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Thotamune W, Ubeysinghe S, Rajarathna C, Kankanamge D, Olupothage K, Chandu A, Copits BA, Karunarathne A. AGS3-based optogenetic GDI induces GPCR-independent Gβγ signaling and macrophage migration. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.04.597473. [PMID: 38895415 PMCID: PMC11185739 DOI: 10.1101/2024.06.04.597473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/21/2024]
Abstract
G protein-coupled receptors (GPCRs) are efficient Guanine nucleotide exchange factors (GEFs) and exchange GDP to GTP on the Gα subunit of G protein heterotrimers in response to various extracellular stimuli, including neurotransmitters and light. GPCRs primarily broadcast signals through activated G proteins, GαGTP, and free Gβγ, and are major disease drivers. Evidence shows that the ambient low threshold signaling required for cells is likely supplemented by signaling regulators such as non-GPCR GEFs and Guanine nucleotide Dissociation Inhibitors (GDIs). Activators of G protein Signaling 3 (AGS3) are recognized as a GDI involved in multiple health and disease-related processes. Nevertheless, understanding of AGS3 is limited, and no significant information is available on its structure-function relationship or signaling regulation in living cells. Here, we employed in silico structure-guided engineering of a novel optogenetic GDI, based on the AGS3's G protein regulatory (GPR) motif, to understand its GDI activity and induce standalone Gβγ signaling in living cells on optical command. Our results demonstrate that plasma membrane recruitment of OptoGDI efficiently releases Gβγ, and its subcellular targeting generated localized PIP3 and triggered macrophage migration. Therefore, we propose OptoGDI as a powerful tool for optically dissecting GDI-mediated signaling pathways and triggering GPCR-independent Gβγ signaling in cells and in vivo.
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Affiliation(s)
- Waruna Thotamune
- Department of Chemistry, Saint Louis University, Saint Louis, MO 63103, USA
- Institute for Drug and Biotherapeutic Innovation, Saint Louis University, Saint Louis, MO 63103, USA
| | - Sithurandi Ubeysinghe
- Department of Chemistry, Saint Louis University, Saint Louis, MO 63103, USA
- Institute for Drug and Biotherapeutic Innovation, Saint Louis University, Saint Louis, MO 63103, USA
| | - Chathuri Rajarathna
- Department of Chemistry, Saint Louis University, Saint Louis, MO 63103, USA
- Institute for Drug and Biotherapeutic Innovation, Saint Louis University, Saint Louis, MO 63103, USA
| | - Dinesh Kankanamge
- Washington University Pain Center, Department of Anesthesiology, Washington University School of Medicine; St. Louis, MO 63110 USA
| | - Koshala Olupothage
- Department of Chemistry and Biochemistry, The University of Toledo, Toledo, OH 43606, USA
| | - Aditya Chandu
- Department of Chemistry, Saint Louis University, Saint Louis, MO 63103, USA
| | - Bryan A. Copits
- Washington University Pain Center, Department of Anesthesiology, Washington University School of Medicine; St. Louis, MO 63110 USA
| | - Ajith Karunarathne
- Department of Chemistry, Saint Louis University, Saint Louis, MO 63103, USA
- Institute for Drug and Biotherapeutic Innovation, Saint Louis University, Saint Louis, MO 63103, USA
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2
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Song Y, Guo JF, Lan PS, Wang M, Du QY. Investigation of the pan-cancer property of FNDC1 and its molecular mechanism to promote lung adenocarcinoma metastasis. Transl Oncol 2024; 44:101953. [PMID: 38593585 PMCID: PMC11024379 DOI: 10.1016/j.tranon.2024.101953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Revised: 03/07/2024] [Accepted: 03/30/2024] [Indexed: 04/11/2024] Open
Abstract
BACKGROUND Fibronectin type III domain containing 1 (FNDC1) has been associated with the metastasis of many tumors, but its function in lung cancer remains uncertain. METHODS FNDC1 expression was analyzed in The Cancer Genome Atlas (TCGA) and Genotype-Tissue Expression (GTEx), evaluate its prognostic value. Gene Set Enrichment Analysis (GSEA) enrichment analysis of differential expression of FNDC1 in lung cancer. The expression of FNDC1 was detected in five types of lung cancer cells, and screened to establish FNDC1 stable knockdown cell strains. To observe the migration and invasion ability of lung cancer cells after FNDC1 knockdown. Finally, we used rhIL-6 to interfere with the stable knockdown of FNDC1 in A549 cells and observed the recovery of migration and invasion. RESULT Our results showed that FNDC1 expression was increased in 21 tumor tissues, including lung cancer, and was associated with poor prognosis in five cancers, including lung adenocarcinoma (LUAD) (P < 0.05). GSEA enrichment analysis showed that FNDC1 was related to the pathways involved the JAK-STAT signaling pathway. Stable knockdown of FNDC1 in A549 and H292 cells resulted in decreased migration and invasion ability of both cells, accompanied by decreased expression of MMP-2 and Snail, and a significant decline in the expression of p-JAK2 and p-STAT3. The suppressive effect of FNDC1 knockdown on lung cancer cell metastasis counteracted by the JAK-STAT agonist rhIL-6 were presented in the nude mouse metastatic tumor model. CONCLUSION FNDC1 is implicated in poor prognosis of a diverse range of malignant tumors, which can promote metastasis and invasion of lung cancer through the JAK2-STAT3 signaling pathway.
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Affiliation(s)
- Yang Song
- Emergency Department, Hospital of Chengdu University of Traditional Chinese Medicine, Chengdu, Sichuan 610072, PR China
| | - Jun-Feng Guo
- Endocrinology Department, Hospital of Chengdu University of Traditional Chinese Medicine, Chengdu, Sichuan 610072, PR China
| | - Pei-Shu Lan
- Endocrinology Department, Hospital of Chengdu University of Traditional Chinese Medicine, Chengdu, Sichuan 610072, PR China
| | - Miao Wang
- Endocrinology Department, Hospital of Chengdu University of Traditional Chinese Medicine, Chengdu, Sichuan 610072, PR China
| | - Quan-Yu Du
- Endocrinology Department, Hospital of Chengdu University of Traditional Chinese Medicine, Chengdu, Sichuan 610072, PR China; TCM Regulating Metabolic Diseases Key Laboratory of Sichuan Province, Chengdu, Sichuan 610072, PR China.
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3
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Kadhim DJ, Azari H, Sokhangouy SK, Hassanian SM, Alshekarchi HI, Goshayeshi L, Goshayeshi L, Abbaszadegan MR, Khojasteh-Leylakoohi F, Khazaei M, Gataa IS, Peters GJ, A. Ferns G, Batra J, Lam AKY, Giovannetti E, Avan A. G-Protein Signaling Modulator 2 as a Potential Biomarker in Colorectal Cancer: Integrative Analysis Using Genetic Profiling and Pan-Cancer Studies. Genes (Basel) 2024; 15:474. [PMID: 38674408 PMCID: PMC11050220 DOI: 10.3390/genes15040474] [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: 03/02/2024] [Revised: 04/06/2024] [Accepted: 04/06/2024] [Indexed: 04/28/2024] Open
Abstract
Colorectal cancer (CRC) imposes a significant healthcare burden globally, prompting the quest for innovative biomarkers to enhance diagnostic and therapeutic strategies. This study investigates the G-protein signaling modulator (GPSM) family across several cancers and presents a comprehensive pan-cancer analysis of the GPSM2 gene across several gastrointestinal (GI) cancers. Leveraging bioinformatics methodologies, we investigated GPSM2 expression patterns, protein interactions, functional enrichments, prognostic implications, genetic alterations, and immune infiltration associations. Furthermore, the expression of the GPSM2 gene was analyzed using real-time analysis. Our findings reveal a consistent upregulation of GPSM2 expression in all GI cancer datasets analyzed, suggesting its potential as a universal biomarker in GI cancers. Functional enrichment analysis underscores the involvement of GPSM2 in vital pathways, indicating its role in tumor progression. The prognostic assessment indicates that elevated GPSM2 expression correlates with adverse overall and disease-free survival outcomes across multiple GI cancer types. Genetic alteration analysis highlights the prevalence of mutations, particularly missense mutations, in GPSM2. Furthermore, significant correlations between GPSM2 expression and immune cell infiltration are observed, suggesting its involvement in tumor immune evasion mechanisms. Collectively, our study underscores the multifaceted role of GPSM2 in GI cancers, particularly in CRC, emphasizing its potential as a promising biomarker for prognosis and therapeutic targeting. Further functional investigations are warranted to elucidate its clinical utility and therapeutic implications in CRC management.
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Affiliation(s)
- Doaa Jawad Kadhim
- Metabolic Syndrome Research Center, Mashhad University of Medical Sciences, Mashhad 91779-48564, Iran (H.A.); (S.M.H.); (F.K.-L.); (M.K.)
| | - Hanieh Azari
- Metabolic Syndrome Research Center, Mashhad University of Medical Sciences, Mashhad 91779-48564, Iran (H.A.); (S.M.H.); (F.K.-L.); (M.K.)
| | - Saeideh Khorshid Sokhangouy
- Medical Genetics Research Center, Mashhad University of Medical Sciences, Mashhad 91886-17871, Iran; (S.K.S.); (M.R.A.)
| | - Seyed Mahdi Hassanian
- Metabolic Syndrome Research Center, Mashhad University of Medical Sciences, Mashhad 91779-48564, Iran (H.A.); (S.M.H.); (F.K.-L.); (M.K.)
| | - Hawraa Ibrahim Alshekarchi
- Al-Zahraa Center for Medical and Pharmaceutical Research Sciences (ZCMRS), Al-Zahraa University for Women, Kerbala 56001, Iraq
| | - Ladan Goshayeshi
- Department of Gastroenterology and Hepatology, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad 91779-48564, Iran;
- Surgical Oncology Research Center, Mashhad University of Medical Sciences, Mashhad 91779-48954, Iran
| | - Lena Goshayeshi
- Surgical Oncology Research Center, Mashhad University of Medical Sciences, Mashhad 91779-48954, Iran
| | - Mohammad Reza Abbaszadegan
- Medical Genetics Research Center, Mashhad University of Medical Sciences, Mashhad 91886-17871, Iran; (S.K.S.); (M.R.A.)
| | - Fatemeh Khojasteh-Leylakoohi
- Metabolic Syndrome Research Center, Mashhad University of Medical Sciences, Mashhad 91779-48564, Iran (H.A.); (S.M.H.); (F.K.-L.); (M.K.)
| | - Majid Khazaei
- Metabolic Syndrome Research Center, Mashhad University of Medical Sciences, Mashhad 91779-48564, Iran (H.A.); (S.M.H.); (F.K.-L.); (M.K.)
| | | | - Godefridus J. Peters
- Department of Biochemistry, Medical University of Gdansk, 80-211 Gdansk, Poland;
- Cancer Center Amsterdam, Cancer Biology and Immunology, Amsterdam UMC, Vrije Universiteit, Department of Medical Oncology, 1081 HV Amsterdam, The Netherlands
| | - Gordon A. Ferns
- Department of Medical Education, Brighton & Sussex Medical School, Falmer, Brighton BN1 9PH, UK;
| | - Jyotsna Batra
- Faculty of Health, School of Biomedical Sciences, Queensland University of Technology (QUT), Brisbane, QLD 4059, Australia;
| | - Alfred King-Yin Lam
- Pathology, School of Medicine and Dentistry, Gold Coast Campus, Griffith University, Gold Coast, QLD 4222, Australia;
| | - Elisa Giovannetti
- Cancer Center Amsterdam, Cancer Biology and Immunology, Amsterdam UMC, Vrije Universiteit, Department of Medical Oncology, 1081 HV Amsterdam, The Netherlands
- Cancer Pharmacology Laboratory, AIRC Start Up Unit, Fondazione Pisana per La Scienza, 56017 Pisa, Italy
| | - Amir Avan
- Metabolic Syndrome Research Center, Mashhad University of Medical Sciences, Mashhad 91779-48564, Iran (H.A.); (S.M.H.); (F.K.-L.); (M.K.)
- Faculty of Health, School of Biomedical Sciences, Queensland University of Technology (QUT), Brisbane, QLD 4059, Australia;
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4
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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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5
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Vural A, Lanier SM. Properties of biomolecular condensates defined by Activator of G-protein Signaling 3. J Cell Sci 2024; 137:jcs261326. [PMID: 38264908 PMCID: PMC10911133 DOI: 10.1242/jcs.261326] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Accepted: 01/11/2024] [Indexed: 01/25/2024] Open
Abstract
Activator of G-protein signaling 3 (AGS3; also known as GPSM1), a receptor-independent activator of G-protein signaling, oscillates among defined subcellular compartments and biomolecular condensates (BMCs) in a regulated manner that is likely related to the functional diversity of the protein. We determined the influence of cell stress on the cellular distribution of AGS3 and core material properties of AGS3 BMCs. Cellular stress (oxidative, pHi and thermal) induced the formation of AGS3 BMCs in HeLa and COS-7 cells, as determined by fluorescent microscopy. Oxidative stress-induced AGS3 BMCs were distinct from G3BP1 stress granules and from RNA processing BMCs defined by the P-body protein Dcp1a. Immunoblots indicated that cellular stress shifted AGS3, but not the stress granule protein G3BP1 to a membrane pellet fraction following cell lysis. The stress-induced generation of AGS3 BMCs was reduced by co-expression of the signaling protein Gαi3, but not the AGS3-binding partner DVL2. Fluorescent recovery following photobleaching of individual AGS3 BMCs indicated that there are distinct diffusion kinetics and restricted fluidity for AGS3 BMCs. These data suggest that AGS3 BMCs represent a distinct class of stress granules that serve as a previously unrecognized signal processing node.
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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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6
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Rajanala K, Wedegaertner PB. Gβγ signaling regulates microtubule-dependent control of Golgi integrity. Cell Signal 2023; 106:110630. [PMID: 36805843 PMCID: PMC10079639 DOI: 10.1016/j.cellsig.2023.110630] [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: 12/29/2022] [Revised: 02/09/2023] [Accepted: 02/13/2023] [Indexed: 02/18/2023]
Abstract
Gβγ subunits regulate several non-canonical functions at distinct intracellular organelles. Previous studies have shown that Gβγ signaling at the Golgi is necessary to mediate vesicular protein transport function and to regulate mitotic Golgi fragmentation. Disruption of Golgi structure also occurs in response to microtubule depolymerizing agents, such as nocodazole. In this study, we use siRNA against Gβ1/2 or specific Gγ subunits to deplete their expression, and show that their knockdown causes a significant reduction in nocodazole-induced Golgi fragmentation. We establish that knockdown of Gβγ or inhibition of Gβγ with gallein resulted in decreased activation of protein kinase D (PKD) in response to nocodazole treatment. We demonstrate that restricting the amount of free Gβγ available for signaling by either inhibiting Gαi activation using pertussis toxin or by knockdown of the non-GPCR GEF, Girdin/GIV protein, results in a substantial decrease in nocodazole-induced Golgi fragmentation and PKD phosphorylation. Our results also indicate that depletion of Gβγ or inhibition with gallein or pertussis toxin significantly reduces the microtubule disruption-dependent Golgi fragmentation phenotype observed in cells transfected with mutant SOD1, a major causative protein in familial amyotrophic lateral sclerosis (ALS). These results provide compelling evidence that Gβγ signaling is critical for the regulation of Golgi integrity.
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Affiliation(s)
- Kalpana Rajanala
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Sidney Kimmel Medical College, Philadelphia, PA 19107, United States of America
| | - Philip B Wedegaertner
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Sidney Kimmel Medical College, Philadelphia, PA 19107, United States of America.
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7
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Endomembrane-Based Signaling by GPCRs and G-Proteins. Cells 2022; 11:cells11030528. [PMID: 35159337 PMCID: PMC8834376 DOI: 10.3390/cells11030528] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2021] [Revised: 01/26/2022] [Accepted: 01/28/2022] [Indexed: 12/14/2022] Open
Abstract
G-protein-coupled receptors (GPCRs) and G-proteins have a range of roles in many physiological and pathological processes and are among the most studied signaling proteins. A plethora of extracellular stimuli can activate the GPCR and can elicit distinct intracellular responses through the activation of specific transduction pathways. For many years, biologists thought that GPCR signaling occurred entirely on the plasma membrane. However, in recent decades, many lines of evidence have proved that the GPCRs and G-proteins may reside on endomembranes and can start or propagate signaling pathways through the organelles that form the secretory route. How these alternative intracellular signaling pathways of the GPCR and G-proteins influence the physiological and pathological function of the endomembranes is still under investigation. Here, we review the general role and classification of GPCRs and G-proteins with a focus on their signaling pathways in the membrane transport apparatus.
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8
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Nubbemeyer B, Pepanian A, Paul George AA, Imhof D. Strategies towards Targeting Gαi/s Proteins: Scanning of Protein-Protein Interaction Sites To Overcome Inaccessibility. ChemMedChem 2021; 16:1696-1715. [PMID: 33615736 PMCID: PMC8252600 DOI: 10.1002/cmdc.202100039] [Citation(s) in RCA: 9] [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: 01/15/2021] [Indexed: 12/16/2022]
Abstract
Heterotrimeric G proteins are classified into four subfamilies and play a key role in signal transduction. They transmit extracellular signals to intracellular effectors subsequent to the activation of G protein-coupled receptors (GPCRs), which are targeted by over 30 % of FDA-approved drugs. However, addressing G proteins as drug targets represents a compelling alternative, for example, when G proteins act independently of the corresponding GPCRs, or in cases of complex multifunctional diseases, when a large number of different GPCRs are involved. In contrast to Gαq, efforts to target Gαi/s by suitable chemical compounds has not been successful so far. Here, a comprehensive analysis was conducted examining the most important interface regions of Gαi/s with its upstream and downstream interaction partners. By assigning the existing compounds and the performed approaches to the respective interfaces, the druggability of the individual interfaces was ranked to provide perspectives for selective targeting of Gαi/s in the future.
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Affiliation(s)
- Britta Nubbemeyer
- Pharmaceutical Biochemistry and BioanalyticsPharmaceutical InstituteUniversity of BonnAn der Immenburg 453121BonnGermany
| | - Anna Pepanian
- Pharmaceutical Biochemistry and BioanalyticsPharmaceutical InstituteUniversity of BonnAn der Immenburg 453121BonnGermany
| | | | - Diana Imhof
- Pharmaceutical Biochemistry and BioanalyticsPharmaceutical InstituteUniversity of BonnAn der Immenburg 453121BonnGermany
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9
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Akhshi T, Trimble WS. A non-canonical Hedgehog pathway initiates ciliogenesis and autophagy. J Cell Biol 2021; 220:211568. [PMID: 33258871 PMCID: PMC7714386 DOI: 10.1083/jcb.202004179] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 08/19/2020] [Accepted: 10/14/2020] [Indexed: 12/17/2022] Open
Abstract
Primary cilia function as critical signaling hubs whose absence leads to severe disorders collectively known as ciliopathies; our knowledge of ciliogenesis remains limited. We show that Smo induces ciliogenesis through two distinct yet essential noncanonical Hh pathways in several cell types, including neurons. Surprisingly, ligand activation of Smo induces autophagy via an LKB1-AMPK axis to remove the satellite pool of OFD1. This is required, but not sufficient, for ciliogenesis. Additionally, Smo activates the Gαi-LGN-NuMA-dynein axis, causing accumulation of a portion of OFD1 at centrioles in early ciliogenesis. Both pathways are critical for redistribution of BBS4 from satellites to centrioles, which is also mediated by OFD1 centriolar translocation. Notably, different Smo agonists, which activate Smo distinctly, activate one or the other of these pathways; only in combination they recapitulate the activity of Hh ligand. These studies provide new insight into physiological stimuli (Hh) that activate autophagy and promote ciliogenesis and introduce a novel role for the Gαi-LGN-NuMA-dynein complex in this process.
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Affiliation(s)
- Tara Akhshi
- Cell Biology Program, Hospital for Sick Children, Toronto, Canada.,Department of Biochemistry, University of Toronto, Toronto, Canada
| | - William S Trimble
- Cell Biology Program, Hospital for Sick Children, Toronto, Canada.,Department of Biochemistry, University of Toronto, Toronto, Canada
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10
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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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11
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Calebiro D, Koszegi Z, Lanoiselée Y, Miljus T, O'Brien S. G protein-coupled receptor-G protein interactions: a single-molecule perspective. Physiol Rev 2020; 101:857-906. [PMID: 33331229 DOI: 10.1152/physrev.00021.2020] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
G protein-coupled receptors (GPCRs) regulate many cellular and physiological processes, responding to a diverse range of extracellular stimuli including hormones, neurotransmitters, odorants, and light. Decades of biochemical and pharmacological studies have provided fundamental insights into the mechanisms of GPCR signaling. Thanks to recent advances in structural biology, we now possess an atomistic understanding of receptor activation and G protein coupling. However, how GPCRs and G proteins interact in living cells to confer signaling efficiency and specificity remains insufficiently understood. The development of advanced optical methods, including single-molecule microscopy, has provided the means to study receptors and G proteins in living cells with unprecedented spatio-temporal resolution. The results of these studies reveal an unexpected level of complexity, whereby GPCRs undergo transient interactions among themselves as well as with G proteins and structural elements of the plasma membrane to form short-lived signaling nanodomains that likely confer both rapidity and specificity to GPCR signaling. These findings may provide new strategies to pharmaceutically modulate GPCR function, which might eventually pave the way to innovative drugs for common diseases such as diabetes or heart failure.
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Affiliation(s)
- Davide Calebiro
- Institute of Metabolism and Systems Research, University of Birmingham, Birmingham, United Kingdom; Centre of Membrane Proteins and Receptors (COMPARE), Universities of Nottingham and Birmingham, Birmingham, United Kingdom
| | - Zsombor Koszegi
- Institute of Metabolism and Systems Research, University of Birmingham, Birmingham, United Kingdom; Centre of Membrane Proteins and Receptors (COMPARE), Universities of Nottingham and Birmingham, Birmingham, United Kingdom
| | - Yann Lanoiselée
- Institute of Metabolism and Systems Research, University of Birmingham, Birmingham, United Kingdom; Centre of Membrane Proteins and Receptors (COMPARE), Universities of Nottingham and Birmingham, Birmingham, United Kingdom
| | - Tamara Miljus
- Institute of Metabolism and Systems Research, University of Birmingham, Birmingham, United Kingdom; Centre of Membrane Proteins and Receptors (COMPARE), Universities of Nottingham and Birmingham, Birmingham, United Kingdom
| | - Shannon O'Brien
- Institute of Metabolism and Systems Research, University of Birmingham, Birmingham, United Kingdom; Centre of Membrane Proteins and Receptors (COMPARE), Universities of Nottingham and Birmingham, Birmingham, United Kingdom
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12
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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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13
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Cai X, Fu H, Wang Y, Liu Q, Wang X. Depletion of GPSM1 enhances ovarian granulosa cell apoptosis via cAMP-PKA-CREB pathway in vitro. J Ovarian Res 2020; 13:136. [PMID: 33220708 PMCID: PMC7680585 DOI: 10.1186/s13048-020-00740-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Accepted: 11/12/2020] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND Genetic causes of premature ovarian insufficiency (POI) account for approximately 20 ~ 25% of patients. So far, only a few genes have been identified. RESULTS Here, we first identified the c.1840C > A on G-protein signaling modulator 1 (GPSM1) as a susceptibility locus for POI in 10 sporadic POI patients by whole-exome sequencing. The frequency of GPSM1 c.1840C > A was then verified as 3/20 in a POI sample of 20 patients (including the above 10 patients) by Sanger sequencing. RT-PCR and western blot analysis showed the expression of GPSM1 in rat ovaries was increased in the large antral follicle stage compared to the primordial follicle stage (P < 0.01). The cell proliferation assay (CCK8) and flow cytometry suggested that the small-interfering RNA-induced silencing of Gpsm1 significantly increased apoptosis and decreased proliferation of rat ovarian granulosa cells (GCs) (P < 0.01). Furthermore, suppression of Gpsm1 in GCs reduced levels of cAMP, PKAc, p-CREB as well as the ratio of Bcl-2/Bax, and increased the expression of Caspase-3 and Cleaved Caspase-3 (P < 0.01). CONCLUSIONS In summary, this study identified a susceptibility variant GPSM1 c.1840C > A of POI for the first time. Gpsm1 was related to rat follicle development, and silencing of Gpsm1 increased apoptosis and decreased proliferation in rat GCs, possibly through inhibition of the cAMP-PKA-CREB pathway.
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Affiliation(s)
- Xuzi Cai
- Department of Obstetrics and Gynecology, The Third Affiliated Hospital of Southern Medical University, No. 183 West Zhongshan Avenue, Guangzhou, 510000, Guangdong, China
| | - Huijiao Fu
- Department of Obstetrics and Gynecology, The Third Affiliated Hospital of Southern Medical University, No. 183 West Zhongshan Avenue, Guangzhou, 510000, Guangdong, China
| | - Yan Wang
- Department of Obstetrics and Gynecology, The Third Affiliated Hospital of Southern Medical University, No. 183 West Zhongshan Avenue, Guangzhou, 510000, Guangdong, China
| | - Qiwen Liu
- Department of Obstetrics and Gynecology, The Third Affiliated Hospital of Southern Medical University, No. 183 West Zhongshan Avenue, Guangzhou, 510000, Guangdong, China
| | - Xuefeng Wang
- Department of Obstetrics and Gynecology, The Third Affiliated Hospital of Southern Medical University, No. 183 West Zhongshan Avenue, Guangzhou, 510000, Guangdong, China.
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14
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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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15
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Modzelewska K, Brown L, Culotti J, Moghal N. Sensory regulated Wnt production from neurons helps make organ development robust to environmental changes in C. elegans. Development 2020; 147:dev186080. [PMID: 32586974 DOI: 10.1242/dev.186080] [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: 11/03/2019] [Accepted: 06/13/2020] [Indexed: 11/20/2022]
Abstract
Long-term survival of an animal species depends on development being robust to environmental variations and climate changes. We used C. elegans to study how mechanisms that sense environmental changes trigger adaptive responses that ensure animals develop properly. In water, the nervous system induces an adaptive response that reinforces vulval development through an unknown backup signal for vulval induction. This response involves the heterotrimeric G-protein EGL-30//Gαq acting in motor neurons. It also requires body-wall muscle, which is excited by EGL-30-stimulated synaptic transmission, suggesting a behavioral function of neurons induces backup signal production from muscle. We now report that increased acetylcholine during liquid growth activates an EGL-30-Rho pathway, distinct from the synaptic transmission pathway, that increases Wnt production from motor neurons. We also provide evidence that this neuronal Wnt contributes to EGL-30-stimulated vulval development, with muscle producing a parallel developmental signal. As diverse sensory modalities stimulate motor neurons via acetylcholine, this mechanism enables broad sensory perception to enhance Wnt-dependent development. Thus, sensory perception improves animal fitness by activating distinct neuronal functions that trigger adaptive changes in both behavior and developmental processes.
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Affiliation(s)
- Katarzyna Modzelewska
- Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah, Salt Lake City, UT 84112, USA
| | - Louise Brown
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, M5G 1X5, Canada
| | - Joseph Culotti
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, M5G 1X5, Canada
| | - Nadeem Moghal
- Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah, Salt Lake City, UT 84112, USA
- Princess Margaret Cancer Centre/University Health Network, Toronto, Ontario, M5G 1L7, Canada
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16
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Wavreil FDM, Yajima M. Diversity of activator of G-protein signaling (AGS)-family proteins and their impact on asymmetric cell division across taxa. Dev Biol 2020; 465:89-99. [PMID: 32687894 DOI: 10.1016/j.ydbio.2020.07.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Revised: 07/05/2020] [Accepted: 07/06/2020] [Indexed: 11/18/2022]
Abstract
Asymmetric cell division (ACD) is a cellular process that forms two different cell types through a cell division and is thus critical for the development of all multicellular organisms. Not all but many of the ACD processes are mediated by proper orientation of the mitotic spindle, which segregates the fate determinants asymmetrically into daughter cells. In many cell types, the evolutionarily conserved protein complex of Gαi/AGS-family protein/NuMA-like protein appears to play critical roles in orienting the spindle and/or generating the polarized cortical forces to regulate ACD. Studies in various organisms reveal that this conserved protein complex is slightly modified in each phylum or even within species. In particular, AGS-family proteins appear to be modified with a variable number of motifs in their functional domains across taxa. This apparently creates different molecular interactions and mechanisms of ACD in each developmental program, ultimately contributing to developmental diversity across species. In this review, we discuss how a conserved ACD machinery has been modified in each phylum over the course of evolution with a major focus on the molecular evolution of AGS-family proteins and its impact on ACD regulation.
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Affiliation(s)
- Florence D M Wavreil
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, RI, 02906, USA
| | - Mamiko Yajima
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, RI, 02906, USA.
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17
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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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18
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Abstract
Glucose-induced (physiological) insulin secretion from the islet β-cell involves interplay between cationic (i.e., changes in intracellular calcium) and metabolic (i.e., generation of hydrophobic and hydrophilic second messengers) events. A large body of evidence affirms support for novel regulation, by G proteins, of specific intracellular signaling events, including actin cytoskeletal remodeling, transport of insulin-containing granules to the plasma membrane for fusion, and secretion of insulin into the circulation. This article highlights the following aspects of GPCR-G protein biology of the islet. First, it overviews our current understanding of the identity of a wide variety of G protein regulators and their modulatory roles in GPCR-G protein-effector coupling, which is requisite for optimal β-cell function under physiological conditions. Second, it describes evidence in support of novel, noncanonical, GPCR-independent mechanisms of activation of G proteins in the islet. Third, it highlights the evidence indicating that abnormalities in G protein function lead to islet β-cell dysregulation and demise under the duress of metabolic stress and diabetes. Fourth, it summarizes observations of potential beneficial effects of GPCR agonists in preventing/halting metabolic defects in the islet β-cell under various pathological conditions (e.g., metabolic stress and inflammation). Lastly, it identifies knowledge gaps and potential avenues for future research in this evolving field of translational islet biology. Published 2020. Compr Physiol 10:453-490, 2020.
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Affiliation(s)
- Anjaneyulu Kowluru
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Center for Translational Research in Diabetes, Biomedical Research Service, John D. Dingell VA Medical Center, Wayne State University, Detroit, Michigan, USA
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19
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Srivastava D, Artemyev NO. Ric-8A, a GEF, and a Chaperone for G Protein α-Subunits: Evidence for the Two-Faced Interface. Bioessays 2020; 42:e1900208. [PMID: 31967346 PMCID: PMC7034654 DOI: 10.1002/bies.201900208] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Revised: 12/30/2019] [Indexed: 12/21/2022]
Abstract
Resistance to inhibitors of cholinesterase 8A (Ric-8A) is a prominent non-receptor GEF and a chaperone of G protein α-subunits (Gα). Recent studies shed light on the structure of Ric-8A, providing insights into the mechanisms underlying its interaction with Gα. Ric-8A is composed of a core armadillo-like domain and a flexible C-terminal tail. Interaction of a conserved concave surface of its core domain with the Gα C-terminus appears to mediate formation of the initial Ric-8A/GαGDP intermediate, followed by the formation of a stable nucleotide-free complex. The latter event involves a large-scale dislocation of the Gα α5-helix that produces an extensive primary interface and disrupts the nucleotide-binding site of Gα. The distal portion of the C-terminal tail of Ric-8A forms a smaller secondary interface, which ostensibly binds the switch II region of Gα, facilitating binding of GTP. The two-site Gα interface of Ric-8A is distinct from that of GPCRs, and might have evolved to support the chaperone function of Ric-8A.
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Affiliation(s)
- Dhiraj Srivastava
- Department of Molecular Physiology and Biophysics, The University of Iowa Carver College of Medicine, Iowa City, IA 52242
| | - Nikolai O. Artemyev
- Department of Molecular Physiology and Biophysics, The University of Iowa Carver College of Medicine, Iowa City, IA 52242
- Department of Ophthalmology and Visual Sciences, The University of Iowa Carver College of Medicine, Iowa City, IA 52242
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20
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Tutunea-Fatan E, Lee JC, Denker BM, Gunaratnam L. Heterotrimeric Gα 12/13 proteins in kidney injury and disease. Am J Physiol Renal Physiol 2020; 318:F660-F672. [PMID: 31984793 DOI: 10.1152/ajprenal.00453.2019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Gα12 and Gα13 are ubiquitous members of the heterotrimeric guanine nucleotide-binding protein (G protein) family that play central and integrative roles in the regulation of signal transduction cascades within various cell types in the kidney. Gα12/Gα13 proteins enable the kidney to adapt to an ever-changing environment by transducing stimuli from cell surface receptors and accessory proteins to effector systems. Therefore, perturbations in Gα12/Gα13 levels or their activity can contribute to the pathogenesis of various renal diseases, including renal cancer. This review will highlight and discuss the complex and expanding roles of Gα12/Gα13 proteins on distinct renal pathologies, with emphasis on more recently reported findings. Deciphering how the different Gα12/Gα13 interaction networks participate in the onset and development of renal diseases may lead to the discovery of new therapeutic strategies.
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Affiliation(s)
- Elena Tutunea-Fatan
- Matthew Mailing Centre for Translational Transplant Studies, Lawson Health Research Institute, London, Ontario, Canada
| | - Jasper C Lee
- Department of Microbiology and Immunology, University of Western Ontario, London, Ontario, Canada
| | - Bradley M Denker
- Beth Israel Deaconess Medical Center and Department of Medicine, Harvard Medical School, Boston, Massachusetts
| | - Lakshman Gunaratnam
- Matthew Mailing Centre for Translational Transplant Studies, Lawson Health Research Institute, London, Ontario, Canada.,Department of Microbiology and Immunology, University of Western Ontario, London, Ontario, Canada.,Division of Nephrology, Department of Medicine, University of Western Ontario, London, Ontario, Canada
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21
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Marivin A, Maziarz M, Zhao J, DiGiacomo V, Olmos Calvo I, Mann EA, Ear J, Blanco-Canosa JB, Ross EM, Ghosh P, Garcia-Marcos M. DAPLE protein inhibits nucleotide exchange on Gα s and Gα q via the same motif that activates Gαi. J Biol Chem 2020; 295:2270-2284. [PMID: 31949046 DOI: 10.1074/jbc.ra119.011648] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Revised: 01/08/2020] [Indexed: 01/03/2023] Open
Abstract
Besides being regulated by G-protein-coupled receptors, the activity of heterotrimeric G proteins is modulated by many cytoplasmic proteins. GIV/Girdin and DAPLE (Dvl-associating protein with a high frequency of leucine) are the best-characterized members of a group of cytoplasmic regulators that contain a Gα-binding and -activating (GBA) motif and whose dysregulation underlies human diseases, including cancer and birth defects. GBA motif-containing proteins were originally reported to modulate G proteins by binding Gα subunits of the Gi/o family (Gαi) over other families (such as Gs, Gq/11, or G12/13), and promoting nucleotide exchange in vitro However, some evidence suggests that this is not always the case, as phosphorylation of the GBA motif of GIV promotes its binding to Gαs and inhibits nucleotide exchange. The G-protein specificity of DAPLE and how it might affect nucleotide exchange on G proteins besides Gαi remain to be investigated. Here, we show that DAPLE's GBA motif, in addition to Gαi, binds efficiently to members of the Gs and Gq/11 families (Gαs and Gαq, respectively), but not of the G12/13 family (Gα12) in the absence of post-translational phosphorylation. We pinpointed Met-1669 as the residue in the GBA motif of DAPLE that diverges from that in GIV and enables better binding to Gαs and Gαq Unlike the nucleotide-exchange acceleration observed for Gαi, DAPLE inhibited nucleotide exchange on Gαs and Gαq These findings indicate that GBA motifs have versatility in their G-protein-modulating effect, i.e. they can bind to Gα subunits of different classes and either stimulate or inhibit nucleotide exchange depending on the G-protein subtype.
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Affiliation(s)
- Arthur Marivin
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118
| | - Marcin Maziarz
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118
| | - Jingyi Zhao
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118
| | - Vincent DiGiacomo
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118
| | - Isabel Olmos Calvo
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118
| | - Emily A Mann
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118
| | - Jason Ear
- Department of Medicine and Cellular and Molecular Medicine, University of California, San Diego, California 92093
| | - Juan B Blanco-Canosa
- Department of Biological Chemistry, Institute for Advanced Chemistry of Catalonia (IQAC-CSIC), Barcelona, Spain 08034
| | - Elliott M Ross
- Department of Pharmacology, Green Center for Systems Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Pradipta Ghosh
- Department of Medicine and Cellular and Molecular Medicine, University of California, San Diego, California 92093
| | - Mikel Garcia-Marcos
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118.
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22
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Subramanian A, Capalbo A, Iyengar NR, Rizzo R, di Campli A, Di Martino R, Lo Monte M, Beccari AR, Yerudkar A, Del Vecchio C, Glielmo L, Turacchio G, Pirozzi M, Kim SG, Henklein P, Cancino J, Parashuraman S, Diviani D, Fanelli F, Sallese M, Luini A. Auto-regulation of Secretory Flux by Sensing and Responding to the Folded Cargo Protein Load in the Endoplasmic Reticulum. Cell 2020; 176:1461-1476.e23. [PMID: 30849374 DOI: 10.1016/j.cell.2019.01.035] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 08/30/2018] [Accepted: 01/23/2019] [Indexed: 11/19/2022]
Abstract
Maintaining the optimal performance of cell processes and organelles is the task of auto-regulatory systems. Here we describe an auto-regulatory device that helps to maintain homeostasis of the endoplasmic reticulum (ER) by adjusting the secretory flux to the cargo load. The cargo-recruiting subunit of the coatomer protein II (COPII) coat, Sec24, doubles as a sensor of folded cargo and, upon cargo binding, acts as a guanine nucleotide exchange factor to activate the signaling protein Gα12 at the ER exit sites (ERESs). This step, in turn, activates a complex signaling network that activates and coordinates the ER export machinery and attenuates proteins synthesis, thus preventing large fluctuations of folded and potentially active cargo that could be harmful to the cell or the organism. We call this mechanism AREX (autoregulation of ER export) and expect that its identification will aid our understanding of human physiology and diseases that develop from secretory dysfunction.
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Affiliation(s)
- Advait Subramanian
- Institute of Protein Biochemistry (IBP), Italian National Research Council (CNR), Napoli, Italy.
| | - Anita Capalbo
- Institute of Protein Biochemistry (IBP), Italian National Research Council (CNR), Napoli, Italy
| | - Namrata Ravi Iyengar
- Institute of Protein Biochemistry (IBP), Italian National Research Council (CNR), Napoli, Italy
| | - Riccardo Rizzo
- Institute of Protein Biochemistry (IBP), Italian National Research Council (CNR), Napoli, Italy
| | - Antonella di Campli
- Institute of Protein Biochemistry (IBP), Italian National Research Council (CNR), Napoli, Italy; Department of Medical, Oral and Biotechnological Sciences and CeSI-MeT, Center for Research on Ageing and Translational Medicine, "G. d'Annunzio" University of Chieti-Pescara, Chieti, Italy
| | - Rosaria Di Martino
- Institute of Protein Biochemistry (IBP), Italian National Research Council (CNR), Napoli, Italy
| | - Matteo Lo Monte
- Institute of Protein Biochemistry (IBP), Italian National Research Council (CNR), Napoli, Italy
| | - Andrea R Beccari
- Institute of Protein Biochemistry (IBP), Italian National Research Council (CNR), Napoli, Italy; Dompé Farmaceutici SpA, Milan, Italy
| | - Amol Yerudkar
- Department of Engineering, Universitá degli Studi del Sannio, Benevento, Italy
| | - Carmen Del Vecchio
- Department of Engineering, Universitá degli Studi del Sannio, Benevento, Italy
| | - Luigi Glielmo
- Department of Engineering, Universitá degli Studi del Sannio, Benevento, Italy
| | - Gabriele Turacchio
- Institute of Protein Biochemistry (IBP), Italian National Research Council (CNR), Napoli, Italy
| | - Marinella Pirozzi
- Institute of Protein Biochemistry (IBP), Italian National Research Council (CNR), Napoli, Italy
| | - Sang Geon Kim
- College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul, South Korea
| | - Petra Henklein
- Institut fur Biochemie, Charite Universitätsmedizin, Berlin, Germany
| | - Jorge Cancino
- Centro de Biología Celular y Biomedicina (CEBICEM), Facultad de Medicina y Ciencia, Universidad San Sebastián, Lota 2465, Santiago 7510157, Chile
| | | | - Dario Diviani
- Université de Lausanne, Département de Pharmacologie et Toxicologie, Rue du Bugnon 27, 1011 Lausanne, Switzerland
| | - Francesca Fanelli
- Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Michele Sallese
- Department of Medical, Oral and Biotechnological Sciences and CeSI-MeT, Center for Research on Ageing and Translational Medicine, "G. d'Annunzio" University of Chieti-Pescara, Chieti, Italy
| | - Alberto Luini
- Institute of Protein Biochemistry (IBP), Italian National Research Council (CNR), Napoli, Italy.
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23
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Srivastava D, Artemyev NO. Large-scale conformational rearrangement of the α5-helix of Gα subunits in complex with the guanine nucleotide exchange factor Ric8A. J Biol Chem 2019; 294:17875-17882. [PMID: 31624147 DOI: 10.1074/jbc.ac119.011135] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Revised: 10/02/2019] [Indexed: 11/06/2022] Open
Abstract
Resistance to inhibitors of cholinesterase 8A (Ric8A) protein is an important G protein-coupled receptor (GPCR)-independent regulator of G protein α-subunits (Gα), acting as a guanine nucleotide exchange factor (GEF) and a chaperone. Insights into the complex between Ric8A and Gα hold the key to understanding the mechanisms underlying noncanonical activation of G-protein signaling as well as the folding of nascent Gα proteins. Here, we examined the structure of the complex of Ric8A with minimized Gαi (miniGαi) in solution by small-angle X-ray scattering (SAXS) and exploited the scattering profile in modeling of the Ric8A/miniGαi complex by steered molecular dynamics (SMD) simulations. A small set of models of the complex featured minimal clash scores, excellent agreement with the experimental SAXS data, and a large-scale rearrangement of the signal-transducing α5-helix of Gα away from its β-sheet core. The resulting interface involved the Gα α5-helix bound to the concave surface of Ric8A and the Gα β-sheet that wraps around the C-terminal part of the Ric8A armadillo domain, leading to a severe disruption of the GDP-binding site. Further modeling of the flexible C-terminal tail of Ric8A indicated that it interacts with the effector surface of Gα. This smaller interface may enable the Ric8A-bound Gα to interact with GTP. The two-interface interaction with Gα described here distinguishes Ric8A from GPCRs and non-GPCR regulators of G-protein signaling.
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Affiliation(s)
- Dhiraj Srivastava
- Department of Molecular Physiology and Biophysics, University of Iowa Carver College of Medicine, Iowa City, Iowa 52242
| | - Nikolai O Artemyev
- Department of Molecular Physiology and Biophysics, University of Iowa Carver College of Medicine, Iowa City, Iowa 52242 .,Department of Ophthalmology and Visual Sciences, University of Iowa Carver College of Medicine, Iowa City, Iowa 52242
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Hajj M, De Vita T, Vol C, Renassia C, Bologna JC, Brabet I, Cazade M, Pastore M, Blahos J, Labesse G, Pin JP, Prézeau L. Nonclassical Ligand-Independent Regulation of Go Protein by an Orphan Class C G-Protein–Coupled Receptor. Mol Pharmacol 2019; 96:233-246. [DOI: 10.1124/mol.118.113019] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Accepted: 05/28/2019] [Indexed: 01/20/2023] Open
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Zeng B, Mou TC, Doukov TI, Steiner A, Yu W, Papasergi-Scott M, Tall GG, Hagn F, Sprang SR. Structure, Function, and Dynamics of the Gα Binding Domain of Ric-8A. Structure 2019; 27:1137-1147.e5. [PMID: 31155309 DOI: 10.1016/j.str.2019.04.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Revised: 04/01/2019] [Accepted: 04/23/2019] [Indexed: 10/26/2022]
Abstract
Ric-8A is a 530-amino acid cytoplasmic molecular chaperone and guanine nucleotide exchange factor (GEF) for i, q, and 12/13 classes of heterortrimeric G protein alpha subunits (Gα). We report the 2.2-Å crystal structure of the Ric-8A Gα-binding domain with GEF activity, residues 1-452, and is phosphorylated at Ser435 and Thr440. Residues 1-429 adopt a superhelical fold comprised of Armadillo (ARM) and HEAT repeats, and the C terminus is disordered. One of the phosphorylated residues potentially binds to a basic cluster in an ARM motif. Amino acid sequence conservation and published hydrogen-deuterium exchange data indicate repeats 3 through 6 to be a putative Gα-binding surface. Normal mode modeling of small-angle X-ray scattering data indicates that phosphorylation induces relative rotation between repeats 1-4, 5-6, and 7-9. 2D 1H-15N-TROSY spectra of [2H,15N]-labeled Gαi1 in the presence of R452 reveals chemical shift perturbations of the C terminus and Gαi1 residues involved in nucleotide binding.
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Affiliation(s)
- Baisen Zeng
- Graduate Program in Biochemistry and Biophysics, University of Montana, Missoula, MT 59812, 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
| | - Tzanko I Doukov
- Macromolecular Crystallography Group, Stanford Synchrotron Radiation Light Source, SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94309, USA
| | - Andrea Steiner
- Bavarian NMR Center at the Department of Chemistry and Institute for Advanced Study, Technical University of Munich, Ernst-Otto-Fischer-Strasse 2, 85748 Garching, Germany; Institute of Structural Biology, Helmholtz Zentrum München, Ingolstädter Landstrasse 1, 85764 Neuherberg, Germany
| | - Wenxi Yu
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Makaia Papasergi-Scott
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Gregory G Tall
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Franz Hagn
- Bavarian NMR Center at the Department of Chemistry and Institute for Advanced Study, Technical University of Munich, Ernst-Otto-Fischer-Strasse 2, 85748 Garching, Germany; Institute of Structural Biology, Helmholtz Zentrum München, Ingolstädter Landstrasse 1, 85764 Neuherberg, Germany
| | - Stephen R Sprang
- Graduate Program in Biochemistry and Biophysics, University of Montana, Missoula, MT 59812, USA; Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, MT 59812, USA; Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA.
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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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Vural A, Nabar NR, Hwang IY, Sohn S, Park C, Karlsson MCI, Blumer JB, Kehrl JH. Gα i2 Signaling Regulates Inflammasome Priming and Cytokine Production by Biasing Macrophage Phenotype Determination. THE JOURNAL OF IMMUNOLOGY 2019; 202:1510-1520. [PMID: 30683698 DOI: 10.4049/jimmunol.1801145] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Accepted: 12/19/2018] [Indexed: 12/14/2022]
Abstract
Macrophages exist as innate immune subsets that exhibit phenotypic heterogeneity and functional plasticity. Their phenotypes are dictated by inputs from the tissue microenvironment. G-protein-coupled receptors are essential in transducing signals from the microenvironment, and heterotrimeric Gα signaling links these receptors to downstream effectors. Several Gαi-coupled G-protein-coupled receptors have been implicated in macrophage polarization. In this study, we use genetically modified mice to investigate the role of Gαi2 on inflammasome activity and macrophage polarization. We report that Gαi2 in murine bone marrow-derived macrophages (BMDMs) regulates IL-1β release after activation of the NLRP3, AIM2, and NLRC4 inflammasomes. We show this regulation stems from the biased polarity of Gαi2 deficient (Gnai2 -/-) and RGS-insensitive Gαi2 (Gnai2 G184S/G184S) BMDMs. We determined that although Gnai2 G184S/G184S BMDMs (excess Gαi2 signaling) have a tendency toward classically activated proinflammatory (M1) phenotype, Gnai2-/- BMDMs (Gαi2 deficient) are biased toward alternatively activated anti-inflammatory (M2) phenotype. Finally, we find that Gαi2-deficient macrophages have increased Akt activation and IFN-β production but defects in ERK1/2 and STAT3 activation after LPS stimulation. Gαi2-deficient macrophages also exhibit increased STAT6 activation after IL-4 stimulation. In summary, our data indicates that excess Gαi2 signaling promotes an M1 macrophage phenotype, whereas Gαi2 signaling deficiency promotes an M2 phenotype. Understanding Gαi2-mediated effects on macrophage polarization may bring to light insights regarding disease pathogenesis and the reprogramming of macrophages for the development of novel therapeutics.
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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, MD 20892
| | - Neel R Nabar
- B-Cell Molecular Immunology Section, Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892; .,Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, 171 77 Stockholm, Sweden; and
| | - Il-Young Hwang
- B-Cell Molecular Immunology Section, Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Silke Sohn
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, 171 77 Stockholm, Sweden; and
| | - Chung Park
- B-Cell Molecular Immunology Section, Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Mikael C I Karlsson
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, 171 77 Stockholm, Sweden; and
| | - Joe B Blumer
- Department of Cell and Molecular Pharmacology and Experimental Therapeutics, Medical University of South Carolina, Charleston, SC 29425
| | - John H Kehrl
- B-Cell Molecular Immunology Section, Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892;
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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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Structural basis of Gip1 for cytosolic sequestration of G protein in wide-range chemotaxis. Nat Commun 2018; 9:4635. [PMID: 30401901 PMCID: PMC6219514 DOI: 10.1038/s41467-018-07035-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Accepted: 10/10/2018] [Indexed: 12/15/2022] Open
Abstract
G protein interacting protein 1 (Gip1) binds and sequesters heterotrimeric G proteins in the cytosolic pool, thus regulating G protein-coupled receptor (GPCR) signalling for eukaryotic chemotaxis. Here, we report the underlying structural basis of Gip1 function. The crystal structure reveals that the region of Gip1 that binds to the G protein has a cylinder-like fold with a central hydrophobic cavity composed of six α-helices. Mutagenesis and biochemical analyses indicate that the hydrophobic cavity and the hydrogen bond network at the entrance of the cavity are essential for complex formation with the geranylgeranyl modification on the Gγ subunit. Mutations of the cavity impair G protein sequestration and translocation to the membrane from the cytosol upon receptor stimulation, leading to defects in chemotaxis at higher chemoattractant concentrations. These results demonstrate that the Gip1-dependent regulation of G protein shuttling ensures wide-range gradient sensing in eukaryotic chemotaxis. Gip1 sequesters heterotrimeric G proteins in the cytosolic pool which regulates G protein-coupled receptor signalling for eukaryotic chemotaxis. Here the authors provide the crystal structure of Gip1's G protein-binding region and show that mutations in this region lead to G protein sequestration and ultimately chemotaxis defects.
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Sakima M, Hayashi H, Mamun AA, Sato M. VEGFR-3 signaling is regulated by a G-protein activator, activator of G-protein signaling 8, in lymphatic endothelial cells. Exp Cell Res 2018; 368:13-23. [DOI: 10.1016/j.yexcr.2018.04.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Revised: 04/04/2018] [Accepted: 04/06/2018] [Indexed: 12/15/2022]
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Senarath K, Kankanamge D, Samaradivakara S, Ratnayake K, Tennakoon M, Karunarathne A. Regulation of G Protein βγ Signaling. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2018; 339:133-191. [PMID: 29776603 DOI: 10.1016/bs.ircmb.2018.02.008] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Heterotrimeric guanine nucleotide-binding proteins (G proteins) deliver external signals to the cell interior, upon activation by the external signal stimulated G protein-coupled receptors (GPCRs).While the activated GPCRs control several pathways independently, activated G proteins control the vast majority of cellular and physiological functions, ranging from vision to cardiovascular homeostasis. Activated GPCRs dissociate GαGDPβγ heterotrimer into GαGTP and free Gβγ. Earlier, GαGTP was recognized as the primary signal transducer of the pathway and Gβγ as a passive signaling modality that facilitates the activity of Gα. However, Gβγ later found to regulate more number of pathways than GαGTP does. Once liberated from the heterotrimer, free Gβγ interacts and activates a diverse range of signaling regulators including kinases, lipases, GTPases, and ion channels, and it does not require any posttranslation modifications. Gβγ family consists of 48 members, which show cell- and tissue-specific expressions, and recent reports show that cells employ the subtype diversity in Gβγ to achieve desired signaling outcomes. In addition to activated GPCRs, which induce free Gβγ generation and the rate of GTP hydrolysis in Gα, which sequester Gβγ in the heterotrimer, terminating Gβγ signaling, additional regulatory mechanisms exist to regulate Gβγ activity. In this chapter, we discuss structure and function, subtype diversity and its significance in signaling regulation, effector activation, regulatory mechanisms as well as the disease relevance of Gβγ in eukaryotes.
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Nakhaei-Rad S, Haghighi F, Nouri P, Rezaei Adariani S, Lissy J, Kazemein Jasemi NS, Dvorsky R, Ahmadian MR. Structural fingerprints, interactions, and signaling networks of RAS family proteins beyond RAS isoforms. Crit Rev Biochem Mol Biol 2018; 53:130-156. [PMID: 29457927 DOI: 10.1080/10409238.2018.1431605] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Saeideh Nakhaei-Rad
- a Institute of Biochemistry and Molecular Biology II, Medical Faculty , Heinrich-Heine University , Düsseldorf , Germany
| | - Fereshteh Haghighi
- a Institute of Biochemistry and Molecular Biology II, Medical Faculty , Heinrich-Heine University , Düsseldorf , Germany
| | - Parivash Nouri
- a Institute of Biochemistry and Molecular Biology II, Medical Faculty , Heinrich-Heine University , Düsseldorf , Germany
| | - Soheila Rezaei Adariani
- a Institute of Biochemistry and Molecular Biology II, Medical Faculty , Heinrich-Heine University , Düsseldorf , Germany
| | - Jana Lissy
- a Institute of Biochemistry and Molecular Biology II, Medical Faculty , Heinrich-Heine University , Düsseldorf , Germany
| | - Neda S Kazemein Jasemi
- a Institute of Biochemistry and Molecular Biology II, Medical Faculty , Heinrich-Heine University , Düsseldorf , Germany
| | - Radovan Dvorsky
- a Institute of Biochemistry and Molecular Biology II, Medical Faculty , Heinrich-Heine University , Düsseldorf , Germany
| | - Mohammad Reza Ahmadian
- a Institute of Biochemistry and Molecular Biology II, Medical Faculty , Heinrich-Heine University , Düsseldorf , Germany
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Siripurapu P, Kankanamge D, Ratnayake K, Senarath K, Karunarathne A. Two independent but synchronized Gβγ subunit-controlled pathways are essential for trailing-edge retraction during macrophage migration. J Biol Chem 2017; 292:17482-17495. [PMID: 28864771 DOI: 10.1074/jbc.m117.787838] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Revised: 08/27/2017] [Indexed: 12/25/2022] Open
Abstract
Chemokine-induced directional cell migration is a universal cellular mechanism and plays crucial roles in numerous biological processes, including embryonic development, immune system function, and tissue remodeling and regeneration. During the migration of a stationary cell, the cell polarizes, forms lamellipodia at the leading edge (LE), and triggers the concurrent retraction of the trailing edge (TE). During cell migration governed by inhibitory G protein (Gi)-coupled receptors (GPCRs), G protein βγ (Gβγ) subunits control the LE signaling. Interestingly, TE retraction has been linked to the activation of the small GTPase Ras homolog family member A (RhoA) by the Gα12/13 pathway. However, it is not clear how the activation of Gi-coupled GPCRs at the LE orchestrates the TE retraction in RAW264.7 macrophages. Here, using an optogenetic approach involving an opsin to activate the Gi pathway in defined subcellular regions of RAW cells, we show that in addition to their LE activities, free Gβγ subunits also govern TE retraction by operating two independent, yet synchronized, pathways. The first pathway involves RhoA activation, which prevents dephosphorylation of the myosin light chain, allowing actomyosin contractility to proceed. The second pathway activates phospholipase Cβ and induces myosin light chain phosphorylation to enhance actomyosin contractility through increasing cytosolic calcium. We further show that both of these pathways are essential, and inhibition of either one is sufficient to abolish the Gi-coupled GPCR-governed TE retraction and subsequent migration of RAW cells.
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Affiliation(s)
- Praneeth Siripurapu
- From the Department of Chemistry and Biochemistry, University of Toledo, Toledo, Ohio 43606
| | - Dinesh Kankanamge
- From the Department of Chemistry and Biochemistry, University of Toledo, Toledo, Ohio 43606
| | - Kasun Ratnayake
- From the Department of Chemistry and Biochemistry, University of Toledo, Toledo, Ohio 43606
| | - Kanishka Senarath
- From the Department of Chemistry and Biochemistry, University of Toledo, Toledo, Ohio 43606
| | - Ajith Karunarathne
- From the Department of Chemistry and Biochemistry, University of Toledo, Toledo, Ohio 43606
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Nanosecond Dynamics of Gαi1 Bound to Nucleotides or Ric-8A, a Gα Chaperone with GEF Activity. Biophys J 2017; 111:722-731. [PMID: 27558716 DOI: 10.1016/j.bpj.2016.07.021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Revised: 06/22/2016] [Accepted: 07/11/2016] [Indexed: 12/13/2022] Open
Abstract
Resistance to Inhibitors of Cholinesterase A (Ric-8A) is a 60-kDa cytosolic protein that has chaperone and guanine nucleotide exchange (GEF) activity toward heterotrimeric G protein α subunits of the i, q, and 12/13 classes, catalyzing the release of GDP from Gα and subsequent binding of GTP. In the absence of GTP or GTP analogs, and subsequent to GDP release, Gα forms a stable nucleotide-free complex with Ric-8A. In this study, time-resolved fluorescence anisotropy measurements were employed to detect local motions of Gαi1 labeled at selected sites with Alexa 488 (C5) fluorescent dye (Ax) in the GDP, GTPγS (collectively, GXP), and Ric-8A-bound states. Sites selected for Alexa 488 (C5) derivatization were in the α-helical domain (residue 106), the α-helical domain-Ras-like domain hinge (residue 63), Switch I (residue 180), Switch II (residue 209), Switch III (residue 238), the α4 helix (residue 305), and at the junction between the purine-binding subsite in the β6-α5 loop and the C-terminal α helix (residue 330). In the GXP-bound states, the Alexa fluorophore reports local motions with correlation times ranging from 1.0 to 1.8 ns. The dynamics at Ax180 is slower in Gαi1•GDP than in Gαi1•GTPγS. The reverse is true at Ax209. The order parameters, S(2), for Alexa probes at switch residues are high (0.78-0.88) in Gαi1•GDP and lower (0.67-0.75) in Gαi1•GTPγS, although in crystal structures, switch segments are more ordered in the latter. Local motions at Ax63, Ax180, Ax209, and Ax330 are all markedly slower (2.3-2.8 ns) in Gαi1:Ric-8A than in Gαi1•GXP, and only modest (± 0.1) differences in S(2) are observed at most sites in Gαi1:Ric-8A relative to Gαi1•GXP. The slow dynamics suggests long-range correlated transitions within an ensemble of states and, particularly in the hinge and switch segments that make direct contact with Ric-8A. Induction of Gαi1 structural heterogeneity by Ric-8A provides a mechanism for nucleotide release.
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Defective Gpsm2/Gα i3 signalling disrupts stereocilia development and growth cone actin dynamics in Chudley-McCullough syndrome. Nat Commun 2017; 8:14907. [PMID: 28387217 PMCID: PMC5385604 DOI: 10.1038/ncomms14907] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Accepted: 02/13/2017] [Indexed: 01/14/2023] Open
Abstract
Mutations in GPSM2 cause Chudley-McCullough syndrome (CMCS), an autosomal recessive neurological disorder characterized by early-onset sensorineural deafness and brain anomalies. Here, we show that mutation of the mouse orthologue of GPSM2 affects actin-rich stereocilia elongation in auditory and vestibular hair cells, causing deafness and balance defects. The G-protein subunit Gαi3, a well-documented partner of Gpsm2, participates in the elongation process, and its absence also causes hearing deficits. We show that Gpsm2 defines an ∼200 nm nanodomain at the tips of stereocilia and this localization requires the presence of Gαi3, myosin 15 and whirlin. Using single-molecule tracking, we report that loss of Gpsm2 leads to decreased outgrowth and a disruption of actin dynamics in neuronal growth cones. Our results elucidate the aetiology of CMCS and highlight a new molecular role for Gpsm2/Gαi3 in the regulation of actin dynamics in epithelial and neuronal tissues. Mutations in GPSM2 cause a rare disease characterized by deafness and brain abnormalities. Here the authors show that Gpsm2 forms a molecular complex with a heterotrimeric G-protein subunit, whirlin and a myosin motor to regulate actin dynamics in neurons and auditory hair cell stereocilia.
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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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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: 20] [Impact Index Per Article: 2.5] [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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Regulator of G-protein signalling and GoLoco proteins suppress TRPC4 channel function via acting at Gαi/o. Biochem J 2016; 473:1379-90. [PMID: 26987813 DOI: 10.1042/bcj20160214] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Accepted: 03/16/2016] [Indexed: 01/09/2023]
Abstract
Transient receptor potential canonical 4 (TRPC4) forms non-selective cation channels implicated in the regulation of diverse physiological functions. Previously, TRPC4 was shown to be activated by the Gi/o subgroup of heterotrimeric G-proteins involving Gαi/o, rather than Gβγ, subunits. Because the lifetime and availability of Gα-GTP are regulated by regulators of G-protein signalling (RGS) and Gαi/o-Loco (GoLoco) domain-containing proteins via their GTPase-activating protein (GAP) and guanine-nucleotide-dissociation inhibitor (GDI) functions respectively, we tested how RGS and GoLoco domain proteins affect TRPC4 currents activated via Gi/o-coupled receptors. Using whole-cell patch-clamp recordings, we show that both RGS and GoLoco proteins [RGS4, RGS6, RGS12, RGS14, LGN or activator of G-protein signalling 3 (AGS3)] suppress receptor-mediated TRPC4 activation without causing detectable basal current or altering surface expression of the channel protein. The inhibitory effects are dependent on the GAP and GoLoco domains and facilitated by enhancing membrane targeting of the GoLoco protein AGS3. In addition, RGS, but not GoLoco, proteins accelerate desensitization of receptor-activation evoked TRPC4 currents. The inhibitory effects of RGS and GoLoco domains are additive and are most prominent with RGS12 and RGS14, which contain both RGS and GoLoco domains. Our data support the notion that the Gα, but not Gβγ, arm of the Gi/o signalling is involved in TRPC4 activation and unveil new roles for RGS and GoLoco domain proteins in fine-tuning TRPC4 activities. The versatile and diverse functions of RGS and GoLoco proteins in regulating G-protein signalling may underlie the complexity of receptor-operated TRPC4 activation in various cell types under different conditions.
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Hayashi H, Al Mamun A, Sakima M, Sato M. Activator of G-protein signaling 8 is involved in VEGF-mediated signal processing during angiogenesis. J Cell Sci 2016; 129:1210-22. [PMID: 26826188 DOI: 10.1242/jcs.181883] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Accepted: 01/26/2016] [Indexed: 01/13/2023] Open
Abstract
Activator of G-protein signaling 8 (AGS8, also known as FNDC1) is a receptor-independent accessory protein for the Gβγ subunit, which was isolated from rat heart subjected to repetitive transient ischemia with the substantial development of collaterals. Here, we report the role of AGS8 in vessel formation by endothelial cells. Knockdown of AGS8 by small interfering RNA (siRNA) inhibited vascular endothelial growth factor (VEGF)-induced tube formation, as well as VEGF-stimulated cell growth and migration. VEGF stimulated the phosphorylation of the VEGF receptor-2 (VEGFR-2, also known as KDR), ERK1/2 and p38 MAPK; however, knockdown of AGS8 inhibited these signaling events. Signal alterations by AGS8 siRNA were associated with a decrease of cell surface VEGFR-2 and an increase of VEGFR-2 in the cytosol. Endocytosis blockers did not influence the decrease of VEGFR-2 by AGS8 siRNA, suggesting the involvement of AGS8 in VEGFR-2 trafficking to the plasma membrane. VEGFR-2 formed a complex with AGS8 in cells, and a peptide designed to disrupt AGS8-Gβγ interaction inhibited VEGF-induced tube formation. These data suggest a potential role for AGS8-Gβγ in VEGF signal processing. AGS8 might play a key role in tissue adaptation by regulating angiogenic events.
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Affiliation(s)
- Hisaki Hayashi
- Department of Physiology, Aichi Medical University, Nagakute, Aichi 480-1195, Japan
| | - Abdullah Al Mamun
- Department of Physiology, Aichi Medical University, Nagakute, Aichi 480-1195, Japan
| | - Miho Sakima
- Department of Physiology, Aichi Medical University, Nagakute, Aichi 480-1195, Japan
| | - Motohiko Sato
- Department of Physiology, Aichi Medical University, Nagakute, Aichi 480-1195, Japan
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Vural A, Al-Khodor S, Cheung GYC, Shi CS, Srinivasan L, McQuiston TJ, Hwang IY, Yeh AJ, Blumer JB, Briken V, Williamson PR, Otto M, Fraser IDC, Kehrl JH. Activator of G-Protein Signaling 3-Induced Lysosomal Biogenesis Limits Macrophage Intracellular Bacterial Infection. THE JOURNAL OF IMMUNOLOGY 2015; 196:846-56. [PMID: 26667172 DOI: 10.4049/jimmunol.1501595] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Accepted: 11/14/2015] [Indexed: 01/08/2023]
Abstract
Many intracellular pathogens cause disease by subverting macrophage innate immune defense mechanisms. Intracellular pathogens actively avoid delivery to or directly target lysosomes, the major intracellular degradative organelle. In this article, we demonstrate that activator of G-protein signaling 3 (AGS3), an LPS-inducible protein in macrophages, affects both lysosomal biogenesis and activity. AGS3 binds the Gi family of G proteins via its G-protein regulatory (GoLoco) motif, stabilizing the Gα subunit in its GDP-bound conformation. Elevated AGS3 levels in macrophages limited the activity of the mammalian target of rapamycin pathway, a sensor of cellular nutritional status. This triggered the nuclear translocation of transcription factor EB, a known activator of lysosomal gene transcription. In contrast, AGS3-deficient macrophages had increased mammalian target of rapamycin activity, reduced transcription factor EB activity, and a lower lysosomal mass. High levels of AGS3 in macrophages enhanced their resistance to infection by Burkholderia cenocepacia J2315, Mycobacterium tuberculosis, and methicillin-resistant Staphylococcus aureus, whereas AGS3-deficient macrophages were more susceptible. We conclude that LPS priming increases AGS3 levels, which enhances lysosomal function and increases the capacity of macrophages to eliminate intracellular pathogens.
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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, MD 20892
| | - Souhaila Al-Khodor
- Signaling Systems Unit, Laboratory of Systems Biology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Gordon Y C Cheung
- Pathogen Molecular Genetics Section, Laboratory of Human Bacterial Pathogenesis, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Chong-Shan Shi
- B-Cell Molecular Immunology Section, Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Lalitha Srinivasan
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742
| | - Travis J McQuiston
- Translational Mycology Unit, Laboratory of Clinical Infectious Disease, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892; and
| | - Il-Young Hwang
- B-Cell Molecular Immunology Section, Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Anthony J Yeh
- Pathogen Molecular Genetics Section, Laboratory of Human Bacterial Pathogenesis, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Joe B Blumer
- Department of Cell and Molecular Pharmacology and Experimental Therapeutics, Medical University of South Carolina, Charleston, SC 29425
| | - Volker Briken
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742
| | - Peter R Williamson
- Translational Mycology Unit, Laboratory of Clinical Infectious Disease, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892; and
| | - Michael Otto
- Pathogen Molecular Genetics Section, Laboratory of Human Bacterial Pathogenesis, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Iain D C Fraser
- Signaling Systems Unit, Laboratory of Systems Biology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
| | - John H Kehrl
- B-Cell Molecular Immunology Section, Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892;
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Hewavitharana T, Wedegaertner PB. PAQR3 regulates Golgi vesicle fission and transport via the Gβγ-PKD signaling pathway. Cell Signal 2015; 27:2444-51. [PMID: 26327583 PMCID: PMC4684484 DOI: 10.1016/j.cellsig.2015.08.017] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Revised: 08/21/2015] [Accepted: 08/26/2015] [Indexed: 01/06/2023]
Abstract
Heterotrimeric G proteins function at diverse subcellular locations, in addition to canonical signaling at the plasma membrane (PM). Gβγ signals at the Golgi, via protein kinase D (PKD), to regulate fission of PM-destined vesicles. However, the mechanism by which Gβγ is regulated at the Golgi in this process remains elusive. Recent studies have revealed that PAQR3 (Progestin and AdipoQ Receptor 3), also called RKTG (Raf Kinase Trapping to the Golgi), interacts with the Gβ subunit and localizes Gβ to the Golgi thereby inhibiting Gβγ signaling at the PM. Herein we show that, in contrast to this inhibition of canonical Gβγ signaling at the PM, PAQR3 promotes Gβγ signaling at the Golgi. Expression of PAQR3 causes fragmentation of the Golgi, while a Gβ binding-deficient mutant of PAQR3 does not cause Golgi fragmentation. Also, a C-terminal fragment of GRK2 (GRK2ct), which interacts with Gβγ and inhibits Gβγ signaling, and gallein, a small molecule inhibitor of Gβγ, are both able to inhibit PAQR3-mediated Golgi fragmentation. Furthermore, a dominant negative form of PKD (PKD-DN) and a pharmacological inhibitor of PKD, Gö6976, also inhibit PAQR3-mediated fragmentation of the Golgi. Importantly, expression of the Gβ binding-deficient mutant of PAQR3 inhibits the constitutive transport of the model cargo protein VSV-G from the Golgi to the PM, indicating the involvement of PAQR3 in Golgi-to PM vesicle transport and a dominant negative role for this mutant. Collectively, these results reveal a novel role for the newly characterized, Golgi-localized PAQR3 in regulating Gβγ at the non-canonical subcellular location of the Golgi and thus for controlling Golgi-to-PM protein transport via the Gβγ-PKD signaling pathway.
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Affiliation(s)
- Thamara Hewavitharana
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 233 S. 10th St., 839 BLSB, Philadelphia, PA 19107, United States.
| | - Philip B Wedegaertner
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 233 S. 10th St., 839 BLSB, Philadelphia, PA 19107, United States.
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Park F. Accessory proteins for heterotrimeric G-proteins in the kidney. Front Physiol 2015; 6:219. [PMID: 26300785 PMCID: PMC4528294 DOI: 10.3389/fphys.2015.00219] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Accepted: 07/20/2015] [Indexed: 11/17/2022] Open
Abstract
Heterotrimeric G-proteins play a fundamentally important role in regulating signal transduction pathways in the kidney. Accessory proteins are being identified as direct binding partners for heterotrimeric G-protein α or βγ subunits to promote more diverse mechanisms by which G-protein signaling is controlled. In some instances, accessory proteins can modulate the signaling magnitude, localization, and duration following the activation of cell membrane-associated receptors. Alternatively, accessory proteins complexed with their G-protein α or βγ subunits can promote non-canonical models of signaling activity within the cell. In this review, we will highlight the expression profile, localization and functional importance of these newly identified accessory proteins to control the function of select G-protein subunits under normal and various disease conditions observed in the kidney.
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Affiliation(s)
- Frank Park
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Tennessee Health Science Center Memphis, TN, USA
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Abstract
The G12 family of heterotrimeric G proteins is defined by their α-subunits,
Gα12 and Gα13. These α-subunits
regulate cellular homeostasis, cell migration, and oncogenesis in a
context-specific manner primarily through their interactions with distinct
proteins partners that include diverse effector molecules and scaffold proteins.
With a focus on identifying any other novel regulatory protein(s) that can
directly interact with Gα13, we subjected Gα13
to tandem affinity purification-coupled mass spectrometric analysis. Our results
from such analysis indicate that Gα13 potently interacts with
mammalian Ric-8A. Our mass spectrometric analysis data also indicates that
Ric-8A, which was tandem affinity purified along with Gα13, is
phosphorylated at Ser-436, Thr-441, Thr-443 and Tyr-435. Using a serial deletion
approach, we have defined that the C-terminus of Gα13 containing
the guanine-ring interaction site is essential and sufficient for its
interaction with Ric-8A. Evaluation of Gα13-specific signaling
pathways in SKOV3 or HeyA8 ovarian cancer cell lines indicate that Ric-8A
potentiates Gα13-mediated activation of RhoA, Cdc42, and the
downstream p38MAPK. We also establish that the tyrosine phosphorylation of
Ric-8A, thus far unidentified, is potently stimulated by Gα13.
Our results also indicate that the stimulation of tyrosine-phosphorylation of
Ric-8A by Gα13 is partially sensitive to inhibitors of
Src-family of kinases, namely PP2 and SI. Furthermore, we demonstrate that
Gα13 promotes the translocation of Ric-8A to plasma membrane
and this translocation is attenuated by the Src-inhibitors, SI1 and PP2. Thus,
our results demonstrate for the first time that Gα13 stimulates
the tyrosine phosphorylation of Ric-8A and Gα13-mediated
tyrosine-phosphorylation plays a critical role in the translocation of Ric-8A to
plasma membrane.
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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: 91] [Impact Index Per Article: 10.1] [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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Zhang P, Kofron CM, Mende U. Heterotrimeric G protein-mediated signaling and its non-canonical regulation in the heart. Life Sci 2015; 129:35-41. [PMID: 25818188 PMCID: PMC4415990 DOI: 10.1016/j.lfs.2015.02.029] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2014] [Revised: 01/31/2015] [Accepted: 02/11/2015] [Indexed: 11/20/2022]
Abstract
Heterotrimeric guanine nucleotide-binding proteins (G proteins) regulate a multitude of signaling pathways in mammalian cells by transducing signals from G protein-coupled receptors (GPCRs) to effectors, which in turn regulate cellular function. In the myocardium, G protein signaling occurs in all cardiac cell types and is centrally involved in the regulation of heart rate, pump function, and vascular tone and in the response to hemodynamic stress and injury. Perturbations in G protein-mediated signaling are well known to contribute to cardiac hypertrophy, failure, and arrhythmias. Most of the currently used drugs for cardiac and other diseases target GPCR signaling. In the canonical G protein signaling paradigm, G proteins that are located at the cytoplasmic surface of the plasma membrane become activated after an agonist-induced conformational change of GPCRs, which then allows GTP-bound Gα and free Gβγ subunits to activate or inhibit effector proteins. Research over the past two decades has markedly broadened the original paradigm with a GPCR-G protein-effector at the cell surface at its core by revealing novel binding partners and additional subcellular localizations for heterotrimeric G proteins that facilitate many previously unrecognized functional effects. In this review, we focus on non-canonical and epigenetic-related mechanisms that regulate heterotrimeric G protein expression, activation, and localization and discuss functional consequences using cardiac examples where possible. Mechanisms reviewed involve microRNAs, histone deacetylases, chaperones, alternative modes of G protein activation, and posttranslational modifications. Some of these newly characterized mechanisms may be further developed into novel strategies for the treatment of cardiac disease and beyond.
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Affiliation(s)
- Peng Zhang
- Cardiovascular Research Center, Cardiology Division, Rhode Island Hospital, Providence, RI, USA; Alpert Medical School of Brown University, Providence, RI, USA
| | - Celinda M Kofron
- Cardiovascular Research Center, Cardiology Division, Rhode Island Hospital, Providence, RI, USA; Alpert Medical School of Brown University, Providence, RI, USA
| | - Ulrike Mende
- Cardiovascular Research Center, Cardiology Division, Rhode Island Hospital, Providence, RI, USA; Alpert Medical School of Brown University, Providence, RI, USA.
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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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Evans PR, Dudek SM, Hepler JR. Regulator of G Protein Signaling 14: A Molecular Brake on Synaptic Plasticity Linked to Learning and Memory. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2015; 133:169-206. [PMID: 26123307 DOI: 10.1016/bs.pmbts.2015.03.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The regulators of G protein signaling (RGS) proteins are a diverse family of proteins that function as central components of G protein and other signaling pathways. In the brain, regulator of G protein signaling 14 (RGS14) is enriched in neurons in the hippocampus where the mRNA and protein are highly expressed. This brain region plays a major role in processing learning and forming new memories. RGS14 is an unusual RGS protein that acts as a multifunctional scaffolding protein to integrate signaling events and pathways essential for synaptic plasticity, including conventional and unconventional G protein signaling, mitogen-activated protein kinase, and, possibly, calcium signaling pathways. Within the hippocampus of primates and rodents, RGS14 is predominantly found in the enigmatic CA2 subfield. Principal neurons within the CA2 subfield differ from neighboring hippocampal regions in that they lack a capacity for long-term potentiation (LTP) of synaptic transmission, which is widely viewed as the cellular substrate of learning and memory formation. RGS14 was recently identified as a natural suppressor of LTP in hippocampal CA2 neurons as well as forms of learning and memory that depend on the hippocampus. Although CA2 has only recently been studied, compelling recent evidence implicates area CA2 as a critical component of hippocampus circuitry with functional roles in mediating certain types of learning and memory. This review will highlight the known functions of RGS14 in cell signaling and hippocampus physiology, and discuss potential roles for RGS14 in human cognition and disease.
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Affiliation(s)
- Paul R Evans
- Department of Pharmacology, Emory University School of Medicine, Rollins Research Center, Atlanta, Georgia, USA
| | - Serena M Dudek
- Neurobiology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina, USA
| | - John R Hepler
- Department of Pharmacology, Emory University School of Medicine, Rollins Research Center, Atlanta, Georgia, USA.
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Brown NE, Goswami D, Branch MR, Ramineni S, Ortlund EA, Griffin PR, Hepler JR. Integration of G protein α (Gα) signaling by the regulator of G protein signaling 14 (RGS14). J Biol Chem 2015; 290:9037-49. [PMID: 25666614 DOI: 10.1074/jbc.m114.634329] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2014] [Indexed: 11/06/2022] Open
Abstract
RGS14 contains distinct binding sites for both active (GTP-bound) and inactive (GDP-bound) forms of Gα subunits. The N-terminal regulator of G protein signaling (RGS) domain binds active Gαi/o-GTP, whereas the C-terminal G protein regulatory (GPR) motif binds inactive Gαi1/3-GDP. The molecular basis for how RGS14 binds different activation states of Gα proteins to integrate G protein signaling is unknown. Here we explored the intramolecular communication between the GPR motif and the RGS domain upon G protein binding and examined whether RGS14 can functionally interact with two distinct forms of Gα subunits simultaneously. Using complementary cellular and biochemical approaches, we demonstrate that RGS14 forms a stable complex with inactive Gαi1-GDP at the plasma membrane and that free cytosolic RGS14 is recruited to the plasma membrane by activated Gαo-AlF4(-). Bioluminescence resonance energy transfer studies showed that RGS14 adopts different conformations in live cells when bound to Gα in different activation states. Hydrogen/deuterium exchange mass spectrometry revealed that RGS14 is a very dynamic protein that undergoes allosteric conformational changes when inactive Gαi1-GDP binds the GPR motif. Pure RGS14 forms a ternary complex with Gαo-AlF4(-) and an AlF4(-)-insensitive mutant (G42R) of Gαi1-GDP, as observed by size exclusion chromatography and differential hydrogen/deuterium exchange. Finally, a preformed RGS14·Gαi1-GDP complex exhibits full capacity to stimulate the GTPase activity of Gαo-GTP, demonstrating that RGS14 can functionally engage two distinct forms of Gα subunits simultaneously. Based on these findings, we propose a working model for how RGS14 integrates multiple G protein signals in host CA2 hippocampal neurons to modulate synaptic plasticity.
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Affiliation(s)
| | - Devrishi Goswami
- the Department of Molecular Therapeutics, The Scripps Research Institute, Jupiter, Florida 33458
| | | | | | - Eric A Ortlund
- Biochemistry, Emory University School of Medicine, Atlanta, Georgia 30322 and
| | - Patrick R Griffin
- the Department of Molecular Therapeutics, The Scripps Research Institute, Jupiter, Florida 33458
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Abstract
Heterotrimeric G proteins play a crucial role in regulating signal processing to maintain normal cellular homeostasis, and subtle perturbations in its activity can potentially lead to the pathogenesis of renal disorders or diseases. Cell-surface receptors and accessory proteins, which normally modify and organize the coupling of individual G protein subunits, contribute to the regulation of heterotrimeric G protein activity and their convergence and/or divergence of downstream signaling initiated by effector systems. Activators of G protein signaling (AGS) are a family of accessory proteins that intervene at multiple distinct points during the activation-inactivation cycle of G proteins, even in the absence of receptor stimulation. Perturbations in the expression of individual AGS proteins have been reported to modulate signal transduction pathways in a wide array of diseases and disorders within the brain, heart, immune system, and more recently, the kidney. This review will provide an overview of the expression profile, localization, and putative biologic role of the AGS family in the context of normal and diseased states of the kidney.
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Affiliation(s)
- Frank Park
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee
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Localization and expression profile of Group I and II Activators of G-protein Signaling in the kidney. J Mol Histol 2014; 46:123-36. [PMID: 25533045 DOI: 10.1007/s10735-014-9605-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Accepted: 12/15/2014] [Indexed: 10/24/2022]
Abstract
Activators of G-protein Signaling (AGS) are a family of accessory proteins that were discovered as modulators of heterotrimeric G-protein subunits. The primary aim of the present study was to localize Group I and II AGS proteins and determine the renal expression profile using immunohistochemistry and quantitative RT-PCR, respectively, during normal and injured states of the kidney. Group I AGS1 was found to be predominantly localized to the proximal tubule, Group II AGS3 and AGS5 were exclusively localized to the distal tubular segments, and Group II AGS6 was ubiquitously expressed in every nephron segment of the rodent kidney. In rat kidneys following ischemia-reperfusion injury (IRI), Group I AGS1 mRNA was dramatically increased after 24 h by fivefold (P < 0.05), whereas Group II AGS3 and AGS4 mRNA was significantly decreased at the same time point (P < 0.05). No significant change in the transcript levels were detected at other time points for any of the AGS genes between control and IRI groups. In polycystic diseased kidneys, mRNA levels for AGS3, AGS4 and AGS6 was significantly increased (P < 0.05) by 75-80 % in PCK rat kidneys. The identification of Group I and II AGS mRNA and protein in the kidney may provide insight into the potential mechanism of action during normal and varying states of renal disease or injury.
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