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Gu M, Zhang Y, Lin Z, Hu X, Zhu Y, Xiao W, Jia X, Chen W, Lu G, Gong W. Decrease in UCP1 by sustained high lipid promotes NK cell necroptosis to exacerbate nonalcoholic liver fibrosis. Cell Death Dis 2024; 15:518. [PMID: 39033153 PMCID: PMC11271447 DOI: 10.1038/s41419-024-06910-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 07/06/2024] [Accepted: 07/11/2024] [Indexed: 07/23/2024]
Abstract
Uncoupling protein 1 (UCP1) catalyzes the leak of protons across the mitochondrial inner membrane for thermogenesis. Compromised NK cell activity is involved in the occurrence of nonalcoholic liver fibrosis. Here, decreased UCP1 in NK cells was identified in patients with advanced nonalcoholic fatty liver disease. Although no obvious changes were observed in the NK cells of physiologic UCP1-/- mice (8-10 weeks old), impaired NK cell bioactivity was shown in methionine-choline-diet (MCD)-fed UCP1-/- mice and involved in the acerbation of nonalcoholic steatohepatitis (NASH) progress to liver fibrosis. Moreover, UCP1-deficient NK cells were responsible for the aggravation of liver fibrosis, as confirmed in MCD-fed UCP1flox/flox-NCR1cre mice. Acerbation of liver fibrosis was also seen in wild-type mice when their endogenous NK cells were replaced with UCP1-/- NK cells. Transcriptions of mitophagy-associated molecules in UCP1-/- NK cells were enhanced according to RNA-seq. Electron microscopic results showed mitochondrial injuries and autophagic vesicles in MCD-fed NKWT cells, PA-treated NKWT cells, or physiologic NKKO cells. However, the co-existence of UCP1 deficiency and high lipid can synergistically induce NK cell necroptosis via DRP1S616 accompanied with reduced mitophagy. Finally, The UCP1 in NK cells was downregulated when treated by sustained high PA (600 μM) via the PPARγ/ATF2 axis. Thus, persistent high-lipid treatment not only decreases UCP1 expression but also combines with reduced UCP1 to promote NK cell necroptosis, and it is involved in NASH progression to fibrosis.
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Affiliation(s)
- Min Gu
- Department of Gastroenterology, Affiliated Hospital of Yangzhou University, Yangzhou, PR China
- Department of Basic Medicine, School of Medicine, Yangzhou University, Yangzhou, PR China
| | - Yu Zhang
- Department of Gastroenterology, Affiliated Hospital of Yangzhou University, Yangzhou, PR China
- Jiangsu Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Treatment of Senile Diseases, Yangzhou, PR China
| | - Zhijie Lin
- Department of Gastroenterology, Affiliated Hospital of Yangzhou University, Yangzhou, PR China
- Department of Basic Medicine, School of Medicine, Yangzhou University, Yangzhou, PR China
| | - Xiangyu Hu
- Department of Gastroenterology, Affiliated Hospital of Yangzhou University, Yangzhou, PR China
- Department of Basic Medicine, School of Medicine, Yangzhou University, Yangzhou, PR China
| | - Yaqin Zhu
- Department of Gastroenterology, Affiliated Hospital of Yangzhou University, Yangzhou, PR China
- Department of Basic Medicine, School of Medicine, Yangzhou University, Yangzhou, PR China
| | - Weiming Xiao
- Department of Gastroenterology, Affiliated Hospital of Yangzhou University, Yangzhou, PR China
- Jiangsu Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Treatment of Senile Diseases, Yangzhou, PR China
| | - Xiaoqin Jia
- Department of Gastroenterology, Affiliated Hospital of Yangzhou University, Yangzhou, PR China
- Department of Basic Medicine, School of Medicine, Yangzhou University, Yangzhou, PR China
- Jiangsu Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Treatment of Senile Diseases, Yangzhou, PR China
| | - Weiwei Chen
- Department of Gastroenterology, Affiliated Hospital of Yangzhou University, Yangzhou, PR China
- Jiangsu Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Treatment of Senile Diseases, Yangzhou, PR China
| | - Guotao Lu
- Department of Gastroenterology, Affiliated Hospital of Yangzhou University, Yangzhou, PR China.
- Jiangsu Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Treatment of Senile Diseases, Yangzhou, PR China.
- Jiangsu Key Laboratory of Zoonosis, Yangzhou, PR China.
| | - Weijuan Gong
- Department of Gastroenterology, Affiliated Hospital of Yangzhou University, Yangzhou, PR China.
- Department of Basic Medicine, School of Medicine, Yangzhou University, Yangzhou, PR China.
- Jiangsu Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Treatment of Senile Diseases, Yangzhou, PR China.
- Jiangsu Key Laboratory of Zoonosis, Yangzhou, PR China.
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2
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Kologrivova IV, Naryzhnaya NV, Suslova TE. Thymus in Cardiometabolic Impairments and Atherosclerosis: Not a Silent Player? Biomedicines 2024; 12:1408. [PMID: 39061983 PMCID: PMC11273826 DOI: 10.3390/biomedicines12071408] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2024] [Revised: 06/11/2024] [Accepted: 06/21/2024] [Indexed: 07/28/2024] Open
Abstract
The thymus represents a primary organ of the immune system, harboring the generation and maturation of T lymphocytes. Starting from childhood, the thymus undergoes involution, being replaced with adipose tissue, and by an advanced age nearly all the thymus parenchyma is represented by adipocytes. This decline of thymic function is associated with compromised maturation and selection of T lymphocytes, which may directly impact the development of inflammation and induce various autoinflammatory disorders, including atherosclerosis. For a long time, thymus health in adults has been ignored. The process of adipogenesis in thymus and impact of thymic fat on cardiometabolism remains a mysterious process, with many issues being still unresolved. Meanwhile, thymus functional activity has a potential to be regulated, since islets of thymopoeisis remain in adults even at an advanced age. The present review describes the intricate process of thymic adipose involution, focusing on the issues of the thymus' role in the development of atherosclerosis and metabolic health, tightly interconnected with the state of vessels. We also review the recent information on the key molecular pathways and biologically active substances that may be targeted to manipulate both thymic function and atherosclerosis.
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Affiliation(s)
- Irina V. Kologrivova
- Cardiology Research Institute, Tomsk National Research Medical Center, Russian Academy of Sciences, 111A Kievskaya, Tomsk 634012, Russia; (N.V.N.); (T.E.S.)
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Pinho ACO, Santos D, Baldeiras I, Burgeiro A, Leal EC, Carvalho E. Mitochondrial respiration in thoracic perivascular adipose tissue of diabetic mice. J Endocrinol 2022; 254:169-184. [PMID: 35904484 DOI: 10.1530/joe-21-0446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Accepted: 06/14/2022] [Indexed: 11/08/2022]
Abstract
Introduction Thoracic perivascular adipose tissue (tPVAT) has a phenotype resembling brown AT. Dysfunctional tPVAT appears to be linked to vascular dysfunction. Methods We evaluated uncoupling protein 1 (UCP1) expression by Western blot, oxidative stress by measuring lipid peroxidation, the antioxidant capacity by HPLC and spectrophotometry, and mitochondrial respiration by high-resolution respirometry (HRR) in tPVAT, compared to inguinal white AT (iWAT), obtained from non-diabetic (NDM) and streptozocin-induced diabetic (STZ-DM) mice. Mitochondrial respiration was assessed by HRR using protocol 1: complex I and II oxidative phosphorylation (OXPHOS) and protocol 2: fatty acid oxidation (FAO) OXPHOS. OXPHOS capacity in tPVAT was also evaluated after UCP1 inhibition by guanosine 5'-diphosphate (GDP). Results UCP1 expression was higher in tPVAT when compared with iWAT in both NDM and STZ-DM mice. The malondialdehyde concentration was elevated in tPVAT from STZ-DM compared to NDM mice. Glutathione peroxidase and reductase activities, as well as reduced glutathione levels, were not different between tPVAT from NDM and STZ-DM mice but were lower compared to iWAT of STZ-DM mice. OXPHOS capacity of tPVAT was significantly decreased after UCP1 inhibition by GDP in protocol 1. While there were no differences in the OXPHOS capacity between NDM and STZ-DM mice in protocol 1, it was increased in STZ-DM compared to NDM mice in protocol 2. Moreover, complex II- and FAO-linked respiration were elevated in STZ-DM mice under UCP1 inhibition. Conclusions Pharmacological therapies could be targeted to modulate UCP1 activity with a significant impact in the uncoupling of mitochondrial bioenergetics in tPVAT.
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Affiliation(s)
- Aryane Cruz Oliveira Pinho
- Center for Neuroscience and Cell Biology (CNC), Faculty of Medicine, University of Coimbra, Rua Larga, Coimbra, Portugal
- Department of Life Sciences, Faculty of Sciences and Technology, University of Coimbra, Calçada Martim de Freitas, Coimbra, Portugal
| | - Diana Santos
- Center for Neuroscience and Cell Biology (CNC), Faculty of Medicine, University of Coimbra, Rua Larga, Coimbra, Portugal
- Institute for Interdisciplinary Research, University of Coimbra, Casa Costa Alemão, Rua Dom Francisco de Lemos, Coimbra, Portugal
| | - Inês Baldeiras
- Center for Neuroscience and Cell Biology (CNC), Faculty of Medicine, University of Coimbra, Rua Larga, Coimbra, Portugal
| | - Ana Burgeiro
- Center for Neuroscience and Cell Biology (CNC), Faculty of Medicine, University of Coimbra, Rua Larga, Coimbra, Portugal
| | - Emelindo C Leal
- Center for Neuroscience and Cell Biology (CNC), Faculty of Medicine, University of Coimbra, Rua Larga, Coimbra, Portugal
- Institute for Interdisciplinary Research, University of Coimbra, Casa Costa Alemão, Rua Dom Francisco de Lemos, Coimbra, Portugal
| | - Eugenia Carvalho
- Center for Neuroscience and Cell Biology (CNC), Faculty of Medicine, University of Coimbra, Rua Larga, Coimbra, Portugal
- Institute for Interdisciplinary Research, University of Coimbra, Casa Costa Alemão, Rua Dom Francisco de Lemos, Coimbra, Portugal
- APDP-Portuguese Diabetes Association, Lisbon, Portugal
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Mitochondrial Uncoupling Proteins (UCPs) as Key Modulators of ROS Homeostasis: A Crosstalk between Diabesity and Male Infertility? Antioxidants (Basel) 2021; 10:antiox10111746. [PMID: 34829617 PMCID: PMC8614977 DOI: 10.3390/antiox10111746] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 10/27/2021] [Accepted: 10/28/2021] [Indexed: 12/14/2022] Open
Abstract
Uncoupling proteins (UCPs) are transmembrane proteins members of the mitochondrial anion transporter family present in the mitochondrial inner membrane. Currently, six homologs have been identified (UCP1-6) in mammals, with ubiquitous tissue distribution and multiple physiological functions. UCPs are regulators of key events for cellular bioenergetic metabolism, such as membrane potential, metabolic efficiency, and energy dissipation also functioning as pivotal modulators of ROS production and general cellular redox state. UCPs can act as proton channels, leading to proton re-entry the mitochondrial matrix from the intermembrane space and thus collapsing the proton gradient and decreasing the membrane potential. Each homolog exhibits its specific functions, from thermogenesis to regulation of ROS production. The expression and function of UCPs are intimately linked to diabesity, with their dysregulation/dysfunction not only associated to diabesity onset, but also by exacerbating oxidative stress-related damage. Male infertility is one of the most overlooked diabesity-related comorbidities, where high oxidative stress takes a major role. In this review, we discuss in detail the expression and function of the different UCP homologs. In addition, the role of UCPs as key regulators of ROS production and redox homeostasis, as well as their influence on the pathophysiology of diabesity and potential role on diabesity-induced male infertility is debated.
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5
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Prawira AY, Novelina S, Farida WR, Darusman HS, Warita K, Agungpriyono S, Hosaka YZ. Localization of uncoupling protein 1 (UCP-1) in the sebaceous gland of the dorsal region in the Sunda porcupine (Hystrix javanica). J Vet Med Sci 2020; 82:1729-1733. [PMID: 33055467 PMCID: PMC7804037 DOI: 10.1292/jvms.20-0412] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Uncoupling protein 1 (UCP-1) was believed to be an exclusive protein found in the brown adipose tissue of small rodents and humans; however, recent studies show that the expression of UCP-1 protein has been found in the sebaceous glands of the mouse tail and human skin. There are a few reports about the presence of UCP-1 in the sebaceous glands of other rodents, such as the Sunda porcupine (Hystrix javanica), a wild spiny rodent commonly found in Indonesia with a large sebaceous gland. The aim of this study was to identify the presence of UCP-1 in the sebaceous glands on the skin of the Sunda porcupine. The skin from three regions (thoracodorsal, lumbosacral and apex caudal) of eight adult Sunda porcupines was used to detect UCP-1-immunopositive cells through immunohistochemistry. All three regions were found immunopositive to anti-UCP-1 antibody in the sebaceous gland of quill and hair follicles, and the epidermal layer in quill and hair follicles with various intensities. The result of immunohistochemistry revealed that the thoracodorsal and apex caudal region was the most intense immunoreaction followed by the lumbosacral region. These findings proved that the presence of UCP-1 was also identified in the sebaceous glands of other rodent (Hystrix javanica) and regions of the body, which has not been reported previously.
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Affiliation(s)
- Andhika Yudha Prawira
- Department of Anatomy, Physiology, and Pharmacology, Faculty of Veterinary Medicine, IPB University, Bogor 16680, Indonesia
| | - Savitri Novelina
- Department of Anatomy, Physiology, and Pharmacology, Faculty of Veterinary Medicine, IPB University, Bogor 16680, Indonesia
| | - Wartika Rosa Farida
- Zoology Division, Research Center for Biology, Indonesian Institute of Sciences, Cibinong 16911, Indonesia
| | - Huda Shalahudin Darusman
- Department of Anatomy, Physiology, and Pharmacology, Faculty of Veterinary Medicine, IPB University, Bogor 16680, Indonesia.,Primate Research Center, IPB University, Bogor 16151, Indonesia
| | - Katsuhiko Warita
- Laboratory of Veterinary Anatomy, Faculty of Agriculture, Tottori University, Tottori 680-8553 Japan
| | - Srihadi Agungpriyono
- Department of Anatomy, Physiology, and Pharmacology, Faculty of Veterinary Medicine, IPB University, Bogor 16680, Indonesia
| | - Yoshinao Z Hosaka
- Laboratory of Veterinary Anatomy, Faculty of Agriculture, Tottori University, Tottori 680-8553 Japan
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6
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Elsukova EI. Two-Level Organization of Thermogenesis in Adipose Tissue: a Morphofunctional Hypothesis. J EVOL BIOCHEM PHYS+ 2019. [DOI: 10.1134/s0022093019050065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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7
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Craft CS, Robles H, Lorenz MR, Hilker ED, Magee KL, Andersen TL, Cawthorn WP, MacDougald OA, Harris CA, Scheller EL. Bone marrow adipose tissue does not express UCP1 during development or adrenergic-induced remodeling. Sci Rep 2019; 9:17427. [PMID: 31758074 PMCID: PMC6874537 DOI: 10.1038/s41598-019-54036-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Accepted: 10/24/2019] [Indexed: 12/31/2022] Open
Abstract
Adipocytes within the skeleton are collectively termed bone marrow adipose tissue (BMAT). BMAT contributes to peripheral and local metabolism, however, its capacity for cell-autonomous expression of uncoupling protein 1 (UCP1), a biomarker of beige and brown adipogenesis, remains unclear. To overcome this, Ucp1-Cre was used to drive diphtheria toxin expression in cells expressing UCP1 (Ucp1Cre+/DTA+). Despite loss of brown adipose tissue, BMAT volume was not reduced in Ucp1Cre+/DTA+ mice. Comparably, in mTmG reporter mice (Ucp1Cre+/mTmG+), Ucp1-Cre expression was absent from BMAT in young (3-weeks) and mature (16-weeks) male and female mice. Further, β3-agonist stimulation failed to induce Ucp1-Cre expression in BMAT. This demonstrates that BMAT adipocytes are not UCP1-expressing beige/brown adipocytes. Thus, to identify novel and emerging roles for BMAT adipocytes in skeletal and whole-body homeostasis, we performed gene enrichment analysis of microarray data from adipose tissues of adult rabbits. Pathway analysis revealed genetic evidence for differences in BMAT including insulin resistance, decreased fatty acid metabolism, and enhanced contributions to local processes including bone mineral density through candidate genes such as osteopontin. In sum, this supports a paradigm by which BMAT adipocytes are a unique subpopulation that is specialized to support cells within the skeletal and hematopoietic niche.
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Affiliation(s)
- Clarissa S Craft
- Division of Bone and Mineral Diseases, Department of Internal Medicine, Washington University School of Medicine, Saint Louis, MO, USA
- Department of Cell Biology & Physiology, Washington University School of Medicine, Saint Louis, MO, USA
| | - Hero Robles
- Division of Bone and Mineral Diseases, Department of Internal Medicine, Washington University School of Medicine, Saint Louis, MO, USA
| | - Madelyn R Lorenz
- Division of Bone and Mineral Diseases, Department of Internal Medicine, Washington University School of Medicine, Saint Louis, MO, USA
| | - Eric D Hilker
- Division of Bone and Mineral Diseases, Department of Internal Medicine, Washington University School of Medicine, Saint Louis, MO, USA
| | - Kristann L Magee
- Division of Bone and Mineral Diseases, Department of Internal Medicine, Washington University School of Medicine, Saint Louis, MO, USA
| | - Thomas L Andersen
- Department of Pathology, Odense University Hospital - Department of Clinical Research & Department Molecular Medicine, University of Southern Denmark, Odense, Denmark
- Department of Forensic Medicine, Aarhus University, Aarhus, Denmark
| | - William P Cawthorn
- University/BHF Centre for Cardiovascular Science, The Queen's Medical Research Institute, Edinburgh Bioquarter, University of Edinburgh, Edinburgh, UK
| | - Ormond A MacDougald
- Department of Molecular & Integrative Physiology, University of Michigan, Ann Arbor, MI, USA
| | - Charles A Harris
- Division of Endocrinology, Metabolism, and Lipid Research, Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
- Department of Medicine, Veterans Affairs St. Louis Healthcare System, John Cochran Division, St. Louis, MO, USA
| | - Erica L Scheller
- Division of Bone and Mineral Diseases, Department of Internal Medicine, Washington University School of Medicine, Saint Louis, MO, USA.
- Department of Cell Biology & Physiology, Washington University School of Medicine, Saint Louis, MO, USA.
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8
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Gaudry MJ, Keuper M, Jastroch M. Molecular evolution of thermogenic uncoupling protein 1 and implications for medical intervention of human disease. Mol Aspects Med 2019; 68:6-17. [DOI: 10.1016/j.mam.2019.06.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Revised: 06/20/2019] [Accepted: 06/21/2019] [Indexed: 12/12/2022]
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9
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Tarry-Adkins JL, Aiken CE, Ashmore TJ, Fernandez-Twinn DS, Chen JH, Ozanne SE. A suboptimal maternal diet combined with accelerated postnatal growth results in an altered aging profile in the thymus of male rats. FASEB J 2019; 33:239-253. [PMID: 29975569 PMCID: PMC6314471 DOI: 10.1096/fj.201701350rr] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Reduced fetal nutrition and rapid postnatal growth accelerates the aging phenotype in many organ systems; however, effects on the immune system are unclear. We addressed this by studying the thymus from a rat model of developmental programming. The recuperated group was generated by in utero protein restriction, followed by cross-fostering to control-fed mothers, and were then compared with controls. Fat infiltration and adipocyte size increased with age ( P < 0.001) and in recuperated thymi ( P < 0.05). Cortex/medulla ratio decreased with age ( P < 0.001) and decreased ( P < 0.05) in 12-mo recuperated thymi. Age-associated decreases in thymic-epithelial cell ( P < 0.01) and thymocyte markers ( P < 0.01) were observed in both groups and was decreased ( P < 0.05) in recuperated thymi. These data demonstrate effects of developmental programming upon thymic involution. The recuperated group had longer thymic telomeres than controls ( P < 0.001) at 22 d and at 3 mo, which was associated with increased expression of telomere-length maintenance molecules [telomerase RNA component ( Terc; P < 0.01), P23 ( P = 0.02), and Ku70 and Ku80 ( P < 0.01)]. By 12 mo, recuperated offspring had shorter thymic telomeres than controls had ( P < 0.001) and reduced DNA damage-response markers [( DNA-PKcs, Mre11 ( P < 0.01), Xrcc4 ( P = 0.02), and γ-H2ax ( P < 0.001], suggesting failure of earlier compensatory responses. Our results suggest that low birth weight with rapid postnatal growth results in premature thymic maturation, resulting in accelerated thymic aging. This could lead to increased age-associated vulnerability to infection.-Tarry-Adkins, J. L., Aiken, C. E., Ashmore, T. J., Fernandez-Twinn, D. S., Chen, J.-H., Ozanne, S. E. A suboptimal maternal diet combined with accelerated postnatal growth results in an altered aging profile in the thymus of male rats.
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Affiliation(s)
- Jane L. Tarry-Adkins
- University of Cambridge Metabolic Research Laboratories and Medical Research Council (MRC) Metabolic Diseases Unit, Wellcome Trust–MRC Institute of Metabolic Science, Addenbrooke’s Treatment Centre, Addenbrooke’s Hospital, Cambridge, United Kingdom,Correspondence: University of Cambridge Metabolic Research Laboratories and Medical Research Council (MRC) Metabolic Diseases Unit, Wellcome Trust–MRC Institute of Metabolic Science, Level 4, Box 289, Addenbrooke’s Treatment Centre, Addenbrooke’s Hospital, Hills Rd., Cambridge CB2 OQQ, United Kingdom. E-mail:
| | - Catherine E. Aiken
- University of Cambridge Metabolic Research Laboratories and Medical Research Council (MRC) Metabolic Diseases Unit, Wellcome Trust–MRC Institute of Metabolic Science, Addenbrooke’s Treatment Centre, Addenbrooke’s Hospital, Cambridge, United Kingdom
| | - Thomas J. Ashmore
- University of Cambridge Metabolic Research Laboratories and Medical Research Council (MRC) Metabolic Diseases Unit, Wellcome Trust–MRC Institute of Metabolic Science, Addenbrooke’s Treatment Centre, Addenbrooke’s Hospital, Cambridge, United Kingdom
| | - Denise S. Fernandez-Twinn
- University of Cambridge Metabolic Research Laboratories and Medical Research Council (MRC) Metabolic Diseases Unit, Wellcome Trust–MRC Institute of Metabolic Science, Addenbrooke’s Treatment Centre, Addenbrooke’s Hospital, Cambridge, United Kingdom
| | - Jian-Hua Chen
- University of Cambridge Metabolic Research Laboratories and Medical Research Council (MRC) Metabolic Diseases Unit, Wellcome Trust–MRC Institute of Metabolic Science, Addenbrooke’s Treatment Centre, Addenbrooke’s Hospital, Cambridge, United Kingdom
| | - Susan E. Ozanne
- University of Cambridge Metabolic Research Laboratories and Medical Research Council (MRC) Metabolic Diseases Unit, Wellcome Trust–MRC Institute of Metabolic Science, Addenbrooke’s Treatment Centre, Addenbrooke’s Hospital, Cambridge, United Kingdom
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10
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Molecular evolution of uncoupling proteins and implications for brain function. Neurosci Lett 2018; 696:140-145. [PMID: 30582970 DOI: 10.1016/j.neulet.2018.12.027] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Revised: 12/17/2018] [Accepted: 12/18/2018] [Indexed: 01/01/2023]
Abstract
Uncoupling proteins (UCPs) belong to the mitochondrial anion carrier superfamily and catalyze important metabolic functions at the mitochondrial inner membrane. While the thermogenic role of UCP1 in brown fat of eutherian mammals is well established, the molecular functions of UCP1 in ectothermic vertebrates and of other UCP paralogs remain less clear. Here, we critically discuss the existence of brain UCPs and their potential roles. Applying phylogenetic classification of novel UCPs, we summarize the evidence for brain UCP1 among vertebrates, the role of UCP2 in specific brain areas, and the existence of brain-specific UCPs. The phylogenetic analyses and discussion on functional data should alert the scientific community that the molecular function of so-called UCP1 homologues is by far not clarified and possibly relates to neither thermogenesis nor mitochondrial uncoupling.
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11
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Ježek P, Holendová B, Garlid KD, Jabůrek M. Mitochondrial Uncoupling Proteins: Subtle Regulators of Cellular Redox Signaling. Antioxid Redox Signal 2018; 29:667-714. [PMID: 29351723 PMCID: PMC6071544 DOI: 10.1089/ars.2017.7225] [Citation(s) in RCA: 80] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
SIGNIFICANCE Mitochondria are the energetic, metabolic, redox, and information signaling centers of the cell. Substrate pressure, mitochondrial network dynamics, and cristae morphology state are integrated by the protonmotive force Δp or its potential component, ΔΨ, which are attenuated by proton backflux into the matrix, termed uncoupling. The mitochondrial uncoupling proteins (UCP1-5) play an eminent role in the regulation of each of the mentioned aspects, being involved in numerous physiological events including redox signaling. Recent Advances: UCP2 structure, including purine nucleotide and fatty acid (FA) binding sites, strongly support the FA cycling mechanism: UCP2 expels FA anions, whereas uncoupling is achieved by the membrane backflux of protonated FA. Nascent FAs, cleaved by phospholipases, are preferential. The resulting Δp dissipation decreases superoxide formation dependent on Δp. UCP-mediated antioxidant protection and its impairment are expected to play a major role in cell physiology and pathology. Moreover, UCP2-mediated aspartate, oxaloacetate, and malate antiport with phosphate is expected to alter metabolism of cancer cells. CRITICAL ISSUES A wide range of UCP antioxidant effects and participations in redox signaling have been reported; however, mechanisms of UCP activation are still debated. Switching off/on the UCP2 protonophoretic function might serve as redox signaling either by employing/releasing the extra capacity of cell antioxidant systems or by directly increasing/decreasing mitochondrial superoxide sources. Rapid UCP2 degradation, FA levels, elevation of purine nucleotides, decreased Mg2+, or increased pyruvate accumulation may initiate UCP-mediated redox signaling. FUTURE DIRECTIONS Issues such as UCP2 participation in glucose sensing, neuronal (synaptic) function, and immune cell activation should be elucidated. Antioxid. Redox Signal. 29, 667-714.
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Affiliation(s)
- Petr Ježek
- 1 Department of Mitochondrial Physiology, Institute of Physiology of the Czech Academy of Sciences , Prague, Czech Republic
| | - Blanka Holendová
- 1 Department of Mitochondrial Physiology, Institute of Physiology of the Czech Academy of Sciences , Prague, Czech Republic
| | - Keith D Garlid
- 2 UCLA Cardiovascular Research Laboratory, David Geffen School of Medicine at UCLA , Los Angeles, California
| | - Martin Jabůrek
- 1 Department of Mitochondrial Physiology, Institute of Physiology of the Czech Academy of Sciences , Prague, Czech Republic
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12
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Jastroch M, Oelkrug R, Keipert S. Insights into brown adipose tissue evolution and function from non-model organisms. ACTA ACUST UNITED AC 2018. [PMID: 29514888 DOI: 10.1242/jeb.169425] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Brown adipose tissue (BAT) enables adaptive thermoregulation through heat production that is catalyzed by mitochondrial uncoupling protein 1 (UCP1). BAT is frequently studied in rodent model organisms, and recently in adult humans to treat metabolic diseases. However, complementary studies of many non-model species, which have diversified to many more ecological niches, may significantly broaden our understanding of BAT regulation and its physiological roles. This Review highlights the research on non-model organisms, which was instrumental to the discovery of BAT function, and the unique evolutionary history of BAT/UCP1 in mammalian thermogenesis. The comparative biology of BAT provides a powerful integrative approach that could identify conserved and specialized functional changes in BAT and UCP1 by considering species diversity, ecology and evolution, and by fusing multiple scientific disciplines such as physiology and biochemistry. Thus, resolving the complete picture of BAT biology may fail if comparative studies of non-model organisms are neglected.
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Affiliation(s)
- Martin Jastroch
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center at Helmholtz Zentrum München, D-85764 Neuherberg, Germany .,German Center for Diabetes Research (DZD), D-85764 Neuherberg, Germany.,Department of Animal Physiology, Faculty of Biology, Philipps University of Marburg, D-35032 Marburg, Germany
| | - Rebecca Oelkrug
- Department of Molecular Endocrinology, Center of Brain, Behavior and Metabolism (CBBM), University of Lübeck, D-23562 Lübeck, Germany
| | - Susanne Keipert
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center at Helmholtz Zentrum München, D-85764 Neuherberg, Germany.,German Center for Diabetes Research (DZD), D-85764 Neuherberg, Germany
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13
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Abstract
Brown adipose tissue (BAT), the specialized heat-producing organ found in many placental mammals including humans, may be accessible for clinical drug intervention to help combat metabolic diseases. Understanding the biology of BAT and its thermogenic uncoupling protein 1 (UCP1) will benefit from an assessment of its evolution, answering where UCP1 originated and how it has been modified and integrated into cellular energy metabolism. Here, we review topical insights regarding the molecular evolution of UCP1-also reconstructing the proximate and ultimate factors selecting for brown fat thermogenesis in placental mammals. This new thinking on "old" events will assist our understanding of how thermogenic mitochondrial uncoupling was integrated into the physiology of the brown adipocyte. Recent comparative studies examining the occurrence of UCP1 in vertebrates not only identified the ancient (pre-mammal) rise of UCP1 but also its repeated downfall during mammalian evolution as evidenced by multiple independent gene loss and/or inactivation events. Together with the comparative physiology of various species, we may be able to find conditions that favor UCP1 thermogenesis and, learning from these insights, identify molecular networks that will be useful to pharmacologically stimulate the tissue.
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Affiliation(s)
- Michael J Gaudry
- Department of Biological Sciences, University of Manitoba, Winnipeg, MB, Canada
| | - Kevin L Campbell
- Department of Biological Sciences, University of Manitoba, Winnipeg, MB, Canada
| | - Martin Jastroch
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center at Helmholtz Zentrum München, Neuherberg, Germany. .,German Center for Diabetes Research (DZD), München-Neuherberg, Germany.
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14
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Hu M, Lin H, Yang L, Cheng Y, Zhang H. Interleukin-22 restored mitochondrial damage and impaired glucose-stimulated insulin secretion through down-regulation of uncoupling protein-2 in INS-1 cells. J Biochem 2017; 161:433-439. [PMID: 28069865 DOI: 10.1093/jb/mvw084] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Accepted: 11/03/2016] [Indexed: 01/17/2023] Open
Abstract
Defective glucose-stimulated insulin secretion (GSIS) induced by chronic exposure to fatty acids is a hallmark of type 2 diabetes (T2D). Interleukin-22 (IL-22) has been shown to exert beneficial effects on insulin secretion and to protect pancreatic β-cells from stress. Moreover, uncoupling protein-2 (UCP-2) plays a central role in the regulation of GSIS and β-cell dysfunction, whereas the role of UCP-2 in IL-22-enhanced glycemic control under conditions of lipotoxicity remains unclear. In this present study, we investigated the effects of IL-22 on rat insulin-secreting cells (INS-1 cells) and the mechanisms that underlie IL-22 and lipotoxicity-impaired GSIS in vitro. Chronic palmitate (PA) treatment impaired insulin secretion and activated UCP-2 expression in INS-1 cells. Furthermore, in INS-1 cells, both reduced mitochondrial membrane potential (ΔΨm) and impaired GSIS induced by PA treatment were effectively reversed by an inhibitor of UCP-2 (genipin). Additionally, compared with the PA-treated group, INS-1 cells treated with IL-22 down-regulated UCP-2 expression, increased mitochondrial membrane potential, and restored GSIS. Together, our findings indicate that chronic exposure to PA could activate UCP-2, resulting in mitochondrial damage and impaired GSIS in INS-1 cells. We also suggest that IL-22 plays a protective role in this process via the down-regulation of UCP-2.
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Affiliation(s)
- Minling Hu
- Department of Endocrinology, The First Affiliated Hospital of Clinical Medicine of Guangdong Pharmaceutical University, Guangzhou 510080, China
| | - Hanxiao Lin
- Department of Nutrition, Guangzhou First People's Hospital, Guangzhou Medical University, 602 Ren Min Bei Road, Guangzhou 510180, P.R. China
| | - Li Yang
- Department of Endocrinology, Zhujiang Hospital, Southern Medical University, S253 Industry Boulevard, Guangzhou 510282, China
| | - Yanzhen Cheng
- Department of Endocrinology, Zhujiang Hospital, Southern Medical University, S253 Industry Boulevard, Guangzhou 510282, China
| | - Hua Zhang
- Department of Endocrinology, Zhujiang Hospital, Southern Medical University, S253 Industry Boulevard, Guangzhou 510282, China
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15
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The conserved regulation of mitochondrial uncoupling proteins: From unicellular eukaryotes to mammals. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2016; 1858:21-33. [PMID: 27751905 DOI: 10.1016/j.bbabio.2016.10.003] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Revised: 09/29/2016] [Accepted: 10/13/2016] [Indexed: 12/19/2022]
Abstract
Uncoupling proteins (UCPs) belong to the mitochondrial anion carrier protein family and mediate regulated proton leak across the inner mitochondrial membrane. Free fatty acids, aldehydes such as hydroxynonenal, and retinoids activate UCPs. However, there are some controversies about the effective action of retinoids and aldehydes alone; thus, only free fatty acids are commonly accepted positive effectors of UCPs. Purine nucleotides such as GTP inhibit UCP-mediated mitochondrial proton leak. In turn, membranous coenzyme Q may play a role as a redox state-dependent metabolic sensor that modulates the complete activation/inhibition of UCPs. Such regulation has been observed for UCPs in microorganisms, plant and animal UCP1 homologues, and UCP1 in mammalian brown adipose tissue. The origin of UCPs is still under debate, but UCP homologues have been identified in all systematic groups of eukaryotes. Despite the differing levels of amino acid/DNA sequence similarities, functional studies in unicellular and multicellular organisms, from amoebae to mammals, suggest that the mechanistic regulation of UCP activity is evolutionarily well conserved. This review focuses on the regulatory feedback loops of UCPs involving free fatty acids, aldehydes, retinoids, purine nucleotides, and coenzyme Q (particularly its reduction level), which may derive from the early stages of evolution as UCP first emerged.
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16
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Clarke KJ, Carroll AM, O'Brien G, Porter RK. Detection of UCP1 protein and measurements of dependent GDP-sensitive proton leak in non-phosphorylating thymus mitochondria. Methods Mol Biol 2015; 1241:123-35. [PMID: 25308493 DOI: 10.1007/978-1-4939-1875-1_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Over several years we have provided evidence that uncoupling protein 1 (UCP1) is present in thymus mitochondria. We have demonstrated the conclusive evidence for the presence of UCP1 in thymus mitochondria and we have been able to demonstrate a GDP-sensitive UCP1-dependent proton leak in non-phosphorylating thymus mitochondria. In this chapter, we show how to detect UCP1 in mitochondria isolated from whole thymus using immunoblotting. We show how to measure GDP-sensitive UCP1-dependent oxygen consumption in non-phosphorylating thymus mitochondria and we show that increased reactive oxygen species production occurs on addition of GDP to non-phosphorylating thymus mitochondria. We conclude that reactive oxygen species production rate can be used as a surrogate for detecting UCP1 catalyzed proton leak activity in thymus mitochondria.
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Affiliation(s)
- Kieran J Clarke
- School of Biochemistry & Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Pearse Street, Dublin 2, Ireland
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17
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Oelkrug R, Polymeropoulos ET, Jastroch M. Brown adipose tissue: physiological function and evolutionary significance. J Comp Physiol B 2015; 185:587-606. [PMID: 25966796 DOI: 10.1007/s00360-015-0907-7] [Citation(s) in RCA: 176] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Revised: 04/21/2015] [Accepted: 04/26/2015] [Indexed: 01/11/2023]
Abstract
In modern eutherian (placental) mammals, brown adipose tissue (BAT) evolved as a specialized thermogenic organ that is responsible for adaptive non-shivering thermogenesis (NST). For NST, energy metabolism of BAT mitochondria is increased by activation of uncoupling protein 1 (UCP1), which dissipates the proton motive force as heat. Despite the presence of UCP1 orthologues prior to the divergence of teleost fish and mammalian lineages, UCP1's significance for thermogenic adipose tissue emerged at later evolutionary stages. Recent studies on the presence of BAT in metatherians (marsupials) and eutherians of the afrotherian clade provide novel insights into the evolution of adaptive NST in mammals. In particular studies on the 'protoendothermic' lesser hedgehog tenrec (Afrotheria) suggest an evolutionary scenario linking BAT to the onset of eutherian endothermy. Here, we review the physiological function and distribution of BAT in an evolutionary context by focusing on the latest research on phylogenetically distinct species.
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Affiliation(s)
- R Oelkrug
- Department of Animal Physiology, Faculty of Biology, Philipps-Universität Marburg, Karl-von-Frisch Straße 8, 35043, Marburg, Germany,
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18
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Brain death-induced inflammatory activity in human pancreatic tissue: a case-control study. Transplantation 2014; 97:212-9. [PMID: 24142035 DOI: 10.1097/tp.0b013e3182a949fa] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
BACKGROUND Long-term insulin independence after islet transplantation depends on engraftment of a large number of islets. However, the yield of pancreatic islets from brain-dead donors is negatively affected by the up-regulation of inflammatory mediators. Brain death is also believed to increase tissue factor (TF) expression, contributing to a low rate of engraftment. METHODS We conducted a case-control study to assess brain death-induced inflammatory effects in human pancreas. Seventeen brain-dead patients and 20 control patients undergoing pancreatectomy were studied. Serum tumor necrosis factor (TNF), interleukin (IL) 6, IL-1β, interferon (IFN) γ, and TF were measured using enzyme-linked immunosorbent assay kits. Gene expressions of these cytokines and TF were evaluated by reverse transcriptase quantitative polymerase chain reaction. Protein quantification was performed by immunohistochemistry in paraffin-embedded pancreas sections. RESULTS Brain-dead patients had higher serum concentrations of TNF and IL-6 and increased TNF protein levels compared to controls. The groups had similar TNF, IL-6, IL-1β, and IFN-γ messenger RNA levels in pancreatic tissue. Reverse transcriptase quantitative polymerase chain reaction revealed TF messenger RNA up-regulation in controls. Immunohistochemical analyses showed that brain-dead patients had increased TNF protein levels compared to controls. CONCLUSIONS Brain death induces inflammation evidenced by the up-regulation of TNF in serum and pancreatic tissue. Blocking the expression of key inflammatory mediators in brain-dead donors should be evaluated as a new approach to improve the outcomes of islet transplantation.
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19
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JEŽEK P, OLEJÁR T, SMOLKOVÁ K, JEŽEK J, DLASKOVÁ A, PLECITÁ-HLAVATÁ L, ZELENKA J, ŠPAČEK T, ENGSTOVÁ H, PAJUELO REGUERA D, JABŮREK M. Antioxidant and Regulatory Role of Mitochondrial Uncoupling Protein UCP2 in Pancreatic β-cells. Physiol Res 2014; 63:S73-91. [DOI: 10.33549/physiolres.932633] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Research on brown adipose tissue and its hallmark protein, mitochondrial uncoupling protein UCP1, has been conducted for half a century and has been traditionally studied in the Institute of Physiology (AS CR, Prague), likewise UCP2 residing in multiple tissues for the last two decades. Our group has significantly contributed to the elucidation of UCP uncoupling mechanism, fully dependent on free fatty acids (FFAs) within the inner mitochondrial membrane. Now we review UCP2 physiological roles emphasizing its roles in pancreatic β-cells, such as antioxidant role, possible tuning of redox homeostasis (consequently UCP2 participation in redox regulations), and fine regulation of glucose-stimulated insulin secretion (GSIS). For example, NADPH has been firmly established as being a modulator of GSIS and since UCP2 may influence redox homeostasis, it likely affects NADPH levels. We also point out the role of phospholipase iPLA2 isoform in providing FFAs for the UCP2 antioxidant function. Such initiation of mild uncoupling hypothetically precedes lipotoxicity in pancreatic β-cells until it reaches the pathological threshold, after which the antioxidant role of UCP2 can be no more cell-protective, for example due to oxidative stress-accumulated mutations in mtDNA. These mechanisms, together with impaired autocrine insulin function belong to important causes of Type 2 diabetes etiology.
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Affiliation(s)
- P. JEŽEK
- Department of Membrane Transport Biophysics, Institute of Physiology Academy of Sciences of the Czech Republic, Prague, Czech Republic
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20
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Brondani LDA, Assmann TS, Duarte GCK, Gross JL, Canani LH, Crispim D. The role of the uncoupling protein 1 (UCP1) on the development of obesity and type 2 diabetes mellitus. ACTA ACUST UNITED AC 2013; 56:215-25. [PMID: 22790465 DOI: 10.1590/s0004-27302012000400001] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2012] [Accepted: 06/10/2012] [Indexed: 12/19/2022]
Abstract
It is well established that genetic factors play an important role in the development of both type 2 diabetes mellitus (DM2) and obesity, and that genetically susceptible subjects can develop these metabolic diseases after being exposed to environmental risk factors. Therefore, great efforts have been made to identify genes associated with DM2 and/or obesity. Uncoupling protein 1 (UCP1) is mainly expressed in brown adipose tissue, and acts in thermogenesis, regulation of energy expenditure, and protection against oxidative stress. All these mechanisms are associated with the pathogenesis of DM2 and obesity. Hence, UCP1 is a candidate gene for the development of these disorders. Indeed, several studies have reported that polymorphisms -3826A/G, -1766A/G and -112A/C in the promoter region, Ala64Thr in exon 2 and Met299Leu in exon 5 of UCP1 gene are possibly associated with obesity and/or DM2. However, results are still controversial in different populations. Thus, the aim of this study was to review the role of UCP1 in the development of these metabolic diseases.
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Affiliation(s)
- Letícia de Almeida Brondani
- Endocrinology Division, Hospital de Clínicas de Porto Alegre, Universidade Federal do Rio Grande do Sul, RS, Brazil
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21
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Lack of activation of UCP1 in isolated brown adipose tissue mitochondria by glucose-O-ω-modified saturated fatty acids of various chain lengths. J Chem Biol 2013; 6:121-33. [PMID: 24432128 DOI: 10.1007/s12154-013-0093-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2012] [Accepted: 03/04/2013] [Indexed: 01/28/2023] Open
Abstract
We previously demonstrated that uncoupling protein 1 activity, as measured in isolated brown adipose tissue mitochondria (and as a native protein reconstituted into liposome membranes), was not activated by the non-flippable modified saturated fatty acid, glucose-O-ω-palmitate, whereas activity was stimulated by palmitate alone (40 nM free final concentration). In this study, we investigated whether fatty acid chain length had any bearing on the ability of glucose-O-ω-fatty acids to activate uncoupling protein 1. Glucose-O-ω-saturated fatty acids of various chain lengths were synthesized and tested for their potential to activate GDP-inhibited uncoupling protein 1-dependent oxygen consumption in brown adipose tissue mitochondria, and the results were compared with equivalent non-modified fatty acid controls. Here we demonstrate that laurate (12C), palmitate (16C) and stearate (18C) could activate GDP-inhibited uncoupling protein 1-dependent oxygen consumption in brown adipose tissue mitochondria, whereas there was no activation with glucose-O-ω-laurate (12C), glucose-O-ω-palmitate (16C), glucose-O-ω-stearate (18C), glucose-O-ω-arachidate (20C) or arachidate alone. We conclude that non-flippable fatty acids cannot activate uncoupling protein 1 irrespective of chain length. Our data further undermine the cofactor activation model of uncoupling protein 1 function but are compatible with the model that uncoupling protein 1 functions by flipping long-chain fatty acid anions.
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22
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Liu J, Li J, Li WJ, Wang CM. The role of uncoupling proteins in diabetes mellitus. J Diabetes Res 2013; 2013:585897. [PMID: 23841103 PMCID: PMC3687498 DOI: 10.1155/2013/585897] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Accepted: 05/21/2013] [Indexed: 01/04/2023] Open
Abstract
Uncoupling proteins (UCPs) are anion carriers expressed in the mitochondrial inner membrane that uncouple oxygen consumption by the respiratory chain from ATP synthesis. The physiological functions of UCPs have long been debated since the new UCPs (UCP2 to 5) were discovered, and the role of UCPs in the pathogeneses of diabetes mellitus is one of the hottest topics. UCPs are thought to be activated by superoxide and then decrease mitochondrial free radicals generation; this may provide a protective effect on diabetes mellitus that is under the oxidative stress conditions. UCP1 is considered to be a candidate gene for diabetes because of its role in thermogenesis and energy expenditure. UCP2 is expressed in several tissues and acts in the negative regulation of insulin secretion by β-cells and in fatty acid metabolism. UCP3 plays a role in fatty acid metabolism and energy homeostasis and modulates insulin sensitivity. Several gene polymorphisms of UCP1, UCP2, and UCP3 were reported to be associated with diabetes. The progress in the role of UCP1, UCP2, and UCP3 on diabetes mellitus is summarized in this review.
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Affiliation(s)
- Jing Liu
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China
| | - Ji Li
- Department of Pharmacology and Toxicology, School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, NY 14214, USA
| | - Wen-Jian Li
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China
| | - Chun-Ming Wang
- School of Life Sciences, Lanzhou University, Lanzhou 730000, China
- *Chun-Ming Wang:
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23
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Clarke KJ, Porter RK. Uncoupling protein 1 dependent reactive oxygen species production by thymus mitochondria. Int J Biochem Cell Biol 2012; 45:81-9. [PMID: 23036787 DOI: 10.1016/j.biocel.2012.09.023] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2012] [Revised: 09/03/2012] [Accepted: 09/25/2012] [Indexed: 11/29/2022]
Abstract
We have previously shown that uncoupling protein 1 is present in thymus and has a role in T-cell development. As reactive oxygen species have been implicated in T-cell development, we set out to determine whether uncoupling protein 1 had the potential to regulate reactive oxygen species production in mitochondria isolated from thymus. This was achieved by inhibiting proton leak through uncoupling protein 1 using the purine nucleotide GDP and through ablation of uncoupling protein 1, measuring the amplex red sensitive reactive oxygen species production by mitochondria. In this work we demonstrate, for the first time, that uncoupling protein 1 has the potential to regulate reactive oxygen species production in thymus mitochondria. We also show that reverse electron transport is possible in thymus mitochondria respiring on succinate and glycerol-3-phosphate. The implications of this regulatory role for uncoupling protein 1 are discussed in the context of thymus function. This article is part of a Directed Issue entitled: Bioenergetic dysfunction, adaptation and therapy.
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Affiliation(s)
- Kieran J Clarke
- School of Biochemistry and Immunology, Trinity Institute of Biomedical Science, Trinity College Dublin, Ireland.
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24
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Porter RK. Studies on the function and regulation of mitochondrial uncoupling proteins. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 748:171-84. [PMID: 22729858 DOI: 10.1007/978-1-4614-3573-0_7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
Mitochondrial uncoupling proteins are members of the SLC25 family of solute carriers. Models of mitochondrial transporter function predict that uncoupling proteins are solute carriers. Evidence in the literature suggests that uncoupling proteins can transport protons, fatty acid anions, chloride anions, and recently the dicarboxylate succinate. Studies have also demonstrated that UCPs can be covalently modified and in some instances this covalent modification is needed to affect uncoupling function. The current evidence from functional analyses of mammalian uncoupling proteins is summarized in this chapter.
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Affiliation(s)
- Richard K Porter
- School of Biochemistry and Immunology, Trinity College Dublin, Dublin 2, Ireland.
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25
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Divakaruni AS, Humphrey DM, Brand MD. Fatty acids change the conformation of uncoupling protein 1 (UCP1). J Biol Chem 2012; 287:36845-53. [PMID: 22952235 DOI: 10.1074/jbc.m112.381780] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
UCP1 catalyzes proton leak across the mitochondrial inner membrane to disengage substrate oxidation from ATP production. It is well established that UCP1 is activated by fatty acids and inhibited by purine nucleotides, but precisely how this regulation occurs remains unsettled. Although fatty acids can competitively overcome nucleotide inhibition in functional assays, fatty acids have little effect on purine nucleotide binding. Here, we present the first demonstration that fatty acids induce a conformational change in UCP1. Palmitate dramatically changed the binding kinetics of 2'/3'-O-(N-methylanthraniloyl)-GDP, a fluorescently labeled nucleotide analog, for UCP1. Furthermore, palmitate accelerated the rate of enzymatic proteolysis of UCP1. The altered kinetics of both processes indicate that fatty acids change the conformation of UCP1, reconciling the apparent discrepancy between existing functional and ligand binding data. Our results provide a framework for how fatty acids and nucleotides compete to regulate the activity of UCP1.
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Affiliation(s)
- Ajit S Divakaruni
- Medical Research Council Mitochondrial Biology Unit, Cambridge CB2 0XY, United Kingdom.
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26
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Clarke KJ, Adams AE, Manzke LH, Pearson TW, Borchers CH, Porter RK. A role for ubiquitinylation and the cytosolic proteasome in turnover of mitochondrial uncoupling protein 1 (UCP1). BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2012; 1817:1759-67. [PMID: 22531154 DOI: 10.1016/j.bbabio.2012.03.035] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2012] [Revised: 03/23/2012] [Accepted: 03/29/2012] [Indexed: 11/19/2022]
Abstract
In this study we show that mitochondrial uncoupling protein 1 (UCP1) in brown adipose tissue (BAT) and thymus mitochondria can be ubiquitinylated and degraded by the cytosolic proteasome. Using a ubiquitin conjugating system, we show that UCP1 can be ubiquitinylated in vitro. We demonstrate that UCP1 is ubiquitinylated in vivo using isolated mitochondria from brown adipose tissue, thymus and whole brown adipocytes. Using an in vitro ubiquitin conjugating-proteasome degradation system, we show that the cytosolic proteasome can degrade UCP1 at a rate commensurate with the half-life of UCP1 (i.e. 30-72h in brown adipocytes and ~3h, in thymocytes). In addition, we demonstrate that the cytoplasmic proteasome is required for UCP1 degradation from mitochondria that the process is inhibited by the proteasome inhibitor MG132 and that dissipation of the mitochondrial membrane potential inhibits degradation of UCP1. There also appears to be a greater amount of ubiquitinylated UCP1 associated with BAT mitochondria from cold-acclimated animals. We have also identified (using immunoprecipitation coupled with mass spectrometry) ubiquitinylated proteins with molecular masses greater than 32kDa, as being UCP1. We conclude that there is a role for ubiquitinylation and the cytosolic proteasome in turnover of mitochondrial UCP1. This article is part of a Special Issue entitled: 17th European Bioenergetics Conference (EBEC 2012).
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Affiliation(s)
- Kieran J Clarke
- School of Biochemistry and Immunology, Trinity College Dublin, Dublin 2, Ireland
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27
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Identification and characterization of uncoupling protein 4 in fat body and muscle mitochondria from the cockroach Gromphadorhina cocquereliana. J Bioenerg Biomembr 2011; 43:717-27. [PMID: 21997226 DOI: 10.1007/s10863-011-9385-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2011] [Accepted: 09/13/2011] [Indexed: 12/23/2022]
Abstract
We have identified and characterized an uncoupling protein in mitochondria isolated from leg muscle and from fat body, an insect analogue tissue of mammalian liver and adipose tissue, of the cockroach Gromphadorhina coquereliana (GcUCP). This is the first functional characterization of UCP activity in isolated insect mitochondria. Bioenergetic studies clearly indicate UCP function in both insect tissues. In resting (non-phosphorylating) mitochondria, cockroach GcUCP activity was stimulated by the addition of micromolar concentrations of palmitic acid and inhibited by the purine nucleotide GTP. Moreover, in phosphorylating mitochondria, GcUCP activity was able to divert energy from oxidative phosphorylation. Functional studies indicate a higher activity of GcUCP-mediated uncoupling in cockroach muscle mitochondria compared to fat body mitochondria. GcUCP activation by palmitic acid resulted in a decrease in superoxide anion production, suggesting that protection against mitochondrial oxidative stress may be a physiological role of UCPs in insects. GcUCP protein was immunodetected using antibodies raised against human UCP4 as a single band of around 36 kDa. GcUCP protein expression in cockroach muscle mitochondria was significantly higher compared to mitochondria isolated from fat body. LC-MS/MS analyses revealed 100% sequence identities for peptides obtained from GcUCP to UCP4 isoforms from D. melanogaster (the highest homology), human, rat or other insect mitochondria. Therefore, it can be proposed that cockroach GcUCP corresponds to the UCP4 isoforms of other animals.
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28
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Divakaruni AS, Brand MD. The regulation and physiology of mitochondrial proton leak. Physiology (Bethesda) 2011; 26:192-205. [PMID: 21670165 DOI: 10.1152/physiol.00046.2010] [Citation(s) in RCA: 289] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Mitochondria couple respiration to ATP synthesis through an electrochemical proton gradient. Proton leak across the inner membrane allows adjustment of the coupling efficiency. The aim of this review is threefold: 1) introduce the unfamiliar reader to proton leak and its physiological significance, 2) review the role and regulation of uncoupling proteins, and 3) outline the prospects of proton leak as an avenue to treat obesity, diabetes, and age-related disease.
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Affiliation(s)
- Ajit S Divakaruni
- Medical Research Council Mitochondrial Biology Unit, Wellcome Trust/MRC Building, Cambridge, United Kingdom
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29
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Absence of mitochondrial uncoupling protein 3: effect on thymus and spleen in the fed and fasted mice. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2011; 1807:1064-74. [PMID: 21689632 DOI: 10.1016/j.bbabio.2011.06.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2011] [Revised: 06/04/2011] [Accepted: 06/06/2011] [Indexed: 11/21/2022]
Abstract
Mitochondrial uncoupling protein 3 (UCP3) is constitutively expressed in mitochondria from thymus and spleen of mice, and confocal microscopy has been used to visualize UCP3 in situ in mouse thymocytes. UCP3 is present in mitochondria of thymus and spleen up to at least 16 weeks after birth, but levels decrease by a half in thymus and a fifth in spleen after three weeks, probably reflecting the suckling to weaning transition. UCP3 protein levels increase approximately 3-fold in thymus on starvation, but expression levels in spleen were unaffected by starvation. Lack of UCP3 had little effect on thymus mass or thymocyte number. However, lack of UCP3 affected spleen mass and splenocyte number (in the fasted state) and results in reduced CD4+ single positive cell numbers and reduced double negative cells in the thymus, but as a 2-fold increase in the proportion of CD4(+), CD8(+) and DP cells in spleen. Starvation attenuates these proportionate differences in the spleen. A lack of UCP3 had no apparent effect on basal oxygen consumption of thymocytes or splenocytes or on oxygen consumption due to mitochondrial proton leak. Splenocytes from UCP3 knock-out mice are also more resistant to apoptosis than those from wild-type mice. Overall we can conclude that UCP3 affects thymocyte and spleen cell profiles in the fed and fasted states.
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Chen K, Sun G, Lv Z, Wang C, Jiang X, Li D, Zhang C. Molecular cloning of amphioxus uncoupling protein and assessment of its uncoupling activity using a yeast heterologous expression system. Biochem Biophys Res Commun 2010; 400:701-6. [PMID: 20816931 DOI: 10.1016/j.bbrc.2010.08.131] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2010] [Accepted: 08/29/2010] [Indexed: 11/19/2022]
Abstract
The present study describes the molecular cloning of a novel cDNA fragment from amphioxus (Branchiostoma belcheri) encoding a 343-amino acid protein that is highly homologous to human uncoupling proteins (UCP), this protein is therefore named amphioxus UCP. This amphioxus UCP shares more homology with and is phylogenetically more related to mammalian UCP2 as compared with UCP1. To further assess the functional similarity of amphioxus UCP to mammalian UCP1 and -2, the amphioxus UCP, rat UCP1, and human UCP2 were separately expressed in Saccharomyces cerevisiae, and the recombinant yeast mitochondria were isolated and assayed for the state 4 respiration rate and proton leak, using pYES2 empty vector as the control. UCP1 increased the state 4 respiration rate by 2.8-fold, and the uncoupling activity was strongly inhibited by GDP, while UCP2 and amphioxus UCP only increased the state 4 respiration rate by 1.5-fold and 1.7-fold in a GDP-insensitive manner, moreover, the proton leak kinetics of amphioxus UCP was very similar to UCP2, but much different from UCP1. In conclusion, the amphioxus UCP has a mild, unregulated uncoupling activity in the yeast system, which resembles mammalian UCP2, but not UCP1.
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Affiliation(s)
- Kun Chen
- Jiangsu Diabetes Research Center, State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, Jiangsu, China
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Aguirre E, Cadenas S. GDP and carboxyatractylate inhibit 4-hydroxynonenal-activated proton conductance to differing degrees in mitochondria from skeletal muscle and heart. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2010; 1797:1716-26. [PMID: 20599679 DOI: 10.1016/j.bbabio.2010.06.009] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2010] [Revised: 06/15/2010] [Accepted: 06/19/2010] [Indexed: 12/17/2022]
Abstract
The lipid peroxidation product 4-hydroxynonenal (HNE) increases the proton conductance of the inner mitochondrial membrane through effects on uncoupling proteins (UCPs) and the adenine nucleotide translocase (ANT); however, the relative contribution of the two carriers to these effects is unclear. To clarify this we isolated mitochondria from skeletal muscle and heart of wild-type and Ucp3 knockout (Ucp3KO) mice. To increase UCP3 expression, some mice were i.p. injected with LPS (12mg/kg body weight). In spite of the increased UCP3 expression levels, basal proton conductance did not change. HNE increased the proton conductance of skeletal muscle and heart mitochondria. In skeletal muscle, this increase was lower in Ucp3KO mice and higher in LPS-treated wild-type mice, and was partially abolished by GDP (UCPs inhibitor) and completely abolished by carboxyatractylate (ANT inhibitor) or addition of both inhibitors. GDP had no effect on HNE-induced conductance in heart mitochondria, but carboxyatractylate or administration of both inhibitors had a partial effect. GDP-mediated inhibition of HNE-activated proton conductance in skeletal muscle mitochondria was not observed in Ucp3KO mice, indicating that GDP is specific for UCP3, at least in muscle. Carboxyatractylate was able to inhibit UCP3, probably through an indirect mechanism. Our results are consistent with the conclusion that, in skeletal muscle, HNE-induced increase in proton conductance is mediated by UCP3 (30%) and ANT, whereas in the heart the increase is mediated by ANT and other carriers, possibly including UCP3.
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Affiliation(s)
- Enara Aguirre
- Department of Regenerative Cardiology, Centro Nacional de Investigaciones Cardiovasculares (CNIC), Melchor Fernández Almagro 3, 28029 Madrid, Spain
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Adams AE, Kelly OM, Porter RK. Absence of mitochondrial uncoupling protein 1 affects apoptosis in thymocytes, thymocyte/T-cell profile and peripheral T-cell number. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2010; 1797:807-16. [PMID: 20417612 DOI: 10.1016/j.bbabio.2010.04.016] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2009] [Revised: 04/14/2010] [Accepted: 04/14/2010] [Indexed: 10/19/2022]
Abstract
Our laboratory has previously demonstrated the presence of constitutively expressed mitochondrial uncoupling protein 1 in mouse thymocytes. In our endeavours to understand the role of mitochondrial uncoupling protein 1 in thymocyte function, we compared cell profiles in thymus and spleen of wild-type with those of UCP 1 knock-out mice, which in turn led to comparative investigations of apoptotic potential in thymocytes from these mice. We demonstrate that spleen cell numbers were reduced approximately 3-fold in UCP 1 knock-out mice compared to wild-type mice. We record a halving of CD8 single positive cell numbers in thymus with a significant incremental increase in CD4/CD8 double positives cell numbers in the thymus of UCP 1 knock-out mice compared to wild-type mice. These data are mirrored by an approximate halving of CD8 single positive cell numbers and a doubling of CD4/CD8 double positive cell numbers in the spleen of UCP 1 knock-out mice compared to wild-type mice. These differences are most probably explained by our observations of decreased apoptotic potential and higher ATP levels in thymocytes of UCP 1 knock-out mice when compared to wild-type controls. We conclude that constitutively expressed UCP 1 is a factor in determining T-cell population selection in mice.
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Affiliation(s)
- Alison E Adams
- School of Biochemistry and Immunology, Trinity College Dublin, Dublin 2, Ireland
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Azzu V, Jastroch M, Divakaruni AS, Brand MD. The regulation and turnover of mitochondrial uncoupling proteins. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2010; 1797:785-91. [PMID: 20211596 DOI: 10.1016/j.bbabio.2010.02.035] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2009] [Revised: 02/23/2010] [Accepted: 02/25/2010] [Indexed: 12/15/2022]
Abstract
Uncoupling proteins (UCP1, UCP2 and UCP3) are important in regulating cellular fuel metabolism and as attenuators of reactive oxygen species production through strong or mild uncoupling. The generic function and broad tissue distribution of the uncoupling protein family means that they are increasingly implicated in a range of pathophysiological processes including obesity, insulin resistance and diabetes mellitus, neurodegeneration, cardiovascular disease, immunity and cancer. The significant recent progress describing the turnover of novel uncoupling proteins, as well as current views on the physiological roles and regulation of UCPs, is outlined.
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Affiliation(s)
- Vian Azzu
- Medical Research Council Mitochondrial Biology Unit, Hills Road, Cambridge CB2 0XY, UK.
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Abstract
UCP3 (uncoupling protein 3) and its homologues UCP2 and UCP1 are regulators of mitochondrial function. UCP2 is known to have a short half-life of approx. 1 h, owing to its rapid degradation by the cytosolic 26S proteasome, whereas UCP1 is turned over much more slowly by mitochondrial autophagy. In the present study we investigate whether UCP3 also has a short half-life, and whether the proteasome is involved in UCP3 degradation. UCP3 half-life was examined in the mouse C2C12 myoblast cell line by inhibiting protein synthesis with cycloheximide and monitoring UCP3 protein levels by immunoblot analysis. We show that UCP3 has a short half-life of 0.5-4 h. Rapid degradation was prevented by a cocktail of proteasome inhibitors, supporting a proteasomal mechanism for turnover. In addition, this phenotype is recapitulated in vitro: UCP3 was degraded in mitochondria isolated from rat skeletal muscle or brown adipose tissue with a half-life of 0.5-4 h, but only in the presence of a purified 26S proteasomal fraction. This in vitro proteolysis was also sensitive to proteasome inhibition. This phenotype is in direct contrast with the related proteins UCP1 and the adenine nucleotide translocase, which have long half-lives. Therefore UCP3 is turned over rapidly in multiple cell types in a proteasome-dependent manner.
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Mujahid A, Akiba Y, Toyomizu M. Olive oil-supplemented diet alleviates acute heat stress-induced mitochondrial ROS production in chicken skeletal muscle. Am J Physiol Regul Integr Comp Physiol 2009; 297:R690-8. [DOI: 10.1152/ajpregu.90974.2008] [Citation(s) in RCA: 101] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
We have previously shown that avian uncoupling protein (avUCP) is downregulated on exposure to acute heat stress, stimulating mitochondrial reactive oxygen species (ROS) production and oxidative damage. In this study, we investigated whether upregulation of avUCP could attenuate oxidative damage caused by acute heat stress. Broiler chickens ( Gallus gallus) were fed either a control diet or an olive oil-supplemented diet (6.7%), which has been shown to increase the expression of UCP3 in mammals, for 8 days and then exposed either to heat stress (34°C, 12 h) or kept at a thermoneutral temperature (25°C). Skeletal muscle mitochondrial ROS (measured as H2O2) production, avUCP expression, oxidative damage, mitochondrial membrane potential, and oxygen consumption were studied. We confirmed that heat stress increased mitochondrial ROS production and malondialdehyde levels and decreased the amount of avUCP. As expected, feeding birds an olive oil-supplemented diet increased the expression of avUCP in skeletal muscle mitochondria and decreased ROS production and oxidative damage. Studies on mitochondrial function showed that heat stress increased membrane potential in state 4, which was reversed by feeding birds an olive oil-supplemented diet, although no differences in basal proton leak were observed between control and heat-stressed groups. These results show that under heat stress, mitochondrial ROS production and olive oil-induced reduction of ROS production may occur due to changes in respiratory chain activity as well as avUCP expression in skeletal muscle mitochondria.
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Session on ‘Obesity’ Adipose tissue development, nutrition in early life and its impact on later obesity. Proc Nutr Soc 2009; 68:321-6. [DOI: 10.1017/s0029665109001402] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
It is now apparent that one key factor determining the current obesity epidemic within the developed world is the extent to which adipose tissue growth and function can be reset in early life. Adipose tissue can be either brown or white, with brown fat being characterised as possessing a unique uncoupling protein (uncoupling protein 1) that enables the rapid generation of heat by non-shivering thermogenesis. In large mammals this function is recruited at approximately the time of birth, after which brown fat is lost, not normally reappearing again throughout the life cycle. The origin and developmental regulation of brown fat in large mammals is therefore very different from that of small mammals in which brown fat is retained throughout the life cycle and may have the same origin as muscle cells. In contrast, white adipose tissue increases in mass after birth, paralleled by a rise in glucocorticoid action and macrophage accumulation. This process can be reset by changes in the maternal nutritional environment, with the magnitude of response being further determined by the timing at which such a challenge is imposed. Importantly, the long-term response within white adipocytes can occur in the absence of any change in total fat mass. The present review therefore emphasises the need to further understand the developmental regulation of the function of fat through the life cycle in order to optimise appropriate and sustainable intervention strategies necessary not only to prevent obesity in the first place but also to reverse excess fat mass in obese individuals.
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Alán L, Smolková K, Kronusová E, Santorová J, Jezek P. Absolute levels of transcripts for mitochondrial uncoupling proteins UCP2, UCP3, UCP4, and UCP5 show different patterns in rat and mice tissues. J Bioenerg Biomembr 2009; 41:71-8. [PMID: 19242784 DOI: 10.1007/s10863-009-9201-2] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2008] [Accepted: 01/29/2009] [Indexed: 12/11/2022]
Abstract
Existing controversies led us to analyze absolute mRNA levels of mitochondrial uncoupling proteins (UCP1-UCP5). Individual UCP isoform mRNA levels varied by up to four orders of magnitude in rat and mouse tissues. UCP2 mRNA content was relatively high (0.4 to 0.8 pg per 10 ng of total mRNA) in rat spleen, rat and mouse lung, and rat heart. Levels of the same order of magnitude were found for UCP3 mRNA in rat and mouse skeletal muscle, for UCP4 and UCP5 mRNA in mouse brain, and for UCP2 and UCP5 mRNA in mouse white adipose tissue. Significant differences in pattern were found for rat vs. mouse tissues, such as the dominance of UCP3/UCP5 vs. UCP2 transcript in mouse heart and vice versa in rat heart; or UCP2 (UCP5) dominance in rat brain contrary to 10-fold higher UCP4 and UCP5 dominance in mouse brain. We predict high antioxidant/antiapoptotic UCP function in tissues with higher UCP mRNA content.
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Affiliation(s)
- Lukás Alán
- Department of Membrane Transport Biophysics, No.75, Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic.
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38
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Samper E, Morgado L, Estrada JC, Bernad A, Hubbard A, Cadenas S, Melov S. Increase in mitochondrial biogenesis, oxidative stress, and glycolysis in murine lymphomas. Free Radic Biol Med 2009; 46:387-96. [PMID: 19038329 PMCID: PMC2665299 DOI: 10.1016/j.freeradbiomed.2008.10.036] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2008] [Revised: 09/05/2008] [Accepted: 10/13/2008] [Indexed: 11/24/2022]
Abstract
Lymphomas adapt to their environment by undergoing a complex series of biochemical changes that are currently not well understood. To better define these changes, we examined the gene expression and gene ontology profiles of thymic lymphomas from a commonly used model of carcinogenesis, the p53(-/-) mouse. These tumors show a highly significant upregulation of mitochondrial biogenesis, mitochondrial protein translation, mtDNA copy number, reactive oxygen species, antioxidant defenses, proton transport, ATP synthesis, hypoxia response, and glycolysis, indicating a fundamental change in the bioenergetic profile of the transformed T cell. Our results suggest that T cell tumorigenesis involves a simultaneous upregulation of mitochondrial biogenesis, mitochondrial respiration, and glycolytic activity. These processes would allow cells to adapt to the stressful tumor environment by facilitating energy production and thereby promote tumor growth. Understanding these adaptations is likely to result in improved therapeutic strategies for this tumor type.
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Affiliation(s)
- Enrique Samper
- The Buck Institute for Age Research, Novato, CA 94945, USA.
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39
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Porter RK. Uncoupling protein 1: a short-circuit in the chemiosmotic process. J Bioenerg Biomembr 2008; 40:457-61. [DOI: 10.1007/s10863-008-9172-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2008] [Accepted: 08/01/2008] [Indexed: 11/28/2022]
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40
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Mujahid A, Furuse M. Homeothermy in neonatal chicks exposed to low environmental temperature with or without intracerebroventricular administration of corticotropin-releasing factor. FEBS Lett 2008; 582:3052-60. [DOI: 10.1016/j.febslet.2008.07.050] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2008] [Revised: 07/22/2008] [Accepted: 07/28/2008] [Indexed: 10/21/2022]
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41
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Energization-dependent endogenous activation of proton conductance in skeletal muscle mitochondria. Biochem J 2008; 412:131-9. [PMID: 18251717 PMCID: PMC2474556 DOI: 10.1042/bj20080006] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Leak of protons into the mitochondrial matrix during substrate oxidation partially uncouples electron transport from phosphorylation of ADP, but the functions and source of basal and inducible proton leak in vivo remain controversial. In the present study we describe an endogenous activation of proton conductance in mitochondria isolated from rat and mouse skeletal muscle following addition of respiratory substrate. This endogenous activation increased with time, required a high membrane potential and was diminished by high concentrations of serum albumin. Inhibition of this endogenous activation by GDP [classically considered specific for UCPs (uncoupling proteins)], carboxyatractylate and bongkrekate (considered specific for the adenine nucleotide translocase) was examined in skeletal muscle mitochondria from wild-type and Ucp3-knockout mice. Proton conductance through endogenously activated UCP3 was calculated as the difference in leak between mitochondria from wild-type and Ucp3-knockout mice, and was found to be inhibited by carboxyatractylate and bongkrekate, but not GDP. Proton conductance in mitochondria from Ucp3-knockout mice was strongly inhibited by carboxyatractylate, bongkrekate and partially by GDP. We conclude the following: (i) at high protonmotive force, an endogenously generated activator stimulates proton conductance catalysed partly by UCP3 and partly by the adenine nucleotide translocase; (ii) GDP is not a specific inhibitor of UCP3, but also inhibits proton translocation by the adenine nucleotide translocase; and (iii) the inhibition of UCP3 by carboxyatractylate and bongkrekate is likely to be indirect, acting through the adenine nucleotide translocase.
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42
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Carroll AM, Porter RK, Morrice NA. Identification of serine phosphorylation in mitochondrial uncoupling protein 1. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2008; 1777:1060-5. [PMID: 18486593 DOI: 10.1016/j.bbabio.2008.04.030] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2008] [Revised: 04/11/2008] [Accepted: 04/22/2008] [Indexed: 10/22/2022]
Abstract
Native uncoupling protein 1 was purified from rat brown adipose tissue of cold-acclimated rats and rats kept at room temperature, in the presence of phosphatase inhibitors. The purified protein from cold-acclimated animals was digested with trypsin and immobilized metal affinity chromatography was used to select for phosphopeptides. Tandem mass spectroscopic analysis of the peptides derived from uncoupling protein 1, suggests phosphorylation of serine 3 or 4 and identified phosphorylation of serine 51. Furthermore, we were able to demonstrate that antibodies to phosphoserine detect full-length UCP 1 and that the proportion of phosphoserine on UCP1, purified from cold-acclimated rats, was significantly greater than that on UCP 1 from rats kept at room temperature (90+/-4% compared to 62+/-8%, p=0.013), respectively). We conclude that uncoupling protein 1 is a phosphoprotein and that cold-acclimation increases the proportion of UCP1 that is serine phosphorylated.
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Affiliation(s)
- Audrey M Carroll
- School of Biochemistry and Immunology, Trinity College Dublin, Dublin 2, UK
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43
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Adams AE, Carroll AM, Fallon PG, Porter RK. Mitochondrial uncoupling protein 1 expression in thymocytes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2008; 1777:772-6. [PMID: 18471433 DOI: 10.1016/j.bbabio.2008.04.020] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2008] [Revised: 04/07/2008] [Accepted: 04/10/2008] [Indexed: 11/19/2022]
Abstract
Using an antibody specific and selective to mitochondrial uncoupling protein 1 (UCP1) peptide, this study confirms the observation that UCP 1 is present in thymocytes isolated from UCP 1 wild-type, but not UCP 1 knock-out mice. UCP 1 is also shown to be present in thymocytes isolated from rat. It was also demonstrated that an antibody raised to the full-length UCP 1 protein appears to be non-specific for UCP 1, as it detects protein in UCP 1 wild-type and UCP 1 knock-out mice, protein in mitochondria isolated from brown adipose tissue of both UCP 1 wild-type and UCP 1 knock-out mice, as well as detecting protein in mitochondria isolated from rat spleen, kidney, skeletal muscle and liver, tissues that do not express UCP 1. We were also able to show that CIDEA, a soluble protein with a suggested role in regulating UCP 1 function, is equally abundant in thymocytes from UCP 1 wild-type and UCP 1 knock-out mice. Taken together our data demonstrate that (a) UCP 1 is present in rat and mouse thymocytes, (b) that the antibody to full-length UCP 1 is not specific for UCP 1 and (c) that the absence of UCP 1 does not affect native expression of CIDEA in thymocytes.
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Affiliation(s)
- Alison E Adams
- School of Biochemistry and Immunology, Trinity College Dublin, Dublin 2, Ireland
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Images of mitochondrial UCP 1 in mouse thymocytes using confocal microscopy. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2007; 1777:115-7. [PMID: 17996719 DOI: 10.1016/j.bbabio.2007.10.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2007] [Revised: 10/05/2007] [Accepted: 10/08/2007] [Indexed: 11/22/2022]
Abstract
The aim of this study was to demonstrate the constitutive expression of mitochondrial uncoupling protein 1 (UCP 1) in pure thymocytes using laser scanning confocal microscopic imagery. To that end we probed thymocytes from UCP 1 knock-out and wild-type mice. Mitochondrial location in thymocytes was determined using Mitotracker Red and the nucleus was labelled using Hoescht stain. We demonstrate that all cells investigated were thymocytes as determined by a monoclonal antibody specific for the thymocyte surface marker Thy 1 (CD90) pre-coupled to a fluorescent labelled (Alexa 448, green). Using a primary peptide antibody specific to UCP 1, and secondary fluorescently labelled (Alexa 647, magenta) antibody, we were able to demonstrate that UCP 1 is associated with mitochondria in thymocytes from UCP 1 wild-type mice but not thymocytes from UCP1-knock-out mice. These are the first images demonstrating the presence of UCP 1 in thymocyte mitochondria, in situ, and the first to clearly demonstrate UCP 1 expression in cells other than brown adipocytes. We conclude that mouse thymocytes contain UCP 1 in their mitochondria.
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45
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Beck V, Jabůrek M, Demina T, Rupprecht A, Porter RK, Jezek P, Pohl EE. Polyunsaturated fatty acids activate human uncoupling proteins 1 and 2 in planar lipid bilayers. FASEB J 2007; 21:1137-44. [PMID: 17242157 DOI: 10.1096/fj.06-7489com] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Uncoupling proteins 1 (UCP1) and 2 (UCP2) belong to the family of mitochondrial anion transporters and share 59% sequence identity with each other. Whereas UCP1 was shown to be responsible for the rapid production of heat in brown adipose tissue, the primary function and transport properties of ubiquitously expressed UCP2 are controversially discussed. Here, for the first time, the activation pattern of the recombinant human UCP2 in comparison to the recombinant human UCP1 are studied using a well-defined system of planar lipid bilayers. It is shown that despite apparently different physiological functions, hUCP2 exhibited its protonophoric function similar to hUCP1--exclusively in the presence of long-chain fatty acids (FA). The calculated hUCP2 transport rate of 4.5 s(-1) is the same order of magnitude, as shown previously for UCP1. It leads to the conclusion that the differences in the activity of both proteins in living mitochondria are based exclusively on their different expression level. Both proteins are activated much more effectively by polyunsaturated than by saturated FA. The proton and total membrane conductances increased in the range palmitic < oleic < eicosatrienoic < linoleic < retinoic < arachidonic acids. The higher uncoupling protein (UCP)-dependent conductance in the presence of polyunsaturated FA is explained on the basis of the FA cycling hypothesis.
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Affiliation(s)
- Valeri Beck
- Institute of Cell Biology and Neurobiology, Charité Universitätsmedizin, Charitéplatz 1, 10117 Berlin, Germany
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46
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Frontini A, Rousset S, Cassard-Doulcier AM, Zingaretti C, Ricquier D, Cinti S. Thymus Uncoupling Protein 1 Is Exclusive to Typical Brown Adipocytes and Is Not Found in Thymocytes. J Histochem Cytochem 2006; 55:183-9. [PMID: 17101729 DOI: 10.1369/jhc.6a7013.2006] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
A large number of studies have established the mitochondrial uncoupling protein UCP1 as a specific marker of brown adipocytes, where it controls energy dissipation of fatty acid oxidation as heat in response to physiological requirements. Following the recent report of the detection of UCP1 in thymocytes of rats and mice, we reinvestigated its presence in thymus. Light microscopy and immunohistochemical analysis demonstrated that the UCP1 signal in thymus is entirely explained by the presence of typical brown adipocytes around the gland. Staining for UCP1 was not observed in thymocytes. Similarly, UCP1 failed to be observed in rat spleen, skeletal muscle, stomach, intestine, or uterus, even after exposure of animals to the cold. These data confirm the specificity of UCP1 expression in the thermogenic brown adipocytes and argue against a direct role for this mitochondrial transporter in immune cells. Whether brown adipocytes adjacent to thymic lobes play a role in thymus physiology remains to be investigated.
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Affiliation(s)
- Andrea Frontini
- Institute of Normal Human Morphology, Marche Polytechnic University, Via Tronto, 10/A, 60020 Ancona, Italy
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47
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Brennan CM, Breen EP, Porter RK. Cold acclimation and oxygen consumption in the thymus. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2006; 1757:1463-8. [PMID: 17022934 DOI: 10.1016/j.bbabio.2006.08.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2005] [Revised: 08/08/2006] [Accepted: 08/10/2006] [Indexed: 11/19/2022]
Abstract
Mitochondrial uncoupling protein 1 is usually associated with brown adipose tissue but has recently been discovered in rat and mouse thymus. We wished to establish whether there was a thermogenic role for UCP 1 in thymus and thus examined the effect of 5 weeks cold-acclimation on rat thymus tissue abundance, thymocyte oxygen consumption, thymus mitochondrial abundance, uncoupling protein 1 expression and function. We found that thymocytes from cold-acclimated rats had oxygen consumption rates 8 times less than those from rats held at room temperature and that thymocytes from cold-acclimated rats or rats kept at room temperature were noradrenaline insensitive. In addition, we found that thymus tissue or mitochondrial abundance was not increased after cold-acclimation. However uncoupling protein 1 expression per unit mass of mitochondria was increased after cold-acclimation, as determined by immunoblotting (approximately 1.7-fold) and GDP binding (approximately 1.5-fold). Consistent with our protein expression data, we also observed an increased, state 4 (approximately 1.5-fold), GDP-inhibitable (approximately 1.3-fold) and palmitate activatable (approximately 1.6-fold) oxygen consumption rates in isolated thymus mitochondria. However, extrapolation of our data showed that cold-acclimation only increased the amount of UCP 1 per gram of thymus tissue approximately 1.2-fold. Taken together, we conclude that UCP 1 does not have a thermogenic role in thymus.
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Affiliation(s)
- Clare M Brennan
- School of Biochemistry and Immunology, Trinity College Dublin, Dublin 2, Ireland
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48
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Cannon B, Shabalina IG, Kramarova TV, Petrovic N, Nedergaard J. Uncoupling proteins: a role in protection against reactive oxygen species--or not? BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2006; 1757:449-58. [PMID: 16806053 DOI: 10.1016/j.bbabio.2006.05.016] [Citation(s) in RCA: 134] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Received: 01/13/2006] [Revised: 04/28/2006] [Accepted: 05/10/2006] [Indexed: 10/24/2022]
Abstract
A physiological function of the original uncoupling protein, UCP1, is well established: UCP1 is the molecular background for nonshivering thermogenesis. The functions of the "novel" UCPs, UCP2 and UCP3, are still not established. Recent discussions imply that all UCPs may play a role in protection against reactive oxygen species (ROS). Here we examine critically the evidence that UCP1, UCP2 and UCP3 are stimulated by ROS (superoxide) or ROS products (4-hydroxy-2-nonenal), and that the UCPs actually diminish oxidative damage. We conclude that, concerning UCP1, it is unlikely that it has such a role; concerning UCP2/UCP3, most evidence for physiologically significant roles in this respect is still circumstantial.
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Affiliation(s)
- Barbara Cannon
- The Wenner-Gren Institute, The Arrhenius Laboratories F3, Stockholm University, SE-106 91 Stockholm, Sweden.
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Dlasková A, Spacek T, Skobisová E, Santorová J, Jezek P. Certain aspects of uncoupling due to mitochondrial uncoupling proteins in vitro and in vivo. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2006; 1757:467-73. [PMID: 16781660 DOI: 10.1016/j.bbabio.2006.05.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2006] [Revised: 04/21/2006] [Accepted: 05/05/2006] [Indexed: 01/12/2023]
Abstract
Thermogenic uncoupling has been proven only for UCP1 in brown adipose tissue. All other isoforms of UCPs are potentially acting in suppression of mitochondrial reactive oxygen species (ROS) production. In this contribution we show that BAT mitochondria can be uncoupled by lauric acid in the range of approximately 100 nM when endogenous fatty acids are combusted by carnitine cycle and beta-oxidation is properly separated from the uncoupling effect. Respiration increased up to 3 times when related to the lowest fatty acid content (BSA present plus carnitine cycle). We also illustrated that any effect leading to more coupled states leads to enhanced H2O2 generation and any effect resulting in uncoupling gives reduced H2O2 generation in BAT mitochondria. Finally, we report doubling of plant UCP transcript in cells as well as amount of protein detected by 3H-GTP-binding sites in mitochondria of shoots and roots of maize seedlings subjected to the salt stress.
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Affiliation(s)
- Andrea Dlasková
- Department No.75, Membrane Transport Biophysics, Institute of Physiology, Academy of Sciences of the Czech Republic, Vídenská 1083, 14220 Prague 4, Czech Republic
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Porter RK. A new look at UCP 1. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2006; 1757:446-8. [PMID: 16730638 DOI: 10.1016/j.bbabio.2006.04.012] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2006] [Revised: 03/31/2006] [Accepted: 04/07/2006] [Indexed: 10/24/2022]
Abstract
There has been a resurgence of interest in mitochondrial uncoupling protein 1 due to a desire to understand the regulation of the prominent role it plays in control of metabolic flux in brown adipose tissue and non-shivering thermogenesis, combined with the fact that UCP 1 acts as a paradigm for other novel less abundant uncoupling proteins. In this manuscript, we review the recent evidence for detection, purification, identification and function of UCP 1 in thymus mitochondria. In addition, we review the two proposed mechanisms for fatty acid dependent UCP 1 activity, namely (a) the flippase (flip-flop) model and (b) the cofactor/activation model, and the implication for these models of recent data showing that glucose-O-omega-palmitate cannot facilitate UCP 1 activity.
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Affiliation(s)
- Richard K Porter
- School of Biochemistry and Immunology, Trinity College Dublin, Dublin 2, Ireland.
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