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Chrestia JF, Turani O, Araujo NR, Hernando G, Esandi MDC, Bouzat C. Regulation of nicotinic acetylcholine receptors by post-translational modifications. Pharmacol Res 2023; 190:106712. [PMID: 36863428 DOI: 10.1016/j.phrs.2023.106712] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Revised: 02/21/2023] [Accepted: 02/24/2023] [Indexed: 03/04/2023]
Abstract
Nicotinic acetylcholine receptors (nAChRs) comprise a family of pentameric ligand-gated ion channels widely distributed in the central and peripheric nervous system and in non-neuronal cells. nAChRs are involved in chemical synapses and are key actors in vital physiological processes throughout the animal kingdom. They mediate skeletal muscle contraction, autonomic responses, contribute to cognitive processes, and regulate behaviors. Dysregulation of nAChRs is associated with neurological, neurodegenerative, inflammatory and motor disorders. In spite of the great advances in the elucidation of nAChR structure and function, our knowledge about the impact of post-translational modifications (PTMs) on nAChR functional activity and cholinergic signaling has lagged behind. PTMs occur at different steps of protein life cycle, modulating in time and space protein folding, localization, function, and protein-protein interactions, and allow fine-tuned responses to changes in the environment. A large body of evidence demonstrates that PTMs regulate all levels of nAChR life cycle, with key roles in receptor expression, membrane stability and function. However, our knowledge is still limited, restricted to a few PTMs, and many important aspects remain largely unknown. There is thus a long way to go to decipher the association of aberrant PTMs with disorders of cholinergic signaling and to target PTM regulation for novel therapeutic interventions. In this review we provide a comprehensive overview of what is known about how different PTMs regulate nAChR.
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Affiliation(s)
- Juan Facundo Chrestia
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca 8000, Argentina
| | - Ornella Turani
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca 8000, Argentina
| | - Noelia Rodriguez Araujo
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca 8000, Argentina
| | - Guillermina Hernando
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca 8000, Argentina
| | - María Del Carmen Esandi
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca 8000, Argentina
| | - Cecilia Bouzat
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca 8000, Argentina.
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2
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Tillman TS, Choi Z, Xu Y, Tang P. Functional Tolerance to Cysteine Mutations in Human α7 Nicotinic Acetylcholine Receptors. ACS Chem Neurosci 2020; 11:242-247. [PMID: 31951367 DOI: 10.1021/acschemneuro.9b00647] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
The α7 nicotinic acetylcholine receptor (α7 nAChR) is involved in various intracellular signaling pathways that mediate addiction, chronic pain, and other diseases, but its intracellular domain structures remain undetermined. The presence of 17 native cysteines in α7 nAChR provides opportunities for extracting structural information through site-directed labeling of chemical probes in strategic locations, but it also creates uncertainties in channel function when those native cysteines must be mutated. Using site-directed mutagenesis and two-electrode voltage clamp electrophysiology measurements, we found that α7 nAChR's function was well tolerated for mutations of all 13 cysteines as long as two pairs of disulfide-bond cysteines remained in the extracellular domain. Furthermore, surface plasmon resonance measurements showed that the cysteine mutations did not affect α7 nAChR binding to the intracellular protein PICK1. The study suggests that a high native cysteine content does not necessarily preclude the use of single cysteine labeling for acquiring structural information on functional proteins.
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Affiliation(s)
- Tommy S. Tillman
- Department of Anesthesiology and Perioperative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Zachary Choi
- Department of Anesthesiology and Perioperative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Yan Xu
- Department of Anesthesiology and Perioperative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
- Department of Structural Biology, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Pei Tang
- Department of Anesthesiology and Perioperative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
- Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
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3
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Matt L, Kim K, Chowdhury D, Hell JW. Role of Palmitoylation of Postsynaptic Proteins in Promoting Synaptic Plasticity. Front Mol Neurosci 2019; 12:8. [PMID: 30766476 PMCID: PMC6365469 DOI: 10.3389/fnmol.2019.00008] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Accepted: 01/10/2019] [Indexed: 12/19/2022] Open
Abstract
Many postsynaptic proteins undergo palmitoylation, the reversible attachment of the fatty acid palmitate to cysteine residues, which influences trafficking, localization, and protein interaction dynamics. Both palmitoylation by palmitoyl acyl transferases (PAT) and depalmitoylation by palmitoyl-protein thioesterases (PPT) is regulated in an activity-dependent, localized fashion. Recently, palmitoylation has received attention for its pivotal contribution to various forms of synaptic plasticity, the dynamic modulation of synaptic strength in response to neuronal activity. For instance, palmitoylation and depalmitoylation of the central postsynaptic scaffold protein postsynaptic density-95 (PSD-95) is important for synaptic plasticity. Here, we provide a comprehensive review of studies linking palmitoylation of postsynaptic proteins to synaptic plasticity.
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Affiliation(s)
- Lucas Matt
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
| | - Karam Kim
- Department of Pharmacology, University of California, Davis, Davis, CA, United States
| | - Dhrubajyoti Chowdhury
- Department of Pharmacology, University of California, Davis, Davis, CA, United States
| | - Johannes W Hell
- Department of Pharmacology, University of California, Davis, Davis, CA, United States
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Adachi N, Hess DT, Kaku M, Ueda C, Numa C, Saito N. Differential S-palmitoylation of the human and rodent β 3-adrenergic receptors. J Biol Chem 2018; 294:2569-2578. [PMID: 30541923 DOI: 10.1074/jbc.ra118.004978] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Revised: 12/07/2018] [Indexed: 12/20/2022] Open
Abstract
With few reported exceptions, G protein-coupled receptors (GPCRs) are modified by Cys palmitoylation (S-palmitoylation). In multiple GPCRs, S-palmitoylation targets a canonical site within the C-terminal cytoplasmic tail adjacent to the C terminus of the seventh transmembrane domain, but modification of additional sites is exemplified by the β-adrenergic receptors (βARs). The β1AR is S-palmitoylated at a second, more distal site within the C-terminal tail, and the β2AR is modified at a second site within the third intracellular loop, neither of which is conserved in other βAR isoforms. The functional roles of S-palmitoylation of disparate sites are incompletely characterized for any GPCR family. Here, we describe S-palmitoylation of the β3AR. We compared mouse and human β3ARs and found that both were S-palmitoylated at the canonical site within the C-terminal tail, Cys-358 and Cys-361/363 in mouse and human β3ARs, respectively. Surprisingly, the human β3AR was S-palmitoylated at two additional sites, Cys-153 and Cys-292 within the second and third intracellular loops, respectively. Cys-153 is apparently unique to the human β3AR, and Cys-292 is conserved primarily in primates. Mutational substitution of C-tail Cys in human but not mouse β3ARs resulted in diminished ligand-induced cAMP production. Substitution of Cys-153, Cys-292, or Cys-361/363 within the human β3AR diminished membrane-receptor abundance, but only Cys-361/363 substitution diminished membrane-receptor half-life. Thus, S-palmitoylation of different sites differentially regulates the human β3AR, and differential S-palmitoylation distinguishes human and rodent β3ARs, potentially contributing to species-specific differences in the clinical efficacy of β3AR-directed pharmacological approaches to disease.
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Affiliation(s)
- Naoko Adachi
- From the Biosignal Research Center, Kobe University, Kobe 657-8501, Japan and
| | - Douglas T Hess
- Institute for Transformative Molecular Medicine and Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106
| | - Mika Kaku
- From the Biosignal Research Center, Kobe University, Kobe 657-8501, Japan and
| | - Chie Ueda
- From the Biosignal Research Center, Kobe University, Kobe 657-8501, Japan and
| | - Chisato Numa
- From the Biosignal Research Center, Kobe University, Kobe 657-8501, Japan and
| | - Naoaki Saito
- From the Biosignal Research Center, Kobe University, Kobe 657-8501, Japan and
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5
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Palmitoylation as a Functional Regulator of Neurotransmitter Receptors. Neural Plast 2018; 2018:5701348. [PMID: 29849559 PMCID: PMC5903346 DOI: 10.1155/2018/5701348] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Accepted: 01/29/2018] [Indexed: 12/11/2022] Open
Abstract
The majority of neuronal proteins involved in cellular signaling undergo different posttranslational modifications significantly affecting their functions. One of these modifications is a covalent attachment of a 16-C palmitic acid to one or more cysteine residues (S-palmitoylation) within the target protein. Palmitoylation is a reversible modification, and repeated cycles of palmitoylation/depalmitoylation might be critically involved in the regulation of multiple signaling processes. Palmitoylation also represents a common posttranslational modification of the neurotransmitter receptors, including G protein-coupled receptors (GPCRs) and ligand-gated ion channels (LICs). From the functional point of view, palmitoylation affects a wide span of neurotransmitter receptors activities including their trafficking, sorting, stability, residence lifetime at the cell surface, endocytosis, recycling, and synaptic clustering. This review summarizes the current knowledge on the palmitoylation of neurotransmitter receptors and its role in the regulation of receptors functions as well as in the control of different kinds of physiological and pathological behavior.
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6
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Grunt TW. Interacting Cancer Machineries: Cell Signaling, Lipid Metabolism, and Epigenetics. Trends Endocrinol Metab 2018; 29:86-98. [PMID: 29203141 DOI: 10.1016/j.tem.2017.11.003] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Revised: 11/13/2017] [Accepted: 11/14/2017] [Indexed: 12/21/2022]
Abstract
Cancer-specific perturbations of signaling, metabolism, and epigenetics can be a cause and/or consequence of malignant transformation. Evidence indicates that these regulatory systems interact with each other to form highly flexible and robust cybernetic networks that promote malignant growth and confer treatment resistance. Deciphering these plexuses using holistic approaches known from systems biology can be instructive for the future design of novel anticancer strategies. In this review, I discuss novel findings elucidating the multiple molecular interdependence among cancer-specific signaling, cell metabolism, and epigenetics to provide an insightful understanding of how major cancer machineries interact with each other during cancer development and progression, and how this knowledge may be used for future co-targeting strategies.
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Affiliation(s)
- Thomas W Grunt
- Signaling Networks Program, Division of Oncology, Department of Medicine I, Medical University of Vienna, Vienna, Austria; Comprehensive Cancer Center, Medical University of Vienna, Vienna, Austria; Ludwig Boltzmann Cluster Oncology, Medical University of Vienna, Vienna, Austria.
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7
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Jiang H, Zhang X, Chen X, Aramsangtienchai P, Tong Z, Lin H. Protein Lipidation: Occurrence, Mechanisms, Biological Functions, and Enabling Technologies. Chem Rev 2018; 118:919-988. [PMID: 29292991 DOI: 10.1021/acs.chemrev.6b00750] [Citation(s) in RCA: 263] [Impact Index Per Article: 43.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Protein lipidation, including cysteine prenylation, N-terminal glycine myristoylation, cysteine palmitoylation, and serine and lysine fatty acylation, occurs in many proteins in eukaryotic cells and regulates numerous biological pathways, such as membrane trafficking, protein secretion, signal transduction, and apoptosis. We provide a comprehensive review of protein lipidation, including descriptions of proteins known to be modified and the functions of the modifications, the enzymes that control them, and the tools and technologies developed to study them. We also highlight key questions about protein lipidation that remain to be answered, the challenges associated with answering such questions, and possible solutions to overcome these challenges.
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Affiliation(s)
- Hong Jiang
- Howard Hughes Medical Institute, Department of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14853, United States
| | - Xiaoyu Zhang
- Howard Hughes Medical Institute, Department of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14853, United States
| | - Xiao Chen
- Howard Hughes Medical Institute, Department of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14853, United States
| | - Pornpun Aramsangtienchai
- Howard Hughes Medical Institute, Department of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14853, United States
| | - Zhen Tong
- Howard Hughes Medical Institute, Department of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14853, United States
| | - Hening Lin
- Howard Hughes Medical Institute, Department of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14853, United States
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8
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Fox-Loe AM, Moonschi FH, Richards CI. Organelle-specific single-molecule imaging of α4β2 nicotinic receptors reveals the effect of nicotine on receptor assembly and cell-surface trafficking. J Biol Chem 2017; 292:21159-21169. [PMID: 29074617 DOI: 10.1074/jbc.m117.801431] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Revised: 10/20/2017] [Indexed: 11/06/2022] Open
Abstract
Nicotinic acetylcholine receptors (nAChRs) assemble in the endoplasmic reticulum (ER) and traffic to the cell surface as pentamers composed of α and β subunits. Many nAChR subtypes can assemble with varying subunit ratios, giving rise to multiple stoichiometries exhibiting different subcellular localization and functional properties. In addition to the endogenous neurotransmitter acetylcholine, nicotine also binds and activates nAChRs and influences their trafficking and expression on the cell surface. Currently, no available technique can specifically elucidate the stoichiometry of nAChRs in the ER versus those in the plasma membrane. Here, we report a method involving single-molecule fluorescence measurements to determine the structural properties of these membrane proteins after isolation in nanoscale vesicles derived from specific organelles. These cell-derived nanovesicles allowed us to separate single membrane receptors while maintaining them in their physiological environment. Sorting the vesicles according to the organelle of origin enabled us to determine localized differences in receptor structural properties, structural influence on transport between organelles, and changes in receptor assembly within intracellular organelles. These organelle-specific nanovesicles revealed that one structural isoform of the α4β2 nAChR was preferentially trafficked to the cell surface. Moreover, nicotine altered nAChR assembly in the ER, resulting in increased production of the receptor isoform that traffics more efficiently to the cell surface. We conclude that the combined effects of the increased assembly of one nAChR stoichiometry and its preferential trafficking likely drive the up-regulation of nAChRs on the cell surface upon nicotine exposure.
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Affiliation(s)
- Ashley M Fox-Loe
- From the Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506
| | - Faruk H Moonschi
- From the Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506
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9
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Baenziger JE, Domville JA, Therien JD. The Role of Cholesterol in the Activation of Nicotinic Acetylcholine Receptors. CURRENT TOPICS IN MEMBRANES 2017; 80:95-137. [DOI: 10.1016/bs.ctm.2017.05.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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10
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Borroni MV, Vallés AS, Barrantes FJ. The lipid habitats of neurotransmitter receptors in brain. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:2662-2670. [PMID: 27424801 DOI: 10.1016/j.bbamem.2016.07.005] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Revised: 06/05/2016] [Accepted: 07/12/2016] [Indexed: 12/17/2022]
Abstract
Neurotransmitter receptors, the macromolecules specialized in decoding the chemical signals encrypted in the chemical signaling mechanism in the nervous system, occur either at the somatic cell surface of chemically excitable cells or at specialized subcellular structures, the synapses. Synapses have lipid compositions distinct from the rest of the cell membrane, suggesting that neurotransmitter receptors and their scaffolding and adaptor protein partners require specific lipid habitats for optimal operation. In this review we discuss some paradigmatic cases of neurotransmitter receptor-lipid interactions, highlighting the chemical nature of the intervening lipid species and providing examples of the receptor mechanisms affected by interaction with lipids. The focus is on the effects of cholesterol, glycerophospholipids and covalent fatty acid acylation on neurotransmitter receptors. We also briefly discuss the role of lipid phase states involving lateral heterogeneities of the host membrane known to modulate membrane transport, protein sorting and signaling. Modulation of neurotransmitter receptors by lipids occurs at multiple levels, affecting a wide span of activities including their trafficking, sorting, stability, residence lifetime at the cell surface, endocytosis, and recycling, among other important functional properties at the synapse.
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Affiliation(s)
- María Virginia Borroni
- Instituto de Tecnología en Polímeros y Nanotecnología (ITPN) Av. Las Heras 2214 C1127AAQ Buenos Aires Argentina
| | - Ana Sofía Vallés
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, B8000FWB Bahía Blanca, Argentina
| | - Francisco J Barrantes
- Laboratory of Molecular Neurobiology, Biomedical Research Institute, UCA-CONICET, Faculty of Medical Sciences, Catholic University of Argentina, Av. Alicia Moreau de Justo 1600, C1107AFF Buenos Aires, Argentina.
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Sandlers Y, Mercier K, Pathmasiri W, Carlson J, McRitchie S, Sumner S, Vernon HJ. Metabolomics Reveals New Mechanisms for Pathogenesis in Barth Syndrome and Introduces Novel Roles for Cardiolipin in Cellular Function. PLoS One 2016; 11:e0151802. [PMID: 27015085 PMCID: PMC4807847 DOI: 10.1371/journal.pone.0151802] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Accepted: 03/04/2016] [Indexed: 02/07/2023] Open
Abstract
Barth Syndrome is the only known Mendelian disorder of cardiolipin remodeling, with characteristic clinical features of cardiomyopathy, skeletal myopathy, and neutropenia. While the primary biochemical defects of reduced mature cardiolipin and increased monolysocardiolipin are well-described, much of the downstream biochemical dysregulation has not been uncovered, and biomarkers are limited. In order to further expand upon the knowledge of the biochemical abnormalities in Barth Syndrome, we analyzed metabolite profiles in plasma from a cohort of individuals with Barth Syndrome compared to age-matched controls via 1H nuclear magnetic resonance spectroscopy and liquid chromatography-mass spectrometry. A clear distinction between metabolite profiles of individuals with Barth Syndrome and controls was observed, and was defined by an array of metabolite classes including amino acids and lipids. Pathway analysis of these discriminating metabolites revealed involvement of mitochondrial and extra-mitochondrial biochemical pathways including: insulin regulation of fatty acid metabolism, lipid metabolism, biogenic amine metabolism, amino acid metabolism, endothelial nitric oxide synthase signaling, and tRNA biosynthesis. Taken together, this data indicates broad metabolic dysregulation in Barth Syndrome with wide cellular effects.
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Affiliation(s)
- Yana Sandlers
- Department of Chemistry, Cleveland State University, Cleveland, OH, United States of America
| | - Kelly Mercier
- Research Triangle International, Durham, NC, United States of America
| | - Wimal Pathmasiri
- Research Triangle International, Durham, NC, United States of America
| | - Jim Carlson
- Research Triangle International, Durham, NC, United States of America
| | - Susan McRitchie
- Research Triangle International, Durham, NC, United States of America
| | - Susan Sumner
- Research Triangle International, Durham, NC, United States of America
| | - Hilary J. Vernon
- Department of Neurogenetics, Kennedy Krieger Institute, Baltimore, MD, United States of America
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University, Baltimore, MD, United States of America
- * E-mail:
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12
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Khanal N, Pejaver V, Li Z, Radivojac P, Clemmer DE, Mukhopadhyay S. Position of Proline Mediates the Reactivity of S-Palmitoylation. ACS Chem Biol 2015; 10:2529-36. [PMID: 26255674 DOI: 10.1021/acschembio.5b00429] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Palmitoylation, a post-translational modification in which a saturated 16-carbon chain is added predominantly to a cysteine residue, participates in various biological functions. The position of proline relative to other residues being post-translationally modified has been previously reported as being important. We determined that proline is statistically enriched around cysteines known to be S-palmitoylated. The goal of this work was to determine how the position of proline influences the palmitoylation of the cysteine residue. We established a mass spectrometry-based approach to investigate time- and temperature-dependent kinetics of autopalmitoylation in vitro and to derive the thermodynamic parameters of the transition state associated with palmitoylation; to the best of our knowledge, our work is the first to study the kinetics and activation properties of the palmitoylation process. We then used these thermochemical parameters to determine if the position of proline relative to the modified cysteine is important for palmitoylation. Our results show that peptides with proline at the -1 position of cysteine in their sequence (PC) have lower enthalpic barriers and higher entropic barriers in comparison to the same peptides with proline at the +1 position of cysteine (CP); interestingly, the free-energy barriers for both pairs are almost identical. Molecular dynamics studies demonstrate that the flexibility of the cysteine backbone in the PC-containing peptide when compared to the CP-containing peptide explains the increased entropic barrier and decreased enthalpic barrier observed experimentally.
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Affiliation(s)
- Neelam Khanal
- Departments of †Chemistry, ‡Computer Science and Informatics, and §Biology, Indiana University, Bloomington, Indiana 47405, United States
| | - Vikas Pejaver
- Departments of †Chemistry, ‡Computer Science and Informatics, and §Biology, Indiana University, Bloomington, Indiana 47405, United States
| | - Zhiyu Li
- Departments of †Chemistry, ‡Computer Science and Informatics, and §Biology, Indiana University, Bloomington, Indiana 47405, United States
| | - Predrag Radivojac
- Departments of †Chemistry, ‡Computer Science and Informatics, and §Biology, Indiana University, Bloomington, Indiana 47405, United States
| | - David E. Clemmer
- Departments of †Chemistry, ‡Computer Science and Informatics, and §Biology, Indiana University, Bloomington, Indiana 47405, United States
| | - Suchetana Mukhopadhyay
- Departments of †Chemistry, ‡Computer Science and Informatics, and §Biology, Indiana University, Bloomington, Indiana 47405, United States
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13
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Liu Q, Kuo YP, Shen J, Lukas RJ, Wu J. Roles of nicotinic acetylcholine receptor β subunit cytoplasmic loops in acute desensitization and single-channel features. Neuroscience 2015; 289:315-23. [PMID: 25536046 DOI: 10.1016/j.neuroscience.2014.12.016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2014] [Revised: 12/12/2014] [Accepted: 12/13/2014] [Indexed: 01/11/2023]
Abstract
To evaluate physiological roles of the large, second cytoplasmic loops (C2) situated between the M3 and M4 transmembrane domains of nicotinic acetylcholine receptor (nAChR) subunits. We have constructed chimeric β2 (β2χ) and β4 (β4χ) subunits in which the "nested" C2 domains (but not the "proximal" sequences of ∼14 residues immediately adjacent to the M3 or M4 domains) of these β subunits were replaced by the corresponding sequence from the serotonin 5-HT3A receptor subunit. We previously reported that heterologously expressed nAChR containing α4 and β2χ subunits displayed a faster whole-cell current decay in its agonist response compared to responses of all-wild-type α4β2-nAChR. This suggests an unexpected, functional role for the C2 domain of the β2 subunit in α4β2-nAChR acute desensitization. Here we report that there also is faster desensitization of α4β4χ-nAChR relative to α4β4-nAChR stably and heterologously expressed in the human SH-EP1 cell-line. In addition, cell-attached, single-channel recording shows that both acetylcholine-activated α4β2χ- and α4β4χ-nAChR have a significantly lower mean open probability, shorter mean open-time, and a longer mean closed-time than their fully wild-type counterparts while not having different conductance amplitudes. These findings reveal microscopic bases for the faster desensitization of α4(∗)-nAChR containing chimeric instead of wild-type β subunits. Our findings also remain consistent with novel and unexpected roles of β subunit-nested C2 domains in modulation of α4(∗)-nAChR function.
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Affiliation(s)
- Q Liu
- Division of Neurology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ 85013-4496, United States.
| | - Y-P Kuo
- Division of Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ 85013-4496, United States
| | - J Shen
- Department of Physiology, Shantou University of Medical College, Shantou, Guangdong, China
| | - R J Lukas
- Division of Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ 85013-4496, United States
| | - J Wu
- Division of Neurology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ 85013-4496, United States; Department of Physiology, Shantou University of Medical College, Shantou, Guangdong, China.
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14
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Nicotinic acetylcholine receptor-lipid interactions: Mechanistic insight and biological function. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1848:1806-17. [PMID: 25791350 DOI: 10.1016/j.bbamem.2015.03.010] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Revised: 02/15/2015] [Accepted: 03/09/2015] [Indexed: 01/14/2023]
Abstract
Membrane lipids are potent modulators of the nicotinic acetylcholine receptor (nAChR) from Torpedo. Lipids influence nAChR function by both conformational selection and kinetic mechanisms, stabilizing varying proportions of activatable versus non-activatable conformations, as well as influencing the transitions between these conformational states. Of note, some membranes stabilize an electrically silent uncoupled conformation that binds agonist but does not undergo agonist-induced conformational transitions. The uncoupled nAChR, however, does transition to activatable conformations in relatively thick lipid bilayers, such as those found in lipid rafts. In this review, we discuss current understanding of lipid-nAChR interactions in the context of increasingly available high resolution structural and functional data. These data highlight different sites of lipid action, including the lipid-exposed M4 transmembrane α-helix. Current evidence suggests that lipids alter nAChR function by modulating interactions between M4 and the adjacent transmembrane α-helices, M1 and M3. These interactions have also been implicated in both the folding and trafficking of nAChRs to the cell surface. We review current mechanistic understanding of lipid-nAChR interactions, and highlight potential biological roles for lipid-nAChR interactions in modulating the synaptic response. This article is part of a Special Issue entitled: Lipid-protein interactions.
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The role of the M4 lipid-sensor in the folding, trafficking, and allosteric modulation of nicotinic acetylcholine receptors. Neuropharmacology 2014; 96:157-68. [PMID: 25433148 DOI: 10.1016/j.neuropharm.2014.11.011] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Revised: 10/31/2014] [Accepted: 11/18/2014] [Indexed: 11/24/2022]
Abstract
With the availability of high resolution structural data, increasing attention has focused on the mechanisms by which drugs and endogenous compounds allosterically modulate nicotinic acetylcholine receptor (nAChR) function. Lipids are potent modulators of the nAChR from Torpedo. Membrane lipids influence nAChR function by both conformational selection and kinetic mechanisms, stabilizing varying proportions of pre-existing resting, open, desensitized, and uncoupled conformations, as well as influencing the transitions between these conformational states. Structural and functional data highlight a role for the lipid-exposed M4 transmembrane α-helix of each subunit in lipid sensing, and suggest that lipids influence gating by altering the binding of M4 to the adjacent transmembrane α-helices, M1 and M3. M4 has also been implicated in both the folding and trafficking of nAChRs to the cell surface, as well as in the potentiation of nAChR gating by neurosteroids. Here, we discuss the roles of M4 in the folding, trafficking, and allosteric modulation of nAChRs. We also consider the hypothesis that variable chemistry at the M4-M1/M3 transmembrane α-helical interface in different nAChR subunits governs the capacity for potentiation by activating lipids. This article is part of the Special Issue entitled 'The Nicotinic Acetylcholine Receptor: From Molecular Biology to Cognition'.
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The role of intracellular linkers in gating and desensitization of human pentameric ligand-gated ion channels. J Neurosci 2014; 34:7238-52. [PMID: 24849357 DOI: 10.1523/jneurosci.5105-13.2014] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
It has recently been proposed that post-translational modification of not only the M3-M4 linker but also the M1-M2 linker of pentameric ligand-gated ion channels modulates function in vivo. To estimate the involvement of the M1-M2 linker in gating and desensitization, we engineered a series of mutations to this linker of the human adult-muscle acetylcholine receptor (AChR), the α3β4 AChR and the homomeric α1 glycine receptor (GlyR). All tested M1-M2 linker mutations had little effect on the kinetics of deactivation or desensitization compared with the effects of mutations to the M2 α-helix or the extracellular M2-M3 linker. However, when the effects of mutations were assessed with 50 Hz trains of ∼1 ms pulses of saturating neurotransmitter, some mutations led to much more, and others to much less, peak-current depression than observed for the wild-type channels, suggesting that these mutations could affect the fidelity of fast synaptic transmission. Nevertheless, no mutation to this linker could mimic the irreversible loss of responsiveness reported to result from the oxidation of the M1-M2 linker cysteines of the α3 AChR subunit. We also replaced the M3-M4 linker of the α1 GlyR with much shorter peptides and found that none of these extensive changes affects channel deactivation strongly or reduces the marked variability in desensitization kinetics that characterizes the wild-type channel. However, we found that these large mutations to the M3-M4 linker can have pronounced effects on desensitization kinetics, supporting the notion that its post-translational modification could indeed modulate α1 GlyR behavior.
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Abstract
Protein S-acylation, the reversible covalent fatty-acid modification of cysteine residues, has emerged as a dynamic posttranslational modification (PTM) that controls the diversity, life cycle, and physiological function of numerous ligand- and voltage-gated ion channels. S-acylation is enzymatically mediated by a diverse family of acyltransferases (zDHHCs) and is reversed by acylthioesterases. However, for most ion channels, the dynamics and subcellular localization at which S-acylation and deacylation cycles occur are not known. S-acylation can control the two fundamental determinants of ion channel function: (1) the number of channels resident in a membrane and (2) the activity of the channel at the membrane. It controls the former by regulating channel trafficking and the latter by controlling channel kinetics and modulation by other PTMs. Ion channel function may be modulated by S-acylation of both pore-forming and regulatory subunits as well as through control of adapter, signaling, and scaffolding proteins in ion channel complexes. Importantly, cross-talk of S-acylation with other PTMs of both cysteine residues by themselves and neighboring sites of phosphorylation is an emerging concept in the control of ion channel physiology. In this review, I discuss the fundamentals of protein S-acylation and the tools available to investigate ion channel S-acylation. The mechanisms and role of S-acylation in controlling diverse stages of the ion channel life cycle and its effect on ion channel function are highlighted. Finally, I discuss future goals and challenges for the field to understand both the mechanistic basis for S-acylation control of ion channels and the functional consequence and implications for understanding the physiological function of ion channel S-acylation in health and disease.
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Affiliation(s)
- Michael J Shipston
- Centre for Integrative Physiology, College of Medicine and Veterinary Medicine, University of Edinburgh, Edinburgh EH8 9XD Scotland, UK
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Li J, Jia J, Li H, Yu J, Sun H, He Y, Lv D, Yang X, Glocker MO, Ma L, Yang J, Li L, Li W, Zhang G, Liu Q, Li Y, Xie L. SysPTM 2.0: an updated systematic resource for post-translational modification. DATABASE-THE JOURNAL OF BIOLOGICAL DATABASES AND CURATION 2014; 2014:bau025. [PMID: 24705204 PMCID: PMC3975108 DOI: 10.1093/database/bau025] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Post-translational modifications (PTMs) of proteins play essential roles in almost all cellular processes, and are closely related to physiological activity and disease development of living organisms. The development of tandem mass spectrometry (MS/MS) has resulted in a rapid increase of PTMs identified on proteins from different species. The collection and systematic ordering of PTM data should provide invaluable information for understanding cellular processes and signaling pathways regulated by PTMs. For this original purpose we developed SysPTM, a systematic resource installed with comprehensive PTM data and a suite of web tools for annotation of PTMs in 2009. Four years later, there has been a significant advance with the generation of PTM data and, consequently, more sophisticated analysis requirements have to be met. Here we submit an updated version of SysPTM 2.0 (http://lifecenter.sgst.cn/SysPTM/), with almost doubled data content, enhanced web-based analysis tools of PTMBlast, PTMPathway, PTMPhylog, PTMCluster. Moreover, a new session SysPTM-H is constructed to graphically represent the combinatorial histone PTMs and dynamic regulation of histone modifying enzymes, and a new tool PTMGO is added for functional annotation and enrichment analysis. SysPTM 2.0 not only facilitates resourceful annotation of PTM sites but allows systematic investigation of PTM functions by the user. Database URL: http://lifecenter.sgst.cn/SysPTM/.
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Affiliation(s)
- Jing Li
- Key Laboratory of Biomedical Photonics of Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, P. R. China, Shanghai Center for Bioinformation Technology, Shanghai Institutes of Biomedicine, Shanghai Academy of Science and Technology, Shanghai 201203, P. R. China, Britton Chance Center for Biomedical Photonics, Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, P. R. China, Department of Bioinformatics and Biostatistics, Shanghai Jiaotong University, Shanghai 200240, P. R. China, Key Laboratory of Systems Biology, Chinese Academy of Sciences, Shanghai 200031, P. R. China and Proteome Center Rostock, Department for Proteome Research, Institute of Immunology, University of Rostock, Rostock 18055, Germany
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