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Rysiewicz B, Błasiak E, Dziedzicka-Wasylewska M, Polit A. The polybasic region in Gαi proteins: Relevant or not? Insights from Gαi 3 research. Cell Signal 2024; 118:111138. [PMID: 38467243 DOI: 10.1016/j.cellsig.2024.111138] [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: 09/25/2023] [Revised: 02/18/2024] [Accepted: 03/08/2024] [Indexed: 03/13/2024]
Abstract
Heterotrimeric G proteins are responsible for signal transduction from G-protein-coupled receptors (GPCRs) to intracellular effectors. This process is only possible when G proteins are located on the inner side of the cell membrane due to the specific localization of GPCR receptors. The Gα subunit is directed to the cell membrane through several signals, including modification by fatty acid moieties, interaction with the Gβγ complex, and, as observed in some Gα proteins, the presence of basic amino acid residues in the N-terminal region. In this work, we focused on investigating the influence of the polybasic region on the localization and function of a representative member of the Gαi family, Gαi3. Through the use of confocal microscopy and fluorescence lifetime microscopy, we showed that, in the case of this protein, neutralizing the positive charge does not significantly affect its abundance in the cell membrane. However, it does affect its spatial arrangement concerning the dopamine D2 receptor and influences inhibitory effect of Gαi3 on intracellular cAMP production triggered by D2 receptor stimulation. Moreover, in this work, we have shown, for the first time, that nonlipidated Gαi3 binds to negatively charged lipids through electrostatic interactions, and membrane fluidity plays a significant role in this interaction.
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Affiliation(s)
- Beata Rysiewicz
- Department of Physical Biochemistry, Faculty of Biochemistry Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387 Kraków, Poland.
| | - Ewa Błasiak
- Department of Physical Biochemistry, Faculty of Biochemistry Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387 Kraków, Poland.
| | - Marta Dziedzicka-Wasylewska
- Department of Physical Biochemistry, Faculty of Biochemistry Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387 Kraków, Poland.
| | - Agnieszka Polit
- Department of Physical Biochemistry, Faculty of Biochemistry Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387 Kraków, Poland.
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Jang W, Senarath K, Lu S, Lambert NA. Visualization of endogenous G proteins on endosomes and other organelles. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.05.583500. [PMID: 38496652 PMCID: PMC10942389 DOI: 10.1101/2024.03.05.583500] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/19/2024]
Abstract
Classical G protein-coupled receptor (GPCR) signaling takes place in response to extracellular stimuli and involves receptors and heterotrimeric G proteins located at the plasma membrane. It has recently been established that GPCR signaling can also take place from intracellular membrane compartments, including endosomes that contain internalized receptors and ligands. While the mechanisms of GPCR endocytosis are well understood, it is not clear how internalized receptors are supplied with G proteins. To address this gap we use gene editing, confocal microscopy, and bioluminescence resonance energy transfer to study the distribution and trafficking of endogenous G proteins. We show here that constitutive endocytosis is sufficient to supply newly internalized endocytic vesicles with 20-30% of the G protein density found at the plasma membrane. We find that G proteins are present on early, late, and recycling endosomes, are abundant on lysosomes, but are virtually undetectable on the endoplasmic reticulum, mitochondria, and the medial Golgi apparatus. Receptor activation does not change heterotrimer abundance on endosomes. Our results provide a detailed subcellular map of endogenous G protein distribution, suggest that G proteins may be partially excluded from nascent endocytic vesicles, and are likely to have implications for GPCR signaling from endosomes and other intracellular compartments.
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Affiliation(s)
- Wonjo Jang
- Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, Augusta, GA, 30912, USA
| | - Kanishka Senarath
- Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, Augusta, GA, 30912, USA
| | - Sumin Lu
- Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, Augusta, GA, 30912, USA
| | - Nevin A Lambert
- Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, Augusta, GA, 30912, USA
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Köck Z, Schnelle K, Persechino M, Umbach S, Schihada H, Januliene D, Parey K, Pockes S, Kolb P, Dötsch V, Möller A, Hilger D, Bernhard F. Cryo-EM structure of cell-free synthesized human histamine 2 receptor/G s complex in nanodisc environment. Nat Commun 2024; 15:1831. [PMID: 38418462 PMCID: PMC10901899 DOI: 10.1038/s41467-024-46096-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Accepted: 02/14/2024] [Indexed: 03/01/2024] Open
Abstract
Here we describe the cryo-electron microscopy structure of the human histamine 2 receptor (H2R) in an active conformation with bound histamine and in complex with Gs heterotrimeric protein at an overall resolution of 3.4 Å. The complex was generated by cotranslational insertion of the receptor into preformed nanodisc membranes using cell-free synthesis in E. coli lysates. Structural comparison with the inactive conformation of H2R and the inactive and Gq-coupled active state of H1R together with structure-guided functional experiments reveal molecular insights into the specificity of ligand binding and G protein coupling for this receptor family. We demonstrate lipid-modulated folding of cell-free synthesized H2R, its agonist-dependent internalization and its interaction with endogenously synthesized H1R and H2R in HEK293 cells by applying a recently developed nanotransfer technique.
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Affiliation(s)
- Zoe Köck
- Centre for Biomolecular Magnetic Resonance, Institute for Biophysical Chemistry, Goethe-University of Frankfurt/Main, Frankfurt, Germany
| | - Kilian Schnelle
- Department of Biology/Chemistry, Structural Biology section, University of Osnabrück, Osnabrück, Germany
- Center of Cellular Nanoanalytic Osnabrück (CellNanOs), University of Osnabrück, Osnabrück, Germany
| | | | - Simon Umbach
- Centre for Biomolecular Magnetic Resonance, Institute for Biophysical Chemistry, Goethe-University of Frankfurt/Main, Frankfurt, Germany
| | - Hannes Schihada
- Department of Pharmaceutical Chemistry, University of Marburg, Marburg, Germany
| | - Dovile Januliene
- Department of Biology/Chemistry, Structural Biology section, University of Osnabrück, Osnabrück, Germany
- Center of Cellular Nanoanalytic Osnabrück (CellNanOs), University of Osnabrück, Osnabrück, Germany
| | - Kristian Parey
- Department of Biology/Chemistry, Structural Biology section, University of Osnabrück, Osnabrück, Germany
- Center of Cellular Nanoanalytic Osnabrück (CellNanOs), University of Osnabrück, Osnabrück, Germany
| | - Steffen Pockes
- Institute of Pharmacy, University of Regensburg, Regensburg, Germany
| | - Peter Kolb
- Department of Pharmaceutical Chemistry, University of Marburg, Marburg, Germany
| | - Volker Dötsch
- Centre for Biomolecular Magnetic Resonance, Institute for Biophysical Chemistry, Goethe-University of Frankfurt/Main, Frankfurt, Germany
| | - Arne Möller
- Department of Biology/Chemistry, Structural Biology section, University of Osnabrück, Osnabrück, Germany.
- Center of Cellular Nanoanalytic Osnabrück (CellNanOs), University of Osnabrück, Osnabrück, Germany.
| | - Daniel Hilger
- Department of Pharmaceutical Chemistry, University of Marburg, Marburg, Germany.
| | - Frank Bernhard
- Centre for Biomolecular Magnetic Resonance, Institute for Biophysical Chemistry, Goethe-University of Frankfurt/Main, Frankfurt, Germany.
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Rysiewicz B, Błasiak E, Mystek P, Dziedzicka-Wasylewska M, Polit A. Beyond the G protein α subunit: investigating the functional impact of other components of the Gαi 3 heterotrimers. Cell Commun Signal 2023; 21:279. [PMID: 37817242 PMCID: PMC10566112 DOI: 10.1186/s12964-023-01307-w] [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: 06/16/2023] [Accepted: 09/05/2023] [Indexed: 10/12/2023] Open
Abstract
BACKGROUND Specific interactions between G protein-coupled receptors (GPCRs) and G proteins play a key role in mediating signaling events. While there is little doubt regarding receptor preference for Gα subunits, the preferences for specific Gβ and Gγ subunits and the effects of different Gβγ dimer compositions on GPCR signaling are poorly understood. In this study, we aimed to investigate the subcellular localization and functional response of Gαi3-based heterotrimers with different combinations of Gβ and Gγ subunits. METHODS Live-cell imaging microscopy and colocalization analysis were used to investigate the subcellular localization of Gαi3 in combination with Gβ1 or Gβ2 heterotrimers, along with representative Gγ subunits. Furthermore, fluorescence lifetime imaging microscopy (FLIM-FRET) was used to investigate the nanoscale distribution of Gαi3-based heterotrimers in the plasma membrane, specifically with the dopamine D2 receptor (D2R). In addition, the functional response of the system was assessed by monitoring intracellular cAMP levels and conducting bioinformatics analysis to further characterize the heterotrimer complexes. RESULTS Our results show that Gαi3 heterotrimers mainly localize to the plasma membrane, although the degree of colocalization is influenced by the accompanying Gβ and Gγ subunits. Heterotrimers containing Gβ2 showed slightly lower membrane localization compared to those containing Gβ1, but certain combinations, such as Gαi3β2γ8 and Gαi3β2γ10, deviated from this trend. Examination of the spatial arrangement of Gαi3 in relation to D2R and of changes in intracellular cAMP level showed that the strongest functional response is observed for those trimers for which the distance between the receptor and the Gα subunit is smallest, i.e. complexes containing Gβ1 and Gγ8 or Gγ10 subunit. Deprivation of Gαi3 lipid modifications resulted in a significant decrease in the amount of protein present in the cell membrane, but did not always affect intracellular cAMP levels. CONCLUSION Our studies show that the composition of G protein heterotrimers has a significant impact on the strength and specificity of GPCR-mediated signaling. Different heterotrimers may exhibit different conformations, which further affects the interactions of heterotrimers and GPCRs, as well as their interactions with membrane lipids. This study contributes to the understanding of the complex signaling mechanisms underlying GPCR-G-protein interactions and highlights the importance of the diversity of Gβ and Gγ subunits in G-protein signaling pathways. Video Abstract.
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Affiliation(s)
- Beata Rysiewicz
- Department of Physical Biochemistry, Faculty of Biochemistry Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387, Kraków, Poland
| | - Ewa Błasiak
- Department of Physical Biochemistry, Faculty of Biochemistry Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387, Kraków, Poland
| | - Paweł Mystek
- Department of Physical Biochemistry, Faculty of Biochemistry Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387, Kraków, Poland
| | - Marta Dziedzicka-Wasylewska
- Department of Physical Biochemistry, Faculty of Biochemistry Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387, Kraków, Poland
| | - Agnieszka Polit
- Department of Physical Biochemistry, Faculty of Biochemistry Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387, Kraków, Poland.
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Tyagi S, Sarveswaran N, Higerd-Rusli GP, Liu S, Dib-Hajj FB, Waxman SG, Dib-Hajj SD. Conserved but not critical: Trafficking and function of NaV1.7 are independent of highly conserved polybasic motifs. Front Mol Neurosci 2023; 16:1161028. [PMID: 37008789 PMCID: PMC10060856 DOI: 10.3389/fnmol.2023.1161028] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Accepted: 03/02/2023] [Indexed: 03/18/2023] Open
Abstract
Non-addictive treatment of chronic pain represents a major unmet clinical need. Peripheral voltage-gated sodium (NaV) channels are an attractive target for pain therapy because they initiate and propagate action potentials in primary afferents that detect and transduce noxious stimuli. NaV1.7 sets the gain on peripheral pain-signaling neurons and is the best validated peripheral ion channel involved in human pain, and previous work has shown that it is transported in vesicles in sensory axons which also carry Rab6a, a small GTPase known to be involved in vesicular packaging and axonal transport. Understanding the mechanism of the association between Rab6a and NaV1.7 could inform therapeutic modalities to decrease trafficking of NaV1.7 to the distal axonal membrane. Polybasic motifs (PBM) have been shown to regulate Rab-protein interactions in a variety of contexts. In this study, we explored whether two PBMs in the cytoplasmic loop that joins domains I and II of human NaV1.7 were responsible for association with Rab6a and regulate axonal trafficking of the channel. Using site-directed mutagenesis we generated NaV1.7 constructs with alanine substitutions in the two PBMs. Voltage-clamp recordings showed that the constructs retain wild-type like gating properties. Optical Pulse-chase Axonal Long-distance (OPAL) imaging in live sensory axons shows that mutations of these PBMs do not affect co-trafficking of Rab6a and NaV1.7, or the accumulation of the channel at the distal axonal surface. Thus, these polybasic motifs are not required for interaction of NaV1.7 with the Rab6a GTPase, or for trafficking of the channel to the plasma membrane.
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Affiliation(s)
- Sidharth Tyagi
- Medical Scientist Training Program, Yale School of Medicine, New Haven, CT, United States
- Center for Neuroscience and Regeneration Research, West Haven, CT, United States
- Department of Neurology, Yale School of Medicine, New Haven, CT, United States
- Center for Restoration of Nervous System Function, VA Connecticut Healthcare System, West Haven, CT, United States
| | - Nivedita Sarveswaran
- Center for Neuroscience and Regeneration Research, West Haven, CT, United States
- Department of Neurology, Yale School of Medicine, New Haven, CT, United States
- Center for Restoration of Nervous System Function, VA Connecticut Healthcare System, West Haven, CT, United States
| | - Grant P. Higerd-Rusli
- Medical Scientist Training Program, Yale School of Medicine, New Haven, CT, United States
- Center for Neuroscience and Regeneration Research, West Haven, CT, United States
- Department of Neurology, Yale School of Medicine, New Haven, CT, United States
- Center for Restoration of Nervous System Function, VA Connecticut Healthcare System, West Haven, CT, United States
| | - Shujun Liu
- Center for Neuroscience and Regeneration Research, West Haven, CT, United States
- Department of Neurology, Yale School of Medicine, New Haven, CT, United States
- Center for Restoration of Nervous System Function, VA Connecticut Healthcare System, West Haven, CT, United States
| | - Fadia B. Dib-Hajj
- Center for Neuroscience and Regeneration Research, West Haven, CT, United States
- Department of Neurology, Yale School of Medicine, New Haven, CT, United States
- Center for Restoration of Nervous System Function, VA Connecticut Healthcare System, West Haven, CT, United States
| | - Stephen G. Waxman
- Center for Neuroscience and Regeneration Research, West Haven, CT, United States
- Department of Neurology, Yale School of Medicine, New Haven, CT, United States
- Center for Restoration of Nervous System Function, VA Connecticut Healthcare System, West Haven, CT, United States
- *Correspondence: Stephen G. Waxman,
| | - Sulayman D. Dib-Hajj
- Center for Neuroscience and Regeneration Research, West Haven, CT, United States
- Department of Neurology, Yale School of Medicine, New Haven, CT, United States
- Center for Restoration of Nervous System Function, VA Connecticut Healthcare System, West Haven, CT, United States
- Sulayman D. Dib-Hajj,
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6
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Randolph CE, Dwyer MB, Aumiller JL, Dixon AJ, Inoue A, Osei-Owusu P, Wedegaertner PB. Enhanced membrane binding of oncogenic G protein αqQ209L confers resistance to inhibitor YM-254890. J Biol Chem 2022; 298:102538. [PMID: 36174676 PMCID: PMC9626947 DOI: 10.1016/j.jbc.2022.102538] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 09/15/2022] [Accepted: 09/18/2022] [Indexed: 11/29/2022] Open
Abstract
Heterotrimeric G proteins couple activated G protein–coupled receptors (GPCRs) to intracellular signaling pathways. They can also function independently of GPCR activation upon acquiring mutations that prevent GTPase activity and result in constitutive signaling, as occurs with the αqQ209L mutation in uveal melanoma. YM-254890 (YM) can inhibit signaling by both GPCR-activated WT αq and GPCR-independent αqQ209L. Although YM inhibits WT αq by binding to αq-GDP and preventing GDP/GTP exchange, the mechanism of YM inhibition of cellular αqQ209L remains to be fully understood. Here, we show that YM promotes a subcellular redistribution of αqQ209L from the plasma membrane (PM) to the cytoplasm. To test if this loss of PM localization could contribute to the mechanism of inhibition of αqQ209L by YM, we developed and examined N-terminal mutants of αqQ209L, termed PM-restricted αqQ209L, in which the addition of membrane-binding motifs enhanced PM localization and prevented YM-promoted redistribution. Treatment of cells with YM failed to inhibit signaling by these PM-restricted αqQ209L. Additionally, pull-down experiments demonstrated that YM promotes similar conformational changes in both αqQ209L and PM-restricted αqQ209L, resulting in increased binding to βγ and decreased binding to regulator RGS2, and effectors p63RhoGEF-DH/PH and phospholipase C-β. GPCR-dependent signaling by PM-restricted WT αq is strongly inhibited by YM, demonstrating that resistance to YM inhibition by membrane-binding mutants is specific to constitutively active αqQ209L. Together, these results indicate that changes in membrane binding impact the ability of YM to inhibit αqQ209L and suggest that YM contributes to inhibition of αqQ209L by promoting its relocalization.
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Affiliation(s)
- Clinita E Randolph
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA
| | - Morgan B Dwyer
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA
| | - Jenna L Aumiller
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA
| | - Alethia J Dixon
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, OH
| | - Asuka Inoue
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan
| | - Patrick Osei-Owusu
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, OH
| | - Philip B Wedegaertner
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA.
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Li L, Zhang J, Sun W, Gong W, Tian C, Shi P, Shi C. Allosteric conformational changes of G proteins upon its interaction with membrane and GPCR. CHINESE CHEM LETT 2022. [DOI: 10.1016/j.cclet.2021.07.042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Polit A, Mystek P, Błasiak E. Every Detail Matters. That Is, How the Interaction between Gα Proteins and Membrane Affects Their Function. MEMBRANES 2021; 11:222. [PMID: 33804791 PMCID: PMC8003949 DOI: 10.3390/membranes11030222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Revised: 03/17/2021] [Accepted: 03/18/2021] [Indexed: 11/16/2022]
Abstract
In highly organized multicellular organisms such as humans, the functions of an individual cell are dependent on signal transduction through G protein-coupled receptors (GPCRs) and subsequently heterotrimeric G proteins. As most of the elements belonging to the signal transduction system are bound to lipid membranes, researchers are showing increasing interest in studying the accompanying protein-lipid interactions, which have been demonstrated to not only provide the environment but also regulate proper and efficient signal transduction. The mode of interaction between the cell membrane and G proteins is well known. Despite this, the recognition mechanisms at the molecular level and how the individual G protein-membrane attachment signals are interrelated in the process of the complex control of membrane targeting of G proteins remain unelucidated. This review focuses on the mechanisms by which mammalian Gα subunits of G proteins interact with lipids and the factors responsible for the specificity of membrane association. We summarize recent data on how these signaling proteins are precisely targeted to a specific site in the membrane region by introducing well-defined modifications as well as through the presence of polybasic regions within these proteins and interactions with other components of the heterocomplex.
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Affiliation(s)
- Agnieszka Polit
- Department of Physical Biochemistry, Faculty of Biochemistry Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387 Kraków, Poland; (P.M.); (E.B.)
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Lavington S, Watts A. Lipid nanoparticle technologies for the study of G protein-coupled receptors in lipid environments. Biophys Rev 2020; 12:10.1007/s12551-020-00775-5. [PMID: 33215301 PMCID: PMC7755959 DOI: 10.1007/s12551-020-00775-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Accepted: 11/06/2020] [Indexed: 12/12/2022] Open
Abstract
G protein-coupled receptors (GPCRs) are a large family of integral membrane proteins which conduct a wide range of biological roles and represent significant drug targets. Most biophysical and structural studies of GPCRs have been conducted on detergent-solubilised receptors, and it is clear that detergents can have detrimental effects on GPCR function. Simultaneously, there is increasing appreciation of roles for specific lipids in modulation of GPCR function. Lipid nanoparticles such as nanodiscs and styrene maleic acid lipid particles (SMALPs) offer opportunities to study integral membrane proteins in lipid environments, in a form that is soluble and amenable to structural and biophysical experiments. Here, we review the application of lipid nanoparticle technologies to the study of GPCRs, assessing the relative merits and limitations of each system. We highlight how these technologies can provide superior platforms to detergents for structural and biophysical studies of GPCRs and inform on roles for protein-lipid interactions in GPCR function.
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Affiliation(s)
- Steven Lavington
- Biochemistry Department, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
| | - Anthony Watts
- Biochemistry Department, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK.
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PtdIns4P-mediated electrostatic forces influence S-acylation of peripheral proteins at the Golgi complex. Biosci Rep 2020; 40:221643. [PMID: 31854448 PMCID: PMC6944663 DOI: 10.1042/bsr20192911] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Revised: 12/16/2019] [Accepted: 12/17/2019] [Indexed: 11/25/2022] Open
Abstract
Protein S-acylation is a reversible post-translational modification involving the addition of fatty acids to cysteines and is catalyzed by transmembrane protein acyltransferases (PATs) mainly expressed at the Golgi complex. In case of soluble proteins, S-acylation confers stable membrane attachment. Myristoylation or farnesylation of many soluble proteins constitutes the initial transient membrane adsorption step prior to S-acylation. However, some S-acylated soluble proteins, such as the neuronal growth-associated protein Growth-associated protein-43 (GAP-43), lack the hydrophobic modifications required for this initial membrane interaction. The signals for GAP-43 S-acylation are confined to the first 13 amino acids, including the S-acylatable cysteines 3 and 4 embedded in a hydrophobic region, followed by a cluster of basic amino acids. We found that mutation of critical basic amino acids drastically reduced membrane interaction and hence S-acylation of GAP-43. Interestingly, acute depletion of phosphatidylinositol 4-phosphate (PtdIns4P) at the Golgi complex reduced GAP-43 membrane binding, highlighting a new, pivotal role for this anionic lipid and supporting the idea that basic amino acid residues are involved in the electrostatic interactions between GAP-43 and membranes of the Golgi complex where they are S-acylated.
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11
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Mystek P, Rysiewicz B, Gregrowicz J, Dziedzicka-Wasylewska M, Polit A. Gγ and Gα Identity Dictate a G-Protein Heterotrimer Plasma Membrane Targeting. Cells 2019; 8:E1246. [PMID: 31614907 PMCID: PMC6829862 DOI: 10.3390/cells8101246] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Revised: 10/10/2019] [Accepted: 10/11/2019] [Indexed: 12/18/2022] Open
Abstract
Heterotrimeric G-proteins along with G-protein-coupled receptors (GPCRs) regulate many biochemical functions by relaying the information from the plasma membrane to the inside of the cell. The lipid modifications of Gα and Gγ subunits, together with the charged regions on the membrane interaction surface, provide a peculiar pattern for various heterotrimeric complexes. In a previous study, we found that Gαs and Gαi3 prefer different types of membrane-anchor and subclass-specific lipid domains. In the present report, we examine the role of distinct Gγ subunits in the membrane localization and spatiotemporal dynamics of Gαs and Gαi3 heterotrimers. We characterized lateral diffusion and G-protein subunit interactions in living cells using fluorescence recovery after photobleaching (FRAP) microscopy and fluorescence resonance energy transfer (FRET) detected by fluorescence lifetime imaging microscopy (FLIM), respectively. The interaction of Gγ subunits with specific lipids was confirmed, and thus the modulation of heterotrimeric G-protein localization. However, the Gα subunit also modulates trimer localization, and so the membrane distribution of heterotrimeric G-proteins is not dependent on Gγ only.
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Affiliation(s)
- Paweł Mystek
- Department of Physical Biochemistry, Faculty of Biochemistry Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387 Kraków, Poland.
| | - Beata Rysiewicz
- Department of Physical Biochemistry, Faculty of Biochemistry Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387 Kraków, Poland.
| | - Jan Gregrowicz
- Department of Physical Biochemistry, Faculty of Biochemistry Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387 Kraków, Poland.
| | - Marta Dziedzicka-Wasylewska
- Department of Physical Biochemistry, Faculty of Biochemistry Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387 Kraków, Poland.
| | - Agnieszka Polit
- Department of Physical Biochemistry, Faculty of Biochemistry Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387 Kraków, Poland.
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12
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Effects of Post-translational Modifications on Membrane Localization and Signaling of Prostanoid GPCR-G Protein Complexes and the Role of Hypoxia. J Membr Biol 2019; 252:509-526. [PMID: 31485700 DOI: 10.1007/s00232-019-00091-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Accepted: 08/17/2019] [Indexed: 02/07/2023]
Abstract
G protein-coupled receptors (GPCRs) play a pivotal role in the adaptive responses to cellular stresses such as hypoxia. In addition to influencing cellular gene expression profiles, hypoxic microenvironments can perturb membrane protein localization, altering GPCR effector scaffolding and altering downstream signaling. Studies using proteomics approaches have revealed significant regulation of GPCR and G proteins by their state of post-translational modification. The aim of this review is to examine the effects of post-translational modifications on membrane localization and signaling of GPCR-G protein complexes, with an emphasis on vascular prostanoid receptors, and to highlight what is known about the effect of cellular hypoxia on these mechanisms. Understanding post-translational modifications of protein targets will help to define GPCR targets in treatment of disease, and to inform research into mechanisms of hypoxic cellular responses.
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Local membrane charge regulates β 2 adrenergic receptor coupling to G i3. Nat Commun 2019; 10:2234. [PMID: 31110175 PMCID: PMC6527575 DOI: 10.1038/s41467-019-10108-0] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2018] [Accepted: 04/18/2019] [Indexed: 11/13/2022] Open
Abstract
The β2 adrenergic receptor (β2AR) signals through both Gs and Gi in cardiac myocytes, and the Gi pathway counteracts the Gs pathway. However, Gi coupling is much less efficient than Gs coupling in most cell-based and biochemical assays, making it difficult to study β2AR−Gi interactions. Here we investigate the role of phospholipid composition on Gs and Gi coupling. While negatively charged phospholipids are known to enhance agonist affinity and stabilize an active state of the β2AR, we find that they impair coupling to Gi3 and facilitate coupling to Gs. Positively charged Ca2+ and Mg2+, known to interact with the negative charge on phospholipids, facilitates Gi3 coupling. Mutational analysis suggests that Ca2+ coordinates an interaction between phospholipid and the negatively charged EDGE motif on the amino terminal helix of Gi3. Taken together, our observations suggest that local membrane charge modulates the interaction between β2AR and competing G protein subtypes. In the healthy heart, the β2 adrenergic receptor (β2AR) signals through Gs and Gi proteins but the mechanism underlying G protein selectivity is not fully understood. Here, the authors show that membrane charge and intracellular cations modulate the β2AR−Gi3 interaction.
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14
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Kano H, Toyama Y, Imai S, Iwahashi Y, Mase Y, Yokogawa M, Osawa M, Shimada I. Structural mechanism underlying G protein family-specific regulation of G protein-gated inwardly rectifying potassium channel. Nat Commun 2019; 10:2008. [PMID: 31043612 PMCID: PMC6494913 DOI: 10.1038/s41467-019-10038-x] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Accepted: 04/12/2019] [Indexed: 01/26/2023] Open
Abstract
G protein-gated inwardly rectifying potassium channel (GIRK) plays a key role in regulating neurotransmission. GIRK is opened by the direct binding of the G protein βγ subunit (Gβγ), which is released from the heterotrimeric G protein (Gαβγ) upon the activation of G protein-coupled receptors (GPCRs). GIRK contributes to precise cellular responses by specifically and efficiently responding to the Gi/o-coupled GPCRs. However, the detailed mechanisms underlying this family-specific and efficient activation are largely unknown. Here, we investigate the structural mechanism underlying the Gi/o family-specific activation of GIRK, by combining cell-based BRET experiments and NMR analyses in a reconstituted membrane environment. We show that the interaction formed by the αA helix of Gαi/o mediates the formation of the Gαi/oβγ-GIRK complex, which is responsible for the family-specific activation of GIRK. We also present a model structure of the Gαi/oβγ-GIRK complex, which provides the molecular basis underlying the specific and efficient regulation of GIRK.
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Affiliation(s)
- Hanaho Kano
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Yuki Toyama
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Shunsuke Imai
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Yuta Iwahashi
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Yoko Mase
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Mariko Yokogawa
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.,Faculty of Pharmacy, Keio University, Shibakoen, Minato-ku, Tokyo, 105-8512, Japan
| | - Masanori Osawa
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.,Faculty of Pharmacy, Keio University, Shibakoen, Minato-ku, Tokyo, 105-8512, Japan
| | - Ichio Shimada
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
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15
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Lim SM, Kim YE, Choi WJ, Oh KW, Noh MY, Kwon MS, Nahm M, Kim N, Ki CS, Kim SH. CLEC4C p.K210del variant causes impaired cell surface transport in plasmacytoid dendritic cells of amyotrophic lateral sclerosis. Oncotarget 2018; 7:24942-9. [PMID: 26943047 PMCID: PMC5041881 DOI: 10.18632/oncotarget.7886] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Accepted: 01/29/2016] [Indexed: 01/06/2023] Open
Abstract
The type II C-type lectin CLEC4C is a transmembrane protein selectively expressed on plasmacytoid dendritic cells (PDCs). Although its mechanism of action remains unclear, triggering of the extracellular C-terminal C-type carbohydrate recognition region of CLEC4C regulates the secretion of proinflammatory cytokines and type I IFNs in PDCs. Applying whole-exome sequencing in a patient with juvenile amyotrophic lateral sclerosis (ALS) and both healthy parents, we identified a de novo CLEC4C variant (c.629_631delAGA; p.Lys210del). In this study, we report that the deletion of a lysine residue at the extracellular region of CLEC4C yields a C-terminal dilysine motif that results in endoplasmic reticulum (ER) retention of the protein in transfected HeLa and Jurkat T lymphoma cell models. As a consequence, a decrease in the surface expression of CLEC4C and the ER localization of the mutant construct were observed. Furthermore, depletion of the cell surface CLEC4C level was also observed in the patient PDCs, further suggesting that the variant p.Lys210del CLEC4C may contribute to juvenile ALS susceptibility.
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Affiliation(s)
- Su Min Lim
- Department of Translational Medicine, Graduate School of Biomedical Science and Engineering, Hanyang University, Seoul, Republic of Korea.,Cell Therapy Center, Hanyang University Hospital, Seoul, Republic of Korea
| | | | - Won Jun Choi
- Department of Neurology, Sheikh Khalifa Specialty Hospital, Ras Al Khaimah, United Arab Emirates
| | - Ki-Wook Oh
- Department of Neurology, College of Medicine, Hanyang University, Seoul, Republic of Korea.,Cell Therapy Center, Hanyang University Hospital, Seoul, Republic of Korea
| | - Min-Young Noh
- Cell Therapy Center, Hanyang University Hospital, Seoul, Republic of Korea
| | - Min-Soo Kwon
- Department of Pharmacology, School of Medicine, CHA University, CHA Bio Complex, Seongnam, Republic of Korea
| | - Minyeop Nahm
- Cell Therapy Center, Hanyang University Hospital, Seoul, Republic of Korea
| | - Namshin Kim
- Epigenomics Research Center Genome Institute, Korea Research Institute of Bioscience and Biotechnology, Daejeon, Republic of Korea
| | - Chang-Seok Ki
- Department of Laboratory Medicine and Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Seung Hyun Kim
- Department of Translational Medicine, Graduate School of Biomedical Science and Engineering, Hanyang University, Seoul, Republic of Korea.,Department of Neurology, College of Medicine, Hanyang University, Seoul, Republic of Korea.,Cell Therapy Center, Hanyang University Hospital, Seoul, Republic of Korea
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16
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Weber P, Batoulis H, Rink KM, Dahlhoff S, Pinkwart K, Söllner TH, Lang T. Electrostatic anchoring precedes stable membrane attachment of SNAP25/SNAP23 to the plasma membrane. eLife 2017; 6. [PMID: 28240595 PMCID: PMC5362264 DOI: 10.7554/elife.19394] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Accepted: 02/26/2017] [Indexed: 11/15/2022] Open
Abstract
The SNAREs SNAP25 and SNAP23 are proteins that are initially cytosolic after translation, but then become stably attached to the cell membrane through palmitoylation of cysteine residues. For palmitoylation to occur, membrane association is a prerequisite, but it is unclear which motif may increase the affinities of the proteins for the target membrane. In experiments with rat neuroendocrine cells, we find that a few basic amino acids in the cysteine-rich region of SNAP25 and SNAP23 are essential for plasma membrane targeting. Reconstitution of membrane-protein binding in a liposome assay shows that the mechanism involves protein electrostatics between basic amino acid residues and acidic lipids such as phosphoinositides that play a primary role in these interactions. Hence, we identify an electrostatic anchoring mechanism underlying initial plasma membrane contact by SNARE proteins, which subsequently become palmitoylated at the plasma membrane. DOI:http://dx.doi.org/10.7554/eLife.19394.001 Cells often communicate with each other by releasing chemicals that normally are stored in small membrane-bound compartments called vesicles. For example, when a neuron is stimulated, vesicles merge with its cell membrane and release their content into a gap between itself and other neurons. This complicated process involves many steps and molecules, including proteins called SNAREs. Some SNARE proteins reside at the inner side of the cell membrane and help vesicles to fuse with this membrane. Two SNARE proteins called SNAP25 and SNAP23 are produced in the liquid inside the cell and initially float freely. Eventually, these proteins become directly anchored to the cell membrane, however, not much is known about what happens to these proteins in between these stages, or how they first attach to the membrane before anchoring to it. Electrostatic forces between oppositely charged molecules are known to be important for them to bind with each other. Here, electrostatic forces are less likely to occur because SNAP25 and SNAP23 are both mostly negatively charged, and should therefore be repelled from the cell membrane, which also typically has a negative charge. However, both SNAP25 and SNAP23 have a small cluster of positively charged amino acids (the building blocks of proteins) near the attachment site, and Weber et al. have now tested whether this charge is sufficient to overcome the predicted repulsion. The approach involved making mutant proteins with either more or less positively charged attachment regions. Mutant SNAP25 or SNAP23 proteins with more positive charges may stick more tightly but not necessarily more permanently to the membrane. However, when the number of positive charges was lowered, more of the proteins remained floating freely in the liquid inside the cell. These results suggest that even a small number of positively charged amino acids is sufficient to help a protein bind to a cell membrane for further processing. The findings of Weber et al. reveal an early step in the life cycle of SNAP25 and SNAP23 before they anchor to the cell membrane. They suggest that finely tuned protein electrostatics can regulate how long a protein spends at a specific site and thereby indirectly determine its fate. Such fine-tuned protein electrostatics are difficult to recognize and could represent an underestimated regulatory mechanism in all types of cells. DOI:http://dx.doi.org/10.7554/eLife.19394.002
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Affiliation(s)
- Pascal Weber
- Membrane Biochemistry, Life and Medical Sciences (LIMES) Institute, University of Bonn, Bonn, Germany
| | - Helena Batoulis
- Membrane Biochemistry, Life and Medical Sciences (LIMES) Institute, University of Bonn, Bonn, Germany
| | - Kerstin M Rink
- Heidelberg University Biochemistry Center (BZH), Heidelberg, Germany
| | - Stefan Dahlhoff
- Membrane Biochemistry, Life and Medical Sciences (LIMES) Institute, University of Bonn, Bonn, Germany
| | - Kerstin Pinkwart
- Membrane Biochemistry, Life and Medical Sciences (LIMES) Institute, University of Bonn, Bonn, Germany
| | - Thomas H Söllner
- Heidelberg University Biochemistry Center (BZH), Heidelberg, Germany
| | - Thorsten Lang
- Membrane Biochemistry, Life and Medical Sciences (LIMES) Institute, University of Bonn, Bonn, Germany
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17
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Page KM, Rothwell SW, Dolphin AC. The CaVβ Subunit Protects the I-II Loop of the Voltage-gated Calcium Channel CaV2.2 from Proteasomal Degradation but Not Oligoubiquitination. J Biol Chem 2016; 291:20402-16. [PMID: 27489103 PMCID: PMC5034038 DOI: 10.1074/jbc.m116.737270] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Indexed: 11/06/2022] Open
Abstract
CaVβ subunits interact with the voltage-gated calcium channel CaV2.2 on a site in the intracellular loop between domains I and II (the I-II loop). This interaction influences the biophysical properties of the channel and leads to an increase in its trafficking to the plasma membrane. We have shown previously that a mutant CaV2.2 channel that is unable to bind CaVβ subunits (CaV2.2 W391A) was rapidly degraded (Waithe, D., Ferron, L., Page, K. M., Chaggar, K., and Dolphin, A. C. (2011) J. Biol. Chem. 286, 9598-9611). Here we show that, in the absence of CaVβ subunits, a construct consisting of the I-II loop of CaV2.2 was directly ubiquitinated and degraded by the proteasome system. Ubiquitination could be prevented by mutation of all 12 lysine residues in the I-II loop to arginines. Including a palmitoylation motif at the N terminus of CaV2.2 I-II loop was insufficient to target it to the plasma membrane in the absence of CaVβ subunits even when proteasomal degradation was inhibited with MG132 or ubiquitination was prevented by the lysine-to-arginine mutations. In the presence of CaVβ subunit, the palmitoylated CaV2.2 I-II loop was protected from degradation, although oligoubiquitination could still occur, and was efficiently trafficked to the plasma membrane. We propose that targeting to the plasma membrane requires a conformational change in the I-II loop that is induced by binding of the CaVβ subunit.
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Affiliation(s)
- Karen M Page
- From the Department of Neuroscience, Physiology and Pharmacology, University College London, Gower St., London WC1E 6BT, United Kingdom
| | - Simon W Rothwell
- From the Department of Neuroscience, Physiology and Pharmacology, University College London, Gower St., London WC1E 6BT, United Kingdom
| | - Annette C Dolphin
- From the Department of Neuroscience, Physiology and Pharmacology, University College London, Gower St., London WC1E 6BT, United Kingdom
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18
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Kamato D, Thach L, Bernard R, Chan V, Zheng W, Kaur H, Brimble M, Osman N, Little PJ. Structure, Function, Pharmacology, and Therapeutic Potential of the G Protein, Gα/q,11. Front Cardiovasc Med 2015; 2:14. [PMID: 26664886 PMCID: PMC4671355 DOI: 10.3389/fcvm.2015.00014] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Accepted: 03/11/2015] [Indexed: 11/19/2022] Open
Abstract
G protein coupled receptors (GPCRs) are one of the major classes of cell surface receptors and are associated with a group of G proteins consisting of three subunits termed alpha, beta, and gamma. G proteins are classified into four families according to their α subunit; Gαi, Gαs, Gα12/13, and Gαq. There are several downstream pathways of Gαq of which the best known is upon activation via guanosine triphosphate (GTP), Gαq activates phospholipase Cβ, hydrolyzing phosphatidylinositol 4,5-biphosphate into diacylglycerol and inositol triphosphate and activating protein kinase C and increasing calcium efflux from the endoplasmic reticulum. Although G proteins, in particular, the Gαq/11 are central elements in GPCR signaling, their actual roles have not yet been thoroughly investigated. The lack of research of the role on Gαq/11 in cell biology is partially due to the obscure nature of the available pharmacological agents. YM-254890 is the most useful Gαq-selective inhibitor with antiplatelet, antithrombotic, and thrombolytic effects. YM-254890 inhibits Gαq signaling pathways by preventing the exchange of guanosine diphosphate for GTP. UBO-QIC is a structurally similar compound to YM-254890, which can inhibit platelet aggregation and cause vasorelaxation in rats. Many agents are available for the study of signaling downstream of Gαq/11. The role of G proteins could potentially represent a novel therapeutic target. This review will explore the range of pharmacological and molecular tools available for the study of the role of Gαq/11 in GPCR signaling.
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Affiliation(s)
- Danielle Kamato
- Discipline of Pharmacy, Diabetes Complications Group, School of Medical Sciences, Health Innovations Research Institute, RMIT University , Bundoora, VIC , Australia
| | - Lyna Thach
- Discipline of Pharmacy, Diabetes Complications Group, School of Medical Sciences, Health Innovations Research Institute, RMIT University , Bundoora, VIC , Australia
| | - Rebekah Bernard
- Discipline of Pharmacy, Diabetes Complications Group, School of Medical Sciences, Health Innovations Research Institute, RMIT University , Bundoora, VIC , Australia
| | - Vincent Chan
- Discipline of Pharmacy, Diabetes Complications Group, School of Medical Sciences, Health Innovations Research Institute, RMIT University , Bundoora, VIC , Australia
| | - Wenhua Zheng
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Centre , Guangzhou , China ; Faculty of Health Sciences, University of Macau , Macau , China
| | - Harveen Kaur
- Department of Chemistry, University of Auckland , Auckland , New Zealand
| | - Margaret Brimble
- Department of Chemistry, University of Auckland , Auckland , New Zealand
| | - Narin Osman
- Discipline of Pharmacy, Diabetes Complications Group, School of Medical Sciences, Health Innovations Research Institute, RMIT University , Bundoora, VIC , Australia
| | - Peter J Little
- Discipline of Pharmacy, Diabetes Complications Group, School of Medical Sciences, Health Innovations Research Institute, RMIT University , Bundoora, VIC , Australia
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19
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Chauvin S, Sobel A. Neuronal stathmins: A family of phosphoproteins cooperating for neuronal development, plasticity and regeneration. Prog Neurobiol 2015; 126:1-18. [DOI: 10.1016/j.pneurobio.2014.09.002] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Revised: 09/23/2014] [Accepted: 09/29/2014] [Indexed: 02/06/2023]
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20
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Sánchez-Fernández G, Cabezudo S, García-Hoz C, Benincá C, Aragay AM, Mayor F, Ribas C. Gαq signalling: the new and the old. Cell Signal 2014; 26:833-48. [PMID: 24440667 DOI: 10.1016/j.cellsig.2014.01.010] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Accepted: 01/09/2014] [Indexed: 01/25/2023]
Abstract
In the last few years the interactome of Gαq has expanded considerably, contributing to improve our understanding of the cellular and physiological events controlled by this G alpha subunit. The availability of high-resolution crystal structures has led the identification of an effector-binding region within the surface of Gαq that is able to recognise a variety of effector proteins. Consequently, it has been possible to ascribe different Gαq functions to specific cellular players and to identify important processes that are triggered independently of the canonical activation of phospholipase Cβ (PLCβ), the first identified Gαq effector. Novel effectors include p63RhoGEF, that provides a link between G protein-coupled receptors and RhoA activation, phosphatidylinositol 3-kinase (PI3K), implicated in the regulation of the Akt pathway, or the cold-activated TRPM8 channel, which is directly inhibited upon Gαq binding. Recently, the activation of ERK5 MAPK by Gq-coupled receptors has also been described as a novel PLCβ-independent signalling axis that relies upon the interaction between this G protein and two novel effectors (PKCζ and MEK5). Additionally, the association of Gαq with different regulatory proteins can modulate its effector coupling ability and, therefore, its signalling potential. Regulators include accessory proteins that facilitate effector activation or, alternatively, inhibitory proteins that downregulate effector binding or promote signal termination. Moreover, Gαq is known to interact with several components of the cytoskeleton as well as with important organisers of membrane microdomains, which suggests that efficient signalling complexes might be confined to specific subcellular environments. Overall, the complex interaction network of Gαq underlies an ever-expanding functional diversity that puts forward this G alpha subunit as a major player in the control of physiological functions and in the development of different pathological situations.
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Affiliation(s)
- Guzmán Sánchez-Fernández
- Departamento de Biología Molecular and Centro de Biologia Molecular "Severo Ochoa", CSIC-UAM, Universidad Autónoma de Madrid, Spain; Instituto de Investigación Sanitaria La Princesa, Madrid, Spain
| | - Sofía Cabezudo
- Departamento de Biología Molecular and Centro de Biologia Molecular "Severo Ochoa", CSIC-UAM, Universidad Autónoma de Madrid, Spain; Instituto de Investigación Sanitaria La Princesa, Madrid, Spain
| | - Carlota García-Hoz
- Departamento de Biología Molecular and Centro de Biologia Molecular "Severo Ochoa", CSIC-UAM, Universidad Autónoma de Madrid, Spain; Instituto de Investigación Sanitaria La Princesa, Madrid, Spain
| | | | - Anna M Aragay
- Department of Cell Biology, Molecular Biology Institute of Barcelona, Spain
| | - Federico Mayor
- Departamento de Biología Molecular and Centro de Biologia Molecular "Severo Ochoa", CSIC-UAM, Universidad Autónoma de Madrid, Spain; Instituto de Investigación Sanitaria La Princesa, Madrid, Spain
| | - Catalina Ribas
- Departamento de Biología Molecular and Centro de Biologia Molecular "Severo Ochoa", CSIC-UAM, Universidad Autónoma de Madrid, Spain; Instituto de Investigación Sanitaria La Princesa, Madrid, Spain.
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21
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Abstract
The classical view of heterotrimeric G protein signaling places G -proteins at the cytoplasmic surface of the cell's plasma membrane where they are activated by an appropriate G protein-coupled receptor. Once activated, the GTP-bound Gα and the free Gβγ are able to regulate plasma membrane-localized effectors, such as adenylyl cyclase, phospholipase C-β, RhoGEFs and ion channels. Hydrolysis of GTP by the Gα subunit returns the G protein to the inactive Gαβγ heterotrimer. Although all of these events in the G protein cycle can be restricted to the cytoplasmic surface of the plasma membrane, G protein localization is dynamic. Thus, it has become increasingly clear that G proteins are able to move to diverse subcellular locations where they perform non-canonical signaling functions. This chapter will highlight our current understanding of trafficking pathways that target newly synthesized G proteins to the plasma membrane, activation-induced and reversible translocation of G proteins from the plasma membrane to intracellular locations, and constitutive trafficking of G proteins.
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22
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Protein palmitoylation and subcellular trafficking. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1808:2981-94. [DOI: 10.1016/j.bbamem.2011.07.009] [Citation(s) in RCA: 257] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2011] [Revised: 07/06/2011] [Accepted: 07/12/2011] [Indexed: 02/07/2023]
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23
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Liu Z, Turan S, Wehbi VL, Vilardaga JP, Bastepe M. Extra-long Gαs variant XLαs protein escapes activation-induced subcellular redistribution and is able to provide sustained signaling. J Biol Chem 2011; 286:38558-38569. [PMID: 21890629 DOI: 10.1074/jbc.m111.240150] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Murine models indicate that Gαs and its extra-long variant XLαs, both of which are derived from GNAS, markedly differ regarding their cellular actions, but these differences are unknown. Here we investigated activation-induced trafficking of Gαs and XLαs, using immunofluorescence microscopy, cell fractionation, and total internal reflection fluorescence microscopy. In transfected cells, XLαs remained localized to the plasma membrane, whereas Gαs redistributed to the cytosol after activation by GTPase-inhibiting mutations, cholera toxin treatment, or G protein-coupled receptor agonists (isoproterenol or parathyroid hormone (PTH)(1-34)). Cholera toxin treatment or agonist (isoproterenol or pituitary adenylate cyclase activating peptide-27) stimulation of PC12 cells expressing Gαs and XLαs endogenously led to an increased abundance of Gαs, but not XLαs, in the soluble fraction. Mutational analyses revealed two conserved cysteines and the highly charged domain as being critically involved in the plasma membrane anchoring of XLαs. The cAMP response induced by M-PTH(1-14), a parathyroid hormone analog, terminated quickly in HEK293 cells stably expressing the type 1 PTH/PTH-related peptide receptor, whereas the response remained maximal for at least 6 min in cells that co-expressed the PTH receptor and XLαs. Although isoproterenol-induced cAMP response was not prolonged by XLαs expression, a GTPase-deficient XLαs mutant found in certain tumors and patients with fibrous dysplasia of bone and McCune-Albright syndrome generated more basal cAMP accumulation in HEK293 cells and caused more severe impairment of osteoblastic differentiation of MC3T3-E1 cells than the cognate Gαs mutant (gsp oncogene). Thus, activated XLαs and Gαs traffic differently, and this may form the basis for the differences in their cellular actions.
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Affiliation(s)
- Zun Liu
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114
| | - Serap Turan
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114; Pediatric Endocrinology, Marmara University School of Medicine Hospital, 34662 Istanbul, Turkey
| | - Vanessa L Wehbi
- Laboratory for G Protein-coupled Receptor Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh, School of Medicine, Pittsburgh, Pennsylvania 15213
| | - Jean-Pierre Vilardaga
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114; Laboratory for G Protein-coupled Receptor Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh, School of Medicine, Pittsburgh, Pennsylvania 15213
| | - Murat Bastepe
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114.
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24
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Qin K, Dong C, Wu G, Lambert NA. Inactive-state preassembly of G(q)-coupled receptors and G(q) heterotrimers. Nat Chem Biol 2011; 7:740-7. [PMID: 21873996 PMCID: PMC3177959 DOI: 10.1038/nchembio.642] [Citation(s) in RCA: 115] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2011] [Accepted: 06/29/2011] [Indexed: 12/29/2022]
Abstract
G protein-coupled receptors (GPCRs) transmit signals by forming active-state complexes with heterotrimeric G proteins. It has been suggested that some GPCRs also assemble with G proteins before ligand-induced activation and that inactive-state preassembly facilitates rapid and specific G protein activation. However, no mechanism of preassembly has been described, and no functional consequences of preassembly have been demonstrated. Here we show that M(3) muscarinic acetylcholine receptors (M3R) form inactive-state complexes with G(q) heterotrimers in intact cells. The M3R C terminus is sufficient, and a six-amino-acid polybasic sequence distal to helix 8 ((565)KKKRRK(570)) is necessary for preassembly with G(q). Replacing this sequence with six alanine residues prevents preassembly, slows the rate of G(q) activation and decreases steady-state agonist sensitivity. That other G(q)-coupled receptors possess similar polybasic regions and also preassemble with G(q) suggests that these GPCRs may use a common preassembly mechanism to facilitate activation of G(q) heterotrimers.
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Affiliation(s)
- Kou Qin
- Department of Pharmacology and Toxicology, Georgia Health Sciences University, Augusta, Georgia, USA
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25
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Levy AD, Devignot V, Fukata Y, Fukata M, Sobel A, Chauvin S. Subcellular Golgi localization of stathmin family proteins is promoted by a specific set of DHHC palmitoyl transferases. Mol Biol Cell 2011; 22:1930-42. [PMID: 21471001 PMCID: PMC3103408 DOI: 10.1091/mbc.e10-10-0824] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Palmitoylation of the neuronal microtubule regulatory stathmin phosphoproteins is crucial for their Golgi and vesicle localization and trafficking along neurites. It is promoted by a specific set of palmitoyl transferases, which suggests that palmitoylation can be viewed as a crucial regulatory process for neuronal stathmin functions. Protein palmitoylation is a reversible lipid modification that plays critical roles in protein sorting and targeting to specific cellular compartments. The neuronal microtubule-regulatory phosphoproteins of the stathmin family (SCG10/stathmin 2, SCLIP/stathmin 3, and RB3/stathmin 4) are peripheral proteins that fulfill specific and complementary roles in the formation and maturation of the nervous system. All neuronal stathmins are localized at the Golgi complex and at vesicles along axons and dendrites. Their membrane anchoring results from palmitoylation of two close cysteine residues present within their homologous N-terminal targeting domains. By preventing palmitoylation with 2-bromopalmitate or disrupting the integrity of the Golgi with brefeldin A, we were able to show that palmitoylation of stathmins 2 and 3 likely occurs at the Golgi and is crucial for their specific subcellular localization and trafficking. In addition, this membrane binding is promoted by a specific set of palmitoyl transferases that localize with stathmins 2 and 3 at the Golgi, directly interact with them, and enhance their membrane association. The subcellular membrane–associated microtubule-regulatory activity of stathmins might then be fine-tuned by extracellular stimuli controlling their reversible palmitoylation, which can be viewed as a crucial regulatory process for specific and local functions of stathmins in neurons.
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Affiliation(s)
- Aurore D Levy
- INSERM U 839, Université Pierre et Marie Curie, UMR-S839, and Institut du Fer à Moulin, F-75005, Paris, France
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Li J, Zhao H, Luo P, Gu Y. Functional cooperation of of IL-1β and RGS4 in the brachial plexus avulsion mediated brain reorganization. J Brachial Plex Peripher Nerve Inj 2010; 5:18. [PMID: 21138588 PMCID: PMC3017042 DOI: 10.1186/1749-7221-5-18] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2010] [Accepted: 12/07/2010] [Indexed: 01/27/2023] Open
Abstract
BACKGROUNDS There is considerable evidence that central nervous system is continuously modulated by activity, behavior and skill acquisition. This study is to examine the reorganization in cortical and subcortical regions in response to brachial plexus avulsion. METHODS Adult C57BL/6 mice were divided into four groups: control, 1, 3 and 6 month of brachial plexus avulsion. IL-1β, IL-6 and RGS4 expression in cortex, brainstem and spinal cord were detected by BiostarM-140 s microarray and real-time PCR. RGS4 subcellular distribution and modulation were further analyzed by primary neuron culture and Western Blot. RESULTS After 1, 3 and 6 months of brachial plexus avulsion, 49 (0 up, 49 down), 29 (17 up, 12 down), 13 (9 up, 4 down) genes in cerebral cortex, 40 (8 up, 32 down), 11 (7 up, 4 down), 137 (63 up, 74 down) in brainstem, 27 (14 up, 13 down), 33 (18 up, 15 down), 60 (29 up, 31 down) in spinal cord were identified. Among the regulated gene, IL-1β and IL-6 were sustainable enhanced in brain stem, while PKACβ and RGS4 were up-regulated throughout cerebral cortex, brainstem and spinal cord in 3 and 6 month of nerve injury. Intriguingly, subcellular distribution of RGS4 in above three regions was dependent on the functional correlation of PKA and IL-1β. CONCLUSION Data herein indicated that brachial plexus avulsion could efficiently initiate and perpetuate the brain reorganization. Network involved IL-1β and RGS4 signaling might implicate in the re-establish and strengthening of the local circuits at the cortical and subcortical levels.
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Affiliation(s)
- Jifeng Li
- Lab of Hand function reconstruction, Huashan Hospital, Fudan University, Shanghai, China
| | - Hui Zhao
- Lab of Hand function reconstruction, Huashan Hospital, Fudan University, Shanghai, China
| | - Pengbo Luo
- Lab of Hand function reconstruction, Huashan Hospital, Fudan University, Shanghai, China
| | - Yudong Gu
- Lab of Hand function reconstruction, Huashan Hospital, Fudan University, Shanghai, China
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Crouthamel M, Abankwa D, Zhang L, DiLizio C, Manning DR, Hancock JF, Wedegaertner PB. An N-terminal polybasic motif of Gαq is required for signaling and influences membrane nanodomain distribution. Mol Pharmacol 2010; 78:767-77. [PMID: 20664004 DOI: 10.1124/mol.110.066340] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Regions of basic amino acids in proteins can promote membrane localization through electrostatic interactions with negatively charged membrane lipid head groups. Previous work showed that the heterotrimeric G protein subunit α(q) contains a polybasic region in its N terminus that contributes to plasma membrane localization. Here, the role of the N-terminal polybasic region of α(q) in signaling was addressed. For α(q) mutants, loss of plasma membrane localization correlated with loss of signaling function, as measured by the ability to couple activated G protein-coupled receptors (GPCRs) to stimulation of inositol phosphate production. However, recovery of plasma membrane localization of α(q) polybasic mutants by introduction of a site for myristoylation or by coexpression of βγ failed to recover signaling, suggesting a role for N-terminal basic amino acids of α(q) beyond simple plasma membrane localization. It is noteworthy that an α(q)4Q mutant, containing glutamine substitutions at arginines 27, 30, 31, and 34, was identified that failed to mediate signaling yet retained plasma membrane localization. Although α(q)4Q failed to couple activated receptors to inositol phosphate production, it was able to bind βγ, bind RGS4 in an activation-dependent manner, stimulate inositol phosphate production in a receptor-independent manner, and productively interact with a GPCR in isolated membranes. It is noteworthy that α(q)4Q showed a differing localization to plasma membrane nanodomains compared with wild-type α(q). Thus, basic amino acids in the N terminus of α(q) can affect its lateral segregation on plasma membranes, and changes in such lateral segregation may be responsible for the observed signaling defects of α(q)4Q.
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Affiliation(s)
- Marykate Crouthamel
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 233 S. 10th Street, 839 BLSB, Philadelphia, PA 19107, USA
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Kosloff M, Alexov E, Arshavsky VY, Honig B. Electrostatic and lipid anchor contributions to the interaction of transducin with membranes: mechanistic implications for activation and translocation. J Biol Chem 2008; 283:31197-207. [PMID: 18782760 PMCID: PMC2576562 DOI: 10.1074/jbc.m803799200] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The heterotrimeric G protein transducin is a key component of the
vertebrate phototransduction cascade. Transducin is peripherally attached to
membranes of the rod outer segment, where it interacts with other proteins at
the membrane-cytosol interface. However, upon sustained activation by light,
the dissociated Gtα and
Gβ1γ1 subunits of transducin translocate from
the outer segment to other parts of the rod cell. Here we used a computational
approach to analyze the interaction strength of transducin and its subunits
with acidic lipid bilayers, as well as the range of orientations that they are
allowed to occupy on the membrane surface. Our results suggest that the
combined constraints of electrostatics and lipid anchors substantially limit
the rotational degrees of freedom of the membrane-bound transducin
heterotrimer. This may contribute to a faster transducin activation rate by
accelerating transducin-rhodopsin complex formation. Notably, the membrane
interactions of the dissociated transducin subunits are very different from
those of the heterotrimer. As shown previously,
Gβ1γ1 experiences significant attractive
interactions with negatively charged membranes, whereas our new results
suggest that Gtα is electrostatically repelled by such
membranes. We suggest that this repulsion could facilitate the membrane
dissociation and intracellular translocation of Gtα.
Moreover, based on similarities in sequence and electrostatic properties, we
propose that the properties described for transducin are common to its
homologs within the Gi subfamily. In a broader view, this work
exemplifies how the activity-dependent association and dissociation of a G
protein can change both the affinity for membranes and the range of allowed
orientations, thereby modulating G protein function.
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Affiliation(s)
- Mickey Kosloff
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, USA
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