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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] [Grants] [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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Nürnberg B, Beer-Hammer S, Reisinger E, Leiss V. Non-canonical G protein signaling. Pharmacol Ther 2024; 255:108589. [PMID: 38295906 DOI: 10.1016/j.pharmthera.2024.108589] [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: 07/03/2023] [Revised: 12/18/2023] [Accepted: 01/08/2024] [Indexed: 02/17/2024]
Abstract
The original paradigm of classical - also referred to as canonical - cellular signal transduction of heterotrimeric G proteins (G protein) is defined by a hierarchical, orthograde interaction of three players: the agonist-activated G protein-coupled receptor (GPCR), which activates the transducing G protein, that in turn regulates its intracellular effectors. This receptor-transducer-effector concept was extended by the identification of regulators and adapters such as the regulators of G protein signaling (RGS), receptor kinases like βARK, or GPCR-interacting arrestin adapters that are integrated into this canonical signaling process at different levels to enable fine-tuning. Finally, the identification of atypical signaling mechanisms of classical regulators, together with the discovery of novel modulators, added a new and fascinating dimension to the cellular G protein signal transduction. This heterogeneous group of accessory G protein modulators was coined "activators of G protein signaling" (AGS) proteins and plays distinct roles in canonical and non-canonical G protein signaling pathways. AGS proteins contribute to the control of essential cellular functions such as cell development and division, intracellular transport processes, secretion, autophagy or cell movements. As such, they are involved in numerous biological processes that are crucial for diseases, like diabetes mellitus, cancer, and stroke, which represent major health burdens. Although the identification of a large number of non-canonical G protein signaling pathways has broadened the spectrum of this cellular communication system, their underlying mechanisms, functions, and biological effects are poorly understood. In this review, we highlight and discuss atypical G protein-dependent signaling mechanisms with a focus on inhibitory G proteins (Gi) involved in canonical and non-canonical signal transduction, review recent developments and open questions, address the potential of new approaches for targeted pharmacological interventions.
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Affiliation(s)
- Bernd Nürnberg
- Department of Pharmacology, Experimental Therapy and Toxicology, Institute of Experimental and Clinical Pharmacology and Pharmacogenomics, and ICePhA Mouse Clinic, University of Tübingen, Wilhelmstraße 56, D-72074 Tübingen, Germany.
| | - Sandra Beer-Hammer
- Department of Pharmacology, Experimental Therapy and Toxicology, Institute of Experimental and Clinical Pharmacology and Pharmacogenomics, and ICePhA Mouse Clinic, University of Tübingen, Wilhelmstraße 56, D-72074 Tübingen, Germany
| | - Ellen Reisinger
- Gene Therapy for Hearing Impairment Group, Department of Otolaryngology - Head & Neck Surgery, University of Tübingen Medical Center, Elfriede-Aulhorn-Straße 5, D-72076 Tübingen, Germany
| | - Veronika Leiss
- Department of Pharmacology, Experimental Therapy and Toxicology, Institute of Experimental and Clinical Pharmacology and Pharmacogenomics, and ICePhA Mouse Clinic, University of Tübingen, Wilhelmstraße 56, D-72074 Tübingen, Germany
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3
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Campagna CM, McMahon H, Nechipurenko I. The G protein alpha chaperone and guanine-nucleotide exchange factor RIC-8 regulates cilia morphogenesis in Caenorhabditis elegans sensory neurons. PLoS Genet 2023; 19:e1011015. [PMID: 37910589 PMCID: PMC10642896 DOI: 10.1371/journal.pgen.1011015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2023] [Revised: 11/13/2023] [Accepted: 10/12/2023] [Indexed: 11/03/2023] Open
Abstract
Heterotrimeric G (αβγ) proteins are canonical transducers of G-protein-coupled receptor (GPCR) signaling and play critical roles in communication between cells and their environment. Many GPCRs and heterotrimeric G proteins localize to primary cilia and modulate cilia morphology via mechanisms that are not well understood. Here, we show that RIC-8, a cytosolic guanine nucleotide exchange factor (GEF) and chaperone for Gα protein subunits, shapes cilia membrane morphology in a subset of Caenorhabditis elegans sensory neurons. Consistent with its role in ciliogenesis, C. elegans RIC-8 localizes to cilia in different sensory neuron types. Using domain mutagenesis, we demonstrate that while the GEF function alone is not sufficient, both the GEF and Gα-interacting chaperone motifs of RIC-8 are required for its role in cilia morphogenesis. We identify ODR-3 as the RIC-8 Gα client and demonstrate that RIC-8 functions in the same genetic pathway with another component of the non-canonical G protein signaling AGS-3 to shape cilia morphology. Notably, despite defects in AWC cilia morphology, ags-3 null mutants exhibit normal chemotaxis toward benzaldehyde unlike odr-3 mutant animals. Collectively, our findings describe a novel function for the evolutionarily conserved protein RIC-8 and non-canonical RIC-8-AGS-3-ODR-3 signaling in cilia morphogenesis and uncouple Gα ODR-3 functions in ciliogenesis and olfaction.
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Affiliation(s)
- Christina M. Campagna
- Department of Biology and Biotechnology, Worcester Polytechnic Institute, Worcester, Massachusetts, United States of America
| | - Hayley McMahon
- Department of Biology and Biotechnology, Worcester Polytechnic Institute, Worcester, Massachusetts, United States of America
| | - Inna Nechipurenko
- Department of Biology and Biotechnology, Worcester Polytechnic Institute, Worcester, Massachusetts, United States of America
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4
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Campagna CM, McMahon H, Nechipurenko I. The G protein alpha Chaperone and Guanine-Nucleotide Exchange Factor RIC-8 Regulates Cilia Morphogenesis in Caenorhabditis elegans Sensory Neurons. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.25.554856. [PMID: 37662329 PMCID: PMC10473713 DOI: 10.1101/2023.08.25.554856] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/05/2023]
Abstract
Heterotrimeric G (αβγ) proteins are canonical transducers of G-protein-coupled receptor (GPCR) signaling and play critical roles in communication between cells and their environment. Many GPCRs and heterotrimeric G proteins localize to primary cilia and modulate cilia morphology via mechanisms that are not well understood. Here, we show that RIC-8, a cytosolic guanine nucleotide exchange factor (GEF) and chaperone for Gα protein subunits, shapes cilia membrane morphology in a subset of Caenorhabditis elegans sensory neurons. Consistent with its role in ciliogenesis, C. elegans RIC-8 localizes to cilia in different sensory neuron types. Using domain mutagenesis, we demonstrate that while the GEF function alone is not sufficient, both the GEF and Gα-interacting chaperone motifs of RIC-8 are required for its role in cilia morphogenesis. We identify ODR-3 as the RIC-8 Gα client and demonstrate that RIC-8 functions in the same genetic pathway with another component of the non-canonical G protein signaling AGS-3 to shape cilia morphology. Notably, despite severe defects in AWC cilia morphology, ags-3 null mutants exhibit normal chemotaxis toward benzaldehyde unlike odr-3 mutant animals. Collectively, our findings describe a novel function for the evolutionarily conserved protein RIC-8 and non-canonical RIC-8-AGS-3-ODR-3 signaling in cilia morphogenesis and uncouple Gα ODR-3 functions in ciliogenesis and olfaction.
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Affiliation(s)
- Christina M. Campagna
- Department of Biology and Biotechnology, Worcester Polytechnic Institute, Worcester, Massachusetts, United States of America
| | - Hayley McMahon
- Department of Biology and Biotechnology, Worcester Polytechnic Institute, Worcester, Massachusetts, United States of America
| | - Inna Nechipurenko
- Department of Biology and Biotechnology, Worcester Polytechnic Institute, Worcester, Massachusetts, United States of America
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5
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Papasergi-Scott MM, Kwarcinski FE, Yu M, Panova O, Ovrutsky AM, Skiniotis G, Tall GG. Structures of Ric-8B in complex with Gα protein folding clients reveal isoform specificity mechanisms. Structure 2023; 31:553-564.e7. [PMID: 36931277 PMCID: PMC10164081 DOI: 10.1016/j.str.2023.02.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 01/23/2023] [Accepted: 02/20/2023] [Indexed: 03/18/2023]
Abstract
Mammalian Ric-8 proteins act as chaperones to regulate the cellular abundance of heterotrimeric G protein α subunits. The Ric-8A isoform chaperones Gαi/o, Gα12/13, and Gαq/11 subunits, while Ric-8B acts on Gαs/olf subunits. Here, we determined cryoelectron microscopy (cryo-EM) structures of Ric-8B in complex with Gαs and Gαolf, revealing isoform differences in the relative positioning and contacts between the C-terminal α5 helix of Gα within the concave pocket formed by Ric-8 α-helical repeat elements. Despite the overall architectural similarity with our earlier structures of Ric-8A complexed to Gαq and Gαi1, Ric-8B distinctly accommodates an extended loop found only in Gαs/olf proteins. The structures, along with results from Ric-8 protein thermal stability assays and cell-based Gαolf folding assays, support a requirement for the Gα C-terminal region for binding specificity, and highlight that multiple structural elements impart specificity for Ric-8/G protein binding.
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Affiliation(s)
- Makaía M Papasergi-Scott
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Frank E Kwarcinski
- Department of Pharmacology, University of Michigan School of Medicine, Ann Arbor, MI 48109, USA
| | - Maiya Yu
- Department of Pharmacology, University of Michigan School of Medicine, Ann Arbor, MI 48109, USA
| | - Ouliana Panova
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Ann M Ovrutsky
- Department of Pharmacology, University of Michigan School of Medicine, Ann Arbor, MI 48109, USA
| | - Georgios Skiniotis
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA.
| | - Gregory G Tall
- Department of Pharmacology, University of Michigan School of Medicine, Ann Arbor, MI 48109, USA.
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6
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Zhang Y, Zhou B, Sun J, He Q, Zhao Y. Knockdown of GPSM1 Inhibits the Proliferation and Promotes the Apoptosis of B-Cell Acute Lymphoblastic Leukemia Cells by Suppressing the ADCY6-RAPGEF3-JNK Signaling Pathway. Pathol Oncol Res 2021; 27:643376. [PMID: 34257610 PMCID: PMC8262160 DOI: 10.3389/pore.2021.643376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 03/01/2021] [Indexed: 12/24/2022]
Abstract
B-cell acute lymphoblastic leukemia (B-ALL) is the common type of blood cancer. Although the remission rate has increased, the current treatment options for B-ALL are usually related to adverse reactions and recurrence, so it is necessary to find other treatment options. G protein signaling modulator 1 (GPSM1) is one of several factors that affect the basic activity of the G protein signaling system, but its role in B-ALL has not yet been clarified. In this study, we analyzed the expression of GPSM1 in the Oncomine database and found that the GPSM1 levels were higher in B-ALL cells than in peripheral blood mononuclear cells (PBMCs). Analyses of the Gene Expression Profiling Interactive Analysis (GEPIA) demonstrated that patients with high GPSM1 levels had shorter survival times than those with low levels. Additionally, gene set enrichment analysis (GSEA) suggested that GPSM1 was positively correlated with proliferation, G protein-coupled receptor (GPCR) ligand binding, Gαs signaling and calcium signaling pathways. In further experiments, GPSM1 was found to be highly expressed in Acute lymphoblastic leukemia (ALL) cell lines, and downregulation of GPSM1 inhibited proliferation and promoted cell cycle arrest and apoptosis in BALL-1 and Reh cells. Moreover, knockdown of GPSM1 suppressed ADCY6 and RAPGEF3 expression in BALL-1 and Reh cells. Furthermore, we reported that GPSM1 regulated JNK expression via ADCY6-RAPGEF3. The present study demonstrates that GPSM1 promotes tumor growth in BALL-1 and Reh cells by modulating ADCY6-RAPGEF3-JNK signaling.
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Affiliation(s)
- Ye Zhang
- Key Laboratory of Cell Biology of Ministry of Public Health, and Key Laboratory of Medical Cell Biology of Ministry of Education, China Medical University, Shenyang, China.,Department of Bioinformatics, School of Life Sciences, China Medical University, Shenyang, China
| | - Bo Zhou
- Key Laboratory of Cell Biology of Ministry of Public Health, and Key Laboratory of Medical Cell Biology of Ministry of Education, China Medical University, Shenyang, China.,Department of Bioinformatics, School of Life Sciences, China Medical University, Shenyang, China
| | - Jingjing Sun
- Key Laboratory of Cell Biology of Ministry of Public Health, and Key Laboratory of Medical Cell Biology of Ministry of Education, China Medical University, Shenyang, China.,Department of Bioinformatics, School of Life Sciences, China Medical University, Shenyang, China
| | - Qun He
- Department of Bioinformatics, School of Life Sciences, China Medical University, Shenyang, China
| | - Yujie Zhao
- Key Laboratory of Cell Biology of Ministry of Public Health, and Key Laboratory of Medical Cell Biology of Ministry of Education, China Medical University, Shenyang, China
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7
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Nie ZW, Niu YJ, Zhou W, Zhou DJ, Kim JY, Cui XS. AGS3-dependent trans-Golgi network membrane trafficking is essential for compaction in mouse embryos. J Cell Sci 2020; 133:jcs.243238. [PMID: 33148610 DOI: 10.1242/jcs.243238] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2019] [Accepted: 10/26/2020] [Indexed: 11/20/2022] Open
Abstract
Activator of G-protein signaling 3 (AGS3, also known as GPSM1) regulates the trans-Golgi network. The AGS3 GoLoco motif binds to Gαi and thereby regulates the transport of proteins to the plasma membrane. Compaction of early embryos is based on the accumulation of E-cadherin (Cdh1) at cell-contacted membranes. However, how AGS3 regulates the transport of Cdh1 to the plasma membrane remains undetermined. To investigate this, AGS3 was knocked out using the Cas9-sgRNA system. Both trans-Golgi network protein 46 (TGN46, also known as TGOLN2) and transmembrane p24-trafficking protein 7 (TMED7) were tracked in early mouse embryos by tagging these proteins with a fluorescent protein label. We observed that the majority of the AGS3-edited embryos were developmentally arrested and were fragmented after the four-cell stage, exhibiting decreased accumulation of Cdh1 at the membrane. The trans-Golgi network and TMED7-positive vesicles were also dispersed and were not polarized near the membrane. Additionally, increased Gαi1 (encoded by GNAI1) expression could rescue AGS3-overexpressed embryos. In conclusion, AGS3 reinforces the dynamics of the trans-Golgi network and the transport of TMED7-positive cargo containing Cdh1 to the cell-contact surface during early mouse embryo development.
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Affiliation(s)
- Zheng-Wen Nie
- Department of Animal Sciences, Chungbuk National University, Chungbuk, Cheongju 361-763, Republic of Korea
| | - Ying-Jie Niu
- Department of Animal Sciences, Chungbuk National University, Chungbuk, Cheongju 361-763, Republic of Korea
| | - Wenjun Zhou
- Department of Animal Sciences, Chungbuk National University, Chungbuk, Cheongju 361-763, Republic of Korea
| | - Dong-Jie Zhou
- Department of Animal Sciences, Chungbuk National University, Chungbuk, Cheongju 361-763, Republic of Korea
| | - Ju-Yeon Kim
- Department of Animal Sciences, Chungbuk National University, Chungbuk, Cheongju 361-763, Republic of Korea
| | - Xiang-Shun Cui
- Department of Animal Sciences, Chungbuk National University, Chungbuk, Cheongju 361-763, Republic of Korea
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8
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Yip JLK, Lee MMK, Leung CCY, Tse MK, Cheung AST, Wong YH. AGS3 and Gα i3 Are Concomitantly Upregulated as Part of the Spindle Orientation Complex during Differentiation of Human Neural Progenitor Cells. Molecules 2020; 25:molecules25215169. [PMID: 33172018 PMCID: PMC7664263 DOI: 10.3390/molecules25215169] [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] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 10/29/2020] [Accepted: 11/03/2020] [Indexed: 11/16/2022] Open
Abstract
Adult neurogenesis is modulated by many Gi-coupled receptors but the precise mechanism remains elusive. A key step for maintaining the population of neural stem cells in the adult is asymmetric cell division (ACD), a process which entails the formation of two evolutionarily conserved protein complexes that establish the cell polarity and spindle orientation. Since ACD is extremely difficult to monitor in stratified tissues such as the vertebrate brain, we employed human neural progenitor cell lines to examine the regulation of the polarity and spindle orientation complexes during neuronal differentiation. Several components of the spindle orientation complex, but not those of the polarity complex, were upregulated upon differentiation of ENStem-A and ReNcell VM neural progenitor cells. Increased expression of nuclear mitotic apparatus (NuMA), Gαi subunit, and activators of G protein signaling (AGS3 and LGN) coincided with the appearance of a neuronal marker (β-III tubulin) and the concomitant loss of neural progenitor cell markers (nestin and Sox-2). Co-immunoprecipitation assays demonstrated that both Gαi3 and NuMA were associated with AGS3 in differentiated ENStem-A cells. Interestingly, AGS3 appeared to preferentially interact with Gαi3 in ENStem-A cells, and this specificity for Gαi3 was recapitulated in co-immunoprecipitation experiments using HEK293 cells transiently overexpressing GST-tagged AGS3 and different Gαi subunits. Moreover, the binding of Gαi3 to AGS3 was suppressed by GTPγS and pertussis toxin. Disruption of AGS3/Gαi3 interaction by pertussis toxin indicates that AGS3 may recognize the same site on the Gα subunit as G protein-coupled receptors. Regulatory mechanisms controlling the formation of spindle orientation complex may provide novel means to manipulate ACD which in turn may have an impact on neurogenesis.
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Affiliation(s)
- Jackson L. K. Yip
- Division of Life Science and the Biotechnology Research Institute, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong 999077, China; (J.L.K.Y.); (M.M.K.L.); (C.C.Y.L.); (M.K.T.); (A.S.T.C.)
| | - Maggie M. K. Lee
- Division of Life Science and the Biotechnology Research Institute, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong 999077, China; (J.L.K.Y.); (M.M.K.L.); (C.C.Y.L.); (M.K.T.); (A.S.T.C.)
| | - Crystal C. Y. Leung
- Division of Life Science and the Biotechnology Research Institute, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong 999077, China; (J.L.K.Y.); (M.M.K.L.); (C.C.Y.L.); (M.K.T.); (A.S.T.C.)
| | - Man K. Tse
- Division of Life Science and the Biotechnology Research Institute, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong 999077, China; (J.L.K.Y.); (M.M.K.L.); (C.C.Y.L.); (M.K.T.); (A.S.T.C.)
| | - Annie S. T. Cheung
- Division of Life Science and the Biotechnology Research Institute, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong 999077, China; (J.L.K.Y.); (M.M.K.L.); (C.C.Y.L.); (M.K.T.); (A.S.T.C.)
| | - Yung H. Wong
- Division of Life Science and the Biotechnology Research Institute, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong 999077, China; (J.L.K.Y.); (M.M.K.L.); (C.C.Y.L.); (M.K.T.); (A.S.T.C.)
- State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong 999077, China
- Correspondence: ; Tel.: +852-2358-7328; Fax: +852-2358-1552
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9
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Adekoya TO, Smith N, Aladeniyi T, Blumer JB, Chen XL, Richardson RM. Activator of G protein signaling 3 modulates prostate tumor development and progression. Carcinogenesis 2020; 40:1504-1513. [PMID: 31215992 DOI: 10.1093/carcin/bgz076] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Revised: 04/05/2019] [Accepted: 04/22/2019] [Indexed: 12/24/2022] Open
Abstract
Prostate cancer (PCa) is a leading cause of cancer death among men, with greater prevalence of the disease among the African American population in the USA. Activator of G-protein signaling 3 (AGS3/G-protein signaling modulator 1) was shown to be overexpressed in prostate adenocarcinoma relative to the prostate gland. In this study, we investigated the correlation between AGS3 overexpression and PCa malignancy. Immunoblotting analysis and real-time quantitative-PCR showed increase in AGS3 expression in the metastatic cell lines LNCaP (~3-fold), MDA PCa 2b (~2-fold), DU 145 (~2-fold) and TRAMP-C1 (~20-fold) but not in PC3 (~1-fold), relative to control RWPE-1. Overexpression of AGS3 in PC3, LNCaP and MDA PCa 2b enhanced tumor growth. AGS3 contains seven tetratricopeptide repeats (TPR) and four G-protein regulatory (GPR) motifs. Overexpression of the TPR or the GPR motifs in PC3 cells had no effect in tumor growth. Depletion of AGS3 in the TRAMP-C1 cells (TRAMP-C1-AGS3-/-) decreased cell proliferation and delayed wound healing and tumor growth in both C57BL/6 (~3-fold) and nude mice xenografts, relative to control TRAMP-C1 cells. TRAMP-C1-AGS3-/- tumors also exhibited a marked increase (~5-fold) in both extracellular signal-regulated kinase (ERK) 1/2 and P38 mitogen-activated protein kinase (MAPK) activation, which correlated with a significant increase (~3-fold) in androgen receptor (AR) expression, relative to TRAMP-C1 xenografts. Interestingly, overexpression of AGS3 in TRAMP-C1-AGS3-/- cells inhibited ERK activation and AR overexpression as compared with control TRAMP-C1 cells. Taken together, the data indicate that the effect of AGS3 in prostate cancer development and progression is probably mediated via a MAPK/AR-dependent pathway.
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Affiliation(s)
- Timothy O Adekoya
- Julius L. Chambers Biomedical/Biotechnology Research Institute, North Carolina Central University, Durham, NC, USA.,Department of Biological and Biomedical Sciences, North Carolina Central University, Durham, NC, USA
| | - Nikia Smith
- Julius L. Chambers Biomedical/Biotechnology Research Institute, North Carolina Central University, Durham, NC, USA
| | - Temilade Aladeniyi
- Julius L. Chambers Biomedical/Biotechnology Research Institute, North Carolina Central University, Durham, NC, USA
| | - Joe B Blumer
- Department of Cell and Molecular Pharmacology and Experimental Therapeutics, Medical University of South Carolina, Charleston, SC, USA
| | - Xiaoxin L Chen
- Julius L. Chambers Biomedical/Biotechnology Research Institute, North Carolina Central University, Durham, NC, USA.,Department of Biological and Biomedical Sciences, North Carolina Central University, Durham, NC, USA
| | - Ricardo M Richardson
- Julius L. Chambers Biomedical/Biotechnology Research Institute, North Carolina Central University, Durham, NC, USA.,Department of Biological and Biomedical Sciences, North Carolina Central University, Durham, NC, USA
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10
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Seven AB, Hilger D, Papasergi-Scott MM, Zhang L, Qu Q, Kobilka BK, Tall GG, Skiniotis G. Structures of Gα Proteins in Complex with Their Chaperone Reveal Quality Control Mechanisms. Cell Rep 2020; 30:3699-3709.e6. [PMID: 32126208 PMCID: PMC7192526 DOI: 10.1016/j.celrep.2020.02.086] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2019] [Revised: 01/31/2020] [Accepted: 02/24/2020] [Indexed: 01/14/2023] Open
Abstract
Many chaperones promote nascent polypeptide folding followed by substrate release through ATP-dependent conformational changes. Here we show cryoEM structures of Gα subunit folding intermediates in complex with full-length Ric-8A, a unique chaperone-client system in which substrate release is facilitated by guanine nucleotide binding to the client G protein. The structures of Ric-8A-Gαi and Ric-8A-Gαq complexes reveal that the chaperone employs its extended C-terminal region to cradle the Ras-like domain of Gα, positioning the Ras core in contact with the Ric-8A core while engaging its switch2 nucleotide binding region. The C-terminal α5 helix of Gα is held away from the Ras-like domain through Ric-8A core domain interactions, which critically depend on recognition of the Gα C terminus by the chaperone. The structures, complemented with biochemical and cellular chaperoning data, support a folding quality control mechanism that ensures proper formation of the C-terminal α5 helix before allowing GTP-gated release of Gα from Ric-8A.
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Affiliation(s)
- Alpay Burak Seven
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Daniel Hilger
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA.
| | - Makaía M Papasergi-Scott
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Li Zhang
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Qianhui Qu
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Brian K Kobilka
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Gregory G Tall
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI 48109, USA.
| | - Georgios Skiniotis
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA.
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11
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Srivastava D, Artemyev NO. Ric-8A, a GEF, and a Chaperone for G Protein α-Subunits: Evidence for the Two-Faced Interface. Bioessays 2020; 42:e1900208. [PMID: 31967346 PMCID: PMC7034654 DOI: 10.1002/bies.201900208] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Revised: 12/30/2019] [Indexed: 12/21/2022]
Abstract
Resistance to inhibitors of cholinesterase 8A (Ric-8A) is a prominent non-receptor GEF and a chaperone of G protein α-subunits (Gα). Recent studies shed light on the structure of Ric-8A, providing insights into the mechanisms underlying its interaction with Gα. Ric-8A is composed of a core armadillo-like domain and a flexible C-terminal tail. Interaction of a conserved concave surface of its core domain with the Gα C-terminus appears to mediate formation of the initial Ric-8A/GαGDP intermediate, followed by the formation of a stable nucleotide-free complex. The latter event involves a large-scale dislocation of the Gα α5-helix that produces an extensive primary interface and disrupts the nucleotide-binding site of Gα. The distal portion of the C-terminal tail of Ric-8A forms a smaller secondary interface, which ostensibly binds the switch II region of Gα, facilitating binding of GTP. The two-site Gα interface of Ric-8A is distinct from that of GPCRs, and might have evolved to support the chaperone function of Ric-8A.
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Affiliation(s)
- Dhiraj Srivastava
- Department of Molecular Physiology and Biophysics, The University of Iowa Carver College of Medicine, Iowa City, IA 52242
| | - Nikolai O. Artemyev
- Department of Molecular Physiology and Biophysics, The University of Iowa Carver College of Medicine, Iowa City, IA 52242
- Department of Ophthalmology and Visual Sciences, The University of Iowa Carver College of Medicine, Iowa City, IA 52242
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12
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McClelland LJ, Zhang K, Mou TC, Johnston J, Yates-Hansen C, Li S, Thomas CJ, Doukov TI, Triest S, Wohlkonig A, Tall GG, Steyaert J, Chiu W, Sprang SR. Structure of the G protein chaperone and guanine nucleotide exchange factor Ric-8A bound to Gαi1. Nat Commun 2020; 11:1077. [PMID: 32103024 PMCID: PMC7044438 DOI: 10.1038/s41467-020-14943-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2020] [Accepted: 02/10/2020] [Indexed: 12/24/2022] Open
Abstract
Ric-8A is a cytosolic Guanine Nucleotide exchange Factor (GEF) that activates heterotrimeric G protein alpha subunits (Gα) and serves as an essential Gα chaperone. Mechanisms by which Ric-8A catalyzes these activities, which are stimulated by Casein Kinase II phosphorylation, are unknown. We report the structure of the nanobody-stabilized complex of nucleotide-free Gα bound to phosphorylated Ric-8A at near atomic resolution by cryo-electron microscopy and X-ray crystallography. The mechanism of Ric-8A GEF activity differs considerably from that employed by G protein-coupled receptors at the plasma membrane. Ric-8A engages a specific conformation of Gα at multiple interfaces to form a complex that is stabilized by phosphorylation within a Ric-8A segment that connects two Gα binding sites. The C-terminus of Gα is ejected from its beta sheet core, thereby dismantling the GDP binding site. Ric-8A binds to the exposed Gα beta sheet and switch II to stabilize the nucleotide-free state of Gα.
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Affiliation(s)
- Levi J McClelland
- Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, MT, 59812, USA
| | - Kaiming Zhang
- Department of Bioengineering and James H. Clark Center, Stanford University, Stanford, CA, 94305, USA
| | - Tung-Chung Mou
- Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, MT, 59812, USA
- Division of Biological Sciences, University of Montana, Missoula, MT, 59812, USA
| | - Jake Johnston
- Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, MT, 59812, USA
- Division of Biological Sciences, University of Montana, Missoula, MT, 59812, USA
| | - Cindee Yates-Hansen
- Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, MT, 59812, USA
| | - Shanshan Li
- Department of Bioengineering and James H. Clark Center, Stanford University, Stanford, CA, 94305, USA
| | - Celestine J Thomas
- Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, MT, 59812, USA
- Regeneron Pharmaceutical, Inc., Tarrytown, NY, USA
| | - Tzanko I Doukov
- Macromolecular Crystallography Group, Stanford Synchrotron Radiation Light Source, SLAC National Accelerator Laboratory, Stanford University, Stanford, CA, 94025, USA
| | - Sarah Triest
- Structural Biology Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium
- VIB-VUB Center for Structural Biology, VIB, Brussels, Belgium
| | - Alexandre Wohlkonig
- Structural Biology Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium
- VIB-VUB Center for Structural Biology, VIB, Brussels, Belgium
| | - Gregory G Tall
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
| | - Jan Steyaert
- Structural Biology Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium
- VIB-VUB Center for Structural Biology, VIB, Brussels, Belgium
| | - Wah Chiu
- Department of Bioengineering and James H. Clark Center, Stanford University, Stanford, CA, 94305, USA.
- Biosciences Division of CryoEM and Bioimaging, SSRL, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, CA, 94025, USA.
| | - Stephen R Sprang
- Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, MT, 59812, USA.
- Division of Biological Sciences, University of Montana, Missoula, MT, 59812, USA.
- Graduate Program in Biochemistry and Biophysics, University of Montana, Missoula, MT, 59812, USA.
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13
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Rajarathnam K, Schnoor M, Richardson RM, Rajagopal S. How do chemokines navigate neutrophils to the target site: Dissecting the structural mechanisms and signaling pathways. Cell Signal 2019; 54:69-80. [PMID: 30465827 PMCID: PMC6664297 DOI: 10.1016/j.cellsig.2018.11.004] [Citation(s) in RCA: 142] [Impact Index Per Article: 28.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Revised: 11/07/2018] [Accepted: 11/08/2018] [Indexed: 12/12/2022]
Abstract
Chemokines play crucial roles in combating microbial infection and initiating tissue repair by recruiting neutrophils in a timely and coordinated manner. In humans, no less than seven chemokines (CXCL1, CXCL2, CXCL3, CXCL5, CXCL6, CXCL7, and CXCL8) and two receptors (CXCR1 and CXCR2) mediate neutrophil functions but in a context dependent manner. Neutrophil-activating chemokines reversibly exist as monomers and dimers, and their receptor binding triggers conformational changes that are coupled to G-protein and β-arrestin signaling pathways. G-protein signaling activates a variety of effectors including Ca2+ channels and phospholipase C. β-arrestin serves as a multifunctional adaptor and is coupled to several signaling hubs including MAP kinase and tyrosine kinase pathways. Both G-protein and β-arrestin signaling pathways play important non-overlapping roles in neutrophil trafficking and activation. Functional studies have established many similarities but distinct differences for a given chemokine and between chemokines at the level of monomer vs. dimer, CXCR1 vs. CXCR2 activation, and G-protein vs. β-arrestin pathways. We propose that two forms of the ligand binding two receptors and activating two signaling pathways enables fine-tuned neutrophil function compared to a single form, a single receptor, or a single pathway. We summarize the current knowledge on the molecular mechanisms by which chemokine monomers/dimers activate CXCR1/CXCR2 and how these interactions trigger G-protein/β-arrestin-coupled signaling pathways. We also discuss current challenges and knowledge gaps, and likely advances in the near future that will lead to a better understanding of the relationship between the chemokine-CXCR1/CXCR2-G-protein/β-arrestin axis and neutrophil function.
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Affiliation(s)
- Krishna Rajarathnam
- Department of Biochemistry and Molecular Biology, Department of Microbiology and Immunology, Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX, USA.
| | - Michael Schnoor
- Department for Molecular Biomedicine, Cinvestav-IPN, 07360 Mexico City, Mexico
| | - Ricardo M Richardson
- Julius L. Chambers Biomedical/Biotechnology Research Institute, North Carolina Central University, Durham, NC 27707, USA
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14
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Papasergi-Scott MM, Stoveken HM, MacConnachie L, Chan PY, Gabay M, Wong D, Freeman RS, Beg AA, Tall GG. Dual phosphorylation of Ric-8A enhances its ability to mediate G protein α subunit folding and to stimulate guanine nucleotide exchange. Sci Signal 2018; 11:11/532/eaap8113. [PMID: 29844055 DOI: 10.1126/scisignal.aap8113] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Resistance to inhibitors of cholinesterase-8A (Ric-8A) and Ric-8B are essential biosynthetic chaperones for heterotrimeric G protein α subunits. We provide evidence for the direct regulation of Ric-8A cellular activity by dual phosphorylation. Using proteomics, Western blotting, and mutational analyses, we determined that Ric-8A was constitutively phosphorylated at five serines and threonines by the protein kinase CK2. Phosphorylation of Ser435 and Thr440 in rat Ric-8A (corresponding to Ser436 and Thr441 in human Ric-8A) was required for high-affinity binding to Gα subunits, efficient stimulation of Gα subunit guanine nucleotide exchange, and mediation of Gα subunit folding. The CK2 consensus sites that contain Ser435 and Thr440 are conserved in Ric-8 homologs from worms to mammals. We found that the homologous residues in mouse Ric-8B, Ser468 and Ser473, were also phosphorylated. Mutation of the genomic copy of ric-8 in Caenorhabditis elegans to encode alanine in the homologous sites resulted in characteristic ric-8 reduction-of-function phenotypes that are associated with defective Gq and Gs signaling, including reduced locomotion and defective egg laying. The C. elegans ric-8 phosphorylation site mutant phenotypes were partially rescued by chemical stimulation of Gq signaling. These results indicate that dual phosphorylation represents a critical form of conserved Ric-8 regulation and demonstrate that Ric-8 proteins are needed for effective Gα signaling. The position of the CK2-phosphorylated sites within a structural model of Ric-8A reveals that these sites contribute to a key acidic and negatively charged surface that may be important for its interactions with Gα subunits.
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Affiliation(s)
- Makaía M Papasergi-Scott
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Hannah M Stoveken
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Lauren MacConnachie
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Pui-Yee Chan
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Meital Gabay
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Dorothy Wong
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Robert S Freeman
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Asim A Beg
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Gregory G Tall
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI 48109, USA.
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15
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Genetic wiring maps of single-cell protein states reveal an off-switch for GPCR signalling. Nature 2017; 546:307-311. [DOI: 10.1038/nature22376] [Citation(s) in RCA: 85] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Accepted: 04/13/2017] [Indexed: 01/05/2023]
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16
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Gong B, Shen W, Xiao W, Meng Y, Meng A, Jia S. The Sec14-like phosphatidylinositol transfer proteins Sec14l3/SEC14L2 act as GTPase proteins to mediate Wnt/Ca 2+ signaling. eLife 2017; 6. [PMID: 28463110 PMCID: PMC5423769 DOI: 10.7554/elife.26362] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Accepted: 04/30/2017] [Indexed: 12/24/2022] Open
Abstract
The non-canonical Wnt/Ca2+ signaling pathway plays important roles in embryonic development, tissue formation and diseases. However, it is unclear how the Wnt ligand-stimulated, G protein-coupled receptor Frizzled activates phospholipases for calcium release. Here, we report that the zebrafish/human phosphatidylinositol transfer protein Sec14l3/SEC14L2 act as GTPase proteins to transduce Wnt signals from Frizzled to phospholipase C (PLC). Depletion of sec14l3 attenuates Wnt/Ca2+ responsive activity and causes convergent and extension (CE) defects in zebrafish embryos. Biochemical analyses in mammalian cells indicate that Sec14l3-GDP forms complex with Frizzled and Dishevelled; Wnt ligand binding of Frizzled induces translocation of Sec14l3 to the plasma membrane; and then Sec14l3-GTP binds to and activates phospholipase Cδ4a (Plcδ4a); subsequently, Plcδ4a initiates phosphatidylinositol-4,5-bisphosphate (PIP2) signaling, ultimately stimulating calcium release. Furthermore, Plcδ4a can act as a GTPase-activating protein to accelerate the hydrolysis of Sec14l3-bound GTP to GDP. Our data provide a new insight into GTPase protein-coupled Wnt/Ca2+ signaling transduction.
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Affiliation(s)
- Bo Gong
- State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China
| | - Weimin Shen
- State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China
| | - Wanghua Xiao
- State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China
| | - Yaping Meng
- State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China
| | - Anming Meng
- State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China
| | - Shunji Jia
- State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China
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17
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García-Rico RO, Fierro F. [Role of G-protein alpha sub-units in the morphogenic processes of filamentous Ascomycota fungi]. Rev Iberoam Micol 2017; 34:1-9. [PMID: 28169110 DOI: 10.1016/j.riam.2016.06.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Revised: 03/30/2016] [Accepted: 06/21/2016] [Indexed: 01/04/2023] Open
Abstract
The phylum Ascomycota comprises about 75% of all the fungal species described, and includes species of medical, phytosanitary, agricultural, and biotechnological importance. The ability to spread, explore, and colonise new substrates is a feature of critical importance for this group of organisms. In this regard, basic processes such as conidial germination, the extension of hyphae and sporulation, make up the backbone of development in most filamentous fungi. These processes require specialised morphogenic machinery, coordinated and regulated by mechanisms that are still being elucidated. In recent years, substantial progress has been made in understanding the role of the signalling pathway mediated by heterotrimericG proteins in basic biological processes of many filamentous fungi. This review focuses on the role of the alpha subunits of heterotrimericG proteins in the morphogenic processes of filamentous Ascomycota.
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Affiliation(s)
- Ramón O García-Rico
- Departamento de Microbiología, Facultad de Ciencias Básicas, Universidad de Pamplona, Pamplona, Norte de Santander, Colombia.
| | - Francisco Fierro
- Departamento de Biotecnología, Universidad Autónoma Metropolitana-Unidad Iztapalapa, Ciudad de México, Distrito Federal, México
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18
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Kant R, Zeng B, Thomas CJ, Bothner B, Sprang SR. Ric-8A, a G protein chaperone with nucleotide exchange activity induces long-range secondary structure changes in Gα. eLife 2016; 5. [PMID: 28008853 PMCID: PMC5182059 DOI: 10.7554/elife.19238] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Accepted: 11/22/2016] [Indexed: 11/24/2022] Open
Abstract
Cytosolic Ric-8A has guanine nucleotide exchange factor (GEF) activity and is a chaperone for several classes of heterotrimeric G protein α subunits in vertebrates. Using Hydrogen-Deuterium Exchange-Mass Spectrometry (HDX-MS) we show that Ric-8A disrupts the secondary structure of the Gα Ras-like domain that girds the guanine nucleotide-binding site, and destabilizes the interface between the Gαi1 Ras and helical domains, allowing domain separation and nucleotide release. These changes are largely reversed upon binding GTP and dissociation of Ric-8A. HDX-MS identifies a potential Gα interaction site in Ric-8A. Alanine scanning reveals residues crucial for GEF activity within that sequence. HDX confirms that, like G protein-coupled receptors (GPCRs), Ric-8A binds the C-terminus of Gα. In contrast to GPCRs, Ric-8A interacts with Switches I and II of Gα and possibly at the Gα domain interface. These extensive interactions provide both allosteric and direct catalysis of GDP unbinding and release and GTP binding. DOI:http://dx.doi.org/10.7554/eLife.19238.001
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Affiliation(s)
- Ravi Kant
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, United States
| | - Baisen Zeng
- Center for Biomolecular Structure and Dynamics, The University of Montana, Missoula, United States
| | - Celestine J Thomas
- Center for Biomolecular Structure and Dynamics, The University of Montana, Missoula, United States
| | - Brian Bothner
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, United States
| | - Stephen R Sprang
- Center for Biomolecular Structure and Dynamics, The University of Montana, Missoula, United States
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19
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Regulation of Airway Inflammation by G-protein Regulatory Motif Peptides of AGS3 protein. Sci Rep 2016; 6:27054. [PMID: 27270970 PMCID: PMC4895231 DOI: 10.1038/srep27054] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Accepted: 05/12/2016] [Indexed: 12/21/2022] Open
Abstract
Respiratory diseases such as asthma, chronic obstructive pulmonary disease (COPD), and lung infections have critical consequences on mortality and morbidity in humans. The aims of the present study were to examine the mechanisms by which CXCL12 affects MUC1 transcription and airway inflammation, which depend on activator of G-protein signaling (AGS) 3 and to identify specific molecules that suppress CXCL12-induced airway inflammation by acting on G-protein-coupled receptors. Herein, AGS3 suppresses CXCL12-mediated upregulation of MUC1 and TNFα by regulating Gαi. We found that the G-protein regulatory (GPR) motif peptide in AGS3 binds to Gαi and downregulates MUC1 expression; in contrast, this motif upregulates TNFα expression. Mutated GPR Q34A peptide increased the expression of MUC1 and TGFβ but decreased the expression of TNFα and IL-6. Moreover, CXCR4-induced dendritic extensions in 2D and 3D matrix cultures were inhibited by the GPR Q34A peptide compared with a wild-type GPR peptide. The GPR Q34A peptide also inhibited CXCL12-induced morphological changes and inflammatory cell infiltration in the mouse lung, and production of inflammatory cytokines in bronchoalveolar lavage (BAL) fluid and the lungs. Our data indicate that the GPR motif of AGS3 is critical for regulating MUC1/Muc1 expression and cytokine production in the inflammatory microenvironment.
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20
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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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21
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Robichaux WG, Oner SS, Lanier SM, Blumer JB. Direct Coupling of a Seven-Transmembrane-Span Receptor to a Gαi G-Protein Regulatory Motif Complex. Mol Pharmacol 2015; 88:231-7. [PMID: 25972449 DOI: 10.1124/mol.115.097741] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Accepted: 05/12/2015] [Indexed: 12/29/2022] Open
Abstract
Group II activator of G-protein signaling (AGS) proteins contain one or more G-protein regulatory motifs (GPR), which serve as docking sites for GαiGDP independent of Gβγ and stabilize the GDP-bound conformation of Gαi, acting as guanine nucleotide dissociation inhibitors. The GαGPR interaction is regulated by seven-transmembrane-spanning (7TM) receptors in the intact cell as determined by bioluminescence resonance energy transfer (BRET). It is hypothesized that a 7TM receptor directly couples to the GαGPR complex in a manner analogous to receptor coupling to the Gαβγ heterotrimer. As an initial approach to test this hypothesis, we used BRET to examine 7TM receptor-mediated regulation of GαGPR in the intact cell when Gαi2 yellow fluorescent protein (YFP) was tethered to the carboxyl terminus of the α2A adrenergic receptor (α2AAR-Gαi2YFP). AGS3- and AGS4-Renilla luciferase (Rluc) exhibited robust BRET with the tethered GαiYFP, and this interaction was regulated by receptor activation localizing the regulation to the receptor microenvironment. Agonist regulation of the receptor-Gαi-GPR complex was also confirmed by coimmunoprecipitation and cell fractionation. The tethered Gαi2 was rendered pertussis toxin-insensitive by a C352I mutation, and receptor coupling to endogenous Gαi/oβγ was subsequently eliminated by cell treatment with pertussis toxin (PT). Basal and agonist-induced regulation of α2AAR-Gαi2YFP(C352I):AGS3Rluc and α2AAR-Gαi2YFP(C352I):AGS4Rluc BRET was not altered by PT treatment or Gβγ antagonists. Thus, the localized regulation of GαGPR by receptor activation appears independent of endogenous Gαi/oβγ, suggesting that GαiAGS3 and GαiAGS4 directly sense agonist-induced conformational changes in the receptor, as is the case for 7TM receptor coupling to the Gαβγ heterotrimer. The direct coupling of a receptor to the GαiGPR complex provides an unexpected platform for signal propagation with broad implications.
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Affiliation(s)
- William G Robichaux
- Department of Cell and Molecular Pharmacology and Experimental Therapeutics (W.G.R., S.S.O., S.M.L., J.B.B.) and Department of Neurosciences (J.B.B.), Medical University of South Carolina, Charleston, South Carolina
| | - Sukru S Oner
- Department of Cell and Molecular Pharmacology and Experimental Therapeutics (W.G.R., S.S.O., S.M.L., J.B.B.) and Department of Neurosciences (J.B.B.), Medical University of South Carolina, Charleston, South Carolina
| | - Stephen M Lanier
- Department of Cell and Molecular Pharmacology and Experimental Therapeutics (W.G.R., S.S.O., S.M.L., J.B.B.) and Department of Neurosciences (J.B.B.), Medical University of South Carolina, Charleston, South Carolina
| | - Joe B Blumer
- Department of Cell and Molecular Pharmacology and Experimental Therapeutics (W.G.R., S.S.O., S.M.L., J.B.B.) and Department of Neurosciences (J.B.B.), Medical University of South Carolina, Charleston, South Carolina
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22
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Papasergi MM, Patel BR, Tall GG. The G protein α chaperone Ric-8 as a potential therapeutic target. Mol Pharmacol 2014; 87:52-63. [PMID: 25319541 DOI: 10.1124/mol.114.094664] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Resistance to inhibitors of cholinesterase (Ric-8)A and Ric-8B are essential genes that encode positive regulators of heterotrimeric G protein α subunits. Controversy persists surrounding the precise way(s) that Ric-8 proteins affect G protein biology and signaling. Ric-8 proteins chaperone nucleotide-free Gα-subunit states during biosynthetic protein folding prior to G protein heterotrimer assembly. In organisms spanning the evolutionary window of Ric-8 expression, experimental perturbation of Ric-8 genes results in reduced functional abundances of G proteins because G protein α subunits are misfolded and degraded rapidly. Ric-8 proteins also act as Gα-subunit guanine nucleotide exchange factors (GEFs) in vitro. However, Ric-8 GEF activity could strictly be an in vitro phenomenon stemming from the ability of Ric-8 to induce partial Gα unfolding, thereby enhancing GDP release. Ric-8 GEF activity clearly differs from the GEF activity of G protein-coupled receptors (GPCRs). G protein βγ is inhibitory to Ric-8 action but obligate for receptors. It remains an open question whether Ric-8 has dual functions in cells and regulates G proteins as both a molecular chaperone and GEF. Clearly, Ric-8 has a profound influence on heterotrimeric G protein function. For this reason, we propose that Ric-8 proteins are as yet untested therapeutic targets in which pharmacological inhibition of the Ric-8/Gα protein-protein interface could serve to attenuate the effects of disease-causing G proteins (constitutively active mutants) and/or GPCR signaling. This minireview will chronicle the understanding of Ric-8 function, provide a comparative discussion of the Ric-8 molecular chaperoning and GEF activities, and support the case for why Ric-8 proteins should be considered potential targets for development of new therapies.
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Affiliation(s)
- Makaía M Papasergi
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, New York
| | - Bharti R Patel
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, New York
| | - Gregory G Tall
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, New York
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23
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Canonical and noncanonical g-protein signaling helps coordinate actin dynamics to promote macrophage phagocytosis of zymosan. Mol Cell Biol 2014; 34:4186-99. [PMID: 25225330 DOI: 10.1128/mcb.00325-14] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Both chemotaxis and phagocytosis depend upon actin-driven cell protrusions and cell membrane remodeling. While chemoattractant receptors rely upon canonical G-protein signaling to activate downstream effectors, whether such signaling pathways affect phagocytosis is contentious. Here, we report that Gαi nucleotide exchange and signaling helps macrophages coordinate the recognition, capture, and engulfment of zymosan bioparticles. We show that zymosan exposure recruits F-actin, Gαi proteins, and Elmo1 to phagocytic cups and early phagosomes. Zymosan triggered an increase in intracellular Ca(2+) that was partially sensitive to Gαi nucleotide exchange inhibition and expression of GTP-bound Gαi recruited Elmo1 to the plasma membrane. Reducing GDP-Gαi nucleotide exchange, decreasing Gαi expression, pharmacologically interrupting Gβγ signaling, or reducing Elmo1 expression all impaired phagocytosis, while favoring the duration that Gαi remained GTP bound promoted it. Our studies demonstrate that targeting heterotrimeric G-protein signaling offers opportunities to enhance or retard macrophage engulfment of phagocytic targets such as zymosan.
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24
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Singh V, Raghuwanshi SK, Smith N, Rivers EJ, Richardson RM. G Protein-coupled receptor kinase-6 interacts with activator of G protein signaling-3 to regulate CXCR2-mediated cellular functions. THE JOURNAL OF IMMUNOLOGY 2014; 192:2186-94. [PMID: 24510965 DOI: 10.4049/jimmunol.1301875] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The IL-8 (CXCL8) receptors CXCR1 and CXCR2 couple to Gαi to induce leukocyte recruitment and activation at sites of inflammation. We recently showed that CXCR1 couples predominantly to the G protein-coupled receptor kinase (GRK)2, whereas CXCR2 interacts with GRK6 to regulate cellular responses. In addition to G protein-coupled receptors, GRKs displayed a more diverse protein/protein interaction in cells. In this study, we sought to identify GRK6 binding partner(s) that may influence CXCL8 activities, using RBL-2H3 cells stably expressing CXCR1 (RBL-CXCR1) or CXCR2 (RBL-CXCR2), as well as human and murine neutrophils. Our data demonstrated that, upon CXCR2 activation, GRK6 interacts with activator of G protein signaling (AGS)3 and Gαi2 to form a GRK6/AGS3/Gαi2 complex. This complex is time dependent and peaked at 2-3 min postactivation. GTPγS pretreatment blocked GRK6/AGS3/Gαi2 formation, suggesting that this assembly depends on G protein activation. Surprisingly, CXCR2 activation induced AGS3 phosphorylation in a PKC-dependent, but GRK6-independent, fashion. Overexpression of AGS3 in RBL-CXCR2 significantly inhibited CXCL8-induced Ca(2+) mobilization, phosphoinositide hydrolysis, and chemotaxis. In contrast, short hairpin RNA inhibition of AGS3 enhanced CXCL8-induced Ca(2+) mobilization, receptor resistance to desensitization, and recycling to the cell surface, with no effect on receptor internalization. Interestingly, RBL-CXCR2-AGS3(-/-) cells displayed a significant increase in CXCR2 expression on the cell surface but decreased ERK1/2 and P38 MAPK activation. Taken together, these results indicate that GRK6 complexes with AGS3-Gαi2 to regulate CXCR2-mediated leukocyte functions at different levels, including downstream effector activation, receptor trafficking, and expression at the cell membrane.
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Affiliation(s)
- Vandana Singh
- Department of Biology, Julius L. Chambers Biomedical/Biotechnology Research Institute, North Carolina Central University, Durham, NC 27707
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25
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Boularan C, Kamenyeva O, Cho H, Kehrl JH. Resistance to inhibitors of cholinesterase (Ric)-8A and Gαi contribute to cytokinesis abscission by controlling vacuolar protein-sorting (Vps)34 activity. PLoS One 2014; 9:e86680. [PMID: 24466196 PMCID: PMC3897744 DOI: 10.1371/journal.pone.0086680] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Accepted: 12/12/2013] [Indexed: 11/18/2022] Open
Abstract
Resistance to inhibitors of cholinesterase (Ric)-8A is a guanine nucleotide exchange factor for Gαi, Gαq, and Gα12/13, which is implicated in cell signaling and as a molecular chaperone required for the initial association of nascent Gα subunits with cellular membranes. Ric-8A, Gαi subunits, and their regulators are localized at the midbody prior to abscission and linked to the final stages of cell division. Here, we identify a molecular mechanism by which Ric-8A affects cytokinesis and abscission by controlling Vps34 activity. We showed that Ric-8A protein expression is post-transcriptionally controlled during the cell cycle reaching its maximum levels at mitosis. A FRET biosensor created to measure conformational changes in Ric-8A by FLIM (Fluorescence Lifetime Imaging Microscopy) revealed that Ric-8A was in a close-state during mitosis and particularly so at cytokinesis. Lowering Ric-8A expression delayed the abscission time of dividing cells, which correlated with increased intercellular bridge length and multinucleation. During cytokinesis, Ric-8A co-localized with Vps34 at the midbody along with Gαi and LGN, where these proteins functioned to regulate Vps34 phosphatidylinositol 3-kinase activity.
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Affiliation(s)
- Cedric Boularan
- B-cell Molecular Immunology Section, Laboratory of Immunoregulation, National Institutes of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Olena Kamenyeva
- B-cell Molecular Immunology Section, Laboratory of Immunoregulation, National Institutes of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Hyeseon Cho
- B-cell Molecular Immunology Section, Laboratory of Immunoregulation, National Institutes of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - John H. Kehrl
- B-cell Molecular Immunology Section, Laboratory of Immunoregulation, National Institutes of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
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26
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Blumer JB, Lanier SM. Activators of G protein signaling exhibit broad functionality and define a distinct core signaling triad. Mol Pharmacol 2013; 85:388-96. [PMID: 24302560 DOI: 10.1124/mol.113.090068] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Activators of G protein signaling (AGS), initially discovered in the search for receptor-independent activators of G protein signaling, define a broad panel of biologic regulators that influence signal transfer from receptor to G-protein, guanine nucleotide binding and hydrolysis, G protein subunit interactions, and/or serve as alternative binding partners for Gα and Gβγ independently of the classic heterotrimeric Gαβγ. AGS proteins generally fall into three groups based upon their interaction with and regulation of G protein subunits: group I, guanine nucleotide exchange factors (GEF); group II, guanine nucleotide dissociation inhibitors; and group III, entities that bind to Gβγ. Group I AGS proteins can engage all subclasses of G proteins, whereas group II AGS proteins primarily engage the Gi/Go/transducin family of G proteins. A fourth group of AGS proteins with selectivity for Gα16 may be defined by the Mitf-Tfe family of transcription factors. Groups I-III may act in concert, generating a core signaling triad analogous to the core triad for heterotrimeric G proteins (GEF + G proteins + effector). These two core triads may function independently of each other or actually cross-integrate for additional signal processing. AGS proteins have broad functional roles, and their discovery has advanced new concepts in signal processing, cell and tissue biology, receptor pharmacology, and system adaptation, providing unexpected platforms for therapeutic and diagnostic development.
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Affiliation(s)
- Joe B Blumer
- Department of Cell and Molecular Pharmacology and Experimental Therapeutics, Medical University of South Carolina, Charleston, South Carolina
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27
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Vural A, McQuiston TJ, Blumer JB, Park C, Hwang IY, Williams-Bey Y, Shi CS, Ma DZ, Kehrl JH. Normal autophagic activity in macrophages from mice lacking Gαi3, AGS3, or RGS19. PLoS One 2013; 8:e81886. [PMID: 24312373 PMCID: PMC3842979 DOI: 10.1371/journal.pone.0081886] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2013] [Accepted: 10/17/2013] [Indexed: 11/19/2022] Open
Abstract
In macrophages autophagy assists antigen presentation, affects cytokine release, and promotes intracellular pathogen elimination. In some cells autophagy is modulated by a signaling pathway that employs Gαi3, Activator of G-protein Signaling-3 (AGS3/GPSM1), and Regulator of G-protein Signaling 19 (RGS19). As macrophages express each of these proteins, we tested their importance in regulating macrophage autophagy. We assessed LC3 processing and the formation of LC3 puncta in bone marrow derived macrophages prepared from wild type, Gnai3(-/-), Gpsm1(-/-), or Rgs19(-/-) mice following amino acid starvation or Nigericin treatment. In addition, we evaluated rapamycin-induced autophagic proteolysis rates by long-lived protein degradation assays and anti-autophagic action after rapamycin induction in wild type, Gnai3(-/-), and Gpsm1(-/-) macrophages. In similar assays we compared macrophages treated or not with pertussis toxin, an inhibitor of GPCR (G-protein couple receptor) triggered Gαi nucleotide exchange. Despite previous findings, the level of basal autophagy, autophagic induction, autophagic flux, autophagic degradation and the anti-autophagic action in macrophages that lacked Gαi3, AGS3, or RGS19; or had been treated with pertussis toxin, were similar to controls. These results indicate that while Gαi signaling may impact autophagy in some cell types it does not in macrophages.
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Affiliation(s)
- Ali Vural
- B-Cell Molecular Immunology Section, Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Travis J. McQuiston
- Translational Mycology Unit, Laboratory of Clinical Infectious Disease, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Joe B. Blumer
- Department of Cell and Molecular Pharmacology and Experimental Therapeutics, Medical University of South Carolina, Charleston, South Carolina, United States of America
| | - Chung Park
- B-Cell Molecular Immunology Section, Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Il-Young Hwang
- B-Cell Molecular Immunology Section, Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Yolanda Williams-Bey
- B-Cell Molecular Immunology Section, Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Chong-Shan Shi
- B-Cell Molecular Immunology Section, Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Dzwokai Zach Ma
- Department of Molecular, Cellular, and Developmental Biology, University of California Santa Barbara, Santa Barbara, California, United States of America
| | - John H. Kehrl
- B-Cell Molecular Immunology Section, Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
- * E-mail:
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28
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Oner SS, Vural A, Lanier SM. Translocation of activator of G-protein signaling 3 to the Golgi apparatus in response to receptor activation and its effect on the trans-Golgi network. J Biol Chem 2013; 288:24091-103. [PMID: 23770668 DOI: 10.1074/jbc.m112.444505] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Group II activators of G-protein signaling play diverse functional roles through their interaction with Gαi, Gαt, and Gαo via a G-protein regulatory (GPR) motif that serves as a docking site for Gα-GDP. We recently reported the regulation of the AGS3-Gαi signaling module by a cell surface, seven-transmembrane receptor. Upon receptor activation, AGS3 reversibly dissociates from the cell cortex, suggesting that it may function as a signal transducer with downstream signaling implications, and this question is addressed in the current report. In HEK-293 and COS-7 cells expressing the α2A/D-AR and Gαi3, receptor activation resulted in the translocation of endogenous AGS3 and AGS3-GFP from the cell cortex to a juxtanuclear region, where it co-localized with markers of the Golgi apparatus (GA). The agonist-induced translocation of AGS3 was reversed by the α2-AR antagonist rauwolscine. The TPR domain of AGS3 was required for agonist-induced translocation of AGS3 from the cell cortex to the GA, and the translocation was blocked by pertussis toxin pretreatment or by the phospholipase Cβ inhibitor U73122. Agonist-induced translocation of AGS3 to the GA altered the functional organization and protein sorting at the trans-Golgi network. The regulated movement of AGS3 between the cell cortex and the GA offers unexpected mechanisms for modulating protein secretion and/or endosome recycling events at the trans-Golgi network.
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Affiliation(s)
- Sukru S Oner
- Department of Cell and Molecular Pharmacology and Experimental Therapeutics, Medical University of South Carolina, Charleston, South Carolina 29425, USA
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29
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Conley JM, Watts VJ. Differential effects of AGS3 expression on D(2L) dopamine receptor-mediated adenylyl cyclase signaling. Cell Mol Neurobiol 2013; 33:551-8. [PMID: 23504261 PMCID: PMC3628818 DOI: 10.1007/s10571-013-9925-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Accepted: 03/09/2013] [Indexed: 12/01/2022]
Abstract
Activator of G protein signaling 3 (AGS3) binds Gα(i) subunits in the GDP-bound state, implicating AGS3 as an important regulator of Gα(i)-linked receptor (e.g., D2 dopamine and μ-opioid) signaling. We examined the ability of AGS3 to modulate recombinant adenylyl cyclase (AC) type 1 and 2 signaling in HEK293 cells following both acute and persistent activation of the D(2L) dopamine receptor (D(2L)DR). AGS3 expression modestly enhanced the potency of acute quinpirole-induced D(2L)DR modulation of AC1 or AC2 activity. AGS3 also promoted desensitization of D(2L)DR-mediated inhibition of AC1, whereas desensitization of D(2L)DR-mediated AC2 activation was significantly attenuated. Additionally, AGS3 reduced D(2L)DR-mediated sensitization of AC1 and AC2. These data suggest that AGS3 is involved in altering G protein signaling in a complex fashion that is effector-specific and dependent on the duration of receptor activation.
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Affiliation(s)
- Jason M. Conley
- Department of Medicinal Chemistry & Molecular Pharmacology, Purdue University, West Lafayette, IN 47907, USA
| | - Val J. Watts
- Department of Medicinal Chemistry & Molecular Pharmacology, Purdue University, West Lafayette, IN 47907, USA
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30
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Group II activators of G-protein signaling: monitoring the interaction of Gα with the G-protein regulatory motif in the intact cell. Methods Enzymol 2013; 522:153-67. [PMID: 23374185 DOI: 10.1016/b978-0-12-407865-9.00009-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The G-protein regulatory (GPR) motif serves as a docking site for Gαi-GDP free of Gβγ. The GPR-Gα complex may function at the cell cortex and/or at intracellular sites. GPR proteins include the Group II Activators of G-protein signaling identified in a functional screen for receptor-independent activators of G-protein signaling (GPSM1-3, RGS12) each of which contain 1-4 GPR motifs. GPR motifs are also found in PCP2/L7(GPSM4), Rap1-Gap1 Transcript Variant 1, and RGS14. While the biochemistry of the interaction of GPR proteins with purified Gα is generally understood, the dynamics of this signaling complex and its regulation within the cell remains undefined. Major questions in the field revolve around the factors that regulate the subcellular location of GPR proteins and their interaction with Gαi and other binding partners in the cell. As an initial approach to this question, we established a platform to monitor the GPR-Gαi complex in intact cells using bioluminescence resonance energy transfer.
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