Publications by authors named "Edward T Chouchani"

54 Publications

Cysteine 253 of UCP1 regulates energy expenditure and sex-dependent adipose tissue inflammation.

Cell Metab 2021 Nov 24. Epub 2021 Nov 24.

Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, USA; Department of Cell Biology, Harvard Medical School, Boston, MA, USA. Electronic address:

Uncoupling protein 1 (UCP1) is a major regulator of brown and beige adipocyte energy expenditure and metabolic homeostasis. However, the widely employed UCP1 loss-of-function model has recently been shown to have a severe deficiency in the entire electron transport chain of thermogenic fat. As such, the role of UCP1 in metabolic regulation in vivo remains unclear. We recently identified cysteine-253 as a regulatory site on UCP1 that elevates protein activity upon covalent modification. Here, we examine the physiological importance of this site through the generation of a UCP1 cysteine-253-null (UCP1 C253A) mouse, a precise genetic model for selective disruption of UCP1 in vivo. UCP1 C253A mice exhibit significantly compromised thermogenic responses in both males and females but display no measurable effect on fat accumulation in an obesogenic environment. Unexpectedly, we find that a lack of C253 results in adipose tissue redox stress, which drives substantial immune cell infiltration and systemic inflammatory pathology in adipose tissues and liver of male, but not female, mice. Elevation of systemic estrogen reverses this male-specific pathology, providing a basis for protection from inflammation due to loss of UCP1 C253 in females. Together, our results establish the UCP1 C253 activation site as a regulator of acute thermogenesis and sex-dependent tissue inflammation.
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http://dx.doi.org/10.1016/j.cmet.2021.11.003DOI Listing
November 2021

Glucose metabolism and pyruvate carboxylase enhance glutathione synthesis and restrict oxidative stress in pancreatic islets.

Cell Rep 2021 Nov;37(8):110037

Department of Cancer Biology, Dana-Farber Cancer Institute, 450 Brookline Ave., Boston, MA 02115, USA; Department of Medical Oncology, Dana-Farber Cancer Institute, Boston 02115, MA, USA; Department of Medicine, Harvard Medical School, 240 Longwood Ave., Boston, MA 02115, USA. Electronic address:

Glucose metabolism modulates the islet β cell responses to diabetogenic stress, including inflammation. Here, we probed the metabolic mechanisms that underlie the protective effect of glucose in inflammation by interrogating the metabolite profiles of primary islets from human donors and identified de novo glutathione synthesis as a prominent glucose-driven pro-survival pathway. We find that pyruvate carboxylase is required for glutathione synthesis in islets and promotes their antioxidant capacity to counter inflammation and nitrosative stress. Loss- and gain-of-function studies indicate that pyruvate carboxylase is necessary and sufficient to mediate the metabolic input from glucose into glutathione synthesis and the oxidative stress response. Altered redox metabolism and cellular capacity to replenish glutathione pools are relevant in multiple pathologies beyond obesity and diabetes. Our findings reveal a direct interplay between glucose metabolism and glutathione biosynthesis via pyruvate carboxylase. This metabolic axis may also have implications in other settings where sustaining glutathione is essential.
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http://dx.doi.org/10.1016/j.celrep.2021.110037DOI Listing
November 2021

Glycogen metabolism links glucose homeostasis to thermogenesis in adipocytes.

Nature 2021 11 27;599(7884):296-301. Epub 2021 Oct 27.

Department of Medicine, University of California San Diego, San Diego, CA, USA.

Adipocytes increase energy expenditure in response to prolonged sympathetic activation via persistent expression of uncoupling protein 1 (UCP1). Here we report that the regulation of glycogen metabolism by catecholamines is critical for UCP1 expression. Chronic β-adrenergic activation leads to increased glycogen accumulation in adipocytes expressing UCP1. Adipocyte-specific deletion of a scaffolding protein, protein targeting to glycogen (PTG), reduces glycogen levels in beige adipocytes, attenuating UCP1 expression and responsiveness to cold or β-adrenergic receptor-stimulated weight loss in obese mice. Unexpectedly, we observed that glycogen synthesis and degradation are increased in response to catecholamines, and that glycogen turnover is required to produce reactive oxygen species leading to the activation of p38 MAPK, which drives UCP1 expression. Thus, glycogen has a key regulatory role in adipocytes, linking glucose metabolism to thermogenesis.
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http://dx.doi.org/10.1038/s41586-021-04019-8DOI Listing
November 2021

Correction: Fragment-based covalent ligand discovery.

RSC Chem Biol 2021 Apr 22;2(2):670-671. Epub 2021 Feb 22.

Department of Cancer Biology, Dana-Farber Cancer Institute Boston MA 02215 USA

[This corrects the article DOI: 10.1039/D0CB00222D.].
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http://dx.doi.org/10.1039/d1cb90008kDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8341680PMC
April 2021

Fragment-based covalent ligand discovery.

RSC Chem Biol 2021 Apr 9;2(2):354-367. Epub 2021 Feb 9.

Department of Cancer Biology, Dana-Farber Cancer Institute Boston MA 02215 USA

Targeted covalent inhibitors have regained widespread attention in drug discovery and have emerged as powerful tools for basic biomedical research. Fueled by considerable improvements in mass spectrometry sensitivity and sample processing, chemoproteomic strategies have revealed thousands of proteins that can be covalently modified by reactive small molecules. Fragment-based drug discovery, which has traditionally been used in a target-centric fashion, is now being deployed on a proteome-wide scale thereby expanding its utility to both the discovery of novel covalent ligands and their cognate protein targets. This powerful approach is allowing 'high-throughput' serendipitous discovery of cryptic pockets leading to the identification of pharmacological modulators of proteins previously viewed as "undruggable". The reactive fragment toolkit has been enabled by recent advances in the development of new chemistries that target residues other than cysteine including lysine and tyrosine. Here, we review the emerging area of covalent fragment-based ligand discovery, which integrates the benefits of covalent targeting and fragment-based medicinal chemistry. We discuss how the two strategies synergize to facilitate the efficient discovery of new pharmacological modulators of established and new therapeutic target proteins.
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http://dx.doi.org/10.1039/d0cb00222dDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8341086PMC
April 2021

Microglial metabolism is a pivotal factor in sexual dimorphism in Alzheimer's disease.

Commun Biol 2021 06 10;4(1):711. Epub 2021 Jun 10.

Trinity College Institute for Neuroscience, Trinity College, Dublin 2, Ireland.

Age and sex are major risk factors in Alzheimer's disease (AD) with a higher incidence of the disease in females. Neuroinflammation, which is a hallmark of AD, contributes to disease pathogenesis and is inexorably linked with inappropriate microglial activation and neurodegeneration. We investigated sex-related differences in microglia in APP/PS1 mice and in post-mortem tissue from AD patients. Changes in genes that are indicative of microglial activation were preferentially increased in cells from female APP/PS1 mice and cells from males and females were morphological, metabolically and functionally distinct. Microglia from female APP/PS1 mice were glycolytic and less phagocytic and associated with increased amyloidosis whereas microglia from males were amoeboid and this was also the case in post-mortem tissue from male AD patients, where plaque load was reduced. We propose that the sex-related differences in microglia are likely to explain, at least in part, the sexual dimorphism in AD.
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http://dx.doi.org/10.1038/s42003-021-02259-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8192523PMC
June 2021

UCP1 governs liver extracellular succinate and inflammatory pathogenesis.

Nat Metab 2021 05 17;3(5):604-617. Epub 2021 May 17.

Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, USA.

Non-alcoholic fatty liver disease (NAFLD), the most prevalent liver pathology worldwide, is intimately linked with obesity and type 2 diabetes. Liver inflammation is a hallmark of NAFLD and is thought to contribute to tissue fibrosis and disease pathogenesis. Uncoupling protein 1 (UCP1) is exclusively expressed in brown and beige adipocytes, and has been extensively studied for its capacity to elevate thermogenesis and reverse obesity. Here we identify an endocrine pathway regulated by UCP1 that antagonizes liver inflammation and pathology, independent of effects on obesity. We show that, without UCP1, brown and beige fat exhibit a diminished capacity to clear succinate from the circulation. Moreover, UCP1KO mice exhibit elevated extracellular succinate in liver tissue that drives inflammation through ligation of its cognate receptor succinate receptor 1 (SUCNR1) in liver-resident stellate cell and macrophage populations. Conversely, increasing brown and beige adipocyte content in mice antagonizes SUCNR1-dependent inflammatory signalling in the liver. We show that this UCP1-succinate-SUCNR1 axis is necessary to regulate liver immune cell infiltration and pathology, and systemic glucose intolerance in an obesogenic environment. As such, the therapeutic use of brown and beige adipocytes and UCP1 extends beyond thermogenesis and may be leveraged to antagonize NAFLD and SUCNR1-dependent liver inflammation.
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http://dx.doi.org/10.1038/s42255-021-00389-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8207988PMC
May 2021

Mitochondrial TNAP controls thermogenesis by hydrolysis of phosphocreatine.

Nature 2021 May 12;593(7860):580-585. Epub 2021 May 12.

Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, USA.

Adaptive thermogenesis has attracted much attention because of its ability to increase systemic energy expenditure and to counter obesity and diabetes. Recent data have indicated that thermogenic fat cells use creatine to stimulate futile substrate cycling, dissipating chemical energy as heat. This model was based on the super-stoichiometric relationship between the amount of creatine added to mitochondria and the quantity of oxygen consumed. Here we provide direct evidence for the molecular basis of this futile creatine cycling activity in mice. Thermogenic fat cells have robust phosphocreatine phosphatase activity, which is attributed to tissue-nonspecific alkaline phosphatase (TNAP). TNAP hydrolyses phosphocreatine to initiate a futile cycle of creatine dephosphorylation and phosphorylation. Unlike in other cells, TNAP in thermogenic fat cells is localized to the mitochondria, where futile creatine cycling occurs. TNAP expression is powerfully induced when mice are exposed to cold conditions, and its inhibition in isolated mitochondria leads to a loss of futile creatine cycling. In addition, genetic ablation of TNAP in adipocytes reduces whole-body energy expenditure and leads to rapid-onset obesity in mice, with no change in movement or feeding behaviour. These data illustrate the critical role of TNAP as a phosphocreatine phosphatase in the futile creatine cycle.
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http://dx.doi.org/10.1038/s41586-021-03533-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8287965PMC
May 2021

AIDA and UCP1 snuggle up to prevent hypothermia.

Nat Cell Biol 2021 03;23(3):216-218

Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, USA.

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http://dx.doi.org/10.1038/s41556-021-00648-3DOI Listing
March 2021

Lactate fluxes mediated by the monocarboxylate transporter-1 are key determinants of the metabolic activity of beige adipocytes.

J Biol Chem 2021 Jan-Jun;296:100137. Epub 2020 Dec 6.

STROMALab, Université de Toulouse, CNRS ERL5311, EFS, INP-ENVT, INSERM U1031, Université Paul Sabatier, Toulouse, France; Institut RESTORE, UMR 1301 INSERM, 5070 CNRS, Université Paul Sabatier, Toulouse, France. Electronic address:

Activation of energy-dissipating brown/beige adipocytes represents an attractive therapeutic strategy against metabolic disorders. While lactate is known to induce beiging through the regulation of Ucp1 gene expression, the role of lactate transporters on beige adipocytes' ongoing metabolic activity remains poorly understood. To explore the function of the lactate-transporting monocarboxylate transporters (MCTs), we used a combination of primary cell culture studies, C isotopic tracing, laser microdissection experiments, and in situ immunofluorescence of murine adipose fat pads. Dissecting white adipose tissue heterogeneity revealed that the MCT1 is expressed in inducible beige adipocytes as the emergence of uncoupling protein 1 after cold exposure was restricted to a subpopulation of MCT1-expressing adipocytes suggesting MCT1 as a marker of inducible beige adipocytes. We also observed that MCT1 mediates bidirectional and simultaneous inward and outward lactate fluxes, which were required for efficient utilization of glucose by beige adipocytes activated by the canonical β3-adrenergic signaling pathway. Finally, we demonstrated that significant lactate import through MCT1 occurs even when glucose is not limiting, which feeds the oxidative metabolism of beige adipocytes. These data highlight the key role of lactate fluxes in finely tuning the metabolic activity of beige adipocytes according to extracellular metabolic conditions and reinforce the emerging role of lactate metabolism in the control of energy homeostasis.
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http://dx.doi.org/10.1074/jbc.RA120.016303DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7949083PMC
August 2021

pH-Gated Succinate Secretion Regulates Muscle Remodeling in Response to Exercise.

Cell 2020 10 17;183(1):62-75.e17. Epub 2020 Sep 17.

Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, USA; Department of Cell Biology, Harvard Medical School, Boston, MA, USA. Electronic address:

In response to skeletal muscle contraction during exercise, paracrine factors coordinate tissue remodeling, which underlies this healthy adaptation. Here we describe a pH-sensing metabolite signal that initiates muscle remodeling upon exercise. In mice and humans, exercising skeletal muscle releases the mitochondrial metabolite succinate into the local interstitium and circulation. Selective secretion of succinate is facilitated by its transient protonation, which occurs upon muscle cell acidification. In the protonated monocarboxylic form, succinate is rendered a transport substrate for monocarboxylate transporter 1, which facilitates pH-gated release. Upon secretion, succinate signals via its cognate receptor SUCNR1 in non-myofibrillar cells in muscle tissue to control muscle-remodeling transcriptional programs. This succinate-SUCNR1 signaling is required for paracrine regulation of muscle innervation, muscle matrix remodeling, and muscle strength in response to exercise training. In sum, we define a bioenergetic sensor in muscle that utilizes intracellular pH and succinate to coordinate tissue adaptation to exercise.
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http://dx.doi.org/10.1016/j.cell.2020.08.039DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7778787PMC
October 2020

Facultative protein selenation regulates redox sensitivity, adipose tissue thermogenesis, and obesity.

Proc Natl Acad Sci U S A 2020 05 1;117(20):10789-10796. Epub 2020 May 1.

Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02115;

Oxidation of cysteine thiols by physiological reactive oxygen species (ROS) initiates thermogenesis in brown and beige adipose tissues. Cellular selenocysteines, where sulfur is replaced with selenium, exhibit enhanced reactivity with ROS. Despite their critical roles in physiology, methods for broad and direct detection of proteogenic selenocysteines are limited. Here we developed a mass spectrometric method to interrogate incorporation of selenium into proteins. Unexpectedly, this approach revealed facultative incorporation of selenium as selenocysteine or selenomethionine into proteins that lack canonical encoding for selenocysteine. Selenium was selectively incorporated into regulatory sites on key metabolic proteins, including as selenocysteine-replacing cysteine at position 253 in uncoupling protein 1 (UCP1). This facultative utilization of selenium was initiated by increasing cellular levels of organic, but not inorganic, forms of selenium. Remarkably, dietary selenium supplementation elevated facultative incorporation into UCP1, elevated energy expenditure through thermogenic adipose tissue, and protected against obesity. Together, these findings reveal the existence of facultative protein selenation, which correlates with impacts on thermogenic adipocyte function and presumably other biological processes as well.
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http://dx.doi.org/10.1073/pnas.2001387117DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7245117PMC
May 2020

Sample multiplexing for targeted pathway proteomics in aging mice.

Proc Natl Acad Sci U S A 2020 05 24;117(18):9723-9732. Epub 2020 Apr 24.

Department of Cell Biology, Harvard Medical School, Boston, MA 02115;

Pathway proteomics strategies measure protein expression changes in specific cellular processes that carry out related functions. Using targeted tandem mass tags-based sample multiplexing, hundreds of proteins can be quantified across 10 or more samples simultaneously. To facilitate these highly complex experiments, we introduce a strategy that provides complete control over targeted sample multiplexing experiments, termed Tomahto, and present its implementation on the Orbitrap Tribrid mass spectrometer platform. Importantly, this software monitors via the external desktop computer to the data stream and inserts optimized MS2 and MS3 scans in real time based on an application programming interface with the mass spectrometer. Hundreds of proteins of interest from diverse biological samples can be targeted and accurately quantified in a sensitive and high-throughput fashion. It achieves sensitivity comparable to, if not better than, deep fractionation and requires minimal total sample input (∼10 µg). As a proof-of-principle experiment, we selected four pathways important in metabolism- and inflammation-related processes (260 proteins/520 peptides) and measured their abundance across 90 samples (nine tissues from five old and five young mice) to explore effects of aging. Tissue-specific aging is presented here and we highlight the role of inflammation- and metabolism-related processes in white adipose tissue. We validated our approach through comparison with a global proteome survey across the tissues, work that we also provide as a general resource for the community.
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http://dx.doi.org/10.1073/pnas.1919410117DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7211924PMC
May 2020

A Quantitative Tissue-Specific Landscape of Protein Redox Regulation during Aging.

Cell 2020 03 27;180(5):968-983.e24. Epub 2020 Feb 27.

Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, USA; Department of Cell Biology, Harvard Medical School, Boston, MA, USA. Electronic address:

Mammalian tissues engage in specialized physiology that is regulated through reversible modification of protein cysteine residues by reactive oxygen species (ROS). ROS regulate a myriad of biological processes, but the protein targets of ROS modification that drive tissue-specific physiology in vivo are largely unknown. Here, we develop Oximouse, a comprehensive and quantitative mapping of the mouse cysteine redox proteome in vivo. We use Oximouse to establish several paradigms of physiological redox signaling. We define and validate cysteine redox networks within each tissue that are tissue selective and underlie tissue-specific biology. We describe a common mechanism for encoding cysteine redox sensitivity by electrostatic gating. Moreover, we comprehensively identify redox-modified disease networks that remodel in aged mice, establishing a systemic molecular basis for the long-standing proposed links between redox dysregulation and tissue aging. We provide the Oximouse compendium as a framework for understanding mechanisms of redox regulation in physiology and aging.
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http://dx.doi.org/10.1016/j.cell.2020.02.012DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8164166PMC
March 2020

Metabolic adaptation and maladaptation in adipose tissue.

Nat Metab 2019 02 21;1(2):189-200. Epub 2019 Jan 21.

Department of Cell and Tissue Biology, University of California San Francisco, San Francisco, CA, USA.

Adipose tissue possesses the remarkable capacity to control its size and function in response to a variety of internal and external cues, such as nutritional status and temperature. The regulatory circuits of fuel storage and oxidation in white adipocytes and thermogenic adipocytes (brown and beige adipocytes) play a central role in systemic energy homeostasis, whereas dysregulation of the pathways is closely associated with metabolic disorders and adipose tissue malfunction, including obesity, insulin resistance, chronic inflammation, mitochondrial dysfunction, and fibrosis. Recent studies have uncovered new regulatory elements that control the above parameters and provide new mechanistic opportunities to reprogram fat cell fate and function. In this Review, we provide an overview of the current understanding of adipocyte metabolism in physiology and disease and also discuss possible strategies to alter fuel utilization in fat cells to improve metabolic health.
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http://dx.doi.org/10.1038/s42255-018-0021-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6941795PMC
February 2019

Author Correction: Glycerol phosphate shuttle enzyme GPD2 regulates macrophage inflammatory responses.

Nat Immunol 2019 Nov;20(11):1555

Department of Genetics & Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, MA, USA.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.
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http://dx.doi.org/10.1038/s41590-019-0517-8DOI Listing
November 2019

Glycerol phosphate shuttle enzyme GPD2 regulates macrophage inflammatory responses.

Nat Immunol 2019 09 5;20(9):1186-1195. Epub 2019 Aug 5.

Department of Genetics & Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, MA, USA.

Macrophages are activated during microbial infection to coordinate inflammatory responses and host defense. Here we find that in macrophages activated by bacterial lipopolysaccharide (LPS), mitochondrial glycerol 3-phosphate dehydrogenase (GPD2) regulates glucose oxidation to drive inflammatory responses. GPD2, a component of the glycerol phosphate shuttle, boosts glucose oxidation to fuel the production of acetyl coenzyme A, acetylation of histones and induction of genes encoding inflammatory mediators. While acute exposure to LPS drives macrophage activation, prolonged exposure to LPS triggers tolerance to LPS, where macrophages induce immunosuppression to limit the detrimental effects of sustained inflammation. The shift in the inflammatory response is modulated by GPD2, which coordinates a shutdown of oxidative metabolism; this limits the availability of acetyl coenzyme A for histone acetylation at genes encoding inflammatory mediators and thus contributes to the suppression of inflammatory responses. Therefore, GPD2 and the glycerol phosphate shuttle integrate the extent of microbial stimulation with glucose oxidation to balance the beneficial and detrimental effects of the inflammatory response.
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http://dx.doi.org/10.1038/s41590-019-0453-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6707851PMC
September 2019

H transport is an integral function of the mitochondrial ADP/ATP carrier.

Nature 2019 07 24;571(7766):515-520. Epub 2019 Jul 24.

Department of Physiology, University of California San Francisco, San Francisco, CA, USA.

The mitochondrial ADP/ATP carrier (AAC) is a major transport protein of the inner mitochondrial membrane. It exchanges mitochondrial ATP for cytosolic ADP and controls cellular production of ATP. In addition, it has been proposed that AAC mediates mitochondrial uncoupling, but it has proven difficult to demonstrate this function or to elucidate its mechanisms. Here we record AAC currents directly from inner mitochondrial membranes from various mouse tissues and identify two distinct transport modes: ADP/ATP exchange and H transport. The AAC-mediated H current requires free fatty acids and resembles the H leak via the thermogenic uncoupling protein 1 found in brown fat. The ADP/ATP exchange via AAC negatively regulates the H leak, but does not completely inhibit it. This suggests that the H leak and mitochondrial uncoupling could be dynamically controlled by cellular ATP demand and the rate of ADP/ATP exchange. By mediating two distinct transport modes, ADP/ATP exchange and H leak, AAC connects coupled (ATP production) and uncoupled (thermogenesis) energy conversion in mitochondria.
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http://dx.doi.org/10.1038/s41586-019-1400-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6662629PMC
July 2019

Coupling Krebs cycle metabolites to signalling in immunity and cancer.

Nat Metab 2019 01;1:16-33

Department of Cancer Biology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts 02115, USA.

Metabolic reprogramming has become a key focus for both immunologists and cancer biologists, with exciting advances providing new insights into underlying mechanisms of disease. Metabolites traditionally associated with bioenergetics or biosynthesis have been implicated in immunity and malignancy in transformed cells, with a particular focus on intermediates of the mitochondrial pathway known as the Krebs cycle. Among these, the intermediates succinate, fumarate, itaconate, 2-hydroxyglutarate isomers (D-2-hydroxyglutarate and L-2-hydroxyglutarate) and acetyl-CoA now have extensive evidence for "non-metabolic" signalling functions in both physiological immune contexts and in disease contexts, such as the initiation of carcinogenesis. This review will describe how metabolic reprogramming, with emphasis placed on these metabolites, leads to altered immune cell and transformed cell function. The latest findings are informative for new therapeutic approaches which could be transformative for a range of diseases.
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http://dx.doi.org/10.1038/s42255-018-0014-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6485344PMC
January 2019

New Advances in Adaptive Thermogenesis: UCP1 and Beyond.

Cell Metab 2019 01 29;29(1):27-37. Epub 2018 Nov 29.

Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, USA; Department of Cell Biology, Harvard Medical School, Boston, MA, USA. Electronic address:

Brown and beige adipocytes can catabolize stored energy to generate heat, and this distinct capacity for thermogenesis could be leveraged as a therapy for metabolic diseases like obesity and type 2 diabetes. Thermogenic adipocytes drive heat production through close coordination of substrate supply with the mitochondrial oxidative machinery and effectors that control the rate of substrate oxidation. Together, this apparatus affords these adipocytes with tremendous capacity to drive thermogenesis. The best characterized thermogenic effector is uncoupling protein 1 (UCP1). Importantly, additional mechanisms for activating thermogenesis beyond UCP1 have been identified and characterized to varying extents. Acute regulation of these thermogenic pathways has been an active area of study, and numerous regulatory factors have been uncovered in recent years. Here we will review the evidence for regulators of heat production in thermogenic adipocytes in the context of the thermodynamic and kinetic principles that govern their therapeutic utility.
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http://dx.doi.org/10.1016/j.cmet.2018.11.002DOI Listing
January 2019

Mechanisms of Mitochondria Assembly, Dynamics and Turnover in Health and Disease.

J Mol Biol 2018 12 11;430(24):4821-4822. Epub 2018 Nov 11.

Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD) and Institute for Mitochondrial Diseases and Aging, Medical Faculty, University of Cologne, Cologne, Germany, Center for Molecular Medicine (CMMC), University of Cologne, Cologne, Germany. Electronic address:

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http://dx.doi.org/10.1016/j.jmb.2018.11.009DOI Listing
December 2018

Accumulation of succinate controls activation of adipose tissue thermogenesis.

Nature 2018 08 18;560(7716):102-106. Epub 2018 Jul 18.

Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, USA.

Thermogenesis by brown and beige adipose tissue, which requires activation by external stimuli, can counter metabolic disease. Thermogenic respiration is initiated by adipocyte lipolysis through cyclic AMP-protein kinase A signalling; this pathway has been subject to longstanding clinical investigation. Here we apply a comparative metabolomics approach and identify an independent metabolic pathway that controls acute activation of adipose tissue thermogenesis in vivo. We show that substantial and selective accumulation of the tricarboxylic acid cycle intermediate succinate is a metabolic signature of adipose tissue thermogenesis upon activation by exposure to cold. Succinate accumulation occurs independently of adrenergic signalling, and is sufficient to elevate thermogenic respiration in brown adipocytes. Selective accumulation of succinate may be driven by a capacity of brown adipocytes to sequester elevated circulating succinate. Furthermore, brown adipose tissue thermogenesis can be initiated by systemic administration of succinate in mice. Succinate from the extracellular milieu is rapidly metabolized by brown adipocytes, and its oxidation by succinate dehydrogenase is required for activation of thermogenesis. We identify a mechanism whereby succinate dehydrogenase-mediated oxidation of succinate initiates production of reactive oxygen species, and drives thermogenic respiration, whereas inhibition of succinate dehydrogenase supresses thermogenesis. Finally, we show that pharmacological elevation of circulating succinate drives UCP1-dependent thermogenesis by brown adipose tissue in vivo, which stimulates robust protection against diet-induced obesity and improves glucose tolerance. These findings reveal an unexpected mechanism for control of thermogenesis, using succinate as a systemically-derived thermogenic molecule.
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http://dx.doi.org/10.1038/s41586-018-0353-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7045287PMC
August 2018

Multiplexed Isobaric Tag-Based Profiling of Seven Murine Tissues Following In Vivo Nicotine Treatment Using a Minimalistic Proteomics Strategy.

Proteomics 2018 05 2;18(10):e1700326. Epub 2018 May 2.

Department of Cell Biology, Harvard Medical School, Boston, MA, 02115, USA.

Nicotine is a major addictive compound in tobacco and a component of smoking-related products, such as e-cigarettes. Once internalized, nicotine can perturb many cellular pathways and can induce alterations in proteins across different cell types; however, the mechanisms thereof remain undetermined. The authors hypothesize that both tissue-specific and global protein abundance alterations result from nicotine exposure. Presented here is the first proteomic profiling of multiple tissues from mice treated orally with nicotine. Proteins extracted from seven tissues (brain, heart, kidney, liver, lung, pancreas, and spleen) from treated (n = 5) and untreated control (n = 5) mice are assembled into a TMT10-plex experiment. A minimalistic proteomics strategy is employed using TMT reagents efficiently and centrifugation-based reversed-phase columns to streamline sample preparation. Combined, over 11 000 non-redundant proteins from over 138 000 different peptides are quantified in seven TMT10-plex experiments. Between 7 and 126 proteins are significantly altered in tissues from nicotine-exposed mice, 11 which are altered in two or more tissues. Our data showcase the vast extent of nicotine exposure across murine tissue.
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http://dx.doi.org/10.1002/pmic.201700326DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5992107PMC
May 2018

Itaconate is an anti-inflammatory metabolite that activates Nrf2 via alkylation of KEAP1.

Nature 2018 04 28;556(7699):113-117. Epub 2018 Mar 28.

Department of Cancer Biology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts 02115, USA.

The endogenous metabolite itaconate has recently emerged as a regulator of macrophage function, but its precise mechanism of action remains poorly understood. Here we show that itaconate is required for the activation of the anti-inflammatory transcription factor Nrf2 (also known as NFE2L2) by lipopolysaccharide in mouse and human macrophages. We find that itaconate directly modifies proteins via alkylation of cysteine residues. Itaconate alkylates cysteine residues 151, 257, 288, 273 and 297 on the protein KEAP1, enabling Nrf2 to increase the expression of downstream genes with anti-oxidant and anti-inflammatory capacities. The activation of Nrf2 is required for the anti-inflammatory action of itaconate. We describe the use of a new cell-permeable itaconate derivative, 4-octyl itaconate, which is protective against lipopolysaccharide-induced lethality in vivo and decreases cytokine production. We show that type I interferons boost the expression of Irg1 (also known as Acod1) and itaconate production. Furthermore, we find that itaconate production limits the type I interferon response, indicating a negative feedback loop that involves interferons and itaconate. Our findings demonstrate that itaconate is a crucial anti-inflammatory metabolite that acts via Nrf2 to limit inflammation and modulate type I interferons.
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http://dx.doi.org/10.1038/nature25986DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6047741PMC
April 2018

Genetic Depletion of Adipocyte Creatine Metabolism Inhibits Diet-Induced Thermogenesis and Drives Obesity.

Cell Metab 2017 Oct 24;26(4):660-671.e3. Epub 2017 Aug 24.

Dana-Farber Cancer Institute, Boston, MA 02115, USA; Department of Cell Biology, Harvard University Medical School, Boston, MA 02115, USA. Electronic address:

Diet-induced thermogenesis is an important homeostatic mechanism that limits weight gain in response to caloric excess and contributes to the relative stability of body weight in most individuals. We previously demonstrated that creatine enhances energy expenditure through stimulation of mitochondrial ATP turnover, but the physiological role and importance of creatine energetics in adipose tissue have not been explored. Here, we have inactivated the first and rate-limiting enzyme of creatine biosynthesis, glycine amidinotransferase (GATM), selectively in fat (Adipo-Gatm KO). Adipo-Gatm KO mice are prone to diet-induced obesity due to the suppression of elevated energy expenditure that occurs in response to high-calorie feeding. This is paralleled by a blunted capacity for β3-adrenergic activation of metabolic rate, which is rescued by dietary creatine supplementation. These results provide strong in vivo genetic support for a role of GATM and creatine metabolism in energy expenditure, diet-induced thermogenesis, and defense against diet-induced obesity.
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http://dx.doi.org/10.1016/j.cmet.2017.08.009DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5629120PMC
October 2017

Mitochondrial reactive oxygen species and adipose tissue thermogenesis: Bridging physiology and mechanisms.

J Biol Chem 2017 10 24;292(41):16810-16816. Epub 2017 Aug 24.

From the Dana-Farber Cancer Institute, Harvard Medical School and

Brown and beige adipose tissues can catabolize stored energy to generate heat, relying on the principal effector of thermogenesis: uncoupling protein 1 (UCP1). This unique capability could be leveraged as a therapy for metabolic disease. Numerous animal and cellular models have now demonstrated that mitochondrial reactive oxygen species (ROS) signal to support adipocyte thermogenic identity and function. Herein, we contextualize these findings within the established principles of redox signaling and mechanistic studies of UCP1 function. We provide a framework for understanding the role of mitochondrial ROS signaling in thermogenesis together with testable hypotheses for understanding mechanisms and developing therapies.
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http://dx.doi.org/10.1074/jbc.R117.789628DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5641863PMC
October 2017

Identification and quantification of protein -nitrosation by nitrite in the mouse heart during ischemia.

J Biol Chem 2017 09 14;292(35):14486-14495. Epub 2017 Jul 14.

the Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Cambridge CB2 0XY, United Kingdom, and

Nitrate (NO) and nitrite (NO) are known to be cardioprotective and to alter energy metabolism NO action results from its conversion to NO by salivary bacteria, but the mechanism(s) by which NO affects metabolism remains obscure. NO may act by -nitrosating protein thiols, thereby altering protein activity. But how this occurs, and the functional importance of -nitrosation sites across the mammalian proteome, remain largely uncharacterized. Here we analyzed protein thiols within mouse hearts using quantitative proteomics to determine -nitrosation site occupancy. We extended the thiol-redox proteomic technique, isotope-coded affinity tag labeling, to quantify the extent of NO-dependent -nitrosation of proteins thiols Using this approach, called SNOxICAT (-nitrosothiol redox isotope-coded affinity tag), we found that exposure to NO under normoxic conditions or exposure to ischemia alone results in minimal -nitrosation of protein thiols. However, exposure to NO in conjunction with ischemia led to extensive -nitrosation of protein thiols across all cellular compartments. Several mitochondrial protein thiols exposed to the mitochondrial matrix were selectively -nitrosated under these conditions, potentially contributing to the beneficial effects of NO on mitochondrial metabolism. The permeability of the mitochondrial inner membrane to HNO, but not to NO, combined with the lack of -nitrosation during anoxia alone or by NO during normoxia places constraints on how -nitrosation occurs and on its mechanisms of cardioprotection and modulation of energy metabolism. Quantifying -nitrosated protein thiols now allows determination of modified cysteines across the proteome and identification of those most likely responsible for the functional consequences of NO exposure.
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http://dx.doi.org/10.1074/jbc.M117.798744DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5582841PMC
September 2017

UCP1 deficiency causes brown fat respiratory chain depletion and sensitizes mitochondria to calcium overload-induced dysfunction.

Proc Natl Acad Sci U S A 2017 07 19;114(30):7981-7986. Epub 2017 Jun 19.

Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02115;

Brown adipose tissue (BAT) mitochondria exhibit high oxidative capacity and abundant expression of both electron transport chain components and uncoupling protein 1 (UCP1). UCP1 dissipates the mitochondrial proton motive force (Δp) generated by the respiratory chain and increases thermogenesis. Here we find that in mice genetically lacking UCP1, cold-induced activation of metabolism triggers innate immune signaling and markers of cell death in BAT. Moreover, global proteomic analysis reveals that this cascade induced by UCP1 deletion is associated with a dramatic reduction in electron transport chain abundance. UCP1-deficient BAT mitochondria exhibit reduced mitochondrial calcium buffering capacity and are highly sensitive to mitochondrial permeability transition induced by reactive oxygen species (ROS) and calcium overload. This dysfunction depends on ROS production by reverse electron transport through mitochondrial complex I, and can be rescued by inhibition of electron transfer through complex I or pharmacologic depletion of ROS levels. Our findings indicate that the interscapular BAT of knockout mice exhibits mitochondrial disruptions that extend well beyond the deletion of UCP1 itself. This finding should be carefully considered when using this mouse model to examine the role of UCP1 in physiology.
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http://dx.doi.org/10.1073/pnas.1705406114DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5544316PMC
July 2017
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