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Hilgendorf KI, Myers BR, Reiter JF. Emerging mechanistic understanding of cilia function in cellular signalling. Nat Rev Mol Cell Biol 2024; 25:555-573. [PMID: 38366037 PMCID: PMC11199107 DOI: 10.1038/s41580-023-00698-5] [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] [Accepted: 12/21/2023] [Indexed: 02/18/2024]
Abstract
Primary cilia are solitary, immotile sensory organelles present on most cells in the body that participate broadly in human health, physiology and disease. Cilia generate a unique environment for signal transduction with tight control of protein, lipid and second messenger concentrations within a relatively small compartment, enabling reception, transmission and integration of biological information. In this Review, we discuss how cilia function as signalling hubs in cell-cell communication using three signalling pathways as examples: ciliary G-protein-coupled receptors (GPCRs), the Hedgehog (Hh) pathway and polycystin ion channels. We review how defects in these ciliary signalling pathways lead to a heterogeneous group of conditions known as 'ciliopathies', including metabolic syndromes, birth defects and polycystic kidney disease. Emerging understanding of these pathways' transduction mechanisms reveals common themes between these cilia-based signalling pathways that may apply to other pathways as well. These mechanistic insights reveal how cilia orchestrate normal and pathophysiological signalling outputs broadly throughout human biology.
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Affiliation(s)
- Keren I Hilgendorf
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT, USA.
| | - Benjamin R Myers
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT, USA.
- Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah School of Medicine, Salt Lake City, UT, USA.
- Department of Bioengineering, University of Utah School of Medicine, Salt Lake City, UT, USA.
| | - Jeremy F Reiter
- Department of Biochemistry and Biophysics, Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA, USA.
- Chan Zuckerberg Biohub, San Francisco, CA, USA.
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2
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Schütz GJ, Pabst G. The asymmetric plasma membrane-A composite material combining different functionalities?: Balancing Barrier Function and Fluidity for Effective Signaling. Bioessays 2023; 45:e2300116. [PMID: 37712937 DOI: 10.1002/bies.202300116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Revised: 08/31/2023] [Accepted: 09/06/2023] [Indexed: 09/16/2023]
Abstract
One persistent puzzle in the life sciences is the asymmetric lipid composition of the cellular plasma membrane: while the exoplasmic leaflet is enriched in lipids carrying predominantly saturated fatty acids, the cytoplasmic leaflet hosts preferentially lipids with (poly-)unsaturated fatty acids. Given the high energy requirements necessary for cells to maintain this asymmetry, the question naturally arises regarding its inherent benefits. In this paper, we propose asymmetry to represent a potential solution for harmonizing two conflicting requirements for the plasma membrane: first, the need to build a barrier for the uncontrolled influx or efflux of substances; and second, the need to form a fluid and dynamic two-dimensional substrate for signaling processes. We hence view here the plasma membrane as a composite material, where the exoplasmic leaflet is mainly responsible for the functional integrity of the barrier and the cytoplasmic leaflet for fluidity. We reinforce the validity of the proposed mechanism by presenting quantitative data from the literature, along with multiple examples that bolster our model.
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Affiliation(s)
| | - Georg Pabst
- Biophysics, Institute of Molecular Bioscience (IMB), NAWI Graz, University of Graz, Graz, Austria
- BioTechMed Graz, Graz, Austria
- Field of Excellence BioHealth-University of Graz, Graz, Austria
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3
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Tennakoon M, Thotamune W, Payton JL, Karunarathne A. CaaX-motif-adjacent residues influence G protein gamma (Gγ) prenylation under suboptimal conditions. J Biol Chem 2023; 299:105269. [PMID: 37739036 PMCID: PMC10590752 DOI: 10.1016/j.jbc.2023.105269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 09/06/2023] [Accepted: 09/09/2023] [Indexed: 09/24/2023] Open
Abstract
Prenylation is an irreversible post-translational modification that supports membrane interactions of proteins involved in various cellular processes, including migration, proliferation, and survival. Dysregulation of prenylation contributes to multiple disorders, including cancers and vascular and neurodegenerative diseases. Prenyltransferases tether isoprenoid lipids to proteins via a thioether linkage during prenylation. Pharmacological inhibition of the lipid synthesis pathway by statins is a therapeutic approach to control hyperlipidemia. Building on our previous finding that statins inhibit membrane association of G protein γ (Gγ) in a subtype-dependent manner, we investigated the molecular reasoning for this differential inhibition. We examined the prenylation of carboxy-terminus (Ct) mutated Gγ in cells exposed to Fluvastatin and prenyl transferase inhibitors and monitored the subcellular localization of fluorescently tagged Gγ subunits and their mutants using live-cell confocal imaging. Reversible optogenetic unmasking-masking of Ct residues was used to probe their contribution to prenylation and membrane interactions of the prenylated proteins. Our findings suggest that specific Ct residues regulate membrane interactions of the Gγ polypeptide, statin sensitivity, and extent of prenylation. Our results also show a few hydrophobic and charged residues at the Ct are crucial determinants of a protein's prenylation ability, especially under suboptimal conditions. Given the cell and tissue-specific expression of different Gγ subtypes, our findings indicate a plausible mechanism allowing for statins to differentially perturb heterotrimeric G protein signaling in cells depending on their Gγ-subtype composition. Our results may also provide molecular reasoning for repurposing statins as Ras oncogene inhibitors and the failure of using prenyltransferase inhibitors in cancer treatment.
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Affiliation(s)
- Mithila Tennakoon
- Department of Chemistry, Saint Louis University, Saint Louis, Missouri, USA; Department of Chemistry and Biochemistry, The University of Toledo, Toledo, Ohio, USA; Institute for Drug and Biotherapeutic Innovation, Saint Louis University, Saint Louis, Missouri, USA
| | - Waruna Thotamune
- Department of Chemistry, Saint Louis University, Saint Louis, Missouri, USA; Department of Chemistry and Biochemistry, The University of Toledo, Toledo, Ohio, USA; Institute for Drug and Biotherapeutic Innovation, Saint Louis University, Saint Louis, Missouri, USA
| | - John L Payton
- Department of Chemistry, Kenyon College, Gambier, Ohio, USA
| | - Ajith Karunarathne
- Department of Chemistry, Saint Louis University, Saint Louis, Missouri, USA; Department of Chemistry and Biochemistry, The University of Toledo, Toledo, Ohio, USA; Institute for Drug and Biotherapeutic Innovation, Saint Louis University, Saint Louis, Missouri, USA.
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4
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Li B, Maruszko K, Kim SK, Yang MY, Vo ADP, Goddard WA. Structure and Molecular Mechanism of Signaling for the Glucagon-like Peptide-1 Receptor Bound to Gs Protein and Exendin-P5 Biased Agonist. J Am Chem Soc 2023; 145:20422-20431. [PMID: 37672637 PMCID: PMC10777869 DOI: 10.1021/jacs.3c05996] [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] [Indexed: 09/08/2023]
Abstract
The glucagon-like peptide-1 receptor (GLP-1R) is a key regulator of blood glucose and a prime target for the treatment of type II diabetes and obesity with multiple public drugs. Here we present a comprehensive computational analysis of the interactions of the activated GLP-1R-Gs signaling complex with a G protein biased agonist, Exendin P5 (ExP5), which possesses a unique N-terminal sequence responsible for the signal bias. Using a refined all-atom model of the ExP5-GLP-1R-Gs complex in molecular dynamics (MD) simulations, we propose a novel mechanism of conformation transduction in which the unique interaction network of ExP5 N-terminus propagates the binding signal across an array of conserved residues at the transmembrane domain to enhance Gs protein coupling at the cytoplasmic end of the receptor. Our simulations reveal previously unobserved interactions important for activation by ExP5 toward GDP-GTP signaling, providing new insights into the mechanism of class B G protein-coupled receptor (GPCR) signaling. These findings offer a framework for the structure-based design of more effective therapeutics.
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Affiliation(s)
- Bo Li
- Division of Chemistry and Chemical Engineering and Materials Process and Simulation Center, California Institute of Technology, Pasadena, California 91125, United States
| | - Krystyna Maruszko
- Division of Chemistry and Chemical Engineering and Materials Process and Simulation Center, California Institute of Technology, Pasadena, California 91125, United States
| | - Soo-Kyung Kim
- Division of Chemistry and Chemical Engineering and Materials Process and Simulation Center, California Institute of Technology, Pasadena, California 91125, United States
| | - Moon Young Yang
- Division of Chemistry and Chemical Engineering and Materials Process and Simulation Center, California Institute of Technology, Pasadena, California 91125, United States
| | - Amy-Doan P Vo
- Division of Chemistry and Chemical Engineering and Materials Process and Simulation Center, California Institute of Technology, Pasadena, California 91125, United States
| | - William A Goddard
- Division of Chemistry and Chemical Engineering and Materials Process and Simulation Center, California Institute of Technology, Pasadena, California 91125, United States
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5
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Tennakoon M, Thotamune W, Payton JL, Karunarathne A. CaaX-motif adjacent residues control G protein prenylation under suboptimal conditions. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.04.547731. [PMID: 37461501 PMCID: PMC10349941 DOI: 10.1101/2023.07.04.547731] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 07/30/2023]
Abstract
Prenylation is a universal and irreversible post-translational modification that supports membrane interactions of proteins involved in various cellular processes, including migration, proliferation, and survival. Thus, dysregulation of prenylation contributes to multiple disorders, including cancers, vascular diseases, and neurodegenerative diseases. During prenylation, prenyltransferase enzymes tether metabolically produced isoprenoid lipids to proteins via a thioether linkage. Pharmacological inhibition of the lipid synthesis pathway by statins has long been a therapeutic approach to control hyperlipidemia. Building on our previous finding that statins inhibit membrane association of G protein γ (Gγ) in a subtype-dependent manner, we investigated the molecular reasoning for this differential. We examined the prenylation efficacy of carboxy terminus (Ct) mutated Gγ in cells exposed to Fluvastatin and prenyl transferase inhibitors and monitored the subcellular localization of fluorescently tagged Gγ subunits and their mutants using live-cell confocal imaging. Reversible optogenetic unmasking-masking of Ct residues was used to probe their contribution to the prenylation process and membrane interactions of the prenylated proteins. Our findings suggest that specific Ct residues regulate membrane interactions of the Gγ polypeptide statin sensitivity, and prenylation efficacy. Our results also show that a few hydrophobic and charged residues at the Ct are crucial determinants of a protein's prenylation ability, especially under suboptimal conditions. Given the cell and tissue-specific expression of different Gγ subtypes, our findings explain how and why statins differentially perturb heterotrimeric G protein signaling in specific cells and tissues. Our results may provide molecular reasoning for repurposing statins as Ras oncogene inhibitors and the failure of using prenyltransferase inhibitors in cancer treatment.
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Affiliation(s)
- Mithila Tennakoon
- Department of Chemistry, Saint Louis University, Saint Louis, MO 63103, USA
- Department of Chemistry and Biochemistry, The University of Toledo, Toledo, OH 43606, USA
- Institute for Drug and Biotherapeutic Innovation, Saint Louis University, Saint Louis, MO 63103, USA
| | - Waruna Thotamune
- Department of Chemistry, Saint Louis University, Saint Louis, MO 63103, USA
- Department of Chemistry and Biochemistry, The University of Toledo, Toledo, OH 43606, USA
- Institute for Drug and Biotherapeutic Innovation, Saint Louis University, Saint Louis, MO 63103, USA
| | - John L. Payton
- Department of Chemistry, Kenyon College, Gambier, Ohio 43022, USA
| | - Ajith Karunarathne
- Department of Chemistry, Saint Louis University, Saint Louis, MO 63103, USA
- Department of Chemistry and Biochemistry, The University of Toledo, Toledo, OH 43606, USA
- Institute for Drug and Biotherapeutic Innovation, Saint Louis University, Saint Louis, MO 63103, USA
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6
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Kankanamge D, Tennakoon M, Karunarathne A, Gautam N. G protein gamma subunit, a hidden master regulator of GPCR signaling. J Biol Chem 2022; 298:102618. [PMID: 36272647 PMCID: PMC9678972 DOI: 10.1016/j.jbc.2022.102618] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Revised: 10/10/2022] [Accepted: 10/14/2022] [Indexed: 11/21/2022] Open
Abstract
Heterotrimeric G proteins (αβγ subunits) that are activated by G protein-coupled receptors (GPCRs) mediate the biological responses of eukaryotic cells to extracellular signals. The α subunits and the tightly bound βγ subunit complex of G proteins have been extensively studied and shown to control the activity of effector molecules. In contrast, the potential roles of the large family of γ subunits have been less studied. In this review, we focus on present knowledge about these proteins. Induced loss of individual γ subunit types in animal and plant models result in strikingly distinct phenotypes indicating that γ subtypes play important and specific roles. Consistent with these findings, downregulation or upregulation of particular γ subunit types result in various types of cancers. Clues about the mechanistic basis of γ subunit function have emerged from imaging the dynamic behavior of G protein subunits in living cells. This shows that in the basal state, G proteins are not constrained to the plasma membrane but shuttle between membranes and on receptor activation βγ complexes translocate reversibly to internal membranes. The translocation kinetics of βγ complexes varies widely and is determined by the membrane affinity of the associated γ subtype. On translocating, some βγ complexes act on effectors in internal membranes. The variation in translocation kinetics determines differential sensitivity and adaptation of cells to external signals. Membrane affinity of γ subunits is thus a parsimonious and elegant mechanism that controls information flow to internal cell membranes while modulating signaling responses.
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Affiliation(s)
- Dinesh Kankanamge
- Department of Anesthesiology, Washington University School of Medicine, St Louis, Missouri, USA
| | - Mithila Tennakoon
- Department of Chemistry, St Louis University, St Louis, Missouri, USA
| | | | - N Gautam
- Department of Anesthesiology, Washington University School of Medicine, St Louis, Missouri, USA; Department of Genetics, Washington University School of Medicine, St Louis, Missouri, USA.
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7
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Cao C, Barros-Álvarez X, Zhang S, Kim K, Dämgen MA, Panova O, Suomivuori CM, Fay JF, Zhong X, Krumm BE, Gumpper RH, Seven AB, Robertson MJ, Krogan NJ, Hüttenhain R, Nichols DE, Dror RO, Skiniotis G, Roth BL. Signaling snapshots of a serotonin receptor activated by the prototypical psychedelic LSD. Neuron 2022; 110:3154-3167.e7. [PMID: 36087581 PMCID: PMC9583076 DOI: 10.1016/j.neuron.2022.08.006] [Citation(s) in RCA: 50] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 07/13/2022] [Accepted: 08/12/2022] [Indexed: 10/14/2022]
Abstract
Serotonin (5-hydroxytryptamine [5-HT]) 5-HT2-family receptors represent essential targets for lysergic acid diethylamide (LSD) and all other psychedelic drugs. Although the primary psychedelic drug effects are mediated by the 5-HT2A serotonin receptor (HTR2A), the 5-HT2B serotonin receptor (HTR2B) has been used as a model receptor to study the activation mechanisms of psychedelic drugs due to its high expression and similarity to HTR2A. In this study, we determined the cryo-EM structures of LSD-bound HTR2B in the transducer-free, Gq-protein-coupled, and β-arrestin-1-coupled states. These structures provide distinct signaling snapshots of LSD's action, ranging from the transducer-free, partially active state to the transducer-coupled, fully active states. Insights from this study will both provide comprehensive molecular insights into the signaling mechanisms of the prototypical psychedelic LSD and accelerate the discovery of novel psychedelic drugs.
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Affiliation(s)
- Can Cao
- Department of Pharmacology, University of North Carolina at Chapel Hill, School of Medicine, Chapel Hill, NC 27599-7365, USA
| | - Ximena Barros-Álvarez
- Department of Molecular and Cellular Physiology, Department of Structural Biology, Stanford University School of Medicine, Stanford University, Stanford, CA 94305, USA
| | - Shicheng Zhang
- Department of Pharmacology, University of North Carolina at Chapel Hill, School of Medicine, Chapel Hill, NC 27599-7365, USA
| | - Kuglae Kim
- Department of Pharmacology, University of North Carolina at Chapel Hill, School of Medicine, Chapel Hill, NC 27599-7365, USA
| | - Marc A Dämgen
- Department of Molecular and Cellular Physiology, Department of Structural Biology, Stanford University School of Medicine, Stanford University, Stanford, CA 94305, USA; Department of Computer Science, Stanford University, Stanford, CA 94305, USA; Institute for Computational and Mathematical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Ouliana Panova
- Department of Molecular and Cellular Physiology, Department of Structural Biology, Stanford University School of Medicine, Stanford University, Stanford, CA 94305, USA
| | - Carl-Mikael Suomivuori
- Department of Molecular and Cellular Physiology, Department of Structural Biology, Stanford University School of Medicine, Stanford University, Stanford, CA 94305, USA; Department of Computer Science, Stanford University, Stanford, CA 94305, USA; Institute for Computational and Mathematical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Jonathan F Fay
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, School of Medicine, Chapel Hill, NC 7599-7365, USA
| | - Xiaofang Zhong
- Quantitative Biosciences Institute (QBI), University of California, San Francisco, San Francisco, CA, USA; J. David Gladstone Institutes, San Francisco, CA, USA; Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA, USA
| | - Brian E Krumm
- Department of Pharmacology, University of North Carolina at Chapel Hill, School of Medicine, Chapel Hill, NC 27599-7365, USA
| | - Ryan H Gumpper
- Department of Pharmacology, University of North Carolina at Chapel Hill, School of Medicine, Chapel Hill, NC 27599-7365, USA
| | - Alpay B Seven
- Department of Molecular and Cellular Physiology, Department of Structural Biology, Stanford University School of Medicine, Stanford University, Stanford, CA 94305, USA
| | - Michael J Robertson
- Department of Molecular and Cellular Physiology, Department of Structural Biology, Stanford University School of Medicine, Stanford University, Stanford, CA 94305, USA
| | - Nevan J Krogan
- Quantitative Biosciences Institute (QBI), University of California, San Francisco, San Francisco, CA, USA; J. David Gladstone Institutes, San Francisco, CA, USA; Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA, USA
| | - Ruth Hüttenhain
- Quantitative Biosciences Institute (QBI), University of California, San Francisco, San Francisco, CA, USA; J. David Gladstone Institutes, San Francisco, CA, USA; Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA, USA
| | - David E Nichols
- Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, NC 27599-7365, USA
| | - Ron O Dror
- Department of Molecular and Cellular Physiology, Department of Structural Biology, Stanford University School of Medicine, Stanford University, Stanford, CA 94305, USA; Department of Computer Science, Stanford University, Stanford, CA 94305, USA; Institute for Computational and Mathematical Engineering, Stanford University, Stanford, CA 94305, USA.
| | - Georgios Skiniotis
- Department of Molecular and Cellular Physiology, Department of Structural Biology, Stanford University School of Medicine, Stanford University, Stanford, CA 94305, USA.
| | - Bryan L Roth
- Department of Pharmacology, University of North Carolina at Chapel Hill, School of Medicine, Chapel Hill, NC 27599-7365, USA; Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, NC 27599-7365, USA.
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8
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A Naturally Occurring Membrane-Anchored Gα s Variant, XLαs, Activates Phospholipase Cβ4. J Biol Chem 2022; 298:102134. [PMID: 35709985 PMCID: PMC9294334 DOI: 10.1016/j.jbc.2022.102134] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Revised: 05/31/2022] [Accepted: 06/01/2022] [Indexed: 12/02/2022] Open
Abstract
Extra-large stimulatory Gα (XLαs) is a large variant of G protein αs subunit (Gαs) that uses an alternative promoter and thus differs from Gαs at the first exon. XLαs activation by G protein–coupled receptors mediates cAMP generation, similarly to Gαs; however, Gαs and XLαs have been shown to have distinct cellular and physiological functions. For example, previous work suggests that XLαs can stimulate inositol phosphate production in renal proximal tubules and thereby regulate serum phosphate levels. In this study, we show that XLαs directly and specifically stimulates a specific isoform of phospholipase Cβ (PLCβ), PLCβ4, both in transfected cells and with purified protein components. We demonstrate that neither the ability of XLαs to activate cAMP generation nor the canonical G protein switch II regions are required for PLCβ stimulation. Furthermore, this activation is nucleotide independent but is inhibited by Gβγ, suggesting a mechanism of activation that relies on Gβγ subunit dissociation. Surprisingly, our results indicate that enhanced membrane targeting of XLαs relative to Gαs confers the ability to activate PLCβ4. We also show that PLCβ4 is required for isoproterenol-induced inositol phosphate accumulation in osteocyte-like Ocy454 cells. Taken together, we demonstrate a novel mechanism for activation of phosphoinositide turnover downstream of Gs-coupled receptors that may have a critical role in endocrine physiology.
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9
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Liao Q, Ye RD. Structural and conformational studies of biased agonism through formyl peptide receptors. Am J Physiol Cell Physiol 2022; 322:C939-C947. [PMID: 35385323 DOI: 10.1152/ajpcell.00108.2022] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
G protein-coupled chemoattractant receptors are class A GPCRs that couple primarily to the Gi class of heterotrimeric G proteins. Initially identified for their abilities to mediate leukocyte chemotaxis, chemoattractant GPCRs such as the formyl peptide receptors (FPRs) have been known for their diverse cellular functions in response to a variety of agonists. Stimulation of FPR2, in particular, leads to ligand-dependent activation of pro-inflammatory signaling as well as anti-inflammatory and pro-resolving signaling. Recently, the structures of FPR2-Gi protein complexed with ligands of different compositions have been solved by crystallization and cryo-electron microscopy. Analysis of the structural data as well as molecular simulation have led to the findings that the FPR2 binding pocket is sufficiently large for accommodation of several different types of ligands, but in different poses. This mini-review focuses on the structural and conformational aspects of FPR2 for mechanisms underlying its biased agonism.
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Affiliation(s)
- Qiwen Liao
- Kobilka Institute of Innovative Drug Discovery, School of Medicine, The Chinese University of Hong Kong, Shenzhen, China
| | - Richard D Ye
- Kobilka Institute of Innovative Drug Discovery, School of Medicine, The Chinese University of Hong Kong, Shenzhen, China
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10
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Huang SK, Prosser RS. Dynamics and Mechanistic Underpinnings to Pharmacology of Class A GPCRs - An NMR Perspective. Am J Physiol Cell Physiol 2022; 322:C739-C753. [PMID: 35235425 DOI: 10.1152/ajpcell.00044.2022] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
One-third of current pharmaceuticals target G protein-coupled receptors (GPCRs), the largest receptor superfamily in humans and mediators of diverse physiological processes. This review summarizes the recent progress in GPCR structural dynamics, focusing on class A receptors and insights derived from nuclear magnetic resonance (NMR) and other spectroscopic techniques. We describe the structural aspects of GPCR activation and the various pharmacological models that capture aspects of receptor signaling behaviour. Spectroscopic studies revealed that receptors and their signaling complexes are dynamic allosteric systems that sample multiple functional states under basal conditions. The distribution of states within the conformational ensemble and the kinetics of transitions between states are regulated through the binding of ligands, allosteric modulators, and the membrane environment. This ensemble view of GPCRs provides a mechanistic framework for understanding many of the pharmacological phenomena associated with receptor signaling, such as basal activity, efficacy, and functional bias.
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Affiliation(s)
- Shuya Kate Huang
- Department of Chemistry, University of Toronto, Toronto, Ontario, Canada.,Department of Chemical and Physical Sciences, University of Toronto Mississauga, Mississauga, Ontario, Canada
| | - R Scott Prosser
- Department of Chemistry, University of Toronto, Toronto, Ontario, Canada.,Department of Chemical and Physical Sciences, University of Toronto Mississauga, Mississauga, Ontario, Canada.,Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
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11
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Morris G, Walder K, Berk M, Carvalho AF, Marx W, Bortolasci CC, Yung AR, Puri BK, Maes M. Intertwined associations between oxidative and nitrosative stress and endocannabinoid system pathways: Relevance for neuropsychiatric disorders. Prog Neuropsychopharmacol Biol Psychiatry 2022; 114:110481. [PMID: 34826557 DOI: 10.1016/j.pnpbp.2021.110481] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Revised: 10/19/2021] [Accepted: 11/21/2021] [Indexed: 12/12/2022]
Abstract
The endocannabinoid system (ECS) appears to regulate metabolic, cardiovascular, immune, gastrointestinal, lung, and reproductive system functions, as well as the central nervous system. There is also evidence that neuropsychiatric disorders are associated with ECS abnormalities as well as oxidative and nitrosative stress pathways. The goal of this mechanistic review is to investigate the mechanisms underlying the ECS's regulation of redox signalling, as well as the mechanisms by which activated oxidative and nitrosative stress pathways may impair ECS-mediated signalling. Cannabinoid receptor (CB)1 activation and upregulation of brain CB2 receptors reduce oxidative stress in the brain, resulting in less tissue damage and less neuroinflammation. Chronically high levels of oxidative stress may impair CB1 and CB2 receptor activity. CB1 activation in peripheral cells increases nitrosative stress and inducible nitric oxide (iNOS) activity, reducing mitochondrial activity. Upregulation of CB2 in the peripheral and central nervous systems may reduce iNOS, nitrosative stress, and neuroinflammation. Nitrosative stress may have an impact on CB1 and CB2-mediated signalling. Peripheral immune activation, which frequently occurs in response to nitro-oxidative stress, may result in increased expression of CB2 receptors on T and B lymphocytes, dendritic cells, and macrophages, reducing the production of inflammatory products and limiting the duration and intensity of the immune and oxidative stress response. In conclusion, high levels of oxidative and nitrosative stress may compromise or even abolish ECS-mediated redox pathway regulation. Future research in neuropsychiatric disorders like mood disorders and deficit schizophrenia should explore abnormalities in these intertwined signalling pathways.
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Affiliation(s)
- Gerwyn Morris
- Deakin University, IMPACT - the Institute for Mental and Physical Health and Clinical Translation, School of Medicine, Barwon Health, Geelong, Australia
| | - Ken Walder
- Deakin University, IMPACT - the Institute for Mental and Physical Health and Clinical Translation, School of Medicine, Barwon Health, Geelong, Australia.
| | - Michael Berk
- Deakin University, IMPACT - the Institute for Mental and Physical Health and Clinical Translation, School of Medicine, Barwon Health, Geelong, Australia; Orygen, Parkville, Victoria, Australia; Centre for Youth Mental Health, The University of Melbourne, Parkville, Victoria, Australia.
| | - Andre F Carvalho
- Deakin University, IMPACT - the Institute for Mental and Physical Health and Clinical Translation, School of Medicine, Barwon Health, Geelong, Australia
| | - Wolf Marx
- Deakin University, IMPACT - the Institute for Mental and Physical Health and Clinical Translation, School of Medicine, Barwon Health, Geelong, Australia.
| | - Chiara C Bortolasci
- Deakin University, IMPACT - the Institute for Mental and Physical Health and Clinical Translation, School of Medicine, Barwon Health, Geelong, Australia.
| | - Alison R Yung
- Deakin University, IMPACT - the Institute for Mental and Physical Health and Clinical Translation, School of Medicine, Barwon Health, Geelong, Australia; Orygen, Parkville, Victoria, Australia; Centre for Youth Mental Health, The University of Melbourne, Parkville, Victoria, Australia; School of Health Science, University of Manchester, UK.
| | - Basant K Puri
- University of Winchester, UK, and C.A.R., Cambridge, UK.
| | - Michael Maes
- Deakin University, IMPACT - the Institute for Mental and Physical Health and Clinical Translation, School of Medicine, Barwon Health, Geelong, Australia; Department of Psychiatry, Faculty of Medicine, King Chulalongkorn Memorial Hospital, Bangkok, Thailand; Department of Psychiatry, Medical University of Plovdiv, Plovdiv, Bulgaria.
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12
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Development of a High-Throughput Calcium Mobilization Assay for CCR6 Receptor Coupled to Hydrolase Activity Readout. Biomedicines 2022; 10:biomedicines10020422. [PMID: 35203631 PMCID: PMC8962412 DOI: 10.3390/biomedicines10020422] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2021] [Revised: 01/17/2022] [Accepted: 02/07/2022] [Indexed: 02/01/2023] Open
Abstract
CCR6 is a chemokine receptor highly implicated in inflammatory diseases and could be a potential therapeutic target; however, no therapeutic agents targeting CCR6 have progressed into clinical evaluation. Development of a high-throughput screening assay for CCR6 should facilitate the identification of novel compounds against CCR6. To develop a cell-based assay, RBL-2H3 cells were transfected with plasmids encoding β-hexosaminidase and CCR6. Intracellular calcium mobilization of transfected cells was measured with a fluorescent substrate using the activity of released hexosaminidase as readout of the assay. This stable, transfected cell showed a specific signal to the background ratio of 19.1 with low variability of the signal along the time. The assay was validated and optimized for high-throughput screening. The cell-based calcium mobilization assay responded to the specific CCR6 ligand, CCL20, in a dose-dependent manner with an EC50 value of 10.72 nM. Furthermore, the assay was deemed robust and reproducible with a Z’ factor of 0.63 and a signal window of 7.75. We have established a cell-based high-throughput calcium mobilization assay for CCR6 receptor. This assay monitors calcium mobilization, due to CCR6h activation by CCL20, using hexosaminidase activity as readout. This assay was proved to be robust, easy to automate and could be used as method for screening of CCR6 modulators.
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Tsutsumi N, Maeda S, Qu Q, Vögele M, Jude KM, Suomivuori CM, Panova O, Waghray D, Kato HE, Velasco A, Dror RO, Skiniotis G, Kobilka BK, Garcia KC. Atypical structural snapshots of human cytomegalovirus GPCR interactions with host G proteins. SCIENCE ADVANCES 2022; 8:eabl5442. [PMID: 35061538 PMCID: PMC8782444 DOI: 10.1126/sciadv.abl5442] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Accepted: 11/29/2021] [Indexed: 05/12/2023]
Abstract
Human cytomegalovirus (HCMV) encodes G protein-coupled receptors (GPCRs) US28 and US27, which facilitate viral pathogenesis through engagement of host G proteins. Here we report cryo-electron microscopy structures of US28 and US27 forming nonproductive and productive complexes with Gi and Gq, respectively, exhibiting unusual features with functional implications. The "orphan" GPCR US27 lacks a ligand-binding pocket and has captured a guanosine diphosphate-bound inactive Gi through a tenuous interaction. The docking modes of CX3CL1-US28 and US27 to Gi favor localization to endosome-like curved membranes, where US28 and US27 can function as nonproductive Gi sinks to attenuate host chemokine-dependent Gi signaling. The CX3CL1-US28-Gq/11 complex likely represents a trapped intermediate during productive signaling, providing a view of a transition state in GPCR-G protein coupling for signaling. Our collective results shed new insight into unique G protein-mediated HCMV GPCR structural mechanisms, compared to mammalian GPCR counterparts, for subversion of host immunity.
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Affiliation(s)
- Naotaka Tsutsumi
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA, USA
- Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA, USA
| | - Shoji Maeda
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA
| | - Qianhui Qu
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA, USA
| | - Martin Vögele
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA, USA
- Department of Computer Science, Stanford University, Stanford, CA, USA
- Institute for Computational and Mathematical Engineering, Stanford University, Stanford, CA, USA
| | - Kevin M. Jude
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA, USA
- Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA, USA
| | - Carl-Mikael Suomivuori
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA, USA
- Department of Computer Science, Stanford University, Stanford, CA, USA
- Institute for Computational and Mathematical Engineering, Stanford University, Stanford, CA, USA
| | - Ouliana Panova
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA, USA
| | - Deepa Waghray
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA
| | - Hideaki E. Kato
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA
| | - Andrew Velasco
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA
| | - Ron O. Dror
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA, USA
- Department of Computer Science, Stanford University, Stanford, CA, USA
- Institute for Computational and Mathematical Engineering, Stanford University, Stanford, CA, USA
| | - Georgios Skiniotis
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA, USA
| | - Brian K. Kobilka
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA
| | - K. Christopher Garcia
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA, USA
- Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA, USA
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Liu H, Zhang C. Measuring Smoothened (SMO)-Mediated Activation of the G i Protein. Methods Mol Biol 2022; 2374:205-212. [PMID: 34562255 DOI: 10.1007/978-1-0716-1701-4_18] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The oncoprotein Smoothened (SMO) can transduce the Hedgehog signal from the tumor suppressor Patched-1 (PTCH1) to glioma-associated-oncogene (Gli) transcription factors. Previous studies have shown that SMO is a G-protein-coupled receptor (GPCR) of the Frizzled-class (class-F) that can activate Gi family of heterotrimeric G proteins. Here, we describe [35S]-GTPγS assay using SMO cell membranes and purified Gi protein to measure the level of Gi protein activation following the activation of SMO by agonists.
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Affiliation(s)
- Heng Liu
- Department of Pharmacology and Chemical Biology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Cheng Zhang
- Department of Pharmacology and Chemical Biology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, USA.
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15
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Tennakoon M, Senarath K, Kankanamge D, Chadee DN, Karunarathne A. A short C-terminal peptide in Gγ regulates Gβγ signaling efficacy. Mol Biol Cell 2021; 32:1446-1458. [PMID: 34106735 PMCID: PMC8351738 DOI: 10.1091/mbc.e20-11-0750] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 05/03/2021] [Accepted: 06/04/2021] [Indexed: 01/03/2023] Open
Abstract
G protein beta-gamma (Gβγ) subunits anchor to the plasma membrane (PM) through the carboxy-terminal (CT) prenyl group in Gγ. This interaction is crucial for the PM localization and functioning of Gβγ, allowing GPCR-G protein signaling to proceed. The diverse Gγ family has 12 members, and we have recently shown that the signaling efficacies of major Gβγ effectors are Gγ-type dependent. This dependency is due to the distinct series of membrane-interacting abilities of Gγ. However, the molecular process allowing for Gβγ subunits to exhibit a discrete and diverse range of Gγ-type-dependent membrane affinities is unclear and cannot be explained using only the type of prenylation. The present work explores the unique designs of membrane-interacting CT residues in Gγ as a major source for this Gγ-type-dependent Gβγ signaling. Despite the type of prenylation, the results show signaling efficacy at the PM, and associated cell behaviors of Gβγ are governed by crucially located specific amino acids in the five to six residue preprenylation region of Gγ. The provided molecular picture of Gγ-membrane interactions may explain how cells gain Gγ-type-dependent G protein-GPCR signaling as well as how Gβγ elicits selective signaling at various subcellular compartments.
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Affiliation(s)
- Mithila Tennakoon
- Department of Chemistry and Biochemistry, The University of Toledo, Toledo, OH 43606
| | - Kanishka Senarath
- Department of Chemistry and Biochemistry, The University of Toledo, Toledo, OH 43606
| | - Dinesh Kankanamge
- Department of Chemistry and Biochemistry, The University of Toledo, Toledo, OH 43606
| | - Deborah N. Chadee
- Department of Biological Sciences, The University of Toledo, Toledo, OH 43606
| | - Ajith Karunarathne
- Department of Chemistry and Biochemistry, The University of Toledo, Toledo, OH 43606
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Tennakoon M, Senarath K, Kankanamge D, Ratnayake K, Wijayaratna D, Olupothage K, Ubeysinghe S, Martins-Cannavino K, Hébert TE, Karunarathne A. Subtype-dependent regulation of Gβγ signalling. Cell Signal 2021; 82:109947. [PMID: 33582184 PMCID: PMC8026654 DOI: 10.1016/j.cellsig.2021.109947] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 02/01/2021] [Accepted: 02/02/2021] [Indexed: 01/04/2023]
Abstract
G protein-coupled receptors (GPCRs) transmit information to the cell interior by transducing external signals to heterotrimeric G protein subunits, Gα and Gβγ subunits, localized on the inner leaflet of the plasma membrane. Though the initial focus was mainly on Gα-mediated events, Gβγ subunits were later identified as major contributors to GPCR-G protein signalling. A broad functional array of Gβγ signalling has recently been attributed to Gβ and Gγ subtype diversity, comprising 5 Gβ and 12 Gγ subtypes, respectively. In addition to displaying selectivity towards each other to form the Gβγ dimer, numerous studies have identified preferences of distinct Gβγ combinations for specific GPCRs, Gα subtypes and effector molecules. Importantly, Gβ and Gγ subtype-dependent regulation of downstream effectors, representing a diverse range of signalling pathways and physiological functions have been found. Here, we review the literature on the repercussions of Gβ and Gγ subtype diversity on direct and indirect regulation of GPCR/G protein signalling events and their physiological outcomes. Our discussion additionally provides perspective in understanding the intricacies underlying molecular regulation of subtype-specific roles of Gβγ signalling and associated diseases.
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Affiliation(s)
- Mithila Tennakoon
- Department of Chemistry and Biochemistry, The University of Toledo, Toledo, OH 43606, USA
| | - Kanishka Senarath
- Genetics and Molecular Biology Unit, University of Sri Jayewardenepura, Nugegoda, Sri Lanka
| | - Dinesh Kankanamge
- Department of Chemistry and Biochemistry, The University of Toledo, Toledo, OH 43606, USA
| | - Kasun Ratnayake
- Department of Chemistry and Biochemistry, The University of Toledo, Toledo, OH 43606, USA; Department of Pharmacology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Dhanushan Wijayaratna
- Department of Chemistry and Biochemistry, The University of Toledo, Toledo, OH 43606, USA
| | - Koshala Olupothage
- Department of Chemistry and Biochemistry, The University of Toledo, Toledo, OH 43606, USA
| | - Sithurandi Ubeysinghe
- Department of Chemistry and Biochemistry, The University of Toledo, Toledo, OH 43606, USA
| | | | - Terence E Hébert
- Department of Pharmacology and Therapeutics, McGill University, Montréal, QC H3G 1Y6, Canada.
| | - Ajith Karunarathne
- Department of Chemistry and Biochemistry, The University of Toledo, Toledo, OH 43606, USA.
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Huang M, Wang Y. GLOBAL AND TARGETED PROFILING OF GTP-BINDING PROTEINS IN BIOLOGICAL SAMPLES BY MASS SPECTROMETRY. MASS SPECTROMETRY REVIEWS 2021; 40:215-235. [PMID: 32519381 PMCID: PMC7725852 DOI: 10.1002/mas.21637] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 05/04/2020] [Accepted: 05/15/2020] [Indexed: 05/05/2023]
Abstract
GTP-binding proteins are among the most important enzyme families that are involved in a plethora of biological processes. However, owing to the enormous diversity of the nucleotide-binding protein family, comprehensive analyses of the expression level, structure, activity, and regulatory mechanisms of GTP-binding proteins remain challenging with the use of conventional approaches. The many advances in mass spectrometry (MS) instrumentation and data acquisition methods, together with a variety of enrichment approaches in sample preparation, render MS a powerful tool for the comprehensive characterizations of the activities and expression levels of various GTP-binding proteins. We review herein the recent developments in the application of MS-based techniques, together with general and widely used affinity enrichment approaches, for the proteome-wide and targeted capture, identification, and quantification of GTP-binding proteins. The working principles, advantages, and limitations of various strategies for profiling the expression level, activity, posttranslational modifications, and interactome of GTP-binding proteins are discussed. It can be envisaged that future applications of MS-based proteomics will lead to a better understanding about the roles of GTP-binding proteins in different biological processes and human diseases. © 2020 John Wiley & Sons Ltd. Mass Spec Rev.
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Affiliation(s)
- Ming Huang
- Environmental Toxicology Graduate Program, University of California Riverside, Riverside, CA 92521, USA
| | - Yinsheng Wang
- Environmental Toxicology Graduate Program, University of California Riverside, Riverside, CA 92521, USA
- Department of Chemistry, University of California Riverside, Riverside, CA 92521, USA
- Correspondence author: Yinsheng Wang. Telephone: (951)827-2700;
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18
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Polit A, Mystek P, Błasiak E. Every Detail Matters. That Is, How the Interaction between Gα Proteins and Membrane Affects Their Function. MEMBRANES 2021; 11:222. [PMID: 33804791 PMCID: PMC8003949 DOI: 10.3390/membranes11030222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Revised: 03/17/2021] [Accepted: 03/18/2021] [Indexed: 11/16/2022]
Abstract
In highly organized multicellular organisms such as humans, the functions of an individual cell are dependent on signal transduction through G protein-coupled receptors (GPCRs) and subsequently heterotrimeric G proteins. As most of the elements belonging to the signal transduction system are bound to lipid membranes, researchers are showing increasing interest in studying the accompanying protein-lipid interactions, which have been demonstrated to not only provide the environment but also regulate proper and efficient signal transduction. The mode of interaction between the cell membrane and G proteins is well known. Despite this, the recognition mechanisms at the molecular level and how the individual G protein-membrane attachment signals are interrelated in the process of the complex control of membrane targeting of G proteins remain unelucidated. This review focuses on the mechanisms by which mammalian Gα subunits of G proteins interact with lipids and the factors responsible for the specificity of membrane association. We summarize recent data on how these signaling proteins are precisely targeted to a specific site in the membrane region by introducing well-defined modifications as well as through the presence of polybasic regions within these proteins and interactions with other components of the heterocomplex.
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Affiliation(s)
- Agnieszka Polit
- Department of Physical Biochemistry, Faculty of Biochemistry Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387 Kraków, Poland; (P.M.); (E.B.)
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19
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Folylpoly-ɣ-glutamate synthetase association to the cytoskeleton: Implications to folate metabolon compartmentalization. J Proteomics 2021; 239:104169. [PMID: 33676037 DOI: 10.1016/j.jprot.2021.104169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 02/03/2021] [Accepted: 02/19/2021] [Indexed: 11/23/2022]
Abstract
Folates are essential for nucleotide biosynthesis, amino acid metabolism and cellular proliferation. Following carrier-mediated uptake, folates are polyglutamylated by folylpoly-ɣ-glutamate synthetase (FPGS), resulting in their intracellular retention. FPGS appears as a long isoform, directed to mitochondria via a leader sequence, and a short isoform reported as a soluble cytosolic protein (cFPGS). However, since folates are labile and folate metabolism is compartmentalized, we herein hypothesized that cFPGS is associated with the cytoskeleton, to couple folate uptake and polyglutamylation and channel folate polyglutamates to metabolon compartments. We show that cFPGS is a cytoskeleton-microtubule associated protein: Western blot analysis revealed that endogenous cFPGS is associated with the insoluble cellular fraction, i.e., cytoskeleton and membranes, but not with the cytosol. Mass spectrometry analysis identified the putative cFPGS interactome primarily consisting of microtubule subunits and cytoskeletal motor proteins. Consistently, immunofluorescence microscopy with cytosol-depleted cells demonstrated the association of cFPGS with the cytoskeleton and unconventional myosin-1c. Furthermore, since anti-microtubule, anti-actin cytoskeleton, and coatomer dissociation-inducing agents yielded perinuclear pausing of cFPGS, we propose an actin- and microtubule-dependent transport of cFPGS between the ER-Golgi and the plasma membrane. These novel findings support the coupling of folate transport with polyglutamylation and folate channeling to intracellular metabolon compartments. SIGNIFICANCE: FPGS, an essential enzyme catalyzing intracellular folate polyglutamylation and efficient retention, was described as a soluble cytosolic enzyme in the past 40 years. However, based on the lability of folates and the compartmentalization of folate metabolism and nucleotide biosynthesis, we herein hypothesized that cytoplasmic FPGS is associated with the cytoskeleton, to couple folate transport and polyglutamylation as well as channel folate polyglutamates to biosynthetic metabolon compartments. Indeed, using complementary techniques including Mass-spectrometry proteomics and fluorescence microscopy, we show that cytoplasmic FPGS is associated with the cytoskeleton and unconventional myosin-1c. This novel cytoskeletal localization of cytoplasmic FPGS supports the dynamic channeling of polyglutamylated folates to metabolon compartments to avoid oxidation and intracellular dilution of folates, while enhancing folate-dependent de novo biosynthesis of nucleotides and DNA/protein methylation.
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Ayo-Martin AC, Kyrousi C, Di Giaimo R, Cappello S. GNG5 Controls the Number of Apical and Basal Progenitors and Alters Neuronal Migration During Cortical Development. Front Mol Biosci 2020; 7:578137. [PMID: 33330619 PMCID: PMC7673377 DOI: 10.3389/fmolb.2020.578137] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 10/12/2020] [Indexed: 12/16/2022] Open
Abstract
Cortical development is a very complex process in which any temporal or spatial alterations can give rise to a wide range of cortical malformations. Among those malformations, periventricular heterotopia (PH) is characterized by clusters of neurons that do not migrate to the correct place. Cerebral organoids derived from patients with mutations in DCHS1 and FAT4, which have been associated with PH, exhibit higher levels of GNG5 expression in a patient-specific cluster of neurons. Here we investigate the role of GNG5 during the development of the cerebral cortex in mice and human cerebral organoids. GNG5, highly expressed in progenitors and downregulated in neurons, is critical for controlling the number of apical and basal progenitors and neuronal migration. Moreover, forced expression of GNG5 recapitulates some of the alterations observed upon downregulation of Dchs1 and Fat4 in mice and human cerebral organoids derived from DCHS1 and FAT4 patients, suggesting a critical role of GNG5 in cortical development.
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Affiliation(s)
- Ane Cristina Ayo-Martin
- Max Planck Institute of Psychiatry, Munich, Germany.,International Max Planck Research School for Translational Psychiatry (IMPRS-TP), Munich, Germany
| | | | - Rossella Di Giaimo
- Max Planck Institute of Psychiatry, Munich, Germany.,Department of Biology, University of Naples Federico II, Naples, Italy
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21
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Barnett ME, Knapp BI, Bidlack JM. Unique Pharmacological Properties of the Kappa Opioid Receptor Signaling Through G αz as Shown with Bioluminescence Resonance Energy Tranfer. Mol Pharmacol 2020; 98:462-474. [PMID: 32958572 DOI: 10.1124/mol.120.119404] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Accepted: 07/16/2020] [Indexed: 12/11/2022] Open
Abstract
Opioid receptors (ORs) convert extracellular messages to signaling events by coupling to the heterotrimeric G proteins, Gα•βγ Classic pharmacological methods, such as [35S]GTPγS binding and inhibition of cyclic AMP production, allow for general opioid characterization, but they are subject to the varying endogenous Gα proteins in a given cell type. Bioluminescence resonance energy transfer (BRET) technology offers new insight by allowing the direct observation of Gα subunit-specific effects on opioid pharmacology. Using a Venus-tagged Gβγ and nanoluciferase-tagged truncated G protein receptor kinase 3, an increase in BRET signal correlated with OR activation mediated by a specific Gα protein. The magnitude of the BRET signal was normalized to the maximum response obtained with 10 µM 2-(3,4-dichlorophenyl)-N-methyl-N-[(1R,2R)-2-pyrrolidin-1-ylcyclohexyl]acetamide (U50,488) for the kappa OR (KOR). Opioids reached equilibrium with the KOR, and concentration-response curves were generated. Although the full agonists U50,488, salvinorin A, nalfurafine, and dynorphin peptides were equally efficacious regardless of the Gα subunit present, the concentration-response curves were leftward shifted when the KOR was signaling through Gαz compared with other Gαi/o subunits. In contrast, the Gα subunit distinctly affected both the efficacy and potency of partial kappa agonists, such as the benzomorphans, and the classic mu opioid antagonists, naloxone, naltrexone, and nalmefene. For example, (-)pentazocine had EC50 values of 7.3 and 110 nM and maximal stimulation values of 79% and 35% when the KOR signaled through Gαz and Gαi1, respectively. Together, these observations suggest KOR pharmacology varies based on the specific Gα subunit coupled to the KOR. SIGNIFICANCE STATEMENT: Opioid receptors couple to various heterotrimeric Gαβγ proteins to convert extracellular cues to precise intracellular events. This paper focuses on how the various inhibitory Gα subunits influence the pharmacology of full and partial agonists at the kappa opioid receptor. Using a bioluminescent assay, the efficacy and potency of kappa opioids was determined. Opioid signaling was more potent through Gαz compared with other Gα proteins. These observations suggest that Gαz may impact opioid pharmacology and cellular physiology more than previously thought.
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Affiliation(s)
- Miriam E Barnett
- Department of Pharmacology and Physiology, University of Rochester, School of Medicine and Dentistry, Rochester, New York
| | - Brian I Knapp
- Department of Pharmacology and Physiology, University of Rochester, School of Medicine and Dentistry, Rochester, New York
| | - Jean M Bidlack
- Department of Pharmacology and Physiology, University of Rochester, School of Medicine and Dentistry, Rochester, New York
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22
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Kosciuk T, Lin H. N-Myristoyltransferase as a Glycine and Lysine Myristoyltransferase in Cancer, Immunity, and Infections. ACS Chem Biol 2020; 15:1747-1758. [PMID: 32453941 DOI: 10.1021/acschembio.0c00314] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Protein myristoylation, the addition of a 14-carbon saturated acyl group, is an abundant modification implicated in biological events as diverse as development, immunity, oncogenesis, and infections. N-Myristoyltransferase (NMT) is the enzyme that catalyzes this modification. Many elegant studies have established the rules guiding the catalysis including substrate amino acid sequence requirements with the indispensable N-terminal glycine, and a co-translational mode of action. Recent advances in technology such as the development of fatty acid analogs, small molecule inhibitors, and new proteomic strategies, allowed a deeper insight into the NMT activity and function. Here we focus on discussing recent work demonstrating that NMT is also a lysine myristoyltransferase, the enzyme's regulation by a previously unnoticed solvent channel, and the mechanism of NMT regulation by protein-protein interactions. We also summarize recent findings on NMT's role in cancer, immunity, and infections and the advances in pharmacological targeting of myristoylation. Our analyses highlight opportunities for further understanding and discoveries.
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Affiliation(s)
- Tatsiana Kosciuk
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
- Department of Molecular Biology and Genetics, 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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Yang YM, Kuen DS, Chung Y, Kurose H, Kim SG. Gα 12/13 signaling in metabolic diseases. Exp Mol Med 2020; 52:896-910. [PMID: 32576930 PMCID: PMC7338450 DOI: 10.1038/s12276-020-0454-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2020] [Revised: 05/04/2020] [Accepted: 05/11/2020] [Indexed: 12/12/2022] Open
Abstract
As the key governors of diverse physiological processes, G protein-coupled receptors (GPCRs) have drawn attention as primary targets for several diseases, including diabetes and cardiovascular disease. Heterotrimeric G proteins converge signals from ~800 members of the GPCR family. Among the members of the G protein α family, the Gα12 family members comprising Gα12 and Gα13 have been referred to as gep oncogenes. Gα12/13 levels are altered in metabolic organs, including the liver and muscles, in metabolic diseases. The roles of Gα12/13 in metabolic diseases have been investigated. In this review, we highlight findings demonstrating Gα12/13 amplifying or dampening regulators of phenotype changes. We discuss the molecular basis of G protein biology in the context of posttranslational modifications to heterotrimeric G proteins and the cell signaling axis. We also highlight findings providing insights into the organ-specific, metabolic and pathological roles of G proteins in changes associated with specific cells, energy homeostasis, glucose metabolism, liver fibrosis and the immune and cardiovascular systems. This review summarizes the currently available knowledge on the importance of Gα12/13 in the physiology and pathogenesis of metabolic diseases, which is presented according to the basic understanding of their metabolic actions and underlying cellular and molecular bases. Understanding the activities of two members of a vital category of proteins called G proteins, which initiate metabolic changes when signaling molecules bind to cells, could lead to new therapies for many diseases. Researchers in South Korea and Japan, led by Sang Geon Kim at Seoul National University, review the significance of the Gα12 and Gα13 proteins in diseases characterised by significant changes in metabolism, including liver conditions and disorders of the cardiovascular and immune systems. Specific roles for the proteins have been identified by a variety of methods, including studying the effect of disabling the genes that code for them in mice. Recent insights suggest that drugs interfering with the activity of these Gα proteins might help treat many conditions in which the molecular signalling networks involving the proteins are disrupted.
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Affiliation(s)
- Yoon Mee Yang
- College of Pharmacy, Kangwon National University, Chuncheon, 24341, South Korea
| | - Da-Sol Kuen
- College of Pharmacy, Seoul National University, Seoul, 08826, South Korea
| | - Yeonseok Chung
- College of Pharmacy, Seoul National University, Seoul, 08826, South Korea
| | - Hitoshi Kurose
- Department of Pharmacology and Toxicology, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, 812-8582, Japan
| | - Sang Geon Kim
- College of Pharmacy, Seoul National University, Seoul, 08826, South Korea.
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Abstract
Glucose-induced (physiological) insulin secretion from the islet β-cell involves interplay between cationic (i.e., changes in intracellular calcium) and metabolic (i.e., generation of hydrophobic and hydrophilic second messengers) events. A large body of evidence affirms support for novel regulation, by G proteins, of specific intracellular signaling events, including actin cytoskeletal remodeling, transport of insulin-containing granules to the plasma membrane for fusion, and secretion of insulin into the circulation. This article highlights the following aspects of GPCR-G protein biology of the islet. First, it overviews our current understanding of the identity of a wide variety of G protein regulators and their modulatory roles in GPCR-G protein-effector coupling, which is requisite for optimal β-cell function under physiological conditions. Second, it describes evidence in support of novel, noncanonical, GPCR-independent mechanisms of activation of G proteins in the islet. Third, it highlights the evidence indicating that abnormalities in G protein function lead to islet β-cell dysregulation and demise under the duress of metabolic stress and diabetes. Fourth, it summarizes observations of potential beneficial effects of GPCR agonists in preventing/halting metabolic defects in the islet β-cell under various pathological conditions (e.g., metabolic stress and inflammation). Lastly, it identifies knowledge gaps and potential avenues for future research in this evolving field of translational islet biology. Published 2020. Compr Physiol 10:453-490, 2020.
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Affiliation(s)
- Anjaneyulu Kowluru
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Center for Translational Research in Diabetes, Biomedical Research Service, John D. Dingell VA Medical Center, Wayne State University, Detroit, Michigan, USA
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25
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Kosciuk T, Price IR, Zhang X, Zhu C, Johnson KN, Zhang S, Halaby SL, Komaniecki GP, Yang M, DeHart CJ, Thomas PM, Kelleher NL, Fromme JC, Lin H. NMT1 and NMT2 are lysine myristoyltransferases regulating the ARF6 GTPase cycle. Nat Commun 2020; 11:1067. [PMID: 32103017 PMCID: PMC7044312 DOI: 10.1038/s41467-020-14893-x] [Citation(s) in RCA: 61] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Accepted: 02/04/2020] [Indexed: 02/08/2023] Open
Abstract
Lysine fatty acylation in mammalian cells was discovered nearly three decades ago, yet the enzymes catalyzing it remain unknown. Unexpectedly, we find that human N-terminal glycine myristoyltransferases (NMT) 1 and 2 can efficiently myristoylate specific lysine residues. They modify ADP-ribosylation factor 6 (ARF6) on lysine 3 allowing it to remain on membranes during the GTPase cycle. We demonstrate that the NAD+-dependent deacylase SIRT2 removes the myristoyl group, and our evidence suggests that NMT prefers the GTP-bound while SIRT2 prefers the GDP-bound ARF6. This allows the lysine myrisotylation-demyristoylation cycle to couple to and promote the GTPase cycle of ARF6. Our study provides an explanation for the puzzling dissimilarity of ARF6 to other ARFs and suggests the existence of other substrates regulated by this previously unknown function of NMT. Furthermore, we identified a NMT/SIRT2-ARF6 regulatory axis, which may offer new ways to treat human diseases.
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Affiliation(s)
- Tatsiana Kosciuk
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Ian R Price
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Xiaoyu Zhang
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Chengliang Zhu
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Kayla N Johnson
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Shuai Zhang
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, USA
- Howard Hughes Medical Institute; Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Steve L Halaby
- Department of Molecular Biology and Genetics; Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Garrison P Komaniecki
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Min Yang
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Caroline J DeHart
- National Resource for Translational and Developmental Proteomics, Departments of Chemistry and Molecular Biosciences and the Feinberg School of Medicine, Northwestern University, Evanston, IL, 60208, USA
| | - Paul M Thomas
- National Resource for Translational and Developmental Proteomics, Departments of Chemistry and Molecular Biosciences and the Feinberg School of Medicine, Northwestern University, Evanston, IL, 60208, USA
| | - Neil L Kelleher
- National Resource for Translational and Developmental Proteomics, Departments of Chemistry and Molecular Biosciences and the Feinberg School of Medicine, Northwestern University, Evanston, IL, 60208, USA
| | - J Christopher Fromme
- Department of Molecular Biology and Genetics; Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Hening Lin
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, USA.
- Howard Hughes Medical Institute; Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, USA.
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26
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Blue light-triggered photochemistry and cytotoxicity of retinal. Cell Signal 2020; 69:109547. [PMID: 31982549 DOI: 10.1016/j.cellsig.2020.109547] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Revised: 01/14/2020] [Accepted: 01/22/2020] [Indexed: 01/08/2023]
Abstract
The chemical- and photo- toxicity of chromophore retinal on cells have long been debated. Although we recently showed that retinal and blue light exposure interrupt cellular signaling, a comprehensive study examining molecular underpinnings of this perturbation and its consequences to cellular fate is lacking. Here, we report molecular evidence for blue light excited-retinal induced oxidative damage of polyunsaturated lipid anchors in membrane-interacting signaling molecules and DNA damage in cells using live-cell imaging and in vitro experimentation. The incurred molecular damage irreversibly disrupted subcellular localization of these molecules, a crucial criterion for their signaling. We further show retinal accumulation in lipid-bilayers of cell membranes could enhance the lifetime of retinal in cells. Comparative response-signatures suggest that retinal triggers reactions upon photoexcitation similar to photodynamic therapy agents and generate reactive oxygen species in cells. Additionally, data also shows that exposing retinal-containing cells to sunlight induces substantial cytotoxicity. Collectively, our results explain a likely in vivo mechanism and reaction conditions under which bio-available retinal in physiological light conditions damages cells.
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27
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Pinner AL, Mueller TM, Alganem K, McCullumsmith R, Meador-Woodruff JH. Protein expression of prenyltransferase subunits in postmortem schizophrenia dorsolateral prefrontal cortex. Transl Psychiatry 2020; 10:3. [PMID: 32066669 PMCID: PMC7026430 DOI: 10.1038/s41398-019-0610-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Revised: 09/09/2019] [Accepted: 10/03/2019] [Indexed: 12/22/2022] Open
Abstract
The pathophysiology of schizophrenia includes altered neurotransmission, dysregulated intracellular signaling pathway activity, and abnormal dendritic morphology that contribute to deficits of synaptic plasticity in the disorder. These processes all require dynamic protein-protein interactions at cell membranes. Lipid modifications target proteins to membranes by increasing substrate hydrophobicity by the addition of a fatty acid or isoprenyl moiety, and recent evidence suggests that dysregulated posttranslational lipid modifications may play a role in multiple neuropsychiatric disorders, including schizophrenia. Consistent with these emerging findings, we have recently reported decreased protein S-palmitoylation in schizophrenia. Protein prenylation is a lipid modification that occurs upstream of S-palmitoylation on many protein substrates, facilitating membrane localization and activity of key intracellular signaling proteins. Accordingly, we hypothesized that, in addition to palmitoylation, protein prenylation may be abnormal in schizophrenia. To test this, we assayed protein expression of the five prenyltransferase subunits (FNTA, FNTB, PGGT1B, RABGGTA, and RABGGTB) in postmortem dorsolateral prefrontal cortex from patients with schizophrenia and paired comparison subjects (n = 13 pairs). We found decreased levels of FNTA (14%), PGGT1B (13%), and RABGGTB (8%) in schizophrenia. To determine whether upstream or downstream factors may be driving these changes, we also assayed protein expression of the isoprenoid synthases FDPS and GGPS1 and prenylation-dependent processing enzymes RCE and ICMT. We found these upstream and downstream enzymes to have normal protein expression. To rule out effects from chronic antipsychotic treatment, we assayed FNTA, PGGT1B, and RABGGTB in the cortex from rats treated long-term with haloperidol decanoate and found no change in the expression of these proteins. Given the role prenylation plays in localization of key signaling proteins found at the synapse, these data offer a potential mechanism underlying abnormal protein-protein interactions and protein localization in schizophrenia.
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Affiliation(s)
- Anita L Pinner
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, Birmingham, AL, 35294-0021, USA.
| | - Toni M Mueller
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, Birmingham, AL, 35294-0021, USA
| | - Khaled Alganem
- Department of Neurosciences, University of Toledo, Toledo, OH, 43614-2598, USA
| | | | - James H Meador-Woodruff
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, Birmingham, AL, 35294-0021, USA
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28
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Petersen EN, Pavel MA, Wang H, Hansen SB. Disruption of palmitate-mediated localization; a shared pathway of force and anesthetic activation of TREK-1 channels. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2020; 1862:183091. [PMID: 31672538 PMCID: PMC6907892 DOI: 10.1016/j.bbamem.2019.183091] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Revised: 09/15/2019] [Accepted: 09/17/2019] [Indexed: 12/22/2022]
Abstract
TWIK related K+ channel (TREK-1) is a mechano- and anesthetic sensitive channel that when activated attenuates pain and causes anesthesia. Recently the enzyme phospholipase D2 (PLD2) was shown to bind to the channel and generate a local high concentration of phosphatidic acid (PA), an anionic signaling lipid that gates TREK-1. In a biological membrane, the cell harnesses lipid heterogeneity (lipid compartments) to control gating of TREK-1 using palmitate-mediated localization of PLD2. Here we discuss the ability of mechanical force and anesthetics to disrupt palmitate-mediated localization of PLD2 giving rise to TREK-1's mechano- and anesthetic-sensitive properties. The likely consequences of this indirect lipid-based mechanism of activation are discussed in terms of a putative model for excitatory and inhibitory mechano-effectors and anesthetic sensitive ion channels in a biological context. Lastly, we discuss the ability of locally generated PA to reach mM concentrations near TREK-1 and the biophysics of localized signaling. Palmitate-mediated localization of PLD2 emerges as a central control mechanism of TREK-1 responding to mechanical force and anesthetic action. This article is part of a Special Issue entitled: Molecular biophysics of membranes and membrane proteins.
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Affiliation(s)
- E Nicholas Petersen
- Department of Molecular Medicine, The Scripps Research Institute, Jupiter, FL 33458, USA; Department of Neuroscience, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Mahmud Arif Pavel
- Department of Molecular Medicine, The Scripps Research Institute, Jupiter, FL 33458, USA; Department of Neuroscience, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Hao Wang
- Department of Molecular Medicine, The Scripps Research Institute, Jupiter, FL 33458, USA; Department of Neuroscience, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Scott B Hansen
- Department of Molecular Medicine, The Scripps Research Institute, Jupiter, FL 33458, USA; Department of Neuroscience, The Scripps Research Institute, Jupiter, FL 33458, USA.
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29
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Jackson L, Qifti A, Pearce KM, Scarlata S. Regulation of bifunctional proteins in cells: Lessons from the phospholipase Cβ/G protein pathway. Protein Sci 2019; 29:1258-1268. [PMID: 31867822 DOI: 10.1002/pro.3809] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Revised: 12/17/2019] [Accepted: 12/18/2019] [Indexed: 12/14/2022]
Abstract
Some proteins can serve multiple functions depending on different cellular conditions. An example of a bifunctional protein is inositide-specific mammalian phospholipase Cβ (PLCβ). PLCβ is activated by G proteins in response to hormones and neurotransmitters to increase intracellular calcium. Recently, alternate cellular function(s) of PLCβ have become uncovered. However, the conditions that allow these different functions to be operative are unclear. Like many mammalian proteins, PLCβ has a conserved catalytic core along with several regulatory domains. These domains modulate the intensity and duration of calcium signals in response to external sensory information, and allow this enzyme to inhibit protein translation in a noncatalytic manner. In this review, we first describe PLCβ's cellular functions and regulation of the switching between these functions, and then discuss the thermodynamic considerations that offer insight into how cells manage multiple and competitive associations allowing them to rapidly shift between functional states.
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Affiliation(s)
- Lela Jackson
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, Worcester, Massachusetts
| | - Androniqi Qifti
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, Worcester, Massachusetts
| | - Katherine M Pearce
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, Worcester, Massachusetts
| | - Suzanne Scarlata
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, Worcester, Massachusetts
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30
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Smrcka AV, Fisher I. G-protein βγ subunits as multi-functional scaffolds and transducers in G-protein-coupled receptor signaling. Cell Mol Life Sci 2019; 76:4447-4459. [PMID: 31435698 PMCID: PMC6842434 DOI: 10.1007/s00018-019-03275-2] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Revised: 08/05/2019] [Accepted: 08/12/2019] [Indexed: 02/08/2023]
Abstract
G-protein βγ subunits are key participants in G-protein signaling. These subunits facilitate interactions between receptors and G proteins that are critical for the G protein activation cycle at the plasma membrane. In addition, they play roles in directly transducing signals to an ever expanding range of downstream targets, including integral membrane and cytosolic proteins. Emerging data indicate that Gβγ may play additional roles at intracellular compartments including endosomes, the Golgi apparatus, and the nucleus. Here, we discuss the molecular and structural basis for their ability to coordinate this wide range of cellular activities.
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Affiliation(s)
- Alan V Smrcka
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI, 48104, USA.
| | - Isaac Fisher
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI, 48104, USA
- Department of Pharmacology and Physiology, University of Rochester School of Medicine, Rochester, NY, 14629, USA
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31
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Fert-Bober J, Murray CI, Parker SJ, Van Eyk JE. Precision Profiling of the Cardiovascular Post-Translationally Modified Proteome: Where There Is a Will, There Is a Way. Circ Res 2019; 122:1221-1237. [PMID: 29700069 DOI: 10.1161/circresaha.118.310966] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
There is an exponential increase in biological complexity as initial gene transcripts are spliced, translated into amino acid sequence, and post-translationally modified. Each protein can exist as multiple chemical or sequence-specific proteoforms, and each has the potential to be a critical mediator of a physiological or pathophysiological signaling cascade. Here, we provide an overview of how different proteoforms come about in biological systems and how they are most commonly measured using mass spectrometry-based proteomics and bioinformatics. Our goal is to present this information at a level accessible to every scientist interested in mass spectrometry and its application to proteome profiling. We will specifically discuss recent data linking various protein post-translational modifications to cardiovascular disease and conclude with a discussion for enablement and democratization of proteomics across the cardiovascular and scientific community. The aim is to inform and inspire the readership to explore a larger breadth of proteoform, particularity post-translational modifications, related to their particular areas of expertise in cardiovascular physiology.
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Affiliation(s)
- Justyna Fert-Bober
- From the Advanced Clinical BioSystems Research Institute, Smidt Heart Institute, Department of Medicine, Cedars Sinai Medical Center, Los Angeles, CA
| | - Christopher I Murray
- From the Advanced Clinical BioSystems Research Institute, Smidt Heart Institute, Department of Medicine, Cedars Sinai Medical Center, Los Angeles, CA
| | - Sarah J Parker
- From the Advanced Clinical BioSystems Research Institute, Smidt Heart Institute, Department of Medicine, Cedars Sinai Medical Center, Los Angeles, CA.
| | - Jennifer E Van Eyk
- From the Advanced Clinical BioSystems Research Institute, Smidt Heart Institute, Department of Medicine, Cedars Sinai Medical Center, Los Angeles, CA
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32
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Effects of Post-translational Modifications on Membrane Localization and Signaling of Prostanoid GPCR-G Protein Complexes and the Role of Hypoxia. J Membr Biol 2019; 252:509-526. [PMID: 31485700 DOI: 10.1007/s00232-019-00091-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Accepted: 08/17/2019] [Indexed: 02/07/2023]
Abstract
G protein-coupled receptors (GPCRs) play a pivotal role in the adaptive responses to cellular stresses such as hypoxia. In addition to influencing cellular gene expression profiles, hypoxic microenvironments can perturb membrane protein localization, altering GPCR effector scaffolding and altering downstream signaling. Studies using proteomics approaches have revealed significant regulation of GPCR and G proteins by their state of post-translational modification. The aim of this review is to examine the effects of post-translational modifications on membrane localization and signaling of GPCR-G protein complexes, with an emphasis on vascular prostanoid receptors, and to highlight what is known about the effect of cellular hypoxia on these mechanisms. Understanding post-translational modifications of protein targets will help to define GPCR targets in treatment of disease, and to inform research into mechanisms of hypoxic cellular responses.
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33
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Saito M, Cui L, Hirano M, Li G, Yanagisawa T, Sato T, Sukegawa J. Activity of Adenylyl Cyclase Type 6 Is Suppressed by Direct Binding of the Cytoskeletal Protein 4.1G. Mol Pharmacol 2019; 96:441-451. [PMID: 31383768 DOI: 10.1124/mol.119.116426] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Accepted: 07/30/2019] [Indexed: 11/22/2022] Open
Abstract
The G protein-coupled receptor (GPCR) signaling pathways mediated by trimeric G proteins have been extensively elucidated, but their associated regulatory mechanisms remain unclear. Parathyroid hormone (PTH)/PTH-related protein receptor (PTHR) is a GPCR coupled with Gs and Gq Gs activates adenylyl cyclases (ACs), which produces cAMP to regulate various cell fates. We previously showed that cell surface expression of PTHR was increased by its direct interaction with a subcortical cytoskeletal protein, 4.1G, whereas PTHR-mediated Gs/AC/cAMP signaling was suppressed by 4.1G through an unknown mechanism in human embryonic kidney (HEK)293 cells. In the present study, we found that AC type 6 (AC6), one of the major ACs activated downstream of PTHR, interacts with 4.1G in HEK293 cells, and the N-terminus of AC6 (AC6-N) directly and selectively binds to the 4.1/ezrin/radixin/moesin (FERM) domain of 4.1G (4.1G-FERM) in vitro. AC6-N was distributed at the plasma membrane, which was disturbed by knockdown of 4.1G. An AC6-N mutant, AC6-N-3A, in which three consecutive arginine residues are mutated to alanine residues, altered both binding to 4.1G-FERM and its plasma membrane distribution in vivo. Further, we overexpressed AC6-N to competitively inhibit the interaction of endogenous AC6 and 4.1G in cells. cAMP production induced by forskolin, an adenylyl cyclase activator, and PTH-(1-34) was enhanced by AC6-N expression and 4.1G-knockdown. In contrast, AC6-N-3A had no impact on forskolin- and PTH-(1-34)-induced cAMP productions. These data provide a novel regulatory mechanism that AC6 activity is suppressed by the direct binding of 4.1G to AC6-N, resulting in attenuation of PTHR-mediated Gs/AC6/cAMP signaling.
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Affiliation(s)
- Masaki Saito
- Department of Molecular Pharmacology, Tohoku University School of Medicine, Sendai, Miyagi, Japan (M.S., L.C., M.H., G.L., T.Y., T.S., J.S.); Department of Human Health and Nutrition, Shokei Gakuin University, Natori, Miyagi, Japan (M.H., J.S.); and Faculty of Health Sciences, Tohoku Fukushi University, Sendai, Miyagi, Japan (T.Y.)
| | - Linran Cui
- Department of Molecular Pharmacology, Tohoku University School of Medicine, Sendai, Miyagi, Japan (M.S., L.C., M.H., G.L., T.Y., T.S., J.S.); Department of Human Health and Nutrition, Shokei Gakuin University, Natori, Miyagi, Japan (M.H., J.S.); and Faculty of Health Sciences, Tohoku Fukushi University, Sendai, Miyagi, Japan (T.Y.)
| | - Marina Hirano
- Department of Molecular Pharmacology, Tohoku University School of Medicine, Sendai, Miyagi, Japan (M.S., L.C., M.H., G.L., T.Y., T.S., J.S.); Department of Human Health and Nutrition, Shokei Gakuin University, Natori, Miyagi, Japan (M.H., J.S.); and Faculty of Health Sciences, Tohoku Fukushi University, Sendai, Miyagi, Japan (T.Y.)
| | - Guanjie Li
- Department of Molecular Pharmacology, Tohoku University School of Medicine, Sendai, Miyagi, Japan (M.S., L.C., M.H., G.L., T.Y., T.S., J.S.); Department of Human Health and Nutrition, Shokei Gakuin University, Natori, Miyagi, Japan (M.H., J.S.); and Faculty of Health Sciences, Tohoku Fukushi University, Sendai, Miyagi, Japan (T.Y.)
| | - Teruyuki Yanagisawa
- Department of Molecular Pharmacology, Tohoku University School of Medicine, Sendai, Miyagi, Japan (M.S., L.C., M.H., G.L., T.Y., T.S., J.S.); Department of Human Health and Nutrition, Shokei Gakuin University, Natori, Miyagi, Japan (M.H., J.S.); and Faculty of Health Sciences, Tohoku Fukushi University, Sendai, Miyagi, Japan (T.Y.)
| | - Takeya Sato
- Department of Molecular Pharmacology, Tohoku University School of Medicine, Sendai, Miyagi, Japan (M.S., L.C., M.H., G.L., T.Y., T.S., J.S.); Department of Human Health and Nutrition, Shokei Gakuin University, Natori, Miyagi, Japan (M.H., J.S.); and Faculty of Health Sciences, Tohoku Fukushi University, Sendai, Miyagi, Japan (T.Y.)
| | - Jun Sukegawa
- Department of Molecular Pharmacology, Tohoku University School of Medicine, Sendai, Miyagi, Japan (M.S., L.C., M.H., G.L., T.Y., T.S., J.S.); Department of Human Health and Nutrition, Shokei Gakuin University, Natori, Miyagi, Japan (M.H., J.S.); and Faculty of Health Sciences, Tohoku Fukushi University, Sendai, Miyagi, Japan (T.Y.)
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34
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Tennakoon M, Kankanamge D, Senarath K, Fasih Z, Karunarathne A. Statins Perturb G βγ Signaling and Cell Behavior in a G γ Subtype Dependent Manner. Mol Pharmacol 2019; 95:361-375. [PMID: 30765461 DOI: 10.1124/mol.118.114710] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2018] [Accepted: 01/25/2019] [Indexed: 01/08/2023] Open
Abstract
Guanine nucleotide-binding proteins (G proteins) facilitate the transduction of external signals to the cell interior, regulate most eukaryotic signaling, and thus have become crucial disease drivers. G proteins largely function at the inner leaflet of the plasma membrane (PM) using covalently attached lipid anchors. Both small monomeric and heterotrimeric G proteins are primarily prenylated, either with a 15-carbon farnesyl or a 20-carbon geranylgeranyl polyunsaturated lipid. The mevalonate [3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase] pathway synthesizes lipids for G-protein prenylation. It is also the source of the precursor lipids for many biomolecules, including cholesterol. Consequently, the rate-limiting enzymes of the mevalonate pathway are major targets for cholesterol-lowering medications and anticancer drug development. Although prenylated G protein γ (Gγ) is essential for G protein-coupled receptor (GPCR)-mediated signaling, how mevalonate pathway inhibitors, statins, influence subcellular distribution of Gβγ dimer and Gαβγ heterotrimer, as well as their signaling upon GPCR activation, is poorly understood. The present study shows that clinically used statins not only significantly disrupt PM localization of Gβγ but also perturb GPCR-G protein signaling and associated cell behaviors. The results also demonstrate that the efficiency of prenylation inhibition by statins is Gγ subtype-dependent and is more effective toward farnesylated Gγ types. Since Gγ is required for Gβγ signaling and shows a cell- and tissue-specific subtype distribution, the present study can help understand the mechanisms underlying clinical outcomes of statin use in patients. This work also reveals the potential of statins as clinically usable drugs to control selected GPCR-G protein signaling.
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Affiliation(s)
- Mithila Tennakoon
- Department of Chemistry and Biochemistry, The University of Toledo, Toledo, Ohio
| | - Dinesh Kankanamge
- Department of Chemistry and Biochemistry, The University of Toledo, Toledo, Ohio
| | - Kanishka Senarath
- Department of Chemistry and Biochemistry, The University of Toledo, Toledo, Ohio
| | - Zehra Fasih
- Department of Chemistry and Biochemistry, The University of Toledo, Toledo, Ohio
| | - Ajith Karunarathne
- Department of Chemistry and Biochemistry, The University of Toledo, Toledo, Ohio
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35
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Mutual action by Gγ and Gβ for optimal activation of GIRK channels in a channel subunit-specific manner. Sci Rep 2019; 9:508. [PMID: 30679535 PMCID: PMC6346094 DOI: 10.1038/s41598-018-36833-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Accepted: 11/29/2018] [Indexed: 01/06/2023] Open
Abstract
The tetrameric G protein-gated K+ channels (GIRKs) mediate inhibitory effects of neurotransmitters that activate Gi/o-coupled receptors. GIRKs are activated by binding of the Gβγ dimer, via contacts with Gβ. Gγ underlies membrane targeting of Gβγ, but has not been implicated in channel gating. We observed that, in Xenopus oocytes, expression of Gγ alone activated homotetrameric GIRK1* and heterotetrameric GIRK1/3 channels, without affecting the surface expression of GIRK or Gβ. Gγ and Gβ acted interdependently: the effect of Gγ required the presence of ambient Gβ and was enhanced by low doses of coexpressed Gβ, whereas excess of either Gβ or Gγ imparted suboptimal activation, possibly by sequestering the other subunit “away” from the channel. The unique distal C-terminus of GIRK1, G1-dCT, was important but insufficient for Gγ action. Notably, GIRK2 and GIRK1/2 were not activated by Gγ. Our results suggest that Gγ regulates GIRK1* and GIRK1/3 channel’s gating, aiding Gβ to trigger the channel’s opening. We hypothesize that Gγ helps to relax the inhibitory effect of a gating element (“lock”) encompassed, in part, by the G1-dCT; GIRK2 acts to occlude the effect of Gγ, either by setting in motion the same mechanism as Gγ, or by triggering an opposing gating effect.
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36
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Koelle MR. Neurotransmitter signaling through heterotrimeric G proteins: insights from studies in C. elegans. WORMBOOK : THE ONLINE REVIEW OF C. ELEGANS BIOLOGY 2018; 2018:1-52. [PMID: 26937633 PMCID: PMC5010795 DOI: 10.1895/wormbook.1.75.2] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Neurotransmitters signal via G protein coupled receptors (GPCRs) to modulate activity of neurons and muscles. C. elegans has ∼150 G protein coupled neuropeptide receptor homologs and 28 additional GPCRs for small-molecule neurotransmitters. Genetic studies in C. elegans demonstrate that neurotransmitters diffuse far from their release sites to activate GPCRs on distant cells. Individual receptor types are expressed on limited numbers of cells and thus can provide very specific regulation of an individual neural circuit and behavior. G protein coupled neurotransmitter receptors signal principally via the three types of heterotrimeric G proteins defined by the G alpha subunits Gαo, Gαq, and Gαs. Each of these G alpha proteins is found in all neurons plus some muscles. Gαo and Gαq signaling inhibit and activate neurotransmitter release, respectively. Gαs signaling, like Gαq signaling, promotes neurotransmitter release. Many details of the signaling mechanisms downstream of Gαq and Gαs have been delineated and are consistent with those of their mammalian orthologs. The details of the signaling mechanism downstream of Gαo remain a mystery. Forward genetic screens in C. elegans have identified new molecular components of neural G protein signaling mechanisms, including Regulators of G protein Signaling (RGS proteins) that inhibit signaling, a new Gαq effector (the Trio RhoGEF domain), and the RIC-8 protein that is required for neuronal Gα signaling. A model is presented in which G proteins sum up the variety of neuromodulator signals that impinge on a neuron to calculate its appropriate output level.
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Affiliation(s)
- Michael R Koelle
- Department of Molecular Biophysics & Biochemistry, Yale University, New Haven CT 06520 USA
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Spears RJ, Brabham RL, Budhadev D, Keenan T, McKenna S, Walton J, Brannigan JA, Brzozowski AM, Wilkinson AJ, Plevin M, Fascione MA. Site-selective C-C modification of proteins at neutral pH using organocatalyst-mediated cross aldol ligations. Chem Sci 2018; 9:5585-5593. [PMID: 30061990 PMCID: PMC6049525 DOI: 10.1039/c8sc01617h] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Accepted: 05/31/2018] [Indexed: 12/30/2022] Open
Abstract
An organocatalyst-mediated protein aldol ligation (OPAL) affords C–C linked bioconjugates at neutral pH.
The bioconjugation of proteins with small molecules has proved an invaluable strategy for probing and perturbing biological mechanisms. The general use of chemical methods for protein functionalisation can be limited however by the requirement for complicated reaction partners to be present in large excess, and harsh conditions which are incompatible with many protein scaffolds. Herein we describe a site-selective organocatalyst-mediated protein aldol ligation (OPAL) that affords stable carbon–carbon linked bioconjugates at neutral pH. OPAL enables rapid modification of proteins using simple aldehyde probes in minimal excess, and is utilised here in the affinity tagging of proteins in cell lysate. Furthermore we demonstrate that the β-hydroxy aldehyde OPAL product can be functionalised again at neutral pH in a tandem organocatalyst-mediated oxime ligation. This tandem strategy is showcased in the ‘chemical mimicry’ of a previously inaccessible natural dual post-translationally modified protein integral to the pathogenesis of the neglected tropical disease Leishmaniasis.
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Affiliation(s)
- Richard J Spears
- Department of Chemistry , University of York , York , YO10 5DD , UK .
| | - Robin L Brabham
- Department of Chemistry , University of York , York , YO10 5DD , UK .
| | - Darshita Budhadev
- Department of Chemistry , University of York , York , YO10 5DD , UK .
| | - Tessa Keenan
- Department of Chemistry , University of York , York , YO10 5DD , UK .
| | - Sophie McKenna
- Department of Chemistry , University of York , York , YO10 5DD , UK .
| | - Julia Walton
- Department of Chemistry , University of York , York , YO10 5DD , UK .
| | - James A Brannigan
- Department of Chemistry , University of York , York , YO10 5DD , UK .
| | | | | | - Michael Plevin
- Department of Biology , University of York , York , YO10 5DD , UK
| | - Martin A Fascione
- Department of Chemistry , University of York , York , YO10 5DD , UK .
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Senarath K, Kankanamge D, Samaradivakara S, Ratnayake K, Tennakoon M, Karunarathne A. Regulation of G Protein βγ Signaling. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2018; 339:133-191. [PMID: 29776603 DOI: 10.1016/bs.ircmb.2018.02.008] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Heterotrimeric guanine nucleotide-binding proteins (G proteins) deliver external signals to the cell interior, upon activation by the external signal stimulated G protein-coupled receptors (GPCRs).While the activated GPCRs control several pathways independently, activated G proteins control the vast majority of cellular and physiological functions, ranging from vision to cardiovascular homeostasis. Activated GPCRs dissociate GαGDPβγ heterotrimer into GαGTP and free Gβγ. Earlier, GαGTP was recognized as the primary signal transducer of the pathway and Gβγ as a passive signaling modality that facilitates the activity of Gα. However, Gβγ later found to regulate more number of pathways than GαGTP does. Once liberated from the heterotrimer, free Gβγ interacts and activates a diverse range of signaling regulators including kinases, lipases, GTPases, and ion channels, and it does not require any posttranslation modifications. Gβγ family consists of 48 members, which show cell- and tissue-specific expressions, and recent reports show that cells employ the subtype diversity in Gβγ to achieve desired signaling outcomes. In addition to activated GPCRs, which induce free Gβγ generation and the rate of GTP hydrolysis in Gα, which sequester Gβγ in the heterotrimer, terminating Gβγ signaling, additional regulatory mechanisms exist to regulate Gβγ activity. In this chapter, we discuss structure and function, subtype diversity and its significance in signaling regulation, effector activation, regulatory mechanisms as well as the disease relevance of Gβγ in eukaryotes.
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Mastop M, Reinhard NR, Zuconelli CR, Terwey F, Gadella TWJ, van Unen J, Adjobo-Hermans MJW, Goedhart J. A FRET-based biosensor for measuring Gα13 activation in single cells. PLoS One 2018; 13:e0193705. [PMID: 29505611 PMCID: PMC5837189 DOI: 10.1371/journal.pone.0193705] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Accepted: 02/19/2018] [Indexed: 12/22/2022] Open
Abstract
Förster Resonance Energy Transfer (FRET) provides a way to directly observe the activation of heterotrimeric G-proteins by G-protein coupled receptors (GPCRs). To this end, FRET based biosensors are made, employing heterotrimeric G-protein subunits tagged with fluorescent proteins. These FRET based biosensors complement existing, indirect, ways to observe GPCR activation. Here we report on the insertion of mTurquoise2 at several sites in the human Gα13 subunit, aiming to develop a FRET-based Gα13 activation biosensor. Three fluorescently tagged Gα13 variants were found to be functional based on i) plasma membrane localization and ii) ability to recruit p115-RhoGEF upon activation of the LPA2 receptor. The tagged Gα13 subunits were used as FRET donor and combined with cp173Venus fused to the Gγ2 subunit, as the acceptor. We constructed Gα13 biosensors by generating a single plasmid that produces Gα13-mTurquoise2, Gβ1 and cp173Venus-Gγ2. The Gα13 activation biosensors showed a rapid and robust response when used in primary human endothelial cells that were exposed to thrombin, triggering endogenous protease activated receptors (PARs). This response was efficiently inhibited by the RGS domain of p115-RhoGEF and from the biosensor data we inferred that this is due to GAP activity. Finally, we demonstrated that the Gα13 sensor can be used to dissect heterotrimeric G-protein coupling efficiency in single living cells. We conclude that the Gα13 biosensor is a valuable tool for live-cell measurements that probe spatiotemporal aspects of Gα13 activation.
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Affiliation(s)
- Marieke Mastop
- Swammerdam Institute for Life Sciences, Section of Molecular Cytology, van Leeuwenhoek Centre for Advanced Microscopy, University of Amsterdam, Amsterdam, The Netherlands
| | - Nathalie R. Reinhard
- Swammerdam Institute for Life Sciences, Section of Molecular Cytology, van Leeuwenhoek Centre for Advanced Microscopy, University of Amsterdam, Amsterdam, The Netherlands
| | - Cristiane R. Zuconelli
- Department of Biochemistry, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Fenna Terwey
- Swammerdam Institute for Life Sciences, Section of Molecular Cytology, van Leeuwenhoek Centre for Advanced Microscopy, University of Amsterdam, Amsterdam, The Netherlands
| | - Theodorus W. J. Gadella
- Swammerdam Institute for Life Sciences, Section of Molecular Cytology, van Leeuwenhoek Centre for Advanced Microscopy, University of Amsterdam, Amsterdam, The Netherlands
| | - Jakobus van Unen
- Swammerdam Institute for Life Sciences, Section of Molecular Cytology, van Leeuwenhoek Centre for Advanced Microscopy, University of Amsterdam, Amsterdam, The Netherlands
| | - Merel J. W. Adjobo-Hermans
- Department of Biochemistry, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Joachim Goedhart
- Swammerdam Institute for Life Sciences, Section of Molecular Cytology, van Leeuwenhoek Centre for Advanced Microscopy, University of Amsterdam, Amsterdam, The Netherlands
- * E-mail:
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Abstract
Activation of G protein-coupled receptors (GPCRs) initiates conformational shifts that trigger interaction with a specific G-protein subtype from a structurally homologous set. A major unsolved problem is the mechanism by which this selectivity is achieved. Structures of GPCR–G protein complexes so far fail to reveal the origin of selectivity because they all involve one G-protein subtype (Gs). In this work, we report a structural model of the activated GPCR rhodopsin in complex with another G-protein subtype (Gi) derived from intermolecular distance mapping with DEER-EPR and refinement with modeling. Comparison of the model with structures of complexes involving Gs reveals distinct GPCR–G protein-binding modes, the differences of which suggest key features of the structural selectivity filter. More than two decades ago, the activation mechanism for the membrane-bound photoreceptor and prototypical G protein-coupled receptor (GPCR) rhodopsin was uncovered. Upon light-induced changes in ligand–receptor interaction, movement of specific transmembrane helices within the receptor opens a crevice at the cytoplasmic surface, allowing for coupling of heterotrimeric guanine nucleotide-binding proteins (G proteins). The general features of this activation mechanism are conserved across the GPCR superfamily. Nevertheless, GPCRs have selectivity for distinct G-protein family members, but the mechanism of selectivity remains elusive. Structures of GPCRs in complex with the stimulatory G protein, Gs, and an accessory nanobody to stabilize the complex have been reported, providing information on the intermolecular interactions. However, to reveal the structural selectivity filters, it will be necessary to determine GPCR–G protein structures involving other G-protein subtypes. In addition, it is important to obtain structures in the absence of a nanobody that may influence the structure. Here, we present a model for a rhodopsin–G protein complex derived from intermolecular distance constraints between the activated receptor and the inhibitory G protein, Gi, using electron paramagnetic resonance spectroscopy and spin-labeling methodologies. Molecular dynamics simulations demonstrated the overall stability of the modeled complex. In the rhodopsin–Gi complex, Gi engages rhodopsin in a manner distinct from previous GPCR–Gs structures, providing insight into specificity determinants.
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Brooks C, Murphy J, Belcastro M, Heller D, Kolandaivelu S, Kisselev O, Sokolov M. Farnesylation of the Transducin G Protein Gamma Subunit Is a Prerequisite for Its Ciliary Targeting in Rod Photoreceptors. Front Mol Neurosci 2018; 11:16. [PMID: 29410614 PMCID: PMC5787109 DOI: 10.3389/fnmol.2018.00016] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Accepted: 01/10/2018] [Indexed: 12/26/2022] Open
Abstract
Primary cilia are microtubule-based organelles, which protrude from the plasma membrane and receive a wide range of extracellular signals. Various cilia use G protein-coupled receptors (GPCRs) for the detection of these signals. For instance, vertebrate rod photoreceptors use their cilia (also called outer segments) as antennae detecting photons by GPCR rhodopsin. Rhodopsin recognizes incoming light and activates its G protein, transducin, which is composed of three subunits α, β, and γ. Similar to all G protein γ subunits, the transducin Gγ1 subunit undergoes C-terminal prenylation resulting in the addition of an isoprenoid farnesyl; however, the significance of this posttranslational modification is unclear. To study the role of the farnesyl group, we genetically introduced a mutant Gγ1 that lacked the prenylation site into the retinal photoreceptors of mice. The biochemical and physiological analyses of these mice revealed that mutant Gγ1 dimerizes with the endogenous transducin Gβ1 subunit and that the resulting Gβγ dimers display reduced hydrophobicity. Although mutant Gβγ dimers could form a heterotrimeric G protein, they could not mediate phototransduction. This deficiency was due to a strong exclusion of non-farnesylated Gβγ complexes from the cilia (rod outer segments). Our results provide the first evidence that farnesylation is required for trafficking of G-protein βγ subunits to the cilium of rod photoreceptors.
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Affiliation(s)
- Celine Brooks
- Department of Ophthalmology, West Virginia University, Morgantown, WV, United States
| | - Joseph Murphy
- Department of Ophthalmology, West Virginia University, Morgantown, WV, United States
| | | | - Daniel Heller
- Department of Ophthalmology, West Virginia University, Morgantown, WV, United States
| | | | - Oleg Kisselev
- Department of Ophthalmology, Saint Louis University, St. Louis, MO, United States
| | - Maxim Sokolov
- Department of Ophthalmology, West Virginia University, Morgantown, WV, United States
- Department of Biochemistry, West Virginia University, Morgantown, WV, United States
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Cholesterol overload in the liver aggravates oxidative stress-mediated DNA damage and accelerates hepatocarcinogenesis. Oncotarget 2017; 8:104136-104148. [PMID: 29262627 PMCID: PMC5732793 DOI: 10.18632/oncotarget.22024] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2017] [Accepted: 09/20/2017] [Indexed: 12/15/2022] Open
Abstract
Primary liver cancers represent the second leading cause of cancer-related deaths worldwide. Diverse etiological factors include chronic viral hepatitis, aflatoxin and alcohol exposure as well as aberrant liver lipid overload. Cholesterol has been identified as a key inducer of metabolic impairment, oxidative stress and promoter of cellular dysfunction. The aim of this work was to address the oxidative stress-mediated DNA damage induced by cholesterol overload, and its role in the development of hepatocellular carcinoma. C57BL/6 male mice were fed with a high cholesterol diet, followed by a single dose of N-diethylnitrosamine (DEN, 10 μg/g, ip). Reactive oxygen species generation, DNA oxidation, antioxidant and DNA repair proteins were analyzed at different time points. Diet-induced cholesterol overload caused enhanced oxidative DNA damage in the liver and was associated with a decrease in key DNA repair genes as early as 7 days. Interestingly, we found a cell survival response, induced by cholesterol, judged by a decrement in Bax to Bcl2 ratio. Importantly, N-acetyl-cysteine supplementation significantly prevented DNA oxidation damage. Furthermore, at 8 months after DEN administration, tumor growth was significantly enhanced in mice under cholesterol diet in comparison to control animals. Together, these results suggest that cholesterol overload exerts an oxidative stress-mediated effects and promotes the development of liver cancer.
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Schattauer SS, Land BB, Reichard KL, Abraham AD, Burgeno LM, Kuhar JR, Phillips PEM, Ong SE, Chavkin C. Peroxiredoxin 6 mediates Gαi protein-coupled receptor inactivation by cJun kinase. Nat Commun 2017; 8:743. [PMID: 28963507 PMCID: PMC5622097 DOI: 10.1038/s41467-017-00791-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Accepted: 07/27/2017] [Indexed: 12/21/2022] Open
Abstract
Inactivation of opioid receptors limits the therapeutic efficacy of morphine-like analgesics and mediates the long duration of kappa opioid antidepressants by an uncharacterized, arrestin-independent mechanism. Here we use an iterative, discovery-based proteomic approach to show that following opioid administration, peroxiredoxin 6 (PRDX6) is recruited to the opioid receptor complex by c-Jun N-terminal kinase (JNK) phosphorylation. PRDX6 activation generates reactive oxygen species via NADPH oxidase, reducing the palmitoylation of receptor-associated Gαi in a JNK-dependent manner. Selective inhibition of PRDX6 blocks Gαi depalmitoylation, prevents the enhanced receptor G-protein association and blocks acute analgesic tolerance to morphine and kappa opioid receptor inactivation in vivo. Opioid stimulation of JNK also inactivates dopamine D2 receptors in a PRDX6-dependent manner. We show that the loss of this lipid modification distorts the receptor G-protein association, thereby preventing agonist-induced guanine nucleotide exchange. These findings establish JNK-dependent PRDX6 recruitment and oxidation-induced Gαi depalmitoylation as an additional mechanism of Gαi-G-protein-coupled receptor inactivation. Opioid receptors are important modulators of nociceptive pain. Here the authors show that opioid receptor activation recruits peroxiredoxin 6 (PRDX6) to the receptor-Gαi complex by c-Jun N-terminal kinase, resulting in Gαi depalmitoylation and enhanced receptor-Gαi association.
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Affiliation(s)
- Selena S Schattauer
- Department of Pharmacology, University of Washington School of Medicine, Seattle, WA, 98195, USA
| | - Benjamin B Land
- Department of Pharmacology, University of Washington School of Medicine, Seattle, WA, 98195, USA
| | - Kathryn L Reichard
- Department of Pharmacology, University of Washington School of Medicine, Seattle, WA, 98195, USA
| | - Antony D Abraham
- Department of Pharmacology, University of Washington School of Medicine, Seattle, WA, 98195, USA
| | - Lauren M Burgeno
- Department of Pharmacology, University of Washington School of Medicine, Seattle, WA, 98195, USA.,Department of Psychiatry, University of Washington School of Medicine, Seattle, WA, 98195, USA
| | - Jamie R Kuhar
- Department of Pharmacology, University of Washington School of Medicine, Seattle, WA, 98195, USA
| | - Paul E M Phillips
- Department of Pharmacology, University of Washington School of Medicine, Seattle, WA, 98195, USA.,Department of Psychiatry, University of Washington School of Medicine, Seattle, WA, 98195, USA
| | - Shao En Ong
- Department of Pharmacology, University of Washington School of Medicine, Seattle, WA, 98195, USA
| | - Charles Chavkin
- Department of Pharmacology, University of Washington School of Medicine, Seattle, WA, 98195, USA.
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Onfroy L, Galandrin S, Pontier SM, Seguelas MH, N'Guyen D, Sénard JM, Galés C. G protein stoichiometry dictates biased agonism through distinct receptor-G protein partitioning. Sci Rep 2017; 7:7885. [PMID: 28801617 PMCID: PMC5554226 DOI: 10.1038/s41598-017-07392-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Accepted: 06/26/2017] [Indexed: 12/22/2022] Open
Abstract
Biased agonism at G protein coupled receptors emerges as an opportunity for development of drugs with enhanced benefit/risk balance making biased ligand identification a priority. However, ligand biased signature, classically inferred from ligand activity across multiple pathways, displays high variability in recombinant systems. Functional assays usually necessity receptor/effector overexpression that should be controlled among assays to allow comparison but this calibration currently fails. Herein, we demonstrate that Gα expression level dictates the biased profiling of agonists and, to a lesser extent of β-blockers, in a Gα isoform- and receptor-specific way, depending on specific G protein activity in different membrane territories. These results have major therapeutic implications since they suggest that the ligand bias phenotype is not necessarily maintained in pathological cell background characterized by fluctuations in G protein expression. Thus, we recommend implementation of G protein stoichiometry as a new parameter in biased ligand screening programs.
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Affiliation(s)
- Lauriane Onfroy
- Institut des Maladies Métaboliques et Cardiovasculaires, Institut National de la Santé et de la Recherche Médicale, U1048, Université de Toulouse, F-31432, Toulouse, France
| | - Ségolène Galandrin
- Institut des Maladies Métaboliques et Cardiovasculaires, Institut National de la Santé et de la Recherche Médicale, U1048, Université de Toulouse, F-31432, Toulouse, France
| | | | - Marie-Hélène Seguelas
- Institut des Maladies Métaboliques et Cardiovasculaires, Institut National de la Santé et de la Recherche Médicale, U1048, Université de Toulouse, F-31432, Toulouse, France
| | - Du N'Guyen
- Institut des Maladies Métaboliques et Cardiovasculaires, Institut National de la Santé et de la Recherche Médicale, U1048, Université de Toulouse, F-31432, Toulouse, France
| | - Jean-Michel Sénard
- Institut des Maladies Métaboliques et Cardiovasculaires, Institut National de la Santé et de la Recherche Médicale, U1048, Université de Toulouse, F-31432, Toulouse, France.,Service de Pharmacologie Clinique, Centre Hospitalier Universitaire de Toulouse, Faculté de Médecine, Université de Toulouse, F-31000, Toulouse, France
| | - Céline Galés
- Institut des Maladies Métaboliques et Cardiovasculaires, Institut National de la Santé et de la Recherche Médicale, U1048, Université de Toulouse, F-31432, Toulouse, France.
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46
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Noguera-Salvà MA, Guardiola-Serrano F, Martin ML, Marcilla-Etxenike A, Bergo MO, Busquets X, Escribá PV. Role of the C-terminal basic amino acids and the lipid anchor of the Gγ 2 protein in membrane interactions and cell localization. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1859:1536-1547. [PMID: 28235469 DOI: 10.1016/j.bbamem.2017.02.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 02/16/2017] [Accepted: 02/18/2017] [Indexed: 12/25/2022]
Abstract
Heterotrimeric G proteins are peripheral membrane proteins that frequently localize to the plasma membrane where their presence in molar excess over G protein coupled receptors permits signal amplification. Their distribution is regulated by protein-lipid interactions, which has a clear influence on their activity. Gβγ dimer drives the interaction between G protein heterotrimers with cell membranes. We focused our study on the role of the C-terminal region of the Gγ2 protein in G protein interactions with cell membranes. The Gγ2 subunit is modified at cysteine (Cys) 68 by the addition of an isoprenyl lipid, which is followed by the proteolytic removal of the last three residues that leaves an isoprenylated and carboxyl methylated Cys-68 as the terminal amino acid. The role of Cys isoprenylation of the CAAX box has been defined for other proteins, yet the importance of proteolysis and carboxyl methylation of isoprenylated proteins is less clear. Here, we showed that not only geranylgeranylation but also proteolysis and carboxyl methylation are essential for the correct localization of Gγ2 in the plasma membrane. Moreover, we showed the importance of electrostatic interactions between the inner leaflet of the plasma membrane and the positively charged C-terminal domain of the Gγ2 subunit (amino acids Arg-62, Lys-64 and Lys-65) as a second signal to reach the plasma membrane. Indeed, single or multiple point mutations at Gγ2 C-terminal amino acids have a significant effect on Gγ2 protein-plasma membrane interactions and its localization to charged Ld (liquid disordered) membrane microdomains. This article is part of a Special Issue entitled: Membrane Lipid Therapy: Drugs Targeting Biomembranes edited by Pablo V. Escribá.
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Affiliation(s)
- Maria A Noguera-Salvà
- Laboratory of Molecular Cell Biomedicine, Department of Biology, University of the Balearic Islands, E-07122 Palma, Balearic Islands, Spain
| | - Francisca Guardiola-Serrano
- Laboratory of Molecular Cell Biomedicine, Department of Biology, University of the Balearic Islands, E-07122 Palma, Balearic Islands, Spain
| | - M Laura Martin
- Laboratory of Molecular Cell Biomedicine, Department of Biology, University of the Balearic Islands, E-07122 Palma, Balearic Islands, Spain
| | - Amaia Marcilla-Etxenike
- Laboratory of Molecular Cell Biomedicine, Department of Biology, University of the Balearic Islands, E-07122 Palma, Balearic Islands, Spain
| | - Martin O Bergo
- Sahlgrenska Cancer Center, University of Gothenburg, SE-405 30 Gothenburg, Sweden
| | - Xavier Busquets
- Laboratory of Molecular Cell Biomedicine, Department of Biology, University of the Balearic Islands, E-07122 Palma, Balearic Islands, Spain.
| | - Pablo V Escribá
- Laboratory of Molecular Cell Biomedicine, Department of Biology, University of the Balearic Islands, E-07122 Palma, Balearic Islands, Spain
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García-Rico RO, Fierro F. [Role of G-protein alpha sub-units in the morphogenic processes of filamentous Ascomycota fungi]. Rev Iberoam Micol 2017; 34:1-9. [PMID: 28169110 DOI: 10.1016/j.riam.2016.06.005] [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: 09/10/2015] [Revised: 03/30/2016] [Accepted: 06/21/2016] [Indexed: 01/04/2023] Open
Abstract
The phylum Ascomycota comprises about 75% of all the fungal species described, and includes species of medical, phytosanitary, agricultural, and biotechnological importance. The ability to spread, explore, and colonise new substrates is a feature of critical importance for this group of organisms. In this regard, basic processes such as conidial germination, the extension of hyphae and sporulation, make up the backbone of development in most filamentous fungi. These processes require specialised morphogenic machinery, coordinated and regulated by mechanisms that are still being elucidated. In recent years, substantial progress has been made in understanding the role of the signalling pathway mediated by heterotrimericG proteins in basic biological processes of many filamentous fungi. This review focuses on the role of the alpha subunits of heterotrimericG proteins in the morphogenic processes of filamentous Ascomycota.
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Affiliation(s)
- Ramón O García-Rico
- Departamento de Microbiología, Facultad de Ciencias Básicas, Universidad de Pamplona, Pamplona, Norte de Santander, Colombia.
| | - Francisco Fierro
- Departamento de Biotecnología, Universidad Autónoma Metropolitana-Unidad Iztapalapa, Ciudad de México, Distrito Federal, México
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Senarath K, Ratnayake K, Siripurapu P, Payton JL, Karunarathne A. Reversible G Protein βγ9 Distribution-Based Assay Reveals Molecular Underpinnings in Subcellular, Single-Cell, and Multicellular GPCR and G Protein Activity. Anal Chem 2016; 88:11450-11459. [PMID: 27778511 DOI: 10.1021/acs.analchem.6b02512] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Current assays to measure the activation of G protein coupled receptors (GPCRs) and G proteins are time-consuming, indirect, and expensive. Therefore, an efficient method which directly measures the ability of a ligand to govern GPCR-G protein interactions can help to understand the molecular underpinnings of the associated signaling. A live cell imaging-based approach is presented here to directly measure ligand-induced GPCR and G protein activity in real time. The number of active GPCRs governs G protein heterotrimer (αβγ) dissociation, thereby controlling the concentration of free βγ subunits. The described γ9 assay measures the GPCR activation-induced extent of the reversible βγ9 subunit exchange between the plasma membrane (PM) and internal membranes (IMs). Confocal microscopy-based γ9 assay quantitatively determines the concentration dependency of ligands on GPCR activation. Demonstrating the high-throughput screening (HTS) adaptability, the γ9 assay performed using an imaging plate reader measures the ligand-induced GPCR activation. This suggests that the γ9 assay can be employed to screen libraries of compounds for their ability to activate GPCRs. Together with subcellular optogenetics, the spatiotemporal sensitivity of the γ9 assay permits experimental determination of the limits of spatially restricted activation of GPCRs and G proteins in subcellular regions of single cells. This assay works effectively for GPCRs coupled to αi/o and αs heterotrimers, including light-sensitive GPCRs. In addition, computational modeling of experimental data from the assay is used to decipher intricate molecular details of the GPCR-G protein activation process. Overall, the γ9 assay provides a robust strategy for quantitative as well as qualitative determination of GPCR and G protein function on a single-cell, multicell, and subcellular level. This assay not only provides information about the inner workings of the signaling pathway, but it also strengthens GPCR deorphanization as well as drug discovery efforts.
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Affiliation(s)
- Kanishka Senarath
- Department of Chemistry and Biochemistry, The University of Toledo , Toledo, Ohio 43606, United States
| | - Kasun Ratnayake
- Department of Chemistry and Biochemistry, The University of Toledo , Toledo, Ohio 43606, United States
| | - Praneeth Siripurapu
- Department of Chemistry and Biochemistry, The University of Toledo , Toledo, Ohio 43606, United States
| | - John L Payton
- Department of Chemistry and Biochemistry, The University of Toledo , Toledo, Ohio 43606, United States
| | - Ajith Karunarathne
- Department of Chemistry and Biochemistry, The University of Toledo , Toledo, Ohio 43606, United States
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49
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Sprang SR. Invited review: Activation of G proteins by GTP and the mechanism of Gα-catalyzed GTP hydrolysis. Biopolymers 2016; 105:449-62. [PMID: 26996924 PMCID: PMC5319639 DOI: 10.1002/bip.22836] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Revised: 03/11/2016] [Accepted: 03/17/2016] [Indexed: 02/02/2023]
Abstract
This review addresses the regulatory consequences of the binding of GTP to the alpha subunits (Gα) of heterotrimeric G proteins, the reaction mechanism of GTP hydrolysis catalyzed by Gα and the means by which GTPase activating proteins (GAPs) stimulate the GTPase activity of Gα. The high energy of GTP binding is used to restrain and stabilize the conformation of the Gα switch segments, particularly switch II, to afford stable complementary to the surfaces of Gα effectors, while excluding interaction with Gβγ, the regulatory binding partner of GDP-bound Gα. Upon GTP hydrolysis, the energy of these conformational restraints is dissipated and the two switch segments, particularly switch II, become flexible and are able to adopt a conformation suitable for tight binding to Gβγ. Catalytic site pre-organization presents a significant activation energy barrier to Gα GTPase activity. The glutamine residue near the N-terminus of switch II (Glncat ) must adopt a conformation in which it orients and stabilizes the γ phosphate and the water nucleophile for an in-line attack. The transition state is probably loose with dissociative character; phosphoryl transfer may be concerted. The catalytic arginine in switch I (Argcat ), together with amide hydrogen bonds from the phosphate binding loop, stabilize charge at the β-γ bridge oxygen of the leaving group. GAPs that harbor "regulator of protein signaling" (RGS) domains, or structurally unrelated domains within G protein effectors that function as GAPs, accelerate catalysis by stabilizing the pre-transition state for Gα-catalyzed GTP hydrolysis, primarily by restraining Argcat and Glncat to their catalytic conformations. © 2016 Wiley Periodicals, Inc. Biopolymers 105: 449-462, 2016.
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Affiliation(s)
- Stephen R. Sprang
- Center for Biomolecular Structure and Dynamics, Division of Biological Sciences, University of Montana, 32 Campus Drive, Missoula, MT 59812, Telephone: (406) 243-6028, Fax: (406) 243-6024,
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50
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Moriya K, Kimoto M, Matsuzaki K, Kiwado A, Takamitsu E, Utsumi T. Identification of dually acylated proteins from complementary DNA resources by cell-free and cellular metabolic labeling. Anal Biochem 2016; 511:1-9. [PMID: 27480498 DOI: 10.1016/j.ab.2016.07.025] [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: 05/22/2016] [Revised: 07/22/2016] [Accepted: 07/26/2016] [Indexed: 01/06/2023]
Abstract
To establish a strategy to identify dually fatty acylated proteins from cDNA resources, seven N-myristoylated proteins with cysteine (Cys) residues within the 10 N-terminal residues were selected as potential candidates among 27 N-myristoylated proteins identified from a model human cDNA resource. Seven proteins C-terminally tagged with FLAG tag or EGFP were generated and their susceptibility to protein N-myristoylation and S-palmitoylation were evaluated by metabolic labeling with [(3)H]myristic acid or [(3)H]palmitic acid either in an insect cell-free protein synthesis system or in transfected mammalian cells. As a result, EEPD1, one of five proteins (RFTN1, EEPD1, GNAI1, PDE2A, RNF11) found to be dually acylated, was shown to be a novel dually fatty acylated protein. Metabolic labeling experiments using G2A and C7S mutants of EEPD1-EGFP revealed that the palmitoylation site of EEPD1 is Cys at position 7. Analysis of the intracellular localization of EEPD1 C-terminally tagged with FLAG tag or EGFP and its G2A and C7S mutants revealed that the dual acylation directs EEPD1 to localize to the plasma membrane. Thus, dually fatty acylated proteins can be identified from cDNA resources by cell-free and cellular metabolic labeling of N-myristoylated proteins with Cys residue(s) close to the N-myristoylated N-terminus.
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Affiliation(s)
- Koko Moriya
- Department of Biological Chemistry, Faculty of Agriculture, Yamaguchi University, Yamaguchi 753-8515, Japan
| | - Mayumi Kimoto
- Department of Biological Chemistry, Faculty of Agriculture, Yamaguchi University, Yamaguchi 753-8515, Japan
| | - Kanako Matsuzaki
- Department of Biological Chemistry, Faculty of Agriculture, Yamaguchi University, Yamaguchi 753-8515, Japan
| | - Aya Kiwado
- Department of Biological Chemistry, Faculty of Agriculture, Yamaguchi University, Yamaguchi 753-8515, Japan
| | - Emi Takamitsu
- Department of Biological Chemistry, Faculty of Agriculture, Yamaguchi University, Yamaguchi 753-8515, Japan
| | - Toshihiko Utsumi
- Department of Biological Chemistry, Faculty of Agriculture, Yamaguchi University, Yamaguchi 753-8515, Japan.
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