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Lefevre TJ, Wei W, Mukhaleva E, Meda Venkata SP, Chandan NR, Abraham S, Li Y, Dessauer CW, Vaidehi N, Smrcka AV. Stabilization of interdomain interactions in G protein α subunits as a determinant of Gα i subtype signaling specificity. J Biol Chem 2024; 300:107211. [PMID: 38522511 PMCID: PMC11066577 DOI: 10.1016/j.jbc.2024.107211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 03/07/2024] [Accepted: 03/12/2024] [Indexed: 03/26/2024] Open
Abstract
Highly homologous members of the Gαi family, Gαi1-3, have distinct tissue distributions and physiological functions, yet their biochemical and functional properties are very similar. We recently identified PDZ-RhoGEF (PRG) as a novel Gαi1 effector that is poorly activated by Gαi2. In a proteomic proximity labeling screen we observed a strong preference for Gαi1 relative to Gαi2 with respect to engagement of a broad range of potential targets. We investigated the mechanistic basis for this selectivity using PRG as a representative target. Substitution of either the helical domain (HD) from Gαi1 into Gαi2 or substitution of a single amino acid, A230 in Gαi2 with the corresponding D in Gαi1, largely rescues PRG activation and interactions with other potential Gαi targets. Molecular dynamics simulations combined with Bayesian network models revealed that in the GTP bound state, separation at the HD-Ras-like domain (RLD) interface is more pronounced in Gαi2 than Gαi1. Mutation of A230 to D in Gαi2 stabilizes HD-RLD interactions via ionic interactions with R145 in the HD which in turn modify the conformation of Switch III. These data support a model where D229 in Gαi1 interacts with R144 and stabilizes a network of interactions between HD and RLD to promote protein target recognition. The corresponding A230 in Gαi2 is unable to stabilize this network leading to an overall lower efficacy with respect to target interactions. This study reveals distinct mechanistic properties that could underly differential biological and physiological consequences of activation of Gαi1 or Gαi2 by G protein-coupled receptors.
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Affiliation(s)
- Tyler J Lefevre
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan, USA; Program in Chemical Biology, University of Michigan, Ann Arbor, Michigan, USA
| | - Wenyuan Wei
- Department of Computational and Quantitative Medicine, Beckman Research Institute of the City of Hope, Duarte, California, USA
| | - Elizaveta Mukhaleva
- Department of Computational and Quantitative Medicine, Beckman Research Institute of the City of Hope, Duarte, California, USA
| | | | - Naincy R Chandan
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan, USA; Genentech, South San Francisco, California, USA
| | - Saji Abraham
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Yong Li
- Department of Integrative Biology and Pharmacology McGovern Medical School, UTHealth, Houston, Texas, USA
| | - Carmen W Dessauer
- Department of Integrative Biology and Pharmacology McGovern Medical School, UTHealth, Houston, Texas, USA
| | - Nagarajan Vaidehi
- Department of Computational and Quantitative Medicine, Beckman Research Institute of the City of Hope, Duarte, California, USA
| | - Alan V Smrcka
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan, USA.
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2
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Shumate AD, Farrens DL. A rapid, tag-free way to purify functional GPCRs. J Biol Chem 2024; 300:105558. [PMID: 38097184 PMCID: PMC10820827 DOI: 10.1016/j.jbc.2023.105558] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Revised: 12/01/2023] [Accepted: 12/05/2023] [Indexed: 01/14/2024] Open
Abstract
G protein-coupled receptors (GPCRs) play diverse signaling roles and represent major pharmaceutical targets. Consequently, they are the focus of intense study, and numerous advances have been made in their handling and analysis. However, a universal way to purify GPCRs has remained elusive, in part because of their inherent instability when isolated from cells. To address this, we have developed a general, rapid, and tag-free way to purify GPCRs. The method uses short peptide analogs of the Gα subunit C terminus (Gα-CT) that are attached to chromatography beads (Gα-CT resin). Because the Gα-CT peptides bind active GPCRs with high affinity, the Gα-CT resin selectively purifies only active functional receptors. We use this method to purify both rhodopsin and the β2-adrenergic receptor and show they can be purified in either active conformations or inactive conformations, simply by varying elution conditions. While simple in concept-leveraging the conserved GPCR-Gα-CT binding interaction for the purpose of GPCR purification-we think this approach holds excellent potential to isolate functional receptors for a myriad of uses, from structural biology to proteomics.
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Affiliation(s)
- Anthony D Shumate
- Department of Chemical Biology and Physiology, Oregon Health and Science University, Portland, Oregon, USA
| | - David L Farrens
- Department of Chemical Biology and Physiology, Oregon Health and Science University, Portland, Oregon, USA.
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3
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Vo ADP, Kim SK, Yang MY, Ondrus AE, Goddard WA. Fully activated structure of the sterol-bound Smoothened GPCR-Gi protein complex. Proc Natl Acad Sci U S A 2023; 120:e2300919120. [PMID: 38015850 DOI: 10.1073/pnas.2300919120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Accepted: 10/22/2023] [Indexed: 11/30/2023] Open
Abstract
Smoothened (SMO) is an oncoprotein and signal transducer in the Hedgehog signaling pathway that regulates cellular differentiation and embryogenesis. As a member of the Frizzled (Class F) family of G protein-coupled receptors (GPCRs), SMO biochemically and functionally interacts with Gi family proteins. However, key molecular features of fully activated, G protein-coupled SMO remain elusive. We present the atomistic structure of activated human SMO complexed with the heterotrimeric Gi protein and two sterol ligands, equilibrated at 310 K in a full lipid bilayer at physiological salt concentration and pH. In contrast to previous experimental structures, our equilibrated SMO complex exhibits complete breaking of the pi-cation interaction between R4516.32 and W5357.55, a hallmark of Class F receptor activation. The Gi protein couples to SMO at seven strong anchor points similar to those in Class A GPCRs: intracellular loop 1, intracellular loop 2, transmembrane helix 6, and helix 8. On the path to full activation, we find that the extracellular cysteine-rich domain (CRD) undergoes a dramatic tilt, following a trajectory suggested by positions of the CRD in active and inactive experimental SMO structures. Strikingly, a sterol ligand bound to a shallow transmembrane domain (TMD) site in the initial structure migrates to a deep TMD pocket found exclusively in activator-bound SMO complexes. Thus, our results indicate that SMO interacts with Gi prior to full activation to break the molecular lock, form anchors with Gi subunits, tilt the CRD, and facilitate migration of a sterol ligand in the TMD to an activated position.
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Affiliation(s)
- Amy-Doan P Vo
- Materials and Process Simulation Center, Division of Chemistry & Chemical Engineering, California Institute of Technology, Pasadena, CA 91125
| | - Soo-Kyung Kim
- Materials and Process Simulation Center, Division of Chemistry & Chemical Engineering, California Institute of Technology, Pasadena, CA 91125
| | - Moon Young Yang
- Materials and Process Simulation Center, Division of Chemistry & Chemical Engineering, California Institute of Technology, Pasadena, CA 91125
| | - Alison E Ondrus
- Department of Chemistry, University of Illinois Chicago, Chicago, IL 60607
- Department of Pharmaceutical Sciences, University of Illinois Chicago, Chicago, IL 60607
| | - William A Goddard
- Materials and Process Simulation Center, Division of Chemistry & Chemical Engineering, California Institute of Technology, Pasadena, CA 91125
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4
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Burghi V, Paradis JS, Officer A, Adame-Garcia SR, Wu X, Matthees ESF, Barsi-Rhyne B, Ramms DJ, Clubb L, Acosta M, Tamayo P, Bouvier M, Inoue A, von Zastrow M, Hoffmann C, Gutkind JS. Gαs is dispensable for β-arrestin coupling but dictates GRK selectivity and is predominant for gene expression regulation by β2-adrenergic receptor. J Biol Chem 2023; 299:105293. [PMID: 37774973 PMCID: PMC10641165 DOI: 10.1016/j.jbc.2023.105293] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Revised: 09/03/2023] [Accepted: 09/14/2023] [Indexed: 10/01/2023] Open
Abstract
β-arrestins play a key role in G protein-coupled receptor (GPCR) internalization, trafficking, and signaling. Whether β-arrestins act independently of G protein-mediated signaling has not been fully elucidated. Studies using genome-editing approaches revealed that whereas G proteins are essential for mitogen-activated protein kinase activation by GPCRs., β-arrestins play a more prominent role in signal compartmentalization. However, in the absence of G proteins, GPCRs may not activate β-arrestins, thereby limiting the ability to distinguish G protein from β-arrestin-mediated signaling events. We used β2-adrenergic receptor (β2AR) and its β2AR-C tail mutant expressed in human embryonic kidney 293 cells wildtype or CRISPR-Cas9 gene edited for Gαs, β-arrestin1/2, or GPCR kinases 2/3/5/6 in combination with arrestin conformational sensors to elucidate the interplay between Gαs and β-arrestins in controlling gene expression. We found that Gαs is not required for β2AR and β-arrestin conformational changes, β-arrestin recruitment, and receptor internalization, but that Gαs dictates the GPCR kinase isoforms involved in β-arrestin recruitment. By RNA-Seq analysis, we found that protein kinase A and mitogen-activated protein kinase gene signatures were activated by stimulation of β2AR in wildtype and β-arrestin1/2-KO cells but absent in Gαs-KO cells. These results were validated by re-expressing Gαs in the corresponding KO cells and silencing β-arrestins in wildtype cells. These findings were extended to cellular systems expressing endogenous levels of β2AR. Overall, our results support that Gs is essential for β2AR-promoted protein kinase A and mitogen-activated protein kinase gene expression signatures, whereas β-arrestins initiate signaling events modulating Gαs-driven nuclear transcriptional activity.
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Affiliation(s)
- Valeria Burghi
- Moores Cancer Center, University of California San Diego, La Jolla, California, USA; Department of Pharmacology, University of California San Diego, La Jolla, California, USA
| | - Justine S Paradis
- Moores Cancer Center, University of California San Diego, La Jolla, California, USA; Department of Pharmacology, University of California San Diego, La Jolla, California, USA
| | - Adam Officer
- Moores Cancer Center, University of California San Diego, La Jolla, California, USA; Department of Pharmacology, University of California San Diego, La Jolla, California, USA
| | - Sendi Rafael Adame-Garcia
- Moores Cancer Center, University of California San Diego, La Jolla, California, USA; Department of Pharmacology, University of California San Diego, La Jolla, California, USA
| | - Xingyu Wu
- Moores Cancer Center, University of California San Diego, La Jolla, California, USA; Department of Pharmacology, University of California San Diego, La Jolla, California, USA
| | - Edda S F Matthees
- Institut für Molekulare Zellbiologie, CMB - Center for Molecular Biomedicine, Universitätsklinikum Jena, Friedrich-Schiller-Universität Jena, Jena, Germany
| | - Benjamin Barsi-Rhyne
- Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, California, USA
| | - Dana J Ramms
- Moores Cancer Center, University of California San Diego, La Jolla, California, USA; Department of Pharmacology, University of California San Diego, La Jolla, California, USA
| | - Lauren Clubb
- Moores Cancer Center, University of California San Diego, La Jolla, California, USA; Department of Pharmacology, University of California San Diego, La Jolla, California, USA
| | - Monica Acosta
- Moores Cancer Center, University of California San Diego, La Jolla, California, USA; Department of Pharmacology, University of California San Diego, La Jolla, California, USA
| | - Pablo Tamayo
- Moores Cancer Center, University of California San Diego, La Jolla, California, USA
| | - Michel Bouvier
- Department of Biochemistry and Molecular Medicine, Institute for Research in Immunology and Cancer, Université de Montréal, Québec, Canada
| | - Asuka Inoue
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Miyagi, Japan
| | - Mark von Zastrow
- Department of Psychiatry and Department of Cellular and Molecular Pharmacology, University of California San Francisco, San Francisco, California, USA
| | - Carsten Hoffmann
- Institut für Molekulare Zellbiologie, CMB - Center for Molecular Biomedicine, Universitätsklinikum Jena, Friedrich-Schiller-Universität Jena, Jena, Germany
| | - J Silvio Gutkind
- Moores Cancer Center, University of California San Diego, La Jolla, California, USA; Department of Pharmacology, University of California San Diego, La Jolla, California, USA.
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5
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Gill KS, Mehta K, Heredia JD, Krishnamurthy VV, Zhang K, Procko E. Multiple mechanisms of self-association of chemokine receptors CXCR4 and CCR5 demonstrated by deep mutagenesis. J Biol Chem 2023; 299:105229. [PMID: 37690681 PMCID: PMC10551899 DOI: 10.1016/j.jbc.2023.105229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2023] [Revised: 08/24/2023] [Accepted: 09/04/2023] [Indexed: 09/12/2023] Open
Abstract
Chemokine receptors are members of the rhodopsin-like class A GPCRs whose signaling through G proteins drives the directional movement of cells in response to a chemokine gradient. Chemokine receptors CXCR4 and CCR5 have been extensively studied due to their roles in leukocyte development and inflammation and their status as coreceptors for HIV-1 infection, among other roles. Both receptors form dimers or oligomers of unclear function. While CXCR4 has been crystallized in a dimeric arrangement, available atomic resolution structures of CCR5 are monomeric. To investigate their dimerization interfaces, we used a bimolecular fluorescence complementation (BiFC)-based screen and deep mutational scanning to find mutations that change how the receptors self-associate, either via specific oligomer assembly or alternative mechanisms of clustering in close proximity. Many disruptive mutations promoted self-associations nonspecifically, suggesting they aggregated in the membrane. A mutationally intolerant region was found on CXCR4 that matched the crystallographic dimer interface, supporting this dimeric arrangement in living cells. A mutationally intolerant region was also observed on the surface of CCR5 by transmembrane helices 3 and 4. Mutations predicted from the scan to reduce BiFC were validated and were localized in the transmembrane domains as well as the C-terminal cytoplasmic tails where they reduced lipid microdomain localization. A mutation in the dimer interface of CXCR4 had increased binding to the ligand CXCL12 and yet diminished calcium signaling. There was no change in syncytia formation with cells expressing HIV-1 Env. The data highlight that multiple mechanisms are involved in self-association of chemokine receptor chains.
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Affiliation(s)
- Kevin S Gill
- Department of Biochemistry, University of Illinois, Urbana, Illinois, USA
| | - Kritika Mehta
- Department of Biochemistry, University of Illinois, Urbana, Illinois, USA
| | - Jeremiah D Heredia
- Department of Biochemistry, University of Illinois, Urbana, Illinois, USA
| | | | - Kai Zhang
- Department of Biochemistry, University of Illinois, Urbana, Illinois, USA
| | - Erik Procko
- Department of Biochemistry, University of Illinois, Urbana, Illinois, USA; Cyrus Biotechnology, Seattle, Washington, USA.
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6
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Ippolito M, De Pascali F, Hopfinger N, Komolov KE, Laurinavichyute D, Reddy PAN, Sakkal LA, Rajkowski KZ, Nayak AP, Lee J, Lee J, Cao G, Donover PS, Reichman M, An SS, Salvino JM, Penn RB, Armen RS, Scott CP, Benovic JL. Identification of a β-arrestin-biased negative allosteric modulator for the β 2-adrenergic receptor. Proc Natl Acad Sci U S A 2023; 120:e2302668120. [PMID: 37490535 PMCID: PMC10401000 DOI: 10.1073/pnas.2302668120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Accepted: 06/26/2023] [Indexed: 07/27/2023] Open
Abstract
Catecholamine-stimulated β2-adrenergic receptor (β2AR) signaling via the canonical Gs-adenylyl cyclase-cAMP-PKA pathway regulates numerous physiological functions, including the therapeutic effects of exogenous β-agonists in the treatment of airway disease. β2AR signaling is tightly regulated by GRKs and β-arrestins, which together promote β2AR desensitization and internalization as well as downstream signaling, often antithetical to the canonical pathway. Thus, the ability to bias β2AR signaling toward the Gs pathway while avoiding β-arrestin-mediated effects may provide a strategy to improve the functional consequences of β2AR activation. Since attempts to develop Gs-biased agonists and allosteric modulators for the β2AR have been largely unsuccessful, here we screened small molecule libraries for allosteric modulators that selectively inhibit β-arrestin recruitment to the receptor. This screen identified several compounds that met this profile, and, of these, a difluorophenyl quinazoline (DFPQ) derivative was found to be a selective negative allosteric modulator of β-arrestin recruitment to the β2AR while having no effect on β2AR coupling to Gs. DFPQ effectively inhibits agonist-promoted phosphorylation and internalization of the β2AR and protects against the functional desensitization of β-agonist mediated regulation in cell and tissue models. The effects of DFPQ were also specific to the β2AR with minimal effects on the β1AR. Modeling, mutagenesis, and medicinal chemistry studies support DFPQ derivatives binding to an intracellular membrane-facing region of the β2AR, including residues within transmembrane domains 3 and 4 and intracellular loop 2. DFPQ thus represents a class of biased allosteric modulators that targets an allosteric site of the β2AR.
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Affiliation(s)
- Michael Ippolito
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA19107
| | - Francesco De Pascali
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA19107
| | - Nathan Hopfinger
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA19107
| | - Konstantin E. Komolov
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA19107
| | - Daniela Laurinavichyute
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA19107
| | | | - Leon A. Sakkal
- Department of Pharmaceutical Sciences, College of Pharmacy, Thomas Jefferson University, Philadelphia, PA19107
| | - Kyle Z. Rajkowski
- Department of Pharmaceutical Sciences, College of Pharmacy, Thomas Jefferson University, Philadelphia, PA19107
| | - Ajay P. Nayak
- Center for Translational Medicine, Department of Medicine, and Jane and Leonard Korman Respiratory Institute, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA19107
| | - Justin Lee
- Rutgers Institute for Translational Medicine and Science, New Brunswick, NJ08901
| | - Jordan Lee
- Rutgers Institute for Translational Medicine and Science, New Brunswick, NJ08901
| | - Gaoyuan Cao
- Rutgers Institute for Translational Medicine and Science, New Brunswick, NJ08901
| | | | | | - Steven S. An
- Rutgers Institute for Translational Medicine and Science, New Brunswick, NJ08901
- Department of Pharmacology, Rutgers-Robert Wood Johnson Medical School, The State University of New Jersey, Piscataway, NJ08854
| | | | - Raymond B. Penn
- Center for Translational Medicine, Department of Medicine, and Jane and Leonard Korman Respiratory Institute, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA19107
| | - Roger S. Armen
- Department of Pharmaceutical Sciences, College of Pharmacy, Thomas Jefferson University, Philadelphia, PA19107
| | - Charles P. Scott
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA19107
| | - Jeffrey L. Benovic
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA19107
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7
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Abstract
Rhodopsin is the photoreceptor in human rod cells responsible for dim-light vision. The visual receptors are part of the large superfamily of G protein-coupled receptors (GPCRs) that mediate signal transduction in response to diverse diffusible ligands. The high level of sequence conservation within the transmembrane helices of the visual receptors and the family A GPCRs has long been considered evidence for a common pathway for signal transduction. I review recent studies that reveal a comprehensive mechanism for how light absorption by the retinylidene chromophore drives rhodopsin activation and highlight those features of the mechanism that are conserved across the ligand-activated GPCRs.
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Affiliation(s)
- Steven O Smith
- Department of Biochemistry and Cell Biology, Center for Structural Biology, Stony Brook University, Stony Brook, New York, USA;
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8
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Xu J, Pittenger C. The histamine H3 receptor modulates dopamine D2 receptor-dependent signaling pathways and mouse behaviors. J Biol Chem 2023; 299:104583. [PMID: 36871761 PMCID: PMC10139999 DOI: 10.1016/j.jbc.2023.104583] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2022] [Revised: 02/20/2023] [Accepted: 02/21/2023] [Indexed: 03/06/2023] Open
Abstract
The histamine H3 receptor (H3R) is highly enriched in the spiny projection neurons (SPNs) of the striatum, in both the D1 receptor (D1R)-expressing and D2 receptor (D2R)-expressing populations. A crossantagonistic interaction between H3R and D1R has been demonstrated in mice, both at the behavioral level and at the biochemical level. Although interactive behavioral effects have been described upon coactivation of H3R and D2R, the molecular mechanisms underlying this interaction are poorly understood. Here, we show that activation of H3R with the selective agonist R-(-)-α-methylhistamine dihydrobromide mitigates D2R agonist-induced locomotor activity and stereotypic behavior. Using biochemical approaches and the proximity ligation assay, we demonstrated the existence of an H3R-D2R complex in the mouse striatum. In addition, we examined consequences of simultaneous H3R-D2R agonism on the phosphorylation levels of several signaling molecules using immunohistochemistry. H3R agonist treatment modulated Akt (serine/threonine PKB)-glycogen synthase kinase 3 beta signaling in response to D2R activation via a β-arrestin 2-dependent mechanism in D2R-SPNs but not in D1R-SPNs. Phosphorylation of mitogen- and stress-activated protein kinase 1 and rpS6 (ribosomal protein S6) was largely unchanged under these conditions. As Akt-glycogen synthase kinase 3 beta signaling has been implicated in several neuropsychiatric disorders, this work may help clarify the role of H3R in modulating D2R function, leading to a better understanding of pathophysiology involving the interaction between histamine and dopamine systems.
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Affiliation(s)
- Jian Xu
- Department of Psychiatry, Yale University. ,
| | - Christopher Pittenger
- Department of Psychiatry, Yale University; Department of Psychology, Yale University; Department of Child Study Center, Yale University; Department of Interdepartmental Neuroscience Program, Yale University; Department of Wu-Tsai Institute, Yale University; Department of Center for Brain and Mind Health, Yale University.
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9
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Huh E, Agosto MA, Wensel TG, Lichtarge O. Coevolutionary signals in metabotropic glutamate receptors capture residue contacts and long-range functional interactions. J Biol Chem 2023; 299:103030. [PMID: 36806686 PMCID: PMC10060750 DOI: 10.1016/j.jbc.2023.103030] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 02/09/2023] [Accepted: 02/10/2023] [Indexed: 02/18/2023] Open
Abstract
Upon ligand binding to a G protein-coupled receptor, extracellular signals are transmitted into a cell through sets of residue interactions that translate ligand binding into structural rearrangements. These interactions needed for functions impose evolutionary constraints so that, on occasion, mutations in one position may be compensated by other mutations at functionally coupled positions. To quantify the impact of amino acid substitutions in the context of major evolutionary divergence in the G protein-coupled receptor subfamily of metabotropic glutamate receptors (mGluRs), we combined two phylogenetic-based algorithms, Evolutionary Trace and covariation Evolutionary Trace, to infer potential structure-function couplings and roles in mGluRs. We found a subset of evolutionarily important residues at known functional sites and evidence of coupling among distinct structural clusters in mGluR. In addition, experimental mutagenesis and functional assays confirmed that some highly covariant residues are coupled, revealing their synergy. Collectively, these findings inform a critical step toward understanding the molecular and structural basis of amino acid variation patterns within mGluRs and provide insight for drug development, protein engineering, and analysis of naturally occurring variants.
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Affiliation(s)
- Eunna Huh
- Department of Pharmacology and Chemical Biology, Baylor College of Medicine, Houston, Texas, USA
| | - Melina A Agosto
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, USA; Retina and Optic Nerve Research Laboratory, Department of Physiology and Biophysics, Dalhousie University, Halifax, Canada
| | - Theodore G Wensel
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, USA
| | - Olivier Lichtarge
- Department of Pharmacology and Chemical Biology, Baylor College of Medicine, Houston, Texas, USA; Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA.
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10
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Sloan DC, Cryan CE, Muntean BS. Multiple potassium channel tetramerization domain (KCTD) family members interact with Gβγ, with effects on cAMP signaling. J Biol Chem 2023; 299:102924. [PMID: 36736897 DOI: 10.1016/j.jbc.2023.102924] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 01/04/2023] [Accepted: 01/05/2023] [Indexed: 02/04/2023] Open
Abstract
G protein-coupled receptors (GPCRs) initiate an array of intracellular signaling programs by activating heterotrimeric G proteins (Gα and Gβγ subunits). Therefore, G protein modifiers are well positioned to shape GPCR pharmacology. A few members of the potassium channel tetramerization domain (KCTD) protein family have been found to adjust G protein signaling through interaction with Gβγ. However, comprehensive details on the KCTD interaction with Gβγ remain unresolved. Here, we report that nearly all the 25 KCTD proteins interact with Gβγ. In this study, we screened Gβγ interaction capacity across the entire KCTD family using two parallel approaches. In a live cell bioluminescence resonance energy transfer-based assay, we find that roughly half of KCTD proteins interact with Gβγ in an agonist-induced fashion, whereas all KCTD proteins except two were found to interact through coimmunoprecipitation. We observed that the interaction was dependent on an amino acid hot spot in the C terminus of KCTD2, KCTD5, and KCTD17. While KCTD2 and KCTD5 require both the Bric-à-brac, Tramtrack, Broad complex domain and C-terminal regions for Gβγ interaction, we uncovered that the KCTD17 C terminus is sufficient for Gβγ interaction. Finally, we demonstrated the functional consequence of the KCTD-Gβγ interaction by examining sensitization of the adenylyl cyclase-cAMP pathway in live cells. We found that Gβγ-mediated sensitization of adenylyl cyclase 5 was blunted by KCTD. We conclude that the KCTD family broadly engages Gβγ to shape GPCR signal transmission.
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11
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Fahmy K, Sakmar TP. Interdisciplinary biophysical studies of membrane proteins bacteriorhodopsin and rhodopsin. Biophys Rev 2023; 15:111-25. [PMID: 36909961 DOI: 10.1007/s12551-022-01003-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Accepted: 09/28/2022] [Indexed: 10/10/2022] Open
Abstract
The centenary of the birth of H. Gobind Khorana provides an auspicious opportunity to review the origins and evolution of parallel advances in biophysical methodology and molecular genetics technology used to study membrane proteins. Interdisciplinary work in the Khorana laboratory in the late 1970s and for the next three decades led to productive collaborations and fostered three subsequent scientific generations whose biophysical work on membrane proteins has led to detailed elucidation of the molecular mechanisms of energy transduction by the light-driven proton pump bacteriorhodopsin (bR) and signal transduction by the G protein-coupled receptor (GPCR) rhodopsin. This review will highlight the origins and advances of biophysical studies of membrane proteins made possible by the application of molecular genetics approaches to engineer site-specific alterations of membrane protein structures.
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Lala T, Doan JK, Takatsu H, Hartzell HC, Shin HW, Hall RA. Phosphatidylserine exposure modulates adhesion GPCR BAI1 (ADGRB1) signaling activity. J Biol Chem 2022; 298:102685. [PMID: 36370845 PMCID: PMC9723945 DOI: 10.1016/j.jbc.2022.102685] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 10/28/2022] [Accepted: 10/31/2022] [Indexed: 11/10/2022] Open
Abstract
Brain-specific angiogenesis inhibitor 1 (BAI1; also called ADGRB1 or B1) is an adhesion G protein-coupled receptor known from studies on macrophages to bind to phosphatidylserine (PS) on apoptotic cells via its N-terminal thrombospondin repeats. A separate body of work has shown that B1 regulates postsynaptic function and dendritic spine morphology via signaling pathways involving Rac and Rho. However, it is unknown if PS binding by B1 has any effect on the receptor's signaling activity. To shed light on this subject, we studied G protein-dependent signaling by B1 in the absence and presence of coexpression with the PS flippase ATP11A in human embryonic kidney 293T cells. ATP11A expression reduced the amount of PS exposed extracellularly and also strikingly reduced the signaling activity of coexpressed full-length B1 but not a truncated version of the receptor lacking the thrombospondin repeats. Further experiments with an inactive mutant of ATP11A showed that the PS flippase function of ATP11A was required for modulation of B1 signaling. In coimmunoprecipitation experiments, we made the surprising finding that ATP11A not only modulates B1 signaling but also forms complexes with B1. Parallel studies in which PS in the outer leaflet was reduced by an independent method, deletion of the gene encoding the endogenous lipid scramblase anoctamin 6 (ANO6), revealed that this manipulation also markedly reduced B1 signaling. These findings demonstrate that B1 signaling is modulated by PS exposure and suggest a model in which B1 serves as a PS sensor at synapses and in other cellular contexts.
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Affiliation(s)
- Trisha Lala
- Department of Pharmacology and Chemical Biology, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Juleva K Doan
- Department of Pharmacology and Chemical Biology, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Hiroyuki Takatsu
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto, Japan
| | - H Criss Hartzell
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Hye-Won Shin
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto, Japan
| | - Randy A Hall
- Department of Pharmacology and Chemical Biology, Emory University School of Medicine, Atlanta, Georgia, USA.
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Li Y, Sun J, Li D, Lin J. The full activation mechanism of the adenosine A 1 receptor revealed by GaMD and Su-GaMD simulations. Proc Natl Acad Sci U S A 2022; 119:e2203702119. [PMID: 36215480 DOI: 10.1073/pnas.2203702119] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The full activation process of G protein-coupled receptor (GPCR) plays an important role in cellular signal transduction. However, it remains challenging to simulate the whole process in which the GPCR is recognized and activated by a ligand and then couples to the G protein on a reasonable simulation timescale. Here, we developed a molecular dynamics (MD) approach named supervised (Su) Gaussian accelerated MD (GaMD) by incorporating a tabu-like supervision algorithm into a standard GaMD simulation. By using this Su-GaMD method, from the active and inactive structure of adenosine A1 receptor (A1R), we successfully revealed the full activation mechanism of A1R, including adenosine (Ado)-A1R recognition, preactivation of A1R, and A1R-G protein recognition, in hundreds of nanoseconds of simulations. The binding of Ado to the extracellular side of A1R initiates conformational changes and the preactivation of A1R. In turn, the binding of Gi2 to the intracellular side of A1R causes a decrease in the volume of the extracellular orthosteric site and stabilizes the binding of Ado to A1R. Su-GaMD could be a useful tool to reconstruct or even predict ligand-protein and protein-protein recognition pathways on a short timescale. The intermediate states revealed in this study could provide more detailed complementary structural characterizations to facilitate the drug design of A1R in the future.
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Huang Y, Rafael Guimarães T, Todd N, Ferguson C, Weiss KM, Stauffer FR, McDermott B, Hurtle BT, Saito T, Saido TC, MacDonald ML, Homanics GE, Thathiah A. G protein-biased GPR3 signaling ameliorates amyloid pathology in a preclinical Alzheimer's disease mouse model. Proc Natl Acad Sci U S A 2022; 119:e2204828119. [PMID: 36161942 DOI: 10.1073/pnas.2204828119] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Levels of the orphan G protein–coupled receptor GPR3 are elevated in a subset of patients with Alzheimer’s disease (AD). Our group previously showed that genetic deletion of Gpr3 attenuates amyloid-β (Aβ) pathology in multiple AD mouse models, highlighting the therapeutic potential of GPR3 as a drug target for AD. However, Gpr3-deficient mice display several adverse phenotypes, including anxiety-like behavior and cognitive deficits. Here, we genetically modified Gpr3 in naive mice and in a preclinical AD mouse model and demonstrated that biased GPR3 signaling reduces AD pathology and induces glial activation in the absence of an effect on basal anxiety levels or cognitive function. Thus, biased GPR3 therapeutics are potentially neuroprotective and a safer avenue for therapeutic intervention in AD. Biased G protein–coupled receptor (GPCR) ligands, which preferentially activate G protein or β-arrestin signaling pathways, are leading to the development of drugs with superior efficacy and reduced side effects in heart disease, pain management, and neuropsychiatric disorders. Although GPCRs are implicated in the pathophysiology of Alzheimer’s disease (AD), biased GPCR signaling is a largely unexplored area of investigation in AD. Our previous work demonstrated that GPR3-mediated β-arrestin signaling modulates amyloid-β (Aβ) generation in vitro and that Gpr3 deficiency ameliorates Aβ pathology in vivo. However, Gpr3-deficient mice display several adverse phenotypes, including elevated anxiety-like behavior, reduced fertility, and memory impairment, which are potentially associated with impaired G protein signaling. Here, we generated a G protein–biased GPR3 mouse model to investigate the physiological and pathophysiological consequences of selective elimination of GPR3-mediated β-arrestin signaling in vivo. In contrast to Gpr3-deficient mice, G protein–biased GPR3 mice do not display elevated anxiety levels, reduced fertility, or cognitive impairment. We further determined that G protein–biased signaling reduces soluble Aβ levels and leads to a decrease in the area and compaction of amyloid plaques in the preclinical AppNL-G-F AD mouse model. The changes in amyloid pathology are accompanied by robust microglial and astrocytic hypertrophy, which suggest a protective glial response that may limit amyloid plaque development in G protein–biased GPR3 AD mice. Collectively, these studies indicate that GPR3-mediated G protein and β-arrestin signaling produce discrete and separable effects and provide proof of concept for the development of safer GPCR-targeting therapeutics with more directed pharmacological action for AD.
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Massimi M, Di Pietro C, La Sala G, Matteoni R. Mouse Mutants of Gpr37 and Gpr37l1 Receptor Genes: Disease Modeling Applications. Int J Mol Sci 2022; 23:ijms23084288. [PMID: 35457105 PMCID: PMC9025225 DOI: 10.3390/ijms23084288] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Revised: 04/08/2022] [Accepted: 04/11/2022] [Indexed: 02/05/2023] Open
Abstract
The vertebrate G protein–coupled receptor 37 and G protein–coupled receptor 37-like 1 (GPR37 and GPR37L1) proteins have amino acid sequence homology to endothelin and bombesin-specific receptors. The prosaposin glycoprotein, its derived peptides, and analogues have been reported to interact with and activate both putative receptors. The GPR37 and GPR37L1 genes are highly expressed in human and rodent brains. GPR37 transcripts are most abundant in oligodendrocytes and in the neurons of the substantia nigra and hippocampus, while the GPR37L1 gene is markedly expressed in cerebellar Bergmann glia astrocytes. The human GPR37 protein is a substrate of parkin, and its insoluble form accumulates in brain samples from patients of inherited juvenile Parkinson’s disease. Several Gpr37 and Gpr37l1 mouse mutant strains have been produced and applied to extensive in vivo and ex vivo analyses of respective receptor functions and involvement in brain and other organ pathologies. The genotypic and phenotypic characteristics of the different mouse strains so far published are reported and discussed, and their current and proposed applications to human disease modeling are highlighted.
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Perez-Ternero C, Aubdool AA, Makwana R, Sanger GJ, Stimson RH, Chan LF, Moyes AJ, Hobbs AJ. C-type natriuretic peptide is a pivotal regulator of metabolic homeostasis. Proc Natl Acad Sci U S A 2022; 119:e2116470119. [PMID: 35333648 DOI: 10.1073/pnas.2116470119] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The global mortality, morbidity, and healthcare costs associated with cardiometabolic disease, including obesity, diabetes, hypertension, and dyslipidemia, are substantial and represent an expanding unmet medical need. Herein, we have identified a physiological role for C-type natriuretic peptide (CNP) in regulating key processes, including thermogenesis and adipogenesis, which combine to coordinate metabolic function and prevent the development of cardiometabolic disorders. This protective mechanism, which is in part mediated via an autocrine action of CNP on adipocytes, is underpinned by activation of cognate natriuretic peptide receptors (NPR)-B and NPR-C. This mechanism advances the fundamental understanding of energy homeostasis and glucose handling and offers the promise of improving the treatment of cardiometabolic disease. Thermogenesis and adipogenesis are tightly regulated mechanisms that maintain lipid homeostasis and energy balance; dysfunction of these critical processes underpins obesity and contributes to cardiometabolic disease. C-type natriuretic peptide (CNP) fulfills a multimodal protective role in the cardiovascular system governing local blood flow, angiogenesis, cardiac function, and immune cell reactivity. Herein, we investigated a parallel, preservative function for CNP in coordinating metabolic homeostasis. Global inducible CNP knockout mice exhibited reduced body weight, higher temperature, lower adiposity, and greater energy expenditure in vivo. This thermogenic phenotype was associated with increased expression of uncoupling protein-1 and preferential lipid utilization by mitochondria, a switch corroborated by a corresponding diminution of insulin secretion and glucose clearance. Complementary studies in isolated murine and human adipocytes revealed that CNP exerts these metabolic regulatory actions by inhibiting sympathetic thermogenic programming via Gi-coupled natriuretic peptide receptor (NPR)-C and reducing peroxisome proliferator-activated receptor-γ coactivator-1α expression, while concomitantly driving adipogenesis via NPR-B/protein kinase-G. Finally, we identified an association between CNP/NPR-C expression and obesity in patient samples. These findings establish a pivotal physiological role for CNP as a metabolic switch to balance energy homeostasis. Pharmacological targeting of these receptors may offer therapeutic utility in the metabolic syndrome and related cardiovascular disorders.
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Rubin LJ. It's Time to Put the Term "Pulmonary Vasodilators" to Rest. JACC Basic Transl Sci 2021; 6:870-871. [PMID: 34869950 PMCID: PMC8617593 DOI: 10.1016/j.jacbts.2021.10.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Affiliation(s)
- Lewis J. Rubin
- Department of Medicine, Columbia University Vagelos College of Physicians and Surgeons, New York, New York, USA
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Haubrich J, Font J, Quast RB, Goupil-Lamy A, Scholler P, Nevoltris D, Acher F, Chames P, Rondard P, Prézeau L, Pin JP. A nanobody activating metabotropic glutamate receptor 4 discriminates between homo- and heterodimers. Proc Natl Acad Sci U S A 2021; 118:e2105848118. [PMID: 34385321 DOI: 10.1073/pnas.2105848118] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
There is growing interest in developing biologics due to their high target selectivity. The G protein-coupled homo- and heterodimeric metabotropic glutamate (mGlu) receptors regulate many synapses and are promising targets for the treatment of numerous brain diseases. Although subtype-selective allosteric small molecules have been reported, their effects on the recently discovered heterodimeric receptors are often not known. Here, we describe a nanobody that specifically and fully activates homodimeric human mGlu4 receptors. Molecular modeling and mutagenesis studies revealed that the nanobody acts by stabilizing the closed active state of the glutamate binding domain by interacting with both lobes. In contrast, this nanobody does not activate the heterodimeric mGlu2-4 but acts as a pure positive allosteric modulator. These data further reveal how an antibody can fully activate a class C receptor and bring further evidence that nanobodies represent an alternative way to specifically control mGlu receptor subtypes.
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Knerr JM, Kledal TN, Rosenkilde MM. Molecular Properties and Therapeutic Targeting of the EBV-Encoded Receptor BILF1. Cancers (Basel) 2021; 13:4079. [PMID: 34439235 PMCID: PMC8392491 DOI: 10.3390/cancers13164079] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 08/05/2021] [Accepted: 08/09/2021] [Indexed: 12/12/2022] Open
Abstract
The γ-herpesvirus Epstein-Barr Virus (EBV) establishes lifelong infections in approximately 90% of adults worldwide. Up to 1,000,000 people yearly are estimated to suffer from health conditions attributed to the infection with this virus, such as nasopharyngeal and gastric carcinomas as well as several forms of B, T and NK cell lymphoma. To date, no EBV-specific therapeutic option has reached the market, greatly reducing the survival prognoses of affected patients. Similar to other herpesviruses, EBV encodes for a G protein-coupled receptor (GPCR), BILF1, affecting a multitude of cellular signaling pathways. BILF1 has been identified to promote immune evasion and tumorigenesis, effectively ensuring a life-long persistence of EBV in, and driving detrimental health conditions to its host. This review summarizes the epidemiology of EBV-associated malignancies, their current standard-of-care, EBV-specific therapeutics in development, GPCRs and their druggability, and most importantly consolidates the findings of over 15 years of research on BILF1 in the context of EBV-specific drug development. Taken together, BILF1 constitutes a promising target for the development of novel EBV-specific therapeutics.
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Affiliation(s)
- Julius Maximilian Knerr
- Laboratory for Molecular Pharmacology, Department of Biomedical Sciences, University of Copenhagen, 2200 København, Denmark;
| | | | - Mette Marie Rosenkilde
- Laboratory for Molecular Pharmacology, Department of Biomedical Sciences, University of Copenhagen, 2200 København, Denmark;
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Wang X, Cheng X, Zhao L, Wang Y, Ye C, Zou X, Dai A, Cong Z, Chen J, Zhou Q, Xia T, Jiang H, Xu HE, Yang D, Wang MW. Molecular insights into differentiated ligand recognition of the human parathyroid hormone receptor 2. Proc Natl Acad Sci U S A 2021; 118:e2101279118. [PMID: 34353904 DOI: 10.1073/pnas.2101279118] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The parathyroid hormone receptor 2 (PTH2R) is a class B1 G protein-coupled receptor (GPCR) involved in the regulation of calcium transport, nociception mediation, and wound healing. Naturally occurring mutations in PTH2R were reported to cause hereditary diseases, including syndromic short stature. Here, we report the cryogenic electron microscopy structure of PTH2R bound to its endogenous ligand, tuberoinfundibular peptide (TIP39), and a heterotrimeric Gs protein at a global resolution of 2.8 Å. The structure reveals that TIP39 adopts a unique loop conformation at the N terminus and deeply inserts into the orthosteric ligand-binding pocket in the transmembrane domain. Molecular dynamics simulation and site-directed mutagenesis studies uncover the basis of ligand specificity relative to three PTH2R agonists, TIP39, PTH, and PTH-related peptide. We also compare the action of TIP39 with an antagonist lacking six residues from the peptide N terminus, TIP(7-39), which underscores the indispensable role of the N terminus of TIP39 in PTH2R activation. Additionally, we unveil that a disease-associated mutation G258D significantly diminished cAMP accumulation induced by TIP39. Together, these results not only provide structural insights into ligand specificity and receptor activation of class B1 GPCRs but also offer a foundation to systematically rationalize the available pharmacological data to develop therapies for various disorders associated with PTH2R.
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Roy S, Chompunud Na Ayudhya C, Thapaliya M, Deepak V, Ali H. Multifaceted MRGPRX2: New insight into the role of mast cells in health and disease. J Allergy Clin Immunol 2021; 148:293-308. [PMID: 33957166 PMCID: PMC8355064 DOI: 10.1016/j.jaci.2021.03.049] [Citation(s) in RCA: 62] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 03/03/2021] [Accepted: 03/16/2021] [Indexed: 02/07/2023]
Abstract
Cutaneous mast cells (MCs) express Mas-related G protein-coupled receptor-X2 (MRGPRX2; mouse ortholog MrgprB2), which is activated by an ever-increasing number of cationic ligands. Antimicrobial host defense peptides (HDPs) generated by keratinocytes contribute to host defense likely by 2 mechanisms, one involving direct killing of microbes and the other via MC activation through MRGPRX2. However, its inappropriate activation may cause pseudoallergy and likely contribute to the pathogenesis of rosacea, atopic dermatitis, allergic contact dermatitis, urticaria, and mastocytosis. Gain- and loss-of-function missense single nucleotide polymorphisms in MRGPRX2 have been identified. The ability of certain ligands to serve as balanced or G protein-biased agonists has been defined. Small-molecule HDP mimetics that display both direct antimicrobial activity and activate MCs via MRGPRX2 have been developed. In addition, antibodies and reagents that modulate MRGPRX2 expression and signaling have been generated. In this article, we provide a comprehensive update on MrgprB2 and MRGPRX2 biology. We propose that harnessing MRGPRX2's host defense function by small-molecule HDP mimetics may provide a novel approach for the treatment of antibiotic-resistant cutaneous infections. In contrast, MRGPRX2-specific antibodies and inhibitors could be used for the modulation of allergic and inflammatory diseases that are mediated via this receptor.
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Affiliation(s)
- Saptarshi Roy
- Department of Basic and Translational Sciences, University of Pennsylvania, School of Dental Medicine, Philadelphia, Pa
| | - Chalatip Chompunud Na Ayudhya
- Department of Basic and Translational Sciences, University of Pennsylvania, School of Dental Medicine, Philadelphia, Pa
| | - Monica Thapaliya
- Department of Basic and Translational Sciences, University of Pennsylvania, School of Dental Medicine, Philadelphia, Pa
| | - Vishwa Deepak
- Department of Basic and Translational Sciences, University of Pennsylvania, School of Dental Medicine, Philadelphia, Pa
| | - Hydar Ali
- Department of Basic and Translational Sciences, University of Pennsylvania, School of Dental Medicine, Philadelphia, Pa.
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Wu N, Olechwier AM, Brunner C, Edwards PC, Tsai CJ, Tate CG, Schertler GFX, Schneider G, Deupi X, Zenobi R, Ma P. High-mass MALDI-MS unravels ligand-mediated G protein-coupling selectivity to GPCRs. Proc Natl Acad Sci U S A 2021; 118:e2024146118. [PMID: 34326250 DOI: 10.1073/pnas.2024146118] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
G protein–coupled receptors (GPCRs) are important pharmaceutical targets for the treatment of a broad spectrum of diseases. Upon ligand binding, GPCRs initiate intracellular signaling pathways by interacting with partner proteins. Assays that quantify the interplay between ligand binding and initiation of downstream signaling cascades are critical in the early stages of drug development. We have developed a high-throughput mass spectrometry method to unravel GPCR–protein complex interplay and demonstrated its use with three GPCRs to provide quantitative information about ligand-modulated coupling selectivity. This method provides insights into the molecular details of GPCR interactions and could serve as an approach for discovery of drugs that initiate specific cell-signaling pathways. G protein–coupled receptors (GPCRs) are important pharmaceutical targets for the treatment of a broad spectrum of diseases. Although there are structures of GPCRs in their active conformation with bound ligands and G proteins, the detailed molecular interplay between the receptors and their signaling partners remains challenging to decipher. To address this, we developed a high-sensitivity, high-throughput matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) method to interrogate the first stage of signal transduction. GPCR–G protein complex formation is detected as a proxy for the effect of ligands on GPCR conformation and on coupling selectivity. Over 70 ligand–GPCR–partner protein combinations were studied using as little as 1.25 pmol protein per sample. We determined the selectivity profile and binding affinities of three GPCRs (rhodopsin, beta-1 adrenergic receptor [β1AR], and angiotensin II type 1 receptor) to engineered Gα-proteins (mGs, mGo, mGi, and mGq) and nanobody 80 (Nb80). We found that GPCRs in the absence of ligand can bind mGo, and that the role of the G protein C terminus in GPCR recognition is receptor-specific. We exemplified our quantification method using β1AR and demonstrated the allosteric effect of Nb80 binding in assisting displacement of nadolol to isoprenaline. We also quantified complex formation with wild-type heterotrimeric Gαiβγ and β-arrestin-1 and showed that carvedilol induces an increase in coupling of β-arrestin-1 and Gαiβγ to β1AR. A normalization strategy allows us to quantitatively measure the binding affinities of GPCRs to partner proteins. We anticipate that this methodology will find broad use in screening and characterization of GPCR-targeting drugs.
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Tian M, Wu Z, Heng J, Chen F, Guan W, Zhang S. Novel advances in understanding fatty acid-binding G protein-coupled receptors and their roles in controlling energy balance. Nutr Rev 2021; 80:187-199. [PMID: 34027989 DOI: 10.1093/nutrit/nuab021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Revised: 01/10/2021] [Accepted: 03/03/2021] [Indexed: 12/13/2022] Open
Abstract
Diabetes, obesity, and other metabolic diseases have been recognized as the main factors that endanger human health worldwide. Most of these metabolic syndromes develop when the energy balance in the body is disrupted. Energy balance depends upon the systemic regulation of food intake, glucose homeostasis, and lipid metabolism. Fatty acid-binding G protein-coupled receptors (GPCRs) are widely expressed in various types of tissues and cells involved in energy homeostasis regulation. In this review, the distribution and biological functions of fatty acid-binding GPCRs are summarized, particularly with respect to the gut, pancreas, and adipose tissue. A systematic understanding of the physiological functions of the fatty acid-binding GPCRs involved in energy homeostasis regulation will help in identifying novel pharmacological targets for metabolic diseases.
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Affiliation(s)
- Min Tian
- M. Tian, Z. Wu, J. Heng, F. Chen, W. Guan, and S. Zhang are with the Guangdong Province Key Laboratory of Animal Nutrition Control, College of Animal Science, South China Agricultural University, Guangzhou, China. F. Chen, W. Guan, and S. Zhang are with the College of Animal Science and National Engineering Research Center for Breeding Swine Industry, and the Guangdong Laboratory for Lingnan Modern Agriculture, South China Agricultural University, Guangzhou, China
| | - Zhihui Wu
- M. Tian, Z. Wu, J. Heng, F. Chen, W. Guan, and S. Zhang are with the Guangdong Province Key Laboratory of Animal Nutrition Control, College of Animal Science, South China Agricultural University, Guangzhou, China. F. Chen, W. Guan, and S. Zhang are with the College of Animal Science and National Engineering Research Center for Breeding Swine Industry, and the Guangdong Laboratory for Lingnan Modern Agriculture, South China Agricultural University, Guangzhou, China
| | - Jinghui Heng
- M. Tian, Z. Wu, J. Heng, F. Chen, W. Guan, and S. Zhang are with the Guangdong Province Key Laboratory of Animal Nutrition Control, College of Animal Science, South China Agricultural University, Guangzhou, China. F. Chen, W. Guan, and S. Zhang are with the College of Animal Science and National Engineering Research Center for Breeding Swine Industry, and the Guangdong Laboratory for Lingnan Modern Agriculture, South China Agricultural University, Guangzhou, China
| | - Fang Chen
- M. Tian, Z. Wu, J. Heng, F. Chen, W. Guan, and S. Zhang are with the Guangdong Province Key Laboratory of Animal Nutrition Control, College of Animal Science, South China Agricultural University, Guangzhou, China. F. Chen, W. Guan, and S. Zhang are with the College of Animal Science and National Engineering Research Center for Breeding Swine Industry, and the Guangdong Laboratory for Lingnan Modern Agriculture, South China Agricultural University, Guangzhou, China
| | - Wutai Guan
- M. Tian, Z. Wu, J. Heng, F. Chen, W. Guan, and S. Zhang are with the Guangdong Province Key Laboratory of Animal Nutrition Control, College of Animal Science, South China Agricultural University, Guangzhou, China. F. Chen, W. Guan, and S. Zhang are with the College of Animal Science and National Engineering Research Center for Breeding Swine Industry, and the Guangdong Laboratory for Lingnan Modern Agriculture, South China Agricultural University, Guangzhou, China
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Khater M, Bryant CN, Wu G. Gβγ translocation to the Golgi apparatus activates ARF1 to spatiotemporally regulate G protein-coupled receptor signaling to MAPK. J Biol Chem 2021; 296:100805. [PMID: 34022220 PMCID: PMC8215300 DOI: 10.1016/j.jbc.2021.100805] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 05/11/2021] [Accepted: 05/18/2021] [Indexed: 01/01/2023] Open
Abstract
After activation of G protein-coupled receptors, G protein βγ dimers may translocate from the plasma membrane to the Golgi apparatus (GA). We recently report that this translocation activates extracellular signal-regulated protein kinases 1 and 2 (ERK1/2) via PI3Kγ; however, how Gβγ-PI3Kγ activates the ERK1/2 pathway is unclear. Here, we demonstrate that chemokine receptor CXCR4 activates ADP-ribosylation factor 1 (ARF1), a small GTPase important for vesicle-mediated membrane trafficking. This activation is blocked by CRISPR-Cas9-mediated knockout of the GA-translocating Gγ9 subunit. Inducible targeting of different Gβγ dimers to the GA can directly activate ARF1. CXCR4 activation and constitutive Gβγ recruitment to the GA also enhance ARF1 translocation to the GA. We further demonstrate that pharmacological inhibition and CRISPR-Cas9-mediated knockout of PI3Kγ markedly inhibit CXCR4-mediated and Gβγ translocation-mediated ARF1 activation. We also show that depletion of ARF1 by siRNA and CRISPR-Cas9 and inhibition of GA-localized ARF1 activation abolish ERK1/2 activation by CXCR4 and Gβγ translocation to the GA and suppress prostate cancer PC3 cell migration and invasion. Collectively, our data reveal a novel function for Gβγ translocation to the GA to activate ARF1 and identify GA-localized ARF1 as an effector acting downstream of Gβγ-PI3Kγ to spatiotemporally regulate G protein-coupled receptor signaling to mitogen-activated protein kinases.
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Affiliation(s)
- Mostafa Khater
- Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, Augusta, Georgia, USA
| | - Christian N Bryant
- Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, Augusta, Georgia, USA
| | - Guangyu Wu
- Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, Augusta, Georgia, USA.
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Pronin A, Slepak V. Ectopically expressed olfactory receptors OR51E1 and OR51E2 suppress proliferation and promote cell death in a prostate cancer cell line. J Biol Chem 2021; 296:100475. [PMID: 33640452 PMCID: PMC8024707 DOI: 10.1016/j.jbc.2021.100475] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Revised: 02/21/2021] [Accepted: 02/24/2021] [Indexed: 02/07/2023] Open
Abstract
Olfactory receptors (ORs), the largest family of G protein–coupled receptors, are expressed in the nasal epithelium where they mediate the sense of smell. However, ORs are also found in other non-nasal tissues, but the role of these ectopic ORs in cell signaling, proliferation, and survival is not well understood. Here, using an inducible expression system in the lymph node carcinoma of the prostate (LNCaP) cell line, we investigated two ectopic ORs, OR51E1 and OR51E2, which have been shown to be upregulated in prostate cancer. We found that, consistent with previous studies, OR51E1 stimulated adenylyl cyclase in response to treatment by short-chain to medium-chain organic acids (C3–C9) but not by acetate. OR51E2 responded to acetate and propionate but not to the longer chain organic acids. Stimulation of LNCaP cells with butyrate inhibited their growth, and the knockdown of the endogenous OR51E1 negated this cytostatic effect. Most significantly, overexpression of OR51E1 or OR51E2 suppressed LNCaP cell proliferation. Overexpression of another ectopic OR OR2AT4, β2-adrenergic receptor, or treatment of cells with forskolin did not suppress cell proliferation, indicating that a rise in cAMP is not sufficient to induce cytostasis. Overexpression of OR51E1 caused an upregulation of cytostatic and cell death markers including p27, p21, and p53, strongly increased annexin V staining, and stimulated extracellular signal–regulated protein kinases 1 and 2. Overexpression and/or activation of OR51E1 did not affect human embryonic kidney 293 cell proliferation, indicating that cytotoxicity of OR51E1/OR51E2 is specific for LNCaP cells. Together, our results further our understanding of prostate cancer etiology and suggest that ectopic ORs may be useful therapeutic targets.
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Affiliation(s)
- Alexey Pronin
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida, USA.
| | - Vladlen Slepak
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida, USA.
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26
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Kennedy C. That was then, this is now: the development of our knowledge and understanding of P2 receptor subtypes. Purinergic Signal 2021; 17:9-23. [PMID: 33527235 DOI: 10.1007/s11302-021-09763-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Accepted: 01/06/2021] [Indexed: 11/17/2022] Open
Abstract
P2 receptors are present in virtually all tissues and cell types in the human body, and they mediate the physiological and pharmacological actions of extracellular purine and pyrimidine nucleotides. They were first characterised and named by Geoff Burnstock in 1978, then subdivided into P2X and P2Y purinoceptors in 1985 on the basis of pharmacological criteria in functional studies on native receptors. Molecular cloning of receptors in the 1990s revealed P2X receptors to comprise seven different subunits that interact to produce functional homo- and heterotrimeric ligand-gated cation channels. A family of eight P2Y G protein–coupled receptors were also cloned, which can form homo- and heterodimers. Deep insight into the molecular mechanisms of agonist and antagonist action has been provided by more recent determination of the tertiary and quaternary structures of several P2X and P2Y receptor subtypes. Agonists and antagonists that are highly selective for individual subtypes are now available and some are in clinical use. This has all come about because of the intelligence, insight and drive of the force of nature that was Geoff Burnstock.
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Khater M, Wei Z, Xu X, Huang W, Lokeshwar BL, Lambert NA, Wu G. G protein βγ translocation to the Golgi apparatus activates MAPK via p110γ-p101 heterodimers. J Biol Chem 2021; 296:100325. [PMID: 33493514 PMCID: PMC7949113 DOI: 10.1016/j.jbc.2021.100325] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 01/11/2021] [Accepted: 01/19/2021] [Indexed: 01/14/2023] Open
Abstract
The Golgi apparatus (GA) is a cellular organelle that plays a critical role in the processing of proteins for secretion. Activation of G protein-coupled receptors at the plasma membrane (PM) induces the translocation of G protein βγ dimers to the GA. However, the functional significance of this translocation is largely unknown. Here, we study PM-GA translocation of all 12 Gγ subunits in response to chemokine receptor CXCR4 activation and demonstrate that Gγ9 is a unique Golgi-translocating Gγ subunit. CRISPR-Cas9-mediated knockout of Gγ9 abolishes activation of extracellular signal-regulated kinase 1 and 2 (ERK1/2), two members of the mitogen-activated protein kinase family, by CXCR4. We show that chemically induced recruitment to the GA of Gβγ dimers containing different Gγ subunits activates ERK1/2, whereas recruitment to the PM is ineffective. We also demonstrate that pharmacological inhibition of phosphoinositide 3-kinase γ (PI3Kγ) and depletion of its subunits p110γ and p101 abrogate ERK1/2 activation by CXCR4 and Gβγ recruitment to the GA. Knockout of either Gγ9 or PI3Kγ significantly suppresses prostate cancer PC3 cell migration, invasion, and metastasis. Collectively, our data demonstrate a novel function for Gβγ translocation to the GA, via activating PI3Kγ heterodimers p110γ-p101, to spatiotemporally regulate mitogen-activated protein kinase activation by G protein-coupled receptors and ultimately control tumor progression.
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Affiliation(s)
- Mostafa Khater
- Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, Augusta, Georgia, USA
| | - Zhe Wei
- Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, Augusta, Georgia, USA
| | - Xin Xu
- Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, Augusta, Georgia, USA
| | - Wei Huang
- Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, Augusta, Georgia, USA
| | - Bal L Lokeshwar
- Georgia Cancer Center, Augusta University, Augusta, Georgia, USA
| | - Nevin A Lambert
- Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, Augusta, Georgia, USA
| | - Guangyu Wu
- Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, Augusta, Georgia, USA.
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28
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Mukai S, Mizokami A, Otani T, Sano T, Matsuda M, Chishaki S, Gao J, Kawakubo-Yasukochi T, Tang R, Kanematsu T, Takeuchi H, Jimi E, Hirata M. Adipocyte-specific GPRC6A ablation promotes diet-induced obesity by inhibiting lipolysis. J Biol Chem 2021; 296:100274. [PMID: 33428938 PMCID: PMC7949034 DOI: 10.1016/j.jbc.2021.100274] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 12/22/2020] [Accepted: 01/07/2021] [Indexed: 12/17/2022] Open
Abstract
The G protein–coupled receptor GPRC6A regulates various physiological processes in response to its interaction with multiple ligands, such as extracellular basic amino acids, divalent cations, testosterone, and the uncarboxylated form of osteocalcin (GluOC). Global ablation of GPRC6A increases the susceptibility of mice to diet-induced obesity and related metabolic disorders. However, given that GPRC6A is expressed in many tissues and responds to a variety of hormonal and nutritional signals, the cellular and molecular mechanisms underlying the development of metabolic disorders in conventional knockout mice have remained unclear. On the basis of our previous observation that long-term oral administration of GluOC markedly reduced adipocyte size and improved glucose tolerance in WT mice, we examined whether GPRC6A signaling in adipose tissue might be responsible for prevention of metabolic disorders. We thus generated adipocyte-specific GPRC6A knockout mice, and we found that these animals manifested increased adipose tissue weight, adipocyte hypertrophy, and adipose tissue inflammation when fed a high-fat and high-sucrose diet compared with control mice. These effects were associated with reduced lipolytic activity because of downregulation of lipolytic enzymes such as adipose triglyceride lipase and hormone-sensitive lipase in adipose tissue of the conditional knockout mice. Given that, among GPR6CA ligands tested, GluOC and ornithine increased the expression of adipose triglyceride lipase in cultured 3T3-L1 adipocytes in a manner dependent on GPRC6A, our results suggest that the constitutive activation of GPRC6A signaling in adipocytes by GluOC or ornithine plays a key role in adipose lipid handling and the prevention of obesity and related metabolic disorders.
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Affiliation(s)
- Satoru Mukai
- OBT Research Center, Faculty of Dental Science, Kyushu University, Fukuoka, Japan; Department of Health and Nutrition care, Faculty of Allied Health Sciences, University of East Asia, Shimonoseki, Japan
| | - Akiko Mizokami
- OBT Research Center, Faculty of Dental Science, Kyushu University, Fukuoka, Japan.
| | - Takahito Otani
- Division of Functional Structure, Department of Morphological Biology, Fukuoka Dental College, Fukuoka, Japan
| | - Tomomi Sano
- Department of Cell Biology and Pharmacology, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
| | - Miho Matsuda
- Laboratory of Molecular and Cellular Biochemistry, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
| | - Sakura Chishaki
- OBT Research Center, Faculty of Dental Science, Kyushu University, Fukuoka, Japan; Laboratory of Molecular and Cellular Biochemistry, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
| | - Jing Gao
- Laboratory of Molecular and Cellular Biochemistry, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
| | | | - Ronghao Tang
- Laboratory of Molecular and Cellular Biochemistry, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
| | - Takashi Kanematsu
- Department of Cell Biology and Pharmacology, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
| | - Hiroshi Takeuchi
- Division of Applied Pharmacology, Kyushu Dental University, Kitakyushu, Japan
| | - Eijiro Jimi
- OBT Research Center, Faculty of Dental Science, Kyushu University, Fukuoka, Japan; Laboratory of Molecular and Cellular Biochemistry, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
| | - Masato Hirata
- Oral Medicine Research Center, Fukuoka Dental College, Fukuoka, Japan.
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29
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Rowe JB, Kapolka NJ, Taghon GJ, Morgan WM, Isom DG. The evolution and mechanism of GPCR proton sensing. J Biol Chem 2021; 296:100167. [PMID: 33478938 PMCID: PMC7948426 DOI: 10.1074/jbc.ra120.016352] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Revised: 12/02/2020] [Accepted: 12/09/2020] [Indexed: 12/13/2022] Open
Abstract
Of the 800 G protein-coupled receptors (GPCRs) in humans, only three (GPR4, GPR65, and GPR68) regulate signaling in acidified microenvironments by sensing protons (H+). How these receptors have uniquely obtained this ability is unknown. Here, we show these receptors evolved the capability to sense H+ signals by acquiring buried acidic residues. Using our informatics platform pHinder, we identified a triad of buried acidic residues shared by all three receptors, a feature distinct from all other human GPCRs. Phylogenetic analysis shows the triad emerged in GPR65, the immediate ancestor of GPR4 and GPR68. To understand the evolutionary and mechanistic importance of these triad residues, we developed deep variant profiling, a yeast-based technology that utilizes high-throughput CRISPR to build and profile large libraries of GPCR variants. Using deep variant profiling and GPCR assays in HEK293 cells, we assessed the pH-sensing contributions of each triad residue in all three receptors. As predicted by our calculations, most triad mutations had profound effects consistent with direct regulation of receptor pH sensing. In addition, we found that an allosteric modulator of many class A GPCRs, Na+, synergistically regulated pH sensing by maintaining the pKa values of triad residues within the physiologically relevant pH range. As such, we show that all three receptors function as coincidence detectors of H+ and Na+. Taken together, these findings elucidate the molecular evolution and long-sought mechanism of GPR4, GPR65, and GPR68 pH sensing and provide pH-insensitive variants that should be valuable for assessing the therapeutic potential and (patho)physiological importance of GPCR pH sensing.
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Affiliation(s)
- Jacob B Rowe
- The Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Nicholas J Kapolka
- The Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Geoffrey J Taghon
- The Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - William M Morgan
- The Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Daniel G Isom
- The Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida, USA; The Department of Tumor Biology, University of Miami Sylvester Comprehensive Cancer Center, Miami, Florida, USA; The Institute for Data Science Computing, University of Miami, Coral Gables, Florida, USA.
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30
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Sasaki T, Watanabe Y, Kuboyama A, Oikawa A, Shimizu M, Yamauchi Y, Sato R. Muscle-specific TGR5 overexpression improves glucose clearance in glucose-intolerant mice. J Biol Chem 2021; 296:100131. [PMID: 33262218 PMCID: PMC7949087 DOI: 10.1074/jbc.ra120.016203] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2020] [Revised: 11/09/2020] [Accepted: 12/01/2020] [Indexed: 01/05/2023] Open
Abstract
TGR5, a G protein-coupled bile acid receptor, is expressed in various tissues and regulates several physiological processes. In the skeletal muscle, TGR5 activation is known to induce muscle hypertrophy; however, the effects on glucose and lipid metabolism are not well understood, despite the fact that the skeletal muscle plays a major role in energy metabolism. Here, we demonstrate that skeletal muscle-specific TGR5 transgenic (Tg) mice exhibit increased glucose utilization, without altering the expression of major genes related to glucose and lipid metabolism. Metabolite profiling analysis by capillary electrophoresis time-of-flight mass spectrometry showed that glycolytic flux was activated in the skeletal muscle of Tg mice, leading to an increase in glucose utilization. Upon long-term, high-fat diet challenge, blood glucose clearance was improved in Tg mice without an accompanying increase in insulin sensitivity in skeletal muscle and a reduction of body weight. Moreover, Tg mice showed improved age-associated glucose intolerance. These results strongly suggest that TGR5 ameliorated glucose metabolism disorder that is caused by diet-induced obesity and aging by enhancing the glucose metabolic capacity of the skeletal muscle. Our study demonstrates that TGR5 activation in the skeletal muscle is effective in improving glucose metabolism and may be beneficial in developing a novel strategy for the prevention or treatment of hyperglycemia.
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Affiliation(s)
- Takashi Sasaki
- Food Biochemistry Laboratory, Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo, Japan.
| | - Yuichi Watanabe
- Food Biochemistry Laboratory, Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo, Japan
| | - Ayane Kuboyama
- Food Biochemistry Laboratory, Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo, Japan
| | - Akira Oikawa
- RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa, Japan; Faculty of Agriculture, Yamagata University, Tsuruoka, Yamagata, Japan
| | - Makoto Shimizu
- Nutri-Life Science Laboratory, Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo, Japan
| | - Yoshio Yamauchi
- Food Biochemistry Laboratory, Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo, Japan
| | - Ryuichiro Sato
- Food Biochemistry Laboratory, Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo, Japan; Nutri-Life Science Laboratory, Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo, Japan; AMED-CREST, Japan Agency for Medical Research and Development, Tokyo, Japan.
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31
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Ceraudo E, Horioka M, Mattheisen JM, Hitchman TD, Moore AR, Kazmi MA, Chi P, Chen Y, Sakmar TP, Huber T. Direct evidence that the GPCR CysLTR2 mutant causative of uveal melanoma is constitutively active with highly biased signaling. J Biol Chem 2020; 296:100163. [PMID: 33288675 PMCID: PMC7948404 DOI: 10.1074/jbc.ra120.015352] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 12/02/2020] [Accepted: 12/06/2020] [Indexed: 12/14/2022] Open
Abstract
Uveal melanoma is the most common eye cancer in adults and is clinically and genetically distinct from skin cutaneous melanoma. In a subset of cases, the oncogenic driver is an activating mutation in CYSLTR2, the gene encoding the G protein-coupled receptor cysteinyl-leukotriene receptor 2 (CysLTR2). The mutant CYSLTR2 encodes for the CysLTR2-L129Q receptor, with the substitution of Leu to Gln at position 129 (3.43). The ability of CysLTR2-L129Q to cause malignant transformation has been hypothesized to result from constitutive activity, but how the receptor could escape desensitization is unknown. Here, we characterize the functional properties of CysLTR2-L129Q. We show that CysLTR2-L129Q is a constitutively active mutant that strongly drives Gq/11 signaling pathways. However, CysLTR2-L129Q only poorly recruits β-arrestin. Using a modified Slack-Hall operational model, we quantified the constitutive activity for both pathways and conclude that CysLTR2-L129Q displays profound signaling bias for Gq/11 signaling pathways while escaping β-arrestin-mediated downregulation. CYSLTR2 is the first known example of a G protein-coupled receptor driver oncogene that encodes a highly biased constitutively active mutant receptor. These results provide new insights into the mechanism of CysLTR2-L129Q oncoprotein signaling and suggest CYSLTR2 as a promising potential therapeutic target in uveal melanoma.
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Affiliation(s)
- Emilie Ceraudo
- Laboratory of Chemical Biology and Signal Transduction, The Rockefeller University, New York, New York, USA
| | - Mizuho Horioka
- Laboratory of Chemical Biology and Signal Transduction, The Rockefeller University, New York, New York, USA; Tri-Institutional PhD Program in Chemical Biology, New York, New York, USA
| | - Jordan M Mattheisen
- Laboratory of Chemical Biology and Signal Transduction, The Rockefeller University, New York, New York, USA; Tri-Institutional PhD Program in Chemical Biology, New York, New York, USA
| | - Tyler D Hitchman
- Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, New York, USA; Louis V. Gerstner Jr. Graduate School of Biomedical Sciences, Memorial Sloan Kettering Cancer Center, New York, New York, USA
| | - Amanda R Moore
- Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, New York, USA; Weill Cornell Graduate School of Medical Sciences, Cornell University, New York, New York, USA
| | - Manija A Kazmi
- Laboratory of Chemical Biology and Signal Transduction, The Rockefeller University, New York, New York, USA
| | - Ping Chi
- Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, New York, USA; Louis V. Gerstner Jr. Graduate School of Biomedical Sciences, Memorial Sloan Kettering Cancer Center, New York, New York, USA; Weill Cornell Graduate School of Medical Sciences, Cornell University, New York, New York, USA; Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, New York, USA; Department of Medicine, Weill Cornell Medical College, New York, New York, USA
| | - Yu Chen
- Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, New York, USA; Louis V. Gerstner Jr. Graduate School of Biomedical Sciences, Memorial Sloan Kettering Cancer Center, New York, New York, USA; Weill Cornell Graduate School of Medical Sciences, Cornell University, New York, New York, USA; Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, New York, USA; Department of Medicine, Weill Cornell Medical College, New York, New York, USA
| | - Thomas P Sakmar
- Laboratory of Chemical Biology and Signal Transduction, The Rockefeller University, New York, New York, USA; Division of Neurogeriatrics, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Solna, Sweden.
| | - Thomas Huber
- Laboratory of Chemical Biology and Signal Transduction, The Rockefeller University, New York, New York, USA.
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32
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Parandeh F, Amisten S, Verma G, Mohammed Al-Amily I, Dunér P, Salehi A. Inhibitory effect of UDP-glucose on cAMP generation and insulin secretion. J Biol Chem 2020; 295:15245-15252. [PMID: 32855238 DOI: 10.1074/jbc.ra120.012929] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Revised: 08/21/2020] [Indexed: 12/27/2022] Open
Abstract
Type-2 diabetes (T2D) is a global disease caused by the inability of pancreatic β-cells to secrete adequate insulin. However, the molecular mechanisms underlying the failure of β-cells to respond to glucose in T2D remains unknown. Here, we investigated the relative contribution of UDP-glucose (UDP-G), a P2Y14-specific agonist, in the regulation of insulin release using human isolated pancreatic islets and INS-1 cells. P2Y14 was expressed in both human and rodent pancreatic β-cells. Dose-dependent activation of P2Y14 by UDP-G suppressed glucose-stimulated insulin secretion (GSIS) and knockdown of P2Y14 abolished the UDP-G effect. 12-h pretreatment of human islets with pertussis-toxin (PTX) improved GSIS and prevented the inhibitory effect of UDP-G on GSIS. UDP-G on GSIS suppression was associated with suppression of cAMP in INS-1 cells. UDP-G decreased the reductive capacity of nondiabetic human islets cultured at 5 mm glucose for 72 h and exacerbated the negative effect of 20 mm glucose on the cell viability during culture period. T2D donor islets displayed a lower reductive capacity when cultured at 5 mm glucose for 72 h that was further decreased in the presence of 20 mm glucose and UDP-G. Presence of a nonmetabolizable cAMP analog during culture period counteracted the effect of glucose and UDP-G. Islet cultures at 20 mm glucose increased apoptosis, which was further amplified when UDP-G was present. UDP-G modulated glucose-induced proliferation of INS-1 cells. The data provide intriguing evidence for P2Y14 and UDP-G's role in the regulation of pancreatic β-cell function.
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Affiliation(s)
- Fariborz Parandeh
- Department of Clinical Science, Division of Islet Cell Physiology, UMAS University of Lund, Malmö, Sweden
| | - Stefan Amisten
- Department of Clinical Science, Division of Islet Cell Physiology, UMAS University of Lund, Malmö, Sweden
| | - Gaurav Verma
- Department of Clinical Science, Division of Islet Cell Physiology, UMAS University of Lund, Malmö, Sweden
| | - Israa Mohammed Al-Amily
- Department of Clinical Science, Division of Islet Cell Physiology, UMAS University of Lund, Malmö, Sweden
| | - Pontus Dunér
- Experimental Cardiovascular Research Unit Clinical Research Centre, UMAS University of Lund, Malmö, Sweden
| | - Albert Salehi
- Department of Clinical Science, Division of Islet Cell Physiology, UMAS University of Lund, Malmö, Sweden.
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33
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Cai X, Wang H, Wang M, Wang D, Zhang Z, Wei R, Gao X, Zhang R, Wang C, Chen J. A novel phosphorylation site on orexin receptor 1 regulating orexinA-induced GRK2-biased signaling. Cell Signal 2020; 75:109743. [PMID: 32827691 DOI: 10.1016/j.cellsig.2020.109743] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 08/15/2020] [Accepted: 08/17/2020] [Indexed: 11/24/2022]
Abstract
Drug discovery efforts targeting G protein-coupled receptors (GPCRs) have succeeded in developing multiple medications for treating various human diseases including cancer, metabolic disorders, and inflammatory disorders. These medications are broadly classified as either agonists or antagonists that respectively promote or inhibit receptor activation by endogenous stimuli. However, there has been a growing appreciation that GPCR biased signaling between G protein- and β-arrestin-dependent signaling in particular is a promising method for improving drug efficacy and therapy. Orexin receptor 1 (OX1R), a member of the GPCRs, is an important drug target in the central nervous system. In this study, we identified a novel regulatory phosphorylation site (Ser-262) on OX1R that abolished its capability to interact with GRK2, but did not affect its interaction with G proteins, GRK5, or β-arrestin1/2 activation, indicating that Ser-262 is a key amino acid for OX1R internalization that contributes to induction of GRK2-dependent biased signaling via orexin A. Our findings could potentially lead to the development of new drug targets for the prevention and treatment of insomnia, narcolepsy, and substance abuse, with fewer side effects than existing therapies.
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Affiliation(s)
- Xin Cai
- School of Clinical Medicine, Weifang Medical University, Weifang, Shandong, 261042, PR China
| | - Huannan Wang
- Neurobiology Institute, Jining Medical University, Jining, Shandong, 272067, PR China; School of Pharmacy, Jining Medical University, Rizhao, Shandong, 276800, PR China
| | - Maochang Wang
- Shouguang Agricultural Development Group Co., Ltd,Shouguang, Shandong, 262700, PR China
| | - Dexiu Wang
- School of Clinical Medicine, Weifang Medical University, Weifang, Shandong, 261042, PR China
| | - Zhen Zhang
- School of Pharmacy, Jining Medical University, Rizhao, Shandong, 276800, PR China
| | - Ruotong Wei
- School of Clinical Medicine, Weifang Medical University, Weifang, Shandong, 261042, PR China
| | - Xiang Gao
- School of Clinical Medicine, Weifang Medical University, Weifang, Shandong, 261042, PR China
| | - Rumin Zhang
- Neurobiology Institute, Jining Medical University, Jining, Shandong, 272067, PR China
| | - Chunmei Wang
- Neurobiology Institute, Jining Medical University, Jining, Shandong, 272067, PR China
| | - Jing Chen
- Neurobiology Institute, Jining Medical University, Jining, Shandong, 272067, PR China; Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, CV4 7AL, UK.
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Abstract
The mu opioid receptor (MOR) is a diversely regulated target for the alleviation of pain in the clinical setting. However, untoward side effects such as tolerance, dependence, respiratory suppression, constipation, and abuse liability detract from the general activation of these receptors. Studies in genetically modified rodent models suggest that activating G protein signaling pathways while avoiding phosphorylation of the receptor or recruitment of β-arrestin scaffolding proteins could preserve the analgesic properties of MOR agonists while avoiding certain side effects. With the development of novel MOR "biased" agonists, which lead to preferential activation of G protein pathways over receptor phosphorylation, internalization, or interaction with other effectors, this hypothesis can be tested in a native, physiological setting. Overall, it is clear that the MOR is not a simple on-off switch and that the diverse means by which the receptor can be regulated may present an opportunity to refine therapeutics for the treatment of pain.
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Affiliation(s)
- Travis W Grim
- Departments of Molecular Medicine and Neuroscience, the Scripps Research Institute, Jupiter, Florida
| | - Agnes Acevedo-Canabal
- Departments of Molecular Medicine and Neuroscience, the Scripps Research Institute, Jupiter, Florida
| | - Laura M Bohn
- Departments of Molecular Medicine and Neuroscience, the Scripps Research Institute, Jupiter, Florida.
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35
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Abstract
Since the isolation of morphine from the opium poppy over 200 years ago, the molecular basis of opioid action has remained the subject of intense inquiry. The identification of specific receptors responsible for opioid function and the discovery of many chemically diverse molecules with unique opioid-like efficacies have provided glimpses into the molecular logic of opioid action. Recent revolutions in the structural biology of transmembrane proteins have, for the first time, yielded high-resolution views into the 3-dimensional shapes of all 4 opioid receptors. These studies have begun to decode the chemical logic that enables opioids to specifically bind and activate their receptor targets. A combination of spectroscopic experiments and computational simulations has provided a view into the molecular movements of the opioid receptors, which itself gives rise to the complex opioid pharmacology observed at the cellular and behavioral levels. Further diversity in opioid receptor structure is driven by both genetic variation and receptor oligomerization. These insights have enabled computational drug discovery efforts, with some evidence of success in the design of completely novel opioids with unique efficacies. The combined progress over the past few years provides hope for new, efficacious opioids devoid of the side effects that have made them the scourge of humanity for millennia.
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Abstract
Enteroendocrine cells (EECs) in the intestine regulate many aspects of whole-body physiology and metabolism. EECs sense luminal and circulating nutrients and respond by secreting hormones that act on multiple organs and organ systems, such as the brain, gallbladder, and pancreas, to control satiety, digestion, and glucose homeostasis. In addition, EECs act locally, on enteric neurons, endothelial cells, and the gastrointestinal epithelium, to facilitate digestion and absorption of nutrients. Many recent reports raise the possibility that EECs and the enteric nervous system may coordinate to regulate gastrointestinal functions. Loss of all EECs results in chronic malabsorptive diarrhea, placing EECs in a central role regulating nutrient absorption in the gut. Because there is increasing evidence that EECs can directly modulate the efficiency of nutrient absorption, it is possible that EECs are master regulators of a feed-forward loop connecting appetite, digestion, metabolism, and abnormally augmented nutrient absorption that perpetuates metabolic disease. This review focuses on the roles that specific EEC hormones play on glucose, peptide, and lipid absorption within the intestine.
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Affiliation(s)
- Heather A McCauley
- Division of Developmental Biology and the Center for Stem Cell and Organoid Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
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37
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Goshima Y, Masukawa D, Kasahara Y, Hashimoto T, Aladeokin AC. l-DOPA and Its Receptor GPR143: Implications for Pathogenesis and Therapy in Parkinson's Disease. Front Pharmacol 2019; 10:1119. [PMID: 31632270 PMCID: PMC6785630 DOI: 10.3389/fphar.2019.01119] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2019] [Accepted: 08/30/2019] [Indexed: 01/26/2023] Open
Abstract
l-3,4-Dihydroxyphenylalanine (l-DOPA) is the most effective therapeutic agent for Parkinson's disease (PD). l-DOPA is traditionally believed to be an inert amino acid that exerts actions and effectiveness in PD through its conversion to dopamine. In contrast to this generally accepted idea, l-DOPA is proposed to be a neurotransmitter. Recently, GPR143 (OA1), the gene product of ocular albinism 1 was identified as a receptor candidate for l-DOPA. GPR143 is widely expressed in the central and peripheral nervous system. GPR143 immunoreactivity was colocalized with phosphorylated α-synuclein in Lewy bodies in PD brains. GPR143 may contribute to the therapeutic effectiveness of l-DOPA and might be related to pathogenesis of PD.
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Affiliation(s)
- Yoshio Goshima
- Department of Molecular Pharmacology & Neurobiology, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Daiki Masukawa
- Department of Molecular Pharmacology & Neurobiology, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Yuka Kasahara
- Department of Molecular Pharmacology & Neurobiology, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Tatsuo Hashimoto
- Department of Molecular Pharmacology & Neurobiology, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Aderemi Caleb Aladeokin
- Department of Molecular Pharmacology & Neurobiology, Yokohama City University Graduate School of Medicine, Yokohama, Japan
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Tomko A, O'Leary L, Trask H, Achenbach JC, Hall SR, Goralski KB, Ellis LD, Dupré DJ. Antitumor Activity of Abnormal Cannabidiol and Its Analog O-1602 in Taxol-Resistant Preclinical Models of Breast Cancer. Front Pharmacol 2019; 10:1124. [PMID: 31611800 PMCID: PMC6777324 DOI: 10.3389/fphar.2019.01124] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Accepted: 08/30/2019] [Indexed: 12/31/2022] Open
Abstract
Cannabinoids exhibit anti-inflammatory and antitumorigenic properties. Contrary to most cannabinoids present in the Cannabis plant, some, such as O-1602 and abnormal cannabidiol, have no or only little affinity to the CB1 or CB2 cannabinoid receptors and instead exert their effects through other receptors. Here, we investigated whether the synthetic regioisomers of cannabidiol, abnormal cannabidiol, and a closely related compound, O-1602, display antitumorigenic effects in cellular models of breast cancer and whether it could reduce tumorigenesis in vivo. Several studies have shown the effects of cannabinoids on chemotherapy-sensitive breast cancer cell lines, but less is known about the antitumorigenic effects of cannabinoids in chemotherapy-resistant cell lines. Paclitaxel-resistant MDA-MB-231 and MCF-7 breast cancer cell lines were used to study the effect of O-1602 and abnormal cannabidiol on viability, apoptosis, and migration. The effects of O-1602 and abnormal cannabidiol on cell viability were completely blocked by the combination of GPR55 and GPR18-specific siRNAs. Both O-1602 and abnormal cannabidiol decreased viability in paclitaxel-resistant breast cancer cells in a concentration-dependent manner through induction of apoptosis. The effect of these cannabinoids on tumor growth in vivo was studied in a zebrafish xenograft model. In this model, treatment with O-1602 and abnormal cannabidiol (2 µM) significantly reduced tumor growth. Our results suggest that atypical cannabinoids, like O-1602 and abnormal cannabidiol, exert antitumorigenic effects on paclitaxel-resistant breast cancer cells. Due to their lack of central sedation and psychoactive effects, these atypical cannabinoids could represent new leads for the development of additional anticancer treatments when resistance to conventional chemotherapy occurs during the treatment of breast and possibly other cancers.
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Affiliation(s)
- Andrea Tomko
- Department of Pharmacology, Faculty of Medicine, Dalhousie University, Halifax, Canada
| | - Lauren O'Leary
- Department of Pharmacology, Faculty of Medicine, Dalhousie University, Halifax, Canada
| | - Hilary Trask
- Department of Pharmacology, Faculty of Medicine, Dalhousie University, Halifax, Canada
| | - John C Achenbach
- Aquatic and Crop Resource Development Research Center, National Research Council of Canada, Halifax, Canada
| | - Steven R Hall
- Department of Pharmacology, Faculty of Medicine, Dalhousie University, Halifax, Canada.,College of Pharmacy, Faculty of Health, Dalhousie University, Halifax, Canada
| | - Kerry B Goralski
- Department of Pharmacology, Faculty of Medicine, Dalhousie University, Halifax, Canada.,College of Pharmacy, Faculty of Health, Dalhousie University, Halifax, Canada
| | - Lee D Ellis
- College of Pharmacy, Faculty of Health, Dalhousie University, Halifax, Canada
| | - Denis J Dupré
- Department of Pharmacology, Faculty of Medicine, Dalhousie University, Halifax, Canada
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Abstract
G protein-coupled receptors (GPCRs) mediate the majority of cellular responses to external stimuli. Upon activation by a ligand, the receptor binds to a partner heterotrimeric G protein and promotes exchange of GTP for GDP, leading to dissociation of the G protein into α and βγ subunits that mediate downstream signals. GPCRs can also activate distinct signaling pathways through arrestins. Active states of GPCRs form by small rearrangements of the ligand-binding, or orthosteric, site that are amplified into larger conformational changes. Molecular understanding of the allosteric coupling between ligand binding and G protein or arrestin interaction is emerging from structures of several GPCRs crystallized in inactive and active states, spectroscopic data, and computer simulations. The coupling is loose, rather than concerted, and agonist binding does not fully stabilize the receptor in an active conformation. Distinct intermediates whose populations are shifted by ligands of different efficacies underlie the complex pharmacology of GPCRs.
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Affiliation(s)
- William I Weis
- Department of Structural Biology, Stanford University School of Medicine, Stanford, California 94305, USA; .,Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, California 94305, USA;
| | - Brian K Kobilka
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, California 94305, USA;
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40
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Abstract
Heterotrimeric GTP-binding proteins are key regulators of a multitude of signaling pathways in all eukaryotes. Although the core G-protein components and their basic biochemistries are broadly conserved throughout evolution, the regulatory mechanisms of G proteins seem to have been rewired in plants to meet specific needs. These proteins are currently the focus of intense research in plants due to their involvement in many agronomically important traits, such as seed yield, organ size regulation, biotic and abiotic stress responses, symbiosis, and nitrogen use efficiency. The availability of massive sequence information from a variety of plant species, extensive biochemical data generated over decades, and impressive genetic resources for plant G proteins have made it possible to examine their role, unique properties, and novel regulation. This review focuses on some recent advances in our understanding of the mechanistic details of this critical signaling pathway to enable the precise manipulation and generation of plants to meet future needs.
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Affiliation(s)
- Sona Pandey
- Donald Danforth Plant Science Center, St. Louis, Missouri 63132, USA;
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41
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Abstract
In recent years, cryo electron microscopy (cryo-EM) technology has been transformed with the development of better instrumentation, direct electron detectors, improved methods for specimen preparation, and improved software for data analysis. Analyses using single-particle cryo-EM methods have enabled determination of structures of proteins with sizes smaller than 100 kDa and resolutions of ∼2 Å in some cases. The use of electron tomography combined with subvolume averaging is beginning to allow the visualization of macromolecular complexes in their native environment in unprecedented detail. As a result of these advances, solutions to many intractable challenges in structural and cell biology, such as analysis of highly dynamic soluble and membrane-embedded protein complexes or partially ordered protein aggregates, are now within reach. Recent reports of structural studies of G protein-coupled receptors, spliceosomes, and fibrillar specimens illustrate the progress that has been made using cryo-EM methods, and are the main focus of this review.
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Affiliation(s)
- Jana Ognjenović
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland 20814, USA; ,
| | - Reinhard Grisshammer
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland 20814, USA; ,
| | - Sriram Subramaniam
- University of British Columbia, Vancouver, British Columbia V6T 1Z2, Canada;
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Liutkevičiūtė Z, Gil-Mansilla E, Eder T, Casillas-Pérez B, Di Giglio MG, Muratspahić E, Grebien F, Rattei T, Muttenthaler M, Cremer S, Gruber CW. Oxytocin-like signaling in ants influences metabolic gene expression and locomotor activity. FASEB J 2018; 32:fj201800443. [PMID: 29939785 PMCID: PMC6174076 DOI: 10.1096/fj.201800443] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Ants are emerging model systems to study cellular signaling because distinct castes possess different physiologic phenotypes within the same colony. Here we studied the functionality of inotocin signaling, an insect ortholog of mammalian oxytocin (OT), which was recently discovered in ants. In Lasius ants, we determined that specialization within the colony, seasonal factors, and physiologic conditions down-regulated the expression of the OT-like signaling system. Given this natural variation, we interrogated its function using RNAi knockdowns. Next-generation RNA sequencing of OT-like precursor knock-down ants highlighted its role in the regulation of genes involved in metabolism. Knock-down ants exhibited higher walking activity and increased self-grooming in the brood chamber. We propose that OT-like signaling in ants is important for regulating metabolic processes and locomotion.-Liutkevičiūtė, Z., Gil-Mansilla, E., Eder, T., Casillas-Pérez, B., Di Giglio, M. G., Muratspahić, E., Grebien, F., Rattei, T., Muttenthaler, M., Cremer, S., Gruber, C. W. Oxytocin-like signaling in ants influences metabolic gene expression and locomotor activity.
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Affiliation(s)
- Zita Liutkevičiūtė
- Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Esther Gil-Mansilla
- Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Thomas Eder
- Division of Computational Systems Biology (CUBE), Department of Microbiology and Ecosystem Science, University of Vienna, Vienna, Austria
- Ludwig Boltzmann Institute for Cancer Research, Vienna, Austria
| | | | | | - Edin Muratspahić
- Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Florian Grebien
- Ludwig Boltzmann Institute for Cancer Research, Vienna, Austria
| | - Thomas Rattei
- Division of Computational Systems Biology (CUBE), Department of Microbiology and Ecosystem Science, University of Vienna, Vienna, Austria
| | - Markus Muttenthaler
- Institute for Molecular Biosciences, The University of Queensland, St. Lucia, Queensland, Australia; and
- Faculty of Chemistry, Institute of Biological Chemistry, University of Vienna, Vienna, Austria
| | - Sylvia Cremer
- Institute of Science and Technology (IST) Austria, Klosterneuburg, Austria
| | - Christian W Gruber
- Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
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43
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Chan EC, Ren C, Xie Z, Jude J, Barker T, Koziol-White CA, Ma M, Panettieri RA, Wu D, Rosenberg HF, Druey KM. Regulator of G protein signaling 5 restricts neutrophil chemotaxis and trafficking. J Biol Chem 2018; 293:12690-12702. [PMID: 29929985 DOI: 10.1074/jbc.ra118.002404] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Revised: 06/14/2018] [Indexed: 01/09/2023] Open
Abstract
Neutrophils are white blood cells that are mobilized to damaged tissues and to sites of pathogen invasion, providing the first line of host defense. Chemokines displayed on the surface of blood vessels promote migration of neutrophils to these sites, and tissue- and pathogen-derived chemoattractant signals, including N-formylmethionylleucylphenylalanine (fMLP), elicit further migration to sites of infection. Although nearly all chemoattractant receptors use heterotrimeric G proteins to transmit signals, many of the mechanisms lying downstream of chemoattractant receptors that either promote or limit neutrophil motility are incompletely defined. Here, we show that regulator of G protein signaling 5 (RGS5), a protein that modulates G protein activity, is expressed in both human and murine neutrophils. We detected significantly more neutrophils in the airways of Rgs5-/- mice than WT counterparts following acute respiratory virus infection and in the peritoneum in response to injection of thioglycollate, a biochemical proinflammatory stimulus. RGS5-deficient neutrophils responded with increased chemotaxis elicited by the chemokines CXC motif chemokine ligand 1 (CXCL1), CXCL2, and CXCL12 but not fMLP. Moreover, adhesion of these cells was increased in the presence of both CXCL2 and fMLP. In summary, our results indicate that RGS5 deficiency increases chemotaxis and adhesion, leading to more efficient neutrophil mobilization to inflamed tissues in mice. These findings suggest that RGS5 expression and activity in neutrophils determine their migrational patterns in the complex microenvironments characteristic of inflamed tissues.
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Affiliation(s)
- Eunice C Chan
- Molecular Signal Transduction Section, NIAID, National Institutes of Health, Bethesda, Maryland 20892
| | - Chunguang Ren
- Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut 06510
| | - Zhihui Xie
- Molecular Signal Transduction Section, NIAID, National Institutes of Health, Bethesda, Maryland 20892
| | - Joseph Jude
- Rutgers Institute for Translational Medicine and Science, Child Health Institute of New Jersey, Rutgers New Jersey School of Medicine, Rutgers, New Jersey 07103
| | - Tolga Barker
- Molecular Signal Transduction Section, NIAID, National Institutes of Health, Bethesda, Maryland 20892
| | - Cynthia A Koziol-White
- Rutgers Institute for Translational Medicine and Science, Child Health Institute of New Jersey, Rutgers New Jersey School of Medicine, Rutgers, New Jersey 07103
| | - Michelle Ma
- Inflammation Immunobiology Section, NIAID, National Institutes of Health, Bethesda, Maryland 20892
| | - Reynold A Panettieri
- Rutgers Institute for Translational Medicine and Science, Child Health Institute of New Jersey, Rutgers New Jersey School of Medicine, Rutgers, New Jersey 07103
| | - Dianqing Wu
- Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut 06510
| | - Helene F Rosenberg
- Inflammation Immunobiology Section, NIAID, National Institutes of Health, Bethesda, Maryland 20892
| | - Kirk M Druey
- Molecular Signal Transduction Section, NIAID, National Institutes of Health, Bethesda, Maryland 20892.
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44
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Abstract
G protein-coupled receptors (GPCRs) represent a large superfamily of membrane proteins that mediate cell signaling and regulate a variety of physiological processes in the human body. Structure-function studies of this superfamily were enabled a decade ago by multiple breakthroughs in technology that included receptor stabilization, crystallization in a membrane environment, and microcrystallography. The recent emergence of X-ray free-electron lasers (XFELs) has further accelerated structural studies of GPCRs and other challenging proteins by overcoming radiation damage and providing access to high-resolution structures and dynamics using micrometer-sized crystals. Here, we summarize key technology advancements and major milestones of GPCR research using XFELs and provide a brief outlook on future developments in the field.
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Affiliation(s)
- Benjamin Stauch
- Department of Chemistry and Bridge Institute, University of Southern California, Los Angeles, California 90089, USA; ,
| | - Vadim Cherezov
- Department of Chemistry and Bridge Institute, University of Southern California, Los Angeles, California 90089, USA; ,
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45
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Abstract
G protein-coupled receptors (GPCRs), which mediate processes as diverse as olfaction and maintenance of metabolic homeostasis, have become the single most effective class of therapeutic drug targets. As a result, understanding the molecular basis for their activity is of paramount importance. Recent technological advances have made GPCR structural biology increasingly tractable, offering views of these receptors in unprecedented atomic detail. Structural and biophysical data have shown that GPCRs function as complex allosteric machines, communicating ligand-binding events through conformational change. Changes in receptor conformation lead to activation of effector proteins, such as G proteins and arrestins, which are themselves conformational switches. Here, we review how structural biology has illuminated the agonist-induced cascade of conformational changes that culminate in a cellular response to GPCR activation.
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Affiliation(s)
- Sarah C Erlandson
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, USA;
| | - Conor McMahon
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, USA;
| | - Andrew C Kruse
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, USA;
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46
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Senarath K, Payton JL, Kankanamge D, Siripurapu P, Tennakoon M, Karunarathne A. Gγ identity dictates efficacy of Gβγ signaling and macrophage migration. J Biol Chem 2018; 293:2974-2989. [PMID: 29317505 DOI: 10.1074/jbc.ra117.000872] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Revised: 01/04/2018] [Indexed: 11/06/2022] Open
Abstract
G protein βγ subunit (Gβγ) is a major signal transducer and controls processes ranging from cell migration to gene transcription. Despite having significant subtype heterogeneity and exhibiting diverse cell- and tissue-specific expression levels, Gβγ is often considered a unified signaling entity with a defined functionality. However, the molecular and mechanistic basis of Gβγ's signaling specificity is unknown. Here, we demonstrate that Gγ subunits, bearing the sole plasma membrane (PM)-anchoring motif, control the PM affinity of Gβγ and thereby differentially modulate Gβγ effector signaling in a Gγ-specific manner. Both Gβγ signaling activity and the migration rate of macrophages are strongly dependent on the PM affinity of Gγ. We also found that the type of C-terminal prenylation and five to six pre-CaaX motif residues at the PM-interacting region of Gγ control the PM affinity of Gβγ. We further show that the overall PM affinity of the Gβγ pool of a cell type is a strong predictor of its Gβγ signaling-activation efficacy. A kinetic model encompassing multiple Gγ types and parameterized for empirical Gβγ behaviors not only recapitulated experimentally observed signaling of Gβγ, but also suggested a Gγ-dependent, active-inactive conformational switch for the PM-bound Gβγ, regulating effector signaling. Overall, our results unveil crucial aspects of signaling and cell migration regulation by Gγ type-specific PM affinities of Gβγ.
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Affiliation(s)
- Kanishka Senarath
- Department of Chemistry and Biochemistry, The University of Toledo, Toledo, Ohio 43606
| | - John L Payton
- Department of Chemistry and Biochemistry, The University of Toledo, Toledo, Ohio 43606
| | - Dinesh Kankanamge
- Department of Chemistry and Biochemistry, The University of Toledo, Toledo, Ohio 43606
| | - Praneeth Siripurapu
- Department of Chemistry and Biochemistry, The University of Toledo, Toledo, Ohio 43606
| | - Mithila Tennakoon
- Department of Chemistry and Biochemistry, The University of Toledo, Toledo, Ohio 43606
| | - Ajith Karunarathne
- Department of Chemistry and Biochemistry, The University of Toledo, Toledo, Ohio 43606.
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Grotegut CA, Ngan E, Garrett ME, Miranda ML, Ashley-Koch AE, Swamy GK. The association of single-nucleotide polymorphisms in the oxytocin receptor and G protein-coupled receptor kinase 6 (GRK6) genes with oxytocin dosing requirements and labor outcomes. Am J Obstet Gynecol 2017; 217:367.e1-367.e9. [PMID: 28526450 DOI: 10.1016/j.ajog.2017.05.023] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Accepted: 05/09/2017] [Indexed: 01/01/2023]
Abstract
BACKGROUND Oxytocin is a potent uterotonic agent that is widely used for induction and augmentation of labor. Oxytocin has a narrow therapeutic index and the optimal dosing for any individual woman varies widely. OBJECTIVE The objective of this study was to determine whether genetic variation in the oxytocin receptor (OXTR) or in the gene encoding G protein-coupled receptor kinase 6 (GRK6), which regulates desensitization of the oxytocin receptor, could explain variation in oxytocin dosing and labor outcomes among women being induced near term. STUDY DESIGN Pregnant women with a singleton gestation residing in Durham County, NC, were prospectively enrolled as part of the Healthy Pregnancy, Healthy Baby cohort study. Those women undergoing an induction of labor at 36 weeks or greater were genotyped for 18 haplotype-tagging single-nucleotide polymorphisms in OXTR and 7 haplotype-tagging single-nucleotide polymorphisms in GRK6 using TaqMan assays. Linear regression was used to examine the relationship between maternal genotype and maximal oxytocin infusion rate, total oxytocin dose received, and duration of labor. Logistic regression was used to test for the association of maternal genotype with mode of delivery. For each outcome, backward selection techniques were utilized to control for important confounding variables and additive genetic models were used. Race/ethnicity was included in all models because of differences in allele frequencies across populations, and Bonferroni correction for multiple testing was used. RESULTS DNA was available from 482 women undergoing induction of labor at 36 weeks or greater. Eighteen haplotype-tagging single-nucleotide polymorphisms within OXTR and 7 haplotype-tagging single-nucleotide polymorphisms within GRK6 were examined. Five single-nucleotide polymorphisms in OXTR showed nominal significance with maximal infusion rate of oxytocin, and two single-nucleotide polymorphisms in OXTR were associated with total oxytocin dose received. One single-nucleotide polymorphism in OXTR and two single-nucleotide polymorphisms in GRK6 were associated with duration of labor, one of which met the multiple testing threshold (P = .0014, rs2731664 [GRK6], mean duration of labor, 17.7 hours vs 20.2 hours vs 23.5 hours for AA, AC, and CC genotypes, respectively). Three single-nucleotide polymorphisms, two in OXTR and one in GRK6, showed nominal significance with mode of delivery. CONCLUSION Genetic variation in OXTR and GRK6 is associated with the amount of oxytocin required as well as the duration of labor and risk for cesarean delivery among women undergoing induction of labor near term. With further research, pharmacogenomic approaches may potentially be utilized to develop personalized treatment to improve safety and efficacy outcomes among women undergoing induction of labor.
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Affiliation(s)
- Chad A Grotegut
- Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Duke University, Durham, NC.
| | - Emily Ngan
- School of Medicine, Duke University, Durham, NC
| | | | - Marie Lynn Miranda
- Department of Pediatrics, Duke University, Durham, NC; Office of the Provost, Rice University, Houston, TX
| | | | - Geeta K Swamy
- Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Duke University, Durham, NC
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48
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Abstract
Chemokines and their cell surface G protein-coupled receptors are critical for cell migration, not only in many fundamental biological processes but also in inflammatory diseases and cancer. Recent X-ray structures of two chemokines complexed with full-length receptors provided unprecedented insight into the atomic details of chemokine recognition and receptor activation, and computational modeling informed by new experiments leverages these insights to gain understanding of many more receptor:chemokine pairs. In parallel, chemokine receptor structures with small molecules reveal the complicated and diverse structural foundations of small molecule antagonism and allostery, highlight the inherent physicochemical challenges of receptor:chemokine interfaces, and suggest novel epitopes that can be exploited to overcome these challenges. The structures and models promote unique understanding of chemokine receptor biology, including the interpretation of two decades of experimental studies, and will undoubtedly assist future drug discovery endeavors.
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Affiliation(s)
- Irina Kufareva
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, California 92093; ,
| | - Martin Gustavsson
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, California 92093; ,
| | - Yi Zheng
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, California 92093; ,
| | - Bryan S Stephens
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, California 92093; ,
| | - Tracy M Handel
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, California 92093; ,
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49
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Abstract
Neuropeptides are by far the largest and most diverse group of signaling molecules in multicellular organisms. They are ancient molecules important in regulating a multitude of processes. Their small proteinaceous character allowed them to evolve and radiate quickly into numerous different molecules. On average, hundreds of distinct neuropeptides are present in animals, sometimes with unique classes that do not occur in distantly related species. Acting as neurotransmitters, neuromodulators, hormones, or growth factors, they are extremely diverse and are involved in controlling growth, development, ecdysis, digestion, diuresis, and many more physiological processes. Neuropeptides are also crucial in regulating myriad behavioral actions associated with feeding, courtship, sleep, learning and memory, stress, addiction, and social interactions. In general, behavior ensures that an organism can survive in its environment and is defined as any action that can change an organism's relationship to its surroundings. Even though the mode of action of neuropeptides in insects has been vigorously studied, relatively little is known about most neuropeptides and only a few model insects have been investigated. Here, we provide an overview of the roles neuropeptides play in insect behavior. We conclude that multiple neuropeptides need to work in concert to coordinate certain behaviors. Additionally, most neuropeptides studied to date have more than a single function.
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Affiliation(s)
- Liliane Schoofs
- Functional Genomics and Proteomics Group, Department of Biology, KU Leuven, 3000 Leuven, Belgium; , ,
| | - Arnold De Loof
- Functional Genomics and Proteomics Group, Department of Biology, KU Leuven, 3000 Leuven, Belgium; , ,
| | - Matthias Boris Van Hiel
- Functional Genomics and Proteomics Group, Department of Biology, KU Leuven, 3000 Leuven, Belgium; , ,
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50
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Abstract
Ligand-induced activation of G protein-coupled receptors (GPCRs) is a key mechanism permitting communication between cells and organs. Enormous progress has recently elucidated the structural and dynamic features of GPCR transmembrane signaling. Nanobodies, the recombinant antigen-binding fragments of camelid heavy-chain-only antibodies, have emerged as important research tools to lock GPCRs in particular conformational states. Active-state stabilizing nanobodies have elucidated several agonist-bound structures of hormone-activated GPCRs and have provided insight into the dynamic character of receptors. Nanobodies have also been used to stabilize transient GPCR transmembrane signaling complexes, yielding the first structural insights into GPCR signal transduction across the cellular membrane. Beyond their in vitro uses, nanobodies have served as conformational biosensors in living systems and have provided novel ways to modulate GPCR function. Here, we highlight several examples of how nanobodies have enabled the study of GPCR function and give insights into potential future uses of these important tools.
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Affiliation(s)
- Aashish Manglik
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, California 94305; ,
| | - Brian K Kobilka
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, California 94305; ,
| | - Jan Steyaert
- Structural Biology Brussels, Vrije Universiteit Brussel, 1050 Brussels, Belgium;
- VIB Structural Biology Research Center, Vrije Universiteit Brussel, 1050 Brussels, Belgium
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