1
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Zhu Y, Pei X, Novaj A, Setton J, Bronder D, Derakhshan F, Selenica P, McDermott N, Orman M, Plum S, Subramanyan S, Braverman SH, McMillan B, Sinha S, Ma J, Gazzo A, Khan A, Bakhoum S, Powell SN, Reis-Filho JS, Riaz N. Large-scale copy number alterations are enriched for synthetic viability in BRCA1/BRCA2 tumors. Genome Med 2024; 16:108. [PMID: 39198848 PMCID: PMC11351199 DOI: 10.1186/s13073-024-01371-y] [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: 10/29/2023] [Accepted: 08/02/2024] [Indexed: 09/01/2024] Open
Abstract
BACKGROUND Pathogenic BRCA1 or BRCA2 germline mutations contribute to hereditary breast, ovarian, prostate, and pancreatic cancer. Paradoxically, bi-allelic inactivation of BRCA1 or BRCA2 (bBRCA1/2) is embryonically lethal and decreases cellular proliferation. The compensatory mechanisms that facilitate oncogenesis in bBRCA1/2 tumors remain unclear. METHODS We identified recurrent genetic alterations enriched in human bBRCA1/2 tumors and experimentally validated if these improved proliferation in cellular models. We analyzed mutations and copy number alterations (CNAs) in bBRCA1/2 breast and ovarian cancer from the TCGA and ICGC. We used Fisher's exact test to identify CNAs enriched in bBRCA1/2 tumors compared to control tumors that lacked evidence of homologous recombination deficiency. Genes located in CNA regions enriched in bBRCA1/2 tumors were further screened by gene expression and their effects on proliferation in genome-wide CRISPR/Cas9 screens. A set of candidate genes was functionally validated with in vitro clonogenic survival and functional assays to validate their influence on proliferation in the setting of bBRCA1/2 mutations. RESULTS We found that bBRCA1/2 tumors harbor recurrent large-scale genomic deletions significantly more frequently than histologically matched controls (n = 238 cytobands in breast and ovarian cancers). Within the deleted regions, we identified 277 BRCA1-related genes and 218 BRCA2-related genes that had reduced expression and increased proliferation in bBRCA1/2 but not in wild-type cells in genome-wide CRISPR screens. In vitro validation of 20 candidate genes with clonogenic proliferation assays validated 9 genes, including RIC8A and ATMIN (ATM-Interacting protein). We identified loss of RIC8A, which occurs frequently in both bBRCA1/2 tumors and is synthetically viable with loss of both BRCA1 and BRCA2. Furthermore, we found that metastatic homologous recombination deficient cancers acquire loss-of-function mutations in RIC8A. Lastly, we identified that RIC8A does not rescue homologous recombination deficiency but may influence mitosis in bBRCA1/2 tumors, potentially leading to increased micronuclei formation. CONCLUSIONS This study provides a means to solve the tumor suppressor paradox by identifying synthetic viability interactions and causal driver genes affected by large-scale CNAs in human cancers.
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Affiliation(s)
- Yingjie Zhu
- Department of Pathology and Laboratory Medicine, Memorial Sloan Kettering Cancer Center, New York, NY, USA
- Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Xin Pei
- Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Ardijana Novaj
- Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Jeremy Setton
- Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Daniel Bronder
- Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Fatemeh Derakhshan
- Department of Pathology and Laboratory Medicine, Memorial Sloan Kettering Cancer Center, New York, NY, USA
- Present address: Department of Pathology & Cell Biology, Columbia University Medical Center, New York, NY, USA
| | - Pier Selenica
- Department of Pathology and Laboratory Medicine, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Niamh McDermott
- Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Mehmet Orman
- Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Sarina Plum
- Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Shyamal Subramanyan
- Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Sara H Braverman
- Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Biko McMillan
- Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Sonali Sinha
- Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Jennifer Ma
- Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Andrea Gazzo
- Department of Pathology and Laboratory Medicine, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Atif Khan
- Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Samuel Bakhoum
- Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, NY, USA
- Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Simon N Powell
- Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Jorge S Reis-Filho
- Department of Pathology and Laboratory Medicine, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
| | - Nadeem Riaz
- Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
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2
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Bonifer C, Hanke W, Mühle J, Löhr F, Becker-Baldus J, Nagel J, Schertler GFX, Müller CE, König GM, Hilger D, Glaubitz C. Structural response of G protein binding to the cyclodepsipeptide inhibitor FR900359 probed by NMR spectroscopy. Chem Sci 2024; 15:12939-12956. [PMID: 39148790 PMCID: PMC11323312 DOI: 10.1039/d4sc01950d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2024] [Accepted: 06/27/2024] [Indexed: 08/17/2024] Open
Abstract
The cyclodepsipeptide FR900359 (FR) and its analogs are able to selectively inhibit the class of Gq proteins by blocking GDP/GTP exchange. The inhibitor binding site of Gq has been characterized by X-ray crystallography, and various binding and functional studies have determined binding kinetics and mode of inhibition. Here we investigate isotope-labeled FR bound to the membrane-anchored G protein heterotrimer by solid-state nuclear magnetic resonance (ssNMR) and in solution by liquid-state NMR. The resulting data allowed us to identify regions of the inhibitor which show especially pronounced effects upon binding and revealed a generally rigid binding mode in the cis conformation under native-like conditions. The inclusion of the membrane environment allowed us to show a deep penetration of FR into the lipid bilayer illustrating a possible access mode of FR into the cell. Dynamic nuclear polarization (DNP)-enhanced ssNMR was used to observe the structural response of specific segments of the Gα subunit to inhibitor binding. This revealed rigidification of the switch I binding site and an allosteric response in the α5 helix as well as suppression of structural changes induced by nucleotide exchange due to inhibition by FR. Our NMR studies of the FR-G protein complex conducted directly within a native membrane environment provide important insights into the inhibitors access via the lipid membrane, binding mode, and structural allosteric effects.
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Affiliation(s)
- Christian Bonifer
- Institute of Biophysical Chemistry, Centre of Biomolecular Magnetic Resonance, Goethe University Frankfurt Max-von-Laue Str. 9 60438 Frankfurt Germany
| | - Wiebke Hanke
- Institute for Pharmaceutical Biology, University of Bonn Nussallee 6 53115 Bonn Germany
| | - Jonas Mühle
- Division of Biology and Chemistry, Laboratory of Biomolecular Research, Paul Scherrer Institute Forschungsstr. 111, 5232 Villigen PSI Switzerland
| | - Frank Löhr
- Institute of Biophysical Chemistry, Centre of Biomolecular Magnetic Resonance, Goethe University Frankfurt Max-von-Laue Str. 9 60438 Frankfurt Germany
| | - Johanna Becker-Baldus
- Institute of Biophysical Chemistry, Centre of Biomolecular Magnetic Resonance, Goethe University Frankfurt Max-von-Laue Str. 9 60438 Frankfurt Germany
| | - Jessica Nagel
- Department of Pharmaceutical & Medicinal Chemistry, Pharmaceutical Institute, University of Bonn An der Immenburg 4 53121 Bonn Germany
| | - Gebhard F X Schertler
- Division of Biology and Chemistry, Laboratory of Biomolecular Research, Paul Scherrer Institute Forschungsstr. 111, 5232 Villigen PSI Switzerland
| | - Christa E Müller
- Department of Pharmaceutical & Medicinal Chemistry, Pharmaceutical Institute, University of Bonn An der Immenburg 4 53121 Bonn Germany
| | - Gabriele M König
- Institute for Pharmaceutical Biology, University of Bonn Nussallee 6 53115 Bonn Germany
| | - Daniel Hilger
- Department of Pharmaceutical Chemistry, University of Marburg 35037 Marburg Germany
| | - Clemens Glaubitz
- Institute of Biophysical Chemistry, Centre of Biomolecular Magnetic Resonance, Goethe University Frankfurt Max-von-Laue Str. 9 60438 Frankfurt Germany
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3
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Pepanian A, Sommerfeld P, Binbay FA, Fischer D, Pietsch M, Imhof D. In-depth analysis of Gαs protein activity by probing different fluorescently labeled guanine nucleotides. Biol Chem 2024; 405:297-309. [PMID: 38353111 DOI: 10.1515/hsz-2023-0321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Accepted: 01/10/2024] [Indexed: 05/04/2024]
Abstract
G proteins are interacting partners of G protein-coupled receptors (GPCRs) in eukaryotic cells. Upon G protein activation, the ability of the Gα subunit to exchange GDP for GTP determines the intracellular signal transduction. Although various studies have successfully shown that both Gαs and Gαi have an opposite effect on the intracellular cAMP production, with the latter being commonly described as "more active", the functional analysis of Gαs is a comparably more complicated matter. Additionally, the thorough investigation of the ubiquitously expressed variants of Gαs, Gαs(short) and Gαs(long), is still pending. Since the previous experimental evaluation of the activity and function of the Gαs isoforms is not consistent, the focus was laid on structural investigations to understand the GTPase activity. Herein, we examined recombinant human Gαs by applying an established methodological setup developed for Gαi characterization. The ability for GTP binding was evaluated with fluorescence and fluorescence anisotropy assays, whereas the intrinsic hydrolytic activity of the isoforms was determined by a GTPase assay. Among different nucleotide probes, BODIPY FL GTPγS exhibited the highest binding affinity towards the Gαs subunit. This work provides a deeper understanding of the Gαs subunit and provides novel information concerning the differences between the two protein variants.
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Affiliation(s)
- Anna Pepanian
- Pharmaceutical Biochemistry and Bioanalytics, Pharmaceutical Institute, University of Bonn, An der Immenburg 4, D-53121 Bonn, Germany
| | - Paul Sommerfeld
- Institutes I & II of Pharmacology, Center of Pharmacology, Faculty of Medicine and University Hospital Cologne, University of Cologne, D-50931 Cologne, Germany
| | - Furkan Ayberk Binbay
- Pharmaceutical Biochemistry and Bioanalytics, Pharmaceutical Institute, University of Bonn, An der Immenburg 4, D-53121 Bonn, Germany
| | - Dietmar Fischer
- Institutes I & II of Pharmacology, Center of Pharmacology, Faculty of Medicine and University Hospital Cologne, University of Cologne, D-50931 Cologne, Germany
| | - Markus Pietsch
- Institutes I & II of Pharmacology, Center of Pharmacology, Faculty of Medicine and University Hospital Cologne, University of Cologne, D-50931 Cologne, Germany
- Faculty of Applied Natural Sciences, TH Köln-University of Applied Sciences, Campus Leverkusen, D-51379 Leverkusen, Germany
| | - Diana Imhof
- Pharmaceutical Biochemistry and Bioanalytics, Pharmaceutical Institute, University of Bonn, An der Immenburg 4, D-53121 Bonn, Germany
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4
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Izquierdo-Villalba I, Mirra S, Manso Y, Parcerisas A, Rubio J, Del Valle J, Gil-Bea FJ, Ulloa F, Herrero-Lorenzo M, Verdaguer E, Benincá C, Castro-Torres RD, Rebollo E, Marfany G, Auladell C, Navarro X, Enríquez JA, López de Munain A, Soriano E, Aragay AM. A mammalian-specific Alex3/Gα q protein complex regulates mitochondrial trafficking, dendritic complexity, and neuronal survival. Sci Signal 2024; 17:eabq1007. [PMID: 38320000 DOI: 10.1126/scisignal.abq1007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Accepted: 01/16/2024] [Indexed: 02/08/2024]
Abstract
Mitochondrial dynamics and trafficking are essential to provide the energy required for neurotransmission and neural activity. We investigated how G protein-coupled receptors (GPCRs) and G proteins control mitochondrial dynamics and trafficking. The activation of Gαq inhibited mitochondrial trafficking in neurons through a mechanism that was independent of the canonical downstream PLCβ pathway. Mitoproteome analysis revealed that Gαq interacted with the Eutherian-specific mitochondrial protein armadillo repeat-containing X-linked protein 3 (Alex3) and the Miro1/Trak2 complex, which acts as an adaptor for motor proteins involved in mitochondrial trafficking along dendrites and axons. By generating a CNS-specific Alex3 knockout mouse line, we demonstrated that Alex3 was required for the effects of Gαq on mitochondrial trafficking and dendritic growth in neurons. Alex3-deficient mice had altered amounts of ER stress response proteins, increased neuronal death, motor neuron loss, and severe motor deficits. These data revealed a mammalian-specific Alex3/Gαq mitochondrial complex, which enables control of mitochondrial trafficking and neuronal death by GPCRs.
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Affiliation(s)
| | - Serena Mirra
- Department of Cell Biology, Physiology and Immunology, and Institute of Neurosciences, University of Barcelona, Barcelona 08028, Spain
- Department of Genetics, Microbiology and Statistics, University of Barcelona, Barcelona 08028, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBER-CIBERNED), ISCIII, Madrid 28031, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Raras (CIBER-CIBERER), ISCIII, Madrid 28031, Spain
- Institut de Biomedicina- Institut de Recerca Sant Joan de Déu (IBUB-IRSJD), Universitat de Barcelona, Barcelona 08028, Spain
| | - Yasmina Manso
- Department of Cell Biology, Physiology and Immunology, and Institute of Neurosciences, University of Barcelona, Barcelona 08028, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBER-CIBERNED), ISCIII, Madrid 28031, Spain
| | - Antoni Parcerisas
- Department of Cell Biology, Physiology and Immunology, and Institute of Neurosciences, University of Barcelona, Barcelona 08028, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBER-CIBERNED), ISCIII, Madrid 28031, Spain
- Biosciences Department, Faculty of Sciences, Technology and Engineering, University of Vic, Central University of Catalonia (UVic-UCC); and Tissue Repair and Regeneration Laboratory (TR2Lab), Institut de Recerca i Innovació en Ciències de la Vida i de la Salut a la Catalunya Central (IRIS-CC), 08500 Vic, Spain
| | - Javier Rubio
- Institut de Biologia Molecular de Barcelona (IBMB-CSIC), Barcelona 08028, Spain
| | - Jaume Del Valle
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBER-CIBERNED), ISCIII, Madrid 28031, Spain
- Department of Cell Biology, Physiology and Immunology, and Institute of Neurosciences, Universitat Autonoma de Barcelona, Bellaterra, Barcelona 08193, Spain
| | - Francisco J Gil-Bea
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBER-CIBERNED), ISCIII, Madrid 28031, Spain
- Neurosciences Area, Biodonostia Health Research Institute, San Sebastián 20014, Spain
| | - Fausto Ulloa
- Department of Cell Biology, Physiology and Immunology, and Institute of Neurosciences, University of Barcelona, Barcelona 08028, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBER-CIBERNED), ISCIII, Madrid 28031, Spain
| | - Marina Herrero-Lorenzo
- Department of Cell Biology, Physiology and Immunology, and Institute of Neurosciences, University of Barcelona, Barcelona 08028, Spain
| | - Ester Verdaguer
- Department of Cell Biology, Physiology and Immunology, and Institute of Neurosciences, University of Barcelona, Barcelona 08028, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBER-CIBERNED), ISCIII, Madrid 28031, Spain
| | - Cristiane Benincá
- Institut de Biologia Molecular de Barcelona (IBMB-CSIC), Barcelona 08028, Spain
| | - Rubén D Castro-Torres
- Department of Cell Biology, Physiology and Immunology, and Institute of Neurosciences, University of Barcelona, Barcelona 08028, Spain
| | - Elena Rebollo
- Institut de Biologia Molecular de Barcelona (IBMB-CSIC), Barcelona 08028, Spain
| | - Gemma Marfany
- Department of Genetics, Microbiology and Statistics, University of Barcelona, Barcelona 08028, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Raras (CIBER-CIBERER), ISCIII, Madrid 28031, Spain
- Institut de Biomedicina- Institut de Recerca Sant Joan de Déu (IBUB-IRSJD), Universitat de Barcelona, Barcelona 08028, Spain
| | - Carme Auladell
- Department of Cell Biology, Physiology and Immunology, and Institute of Neurosciences, University of Barcelona, Barcelona 08028, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBER-CIBERNED), ISCIII, Madrid 28031, Spain
| | - Xavier Navarro
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBER-CIBERNED), ISCIII, Madrid 28031, Spain
- Department of Cell Biology, Physiology and Immunology, and Institute of Neurosciences, Universitat Autonoma de Barcelona, Bellaterra, Barcelona 08193, Spain
| | - José A Enríquez
- Fundación Centro Nacional de Investigaciones Cardiovasculares Carlos III, Madrid 28029, Spain
- Centro de Investigación Biomédica en Red en Fragilidad y Envejecimiento Saludable (CIBER-CIBERFES), Madrid 28031, Spain
| | - Adolfo López de Munain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBER-CIBERNED), ISCIII, Madrid 28031, Spain
- Neurosciences Area, Biodonostia Health Research Institute, San Sebastián 20014, Spain
- Neurology Department, Donostia University Hospital, San Sebastián 20014, Spain
| | - Eduardo Soriano
- Department of Cell Biology, Physiology and Immunology, and Institute of Neurosciences, University of Barcelona, Barcelona 08028, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBER-CIBERNED), ISCIII, Madrid 28031, Spain
| | - Anna M Aragay
- Institut de Biologia Molecular de Barcelona (IBMB-CSIC), Barcelona 08028, Spain
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5
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Zhao LH, He Q, Yuan Q, Gu Y, He X, Shan H, Li J, Wang K, Li Y, Hu W, Wu K, Shen J, Xu HE. Conserved class B GPCR activation by a biased intracellular agonist. Nature 2023; 621:635-641. [PMID: 37524305 DOI: 10.1038/s41586-023-06467-w] [Citation(s) in RCA: 21] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Accepted: 07/20/2023] [Indexed: 08/02/2023]
Abstract
Class B G-protein-coupled receptors (GPCRs), including glucagon-like peptide 1 receptor (GLP1R) and parathyroid hormone 1 receptor (PTH1R), are important drug targets1-5. Injectable peptide drugs targeting these receptors have been developed, but orally available small-molecule drugs remain under development6,7. Here we report the high-resolution structure of human PTH1R in complex with the stimulatory G protein (Gs) and a small-molecule agonist, PCO371, which reveals an unexpected binding mode of PCO371 at the cytoplasmic interface of PTH1R with Gs. The PCO371-binding site is totally different from all binding sites previously reported for small molecules or peptide ligands in GPCRs. The residues that make up the PCO371-binding pocket are conserved in class B GPCRs, and a single alteration in PTH2R and two residue alterations in GLP1R convert these receptors to respond to PCO371. Functional assays reveal that PCO371 is a G-protein-biased agonist that is defective in promoting PTH1R-mediated arrestin signalling. Together, these results uncover a distinct binding site for designing small-molecule agonists for PTH1R and possibly other members of the class B GPCRs and define a receptor conformation that is specific only for G-protein activation but not arrestin signalling. These insights should facilitate the design of distinct types of class B GPCR small-molecule agonist for various therapeutic indications.
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MESH Headings
- Humans
- Arrestin/metabolism
- Binding Sites
- GTP-Binding Protein alpha Subunits, Gs/metabolism
- Imidazolidines/pharmacology
- Ligands
- Peptides/pharmacology
- Protein Conformation
- Receptor, Parathyroid Hormone, Type 1/agonists
- Receptor, Parathyroid Hormone, Type 1/classification
- Receptor, Parathyroid Hormone, Type 1/metabolism
- Receptors, G-Protein-Coupled/agonists
- Receptors, G-Protein-Coupled/classification
- Receptors, G-Protein-Coupled/metabolism
- Signal Transduction/drug effects
- Spiro Compounds/pharmacology
- Drug Design
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Affiliation(s)
- Li-Hua Zhao
- State Key Laboratory of Drug Research, Center for Structure and Function of Drug Targets, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China.
- University of Chinese Academy of Sciences, Beijing, China.
| | - Qian He
- State Key Laboratory of Drug Research, Center for Structure and Function of Drug Targets, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Qingning Yuan
- State Key Laboratory of Drug Research, Center for Structure and Function of Drug Targets, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Yimin Gu
- State Key Laboratory of Drug Research, Center for Structure and Function of Drug Targets, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Xinheng He
- State Key Laboratory of Drug Research, Center for Structure and Function of Drug Targets, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Hong Shan
- State Key Laboratory of Drug Research, Center for Structure and Function of Drug Targets, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Junrui Li
- State Key Laboratory of Drug Research, Center for Structure and Function of Drug Targets, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Kai Wang
- State Key Laboratory of Drug Research, Center for Structure and Function of Drug Targets, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Yang Li
- State Key Laboratory of Drug Research, Center for Structure and Function of Drug Targets, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Wen Hu
- State Key Laboratory of Drug Research, Center for Structure and Function of Drug Targets, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Kai Wu
- State Key Laboratory of Drug Research, Center for Structure and Function of Drug Targets, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Jianhua Shen
- State Key Laboratory of Drug Research, Center for Structure and Function of Drug Targets, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - H Eric Xu
- State Key Laboratory of Drug Research, Center for Structure and Function of Drug Targets, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China.
- University of Chinese Academy of Sciences, Beijing, China.
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6
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Falzone ME, MacKinnon R. The mechanism of Gα q regulation of PLCβ3 -catalyzed PIP2 hydrolysis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.29.555394. [PMID: 37693483 PMCID: PMC10491199 DOI: 10.1101/2023.08.29.555394] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
PLCβ enzymes cleave PIP2 producing IP3 and DAG. PIP2 modulates the function of many ion channels, while IP3 and DAG regulate intracellular Ca 2+ levels and protein phosphorylation by protein kinase C, respectively. PLCβ enzymes are under the control of GPCR signaling through direct interactions with G proteins Gβγ and Gα q and have been shown to be coincidence detectors for dual stimulation of Gα q and G α i coupled receptors. PLCβs are aqueous-soluble cytoplasmic enzymes, but partition onto the membrane surface to access their lipid substrate, complicating their functional and structural characterization. Using newly developed methods, we recently showed that Gβγ activates PLCβ3 by recruiting it to the membrane. Using these same methods, here we show that Gα q increases the catalytic rate constant, k cat , of PLCβ3 . Since stimulation of PLCβ3 by Gα q depends on an autoinhibitory element (the X-Y linker), we propose that Gα q produces partial relief of the X-Y linker autoinhibition through an allosteric mechanism. We also determined membrane-bound structures of the PLCβ3-Gα q , and PLCβ3-Gβγ(2)-Gα q complexes, which show that these G proteins can bind simultaneously and independently of each other to regulate PLCβ3 activity. The structures rationalize a finding in the enzyme assay, that co-stimulation by both G proteins follows a product rule of each independent stimulus. We conclude that baseline activity of PLCβ3 is strongly suppressed, but the effect of G proteins, especially acting together, provides a robust stimulus upon G protein stimulation. Significance Statement For certain cellular signaling processes, the background activity of signaling enzymes must be minimal and stimulus-dependent activation robust. Nowhere is this truer than in signaling by PLCβ3 , whose activity regulates intracellular Ca 2+ , phosphorylation by Protein Kinase C, and the activity of numerous ion channels and membrane receptors. In this study we show how PLCβ3 enzymes are regulated by two kinds of G proteins, Gβγ and Gα q . Enzyme activity studies and structures on membranes show how these G proteins act by separate, independent mechanisms, leading to a product rule of co-stimulation when they act together. The findings explain how cells achieve robust stimulation of PLCβ3 in the setting of very low background activity, properties essential to cell health and survival.
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7
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Zhao LH, Yuan QN, Dai AT, He XH, Chen CW, Zhang C, Xu YW, Zhou Y, Wang MW, Yang DH, Xu HE. Molecular recognition of two endogenous hormones by the human parathyroid hormone receptor-1. Acta Pharmacol Sin 2023; 44:1227-1237. [PMID: 36482086 PMCID: PMC10203121 DOI: 10.1038/s41401-022-01032-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2022] [Accepted: 11/15/2022] [Indexed: 12/13/2022] Open
Abstract
Parathyroid hormone (PTH) and PTH-related peptide (PTHrP) are two endogenous hormones recognized by PTH receptor-1 (PTH1R), a member of class B G protein- coupled receptors (GPCRs). Both PTH and PTHrP analogs including teriparatide and abaloparatide are approved drugs for osteoporosis, but they exhibit distinct pharmacology. Here we report two cryo-EM structures of human PTH1R bound to PTH and PTHrP in the G protein-bound state at resolutions of 2.62 Å and 3.25 Å, respectively. Detailed analysis of these structures uncovers both common and unique features for the agonism of PTH and PTHrP. Molecular dynamics (MD) simulation together with site-directed mutagenesis studies reveal the molecular basis of endogenous hormones recognition specificity and selectivity to PTH1R. These results provide a rational template for the clinical use of PTH and PTHrP analogs as an anabolic therapy for osteoporosis and other disorders.
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Affiliation(s)
- Li-Hua Zhao
- The CAS Key Laboratory of Receptor Research, Center for Structure and Function of Drug Targets, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China.
- University of Chinese Academy of Sciences, Beijing, 100049, China.
| | - Qing-Ning Yuan
- The CAS Key Laboratory of Receptor Research, Center for Structure and Function of Drug Targets, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
| | - An-Tao Dai
- The CAS Key Laboratory of Receptor Research, Center for Structure and Function of Drug Targets, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
- The National Center for Drug Screening, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
| | - Xin-Heng He
- The CAS Key Laboratory of Receptor Research, Center for Structure and Function of Drug Targets, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Chuan-Wei Chen
- Research Center for Deepsea Bioresources, Sanya, 572025, China
| | - Chao Zhang
- School of Pharmacy, Fudan University, Shanghai, 201203, China
| | - You-Wei Xu
- The CAS Key Laboratory of Receptor Research, Center for Structure and Function of Drug Targets, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
| | - Yan Zhou
- The CAS Key Laboratory of Receptor Research, Center for Structure and Function of Drug Targets, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
- The National Center for Drug Screening, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
| | - Ming-Wei Wang
- Research Center for Deepsea Bioresources, Sanya, 572025, China
- Department of Pharmacology, School of Basic Medical Sciences, Fudan University, Shanghai, 200032, China
- Department of Chemistry, School of Science, The University of Tokyo, Tokyo, 113-0033, Japan
| | - De-Hua Yang
- The CAS Key Laboratory of Receptor Research, Center for Structure and Function of Drug Targets, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China.
- University of Chinese Academy of Sciences, Beijing, 100049, China.
- The National Center for Drug Screening, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China.
| | - H Eric Xu
- The CAS Key Laboratory of Receptor Research, Center for Structure and Function of Drug Targets, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China.
- University of Chinese Academy of Sciences, Beijing, 100049, China.
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8
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Papasergi-Scott MM, Kwarcinski FE, Yu M, Panova O, Ovrutsky AM, Skiniotis G, Tall GG. Structures of Ric-8B in complex with Gα protein folding clients reveal isoform specificity mechanisms. Structure 2023; 31:553-564.e7. [PMID: 36931277 PMCID: PMC10164081 DOI: 10.1016/j.str.2023.02.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 01/23/2023] [Accepted: 02/20/2023] [Indexed: 03/18/2023]
Abstract
Mammalian Ric-8 proteins act as chaperones to regulate the cellular abundance of heterotrimeric G protein α subunits. The Ric-8A isoform chaperones Gαi/o, Gα12/13, and Gαq/11 subunits, while Ric-8B acts on Gαs/olf subunits. Here, we determined cryoelectron microscopy (cryo-EM) structures of Ric-8B in complex with Gαs and Gαolf, revealing isoform differences in the relative positioning and contacts between the C-terminal α5 helix of Gα within the concave pocket formed by Ric-8 α-helical repeat elements. Despite the overall architectural similarity with our earlier structures of Ric-8A complexed to Gαq and Gαi1, Ric-8B distinctly accommodates an extended loop found only in Gαs/olf proteins. The structures, along with results from Ric-8 protein thermal stability assays and cell-based Gαolf folding assays, support a requirement for the Gα C-terminal region for binding specificity, and highlight that multiple structural elements impart specificity for Ric-8/G protein binding.
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Affiliation(s)
- Makaía M Papasergi-Scott
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Frank E Kwarcinski
- Department of Pharmacology, University of Michigan School of Medicine, Ann Arbor, MI 48109, USA
| | - Maiya Yu
- Department of Pharmacology, University of Michigan School of Medicine, Ann Arbor, MI 48109, USA
| | - Ouliana Panova
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Ann M Ovrutsky
- Department of Pharmacology, University of Michigan School of Medicine, Ann Arbor, MI 48109, USA
| | - Georgios Skiniotis
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA.
| | - Gregory G Tall
- Department of Pharmacology, University of Michigan School of Medicine, Ann Arbor, MI 48109, USA.
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9
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Zhao LH, Lin J, Ji SY, Zhou XE, Mao C, Shen DD, He X, Xiao P, Sun J, Melcher K, Zhang Y, Yu X, Xu HE. Structure insights into selective coupling of G protein subtypes by a class B G protein-coupled receptor. Nat Commun 2022; 13:6670. [PMID: 36335102 PMCID: PMC9637140 DOI: 10.1038/s41467-022-33851-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Accepted: 10/05/2022] [Indexed: 11/07/2022] Open
Abstract
The ability to couple with multiple G protein subtypes, such as Gs, Gi/o, or Gq/11, by a given G protein-coupled receptor (GPCR) is critical for many physiological processes. Over the past few years, the cryo-EM structures for all 15 members of the medically important class B GPCRs, all in complex with Gs protein, have been determined. However, no structure of class B GPCRs with Gq/11 has been solved to date, limiting our understanding of the precise mechanisms of G protein coupling selectivity. Here we report the structures of corticotropin releasing factor receptor 2 (CRF2R) bound to Urocortin 1 (UCN1), coupled with different classes of heterotrimeric G proteins, G11 and Go. We compare these structures with the structure of CRF2R in complex with Gs to uncover the structural differences that determine the selective coupling of G protein subtypes by CRF2R. These results provide important insights into the structural basis for the ability of CRF2R to couple with multiple G protein subtypes.
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Affiliation(s)
- Li-Hua Zhao
- grid.9227.e0000000119573309The CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203 China ,grid.410726.60000 0004 1797 8419University of Chinese Academy of Sciences, Beijing, 100049 China
| | - Jingyu Lin
- grid.27255.370000 0004 1761 1174Department of Physiology, School of Basic Medical Sciences, Shandong University, Jinan, 250012 China
| | - Su-Yu Ji
- grid.13402.340000 0004 1759 700XDepartment of Biophysics and Pathology of Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, 310058 China
| | - X. Edward Zhou
- grid.251017.00000 0004 0406 2057Department of Structural Biology, Van Andel Research Institute, Grand Rapids, MI 49503 USA
| | - Chunyou Mao
- grid.13402.340000 0004 1759 700XDepartment of Biophysics and Pathology of Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, 310058 China
| | - Dan-Dan Shen
- grid.13402.340000 0004 1759 700XDepartment of Biophysics and Pathology of Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, 310058 China
| | - Xinheng He
- grid.9227.e0000000119573309The CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203 China ,grid.410726.60000 0004 1797 8419University of Chinese Academy of Sciences, Beijing, 100049 China
| | - Peng Xiao
- grid.27255.370000 0004 1761 1174Department of Physiology, School of Basic Medical Sciences, Shandong University, Jinan, 250012 China
| | - Jinpeng Sun
- grid.27255.370000 0004 1761 1174Department of Physiology, School of Basic Medical Sciences, Shandong University, Jinan, 250012 China
| | - Karsten Melcher
- grid.251017.00000 0004 0406 2057Department of Structural Biology, Van Andel Research Institute, Grand Rapids, MI 49503 USA
| | - Yan Zhang
- grid.13402.340000 0004 1759 700XDepartment of Biophysics and Pathology of Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, 310058 China ,grid.13402.340000 0004 1759 700XLiangzhu Laboratory, Zhejiang University Medical Center, Hangzhou, 311121 China ,grid.13402.340000 0004 1759 700XMOE Frontier Science Center for Brain Research and Brain-Machine Integration, Zhejiang University School of Medicine, Hangzhou, 310058 China ,Zhejiang Provincial Key Laboratory of Immunity and Inflammatory diseases, Hangzhou, 310058 China
| | - Xiao Yu
- grid.27255.370000 0004 1761 1174Department of Physiology, School of Basic Medical Sciences, Shandong University, Jinan, 250012 China
| | - H. Eric Xu
- grid.9227.e0000000119573309The CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203 China ,grid.410726.60000 0004 1797 8419University of Chinese Academy of Sciences, Beijing, 100049 China
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10
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Srivastava D, Yadav RP, Inamdar SM, Huang Z, Sokolov M, Boyd K, Artemyev NO. Transducin Partners Outside the Phototransduction Pathway. Front Cell Neurosci 2020; 14:589494. [PMID: 33173469 PMCID: PMC7591391 DOI: 10.3389/fncel.2020.589494] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Accepted: 09/10/2020] [Indexed: 11/13/2022] Open
Abstract
Transducin mediates signal transduction in a classical G protein-coupled receptor (GPCR) phototransduction cascade. Interactions of transducin with the receptor and the effector molecules had been extensively investigated and are currently defined at the atomic level. However, partners and functions of rod transducin α (Gαt 1) and βγ (Gβ1γ1) outside the visual pathway are not well-understood. In particular, light-induced redistribution of rod transducin from the outer segment to the inner segment and synaptic terminal (IS/ST) allows Gαt1 and/or Gβ1γ1 to modulate synaptic transmission from rods to rod bipolar cells (RBCs). Protein-protein interactions underlying this modulation are largely unknown. We discuss known interactors of transducin in the rod IS/ST compartment and potential pathways leading to the synaptic effects of light-dispersed Gαt1 and Gβ1γ1. Furthermore, we show that a prominent non-GPCR guanine nucleotide exchange factor (GEF) and a chaperone of Gα subunits, resistance to inhibitors of cholinesterase 8A (Ric-8A) protein, is expressed throughout the retina including photoreceptor cells. Recent structures of Ric-8A alone and in complexes with Gα subunits have illuminated the structural underpinnings of the Ric-8A activities. We generated a mouse model with conditional knockout of Ric-8A in rods in order to begin defining the functional roles of the protein in rod photoreceptors and the retina. Our analysis suggests that Ric-8A is not an obligate chaperone of Gαt1. Further research is needed to investigate probable roles of Ric-8A as a GEF, trafficking chaperone, or a mediator of the synaptic effects of Gαt1.
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Affiliation(s)
- Dhiraj Srivastava
- Department of Molecular Physiology and Biophysics, The University of Iowa Carver College of Medicine, Iowa City, IA, United States
| | - Ravi P Yadav
- Department of Molecular Physiology and Biophysics, The University of Iowa Carver College of Medicine, Iowa City, IA, United States
| | - Shivangi M Inamdar
- Department of Molecular Physiology and Biophysics, The University of Iowa Carver College of Medicine, Iowa City, IA, United States
| | - Zhen Huang
- Department of Neurology and Neuroscience, University of Wisconsin-Madison, Madison, WI, United States
| | - Maxim Sokolov
- Department of Ophthalmology, Biochemistry and Neuroscience, West Virginia University, Morgantown, WV, United States
| | - Kimberly Boyd
- Department of Molecular Physiology and Biophysics, The University of Iowa Carver College of Medicine, Iowa City, IA, United States
| | - Nikolai O Artemyev
- Department of Molecular Physiology and Biophysics, The University of Iowa Carver College of Medicine, Iowa City, IA, United States.,Department of Ophthalmology and Visual Sciences, Ophthalmology and Visual Sciences, The University of Iowa Carver College of Medicine, Iowa City, IA, United States
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11
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Seven AB, Hilger D, Papasergi-Scott MM, Zhang L, Qu Q, Kobilka BK, Tall GG, Skiniotis G. Structures of Gα Proteins in Complex with Their Chaperone Reveal Quality Control Mechanisms. Cell Rep 2020; 30:3699-3709.e6. [PMID: 32126208 PMCID: PMC7192526 DOI: 10.1016/j.celrep.2020.02.086] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2019] [Revised: 01/31/2020] [Accepted: 02/24/2020] [Indexed: 01/14/2023] Open
Abstract
Many chaperones promote nascent polypeptide folding followed by substrate release through ATP-dependent conformational changes. Here we show cryoEM structures of Gα subunit folding intermediates in complex with full-length Ric-8A, a unique chaperone-client system in which substrate release is facilitated by guanine nucleotide binding to the client G protein. The structures of Ric-8A-Gαi and Ric-8A-Gαq complexes reveal that the chaperone employs its extended C-terminal region to cradle the Ras-like domain of Gα, positioning the Ras core in contact with the Ric-8A core while engaging its switch2 nucleotide binding region. The C-terminal α5 helix of Gα is held away from the Ras-like domain through Ric-8A core domain interactions, which critically depend on recognition of the Gα C terminus by the chaperone. The structures, complemented with biochemical and cellular chaperoning data, support a folding quality control mechanism that ensures proper formation of the C-terminal α5 helix before allowing GTP-gated release of Gα from Ric-8A.
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Affiliation(s)
- Alpay Burak Seven
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Daniel Hilger
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA.
| | - Makaía M Papasergi-Scott
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Li Zhang
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Qianhui Qu
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Brian K Kobilka
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Gregory G Tall
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI 48109, USA.
| | - Georgios Skiniotis
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA.
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12
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Srivastava D, Artemyev NO. Ric-8A, a GEF, and a Chaperone for G Protein α-Subunits: Evidence for the Two-Faced Interface. Bioessays 2020; 42:e1900208. [PMID: 31967346 PMCID: PMC7034654 DOI: 10.1002/bies.201900208] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Revised: 12/30/2019] [Indexed: 12/21/2022]
Abstract
Resistance to inhibitors of cholinesterase 8A (Ric-8A) is a prominent non-receptor GEF and a chaperone of G protein α-subunits (Gα). Recent studies shed light on the structure of Ric-8A, providing insights into the mechanisms underlying its interaction with Gα. Ric-8A is composed of a core armadillo-like domain and a flexible C-terminal tail. Interaction of a conserved concave surface of its core domain with the Gα C-terminus appears to mediate formation of the initial Ric-8A/GαGDP intermediate, followed by the formation of a stable nucleotide-free complex. The latter event involves a large-scale dislocation of the Gα α5-helix that produces an extensive primary interface and disrupts the nucleotide-binding site of Gα. The distal portion of the C-terminal tail of Ric-8A forms a smaller secondary interface, which ostensibly binds the switch II region of Gα, facilitating binding of GTP. The two-site Gα interface of Ric-8A is distinct from that of GPCRs, and might have evolved to support the chaperone function of Ric-8A.
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Affiliation(s)
- Dhiraj Srivastava
- Department of Molecular Physiology and Biophysics, The University of Iowa Carver College of Medicine, Iowa City, IA 52242
| | - Nikolai O. Artemyev
- Department of Molecular Physiology and Biophysics, The University of Iowa Carver College of Medicine, Iowa City, IA 52242
- Department of Ophthalmology and Visual Sciences, The University of Iowa Carver College of Medicine, Iowa City, IA 52242
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13
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Gupte TM, Ritt M, Dysthe M, Malik RU, Sivaramakrishnan S. Minute-scale persistence of a GPCR conformation state triggered by non-cognate G protein interactions primes signaling. Nat Commun 2019; 10:4836. [PMID: 31645561 PMCID: PMC6811539 DOI: 10.1038/s41467-019-12755-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Accepted: 09/17/2019] [Indexed: 02/01/2023] Open
Abstract
Despite the crowded nature of the cellular milieu, ligand-GPCR-G protein interactions are traditionally viewed as spatially and temporally isolated events. In contrast, recent reports suggest the spatial and temporal coupling of receptor-effector interactions, with the potential to diversify downstream responses. In this study, we combine protein engineering of GPCR-G protein interactions with affinity sequestration and photo-manipulation of the crucial Gα C terminus, to demonstrate the temporal coupling of cognate and non-cognate G protein interactions through priming of the GPCR conformation. We find that interactions of the Gαs and Gαq C termini with the β2-adrenergic receptor (β2-AR), targeted at the G-protein-binding site, enhance Gs activation and cyclic AMP levels. β2-AR-Gα C termini interactions alter receptor conformation, which persists for ~90 s following Gα C terminus dissociation. Non-cognate G-protein expression levels impact cognate signaling in cells. Our study demonstrates temporal allostery in GPCRs, with implications for the modulation of downstream responses through the canonical G-protein-binding interface.
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Affiliation(s)
- Tejas M Gupte
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Twin-Cities, Minneapolis, Minnesota, 55455, USA
| | - Michael Ritt
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Twin-Cities, Minneapolis, Minnesota, 55455, USA
| | - Matthew Dysthe
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Twin-Cities, Minneapolis, Minnesota, 55455, USA
| | - Rabia U Malik
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Twin-Cities, Minneapolis, Minnesota, 55455, USA
| | - Sivaraj Sivaramakrishnan
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Twin-Cities, Minneapolis, Minnesota, 55455, USA.
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14
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Hudson BN, Jessup RE, Prahalad KK, Lyon AM. Gα q and the Phospholipase Cβ3 X-Y Linker Regulate Adsorption and Activity on Compressed Lipid Monolayers. Biochemistry 2019; 58:3454-3467. [PMID: 31322863 DOI: 10.1021/acs.biochem.9b00441] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Phospholipase Cβ (PLCβ) enzymes are peripheral membrane proteins required for normal cardiovascular function. PLCβ hydrolyzes phosphatidylinositol 4,5-bisphosphate, producing second messengers that increase intracellular Ca2+ level and activate protein kinase C. Under basal conditions, PLCβ is autoinhibited by its C-terminal domains and by the X-Y linker, which contains a stretch of conserved acidic residues required for interfacial activation. Following stimulation of G protein-coupled receptors, the heterotrimeric G protein subunit Gαq allosterically activates PLCβ and helps orient the activated complex at the membrane for efficient lipid hydrolysis. However, the molecular basis for how the PLCβ X-Y linker, its C-terminal domains, Gαq, and the membrane coordinately regulate activity is not well understood. Using compressed lipid monolayers and atomic force microscopy, we found that a highly conserved acidic region of the X-Y linker is sufficient to regulate adsorption. Regulation of adsorption and activity by the X-Y linker also occurs independently of the C-terminal domains. We next investigated whether Gαq-dependent activation of PLCβ altered interactions with the model membrane. Gαq increased PLCβ adsorption in a manner that was independent of the PLCβ regulatory elements and targeted adsorption to specific regions of the monolayer in the absence of the C-terminal domains. Thus, the mechanism of Gαq-dependent activation likely includes a spatial component.
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15
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Structural underpinnings of Ric8A function as a G-protein α-subunit chaperone and guanine-nucleotide exchange factor. Nat Commun 2019; 10:3084. [PMID: 31300652 PMCID: PMC6625990 DOI: 10.1038/s41467-019-11088-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Accepted: 06/21/2019] [Indexed: 02/03/2023] Open
Abstract
Resistance to inhibitors of cholinesterase 8A (Ric8A) is an essential regulator of G protein α-subunits (Gα), acting as a guanine nucleotide exchange factor and a chaperone. We report two crystal structures of Ric8A, one in the apo form and the other in complex with a tagged C-terminal fragment of Gα. These structures reveal two principal domains of Ric8A: an armadillo-fold core and a flexible C-terminal tail. Additionally, they show that the Gα C-terminus binds to a highly-conserved patch on the concave surface of the Ric8A armadillo-domain, with selectivity determinants residing in the Gα sequence. Biochemical analysis shows that the Ric8A C-terminal tail is critical for its stability and function. A model of the Ric8A/Gα complex derived from crosslinking mass spectrometry and molecular dynamics simulations suggests that the Ric8A C-terminal tail helps organize the GTP-binding site of Gα. This study lays the groundwork for understanding Ric8A function at the molecular level. Ric8A regulates G protein α-subunits (Gα) by acting as a guanine nucleotide exchange factor (GEF) and a Gα chaperone. Here, the authors solve the crystal structures of free and Gα fragment bound Ric8A, and provide insights into the structural basis for Ric8A’s GEF and chaperone functions.
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16
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Lapadula D, Farias E, Randolph CE, Purwin TJ, McGrath D, Charpentier TH, Zhang L, Wu S, Terai M, Sato T, Tall GG, Zhou N, Wedegaertner PB, Aplin AE, Aguirre-Ghiso J, Benovic JL. Effects of Oncogenic Gα q and Gα 11 Inhibition by FR900359 in Uveal Melanoma. Mol Cancer Res 2018; 17:963-973. [PMID: 30567972 DOI: 10.1158/1541-7786.mcr-18-0574] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Revised: 11/14/2018] [Accepted: 12/04/2018] [Indexed: 12/14/2022]
Abstract
Uveal melanoma is the most common intraocular tumor in adults and often metastasizes to the liver, leaving patients with few options. Recurrent activating mutations in the G proteins, Gαq and Gα11, are observed in approximately 93% of all uveal melanomas. Although therapeutic intervention of downstream Gαq/11 targets has been unsuccessful in treating uveal melanoma, we have found that the Gαq/11 inhibitor, FR900359 (FR), effectively inhibits oncogenic Gαq/11 signaling in uveal melanoma cells expressing either mutant Gαq or Gα11. Inhibition of oncogenic Gαq/11 by FR results in cell-cycle arrest and induction of apoptosis. Furthermore, colony formation is prevented by FR treatment of uveal melanoma cells in 3D-cell culture, providing promise for future in vivo studies. This suggests direct inhibition of activating Gαq/11 mutants may be a potential means of treating uveal melanoma. IMPLICATIONS: Oncogenic Gαq/11 inhibition by FR900359 may be a potential treatment option for those with uveal melanoma.
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Affiliation(s)
- Dominic Lapadula
- Department of Biochemistry and Molecular Biology, Cancer Cell Biology and Signaling Program, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Eduardo Farias
- Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York.,Department of Otolaryngology, Icahn School of Medicine at Mount Sinai, New York, New York.,Department of Oncological Sciences and Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Clinita E Randolph
- Department of Biochemistry and Molecular Biology, Cancer Cell Biology and Signaling Program, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Timothy J Purwin
- Department of Cancer Biology, Cancer Cell Biology and Signaling Program, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Dougan McGrath
- Department of Biochemistry and Molecular Biology, Cancer Cell Biology and Signaling Program, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Thomas H Charpentier
- Department of Biochemistry and Molecular Biology, Cancer Cell Biology and Signaling Program, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Lihong Zhang
- College of Life Sciences, Zhejiang University, Hangzhou, P.R. China
| | - Shihua Wu
- College of Life Sciences, Zhejiang University, Hangzhou, P.R. China
| | - Mizue Terai
- Department of Medical Oncology, Sidney Kimmel Medical College, Cancer Cell Biology and Signaling Program, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Takami Sato
- Department of Medical Oncology, Sidney Kimmel Medical College, Cancer Cell Biology and Signaling Program, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Gregory G Tall
- Department of Pharmacology, University of Michigan Medical Center, Ann Arbor, Michigan
| | - Naiming Zhou
- College of Life Sciences, Zhejiang University, Hangzhou, P.R. China
| | - Philip B Wedegaertner
- Department of Biochemistry and Molecular Biology, Cancer Cell Biology and Signaling Program, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Andrew E Aplin
- Department of Cancer Biology, Cancer Cell Biology and Signaling Program, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Julio Aguirre-Ghiso
- Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York.,Department of Otolaryngology, Icahn School of Medicine at Mount Sinai, New York, New York.,Department of Oncological Sciences and Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Jeffrey L Benovic
- Department of Biochemistry and Molecular Biology, Cancer Cell Biology and Signaling Program, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania.
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17
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Sokolov M, Yadav RP, Brooks C, Artemyev NO. Chaperones and retinal disorders. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2018; 114:85-117. [PMID: 30635087 DOI: 10.1016/bs.apcsb.2018.09.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Defects in protein folding and trafficking are a common cause of photoreceptor degeneration, causing blindness. Photoreceptor cells present an unusual challenge to the protein folding and transport machinery due to the high rate of protein synthesis, trafficking and the renewal of the outer segment, a primary cilium that has been modified into a specialized light-sensing compartment. Phototransduction components, such as rhodopsin and cGMP-phosphodiesterase, and multimeric ciliary transport complexes, such as the BBSome, are hotspots for mutations that disrupt proteostasis and lead to the death of photoreceptors. In this chapter, we review recent studies that advance our understanding of the chaperone and transport machinery of phototransduction proteins.
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Affiliation(s)
- Maxim Sokolov
- Department of Ophthalmology, West Virginia University, Morgantown, WV, United States
| | - Ravi P Yadav
- Department of Molecular Physiology and Biophysics, The University of Iowa Carver College of Medicine, Iowa City, IA, United States
| | - Celine Brooks
- Department of Ophthalmology, West Virginia University, Morgantown, WV, United States
| | - Nikolai O Artemyev
- Department of Molecular Physiology and Biophysics, The University of Iowa Carver College of Medicine, Iowa City, IA, United States; Department of Ophthalmology and Visual Sciences, The University of Iowa Carver College of Medicine, Iowa City, IA, United States.
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18
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Toro-Tapia G, Villaseca S, Beyer A, Roycroft A, Marcellini S, Mayor R, Torrejón M. The Ric-8A/Gα13/FAK signalling cascade controls focal adhesion formation during neural crest cell migration in Xenopus. Development 2018; 145:dev.164269. [PMID: 30297374 DOI: 10.1242/dev.164269] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Accepted: 09/23/2018] [Indexed: 12/22/2022]
Abstract
Ric-8A is a pleiotropic guanine nucleotide exchange factor involved in the activation of various heterotrimeric G-protein pathways during adulthood and early development. Here, we sought to determine the downstream effectors of Ric-8A during the migration of the vertebrate cranial neural crest (NC) cells. We show that the Gα13 knockdown phenocopies the Ric-8A morphant condition, causing actin cytoskeleton alteration, protrusion instability, and a strong reduction in the number and dynamics of focal adhesions. In addition, the overexpression of Gα13 is sufficient to rescue Ric-8A-depleted cells. Ric-8A and Gα13 physically interact and colocalize in protrusions of the cells leading edge. The focal adhesion kinase FAK colocalizes and interacts with the endogenous Gα13, and a constitutively active form of Src efficiently rescues the Gα13 morphant phenotype in NC cells. We propose that Ric-8A-mediated Gα13 signalling is required for proper cranial NC cell migration by regulating focal adhesion dynamics and protrusion formation.
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Affiliation(s)
- Gabriela Toro-Tapia
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Casilla 160-C, Concepción 4030000, Chile
| | - Soraya Villaseca
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Casilla 160-C, Concepción 4030000, Chile
| | - Andrea Beyer
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Casilla 160-C, Concepción 4030000, Chile
| | - Alice Roycroft
- Department of Cell and Developmental Biology, University College London, London WC1E 6BT, UK
| | - Sylvain Marcellini
- Departamento de Biología Cellular, Facultad de Ciencias Biológicas, Universidad de Concepción, Casilla 160-C, Concepción 4030000, Chile
| | - Roberto Mayor
- Department of Cell and Developmental Biology, University College London, London WC1E 6BT, UK
| | - Marcela Torrejón
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Casilla 160-C, Concepción 4030000, Chile
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19
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Yu W, Yu M, Papasergi-Scott MM, Tall GG. Production of Phosphorylated Ric-8A proteins using protein kinase CK2. Protein Expr Purif 2018; 154:98-103. [PMID: 30290220 DOI: 10.1016/j.pep.2018.10.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Revised: 09/26/2018] [Accepted: 10/01/2018] [Indexed: 01/13/2023]
Abstract
Resistance to Inhibitors of Cholinesterase-8 (Ric-8) proteins are molecular chaperones that fold heterotrimeric G protein α subunits shortly after biosynthesis. Ric-8 proteins also act as test tube guanine nucleotide exchange factors (GEF) that promote Gα subunit GDP for GTP exchange. The GEF and chaperoning activities of Ric-8A are regulated by phosphorylation of five serine and threonine residues within protein kinase CK2 consensus sites. The traditional way that Ric-8A proteins have been purified is from Spodoptera frugiperda (Sf9) or Trichoplusia ni (Tni) insect cells. Endogenous insect cell kinases do phosphorylate the critical regulatory sites of recombinant Ric-8A reasonably well, but there is batch-to-batch variability among recombinant Ric-8A preparations. Additionally, insect cell-production of some Ric-8 proteins with phosphosite alanine substitution mutations is proscribed as there seems to be interdependency of multi-site phosphorylation for functional protein production. Here, we present a method to produce wild type and phosphosite mutant Ric-8A proteins that are fully occupied with bound phosphate at each of the regulatory positions. Ric-8A proteins were expressed and purified from E. coli. Purified Ric-8A was phosphorylated in vitro with protein kinase CK2 and then re-isolated to remove kinase. The phosphorylated Ric-8A proteins were ∼99% pure and the completeness of phosphorylation was verified by chromatography, phos-tag SDS-PAGE mobility shifts, immunoblotting using phospho-site specific antibodies, and mass spectrometry analysis. E. coli-produced Ric-8A that was phosphorylated using this method promoted a faster rate of Gα subunit guanine nucleotide exchange than Ric-8A that was variably phosphorylated during production in insect cells.
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Affiliation(s)
- Wenxi Yu
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Maiya Yu
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | | | - Gregory G Tall
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI 48109, USA.
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20
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Papasergi-Scott MM, Stoveken HM, MacConnachie L, Chan PY, Gabay M, Wong D, Freeman RS, Beg AA, Tall GG. Dual phosphorylation of Ric-8A enhances its ability to mediate G protein α subunit folding and to stimulate guanine nucleotide exchange. Sci Signal 2018; 11:11/532/eaap8113. [PMID: 29844055 DOI: 10.1126/scisignal.aap8113] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Resistance to inhibitors of cholinesterase-8A (Ric-8A) and Ric-8B are essential biosynthetic chaperones for heterotrimeric G protein α subunits. We provide evidence for the direct regulation of Ric-8A cellular activity by dual phosphorylation. Using proteomics, Western blotting, and mutational analyses, we determined that Ric-8A was constitutively phosphorylated at five serines and threonines by the protein kinase CK2. Phosphorylation of Ser435 and Thr440 in rat Ric-8A (corresponding to Ser436 and Thr441 in human Ric-8A) was required for high-affinity binding to Gα subunits, efficient stimulation of Gα subunit guanine nucleotide exchange, and mediation of Gα subunit folding. The CK2 consensus sites that contain Ser435 and Thr440 are conserved in Ric-8 homologs from worms to mammals. We found that the homologous residues in mouse Ric-8B, Ser468 and Ser473, were also phosphorylated. Mutation of the genomic copy of ric-8 in Caenorhabditis elegans to encode alanine in the homologous sites resulted in characteristic ric-8 reduction-of-function phenotypes that are associated with defective Gq and Gs signaling, including reduced locomotion and defective egg laying. The C. elegans ric-8 phosphorylation site mutant phenotypes were partially rescued by chemical stimulation of Gq signaling. These results indicate that dual phosphorylation represents a critical form of conserved Ric-8 regulation and demonstrate that Ric-8 proteins are needed for effective Gα signaling. The position of the CK2-phosphorylated sites within a structural model of Ric-8A reveals that these sites contribute to a key acidic and negatively charged surface that may be important for its interactions with Gα subunits.
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Affiliation(s)
- Makaía M Papasergi-Scott
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Hannah M Stoveken
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Lauren MacConnachie
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Pui-Yee Chan
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Meital Gabay
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Dorothy Wong
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Robert S Freeman
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Asim A Beg
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Gregory G Tall
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI 48109, USA.
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21
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Tourdot BE, Stoveken H, Trumbo D, Yeung J, Kanthi Y, Edelstein LC, Bray PF, Tall GG, Holinstat M. Genetic Variant in Human PAR (Protease-Activated Receptor) 4 Enhances Thrombus Formation Resulting in Resistance to Antiplatelet Therapeutics. Arterioscler Thromb Vasc Biol 2018; 38:1632-1643. [PMID: 29748334 PMCID: PMC6023764 DOI: 10.1161/atvbaha.118.311112] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Accepted: 04/24/2018] [Indexed: 12/18/2022]
Abstract
OBJECTIVE Platelet activation after stimulation of PAR (protease-activated receptor) 4 is heightened in platelets from blacks compared with those from whites. The difference in PAR4 signaling by race is partially explained by a single-nucleotide variant in PAR4 encoding for either an alanine or threonine at amino acid 120 in the second transmembrane domain. The current study sought to determine whether the difference in PAR4 signaling by this PAR4 variant is because of biased Gq signaling and whether the difference in PAR4 activity results in resistance to traditional antiplatelet intervention. APPROACH AND RESULTS Membranes expressing human PAR4-120 variants were reconstituted with either Gq or G13 to determine the kinetics of G protein activation. The kinetics of Gq and G13 activation were both increased in membranes expressing PAR4-Thr120 compared with those expressing PAR4-Ala120. Further, inhibiting PAR4-mediated platelet activation by targeting COX (cyclooxygenase) and P2Y12 receptor was less effective in platelets from subjects expressing PAR4-Thr120 compared with PAR4-Ala120. Additionally, ex vivo thrombus formation in whole blood was evaluated at high shear to determine the relationship between PAR4 variant expression and response to antiplatelet drugs. Ex vivo thrombus formation was enhanced in blood from subjects expressing PAR4-Thr120 in the presence or absence of antiplatelet therapy. CONCLUSIONS Together, these data support that the signaling difference by the PAR4-120 variant results in the enhancement of both Gq and G13 activation and an increase in thrombus formation resulting in a potential resistance to traditional antiplatelet therapies targeting COX-1 and the P2Y12 receptor.
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Affiliation(s)
- Benjamin E Tourdot
- From the Department of Pharmacology (B.E.T., H.S., D.T., J.Y., G.G.T., M.H.)
| | - Hannah Stoveken
- From the Department of Pharmacology (B.E.T., H.S., D.T., J.Y., G.G.T., M.H.)
| | - Derek Trumbo
- From the Department of Pharmacology (B.E.T., H.S., D.T., J.Y., G.G.T., M.H.)
| | - Jennifer Yeung
- From the Department of Pharmacology (B.E.T., H.S., D.T., J.Y., G.G.T., M.H.)
| | - Yogendra Kanthi
- Division of Cardiovascular Medicine, Department of Internal Medicine (Y.K., M.H.), University of Michigan, Ann Arbor.,Ann Arbor Veterans Affairs Health System, MI (Y.K.)
| | - Leonard C Edelstein
- Department of Medicine, Cardeza Foundation for Hematologic Research, Thomas Jefferson University, Philadelphia, PA (L.C.E.)
| | - Paul F Bray
- Department of Internal Medicine, University of Utah, Salt Lake City (P.F.B.)
| | - Gregory G Tall
- From the Department of Pharmacology (B.E.T., H.S., D.T., J.Y., G.G.T., M.H.)
| | - Michael Holinstat
- From the Department of Pharmacology (B.E.T., H.S., D.T., J.Y., G.G.T., M.H.) .,Division of Cardiovascular Medicine, Department of Internal Medicine (Y.K., M.H.), University of Michigan, Ann Arbor
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22
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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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23
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Stoveken HM, Larsen SD, Smrcka AV, Tall GG. Gedunin- and Khivorin-Derivatives Are Small-Molecule Partial Agonists for Adhesion G Protein-Coupled Receptors GPR56/ADGRG1 and GPR114/ADGRG5. Mol Pharmacol 2018; 93:477-488. [PMID: 29476042 DOI: 10.1124/mol.117.111476] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Accepted: 02/22/2018] [Indexed: 12/26/2022] Open
Abstract
Adhesion G protein-coupled receptors (aGPCRs) have emerged as potential therapeutic targets in multiple cancers and in neurologic diseases. However, there are few modulatory compounds that act on these receptors. The majority of aGPCRs are orphans and a general activation mechanism has only recently been defined: aGPCRs are activated by a tethered agonist. aGPCRs constitutively cleave themselves during biosynthesis to generated two-part receptors comprising an extracellular domain (ECD) and a 7-transmembrane spanning domain (7TM). ECD dissociation reveals the tethered agonist initiating G protein signaling. Synthetic peptides that mimic the tethered agonist region can activate aGPCRs. We hypothesized that small molecules could act in the same way as peptide agonists. High throughput screening of the 2000-compound Spectrum Collection library using the serum response element luciferase gene reporter assay revealed two related classes of small molecules that could activate the aGPCR GPR56/ADGRG1. The most potent compound identified was 3-α-acetoxydihydrodeoxygedunin, or 3-α-DOG. 3-α-DOG activated engineered, low-activity GPR56 7TM in independent biochemical and cell-based assays with an EC50 of ∼5 μM. The compound also activated a subset of aGPCRs but not two class A GPCRs tested. The mode of 3-α-DOG-mediated receptor activation is that of partial agonist. 3-α-DOG activated GPR56 less efficaciously than peptide agonist and could antagonize both the peptide agonist and the endogenous tethered agonist, which are pharmacological hallmarks of partial agonists. Taken together, we have uncovered a novel group of aGPCR partial agonists that will serve as invaluable resources for understanding this unique class receptors.
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Affiliation(s)
- Hannah M Stoveken
- Departments of Pharmacology (H.M.S., A.V.S., G.G.T.) and Medicinal Chemistry (S.D.L.), University of Michigan, Ann Arbor, Michigan
| | - Scott D Larsen
- Departments of Pharmacology (H.M.S., A.V.S., G.G.T.) and Medicinal Chemistry (S.D.L.), University of Michigan, Ann Arbor, Michigan
| | - Alan V Smrcka
- Departments of Pharmacology (H.M.S., A.V.S., G.G.T.) and Medicinal Chemistry (S.D.L.), University of Michigan, Ann Arbor, Michigan
| | - Gregory G Tall
- Departments of Pharmacology (H.M.S., A.V.S., G.G.T.) and Medicinal Chemistry (S.D.L.), University of Michigan, Ann Arbor, Michigan
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24
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Ben Khemis I, Mechi N, Ben Lamine A. Stereochemical study of mouse muscone receptor MOR215-1 and vibrational theory based on statistical physics formalism. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2018; 136:54-60. [PMID: 29438653 DOI: 10.1016/j.pbiomolbio.2018.02.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Revised: 02/02/2018] [Accepted: 02/09/2018] [Indexed: 11/29/2022]
Abstract
In the biosensor system, olfactory receptor sites could be activated by odorant molecules and then the biological interactions are converted into electrical signals by a signal transduction cascade that leads the toopening of ion channels, generating a current that leads into the cilia and depolarizes the membrane. The aim of this paper is to present a new investigation that allows determining the olfactory band using a monolayer adsorption with identical sites modeling which may also describe the static and the dynamic sensitivities through the expression of the olfactory response. Moreover, knowing the size of receptor site in olfactory sensory neurons provides valuable information about the relationship between molecular structure and biological activity. The determination of microreceptors and mesoreceptors is mostly carried out via physical adsorption and the radius is calculated using the Kelvin equation. The mean values of radius obtained from the maximum of the receptor size distributions peaks are 4 nm for ℓ-muscone and 6 nm for d-muscone.
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Affiliation(s)
- Ismahene Ben Khemis
- Laboratory of Quantum Physics UR 11 ES 54, Faculty of Sciences of Monastir, Environnement Street, 5019, Monastir, Tunisia.
| | - Nesrine Mechi
- Laboratory of Quantum Physics UR 11 ES 54, Faculty of Sciences of Monastir, Environnement Street, 5019, Monastir, Tunisia
| | - Abdelmottaleb Ben Lamine
- Laboratory of Quantum Physics UR 11 ES 54, Faculty of Sciences of Monastir, Environnement Street, 5019, Monastir, Tunisia.
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25
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Yano H, Provasi D, Cai NS, Filizola M, Ferré S, Javitch JA. Development of novel biosensors to study receptor-mediated activation of the G-protein α subunits G s and G olf. J Biol Chem 2017; 292:19989-19998. [PMID: 29042444 PMCID: PMC5723988 DOI: 10.1074/jbc.m117.800698] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Revised: 10/02/2017] [Indexed: 11/06/2022] Open
Abstract
Gαs (Gs) and Gαolf (Golf) are highly homologous G-protein α subunits that activate adenylate cyclase, thereby serving as crucial mediators of intracellular signaling. Because of their dramatically different brain expression patterns, we studied similarities and differences between their activation processes with the aim of comparing their receptor coupling mechanisms. We engineered novel luciferase- and Venus-fused Gα constructs that can be used in bioluminescence resonance energy transfer assays. In conjunction with molecular simulations, these novel biosensors were used to determine receptor activation-induced changes in conformation. Relative movements in Gs were consistent with the crystal structure of β2 adrenergic receptor in complex with Gs Conformational changes in Golf activation are shown to be similar to those in Gs Overall the current study reveals general similarities between Gs and Golf activation at the molecular level and provides a novel set of tools to search for Gs- and Golf-specific receptor pharmacology. In view of the wide functional and pharmacological roles of Gs- and Golf-coupled dopamine D1 receptor and adenosine A2A receptor in the brain and other organs, elucidating their differential structure-function relationships with Gs and Golf might provide new approaches for the treatment of a variety of neuropsychiatric disorders. In particular, these novel biosensors can be used to reveal potentially therapeutic dopamine D1 receptor and adenosine A2A receptor ligands with functionally selective properties between Gs and Golf signaling.
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Affiliation(s)
- Hideaki Yano
- National Institute on Drug Abuse, Baltimore, Maryland 21224.
| | - Davide Provasi
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, New York 10029
| | - Ning Sheng Cai
- National Institute on Drug Abuse, Baltimore, Maryland 21224
| | - Marta Filizola
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, New York 10029
| | - Sergi Ferré
- National Institute on Drug Abuse, Baltimore, Maryland 21224
| | - Jonathan A Javitch
- Departments of Psychiatry and Pharmacology, College of Physicians & Surgeons, Columbia University, New York, New York 10032; Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, New York 10032.
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26
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Conditional Deletion of Ric-8b in Olfactory Sensory Neurons Leads to Olfactory Impairment. J Neurosci 2017; 37:12202-12213. [PMID: 29118104 DOI: 10.1523/jneurosci.0943-17.2017] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Revised: 10/25/2017] [Accepted: 10/29/2017] [Indexed: 11/21/2022] Open
Abstract
The olfactory system can discriminate a vast number of odorants. This ability derives from the existence of a large family of odorant receptors expressed in the cilia of the olfactory sensory neurons. Odorant receptors signal through the olfactory-specific G-protein subunit, Gαolf. Ric-8b, a guanine nucleotide exchange factor, interacts with Gαolf and can amplify odorant receptor signal transduction in vitro To explore the function of Ric-8b in vivo, we generated a tissue specific knock-out mouse by crossing OMP-Cre transgenic mice to Ric-8b floxed mice. We found that olfactory-specific Ric-8b knock-out mice of mixed sex do not express the Gαolf protein in the olfactory epithelium. We also found that in these mice, the mature olfactory sensory neuron layer is reduced, and that olfactory sensory neurons show increased rate of cell death compared with wild-type mice. Finally, behavioral tests showed that the olfactory-specific Ric-8b knock-out mice show an impaired sense of smell, even though their motivation and mobility behaviors remain normal.SIGNIFICANCE STATEMENT Ric-8b is a guanine nucleotide exchange factor (GEF) expressed in the olfactory epithelium and in the striatum. Ric-8b interacts with the olfactory Gαolf subunit, and can amplify odorant signaling through odorant receptors in vitro However, the functional significance of this GEF in the olfactory neurons in vivo remains unknown. We report that deletion of Ric-8b in olfactory sensory neurons prevents stable expression of Gαolf. In addition, we demonstrate that olfactory neurons lacking Ric-8b (and consequently Gαolf) are more susceptible to cell death. Ric-8b conditional knock-out mice display impaired olfactory guided behavior. Our results reveal that Ric-8b is essential for olfactory function, and suggest that it may also be essential for Gαolf-dependent functions in the brain.
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27
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Navaratnarajah P, Gershenson A, Ross EM. The binding of activated Gα q to phospholipase C-β exhibits anomalous affinity. J Biol Chem 2017; 292:16787-16801. [PMID: 28842497 DOI: 10.1074/jbc.m117.809673] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Revised: 08/22/2017] [Indexed: 01/01/2023] Open
Abstract
Upon activation by the Gq family of Gα subunits, Gβγ subunits, and some Rho family GTPases, phospholipase C-β (PLC-β) isoforms hydrolyze phosphatidylinositol 4,5-bisphosphate to the second messengers inositol 1,4,5-trisphosphate and diacylglycerol. PLC-β isoforms also function as GTPase-activating proteins, potentiating Gq deactivation. To elucidate the mechanism of this mutual regulation, we measured the thermodynamics and kinetics of PLC-β3 binding to Gαq FRET and fluorescence correlation spectroscopy, two physically distinct methods, both yielded Kd values of about 200 nm for PLC-β3-Gαq binding. This Kd is 50-100 times greater than the EC50 for Gαq-mediated PLC-β3 activation and for the Gαq GTPase-activating protein activity of PLC-β. The measured Kd was not altered either by the presence of phospholipid vesicles, phosphatidylinositol 4,5-bisphosphate and Ca2+, or by the identity of the fluorescent labels. FRET-based kinetic measurements were also consistent with a Kd of 200 nm We determined that PLC-β3 hysteresis, whereby PLC-β3 remains active for some time following either Gαq-PLC-β3 dissociation or PLC-β3-potentiated Gαq deactivation, is not sufficient to explain the observed discrepancy between EC50 and Kd These results indicate that the mechanism by which Gαq and PLC-β3 mutually regulate each other is far more complex than a simple, two-state allosteric model and instead is probably kinetically determined.
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Affiliation(s)
- Punya Navaratnarajah
- From the Department of Pharmacology and Green Center for Systems Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9041 and
| | - Anne Gershenson
- the Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, Massachusetts 01003-9292
| | - Elliott M Ross
- From the Department of Pharmacology and Green Center for Systems Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9041 and
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28
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Toro-Tapia G, Villaseca S, Leal JI, Beyer A, Fuentealba J, Torrejón M. Xenopus as a model organism to study heterotrimeric G-protein pathway during collective cell migration of neural crest. Genesis 2017; 55. [PMID: 28095644 DOI: 10.1002/dvg.23008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Revised: 11/22/2016] [Accepted: 11/24/2016] [Indexed: 01/03/2023]
Abstract
Collective cell migration is essential in many fundamental aspects of normal development, like morphogenesis, organ formation, wound healing, and immune responses, as well as in the etiology of severe pathologies, like cancer metastasis. In spite of the huge amount of data accumulated on cell migration, such a complex process involves many molecular actors, some of which still remain to be functionally characterized. One of these signals is the heterotrimeric G-protein pathway that has been studied mainly in gastrulation movements. Recently we have reported that Ric-8A, a GEF for Gα proteins, plays an important role in neural crest migration in Xenopus development. Xenopus neural crest cells, a highly migratory embryonic cell population induced at the border of the neural plate that migrates extensively in order to differentiate in other tissues during development, have become a good model to understand the dynamics that regulate cell migration. In this review, we aim to provide sufficient evidence supporting how useful Xenopus model with its different tools, such as explants and transplants, paired with improved in vivo imaging techniques, will allow us to tackle the multiple signaling mechanisms involved in neural crest cell migration.
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Affiliation(s)
- G Toro-Tapia
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Casilla 160-C, Concepción, Chile
| | - S Villaseca
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Casilla 160-C, Concepción, Chile
| | - J I Leal
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Casilla 160-C, Concepción, Chile
| | - A Beyer
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Casilla 160-C, Concepción, Chile
| | - J Fuentealba
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Casilla 160-C, Concepción, Chile
| | - M Torrejón
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Casilla 160-C, Concepción, Chile
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29
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Nehmé R, Carpenter B, Singhal A, Strege A, Edwards PC, White CF, Du H, Grisshammer R, Tate CG. Mini-G proteins: Novel tools for studying GPCRs in their active conformation. PLoS One 2017; 12:e0175642. [PMID: 28426733 PMCID: PMC5398546 DOI: 10.1371/journal.pone.0175642] [Citation(s) in RCA: 170] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Accepted: 03/29/2017] [Indexed: 01/08/2023] Open
Abstract
Mini-G proteins are the engineered GTPase domains of Gα subunits. They couple to GPCRs and recapitulate the increase in agonist affinity observed upon coupling of a native heterotrimeric G protein. Given the small size and stability of mini-G proteins, and their ease of expression and purification, they are ideal for biophysical studies of GPCRs in their fully active state. The first mini-G protein developed was mini-Gs. Here we extend the family of mini-G proteins to include mini-Golf, mini-Gi1, mini-Go1 and the chimeras mini-Gs/q and mini-Gs/i. The mini-G proteins were shown to couple to relevant GPCRs and to form stable complexes with purified receptors that could be purified by size exclusion chromatography. Agonist-bound GPCRs coupled to a mini-G protein showed higher thermal stability compared to the agonist-bound receptor alone. Fusion of GFP at the N-terminus of mini-G proteins allowed receptor coupling to be monitored by fluorescence-detection size exclusion chromatography (FSEC) and, in a separate assay, the affinity of mini-G protein binding to detergent-solubilised receptors was determined. This work provides the foundation for the development of any mini-G protein and, ultimately, for the structure determination of GPCRs in a fully active state.
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Affiliation(s)
- Rony Nehmé
- MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Byron Carpenter
- MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Ankita Singhal
- MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Annette Strege
- MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
| | | | - Courtney F. White
- Membrane Protein Structure Function Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Department of Health and Human Services, Rockville, United States of America
| | - Haijuan Du
- Membrane Protein Structure Function Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Department of Health and Human Services, Rockville, United States of America
| | - Reinhard Grisshammer
- Membrane Protein Structure Function Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Department of Health and Human Services, Rockville, United States of America
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Dessauer CW, Watts VJ, Ostrom RS, Conti M, Dove S, Seifert R. International Union of Basic and Clinical Pharmacology. CI. Structures and Small Molecule Modulators of Mammalian Adenylyl Cyclases. Pharmacol Rev 2017; 69:93-139. [PMID: 28255005 PMCID: PMC5394921 DOI: 10.1124/pr.116.013078] [Citation(s) in RCA: 128] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Adenylyl cyclases (ACs) generate the second messenger cAMP from ATP. Mammalian cells express nine transmembrane AC (mAC) isoforms (AC1-9) and a soluble AC (sAC, also referred to as AC10). This review will largely focus on mACs. mACs are activated by the G-protein Gαs and regulated by multiple mechanisms. mACs are differentially expressed in tissues and regulate numerous and diverse cell functions. mACs localize in distinct membrane compartments and form signaling complexes. sAC is activated by bicarbonate with physiologic roles first described in testis. Crystal structures of the catalytic core of a hybrid mAC and sAC are available. These structures provide detailed insights into the catalytic mechanism and constitute the basis for the development of isoform-selective activators and inhibitors. Although potent competitive and noncompetitive mAC inhibitors are available, it is challenging to obtain compounds with high isoform selectivity due to the conservation of the catalytic core. Accordingly, caution must be exerted with the interpretation of intact-cell studies. The development of isoform-selective activators, the plant diterpene forskolin being the starting compound, has been equally challenging. There is no known endogenous ligand for the forskolin binding site. Recently, development of selective sAC inhibitors was reported. An emerging field is the association of AC gene polymorphisms with human diseases. For example, mutations in the AC5 gene (ADCY5) cause hyperkinetic extrapyramidal motor disorders. Overall, in contrast to the guanylyl cyclase field, our understanding of the (patho)physiology of AC isoforms and the development of clinically useful drugs targeting ACs is still in its infancy.
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Affiliation(s)
- Carmen W Dessauer
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Sciences Center at Houston, Houston, Texas (C.W.D.); Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana (V.J.W.); Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, California (R.S.O.); Center for Reproductive Sciences, University of California San Francisco, San Francisco, California (M.C.); Institute of Pharmacy, University of Regensburg, Regensburg, Germany (S.D.); and Institute of Pharmacology, Hannover Medical School, Hannover, Germany (R.S.)
| | - Val J Watts
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Sciences Center at Houston, Houston, Texas (C.W.D.); Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana (V.J.W.); Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, California (R.S.O.); Center for Reproductive Sciences, University of California San Francisco, San Francisco, California (M.C.); Institute of Pharmacy, University of Regensburg, Regensburg, Germany (S.D.); and Institute of Pharmacology, Hannover Medical School, Hannover, Germany (R.S.)
| | - Rennolds S Ostrom
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Sciences Center at Houston, Houston, Texas (C.W.D.); Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana (V.J.W.); Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, California (R.S.O.); Center for Reproductive Sciences, University of California San Francisco, San Francisco, California (M.C.); Institute of Pharmacy, University of Regensburg, Regensburg, Germany (S.D.); and Institute of Pharmacology, Hannover Medical School, Hannover, Germany (R.S.)
| | - Marco Conti
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Sciences Center at Houston, Houston, Texas (C.W.D.); Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana (V.J.W.); Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, California (R.S.O.); Center for Reproductive Sciences, University of California San Francisco, San Francisco, California (M.C.); Institute of Pharmacy, University of Regensburg, Regensburg, Germany (S.D.); and Institute of Pharmacology, Hannover Medical School, Hannover, Germany (R.S.)
| | - Stefan Dove
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Sciences Center at Houston, Houston, Texas (C.W.D.); Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana (V.J.W.); Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, California (R.S.O.); Center for Reproductive Sciences, University of California San Francisco, San Francisco, California (M.C.); Institute of Pharmacy, University of Regensburg, Regensburg, Germany (S.D.); and Institute of Pharmacology, Hannover Medical School, Hannover, Germany (R.S.)
| | - Roland Seifert
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Sciences Center at Houston, Houston, Texas (C.W.D.); Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana (V.J.W.); Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, California (R.S.O.); Center for Reproductive Sciences, University of California San Francisco, San Francisco, California (M.C.); Institute of Pharmacy, University of Regensburg, Regensburg, Germany (S.D.); and Institute of Pharmacology, Hannover Medical School, Hannover, Germany (R.S.)
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Ric-8A gene deletion or phorbol ester suppresses tumorigenesis in a mouse model of GNAQ(Q209L)-driven melanoma. Oncogenesis 2016; 5:e236. [PMID: 27348266 PMCID: PMC4945744 DOI: 10.1038/oncsis.2016.45] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Revised: 05/06/2016] [Accepted: 05/11/2016] [Indexed: 01/19/2023] Open
Abstract
The heterotrimeric G protein α subunit oncogenes GNAQ or GNA11 carry Q209X or R183X activating mutations and are present with ~90% frequency in human uveal melanomas. Forced expression of GNAQ/11Q209L in melanocytes is sufficient to drive metastatic melanoma in immune-compromised mice. No known drugs directly target these oncogenic G proteins. Ric-8A is the molecular chaperone that selectively folds Gαq/i/13 subunits. Targeting Ric-8A serves as a rational, yet unexplored approach to reduce the functional abundance of oncogenic Gαq/11 in order to blunt cancer signaling. Here, using mouse melanocyte cell graft tumorigenesis models, we determined that Ric-8A genetic ablation attenuated the abundance and melanoma-driving potential of Gαq-Q209L. A new conditional Ric-8AFlox/Flox; Rosa-CreER+/− mouse strain was derived and used as a tissue source to culture an immortalized, tamoxifen-inducible Ric-8A knockout melanocyte cell line that required 12-O-tetradecanoylphorbol-13-acetate (TPA, phorbol ester) for growth. The cell line failed to grow tumors when grafted into immune-compromised mice regardless of Ric-8A expression. Stable expression of human GNAQQ209L, but not GNAQWT in the cell line promoted TPA-independent cell proliferation, and upon cell grafting in mice, the initiation and robust growth of darkly-pigmented melanoma tumors. Deletion of Ric-8A in GNAQQ209L cells restored TPA-dependent growth, reduced Gαq-Q209L below detectable levels and completely mitigated tumorigenesis from primary or secondary cell line grafts. Interestingly, TPA treatment of cultured GNAQQ209L cells or host animals grafted with GNAQQ209L cells also sharply reduced Gαq-Q209L abundance and tumorigenic capacity. Finally, tumorigenesis initiated from GNAQQ209L cell grafts, followed by host mouse systemic tamoxifen treatment to delete Ric-8A in the grafted cells completely abrogated GNAQQ209L-driven tumor progression unless a stable human RIC-8A transgene was used to rescue the floxed Ric-8A alleles. Our work defines two new rational targets that may be developed as potential uveal melanoma therapies through reduction of Gαq/11-Q209L oncoprotein abundance: (1) Ric-8A inhibition and (2) phorbol ester treatment.
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Stoveken HM, Bahr LL, Anders MW, Wojtovich AP, Smrcka AV, Tall GG. Dihydromunduletone Is a Small-Molecule Selective Adhesion G Protein-Coupled Receptor Antagonist. Mol Pharmacol 2016; 90:214-24. [PMID: 27338081 DOI: 10.1124/mol.116.104828] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Accepted: 06/10/2016] [Indexed: 12/21/2022] Open
Abstract
Adhesion G protein-coupled receptors (aGPCRs) have emerging roles in development and tissue maintenance and is the most prevalent GPCR subclass mutated in human cancers, but to date, no drugs have been developed to target them in any disease. aGPCR extracellular domains contain a conserved subdomain that mediates self-cleavage proximal to the start of the 7-transmembrane domain (7TM). The two receptor protomers, extracellular domain and amino terminal fragment (NTF), and the 7TM or C-terminal fragment remain noncovalently bound at the plasma membrane in a low-activity state. We recently demonstrated that NTF dissociation liberates the 7TM N-terminal stalk, which acts as a tethered-peptide agonist permitting receptor-dependent heterotrimeric G protein activation. In many cases, natural aGPCR ligands are extracellular matrix proteins that dissociate the NTF to reveal the tethered agonist. Given the perceived difficulty in modifying extracellular matrix proteins to create aGPCR probes, we developed a serum response element (SRE)-luciferase-based screening approach to identify GPR56/ADGRG1 small-molecule inhibitors. A 2000-compound library comprising known drugs and natural products was screened for GPR56-dependent SRE activation inhibitors that did not inhibit constitutively active Gα13-dependent SRE activation. Dihydromunduletone (DHM), a rotenoid derivative, was validated using cell-free aGPCR/heterotrimeric G protein guanosine 5'-3-O-(thio)triphosphate binding reconstitution assays. DHM inhibited GPR56 and GPR114/ADGRG5, which have similar tethered agonists, but not the aGPCR GPR110/ADGRF1, M3 muscarinic acetylcholine, or β2 adrenergic GPCRs. DHM inhibited tethered peptide agonist-stimulated and synthetic peptide agonist-stimulated GPR56 but did not inhibit basal activity, demonstrating that it antagonizes the peptide agonist. DHM is a novel aGPCR antagonist and potentially useful chemical probe that may be developed as a future aGPCR therapeutic.
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Affiliation(s)
- Hannah M Stoveken
- Department of Pharmacology and Physiology (H.M.S., L.L.B., M.W.A., A.P.W., A.V.S.), and Department of Anesthesiology (L.L.B., A.P.W.), University of Rochester Medical Center, Rochester, New York; and Department of Pharmacology, University of Michigan, Ann Arbor, Michigan (G.G.T.)
| | - Laura L Bahr
- Department of Pharmacology and Physiology (H.M.S., L.L.B., M.W.A., A.P.W., A.V.S.), and Department of Anesthesiology (L.L.B., A.P.W.), University of Rochester Medical Center, Rochester, New York; and Department of Pharmacology, University of Michigan, Ann Arbor, Michigan (G.G.T.)
| | - M W Anders
- Department of Pharmacology and Physiology (H.M.S., L.L.B., M.W.A., A.P.W., A.V.S.), and Department of Anesthesiology (L.L.B., A.P.W.), University of Rochester Medical Center, Rochester, New York; and Department of Pharmacology, University of Michigan, Ann Arbor, Michigan (G.G.T.)
| | - Andrew P Wojtovich
- Department of Pharmacology and Physiology (H.M.S., L.L.B., M.W.A., A.P.W., A.V.S.), and Department of Anesthesiology (L.L.B., A.P.W.), University of Rochester Medical Center, Rochester, New York; and Department of Pharmacology, University of Michigan, Ann Arbor, Michigan (G.G.T.)
| | - Alan V Smrcka
- Department of Pharmacology and Physiology (H.M.S., L.L.B., M.W.A., A.P.W., A.V.S.), and Department of Anesthesiology (L.L.B., A.P.W.), University of Rochester Medical Center, Rochester, New York; and Department of Pharmacology, University of Michigan, Ann Arbor, Michigan (G.G.T.)
| | - Gregory G Tall
- Department of Pharmacology and Physiology (H.M.S., L.L.B., M.W.A., A.P.W., A.V.S.), and Department of Anesthesiology (L.L.B., A.P.W.), University of Rochester Medical Center, Rochester, New York; and Department of Pharmacology, University of Michigan, Ann Arbor, Michigan (G.G.T.)
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Kadamur G, Ross EM. Intrinsic Pleckstrin Homology (PH) Domain Motion in Phospholipase C-β Exposes a Gβγ Protein Binding Site. J Biol Chem 2016; 291:11394-406. [PMID: 27002154 DOI: 10.1074/jbc.m116.723940] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Indexed: 11/06/2022] Open
Abstract
Mammalian phospholipase C-β (PLC-β) isoforms are stimulated by heterotrimeric G protein subunits and members of the Rho GTPase family of small G proteins. Although recent structural studies showed how Gαq and Rac1 bind PLC-β, there is a lack of consensus regarding the Gβγ binding site in PLC-β. Using FRET between cerulean fluorescent protein-labeled Gβγ and the Alexa Fluor 594-labeled PLC-β pleckstrin homology (PH) domain, we demonstrate that the PH domain is the minimal Gβγ binding region in PLC-β3. We show that the isolated PH domain can compete with full-length PLC-β3 for binding Gβγ but not Gαq, Using sequence conservation, structural analyses, and mutagenesis, we identify a hydrophobic face of the PLC-β PH domain as the Gβγ binding interface. This PH domain surface is not solvent-exposed in crystal structures of PLC-β, necessitating conformational rearrangement to allow Gβγ binding. Blocking PH domain motion in PLC-β by cross-linking it to the EF hand domain inhibits stimulation by Gβγ without altering basal activity or Gαq response. The fraction of PLC-β cross-linked is proportional to the fractional loss of Gβγ response. Cross-linked PLC-β does not bind Gβγ in a FRET-based Gβγ-PLC-β binding assay. We propose that unliganded PLC-β exists in equilibrium between a closed conformation observed in crystal structures and an open conformation where the PH domain moves away from the EF hands. Therefore, intrinsic movement of the PH domain in PLC-β modulates Gβγ access to its binding site.
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Affiliation(s)
- Ganesh Kadamur
- From the Department of Pharmacology, Molecular Biophysics Graduate Program, and Green Center for Systems Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Elliott M Ross
- From the Department of Pharmacology, Molecular Biophysics Graduate Program, and Green Center for Systems Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390
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Sánchez-Fernández G, Cabezudo S, Caballero Á, García-Hoz C, Tall GG, Klett J, Michnick SW, Mayor F, Ribas C. Protein Kinase C ζ Interacts with a Novel Binding Region of Gαq to Act as a Functional Effector. J Biol Chem 2016; 291:9513-25. [PMID: 26887939 DOI: 10.1074/jbc.m115.684308] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Indexed: 12/13/2022] Open
Abstract
Heterotrimeric G proteins play an essential role in the initiation of G protein-coupled receptor (GPCR) signaling through specific interactions with a variety of cellular effectors. We have recently reported that GPCR activation promotes a direct interaction between Gαq and protein kinase C ζ (PKCζ), leading to the stimulation of the ERK5 pathway independent of the canonical effector PLCβ. We report herein that the activation-dependent Gαq/PKCζ complex involves the basic PB1-type II domain of PKCζ and a novel interaction module in Gαq different from the classical effector-binding site. Point mutations in this Gαq region completely abrogate ERK5 phosphorylation, indicating that Gαq/PKCζ association is required for the activation of the pathway. Indeed, PKCζ was demonstrated to directly bind ERK5 thus acting as a scaffold between Gαq and ERK5 upon GPCR activation. The inhibition of these protein complexes by G protein-coupled receptor kinase 2, a known Gαq modulator, led to a complete abrogation of ERK5 stimulation. Finally, we reveal that Gαq/PKCζ complexes link Gαq to apoptotic cell death pathways. Our data suggest that the interaction between this novel region in Gαq and the effector PKCζ is a key event in Gαq signaling.
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Affiliation(s)
- Guzmán Sánchez-Fernández
- From the Departamento de Biología Molecular and Centro de Biología Molecular "Severo Ochoa," CSIC-UAM, Universidad Autónoma de Madrid, 28049-Madrid, Spain, Instituto de Investigación Sanitaria La Princesa, 29006-Madrid, Spain, Department of Pharmacology, Max-Planck-Institute for Heart and Lung Research, 61231 Bad Nauheim, Germany
| | - Sofía Cabezudo
- From the Departamento de Biología Molecular and Centro de Biología Molecular "Severo Ochoa," CSIC-UAM, Universidad Autónoma de Madrid, 28049-Madrid, Spain, Instituto de Investigación Sanitaria La Princesa, 29006-Madrid, Spain
| | - Álvaro Caballero
- From the Departamento de Biología Molecular and Centro de Biología Molecular "Severo Ochoa," CSIC-UAM, Universidad Autónoma de Madrid, 28049-Madrid, Spain, Instituto de Investigación Sanitaria La Princesa, 29006-Madrid, Spain
| | - Carlota García-Hoz
- From the Departamento de Biología Molecular and Centro de Biología Molecular "Severo Ochoa," CSIC-UAM, Universidad Autónoma de Madrid, 28049-Madrid, Spain, Instituto de Investigación Sanitaria La Princesa, 29006-Madrid, Spain
| | - Gregory G Tall
- Departments of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, New York 14642, and
| | - Javier Klett
- From the Departamento de Biología Molecular and Centro de Biología Molecular "Severo Ochoa," CSIC-UAM, Universidad Autónoma de Madrid, 28049-Madrid, Spain
| | - Stephen W Michnick
- Département de Biochimie, Université de Montréal, C.P. 6128, Succursale centre-ville, Montréal, Québec, H3C 3J7 Canada
| | - Federico Mayor
- From the Departamento de Biología Molecular and Centro de Biología Molecular "Severo Ochoa," CSIC-UAM, Universidad Autónoma de Madrid, 28049-Madrid, Spain, Instituto de Investigación Sanitaria La Princesa, 29006-Madrid, Spain,
| | - Catalina Ribas
- From the Departamento de Biología Molecular and Centro de Biología Molecular "Severo Ochoa," CSIC-UAM, Universidad Autónoma de Madrid, 28049-Madrid, Spain, Instituto de Investigación Sanitaria La Princesa, 29006-Madrid, Spain,
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Xie K, Masuho I, Shih CC, Cao Y, Sasaki K, Lai CWJ, Han PL, Ueda H, Dessauer CW, Ehrlich ME, Xu B, Willardson BM, Martemyanov KA. Stable G protein-effector complexes in striatal neurons: mechanism of assembly and role in neurotransmitter signaling. eLife 2015; 4. [PMID: 26613416 PMCID: PMC4728126 DOI: 10.7554/elife.10451] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Accepted: 11/26/2015] [Indexed: 12/23/2022] Open
Abstract
In the striatum, signaling via G protein-coupled neurotransmitter receptors is essential for motor control. Critical to this process is the effector enzyme adenylyl cyclase type 5 (AC5) that produces second messenger cAMP upon receptor-mediated activation by G protein Golf. However, the molecular organization of the Golf-AC5 signaling axis is not well understood. In this study, we report that in the striatum AC5 exists in a stable pre-coupled complex with subunits of Golf heterotrimer. We use genetic mouse models with disruption in individual components of the complex to reveal hierarchical order of interactions required for AC5-Golf stability. We further identify that the assembly of AC5-Golf complex is mediated by PhLP1 chaperone that plays central role in neurotransmitter receptor coupling to cAMP production motor learning. These findings provide evidence for the existence of stable G protein-effector signaling complexes and identify a new component essential for their assembly.
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Affiliation(s)
- Keqiang Xie
- Department of Neuroscience, The Scripps Research Institute, Jupiter, United States
| | - Ikuo Masuho
- Department of Neuroscience, The Scripps Research Institute, Jupiter, United States
| | - Chien-Cheng Shih
- Department of Neuroscience, The Scripps Research Institute, Jupiter, United States.,Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, United States
| | - Yan Cao
- Department of Neuroscience, The Scripps Research Institute, Jupiter, United States
| | - Keita Sasaki
- Department of Pharmacology and Therapeutic Innovation, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
| | - Chun Wan J Lai
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, United States
| | - Pyung-Lim Han
- Department of Brain and Cognitive Sciences, Ewha Womans University, Seoul, Republic of Korea
| | - Hiroshi Ueda
- Department of Pharmacology and Therapeutic Innovation, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
| | - Carmen W Dessauer
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center, Houston, United States
| | - Michelle E Ehrlich
- Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, United States.,Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York, United States.,Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, United States
| | - Baoji Xu
- Department of Neuroscience, The Scripps Research Institute, Jupiter, United States
| | - Barry M Willardson
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, United States
| | - Kirill A Martemyanov
- Department of Neuroscience, The Scripps Research Institute, Jupiter, United States
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Carr R, Koziol-White C, Zhang J, Lam H, An SS, Tall GG, Panettieri RA, Benovic JL. Interdicting Gq Activation in Airway Disease by Receptor-Dependent and Receptor-Independent Mechanisms. Mol Pharmacol 2015; 89:94-104. [PMID: 26464325 DOI: 10.1124/mol.115.100339] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Accepted: 10/09/2015] [Indexed: 12/25/2022] Open
Abstract
Gαqβγ heterotrimer (Gq), an important mediator in the pathology of airway disease, plays a central role in bronchoconstriction and airway remodeling, including airway smooth muscle growth and inflammation. Current therapeutic strategies to treat airway disease include the use of muscarinic and leukotriene receptor antagonists; however, these pharmaceuticals demonstrate a limited clinical efficacy as multiple Gq-coupled receptor subtypes contribute to these pathologies. Thus, broadly inhibiting the activation of Gq may be an advantageous therapeutic approach. Here, we investigated the effects of broadly inhibiting Gq activation in vitro and ex vivo using receptor-dependent and receptor-independent strategies. P4pal-10 is a protease activated receptor 4-derived pepducin that exhibits efficacy toward multiple Gq-coupled receptors. Mechanistic studies demonstrated that P4pal-10 selectively inhibits all G protein coupling to several Gq-coupled receptors, including protease activated receptor 1, muscarinic acetylcholine M3, and histamine H1 receptors, while demonstrating no direct effect on Gq. We also evaluated the ability of FR900359, also known as UBO-QIC, to directly inhibit Gq activation. FR900359 inhibited spontaneous Gαq nucleotide exchange, while having little effect on Gαsβγ, Gαiβγ, or Gα12/13βγ heterotrimer activity. Both P4pal-10 and FR900359 inhibited Gq-mediated intracellular signaling and primary human airway smooth muscle growth, whereas only FR900359 effectively interdicted agonist-promoted airway contraction in human precision cut lung slices. These studies serve as a proof of concept that the broad-based inhibition of Gq activation may be a useful therapeutic approach to treat multiple common pathologies of airway disease.
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Affiliation(s)
- Richard Carr
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, Pennsylvania (R.C., J.L.B.); Department of Medicine, Pulmonary, Allergy, and Critical Care Division, Airways Biology Initiative, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania (C.K.W., J.Z., R.A.P.); Department of Environmental Health Sciences, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland (H.L., S.S.A.); and Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, New York (G.G.T.)
| | - Cynthia Koziol-White
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, Pennsylvania (R.C., J.L.B.); Department of Medicine, Pulmonary, Allergy, and Critical Care Division, Airways Biology Initiative, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania (C.K.W., J.Z., R.A.P.); Department of Environmental Health Sciences, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland (H.L., S.S.A.); and Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, New York (G.G.T.)
| | - Jie Zhang
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, Pennsylvania (R.C., J.L.B.); Department of Medicine, Pulmonary, Allergy, and Critical Care Division, Airways Biology Initiative, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania (C.K.W., J.Z., R.A.P.); Department of Environmental Health Sciences, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland (H.L., S.S.A.); and Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, New York (G.G.T.)
| | - Hong Lam
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, Pennsylvania (R.C., J.L.B.); Department of Medicine, Pulmonary, Allergy, and Critical Care Division, Airways Biology Initiative, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania (C.K.W., J.Z., R.A.P.); Department of Environmental Health Sciences, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland (H.L., S.S.A.); and Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, New York (G.G.T.)
| | - Steven S An
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, Pennsylvania (R.C., J.L.B.); Department of Medicine, Pulmonary, Allergy, and Critical Care Division, Airways Biology Initiative, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania (C.K.W., J.Z., R.A.P.); Department of Environmental Health Sciences, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland (H.L., S.S.A.); and Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, New York (G.G.T.)
| | - Gregory G Tall
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, Pennsylvania (R.C., J.L.B.); Department of Medicine, Pulmonary, Allergy, and Critical Care Division, Airways Biology Initiative, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania (C.K.W., J.Z., R.A.P.); Department of Environmental Health Sciences, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland (H.L., S.S.A.); and Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, New York (G.G.T.)
| | - Reynold A Panettieri
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, Pennsylvania (R.C., J.L.B.); Department of Medicine, Pulmonary, Allergy, and Critical Care Division, Airways Biology Initiative, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania (C.K.W., J.Z., R.A.P.); Department of Environmental Health Sciences, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland (H.L., S.S.A.); and Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, New York (G.G.T.)
| | - Jeffrey L Benovic
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, Pennsylvania (R.C., J.L.B.); Department of Medicine, Pulmonary, Allergy, and Critical Care Division, Airways Biology Initiative, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania (C.K.W., J.Z., R.A.P.); Department of Environmental Health Sciences, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland (H.L., S.S.A.); and Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, New York (G.G.T.)
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Álvarez R, López DJ, Casas J, Lladó V, Higuera M, Nagy T, Barceló M, Busquets X, Escribá PV. G protein-membrane interactions I: Gαi1 myristoyl and palmitoyl modifications in protein-lipid interactions and its implications in membrane microdomain localization. Biochim Biophys Acta Mol Cell Biol Lipids 2015; 1851:1511-20. [PMID: 26253820 DOI: 10.1016/j.bbalip.2015.08.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2015] [Revised: 07/10/2015] [Accepted: 08/03/2015] [Indexed: 12/31/2022]
Abstract
G proteins are fundamental elements in signal transduction involved in key cell responses, and their interactions with cell membrane lipids are critical events whose nature is not fully understood. Here, we have studied how the presence of myristic and palmitic acid moieties affects the interaction of the Gαi1 protein with model and biological membranes. For this purpose, we quantified the binding of purified Gαi1 protein and Gαi1 protein acylation mutants to model membranes, with lipid compositions that resemble different membrane microdomains. We observed that myristic and palmitic acids not only act as membrane anchors but also regulate Gαi1 subunit interaction with lipids characteristics of certain membrane microdomains. Thus, when the Gαi1 subunit contains both fatty acids it prefers raft-like lamellar membranes, with a high sphingomyelin and cholesterol content and little phosphatidylserine and phosphatidylethanolamine. By contrast, the myristoylated and non-palmitoylated Gαi1 subunit prefers other types of ordered lipid microdomains with higher phosphatidylserine content. These results in part explain the mobility of Gαi1 protein upon reversible palmitoylation to meet one or another type of signaling protein partner. These results also serve as an example of how membrane lipid alterations can change membrane signaling or how membrane lipid therapy can regulate the cell's physiology.
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Affiliation(s)
- Rafael Álvarez
- Laboratory of Molecular Cell Biomedicine, Department of Biology, IUNICS, University of Islas Baleares, Carretera de Valldemossa km 7.5, E-07122 Palma de Mallorca, Spain
| | - David J López
- Laboratory of Molecular Cell Biomedicine, Department of Biology, IUNICS, University of Islas Baleares, Carretera de Valldemossa km 7.5, E-07122 Palma de Mallorca, Spain
| | - Jesús Casas
- Laboratory of Molecular Cell Biomedicine, Department of Biology, IUNICS, University of Islas Baleares, Carretera de Valldemossa km 7.5, E-07122 Palma de Mallorca, Spain
| | - Victoria Lladó
- Laboratory of Molecular Cell Biomedicine, Department of Biology, IUNICS, University of Islas Baleares, Carretera de Valldemossa km 7.5, E-07122 Palma de Mallorca, Spain
| | - Mónica Higuera
- Laboratory of Molecular Cell Biomedicine, Department of Biology, IUNICS, University of Islas Baleares, Carretera de Valldemossa km 7.5, E-07122 Palma de Mallorca, Spain
| | - Tünde Nagy
- Laboratory of Molecular Cell Biomedicine, Department of Biology, IUNICS, University of Islas Baleares, Carretera de Valldemossa km 7.5, E-07122 Palma de Mallorca, Spain
| | - Miquel Barceló
- Bioinorganic and Bioorganic Research Group, Department of Chemistry, IUNICS, University of Islas Baleares, Carretera de Valldemossa km 7.5, E-07122 Palma de Mallorca, Spain
| | - Xavier Busquets
- Laboratory of Molecular Cell Biomedicine, Department of Biology, IUNICS, University of Islas Baleares, Carretera de Valldemossa km 7.5, E-07122 Palma de Mallorca, Spain
| | - Pablo V Escribá
- Laboratory of Molecular Cell Biomedicine, Department of Biology, IUNICS, University of Islas Baleares, Carretera de Valldemossa km 7.5, E-07122 Palma de Mallorca, Spain.
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Adhesion G protein-coupled receptors are activated by exposure of a cryptic tethered agonist. Proc Natl Acad Sci U S A 2015; 112:6194-9. [PMID: 25918380 DOI: 10.1073/pnas.1421785112] [Citation(s) in RCA: 188] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The large class of adhesion G protein-coupled receptors (aGPCRs) bind extracellular matrix or neighboring cell-surface ligands to regulate organ and tissue development through an unknown activation mechanism. We examined aGPCR activation using two prototypical aGPCRs, GPR56 and GPR110. Active dissociation of the noncovalently bound GPR56 or GPR110 extracellular domains (ECDs) from the respective seven-transmembrane (7TM) domains relieved an inhibitory influence and permitted both receptors to activate defined G protein subtypes. After ECD displacement, the newly revealed short N-terminal stalk regions of the 7TM domains were found to be essential for G protein activation. Synthetic peptides comprising these stalks potently activated GPR56 or GPR110 in vitro or in cells, demonstrating that the stalks comprise a tethered agonist that was encrypted within the ECD. Establishment of an aGPCR activation mechanism provides a rational platform for the development of aGPCR synthetic modulators that could find clinical utility toward aGPCR-directed disease.
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Liebscher I, Ackley B, Araç D, Ariestanti DM, Aust G, Bae BI, Bista BR, Bridges JP, Duman JG, Engel FB, Giera S, Goffinet AM, Hall RA, Hamann J, Hartmann N, Lin HH, Liu M, Luo R, Mogha A, Monk KR, Peeters MC, Prömel S, Ressl S, Schiöth HB, Sigoillot SM, Song H, Talbot WS, Tall GG, White JP, Wolfrum U, Xu L, Piao X. New functions and signaling mechanisms for the class of adhesion G protein-coupled receptors. Ann N Y Acad Sci 2014; 1333:43-64. [PMID: 25424900 DOI: 10.1111/nyas.12580] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The class of adhesion G protein-coupled receptors (aGPCRs), with 33 human homologs, is the second largest family of GPCRs. In addition to a seven-transmembrane α-helix-a structural feature of all GPCRs-the class of aGPCRs is characterized by the presence of a large N-terminal extracellular region. In addition, all aGPCRs but one (GPR123) contain a GPCR autoproteolysis-inducing (GAIN) domain that mediates autoproteolytic cleavage at the GPCR autoproteolysis site motif to generate N- and a C-terminal fragments (NTF and CTF, respectively) during protein maturation. Subsequently, the NTF and CTF are associated noncovalently as a heterodimer at the plasma membrane. While the biological function of the GAIN domain-mediated autocleavage is not fully understood, mounting evidence suggests that the NTF and CTF possess distinct biological activities in addition to their function as a receptor unit. We discuss recent advances in understanding the biological functions, signaling mechanisms, and disease associations of the aGPCRs.
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Affiliation(s)
- Ines Liebscher
- Institute of Biochemistry, Molecular Biochemistry, Medical Faculty, University of Leipzig, Leipzig, Germany
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Papasergi MM, Patel BR, Tall GG. The G protein α chaperone Ric-8 as a potential therapeutic target. Mol Pharmacol 2014; 87:52-63. [PMID: 25319541 DOI: 10.1124/mol.114.094664] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Resistance to inhibitors of cholinesterase (Ric-8)A and Ric-8B are essential genes that encode positive regulators of heterotrimeric G protein α subunits. Controversy persists surrounding the precise way(s) that Ric-8 proteins affect G protein biology and signaling. Ric-8 proteins chaperone nucleotide-free Gα-subunit states during biosynthetic protein folding prior to G protein heterotrimer assembly. In organisms spanning the evolutionary window of Ric-8 expression, experimental perturbation of Ric-8 genes results in reduced functional abundances of G proteins because G protein α subunits are misfolded and degraded rapidly. Ric-8 proteins also act as Gα-subunit guanine nucleotide exchange factors (GEFs) in vitro. However, Ric-8 GEF activity could strictly be an in vitro phenomenon stemming from the ability of Ric-8 to induce partial Gα unfolding, thereby enhancing GDP release. Ric-8 GEF activity clearly differs from the GEF activity of G protein-coupled receptors (GPCRs). G protein βγ is inhibitory to Ric-8 action but obligate for receptors. It remains an open question whether Ric-8 has dual functions in cells and regulates G proteins as both a molecular chaperone and GEF. Clearly, Ric-8 has a profound influence on heterotrimeric G protein function. For this reason, we propose that Ric-8 proteins are as yet untested therapeutic targets in which pharmacological inhibition of the Ric-8/Gα protein-protein interface could serve to attenuate the effects of disease-causing G proteins (constitutively active mutants) and/or GPCR signaling. This minireview will chronicle the understanding of Ric-8 function, provide a comparative discussion of the Ric-8 molecular chaperoning and GEF activities, and support the case for why Ric-8 proteins should be considered potential targets for development of new therapies.
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Affiliation(s)
- Makaía M Papasergi
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, New York
| | - Bharti R Patel
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, New York
| | - Gregory G Tall
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, New York
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Kan W, Adjobo-Hermans M, Burroughs M, Faibis G, Malik S, Tall GG, Smrcka AV. M3 muscarinic receptor interaction with phospholipase C β3 determines its signaling efficiency. J Biol Chem 2014; 289:11206-11218. [PMID: 24596086 DOI: 10.1074/jbc.m113.538546] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Phospholipase Cβ (PLCβ) enzymes are activated by G protein-coupled receptors through receptor-catalyzed guanine nucleotide exchange on Gαβγ heterotrimers containing Gq family G proteins. Here we report evidence for a direct interaction between M3 muscarinic receptor (M3R) and PLCβ3. Both expressed and endogenous M3R interacted with PLCβ in coimmunoprecipitation experiments. Stimulation of M3R with carbachol significantly increased this association. Expression of M3R in CHO cells promoted plasma membrane localization of YFP-PLCβ3. Deletion of the PLCβ3 C terminus or deletion of the PLCβ3 PDZ ligand inhibited coimmunoprecipitation with M3R and M3R-dependent PLCβ3 plasma membrane localization. Purified PLCβ3 bound directly to glutathione S-transferase (GST)-fused M3R intracellular loops 2 and 3 (M3Ri2 and M3Ri3) as well as M3R C terminus (M3R/H8-CT). PLCβ3 binding to M3Ri3 was inhibited when the PDZ ligand was removed. In assays using reconstituted purified components in vitro, M3Ri2, M3Ri3, and M3R/H8-CT potentiated Gαq-dependent but not Gβγ-dependent PLCβ3 activation. Disruption of key residues in M3Ri3N and of the PDZ ligand in PLCβ3 inhibited M3Ri3-mediated potentiation. We propose that the M3 muscarinic receptor maximizes the efficiency of PLCβ3 signaling beyond its canonical role as a guanine nucleotide exchange factor for Gα.
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Affiliation(s)
- Wei Kan
- Departments of Pharmacology and Physiology and University of Rochester School of Medicine and Dentistry, Rochester, New York 14642
| | - Merel Adjobo-Hermans
- Department of Biochemistry, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical Centre, Geert Grooteplein 28, 6525 GA Nijmegen, The Netherlands
| | - Michael Burroughs
- Departments of Pharmacology and Physiology and University of Rochester School of Medicine and Dentistry, Rochester, New York 14642
| | - Guy Faibis
- Departments of Pharmacology and Physiology and University of Rochester School of Medicine and Dentistry, Rochester, New York 14642
| | - Sundeep Malik
- Departments of Pharmacology and Physiology and University of Rochester School of Medicine and Dentistry, Rochester, New York 14642
| | - Gregory G Tall
- Departments of Pharmacology and Physiology and University of Rochester School of Medicine and Dentistry, Rochester, New York 14642
| | - Alan V Smrcka
- Departments of Pharmacology and Physiology and University of Rochester School of Medicine and Dentistry, Rochester, New York 14642; Biochemistry and Biophysics and University of Rochester School of Medicine and Dentistry, Rochester, New York 14642; Aab Institute of Cardiovascular Research, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642 and.
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Boularan C, Kehrl JH. Implications of non-canonical G-protein signaling for the immune system. Cell Signal 2014; 26:1269-82. [PMID: 24583286 DOI: 10.1016/j.cellsig.2014.02.010] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2014] [Accepted: 02/22/2014] [Indexed: 01/13/2023]
Abstract
Heterotrimeric guanine nucleotide-binding proteins (G proteins), which consist of three subunits α, β, and γ, function as molecular switches to control downstream effector molecules activated by G protein-coupled receptors (GPCRs). The GTP/GDP binding status of Gα transmits information about the ligand binding state of the GPCR to intended signal transduction pathways. In immune cells heterotrimeric G proteins impact signal transduction pathways that directly, or indirectly, regulate cell migration, activation, survival, proliferation, and differentiation. The cells of the innate and adaptive immune system abundantly express chemoattractant receptors and lesser amounts of many other types of GPCRs. But heterotrimeric G-proteins not only function in classical GPCR signaling, but also in non-canonical signaling. In these pathways the guanine exchange factor (GEF) exerted by a GPCR in the canonical pathway is replaced or supplemented by another protein such as Ric-8A. In addition, other proteins such as AGS3-6 can compete with Gβγ for binding to GDP bound Gα. This competition can promote Gβγ signaling by freeing Gβγ from rapidly rebinding GDP bound Gα. The proteins that participate in these non-canonical signaling pathways will be briefly described and their role, or potential one, in cells of the immune system will be highlighted.
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Affiliation(s)
- Cédric Boularan
- B-cell Molecular Immunology Section, Laboratory of Immunoregulation, National Institutes of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, United States
| | - John H Kehrl
- B-cell Molecular Immunology Section, Laboratory of Immunoregulation, National Institutes of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, United States.
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Gutierrez-Arenas O, Eriksson O, Hellgren Kotaleski J. Segregation and crosstalk of D1 receptor-mediated activation of ERK in striatal medium spiny neurons upon acute administration of psychostimulants. PLoS Comput Biol 2014; 10:e1003445. [PMID: 24499932 PMCID: PMC3907292 DOI: 10.1371/journal.pcbi.1003445] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2013] [Accepted: 12/06/2013] [Indexed: 12/29/2022] Open
Abstract
The convergence of corticostriatal glutamate and dopamine from the midbrain in the striatal medium spiny neurons (MSN) triggers synaptic plasticity that underlies reinforcement learning and pathological conditions such as psychostimulant addiction. The increase in striatal dopamine produced by the acute administration of psychostimulants has been found to activate not only effectors of the AC5/cAMP/PKA signaling cascade such as GluR1, but also effectors of the NMDAR/Ca(2+)/RAS cascade such as ERK. The dopamine-triggered effects on both these cascades are mediated by D1R coupled to Golf but while the phosphorylation of GluR1 is affected by reductions in the available amount of Golf but not of D1R, the activation of ERK follows the opposite pattern. This segregation is puzzling considering that D1R-induced Golf activation monotonically increases with DA and that there is crosstalk from the AC5/cAMP/PKA cascade to the NMDAR/Ca(2+)/RAS cascade via a STEP (a tyrosine phosphatase). In this work, we developed a signaling model which accounts for this segregation based on the assumption that a common pool of D1R and Golf is distributed in two D1R/Golf signaling compartments. This model integrates a relatively large amount of experimental data for neurons in vivo and in vitro. We used it to explore the crosstalk topologies under which the sensitivities of the AC5/cAMP/PKA signaling cascade to reductions in D1R or Golf are transferred or not to the activation of ERK. We found that the sequestration of STEP by its substrate ERK together with the insensitivity of STEP activity on targets upstream of ERK (i.e. Fyn and NR2B) to PKA phosphorylation are able to explain the experimentally observed segregation. This model provides a quantitative framework for simulation based experiments to study signaling required for long term potentiation in MSNs.
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Affiliation(s)
- Omar Gutierrez-Arenas
- School of Computer Science and Communication, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Olivia Eriksson
- Department of Numerical Analysis and Computer Science, Stockholm University, Stockholm, Sweden
| | - Jeanette Hellgren Kotaleski
- School of Computer Science and Communication, KTH Royal Institute of Technology, Stockholm, Sweden
- Department of Numerical Analysis and Computer Science, Stockholm University, Stockholm, Sweden
- Department of Neuroscience, Karolinska Institute, Stockholm, Sweden
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Tõntson L, Kopanchuk S, Rinken A. Biarsenical ligands bind to endogenous G-protein α-subunits and enable allosteric sensing of nucleotide binding. BMC BIOCHEMISTRY 2013; 14:37. [PMID: 24344803 PMCID: PMC3878488 DOI: 10.1186/1471-2091-14-37] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/14/2013] [Accepted: 12/13/2013] [Indexed: 11/13/2022]
Abstract
BACKGROUND Heterotrimeric G-proteins relay extracellular signals to intracellular effector proteins. Multiple methods have been developed to monitor their activity; including labeled nucleotides and biosensors based on genetically engineered G-proteins. Here we describe a method for monitoring unlabeled nucleotide binding to endogenous G-proteins α-subunits in a homogeneous assay based on the interaction of 4',5'-bis(1,2,3-dithioarsolan-2-yl)-2',7'-difluorofluorescein (F2FlAsH) with G-protein α-subunits. RESULTS The biarsenic fluorescent ligand F2FlAsH binds to various wild-type G-protein α-subunits (αi1, αi2, αi3, αslong, αsshort, αolf, αq, α13) via high affinity As-cysteine interactions. This allosteric label enables real time monitoring of the nucleotide bound states of α-subunits via changes in fluorescence anisotropy and intensity of their F2FlAsH-complexes. We have found that different α-subunits displayed different signal amplitudes when interacting with F2FlAsH, being more sensitive to nucleotide binding to αi, αs, αolf and αq than to α13. Addition of nucleotides to F2FlAsH-labeled α-subunits caused concentration-dependent effects on their fluorescence anisotropy. pEC50 values of studied nucleotides depended on the subtype of the α-subunit and were from 5.7 to 8.2 for GTPγS, from 5.4 to 8.1 for GppNHp and from 4.8 to 8.2 for GDP and lastly up to 5.9 for GMP. While GDP and GMP increased the fluorescence anisotropy of F2FlAsH complexes with αi-subunits, they had the opposite effect on the other αβγM complexes studied. CONCLUSIONS Biarsenical ligands interact allosterically with endogenous G-protein α-subunits in a nucleotide-sensitive manner, so the presence or absence of guanine nucleotides has an effect on the fluorescence anisotropy, intensity and lifetime of F2FlAsH-G-protein complexes.
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Affiliation(s)
- Lauri Tõntson
- University of Tartu, Institute of Chemistry, Ravila 14a, 50411, Tartu, Estonia
| | - Sergei Kopanchuk
- University of Tartu, Institute of Chemistry, Ravila 14a, 50411, Tartu, Estonia
- Competence Centre on Reproductive Medicine & Biology, Tiigi 61b, 50410, Tartu, Estonia
| | - Ago Rinken
- University of Tartu, Institute of Chemistry, Ravila 14a, 50411, Tartu, Estonia
- Competence Centre on Reproductive Medicine & Biology, Tiigi 61b, 50410, Tartu, Estonia
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Blumer JB, Lanier SM. Activators of G protein signaling exhibit broad functionality and define a distinct core signaling triad. Mol Pharmacol 2013; 85:388-96. [PMID: 24302560 DOI: 10.1124/mol.113.090068] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Activators of G protein signaling (AGS), initially discovered in the search for receptor-independent activators of G protein signaling, define a broad panel of biologic regulators that influence signal transfer from receptor to G-protein, guanine nucleotide binding and hydrolysis, G protein subunit interactions, and/or serve as alternative binding partners for Gα and Gβγ independently of the classic heterotrimeric Gαβγ. AGS proteins generally fall into three groups based upon their interaction with and regulation of G protein subunits: group I, guanine nucleotide exchange factors (GEF); group II, guanine nucleotide dissociation inhibitors; and group III, entities that bind to Gβγ. Group I AGS proteins can engage all subclasses of G proteins, whereas group II AGS proteins primarily engage the Gi/Go/transducin family of G proteins. A fourth group of AGS proteins with selectivity for Gα16 may be defined by the Mitf-Tfe family of transcription factors. Groups I-III may act in concert, generating a core signaling triad analogous to the core triad for heterotrimeric G proteins (GEF + G proteins + effector). These two core triads may function independently of each other or actually cross-integrate for additional signal processing. AGS proteins have broad functional roles, and their discovery has advanced new concepts in signal processing, cell and tissue biology, receptor pharmacology, and system adaptation, providing unexpected platforms for therapeutic and diagnostic development.
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Affiliation(s)
- Joe B Blumer
- Department of Cell and Molecular Pharmacology and Experimental Therapeutics, Medical University of South Carolina, Charleston, South Carolina
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Abstract
Resistance to inhibitors of cholinesterase 8 proteins (Ric-8A and Ric-8B) collectively bind the four classes of heterotrimeric G protein α subunits. Ric-8A and Ric-8B act as non-receptor guanine nucleotide exchange factors (GEFs) toward the Gα subunits that each binds in vitro and seemingly regulate diverse G protein signaling systems in cells. Combined evidence from worm, fly and mammalian systems has shown that Ric-8 proteins are required to maintain proper cellular abundances of G proteins. Ric-8 proteins support G protein levels by serving as molecular chaperones that promote Gα subunit biosynthesis. In this review, the evidence that Ric-8 proteins act as non-receptor GEF activators of G proteins in signal transduction contexts will be weighed against the evidence supporting the molecular chaperoning function of Ric-8 in promoting G protein abundance. I will conclude by suggesting that Ric-8 proteins may act in either capacity in specific contexts. The field awaits additional experimentation to delineate the putative multi-functionality of Ric-8 towards G proteins in cells.
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Affiliation(s)
- Gregory G Tall
- Department of Pharmacology and Physiology, University of Rochester Medical Center , Rochester, NY, USA.
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Chan P, Thomas CJ, Sprang SR, Tall GG. Molecular chaperoning function of Ric-8 is to fold nascent heterotrimeric G protein α subunits. Proc Natl Acad Sci U S A 2013; 110:3794-9. [PMID: 23431197 PMCID: PMC3593926 DOI: 10.1073/pnas.1220943110] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
We have shown that resistance to inhibitors of cholinesterase 8 (Ric-8) proteins regulate an early step of heterotrimeric G protein α (Gα) subunit biosynthesis. Here, mammalian and plant cell-free translation systems were used to study Ric-8A action during Gα subunit translation and protein folding. Gα translation rates and overall produced protein amounts were equivalent in mock and Ric-8A-immunodepleted rabbit reticulocyte lysate (RRL). GDP-AlF4(-)-bound Gαi, Gαq, Gα13, and Gαs produced in mock-depleted RRL had characteristic resistance to limited trypsinolysis, showing that these G proteins were folded properly. Gαi, Gαq, and Gα13, but not Gαs produced from Ric-8A-depleted RRL were not protected from trypsinization and therefore not folded correctly. Addition of recombinant Ric-8A to the Ric-8A-depleted RRL enhanced GDP-AlF4(-)-bound Gα subunit trypsin protection. Dramatic results were obtained in wheat germ extract (WGE) that has no endogenous Ric-8 component. WGE-translated Gαq was gel filtered and found to be an aggregate. Ric-8A supplementation of WGE allowed production of Gαq that gel filtered as a ∼100 kDa Ric-8A:Gαq heterodimer. Addition of GTPγS to Ric-8A-supplemented WGE Gαq translation resulted in dissociation of the Ric-8A:Gαq heterodimer and production of functional Gαq-GTPγS monomer. Excess Gβγ supplementation of WGE did not support functional Gαq production. The molecular chaperoning function of Ric-8 is to participate in the folding of nascent G protein α subunits.
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Affiliation(s)
- PuiYee Chan
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY 14642; and
| | - Celestine J. Thomas
- Center for Biomolecular Structure and Dynamics and the Division of Biological Science, University of Montana, Missoula, MT 59812
| | - Stephen R. Sprang
- Center for Biomolecular Structure and Dynamics and the Division of Biological Science, University of Montana, Missoula, MT 59812
| | - Gregory G. Tall
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY 14642; and
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Zhao P, Cladman W, Van Tol HHM, Chidiac P. Fine-tuning of GPCR signals by intracellular G protein modulators. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2013; 115:421-53. [PMID: 23415100 DOI: 10.1016/b978-0-12-394587-7.00010-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Heterotrimeric G proteins convey receptor signals to intracellular effectors. Superimposed over the basic GPCR-G protein-effector scheme are three types of auxiliary proteins that also modulate Gα. Regulator of G protein signaling proteins and G protein signaling modifier proteins respectively promote GTPase activity and hinder GTP/GDP exchange to limit Gα activation. There are also diverse proteins that, like GPCRs, can promote nucleotide exchange and thus activation. Here we review the impact of these auxiliary proteins on GPCR signaling. Although their precise physiological functions are not yet clear, all of them can produce significant effects in experimental systems. These signaling changes are generally consistent with established effects on isolated Gα; however, the activation state of Gα is seldom verified and many such changes appear also to reflect the physical disruption of or indirect effects on interactions between Gα and its associated GPCR, Gβγ, and/or effector.
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Affiliation(s)
- Peishen Zhao
- Department of Physiology and Pharmacology, Western University, London, Ontario, Canada
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Oner SS, Maher EM, Gabay M, Tall GG, Blumer JB, Lanier SM. Regulation of the G-protein regulatory-Gαi signaling complex by nonreceptor guanine nucleotide exchange factors. J Biol Chem 2012; 288:3003-15. [PMID: 23212907 DOI: 10.1074/jbc.m112.418467] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Group II activators of G-protein signaling (AGS) serve as binding partners for Gα(i/o/t) via one or more G-protein regulatory (GPR) motifs. GPR-Gα signaling modules may be differentially regulated by cell surface receptors or by different nonreceptor guanine nucleotide exchange factors. We determined the effect of the nonreceptor guanine nucleotide exchange factors AGS1, GIV/Girdin, and Ric-8A on the interaction of two distinct GPR proteins, AGS3 and AGS4, with Gα(il) in the intact cell by bioluminescence resonance energy transfer (BRET) in human embryonic kidney 293 cells. AGS3-Rluc-Gα(i1)-YFP and AGS4-Rluc-Gα(i1)-YFP BRET were regulated by Ric-8A but not by Gα-interacting vesicle-associated protein (GIV) or AGS1. The Ric-8A regulation was biphasic and dependent upon the amount of Ric-8A and Gα(i1)-YFP. The inhibitory regulation of GPR-Gα(i1) BRET by Ric-8A was blocked by pertussis toxin. The enhancement of GPR-Gα(i1) BRET observed with Ric-8A was further augmented by pertussis toxin treatment. The regulation of GPR-Gα(i) interaction by Ric-8A was not altered by RGS4. AGS3-Rluc-Gα(i1)-YFP and AGS4-Rluc-G-Gα(i1)-YFP BRET were observed in both pellet and supernatant subcellular fractions and were regulated by Ric-8A in both fractions. The regulation of the GPR-Gα(i1) complex by Ric-8A, as well as the ability of Ric-8A to restore Gα expression in Ric8A(-/-) mouse embryonic stem cells, involved two helical domains at the carboxyl terminus of Ric-8A. These data indicate a dynamic interaction between GPR proteins, Gα(i1) and Ric-8A, in the cell that influences subcellular localization of the three proteins and regulates complex formation.
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Affiliation(s)
- Sukru Sadik Oner
- Department of Cell and Molecular Pharmacology and Experimental Therapeutics, Medical University of South Carolina, Charleston, South Carolina 29425, USA
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