1
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Little M, Ortlund EA. Structure, function, and lipid sensing activity in the thioesterase superfamily. Biochem Soc Trans 2024; 52:1565-1577. [PMID: 39140379 DOI: 10.1042/bst20230313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2024] [Revised: 08/02/2024] [Accepted: 08/05/2024] [Indexed: 08/15/2024]
Abstract
Lipid synthesis and transport are essential for energy, production of cell membrane, and cell signaling. Acyl-CoA thioesterases (ACOTs) function to regulate intracellular levels of fatty acyl-CoAs through hydrolysis. Two members of this family, ACOT11 and ACOT12, contain steroidogenic acute regulatory related lipid transfer domains, which typically function as lipid transport or regulatory domains. This work reviews ACOT11 and ACOT12 structures and functions, and the potential role of the START domains in lipid transfer activity and the allosteric regulation of catalytic activity.
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Affiliation(s)
- Molly Little
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia 30322, U.S.A
| | - Eric A Ortlund
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia 30322, U.S.A
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2
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Wojciechowska I, Mukherjee T, Knox-Brown P, Hu X, Khosla A, Subedi B, Ahmad B, Mathews GL, Panagakis AA, Thompson KA, Peery ST, Szlachetko J, Thalhammer A, Hincha DK, Skirycz A, Schrick K. Arabidopsis PROTODERMAL FACTOR2 binds lysophosphatidylcholines and transcriptionally regulates phospholipid metabolism. THE NEW PHYTOLOGIST 2024. [PMID: 38952028 DOI: 10.1111/nph.19917] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2024] [Accepted: 05/06/2024] [Indexed: 07/03/2024]
Abstract
Plant homeodomain leucine zipper IV (HD-Zip IV) transcription factors (TFs) contain an evolutionarily conserved steroidogenic acute regulatory protein (StAR)-related lipid transfer (START) domain. While the START domain is required for TF activity, its presumed role as a lipid sensor is not clear. Here we used tandem affinity purification from Arabidopsis cell cultures to demonstrate that PROTODERMAL FACTOR2 (PDF2), a representative member that controls epidermal differentiation, recruits lysophosphatidylcholines (LysoPCs) in a START-dependent manner. Microscale thermophoresis assays confirmed that a missense mutation in a predicted ligand contact site reduces lysophospholipid binding. We additionally found that PDF2 acts as a transcriptional regulator of phospholipid- and phosphate (Pi) starvation-related genes and binds to a palindromic octamer with consensus to a Pi response element. Phospholipid homeostasis and elongation growth were altered in pdf2 mutants according to Pi availability. Cycloheximide chase experiments revealed a role for START in maintaining protein levels, and Pi starvation resulted in enhanced protein destabilization, suggesting a mechanism by which lipid binding controls TF activity. We propose that the START domain serves as a molecular sensor for membrane phospholipid status in the epidermis. Our data provide insights toward understanding how the lipid metabolome integrates Pi availability with gene expression.
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Affiliation(s)
| | - Thiya Mukherjee
- Division of Biology, Kansas State University, Manhattan, KS, 66506, USA
- Molecular, Cellular and Developmental Biology, Kansas State University, Manhattan, KS, 66506, USA
- Donald Danforth Plant Science Center, Olivette, MO, 63132, USA
| | | | - Xueyun Hu
- Division of Biology, Kansas State University, Manhattan, KS, 66506, USA
- Joint International Research Laboratory of Agriculture and Agri-Product Safety of Ministry of Education of China, Yangzhou University, Yangzhou, 225009, China
| | - Aashima Khosla
- Division of Biology, Kansas State University, Manhattan, KS, 66506, USA
- Molecular, Cellular and Developmental Biology, Kansas State University, Manhattan, KS, 66506, USA
| | - Bibek Subedi
- Division of Biology, Kansas State University, Manhattan, KS, 66506, USA
- Molecular, Cellular and Developmental Biology, Kansas State University, Manhattan, KS, 66506, USA
| | - Bilal Ahmad
- Division of Biology, Kansas State University, Manhattan, KS, 66506, USA
- Molecular, Cellular and Developmental Biology, Kansas State University, Manhattan, KS, 66506, USA
| | - Graham L Mathews
- Division of Biology, Kansas State University, Manhattan, KS, 66506, USA
| | | | - Kyle A Thompson
- Division of Biology, Kansas State University, Manhattan, KS, 66506, USA
| | - Sophie T Peery
- Division of Biology, Kansas State University, Manhattan, KS, 66506, USA
| | - Jagoda Szlachetko
- Max Planck Institute of Molecular Plant Physiology, 14476, Potsdam, Germany
| | - Anja Thalhammer
- Physical Biochemistry, University of Potsdam, 14476, Potsdam, Germany
| | - Dirk K Hincha
- Max Planck Institute of Molecular Plant Physiology, 14476, Potsdam, Germany
| | - Aleksandra Skirycz
- Max Planck Institute of Molecular Plant Physiology, 14476, Potsdam, Germany
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, 48823, USA
| | - Kathrin Schrick
- Division of Biology, Kansas State University, Manhattan, KS, 66506, USA
- Molecular, Cellular and Developmental Biology, Kansas State University, Manhattan, KS, 66506, USA
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3
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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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4
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Schrick K, Ahmad B, Nguyen HV. HD-Zip IV transcription factors: Drivers of epidermal cell fate integrate metabolic signals. CURRENT OPINION IN PLANT BIOLOGY 2023; 75:102417. [PMID: 37441837 PMCID: PMC10527651 DOI: 10.1016/j.pbi.2023.102417] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Revised: 06/14/2023] [Accepted: 06/14/2023] [Indexed: 07/15/2023]
Abstract
The leaf epidermis comprises the outermost layer of cells that protect plants against environmental stresses such as drought, ultraviolet radiation, and pathogen attack. Research over the past decades highlights the role of class IV homeodomain leucine-zipper (HD-Zip IV) transcription factors (TFs) in driving differentiation of various epidermal cell types, such as trichomes, guard cells, and pavement cells. Evolutionary origins of this family in the charophycean green algae and HD-Zip-specific gene expression in the maternal genome provide clues to unlocking their secrets which include ties to cell cycle regulation. A distinguishing feature of these TFs is the presence of a lipid binding pocket that integrates metabolic information with gene expression. Identities of metabolic partners are beginning to emerge, uncovering feedback loops to maintain epidermal cell specification. Discoveries of associated molecular mechanisms are revealing fascinating links to phospholipid and sphingolipid metabolism and mechanical signaling.
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Affiliation(s)
- Kathrin Schrick
- Molecular, Cellular, and Developmental Biology, Kansas State University, Manhattan, KS 66506, USA; Division of Biology, Kansas State University, Manhattan, KS 66506, USA.
| | - Bilal Ahmad
- Molecular, Cellular, and Developmental Biology, Kansas State University, Manhattan, KS 66506, USA; Division of Biology, Kansas State University, Manhattan, KS 66506, USA
| | - Hieu V Nguyen
- Division of Biology, Kansas State University, Manhattan, KS 66506, USA
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5
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Liao J, Lederer V, Bardhi A, Zou Z, Hoffmann TD, Sun G, Song C, Hoffmann T, Schwab W. Acceptors and Effectors Alter Substrate Inhibition Kinetics of a Plant Glucosyltransferase NbUGT72AY1 and Its Mutants. Int J Mol Sci 2023; 24:ijms24119542. [PMID: 37298492 DOI: 10.3390/ijms24119542] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Revised: 05/22/2023] [Accepted: 05/25/2023] [Indexed: 06/12/2023] Open
Abstract
One of the main obstacles in biocatalysis is the substrate inhibition (SI) of enzymes that play important roles in biosynthesis and metabolic regulation in organisms. The promiscuous glycosyltransferase UGT72AY1 from Nicotiana benthamiana is strongly substrate-inhibited by hydroxycoumarins (inhibitory constant Ki < 20 µM), but only weakly inhibited when monolignols are glucosylated (Ki > 1000 µM). Apocarotenoid effectors reduce the inherent UDP-glucose glucohydrolase activity of the enzyme and attenuate the SI by scopoletin derivatives, which could also be achieved by mutations. Here, we studied the kinetic profiles of different phenols and used the substrate analog vanillin, which has shown atypical Michaelis-Menten kinetics in previous studies, to examine the effects of different ligands and mutations on the SI of NbUGT72AY1. Coumarins had no effect on enzymatic activity, whereas apocarotenoids and fatty acids strongly affected SI kinetics by increasing the inhibition constant Ki. Only the F87I mutant and a chimeric version of the enzyme showed weak SI with the substrate vanillin, but all mutants exhibited mild SI when sinapaldehyde was used as an acceptor. In contrast, stearic acid reduced the transferase activity of the mutants to varying degrees. The results not only confirm the multi-substrate functionality of NbUGT72AY1, but also reveal that the enzymatic activity of this protein can be fine-tuned by external metabolites such as apocarotenoids and fatty acids that affect SI. Since these signals are generated during plant cell destruction, NbUGT72AY1 likely plays an important role in plant defense by participating in the production of lignin in the cell wall and providing direct protection through the formation of toxic phytoalexins.
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Affiliation(s)
- Jieren Liao
- Biotechnology of Natural Products, Technische Universität München, Liesel-Beckmann-Str. 1, 85354 Freising, Germany
| | - Veronika Lederer
- Biotechnology of Natural Products, Technische Universität München, Liesel-Beckmann-Str. 1, 85354 Freising, Germany
| | - Alba Bardhi
- Biotechnology of Natural Products, Technische Universität München, Liesel-Beckmann-Str. 1, 85354 Freising, Germany
| | - Zhiwei Zou
- Biotechnology of Natural Products, Technische Universität München, Liesel-Beckmann-Str. 1, 85354 Freising, Germany
| | - Timothy D Hoffmann
- Biotechnology of Natural Products, Technische Universität München, Liesel-Beckmann-Str. 1, 85354 Freising, Germany
| | - Guangxin Sun
- Biotechnology of Natural Products, Technische Universität München, Liesel-Beckmann-Str. 1, 85354 Freising, Germany
| | - Chuankui Song
- State Key Laboratory of Tea Plant Biology and Utilization, International Joint Laboratory on Tea Chemistry and Health Effects, Anhui Agricultural University, Hefei 230036, China
| | - Thomas Hoffmann
- Biotechnology of Natural Products, Technische Universität München, Liesel-Beckmann-Str. 1, 85354 Freising, Germany
| | - Wilfried Schwab
- Biotechnology of Natural Products, Technische Universität München, Liesel-Beckmann-Str. 1, 85354 Freising, Germany
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6
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Husbands AY, Feller A, Aggarwal V, Dresden CE, Holub AS, Ha T, Timmermans MCP. The START domain potentiates HD-ZIPIII transcriptional activity. THE PLANT CELL 2023; 35:2332-2348. [PMID: 36861320 DOI: 10.1093/plcell/koad058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 01/09/2023] [Accepted: 02/05/2023] [Indexed: 05/30/2023]
Abstract
The CLASS III HOMEODOMAIN-LEUCINE ZIPPER (HD-ZIPIII) transcription factors (TFs) were repeatedly deployed over 725 million years of evolution to regulate central developmental innovations. The START domain of this pivotal class of developmental regulators was recognized over 20 years ago, but its putative ligands and functional contributions remain unknown. Here, we demonstrate that the START domain promotes HD-ZIPIII TF homodimerization and increases transcriptional potency. Effects on transcriptional output can be ported onto heterologous TFs, consistent with principles of evolution via domain capture. We also show the START domain binds several species of phospholipids, and that mutations in conserved residues perturbing ligand binding and/or its downstream conformational readout abolish HD-ZIPIII DNA-binding competence. Our data present a model in which the START domain potentiates transcriptional activity and uses ligand-induced conformational change to render HD-ZIPIII dimers competent to bind DNA. These findings resolve a long-standing mystery in plant development and highlight the flexible and diverse regulatory potential coded within this widely distributed evolutionary module.
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Affiliation(s)
- Aman Y Husbands
- Cold Spring Harbor Laboratory, 1 Bungtown Road, Cold Spring Harbor, NY 11724, USA
- Department of Biology, University of Pennsylvania, 415 S. University Ave, Philadelphia, PA 19104, USA
| | - Antje Feller
- Center for Plant Molecular Biology, University of Tübingen, Auf der Morgenstelle 32, 72076 Tübingen, Germany
| | - Vasudha Aggarwal
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins School of Medicine, Baltimore, MD 21205, USA
| | - Courtney E Dresden
- Department of Biology, University of Pennsylvania, 415 S. University Ave, Philadelphia, PA 19104, USA
- Molecular, Cellular, and Developmental Biology (MCDB), The Ohio State University, Columbus, OH 43215, USA
| | - Ashton S Holub
- Department of Molecular Genetics, The Ohio State University, Columbus, OH 43215, USA
| | - Taekjip Ha
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins School of Medicine, Baltimore, MD 21205, USA
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins School of Medicine, Howard Hughes Medical Institute, Baltimore, MD 21205, USA
| | - Marja C P Timmermans
- Cold Spring Harbor Laboratory, 1 Bungtown Road, Cold Spring Harbor, NY 11724, USA
- Center for Plant Molecular Biology, University of Tübingen, Auf der Morgenstelle 32, 72076 Tübingen, Germany
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7
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Druzak SA, Tardelli M, Mays SG, El Bejjani M, Mo X, Maner-Smith KM, Bowen T, Cato ML, Tillman MC, Sugiyama A, Xie Y, Fu H, Cohen DE, Ortlund EA. Ligand dependent interaction between PC-TP and PPARδ mitigates diet-induced hepatic steatosis in male mice. Nat Commun 2023; 14:2748. [PMID: 37173315 PMCID: PMC10182070 DOI: 10.1038/s41467-023-38010-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Accepted: 04/12/2023] [Indexed: 05/15/2023] Open
Abstract
Phosphatidylcholine transfer protein (PC-TP; synonym StarD2) is a soluble lipid-binding protein that transports phosphatidylcholine (PC) between cellular membranes. To better understand the protective metabolic effects associated with hepatic PC-TP, we generated a hepatocyte-specific PC-TP knockdown (L-Pctp-/-) in male mice, which gains less weight and accumulates less liver fat compared to wild-type mice when challenged with a high-fat diet. Hepatic deletion of PC-TP also reduced adipose tissue mass and decreases levels of triglycerides and phospholipids in skeletal muscle, liver and plasma. Gene expression analysis suggest that the observed metabolic changes are related to transcriptional activity of peroxisome proliferative activating receptor (PPAR) family members. An in-cell protein complementation screen between lipid transfer proteins and PPARs uncovered a direct interaction between PC-TP and PPARδ that was not observed for other PPARs. We confirmed the PC-TP- PPARδ interaction in Huh7 hepatocytes, where it was found to repress PPARδ-mediated transactivation. Mutations of PC-TP residues implicated in PC binding and transfer reduce the PC-TP-PPARδ interaction and relieve PC-TP-mediated PPARδ repression. Reduction of exogenously supplied methionine and choline reduces the interaction while serum starvation enhances the interaction in cultured hepatocytes. Together our data points to a ligand sensitive PC-TP- PPARδ interaction that suppresses PPAR activity.
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Affiliation(s)
- Samuel A Druzak
- Department of Biochemistry, Emory University School of Medicine, 1510 Clifton Road, Atlanta, GA, USA
| | - Matteo Tardelli
- Joan & Sanford I. Weill Department of Medicine, Weill Cornell Medical College, New York, NY, USA
| | - Suzanne G Mays
- Department of Biochemistry, Emory University School of Medicine, 1510 Clifton Road, Atlanta, GA, USA
| | - Mireille El Bejjani
- Department of Biochemistry, Emory University School of Medicine, 1510 Clifton Road, Atlanta, GA, USA
| | - Xulie Mo
- Department of Chemical Biology and Pharmacology, Emory University School of Medicine, 1510 Clifton Road, Atlanta, GA, USA
| | - Kristal M Maner-Smith
- Emory Integrated Lipidomics and Metabolomics Core, Emory University School of Medicine, 1510 Clifton Road, Atlanta, GA, USA
| | - Thomas Bowen
- Emory Integrated Lipidomics and Metabolomics Core, Emory University School of Medicine, 1510 Clifton Road, Atlanta, GA, USA
| | - Michael L Cato
- Department of Biochemistry, Emory University School of Medicine, 1510 Clifton Road, Atlanta, GA, USA
| | - Matthew C Tillman
- Department of Biochemistry, Emory University School of Medicine, 1510 Clifton Road, Atlanta, GA, USA
| | - Akiko Sugiyama
- Joan & Sanford I. Weill Department of Medicine, Weill Cornell Medical College, New York, NY, USA
- Division of Gastroenterology, Hepatology and Endoscopy, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Yang Xie
- Joan & Sanford I. Weill Department of Medicine, Weill Cornell Medical College, New York, NY, USA
- Division of Gastroenterology, Hepatology and Endoscopy, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Haian Fu
- Department of Chemical Biology and Pharmacology, Emory University School of Medicine, 1510 Clifton Road, Atlanta, GA, USA
| | - David E Cohen
- Joan & Sanford I. Weill Department of Medicine, Weill Cornell Medical College, New York, NY, USA
- Division of Gastroenterology, Hepatology and Endoscopy, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Eric A Ortlund
- Department of Biochemistry, Emory University School of Medicine, 1510 Clifton Road, Atlanta, GA, USA.
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8
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Heintz MM, Eccles JA, Olack EM, Maner-Smith KM, Ortlund EA, Baldwin WS. Human CYP2B6 produces oxylipins from polyunsaturated fatty acids and reduces diet-induced obesity. PLoS One 2022; 17:e0277053. [PMID: 36520866 PMCID: PMC9754190 DOI: 10.1371/journal.pone.0277053] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Accepted: 10/18/2022] [Indexed: 12/23/2022] Open
Abstract
Multiple factors in addition to over consumption lead to obesity and non-alcoholic fatty liver disease (NAFLD) in the United States and worldwide. CYP2B6 is the only human detoxification CYP whose loss is associated with obesity, and Cyp2b-null mice show greater diet-induced obesity with increased steatosis than wildtype mice. However, a putative mechanism has not been determined. LC-MS/MS revealed that CYP2B6 metabolizes PUFAs, with a preference for metabolism of ALA to 9-HOTrE and to a lesser extent 13-HOTrE with a preference for metabolism of PUFAs at the 9- and 13-positions. To further study the role of CYP2B6 in vivo, humanized-CYP2B6-transgenic (hCYP2B6-Tg) and Cyp2b-null mice were fed a 60% high-fat diet for 16 weeks. Compared to Cyp2b-null mice, hCYP2B6-Tg mice showed reduced weight gain and metabolic disease as measured by glucose tolerance tests, however hCYP2B6-Tg male mice showed increased liver triglycerides. Serum and liver oxylipin metabolite concentrations increased in male hCYP2B6-Tg mice, while only serum oxylipins increased in female hCYP2B6-Tg mice with the greatest increases in LA oxylipins metabolized at the 9 and 13-positions. Several of these oxylipins, specifically 9-HODE, 9-HOTrE, and 13-oxoODE, are PPAR agonists. RNA-seq data also demonstrated sexually dimorphic changes in gene expression related to nuclear receptor signaling, especially CAR > PPAR with qPCR suggesting PPARγ signaling is more likely than PPARα signaling in male mice. Overall, our data indicates that CYP2B6 is an anti-obesity enzyme, but probably to a lesser extent than murine Cyp2b's. Therefore, the inhibition of CYP2B6 by xenobiotics or dietary fats can exacerbate obesity and metabolic disease potentially through disrupted PUFA metabolism and the production of key lipid metabolites.
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Affiliation(s)
- Melissa M. Heintz
- Biological Sciences, Clemson University, Clemson, South Carolina, United States of America
| | - Jazmine A. Eccles
- Biological Sciences, Clemson University, Clemson, South Carolina, United States of America
| | - Emily M. Olack
- Biological Sciences, Clemson University, Clemson, South Carolina, United States of America
| | - Kristal M. Maner-Smith
- Emory Integrated Metabolomics and Lipodomics Core, Emory University, Atlanta, Georgia, United States of America
| | - Eric A. Ortlund
- Department of Biochemistry, Emory University School of Medicine, Emory University, Atlanta, Georgia, United States of America
| | - William S. Baldwin
- Biological Sciences, Clemson University, Clemson, South Carolina, United States of America
- * E-mail:
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9
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Mukherjee T, Subedi B, Khosla A, Begler EM, Stephens PM, Warner AL, Lerma-Reyes R, Thompson KA, Gunewardena S, Schrick K. The START domain mediates Arabidopsis GLABRA2 dimerization and turnover independently of homeodomain DNA binding. PLANT PHYSIOLOGY 2022; 190:2315-2334. [PMID: 35984304 PMCID: PMC9706451 DOI: 10.1093/plphys/kiac383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Accepted: 06/09/2022] [Indexed: 05/08/2023]
Abstract
Class IV homeodomain leucine-zipper transcription factors (HD-Zip IV TFs) are key regulators of epidermal differentiation that are characterized by a DNA-binding HD in conjunction with a lipid-binding domain termed steroidogenic acute regulatory-related lipid transfer (START). Previous work established that the START domain of GLABRA2 (GL2), a HD-Zip IV member from Arabidopsis (Arabidopsis thaliana), is required for TF activity. Here, we addressed the functions and possible interactions of START and the HD in DNA binding, dimerization, and protein turnover. Deletion analysis of the HD and missense mutations of a conserved lysine (K146) resulted in phenotypic defects in leaf trichomes, root hairs, and seed mucilage, similar to those observed for START domain mutants, despite nuclear localization of the respective proteins. In vitro and in vivo experiments demonstrated that while HD mutations impair binding to target DNA, the START domain is dispensable for DNA binding. Vice versa, protein interaction assays revealed impaired GL2 dimerization for multiple alleles of START mutants, but not HD mutants. Using in vivo cycloheximide chase experiments, we provided evidence for the role of START, but not HD, in maintaining protein stability. This work advances our mechanistic understanding of HD-Zip TFs as multidomain regulators of epidermal development in plants.
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Affiliation(s)
- Thiya Mukherjee
- Division of Biology, Kansas State University, Manhattan, Kansas 66506, USA
- Molecular, Cellular and Developmental Biology, Kansas State University, Manhattan, Kansas 66506, USA
- Donald Danforth Plant Science Center, Olivette, Missouri 63132, USA
| | - Bibek Subedi
- Division of Biology, Kansas State University, Manhattan, Kansas 66506, USA
- Molecular, Cellular and Developmental Biology, Kansas State University, Manhattan, Kansas 66506, USA
| | - Aashima Khosla
- Division of Biology, Kansas State University, Manhattan, Kansas 66506, USA
- Molecular, Cellular and Developmental Biology, Kansas State University, Manhattan, Kansas 66506, USA
- Department of Botany and Plant Sciences, University of California, Riverside, California 92521, USA
| | - Erika M Begler
- Division of Biology, Kansas State University, Manhattan, Kansas 66506, USA
| | - Preston M Stephens
- Division of Biology, Kansas State University, Manhattan, Kansas 66506, USA
| | - Adara L Warner
- Division of Biology, Kansas State University, Manhattan, Kansas 66506, USA
| | - Ruben Lerma-Reyes
- Division of Biology, Kansas State University, Manhattan, Kansas 66506, USA
- Interdepartmental Genetics, Kansas State University, Manhattan, Kansas 66506, USA
| | - Kyle A Thompson
- Division of Biology, Kansas State University, Manhattan, Kansas 66506, USA
| | - Sumedha Gunewardena
- Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, Kansas 66160, USA
| | - Kathrin Schrick
- Division of Biology, Kansas State University, Manhattan, Kansas 66506, USA
- Molecular, Cellular and Developmental Biology, Kansas State University, Manhattan, Kansas 66506, USA
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10
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Dresden CE, Ashraf Q, Husbands AY. Diverse regulatory mechanisms of StARkin domains in land plants and mammals. CURRENT OPINION IN PLANT BIOLOGY 2021; 64:102148. [PMID: 34814028 DOI: 10.1016/j.pbi.2021.102148] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 10/12/2021] [Accepted: 10/28/2021] [Indexed: 06/13/2023]
Abstract
The StARkin domain (derived from 'kin of steroidogenic acute regulatory protein (StAR)') is an evolutionarily conserved helix-grip-fold structure. StARkin domains possess a deep hydrophobic pocket capable of binding lipophilic ligands such as fatty acids, sterols, and isoprenoids. Dysregulation of StARkin proteins has profound effects on disease and development. In this review, we profile recent mechanistic and evolutionary studies, which highlight the remarkable diversity of regulatory mechanisms employed by the StARkin module. Although primarily focused on land plants, we also discuss select key advances in mammalian StARkin biology. The diversity of perspectives, systems, and approaches described here may be helpful to researchers characterizing poorly understood StARkin proteins.
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Affiliation(s)
- Courtney E Dresden
- Molecular, Cellular, and Developmental Biology (MCDB), the Ohio State University, Columbus, OH 43215, USA
| | - Quratulayn Ashraf
- Molecular, Cellular, and Developmental Biology (MCDB), the Ohio State University, Columbus, OH 43215, USA
| | - Aman Y Husbands
- Molecular, Cellular, and Developmental Biology (MCDB), the Ohio State University, Columbus, OH 43215, USA; Department of Molecular Genetics, The Ohio State University, Columbus, OH 43215, USA; Center for Applied Plant Sciences (CAPS), The Ohio State University, Columbus, OH 43215, USA.
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Identifying Cancer-Relevant Mutations in the DLC START Domain Using Evolutionary and Structure-Function Analyses. Int J Mol Sci 2020; 21:ijms21218175. [PMID: 33142932 PMCID: PMC7662654 DOI: 10.3390/ijms21218175] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 10/22/2020] [Accepted: 10/30/2020] [Indexed: 01/05/2023] Open
Abstract
Rho GTPase signaling promotes proliferation, invasion, and metastasis in a broad spectrum of cancers. Rho GTPase activity is regulated by the deleted in liver cancer (DLC) family of bona fide tumor suppressors which directly inactivate Rho GTPases by stimulating GTP hydrolysis. In addition to a RhoGAP domain, DLC proteins contain a StAR-related lipid transfer (START) domain. START domains in other organisms bind hydrophobic small molecules and can regulate interacting partners or co-occurring domains through a variety of mechanisms. In the case of DLC proteins, their START domain appears to contribute to tumor suppressive activity. However, the nature of this START-directed mechanism, as well as the identities of relevant functional residues, remain virtually unknown. Using the Catalogue of Somatic Mutations in Cancer (COSMIC) dataset and evolutionary and structure-function analyses, we identify several conserved residues likely to be required for START-directed regulation of DLC-1 and DLC-2 tumor-suppressive capabilities. This pan-cancer analysis shows that conserved residues of both START domains are highly overrepresented in cancer cells from a wide range tissues. Interestingly, in DLC-1 and DLC-2, three of these residues form multiple interactions at the tertiary structural level. Furthermore, mutation of any of these residues is predicted to disrupt interactions and thus destabilize the START domain. As such, these mutations would not have emerged from traditional hotspot scans of COSMIC. We propose that evolutionary and structure-function analyses are an underutilized strategy which could be used to unmask cancer-relevant mutations within COSMIC. Our data also suggest DLC-1 and DLC-2 as high-priority candidates for development of novel therapeutics that target their START domain.
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