1
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Burger WAC, Draper-Joyce CJ, Valant C, Christopoulos A, Thal DM. Positive allosteric modulation of a GPCR ternary complex. SCIENCE ADVANCES 2024; 10:eadp7040. [PMID: 39259792 PMCID: PMC11389776 DOI: 10.1126/sciadv.adp7040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2024] [Accepted: 08/06/2024] [Indexed: 09/13/2024]
Abstract
The activation of a G protein-coupled receptor (GPCR) leads to the formation of a ternary complex between agonist, receptor, and G protein that is characterized by high-affinity binding. Allosteric modulators bind to a distinct binding site from the orthosteric agonist and can modulate both the affinity and the efficacy of orthosteric agonists. The influence allosteric modulators have on the high-affinity active state of the GPCR-G protein ternary complex is unknown due to limitations on attempting to characterize this interaction in recombinant whole cell or membrane-based assays. Here, we use the purified M2 muscarinic acetylcholine receptor reconstituted into nanodiscs to show that, once the agonist-bound high-affinity state is promoted by the G protein, positive allosteric modulators stabilize the ternary complex that, in the presence of nucleotides, leads to an enhanced initial rate of signaling. Our results enhance our understanding of how allosteric modulators influence orthosteric ligand signaling and will aid the design of allosteric therapeutics.
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Affiliation(s)
- Wessel A C Burger
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
- Australian Research Council Centre for Cryo-Electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Christopher J Draper-Joyce
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Celine Valant
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Arthur Christopoulos
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
- Australian Research Council Centre for Cryo-Electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - David M Thal
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
- Australian Research Council Centre for Cryo-Electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
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2
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Knight KM, Krumm BE, Kapolka NJ, Ludlam WG, Cui M, Mani S, Prytkova I, Obarow EG, Lefevre TJ, Wei W, Ma N, Huang XP, Fay JF, Vaidehi N, Smrcka AV, Slesinger PA, Logothetis DE, Martemyanov KA, Roth BL, Dohlman HG. A neurodevelopmental disorder mutation locks G proteins in the transitory pre-activated state. Nat Commun 2024; 15:6643. [PMID: 39103320 DOI: 10.1038/s41467-024-50964-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Accepted: 07/25/2024] [Indexed: 08/07/2024] Open
Abstract
Many neurotransmitter receptors activate G proteins through exchange of GDP for GTP. The intermediate nucleotide-free state has eluded characterization, due largely to its inherent instability. Here we characterize a G protein variant associated with a rare neurological disorder in humans. GαoK46E has a charge reversal that clashes with the phosphate groups of GDP and GTP. As anticipated, the purified protein binds poorly to guanine nucleotides yet retains wild-type affinity for G protein βγ subunits. In cells with physiological concentrations of nucleotide, GαoK46E forms a stable complex with receptors and Gβγ, impeding effector activation. Further, we demonstrate that the mutant can be easily purified in complex with dopamine-bound D2 receptors, and use cryo-electron microscopy to determine the structure, including both domains of Gαo, without nucleotide or stabilizing nanobodies. These findings reveal the molecular basis for the first committed step of G protein activation, establish a mechanistic basis for a neurological disorder, provide a simplified strategy to determine receptor-G protein structures, and a method to detect high affinity agonist binding in cells.
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Affiliation(s)
- Kevin M Knight
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Department of Neuroscience, The Herbert Wertheim UF Scripps Institute for Biomedical Innovation & Technology, University of Florida, Jupiter, FL, USA
| | - Brian E Krumm
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Nicholas J Kapolka
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - W Grant Ludlam
- Department of Neuroscience, The Herbert Wertheim UF Scripps Institute for Biomedical Innovation & Technology, University of Florida, Jupiter, FL, USA
| | - Meng Cui
- Department of Pharmaceutical Sciences Northeastern University, Boston, MA, USA
| | - Sepehr Mani
- Department of Pharmaceutical Sciences Northeastern University, Boston, MA, USA
| | - Iya Prytkova
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Elizabeth G Obarow
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Tyler J Lefevre
- Department of Pharmacology, University of Michigan, Ann Arbor, MI, USA
| | - Wenyuan Wei
- Department of Computational and Quantitative Medicine, Beckman Research Institute of the City of Hope, Duarte, CA, USA
| | - Ning Ma
- Department of Computational and Quantitative Medicine, Beckman Research Institute of the City of Hope, Duarte, CA, USA
| | - Xi-Ping Huang
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Jonathan F Fay
- Department of Biochemistry and Molecular Biology, School of Medicine, University of Maryland, Baltimore, Baltimore, MD, USA
| | - Nagarajan Vaidehi
- Department of Computational and Quantitative Medicine, Beckman Research Institute of the City of Hope, Duarte, CA, USA
| | - Alan V Smrcka
- Department of Pharmacology, University of Michigan, Ann Arbor, MI, USA
| | - Paul A Slesinger
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | | | - Kirill A Martemyanov
- Department of Neuroscience, The Herbert Wertheim UF Scripps Institute for Biomedical Innovation & Technology, University of Florida, Jupiter, FL, USA
| | - Bryan L Roth
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Henrik G Dohlman
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
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3
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Schihada H, Shekhani R, Schulte G. Quantitative assessment of constitutive G protein-coupled receptor activity with BRET-based G protein biosensors. Sci Signal 2021; 14:eabf1653. [PMID: 34516756 DOI: 10.1126/scisignal.abf1653] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
[Figure: see text].
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Affiliation(s)
- Hannes Schihada
- Section for Receptor Biology and Signaling, Department of Physiology and Pharmacology, Karolinska Institutet, Biomedicum, Solnavägen 9, SE-17165 Stockholm, Sweden
| | - Rawan Shekhani
- Section for Receptor Biology and Signaling, Department of Physiology and Pharmacology, Karolinska Institutet, Biomedicum, Solnavägen 9, SE-17165 Stockholm, Sweden
| | - Gunnar Schulte
- Section for Receptor Biology and Signaling, Department of Physiology and Pharmacology, Karolinska Institutet, Biomedicum, Solnavägen 9, SE-17165 Stockholm, Sweden
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4
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Maruta N, Trusov Y, Urano D, Chakravorty D, Assmann SM, Jones AM, Botella JR. GTP binding by Arabidopsis extra-large G protein 2 is not essential for its functions. PLANT PHYSIOLOGY 2021; 186:1240-1253. [PMID: 33729516 PMCID: PMC8195506 DOI: 10.1093/plphys/kiab119] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Accepted: 02/19/2021] [Indexed: 05/06/2023]
Abstract
The extra-large guanosine-5'-triphosphate (GTP)-binding protein 2, XLG2, is an unconventional Gα subunit of the Arabidopsis (Arabidopsis thaliana) heterotrimeric GTP-binding protein complex with a major role in plant defense. In vitro biochemical analyses and molecular dynamic simulations show that affinity of XLG2 for GTP is two orders of magnitude lower than that of the conventional Gα, AtGPA1. Here we tested the physiological relevance of GTP binding by XLG2. We generated an XLG2(T476N) variant with abolished GTP binding, as confirmed by in vitro GTPγS binding assay. Yeast three-hybrid, bimolecular fluorescence complementation, and split firefly-luciferase complementation assays revealed that the nucleotide-depleted XLG2(T476N) retained wild-type XLG2-like interactions with the Gβγ dimer and defense-related receptor-like kinases. Both wild-type and nucleotide-depleted XLG2(T476N) restored the defense responses against Fusarium oxysporum and Pseudomonas syringae compromised in the xlg2 xlg3 double mutant. Additionally, XLG2(T476N) was fully functional restoring stomatal density, root growth, and sensitivity to NaCl, but failed to complement impaired germination and vernalization-induced flowering. We conclude that XLG2 is able to function in a GTP-independent manner and discuss its possible mechanisms of action.
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Affiliation(s)
- Natsumi Maruta
- Plant Genetic Engineering Laboratory, School of Agriculture and Food Sciences, University of Queensland, Brisbane, QLD, 4072, Australia
- School of Chemistry and Molecular Biosciences, Institute for Molecular Bioscience and Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, QLD 4072, Australia
| | - Yuri Trusov
- Plant Genetic Engineering Laboratory, School of Agriculture and Food Sciences, University of Queensland, Brisbane, QLD, 4072, Australia
| | - Daisuke Urano
- Temasek Life Sciences Laboratory, 1 Research Link, National University of Singapore, Singapore 117604, Singapore
| | - David Chakravorty
- Department of Biology, Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Sarah M Assmann
- Department of Biology, Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Alan M Jones
- Department of Biology, University of North Carolina, Chapel Hill, North Carolina 27599, USA
- Department of Pharmacology, University of North Carolina, Chapel Hill, North Carolina 27599, USA
| | - Jose R Botella
- Plant Genetic Engineering Laboratory, School of Agriculture and Food Sciences, University of Queensland, Brisbane, QLD, 4072, Australia
- Author for communication:
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5
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Tong Y, Wu H, Liu Z, Wang Z, Huang B. G-Protein Subunit Gα i in Mitochondria, MrGPA1, Affects Conidiation, Stress Resistance, and Virulence of Entomopathogenic Fungus Metarhizium robertsii. Front Microbiol 2020; 11:1251. [PMID: 32612588 PMCID: PMC7309505 DOI: 10.3389/fmicb.2020.01251] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2020] [Accepted: 05/15/2020] [Indexed: 12/16/2022] Open
Abstract
G proteins are critical modulators or transducers in various transmembrane signaling systems. They play key roles in numerous biological processes in fungi, including vegetative growth, development of infection-related structures, asexual conidiation, and virulence. However, functions of G proteins in entomopathogenic fungi remain unclear. Here, we characterized the roles of MrGPA1, a G-protein subunit Gαi, in conidiation, stress resistance, and virulence in Metarhizium robertsii. MrGPA1 was localized in the mitochondria. MrGpa1 deletion resulted in a significant reduction (47%) in the conidiation capacity, and reduced expression of several key conidiation-related genes, including fluG, flbD, brlA, wetA, phiA, and stuA. Further, MrGpa1 disruption resulted in decreased fungal sensitivity to UV irradiation and thermal stress, as determined based on conidial germination of ΔMrGpa1 and wild-type (WT) strains. Chemical stress analysis indicated that MrGpa1 contributes to fungal antioxidant capacity and cell wall integrity, but is not involved in tolerance to antifungal drug and osmotic stress. Importantly, insect bioassays involving (topical inoculation and injection) of Galleria mellonella larvae revealed decreased virulence of ΔMrGpa1 strain after cuticle infection. This was accompanied by decreased rates of appressorium formation and reduced expression of several cuticle penetration-related genes. Further assays showed that MrGpa1 regulated intracellular cyclic AMP (cAMP) levels, but feeding with cAMP could not recover the appressorium formation rate of ΔMrGpa1. These observations suggest that MrGpa1 contributes to the regulation of conidiation, UV irradiation, thermal stress response, antioxidant capacity, and cell wall integrity in M. robertsii. This gene is also involved in insect cuticle penetration during infection. These findings raise the possibility of designing powerful strategies for genetic improvement of M. robertsii conidiation capacity and virulence for killing pests.
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Affiliation(s)
- Youmin Tong
- Anhui Provincial Key Laboratory of Microbial Pest Control, Anhui Agricultural University, Hefei, China
| | - Hao Wu
- Anhui Provincial Key Laboratory of Microbial Pest Control, Anhui Agricultural University, Hefei, China
| | - Zhenbang Liu
- School of Life Sciences, University of Science and Technology of China, Hefei, China
| | - Zhangxun Wang
- Anhui Provincial Key Laboratory of Microbial Pest Control, Anhui Agricultural University, Hefei, China
- School of Plant Protection, Anhui Agricultural University, Hefei, China
| | - Bo Huang
- Anhui Provincial Key Laboratory of Microbial Pest Control, Anhui Agricultural University, Hefei, China
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6
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Kniazeff J. The different aspects of the GABAB receptor allosteric modulation. FROM STRUCTURE TO CLINICAL DEVELOPMENT: ALLOSTERIC MODULATION OF G PROTEIN-COUPLED RECEPTORS 2020; 88:83-113. [DOI: 10.1016/bs.apha.2020.02.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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7
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Lou F, Abramyan TM, Jia H, Tropsha A, Jones AM. An atypical heterotrimeric Gα protein has substantially reduced nucleotide binding but retains nucleotide-independent interactions with its cognate RGS protein and Gβγ dimer. J Biomol Struct Dyn 2019; 38:5204-5218. [PMID: 31838952 DOI: 10.1080/07391102.2019.1704879] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Plants uniquely have a family of proteins called extra-large G proteins (XLG) that share homology in their C-terminal half with the canonical Gα subunits; we carefully detail here that Arabidopsis XLG2 lacks critical residues requisite for nucleotide binding and hydrolysis which is consistent with our quantitative analyses. Based on microscale thermophoresis, Arabidopsis XLG2 binds GTPγS with an affinity 100 times lower than that to canonical Gα subunits. This means that given the concentration range of guanine nucleotide in plant cells, XLG2 is not likely bound by GTP in vivo. Homology modeling and molecular dynamics simulations provide a plausible mechanism for the poor nucleotide binding affinity of XLG2. Simulations indicate substantially stronger salt bridge networks formed by several key amino-acid residues of AtGPA1 which are either misplaced or missing in XLG2. These residues in AtGPA1 not only maintain the overall shape and integrity of the apoprotein cavity but also increase the frequency of favorable nucleotide-protein interactions in the nucleotide-bound state. Despite this loss of nucleotide dependency, XLG2 binds the RGS domain of AtRGS1 with an affinity similar to the Arabidopsis AtGPA1 in its apo-state and about 2 times lower than AtGPA1 in its transition state. In addition, XLG2 binds the Gβγ dimer with an affinity similar to that of AtGPA1. XLG2 likely acts as a dominant negative Gα protein to block G protein signaling. We propose that XLG2, independent of guanine nucleotide binding, regulates the active state of the canonical G protein pathway directly by sequestering Gβγ and indirectly by promoting heterodimer formation.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Fei Lou
- Departments of Pharmacology, University of North Carolina at Chapel Hill, NC, USA
| | - Tigran M Abramyan
- Division of Chemical Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, NC, USA
| | - Haiyan Jia
- Departments of Pharmacology, University of North Carolina at Chapel Hill, NC, USA
| | - Alexander Tropsha
- Division of Chemical Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, NC, USA
| | - Alan M Jones
- Departments of Pharmacology, University of North Carolina at Chapel Hill, NC, USA.,Departments of Biology and Pharmacology, University of North Carolina at Chapel Hill, NC, USA
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8
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Maruta N, Trusov Y, Chakravorty D, Urano D, Assmann SM, Botella JR. Nucleotide exchange-dependent and nucleotide exchange-independent functions of plant heterotrimeric GTP-binding proteins. Sci Signal 2019; 12:12/606/eaav9526. [PMID: 31690635 DOI: 10.1126/scisignal.aav9526] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Heterotrimeric guanine nucleotide-binding proteins (G proteins), which are composed of α, β, and γ subunits, are versatile, guanine nucleotide-dependent, molecular on-off switches. In animals and fungi, the exchange of GDP for GTP on Gα controls G protein activation and is crucial for normal cellular responses to diverse extracellular signals. The model plant Arabidopsis thaliana has a single canonical Gα subunit, AtGPA1. We found that, in planta, the constitutively active, GTP-bound AtGPA1(Q222L) mutant and the nucleotide-free AtGPA1(S52C) mutant interacted with Gβγ1 and Gβγ2 dimers with similar affinities, suggesting that G protein heterotrimer formation occurred independently of nucleotide exchange. In contrast, AtGPA1(Q222L) had a greater affinity than that of AtGPA1(S52C) for Gβγ3, suggesting that the GTP-bound conformation of AtGPA1(Q222L) is distinct and tightly associated with Gβγ3. Functional analysis of transgenic lines expressing either AtGPA1(S52C) or AtGPA1(Q222L) in the gpa1-null mutant background revealed various mutant phenotypes that were complemented by either AtGPA1(S52C) or AtGPA1(Q222L). We conclude that, in addition to the canonical GDP-GTP exchange-dependent mechanism, plant G proteins can function independently of nucleotide exchange.
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Affiliation(s)
- Natsumi Maruta
- Plant Genetic Engineering Laboratory, School of Agriculture and Food Sciences, University of Queensland, Brisbane, QLD 4072, Australia
| | - Yuri Trusov
- Plant Genetic Engineering Laboratory, School of Agriculture and Food Sciences, University of Queensland, Brisbane, QLD 4072, Australia
| | - David Chakravorty
- Department of Biology, Pennsylvania State University, University Park, PA 16802, USA
| | - Daisuke Urano
- Temasek Life Sciences Laboratory, 1 Research Link, National University of Singapore, Singapore 117604, Singapore
| | - Sarah M Assmann
- Department of Biology, Pennsylvania State University, University Park, PA 16802, USA
| | - Jose R Botella
- Plant Genetic Engineering Laboratory, School of Agriculture and Food Sciences, University of Queensland, Brisbane, QLD 4072, Australia. .,State Key Laboratory of Cotton Biology, Department of Biology, Institute of Plant Stress Biology, Henan University, Kaifeng 475001, China
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9
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Li Z, Zhang X, Xue W, Zhang Y, Li C, Song Y, Mei M, Lu L, Wang Y, Zhou Z, Jin M, Bian Y, Zhang L, Wang X, Li L, Li X, Fu X, Sun Z, Wu J, Nan F, Chang Y, Yan J, Yu H, Feng X, Wang G, Zhang D, Fu X, Zhang Y, Young KH, Li W, Zhang M. Recurrent GNAQ mutation encoding T96S in natural killer/T cell lymphoma. Nat Commun 2019; 10:4209. [PMID: 31527657 PMCID: PMC6746819 DOI: 10.1038/s41467-019-12032-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Accepted: 08/16/2019] [Indexed: 01/04/2023] Open
Abstract
Natural killer/T cell lymphoma (NKTCL) is a rare and aggressive malignancy with a higher prevalence in Asia and South America. However, the molecular genetic mechanisms underlying NKTCL remain unclear. Here, we identify somatic mutations of GNAQ (encoding the T96S alteration of Gαq protein) in 8.7% (11/127) of NKTCL patients, through whole-exome/targeted deep sequencing. Using conditional knockout mice (Ncr1-Cre-Gnaqfl/fl), we demonstrate that Gαq deficiency leads to enhanced NK cell survival. We also find that Gαq suppresses tumor growth of NKTCL via inhibition of the AKT and MAPK signaling pathways. Moreover, the Gαq T96S mutant may act in a dominant negative manner to promote tumor growth in NKTCL. Clinically, patients with GNAQ T96S mutations have inferior survival. Taken together, we identify recurrent somatic GNAQ T96S mutations that may contribute to the pathogenesis of NKTCL. Our work thus has implications for refining our understanding of the genetic mechanisms of NKTCL and for the development of therapies.
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Affiliation(s)
- Zhaoming Li
- Department of Oncology, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, China
- Lymphoma Diagnosis and Treatment Center of Henan Province, 450000, Zhengzhou, China
| | - Xudong Zhang
- Department of Oncology, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, China
- Lymphoma Diagnosis and Treatment Center of Henan Province, 450000, Zhengzhou, China
| | - Weili Xue
- Department of Oncology, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, China
- Institute of Clinical Medicine, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, China
| | - Yanjie Zhang
- Department of Oncology, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, China
- Institute of Clinical Medicine, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, China
| | - Chaoping Li
- Department of Oncology, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, China
- Institute of Clinical Medicine, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, China
| | - Yue Song
- Department of Oncology, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, China
- Institute of Clinical Medicine, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, China
| | - Mei Mei
- Department of Oncology, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, China
- Institute of Clinical Medicine, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, China
| | - Lisha Lu
- Department of Oncology, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, China
- Institute of Clinical Medicine, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, China
| | - Yingjun Wang
- Department of Oncology, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, China
- Institute of Clinical Medicine, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, China
| | - Zhiyuan Zhou
- Department of Oncology, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, China
- Institute of Clinical Medicine, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, China
| | - Mengyuan Jin
- Department of Oncology, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, China
- Institute of Clinical Medicine, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, China
| | - Yangyang Bian
- Medical Research Centre, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, China
| | - Lei Zhang
- Department of Oncology, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, China
- Lymphoma Diagnosis and Treatment Center of Henan Province, 450000, Zhengzhou, China
| | - Xinhua Wang
- Department of Oncology, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, China
- Lymphoma Diagnosis and Treatment Center of Henan Province, 450000, Zhengzhou, China
| | - Ling Li
- Department of Oncology, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, China
- Lymphoma Diagnosis and Treatment Center of Henan Province, 450000, Zhengzhou, China
| | - Xin Li
- Department of Oncology, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, China
- Lymphoma Diagnosis and Treatment Center of Henan Province, 450000, Zhengzhou, China
| | - Xiaorui Fu
- Department of Oncology, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, China
- Lymphoma Diagnosis and Treatment Center of Henan Province, 450000, Zhengzhou, China
| | - Zhenchang Sun
- Department of Oncology, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, China
- Lymphoma Diagnosis and Treatment Center of Henan Province, 450000, Zhengzhou, China
| | - Jingjing Wu
- Department of Oncology, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, China
- Lymphoma Diagnosis and Treatment Center of Henan Province, 450000, Zhengzhou, China
| | - Feifei Nan
- Department of Oncology, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, China
- Lymphoma Diagnosis and Treatment Center of Henan Province, 450000, Zhengzhou, China
| | - Yu Chang
- Department of Oncology, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, China
- Lymphoma Diagnosis and Treatment Center of Henan Province, 450000, Zhengzhou, China
| | - Jiaqin Yan
- Department of Oncology, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, China
- Lymphoma Diagnosis and Treatment Center of Henan Province, 450000, Zhengzhou, China
| | - Hui Yu
- Department of Oncology, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, China
- Lymphoma Diagnosis and Treatment Center of Henan Province, 450000, Zhengzhou, China
| | - Xiaoyan Feng
- Department of Oncology, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, China
- Lymphoma Diagnosis and Treatment Center of Henan Province, 450000, Zhengzhou, China
| | - Guannan Wang
- Department of Pathology, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, China
| | - Dandan Zhang
- Department of Pathology, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, China
| | - Xuefei Fu
- Novogene Bioinformatics Technology Co, Ltd, 38 Xueqing Road, 100083, Beijing, China
| | - Yuan Zhang
- The Academy of Medical Science of Zhengzhou University, 450052, Zhengzhou, China
| | - Ken H Young
- Department of Hematopathology, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA
| | - Wencai Li
- Department of Pathology, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, China.
| | - Mingzhi Zhang
- Department of Oncology, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, China.
- Lymphoma Diagnosis and Treatment Center of Henan Province, 450000, Zhengzhou, China.
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10
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Gutzeit VA, Thibado J, Stor DS, Zhou Z, Blanchard SC, Andersen OS, Levitz J. Conformational dynamics between transmembrane domains and allosteric modulation of a metabotropic glutamate receptor. eLife 2019; 8:45116. [PMID: 31172948 PMCID: PMC6588349 DOI: 10.7554/elife.45116] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Accepted: 06/06/2019] [Indexed: 01/01/2023] Open
Abstract
Metabotropic glutamate receptors (mGluRs) are class C, synaptic G-protein-coupled receptors (GPCRs) that contain large extracellular ligand binding domains (LBDs) and form constitutive dimers. Despite the existence of a detailed picture of inter-LBD conformational dynamics and structural snapshots of both isolated domains and full-length receptors, it remains unclear how mGluR activation proceeds at the level of the transmembrane domains (TMDs) and how TMD-targeting allosteric drugs exert their effects. Here, we use time-resolved functional and conformational assays to dissect the mechanisms by which allosteric drugs activate and modulate mGluR2. Single-molecule subunit counting and inter-TMD fluorescence resonance energy transfer measurements in living cells reveal LBD-independent conformational rearrangements between TMD dimers during receptor modulation. Using these assays along with functional readouts, we uncover heterogeneity in the magnitude, direction, and the timing of the action of both positive and negative allosteric drugs. Together our experiments lead to a three-state model of TMD activation, which provides a framework for understanding how inter-subunit rearrangements drive class C GPCR activation.
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Affiliation(s)
- Vanessa A Gutzeit
- Neuroscience Graduate Program, Weill Cornell Graduate School of Medical Sciences, New York, United States
| | - Jordana Thibado
- Physiology, Biophysics and Systems Biology Graduate Program, Weill Cornell Graduate School of Medical Sciences, New York, United States
| | - Daniel Starer Stor
- Physiology, Biophysics and Systems Biology Graduate Program, Weill Cornell Graduate School of Medical Sciences, New York, United States
| | - Zhou Zhou
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, United States
| | - Scott C Blanchard
- Physiology, Biophysics and Systems Biology Graduate Program, Weill Cornell Graduate School of Medical Sciences, New York, United States.,Department of Physiology and Biophysics, Weill Cornell Medicine, New York, United States.,Tri-Institutional PhD Program in Chemical Biology, New York, United States
| | - Olaf S Andersen
- Physiology, Biophysics and Systems Biology Graduate Program, Weill Cornell Graduate School of Medical Sciences, New York, United States.,Department of Physiology and Biophysics, Weill Cornell Medicine, New York, United States
| | - Joshua Levitz
- Physiology, Biophysics and Systems Biology Graduate Program, Weill Cornell Graduate School of Medical Sciences, New York, United States.,Tri-Institutional PhD Program in Chemical Biology, New York, United States.,Department of Biochemistry, Weill Cornell Medicine, New York, United States
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11
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Sun J, Huang W, Yang SF, Zhang XP, Yu Q, Zhang ZQ, Yao J, Li KR, Jiang Q, Cao C. Gαi1 and Gαi3mediate VEGF-induced VEGFR2 endocytosis, signaling and angiogenesis. Theranostics 2018; 8:4695-4709. [PMID: 30279732 PMCID: PMC6160771 DOI: 10.7150/thno.26203] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Accepted: 08/17/2018] [Indexed: 12/21/2022] Open
Abstract
VEGF binding to VEGFR2 leads to VEGFR2 endocytosis and downstream signaling activation to promote angiogenesis. Methods: Using genetic strategies, we tested the requirement of α subunits of heterotrimeric G proteins (Gαi1/3) in the process. Results: Gαi1/3 are located in the VEGFR2 endocytosis complex (VEGFR2-Ephrin-B2-Dab2-PAR-3), where they are required for VEGFR2 endocytosis and downstream signaling transduction. Gαi1/3 knockdown, knockout or dominant negative mutation inhibited VEGF-induced VEGFR2 endocytosis, and downstream Akt-mTOR and Erk-MAPK activation. Functional studies show that Gαi1/3 shRNA inhibited VEGF-induced proliferation, invasion, migration and vessel-like tube formation of HUVECs. In vivo, Gαi1/3 shRNA lentivirus inhibited alkali burn-induced neovascularization in mouse cornea. Further, oxygen-induced retinopathy (OIR)-induced retinal neovascularization was inhibited by intravitreal injection of Gαi1/3 shRNA lentivirus. Moreover, in vivo angiogenesis by alkali burn and OIR was significantly attenuated in Gαi1/3 double knockout mice. Significantly, Gαi1/3 proteins are upregulated in proliferative retinal tissues of proliferative diabetic retinopathy (PDR) patients. Conclusion: These results provide mechanistic insights into the critical role played by Gαi1/3 proteins in VEGF-induced VEGFR2 endocytosis, signaling and angiogenesis.
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12
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Movahedi K, Wiegmann R, De Vlaminck K, Van Ginderachter JA, Nikolaev VO. RoMo: An efficient strategy for functional mosaic analysis via stochastic Cre recombination and gene targeting in theROSA26locus. Biotechnol Bioeng 2018; 115:1778-1792. [DOI: 10.1002/bit.26594] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2017] [Revised: 02/20/2018] [Accepted: 03/15/2018] [Indexed: 01/03/2023]
Affiliation(s)
- Kiavash Movahedi
- Myeloid Cell Immunology Lab; VIB Center for Inflammation Research; Brussels Belgium
- Lab of Cellular and Molecular Immunology; Vrije Universiteit Brussel; Brussels Belgium
- Max Planck Institute of Biophysics; Max-von-Laue-Strasse 3; Frankfurt Germany
| | - Robert Wiegmann
- Institute of Experimental Cardiovascular Research, University Medical Hamburg-Eppendorf, DZHK (German Center for Cardiovascular Research); Partner Site Hamburg/Kiel/Lübeck; Hamburg Germany
| | - Karen De Vlaminck
- Myeloid Cell Immunology Lab; VIB Center for Inflammation Research; Brussels Belgium
- Lab of Cellular and Molecular Immunology; Vrije Universiteit Brussel; Brussels Belgium
| | - Jo A. Van Ginderachter
- Myeloid Cell Immunology Lab; VIB Center for Inflammation Research; Brussels Belgium
- Lab of Cellular and Molecular Immunology; Vrije Universiteit Brussel; Brussels Belgium
| | - Viacheslav O. Nikolaev
- Institute of Experimental Cardiovascular Research, University Medical Hamburg-Eppendorf, DZHK (German Center for Cardiovascular Research); Partner Site Hamburg/Kiel/Lübeck; Hamburg Germany
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13
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Cai S, Li Y, Bai JY, Zhang ZQ, Wang Y, Qiao YB, Zhou XZ, Yang B, Tian Y, Cao C. Gαi3 nuclear translocation causes irradiation resistance in human glioma cells. Oncotarget 2018; 8:35061-35068. [PMID: 28456783 PMCID: PMC5471034 DOI: 10.18632/oncotarget.17043] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Accepted: 03/30/2017] [Indexed: 12/27/2022] Open
Abstract
We have previously shown that Gαi3 is elevated in human glioma, mediating Akt activation and cancer cell proliferation. Here, we imply that Gαi3 could also be important for irradiation resistance. In A172 human glioma cells, Gαi3 knockdown (by targeted shRNAs) or dominant-negative mutation significantly potentiated irradiation-induced cell apoptosis. Reversely, forced over-expression of wild-type or constitutively-active Gαi3 inhibited irradiation-induced A172 cell apoptosis. Irradiation in A172 cells induced Gαi3 translocation to cell nuclei and association with local protein DNA-dependent protein kinase (DNA-PK) catalytic subunit. This association was important for DNA damage repair. Gαi3 knockdown, depletion (using Gαi3 knockout MEFs) or dominant-negative mutation potentiated irradiation-induced DNA damages. On the other hand, expression of the constitutively-active Gαi3 in A172 cells inhibited DNA damage by irradiation. Together, these results indicate a novel function of Gαi3 in irradiation-resistance in human glioma cells.
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Affiliation(s)
- Shang Cai
- Department of Radiotherapy and Oncology, The Second Affiliated Hospital of Soochow University, Suzhou, China
| | - Ya Li
- Institute of Neuroscience, Soochow University, Suzhou, China
| | - Jin-Yu Bai
- Department of Orthopedics, The Second Affiliated Hospital of Soochow University, Suzhou, China
| | - Zhi-Qing Zhang
- Institute of Neuroscience, Soochow University, Suzhou, China
| | - Yin Wang
- Institute of Neuroscience, Soochow University, Suzhou, China
| | - Yin-Biao Qiao
- Department of Surgery, The Third Hospital affiliated to Soochow University
| | - Xiao-Zhong Zhou
- Department of Orthopedics, The Second Affiliated Hospital of Soochow University, Suzhou, China
| | - Bo Yang
- Department of Surgery, The Third Hospital affiliated to Soochow University
| | - Ye Tian
- Department of Radiotherapy and Oncology, The Second Affiliated Hospital of Soochow University, Suzhou, China
| | - Cong Cao
- Institute of Neuroscience, Soochow University, Suzhou, China
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14
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Cleator JH, Wells CA, Dingus J, Kurtz DT, Hildebrandt JD. The N54- αs Mutant Has Decreased Affinity for βγ and Suggests a Mechanism for Coupling Heterotrimeric G Protein Nucleotide Exchange with Subunit Dissociation. J Pharmacol Exp Ther 2018; 365:219-225. [PMID: 29491039 DOI: 10.1124/jpet.117.245779] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Accepted: 02/23/2018] [Indexed: 11/22/2022] Open
Abstract
Ser54 of Gsα binds guanine nucleotide and Mg2+ as part of a conserved sequence motif in GTP binding proteins. Mutating the homologous residue in small and heterotrimeric G proteins generates dominant-negative proteins, but by protein-specific mechanisms. For αi/o, this results from persistent binding of α to βγ, whereas for small GTP binding proteins and αs this results from persistent binding to guanine nucleotide exchange factor or receptor. This work examined the role of βγ interactions in mediating the properties of the Ser54-like mutants of Gα subunits. Unexpectedly, WT-αs or N54-αs coexpressed with α1B-adrenergic receptor in human embryonic kidney 293 cells decreased receptor stimulation of IP3 production by a cAMP-independent mechanism, but WT-αs was more effective than the mutant. One explanation for this result would be that αs, like Ser47 αi/o, blocks receptor activation by sequestering βγ; implying that N54-αS has reduced affinity for βγ since it was less effective at blocking IP3 production. This possibility was more directly supported by the observation that WT-αs was more effective than the mutant in inhibiting βγ activation of phospholipase Cβ2. Further, in vitro synthesized N54-αs bound biotinylated-βγ with lower apparent affinity than did WT-αs The Cys54 mutation also decreased βγ binding but less effectively than N54-αs Substitution of the conserved Ser in αo with Cys or Asn increased βγ binding, with the Cys mutant being more effective. This suggests that Ser54 of αs is involved in coupling changes in nucleotide binding with altered subunit interactions, and has important implications for how receptors activate G proteins.
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Affiliation(s)
- John H Cleator
- Department of Pharmacology, Medical University of South Carolina, Charleston, South Carolina
| | - Christopher A Wells
- Department of Pharmacology, Medical University of South Carolina, Charleston, South Carolina
| | - Jane Dingus
- Department of Pharmacology, Medical University of South Carolina, Charleston, South Carolina
| | - David T Kurtz
- Department of Pharmacology, Medical University of South Carolina, Charleston, South Carolina
| | - John D Hildebrandt
- Department of Pharmacology, Medical University of South Carolina, Charleston, South Carolina
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15
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Lecat-Guillet N, Monnier C, Rovira X, Kniazeff J, Lamarque L, Zwier JM, Trinquet E, Pin JP, Rondard P. FRET-Based Sensors Unravel Activation and Allosteric Modulation of the GABA B Receptor. Cell Chem Biol 2017; 24:360-370. [PMID: 28286129 DOI: 10.1016/j.chembiol.2017.02.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Revised: 11/21/2016] [Accepted: 02/10/2017] [Indexed: 01/11/2023]
Abstract
The main inhibitory neurotransmitter, γ-aminobutyric acid (GABA), modulates many synapses by activating the G protein-coupled receptor GABAB, which is a target for various therapeutic applications. It is an obligatory heterodimer made of GB1 and GB2 that can be regulated by positive allosteric modulators (PAMs). The molecular mechanism of activation of the GABAB receptor remains poorly understood. Here, we have developed FRET-based conformational GABAB sensors compatible with high-throughput screening. We identified conformational changes occurring within the extracellular and transmembrane domains upon receptor activation, which are smaller than those observed in the related metabotropic glutamate receptors. These sensors also allow discrimination between agonists of different efficacies and between PAMs that have different modes of action, which has not always been possible using conventional functional assays. Our study brings important new information on the activation mechanism of the GABAB receptor and should facilitate the screening and identification of new chemicals targeting this receptor.
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Affiliation(s)
- Nathalie Lecat-Guillet
- Institut de Génomique Fonctionnelle (IGF), CNRS, INSERM, University of Montpellier, 141 rue de la Cardonille, 34094 Montpellier, France
| | - Carine Monnier
- Institut de Génomique Fonctionnelle (IGF), CNRS, INSERM, University of Montpellier, 141 rue de la Cardonille, 34094 Montpellier, France
| | - Xavier Rovira
- Institut de Génomique Fonctionnelle (IGF), CNRS, INSERM, University of Montpellier, 141 rue de la Cardonille, 34094 Montpellier, France
| | - Julie Kniazeff
- Institut de Génomique Fonctionnelle (IGF), CNRS, INSERM, University of Montpellier, 141 rue de la Cardonille, 34094 Montpellier, France
| | | | | | | | - Jean-Philippe Pin
- Institut de Génomique Fonctionnelle (IGF), CNRS, INSERM, University of Montpellier, 141 rue de la Cardonille, 34094 Montpellier, France
| | - Philippe Rondard
- Institut de Génomique Fonctionnelle (IGF), CNRS, INSERM, University of Montpellier, 141 rue de la Cardonille, 34094 Montpellier, France.
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16
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Li S, Wang X, Ma QH, Yang WL, Zhang XG, Dawe GS, Xiao ZC. Amyloid precursor protein modulates Nav1.6 sodium channel currents through a Go-coupled JNK pathway. Sci Rep 2016; 6:39320. [PMID: 28008944 PMCID: PMC5180232 DOI: 10.1038/srep39320] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Accepted: 11/17/2016] [Indexed: 02/08/2023] Open
Abstract
Amyloid precursor protein (APP), commonly associated with Alzheimer's disease, also marks axonal degeneration. In the recent studies, we demonstrated that APP aggregated at nodes of Ranvier (NORs) in myelinated central nervous system (CNS) axons and interacted with Nav1.6. However, the physiological function of APP remains unknown. In this study, we described reduced sodium current densities in APP knockout hippocampal neurons. Coexpression of APP or its intracellular domains containing a VTPEER motif with Nav1.6 sodium channels in Xenopus oocytes resulted in an increase in peak sodium currents, which was enhanced by constitutively active Go mutant and blocked by a dominant negative mutant. JNK and CDK5 inhibitor attenuated increases in Nav1.6 sodium currents induced by overexpression of APP. Nav1.6 sodium currents were increased by APPT668E (mutant Thr to Glu) and decreased by T668A (mutant Thr to ALa) mutant, respectively. The cell surface expression of Nav1.6 sodium channels in the white matter of spinal cord and the spinal conduction velocity is decreased in APP, p35 and JNK3 knockout mice. Therefore, APP modulates Nav1.6 sodium channels through a Go-coupled JNK pathway, which is dependent on phosphorylation of APP at Thr668.
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Affiliation(s)
- Shao Li
- Department of Physiology, Dalian Medical University, Dalian 116044, China
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University Health System, National University of Singapore, 10 Medical Drive 117597, Singapore
| | - Xi Wang
- Department of Physiology, Dalian Medical University, Dalian 116044, China
- The Key Laboratory of Stem Cell and Regenerative Medicine, Institute of Molecular and Clinical Medicine, Kunming Medical College, Kunming 650031, China
| | - Quan-Hong Ma
- Jiangsu Key Laboratory of Translational Research and Therapy for Neuro-Psycho-Diseases, Institute of Neuroscience, Second Affiliated Hospital, Soochow University, Suzhou, Jiangsu Province 215123, China
| | - Wu-lin Yang
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University Health System, National University of Singapore, 10 Medical Drive 117597, Singapore
| | - Xiao-Gang Zhang
- Department of Physiology, Dalian Medical University, Dalian 116044, China
| | - Gavin S. Dawe
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University Health System, National University of Singapore, 10 Medical Drive 117597, Singapore
- Neurobiology and Ageing Programme, Life Sciences Institute, Centre for Life Sciences, National University of Singapore, 28 Medical Drive 117456, Singapore
- Singapore Institute for Neurotechnology (SINAPSE), Centre for Life Sciences, National University of Singapore, 28 Medical Drive 117456, Singapore
| | - Zhi-Cheng Xiao
- The Key Laboratory of Stem Cell and Regenerative Medicine, Institute of Molecular and Clinical Medicine, Kunming Medical College, Kunming 650031, China
- Department of Anatomy and Developmental Biology, Monash University, Clayton, Melbourne, Victoria 3800, Australia
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17
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Liu P, Jia MZ, Zhou XE, De Waal PW, Dickson BM, Liu B, Hou L, Yin YT, Kang YY, Shi Y, Melcher K, Xu HE, Jiang Y. The structural basis of the dominant negative phenotype of the Gαi1β1γ2 G203A/A326S heterotrimer. Acta Pharmacol Sin 2016; 37:1259-72. [PMID: 27498775 PMCID: PMC5022103 DOI: 10.1038/aps.2016.69] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Accepted: 06/08/2016] [Indexed: 12/13/2022] Open
Abstract
Aim: Dominant negative mutant G proteins have provided critical insight into the mechanisms of G protein-coupled receptor (GPCR) signaling, but the mechanisms underlying the dominant negative characteristics are not completely understood. The aim of this study was to determine the structure of the dominant negative Gαi1β1γ2 G203A/A326S complex (Gi-DN) and to reveal the structural basis of the mutation-induced phenotype of Gαi1β1γ2. Methods: The three subunits of the Gi-DN complex were co-expressed with a baculovirus expression system. The Gi-DN heterotrimer was purified, and the structure of its complex with GDP was determined through X-ray crystallography. Results: The Gi-DN heterotrimer structure revealed a dual mechanism underlying the dominant negative characteristics. The mutations weakened the hydrogen bonding network between GDP/GTP and the binding pocket residues, and increased the interactions in the Gα-Gβγ interface. Concomitantly, the Gi-DN heterotrimer adopted a conformation, in which the C-terminus of Gαi and the N-termini of both the Gβ and Gγ subunits were more similar to the GPCR-bound state compared with the wild type complex. From these structural observations, two additional mutations (T48F and D272F) were designed that completely abolish the GDP binding of the Gi-DN heterotrimer. Conclusion: Overall, the results suggest that the mutations impede guanine nucleotide binding and Gα-Gβγ protein dissociation and favor the formation of the G protein/GPCR complex, thus blocking signal propagation. In addition, the structure provides a rationale for the design of other mutations that cause dominant negative effects in the G protein, as exemplified by the T48F and D272F mutations.
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18
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Marivin A, Leyme A, Parag-Sharma K, DiGiacomo V, Cheung AY, Nguyen LT, Dominguez I, Garcia-Marcos M. Dominant-negative Gα subunits are a mechanism of dysregulated heterotrimeric G protein signaling in human disease. Sci Signal 2016; 9:ra37. [PMID: 27072656 DOI: 10.1126/scisignal.aad2429] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Auriculo-condylar syndrome (ACS), a rare condition that impairs craniofacial development, is caused by mutations in a G protein-coupled receptor (GPCR) signaling pathway. In mice, disruption of signaling by the endothelin type A receptor (ET(A)R), which is mediated by the G protein (heterotrimeric guanine nucleotide-binding protein) subunit Gα(q/11) and subsequently phospholipase C (PLC), impairs neural crest cell differentiation that is required for normal craniofacial development. Some ACS patients have mutations inGNAI3, which encodes Gα(i3), but it is unknown whether this G protein has a role within the ET(A)R pathway. We used a Xenopus model of vertebrate development, in vitro biochemistry, and biosensors of G protein activity in mammalian cells to systematically characterize the phenotype and function of all known ACS-associated Gα(i3) mutants. We found that ACS-associated mutations in GNAI3 produce dominant-negative Gα(i3) mutant proteins that couple to ET(A)R but cannot bind and hydrolyze guanosine triphosphate, resulting in the prevention of endothelin-mediated activation of Gα(q/11) and PLC. Thus, ACS is caused by functionally dominant-negative mutations in a heterotrimeric G protein subunit.
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Affiliation(s)
- Arthur Marivin
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA
| | - Anthony Leyme
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA
| | - Kshitij Parag-Sharma
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA
| | - Vincent DiGiacomo
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA
| | - Anthony Y Cheung
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA
| | - Lien T Nguyen
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA
| | - Isabel Dominguez
- Department of Medicine, Boston University School of Medicine, Boston, MA 02118, USA
| | - Mikel Garcia-Marcos
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA.
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19
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Stanley RJ, Thomas GMH. Activation of G Proteins by Guanine Nucleotide Exchange Factors Relies on GTPase Activity. PLoS One 2016; 11:e0151861. [PMID: 26986850 PMCID: PMC4795700 DOI: 10.1371/journal.pone.0151861] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Accepted: 03/04/2016] [Indexed: 11/18/2022] Open
Abstract
G proteins are an important family of signalling molecules controlled by guanine nucleotide exchange and GTPase activity in what is commonly called an 'activation/inactivation cycle'. The molecular mechanism by which guanine nucleotide exchange factors (GEFs) catalyse the activation of monomeric G proteins is well-established, however the complete reversibility of this mechanism is often overlooked. Here, we use a theoretical approach to prove that GEFs are unable to positively control G protein systems at steady-state in the absence of GTPase activity. Instead, positive regulation of G proteins must be seen as a product of the competition between guanine nucleotide exchange and GTPase activity--emphasising a central role for GTPase activity beyond merely signal termination. We conclude that a more accurate description of the regulation of G proteins via these processes is as a 'balance/imbalance' mechanism. This result has implications for the understanding of intracellular signalling processes, and for experimental strategies that rely on modulating G protein systems.
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Affiliation(s)
- Rob J. Stanley
- CoMPLEX, University College London, London, United Kingdom
- Department of Cell & Developmental Biology, University College London, London, United Kingdom
| | - Geraint M. H. Thomas
- CoMPLEX, University College London, London, United Kingdom
- Department of Cell & Developmental Biology, University College London, London, United Kingdom
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20
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The experimental power of FR900359 to study Gq-regulated biological processes. Nat Commun 2015; 6:10156. [PMID: 26658454 PMCID: PMC4682109 DOI: 10.1038/ncomms10156] [Citation(s) in RCA: 259] [Impact Index Per Article: 28.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Accepted: 11/06/2015] [Indexed: 12/13/2022] Open
Abstract
Despite the discovery of heterotrimeric αβγ G proteins ∼25 years ago, their selective perturbation by cell-permeable inhibitors remains a fundamental challenge. Here we report that the plant-derived depsipeptide FR900359 (FR) is ideally suited to this task. Using a multifaceted approach we systematically characterize FR as a selective inhibitor of Gq/11/14 over all other mammalian Gα isoforms and elaborate its molecular mechanism of action. We also use FR to investigate whether inhibition of Gq proteins is an effective post-receptor strategy to target oncogenic signalling, using melanoma as a model system. FR suppresses many of the hallmark features that are central to the malignancy of melanoma cells, thereby providing new opportunities for therapeutic intervention. Just as pertussis toxin is used extensively to probe and inhibit the signalling of Gi/o proteins, we anticipate that FR will at least be its equivalent for investigating the biological relevance of Gq.
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21
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Requirement of Gαi1/3–Gab1 Signaling Complex for Keratinocyte Growth Factor–Induced PI3K–AKT–mTORC1 Activation. J Invest Dermatol 2015; 135:181-191. [DOI: 10.1038/jid.2014.326] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2014] [Revised: 06/24/2014] [Accepted: 07/14/2014] [Indexed: 01/06/2023]
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22
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Wie J, Kim J, Ha K, Zhang YH, Jeon JH, So I. Dexamethasone activates transient receptor potential canonical 4 (TRPC4) channels via Rasd1 small GTPase pathway. Pflugers Arch 2014; 467:2081-91. [PMID: 25502319 DOI: 10.1007/s00424-014-1666-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Revised: 11/24/2014] [Accepted: 12/01/2014] [Indexed: 12/15/2022]
Abstract
Canonical transient receptor potential 4 (TRPC4) channels are calcium-permeable, nonselective cation channels that are widely distributed in mammalian cells. It is generally speculated that TRPC4 channels are activated by Gq/11-PLC pathway or directly activated by Gi/o proteins. Although many mechanistic studies regarding TRPC4 have dealt with heterotrimeric G proteins, here, we first report the functional relationship between TRPC4 and small GTPase, Rasd1. Rasd1 selectively activated TRPC4 channels, and it was the only Ras protein among Ras protein family that can activate TRPC4 channels. For this to occur, it was found that certain population of functional Gαi1 and Gαi3 proteins are essential. Meanwhile, dexamethasone, a synthetic glucocorticoid and anti-inflammatory drug was known to increase messenger RNA (mRNA) level of Rasd1 in pancreatic β-cells. We have found that dexamethasone triggers TRPC4-like cationic current in INS-1 cells via increasing protein expression level of Rasd1. This relationship among dexamethasone, Rasd1, and TRPC4 could suggest a new therapeutic agent for hospitalized diabetes mellitus (DM) patients with prolonged dexamethasone prescription.
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Affiliation(s)
- Jinhong Wie
- Department of Physiology, Seoul National University College of Medicine, Seoul, 110-799, Republic of Korea
| | - Jinsung Kim
- Department of Physiology, Seoul National University College of Medicine, Seoul, 110-799, Republic of Korea.,Catholic University of Korea, College of Medicine, Seoul, 137-701, Republic of Korea
| | - Kotdaji Ha
- Department of Physiology, Seoul National University College of Medicine, Seoul, 110-799, Republic of Korea
| | - Yin Hua Zhang
- Department of Physiology, Seoul National University College of Medicine, Seoul, 110-799, Republic of Korea
| | - Ju-Hong Jeon
- Department of Physiology, Seoul National University College of Medicine, Seoul, 110-799, Republic of Korea
| | - Insuk So
- Department of Physiology, Seoul National University College of Medicine, Seoul, 110-799, Republic of Korea.
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23
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Novel variants in GNAI3 associated with auriculocondylar syndrome strengthen a common dominant negative effect. Eur J Hum Genet 2014; 23:481-5. [PMID: 25026904 DOI: 10.1038/ejhg.2014.132] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2014] [Revised: 06/03/2014] [Accepted: 06/06/2014] [Indexed: 12/21/2022] Open
Abstract
Auriculocondylar syndrome is a rare craniofacial disorder comprising core features of micrognathia, condyle dysplasia and question mark ear. Causative variants have been identified in PLCB4, GNAI3 and EDN1, which are predicted to function within the EDN1-EDNRA pathway during early pharyngeal arch patterning. To date, two GNAI3 variants in three families have been reported. Here we report three novel GNAI3 variants, one segregating with affected members in a family previously linked to 1p21.1-q23.3 and two de novo variants in simplex cases. Two variants occur in known functional motifs, the G1 and G4 boxes, and the third variant is one amino acid outside of the G1 box. Structural modeling shows that all five altered GNAI3 residues identified to date cluster in a region involved in GDP/GTP binding. We hypothesize that all GNAI3 variants lead to dominant negative effects.
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Balakumar P, Jagadeesh G. A century old renin-angiotensin system still grows with endless possibilities: AT1 receptor signaling cascades in cardiovascular physiopathology. Cell Signal 2014; 26:2147-60. [PMID: 25007996 DOI: 10.1016/j.cellsig.2014.06.011] [Citation(s) in RCA: 128] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2014] [Accepted: 06/27/2014] [Indexed: 12/25/2022]
Abstract
Ang II, the primary effector pleiotropic hormone of the renin-angiotensin system (RAS) cascade, mediates physiological control of blood pressure and electrolyte balance through its action on vascular tone, aldosterone secretion, renal sodium absorption, water intake, sympathetic activity and vasopressin release. It affects the function of most of the organs far beyond blood pressure control including heart, blood vessels, kidney and brain, thus, causing both beneficial and deleterious effects. However, the protective axis of the RAS composed of ACE2, Ang (1-7), alamandine, and Mas and MargD receptors might oppose some harmful effects of Ang II and might promote beneficial cardiovascular effects. Newly identified RAS family peptides, Ang A and angioprotectin, further extend the complexities in understanding the cardiovascular physiopathology of RAS. Most of the diverse actions of Ang II are mediated by AT1 receptors, which couple to classical Gq/11 protein and activate multiple downstream signals, including PKC, ERK1/2, Raf, tyrosine kinases, receptor tyrosine kinases (EGFR, PDGF, insulin receptor), nuclear factor κB and reactive oxygen species (ROS). Receptor activation via G12/13 stimulates Rho-kinase, which causes vascular contraction and hypertrophy. The AT1 receptor activation also stimulates G protein-independent signaling pathways such as β-arrestin-mediated MAPK activation and Src-JAK/STAT. AT1 receptor-mediated activation of NADPH oxidase releases ROS, resulting in the activation of pro-inflammatory transcription factors and stimulation of small G proteins such as Ras, Rac and RhoA. The components of the RAS and the major Ang II-induced signaling cascades of AT1 receptors are reviewed.
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Affiliation(s)
- Pitchai Balakumar
- Pharmacology Unit, Faculty of Pharmacy, AIMST University, Semeling, 08100 Bedong, Kedah Darul Aman, Malaysia.
| | - Gowraganahalli Jagadeesh
- Division of Cardiovascular and Renal Products, Center for Drug Evaluation and Research, US Food and Drug Administration, Silver Spring, MD 20993, USA.
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Moreira IS. Structural features of the G-protein/GPCR interactions. Biochim Biophys Acta Gen Subj 2013; 1840:16-33. [PMID: 24016604 DOI: 10.1016/j.bbagen.2013.08.027] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Revised: 08/27/2013] [Accepted: 08/28/2013] [Indexed: 01/07/2023]
Abstract
BACKGROUND The details of the functional interaction between G proteins and the G protein coupled receptors (GPCRs) have long been subjected to extensive investigations with structural and functional assays and a large number of computational studies. SCOPE OF REVIEW The nature and sites of interaction in the G-protein/GPCR complexes, and the specificities of these interactions selecting coupling partners among the large number of families of GPCRs and G protein forms, are still poorly defined. MAJOR CONCLUSIONS Many of the contact sites between the two proteins in specific complexes have been identified, but the three dimensional molecular architecture of a receptor-Gα interface is only known for one pair. Consequently, many fundamental questions regarding this macromolecular assembly and its mechanism remain unanswered. GENERAL SIGNIFICANCE In the context of current structural data we review the structural details of the interfaces and recognition sites in complexes of sub-family A GPCRs with cognate G-proteins, with special emphasis on the consequences of activation on GPCR structure, the prevalence of preassembled GPCR/G-protein complexes, the key structural determinants for selective coupling and the possible involvement of GPCR oligomerization in this process.
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Affiliation(s)
- Irina S Moreira
- REQUIMTE/Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre s/n, 4169-007 Porto, Portugal.
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Illuminating the activation mechanisms and allosteric properties of metabotropic glutamate receptors. Proc Natl Acad Sci U S A 2013; 110:E1416-25. [PMID: 23487753 DOI: 10.1073/pnas.1215615110] [Citation(s) in RCA: 93] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In multimeric cell-surface receptors, the conformational changes of the extracellular ligand-binding domains (ECDs) associated with receptor activation remain largely unknown. This is the case for the dimeric metabotropic glutamate receptors even though a number of ECD structures have been solved. Here, using an innovative approach based on cell-surface labeling and FRET, we demonstrate that a reorientation of the ECDs is associated with receptor and G-protein activation. Our approach helps identify partial agonists and highlights allosteric interactions between the effector and binding domains. Any approach expected to stabilize the active conformation of the effector domain increased the agonist potency in stabilizing the active ECDs conformation. These data provide key information on the structural dynamics and drug action at metabotropic glutamate receptors and validate an approach for tackling such analysis on other receptors.
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Abstract
The classical genetic approach for exploring biological pathways typically begins by identifying mutations that cause a phenotype of interest. Overexpression or misexpression of a wild-type gene product, however, can also cause mutant phenotypes, providing geneticists with an alternative yet powerful tool to identify pathway components that might remain undetected using traditional loss-of-function analysis. This review describes the history of overexpression, the mechanisms that are responsible for overexpression phenotypes, tests that begin to distinguish between those mechanisms, the varied ways in which overexpression is used, the methods and reagents available in several organisms, and the relevance of overexpression to human disease.
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Heo JB, Sung S, Assmann SM. Ca2+-dependent GTPase, extra-large G protein 2 (XLG2), promotes activation of DNA-binding protein related to vernalization 1 (RTV1), leading to activation of floral integrator genes and early flowering in Arabidopsis. J Biol Chem 2012; 287:8242-53. [PMID: 22232549 DOI: 10.1074/jbc.m111.317412] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Heterotrimeric G proteins, consisting of Gα, Gβ, and Gγ subunits, play important roles in plant development and cell signaling. In Arabidopsis, in addition to one prototypical G protein α subunit, GPA1, there are three extra-large G proteins, XLG1, XLG2, and XLG3, of largely unknown function. Each extra-large G (XLG) protein has a C-terminal Gα-like region and a ∼400 amino acid N-terminal extension. Here we show that the three XLG proteins specifically bind and hydrolyze GTP, despite the fact that these plant-specific proteins lack key conserved amino acid residues important for GTP binding and hydrolysis of GTP in mammalian Gα proteins. Moreover, unlike other known Gα proteins, these activities require Ca(2+) instead of Mg(2+) as a cofactor. Yeast two-hybrid library screening and in vitro protein pull-down assays revealed that XLG2 interacts with the nuclear protein RTV1 (related to vernalization 1). Electrophoretic mobility shift assays show that RTV1 binds to DNA in vitro in a non-sequence-specific manner and that GTP-bound XLG2 promotes the DNA binding activity of RTV1. Overexpression of RTV1 results in early flowering. Combined overexpression of XLG2 and RTV1 enhances this early flowering phenotype and elevates expression of the floral pathway integrator genes, FT and SOC1, but does not repress expression of the floral repressor, FLC. Chromatin immunoprecipitation assays show that XLG2 increases RTV1 binding to FT and SOC1 promoters. Thus, a Ca(2+)-dependent G protein, XLG2, promotes RTV1 DNA binding activity for a subset of floral integrator genes and contributes to floral transition.
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Affiliation(s)
- Jae Bok Heo
- Department of Biology, Penn State University, University Park, Pennsylvania 16802, USA
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Tadevosyan A, Vaniotis G, Allen BG, Hébert TE, Nattel S. G protein-coupled receptor signalling in the cardiac nuclear membrane: evidence and possible roles in physiological and pathophysiological function. J Physiol 2011; 590:1313-30. [PMID: 22183719 DOI: 10.1113/jphysiol.2011.222794] [Citation(s) in RCA: 108] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
G protein-coupled receptors (GPCRs) play key physiological roles in numerous tissues, including the heart, and their dysfunction influences a wide range of cardiovascular diseases. Recently, the notion of nuclear localization and action of GPCRs has become more widely accepted. Nuclear-localized receptors may regulate distinct signalling pathways, suggesting that the biological responses mediated by GPCRs are not solely initiated at the cell surface but may result from the integration of extracellular and intracellular signalling pathways. Many of the observed nuclear effects are not prevented by classical inhibitors that exclusively target cell surface receptors, presumably because of their structures, lipophilic properties, or affinity for nuclear receptors. In this topical review, we discuss specifically how angiotensin-II, endothelin, β-adrenergic and opioid receptors located on the nuclear envelope activate signalling pathways, which convert intracrine stimuli into acute responses such as generation of second messengers and direct genomic effects, and thereby participate in the development of cardiovascular disorders.
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Affiliation(s)
- Artavazd Tadevosyan
- Department of Medicine, Université de Montréal, Montréal, Québec, Canada H3C 3J7
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Mühlbach H, Mohr CA, Ruzsics Z, Koszinowski UH. Dominant-negative proteins in herpesviruses - from assigning gene function to intracellular immunization. Viruses 2009; 1:420-40. [PMID: 21994555 PMCID: PMC3185506 DOI: 10.3390/v1030420] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2009] [Revised: 10/19/2009] [Accepted: 10/19/2009] [Indexed: 11/17/2022] Open
Abstract
Investigating and assigning gene functions of herpesviruses is a process, which profits from consistent technical innovation. Cloning of bacterial artificial chromosomes encoding herpesvirus genomes permits nearly unlimited possibilities in the construction of genetically modified viruses. Targeted or randomized screening approaches allow rapid identification of essential viral proteins. Nevertheless, mapping of essential genes reveals only limited insight into function. The usage of dominant-negative (DN) proteins has been the tool of choice to dissect functions of proteins during the viral life cycle. DN proteins also facilitate the analysis of host-virus interactions. Finally, DNs serve as starting-point for design of new antiviral strategies.
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Affiliation(s)
| | | | - Zsolt Ruzsics
- Max-von-Pettenkofer Institut, LMU, Feodor-Lynenstr. 25, 81377 Munich, Germany; E-Mails: (H.M.); (C.A.M.); (Z.R.)
| | - Ulrich H. Koszinowski
- Max-von-Pettenkofer Institut, LMU, Feodor-Lynenstr. 25, 81377 Munich, Germany; E-Mails: (H.M.); (C.A.M.); (Z.R.)
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Cao C, Huang X, Han Y, Wan Y, Birnbaumer L, Feng GS, Marshall J, Jiang M, Chu WM. Galpha(i1) and Galpha(i3) are required for epidermal growth factor-mediated activation of the Akt-mTORC1 pathway. Sci Signal 2009; 2:ra17. [PMID: 19401591 DOI: 10.1126/scisignal.2000118] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The precise mechanism whereby epidermal growth factor (EGF) activates the serine-threonine kinase Akt and the mammalian target of rapamycin (mTOR) complex 1 (mTORC1) remains elusive. Here, we report that the alpha subunits of the heterotrimeric guanine nucleotide-binding proteins (G proteins) Galpha(i1) and Galpha(i3) are critical for this activation process. Both Galpha(i1) and Galpha(i3) formed complexes with growth factor receptor binding 2 (Grb2)-associated binding protein 1 (Gab1) and the EGF receptor (EGFR) and were required for the phosphorylation of Gab1 and its subsequent interaction with the p85 subunit of phosphatidylinositol 3-kinase in response to EGF. Loss of Galpha(i1) and Galpha(i3) severely impaired the activation of Akt and of p70 S6 kinase and 4E-BP1, downstream targets of mTORC1, in response to EGF, heparin-binding EGF-like growth factor, and transforming growth factor alpha, but not insulin, insulin-like growth factor, or platelet-derived growth factor. In addition, ablation of Galpha(i1) and Galpha(i3) largely inhibited EGF-induced cell growth, migration, and survival and the accumulation of cyclin D1. Overall, this study suggests that Galpha(i1) and Galpha(i3) lie downstream of EGFR, but upstream of Gab1-mediated activation of Akt and mTORC1, thus revealing a role for Galpha(i) proteins in mediating EGFR signaling.
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Affiliation(s)
- Cong Cao
- Department of Molecular Microbiology and Immunology, Brown University, Providence, RI 02912, USA
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Preuß I, Kurig B, Nürnberg B, Orth JH, Aktories K. Pasteurella multocida toxin activates Gβγ dimers of heterotrimeric G proteins. Cell Signal 2009; 21:551-8. [DOI: 10.1016/j.cellsig.2008.12.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2008] [Revised: 12/12/2008] [Accepted: 12/15/2008] [Indexed: 10/21/2022]
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Veitia RA. Exploring the molecular etiology of dominant-negative mutations. THE PLANT CELL 2007; 19:3843-51. [PMID: 18083908 PMCID: PMC2217636 DOI: 10.1105/tpc.107.055053] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Affiliation(s)
- Reiner A Veitia
- Université Denis Diderot/Paris VII (Unité de Formation et de Recherche/Department of Biology), 75005 Paris, France.
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