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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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2
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Vural A, Lanier SM. Intersection of two key signal integrators in the cell: activator of G-protein signaling 3 and dishevelled-2. J Cell Sci 2020; 133:jcs247908. [PMID: 32737219 PMCID: PMC7490517 DOI: 10.1242/jcs.247908] [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: 04/21/2020] [Accepted: 07/23/2020] [Indexed: 10/23/2022] Open
Abstract
Activator of G-protein signaling 3 (AGS3, encoded by GPSM1) was discovered as a one of several receptor-independent activators of G-protein signaling, which are postulated to provide a platform for divergence between canonical and noncanonical G-protein signaling pathways. Similarly, Dishevelled (DVL) proteins serve as a point of divergence for β-catenin-dependent and -independent signaling pathways involving the family of Frizzled (FZD) ligands and cell-surface WNT receptors. We recently discovered the apparent regulated localization of dishevelled-2 (DVL2) and AGS3 to distinct cellular puncta, suggesting that the two proteins interact as part of various cell signaling systems. To address this hypothesis, we asked the following questions: (1) do AGS3 signaling pathways influence the activation of β-catenin (CTNNB1)-regulated transcription through the WNT-Frizzled-Dishevelled axis, and (2) is the AGS3 and DVL2 interaction regulated? The interaction of AGS3 and DVL2 was regulated by protein phosphorylation, subcellular distribution, and a cell-surface G-protein-coupled receptor. These data, and the commonality of functional system impacts observed for AGS3 and DVL2, suggest that the AGS3-DVL2 complex presents an unexpected path for functional integration within the cell.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Ali Vural
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Stephen M Lanier
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI 48201, USA
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Vural A, Fadillioglu E, Kelesoglu F, Ma D, Lanier SM. Role of G-proteins and phosphorylation in the distribution of AGS3 to cell puncta. J Cell Sci 2018; 131:jcs.216507. [PMID: 30404823 DOI: 10.1242/jcs.216507] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Accepted: 08/02/2018] [Indexed: 12/20/2022] Open
Abstract
Activator of G-protein signaling 3 (AGS3, also known as GPSM1) exhibits broad functional diversity and oscillates among different subcellular compartments in a regulated manner. AGS3 consists of a tetratricopeptide repeat (TPR) domain and a G-protein regulatory (GPR) domain. Here, we tested the hypothesis that phosphorylation of the AGS3 GPR domain regulates its subcellular distribution and functionality. In contrast to the cortical and/or diffuse non-homogeneous distribution of wild-type (WT) AGS3, an AGS3 construct lacking all 24 potential phosphorylation sites in the GPR domain localized to cytosolic puncta. This change in localization was revealed to be dependent upon phosphorylation of a single threonine amino acid (T602). The punctate distribution of AGS3-T602A was rescued by co-expression of Gαi and Gαo but not Gαs or Gαq Following treatment with alkaline phosphatase, both AGS3-T602A and WT AGS3 exhibited a gel shift in SDS-PAGE as compared to untreated WT AGS3, consistent with a loss of protein phosphorylation. The punctate distribution of AGS3-T602A was lost in an AGS3-A602T conversion mutant, but was still present upon T602 mutation to glutamate or aspartate. These results implicate dynamic phosphorylation as a discrete mechanism to regulate the subcellular distribution of AGS3 and associated functionality.
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Affiliation(s)
- Ali Vural
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Ersin Fadillioglu
- Department of Cell and Molecular Pharmacology and Experimental Therapeutics, Medical University of South Carolina, Charleston, SC 29425, USA
| | - Fatih Kelesoglu
- Department of Cell and Molecular Pharmacology and Experimental Therapeutics, Medical University of South Carolina, Charleston, SC 29425, USA
| | - Dzwokai Ma
- Department of Molecular, Cellular, and Developmental Biology, Neuroscience Research Institute, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - Stephen M Lanier
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI 48201, USA .,Department of Cell and Molecular Pharmacology and Experimental Therapeutics, Medical University of South Carolina, Charleston, SC 29425, USA
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Robichaux WG, Branham-O'Connor M, Hwang IY, Vural A, Kehrl JH, Blumer JB. Regulation of Chemokine Signal Integration by Activator of G-Protein Signaling 4 (AGS4). J Pharmacol Exp Ther 2017; 360:424-433. [PMID: 28062526 DOI: 10.1124/jpet.116.238436] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2016] [Accepted: 12/28/2016] [Indexed: 12/15/2022] Open
Abstract
Activator of G-protein signaling 4 (AGS4)/G-protein signaling modulator 3 (Gpsm3) contains three G-protein regulatory (GPR) motifs, each of which can bind Gαi-GDP free of Gβγ We previously demonstrated that the AGS4-Gαi interaction is regulated by seven transmembrane-spanning receptors (7-TMR), which may reflect direct coupling of the GPR-Gαi module to the receptor analogous to canonical Gαβγ heterotrimer. We have demonstrated that the AGS4-Gαi complex is regulated by chemokine receptors in an agonist-dependent manner that is receptor-proximal. As an initial approach to investigate the functional role(s) of this regulated interaction in vivo, we analyzed leukocytes, in which AGS4/Gpsm3 is predominantly expressed, from AGS4/Gpsm3-null mice. Loss of AGS4/Gpsm3 resulted in mild but significant neutropenia and leukocytosis. Dendritic cells, T lymphocytes, and neutrophils from AGS4/Gpsm3-null mice also exhibited significant defects in chemoattractant-directed chemotaxis and extracellular signal-regulated kinase activation. An in vivo peritonitis model revealed a dramatic reduction in the ability of AGS4/Gpsm3-null neutrophils to migrate to primary sites of inflammation. Taken together, these data suggest that AGS4/Gpsm3 is required for proper chemokine signal processing in leukocytes and provide further evidence for the importance of the GPR-Gαi module in the regulation of leukocyte function.
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Affiliation(s)
- William G Robichaux
- Department of Cell and Molecular Pharmacology and Experimental Therapeutics, Department of Neurosciences, Medical University of South Carolina, Charleston, South Carolina (W.G.R., M.B.-O., J.B.B.); and B-Cell Molecular Immunology Section, Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland (I.-Y.H., A.V., J.H.K.)
| | - Melissa Branham-O'Connor
- Department of Cell and Molecular Pharmacology and Experimental Therapeutics, Department of Neurosciences, Medical University of South Carolina, Charleston, South Carolina (W.G.R., M.B.-O., J.B.B.); and B-Cell Molecular Immunology Section, Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland (I.-Y.H., A.V., J.H.K.)
| | - Il-Young Hwang
- Department of Cell and Molecular Pharmacology and Experimental Therapeutics, Department of Neurosciences, Medical University of South Carolina, Charleston, South Carolina (W.G.R., M.B.-O., J.B.B.); and B-Cell Molecular Immunology Section, Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland (I.-Y.H., A.V., J.H.K.)
| | - Ali Vural
- Department of Cell and Molecular Pharmacology and Experimental Therapeutics, Department of Neurosciences, Medical University of South Carolina, Charleston, South Carolina (W.G.R., M.B.-O., J.B.B.); and B-Cell Molecular Immunology Section, Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland (I.-Y.H., A.V., J.H.K.)
| | - Johne H Kehrl
- Department of Cell and Molecular Pharmacology and Experimental Therapeutics, Department of Neurosciences, Medical University of South Carolina, Charleston, South Carolina (W.G.R., M.B.-O., J.B.B.); and B-Cell Molecular Immunology Section, Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland (I.-Y.H., A.V., J.H.K.)
| | - Joe B Blumer
- Department of Cell and Molecular Pharmacology and Experimental Therapeutics, Department of Neurosciences, Medical University of South Carolina, Charleston, South Carolina (W.G.R., M.B.-O., J.B.B.); and B-Cell Molecular Immunology Section, Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland (I.-Y.H., A.V., J.H.K.)
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Brown NE, Lambert NA, Hepler JR. RGS14 regulates the lifetime of G α-GTP signaling but does not prolong G βγ signaling following receptor activation in live cells. Pharmacol Res Perspect 2016; 4:e00249. [PMID: 27713821 PMCID: PMC5045935 DOI: 10.1002/prp2.249] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Accepted: 06/28/2016] [Indexed: 12/17/2022] Open
Abstract
RGS14 is a multifunctional scaffolding protein possessing two distinct G protein interaction sites including a regulator of G protein signaling (RGS) domain that acts as a GTPase activating protein (GAP) to deactivate Gαi/o‐GTP proteins, and a G protein regulatory (GPR) motif that binds inactive Gαi1/3‐GDP proteins independent of Gβγ. GPR interactions with Gαi recruit RGS14 to the plasma membrane to interact with Gαi‐linked GPCRs and regulate Gαi signaling. While RGS14 actions on Gα proteins are well characterized, consequent effects on Gβγ signaling remain unknown. Conventional RGS proteins act as dedicated GAPs to deactivate Gα and Gβγ signaling following receptor activation. RGS14 may do the same or, alternatively, may coordinate its actions to deactivate Gα‐GTP with the RGS domain and then capture the same Gα‐GDP via its GPR motif to prevent heterotrimer reassociation and prolong Gβγ signaling. To test this idea, we compared the regulation of G protein activation and deactivation kinetics by a conventional RGS protein, RGS4, and RGS14 in response to GPCR agonist/antagonist treatment utilizing bioluminescence resonance energy transfer (BRET). Co‐expression of either RGS4 or RGS14 inhibited the release of free Gβγ after agonist stimulation and increased the deactivation rate of Gα, consistent with their roles as GTPase activating proteins (GAPs). Overexpression of inactive Gαi1 to recruit RGS14 to the plasma membrane did not alter RGS14′s capacity to act as a GAP for a second Gαo protein. These results demonstrate the role of RGS14 as a dedicated GAP and suggest that the G protein regulatory (GPR) motif functions independently of the RGS domain and is silent in regulating GAP activity in a cellular context.
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Affiliation(s)
- Nicole E Brown
- Department of Pharmacology Emory University School of Medicine Atlanta Georgia 30322
| | - Nevin A Lambert
- Department of Pharmacology and Toxicology Medical College of Georgia at Augusta University Augusta Georgia 30912
| | - John R Hepler
- Department of Pharmacology Emory University School of Medicine Atlanta Georgia 30322
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Gall BJ, Schroer AB, Gross JD, Setola V, Siderovski DP. Reduction of GPSM3 expression akin to the arthritis-protective SNP rs204989 differentially affects migration in a neutrophil model. Genes Immun 2016; 17:321-7. [PMID: 27307211 PMCID: PMC5009006 DOI: 10.1038/gene.2016.26] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Revised: 05/03/2016] [Accepted: 05/09/2016] [Indexed: 12/11/2022]
Abstract
G Protein Signaling Modulator-3 (GPSM3) is a leukocyte-specific regulator of G protein-coupled receptors (GPCRs), which binds inactivated Gαi·GDP subunits and precludes their reassociation with Gβγ subunits. GPSM3 deficiency protects mice from inflammatory arthritis and, in humans, GPSM3 single nucleotide polymorphisms (SNPs) are inversely associated with the risk of rheumatoid arthritis development; recently, these polymorphisms were linked to one particular SNP (rs204989) that decreases GPSM3 transcript abundance. However, the precise role of GPSM3 in leukocyte biology is unknown. Here we show that GPSM3 is induced in the human promyelocytic leukemia NB4 cell line following retinoic acid treatment, which differentiates this cell line into a model of neutrophil physiology (NB4*). Reducing GPSM3 expression in NB4* cells, akin to the effect ascribed to the rs204989 C>T transition, disrupts cellular migration toward leukotriene B4 (LTB4) and (to a lesser extent) interleukin-8 (a.k.a. IL-8 or CXCL8), but not migration toward formylated peptides (fMLP). As the chemoattractants LTB4 and CXCL8 are involved in recruitment of neutrophils to the arthritic joint, our results suggest that the arthritis-protective GPSM3 SNP rs204989 may act to decrease neutrophil chemoattractant responsiveness.
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Affiliation(s)
- B J Gall
- Department of Physiology and Pharmacology, West Virginia University School of Medicine, Morgantown, WV, USA
| | - A B Schroer
- Department of Physiology and Pharmacology, West Virginia University School of Medicine, Morgantown, WV, USA
| | - J D Gross
- Department of Physiology and Pharmacology, West Virginia University School of Medicine, Morgantown, WV, USA
| | - V Setola
- Department of Physiology and Pharmacology, West Virginia University School of Medicine, Morgantown, WV, USA.,Department of Behavioral Medicine and Psychiatry, West Virginia University School of Medicine, Morgantown, WV, USA
| | - D P Siderovski
- Department of Physiology and Pharmacology, West Virginia University School of Medicine, Morgantown, WV, USA
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Kehrl JH. The impact of RGS and other G-protein regulatory proteins on Gαi-mediated signaling in immunity. Biochem Pharmacol 2016; 114:40-52. [PMID: 27071343 DOI: 10.1016/j.bcp.2016.04.005] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Accepted: 04/08/2016] [Indexed: 01/30/2023]
Abstract
Leukocyte chemoattractant receptors are members of the G-protein coupled receptor (GPCR) family. Signaling downstream of these receptors directs the localization, positioning and homeostatic trafficking of leukocytes; as well as their recruitment to, and their retention at, inflammatory sites. Ligand induced changes in the molecular conformation of chemoattractant receptors results in the engagement of heterotrimeric G-proteins, which promotes α subunits to undergo GTP/GDP exchange. This results in the functional release of βγ subunits from the heterotrimers, thereby activating downstream effector molecules, which initiate leukocyte polarization, gradient sensing, and directional migration. Pertussis toxin ADP ribosylates Gαi subunits and prevents chemoattractant receptors from triggering Gαi nucleotide exchange. The use of pertussis toxin revealed the essential importance of Gαi subunit nucleotide exchange for chemoattractant receptor signaling. More recent studies have identified a range of regulatory mechanisms that target these receptors and their associated heterotrimeric G-proteins, thereby helping to control the magnitude, kinetics, and duration of signaling. A failure in these regulatory pathways can lead to impaired receptor signaling and immunopathology. The analysis of mice with targeted deletions of Gαi isoforms as well as some of these G-protein regulatory proteins is providing insights into their roles in chemoattractant receptor signaling.
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Affiliation(s)
- John H Kehrl
- Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 2089, United States.
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Abstract
Activator of G-protein signaling 3 (AGS3) is an accessory protein that functions to regulate the activation status of heterotrimeric G-protein subunits. To date, however, the downstream signaling pathways regulated by AGS3 remain to be fully elucidated, particularly in renal epithelial cells. In the present study, normal rat kidney (NRK-52E) proximal tubular epithelial cells were genetically modified to regulate the expression of AGS3 to investigate its role on MAPK and mTOR signaling to control epithelial cell number. Knockdown of endogenous AGS3 protein was associated with a reduced phosphorylated form of ERK5 and increased apoptosis as determined by elevated cleaved caspase-3. In the presence of the ERK5 inhibitor, BIX02189, a significant 2-fold change (P < 0.05) in G2/M transition state was detected compared to control conditions. Neither of the other MAPK, ERK1/2 or p38 MAPK, nor another pro-survival pathway, mTOR, was significantly altered by the changes in AGS3 protein levels in the renal epithelial cells. The selective ERK5 inhibitor, BIX02189, was found to dose-dependently reduce NRK cell number by up to 41% (P < 0.05) compared to control cells. In summary, these findings demonstrated that cell viability was regulated by AGS3 and was associated with ERK5 activation in renal epithelial cells.
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