1
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Mostafa ME, Agongo J, Grady SF, Pyles K, McCommis KS, Arnatt CK, Ford DA, Edwards JL. Double Cyclization Tandem Mass for Identification and Quantification of Phosphatidylcholines Using Isobaric Six-Plex Capillary nLC-MS/MS. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2024. [PMID: 38870035 DOI: 10.1021/jasms.3c00447] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2024]
Abstract
Multiplexing of phosphatidylcholine analysis is hindered by a lack of appropriate derivatization. Presented here is a tagging scheme that uses a quaternary amine tag and targets the hydroxy group of the phosphate, which switches the net charge from neutral to +2. Quantitative yields were achieved from >99% reaction completion derived by dimethoxymethyl morpholinium (DMTMM) activation. Fragmentation of phosphatidylcholines (PCs) and lysophosphatidylcholines (LPCs) releases two trimethylamines and the acyl chains through neutral loss and generates a unique double cyclization constant mass reporter. Selective incorporation of isotopes onto the tag produces a six-plex set of isobaric reagents. For equivalent six-plex-labeled samples, <14% RSD was achieved, followed by a dynamic range of 1:10 without signal compression. Quantification of PCs/LPCs in human hepatic cancer cells was conducted as six-plex using data-dependent analysis tandem MS. We report a six-plex qualitative and quantitative isobaric tagging strategy expanding the limits of analyzing PCs/LPCs.
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Affiliation(s)
- Mahmoud Elhusseiny Mostafa
- Department of Chemistry and Biochemistry, Saint Louis University, 3501 Laclede Avenue, St. Louis, Missouri 63103, United States
| | - Julius Agongo
- Department of Chemistry and Biochemistry, Saint Louis University, 3501 Laclede Avenue, St. Louis, Missouri 63103, United States
| | - Scott F Grady
- Department of Chemistry and Biochemistry, Saint Louis University, 3501 Laclede Avenue, St. Louis, Missouri 63103, United States
| | - Kelly Pyles
- Edward A. Doisy Department of Biochemistry and Molecular Biology and Center for Cardiovascular Research, Saint Louis University School of Medicine, St. Louis, Missouri 63104, United States
| | - Kyle S McCommis
- Edward A. Doisy Department of Biochemistry and Molecular Biology and Center for Cardiovascular Research, Saint Louis University School of Medicine, St. Louis, Missouri 63104, United States
| | - Christopher K Arnatt
- Department of Chemistry and Biochemistry, Saint Louis University, 3501 Laclede Avenue, St. Louis, Missouri 63103, United States
| | - David A Ford
- Edward A. Doisy Department of Biochemistry and Molecular Biology and Center for Cardiovascular Research, Saint Louis University School of Medicine, St. Louis, Missouri 63104, United States
| | - James L Edwards
- Department of Chemistry and Biochemistry, Saint Louis University, 3501 Laclede Avenue, St. Louis, Missouri 63103, United States
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2
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Krumm CS, Landzberg RS, Ramos-Espiritu L, Adura C, Liu X, Acuna M, Xie Y, Xu X, Tillman MC, Li Y, Glickman JF, Ortlund EA, Ginn JD, Cohen DE. High-throughput screening identifies small molecule inhibitors of thioesterase superfamily member 1: Implications for the management of non-alcoholic fatty liver disease. Mol Metab 2023; 78:101832. [PMID: 38403978 PMCID: PMC10663673 DOI: 10.1016/j.molmet.2023.101832] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Revised: 10/24/2023] [Accepted: 10/24/2023] [Indexed: 02/27/2024] Open
Abstract
OBJECTIVE Thioesterase superfamily member 1 (Them1) is a long chain acyl-CoA thioesterase comprising two N-terminal HotDog fold enzymatic domains linked to a C-terminal lipid-sensing steroidogenic acute regulatory transfer-related (START) domain, which allosterically modulates enzymatic activity. Them1 is highly expressed in thermogenic adipose tissue, where it functions to suppress energy expenditure by limiting rates of fatty acid oxidation, and is induced markedly in liver in response to high fat feeding, where it suppresses fatty acid oxidation and promotes glucose production. Them1-/- mice are protected against non-alcoholic fatty liver disease (NAFLD), suggesting Them1 as a therapeutic target. METHODS A high-throughput small molecule screen was performed to identify promising inhibitors targeting the fatty acyl-CoA thioesterase activity of purified recombinant Them1.Counter screening was used to determine specificity for Them1 relative to other acyl-CoA thioesterase isoforms. Inhibitor binding and enzyme inhibition were quantified by biophysical and biochemical approaches, respectively. Following structure-based optimization, lead compounds were tested in cell culture. RESULTS Two lead allosteric inhibitors were identified that selectively inhibited Them1 by binding the START domain. In mouse brown adipocytes, these inhibitors promoted fatty acid oxidation, as evidenced by increased oxygen consumption rates. In mouse hepatocytes, they promoted fatty acid oxidation, but also reduced glucose production. CONCLUSION Them1 inhibitors could prove attractive for the pharmacologic management of NAFLD.
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Affiliation(s)
- Christopher S Krumm
- Division of Gastroenterology & Hepatology, Joan & Sanford I. Weill Department of Medicine, Weill Cornell Medical College, New York, NY 10065, USA; Sanders Tri-Institutional Therapeutics Discovery Institute, New York, NY 10065, USA
| | - Renée S Landzberg
- Division of Gastroenterology & Hepatology, Joan & Sanford I. Weill Department of Medicine, Weill Cornell Medical College, New York, NY 10065, USA; Division of Gastroenterology, Hepatology and Endoscopy, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, 02115, USA
| | | | - Carolina Adura
- Fisher Drug Discovery Resource Center, The Rockefeller University, New York, NY 10065, USA
| | - Xu Liu
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Mariana Acuna
- Division of Gastroenterology, Hepatology and Endoscopy, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, 02115, USA
| | - Yang Xie
- Division of Gastroenterology, Hepatology and Endoscopy, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, 02115, USA
| | - Xu Xu
- Division of Gastroenterology & Hepatology, Joan & Sanford I. Weill Department of Medicine, Weill Cornell Medical College, New York, NY 10065, USA; Division of Surgical Sciences, Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Matthew C Tillman
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Yingxia Li
- Division of Gastroenterology & Hepatology, Joan & Sanford I. Weill Department of Medicine, Weill Cornell Medical College, New York, NY 10065, USA
| | - J Fraser Glickman
- Fisher Drug Discovery Resource Center, The Rockefeller University, New York, NY 10065, USA
| | - Eric A Ortlund
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - John D Ginn
- Sanders Tri-Institutional Therapeutics Discovery Institute, New York, NY 10065, USA
| | - David E Cohen
- Division of Gastroenterology & Hepatology, Joan & Sanford I. Weill Department of Medicine, Weill Cornell Medical College, New York, NY 10065, USA; Division of Gastroenterology, Hepatology and Endoscopy, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, 02115, USA.
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3
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Depta L, Whitmarsh-Everiss T, Laraia L. Structure, function and small molecule modulation of intracellular sterol transport proteins. Bioorg Med Chem 2022; 68:116856. [PMID: 35716590 DOI: 10.1016/j.bmc.2022.116856] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Accepted: 05/23/2022] [Indexed: 11/02/2022]
Abstract
Intracellular sterol transport proteins (STPs) are crucial for maintaining cellular lipid homeostasis by regulating local sterol pools. Despite structural similarities in their sterol binding domains, STPs have different substrate specificities, intracellular localisation and biological functions. In this review, we highlight recent advances in the determination of STP structures and how this regulates their lipid specificities. Furthermore, we cover the important discoveries relating to the intracellular localisation of STPs, and the organelles between which lipid transport is carried out, giving rise to specific functions in health and disease. Finally, serendipitous and targeted efforts to identify small molecule modulators of STPs, as well as their ability to act as tool compounds and potential therapeutics, will be discussed.
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Affiliation(s)
- Laura Depta
- Department of Chemistry, Technical University of Denmark, Kemitorvet 207, 2800 Kgs Lyngby, Denmark
| | - Thomas Whitmarsh-Everiss
- Department of Chemistry, Technical University of Denmark, Kemitorvet 207, 2800 Kgs Lyngby, Denmark
| | - Luca Laraia
- Department of Chemistry, Technical University of Denmark, Kemitorvet 207, 2800 Kgs Lyngby, Denmark.
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4
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Chai X, Hu X, Zhao X, Yin Y, Cao S, Jiang Z. Asymmetric Hydroaminoalkylation of Alkenylazaarenes via Cooperative Photoredox and Chiral Hydrogen-Bonding Catalysis. Angew Chem Int Ed Engl 2022; 61:e202115110. [PMID: 35001449 DOI: 10.1002/anie.202115110] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2021] [Indexed: 11/08/2022]
Abstract
Chiral hydrogen-bonding (H-bonding) catalytic asymmetric conjugate addition to activated olefins has been widely used to access enantioenriched molecules containing stereocenters at the β-position of the olefin activating groups. Herein, we report the first highly enantioselective radical-based manifold. Under a dual organocatalyst system involving a chiral phosphoric acid and DPZ as the photoredox sensitizer, transformations of N-arylglycines, in which aryls with CF3 substituents are introduced, with alkenyl azaarenes afforded valuable hydroaminoalkylation adducts with satisfactory results. In addition to the diversity of azaarenes, the method can be used to construct aryl-, alkyl- and silyl-substituted stereocenter. Control experiments and density functional theory calculations were performed to elucidate a plausible reaction mechanism and the origin of stereoselectivity, wherein nonclassical H-bonding interactions were found to assist chiral catalysts in offering sufficient enantiocontrol.
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Affiliation(s)
- Xiangpei Chai
- School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, Henan, 453007, P. R. China
| | - Xinheng Hu
- International S&T Cooperation Base of Chiral Chemistry, Henan University, Kaifeng, Henan, 475004, P. R. China
| | - Xiaowei Zhao
- International S&T Cooperation Base of Chiral Chemistry, Henan University, Kaifeng, Henan, 475004, P. R. China
| | - Yanli Yin
- School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, Henan, 453007, P. R. China.,College of Bioengineering, Henan University of Technology, Zhengzhou, Henan, 450001, P. R. China
| | - Shanshan Cao
- School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, Henan, 453007, P. R. China
| | - Zhiyong Jiang
- School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, Henan, 453007, P. R. China.,International S&T Cooperation Base of Chiral Chemistry, Henan University, Kaifeng, Henan, 475004, P. R. China
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5
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Chai X, Hu X, Zhao X, Yin Y, Cao S, Jiang Z. Asymmetric Hydroaminoalkylation of Alkenylazaarenes via Cooperative Photoredox and Chiral Hydrogen‐Bonding Catalysis. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202115110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Xiangpei Chai
- Henan Normal University School of Chemistry and Chemical Engineering 453007 Xinxiang CHINA
| | - Xinheng Hu
- Henan University International S&T Cooperation Base of Chiral Chemistry 475004 Kaifeng CHINA
| | - Xiaowei Zhao
- Henan University International S&T Cooperation Base of Chiral Chemistry 475004 Kaifeng CHINA
| | - Yanli Yin
- Henan Normal University School of Chemistry and Chemical Engineering 453007 Xinxiang CHINA
| | - Shanshan Cao
- Henan Normal University School of Chemistry and Chemical Engineering 453007 Xinxiang CHINA
| | - Zhiyong Jiang
- Henan University Key Laboratory of Natural Medicine and Immuno-Engineering of Henan Province Jinming Campus 475004 Kaifeng CHINA
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6
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Asif K, Memeo L, Palazzolo S, Frión-Herrera Y, Parisi S, Caligiuri I, Canzonieri V, Granchi C, Tuccinardi T, Rizzolio F. STARD3: A Prospective Target for Cancer Therapy. Cancers (Basel) 2021; 13:4693. [PMID: 34572920 PMCID: PMC8472075 DOI: 10.3390/cancers13184693] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Accepted: 09/10/2021] [Indexed: 12/24/2022] Open
Abstract
Cancer is one of the major causes of death in developed countries and current therapies are based on surgery, chemotherapeutic agents, and radiation. To overcome side effects induced by chemo- and radiotherapy, in recent decades, targeted therapies have been proposed in second and even first lines. Targeted drugs act on the essential pathways involved in tumor induction, progression, and metastasis, basically all the hallmark of cancers. Among emerging pathways, the cholesterol metabolic pathway is a strong candidate for this purpose. Cancer cells have an accelerated metabolic rate and require a continuous supply of cholesterol for cell division and membrane renewal. Steroidogenic acute regulatory related lipid transfer (START) proteins are a family of proteins involved in the transfer of lipids and some of them are important in non-vesicular cholesterol transportation within the cell. The alteration of their expression levels is implicated in several diseases, including cancers. In this review, we report the latest discoveries on StAR-related lipid transfer protein domain 3 (STARD3), a member of the START family, which has a potential role in cancer, focusing on the structural and biochemical characteristics and mechanisms that regulate its activity. The role of the STARD3 protein as a molecular target for the development of cancer therapies is also discussed. As STARD3 is a key protein in the cholesterol movement in cancer cells, it is of interest to identify inhibitors able to block its activity.
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Affiliation(s)
- Kanwal Asif
- Department of Molecular Sciences and Nanosystems, PhD School in Science and Technology of Bio and Nanomaterials, Ca’ Foscari University of Venice, 30172 Venice, Italy;
- Pathology Unit, Centro di Riferimento Oncologico di Aviano (C.R.O.) IRCCS, 33081 Aviano, Italy; (S.P.); (S.P.); (V.C.)
| | - Lorenzo Memeo
- Department of Experimental Oncology, Mediterranean Institute of Oncology, 95029 Catania, Italy;
| | - Stefano Palazzolo
- Pathology Unit, Centro di Riferimento Oncologico di Aviano (C.R.O.) IRCCS, 33081 Aviano, Italy; (S.P.); (S.P.); (V.C.)
| | - Yahima Frión-Herrera
- Department of Molecular Sciences and Nanosystems, Ca’ Foscari University of Venice, 30172 Venice, Italy; or
| | - Salvatore Parisi
- Pathology Unit, Centro di Riferimento Oncologico di Aviano (C.R.O.) IRCCS, 33081 Aviano, Italy; (S.P.); (S.P.); (V.C.)
| | - Isabella Caligiuri
- Pathology Unit, Centro di Riferimento Oncologico di Aviano (C.R.O.) IRCCS, 33081 Aviano, Italy; (S.P.); (S.P.); (V.C.)
| | - Vincenzo Canzonieri
- Pathology Unit, Centro di Riferimento Oncologico di Aviano (C.R.O.) IRCCS, 33081 Aviano, Italy; (S.P.); (S.P.); (V.C.)
- Department of Medical, Surgical and Health Sciences, University of Trieste, 34149 Trieste, Italy
| | - Carlotta Granchi
- Department of Pharmacy, University of Pisa, 56126 Pisa, Italy; (C.G.); (T.T.)
| | - Tiziano Tuccinardi
- Department of Pharmacy, University of Pisa, 56126 Pisa, Italy; (C.G.); (T.T.)
| | - Flavio Rizzolio
- Pathology Unit, Centro di Riferimento Oncologico di Aviano (C.R.O.) IRCCS, 33081 Aviano, Italy; (S.P.); (S.P.); (V.C.)
- Department of Molecular Sciences and Nanosystems, Ca’ Foscari University of Venice, 30172 Venice, Italy; or
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7
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Miyachi Y, Akiyama K, Tsukuda Y, Kumrungsee T, Yanaka N. Liver choline metabolism and gene expression in choline-deficient mice offspring differ with gender. Biosci Biotechnol Biochem 2021; 85:447-451. [PMID: 33604639 DOI: 10.1093/bbb/zbaa047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2020] [Accepted: 09/05/2020] [Indexed: 11/12/2022]
Abstract
Choline is an important nutrient during pregnancy and lactation. Maternal choline deficiency in CD-1 mice lowers liver betaine levels in male offspring. By contrast, it increases elovl3 and vanin-1 mRNA levels in female offspring. Taken together, these observations suggest gender-specific responses to a choline-deficient diet.
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Affiliation(s)
- Yukino Miyachi
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, Japan
| | - Kei Akiyama
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, Japan
| | - Yoshiko Tsukuda
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, Japan
| | | | - Noriyuki Yanaka
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, Japan
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8
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Sun DY, Fu JT, Li GQ, Zhang WJ, Zeng FY, Tong J, Miao CY, Li DJ, Wang P. iTRAQ- and LC-MS/MS-based quantitative proteomics reveals Pqlc2 as a potential regulator of hepatic glucose metabolism and insulin signalling pathway during fasting. Clin Exp Pharmacol Physiol 2020; 48:238-249. [PMID: 33051888 DOI: 10.1111/1440-1681.13419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 09/24/2020] [Accepted: 10/06/2020] [Indexed: 11/30/2022]
Abstract
Glucose homeostasis is tightly controlled by balance between glucose production and uptake in liver tissue upon energy shortage condition. Altered glucose homeostasis contributes to the pathophysiology of metabolic disorders including diabetes and obesity. Here, we aimed to analyse the change of proteomic profile upon prolonged fasting in mice with isobaric tag for relative and absolute quantification (iTRAQ) labelling followed by liquid chromatography-mass spectrometry (LC/MS) technology. Adult male mice were fed or fasted for 16 hours and liver tissues were collected for iTRAQ labelling followed by LC/MS analysis. A total of 322 differentially expressed proteins were identified, including 189 upregulated and 133 downregulated proteins. Bioinformatics analyses, including Gene Ontology analysis (GO), Kyoto encyclopaedia of genes and genomes analysis (KEGG) and protein-protein interaction analysis (PPI) were conducted to understand biological process, cell component, and molecular function of the 322 differentially expressed proteins. Among 322 hepatic proteins differentially expressed between fasting and fed mice, we validated three upregulated proteins (Pqlc2, Ehhadh and Apoa4) and two downregulated proteins (Uba52 and Rpl37) by western-blotting analysis. In cultured HepG2 hepatocellular cells, we found that depletion of Pqlc2 by siRNA-mediated knockdown impaired the insulin-induced glucose uptake, inhibited GLUT2 mRNA level and suppressed the insulin-induced Akt phosphorylation. By contrast, knockdown of Pqlc2 did not affect the cAMP/dexamethasone-induced gluconeogenesis. In conclusion, our study provides important information on protein profile change during prolonged fasting with iTRAQ- and LC-MS/MS-based quantitative proteomics, and identifies Pqlc2 as a potential regulator of hepatic glucose metabolism and insulin signalling pathway in this process.
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Affiliation(s)
- Di-Yang Sun
- Department of Pharmacology, School of Pharmacy, Second Military Medical University/Naval Medical University, Shanghai, China
| | - Jiang-Tao Fu
- Department of Pharmacology, School of Pharmacy, Second Military Medical University/Naval Medical University, Shanghai, China
| | - Guo-Qiang Li
- Department of Pharmacology, School of Pharmacy, Second Military Medical University/Naval Medical University, Shanghai, China
| | - Wen-Jie Zhang
- Department of Pharmacology, School of Pharmacy, Second Military Medical University/Naval Medical University, Shanghai, China
| | - Fei-Yan Zeng
- Department of Pharmacy, Shanghai Tenth People's Hospital, Tongji University, Shanghai, China
| | - Jie Tong
- Department of Pharmacy, Shanghai Tenth People's Hospital, Tongji University, Shanghai, China
| | - Chao-Yu Miao
- Department of Pharmacology, School of Pharmacy, Second Military Medical University/Naval Medical University, Shanghai, China
| | - Dong-Jie Li
- Department of Pharmacy, Shanghai Tenth People's Hospital, Tongji University, Shanghai, China
| | - Pei Wang
- Department of Pharmacology, School of Pharmacy, Second Military Medical University/Naval Medical University, Shanghai, China.,Department of Pharmacy, Shanghai Tenth People's Hospital, Tongji University, Shanghai, China
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9
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Clark BJ. The START-domain proteins in intracellular lipid transport and beyond. Mol Cell Endocrinol 2020; 504:110704. [PMID: 31927098 DOI: 10.1016/j.mce.2020.110704] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Revised: 01/08/2020] [Accepted: 01/08/2020] [Indexed: 12/17/2022]
Abstract
The Steroidogenic Acute Regulatory Protein-related Lipid Transfer (START) domain is a ~210 amino acid sequence that folds into an α/β helix-grip structure forming a hydrophobic pocket for lipid binding. The helix-grip fold structure defines a large superfamily of proteins, and this review focuses on the mammalian START domain family members that include single START domain proteins with identified ligands, and larger multi-domain proteins that may have novel roles in metabolism. Much of our understanding of the mammalian START domain proteins in lipid transport and changes in metabolism has advanced through studies using knockout mouse models, although for some of these proteins the identity and/or physiological role of ligand binding remains unknown. The findings that helped define START domain lipid-binding specificity, lipid transport, and changes in metabolism are presented to highlight that fundamental questions remain regarding the biological function(s) for START domain-containing proteins.
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Affiliation(s)
- Barbara J Clark
- Department of Biochemistry & Molecular Genetics, University of Louisville School of Medicine, Louisville, KY, 40292, USA.
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10
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Ersoy BA, Maner-Smith KM, Li Y, Alpertunga I, Cohen DE. Thioesterase-mediated control of cellular calcium homeostasis enables hepatic ER stress. J Clin Invest 2017; 128:141-156. [PMID: 29202465 DOI: 10.1172/jci93123] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Accepted: 10/12/2017] [Indexed: 12/11/2022] Open
Abstract
The incorporation of excess saturated free fatty acids (SFAs) into membrane phospholipids within the ER promotes ER stress, insulin resistance, and hepatic gluconeogenesis. Thioesterase superfamily member 2 (Them2) is a mitochondria-associated long-chain fatty acyl-CoA thioesterase that is activated upon binding phosphatidylcholine transfer protein (PC-TP). Under fasting conditions, the Them2/PC-TP complex directs saturated fatty acyl-CoA toward β-oxidation. Here, we showed that during either chronic overnutrition or acute induction of ER stress, Them2 and PC-TP play critical roles in trafficking SFAs into the glycerolipid biosynthetic pathway to form saturated phospholipids, which ultimately reduce ER membrane fluidity. The Them2/PC-TP complex activated ER stress pathways by enhancing translocon-mediated efflux of ER calcium. The increased cytosolic calcium, in turn, led to the phosphorylation of calcium/calmodulin-dependent protein kinase II, which promoted both hepatic insulin resistance and gluconeogenesis. These findings delineate a mechanistic link between obesity and insulin resistance and establish the Them2/PC-TP complex as an attractive target for the management of hepatic steatosis and insulin resistance.
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11
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Nicholls HT, Hornick JL, Cohen DE. Phosphatidylcholine transfer protein/StarD2 promotes microvesicular steatosis and liver injury in murine experimental steatohepatitis. Am J Physiol Gastrointest Liver Physiol 2017; 313:G50-G61. [PMID: 28385694 PMCID: PMC5538832 DOI: 10.1152/ajpgi.00379.2016] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Revised: 03/31/2017] [Accepted: 03/31/2017] [Indexed: 01/31/2023]
Abstract
Mice fed a methionine- and choline-deficient (MCD) diet develop steatohepatitis that recapitulates key features of nonalcoholic steatohepatitis (NASH) in humans. Phosphatidylcholine is the most abundant phospholipid in the surfactant monolayer that coats and stabilizes lipid droplets within cells, and choline is required for its major biosynthetic pathway. Phosphatidylcholine-transfer protein (PC-TP), which exchanges phosphatidylcholines among membranes, is enriched in hepatocytes. PC-TP also regulates fatty acid metabolism through interactions with thioesterase superfamily member 2. We investigated the contribution of PC-TP to steatohepatitis induced by the MCD diet. Pctp-/- and wild-type control mice were fed the MCD diet for 5 wk and were then euthanized for histopathologic and biochemical analyses, as well as determinations of mRNA and protein expression. Whereas all mice developed steatohepatitis, plasma alanine aminotransferase and aspartate aminotransferase activities were only elevated in wild-type mice, indicating that Pctp-/- mice were protected from MCD diet-induced hepatocellular injury. Reduced hepatotoxicity due to the MCD diet in the absence of PC-TP expression was further evidenced by decreased activation of c-Jun and reduced plasma concentrations of fibroblast growth factor 21. Despite similar total hepatic concentrations of phosphatidylcholines and other lipids, the relative abundance of microvesicular lipid droplets within hepatocytes was reduced in Pctp-/- mice. Considering that the formation of larger lipid droplets may serve to protect against lipotoxicity in NASH, our findings suggest a pathogenic role for PC-TP that could be targeted in the management of this condition.NEW & NOTEWORTHY Phosphatidylcholine-transfer protein (PC-TP) is a highly specific phosphatidylcholine-binding protein that we previously showed to regulate hepatocellular nutrient metabolism through its interacting partner thioesterase superfamily member 2 (Them2). This study identifies a pathogenic role for PC-TP, independent of Them2, in the methionine- and choline-deficient diet model of experimental steatohepatitis. Our current observations suggest that PC-TP promotes liver injury by mediating the intermembrane transfer of phosphatidylcholines, thus stabilizing more pathogenic microvesicular lipid droplets.
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Affiliation(s)
- Hayley T. Nicholls
- 1Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts; and
| | - Jason L. Hornick
- 2Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
| | - David E. Cohen
- 1Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts; and
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12
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Tillander V, Alexson SEH, Cohen DE. Deactivating Fatty Acids: Acyl-CoA Thioesterase-Mediated Control of Lipid Metabolism. Trends Endocrinol Metab 2017; 28:473-484. [PMID: 28385385 PMCID: PMC5474144 DOI: 10.1016/j.tem.2017.03.001] [Citation(s) in RCA: 93] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Accepted: 03/01/2017] [Indexed: 12/28/2022]
Abstract
The cellular uptake of free fatty acids (FFA) is followed by esterification to coenzyme A (CoA), generating fatty acyl-CoAs that are substrates for oxidation or incorporation into complex lipids. Acyl-CoA thioesterases (ACOTs) constitute a family of enzymes that hydrolyze fatty acyl-CoAs to form FFA and CoA. Although biochemically and biophysically well characterized, the metabolic functions of these enzymes remain incompletely understood. Existing evidence suggests regulatory roles in controlling rates of peroxisomal and mitochondrial fatty acyl-CoA oxidation, as well as in the subcellular trafficking of fatty acids. Emerging data implicate ACOTs in the pathogenesis of metabolic diseases, suggesting that better understanding their pathobiology could reveal unique targets in the management of obesity, diabetes, and nonalcoholic fatty liver disease.
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Affiliation(s)
- Veronika Tillander
- Division of Clinical Chemistry, Department of Laboratory Medicine, Karolinska Institutet, Karolinska University Hospital, Stockholm, 14186, Sweden
| | - Stefan E H Alexson
- Division of Clinical Chemistry, Department of Laboratory Medicine, Karolinska Institutet, Karolinska University Hospital, Stockholm, 14186, Sweden
| | - David E Cohen
- Division of Gastroenterology and Hepatology, Joan & Sanford I. Weill Department of Medicine, Weill Cornell Medical College, New York, NY 10021, USA.
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13
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Kong X, Simon LM, Holinstat M, Shaw CA, Bray PF, Edelstein LC. Identification of a functional genetic variant driving racially dimorphic platelet gene expression of the thrombin receptor regulator, PCTP. Thromb Haemost 2017; 117:962-970. [PMID: 28251237 DOI: 10.1160/th16-09-0692] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Accepted: 02/12/2017] [Indexed: 01/08/2023]
Abstract
Platelet activation in response to stimulation of the Protease Activated Receptor 4 (PAR4) receptor differs by race. One factor that contributes to this difference is the expression level of Phosphatidylcholine Transfer Protein (PCTP), a regulator of platelet PAR4 function. We have conducted an expression Quantitative Trait Locus (eQTL) analysis that identifies single nucleotide polymorphisms (SNPs) linked to the expression level of platelet genes. This analysis revealed 26 SNPs associated with the expression level of PCTP at genome-wide significance (p < 5×10-8). Using annotation from ENCODE and other public data we prioritised one of these SNPs, rs2912553, for functional testing. The allelic frequency of rs2912553 is racially-dimorphic, in concordance with the racially differential expression of PCTP. Reporter gene assays confirmed that the single nucleotide change caused by rs2912553 altered the transcriptional potency of the surrounding genomic locus. Electromobility shift assays, luciferase assays, and overexpression studies indicated a role for the megakaryocytic transcription factor GATA1. In summary, we have integrated multi-omic data to identify and functionalise an eQTL. This, along with the previously described relationship between PCTP and PAR4 function, allows us to characterise a genotype-phenotype relationship through the mechanism of gene expression.
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Affiliation(s)
| | | | | | | | | | - Leonard C Edelstein
- Leonard C. Edelstein, Department of Medicine Sidney Kimmel Medical College, Thomas Jefferson University, 1020 Locust Street, Suite 394, Philadelphia, PA 19107, USA, Tel.: +1 215 955 1797, Fax: +1 215 955 9170,
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14
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Krisko TI, LeClair KB, Cohen DE. Genetic ablation of phosphatidylcholine transfer protein/StarD2 in ob/ob mice improves glucose tolerance without increasing energy expenditure. Metabolism 2017; 68:145-149. [PMID: 28183446 PMCID: PMC5308448 DOI: 10.1016/j.metabol.2016.11.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Revised: 10/24/2016] [Accepted: 11/22/2016] [Indexed: 10/20/2022]
Abstract
OBJECTIVE Phosphatidylcholine transfer protein (PC-TP; synonym StarD2) is highly expressed in liver and oxidative tissues. PC-TP promotes hepatic glucose production during fasting and aggravates glucose intolerance in high fat fed mice. However, because PC-TP also suppresses thermogenesis in brown adipose tissue (BAT), its direct contribution to obesity-associated diabetes in mice remains unclear. Here we examined the effects of genetic PC-TP ablation on glucose homeostasis in leptin-deficient ob/ob mice, which exhibit both diabetes and altered thermoregulation. ANIMALS/METHODS Mice lacking both PC-TP and leptin (Pctp-/-;ob/ob) were prepared by crossing Pctp-/- with ob/+ mice. Glucose homeostasis was assessed by standard assays, and energy expenditure was determined by indirect calorimetry using a comprehensive laboratory animal monitoring system, which also recorded physical activity and food intake. Body composition was determined by NMR and hepatic lipids by enzymatic assays. Core body temperature was measured using a rectal thermocouple probe. RESULTS Pctp-/-;ob/ob mice demonstrated improved glucose homeostasis, as evidenced by markedly improved glucose and pyruvate tolerance tests, without changes in insulin tolerance. However, there were no differences in EE at any ambient temperature. There were also no effects of PC-TP expression on physical activity, food intake or core body temperature. CONCLUSIONS Improved glucose tolerance in Pctp-/-;ob/ob mice in the absence of increases in energy expenditure or core body temperature indicates a direct pathogenic role for PC-TP in diabetes in leptin deficient mice.
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Affiliation(s)
- Tibor I Krisko
- Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA, 02115, USA
| | - Katherine B LeClair
- Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA, 02115, USA
| | - David E Cohen
- Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA, 02115, USA.
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15
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Abstract
Since its discovery in the 19th century, phosphatidylcholine (PC) has been regarded primarily as a structural lipid. However, more recent evidence, much of it in the last five years, strongly suggests that PC has other roles. Here, we explore some of that new evidence and consider the possibility that the ultimate role of phosphatidylcholine may not be predictable.
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Affiliation(s)
- Samuel Furse
- a Membrane Biochemistry and Biophysics, University of Utrecht , Utrecht , The Netherlands
| | - Anton I P M de Kroon
- a Membrane Biochemistry and Biophysics, University of Utrecht , Utrecht , The Netherlands
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16
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Vance JE. Phospholipid Synthesis and Transport in Mammalian Cells. Traffic 2014; 16:1-18. [DOI: 10.1111/tra.12230] [Citation(s) in RCA: 376] [Impact Index Per Article: 37.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2014] [Revised: 09/17/2014] [Accepted: 09/18/2014] [Indexed: 01/18/2023]
Affiliation(s)
- Jean E. Vance
- Department of Medicine and Group on Molecular and Cell Biology of Lipids; University of Alberta; Edmonton AB Canada
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17
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Thioesterase superfamily member 2 (Them2) and phosphatidylcholine transfer protein (PC-TP) interact to promote fatty acid oxidation and control glucose utilization. Mol Cell Biol 2014; 34:2396-408. [PMID: 24732803 DOI: 10.1128/mcb.01601-13] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Thioesterase superfamily member 2 (Them2) is a mitochondrion-associated long-chain fatty acyl coenzyme A (CoA) thioesterase that is highly expressed in the liver and oxidative tissues. Them2 activity in vitro is increased when it interacts with phosphatidylcholine transfer protein (PC-TP), a cytosolic lipid binding protein. Them2-/- and Pctp-/- mice exhibit enhanced hepatic insulin sensitivity and increased adaptive thermogenesis, and Them2-/- mice are also resistant to diet-induced hepatic steatosis. Although we showed previously that a Them2-PC-TP complex suppresses insulin signaling, the enzymatic activity of Them2 suggests additional direct involvement in regulating hepatic nutrient homeostasis. Here we used cultured primary hepatocytes to elucidate biochemical and cellular mechanisms by which Them2 and PC-TP regulate lipid and glucose metabolism. Under conditions simulating fasting, Them2-/- and Pctp-/- hepatocytes each exhibited decreased rates of fatty acid oxidation and gluconeogenesis. In results indicative of Them2-dependent regulation by PC-TP, chemical inhibition of PC-TP failed to reproduce these changes in Them2-/- hepatocytes. In contrast, rates of glucose oxidation and lipogenesis in the presence of high glucose concentrations were decreased only in Them2-/- hepatocytes. These findings reveal a primary role for Them2 in promoting mitochondrial oxidation of fatty acids and glucose in the liver.
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18
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Racial differences in human platelet PAR4 reactivity reflect expression of PCTP and miR-376c. Nat Med 2013; 19:1609-16. [PMID: 24216752 PMCID: PMC3855898 DOI: 10.1038/nm.3385] [Citation(s) in RCA: 166] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Accepted: 09/20/2013] [Indexed: 12/17/2022]
Abstract
Racial differences in the pathophysiology of atherothrombosis are poorly understood. We explored the function and transcriptome of platelets in healthy black (n = 70) and white (n = 84) subjects. PAR4 thrombin receptor induced platelet aggregation and calcium mobilization were significantly greater in black subjects. Numerous differentially expressed (DE) RNAs were associated with both race and PAR4 reactivity, including phosphatidylcholine transfer protein (PCTP), and platelets from blacks expressed higher levels of PC-TP protein. PC-TP inhibition or depletion blocked activation of platelets or megakaryocytic cell lines through PAR4 but not PAR1. MiR-376c levels were DE by race and PAR4 reactivity, and were inversely correlated with PCTP mRNA levels, PC-TP protein levels and PAR4 reactivity. MiR-376c regulated expression of PC-TP in human megakaryocytes. A disproportionately high number of miRNAs DE by race and PAR4 reactivity, including miR-376c, are encoded in the DLK1-DIO3 locus, and were lower in platelets from blacks. These results support PC-TP as a regulator of the racial difference in PAR4-mediated platelet activation, indicate a genomic contribution to platelet function that differs by race, and emphasize a need to consider race effects when developing anti-thrombotic drugs.
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19
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Ersoy BA, Tarun A, D'Aquino K, Hancer NJ, Ukomadu C, White MF, Michel T, Manning BD, Cohen DE. Phosphatidylcholine transfer protein interacts with thioesterase superfamily member 2 to attenuate insulin signaling. Sci Signal 2013; 6:ra64. [PMID: 23901139 DOI: 10.1126/scisignal.2004111] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Phosphatidylcholine transfer protein (PC-TP) is a phospholipid-binding protein that is enriched in liver and that interacts with thioesterase superfamily member 2 (THEM2). Mice lacking either protein exhibit improved hepatic glucose homeostasis and are resistant to diet-induced diabetes. Insulin receptor substrate 2 (IRS2) and mammalian target of rapamycin complex 1 (mTORC1) are key effectors of insulin signaling, which is attenuated in diabetes. We found that PC-TP inhibited IRS2, as evidenced by insulin-independent IRS2 activation after knockdown, genetic ablation, or chemical inhibition of PC-TP. In addition, IRS2 was activated after knockdown of THEM2, providing support for a role for the interaction of PC-TP with THEM2 in suppressing insulin signaling. Additionally, we showed that PC-TP bound to tuberous sclerosis complex 2 (TSC2) and stabilized the components of the TSC1-TSC2 complex, which functions to inhibit mTORC1. Preventing phosphatidylcholine from binding to PC-TP disrupted interactions of PC-TP with THEM2 and TSC2, and disruption of the PC-TP-THEM2 complex was associated with increased activation of both IRS2 and mTORC1. In livers of mice with genetic ablation of PC-TP or that had been treated with a PC-TP inhibitor, steady-state amounts of IRS2 were increased, whereas those of TSC2 were decreased. These findings reveal a phospholipid-dependent mechanism that suppresses insulin signaling downstream of its receptor.
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Affiliation(s)
- Baran A Ersoy
- Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
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20
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The Lipid Transfer Protein StarD7: Structure, Function, and Regulation. Int J Mol Sci 2013; 14:6170-86. [PMID: 23507753 PMCID: PMC3634439 DOI: 10.3390/ijms14036170] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2012] [Revised: 02/17/2013] [Accepted: 02/22/2013] [Indexed: 02/06/2023] Open
Abstract
The steroidogenic acute regulatory (StAR) protein-related lipid transfer (START) domain proteins constitute a family of evolutionarily conserved and widely expressed proteins that have been implicated in lipid transport, metabolism, and signaling. The 15 well-characterized mammalian START domain-containing proteins are grouped into six subfamilies. The START domain containing 7 mRNA encodes StarD7, a member of the StarD2/phosphatidylcholine transfer protein (PCTP) subfamily, which was first identified as a gene overexpressed in a choriocarcinoma cell line. Recent studies show that the StarD7 protein facilitates the delivery of phosphatidylcholine to the mitochondria. This review summarizes the latest advances in StarD7 research, focusing on the structural and biochemical features, protein-lipid interactions, and mechanisms that regulate StarD7 expression. The implications of the role of StarD7 in cell proliferation, migration, and differentiation are also discussed.
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21
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Abstract
Members of the acyl-CoA thioesterase (Acot) gene family catalyze the hydrolysis of fatty acyl-CoA thioesters. Thioesterase superfamily member (Them) 1 (synonym: Acot11) is enriched in brown adipose tissue and is markedly upregulated when mice are exposed to cold ambient temperatures. In a recent study, we demonstrated that Them1−/− mice exhibit increased energy expenditure and are resistant to diet-induced obesity and its metabolic consequences. This mini-review places these findings in the context of an emerging understanding of Them/Acot genes.
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22
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Hochrath K, Krawczyk M, Goebel R, Langhirt M, Rathkolb B, Micklich K, Rozman J, Horsch M, Beckers J, Klingenspor M, Fuchs H, Gailus-Durner V, Wolf E, Acalovschi M, Volmer DA, Hrabě de Angelis M, Lammert F. The hepatic phosphatidylcholine transporter ABCB4 as modulator of glucose homeostasis. FASEB J 2012; 26:5081-91. [PMID: 22982378 DOI: 10.1096/fj.12-209379] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The hepatic phosphatidylcholine (PC) transporter ATP-binding cassette (ABC) B4 flops PC from hepatocytes into bile, and its dysfunction causes chronic cholestasis and fibrosis. Because a nuclear receptor-dependent PC pathway has been determined to exert antidiabetic effects, we now analyzed the role of ABCB4 in glucose metabolism. We bred congenic Abcb4-knockout (Abcb4(-/-)) mice on the fibrosis-susceptible BALB/cJ background. Knockout mice and wild-type controls were phenotyped by measuring plasma glucose concentrations, intraperitoneal glucose tolerance, hepatic RNA expression profiles, and liver histology. In addition, 4 procholestatic ABCB4 gene variants were correlated with blood glucose levels in 682 individuals from 2 independent European cohorts. Systemic glucose levels differ significantly between Abcb4(-/-) mice and wild-type controls, and knockout mice display improved glucose tolerance with significantly lower area under the curve values on intraperitoneal glucose challenge. Of note, hepatic expression of the antidiabetic nuclear receptor 5A2 (LRH-1) is induced consistently in Abcb4(-/-) mice, and its specific rare PC ligands are detected in liver by mass spectrometry imaging. In humans, serum glucose levels are associated significantly with the common ABCB4 variant c.711A>T. In summary, ABCB4 might play a critical role in glucose homeostasis in mice and humans. We speculate that the effects could be mediated via LRH-1-dependent PC pathways.
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MESH Headings
- ATP Binding Cassette Transporter, Subfamily B/genetics
- ATP Binding Cassette Transporter, Subfamily B/metabolism
- Adult
- Aged
- Aged, 80 and over
- Animals
- Blood Glucose/metabolism
- Cells, Cultured
- Cohort Studies
- Female
- Gallstones/blood
- Gallstones/genetics
- Gallstones/metabolism
- Gene Expression Profiling
- Homeostasis
- Humans
- Liver/metabolism
- Liver/pathology
- Male
- Mice
- Mice, Congenic
- Mice, Inbred BALB C
- Mice, Knockout
- Middle Aged
- Oligonucleotide Array Sequence Analysis
- Phosphatidylcholines/metabolism
- Polymorphism, Single Nucleotide
- Receptors, Cytoplasmic and Nuclear/genetics
- Receptors, Cytoplasmic and Nuclear/metabolism
- Young Adult
- ATP-Binding Cassette Sub-Family B Member 4
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Affiliation(s)
- Katrin Hochrath
- Department of Medicine II, Saarland University Medical Center, Kirrberger Str. 100, 66421 Homburg, Germany
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23
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Abstract
Lipid transfer proteins of the steroidogenic acute regulatory protein-related lipid transfer (START) domain family are defined by the presence of a conserved ∼210 amino acid sequence that folds into an α/β helix-grip structure forming a hydrophobic pocket for ligand binding. The mammalian START proteins bind diverse ligands, such as cholesterol, oxysterols, phospholipids, sphingolipids, and possibly fatty acids, and have putative roles in non-vesicular lipid transport, thioesterase enzymatic activity, and tumor suppression. However, the biological functions of many members of the START domain protein family are not well established. Recent research has focused on characterizing the cell-type distribution and regulation of the START proteins, examining the specificity and directionality of lipid transport, and identifying disease states associated with dysregulation of START protein expression. This review summarizes the current concepts of the proposed physiological and pathological roles for the mammalian START domain proteins in cholesterol and lipid trafficking.
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Affiliation(s)
- Barbara J Clark
- Department of Biochemistry and Molecular Biology, Center for Genetics and Molecular Medicine, School of Medicine, University of Louisville, Louisville, Kentucky 40292, USA.
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24
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Kang HW, Niepel MW, Han S, Kawano Y, Cohen DE. Thioesterase superfamily member 2/acyl-CoA thioesterase 13 (Them2/Acot13) regulates hepatic lipid and glucose metabolism. FASEB J 2012; 26:2209-21. [PMID: 22345407 DOI: 10.1096/fj.11-202853] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Members of the acyl-CoA thioesterase (Acot) gene family catalyze the hydrolysis of fatty acyl-CoAs, but their biological functions remain unknown. Thioesterase superfamily member 2 (Them2; synonym Acot13) is a broadly expressed mitochondria-associated Acot. Them2 was previously identified as an interacting protein of phosphatidylcholine transfer protein (PC-TP). Pctp(-/-) mice exhibit altered fatty acid metabolism that is accompanied by reduced hepatic glucose production. To examine the role of Them2 in regulating hepatic lipid and glucose homeostasis, we generated Them2(-/-) mice. In livers of Them2(-/-) mice compared with Them2(+/+) controls, a 1.9-fold increase in the K(m) of mitochondrial thioesterase activity was accompanied by a 28% increase in fatty acyl-CoA concentration. A reciprocal 23% decrease in free fatty acid concentration was associated with reduced activation of peroxisome proliferator-activated receptor α. However, fatty acid oxidation rates were preserved in livers of Them2(-/-) mice, suggesting that Them2 functions to limit β-oxidation. Hepatic glucose production was also decreased by 45% in the setting of reduced hepatocyte nuclear factor 4α (HNF4α) expression. When fed a high-fat diet, Them2(-/-) mice were resistant to increases in hepatic glucose production and steatosis. These findings reveal key roles for Them2 in the regulation of hepatic metabolism, which are potentially mediated by PC-TP-Them2 interactions.
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Affiliation(s)
- Hye Won Kang
- Department of Medicine, Division of Gastroenterology, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts, USA
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