSERM U1124, Université Paris Descartes, Paris, France.,Service de Biochimie Métabolomique et Protéomique, Hôpital Necker, APHP, Paris, France
| | - P de Lonlay
- Centre de Référence des Maladies Héréditaires du Métabolisme, Hôpital Necker, APHP, Paris, France.,Université Paris Descartes, Paris, France.,INSERM U781, Paris, France
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16
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Aon MA, Bhatt N, Cortassa SC. Mitochondrial and cellular mechanisms for managing lipid excess. Front Physiol 2014; 5:282. [PMID: 25132820 PMCID: PMC4116787 DOI: 10.3389/fphys.2014.00282] [Citation(s) in RCA: 160] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Accepted: 07/10/2014] [Indexed: 12/16/2022] Open
Abstract
Current scientific debates center on the impact of lipids and mitochondrial function on diverse aspects of human health, nutrition and disease, among them the association of lipotoxicity with the onset of insulin resistance in skeletal muscle, and with heart dysfunction in obesity and diabetes. Mitochondria play a fundamental role in aging and in prevalent acute or chronic diseases. Lipids are main mitochondrial fuels however these molecules can also behave as uncouplers and inhibitors of oxidative phosphorylation. Knowledge about the functional composition of these contradictory effects and their impact on mitochondrial-cellular energetics/redox status is incomplete. Cells store fatty acids (FAs) as triacylglycerol and package them into cytoplasmic lipid droplets (LDs). New emerging data shows the LD as a highly dynamic storage pool of FAs that can be used for energy reserve. Lipid excess packaging into LDs can be seen as an adaptive response to fulfilling energy supply without hindering mitochondrial or cellular redox status and keeping low concentration of lipotoxic intermediates. Herein we review the mechanisms of action and utilization of lipids by mitochondria reported in liver, heart and skeletal muscle under relevant physiological situations, e.g., exercise. We report on perilipins, a family of proteins that associate with LDs in response to loading of cells with lipids. Evidence showing that in addition to physical contact, mitochondria and LDs exhibit metabolic interactions is presented and discussed. A hypothetical model of channeled lipid utilization by mitochondria is proposed. Direct delivery and channeled processing of lipids in mitochondria could represent a reliable and efficient way to maintain reactive oxygen species (ROS) within levels compatible with signaling while ensuring robust and reliable energy supply.
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Affiliation(s)
- Miguel A Aon
- Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine Baltimore, MD, USA
| | - Niraj Bhatt
- Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine Baltimore, MD, USA
| | - Sonia C Cortassa
- Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine Baltimore, MD, USA
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17
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Cooper AN, Brown JCL, Staples JF. Are long chain acyl CoAs responsible for suppression of mitochondrial metabolism in hibernating 13-lined ground squirrels? Comp Biochem Physiol B Biochem Mol Biol 2014; 170:50-7. [PMID: 24561259 DOI: 10.1016/j.cbpb.2014.02.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Revised: 02/11/2014] [Accepted: 02/13/2014] [Indexed: 11/18/2022]
Abstract
Hibernation in 13-lined ground squirrels (Ictidomys tridecemlineatus) is associated with a substantial suppression of whole-animal metabolism. We compared the metabolism of liver mitochondria isolated from torpid ground squirrels with those from interbout euthermic (IBE; recently aroused from torpor) and summer euthermic conspecifics. Succinate-fuelled state 3 respiration, calculated relative to mitochondrial protein, was suppressed in torpor by 48% and 44% compared with IBE and summer, respectively. This suppression remains when respiration is expressed relative to cytochrome c oxidase activity. We hypothesized that this suppression was caused by inhibition of succinate transport at the dicarboxylate transporter (DCT) by long-chain fatty acyl CoAs that may accumulate during torpor. We predicted, therefore, that exogenous palmitoyl CoA would inhibit respiration in IBE more than in torpor. Palmitoyl CoA inhibited respiration ~70%, in both torpor and IBE. The addition of carnitine, predicted to reverse palmitoyl CoA suppression by facilitating its transport into the mitochondrial matrix, did not rescue the respiration rates in IBE or torpor. Liver mitochondrial activities of carnitine palmitoyl transferase did not differ among IBE, torpor and summer animals. Although palmitoyl CoA inhibits succinate-fuelled respiration, this suppression is likely not related exclusively to inhibition of the DCT, and may involve additional mitochondrial transporters such as the adenine-nucleotide transporter.
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Affiliation(s)
- Alex N Cooper
- Department of Biology, University of Western Ontario, London, ON N6A5B8, Canada
| | - Jason C L Brown
- Department of Biology, University of Western Ontario, London, ON N6A5B8, Canada
| | - James F Staples
- Department of Biology, University of Western Ontario, London, ON N6A5B8, Canada.
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18
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Sharma S, Aramburo A, Rafikov R, Sun X, Kumar S, Oishi PE, Datar SA, Raff G, Xoinis K, Kalkan G, Fratz S, Fineman JR, Black SM. L-carnitine preserves endothelial function in a lamb model of increased pulmonary blood flow. Pediatr Res 2013; 74:39-47. [PMID: 23628882 PMCID: PMC3709010 DOI: 10.1038/pr.2013.71] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Accepted: 02/01/2013] [Indexed: 12/30/2022]
Abstract
BACKGROUND In our model of a congenital heart defect (CHD) with increased pulmonary blood flow (PBF; shunt), we have recently shown a disruption in carnitine homeostasis, associated with mitochondrial dysfunction and decreased endothelial nitric oxide synthase (eNOS)/heat shock protein (Hsp)90 interactions that contribute to eNOS uncoupling, increased superoxide levels, and decreased bioavailable nitric oxide (NO). Therefore, we undertook this study to test the hypothesis that L-carnitine therapy would maintain mitochondrial function and NO signaling. METHODS Thirteen fetal lambs underwent in utero placement of an aortopulmonary graft. Immediately after delivery, lambs received daily treatment with oral L-carnitine or its vehicle. RESULTS L-Carnitine-treated lambs had decreased levels of acylcarnitine and a reduced acylcarnitine:free carnitine ratio as compared with vehicle-treated shunt lambs. These changes correlated with increased carnitine acetyl transferase (CrAT) protein and enzyme activity and decreased levels of nitrated CrAT. The lactate:pyruvate ratio was also decreased in L-carnitine-treated lambs. Hsp70 protein levels were significantly decreased, and this correlated with increases in eNOS/Hsp90 interactions, NOS activity, and NOx levels, and a significant decrease in eNOS-derived superoxide. Furthermore, acetylcholine significantly decreased left pulmonary vascular resistance only in L-carnitine-treated lambs. CONCLUSION L-Carnitine therapy may improve the endothelial dysfunction noted in children with CHDs and has important clinical implications that warrant further investigation.
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Affiliation(s)
- Shruti Sharma
- Pulmonary Vascular Disease Program, Vascular Biology Center, Georgia Health Sciences University, Augusta GA 30912
| | - Angela Aramburo
- Department of Pediatrics, University of California, San Francisco CA,Department of Pediatrics, University Autonomous Barcelona, Spain
| | - Ruslan Rafikov
- Pulmonary Vascular Disease Program, Vascular Biology Center, Georgia Health Sciences University, Augusta GA 30912
| | - Xutong Sun
- Pulmonary Vascular Disease Program, Vascular Biology Center, Georgia Health Sciences University, Augusta GA 30912
| | - Sanjiv Kumar
- Pulmonary Vascular Disease Program, Vascular Biology Center, Georgia Health Sciences University, Augusta GA 30912
| | - Peter E. Oishi
- Department of Pediatrics, University of California, San Francisco CA,Cardiovascular Research Institute, University of California, San Francisco CA
| | - Sanjeev A. Datar
- Department of Pediatrics, University of California, San Francisco CA
| | - Gary Raff
- Department of Cardiothoracic Surgery, University of California, Davis CA
| | - Kon Xoinis
- Department of Pediatrics, University of California, San Francisco CA
| | - Gohkan Kalkan
- Department of Pediatrics, University of California, San Francisco CA
| | - Sohrab Fratz
- Department of Pediatric Cardiology and Congenital Heart Disease, Deutsches Herzzentrum München, Klinik an der Technischen Universität München, Lazarettstrasse 36, 80636 Munich, Germany
| | - Jeffrey R. Fineman
- Department of Pediatrics, University of California, San Francisco CA,Cardiovascular Research Institute, University of California, San Francisco CA
| | - Stephen M. Black
- Pulmonary Vascular Disease Program, Vascular Biology Center, Georgia Health Sciences University, Augusta GA 30912
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19
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Morota S, Manolopoulos T, Eyjolfsson A, Kimblad PO, Wierup P, Metzsch C, Blomquist S, Hansson MJ. Functional and pharmacological characteristics of permeability transition in isolated human heart mitochondria. PLoS One 2013; 8:e67747. [PMID: 23840770 PMCID: PMC3695980 DOI: 10.1371/journal.pone.0067747] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Accepted: 05/22/2013] [Indexed: 11/18/2022] Open
Abstract
The objective of the present study was to validate the presence and explore the characteristics of mitochondrial permeability transition (mPT) in isolated mitochondria from human heart tissue in order to investigate if previous findings in animal models of cardiac disorders are translatable to human disease. Mitochondria were rapidly isolated from fresh atrial tissue samples obtained from 14 patients undergoing Maze surgery due to atrial fibrillation. Human heart mitochondria exhibited typical mPT characteristics upon calcium overload such as swelling, evaluated by changes in light scattering, inhibition of respiration and loss of respiratory coupling. Swelling was a morphologically reversible event following transient calcium challenge. Calcium retention capacity (CRC), a quantitative measure of mPT sensitivity assayed by following extramitochondrial [Ca(2+)] and changes in respiration during a continuous calcium infusion, was significantly increased by cyclophilin D (CypD) inhibitors. The thiol-reactive oxidant phenylarsine oxide sensitized mitochondria to calcium-induced mPT. Release of the pro-apoptotic intermembrane protein cytochrome c was increased after, but not before, calcium discharge and respiratory inhibition in the CRC assay. From the present study, we conclude that adult viable heart mitochondria have a CypD- and oxidant-regulated mPT. The findings support that inhibition of mPT may be a relevant pharmacological target in human cardiac disease and may underlie the beneficial effect of cyclosporin A in reperfusion injury.
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Affiliation(s)
- Saori Morota
- Mitochondrial Pathophysiology Unit, Skåne University Hospital & Lund University, Lund, Sweden
| | - Theodor Manolopoulos
- Department of Cardiothoracic Anesthesiology and Intensive Care, Skåne University Hospital & Lund University, Lund, Sweden
| | - Atli Eyjolfsson
- Department of Cardiothoracic Surgery, Skåne University Hospital & Lund University, Lund, Sweden
| | - Per-Ola Kimblad
- Department of Cardiothoracic Surgery, Skåne University Hospital & Lund University, Lund, Sweden
| | - Per Wierup
- Department of Cardiothoracic Surgery, Skåne University Hospital & Lund University, Lund, Sweden
| | - Carsten Metzsch
- Department of Cardiothoracic Anesthesiology and Intensive Care, Skåne University Hospital & Lund University, Lund, Sweden
| | - Sten Blomquist
- Department of Cardiothoracic Anesthesiology and Intensive Care, Skåne University Hospital & Lund University, Lund, Sweden
| | - Magnus J. Hansson
- Mitochondrial Pathophysiology Unit, Skåne University Hospital & Lund University, Lund, Sweden
- Department of Clinical Physiology, Skåne University Hospital & Lund University, Lund, Sweden
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20
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Chung DJ, Szyszka B, Brown JCL, Hüner NPA, Staples JF. Changes in the mitochondrial phosphoproteome during mammalian hibernation. Physiol Genomics 2013; 45:389-99. [PMID: 23572536 DOI: 10.1152/physiolgenomics.00171.2012] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Mammalian hibernation involves periods of substantial suppression of metabolic rate (torpor) allowing energy conservation during winter. In thirteen-lined ground squirrels (Ictidomys tridecemlineatus), suppression of liver mitochondrial respiration during entrance into torpor occurs rapidly (within 2 h) before core body temperature falls below 30°C, whereas reversal of this suppression occurs slowly during arousal from torpor. We hypothesized that this pattern of rapid suppression in entrance and slow reversal during arousal was related to changes in the phosphorylation state of mitochondrial enzymes during torpor catalyzed by temperature-dependent kinases and phosphatases. We compared mitochondrial protein phosphorylation among hibernation metabolic states using immunoblot analyses and assessed how phosphorylation related to mitochondrial respiration rates. No proteins showed torpor-specific changes in phosphorylation, nor did phosphorylation state correlate with mitochondrial respiration. However, several proteins showed seasonal (summer vs. winter) differences in phosphorylation of threonine or serine residues. Using matrix-assisted laser desorption/ionization-time of flight/time of flight mass spectrometry, we identified three of these proteins: F1-ATPase α-chain, long chain-specific acyl-CoA dehydrogenase, and ornithine transcarbamylase. Therefore, we conclude that protein phosphorylation is likely a mechanism involved in bringing about seasonal changes in mitochondrial metabolism in hibernating ground squirrels, but it seems unlikely to play any role in acute suppression of mitochondrial metabolism during torpor.
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Affiliation(s)
- Dillon J Chung
- Department of Biology, University of Western Ontario, London, Ontario, Canada.
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21
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Role of carnitine acetyl transferase in regulation of nitric oxide signaling in pulmonary arterial endothelial cells. Int J Mol Sci 2012; 14:255-72. [PMID: 23344032 PMCID: PMC3565262 DOI: 10.3390/ijms14010255] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Revised: 11/26/2012] [Accepted: 11/30/2012] [Indexed: 12/16/2022] Open
Abstract
Congenital heart defects with increased pulmonary blood flow (PBF) result in pulmonary endothelial dysfunction that is dependent, at least in part, on decreases in nitric oxide (NO) signaling. Utilizing a lamb model with left-to-right shunting of blood and increased PBF that mimics the human disease, we have recently shown that a disruption in carnitine homeostasis, due to a decreased carnitine acetyl transferase (CrAT) activity, correlates with decreased bioavailable NO. Thus, we undertook this study to test the hypothesis that the CrAT enzyme plays a major role in regulating NO signaling through its effect on mitochondrial function. We utilized the siRNA gene knockdown approach to mimic the effect of decreased CrAT activity in pulmonary arterial endothelial cells (PAEC). Our data indicate that silencing the CrAT gene disrupted cellular carnitine homeostasis, reduced the expression of mitochondrial superoxide dismutase-and resulted in an increase in oxidative stress within the mitochondrion. CrAT gene silencing also disrupted mitochondrial bioenergetics resulting in reduced ATP generation and decreased NO signaling secondary to a reduction in eNOS/Hsp90 interactions. Thus, this study links the disruption of carnitine homeostasis to the loss of NO signaling observed in children with CHD. Preserving carnitine homeostasis may have important clinical implications that warrant further investigation.
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22
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Kim YJ, Kim SY, Sung DK, Chang YS, Park WS. Neuroprotective effects of L-carnitine against oxygen-glucose deprivation in rat primary cortical neurons. KOREAN JOURNAL OF PEDIATRICS 2012; 55:238-48. [PMID: 22844318 PMCID: PMC3405156 DOI: 10.3345/kjp.2012.55.7.238] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/01/2011] [Revised: 02/15/2012] [Accepted: 03/20/2012] [Indexed: 01/29/2023]
Abstract
Purpose Hypoxic-ischemic encephalopathy is an important cause of neonatal mortality, as this brain injury disrupts normal mitochondrial respiratory activity. Carnitine plays an essential role in mitochondrial fatty acid transport and modulates excess acyl coenzyme A levels. In this study, we investigated whether treatment of primary cultures of rat cortical neurons with L-carnitine was able to prevent neurotoxicity resulting from oxygen-glucose deprivation (OGD). Methods Cortical neurons were prepared from Sprague-Dawley rat embryos. L-Carnitine was applied to cultures just prior to OGD and subsequent reoxygenation. The numbers of cells that stained with acridine orange (AO) and propidium iodide (PI) were counted, and lactate dehydrogenase (LDH) activity and reactive oxygen species (ROS) levels were measured. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and the terminal uridine deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling assay were performed to evaluate the effect of L-carnitine (1 µM, 10 µM, and 100 µM) on OGD-induced neurotoxicity. Results Treatment of primary cultures of rat cortical neurons with L-carnitine significantly reduced cell necrosis and prevented apoptosis after OGD. L-Carnitine application significantly reduced the number of cells that died, as assessed by the PI/AO ratio, and also reduced ROS release in the OGD groups treated with 10 µM and 100 µM of L-carnitine compared with the untreated OGD group (P<0.05). The application of L-carnitine at 100 µM significantly decreased cytotoxicity, LDH release, and inhibited apoptosis compared to the untreated OGD group (P<0.05). Conclusion L-Carnitine has neuroprotective benefits against OGD in rat primary cortical neurons in vitro.
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Affiliation(s)
- Yu Jin Kim
- Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
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Mei S, Gu H, Yang X, Guo H, Liu Z, Cao W. Prolonged exposure to insulin induces mitochondrion-derived oxidative stress through increasing mitochondrial cholesterol content in hepatocytes. Endocrinology 2012; 153:2120-9. [PMID: 22374974 PMCID: PMC3339654 DOI: 10.1210/en.2011-2119] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
We addressed the link between excessive exposure to insulin and mitochondrion-derived oxidative stress in this study and found that prolonged exposure to insulin increased mitochondrial cholesterol in cultured hepatocytes and in mice and stimulated production of reactive oxygen species (ROS) and decreased the reduced glutathione to glutathione disulfide ratio in cultured hepatocytes. Exposure of isolated hepatic mitochondria to cholesterol alone promoted ROS emission. The oxidative stress induced by the prolonged exposure to insulin was prevented by inhibition of cholesterol synthesis with simvastatin. We further found that prolonged exposure to insulin decreased mitochondrial membrane potential and the increased ROS production came from mitochondrial respiration complex I. Finally, we observed that prolonged exposure to insulin decreased mitochondrial membrane fluidity in a cholesterol synthesis-dependent manner. Together our results demonstrate that excess exposure to insulin causes mitochondrion-derived oxidative stress through cholesterol synthesis in hepatocytes.
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Affiliation(s)
- Shuang Mei
- Department of Nutrition, Gillings School of Global Public Health, The University of North Carolina at Chapel Hill, North Carolina 27559, USA
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Perez E, Chu J, Bania T, Medlej K. L-carnitine increases survival in a murine model of severe verapamil toxicity. Acad Emerg Med 2012; 18:1135-40. [PMID: 22092894 DOI: 10.1111/j.1553-2712.2011.01217.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
OBJECTIVES L-carnitine is an essential compound involved in cellular energy production through free fatty acid metabolism. It has been theorized that severe verapamil toxicity "shifts" heart energy production away from free fatty acids and toward other sources, contributing to profound cardiogenic shock. The primary study objective was to determine whether intravenous (IV) L-carnitine affects survival in severe verapamil toxicity. Secondary objectives were to determine the effects on hemodynamic parameters. The authors hypothesized that IV L-carnitine would increase both survival and hemodynamic parameters in severe verapamil toxicity. METHODS This was a controlled, blinded animal investigation. Sixteen male rats were anesthetized, ventilated, and instrumented to record mean arterial pressure (MAP) and heart rate. Verapamil toxicity was achieved by a constant infusion of 5 mg/kg/hr. After 5 minutes a bolus of 50 mg/kg of either L-carnitine or normal saline was given. The experiment concluded when either 10% of baseline MAP was achieved or 150 minutes had elapsed. The data were analyzed using Kaplan-Meier analysis, log rank test, and analysis of variance. RESULTS The median survival for the animals in the L-carnitine group was 140.75 minutes (interquartile range [IQR] = 98.6 to 150 minutes), and for those in the normal saline group it was 49.19 minutes (IQR = 39.02 to 70.97 minutes; p = 0.0001). At 15 minutes the MAP was 20.45 mm Hg greater in the animals in the L-carnitine group than in the animals in the normal saline group (95% confidence interval [CI] = 0.25 to 40.65; p = 0.047). CONCLUSIONS When compared with saline, IV L-carnitine increases survival and MAP in a murine model of severe verapamil toxicity.
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Affiliation(s)
- Eric Perez
- Department of Emergency Medicine, St Luke's/Roosevelt Hospital, New York, NY, USA.
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Ning J, Hong T, Yang X, Mei S, Liu Z, Liu HY, Cao W. Insulin and insulin signaling play a critical role in fat induction of insulin resistance in mouse. Am J Physiol Endocrinol Metab 2011; 301:E391-401. [PMID: 21586696 PMCID: PMC3154527 DOI: 10.1152/ajpendo.00164.2011] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The primary player that induces insulin resistance has not been established. Here, we studied whether or not fat can cause insulin resistance in the presence of insulin deficiency. Our results showed that high-fat diet (HFD) induced insulin resistance in C57BL/6 (B6) mice. The HFD-induced insulin resistance was prevented largely by the streptozotocin (STZ)-induced moderate insulin deficiency. The STZ-induced insulin deficiency prevented the HFD-induced ectopic fat accumulation and oxidative stress in liver and gastrocnemius. The STZ-induced insulin deficiency prevented the HFD- or insulin-induced increase in hepatic expression of long-chain acyl-CoA synthetases (ACSL), which are necessary for fatty acid activation. HFD increased mitochondrial contents of long-chain acyl-CoAs, whereas it decreased mitochondrial ADP/ATP ratio, and these HFD-induced changes were prevented by the STZ-induced insulin deficiency. In cultured hepatocytes, we observed that expressions of ACSL1 and -5 were stimulated by insulin signaling. Results in cultured cells also showed that blunting insulin signaling by the PI3K inhibitor LY-294002 prevented fat accumulation, oxidative stress, and insulin resistance induced by the prolonged exposure to either insulin or oleate plus sera that normally contain insulin. Finally, knockdown of the insulin receptor prevented the oxidative stress and insulin resistance induced by the prolonged exposure to insulin or oleate plus sera. Together, our results show that insulin and insulin signaling are required for fat induction of insulin resistance in mice and cultured mouse hepatocytes.
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Affiliation(s)
- Jie Ning
- Department of Nutrition, Gillings School of Global Public Health, University of North Carolina at Chapel Hill,Chapel Hill, NC 27559, USA
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Benhabbouche S, Crola da silva C, Abrial M, Ferrera R. Base des phénomènes d’ischémie reperfusion et de la protection myocardique. ACTA ACUST UNITED AC 2011; 30 Suppl 1:S2-16. [DOI: 10.1016/s0750-7658(11)70002-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Zolkipli Z, Pedersen CB, Lamhonwah AM, Gregersen N, Tein I. Vulnerability to oxidative stress in vitro in pathophysiology of mitochondrial short-chain acyl-CoA dehydrogenase deficiency: response to antioxidants. PLoS One 2011; 6:e17534. [PMID: 21483766 PMCID: PMC3069965 DOI: 10.1371/journal.pone.0017534] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2010] [Accepted: 02/07/2011] [Indexed: 12/14/2022] Open
Abstract
Objective To elucidate the pathophysiology of SCAD deficient patients who have a
unique neurological phenotype, among fatty acid oxidation disorders, with
early developmental delay, CNS malformations, intractable seizures, myopathy
and clinical signs suggesting oxidative stress. Methods We studied skin fibroblast cultures from patients homozygous for ACADS
common variant c.625G>A (n = 10), compound heterozygous
for c.625G>A/c.319C>T (n = 3) or homozygous for
pathogenic c.319C>T (n = 2) and c.1138C>T (n = 2)
mutations compared to fibroblasts from patients with carnitine palmitoyltransferase
2 (CPT2) (n = 5), mitochondrial trifunctional protein
(MTP)/long-chain L-3-hydroxyacyl-CoA dehydrogenase (LCHAD) (n = 7),
and medium-chain acyl-CoA dehydrogenase (MCAD) deficiencies (n = 4)
and normal controls (n = 9). All were exposed to 50 µM
menadione at 37°C. Additonal conditions included exposure to 39°C
and/or hypoglycemia. Time to 100% cell death was confirmed with trypan
blue dye exclusion. Experiments were repeated with antioxidants (Vitamins
C and E or N-acetylcysteine), Bezafibrate or glucose and temperature rescue. Results The most significant risk factor for vulnerability to menadione-induced
oxidative stress was the presence of a FAO defect. SCADD fibroblasts were
the most vulnerable compared to other FAO disorders and controls, and were
similarly affected, independent of genotype. Cell death was exacerbated by
hyperthermia and/or hypoglycemia. Hyperthermia was a more significant independent
risk factor than hypoglycemia. Rescue significantly prolonged survival. Incubation
with antioxidants and Bezafibrate significantly increased viability of SCADD
fibroblasts. Interpretation Vulnerability to oxidative stress likely contributes to neurotoxicity of
SCADD regardless of ACADS genotype and is significantly exacerbated
by hyperthermia. We recommend rigorous temperature control in SCADD patients
during acute illness. Antioxidants and Bezafibrate may also prove instrumental
in their management.
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Affiliation(s)
- Zarazuela Zolkipli
- Neurometabolic Research Laboratory, Division of Neurology, Department of Pediatrics, Hospital for Sick Children, Toronto, Canada
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Kim M, Song E. Effects of ATP and ADP on iron uptake in rat heart mitochondria. Anim Cells Syst (Seoul) 2010. [DOI: 10.1080/19768354.2010.525836] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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Kim M, Song E. Temporal changes in mitochondrial activities of rat heart after a single injection of iron, including increased complex II activity. Anim Cells Syst (Seoul) 2010. [DOI: 10.1080/19768354.2010.486936] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
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Liu HY, Cao SY, Hong T, Han J, Liu Z, Cao W. Insulin is a stronger inducer of insulin resistance than hyperglycemia in mice with type 1 diabetes mellitus (T1DM). J Biol Chem 2009; 284:27090-100. [PMID: 19654321 PMCID: PMC2785638 DOI: 10.1074/jbc.m109.016675] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2009] [Revised: 07/22/2009] [Indexed: 12/13/2022] Open
Abstract
Subjects with type 1 diabetes mellitus (T1DM) eventually develop insulin resistance and other features of T2DM such as cardiovascular disorders. The exact mechanism has been not been completely understood. In this study, we tested the hypothesis that excessive or inappropriate exposure to insulin is a primary mediator of insulin resistance in T1DM. We found that continuous exposure of mice with non-obese diabetes to insulin detemir, which is similar to some current conventional treatment of human T1DM, induced severe insulin resistance, whereas untreated hyperglycemia for the same amount of time (2 weeks) did not cause obvious insulin resistance. Insulin resistance was accompanied by decreased mitochondrial production as evaluated by mitochondrial DNA and levels of transcripts and proteins of mitochondrion-associated genes, increased ectopic fat accumulation in liver and skeletal muscle (gastrocnemius) evaluated by measurements of triglyceride content, and elevated oxidative stress detected by the GSH/GSSG ratio. Prolonged exposure of cultured hepatocytes to insulin induced significant insulin resistance, whereas the same length of exposure to a high level of glucose (33 mm) did not cause obvious insulin resistance. Furthermore, our results showed that prolonged exposure to insulin caused oxidative stress, and blockade of mitochondrion-derived oxidative stress by overexpression of manganese-superoxide dismutase prevented insulin resistance induced by the prolonged exposure to insulin. Together, our results show that excessive exposure to insulin is a primary inducer of insulin resistance in T1DM in mice.
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Affiliation(s)
- Hui-Yu Liu
- From the Division of Translational Biology, The Hamner Institutes for Health Sciences, Research Triangle Park, North Carolina 27709
| | - Sophia Y. Cao
- From the Division of Translational Biology, The Hamner Institutes for Health Sciences, Research Triangle Park, North Carolina 27709
| | - Tao Hong
- From the Division of Translational Biology, The Hamner Institutes for Health Sciences, Research Triangle Park, North Carolina 27709
| | - Jianmin Han
- From the Division of Translational Biology, The Hamner Institutes for Health Sciences, Research Triangle Park, North Carolina 27709
| | - Zhenqi Liu
- Department of Medicine (Endocrinology), University of Virginia Medical Science Center, Charlottesville, Virginia 22908, and
| | - Wenhong Cao
- From the Division of Translational Biology, The Hamner Institutes for Health Sciences, Research Triangle Park, North Carolina 27709
- Department of Internal Medicine (Endocrinology), Duke University Medical System, Durham, North Carolina 27705
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Liu HY, Hong T, Wen GB, Han J, Zuo D, Liu Z, Cao W. Increased basal level of Akt-dependent insulin signaling may be responsible for the development of insulin resistance. Am J Physiol Endocrinol Metab 2009; 297:E898-906. [PMID: 19638508 PMCID: PMC2763787 DOI: 10.1152/ajpendo.00374.2009] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
A majority of subjects with insulin resistance and hyperinsulinemia can maintain their blood glucose levels normal for the whole life presumably through protein kinase B (Akt)-dependent insulin signaling. In this study, we found that the basal Akt phosphorylation level was increased in liver and gastrocnemius of mice under the high-fat diet (HFD). Levels of mitochondrial DNA and expression of some mitochondrion-associated genes were decreased by the HFD primarily in liver. Triglyceride content was increased in both liver and gastrocnemius by the HFD. Oxidative stress was induced by the HFD in both liver and gastrocnemius. Insulin sensitivity was decreased by the HFD. All of these changes were largely or completely reversed by treatment of animals with the phosphatidylinositol 3-kinase inhibitor LY-294002 during the time when animals usually do not eat. Consequently, the overall insulin sensitivity was increased by treatment with LY-294002. Together, our results indicate that increased basal Akt-dependent insulin signaling suppresses mitochondrial production, increases ectopic fat accumulation, induces oxidative stress, and desensitizes insulin signaling in subjects with insulin resistance and hyperinsulinemia.
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Affiliation(s)
- Hui-Yu Liu
- Division of Translational Biology, The Hamner Institutes for Health Sciences, Research Triangle Park, NC 27709, USA
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Zorov DB, Juhaszova M, Yaniv Y, Nuss HB, Wang S, Sollott SJ. Regulation and pharmacology of the mitochondrial permeability transition pore. Cardiovasc Res 2009; 83:213-25. [PMID: 19447775 PMCID: PMC2701724 DOI: 10.1093/cvr/cvp151] [Citation(s) in RCA: 185] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/14/2009] [Revised: 05/04/2009] [Accepted: 05/10/2009] [Indexed: 12/18/2022] Open
Abstract
The 'mitochondrial permeability transition', characterized by a sudden induced change of the inner mitochondrial membrane permeability for water as well as for small substances (=1.5 kDa), has been known for three decades. Research interest in the entity responsible for this phenomenon, the 'mitochondrial permeability transition pore' (mPTP), has dramatically increased after demonstration that it plays a key role in the life and death decision in cells. Therefore, a better understanding of this phenomenon and its regulation by environmental stresses, kinase signalling, and pharmacological intervention is vital. The characterization of the molecular identity of the mPTP will allow identification of possible pharmacological targets and assist in drug design for its precise regulation. However, despite extensive research efforts, at this point the pore-forming core component(s) of the mPTP remain unidentified. Pivotal new genetic evidence has shown that components once believed to be core elements of the mPTP (namely mitochondrial adenine nucleotide translocator and cyclophilin D) are instead only mPTP regulators (or in the case of voltage-dependent anion channels, probably entirely dispensable). This review provides an update on the current state of knowledge regarding the regulation of the mPTP.
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Affiliation(s)
| | | | | | | | | | - Steven J. Sollott
- Laboratory of Cardiovascular Science, Gerontology Research Center, Box 13, Intramural Research Program, National Institute on Aging, NIH, 5600 Nathan Shock Drive, Baltimore, MD 21224-6825, USA
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Kim M, Hong M, Song E. Changes in cytochrome c oxidase and NO in rat lung mitochondria following iron overload. Anim Cells Syst (Seoul) 2009. [DOI: 10.1080/19768354.2009.9647200] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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Berezhnov AV, Fedotova EI, Nenov MN, Kokoz YM, Zinchenko VP, Dynnik VV. Destabilization of the cytosolic calcium level and the death of cardiomyocytes in the presence of derivatives of long-chain fatty acids. Biophysics (Nagoya-shi) 2008. [DOI: 10.1134/s0006350908060183] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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35
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Schönfeld P, Wojtczak L. Fatty acids as modulators of the cellular production of reactive oxygen species. Free Radic Biol Med 2008; 45:231-41. [PMID: 18482593 DOI: 10.1016/j.freeradbiomed.2008.04.029] [Citation(s) in RCA: 308] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2008] [Revised: 04/16/2008] [Accepted: 04/22/2008] [Indexed: 12/17/2022]
Abstract
Long-chain nonesterified ("free") fatty acids (FFA) and some of their derivatives and metabolites can modify intracellular production of reactive oxygen species (ROS), in particular O(2)(-) and H(2)O(2). In mitochondria, FFA exert a dual effect on ROS production. Because of slowing down the rate of electron flow through Complexes I and III of the respiratory chain due to interaction within the complex subunit structure, and between Complexes III and IV due to release of cytochrome c from the inner membrane, FFA increase the rate of ROS generation in the forward mode of electron transport. On the other hand, due to their protonophoric action on the inner mitochondrial membrane ("mild uncoupling effect"), FFA strongly decrease ROS generation in the reverse mode of electron transport. In the plasma membrane of phagocytic neutrophils and a number of other types of cells, polyunsaturated FFA stimulate O(2)(-) generation by NADPH oxidase. These effects of FFA can modulate signaling functions of ROS and be, at least partly, responsible for their proapoptotic effects in several types of cells.
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Affiliation(s)
- Peter Schönfeld
- Institute of Biochemistry and Cell Biology, Otto von Guericke University, Leipziger Str. 44, 39120 Magdeburg, Germany.
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Klingenberg M. The ADP and ATP transport in mitochondria and its carrier. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2008; 1778:1978-2021. [PMID: 18510943 DOI: 10.1016/j.bbamem.2008.04.011] [Citation(s) in RCA: 452] [Impact Index Per Article: 28.3] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 10/04/2007] [Revised: 04/24/2008] [Accepted: 04/24/2008] [Indexed: 10/22/2022]
Abstract
Different from some more specialised short reviews, here a general although not encyclopaedic survey of the function, metabolic role, structure and mechanism of the ADP/ATP transport in mitochondria is presented. The obvious need for an "old fashioned" review comes from the gateway role in metabolism of the ATP transfer to the cytosol from mitochondria. Amidst the labours, 40 or more years ago, of unravelling the role of mitochondrial compartments and of the two membranes, the sequence of steps of how ATP arrives in the cytosol became a major issue. When the dust settled, a picture emerged where ATP is exported across the inner membrane in a 1:1 exchange against ADP and where the selection of ATP versus ADP is controlled by the high membrane potential at the inner membrane, thus uplifting the free energy of ATP in the cytosol over the mitochondrial matrix. Thus the disparate energy and redox states of the two major compartments are bridged by two membrane potential responsive carriers to enable their symbiosis in the eukaryotic cell. The advance to the molecular level by studying the binding of nucleotides and inhibitors was facilitated by the high level of carrier (AAC) binding sites in the mitochondrial membrane. A striking flexibility of nucleotide binding uncovered the reorientation of carrier sites between outer and inner face, assisted by the side specific high affinity inhibitors. The evidence of a single carrier site versus separate sites for substrate and inhibitors was expounded. In an ideal setting principles of transport catalysis were elucidated. The isolation of intact AAC as a first for any transporter enabled the reconstitution of transport for unravelling, independently of mitochondrial complications, the factors controlling the ADP/ATP exchange. Electrical currents measured with the reconstituted AAC demonstrated electrogenic translocation and charge shift of reorienting carrier sites. Aberrant or vital para-functions of AAC in basal uncoupling and in the mitochondrial pore transition were demonstrated in mitochondria and by patch clamp with reconstituted AAC. The first amino acid sequence of AAC and of any eukaryotic carrier furnished a 6-transmembrane helix folding model, and was the basis for mapping the structure by access studies with various probes, and for demonstrating the strong conformation changes demanded by the reorientation mechanism. Mutations served to elucidate the function of residues, including the particular sensitivity of ATP versus ADP transport to deletion of critical positive charge in AAC. After resisting for decades, at last the atomic crystal structure of the stabilised CAT-AAC complex emerged supporting the predicted principle fold of the AAC but showing unexpected features relevant to mechanism. Being a snapshot of an extreme abortive "c-state" the actual mechanism still remains a conjecture.
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Abstract
Obesity and the related metabolic syndrome have become a worldwide epidemic. Inactivity appears to be a primary causative factor in the pathogenesis of this obesity and metabolic syndrome. There are two possible, perhaps not mutually exclusive, events that may lead to intramyocellular lipid accumulation and mitochondrial dysfunction in patients with obesity. First, obesity, with high intake-associated lipid accumulation in muscle may interfere with cellular mitochondrial function through generation of reactive oxygen species leading to lipid membrane peroxidative injury and disruption of mitochondrial membrane-dependent enzymes. This in turn leads to impaired oxidative metabolism. Secondly, a primary defect in mitochondrial oxidative metabolism may be responsible for a reduction in fatty acid oxidation leading to intramyocellular lipid accumulation as a secondary event. Non-invasive techniques such as proton (1H) and phosphorus (31P) magnetic resonance spectroscopy, coupled with specific magnetic resonance imaging techniques, may facilitate the investigation of the effects of various ergometric interventions on the pathophysiology of obesity and the metabolic syndrome. Exercise has positive effects on glucose metabolism, aerobic metabolism, mitochondrial density, and respiratory chain proteins in patients with metabolic syndrome, and we propose that this may be due to the exercise effects on AMP kinase, and a prospective physiological mechanism for this benefit is presented. A physiological model of the effect of intramyocellular lipid accumulation on oxidative metabolism and insulin mediated glucose uptake is proposed.
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Sharma S, Sud N, Wiseman DA, Carter AL, Kumar S, Hou Y, Rau T, Wilham J, Harmon C, Oishi P, Fineman JR, Black SM. Altered carnitine homeostasis is associated with decreased mitochondrial function and altered nitric oxide signaling in lambs with pulmonary hypertension. Am J Physiol Lung Cell Mol Physiol 2007; 294:L46-56. [PMID: 18024721 DOI: 10.1152/ajplung.00247.2007] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Utilizing aortopulmonary vascular graft placement in the fetal lamb, we have developed a model (shunt) of pulmonary hypertension that mimics congenital heart disease with increased pulmonary blood flow. Our previous studies have identified a progressive development of endothelial dysfunction in shunt lambs that is dependent, at least in part, on decreased nitric oxide (NO) signaling. The purpose of this study was to evaluate the possible role of a disruption in carnitine metabolism in shunt lambs and to determine the effect on NO signaling. Our data indicate that at 2 wk of age, shunt lambs have significantly reduced expression (P < 0.05) of the key enzymes in carnitine metabolism: carnitine palmitoyltransferases 1 and 2 as well as carnitine acetyltransferase (CrAT). In addition, we found that CrAT activity was inhibited due to increased nitration. Furthermore, free carnitine levels were significantly decreased whereas acylcarnitine levels were significantly higher in shunt lambs (P < 0.05). We also found that alterations in carnitine metabolism resulted in mitochondrial dysfunction, since shunt lambs had significantly decreased pyruvate, increased lactate, and a reduced pyruvate/lactate ratio. In pulmonary arterial endothelial cells cultured from juvenile lambs, we found that mild uncoupling of the mitochondria led to a decrease in cellular ATP levels and a reduction in both endothelial NO synthase-heat shock protein 90 (eNOS-HSP90) interactions and NO signaling. Similarly, in shunt lambs we found a loss of eNOS-HSP90 interactions that correlated with a progressive decrease in NO signaling. Our data suggest that mitochondrial dysfunction may play a role in the development of endothelial dysfunction and pulmonary hypertension and increased pulmonary blood flow.
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Affiliation(s)
- Shruti Sharma
- Program in Pulmonary Disease, Vascular Biology Center, Medical College of Georgia, Augusta, GA 30912, USA
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Ventura FV, Tavares de Almeida I, Wanders RJA. Inhibition of adenine nucleotide transport in rat liver mitochondria by long-chain acyl-coenzyme A beta-oxidation intermediates. Biochem Biophys Res Commun 2006; 352:873-8. [PMID: 17157818 DOI: 10.1016/j.bbrc.2006.11.109] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2006] [Accepted: 11/17/2006] [Indexed: 11/17/2022]
Abstract
Long-chain acyl-coenzyme A esters (LCAC), which may accumulate under different pathological conditions and especially in patients with a mitochondrial fatty acid beta-oxidation defect, have long been known as potent inhibitors of several enzymes in multiple metabolic pathways, particularly the oxidative phosphorylation system (OXPHOS). To shed more light on the inhibitory mechanisms of acyl-CoA esters upon energy metabolism, the effect of palmitoyl-CoA and its beta-oxidation intermediates on OXPHOS was studied. We have recently shown that, using rat liver mitochondria, LCAC inhibit l-glutamate driven oxygen consumption in the presence of ADP whereas no effect is found when an uncoupler is used to stimulate respiration maximally. A similar inhibitory effect of these compounds is now reported upon the distribution of ATP for intra- and extra-mitochondrial utilization. Taken together these data strongly suggest that the inhibition of ADP-induced respiration with l-glutamate as substrate by LCAC is primarily due to inhibition of the mitochondrial ADP/ATP carrier.
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Affiliation(s)
- Fátima V Ventura
- Centro de Patogénese Molecular - Unidade de Biologia Molecular e Biopatologia Experimental, Faculdade de Farmácia, Universidade de Lisboa, Lisboa, Portugal.
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Bârzu O. Measurement of oxygen consumption by the spectrophotometric oxyhemoglobin method. METHODS OF BIOCHEMICAL ANALYSIS 2006; 30:227-67. [PMID: 6330496 DOI: 10.1002/9780470110515.ch5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Brand MD, Pakay JL, Ocloo A, Kokoszka J, Wallace DC, Brookes PS, Cornwall EJ. The basal proton conductance of mitochondria depends on adenine nucleotide translocase content. Biochem J 2006; 392:353-62. [PMID: 16076285 PMCID: PMC1316271 DOI: 10.1042/bj20050890] [Citation(s) in RCA: 289] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The basal proton conductance of mitochondria causes mild uncoupling and may be an important contributor to metabolic rate. The molecular nature of the proton-conductance pathway is unknown. We show that the proton conductance of muscle mitochondria from mice in which isoform 1 of the adenine nucleotide translocase has been ablated is half that of wild-type controls. Overexpression of the adenine nucleotide translocase encoded by the stress-sensitive B gene in Drosophila mitochondria increases proton conductance, and underexpression decreases it, even when the carrier is fully inhibited using carboxyatractylate. We conclude that half to two-thirds of the basal proton conductance of mitochondria is catalysed by the adenine nucleotide carrier, independently of its ATP/ADP exchange or fatty-acid-dependent proton-leak functions.
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Affiliation(s)
- Martin D Brand
- Medical Research Council Dunn Human Nutrition Unit, Hills Road, Cambridge CB2 2XY, UK.
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Schlimme E, Boos KS, Bojanovski D, Lüstorff J. Untersuchungen der mitochondrialen Adeninnucleotid-Translokation mit Nucleotidanaloga. Angew Chem Int Ed Engl 2006. [DOI: 10.1002/ange.19770891007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Reis de Assis D, Maria RDC, Borba Rosa R, Schuck PF, Ribeiro CAJ, da Costa Ferreira G, Dutra-Filho CS, Terezinha de Souza Wyse A, Duval Wannmacher CM, Santos Perry ML, Wajner M. Inhibition of energy metabolism in cerebral cortex of young rats by the medium-chain fatty acids accumulating in MCAD deficiency. Brain Res 2005; 1030:141-51. [PMID: 15567346 DOI: 10.1016/j.brainres.2004.10.010] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/12/2004] [Indexed: 11/30/2022]
Abstract
Patients affected by medium-chain acyl CoA dehydrogenase (MCAD) deficiency, a frequent inborn error of metabolism, suffer from acute episodes of encephalopathy. However, the mechanisms underlying the neuropathology of this disease are poorly known. In the present study, we investigated the in vitro effect of the medium-chain fatty acids (MCFA), at concentrations varying from 0.01 to 3 mM, accumulating in MCAD deficiency on some parameters of energy metabolism in cerebral cortex of young rats. (14)CO(2) production from [U(14)] glucose, [1-(14)C] acetate and [1,5-(14)C] citrate was evaluated by incubating cerebral cortex homogenates from 30-day-old rats in the absence (controls) or presence of octanoic acid, decanoic acid or cis-4-decenoic acid. OA and DA significantly reduced (14)CO(2) production from acetate by around 30-40%, and from glucose by around 70%. DA significantly reduced (14)CO(2) production from citrate by around 40%, while OA did not affect this parameter. cDA inhibited (14)CO(2) production from all tested substrates by around 30-40%. The activities of the respiratory chain complexes and of creatine kinase were also tested in the presence of DA and cDA. Both metabolites significantly inhibited cytochrome c oxidase activity (by 30%) and complex II-III activity (DA, 25%; cDA, 80%). Furthermore, only cDA inhibited complex II activity (by 30%), while complex I-III and citrate synthase were not affected by these MCFA. On the other hand, only cDA reduced the activity of creatine kinase in total homogenates, as well as in mitochondrial and cytosolic fractions from cerebral cortex (by 50%). The data suggest that the major metabolites which accumulate in MCAD deficiency, with particular emphasis to cDA, compromise brain energy metabolism. We presume that these findings may contribute to the understanding of the pathophysiology of the neurological dysfunction of MCAD deficient patients.
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Affiliation(s)
- Dênis Reis de Assis
- Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS 90035-003, Brazil
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Juárez O, Guerra G, Martínez F, Pardo JP. The mitochondrial respiratory chain of Ustilago maydis. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2004; 1658:244-51. [PMID: 15450962 DOI: 10.1016/j.bbabio.2004.06.005] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2003] [Revised: 05/17/2004] [Accepted: 06/09/2004] [Indexed: 11/29/2022]
Abstract
Ustilago maydis mitochondria contain the four classical components of the electron transport chain (complexes I, II, III, and IV), a glycerol phosphate dehydrogenase, and two alternative elements: an external rotenone-insensitive flavone-sensitive NADH dehydrogenase (NDH-2) and an alternative oxidase (AOX). The external NDH-2 contributes as much as complex I to the NADH-dependent respiratory activity, and is not modulated by Ca2+, a regulatory mechanism described for plant NDH-2, and presumed to be a unique characteristic of the external isozyme. The AOX accounts for the 20% residual respiratory activity after inhibition of complex IV by cyanide. This residual activity depends on growth conditions, since cells grown in the presence of cyanide or antimycin A increase its proportion to about 75% of the uninhibited rate. The effect of AMP, pyruvate and DTT on AOX was studied. The activity of AOX in U. maydis cells was sensitive to AMP but not to pyruvate, which agrees with the regulatory characteristics of a fungal AOX. Interestingly, the presence of DTT during cell permeabilisation protected the enzyme against inactivation. The pathways of quinone reduction and quinol oxidation lack an additive behavior. This is consistent with the competition of the respiratory components of each pathway for the quinol/quinone pool.
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Affiliation(s)
- Oscar Juárez
- Departamento de Bioquímica, Facultad de Medicina, Ciudad Universitaria, Universidad Nac. Autonoma Mex., UNAM, México D.F. 14080, Mexico
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Abstract
Perinatal hypoxia-ischemia remains a significant cause of neonatal mortality and neurodevelopmental disability. Numerous lines of evidence indicate that cerebral ischemic insults disrupt normal respiratory activity in mitochondria. Carnitine (3-hydroxy-4-N-trimethylammonium-butyrate) has an essential role in fatty acid transport in the mitochondrion and in modulating potentially toxic acyl-CoA levels in the mitochondrial matrix. There are no naturally occurring esterases available to reduce the accumulation of acyl-CoA but this process can be overcome by exogenous carnitine. We used a newborn rat model of perinatal hypoxia-ischemia to test the hypothesis that treatment with l-carnitine would reduce the neuropathologic injury resulting from hypoxia-ischemia in the developing brain. We found that treatment with l-carnitine during hypoxia-ischemia reduces neurologic injury in the immature rat after both a 7- and 28-d recovery period. We saw no neuroprotective effect when l-carnitine was administered after hypoxia-ischemia. Treatment with d-carnitine resulted in an increase in mortality during hypoxia-ischemia. Carnitine is easy to administer, has low toxicity, and is routinely used in neonates as well as children with epilepsy, cardiomyopathy, and inborn errors of metabolism. l-Carnitine merits further investigation as a treatment modality for the asphyxiated newborn or as prophylaxis for the at-risk fetus or newborn.
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Affiliation(s)
- Mark S Wainwright
- Division of Pediatric Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60614, USA.
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Bernardi P, Penzo D, Wojtczak L. Mitochondrial energy dissipation by fatty acids. Mechanisms and implications for cell death. VITAMINS AND HORMONES 2003; 65:97-126. [PMID: 12481544 DOI: 10.1016/s0083-6729(02)65061-7] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
For most cell types, fatty acids are excellent respiratory substrates. After being transported across the outer and inner mitochondrial membranes they undergo beta-oxidation in the matrix and feed electrons into the mitochondrial energy-conserving respiratory chain. On the other hand, fatty acids also physically interact with mitochondrial membranes, and possess the potential to alter their permeability. This occurs according to two mechanisms: an increase in proton conductance of the inner mitochondrial membrane and the opening of the permeability transition pore, an inner membrane high-conductance channel that may be involved in the release of apoptogenic proteins into the cytosol. This article addresses in some detail the mechanisms through which fatty acids exert their protonophoric action and how they modulate the permeability transition pore and discusses the cellular effects of fatty acids, with specific emphasis on their role as potential mitochondrial mediators of apoptotic signaling.
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Affiliation(s)
- Paolo Bernardi
- Department of Biomedical Sciences, Venetian Institute of Molecular Medicine, University of Padova, I-35131 Padova, Italy
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Abstract
Fatty infiltration of the liver is common in the brain-dead donor population and has a strong correlation with primary nonfunction after cold preservation, a condition that is catastrophic to liver transplant recipients. This literature review examines factors associated with the development, diagnosis, quantification, and clinical management of this difficult condition.
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Fox SR, Rawsthorne S, Hills MJ. Fatty acid synthesis in pea root plastids is inhibited by the action of long-chain acyl- coenzyme as on metabolite transporters. PLANT PHYSIOLOGY 2001; 126:1259-65. [PMID: 11457976 PMCID: PMC116482 DOI: 10.1104/pp.126.3.1259] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2001] [Revised: 03/14/2001] [Accepted: 04/06/2001] [Indexed: 05/21/2023]
Abstract
The uptake in vitro of glucose (Glc)-6-phosphate (Glc-6-P) into plastids from the roots of 10- to 14-d-old pea (Pisum sativum L. cv Puget) plants was inhibited by oleoyl-coenzyme A (CoA) concentrations in the low micromolar range (1--2 microM). The IC(50) (the concentration of inhibitor that reduces enzyme activity by 50%) for the inhibition of Glc-6-P uptake was approximately 750 nM; inhibition was reversed by recombinant rapeseed (Brassica napus) acyl-CoA binding protein. In the presence of ATP (3 mM) and CoASH (coenzyme A; 0.3 mM), Glc-6-P uptake was inhibited by 60%, due to long-chain acyl-CoA synthesis, presumably from endogenous sources of fatty acids present in the preparations. Addition of oleoyl-CoA (1 microM) decreased carbon flux from Glc-6-P into the synthesis of starch and through the oxidative pentose phosphate (OPP) pathway by up to 73% and 40%, respectively. The incorporation of carbon from Glc-6-P into fatty acids was not detected under any conditions. Oleoyl-CoA inhibited the incorporation of acetate into fatty acids by 67%, a decrease similar to that when ATP was excluded from incubations. The oleoyl-CoA-dependent inhibition of fatty acid synthesis was attributable to a direct inhibition of the adenine nucleotide translocator by oleoyl-CoA, which indirectly reduced fatty acid synthesis by ATP deprivation. The Glc-6-P-dependent stimulation of acetate incorporation into fatty acids was reversed by the addition of oleoyl-CoA.
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Affiliation(s)
- S R Fox
- The Department of Brassica and Oilseeds Research, John Innes Centre, Norwich Research Park, Colney, Norwich NR4 7UH, United Kingdom
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Sakamoto T, Aoki M, Imai Y, Nemoto S. Carnitine affects fatty acid metabolism after cardioplegic arrest in neonatal rabbit hearts. Ann Thorac Surg 2001; 71:648-53. [PMID: 11235722 DOI: 10.1016/s0003-4975(00)02390-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
BACKGROUND Fatty acid (FA) metabolism and the contribution of carnitine to metabolism after cardioplegic arrest still remain unclear, especially in the neonatal heart where beta-oxidation is not a predominant source of adenosine triphosphate. METHODS FA metabolism and the effects of carnitine administration were evaluated using a newborn (7-day-old) rabbit blood-perfused Langendorff model subjected to cold cardioplegic arrest. The hearts were divided into five groups; (1) perfused with unmodified diluted blood (n = 9), (2) subjected to 180 minutes of cold cardioplegic arrest and reperfused with the blood (n = 9), (3) subjected to the same ischemia and reperfused with the blood containing 40 microM/L (n = 9), (4) 0.5 mM/L (n = 5), and (5) 5 mM/L of carnitine (n = 5). During reperfusion, FA metabolism was assessed by iodine-123-labeled 15-(p-iodophenyl)-3-(R,S)-methylpentadecanoic acid, a fatty acid. The myocardial time-radioactivity curve was then determined and a mathematical compartment analysis of the external detection was used to elucidate FA metabolism in the cardiac myocyte. RESULTS Cold cardioplegic arrest resulted in significantly impaired FA metabolism following reperfusion. Compartment analysis suggested that FA activation in the cytosol and beta-oxidation were impaired. Carnitine supplementation in groups 3 and 4 improved FA metabolism during reperfusion. In contrast, supplementation in group 5 had no beneficial effect on FA metabolism. CONCLUSIONS These results suggest that FA metabolism is impaired after cold cardioplegic arrest and that carnitine supplementation may improve aerobic metabolism in neonates after open heart surgery.
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Affiliation(s)
- T Sakamoto
- Department of Pediatric Cardiovascular Surgery, The Heart Institute of Japan, Tokyo Women's Medical University, Japan
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Nemoto S, Aoki M, Dehua C, Imai Y. Effects of carnitine on cardiac function after cardioplegic ischemia in neonatal rabbit hearts. Ann Thorac Surg 2001; 71:254-9. [PMID: 11216757 DOI: 10.1016/s0003-4975(00)02023-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
BACKGROUND Ischemia immediately impairs myocardial fatty acid metabolism and reduces the concentration of carnitine which is an essential cofactor for fatty acid metabolism in the mitochondria. The purpose of this study was to investigate the effects of carnitine administration on recovery of cardiac function after cardioplegic ischemia in the neonatal heart where fatty acid metabolism is not a predominant source of adenosine triphosphate. METHODS Isolated blood-perfused neonatal rabbit hearts underwent 3 hours of cold cardioplegic ischemia. The control group (n = 10) was reperfused with unmodified diluted blood. The carnitine group (n = 10) was reperfused with the blood containing 5 mM/L of carnitine. Before ischemia (base line) and after 15 and 30 minutes reperfusion, left ventricular (LV) function and LV compliance were measured using a intraventricular conductance catheter combined with an isovolumic balloon. Coronary blood flow was measured and myocardial oxygen consumption was calculated. RESULTS Carnitine significantly improved not only LV systolic function but also LV diastolic function (p < 0.05) as well as LV compliance after ischemia. Coronary blood flow and myocardial oxygen consumption were significantly improved after ischemia in the carnitine group compared with the control group (p < 0.05). CONCLUSIONS These results suggest that carnitine strikingly improves LV functional recovery and aerobic metabolism after cold cardioplegic arrest, and may improve cardiac performance in neonates after open heart surgery.
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Affiliation(s)
- S Nemoto
- Department of Pediatric Cardiovascular Surgery, The Heart Institute of Japan, Tokyo Women's Medical University.
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