1
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Roy S, Sinha S, Silas AJ, Ghassemian M, Kufareva I, Ghosh P. Growth factor-dependent phosphorylation of Gα i shapes canonical signaling by G protein-coupled receptors. Sci Signal 2024; 17:eade8041. [PMID: 38833528 DOI: 10.1126/scisignal.ade8041] [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: 09/11/2022] [Accepted: 05/17/2024] [Indexed: 06/06/2024]
Abstract
A long-standing question in the field of signal transduction is how distinct signaling pathways interact with each other to control cell behavior. Growth factor receptors and G protein-coupled receptors (GPCRs) are the two major signaling hubs in eukaryotes. Given that the mechanisms by which they signal independently have been extensively characterized, we investigated how they may cross-talk with each other. Using linear ion trap mass spectrometry and cell-based biophysical, biochemical, and phenotypic assays, we found at least three distinct ways in which epidermal growth factor affected canonical G protein signaling by the Gi-coupled GPCR CXCR4 through the phosphorylation of Gαi. Phosphomimicking mutations in two residues in the αE helix of Gαi (tyrosine-154/tyrosine-155) suppressed agonist-induced Gαi activation while promoting constitutive Gβγ signaling. Phosphomimicking mutations in the P loop (serine-44, serine-47, and threonine-48) suppressed Gi activation entirely, thus completely segregating growth factor and GPCR pathways. As expected, most of the phosphorylation events appeared to affect intrinsic properties of Gαi proteins, including conformational stability, nucleotide binding, and the ability to associate with and to release Gβγ. However, one phosphomimicking mutation, targeting the carboxyl-terminal residue tyrosine-320, promoted mislocalization of Gαi from the plasma membrane, a previously uncharacterized mechanism of suppressing GPCR signaling through G protein subcellular compartmentalization. Together, these findings elucidate not only how growth factor and chemokine signals cross-talk through the phosphorylation-dependent modulation of Gαi but also how such cross-talk may generate signal diversity.
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Affiliation(s)
- Suchismita Roy
- Department of Cellular and Molecular Medicine, University of California San Diego, San Diego, CA 92093, USA
| | - Saptarshi Sinha
- Department of Cellular and Molecular Medicine, University of California San Diego, San Diego, CA 92093, USA
| | - Ananta James Silas
- Department of Cellular and Molecular Medicine, University of California San Diego, San Diego, CA 92093, USA
| | - Majid Ghassemian
- Department of Chemistry and Biochemistry, Biomolecular and Proteomics Mass Spectrometry Facility, University of California San Diego, San Diego, CA 92093, USA
| | - Irina Kufareva
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, San Diego, CA 92093, USA
| | - Pradipta Ghosh
- Department of Cellular and Molecular Medicine, University of California San Diego, San Diego, CA 92093, USA
- Department of Medicine, University of California San Diego, San Diego, CA 92093, USA
- Moores Comprehensive Cancer Center, University of California San Diego, San Diego, CA 92093, USA
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2
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Janicot R, Maziarz M, Park JC, Zhao J, Luebbers A, Green E, Philibert CE, Zhang H, Layne MD, Wu JC, Garcia-Marcos M. Direct interrogation of context-dependent GPCR activity with a universal biosensor platform. Cell 2024; 187:1527-1546.e25. [PMID: 38412860 PMCID: PMC10947893 DOI: 10.1016/j.cell.2024.01.028] [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: 07/16/2023] [Revised: 12/04/2023] [Accepted: 01/18/2024] [Indexed: 02/29/2024]
Abstract
G protein-coupled receptors (GPCRs) are the largest family of druggable proteins encoded in the human genome, but progress in understanding and targeting them is hindered by the lack of tools to reliably measure their nuanced behavior in physiologically relevant contexts. Here, we developed a collection of compact ONE vector G-protein Optical (ONE-GO) biosensor constructs as a scalable platform that can be conveniently deployed to measure G-protein activation by virtually any GPCR with high fidelity even when expressed endogenously in primary cells. By characterizing dozens of GPCRs across many cell types like primary cardiovascular cells or neurons, we revealed insights into the molecular basis for G-protein coupling selectivity of GPCRs, pharmacogenomic profiles of anti-psychotics on naturally occurring GPCR variants, and G-protein subtype signaling bias by endogenous GPCRs depending on cell type or upon inducing disease-like states. In summary, this open-source platform makes the direct interrogation of context-dependent GPCR activity broadly accessible.
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Affiliation(s)
- Remi Janicot
- Department of Biochemistry & Cell Biology, Chobanian & Avedisian School of Medicine, Boston University, Boston, MA 02118, USA
| | - Marcin Maziarz
- Department of Biochemistry & Cell Biology, Chobanian & Avedisian School of Medicine, Boston University, Boston, MA 02118, USA
| | - Jong-Chan Park
- Department of Biochemistry & Cell Biology, Chobanian & Avedisian School of Medicine, Boston University, Boston, MA 02118, USA
| | - Jingyi Zhao
- Department of Biochemistry & Cell Biology, Chobanian & Avedisian School of Medicine, Boston University, Boston, MA 02118, USA
| | - Alex Luebbers
- Department of Biochemistry & Cell Biology, Chobanian & Avedisian School of Medicine, Boston University, Boston, MA 02118, USA
| | - Elena Green
- Department of Biochemistry & Cell Biology, Chobanian & Avedisian School of Medicine, Boston University, Boston, MA 02118, USA
| | - Clementine Eva Philibert
- Department of Biochemistry & Cell Biology, Chobanian & Avedisian School of Medicine, Boston University, Boston, MA 02118, USA
| | - Hao Zhang
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Mathew D Layne
- Department of Biochemistry & Cell Biology, Chobanian & Avedisian School of Medicine, Boston University, Boston, MA 02118, USA
| | - Joseph C Wu
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Mikel Garcia-Marcos
- Department of Biochemistry & Cell Biology, Chobanian & Avedisian School of Medicine, Boston University, Boston, MA 02118, USA; Department of Biology, College of Arts & Sciences, Boston University, Boston, MA 02115, USA.
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3
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Garcia-Marcos M. Heterotrimeric G protein signaling without GPCRs: The Gα-binding-and-activating (GBA) motif. J Biol Chem 2024; 300:105756. [PMID: 38364891 PMCID: PMC10943482 DOI: 10.1016/j.jbc.2024.105756] [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: 10/28/2023] [Revised: 01/30/2024] [Accepted: 02/02/2024] [Indexed: 02/18/2024] Open
Abstract
Heterotrimeric G proteins (Gαβγ) are molecular switches that relay signals from 7-transmembrane receptors located at the cell surface to the cytoplasm. The function of these receptors is so intimately linked to heterotrimeric G proteins that they are named G protein-coupled receptors (GPCRs), showcasing the interdependent nature of this archetypical receptor-transducer axis of transmembrane signaling in eukaryotes. It is generally assumed that activation of heterotrimeric G protein signaling occurs exclusively by the action of GPCRs, but this idea has been challenged by the discovery of alternative mechanisms by which G proteins can propagate signals in the cell. This review will focus on a general principle of G protein signaling that operates without the direct involvement of GPCRs. The mechanism of G protein signaling reviewed here is mediated by a class of G protein regulators defined by containing an evolutionarily conserved sequence named the Gα-binding-and-activating (GBA) motif. Using the best characterized proteins with a GBA motif as examples, Gα-interacting vesicle-associated protein (GIV)/Girdin and dishevelled-associating protein with a high frequency of leucine residues (DAPLE), this review will cover (i) the mechanisms by which extracellular cues not relayed by GPCRs promote the coupling of GBA motif-containing regulators with G proteins, (ii) the structural and molecular basis for how GBA motifs interact with Gα subunits to facilitate signaling, (iii) the relevance of this mechanism in different cellular and pathological processes, including cancer and birth defects, and (iv) strategies to manipulate GBA-G protein coupling for experimental therapeutics purposes, including the development of rationally engineered proteins and chemical probes.
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Affiliation(s)
- Mikel Garcia-Marcos
- Department of Biochemistry & Cell Biology, Chobanian & Avedisian School of Medicine, Boston University, Boston, Massachusetts, USA; Department of Biology, College of Arts & Sciences, Boston University, Boston, Massachusetts, USA.
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4
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Lao-Peregrin C, Xiang G, Kim J, Srivastava I, Fall AB, Gerhard DM, Kohtala P, Kim D, Song M, Garcia-Marcos M, Levitz J, Lee FS. Synaptic plasticity via receptor tyrosine kinase/G-protein-coupled receptor crosstalk. Cell Rep 2024; 43:113595. [PMID: 38117654 PMCID: PMC10844890 DOI: 10.1016/j.celrep.2023.113595] [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: 11/09/2022] [Revised: 11/15/2023] [Accepted: 12/01/2023] [Indexed: 12/22/2023] Open
Abstract
Cellular signaling involves a large repertoire of membrane receptors operating in overlapping spatiotemporal regimes and targeting many common intracellular effectors. However, both the molecular mechanisms and the physiological roles of crosstalk between receptors, especially those from different superfamilies, are poorly understood. We find that the receptor tyrosine kinase (RTK) TrkB and the G-protein-coupled receptor (GPCR) metabotropic glutamate receptor 5 (mGluR5) together mediate hippocampal synaptic plasticity in response to brain-derived neurotrophic factor (BDNF). Activated TrkB enhances constitutive mGluR5 activity to initiate a mode switch that drives BDNF-dependent sustained, oscillatory Ca2+ signaling and enhanced MAP kinase activation. This crosstalk is mediated, in part, by synergy between Gβγ, released by TrkB, and Gαq-GTP, released by mGluR5, to enable physiologically relevant RTK/GPCR crosstalk.
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Affiliation(s)
| | - Guoqing Xiang
- Department of Psychiatry, Weill Cornell Medicine. New York, NY 10065, USA; Department of Biochemistry, Weill Cornell Medicine, New York, NY 10065, USA
| | - Jihye Kim
- Department of Psychiatry, Weill Cornell Medicine. New York, NY 10065, USA
| | - Ipsit Srivastava
- Department of Biochemistry, Weill Cornell Medicine, New York, NY 10065, USA
| | - Alexandra B Fall
- Department of Psychiatry, Weill Cornell Medicine. New York, NY 10065, USA
| | - Danielle M Gerhard
- Department of Psychiatry, Weill Cornell Medicine. New York, NY 10065, USA
| | - Piia Kohtala
- Department of Psychiatry, Weill Cornell Medicine. New York, NY 10065, USA
| | - Daegeon Kim
- Department of Life Sciences, Yeongnam University, Gyeongsan, Gyeongbuk 38451, South Korea
| | - Minseok Song
- Department of Life Sciences, Yeongnam University, Gyeongsan, Gyeongbuk 38451, South Korea
| | - Mikel Garcia-Marcos
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA
| | - Joshua Levitz
- Department of Psychiatry, Weill Cornell Medicine. New York, NY 10065, USA; Department of Biochemistry, Weill Cornell Medicine, New York, NY 10065, USA.
| | - Francis S Lee
- Department of Psychiatry, Weill Cornell Medicine. New York, NY 10065, USA.
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5
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Luebbers A, Gonzalez-Hernandez AJ, Zhou M, Eyles SJ, Levitz J, Garcia-Marcos M. Dissecting the molecular basis for the modulation of neurotransmitter GPCR signaling by GINIP. Structure 2024; 32:47-59.e7. [PMID: 37989308 PMCID: PMC10872408 DOI: 10.1016/j.str.2023.10.010] [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: 05/04/2023] [Revised: 09/23/2023] [Accepted: 10/25/2023] [Indexed: 11/23/2023]
Abstract
It is well established that G-protein-coupled receptors (GPCRs) stimulated by neurotransmitters are critical for neuromodulation. Much less is known about how heterotrimeric G-protein (Gαβγ) regulation after receptor-mediated activation contributes to neuromodulation. Recent evidence indicates that the neuronal protein GINIP shapes GPCR inhibitory neuromodulation via a unique mechanism of G-protein regulation that controls pain and seizure susceptibility. However, the molecular basis of this mechanism remains ill-defined because the structural determinants of GINIP responsible for binding and regulating G proteins are not known. Here, we combined hydrogen-deuterium exchange mass spectrometry, computational structure predictions, biochemistry, and cell-based biophysical assays to demonstrate an effector-like binding mode of GINIP to Gαi. Specific amino acids of GINIP's PHD domain first loop are essential for G-protein binding and subsequent regulation of Gαi-GTP and Gβγ signaling upon neurotransmitter GPCR stimulation. In summary, these findings shed light onto the molecular basis for a post-receptor mechanism of G-protein regulation that fine-tunes inhibitory neuromodulation.
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Affiliation(s)
- Alex Luebbers
- Department of Biochemistry & Cell Biology, Chobanian & Avedisian School of Medicine, Boston University, Boston, MA 02118, USA
| | | | - Myles Zhou
- Department of Biochemistry & Cell Biology, Chobanian & Avedisian School of Medicine, Boston University, Boston, MA 02118, USA
| | - Stephen J Eyles
- Mass Spectrometry Core Facility, Institute for Applied Life Sciences (IALS), University of Massachusetts Amherst, Amherst, MA 01003, USA
| | - Joshua Levitz
- Department of Biochemistry, Weill Cornell Medicine, New York, NY 10064, USA; Department of Psychiatry, Weill Cornell Medicine, New York, NY 10065, USA
| | - Mikel Garcia-Marcos
- Department of Biochemistry & Cell Biology, Chobanian & Avedisian School of Medicine, Boston University, Boston, MA 02118, USA; Department of Biology, College of Arts & Sciences, Boston University, Boston, MA 02115, USA.
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6
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Janicot R, Maziarz M, Park JC, Luebbers A, Green E, Zhao J, Philibert C, Zhang H, Layne MD, Wu JC, Garcia-Marcos M. Direct interrogation of context-dependent GPCR activity with a universal biosensor platform. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.02.573921. [PMID: 38260348 PMCID: PMC10802303 DOI: 10.1101/2024.01.02.573921] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
G protein-coupled receptors (GPCRs) are the largest family of druggable proteins in the human genome, but progress in understanding and targeting them is hindered by the lack of tools to reliably measure their nuanced behavior in physiologically-relevant contexts. Here, we developed a collection of compact ONE vector G-protein Optical (ONE-GO) biosensor constructs as a scalable platform that can be conveniently deployed to measure G-protein activation by virtually any GPCR with high fidelity even when expressed endogenously in primary cells. By characterizing dozens of GPCRs across many cell types like primary cardiovascular cells or neurons, we revealed new insights into the molecular basis for G-protein coupling selectivity of GPCRs, pharmacogenomic profiles of anti-psychotics on naturally-occurring GPCR variants, and G-protein subtype signaling bias by endogenous GPCRs depending on cell type or upon inducing disease-like states. In summary, this open-source platform makes the direct interrogation of context-dependent GPCR activity broadly accessible.
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Affiliation(s)
- Remi Janicot
- Department of Biochemistry & Cell Biology, Chobanian & Avedisian School of Medicine, Boston University, Boston, MA 02118, USA
| | - Marcin Maziarz
- Department of Biochemistry & Cell Biology, Chobanian & Avedisian School of Medicine, Boston University, Boston, MA 02118, USA
| | - Jong-Chan Park
- Department of Biochemistry & Cell Biology, Chobanian & Avedisian School of Medicine, Boston University, Boston, MA 02118, USA
| | - Alex Luebbers
- Department of Biochemistry & Cell Biology, Chobanian & Avedisian School of Medicine, Boston University, Boston, MA 02118, USA
| | - Elena Green
- Department of Biochemistry & Cell Biology, Chobanian & Avedisian School of Medicine, Boston University, Boston, MA 02118, USA
| | - Jingyi Zhao
- Department of Biochemistry & Cell Biology, Chobanian & Avedisian School of Medicine, Boston University, Boston, MA 02118, USA
| | - Clementine Philibert
- Department of Biochemistry & Cell Biology, Chobanian & Avedisian School of Medicine, Boston University, Boston, MA 02118, USA
| | - Hao Zhang
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Mathew D. Layne
- Department of Biochemistry & Cell Biology, Chobanian & Avedisian School of Medicine, Boston University, Boston, MA 02118, USA
| | - Joseph C. Wu
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Mikel Garcia-Marcos
- Department of Biochemistry & Cell Biology, Chobanian & Avedisian School of Medicine, Boston University, Boston, MA 02118, USA
- Department of Biology, College of Arts & Sciences, Boston University, Boston, MA 02115, USA
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7
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Lao-Peregrin C, Xiang G, Kim J, Srivastava I, Fall AB, Gerhard DM, Kohtala P, Kim D, Song M, Garcia-Marcos M, Levitz J, Lee FS. Synaptic plasticity via receptor tyrosine kinase/G protein-coupled receptor crosstalk. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.28.555210. [PMID: 37693535 PMCID: PMC10491144 DOI: 10.1101/2023.08.28.555210] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
Cellular signaling involves a large repertoire of membrane receptors operating in overlapping spatiotemporal regimes and targeting many common intracellular effectors. However, both the molecular mechanisms and physiological roles of crosstalk between receptors, especially those from different superfamilies, are poorly understood. We find that the receptor tyrosine kinase (RTK), TrkB, and the G protein-coupled receptor (GPCR), metabotropic glutamate receptor 5 (mGluR5), together mediate a novel form of hippocampal synaptic plasticity in response to brain-derived neurotrophic factor (BDNF). Activated TrkB enhances constitutive mGluR5 activity to initiate a mode-switch that drives BDNF-dependent sustained, oscillatory Ca 2+ signaling and enhanced MAP kinase activation. This crosstalk is mediated, in part, by synergy between Gβγ, released by TrkB, and Gα q -GTP, released by mGluR5, to enable a previously unidentified form of physiologically relevant RTK/GPCR crosstalk.
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8
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Park JC, Luebbers A, Dao M, Semeano A, Nguyen AM, Papakonstantinou MP, Broselid S, Yano H, Martemyanov KA, Garcia-Marcos M. Fine-tuning GPCR-mediated neuromodulation by biasing signaling through different G protein subunits. Mol Cell 2023; 83:2540-2558.e12. [PMID: 37390816 PMCID: PMC10527995 DOI: 10.1016/j.molcel.2023.06.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 04/28/2023] [Accepted: 06/02/2023] [Indexed: 07/02/2023]
Abstract
G-protein-coupled receptors (GPCRs) mediate neuromodulation through the activation of heterotrimeric G proteins (Gαβγ). Classical models depict that G protein activation leads to a one-to-one formation of Gα-GTP and Gβγ species. Each of these species propagates signaling by independently acting on effectors, but the mechanisms by which response fidelity is ensured by coordinating Gα and Gβγ responses remain unknown. Here, we reveal a paradigm of G protein regulation whereby the neuronal protein GINIP (Gα inhibitory interacting protein) biases inhibitory GPCR responses to favor Gβγ over Gα signaling. Tight binding of GINIP to Gαi-GTP precludes its association with effectors (adenylyl cyclase) and, simultaneously, with regulator-of-G-protein-signaling (RGS) proteins that accelerate deactivation. As a consequence, Gαi-GTP signaling is dampened, whereas Gβγ signaling is enhanced. We show that this mechanism is essential to prevent the imbalances of neurotransmission that underlie increased seizure susceptibility in mice. Our findings reveal an additional layer of regulation within a quintessential mechanism of signal transduction that sets the tone of neurotransmission.
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Affiliation(s)
- Jong-Chan Park
- Department of Biochemistry & Cell Biology, Chobanian & Avedisian School of Medicine, Boston University, Boston, MA 02118, USA
| | - Alex Luebbers
- Department of Biochemistry & Cell Biology, Chobanian & Avedisian School of Medicine, Boston University, Boston, MA 02118, USA
| | - Maria Dao
- U.F. Scripps Biomedical Research, University of Florida, Jupiter, FL 33458, USA
| | - Ana Semeano
- Department of Pharmaceutical Sciences, Center for Drug Discovery, School of Pharmacy and Pharmaceutical Sciences, Bouvé College of Health Sciences, Northeastern University, Boston, MA 02115, USA
| | - Anh Minh Nguyen
- Department of Pharmaceutical Sciences, Center for Drug Discovery, School of Pharmacy and Pharmaceutical Sciences, Bouvé College of Health Sciences, Northeastern University, Boston, MA 02115, USA
| | - Maria P Papakonstantinou
- Department of Biochemistry & Cell Biology, Chobanian & Avedisian School of Medicine, Boston University, Boston, MA 02118, USA
| | - Stefan Broselid
- Department of Biochemistry & Cell Biology, Chobanian & Avedisian School of Medicine, Boston University, Boston, MA 02118, USA
| | - Hideaki Yano
- Department of Pharmaceutical Sciences, Center for Drug Discovery, School of Pharmacy and Pharmaceutical Sciences, Bouvé College of Health Sciences, Northeastern University, Boston, MA 02115, USA
| | | | - Mikel Garcia-Marcos
- Department of Biochemistry & Cell Biology, Chobanian & Avedisian School of Medicine, Boston University, Boston, MA 02118, USA; Department of Biology, College of Arts & Sciences, Boston University, Boston, MA 02115, USA.
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9
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Zhao J, DiGiacomo V, Ferreras-Gutierrez M, Dastjerdi S, Ibáñez de Opakua A, Park JC, Luebbers A, Chen Q, Beeler A, Blanco FJ, Garcia-Marcos M. Small-molecule targeting of GPCR-independent noncanonical G-protein signaling in cancer. Proc Natl Acad Sci U S A 2023; 120:e2213140120. [PMID: 37098067 PMCID: PMC10160980 DOI: 10.1073/pnas.2213140120] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2022] [Accepted: 03/06/2023] [Indexed: 04/26/2023] Open
Abstract
Activation of heterotrimeric G-proteins (Gαβγ) by G-protein-coupled receptors (GPCRs) is a quintessential mechanism of cell signaling widely targeted by clinically approved drugs. However, it has become evident that heterotrimeric G-proteins can also be activated via GPCR-independent mechanisms that remain untapped as pharmacological targets. GIV/Girdin has emerged as a prototypical non-GPCR activator of G proteins that promotes cancer metastasis. Here, we introduce IGGi-11, a first-in-class small-molecule inhibitor of noncanonical activation of heterotrimeric G-protein signaling. IGGi-11 binding to G-protein α-subunits (Gαi) specifically disrupted their engagement with GIV/Girdin, thereby blocking noncanonical G-protein signaling in tumor cells and inhibiting proinvasive traits of metastatic cancer cells. In contrast, IGGi-11 did not interfere with canonical G-protein signaling mechanisms triggered by GPCRs. By revealing that small molecules can selectively disable noncanonical mechanisms of G-protein activation dysregulated in disease, these findings warrant the exploration of therapeutic modalities in G-protein signaling that go beyond targeting GPCRs.
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Affiliation(s)
- Jingyi Zhao
- Department of Biochemistry & Cell Biology, Boston University, Chobanian & Avedisian School of Medicine, Boston, MA02118
| | - Vincent DiGiacomo
- Department of Biochemistry & Cell Biology, Boston University, Chobanian & Avedisian School of Medicine, Boston, MA02118
| | | | - Shiva Dastjerdi
- Department of Chemistry, Boston University, College of Arts & Sciences, Boston, MA02115
| | | | - Jong-Chan Park
- Department of Biochemistry & Cell Biology, Boston University, Chobanian & Avedisian School of Medicine, Boston, MA02118
| | - Alex Luebbers
- Department of Biochemistry & Cell Biology, Boston University, Chobanian & Avedisian School of Medicine, Boston, MA02118
| | - Qingyan Chen
- Department of Biochemistry & Cell Biology, Boston University, Chobanian & Avedisian School of Medicine, Boston, MA02118
| | - Aaron Beeler
- Department of Chemistry, Boston University, College of Arts & Sciences, Boston, MA02115
| | - Francisco J. Blanco
- Centro de Investigaciones Biológicas-Centro Superior de Investigaciones Cientificas, Madrid, Spain
| | - Mikel Garcia-Marcos
- Department of Biochemistry & Cell Biology, Boston University, Chobanian & Avedisian School of Medicine, Boston, MA02118
- Department of Biology, College of Arts & Sciences, Boston University, Boston, MA02115
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10
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Luebbers A, Zhou M, Eyles SJ, Garcia-Marcos M. Dissecting the molecular basis for the modulation of neurotransmitter GPCR signaling by GINIP. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.20.537566. [PMID: 37131787 PMCID: PMC10153262 DOI: 10.1101/2023.04.20.537566] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
It is well-established that activation of heterotrimeric G-proteins (Gαβγ) by G-protein-coupled receptors (GPCRs) stimulated by neurotransmitters is a key mechanism underlying neuromodulation. Much less is known about how G-protein regulation after receptor-mediated activation contributes to neuromodulation. Recent evidence indicates that the neuronal protein GINIP shapes GPCR inhibitory neuromodulation via a unique mechanism of G-protein regulation that controls neurological processes like pain and seizure susceptibility. However, the molecular basis of this mechanism remains ill-defined because the structural determinants of GINIP responsible for binding Gαi subunits and regulating G-protein signaling are not known. Here, we combined hydrogen-deuterium exchange mass-spectrometry, protein folding predictions, bioluminescence resonance energy transfer assays, and biochemical experiments to identify the first loop of the PHD domain of GINIP as an obligatory requirement for Gαi binding. Surprisingly, our results support a model in which GINIP undergoes a long-range conformational change to accommodate Gαi binding to this loop. Using cell-based assays, we demonstrate that specific amino acids in the first loop of the PHD domain are essential for the regulation of Gαi-GTP and free Gβγ signaling upon neurotransmitter GPCR stimulation. In summary, these findings shed light onto the molecular basis for a post-receptor mechanism of G-protein regulation that fine-tunes inhibitory neuromodulation.
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Affiliation(s)
- Alex Luebbers
- Department of Biochemistry & Cell Biology, Chobanian & Avedisian School of Medicine, Boston University, Boston, MA 02118, USA
| | - Myles Zhou
- Department of Biochemistry & Cell Biology, Chobanian & Avedisian School of Medicine, Boston University, Boston, MA 02118, USA
| | - Stephen J Eyles
- Mass Spectrometry Core Facility, Institute for Applied Life Sciences (IALS), University of Massachusetts Amherst, Amherst, MA 01003, USA
| | - Mikel Garcia-Marcos
- Department of Biochemistry & Cell Biology, Chobanian & Avedisian School of Medicine, Boston University, Boston, MA 02118, USA
- Department of Biology, College of Arts & Sciences, Boston University, Boston, MA 02115, USA
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11
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Zhao J, DiGiacomo V, Ferreras-Gutierrez M, Dastjerdi S, de Opakua AI, Park JC, Luebbers A, Chen Q, Beeler A, Blanco FJ, Garcia-Marcos M. Small-molecule targeting of GPCR-independent non-canonical G protein signaling inhibits cancer progression. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.18.529092. [PMID: 36824907 PMCID: PMC9949157 DOI: 10.1101/2023.02.18.529092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
Abstract
Activation of heterotrimeric G-proteins (Gαβγ) by G-protein-coupled receptors (GPCRs) is a quintessential mechanism of cell signaling widely targeted by clinically-approved drugs. However, it has become evident that heterotrimeric G-proteins can also be activated via GPCR-independent mechanisms that remain untapped as pharmacological targets. GIV/Girdin has emerged as a prototypical non-GPCR activator of G proteins that promotes cancer metastasis. Here, we introduce IGGi-11, a first-in-class smallmolecule inhibitor of non-canonical activation of heterotrimeric G-protein signaling. IGGi-11 binding to G-protein α-subunits (Gαi) specifically disrupted their engagement with GIV/Girdin, thereby blocking non-canonical G-protein signaling in tumor cells, and inhibiting pro-invasive traits of metastatic cancer cells in vitro and in mice. In contrast, IGGi-11 did not interfere with canonical G-protein signaling mechanisms triggered by GPCRs. By revealing that small molecules can selectively disable non-canonical mechanisms of G-protein activation dysregulated in disease, these findings warrant the exploration of therapeutic modalities in G-protein signaling that go beyond targeting GPCRs.
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12
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Liu L, Zhang J, Han Y, Liu D. The mechanism of Girdin in degenerative brain disease caused by high glucose stimulation. Front Endocrinol (Lausanne) 2022; 13:892897. [PMID: 36329890 PMCID: PMC9623676 DOI: 10.3389/fendo.2022.892897] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Accepted: 06/10/2022] [Indexed: 11/13/2022] Open
Abstract
UNLABELLED Girdin, as an actin-binding protein, plays a major role in maintaining the stability of the actin skeleton structure and affects the growth, development, and migration of neurons. This study discusses the mechanism of Girdin in brain degeneration caused by high glucose stimulation. We examined the expression of Girdin in diabetic patients. The positive expression rate of Girdin in the diabetic group was 17.2% (5/29), which was obviously lower than the positive expression rate of 83.3% (20/24) in the non-diabetic group. We examined the expression of Girdin and its signaling pathway-related proteins Akt and STAT3 in hippocampal neurons induced by high glucose. The results showed that, in contrast to the control group (glucose concentration = 25 mmol/L), the expression of Girdin in the high-glucose group (glucose concentration = 225 mmol/L) was reduced (P < 0.05); the phosphorylation levels of Akt and STAT3 related to Girdin signaling pathway were also reduced (P < 0.05). Under high-glucose stimulation, the structure of neurons is abnormal, such as the reduction or disappearance of dendritic spines, and the number of neurons is reduced. In addition, Girdin and Akt were less expressed in neurons and synapses, especially the most obvious reduction in synaptic terminals. The activity of Girdin and its signaling pathway-related proteins Akt and STAT3 decreased in neurons under high glucose stimulation, indicating that the mechanism of Girdin in brain degeneration caused by high glucose stimulation was closely related to the Akt and STAT3 pathways. GRAPHIC ABSTRACT The mechanism of Girdin in degenerative brain disease caused by high glucose stimulation. This article discusses the mechanism of Girdin in brain degeneration induced by high glucose stimulation. The expression of Girdin in the diabetic group was significantly lower than that in the non-diabetic group. The expression of Girdin and its signaling pathway-related proteins Akt and STAT3 in hippocampal neurons was significantly reduced under high glucose stimulation. Under high glucose stimulation, the structure of neurons is abnormal and the number decreases; synapses become shorter. It indicates that the mechanism of brain degeneration caused by high glucose stimulation by Girdin is closely related to the Akt and STAT3 pathways.
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Affiliation(s)
- Longteng Liu
- Department of Pathology, Beijing Hospital; National Center of Gerontology; Institute of Geriatric Medicine; Chinese Academy of Medical Sciences, Beijing, China
| | - Jinsong Zhang
- Department of Pathology, Beijing Hospital; National Center of Gerontology; Institute of Geriatric Medicine; Chinese Academy of Medical Sciences, Beijing, China
| | - Yanxi Han
- National Center for Clinical Laboratories, Beijing Hospital, National Center of Gerontology; Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, P.R. China; Graduate School of Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China
| | - Dongge Liu
- Department of Pathology, Beijing Hospital; National Center of Gerontology; Institute of Geriatric Medicine; Chinese Academy of Medical Sciences, Beijing, China
- *Correspondence: Dongge Liu,
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13
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Garcia-Marcos M. Complementary biosensors reveal different G-protein signaling modes triggered by GPCRs and non-receptor activators. eLife 2021; 10:65620. [PMID: 33787494 PMCID: PMC8034979 DOI: 10.7554/elife.65620] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 03/30/2021] [Indexed: 01/14/2023] Open
Abstract
It has become evident that activation of heterotrimeric G-proteins by cytoplasmic proteins that are not G-protein-coupled receptors (GPCRs) plays a role in physiology and disease. Despite sharing the same biochemical guanine nucleotide exchange factor (GEF) activity as GPCRs in vitro, the mechanisms by which these cytoplasmic proteins trigger G-protein-dependent signaling in cells have not been elucidated. Heterotrimeric G-proteins can give rise to two active signaling species, Gα-GTP and dissociated Gβγ, with different downstream effectors, but how non-receptor GEFs affect the levels of these two species in cells is not known. Here, a systematic comparison of GPCRs and three unrelated non-receptor proteins with GEF activity in vitro (GIV/Girdin, AGS1/Dexras1, and Ric-8A) revealed high divergence in their contribution to generating Gα-GTP and free Gβγ in cells directly measured with live-cell biosensors. These findings demonstrate fundamental differences in how receptor and non-receptor G-protein activators promote signaling in cells despite sharing similar biochemical activities in vitro.
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Affiliation(s)
- Mikel Garcia-Marcos
- Department of Biochemistry, Boston University School of Medicine, Boston, United States
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14
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Ear J, Abd El-Hafeez AA, Roy S, Ngo T, Rajapakse N, Choi J, Khandelwal S, Ghassemian M, McCaffrey L, Kufareva I, Sahoo D, Ghosh P. A long isoform of GIV/Girdin contains a PDZ-binding module that regulates localization and G-protein binding. J Biol Chem 2021; 296:100493. [PMID: 33675748 PMCID: PMC8042451 DOI: 10.1016/j.jbc.2021.100493] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 02/19/2021] [Accepted: 02/26/2021] [Indexed: 11/28/2022] Open
Abstract
PDZ domains are one of the most abundant protein domains in eukaryotes and are frequently found on junction-localized scaffold proteins. Various signaling molecules bind to PDZ proteins via PDZ-binding motifs (PBM) and fine-tune cellular signaling. However, how such interaction affects protein function is difficult to predict and must be solved empirically. Here we describe a long isoform of the guanine nucleotide exchange factor GIV/Girdin (CCDC88A) that we named GIV-L, which is conserved throughout evolution, from invertebrates to vertebrates, and contains a PBM. Unlike GIV, which lacks PBM and is cytosolic, GIV-L localizes onto cell junctions and has a PDZ interactome (as shown through annotating Human Cell Map and BioID-proximity labeling studies), which impacts GIV-L's ability to bind and activate trimeric G-protein, Gαi, through its guanine-nucleotide exchange modulator (GEM) module. This GEM module is found exclusively in vertebrates. We propose that the two functional modules in GIV may have evolved sequentially: the ability to bind PDZ proteins via the PBM evolved earlier in invertebrates, whereas G-protein binding and activation may have evolved later only among vertebrates. Phenotypic studies in Caco-2 cells revealed that GIV and GIV-L may have antagonistic effects on cell growth, proliferation (cell cycle), and survival. Immunohistochemical analysis in human colon tissues showed that GIV expression increases with a concomitant decrease in GIV-L during cancer initiation. Taken together, these findings reveal how regulation in GIV/CCDC88A transcript helps to achieve protein modularity, which allows the protein to play opposing roles either as a tumor suppressor (GIV-L) or as an oncogene (GIV).
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Affiliation(s)
- Jason Ear
- Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, California, USA; Biological Sciences Department, California State Polytechnic University, Pomona, California, USA.
| | - Amer Ali Abd El-Hafeez
- Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, California, USA; Pharmacology and Experimental Oncology Unit, Cancer Biology Department, National Cancer Institute, Cairo University, Cairo, Egypt
| | - Suchismita Roy
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, California, USA
| | - Tony Ngo
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, California, USA
| | - Navin Rajapakse
- Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, California, USA
| | - Julie Choi
- Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, California, USA
| | - Soni Khandelwal
- Department of Pediatrics, University of California San Diego, La Jolla, California, USA
| | - Majid Ghassemian
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California, USA
| | - Luke McCaffrey
- Rosalind and Morris Goodman Cancer Research Centre, McGill University, Montreal, Canada; Gerald Bronfman Department of Oncology, McGill University, Montreal, Canada
| | - Irina Kufareva
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, California, USA
| | - Debashis Sahoo
- Department of Pediatrics, University of California San Diego, La Jolla, California, USA
| | - Pradipta Ghosh
- Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, California, USA; Department of Medicine, University of California San Diego, La Jolla, California, USA; Rebecca and John Moore Comprehensive Cancer Center, University of California San Diego, La Jolla, California, USA; Veterans Affairs Medical Center, La Jolla, California, USA.
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15
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Receptor tyrosine kinases activate heterotrimeric G proteins via phosphorylation within the interdomain cleft of Gαi. Proc Natl Acad Sci U S A 2020; 117:28763-28774. [PMID: 33139573 DOI: 10.1073/pnas.2004699117] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The molecular mechanisms by which receptor tyrosine kinases (RTKs) and heterotrimeric G proteins, two major signaling hubs in eukaryotes, independently relay signals across the plasma membrane have been extensively characterized. How these hubs cross-talk has been a long-standing question, but answers remain elusive. Using linear ion-trap mass spectrometry in combination with biochemical, cellular, and computational approaches, we unravel a mechanism of activation of heterotrimeric G proteins by RTKs and chart the key steps that mediate such activation. Upon growth factor stimulation, the guanine-nucleotide exchange modulator dissociates Gαi•βγ trimers, scaffolds monomeric Gαi with RTKs, and facilitates the phosphorylation on two tyrosines located within the interdomain cleft of Gαi. Phosphorylation triggers the activation of Gαi and inhibits second messengers (cAMP). Tumor-associated mutants reveal how constitutive activation of this pathway impacts cell's decision to "go" vs. "grow." These insights define a tyrosine-based G protein signaling paradigm and reveal its importance in eukaryotes.
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16
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Ear J, Ali Abd El-hafeez A, Roy S, Ngo T, Rajapakse N, Choi J, Khandelwal S, Ghassemian M, Mccaffrey L, Kufareva I, Sahoo D, Ghosh P. Evolution of Modularity, Interactome and Functions of GIV/Girdin (CCDC88A) from Invertebrates to Vertebrates.. [DOI: 10.1101/2020.09.28.317172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
Abstract
AbstractPDZ domains are one of the most abundant protein domains in eukaryotes and frequently found on junction-localized scaffold proteins. Various signaling molecules bind to PDZ proteins via PDZ-binding motifs (PBM) and finetune cellular signaling. Here we describe the presence of a PBM on GIV/Girdin (CCDC88A) that is conserved throughout evolution, from invertebrates to vertebrates, and is generated as a long isoform-variant in humans, which we named GIV-L. Unlike GIV, which lacks PBM and is cytosolic, GIV-L localizes to the cell junctions, and has a unique PDZ-interactome, which impacts GIV-L’s ability to bind and activate trimeric G-protein, Gi through its guanine-nucleotide exchange modulator (GEM) module; the GEM module is found exclusively in vertebrates. Thus, the two functional modules in GIV evolved sequentially: the ability to bind PDZ proteins via the PBM evolved earlier in invertebrates, whereas G-protein binding and activation may have evolved later only among vertebrates. Phenotypic studies in Caco-2 cells revealed that GIV and GIV-L may have antagonistic effects on cell growth, proliferation (cell cycle), and survival. Immunohistochemical analyses in human colon tissues showed that GIV expression increases with a concomitant decrease in GIV-L during cancer initiation. Taken together, these findings reveal how GIV/CCDC88A in humans displays evolutionary flexibility in modularity, which allows the resultant isoforms to play opposing roles either as a tumor suppressor (GIV-L) or as an oncogene (GIV).
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17
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Garcia-Marcos M, Parag-Sharma K, Marivin A, Maziarz M, Luebbers A, Nguyen LT. Optogenetic activation of heterotrimeric G-proteins by LOV2GIVe, a rationally engineered modular protein. eLife 2020; 9:60155. [PMID: 32936073 PMCID: PMC7515630 DOI: 10.7554/elife.60155] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 09/15/2020] [Indexed: 12/24/2022] Open
Abstract
Heterotrimeric G-proteins are signal transducers involved in mediating the action of many natural extracellular stimuli and many therapeutic agents. Non-invasive approaches to manipulate the activity of G-proteins with high precision are crucial to understand their regulation in space and time. Here, we developed LOV2GIVe, an engineered modular protein that allows the activation of heterotrimeric G-proteins with blue light. This optogenetic construct relies on a versatile design that differs from tools previously developed for similar purposes, that is metazoan opsins, which are light-activated G-protein-coupled receptors (GPCRs). Instead, LOV2GIVe consists of the fusion of a G-protein activating peptide derived from a non-GPCR regulator of G-proteins to a small plant protein domain, such that light uncages the G-protein activating module. Targeting LOV2GIVe to cell membranes allowed for light-dependent activation of Gi proteins in different experimental systems. In summary, LOV2GIVe expands the armamentarium and versatility of tools available to manipulate heterotrimeric G-protein activity.
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Affiliation(s)
- Mikel Garcia-Marcos
- Department of Biochemistry, Boston University School of Medicine, Boston, United States
| | - Kshitij Parag-Sharma
- Department of Biochemistry, Boston University School of Medicine, Boston, United States
| | - Arthur Marivin
- Department of Biochemistry, Boston University School of Medicine, Boston, United States
| | - Marcin Maziarz
- Department of Biochemistry, Boston University School of Medicine, Boston, United States
| | - Alex Luebbers
- Department of Biochemistry, Boston University School of Medicine, Boston, United States
| | - Lien T Nguyen
- Department of Biochemistry, Boston University School of Medicine, Boston, United States
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18
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Maziarz M, Park JC, Leyme A, Marivin A, Garcia-Lopez A, Patel PP, Garcia-Marcos M. Revealing the Activity of Trimeric G-proteins in Live Cells with a Versatile Biosensor Design. Cell 2020; 182:770-785.e16. [PMID: 32634377 DOI: 10.1016/j.cell.2020.06.020] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 04/21/2020] [Accepted: 06/08/2020] [Indexed: 12/28/2022]
Abstract
Heterotrimeric G-proteins (Gαβγ) are the main transducers of signals from GPCRs, mediating the action of countless natural stimuli and therapeutic agents. However, there are currently no robust approaches to directly measure the activity of endogenous G-proteins in cells. Here, we describe a suite of optical biosensors that detect endogenous active G-proteins with sub-second resolution in live cells. Using a modular design principle, we developed genetically encoded, unimolecular biosensors for endogenous Gα-GTP and free Gβγ: the two active species of heterotrimeric G-proteins. This design was leveraged to generate biosensors with specificity for different heterotrimeric G-proteins or for other G-proteins, such as Rho GTPases. Versatility was further validated by implementing the biosensors in multiple contexts, from characterizing cancer-associated G-protein mutants to neurotransmitter signaling in primary neurons. Overall, the versatile biosensor design introduced here enables studying the activity of endogenous G-proteins in live cells with high fidelity, temporal resolution, and convenience.
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Affiliation(s)
- Marcin Maziarz
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA
| | - Jong-Chan Park
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA
| | - Anthony Leyme
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA
| | - Arthur Marivin
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA
| | - Alberto Garcia-Lopez
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA
| | - Prachi P Patel
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA
| | - Mikel Garcia-Marcos
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA.
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19
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Bastin G, Dissanayake K, Langburt D, Tam ALC, Lee SH, Lachhar K, Heximer SP. RGS4 controls Gαi3-mediated regulation of Bcl-2 phosphorylation on TGN38-containing intracellular membranes. J Cell Sci 2020; 133:jcs241034. [PMID: 32501280 DOI: 10.1242/jcs.241034] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Accepted: 05/05/2020] [Indexed: 08/31/2023] Open
Abstract
Intracellular pools of the heterotrimeric G-protein α-subunit Gαi3 (encoded by GNAI3) have been shown to promote growth factor signaling, while at the same time inhibiting the activation of JNK and autophagic signaling following nutrient starvation. The precise molecular mechanisms linking Gαi3 to both stress and growth factor signaling remain poorly understood. Importantly, JNK-mediated phosphorylation of Bcl-2 was previously found to activate autophagic signaling following nutrient deprivation. Our data shows that activated Gαi3 decreases Bcl-2 phosphorylation, whereas inhibitors of Gαi3, such as RGS4 and AGS3 (also known as GPSM1), markedly increase the levels of phosphorylated Bcl-2. Manipulation of the palmitoylation status and intracellular localization of RGS4 suggests that Gαi3 modulates phosphorylated Bcl-2 levels and autophagic signaling from discreet TGN38 (also known as TGOLN2)-labeled vesicle pools. Consistent with an important role for these molecules in normal tissue responses to nutrient deprivation, increased Gαi signaling within nutrient-starved adrenal glands from RGS4-knockout mice resulted in a dramatic abrogation of autophagic flux, compared to wild-type tissues. Together, these data suggest that the activity of Gαi3 and RGS4 from discreet TGN38-labeled vesicle pools are critical regulators of autophagic signaling that act via their ability to modulate phosphorylation of Bcl-2.
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Affiliation(s)
- Guillaume Bastin
- Ted Rogers Centre for Heart Research, Translational Biology and Engineering Program, 661 University Ave. 14th Floor, Toronto, ON, M5G 1M1, Canada
- Heart and Stroke/Richard Lewar Centre of Excellence in Cardiovascular Research, Room 303, C. David Naylor Building, 6 Queen's Park Crescent West, Toronto, ON, M5S 3H2, Canada
- Department of Physiology, University of Toronto, 1 King's College Circle, Toronto, ON, M5S1A8, Canada
| | - Kaveesh Dissanayake
- Department of Physiology, University of Toronto, 1 King's College Circle, Toronto, ON, M5S1A8, Canada
| | - Dylan Langburt
- Ted Rogers Centre for Heart Research, Translational Biology and Engineering Program, 661 University Ave. 14th Floor, Toronto, ON, M5G 1M1, Canada
- Department of Physiology, University of Toronto, 1 King's College Circle, Toronto, ON, M5S1A8, Canada
| | - Alex L C Tam
- Department of Physiology, University of Toronto, 1 King's College Circle, Toronto, ON, M5S1A8, Canada
| | - Shin-Haw Lee
- Ted Rogers Centre for Heart Research, Translational Biology and Engineering Program, 661 University Ave. 14th Floor, Toronto, ON, M5G 1M1, Canada
- Department of Physiology, University of Toronto, 1 King's College Circle, Toronto, ON, M5S1A8, Canada
| | - Karanjit Lachhar
- Department of Physiology, University of Toronto, 1 King's College Circle, Toronto, ON, M5S1A8, Canada
| | - Scott P Heximer
- Ted Rogers Centre for Heart Research, Translational Biology and Engineering Program, 661 University Ave. 14th Floor, Toronto, ON, M5G 1M1, Canada
- Heart and Stroke/Richard Lewar Centre of Excellence in Cardiovascular Research, Room 303, C. David Naylor Building, 6 Queen's Park Crescent West, Toronto, ON, M5S 3H2, Canada
- Department of Physiology, University of Toronto, 1 King's College Circle, Toronto, ON, M5S1A8, Canada
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20
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Ghosh P, Swanson L, Sayed IM, Mittal Y, Lim BB, Ibeawuchi SR, Foretz M, Viollet B, Sahoo D, Das S. The stress polarity signaling (SPS) pathway serves as a marker and a target in the leaky gut barrier: implications in aging and cancer. Life Sci Alliance 2020; 3:e201900481. [PMID: 32041849 PMCID: PMC7012149 DOI: 10.26508/lsa.201900481] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Revised: 01/21/2020] [Accepted: 01/22/2020] [Indexed: 12/14/2022] Open
Abstract
The gut barrier separates trillions of microbes from the largest immune system in the body; when compromised, a "leaky" gut barrier fuels systemic inflammation, which hastens the progression of chronic diseases. Strategies to detect and repair the leaky gut barrier remain urgent and unmet needs. Recently, a stress-polarity signaling (SPS) pathway has been described in which the metabolic sensor, AMP-kinase acts via its effector, GIV (also known as Girdin) to augment epithelial polarity exclusively under energetic stress and suppresses tumor formation. Using murine and human colon-derived organoids, and enteroid-derived monolayers (EDMs) that are exposed to stressors, we reveal that the SPS-pathway is active in the intestinal epithelium and requires a catalytically active AMP-kinase. Its pharmacologic augmentation resists stress-induced collapse of the epithelium when challenged with microbes or microbial products. In addition, the SPS-pathway is suppressed in the aging gut, and its reactivation in enteroid-derived monolayers reverses aging-associated inflammation and loss of barrier function. It is also silenced during progression of colorectal cancers. These findings reveal the importance of the SPS-pathway in the gut and highlights its therapeutic potential for treating gut barrier dysfunction in aging, cancer, and dysbiosis.
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Affiliation(s)
- Pradipta Ghosh
- Department of Medicine, University of California San Diego, La Jolla, CA, USA
- Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, CA, USA
- Moores Cancer Center at UC San Diego Health, La Jolla, CA, USA
- Veterans Affairs Medical Center, La Jolla, CA, USA
| | - Lee Swanson
- Department of Medicine, University of California San Diego, La Jolla, CA, USA
- Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, CA, USA
| | - Ibrahim M Sayed
- Department of Pathology, University of California San Diego, La Jolla, CA, USA
- Microbiology and Immunology Department, Assiut University, Asyut, Egypt
| | - Yash Mittal
- Department of Medicine, University of California San Diego, La Jolla, CA, USA
| | - Blaze B Lim
- Department of Medicine, University of California San Diego, La Jolla, CA, USA
- Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, CA, USA
| | | | - Marc Foretz
- Institut National de la Santé et de la Recherche Médicale (French Institute of Health and Medical Research) (INSERM) U1016, Institut Cochin, Paris, France
- Centre National de la Recherche Scientifique (National Center for Scientific Research) (CNRS) United for Medical Research (UMR) 8104, Paris, France
- Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Benoit Viollet
- Institut National de la Santé et de la Recherche Médicale (French Institute of Health and Medical Research) (INSERM) U1016, Institut Cochin, Paris, France
- Centre National de la Recherche Scientifique (National Center for Scientific Research) (CNRS) United for Medical Research (UMR) 8104, Paris, France
- Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Debashis Sahoo
- Department of Pediatrics, University of California San Diego, La Jolla, CA, USA
- Department of Computer Science and Engineering, Jacob's School of Engineering, University of California San Diego, La Jolla, CA, USA
| | - Soumita Das
- Department of Pathology, University of California San Diego, La Jolla, CA, USA
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21
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Marivin A, Maziarz M, Zhao J, DiGiacomo V, Olmos Calvo I, Mann EA, Ear J, Blanco-Canosa JB, Ross EM, Ghosh P, Garcia-Marcos M. DAPLE protein inhibits nucleotide exchange on Gα s and Gα q via the same motif that activates Gαi. J Biol Chem 2020; 295:2270-2284. [PMID: 31949046 DOI: 10.1074/jbc.ra119.011648] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Revised: 01/08/2020] [Indexed: 01/03/2023] Open
Abstract
Besides being regulated by G-protein-coupled receptors, the activity of heterotrimeric G proteins is modulated by many cytoplasmic proteins. GIV/Girdin and DAPLE (Dvl-associating protein with a high frequency of leucine) are the best-characterized members of a group of cytoplasmic regulators that contain a Gα-binding and -activating (GBA) motif and whose dysregulation underlies human diseases, including cancer and birth defects. GBA motif-containing proteins were originally reported to modulate G proteins by binding Gα subunits of the Gi/o family (Gαi) over other families (such as Gs, Gq/11, or G12/13), and promoting nucleotide exchange in vitro However, some evidence suggests that this is not always the case, as phosphorylation of the GBA motif of GIV promotes its binding to Gαs and inhibits nucleotide exchange. The G-protein specificity of DAPLE and how it might affect nucleotide exchange on G proteins besides Gαi remain to be investigated. Here, we show that DAPLE's GBA motif, in addition to Gαi, binds efficiently to members of the Gs and Gq/11 families (Gαs and Gαq, respectively), but not of the G12/13 family (Gα12) in the absence of post-translational phosphorylation. We pinpointed Met-1669 as the residue in the GBA motif of DAPLE that diverges from that in GIV and enables better binding to Gαs and Gαq Unlike the nucleotide-exchange acceleration observed for Gαi, DAPLE inhibited nucleotide exchange on Gαs and Gαq These findings indicate that GBA motifs have versatility in their G-protein-modulating effect, i.e. they can bind to Gα subunits of different classes and either stimulate or inhibit nucleotide exchange depending on the G-protein subtype.
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Affiliation(s)
- Arthur Marivin
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118
| | - Marcin Maziarz
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118
| | - Jingyi Zhao
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118
| | - Vincent DiGiacomo
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118
| | - Isabel Olmos Calvo
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118
| | - Emily A Mann
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118
| | - Jason Ear
- Department of Medicine and Cellular and Molecular Medicine, University of California, San Diego, California 92093
| | - Juan B Blanco-Canosa
- Department of Biological Chemistry, Institute for Advanced Chemistry of Catalonia (IQAC-CSIC), Barcelona, Spain 08034
| | - Elliott M Ross
- Department of Pharmacology, Green Center for Systems Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Pradipta Ghosh
- Department of Medicine and Cellular and Molecular Medicine, University of California, San Diego, California 92093
| | - Mikel Garcia-Marcos
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118.
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22
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Ear J, Dunkel Y, Mittal Y, Lim BBC, Liu L, Holda MK, Nitsche U, Barbazán J, Goel A, Janssen KP, Aznar N, Ghosh P. Two Isoforms of the Guanine Nucleotide Exchange Factor, Daple/CCDC88C Cooperate as Tumor Suppressors. Sci Rep 2019; 9:12124. [PMID: 31431650 PMCID: PMC6702192 DOI: 10.1038/s41598-019-48420-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Accepted: 08/01/2019] [Indexed: 01/27/2023] Open
Abstract
Previously, Aznar et al., showed that Daple/CCDC88C enables Wnt receptors to transactivate trimeric G-proteins during non-canonical Wnt signaling via a novel G-protein binding and activating (GBA) motif. By doing so, Daple serves two opposing roles; earlier during oncogenesis it suppresses neoplastic transformation and tumor growth, but later it triggers epithelial-to-mesenchymal-transition (EMT). We have identified and characterized two isoforms of the human Daple gene. While both isoforms cooperatively suppress tumor growth via their GBA motif, only the full-length transcript triggers EMT and invasion. Both isoforms are suppressed during colon cancer progression, and their reduced expression carries additive prognostic significance. These findings provide insights into the opposing roles of Daple during cancer progression and define the G-protein regulatory GBA motif as one of the minimal modules essential for Daple’s role as a tumor suppressor.
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Affiliation(s)
- Jason Ear
- Department of Medicine, University of California, San Diego, La Jolla, California, USA.,Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, California, USA
| | - Ying Dunkel
- Department of Medicine, University of California, San Diego, La Jolla, California, USA
| | - Yash Mittal
- Department of Medicine, University of California, San Diego, La Jolla, California, USA
| | - Blaze B C Lim
- Department of Medicine, University of California, San Diego, La Jolla, California, USA
| | - Lawrence Liu
- Department of Medicine, University of California, San Diego, La Jolla, California, USA
| | - Magda K Holda
- Department of Medicine, University of California, San Diego, La Jolla, California, USA
| | - Ulrich Nitsche
- Department of Surgery, Klinikumrechts der Isar, TechnischeUniversitätMünchen, Munich, Germany
| | - Jorge Barbazán
- Translational Medical Oncology Laboratory, Health Research Institute of Santiago (IDIS), SERGAS., Santiago de Compostela, Spain
| | - Ajay Goel
- Division of Gastroenterology, Department of Internal Medicine and Charles A. Sammons Cancer Center and Baylor Research Institute, Baylor University Medical Center, Dallas, Texas, USA
| | - Klaus-Peter Janssen
- Department of Surgery, Klinikumrechts der Isar, TechnischeUniversitätMünchen, Munich, Germany
| | - Nicolas Aznar
- Department of Medicine, University of California, San Diego, La Jolla, California, USA. .,Cancer Research Center of Lyon, Centre Léon Bérard, Lyon, France.
| | - Pradipta Ghosh
- Department of Medicine, University of California, San Diego, La Jolla, California, USA. .,Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, California, USA. .,Moores Cancer Center, University of California, San Diego, La Jolla, California, USA.
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23
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Structural basis for GPCR-independent activation of heterotrimeric Gi proteins. Proc Natl Acad Sci U S A 2019; 116:16394-16403. [PMID: 31363053 DOI: 10.1073/pnas.1906658116] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Heterotrimeric G proteins are key molecular switches that control cell behavior. The canonical activation of G proteins by agonist-occupied G protein-coupled receptors (GPCRs) has recently been elucidated from the structural perspective. In contrast, the structural basis for GPCR-independent G protein activation by a novel family of guanine-nucleotide exchange modulators (GEMs) remains unknown. Here, we present a 2.0-Å crystal structure of Gαi in complex with the GEM motif of GIV/Girdin. Nucleotide exchange assays, molecular dynamics simulations, and hydrogen-deuterium exchange experiments demonstrate that GEM binding to the conformational switch II causes structural changes that allosterically propagate to the hydrophobic core of the Gαi GTPase domain. Rearrangement of the hydrophobic core appears to be a common mechanism by which GPCRs and GEMs activate G proteins, although with different efficiency. Atomic-level insights presented here will aid structure-based efforts to selectively target the noncanonical G protein activation.
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24
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Marivin A, Garcia-Marcos M. DAPLE and MPDZ bind to each other and cooperate to promote apical cell constriction. Mol Biol Cell 2019; 30:1900-1910. [PMID: 31268831 PMCID: PMC6727773 DOI: 10.1091/mbc.e19-02-0091] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Dishevelled-Associating Protein with a high frequency of LEucines (DAPLE) belongs to a group of unconventional activators of heterotrimeric G-proteins that are cytoplasmic factors rather than membrane proteins of the G-protein–coupled receptor superfamily. During neurulation, DAPLE localizes to apical junctions of neuroepithelial cells and promotes apical cell constriction via G-protein activation. While junctional localization of DAPLE is necessary for this function, the factors it associates with at apical junctions or how they contribute to DAPLE-mediated apical constriction are unknown. MPDZ is a multi-PDZ (PSD95/DLG1/ZO-1) domain scaffold present at apical cell junctions whose mutation in humans is linked to nonsyndromic congenital hydrocephalus (NSCH). DAPLE contains a PDZ-binding motif (PBM) and is also mutated in human NSCH, so we investigated the functional relationship between both proteins. DAPLE colocalized with MPDZ at apical cell junctions and bound directly to the PDZ3 domain of MPDZ via its PBM. Much like DAPLE, MPDZ is induced during neurulation in Xenopus and is required for apical constriction of neuroepithelial cells and subsequent neural plate bending. MPDZ depletion also blunted DAPLE-mediated apical constriction of cultured cells. These results show that DAPLE and MPDZ, two factors genetically linked to NSCH, function as cooperative partners at apical junctions and are required for proper tissue remodeling during early stages of neurodevelopment.
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Affiliation(s)
- Arthur Marivin
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118
| | - Mikel Garcia-Marcos
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118
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25
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Marivin A, Morozova V, Walawalkar I, Leyme A, Kretov DA, Cifuentes D, Dominguez I, Garcia-Marcos M. GPCR-independent activation of G proteins promotes apical cell constriction in vivo. J Cell Biol 2019; 218:1743-1763. [PMID: 30948426 PMCID: PMC6504902 DOI: 10.1083/jcb.201811174] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 01/19/2019] [Accepted: 03/12/2019] [Indexed: 01/21/2023] Open
Abstract
Heterotrimeric G proteins are signaling switches that control organismal morphogenesis across metazoans. In invertebrates, specific GPCRs instruct G proteins to promote collective apical cell constriction in the context of epithelial tissue morphogenesis. In contrast, tissue-specific factors that instruct G proteins during analogous processes in vertebrates are largely unknown. Here, we show that DAPLE, a non-GPCR protein linked to human neurodevelopmental disorders, is expressed specifically in the neural plate of Xenopus laevis embryos to trigger a G protein signaling pathway that promotes apical cell constriction during neurulation. DAPLE localizes to apical cell-cell junctions in the neuroepithelium, where it activates G protein signaling to drive actomyosin-dependent apical constriction and subsequent bending of the neural plate. This function is mediated by a Gα-binding-and-activating (GBA) motif that was acquired by DAPLE in vertebrates during evolution. These findings reveal that regulation of tissue remodeling during vertebrate development can be driven by an unconventional mechanism of heterotrimeric G protein activation that operates in lieu of GPCRs.
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Affiliation(s)
- Arthur Marivin
- Department of Biochemistry, Boston University School of Medicine, Boston, MA
| | - Veronika Morozova
- Department of Biochemistry, Boston University School of Medicine, Boston, MA
| | - Isha Walawalkar
- Department of Biochemistry, Boston University School of Medicine, Boston, MA
| | - Anthony Leyme
- Department of Biochemistry, Boston University School of Medicine, Boston, MA
| | - Dmitry A Kretov
- Department of Biochemistry, Boston University School of Medicine, Boston, MA
| | - Daniel Cifuentes
- Department of Biochemistry, Boston University School of Medicine, Boston, MA
| | - Isabel Dominguez
- Department of Medicine, Boston University School of Medicine, Boston, MA
| | - Mikel Garcia-Marcos
- Department of Biochemistry, Boston University School of Medicine, Boston, MA
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26
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Maziarz M, Leyme A, Marivin A, Luebbers A, Patel PP, Chen Z, Sprang SR, Garcia-Marcos M. Atypical activation of the G protein Gα q by the oncogenic mutation Q209P. J Biol Chem 2018; 293:19586-19599. [PMID: 30352874 DOI: 10.1074/jbc.ra118.005291] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Revised: 10/15/2018] [Indexed: 12/22/2022] Open
Abstract
The causative role of G protein-coupled receptor (GPCR) pathway mutations in uveal melanoma (UM) has been well-established. Nearly all UMs bear an activating mutation in a GPCR pathway mediated by G proteins of the Gq/11 family, driving tumor initiation and possibly metastatic progression. Thus, targeting this pathway holds therapeutic promise for managing UM. However, direct targeting of oncogenic Gαq/11 mutants, present in ∼90% of UMs, is complicated by the belief that these mutants structurally resemble active Gαq/11 WT. This notion is solidly founded on previous studies characterizing Gα mutants in which a conserved catalytic glutamine (Gln-209 in Gαq) is replaced by leucine, which leads to GTPase function deficiency and constitutive activation. Whereas Q209L accounts for approximately half of GNAQ mutations in UM, Q209P is as frequent as Q209L and also promotes oncogenesis, but has not been characterized at the molecular level. Here, we characterized the biochemical and signaling properties of Gαq Q209P and found that it is also GTPase-deficient and activates downstream signaling as efficiently as Gαq Q209L. However, Gαq Q209P had distinct molecular and functional features, including in the switch II region of Gαq Q209P, which adopted a conformation different from that of Gαq Q209L or active WT Gαq, resulting in altered binding to effectors, Gβγ, and regulators of G-protein signaling (RGS) proteins. Our findings reveal that the molecular properties of Gαq Q209P are fundamentally different from those in other active Gαq proteins and could be leveraged as a specific vulnerability for the ∼20% of UMs bearing this mutation.
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Affiliation(s)
- Marcin Maziarz
- From the Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118
| | - Anthony Leyme
- From the Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118
| | - Arthur Marivin
- From the Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118
| | - Alex Luebbers
- From the Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118
| | - Prachi P Patel
- From the Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118
| | - Zhe Chen
- the Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, Texas 75390, and
| | - Stephen R Sprang
- the Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, Montana 59812
| | - Mikel Garcia-Marcos
- From the Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118,
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27
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Maziarz M, Broselid S, DiGiacomo V, Park JC, Luebbers A, Garcia-Navarrete L, Blanco-Canosa JB, Baillie GS, Garcia-Marcos M. A biochemical and genetic discovery pipeline identifies PLCδ4b as a nonreceptor activator of heterotrimeric G-proteins. J Biol Chem 2018; 293:16964-16983. [PMID: 30194280 DOI: 10.1074/jbc.ra118.003580] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Revised: 08/21/2018] [Indexed: 02/06/2023] Open
Abstract
Recent evidence has revealed that heterotrimeric G-proteins can be activated by cytoplasmic proteins that share an evolutionarily conserved sequence called the Gα-binding-and-activating (GBA) motif. This mechanism provides an alternative to canonical activation by G-protein-coupled receptors (GPCRs) and plays important roles in cell function, and its dysregulation is linked to diseases such as cancer. Here, we describe a discovery pipeline that uses biochemical and genetic approaches to validate GBA candidates identified by sequence similarity. First, putative GBA motifs discovered in bioinformatics searches were synthesized on peptide arrays and probed in batch for Gαi3 binding. Then, cDNAs encoding proteins with Gαi3-binding sequences were expressed in a genetically-modified yeast strain that reports mammalian G-protein activity in the absence of GPCRs. The resulting GBA motif candidates were characterized by comparison of their biochemical, structural, and signaling properties with those of all previously described GBA motifs in mammals (GIV/Girdin, DAPLE, Calnuc, and NUCB2). We found that the phospholipase Cδ4 (PLCδ4) GBA motif binds G-proteins with high affinity, has guanine nucleotide exchange factor activity in vitro, and activates G-protein signaling in cells, as indicated by bioluminescence resonance energy transfer (BRET)-based biosensors of G-protein activity. Interestingly, the PLCδ4 isoform b (PLCδ4b), which lacks the domains required for PLC activity, bound and activated G-proteins more efficiently than the full-length isoform a, suggesting that PLCδ4b functions as a G-protein regulator rather than as a PLC. In summary, we have identified PLCδ4 as a nonreceptor activator of G-proteins and established an experimental pipeline to discover and characterize GBA motif-containing proteins.
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Affiliation(s)
- Marcin Maziarz
- From the Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts, 02118
| | - Stefan Broselid
- From the Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts, 02118
| | - Vincent DiGiacomo
- From the Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts, 02118
| | - Jong-Chan Park
- From the Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts, 02118
| | - Alex Luebbers
- From the Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts, 02118
| | - Lucia Garcia-Navarrete
- From the Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts, 02118
| | - Juan B Blanco-Canosa
- the Department of Biological Chemistry and Molecular Modelling, Institute of Advanced Chemistry of Catalonia (IQAC-CSIC), 08034 Barcelona, Spain, and
| | - George S Baillie
- the Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom
| | - Mikel Garcia-Marcos
- From the Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts, 02118
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28
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Aznar N, Ear J, Dunkel Y, Sun N, Satterfield K, He F, Kalogriopoulos NA, Lopez-Sanchez I, Ghassemian M, Sahoo D, Kufareva I, Ghosh P. Convergence of Wnt, growth factor, and heterotrimeric G protein signals on the guanine nucleotide exchange factor Daple. Sci Signal 2018; 11:11/519/eaao4220. [PMID: 29487190 DOI: 10.1126/scisignal.aao4220] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Cellular proliferation, differentiation, and morphogenesis are shaped by multiple signaling cascades, and their dysregulation plays an integral role in cancer progression. Three cascades that contribute to oncogenic potential are those mediated by Wnt proteins and the receptor Frizzled (FZD), growth factor receptor tyrosine kinases (RTKs), and heterotrimeric G proteins and associated GPCRs. Daple is a guanine nucleotide exchange factor (GEF) for the G protein Gαi Daple also binds to FZD and the Wnt/FZD mediator Dishevelled (Dvl), and it enhances β-catenin-independent Wnt signaling in response to Wnt5a-FZD7 signaling. We identified Daple as a substrate of multiple RTKs and non-RTKs and, hence, as a point of convergence for the three cascades. We found that phosphorylation near the Dvl-binding motif in Daple by both RTKs and non-RTKs caused Daple/Dvl complex dissociation and augmented the ability of Daple to bind to and activate Gαi, which potentiated β-catenin-independent Wnt signals and stimulated epithelial-mesenchymal transition (EMT) similarly to Wnt5a/FZD7 signaling. Although Daple acts as a tumor suppressor in the healthy colon, the concurrent increased abundance of Daple and epidermal growth factor receptor (EGFR) in colorectal tumors was associated with poor patient prognosis. Thus, the Daple-dependent activation of Gαi and the Daple-dependent enhancement of β-catenin-independent Wnt signals are not only stimulated by Wnt5a/FZD7 to suppress tumorigenesis but also hijacked by growth factor-activated RTKs to enhance tumor progression. These findings identify a cross-talk paradigm among growth factor RTKs, heterotrimeric G proteins, and the Wnt/FZD pathway in cancer.
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Affiliation(s)
- Nicolas Aznar
- Department of Medicine, University of California, San Diego, La Jolla, CA 92093, USA.
| | - Jason Ear
- Department of Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Ying Dunkel
- Department of Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Nina Sun
- Department of Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Kendall Satterfield
- Department of Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Fang He
- Department of Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | | | | | - Majid Ghassemian
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093, USA
| | - Debashis Sahoo
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA 92093, USA.,Department of Computer Science and Engineering, Jacobs School of Engineering, University of California, San Diego, La Jolla, CA 92093, USA
| | - Irina Kufareva
- Department of Pediatrics, University of California, San Diego, La Jolla, CA 92093, USA
| | - Pradipta Ghosh
- Department of Medicine, University of California, San Diego, La Jolla, CA 92093, USA. .,Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093, USA.,Moores Cancer Center, University of California, San Diego, La Jolla, CA 92093, USA
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29
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Zhang H, Yu F, Qin F, Shao Y, Chong W, Guo Z, Liu X, Fu L, Gu F, Ma Y. Combination of cytoplasmic and nuclear girdin expression is an independent prognosis factor of breast cancer. FASEB J 2017; 32:2395-2410. [PMID: 29259035 DOI: 10.1096/fj.201700825rr] [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] [Indexed: 01/03/2023]
Abstract
Girdin is an actin-binding protein playing key roles in the development of various carcinomas. Although online tools have predicted nuclear localization of girdin with a high probability, convincing proof has rarely been provided until now. The purpose of this study was to discover girdin's precise subcellular distribution and the potential prognostic value corresponding to its localization. The subcellular distribution of girdin was detected in a human breast cancer cell line and in >800 samples of human breast tissue by clinical pathologic analysis. In this study, we discovered for the first time that girdin could attach to chromatin and interact with topoisomerase-IIα in nucleus. Cytoplasmic and nuclear girdin exhibited different roles in prognosis of breast cancer: cytoplasmic girdin expression was an independent prognostic factor for progression-free survival (PFS), whereas nuclear girdin expression was an independent prognostic factor for overall survival (OS). More important, combination cytoplasmic and nuclear girdin was an independent prognosis factor of both OS and PFS. In conclusion, our research results strongly recommend combination analysis of cytoplasmic and nuclear girdin for a precise prognostic prediction in breast cancer.-Zhang, H., Yu, F., Qin, F., Shao, Y., Chong, W., Guo, Z., Liu, X., Fu, L., Gu, F., Ma, Y. Combination of cytoplasmic and nuclear girdin expression is an independent prognosis factor of breast cancer.
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Affiliation(s)
- Huikun Zhang
- Department of Breast Cancer Pathology and Research Laboratory, Tianjin Medical University Cancer Institute and Hospital, Tianjin, China
| | - Feng Yu
- Department of Tumor Cell Biology, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Tianjin, China.,Tianjin's Clinical Research Center for Cancer, Tianjin, China.,Key Laboratory of Cancer Prevention and Therapy, Tianjin, China.,Key Laboratory of Breast Cancer Prevention and Therapy, Tianjin Medical University, Ministry of Education, Tianjin, China
| | - Fengxia Qin
- Department of Breast Cancer Pathology and Research Laboratory, Tianjin Medical University Cancer Institute and Hospital, Tianjin, China
| | - Ying Shao
- Department of Breast Cancer Pathology and Research Laboratory, Tianjin Medical University Cancer Institute and Hospital, Tianjin, China
| | - Wei Chong
- Department of Breast Cancer Pathology and Research Laboratory, Tianjin Medical University Cancer Institute and Hospital, Tianjin, China
| | - Zhifang Guo
- Department of Tumor Cell Biology, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Tianjin, China
| | - Xiaoli Liu
- Department of Tumor Cell Biology, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Tianjin, China
| | - Li Fu
- Department of Breast Cancer Pathology and Research Laboratory, Tianjin Medical University Cancer Institute and Hospital, Tianjin, China
| | - Feng Gu
- Department of Breast Cancer Pathology and Research Laboratory, Tianjin Medical University Cancer Institute and Hospital, Tianjin, China
| | - Yongjie Ma
- Department of Tumor Cell Biology, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Tianjin, China.,Tianjin's Clinical Research Center for Cancer, Tianjin, China.,Key Laboratory of Cancer Prevention and Therapy, Tianjin, China.,Key Laboratory of Breast Cancer Prevention and Therapy, Tianjin Medical University, Ministry of Education, Tianjin, China
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30
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Specific inhibition of GPCR-independent G protein signaling by a rationally engineered protein. Proc Natl Acad Sci U S A 2017; 114:E10319-E10328. [PMID: 29133411 DOI: 10.1073/pnas.1707992114] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Activation of heterotrimeric G proteins by cytoplasmic nonreceptor proteins is an alternative to the classical mechanism via G protein-coupled receptors (GPCRs). A subset of nonreceptor G protein activators is characterized by a conserved sequence named the Gα-binding and activating (GBA) motif, which confers guanine nucleotide exchange factor (GEF) activity in vitro and promotes G protein-dependent signaling in cells. GBA proteins have important roles in physiology and disease but remain greatly understudied. This is due, in part, to the lack of efficient tools that specifically disrupt GBA motif function in the context of the large multifunctional proteins in which they are embedded. This hindrance to the study of alternative mechanisms of G protein activation contrasts with the wealth of convenient chemical and genetic tools to manipulate GPCR-dependent activation. Here, we describe the rational design and implementation of a genetically encoded protein that specifically inhibits GBA motifs: GBA inhibitor (GBAi). GBAi was engineered by introducing modifications in Gαi that preclude coupling to every known major binding partner [GPCRs, Gβγ, effectors, guanine nucleotide dissociation inhibitors (GDIs), GTPase-activating proteins (GAPs), or the chaperone/GEF Ric-8A], while favoring high-affinity binding to all known GBA motifs. We demonstrate that GBAi does not interfere with canonical GPCR-G protein signaling but blocks GBA-dependent signaling in cancer cells. Furthermore, by implementing GBAi in vivo, we show that GBA-dependent signaling modulates phenotypes during Xenopus laevis embryonic development. In summary, GBAi is a selective, efficient, and convenient tool to dissect the biological processes controlled by a GPCR-independent mechanism of G protein activation mediated by cytoplasmic factors.
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31
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Maziarz M, Garcia-Marcos M. Fluorescence polarization assays to measure interactions between Gα subunits of heterotrimeric G proteins and regulatory motifs. Methods Cell Biol 2017; 142:133-143. [PMID: 28964332 DOI: 10.1016/bs.mcb.2017.07.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
Fluorescence polarization (FP) is a simple and sensitive method allowing for the quantification of interactions between proteins and fluorescently tagged small molecules like peptides. Heterotrimeric G proteins are critical signal transducing molecules and their activity is controlled by a complex network of regulatory proteins. Some of these regulators have defined short motifs (<40 amino acids) that are sufficient to bind G proteins and subsequently modulate their activity. For these cases, FP represents a robust and quantitative method to characterize the G protein regulator interaction. Here we describe FP assays in a 384-well plate format to quantify interactions between Gα subunits of heterotrimeric G proteins and peptides corresponding to the Gα binding and activating (GBA) or GoLoco motifs, which are present in some proteins with guanine nucleotide exchange factor (GEF) (e.g., GIV/Girdin) or guanine nucleotide dissociation inhibitor (GDI) (e.g., RGS12) activity, respectively. This assay can be used to determine equilibrium dissociation constants, characterize the impact of single amino acid point mutations on the Gα-peptide interaction, and is suitable for high-throughput screening.
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Affiliation(s)
- Marcin Maziarz
- Boston University School of Medicine, Boston, MA, United States
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32
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DiGiacomo V, de Opakua AI, Papakonstantinou MP, Nguyen LT, Merino N, Blanco-Canosa JB, Blanco FJ, Garcia-Marcos M. The Gαi-GIV binding interface is a druggable protein-protein interaction. Sci Rep 2017; 7:8575. [PMID: 28819150 PMCID: PMC5561080 DOI: 10.1038/s41598-017-08829-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Accepted: 07/12/2017] [Indexed: 01/26/2023] Open
Abstract
Heterotrimeric G proteins are usually activated by the guanine-nucleotide exchange factor (GEF) activity of GPCRs. However, some non-receptor proteins are also GEFs. GIV (a.k.a Girdin) was the first non-receptor protein for which the GEF activity was ascribed to a well-defined protein sequence that directly binds Gαi. GIV expression promotes metastasis and disruption of its binding to Gαi blunts the pro-metastatic behavior of cancer cells. Although this suggests that inhibition of the Gαi-GIV interaction is a promising therapeutic strategy, protein-protein interactions (PPIs) are considered poorly "druggable" targets requiring case-by-case validation. Here, we set out to investigate whether Gαi-GIV is a druggable PPI. We tested a collection of >1,000 compounds on the Gαi-GIV PPI by in silico ligand screening and separately by a chemical high-throughput screening (HTS) assay. Two hits, ATA and NF023, obtained in both screens were confirmed in secondary HTS and low-throughput assays. The binding site of NF023, identified by NMR spectroscopy and biochemical assays, overlaps with the Gαi-GIV interface. Importantly, NF023 did not disrupt Gαi-Gβγ binding, indicating its specificity toward Gαi-GIV. This work establishes the Gαi-GIV PPI as a druggable target and sets the conceptual and technical framework for the discovery of novel inhibitors of this PPI.
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Affiliation(s)
- Vincent DiGiacomo
- Department of Biochemistry, Boston University School of Medicine, Boston, USA
| | | | | | - Lien T Nguyen
- Department of Biochemistry, Boston University School of Medicine, Boston, USA
| | | | - Juan B Blanco-Canosa
- Department of Chemistry and Molecular Pharmacology, IRB Barcelona, Barcelona, Spain
| | - Francisco J Blanco
- CIC-BioGune, Derio, Spain.,IKERBASQUE, Basque Foundation for Science, Bilbao, Spain
| | - Mikel Garcia-Marcos
- Department of Biochemistry, Boston University School of Medicine, Boston, USA.
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33
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de Opakua AI, Parag-Sharma K, DiGiacomo V, Merino N, Leyme A, Marivin A, Villate M, Nguyen LT, de la Cruz-Morcillo MA, Blanco-Canosa JB, Ramachandran S, Baillie GS, Cerione RA, Blanco FJ, Garcia-Marcos M. Molecular mechanism of Gαi activation by non-GPCR proteins with a Gα-Binding and Activating motif. Nat Commun 2017; 8:15163. [PMID: 28516903 PMCID: PMC5454376 DOI: 10.1038/ncomms15163] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Accepted: 03/06/2017] [Indexed: 01/03/2023] Open
Abstract
Heterotrimeric G proteins are quintessential signalling switches activated by nucleotide exchange on Gα. Although activation is predominantly carried out by G-protein-coupled receptors (GPCRs), non-receptor guanine-nucleotide exchange factors (GEFs) have emerged as critical signalling molecules and therapeutic targets. Here we characterize the molecular mechanism of G-protein activation by a family of non-receptor GEFs containing a Gα-binding and -activating (GBA) motif. We combine NMR spectroscopy, computational modelling and biochemistry to map changes in Gα caused by binding of GBA proteins with residue-level resolution. We find that the GBA motif binds to the SwitchII/α3 cleft of Gα and induces changes in the G-1/P-loop and G-2 boxes (involved in phosphate binding), but not in the G-4/G-5 boxes (guanine binding). Our findings reveal that G-protein-binding and activation mechanisms are fundamentally different between GBA proteins and GPCRs, and that GEF-mediated perturbation of nucleotide phosphate binding is sufficient for Gα activation. Nonreceptor guanine-nucleotide exchange factors (GEFs) are emerging as important regulators of heterotrimeric G proteins. Here, the authors present structural and mechanistic insights into how a class of nonreceptor GEFs containing the Ga-Binding and Activating motif interact and modulate G proteins.
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Affiliation(s)
| | - Kshitij Parag-Sharma
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118, USA
| | - Vincent DiGiacomo
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118, USA
| | | | - Anthony Leyme
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118, USA
| | - Arthur Marivin
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118, USA
| | | | - Lien T Nguyen
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118, USA
| | | | - Juan B Blanco-Canosa
- Department of Chemistry and Molecular Pharmacology, IRB Barcelona, 08028 Barcelona, Spain
| | - Sekar Ramachandran
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA
| | - George S Baillie
- Institute of Cardiovascular and Medical Sciences, Department of Molecular Pharmacology, University of Glasgow, Glasgow G12 8QQ, UK
| | - Richard A Cerione
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA.,Department of Molecular Medicine, Cornell University, Ithaca, New York 14853, USA
| | - Francisco J Blanco
- CIC bioGUNE, 48160 Derio, Spain.,IKERBASQUE, Basque Foundation for Science, 48160 Bilbao, Spain
| | - Mikel Garcia-Marcos
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118, USA
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Ghosh P, Rangamani P, Kufareva I. The GAPs, GEFs, GDIs and…now, GEMs: New kids on the heterotrimeric G protein signaling block. Cell Cycle 2017; 16:607-612. [PMID: 28287365 DOI: 10.1080/15384101.2017.1282584] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
The canonical process of activation of heterotrimeric G proteins by G protein coupled receptors (GPCRs) is well studied. Recently, a rapidly emerging paradigm has revealed the existence of a new, non-canonical set of cytosolic G protein modulators, guanine exchange modulators (GEMs). Among G proteins regulators, GEMs are uniquely capable of initiating pleiotropic signals: these bifunctional modulators can activate cAMP inhibitory (Gi) proteins and inhibit cAMP-stimulatory (Gs) proteins through a single short evolutionarily conserved module. A prototypical member of the GEM family, GIV/Girdin, integrates signals downstream of a myriad of cell surface receptors, e.g., growth factor RTKs, integrins, cytokine, GPCRs, etc., and translates these signals into G protein activation or inhibition. By their pleiotropic action, GIV and other GEMs modulate several key pathways within downstream signaling network. Unlike canonical G protein signaling that is finite and is triggered directly and exclusively by GPCRs, the temporal and spatial features of non-canonical activation of G protein via GIV-family of cytosolic GEMs are unusually relaxed. GIV uses this relaxed circuitry to integrate, reinforce and compartmentalize signals downstream of both growth factors and G proteins in a way that enables it to orchestrate cellular phenotypes in a sustained manner. Mounting evidence suggests the importance of GIV and other GEMs as disease modulators and their potential to serve as therapeutic targets; however, a lot remains unknown within the layers of the proverbial onion that must be systematically peeled. This perspective summarizes the key concepts of the GEM-dependent G protein signaling paradigm and discusses the multidisciplinary approaches that are likely to revolutionize our understanding of this paradigm from the atomic level to systems biology.
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Affiliation(s)
- Pradipta Ghosh
- a Departments of Medicine and Cell and Molecular Medicine , University of California at San Diego , La Jolla , CA , USA
| | - Padmini Rangamani
- b Department of Mechanical and Aerospace Engineering , Jacobs School of Engineering, University of California at San Diego , La Jolla , CA , USA
| | - Irina Kufareva
- c Skaggs School of Pharmacy and Pharmaceutical Sciences , University of California at San Diego , La Jolla , CA , USA
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35
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Ghosh P, Aznar N, Swanson L, Lo IC, Lopez-Sanchez I, Ear J, Rohena C, Kalogriopoulos N, Joosen L, Dunkel Y, Sun N, Nguyen P, Bhandari D. Biochemical, Biophysical and Cellular Techniques to Study the Guanine Nucleotide Exchange Factor, GIV/Girdin. CURRENT PROTOCOLS IN CHEMICAL BIOLOGY 2016; 8:265-298. [PMID: 27925669 PMCID: PMC5154557 DOI: 10.1002/cpch.13] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Canonical signal transduction via heterotrimeric G proteins is spatiotemporally restricted, i.e., triggered exclusively at the plasma membrane, only by agonist activation of G protein-coupled receptors via a finite process that is terminated within a few hundred milliseconds. Recently, a rapidly emerging paradigm has revealed a noncanonical pathway for activation of heterotrimeric G proteins via the nonreceptor guanidine-nucleotide exchange factor, GIV/Girdin. Biochemical, biophysical, and functional studies evaluating this pathway have unraveled its unique properties and distinctive spatiotemporal features. As in the case of any new pathway/paradigm, these studies first required an in-depth optimization of tools/techniques and protocols, governed by rationale and fundamentals unique to the pathway, and more specifically to the large multimodular GIV protein. Here we provide the most up-to-date overview of protocols that have generated most of what we know today about noncanonical G protein activation by GIV and its relevance in health and disease. © 2016 by John Wiley & Sons, Inc.
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Affiliation(s)
- Pradipta Ghosh
- Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA 92093-0651
- Department of Medicine, University of California at San Diego, La Jolla, CA 92093-0651
| | - Nicolas Aznar
- Department of Medicine, University of California at San Diego, La Jolla, CA 92093-0651
| | - Lee Swanson
- Department of Medicine, University of California at San Diego, La Jolla, CA 92093-0651
| | - I-Chung Lo
- Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA 92093-0651
| | | | - Jason Ear
- Department of Medicine, University of California at San Diego, La Jolla, CA 92093-0651
| | - Cristina Rohena
- Department of Medicine, University of California at San Diego, La Jolla, CA 92093-0651
| | | | - Linda Joosen
- Department of Medicine, University of California at San Diego, La Jolla, CA 92093-0651
| | - Ying Dunkel
- Department of Medicine, University of California at San Diego, La Jolla, CA 92093-0651
| | - Nina Sun
- Department of Medicine, University of California at San Diego, La Jolla, CA 92093-0651
| | - Peter Nguyen
- Department of Chemistry and Biochemistry, California State University Long Beach, Long Beach, CA 90840-9507
| | - Deepali Bhandari
- Department of Chemistry and Biochemistry, California State University Long Beach, Long Beach, CA 90840-9507
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36
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Parag-Sharma K, Leyme A, DiGiacomo V, Marivin A, Broselid S, Garcia-Marcos M. Membrane Recruitment of the Non-receptor Protein GIV/Girdin (Gα-interacting, Vesicle-associated Protein/Girdin) Is Sufficient for Activating Heterotrimeric G Protein Signaling. J Biol Chem 2016; 291:27098-27111. [PMID: 27864364 DOI: 10.1074/jbc.m116.764431] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2016] [Revised: 11/17/2016] [Indexed: 11/06/2022] Open
Abstract
GIV (aka Girdin) is a guanine nucleotide exchange factor that activates heterotrimeric G protein signaling downstream of RTKs and integrins, thereby serving as a platform for signaling cascade cross-talk. GIV is recruited to the cytoplasmic tail of receptors upon stimulation, but the mechanism of activation of its G protein regulatory function is not well understood. Here we used assays in humanized yeast models and G protein activity biosensors in mammalian cells to investigate the role of GIV subcellular compartmentalization in regulating its ability to promote G protein signaling. We found that in unstimulated cells GIV does not co-fractionate with its substrate G protein Gαi3 on cell membranes and that constitutive membrane anchoring of GIV in yeast cells or rapid membrane translocation in mammalian cells via chemically induced dimerization leads to robust G protein activation. We show that membrane recruitment of the GIV "Gα binding and activating" motif alone is sufficient for G protein activation and that it does not require phosphomodification. Furthermore, we engineered a synthetic protein to show that recruitment of the GIV "Gα binding and activating" motif to membranes via association with active RTKs, instead of via chemically induced dimerization, is also sufficient for G protein activation. These results reveal that recruitment of GIV to membranes in close proximity to its substrate G protein is a major mechanism responsible for the activation of its G protein regulatory function.
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Affiliation(s)
- Kshitij Parag-Sharma
- From the Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118
| | - Anthony Leyme
- From the Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118
| | - Vincent DiGiacomo
- From the Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118
| | - Arthur Marivin
- From the Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118
| | - Stefan Broselid
- From the Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118
| | - Mikel Garcia-Marcos
- From the Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118
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37
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Aznar N, Patel A, Rohena CC, Dunkel Y, Joosen LP, Taupin V, Kufareva I, Farquhar MG, Ghosh P. AMP-activated protein kinase fortifies epithelial tight junctions during energetic stress via its effector GIV/Girdin. eLife 2016; 5. [PMID: 27813479 PMCID: PMC5119889 DOI: 10.7554/elife.20795] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2016] [Accepted: 11/03/2016] [Indexed: 02/06/2023] Open
Abstract
Loss of epithelial polarity impacts organ development and function; it is also oncogenic. AMPK, a key sensor of metabolic stress stabilizes cell-cell junctions and maintains epithelial polarity; its activation by Metformin protects the epithelial barrier against stress and suppresses tumorigenesis. How AMPK protects the epithelium remains unknown. Here, we identify GIV/Girdin as a novel effector of AMPK, whose phosphorylation at a single site is both necessary and sufficient for strengthening mammalian epithelial tight junctions and preserving cell polarity and barrier function in the face of energetic stress. Expression of an oncogenic mutant of GIV (cataloged in TCGA) that cannot be phosphorylated by AMPK increased anchorage-independent growth of tumor cells and helped these cells to evade the tumor-suppressive action of Metformin. This work defines a fundamental homeostatic mechanism by which the AMPK-GIV axis reinforces cell junctions against stress-induced collapse and also provides mechanistic insight into the tumor-suppressive action of Metformin.
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Affiliation(s)
- Nicolas Aznar
- Department of Medicine, University of California, San Diego, San Diego, United States
| | - Arjun Patel
- Department of Medicine, University of California, San Diego, San Diego, United States
| | - Cristina C Rohena
- Department of Medicine, University of California, San Diego, San Diego, United States
| | - Ying Dunkel
- Department of Medicine, University of California, San Diego, San Diego, United States
| | - Linda P Joosen
- Department of Medicine, University of California, San Diego, San Diego, United States
| | - Vanessa Taupin
- Department of Cellular and Molecular Medicine, University of California, San Diego, San Diego, United States
| | - Irina Kufareva
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, San Diego, United States
| | - Marilyn G Farquhar
- Department of Cellular and Molecular Medicine, University of California, San Diego, San Diego, United States
| | - Pradipta Ghosh
- Department of Medicine, University of California, San Diego, San Diego, United States.,Department of Cellular and Molecular Medicine, University of California, San Diego, San Diego, United States.,Moores Cancer Center, University of California, San Diego, San Diego, United States
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38
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GIV/Girdin activates Gαi and inhibits Gαs via the same motif. Proc Natl Acad Sci U S A 2016; 113:E5721-30. [PMID: 27621449 DOI: 10.1073/pnas.1609502113] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We previously showed that guanine nucleotide-binding (G) protein α subunit (Gα)-interacting vesicle-associated protein (GIV), a guanine-nucleotide exchange factor (GEF), transactivates Gα activity-inhibiting polypeptide 1 (Gαi) proteins in response to growth factors, such as EGF, using a short C-terminal motif. Subsequent work demonstrated that GIV also binds Gαs and that inactive Gαs promotes maturation of endosomes and shuts down mitogenic MAPK-ERK1/2 signals from endosomes. However, the mechanism and consequences of dual coupling of GIV to two G proteins, Gαi and Gαs, remained unknown. Here we report that GIV is a bifunctional modulator of G proteins; it serves as a guanine nucleotide dissociation inhibitor (GDI) for Gαs using the same motif that allows it to serve as a GEF for Gαi. Upon EGF stimulation, GIV modulates Gαi and Gαs sequentially: first, a key phosphomodification favors the assembly of GIV-Gαi complexes and activates GIV's GEF function; then a second phosphomodification terminates GIV's GEF function, triggers the assembly of GIV-Gαs complexes, and activates GIV's GDI function. By comparing WT and GIV mutants, we demonstrate that GIV inhibits Gαs activity in cells responding to EGF. Consequently, the cAMP→PKA→cAMP response element-binding protein signaling axis is inhibited, the transit time of EGF receptor through early endosomes are accelerated, mitogenic MAPK-ERK1/2 signals are rapidly terminated, and proliferation is suppressed. These insights define a paradigm in G-protein signaling in which a pleiotropically acting modulator uses the same motif both to activate and to inhibit G proteins. Our findings also illuminate how such modulation of two opposing Gα proteins integrates downstream signals and cellular responses.
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39
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Marivin A, Leyme A, Parag-Sharma K, DiGiacomo V, Cheung AY, Nguyen LT, Dominguez I, Garcia-Marcos M. Dominant-negative Gα subunits are a mechanism of dysregulated heterotrimeric G protein signaling in human disease. Sci Signal 2016; 9:ra37. [PMID: 27072656 DOI: 10.1126/scisignal.aad2429] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Auriculo-condylar syndrome (ACS), a rare condition that impairs craniofacial development, is caused by mutations in a G protein-coupled receptor (GPCR) signaling pathway. In mice, disruption of signaling by the endothelin type A receptor (ET(A)R), which is mediated by the G protein (heterotrimeric guanine nucleotide-binding protein) subunit Gα(q/11) and subsequently phospholipase C (PLC), impairs neural crest cell differentiation that is required for normal craniofacial development. Some ACS patients have mutations inGNAI3, which encodes Gα(i3), but it is unknown whether this G protein has a role within the ET(A)R pathway. We used a Xenopus model of vertebrate development, in vitro biochemistry, and biosensors of G protein activity in mammalian cells to systematically characterize the phenotype and function of all known ACS-associated Gα(i3) mutants. We found that ACS-associated mutations in GNAI3 produce dominant-negative Gα(i3) mutant proteins that couple to ET(A)R but cannot bind and hydrolyze guanosine triphosphate, resulting in the prevention of endothelin-mediated activation of Gα(q/11) and PLC. Thus, ACS is caused by functionally dominant-negative mutations in a heterotrimeric G protein subunit.
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Affiliation(s)
- Arthur Marivin
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA
| | - Anthony Leyme
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA
| | - Kshitij Parag-Sharma
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA
| | - Vincent DiGiacomo
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA
| | - Anthony Y Cheung
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA
| | - Lien T Nguyen
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA
| | - Isabel Dominguez
- Department of Medicine, Boston University School of Medicine, Boston, MA 02118, USA
| | - Mikel Garcia-Marcos
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA.
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40
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Leyme A, Marivin A, Garcia-Marcos M. GIV/Girdin (Gα-interacting, Vesicle-associated Protein/Girdin) Creates a Positive Feedback Loop That Potentiates Outside-in Integrin Signaling in Cancer Cells. J Biol Chem 2016; 291:8269-82. [PMID: 26887938 DOI: 10.1074/jbc.m115.691550] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Indexed: 11/06/2022] Open
Abstract
Activation of the tyrosine kinase focal adhesion kinase (FAK) upon cell stimulation by the extracellular matrix initiates integrin outside-in signaling. FAK is directly recruited to active integrins, which enhances its kinase activity and triggers downstream signaling like activation of PI3K. We recently described that Gα-interacting, vesicle-associated protein (GIV), a protein up-regulated in metastatic cancers, is also required for outside-in integrin signaling. More specifically, we found that GIV is a non-receptor guanine nucleotide exchange factor that activates trimeric G proteins in response to integrin stimulation to enhance PI3K signaling and tumor cell migration. In contrast, previous reports have established that GIV is involved in phosphotyrosine (Tyr(P))-based signaling in response to growth factor stimulation;i.e.GIV phosphorylation at Tyr-1764 and Tyr-1798 recruits and activates PI3K. Here we show that phosphorylation of GIV at Tyr-1764/Tyr-1798 is also required to enhance PI3K-Akt signaling and tumor cell migration in response to integrin stimulation, indicating that GIV functions in Tyr(P)-dependent integrin signaling. Unexpectedly, we found that activation of FAK, an upstream component of the integrin Tyr(P) signaling cascade, was diminished in GIV-depleted cells, suggesting that GIV is required to establish a positive feedback loop that enhances integrin-FAK signaling. Mechanistically, we demonstrate that this feedback activation of FAK depends on both guanine nucleotide exchange factor and Tyr(P) GIV signaling as well as on their convergence point, PI3K. Taken together, our results provide novel mechanistic insights into how GIV promotes proinvasive cancer cell behavior by working as a signal-amplifying platform at the crossroads of trimeric G protein and Tyr(P) signaling.
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Affiliation(s)
- Anthony Leyme
- From the Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118
| | - Arthur Marivin
- From the Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118
| | - Mikel Garcia-Marcos
- From the Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118
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41
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Aznar N, Kalogriopoulos N, Midde KK, Ghosh P. Heterotrimeric G protein signaling via GIV/Girdin: Breaking the rules of engagement, space, and time. Bioessays 2016; 38:379-93. [PMID: 26879989 DOI: 10.1002/bies.201500133] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Canonical signal transduction via heterotrimeric G proteins is spatially and temporally restricted, that is, triggered exclusively at the plasma membrane (PM), only by agonist activation of G protein-coupled receptors (GPCRs) via a process that completes within a few hundred milliseconds. Recently, a rapidly emerging paradigm has revealed a non-canonical pathway for activation of heterotrimeric G proteins by the non-receptor guanidine-nucleotide exchange factor (GEF), GIV/Girdin. This pathway has distinctive temporal and spatial features and an unusual profile of receptor engagement: diverse classes of receptors, not just GPCRs can engage with GIV to trigger such activation. Such activation is spatially and temporally unrestricted, that is, can occur both at the PM and on internal membranes discontinuous with the PM, and can continue for prolonged periods of time. Here, we provide the most complete up-to-date review of the molecular mechanisms that govern the unique spatiotemporal aspects of non-canonical G protein activation by GIV and the relevance of this new paradigm in health and disease.
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Affiliation(s)
- Nicolas Aznar
- Department of Medicine, University of California at San Diego, La Jolla, CA, USA
| | | | - Krishna K Midde
- Department of Medicine, University of California at San Diego, La Jolla, CA, USA
| | - Pradipta Ghosh
- Department of Medicine, University of California at San Diego, La Jolla, CA, USA.,Department of Cell and Molecular Medicine, University of California at San Diego, La Jolla, CA, USA
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42
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Ghosh P. The untapped potential of tyrosine-based G protein signaling. Pharmacol Res 2016; 105:99-107. [PMID: 26808081 DOI: 10.1016/j.phrs.2016.01.017] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Revised: 01/14/2016] [Accepted: 01/15/2016] [Indexed: 01/14/2023]
Abstract
Tyrosine-based and trimeric G protein-based signaling are the two most widely studied and distinct mechanisms for signal transduction in eukaryotes. How each of them relay signals across the plasma membrane independently of each other has been extensively characterized; however, an understanding of how they work together remained obscure. Recently, a rapidly emerging paradigm has revealed that tyrosine based signals are relayed via G proteins, and that the cross-talk between the two hubs are more robustly and sophisticatedly integrated than was previously imagined. More importantly, by straddling the two signaling hubs that are most frequently targeted for their therapeutic significance, the tyrosine-based G-protein signaling pathway has its own growing list of pathophysiologic importance, both as therapeutic target in a variety of disease states, and by paving the way for personalized medicine. The fundamental principles of this emerging paradigm and its pharmacologic potential are discussed.
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Affiliation(s)
- Pradipta Ghosh
- Department of Medicine and Department of Cell and Molecular Medicine, University of California at San Diego, La Jolla, CA 92093-0651, United States.
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43
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Coleman BD, Marivin A, Parag-Sharma K, DiGiacomo V, Kim S, Pepper JS, Casler J, Nguyen LT, Koelle MR, Garcia-Marcos M. Evolutionary Conservation of a GPCR-Independent Mechanism of Trimeric G Protein Activation. Mol Biol Evol 2015; 33:820-37. [PMID: 26659249 PMCID: PMC4760084 DOI: 10.1093/molbev/msv336] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Trimeric G protein signaling is a fundamental mechanism of cellular communication in eukaryotes. The core of this mechanism consists of activation of G proteins by the guanine-nucleotide exchange factor (GEF) activity of G protein coupled receptors. However, the duration and amplitude of G protein-mediated signaling are controlled by a complex network of accessory proteins that appeared and diversified during evolution. Among them, nonreceptor proteins with GEF activity are the least characterized. We recently found that proteins of the ccdc88 family possess a Gα-binding and activating (GBA) motif that confers GEF activity and regulates mammalian cell behavior. A sequence similarity-based search revealed that ccdc88 genes are highly conserved across metazoa but the GBA motif is absent in most invertebrates. This prompted us to investigate whether the GBA motif is present in other nonreceptor proteins in invertebrates. An unbiased bioinformatics search in Caenorhabditis elegans identified GBAS-1 (GBA and SPK domain containing-1) as a GBA motif-containing protein with homologs only in closely related worm species. We demonstrate that GBAS-1 has GEF activity for the nematode G protein GOA-1 and that the two proteins are coexpressed in many cells of living worms. Furthermore, we show that GBAS-1 can activate mammalian Gα-subunits and provide structural insights into the evolutionarily conserved determinants of the GBA–G protein interface. These results demonstrate that the GBA motif is a functional GEF module conserved among highly divergent proteins across evolution, indicating that the GBA-Gα binding mode is strongly constrained under selective pressure to mediate receptor-independent G protein activation in metazoans.
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Affiliation(s)
| | - Arthur Marivin
- Department of Biochemistry, Boston University School of Medicine
| | | | | | - Seongseop Kim
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine
| | - Judy S Pepper
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine
| | - Jason Casler
- Department of Biochemistry, Boston University School of Medicine
| | - Lien T Nguyen
- Department of Biochemistry, Boston University School of Medicine
| | - Michael R Koelle
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine
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44
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Lopez-Sanchez I, Kalogriopoulos N, Lo IC, Kabir F, Midde KK, Wang H, Ghosh P. Focal adhesions are foci for tyrosine-based signal transduction via GIV/Girdin and G proteins. Mol Biol Cell 2015; 26:4313-24. [PMID: 26446841 PMCID: PMC4666128 DOI: 10.1091/mbc.e15-07-0496] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Accepted: 09/28/2015] [Indexed: 12/14/2022] Open
Abstract
GIV is a guanine-nucleotide exchange factor and a bona fide metastasis-related protein. It is found, unexpectedly, that focal adhesions are the major foci for GIV-dependent signaling and that GIV modulates integrin-FAK signaling via activation of G proteins. It is also shown how this phenomenon is altered during cancer progression. GIV/Girdin is a multimodular signal transducer and a bona fide metastasis-related protein. As a guanidine exchange factor (GEF), GIV modulates signals initiated by growth factors (chemical signals) by activating the G protein Gαi. Here we report that mechanical signals triggered by the extracellular matrix (ECM) also converge on GIV-GEF via β1 integrins and that focal adhesions (FAs) serve as the major hubs for mechanochemical signaling via GIV. GIV interacts with focal adhesion kinase (FAK) and ligand-activated β1 integrins. Phosphorylation of GIV by FAK enhances PI3K-Akt signaling, the integrity of FAs, increases cell–ECM adhesion, and triggers ECM-induced cell motility. Activation of Gαi by GIV-GEF further potentiates FAK-GIV-PI3K-Akt signaling at the FAs. Spatially restricted signaling via tyrosine phosphorylated GIV at the FAs is enhanced during cancer metastasis. Thus GIV-GEF serves as a unifying platform for integration and amplification of adhesion (mechanical) and growth factor (chemical) signals during cancer progression.
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Affiliation(s)
- Inmaculada Lopez-Sanchez
- Department of Medicine, University of California, San Diego, School of Medicine, La Jolla, CA 92093
| | - Nicholas Kalogriopoulos
- Department of Medicine, University of California, San Diego, School of Medicine, La Jolla, CA 92093
| | - I-Chung Lo
- Department of Cellular and Molecular Medicine, University of California, San Diego, School of Medicine, La Jolla, CA 92093
| | - Firooz Kabir
- Department of Medicine, University of California, San Diego, School of Medicine, La Jolla, CA 92093
| | - Krishna K Midde
- Department of Medicine, University of California, San Diego, School of Medicine, La Jolla, CA 92093
| | - Honghui Wang
- Department of Cellular and Molecular Medicine, University of California, San Diego, School of Medicine, La Jolla, CA 92093
| | - Pradipta Ghosh
- Department of Medicine, University of California, San Diego, School of Medicine, La Jolla, CA 92093 Department of Cellular and Molecular Medicine, University of California, San Diego, School of Medicine, La Jolla, CA 92093
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Leyme A, Marivin A, Perez-Gutierrez L, Nguyen LT, Garcia-Marcos M. Integrins activate trimeric G proteins via the nonreceptor protein GIV/Girdin. J Cell Biol 2015; 210:1165-84. [PMID: 26391662 PMCID: PMC4586755 DOI: 10.1083/jcb.201506041] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Accepted: 08/20/2015] [Indexed: 01/04/2023] Open
Abstract
Signal transduction via integrins and G protein-coupled receptors is critical to control cell behavior. These two receptor classes have been traditionally believed to trigger distinct and independent signaling cascades in response to extracellular cues. Here, we report a novel mechanism of integrin signaling that requires activation of the trimeric G protein Gαi by the nonreceptor guanine nucleotide exchange factor (GEF) GIV (also known as Girdin), a metastasis-associated protein. We demonstrate that GIV enhances integrin-dependent cell responses upon extracellular matrix stimulation and makes tumor cells more invasive. These responses include remodeling of the actin cytoskeleton and PI3K-dependent signaling, resulting in enhanced haptotaxis and invasion. We show that both GIV and its substrate Gαi3 are recruited to active integrin complexes and that tumor cells engineered to express GEF-deficient GIV fail to transduce integrin signals into proinvasive responses via a Gβγ-PI3K axis. Our discoveries delineate a novel mechanism by which integrin signaling is rewired during metastasis to result in increased tumor invasiveness.
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Affiliation(s)
- Anthony Leyme
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118
| | - Arthur Marivin
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118
| | | | - Lien T Nguyen
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118
| | - Mikel Garcia-Marcos
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118
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Ma GS, Lopez-Sanchez I, Aznar N, Kalogriopoulos N, Pedram S, Midde K, Ciaraldi TP, Henry RR, Ghosh P. Activation of G proteins by GIV-GEF is a pivot point for insulin resistance and sensitivity. Mol Biol Cell 2015; 26:4209-23. [PMID: 26378251 PMCID: PMC4642855 DOI: 10.1091/mbc.e15-08-0553] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Accepted: 09/11/2015] [Indexed: 11/11/2022] Open
Abstract
A long-held tenet in the field of diabetes is that the tipping point between insulin sensitivity and resistance resides at the level of insulin receptor/insulin receptor substrate–adaptor complexes. Here it is shown that activation of Gαi by GIV/Girdin is a decisive event within the metabolic insulin signaling cascade that reversibly orchestrates insulin sensitivity or resistance. Insulin resistance (IR) is a metabolic disorder characterized by impaired insulin signaling and cellular glucose uptake. The current paradigm for insulin signaling centers upon the insulin receptor (InsR) and its substrate IRS1; the latter is believed to be the sole conduit for postreceptor signaling. Here we challenge that paradigm and show that GIV/Girdin, a guanidine exchange factor (GEF) for the trimeric G protein Gαi, is another major hierarchical conduit for the metabolic insulin response. By virtue of its ability to directly bind InsR, IRS1, and phosphoinositide 3-kinase, GIV serves as a key hub in the immediate postreceptor level, which coordinately enhances the metabolic insulin response and glucose uptake in myotubes via its GEF function. Site-directed mutagenesis or phosphoinhibition of GIV-GEF by the fatty acid/protein kinase C-theta pathway triggers IR. Insulin sensitizers reverse phosphoinhibition of GIV and reinstate insulin sensitivity. We also provide evidence for such reversible regulation of GIV-GEF in skeletal muscles from patients with IR. Thus GIV is an essential upstream component that couples InsR to G-protein signaling to enhance the metabolic insulin response, and impairment of such coupling triggers IR. We also provide evidence that GIV-GEF serves as therapeutic target for exogenous manipulation of physiological insulin response and reversal of IR in skeletal muscles.
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Affiliation(s)
- Gary S Ma
- Department of Medicine, University of California, San Diego, School of Medicine, La Jolla, CA 92093
| | - Inmaculada Lopez-Sanchez
- Department of Medicine, University of California, San Diego, School of Medicine, La Jolla, CA 92093
| | - Nicolas Aznar
- Department of Medicine, University of California, San Diego, School of Medicine, La Jolla, CA 92093
| | - Nicholas Kalogriopoulos
- Department of Medicine, University of California, San Diego, School of Medicine, La Jolla, CA 92093
| | - Shabnam Pedram
- Department of Medicine, University of California, San Diego, School of Medicine, La Jolla, CA 92093
| | - Krishna Midde
- Department of Medicine, University of California, San Diego, School of Medicine, La Jolla, CA 92093
| | - Theodore P Ciaraldi
- Department of Veterans Affairs, VA San Diego Healthcare System, San Diego, CA 92161
| | - Robert R Henry
- Department of Veterans Affairs, VA San Diego Healthcare System, San Diego, CA 92161
| | - Pradipta Ghosh
- Department of Medicine, University of California, San Diego, School of Medicine, La Jolla, CA 92093 Department of Veterans Affairs, VA San Diego Healthcare System, San Diego, CA 92161 Department of Cell and Molecular Medicine, University of California, San Diego, School of Medicine, La Jolla, CA 92093
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Cyclin-dependent kinase 5 activates guanine nucleotide exchange factor GIV/Girdin to orchestrate migration-proliferation dichotomy. Proc Natl Acad Sci U S A 2015; 112:E4874-83. [PMID: 26286990 DOI: 10.1073/pnas.1514157112] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Signals propagated by receptor tyrosine kinases (RTKs) can drive cell migration and proliferation, two cellular processes that do not occur simultaneously--a phenomenon called "migration-proliferation dichotomy." We previously showed that epidermal growth factor (EGF) signaling is skewed to favor migration over proliferation via noncanonical transactivation of Gαi proteins by the guanine exchange factor (GEF) GIV. However, what turns on GIV-GEF downstream of growth factor RTKs remained unknown. Here we reveal the molecular mechanism by which phosphorylation of GIV by cyclin-dependent kinase 5 (CDK5) triggers GIV's ability to bind and activate Gαi in response to growth factors and modulate downstream signals to establish a dichotomy between migration and proliferation. We show that CDK5 binds and phosphorylates GIV at Ser1674 near its GEF motif. When Ser1674 is phosphorylated, GIV activates Gαi and enhances promigratory Akt signals. Phosphorylated GIV also binds Gαs and enhances endosomal maturation, which shortens the transit time of EGFR through early endosomes, thereby limiting mitogenic MAPK signals. Consequently, this phosphoevent triggers cells to preferentially migrate during wound healing and transmigration of cancer cells. When Ser1674 cannot be phosphorylated, GIV cannot bind either Gαi or Gαs, Akt signaling is suppressed, mitogenic signals are enhanced due to delayed transit time of EGFR through early endosomes, and cells preferentially proliferate. These results illuminate how GIV-GEF is turned on upon receptor activation, adds GIV to the repertoire of CDK5 substrates, and defines a mechanism by which this unusual CDK orchestrates migration-proliferation dichotomy during cancer invasion, wound healing, and development.
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Ghosh P. Heterotrimeric G proteins as emerging targets for network based therapy in cancer: End of a long futile campaign striking heads of a Hydra. Aging (Albany NY) 2015; 7:469-74. [PMID: 26224586 PMCID: PMC4543036 DOI: 10.18632/aging.100781] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2015] [Accepted: 07/15/2015] [Indexed: 01/17/2023]
Abstract
Most common diseases, e.g., cancer are driven by not one, but multiple cell surface receptors that trigger and sustain a pathologic signaling network. The largest fraction of therapeutic agents that target individual receptors/pathways eventually fail due to the emergence of compensatory mechanisms that reestablish the pathologic network. Recently, a rapidly emerging paradigm has revealed GIV/Girdin as a central platform for receptor cross-talk which integrates signals downstream of a myriad of cell surface receptors, and modulates several key pathways within downstream signaling network, all via non-canonical activation of trimeric G proteins. Unlike canonical signal transduction via G proteins, which is spatially and temporally restricted, the temporal and spatial features of non-canonical activation of G protein via GIV is unusually unrestricted. Consequently, the GIV●G protein interface serves as a central hub allowing for control over several pathways within the pathologic signaling network, all at once. The relevance of this new paradigm in cancer and other disease states and the pros and cons of targeting the GIV●G protein interface are discussed.
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Affiliation(s)
- Pradipta Ghosh
- Department of Medicine, University of California at San Diego, La Jolla, CA 92093, USA
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Aznar N, Midde KK, Dunkel Y, Lopez-Sanchez I, Pavlova Y, Marivin A, Barbazán J, Murray F, Nitsche U, Janssen KP, Willert K, Goel A, Abal M, Garcia-Marcos M, Ghosh P. Daple is a novel non-receptor GEF required for trimeric G protein activation in Wnt signaling. eLife 2015; 4:e07091. [PMID: 26126266 PMCID: PMC4484057 DOI: 10.7554/elife.07091] [Citation(s) in RCA: 90] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2015] [Accepted: 06/01/2015] [Indexed: 12/17/2022] Open
Abstract
Wnt signaling is essential for tissue homeostasis and its dysregulation causes cancer. Wnt ligands trigger signaling by activating Frizzled receptors (FZDRs), which belong to the G-protein coupled receptor superfamily. However, the mechanisms of G protein activation in Wnt signaling remain controversial. In this study, we demonstrate that FZDRs activate G proteins and trigger non-canonical Wnt signaling via the Dishevelled-binding protein, Daple. Daple contains a Gα-binding and activating (GBA) motif, which activates Gαi proteins and an adjacent domain that directly binds FZDRs, thereby linking Wnt stimulation to G protein activation. This triggers non-canonical Wnt responses, that is, suppresses the β-catenin/TCF/LEF pathway and tumorigenesis, but enhances PI3K-Akt and Rac1 signals and tumor cell invasiveness. In colorectal cancers, Daple is suppressed during adenoma-to-carcinoma transformation and expressed later in metastasized tumor cells. Thus, Daple activates Gαi and enhances non-canonical Wnt signaling by FZDRs, and its dysregulation can impact both tumor initiation and progression to metastasis.
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Affiliation(s)
- Nicolas Aznar
- Department of Medicine, University of California, San Diego, San Diego, United States
| | - Krishna K Midde
- Department of Medicine, University of California, San Diego, San Diego, United States
| | - Ying Dunkel
- Department of Medicine, University of California, San Diego, San Diego, United States
| | | | - Yelena Pavlova
- Department of Medicine, University of California, San Diego, San Diego, United States
| | - Arthur Marivin
- Department of Biochemistry, Boston University School of Medicine, Boston, United States
| | - Jorge Barbazán
- Translational Medical Oncology Laboratory, Health Research Institute of Santiago, Servizo Galego de Saúde, Santiago de Compostela, Spain
| | - Fiona Murray
- Department of Medicine, University of California, San Diego, San Diego, United States
| | - Ulrich Nitsche
- Department of Surgery, Klinikum rechts der Isar, Technische Universität München, Munich, Germany
| | - Klaus-Peter Janssen
- Department of Surgery, Klinikum rechts der Isar, Technische Universität München, Munich, Germany
| | - Karl Willert
- Sanford Consortium for Regenerative Medicine, University of California, San Diego, La Jolla, California, United States
| | - Ajay Goel
- Division of Gastroenterology, Department of Internal Medicine and Charles A Sammons Cancer Center and Baylor Research Institute, Baylor University Medical Center, Dallas, Texas, United States
| | - Miguel Abal
- Translational Medical Oncology Laboratory, Health Research Institute of Santiago, Servizo Galego de Saúde, Santiago de Compostela, Spain
| | - Mikel Garcia-Marcos
- Department of Biochemistry, Boston University School of Medicine, Boston, United States
| | - Pradipta Ghosh
- Department of Medicine, University of California, San Diego, San Diego, United States
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Abstract
Environmental cues are transmitted to the interior of the cell via a complex network of signaling hubs. Receptor tyrosine kinases (RTKs) and trimeric G proteins are 2 such major signaling hubs in eukaryotes. Canonical signal transduction via trimeric G proteins is spatially and temporally restricted, i.e., triggered exclusively at the plasma membrane (PM) by agonist activation of G-protein-coupled receptors (GPCRs) via a process that completes within a few hundred milliseconds. Recently, a rapidly emerging paradigm has revealed a non-canonical pathway for activation of trimeric G proteins by the non-receptor GEF, GIV/Girdin, that has distinctive temporal and spatial features. Such activation can be triggered by multiple growth factor RTKs, can occur at the PM and on internal membranes discontinuous with the PM, and can continue for prolonged periods of time. The molecular mechanisms that govern such non-canonical G protein activation and the relevance of this new paradigm in health and disease is discussed.
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Affiliation(s)
- Pradipta Ghosh
- a Department of Medicine ; University of California at San Diego ; La Jolla , CA USA
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