1
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Ansell TB, Healy M, Coupland CE, Sansom MSP, Siebold C. Mapping structural and dynamic divergence across the MBOAT family. Structure 2024; 32:1011-1022.e3. [PMID: 38636523 DOI: 10.1016/j.str.2024.03.014] [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: 12/14/2023] [Revised: 02/09/2024] [Accepted: 03/22/2024] [Indexed: 04/20/2024]
Abstract
Membrane-bound O-acyltransferases (MBOATs) are membrane-embedded enzymes that catalyze acyl chain transfer to a diverse group of substrates, including lipids, small molecules, and proteins. MBOATs share a conserved structural core, despite wide-ranging functional specificity across both prokaryotes and eukaryotes. The structural basis of catalytic specificity, regulation and interactions with the surrounding environment remain uncertain. Here, we combine comparative molecular dynamics (MD) simulations with bioinformatics to assess molecular and interactional divergence across the family. In simulations, MBOATs differentially distort the bilayer depending on their substrate type. Additionally, we identify lipid binding sites surrounding reactant gates in the surrounding membrane. Complementary bioinformatic analyses reveal a conserved role for re-entrant loop-2 in MBOAT fold stabilization and a key hydrogen bond bridging DGAT1 dimerization. Finally, we predict differences in MBOAT solvation and water gating properties. These data are pertinent to the design of MBOAT-specific inhibitors that encompass dynamic information within cellular mimetic environments.
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Affiliation(s)
- T Bertie Ansell
- Department of Biochemistry, South Parks Road, Oxford OX1 3QU, UK; Division of CryoEM and Bioimaging, SSRL, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA; Department of Biology, Stanford University, Stanford, CA 94305, USA.
| | - Megan Healy
- Department of Biochemistry, South Parks Road, Oxford OX1 3QU, UK
| | - Claire E Coupland
- Division of Structural Biology, Wellcome Centre for Human Genetics, Roosevelt Drive, Oxford OX3 7BN, UK; Molecular Medicine Program, The Hospital for Sick Children, 686 Bay Street, Toronto M5G 0A4, Canada
| | - Mark S P Sansom
- Department of Biochemistry, South Parks Road, Oxford OX1 3QU, UK
| | - Christian Siebold
- Division of Structural Biology, Wellcome Centre for Human Genetics, Roosevelt Drive, Oxford OX3 7BN, UK
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2
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Ji J, Carpentier B, Chakraborty A, Nangia S. An Affordable Topography-Based Protocol for Assigning a Residue's Character on a Hydropathy (PARCH) Scale. J Chem Theory Comput 2024; 20:1656-1672. [PMID: 37018141 PMCID: PMC10902853 DOI: 10.1021/acs.jctc.3c00106] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Indexed: 04/06/2023]
Abstract
The hydropathy of proteins or quantitative assessment of protein-water interactions has been a topic of interest for decades. Most hydropathy scales use a residue-based or atom-based approach to assign fixed numerical values to the 20 amino acids and categorize them as hydrophilic, hydroneutral, or hydrophobic. These scales overlook the protein's nanoscale topography, such as bumps, crevices, cavities, clefts, pockets, and channels, in calculating the hydropathy of the residues. Some recent studies have included protein topography in determining hydrophobic patches on protein surfaces, but these methods do not provide a hydropathy scale. To overcome the limitations in the existing methods, we have developed a Protocol for Assigning a Residue's Character on the Hydropathy (PARCH) scale that adopts a holistic approach to assigning the hydropathy of a residue. The parch scale evaluates the collective response of the water molecules in the protein's first hydration shell to increasing temperatures. We performed the parch analysis of a set of well-studied proteins that include the following─enzymes, immune proteins, and integral membrane proteins, as well as fungal and virus capsid proteins. Since the parch scale evaluates every residue based on its location, a residue may have very different parch values inside a crevice versus a surface bump. Thus, a residue can have a range of parch values (or hydropathies) dictated by the local geometry. The parch scale calculations are computationally inexpensive and can compare hydropathies of different proteins. The parch analysis can affordably and reliably aid in designing nanostructured surfaces, identifying hydrophilic and hydrophobic patches, and drug discovery.
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Affiliation(s)
- Jingjing Ji
- Department
of Biomedical and Chemical Engineering, Syracuse University, Syracuse, New York 13244, United States
| | - Britnie Carpentier
- Department
of Biomedical and Chemical Engineering, Syracuse University, Syracuse, New York 13244, United States
| | - Arindam Chakraborty
- Department
of Chemistry, Syracuse University, Syracuse, New York 13244, United States
| | - Shikha Nangia
- Department
of Biomedical and Chemical Engineering, Syracuse University, Syracuse, New York 13244, United States
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3
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Pierce M, Ji J, Novak SX, Sieburg MA, Nangia S, Nangia S, Hougland JL. Combined Computational-Biochemical Approach Offers an Accelerated Path to Membrane Protein Solubilization. J Chem Inf Model 2023; 63:7159-7170. [PMID: 37939203 PMCID: PMC10685452 DOI: 10.1021/acs.jcim.3c00917] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2023] [Revised: 10/25/2023] [Accepted: 10/25/2023] [Indexed: 11/10/2023]
Abstract
Membrane proteins are difficult to isolate and purify due to their dependence on the surrounding lipid membrane for structural stability. Detergents are often used to solubilize these proteins, with this approach requiring a careful balance between protein solubilization and denaturation. Determining which detergent is most appropriate for a given protein has largely been done empirically through screening, which requires large amounts of membrane protein and associated resources. Here, we describe an alternative to conventional detergent screening using a computational modeling approach to identify the most likely candidate detergents for solubilizing a protein of interest. We demonstrate our approach using ghrelin O-acyltransferase (GOAT), a member of the membrane-bound O-acyltransferase family of integral membrane enzymes that has not been solubilized or purified in active form. A computationally derived GOAT structural model provides the only structural information required for this approach. Using computational analysis of detergent ability to penetrate phospholipid bilayers and stabilize the GOAT structure, a panel of common detergents were rank-ordered for their proposed ability to solubilize GOAT. The simulations were performed at all-atom resolution for a combined simulation time of 24 μs. Independently, we biologically screened these detergents for their solubilization of fluorescently tagged GOAT constructs. We found computational prediction of protein structural stabilization was the better predictor of detergent solubilization ability, but neither approach was effective for predicting detergents that would support GOAT enzymatic function. The current rapid expansion of membrane protein computational models lacking experimental structural information and our computational detergent screening approach can greatly improve the efficiency of membrane protein detergent solubilization, supporting downstream functional and structural studies.
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Affiliation(s)
- Mariah
R. Pierce
- Department
of Chemistry, Syracuse University, Syracuse, New York 13244, United States
| | - Jingjing Ji
- Department
of Biomedical and Chemical Engineering, Syracuse University, Syracuse, New York 13244, United States
| | - Sadie X. Novak
- Department
of Chemistry, Syracuse University, Syracuse, New York 13244, United States
| | - Michelle A. Sieburg
- Department
of Chemistry, Syracuse University, Syracuse, New York 13244, United States
| | - Shivangi Nangia
- Department
of Chemistry, University of Hartford, West Hartford, Connecticut 06117, United States
| | - Shikha Nangia
- Department
of Biomedical and Chemical Engineering, Syracuse University, Syracuse, New York 13244, United States
- BioInspired
Syracuse, Syracuse, New York 13244, United States
| | - James L. Hougland
- Department
of Chemistry, Syracuse University, Syracuse, New York 13244, United States
- BioInspired
Syracuse, Syracuse, New York 13244, United States
- Department
of Biology, Syracuse University, Syracuse, New York 13244, United States
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4
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Campaña M, Davis TR, Novak SX, Cleverdon ER, Bates M, Krishnan N, Curtis ER, Childs MD, Pierce MR, Morales-Rodriguez Y, Sieburg MA, Hehnly H, Luyt LG, Hougland JL. Cellular Uptake of a Fluorescent Ligand Reveals Ghrelin O-Acyltransferase Interacts with Extracellular Peptides and Exhibits Unexpected Localization for a Secretory Pathway Enzyme. ACS Chem Biol 2023; 18:1880-1890. [PMID: 37494676 PMCID: PMC10442857 DOI: 10.1021/acschembio.3c00334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Accepted: 07/17/2023] [Indexed: 07/28/2023]
Abstract
Ghrelin O-acyltransferase (GOAT) plays a central role in the maturation and activation of the peptide hormone ghrelin, which performs a wide range of endocrinological signaling roles. Using a tight-binding fluorescent ghrelin-derived peptide designed for high selectivity for GOAT over the ghrelin receptor GHSR, we demonstrate that GOAT interacts with extracellular ghrelin and facilitates ligand cell internalization in both transfected cells and prostate cancer cells endogenously expressing GOAT. Coupled with enzyme mutagenesis, ligand uptake studies support the interaction of the putative histidine general base within GOAT with the ghrelin peptide acylation site. Our work provides a new understanding of GOAT's catalytic mechanism, establishes that GOAT can interact with ghrelin and other peptides located outside the cell, and raises the possibility that other peptide hormones may exhibit similar complexity in their intercellular and organismal-level signaling pathways.
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Affiliation(s)
- Maria
B. Campaña
- Department
of Chemistry, Syracuse University, Syracuse, New York 13244, United States
| | - Tasha R. Davis
- Department
of Chemistry, Syracuse University, Syracuse, New York 13244, United States
| | - Sadie X. Novak
- Department
of Chemistry, Syracuse University, Syracuse, New York 13244, United States
| | | | - Michael Bates
- Department
of Biology, Syracuse University, Syracuse, New York 13244, United States
| | - Nikhila Krishnan
- Department
of Biology, Syracuse University, Syracuse, New York 13244, United States
| | - Erin R. Curtis
- Department
of Biology, Syracuse University, Syracuse, New York 13244, United States
| | - Marina D. Childs
- Department
of Chemistry, University of Western Ontario, London, Ontario N6A 2K7, Canada
| | - Mariah R. Pierce
- Department
of Chemistry, Syracuse University, Syracuse, New York 13244, United States
| | | | - Michelle A. Sieburg
- Department
of Chemistry, Syracuse University, Syracuse, New York 13244, United States
| | - Heidi Hehnly
- Department
of Biology, Syracuse University, Syracuse, New York 13244, United States
- BioInspired
Syracuse, Syracuse University, Syracuse, New York 13244, United States
| | - Leonard G. Luyt
- Department
of Chemistry, University of Western Ontario, London, Ontario N6A 2K7, Canada
- Department
of Oncology and Department of Medical Imaging, London Regional Cancer
Program, Lawson Health Research Institute, 800 Commissioners Road East, London, Ontario N6A 5W9, Canada
| | - James L. Hougland
- Department
of Chemistry, Syracuse University, Syracuse, New York 13244, United States
- Department
of Biology, Syracuse University, Syracuse, New York 13244, United States
- BioInspired
Syracuse, Syracuse University, Syracuse, New York 13244, United States
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5
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Coupland CE, Ansell TB, Sansom MSP, Siebold C. Rocking the MBOAT: Structural insights into the membrane bound O-acyltransferase family. Curr Opin Struct Biol 2023; 80:102589. [PMID: 37040671 DOI: 10.1016/j.sbi.2023.102589] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Revised: 02/28/2023] [Accepted: 03/06/2023] [Indexed: 04/13/2023]
Abstract
The membrane-bound O-acyltransferase (MBOAT) superfamily catalyses the transfer of acyl chains to substrates implicated in essential cellular functions. Aberrant function of MBOATs is associated with various diseases and MBOATs are promising drug targets. There has been recent progress in structural characterisation of MBOATs, advancing our understanding of their functional mechanism. Integrating information across the MBOAT family, we characterise a common MBOAT fold and provide a blueprint for substrate and inhibitor engagement. This work provides context for the diverse substrates, mechanisms, and evolutionary relationships of protein and small-molecule MBOATs. Further work should aim to characterise MBOATs, as inherently lipid-associated proteins, within their membrane environment.
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Affiliation(s)
- Claire E Coupland
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - T Bertie Ansell
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK; Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
| | - Mark S P Sansom
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK.
| | - Christian Siebold
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK.
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6
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Pierce MR, Hougland JL. A rising tide lifts all MBOATs: recent progress in structural and functional understanding of membrane bound O-acyltransferases. Front Physiol 2023; 14:1167873. [PMID: 37250116 PMCID: PMC10213974 DOI: 10.3389/fphys.2023.1167873] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Accepted: 04/19/2023] [Indexed: 05/31/2023] Open
Abstract
Acylation modifications play a central role in biological and physiological processes. Across a range of biomolecules from phospholipids to triglycerides to proteins, introduction of a hydrophobic acyl chain can dramatically alter the biological function and cellular localization of these substrates. Amongst the enzymes catalyzing these modifications, the membrane bound O-acyltransferase (MBOAT) family occupies an intriguing position as the combined substrate selectivities of the various family members span all three classes of these biomolecules. MBOAT-dependent substrates are linked to a wide range of health conditions including metabolic disease, cancer, and neurodegenerative disease. Like many integral membrane proteins, these enzymes have presented challenges to investigation due to their intractability to solubilization and purification. However, over the last several years new solubilization approaches coupled with computational modeling, crystallography, and cryoelectron microscopy have brought an explosion of structural information for multiple MBOAT family members. These studies enable comparison of MBOAT structure and function across members catalyzing modifications of all three substrate classes, revealing both conserved features amongst all MBOATs and distinct architectural features that correlate with different acylation substrates ranging from lipids to proteins. We discuss the methods that led to this renaissance of MBOAT structural investigations, our new understanding of MBOAT structure and implications for catalytic function, and the potential impact of these studies for development of new therapeutics targeting MBOAT-dependent physiological processes.
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Affiliation(s)
- Mariah R. Pierce
- Department of Chemistry, Syracuse University, Syracuse, NY, United States
| | - James L. Hougland
- Department of Chemistry, Syracuse University, Syracuse, NY, United States
- Department of Biology, Syracuse University, Syracuse, NY, United States
- BioInspired Syracuse, Syracuse University, Syracuse, NY, United States
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7
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In Search of Small Molecules That Selectively Inhibit MBOAT4. Molecules 2021; 26:molecules26247599. [PMID: 34946685 PMCID: PMC8709388 DOI: 10.3390/molecules26247599] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 12/11/2021] [Accepted: 12/13/2021] [Indexed: 01/31/2023] Open
Abstract
Ghrelin is a 28-residue peptide hormone produced by stomach P/D1 cells located in oxyntic glands of the fundus mucosa. Post-translational octanoylation of its Ser-3 residue, catalyzed by MBOAT4 (aka ghrelin O-acyl transferase (GOAT)), is essential for the binding of the hormone to its receptor in target tissues. Physiological roles of acyl ghrelin include the regulation of food intake, growth hormone secretion from the pituitary, and inhibition of insulin secretion from the pancreas. Here, we describe a medicinal chemistry campaign that led to the identification of small lipopeptidomimetics that inhibit GOAT in vitro. These molecules compete directly for substrate binding. We further describe the synthesis of heterocyclic inhibitors that compete at the acyl coenzyme A binding site.
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8
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Yu J, Liao PJ, Xu W, Jones JR, Everman DB, Flanagan-Steet H, Keller TH, Virshup DM. Structural model of human PORCN illuminates disease-associated variants and drug-binding sites. J Cell Sci 2021; 134:273795. [PMID: 34817055 DOI: 10.1242/jcs.259383] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Accepted: 11/11/2021] [Indexed: 12/20/2022] Open
Abstract
Wnt signaling is essential for normal development and is a therapeutic target in cancer. The enzyme PORCN, or porcupine, is a membrane-bound O-acyltransferase (MBOAT) that is required for the post-translational modification of all Wnts, adding an essential mono-unsaturated palmitoleic acid to a serine on the tip of Wnt hairpin 2. Inherited mutations in PORCN cause focal dermal hypoplasia, and therapeutic inhibition of PORCN slows the growth of Wnt-dependent cancers. Based on homology to mammalian MBOAT proteins, we developed and validated a structural model of human PORCN. The model accommodates palmitoleoyl-CoA and Wnt hairpin 2 in two tunnels in the conserved catalytic core, shedding light on the catalytic mechanism. The model predicts how previously uncharacterized human variants of uncertain significance can alter PORCN function. Drugs including ETC-159, IWP-L6 and LGK-974 dock in the PORCN catalytic site, providing insights into PORCN pharmacologic inhibition. This structural model enhances our mechanistic understanding of PORCN substrate recognition and catalysis, as well as the inhibition of its enzymatic activity, and can facilitate the development of improved inhibitors and the understanding of disease-relevant PORCN mutants. This article has an associated First Person interview with the joint first authors of the paper.
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Affiliation(s)
- Jia Yu
- Programme in Cancer and Stem Cell Biology, Duke-NUS Medical School, 169857, Singapore
| | - Pei-Ju Liao
- Programme in Cancer and Stem Cell Biology, Duke-NUS Medical School, 169857, Singapore
| | - Weijun Xu
- Discovery Chemistry, Experimental Drug Development Centre, 10 Biopolis Road, Chromos, 138670, Singapore
| | - Julie R Jones
- JC Self Research Institute, Greenwood Genetic Center, Greenwood, SC 29646, USA
| | - David B Everman
- JC Self Research Institute, Greenwood Genetic Center, Greenwood, SC 29646, USA
| | | | - Thomas H Keller
- Discovery Chemistry, Experimental Drug Development Centre, 10 Biopolis Road, Chromos, 138670, Singapore
| | - David M Virshup
- Programme in Cancer and Stem Cell Biology, Duke-NUS Medical School, 169857, Singapore.,Department of Pediatrics, Duke University School of Medicine, Durham, NC 27710, USA
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9
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Abstract
Fatty acylation is a widespread form of protein modification that occurs on specific intracellular and secreted proteins. Beyond increasing hydrophobicity and the affinity of the modified protein for lipid bilayers, covalent attachment of a fatty acid exerts effects on protein localization, inter- and intramolecular interactions and signal transduction. As such, research into protein fatty acylation has been embraced by an extensive community of biologists. This special issue highlights advances at the forefront of the field, by focusing on two families of enzymes that catalyse post-translational protein fatty acylation, zDHHC palmitoyl acyltransferases and membrane-bound O-acyl transferases, and signalling pathways regulated by their fatty acylated protein substrates. The collected contributions catalogue the tremendous progress that has been made in enzyme and substrate identification. In addition, articles in this special issue provide insights into the pivotal functions of fatty acylated proteins in immune cell, insulin and EGF receptor-mediated signalling pathways. As selective inhibitors of protein fatty acyltransferases are generated, the future holds great promise for therapeutic targeting of fatty acyltransferases that play key roles in human disease.
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Affiliation(s)
- Marilyn D. Resh
- Cell Biology Program, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, Box 143, New York, NY 10075, USA
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10
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Davis TR, Pierce MR, Novak SX, Hougland JL. Ghrelin octanoylation by ghrelin O-acyltransferase: protein acylation impacting metabolic and neuroendocrine signalling. Open Biol 2021; 11:210080. [PMID: 34315274 PMCID: PMC8316800 DOI: 10.1098/rsob.210080] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The acylated peptide hormone ghrelin impacts a wide range of physiological processes but is most well known for controlling hunger and metabolic regulation. Ghrelin requires a unique posttranslational modification, serine octanoylation, to bind and activate signalling through its cognate GHS-R1a receptor. Ghrelin acylation is catalysed by ghrelin O-acyltransferase (GOAT), a member of the membrane-bound O-acyltransferase (MBOAT) enzyme family. The ghrelin/GOAT/GHS-R1a system is defined by multiple unique aspects within both protein biochemistry and endocrinology. Ghrelin serves as the only substrate for GOAT within the human proteome and, among the multiple hormones involved in energy homeostasis and metabolism such as insulin and leptin, acts as the only known hormone in circulation that directly stimulates appetite and hunger signalling. Advances in GOAT enzymology, structural modelling and inhibitor development have revolutionized our understanding of this enzyme and offered new tools for investigating ghrelin signalling at the molecular and organismal levels. In this review, we briefly summarize the current state of knowledge regarding ghrelin signalling and ghrelin/GOAT enzymology, discuss the GOAT structural model in the context of recently reported MBOAT enzyme superfamily member structures, and highlight the growing complement of GOAT inhibitors that offer options for both ghrelin signalling studies and therapeutic applications.
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Affiliation(s)
- Tasha R Davis
- Department of Chemistry, Syracuse University, Syracuse, NY 13244 USA
| | - Mariah R Pierce
- Department of Chemistry, Syracuse University, Syracuse, NY 13244 USA
| | - Sadie X Novak
- Department of Chemistry, Syracuse University, Syracuse, NY 13244 USA
| | - James L Hougland
- Department of Chemistry, Syracuse University, Syracuse, NY 13244 USA.,BioInspired Syracuse, Syracuse University, Syracuse, NY 13244 USA
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11
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Galli LM, Anderson MO, Gabriel Fraley J, Sanchez L, Bueno R, Hernandez DN, Maddox EU, Lingappa VR, Burrus LW. Determination of the membrane topology of PORCN, an O-acyl transferase that modifies Wnt signalling proteins. Open Biol 2021; 11:200400. [PMID: 34186010 PMCID: PMC8241489 DOI: 10.1098/rsob.200400] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Wnt gradients elicit distinct cellular responses, such as proliferation, specification, differentiation and survival in a dose-dependent manner. Porcupine (PORCN), a membrane-bound O-acyl transferase (MBOAT) that resides in the endoplasmic reticulum, catalyses the addition of monounsaturated palmitate to Wnt proteins and is required for Wnt gradient formation and signalling. In humans, PORCN mutations are causal for focal dermal hypoplasia (FDH), an X-linked dominant syndrome characterized by defects in mesodermal and endodermal tissues. PORCN is also an emerging target for cancer therapeutics. Despite the importance of this enzyme, its structure remains poorly understood. Recently, the crystal structure of DltB, an MBOAT family member from bacteria, was solved. In this report, we use experimental data along with homology modelling to DltB to determine the membrane topology of PORCN. Our studies reveal that PORCN has 11 membrane domains, comprising nine transmembrane spanning domains and two reentrant domains. The N-terminus is oriented towards the lumen while the C-terminus is oriented towards the cytosol. Like DltB, PORCN has a funnel-like structure that is encapsulated by multiple membrane-spanning helices. This new model for PORCN topology allows us to map residues that are important for biological activity (and implicated in FDH) onto its three-dimensional structure.
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Affiliation(s)
- Lisa M Galli
- Department of Biology, San Francisco State University, 1600 Holloway Avenue, San Francisco, CA 94132, USA
| | - Marc O Anderson
- Department of Chemistry and Biochemistry, San Francisco State University, 1600 Holloway Avenue, San Francisco, CA 94132, USA
| | - J Gabriel Fraley
- Department of Biology, San Francisco State University, 1600 Holloway Avenue, San Francisco, CA 94132, USA
| | - Luis Sanchez
- Department of Biology, San Francisco State University, 1600 Holloway Avenue, San Francisco, CA 94132, USA
| | - Raymund Bueno
- Department of Biology, San Francisco State University, 1600 Holloway Avenue, San Francisco, CA 94132, USA
| | - David N Hernandez
- Department of Biology, San Francisco State University, 1600 Holloway Avenue, San Francisco, CA 94132, USA
| | - Eva U Maddox
- Department of Biology, San Francisco State University, 1600 Holloway Avenue, San Francisco, CA 94132, USA
| | | | - Laura W Burrus
- Department of Biology, San Francisco State University, 1600 Holloway Avenue, San Francisco, CA 94132, USA
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12
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Lanyon‐Hogg T, Ritzefeld M, Zhang L, Andrei SA, Pogranyi B, Mondal M, Sefer L, Johnston CD, Coupland CE, Greenfield JL, Newington J, Fuchter MJ, Magee AI, Siebold C, Tate EW. Photochemical Probe Identification of a Small-Molecule Inhibitor Binding Site in Hedgehog Acyltransferase (HHAT). ANGEWANDTE CHEMIE (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2021; 133:13654-13659. [PMID: 38504937 PMCID: PMC10946827 DOI: 10.1002/ange.202014457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 02/26/2021] [Indexed: 03/21/2024]
Abstract
The mammalian membrane-bound O-acyltransferase (MBOAT) superfamily is involved in biological processes including growth, development and appetite sensing. MBOATs are attractive drug targets in cancer and obesity; however, information on the binding site and molecular mechanisms underlying small-molecule inhibition is elusive. This study reports rational development of a photochemical probe to interrogate a novel small-molecule inhibitor binding site in the human MBOAT Hedgehog acyltransferase (HHAT). Structure-activity relationship investigation identified single enantiomer IMP-1575, the most potent HHAT inhibitor reported to-date, and guided design of photocrosslinking probes that maintained HHAT-inhibitory potency. Photocrosslinking and proteomic sequencing of HHAT delivered identification of the first small-molecule binding site in a mammalian MBOAT. Topology and homology data suggested a potential mechanism for HHAT inhibition which was confirmed by kinetic analysis. Our results provide an optimal HHAT tool inhibitor IMP-1575 (K i=38 nM) and a strategy for mapping small molecule interaction sites in MBOATs.
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Affiliation(s)
| | | | - Leran Zhang
- Department of ChemistryImperial College LondonLondonW12 0BZUK
| | | | - Balazs Pogranyi
- Department of ChemistryImperial College LondonLondonW12 0BZUK
| | - Milon Mondal
- Department of ChemistryImperial College LondonLondonW12 0BZUK
| | - Lea Sefer
- Division of Structural BiologyWellcome Centre for Human GeneticsUniversity of OxfordOxfordOX3 7BNUK
| | | | - Claire E. Coupland
- Division of Structural BiologyWellcome Centre for Human GeneticsUniversity of OxfordOxfordOX3 7BNUK
| | | | | | | | - Anthony I. Magee
- National Heart & Lung InstituteImperial College LondonLondonSW7 2AZUK
| | - Christian Siebold
- Division of Structural BiologyWellcome Centre for Human GeneticsUniversity of OxfordOxfordOX3 7BNUK
| | - Edward W. Tate
- Department of ChemistryImperial College LondonLondonW12 0BZUK
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13
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Lanyon‐Hogg T, Ritzefeld M, Zhang L, Andrei SA, Pogranyi B, Mondal M, Sefer L, Johnston CD, Coupland CE, Greenfield JL, Newington J, Fuchter MJ, Magee AI, Siebold C, Tate EW. Photochemical Probe Identification of a Small-Molecule Inhibitor Binding Site in Hedgehog Acyltransferase (HHAT)*. Angew Chem Int Ed Engl 2021; 60:13542-13547. [PMID: 33768725 PMCID: PMC8252026 DOI: 10.1002/anie.202014457] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 02/26/2021] [Indexed: 11/30/2022]
Abstract
The mammalian membrane-bound O-acyltransferase (MBOAT) superfamily is involved in biological processes including growth, development and appetite sensing. MBOATs are attractive drug targets in cancer and obesity; however, information on the binding site and molecular mechanisms underlying small-molecule inhibition is elusive. This study reports rational development of a photochemical probe to interrogate a novel small-molecule inhibitor binding site in the human MBOAT Hedgehog acyltransferase (HHAT). Structure-activity relationship investigation identified single enantiomer IMP-1575, the most potent HHAT inhibitor reported to-date, and guided design of photocrosslinking probes that maintained HHAT-inhibitory potency. Photocrosslinking and proteomic sequencing of HHAT delivered identification of the first small-molecule binding site in a mammalian MBOAT. Topology and homology data suggested a potential mechanism for HHAT inhibition which was confirmed by kinetic analysis. Our results provide an optimal HHAT tool inhibitor IMP-1575 (Ki =38 nM) and a strategy for mapping small molecule interaction sites in MBOATs.
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Affiliation(s)
| | | | - Leran Zhang
- Department of ChemistryImperial College LondonLondonW12 0BZUK
| | | | - Balazs Pogranyi
- Department of ChemistryImperial College LondonLondonW12 0BZUK
| | - Milon Mondal
- Department of ChemistryImperial College LondonLondonW12 0BZUK
| | - Lea Sefer
- Division of Structural BiologyWellcome Centre for Human GeneticsUniversity of OxfordOxfordOX3 7BNUK
| | | | - Claire E. Coupland
- Division of Structural BiologyWellcome Centre for Human GeneticsUniversity of OxfordOxfordOX3 7BNUK
| | | | | | | | - Anthony I. Magee
- National Heart & Lung InstituteImperial College LondonLondonSW7 2AZUK
| | - Christian Siebold
- Division of Structural BiologyWellcome Centre for Human GeneticsUniversity of OxfordOxfordOX3 7BNUK
| | - Edward W. Tate
- Department of ChemistryImperial College LondonLondonW12 0BZUK
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14
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Resh MD. Palmitoylation of Hedgehog proteins by Hedgehog acyltransferase: roles in signalling and disease. Open Biol 2021; 11:200414. [PMID: 33653085 PMCID: PMC8061759 DOI: 10.1098/rsob.200414] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Hedgehog acyltransferase (Hhat), a member of the membrane-bound O-acyltransferase (MBOAT) family, catalyses the covalent attachment of palmitate to the N-terminus of Hedgehog proteins. Palmitoylation is a post-translational modification essential for Hedgehog signalling. This review explores the mechanisms involved in Hhat acyltransferase enzymatic activity, similarities and differences between Hhat and other MBOAT enzymes, and the role of palmitoylation in Hedgehog signalling. In vitro and cell-based assays for Hhat activity have been developed, and residues within Hhat and Hedgehog essential for palmitoylation have been identified. In cells, Hhat promotes the transfer of palmitoyl-CoA from the cytoplasmic to the luminal side of the endoplasmic reticulum membrane, where Shh palmitoylation occurs. Palmitoylation is required for efficient delivery of secreted Hedgehog to its receptor Patched1, as well as for the deactivation of Patched1, which initiates the downstream Hedgehog signalling pathway. While Hhat loss is lethal during embryogenesis, mutations in Hhat have been linked to disease states or abnormalities in mice and humans. In adults, aberrant re-expression of Hedgehog ligands promotes tumorigenesis in an Hhat-dependent manner in a variety of different cancers, including pancreatic, breast and lung. Targeting hedgehog palmitoylation by inhibition of Hhat is thus a promising, potential intervention in human disease.
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Affiliation(s)
- Marilyn D Resh
- Cell Biology Program, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, Box 143, New York, NY 10065, USA
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15
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Iyer MR, Wood CM, Kunos G. Recent progress in the discovery of ghrelin O-acyltransferase (GOAT) inhibitors. RSC Med Chem 2020; 11:1136-1144. [PMID: 33479618 PMCID: PMC7651998 DOI: 10.1039/d0md00210k] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Accepted: 08/03/2020] [Indexed: 12/29/2022] Open
Abstract
Ghrelin is a stomach-derived peptide hormone which stimulates appetite. For ghrelin to exert its orexigenic effect, octanoylation on the serine-3 residue of this gut-brain peptide is essential. The octanoylation of ghrelin is mediated by a unique acyltransferase enzyme known as ghrelin O-acyltransferase (GOAT). Thus modulating this enzyme offers viable approaches to alter feeding behaviors. Over the past decade, several small-molecule based approaches have appeared dealing with the discovery of compounds able to modulate this enzyme for the treatment of obesity and type 2 diabetes. Drug discovery efforts from academic groups and several pharmaceutical companies have fielded compounds having efficacy in altering acylated ghrelin levels in animal models but to date, compounds modulating the activity of the GOAT enzyme do not yet represent clinical options. This mini-review covers the drug discovery approaches of the last decade since the discovery of the GOAT enzyme.
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Affiliation(s)
- Malliga R Iyer
- Medicinal Chemistry Core and Laboratory of Physiologic Studies , National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health (NIAAA/NIH) , 5625 Fishers Lane , Rockville , MD 20852 , USA . ; Tel: +301 443 2807
| | - Casey M Wood
- Medicinal Chemistry Core and Laboratory of Physiologic Studies , National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health (NIAAA/NIH) , 5625 Fishers Lane , Rockville , MD 20852 , USA . ; Tel: +301 443 2807
| | - George Kunos
- Medicinal Chemistry Core and Laboratory of Physiologic Studies , National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health (NIAAA/NIH) , 5625 Fishers Lane , Rockville , MD 20852 , USA . ; Tel: +301 443 2807
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16
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Moose JE, Leets KA, Mate NA, Chisholm JD, Hougland JL. An overview of ghrelin O-acyltransferase inhibitors: a literature and patent review for 2010-2019. Expert Opin Ther Pat 2020; 30:581-593. [PMID: 32564644 DOI: 10.1080/13543776.2020.1776263] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
INTRODUCTION The peptide hormone ghrelin regulates physiological processes associated with energy homeostasis such as appetite, insulin signaling, glucose metabolism, and adiposity. Ghrelin has also been implicated in a growing number of neurological pathways involved in stress response and addiction behavior. For ghrelin to bind the growth hormone secretagogue receptor 1a (GHS-R1a) and activate signaling, the hormone must first be octanoylated on a specific serine side chain. This key transformation is performed by the enzyme ghrelin O-acyltransferase (GOAT), and therefore GOAT inhibitors may be useful in treating disorders related to ghrelin signaling such as diabetes, obesity, and related metabolic syndromes. AREAS COVERED This report covers ghrelin and GOAT as potential therapeutic targets and summarizes work on GOAT inhibitors through the end of 2019, highlighting recent successes with both peptidomimetics and small molecule GOAT inhibitors as potent modulators of GOAT-catalyzed ghrelin octanoylation. EXPERT OPINION A growing body of biochemical and structural knowledge regarding the ghrelin/GOAT system now enables multiple avenues for identifying and optimizing GOAT inhibitors. We are at the beginning of a new era with increased opportunities for leveraging ghrelin and GOAT in the understanding and treatment of multiple health conditions including diabetes, obesity, and addiction.
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Affiliation(s)
- Jacob E Moose
- Department of Chemistry and BioInspired Syracuse, Syracuse University , Syracuse, NY, USA
| | - Katelyn A Leets
- Department of Chemistry and BioInspired Syracuse, Syracuse University , Syracuse, NY, USA
| | - Nilamber A Mate
- Department of Chemistry and BioInspired Syracuse, Syracuse University , Syracuse, NY, USA
| | - John D Chisholm
- Department of Chemistry and BioInspired Syracuse, Syracuse University , Syracuse, NY, USA
| | - James L Hougland
- Department of Chemistry and BioInspired Syracuse, Syracuse University , Syracuse, NY, USA
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17
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Sui X, Wang K, Gluchowski NL, Elliott SD, Liao M, Walther TC, Farese RV. Structure and catalytic mechanism of a human triacylglycerol-synthesis enzyme. Nature 2020; 581:323-328. [PMID: 32433611 PMCID: PMC7398557 DOI: 10.1038/s41586-020-2289-6] [Citation(s) in RCA: 63] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Accepted: 03/17/2020] [Indexed: 12/12/2022]
Abstract
Triglycerides (triacylglycerols, TGs) store metabolic energy in organisms and have industrial uses for foods and fuels. Excessive accumulation of TGs in humans causes obesity and is associated with metabolic diseases1. TG synthesis is catalyzed by acyl-CoA:diacylglycerol acyltransferase (DGAT) enzymes2–4 whose structures and catalytic mechanisms are unknown. Here we determined the structure of dimeric human DGAT1, a member of the membrane-bound O-acyltransferase (MBOAT) family, by cryo-electron microscopy at 3.0-Å resolution. DGAT1 forms a homodimer through N-terminal segments and a hydrophobic interface, with putative active sites within the membrane region. A structure obtained with oleoyl-CoA substrate resolved at 3.2-Å shows that the CoA moiety binds DGAT1 on the cytosolic side and the acyl group lies deep within a hydrophobic channel, positioning the acyl-CoA thioester bond near an invariant catalytic histidine residue. The reaction center is located inside a large cavity, which opens laterally to the membrane bilayer, providing lipid access to the active site. A lipid-like density, possibly an acyl-acceptor molecule, is located within the reaction center, orthogonal to acyl-CoA. Insights provided by the DGAT1 structures, together with mutagenesis and functional studies, give rise to a model of catalysis for DGAT’s generation of TGs.
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Affiliation(s)
- Xuewu Sui
- Department of Molecular Metabolism, Harvard T. H. Chan School of Public Health, Boston, MA, USA.,Department of Cell Biology, Harvard Medical School, Boston, MA, USA
| | - Kun Wang
- Department of Molecular Metabolism, Harvard T. H. Chan School of Public Health, Boston, MA, USA.,Department of Cell Biology, Harvard Medical School, Boston, MA, USA
| | - Nina L Gluchowski
- Department of Molecular Metabolism, Harvard T. H. Chan School of Public Health, Boston, MA, USA.,Department of Cell Biology, Harvard Medical School, Boston, MA, USA.,Department of Gastroenterology, Hepatology, and Nutrition, Boston Children's Hospital, Boston, MA, USA
| | - Shane D Elliott
- Department of Molecular Metabolism, Harvard T. H. Chan School of Public Health, Boston, MA, USA.,Department of Cell Biology, Harvard Medical School, Boston, MA, USA
| | - Maofu Liao
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA.
| | - Tobias C Walther
- Department of Molecular Metabolism, Harvard T. H. Chan School of Public Health, Boston, MA, USA. .,Department of Cell Biology, Harvard Medical School, Boston, MA, USA. .,Broad Institute of MIT and Harvard, Cambridge, MA, USA. .,Howard Hughes Medical Institute, Boston, MA, USA.
| | - Robert V Farese
- Department of Molecular Metabolism, Harvard T. H. Chan School of Public Health, Boston, MA, USA. .,Department of Cell Biology, Harvard Medical School, Boston, MA, USA. .,Broad Institute of MIT and Harvard, Cambridge, MA, USA.
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18
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Abizaid A, Hougland JL. Ghrelin Signaling: GOAT and GHS-R1a Take a LEAP in Complexity. Trends Endocrinol Metab 2020; 31:107-117. [PMID: 31636018 PMCID: PMC7299083 DOI: 10.1016/j.tem.2019.09.006] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Revised: 09/25/2019] [Accepted: 09/27/2019] [Indexed: 12/30/2022]
Abstract
Ghrelin and the growth hormone secretagogue receptor 1a (GHS-R1a) are important targets for disorders related to energy balance and metabolic regulation. Pharmacological control of ghrelin signaling is a promising avenue to address health issues involving appetite, weight gain, obesity, and related metabolic disorders, and may be an option for patients suffering from wasting conditions like cachexia. In this review, we summarize recent developments in the biochemistry of ghrelin and GHS-R1a signaling. These include unravelling the enzymatic transformations that generate active ghrelin and the discovery of multiple proteins that interact with ghrelin and GHS-R1a to regulate signaling. Furthermore, we propose that harnessing these processes will lead to highly selective treatments to address obesity, diabetes, and other metabolism-linked disorders.
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Affiliation(s)
- Alfonso Abizaid
- Department of Neuroscience, Carleton University, Ottawa, ON, Canada
| | - James L Hougland
- Department of Chemistry, Syracuse University, Syracuse, NY, USA.
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19
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Soleyman-Jahi S, Sadeghi F, Pastaki Khoshbin A, Khani L, Roosta V, Zendehdel K. Attribution of Ghrelin to Cancer; Attempts to Unravel an Apparent Controversy. Front Oncol 2019; 9:1014. [PMID: 31681567 PMCID: PMC6805778 DOI: 10.3389/fonc.2019.01014] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Accepted: 09/20/2019] [Indexed: 12/21/2022] Open
Abstract
Ghrelin is an endogenous peptide hormone mainly produced in the stomach. It has been known to regulate energy homeostasis, stimulate secretion of growth hormone, and mediate many other physiologic effects. Various effects attributed to ghrelin contribute to many aspects of cancer development and progression. Accordingly, a large body of evidence has emerged about the association of ghrelin with several types of cancer in scales of cell-line, animal, and human studies. However, existing data are controversial. This controversy occurs in two main domains: one is the controversial results in local effects of ghrelin on different types of human cancer cell-lines; the second is the apparent disagreement in the results of in-vitro and clinical studies that investigated ghrelin association to one type of cancer. These inconsistencies have hampered the indications to consider ghrelin as a potential tumor biomarker or therapeutic agent in cancer patients. Previous studies have reviewed different parts of current literature about the ghrelin-cancer relationship. Although they have highlighted these controversial results in various ways, no specific recommendations have been given to address it. In this study, we comprehensively reviewed in-vitro, in-vivo, and clinical studies and attempted to use the following approaches to unravel the inconsistencies detected: (a) to distinguish local and systemic effects of ghrelin in interpreting its summary clinical role in each cancer; (b) scrutinizing factors that regulate local effects of ghrelin and could justify different effects of ghrelin on different cancer cell-lines. These approaches could have notable implications for future in-vitro and clinical studies.
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Affiliation(s)
- Saeed Soleyman-Jahi
- Division of Gastroenterology, School of Medicine, Washington University in St. Louis, St. Louis, MO, United States.,Cancer Immunology Project, Universal Scientific Education and Research Network, St. Louis, MO, United States.,Cancer Research Center, Cancer Institute of Iran, Tehran University of Medical Sciences, Tehran, Iran
| | - Fatemeh Sadeghi
- Cancer Research Center, Cancer Institute of Iran, Tehran University of Medical Sciences, Tehran, Iran.,Cancer Immunology Project, Universal Scientific Education and Research Network, Tehran, Iran.,Department of Immunology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - Amin Pastaki Khoshbin
- Cancer Immunology Project, Universal Scientific Education and Research Network, Tehran, Iran.,School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Leila Khani
- Department of Immunology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - Venus Roosta
- School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Kazem Zendehdel
- Cancer Research Center, Cancer Institute of Iran, Tehran University of Medical Sciences, Tehran, Iran
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20
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Rajagopal N, Nangia S. Obtaining Protein Association Energy Landscape for Integral Membrane Proteins. J Chem Theory Comput 2019; 15:6444-6455. [DOI: 10.1021/acs.jctc.9b00626] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Nandhini Rajagopal
- Department of Biomedical and Chemical Engineering, Syracuse University, 343 Link Hall, Syracuse, New York 13244, United States
| | - Shikha Nangia
- Department of Biomedical and Chemical Engineering, Syracuse University, 343 Link Hall, Syracuse, New York 13244, United States
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