1
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Xuan MF, Luo ZB, Han SZ, Li ZY, Gao K, Liu XY, Chang SY, Jin ZY, Choe HM, Paek HJ, Quan BH, Yin XJ, Kang JD. Skeletal muscle-secreted myokine interleukin-6 induces white adipose tissue conversion into beige adipose tissue in myostatin gene knockout pigs. Domest Anim Endocrinol 2022; 78:106679. [PMID: 34715416 DOI: 10.1016/j.domaniend.2021.106679] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2021] [Revised: 08/31/2021] [Accepted: 09/01/2021] [Indexed: 11/03/2022]
Abstract
Myostatin (MSTN) is primarily expressed in skeletal muscle and plays an important role in the regulation of muscle growth and development as well as fat deposition; however, little is known about the molecular mechanism through which MSTN regulates body fat deposition. Therefore, in this study, we sought to identify the signaling pathways through which MSTN regulates fat accumulation in pigs. MSTN knockout (MSTN-/-) pigs showed increased muscle mass, decreased fat mass, and a leaner body composition. In this study, we found that the adipose tissue of MSTN-/- pigs exhibits the characteristics of beige adipose tissue, and the mRNA expression levels of beige adipose marker genes, including UCP3, Cidea, and CD137, were significantly increased. Remarkably, the observed beige phenotype was not adipocyte autonomous but rather caused by muscle-secreted myokine interleukin (IL)-6. This occurrence results in increased AMP-activated protein kinase (AMPK) phosphorylation in adipose tissue, which subsequently activates peroxisome proliferator-activated receptor gamma coactivator 1α and the conversion of white adipocytes to beige in pigs. Therefore, we concluded that MSTN deficiency leads to increased IL-6 secretion in skeletal muscle and activates AMPK in adipocytes, thereby increasing the beige adipose tissue in MSTN-/- pigs.
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Affiliation(s)
- M-F Xuan
- Department of Animal Science, Agricultural College, Yanbian University, Yanji, Jilin, 133002, China
| | - Z-B Luo
- Department of Animal Science, Agricultural College, Yanbian University, Yanji, Jilin, 133002, China
| | - S-Z Han
- Department of Animal Science, Agricultural College, Yanbian University, Yanji, Jilin, 133002, China
| | - Z-Y Li
- Department of Animal Science, Agricultural College, Yanbian University, Yanji, Jilin, 133002, China
| | - K Gao
- Department of Animal Science, Agricultural College, Yanbian University, Yanji, Jilin, 133002, China
| | - X-Y Liu
- Department of Animal Science, Agricultural College, Yanbian University, Yanji, Jilin, 133002, China
| | - S-Y Chang
- Department of Animal Science, Agricultural College, Yanbian University, Yanji, Jilin, 133002, China
| | - Z-Y Jin
- Department of Animal Science, Agricultural College, Yanbian University, Yanji, Jilin, 133002, China
| | - H-M Choe
- Department of Animal Science, Agricultural College, Yanbian University, Yanji, Jilin, 133002, China
| | - H-J Paek
- Department of Animal Science, Agricultural College, Yanbian University, Yanji, Jilin, 133002, China
| | - B-H Quan
- Department of Animal Science, Agricultural College, Yanbian University, Yanji, Jilin, 133002, China; Jilin Provincial Key Laboratory of Transgenic Animal and Embryo Engineering, Yanbian University, Yanji, Jilin, 133002, China
| | - X-J Yin
- Department of Animal Science, Agricultural College, Yanbian University, Yanji, Jilin, 133002, China; Jilin Provincial Key Laboratory of Transgenic Animal and Embryo Engineering, Yanbian University, Yanji, Jilin, 133002, China.
| | - J-D Kang
- Department of Animal Science, Agricultural College, Yanbian University, Yanji, Jilin, 133002, China; Jilin Provincial Key Laboratory of Transgenic Animal and Embryo Engineering, Yanbian University, Yanji, Jilin, 133002, China.
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2
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Mitochondrial Uncoupling Proteins (UCP1-UCP3) and Adenine Nucleotide Translocase (ANT1) Enhance the Protonophoric Action of 2,4-Dinitrophenol in Mitochondria and Planar Bilayer Membranes. Biomolecules 2021; 11:biom11081178. [PMID: 34439844 PMCID: PMC8392417 DOI: 10.3390/biom11081178] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 07/30/2021] [Accepted: 08/04/2021] [Indexed: 11/30/2022] Open
Abstract
2,4-Dinitrophenol (DNP) is a classic uncoupler of oxidative phosphorylation in mitochondria which is still used in “diet pills”, despite its high toxicity and lack of antidotes. DNP increases the proton current through pure lipid membranes, similar to other chemical uncouplers. However, the molecular mechanism of its action in the mitochondria is far from being understood. The sensitivity of DNP’s uncoupling action in mitochondria to carboxyatractyloside, a specific inhibitor of adenine nucleotide translocase (ANT), suggests the involvement of ANT and probably other mitochondrial proton-transporting proteins in the DNP’s protonophoric activity. To test this hypothesis, we investigated the contribution of recombinant ANT1 and the uncoupling proteins UCP1-UCP3 to DNP-mediated proton leakage using the well-defined model of planar bilayer lipid membranes. All four proteins significantly enhanced the protonophoric effect of DNP. Notably, only long-chain free fatty acids were previously shown to be co-factors of UCPs and ANT1. Using site-directed mutagenesis and molecular dynamics simulations, we showed that arginine 79 of ANT1 is crucial for the DNP-mediated increase of membrane conductance, implying that this amino acid participates in DNP binding to ANT1.
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3
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Ardalan A, Sowlati-Hashjin S, Oduwoye H, Uwumarenogie SO, Karttunen M, Smith MD, Jelokhani-Niaraki M. Biphasic Proton Transport Mechanism for Uncoupling Proteins. J Phys Chem B 2021; 125:9130-9144. [PMID: 34365794 DOI: 10.1021/acs.jpcb.1c04766] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
It has been suggested that uncoupling proteins (UCPs) transport protons via interconversion between two conformational states: one in the "cytoplasmic state" and the other in the "matrix state". Matrix and cytoplasmic salt-bridge networks are key controllers of these states. This study proposes a mechanism for proton transport in tetrameric UCP2, with focus on the role of the matrix network. Eleven mutants were prepared to disrupt (K → Q or D → N mutations) or alter (K → D and D → K mutations) the salt-bridges in the matrix network. Proteins were recombinantly expressed in Escherichia coli membrane, reconstituted in model lipid membranes, and their structures and functions were analyzed by gel electrophoresis, circular dichroism spectroscopy, fluorescence assays, as well as molecular dynamics simulations. It is shown that the UCP2 matrix network contains five salt-bridges (rather than the previously reported three), and the matrix network can regulate the proton transport by holding the protein's transmembrane helices in close proximity, limiting the movement of the activator fatty acid(s). A biphasic two-state molecular model is proposed for proton transport in tetrameric (a dimer of stable dimers) UCP2, in which all the monomers are functional, and monomers in each dimer are in the same transport mode. Purine nucleotide (e.g., ATP) can occlude the internal pore of the monomeric units of UCP tetramers via interacting with positive residues at or in the proximity of the matrix network (K38, K141, K239, R88, R185, and R279) and prevent switching between cytoplasmic and matrix states, thus inhibiting the proton transport. This study provides new insights into the mechanism of proton transport and regulation in UCPs.
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Affiliation(s)
- Afshan Ardalan
- Department of Chemistry and Biochemistry, Wilfrid Laurier University, Waterloo, Ontario N2L 3C5, Canada
| | - Shahin Sowlati-Hashjin
- Department of Chemistry, The University of Western Ontario, London, Ontario N6A 3K7, Canada.,The Center for Advanced Materials and Biomaterials Research, The University of Western Ontario, London, Ontario N6K 3K7, Canada
| | - Habib Oduwoye
- Department of Chemistry and Biochemistry, Wilfrid Laurier University, Waterloo, Ontario N2L 3C5, Canada
| | - Stephanie O Uwumarenogie
- Department of Chemistry and Biochemistry, Wilfrid Laurier University, Waterloo, Ontario N2L 3C5, Canada
| | - Mikko Karttunen
- Department of Chemistry, The University of Western Ontario, London, Ontario N6A 3K7, Canada.,The Center for Advanced Materials and Biomaterials Research, The University of Western Ontario, London, Ontario N6K 3K7, Canada.,Department of Physics and Astronomy, The University of Western Ontario, London, Ontario N6A 3K7, Canada
| | - Matthew D Smith
- Department of Biology, Wilfrid Laurier University, Waterloo, Ontario N2L 3C5, Canada
| | - Masoud Jelokhani-Niaraki
- Department of Chemistry and Biochemistry, Wilfrid Laurier University, Waterloo, Ontario N2L 3C5, Canada
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4
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Coccurello R, Volonté C. P2X7 Receptor in the Management of Energy Homeostasis: Implications for Obesity, Dyslipidemia, and Insulin Resistance. Front Endocrinol (Lausanne) 2020; 11:199. [PMID: 32528404 PMCID: PMC7247848 DOI: 10.3389/fendo.2020.00199] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Accepted: 03/19/2020] [Indexed: 12/15/2022] Open
Abstract
Whole-body energy metabolism entails the highly regulated balance between food intake, nutrient breakdown, energy generation (ATP), and energy storage for the preservation of vital functions and body mass. Purinergic signaling has attracted increasing attention in the regulatory mechanisms not only for the reverse processes of white adipose tissue lipogenesis and lipolysis, but also for brown adipocyte-dependent thermogenesis and leptin production. This regulatory role has remarkable implications in the handling of body's energy expenditure and energy reservoir. Hence, selected purinergic receptors can play a relevant function in lipid metabolism, endocrine activity, glucose uptake, ATP-dependent increased expression of uncoupling protein 1, and browning of adipose tissue. Indeed, purinergic P2 receptors regulate adipogenesis and lipid metabolism and are involved in adipogenic differentiation. In particular, the ionotropic ATP-activated P2X7 subtype is involved in fat distribution, as well as in the modulation of inflammatory pathways in white adipose tissue. Within this context, very recent evidence has established a direct function of P2X7 in energy metabolism. Specifically, either genetic deletion (P2X7 knockout mice) or subchronic pharmacological inhibition of the receptor produces a decrease of whole-body energy expenditure and, concurrently, an increase of carbohydrate oxidation. As further evidence, lipid accumulation, increased fat mass distribution, and weight gain are reported in P2X7-depleted mice. Conversely, the stimulation of P2X7 enhances energy expenditure. Altogether, this knowledge supports the role of P2X7 signaling in the fight against obesity and insulin resistance, as well as in the promotion of adaptive thermogenesis.
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Affiliation(s)
- Roberto Coccurello
- Institute for Complex System (ISC), National Research Council (CNR), Rome, Italy
- Preclinical Neuroscience, European Center for Brain Research (CERC)/IRCCS Santa Lucia Foundation, Rome, Italy
| | - Cinzia Volonté
- Preclinical Neuroscience, European Center for Brain Research (CERC)/IRCCS Santa Lucia Foundation, Rome, Italy
- Institute for Systems Analysis and Computer Science, National Research Council (CNR), Rome, Italy
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5
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Bertholet AM, Kirichok Y. Patch-Clamp Analysis of the Mitochondrial H + Leak in Brown and Beige Fat. Front Physiol 2020; 11:326. [PMID: 32351404 PMCID: PMC7174661 DOI: 10.3389/fphys.2020.00326] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Accepted: 03/20/2020] [Indexed: 01/27/2023] Open
Abstract
Mitochondria convert the chemical energy of metabolic substrates into adenosine triphosphate (ATP) and heat. Although ATP production has become a focal point of research in bioenergetics, mitochondrial thermogenesis is also crucial for energy metabolism. Mitochondria generate heat due to H+ leak across the inner mitochondrial membrane (IMM) which is mediated by mitochondrial uncoupling proteins. The mitochondrial H+ leak was first identified, and studied for many decades, using mitochondrial respiration technique. Unfortunately, this method measures H+ leak indirectly, and its precision is insufficient for the rigorous insight into the mitochondrial function at the molecular level. Direct patch-clamp recording of H+ leak would have a significantly higher amplitude and time resolution, but application of the patch-clamp technique to a small subcellular organelle such as mitochondria has been challenging. We developed a method that facilitates patch-clamp recording from the whole IMM, enabling the direct measurement of small H+ leak currents via uncoupling proteins and thus, providing a rigorous understanding of the molecular mechanisms involved. In this paper we cover the methodology of measuring the H+ leak in mitochondria of specialized thermogenic tissues brown and beige fat.
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Affiliation(s)
- Ambre M. Bertholet
- Department of Physiology, University of California, San Francisco, San Francisco, CA, United States
| | - Yuriy Kirichok
- Department of Physiology, University of California, San Francisco, San Francisco, CA, United States
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6
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Kreiter J, Rupprecht A, Zimmermann L, Moschinger M, Rokitskaya TI, Antonenko YN, Gille L, Fedorova M, Pohl EE. Molecular Mechanisms Responsible for Pharmacological Effects of Genipin on Mitochondrial Proteins. Biophys J 2019; 117:1845-1857. [PMID: 31706565 PMCID: PMC7031773 DOI: 10.1016/j.bpj.2019.10.021] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Revised: 09/26/2019] [Accepted: 10/15/2019] [Indexed: 12/15/2022] Open
Abstract
Genipin, a natural compound from Gardenia jasminoides, is a well-known compound in Chinese medicine that is used for the treatment of cancer, inflammation, and diabetes. The use of genipin in classical medicine is hindered because of its unknown molecular mechanisms of action apart from its strong cross-linking ability. Genipin is increasingly applied as a specific inhibitor of proton transport mediated by mitochondrial uncoupling protein 2 (UCP2). However, its specificity for UCP2 is questionable, and the underlying mechanism behind its action is unknown. Here, we investigated the effect of genipin in different systems, including neuroblastoma cells, isolated mitochondria, isolated mitochondrial proteins, and planar lipid bilayer membranes reconstituted with recombinant proteins. We revealed that genipin activated dicarboxylate carrier and decreased the activity of UCP1, UCP3, and complex III of the respiratory chain alongside with UCP2 inhibition. Based on competitive inhibition experiments, the use of amino acid blockers, and site-directed mutagenesis of UCP1, we propose a mechanism of genipin’s action on UCPs. At low concentrations, genipin binds to arginine residues located in the UCP funnel, which leads to a decrease in UCP’s proton transporting function in the presence of long chain fatty acids. At concentrations above 200 μM, the inhibitory action of genipin on UCPs is overlaid by increased nonspecific membrane conductance due to the formation of protein-genipin aggregates. Understanding the concentration-dependent mechanism of genipin action in cells will allow its targeted application as a drug in the above-mentioned diseases.
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Affiliation(s)
- Jürgen Kreiter
- Institute of Physiology, Pathophysiology and Biophysics, Department of Biomedical Sciences, University of Veterinary Medicine, Vienna, Austria
| | - Anne Rupprecht
- Rostock University Medical Center, Rostock, Mecklenburg-Vorpommern, Germany
| | - Lars Zimmermann
- Institute of Physiology, Pathophysiology and Biophysics, Department of Biomedical Sciences, University of Veterinary Medicine, Vienna, Austria
| | - Michael Moschinger
- Institute of Physiology, Pathophysiology and Biophysics, Department of Biomedical Sciences, University of Veterinary Medicine, Vienna, Austria
| | - Tatyana I Rokitskaya
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Yuri N Antonenko
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Lars Gille
- Institute of Pharmacology and Toxicology, Department of Biomedical Sciences, University of Veterinary Medicine, Vienna, Austria
| | - Maria Fedorova
- Institute of Bioanalytical Chemistry, Faculty of Chemistry and Mineralogy, Center for Biotechnology and Biomedicine, University of Leipzig, Leipzig, Germany
| | - Elena E Pohl
- Institute of Physiology, Pathophysiology and Biophysics, Department of Biomedical Sciences, University of Veterinary Medicine, Vienna, Austria.
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7
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Abstract
Uncoupling protein 1 (UCP1) is an integral protein of the inner mitochondrial membrane (IMM) that is expressed specifically in brown and beige fat depots. UCP1 is responsible for the production of heat to control core body temperature, the regulation of fat metabolism, and the energy balance. As an uncoupling protein, UCP1 transports H+ across the IMM in presence of long-chain fatty acids (FA), which makes brown fat mitochondria produce heat at the expense of ATP. However, the exact mechanism of UCP1 action has remained difficult to elucidate, because direct methods for studying currents generated by UCP1 were unavailable. Recently, the patch-clamp technique was successfully applied to brown and beige fat mitochondria to directly study H+ currents across the IMM and characterize UCP1 function. A new model of the UCP1 mechanism was proposed based on the patch-clamp analysis. In this model, both FA anions (FA-) and H+ are transport substrates of UCP1, and UCP1 operates as a non-canonical FA-/H+ symporter. Here, we summarize recent findings obtained with the patch-clamp technique that describe how UCP1 can transport not only H+ but also FA-.
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8
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Pohl EE, Rupprecht A, Macher G, Hilse KE. Important Trends in UCP3 Investigation. Front Physiol 2019; 10:470. [PMID: 31133866 PMCID: PMC6524716 DOI: 10.3389/fphys.2019.00470] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2018] [Accepted: 04/04/2019] [Indexed: 11/13/2022] Open
Abstract
Membrane uncoupling protein 3 (UCP3), a member of the mitochondrial uncoupling protein family, was discovered in 1997. UCP3's properties, such as its high homology to other mitochondrial carriers, especially to UCP2, its short lifetime and low specificity of UCP3 antibodies, have hindered progress in understanding its biological function and transport mechanism over decades. The abundance of UCP3 is highest in murine brown adipose tissue (BAT, 15.0 pmol/mg protein), compared to heart (2.7 pmol/mg protein) and the gastrocnemius muscle (1.7 pmol/mg protein), but it is still 400-fold lower than the abundance of UCP1, a biomarker for BAT. Investigation of UCP3 reconstituted in planar bilayer membranes revealed that it transports protons only when activated by fatty acids (FA). Although purine nucleotides (PN) inhibit UCP3-mediated transport, the molecular mechanism differs from that of UCP1. It remains a conundrum that two homologous proton-transporting proteins exist within the same tissue. Recently, we proposed that UCP3 abundance directly correlates with the degree of FA β-oxidation in cell metabolism. Further development in this field implies that UCP3 may have dual function in transporting substrates, which have yet to be identified, alongside protons. Evaluation of the literature with respect to UCP3 is a complex task because (i) UCP3 features are often extrapolated from its "twin" UCP2 without additional proof, and (ii) the specificity of antibodies against UCP3 used in studies is rarely evaluated. In this review, we primarily focus on recent findings obtained for UCP3 in biological and biomimetic systems.
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Affiliation(s)
- Elena E. Pohl
- Institute of Physiology, Pathophysiology and Biophysics, University of Veterinary Medicine, Vienna, Austria
| | - Anne Rupprecht
- Institute of Physiology, Pathophysiology and Biophysics, University of Veterinary Medicine, Vienna, Austria
- Institute of Pharmacology and Toxicology, Rostock University Medical Center, Rostock, Germany
| | - Gabriel Macher
- Institute of Physiology, Pathophysiology and Biophysics, University of Veterinary Medicine, Vienna, Austria
| | - Karolina E. Hilse
- Institute of Physiology, Pathophysiology and Biophysics, University of Veterinary Medicine, Vienna, Austria
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9
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Qin N, Cai T, Ke Q, Yuan Q, Luo J, Mao X, Jiang L, Cao H, Wen P, Zen K, Zhou Y, Yang J. UCP2-dependent improvement of mitochondrial dynamics protects against acute kidney injury. J Pathol 2018; 247:392-405. [PMID: 30426490 DOI: 10.1002/path.5198] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Revised: 10/11/2018] [Accepted: 11/06/2018] [Indexed: 01/06/2023]
Abstract
Acute kidney injury (AKI) is a public health concern, with high morbidity and mortality rates in hospitalized patients and because survivors have an increased risk of progression to chronic kidney disease. Mitochondrial damage is the critical driver of AKI-associated dysfunction and loss of tubular epithelial cells; however, the pathways that mediate these events are poorly defined. Here, in murine ischemia/reperfusion (I/R)-induced AKI, we determined that mitochondrial damage is associated with the level of renal uncoupling protein 2 (UCP2). In hypoxia-damaged proximal tubular cells, a disruption of mitochondrial dynamics demonstrated by mitochondrial fragmentation and disturbance between fusion and fission was clearly indicated. Ucp2-deficient mice (knockout mice) with I/R injury experienced more severe AKI and mitochondrial fragmentation than wild-type mice. Moreover, genetic or pharmacological treatment increased UCP2 expression, improved renal function, reduced tubular injury and limited mitochondrial fission. In cultured proximal tubular epithelial cells, hypoxia-induced mitochondrial fission was exacerbated in cells with UCP2 deletion, whereas an increase in UCP2 ameliorated the hypoxia-induced disturbance of the balance between mitochondrial fusion and fission. Furthermore, results following modulation of UCP2 suggested it has a role in preserving mitochondrial integrity by preventing loss of membrane potential and reducing subsequent mitophagy. Taken together, our results indicate that UCP2 is protective against AKI and suggest that enhancing UCP2 to improve mitochondrial dynamics has potential as a strategy for improving outcomes of renal injury. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
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Affiliation(s)
- Nan Qin
- Center for Kidney Disease, Second Affiliated Hospital, Nanjing Medical University, Nanjing, PR China
| | - Ting Cai
- Center for Kidney Disease, Second Affiliated Hospital, Nanjing Medical University, Nanjing, PR China
| | - Qingqing Ke
- Center for Kidney Disease, Second Affiliated Hospital, Nanjing Medical University, Nanjing, PR China
| | - Qi Yuan
- Center for Kidney Disease, Second Affiliated Hospital, Nanjing Medical University, Nanjing, PR China
| | - Jing Luo
- Center for Kidney Disease, Second Affiliated Hospital, Nanjing Medical University, Nanjing, PR China
| | - Xiaoming Mao
- Center for Kidney Disease, Second Affiliated Hospital, Nanjing Medical University, Nanjing, PR China
| | - Lei Jiang
- Center for Kidney Disease, Second Affiliated Hospital, Nanjing Medical University, Nanjing, PR China
| | - Hongdi Cao
- Center for Kidney Disease, Second Affiliated Hospital, Nanjing Medical University, Nanjing, PR China
| | - Ping Wen
- Center for Kidney Disease, Second Affiliated Hospital, Nanjing Medical University, Nanjing, PR China
| | - Ke Zen
- State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, Advanced Institute of Life Sciences, Nanjing, PR China
| | - Yang Zhou
- Center for Kidney Disease, Second Affiliated Hospital, Nanjing Medical University, Nanjing, PR China
| | - Junwei Yang
- Center for Kidney Disease, Second Affiliated Hospital, Nanjing Medical University, Nanjing, PR China
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10
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Lin J, Cao C, Tao C, Ye R, Dong M, Zheng Q, Wang C, Jiang X, Qin G, Yan C, Li K, Speakman JR, Wang Y, Jin W, Zhao J. Cold adaptation in pigs depends on UCP3 in beige adipocytes. J Mol Cell Biol 2018; 9:364-375. [PMID: 28486585 DOI: 10.1093/jmcb/mjx018] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2017] [Accepted: 05/07/2017] [Indexed: 12/27/2022] Open
Abstract
Pigs lack functional uncoupling protein 1 (UCP1) making them susceptible to cold. Nevertheless, several pig breeds are known to be cold resistant. The molecular mechanism(s) enabling such adaptation are currently unknown. Here, we show that this resistance is not dependent on shivering, but rather depends on UCP3 and white adipose tissue (WAT) browning. In two cold-resistant breeds (Tibetan and Min), but not a cold-sensitive breed (Bama), WAT browning was induced after cold exposure. Beige adipocytes from Tibetan pigs exhibited greater oxidative capacity than those from Bama pigs. Notably, UCP3 expression was significantly increased only in cold-resistant breeds, and knockdown of UCP3 expression in Tibetan adipocytes phenocopied Bama adipocytes in culture. Moreover, the eight dominant pig breeds found across China can be classified into cold-sensitive and cold-resistant breeds based on the UCP3 cDNA sequence. This study indicates that UCP3 has contributed to the evolution of cold resistance in the pig and overturns the orthodoxy that UCP1 is the only thermogenic uncoupling protein.
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Affiliation(s)
- Jun Lin
- Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.,College of Life Science, University of Chinese Academy of Sciences, Beijing, China
| | - Chunwei Cao
- State Key Laboratory of Stem Cell and Reproductive Biology, Chinese Academy of Sciences, Beijing, China
| | - Cong Tao
- State Key Laboratory of Animal Nutrition, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Rongcai Ye
- Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.,College of Life Science, University of Chinese Academy of Sciences, Beijing, China
| | - Meng Dong
- Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.,College of Life Science, University of Chinese Academy of Sciences, Beijing, China
| | - Qiantao Zheng
- College of Life Science, University of Chinese Academy of Sciences, Beijing, China.,State Key Laboratory of Stem Cell and Reproductive Biology, Chinese Academy of Sciences, Beijing, China
| | - Chao Wang
- State Key Laboratory of Animal Nutrition, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Xiaoxiao Jiang
- Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.,College of Life Science, University of Chinese Academy of Sciences, Beijing, China
| | - Guosong Qin
- State Key Laboratory of Stem Cell and Reproductive Biology, Chinese Academy of Sciences, Beijing, China
| | - Changguo Yan
- Department of Animal Science, Yanbian University, Yanji, China
| | - Kui Li
- State Key Laboratory of Animal Nutrition, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, China
| | - John R Speakman
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Yanfang Wang
- State Key Laboratory of Animal Nutrition, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Wanzhu Jin
- Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.,Savaid Medical School, University of Chinese Academy of Sciences, Beijing, China
| | - Jianguo Zhao
- State Key Laboratory of Stem Cell and Reproductive Biology, Chinese Academy of Sciences, Beijing, China.,Savaid Medical School, University of Chinese Academy of Sciences, Beijing, China
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11
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Macher G, Koehler M, Rupprecht A, Kreiter J, Hinterdorfer P, Pohl EE. Inhibition of mitochondrial UCP1 and UCP3 by purine nucleotides and phosphate. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2018; 1860:664-672. [PMID: 29212043 PMCID: PMC6118327 DOI: 10.1016/j.bbamem.2017.12.001] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2017] [Revised: 11/04/2017] [Accepted: 12/01/2017] [Indexed: 11/26/2022]
Abstract
Mitochondrial membrane uncoupling protein 3 (UCP3) is not only expressed in skeletal muscle and heart, but also in brown adipose tissue (BAT) alongside UCP1, which facilitates a proton leak to support non-shivering thermogenesis. In contrast to UCP1, the transport function and molecular mechanism of UCP3 regulation are poorly investigated, although it is generally agreed upon that UCP3, analogous to UCP1, transports protons, is activated by free fatty acids (FFAs) and is inhibited by purine nucleotides (PNs). Because the presence of two similar uncoupling proteins in BAT is surprising, we hypothesized that UCP1 and UCP3 are differently regulated, which may lead to differences in their functions. By combining atomic force microscopy and electrophysiological measurements of recombinant proteins reconstituted in planar bilayer membranes, we compared the level of protein activity with the bond lifetimes between UCPs and PNs. Our data revealed that, in contrast to UCP1, UCP3 can be fully inhibited by all PNs and IC50 increases with a decrease in PN-phosphorylation. Experiments with mutant proteins demonstrated that the conserved arginines in the PN-binding pocket are involved in the inhibition of UCP1 and UCP3 to different extents. Fatty acids compete with all PNs bound to UCP1, but only with ATP bound to UCP3. We identified phosphate as a novel inhibitor of UCP3 and UCP1, which acts independently of PNs. The differences in molecular mechanisms of the inhibition between the highly homologous transporters UCP1 and UCP3 indicate that UCP3 has adapted to fulfill a different role and possibly another transport function in BAT.
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Affiliation(s)
- Gabriel Macher
- Institute of Physiology, Pathophysiology and Biophysics, University of Veterinary Medicine, Vienna, Austria
| | - Melanie Koehler
- Institute of Biophysics, Johannes Kepler University, Linz, Austria
| | - Anne Rupprecht
- Institute of Physiology, Pathophysiology and Biophysics, University of Veterinary Medicine, Vienna, Austria
| | - Jürgen Kreiter
- Institute of Physiology, Pathophysiology and Biophysics, University of Veterinary Medicine, Vienna, Austria
| | | | - Elena E Pohl
- Institute of Physiology, Pathophysiology and Biophysics, University of Veterinary Medicine, Vienna, Austria.
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12
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Brown adipose tissue and lipid metabolism imaging. Methods 2017; 130:105-113. [DOI: 10.1016/j.ymeth.2017.05.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Revised: 04/28/2017] [Accepted: 05/05/2017] [Indexed: 01/20/2023] Open
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13
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Zhao L, Wang S, Zhu Q, Wu B, Liu Z, OuYang B, Chou JJ. Specific Interaction of the Human Mitochondrial Uncoupling Protein 1 with Free Long-Chain Fatty Acid. Structure 2017; 25:1371-1379.e3. [PMID: 28781081 DOI: 10.1016/j.str.2017.07.005] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Revised: 06/16/2017] [Accepted: 07/06/2017] [Indexed: 01/05/2023]
Abstract
The mitochondrial uncoupling protein 1 (UCP1) generates heat by causing proton leak across the mitochondrial inner membrane that requires fatty acid (FA). The mechanism by which UCP1 uses FA to conduct proton remains unsolved, and it is also unclear whether a direct physical interaction between UCP1 and FA exists. Here, we have shown using nuclear magnetic resonance that FA can directly bind UCP1 at a helix-helix interface site composed of residues from the transmembrane helices H1 and H6. According to the paramagnetic relaxation enhancement data and molecular dynamics simulation, the FA acyl chain appears to fit into the groove between H1 and H6 while the FA carboxylate group interacts with the basic residues near the matrix side of UCP1. Functional mutagenesis showed that mutating the observed FA binding site severely reduced UCP1-mediated proton flux. Our study identifies a functionally important FA-UCP1 interaction that is potentially useful for mechanistic understanding of UCP1-mediated thermogenesis.
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Affiliation(s)
- Linlin Zhao
- State Key Laboratory of Molecular Biology, National Center for Protein Science Shanghai, Shanghai Science Research Center, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 201203, China
| | - Shuqing Wang
- School of Pharmacy, Tianjin Medical University, Tianjin 300070, China
| | - Qianli Zhu
- State Key Laboratory of Molecular Biology, National Center for Protein Science Shanghai, Shanghai Science Research Center, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 201203, China
| | - Bin Wu
- State Key Laboratory of Molecular Biology, National Center for Protein Science Shanghai, Shanghai Science Research Center, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 201203, China
| | - Zhijun Liu
- State Key Laboratory of Molecular Biology, National Center for Protein Science Shanghai, Shanghai Science Research Center, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 201203, China
| | - Bo OuYang
- State Key Laboratory of Molecular Biology, National Center for Protein Science Shanghai, Shanghai Science Research Center, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 201203, China.
| | - James J Chou
- State Key Laboratory of Molecular Biology, National Center for Protein Science Shanghai, Shanghai Science Research Center, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 201203, China; Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA.
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14
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Mitochondrial Patch Clamp of Beige Adipocytes Reveals UCP1-Positive and UCP1-Negative Cells Both Exhibiting Futile Creatine Cycling. Cell Metab 2017; 25:811-822.e4. [PMID: 28380374 PMCID: PMC5448977 DOI: 10.1016/j.cmet.2017.03.002] [Citation(s) in RCA: 165] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Revised: 12/27/2016] [Accepted: 03/04/2017] [Indexed: 11/27/2022]
Abstract
Cold and other environmental factors induce "browning" of white fat depots-development of beige adipocytes with morphological and functional resemblance to brown fat. Similar to brown fat, beige adipocytes are assumed to express mitochondrial uncoupling protein 1 (UCP1) and are thermogenic due to the UCP1-mediated H+ leak across the inner mitochondrial membrane. However, this assumption has never been tested directly. Herein we patch clamped the inner mitochondrial membrane of beige and brown fat to provide a direct comparison of their thermogenic H+ leak (IH). All inguinal beige adipocytes had robust UCP1-dependent IH comparable to brown fat, but it was about three times less sensitive to purine nucleotide inhibition. Strikingly, only ∼15% of epididymal beige adipocytes had IH, while in the rest UCP1-dependent IH was undetectable. Despite the absence of UCP1 in the majority of epididymal beige adipocytes, these cells employ prominent creatine cycling as a UCP1-independent thermogenic mechanism.
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15
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Bertholet AM, Kirichok Y. UCP1: A transporter for H + and fatty acid anions. Biochimie 2016; 134:28-34. [PMID: 27984203 DOI: 10.1016/j.biochi.2016.10.013] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Accepted: 10/25/2016] [Indexed: 12/21/2022]
Abstract
Adaptive thermogenesis regulates core body temperature, controls fat deposition, and contributes strongly to the overall energy balance. This process occurs in brown fat and requires uncoupling protein 1 (UCP1), an integral protein of the inner mitochondrial membrane. Classic biochemical studies revealed the general principle of adaptive thermogenesis: in the presence of long-chain fatty acids (FA), UCP1 increases the permeability of the inner mitochondrial membrane for H+, which makes brown fat mitochondria produce heat rather than ATP. However, the exact mechanism by which UCP1 increases the membrane H+ conductance in a FA-dependent manner has remained a fundamental unresolved question. Recently, the patch-clamp technique was successfully applied to the inner mitochondrial membrane of brown fat to directly characterize the H+ currents carried by UCP1. Based on the patch-clamp data, a new model of UCP1 operation was proposed. In brief, FA anions are transport substrates of UCP1, and UCP1 operates as an unusual FA anion/H+ symporter. Interestingly, in contrast to short-chain FA anions, long-chain FA anions cannot easily dissociate from UCP1 due to strong hydrophobic interactions established by their carbon tails, and a single long-chain FA participates in many H+ transport cycles. Therefore, in the presence of long-chain FA, endogenous activators of brown fat thermogenesis, UCP1 effectively operates as an H+ uniport. In addition to their transport function, long-chain FA competitively remove tonic inhibition of UCP1 by cytosolic purine nucleotides, thus enabling activation of the thermogenic H+ leak through UCP1 under physiological conditions.
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Affiliation(s)
- Ambre M Bertholet
- Department of Physiology, University of California San Francisco, UCSF Mail Code 2140, Genentech Hall Room N272F, 600 16th Street, San Francisco, CA 94158, USA
| | - Yuriy Kirichok
- Department of Physiology, University of California San Francisco, UCSF Mail Code 2140, Genentech Hall Room N272F, 600 16th Street, San Francisco, CA 94158, USA.
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16
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Abstract
This review focuses on the biochemical work of UCP1 starting from the early observation by Ricquier and Kader in 1976. We entered this field in 1980 with the isolation of native UCP1 and then reported the amino acid sequence structure discovering a strong homology to the ADP/ATP carrier. With the isolated native UCP1 we studied structural and functional features, in particular the complex characteristics of nucleotide binding. A strong pH dependence of binding and herein the differences between diphopho- and triphopho-nucleotides were observed, resulting in the identification of residues which control binding site access by their H+ dissociation. Newly synthesized fluorescent nucleotide derivatives provided tools to determine a two state nucleotide binding in line with loose and tight UCP1 conformations and H+ transport inhibition. The slow transition between these states were a notable feature. The reconstitution of isolated UCP1 in vesicles demonstrated that UCP1 protein is in fact the uncoupling factor and not only a nucleotide controlled regulator. The H+ transport was shown to be electrophoretic with a linear relation to the membrane potential. The dependence of H+ transport on fatty acids (FA) was characterized and is elaborated here with a view of the experimental conditions of other research groups which had different views of the role of FA in H+ transport. Furthermore, to explain the contrast of the FA - nucleotide competition between mitochondria and reconstituted system, indirect paths for FA to relieve the inhibition in mitochondria are here proposed, such as a FA induced upward pH shift and a FA induced increase of cardiolipin level around UCP1 since cardiolipin has been found by us to relieve nucleotide binding on isolated UCP1. Recently reported patch clamp results on mitoplasts led to a reformulation of the H+ transport mechanism of FA in UCP1 in which bound FA shuttles with the carboxyl group between the two membrane sides along the translocation channel outward as FA- and inward as FA-H+. We propose here a modified version, where FA forms an immobile prosthetic group surrounded by the inner and outer gate of the H+ translocation channel. By alternating opening of the gates FA takes up H+ from the cytosol side and releases H+ to the matrix.
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17
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Oxenoid K, Chou JJ. A functional NMR for membrane proteins: dynamics, ligand binding, and allosteric modulation. Protein Sci 2016; 25:959-73. [PMID: 26928605 DOI: 10.1002/pro.2910] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Revised: 02/25/2016] [Accepted: 02/25/2016] [Indexed: 01/13/2023]
Abstract
By nature of conducting ions, transporting substrates and transducing signals, membrane channels, transporters and receptors are expected to exhibit intrinsic conformational dynamics. It is therefore of great interest and importance to understand the various properties of conformational dynamics acquired by these proteins, for example, the relative population of states, exchange rate, conformations of multiple states, and how small molecule ligands modulate the conformational exchange. Because small molecule binding to membrane proteins can be weak and/or dynamic, structural characterization of these effects is very challenging. This review describes several NMR studies of membrane protein dynamics, ligand-induced conformational rearrangements, and the effect of ligand binding on the equilibrium of conformational exchange. The functional significance of the observed phenomena is discussed.
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Affiliation(s)
- Kirill Oxenoid
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts, 02115
| | - James J Chou
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts, 02115
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18
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Normoyle KP, Kim M, Farahvar A, Llano D, Jackson K, Wang H. The emerging neuroprotective role of mitochondrial uncoupling protein-2 in traumatic brain injury. Transl Neurosci 2015; 6:179-186. [PMID: 28123803 PMCID: PMC4936626 DOI: 10.1515/tnsci-2015-0019] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Accepted: 07/20/2015] [Indexed: 12/11/2022] Open
Abstract
Traumatic brain injury (TBI) is a multifaceted disease with intrinsically complex heterogeneity and remains a significant clinical challenge to manage. TBI model systems have demonstrated many mechanisms that contribute to brain parenchymal cell death, including glutamate and calcium toxicity, oxidative stress, inflammation, and mitochondrial dysfunction. Mitochondria are critically regulated by uncoupling proteins (UCP), which allow protons to leak back into the matrix and thus reduce the mitochondrial membrane potential by dissipating the proton motive force. This uncoupling of oxidative phosphorylation from adenosine triphosphate (ATP) synthesis is potentially critical for protection against cellular injury as a result of TBI and stroke. A greater understanding of the underlying mechanism or mechanisms by which uncoupling protein-2 (UCP2) functions to maintain or optimize mitochondrial function, and the conditions which precipitate the failure of these mechanisms, would inform future research and treatment strategies. We posit that UCP2-mediated function underlies the physiological response to neuronal stress associated with traumatic and ischemic injury and that clinical development of UCP2-targeted treatment would significantly impact these patient populations. With a focus on clinical relevance in TBI, we synthesize current knowledge concerning UCP2 and its potential neuroprotective role and apply this body of knowledge to current and potential treatment modalities.
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Affiliation(s)
- Kieran P Normoyle
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL, USA; College of Medicine, University of Illinois at Urbana-Champaign, Urbana, IL, USA; Department of Child Neurology, Massachusetts General Hospital, Boston, MA, USA
| | - Miri Kim
- College of Medicine, University of Illinois at Urbana-Champaign, Urbana, IL, USA; Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Arash Farahvar
- Department of Neurosurgery, Carle Foundation Hospital, Urbana, IL, USA
| | - Daniel Llano
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL, USA; Department of Neurology, Carle Foundation Hospital, Urbana, IL, USA; The Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Kevin Jackson
- The Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, IL, USA; Thermal Neuroscience Laboratory (TNL), Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Huan Wang
- Department of Neurology, Carle Foundation Hospital, Urbana, IL, USA; Thermal Neuroscience Laboratory (TNL), Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, IL, USA
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19
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Berardi MJ, Chou JJ. Fatty acid flippase activity of UCP2 is essential for its proton transport in mitochondria. Cell Metab 2014; 20:541-52. [PMID: 25127353 PMCID: PMC4156518 DOI: 10.1016/j.cmet.2014.07.004] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Revised: 06/06/2014] [Accepted: 07/02/2014] [Indexed: 01/11/2023]
Abstract
Modulation of cellular energy expenditure is fundamental to normal and pathological cell growth and differentiation. Mitochondria stores energy as a proton gradient across their inner membrane. Uncoupling proteins (UCPs) can dissipate the gradient to produce heat or regulate metabolite fluxes. UCP-mediated proton currents require fatty acids (FAs) and are blocked by nucleotides, but the molecular basis of these processes is unknown. We find, by nuclear magnetic resonance and functional mutagenesis, that UCP2 can bind FAs laterally through its peripheral site, and this intramembrane molecular recognition is essential for UCP2-catalyzed FA flipping across the membrane, which in turn is essential for proton translocation. The antagonist GDP binds inside the UCP2 cavity and perturbs its conformation, which can displace FA from the peripheral site as a mean of inhibiting proton currents. Our data provide a biophysical perspective of the intricate interplay of UCPs, FA, and nucleotides in determining proton fluxes in mitochondria.
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Affiliation(s)
- Marcelo J Berardi
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
| | - James J Chou
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA; State Key Laboratory of Molecular Biology, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai 200031, China; National Center for Protein Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai 200031, China.
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20
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Akopyan K, Trchounian A. Proton cycles through membranes in bacteria: Relationship between proton passive and active fluxes and their dependence on some external physico-chemical factors under fermentation. Biophysics (Nagoya-shi) 2013. [DOI: 10.1134/s0006350913050023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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21
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Zhu R, Rupprecht A, Ebner A, Haselgrübler T, Gruber HJ, Hinterdorfer P, Pohl EE. Mapping the nucleotide binding site of uncoupling protein 1 using atomic force microscopy. J Am Chem Soc 2013; 135:3640-6. [PMID: 23414455 PMCID: PMC3593612 DOI: 10.1021/ja312550k] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
A tight regulation of proton transport
in the inner mitochondrial
membrane is crucial for physiological processes such as ATP synthesis,
heat production, or regulation of the reactive oxygen species as proposed
for the uncoupling protein family members (UCP). Specific regulation
of proton transport is thus becoming increasingly important in the
therapy of obesity and inflammatory, neurodegenerative, and ischemic
diseases. We and other research groups have shown previously that
UCP1- and UCP2-mediated proton transport is inhibited by purine nucleotides.
Several hypotheses have been proposed to explain the inhibitory effect
of ATP, although structural details are still lacking. Moreover, the
unresolved mystery is how UCP operates in vivo despite the permanent
presence of high (millimolar) concentrations of ATP in mitochondria.
Here we use the topographic and recognition (TREC) mode of an atomic
force microscope to visualize UCP1 reconstituted into lipid bilayers
and to analyze the ATP–protein interaction at a single molecule
level. The comparison of recognition patterns obtained with anti-UCP1
antibody and ATP led to the conclusion that the ATP binding site can
be accessed from both sides of the membrane. Using cantilever tips
with different cross-linker lengths, we determined the location of
the nucleotide binding site inside the membrane with 1 Å precision.
Together with the recently published NMR structure of a UCP family
member (Berardi et al. Nature, 2011, 476, 109–113), our data
provide a valuable insight into the mechanism of the nucleotide binding
and pave the way for new pharmacological approaches against the diseases
mentioned above.
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Affiliation(s)
- Rong Zhu
- Institute for Biophysics, Johannes Kepler University, Linz, Austria
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22
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Fedorenko A, Lishko PV, Kirichok Y. Mechanism of fatty-acid-dependent UCP1 uncoupling in brown fat mitochondria. Cell 2012; 151:400-13. [PMID: 23063128 DOI: 10.1016/j.cell.2012.09.010] [Citation(s) in RCA: 658] [Impact Index Per Article: 54.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Revised: 04/20/2012] [Accepted: 09/06/2012] [Indexed: 01/10/2023]
Abstract
Mitochondrial uncoupling protein 1 (UCP1) is responsible for nonshivering thermogenesis in brown adipose tissue (BAT). Upon activation by long-chain fatty acids (LCFAs), UCP1 increases the conductance of the inner mitochondrial membrane (IMM) to make BAT mitochondria generate heat rather than ATP. Despite being a member of the family of mitochondrial anion carriers (SLC25), UCP1 is believed to transport H(+) by an unusual mechanism that has long remained unresolved. Here, we achieved direct patch-clamp measurements of UCP1 currents from the IMM of BAT mitochondria. We show that UCP1 is an LCFA anion/H(+) symporter. However, the LCFA anions cannot dissociate from UCP1 due to hydrophobic interactions established by their hydrophobic tails, and UCP1 effectively operates as an H(+) carrier activated by LCFA. A similar LCFA-dependent mechanism of transmembrane H(+) transport may be employed by other SLC25 members and be responsible for mitochondrial uncoupling and regulation of metabolic efficiency in various tissues.
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Affiliation(s)
- Andriy Fedorenko
- Department of Physiology, University of California San Francisco, UCSF Mail Code 2140, Genentech Hall Room N272F, 600 16th Street, San Francisco, CA 94158, USA
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23
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Ren L, Yan D, Zhong W. Enhanced enzyme activity through electron transfer between single-walled carbon nanotubes and horseradish peroxidase. CARBON 2012; 50:1303-1310. [PMID: 22228910 PMCID: PMC3249833 DOI: 10.1016/j.carbon.2011.10.053] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Better understanding of electron transfer (ET) taking place at the nano-bio interface can guide design of more effective functional materials used in fuel cells, biosensors, and medical devices. Single-walled carbon nanotube (SWCNT) coupled with biological enzymes serves as a model system for studying the ET mechanism, as demonstrated in the present study. SWCNT enhanced the activity of horseradish peroxidase (HRP) in the solution-based redox reaction by binding to HRP at a site proximate to the enzyme's activity center and participating in the ET process. ET to and from SWCNT was clearly observable using near-infrared spectroscopy. The capability of SWCNT in receiving electrons and the direct attachment of HRP to the surface of SWCNT strongly affected the enzyme activity due to the direct involvement of SWCNT in ET.
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Affiliation(s)
- Lei Ren
- Environmental Toxicology Graduate Program, University of California, Riverside, CA, 92521, USA
| | - Dong Yan
- Center for Nanoscale Science and Engineering, University of California, Riverside, CA, 92521, USA
| | - Wenwan Zhong
- Environmental Toxicology Graduate Program, University of California, Riverside, CA, 92521, USA
- Department of Chemistry, University of California, Riverside, CA, 92521, USA
- Corresponding Author. Tel: +1 951 8274925.
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24
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Kassab A, Piwowar A. Cell oxidant stress delivery and cell dysfunction onset in type 2 diabetes. Biochimie 2012; 94:1837-48. [PMID: 22333037 DOI: 10.1016/j.biochi.2012.01.020] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2011] [Accepted: 01/25/2012] [Indexed: 01/18/2023]
Abstract
Most known pathways of diabetic complications involve oxidative stress. The mitochondria electron transport chain is a significant source of reactive oxygen species (ROS) in insulin secretory cells, insulin peripheral sensitive cells and endothelial cells. Elevated intracellular glucose level induces tricarboxylic acid cycle electron donor overproduction and mitochondrial proton gradient increase leading to an increase in electron transporter lifetime. Subsequently, the electrons leaked combine with respiratory oxygen (O(2)) resulting in superoxide anion ((•)O(2)(-)) production. Advanced glycation end products derive ROS via interaction with their receptors. Elevated diacylglycerol and ROS activate the protein kinase C pathway which, in turn, activates NADPH oxidases. A vicious circle of pathway derived ROS installs. Pathologic pathways induced ROS are activated and persistent though glycemia returns to normal due to hyperglycemia memory. Endothelial nitric oxide synthase may produce both superoxide anion ((•)O(2)(-)) and nitric oxide (NO) leading to peroxynitrite ((•)ONOO(-)) generation. Homocysteine is also implicated in oxidative stress pathogenesis. In this paper we have highlighted the pathologic mechanisms of ROS on atherosclerosis, renal dysfunction, retina dysfunction and nerve dysfunction in type 2 diabetes. Cell oxidant stress delivery have pivotal role in cell dysfunction onset and progression of angiopathies but an early introduction of good glycemic control may protect cells more efficiently than antioxidants.
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Affiliation(s)
- Asma Kassab
- Biochemistry Laboratory, CHU Farhat Hached, Sousse, Tunisia.
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25
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Karo J, Peterson P, Vendelin M. Molecular dynamics simulations of creatine kinase and adenine nucleotide translocase in mitochondrial membrane patch. J Biol Chem 2012; 287:7467-76. [PMID: 22241474 PMCID: PMC3293576 DOI: 10.1074/jbc.m111.332320] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Interaction between mitochondrial creatine kinase (MtCK) and adenine nucleotide translocase (ANT) can play an important role in determining energy transfer pathways in the cell. Although the functional coupling between MtCK and ANT has been demonstrated, the precise mechanism of the coupling is not clear. To study the details of the coupling, we turned to molecular dynamics simulations. We introduce a new coarse-grained molecular dynamics model of a patch of the mitochondrial inner membrane containing a transmembrane ANT and an MtCK above the membrane. The membrane model consists of three major types of lipids (phosphatidylcholine, phosphatidylethanolamine, and cardiolipin) in a roughly 2:1:1 molar ratio. A thermodynamics-based coarse-grained force field, termed MARTINI, has been used together with the GROMACS molecular dynamics package for all simulated systems in this work. Several physical properties of the system are reproduced by the model and are in agreement with known data. This includes membrane thickness, dimension of the proteins, and diffusion constants. We have studied the binding of MtCK to the membrane and demonstrated the effect of cardiolipin on the stabilization of the binding. In addition, our simulations predict which part of the MtCK protein sequence interacts with the membrane. Taken together, the model has been verified by dynamical and structural data and can be used as the basis for further studies.
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Affiliation(s)
- Jaanus Karo
- Laboratory of Systems Biology, Institute of Cybernetics at Tallinn University of Technology, Akadeemia tee 21, 12618 Tallinn, Estonia
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26
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Ricquier D. Uncoupling protein 1 of brown adipocytes, the only uncoupler: a historical perspective. Front Endocrinol (Lausanne) 2011; 2:85. [PMID: 22649389 PMCID: PMC3355862 DOI: 10.3389/fendo.2011.00085] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2011] [Accepted: 11/12/2011] [Indexed: 11/28/2022] Open
Abstract
Uncoupling protein 1 (UCP1), is a unique mitochondrial membranous protein devoted to adaptive thermogenesis, a specialized function performed by brown adipocytes. Whereas the family of mitochondrial metabolite carriers comprises ∼40 members, UCP1 is the only memberable to translocate protons through the inner membrane of brown adipocyte mitochondria. By this process, UCP1 uncouples respiration from ATP synthesis and therefore provokes energy dissipation in the form of heat while, also stimulating high levels of fatty acid oxidation. UCP1 homologs were identified but they are biochemically and physiologically different from UCP1. Thirty five years after its identification, UCP1 still appears as a fascinating component. The recent renewal of the interest in human brown adipose tissue makes UCP1 as a potential target for strategies of treatment of metabolic disorders.
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27
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Mitochondrial uncoupling protein 2 (UCP2) in glucose and lipid metabolism. Trends Mol Med 2011; 18:52-8. [PMID: 21917523 DOI: 10.1016/j.molmed.2011.08.003] [Citation(s) in RCA: 158] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2011] [Revised: 08/09/2011] [Accepted: 08/18/2011] [Indexed: 12/18/2022]
Abstract
Nutrient availability is critical for the physiological functions of all tissues. By contrast, an excess of nutrients such as carbohydrate and fats impair health and shorten life due by stimulating chronic diseases, including diabetes, cancer and neurodegeneration. The control of circulating glucose and lipid levels involve mitochondria in both central and peripheral mechanisms of metabolism regulation. Mitochondrial uncoupling protein 2 (UCP2) has been implicated in physiological and pathological processes related to glucose and lipid metabolism, and in this review we discuss the latest data on the relationships between UCP2 and glucose and lipid sensing from the perspective of specific hypothalamic neuronal circuits and peripheral tissue functions. The goal is to provide a framework for discussion of future therapeutic strategies for metabolism-related chronic diseases.
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28
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Genova ML, Lenaz G. New developments on the functions of coenzyme Q in mitochondria. Biofactors 2011; 37:330-54. [PMID: 21989973 DOI: 10.1002/biof.168] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2011] [Accepted: 04/06/2011] [Indexed: 12/12/2022]
Abstract
The notion of a mobile pool of coenzyme Q (CoQ) in the lipid bilayer has changed with the discovery of respiratory supramolecular units, in particular the supercomplex comprising complexes I and III; in this model, the electron transfer is thought to be mediated by tunneling or microdiffusion, with a clear kinetic advantage on the transfer based on random collisions. The CoQ pool, however, has a fundamental function in establishing a dissociation equilibrium with bound quinone, besides being required for electron transfer from other dehydrogenases to complex III. The mechanism of CoQ reduction by complex I is analyzed regarding recent developments on the crystallographic structure of the enzyme, also in relation to the capacity of complex I to generate superoxide. Although the mechanism of the Q-cycle is well established for complex III, involvement of CoQ in proton translocation by complex I is still debated. Some additional roles of CoQ are also examined, such as the antioxidant effect of its reduced form and the capacity to bind the permeability transition pore and the mitochondrial uncoupling proteins. Finally, a working hypothesis is advanced on the establishment of a vicious circle of oxidative stress and supercomplex disorganization in pathological states, as in neurodegeneration and cancer.
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Forrest LR, Krämer R, Ziegler C. The structural basis of secondary active transport mechanisms. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2010; 1807:167-88. [PMID: 21029721 DOI: 10.1016/j.bbabio.2010.10.014] [Citation(s) in RCA: 321] [Impact Index Per Article: 22.9] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 07/16/2010] [Revised: 10/13/2010] [Accepted: 10/15/2010] [Indexed: 12/22/2022]
Abstract
Secondary active transporters couple the free energy of the electrochemical potential of one solute to the transmembrane movement of another. As a basic mechanistic explanation for their transport function the model of alternating access was put forward more than 40 years ago, and has been supported by numerous kinetic, biochemical and biophysical studies. According to this model, the transporter exposes its substrate binding site(s) to one side of the membrane or the other during transport catalysis, requiring a substantial conformational change of the carrier protein. In the light of recent structural data for a number of secondary transport proteins, we analyze the model of alternating access in more detail, and correlate it with specific structural and chemical properties of the transporters, such as their assignment to different functional states in the catalytic cycle of the respective transporter, the definition of substrate binding sites, the type of movement of the central part of the carrier harboring the substrate binding site, as well as the impact of symmetry on fold-specific conformational changes. Besides mediating the transmembrane movement of solutes, the mechanism of secondary carriers inherently involves a mechanistic coupling of substrate flux to the electrochemical potential of co-substrate ions or solutes. Mainly because of limitations in resolution of available transporter structures, this important aspect of secondary transport cannot yet be substantiated by structural data to the same extent as the conformational change aspect. We summarize the concepts of coupling in secondary transport and discuss them in the context of the available evidence for ion binding to specific sites and the impact of the ions on the conformational state of the carrier protein, which together lead to mechanistic models for coupling.
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Affiliation(s)
- Lucy R Forrest
- Structural Biology Department, Max Planck Institute for Biophysics, Frankfurt, Germany
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