1
|
McNeill SM, Zhao P. The roles of RGS proteins in cardiometabolic disease. Br J Pharmacol 2024; 181:2319-2337. [PMID: 36964984 DOI: 10.1111/bph.16076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Revised: 02/12/2023] [Accepted: 03/20/2023] [Indexed: 03/27/2023] Open
Abstract
G protein-coupled receptors (GPCRs) are the most prominent receptors on the surface of the cell and play a central role in the regulation of cardiac and metabolic functions. GPCRs transmit extracellular stimuli to the interior of the cells by activating one or more heterotrimeric G proteins. The duration and intensity of G protein-mediated signalling are tightly controlled by a large array of intracellular mediators, including the regulator of G protein signalling (RGS) proteins. RGS proteins selectively promote the GTPase activity of a subset of Gα subunits, thus serving as negative regulators in a pathway-dependent manner. In the current review, we summarise the involvement of RGS proteins in cardiometabolic function with a focus on their tissue distribution, mechanisms of action and dysregulation under various disease conditions. We also discuss the potential therapeutic applications for targeting RGS proteins in treating cardiometabolic conditions and current progress in developing RGS modulators. LINKED ARTICLES: This article is part of a themed issue Therapeutic Targeting of G Protein-Coupled Receptors: hot topics from the Australasian Society of Clinical and Experimental Pharmacologists and Toxicologists 2021 Virtual Annual Scientific Meeting. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v181.14/issuetoc.
Collapse
Affiliation(s)
- Samantha M McNeill
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Peishen Zhao
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
- ARC Centre for Cryo-Electron Microscopy of Membrane Proteins (CCeMMP), Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| |
Collapse
|
2
|
Bramlett SN, Fitzmaurice SM, Harbin NH, Yan W, Bandlamudi C, Van Doorn GE, Smith Y, Hepler JR. Regulator of G Protein Signaling 14 protein expression profile in the adult mouse brain. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.22.600169. [PMID: 38979272 PMCID: PMC11230234 DOI: 10.1101/2024.06.22.600169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/10/2024]
Abstract
Regulator of G protein signaling 14 (RGS14) is a multifunctional signaling protein that serves as a natural suppressor of synaptic plasticity in the mouse brain. Our previous studies showed that RGS14 is highly expressed in postsynaptic dendrites and spines of pyramidal neurons in hippocampal area CA2 of the developing mouse brain. However, our more recent work with adult rhesus macaque brain shows that RGS14 is found in multiple neuron populations throughout hippocampal area CA1 and CA2, caudate nucleus, putamen, globus pallidus, substantia nigra, and amygdala in the adult rhesus monkey brain. In the mouse brain, we also have observed RGS14 protein in discrete limbic regions linked to reward behavior and addiction, including the central amygdala and the nucleus accumbens, but a comprehensive mapping of RGS14 protein expression in the adult mouse brain is lacking. Here, we report that RGS14 is more broadly expressed in mouse brain than previously known. Intense RGS14 staining is observed in specific neuron populations of the hippocampal formation, amygdala, septum, bed nucleus of stria terminalis and ventral striatum/nucleus accumbens. RGS14 is also observed in axon fiber tracts including the dorsal fornix, fimbria, stria terminalis, and the ventrohippocampal commissure. Moderate RGS14 staining is observed in various other adjacent regions not previously reported. These findings show that RGS14 is expressed in brain regions that govern aspects of core cognitive functions such as sensory perception, emotion, memory, motivation, and execution of actions, and suggests that RGS14 may serve to suppress plasticity and filter inputs in these brain regions to set the overall tone on experience-to-action processes.
Collapse
|
3
|
Zhang Q, Sjögren B. Palmitoylation of RGS20 affects Gα o-mediated signaling independent of its GAP activity. Cell Signal 2023; 107:110682. [PMID: 37075876 DOI: 10.1016/j.cellsig.2023.110682] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Revised: 04/07/2023] [Accepted: 04/15/2023] [Indexed: 04/21/2023]
Abstract
Regulator of protein signaling (RGS20) is a member of the RGS protein superfamily, which serve as key negative regulators of G protein-mediated signal transduction. Through their GTPase accelerating protein (GAP) activity, RGS proteins deactivate α-subunits of heterotrimeric G proteins. In addition, the majority of RGS proteins also have the ability to act through other, non-GAP related, functions. RGS20 is one of three members of the RZ subfamily, which all show selective GAP activity towards Gαz, however emerging data suggest that RGS20 can also regulate Gi/o-mediated signaling. While increased RGS20 expression is associated with the progression of multiple cancers, a large gap still exists relating to the mechanisms of RGS20 regulation and function. RGS20 contains a poly-cysteine string motif and a conserved cysteine in RGS domain, which are assumed to be palmitoylated. Palmitoylation, an important post-translational modification, plays an important role in cells by changing cellular functions of proteins. Consequently, the aim of this study was to confirm that RGS20 is palmitoylated and determine how palmitoylation affects its inhibition of Gαo-mediated signaling. We found a significant positive correlation between RGS20 palmitoylation and its association with active Gαo. We also showed that a conserved cysteine residue in the RGS domain is a critical site for its palmitoylation, with large impact on its association with Gαo. Palmitoylation on this site did not affect its GAP activity, however, it increased the inhibition of Gαo-mediated cAMP signaling. Altogether these data suggest that palmitoylation is a regulatory mechanism controlling RGS20 function, and that RGS20 can inhibit Gαo signaling through both GAP activity and non-GAP mechanisms.
Collapse
Affiliation(s)
- Qian Zhang
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN 47907, United States of America
| | - Benita Sjögren
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN 47907, United States of America.
| |
Collapse
|
4
|
Montanez-Miranda C, Bramlett SN, Hepler JR. RGS14 expression in CA2 hippocampus, amygdala, and basal ganglia: Implications for human brain physiology and disease. Hippocampus 2023; 33:166-181. [PMID: 36541898 PMCID: PMC9974931 DOI: 10.1002/hipo.23492] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Revised: 11/09/2022] [Accepted: 12/07/2022] [Indexed: 12/24/2022]
Abstract
RGS14 is a multifunctional scaffolding protein that is highly expressed within postsynaptic spines of pyramidal neurons in hippocampal area CA2. Known roles of RGS14 in CA2 include regulating G protein, H-Ras/ERK, and calcium signaling pathways to serve as a natural suppressor of synaptic plasticity and postsynaptic signaling. RGS14 also shows marked postsynaptic expression in major structures of the limbic system and basal ganglia, including the amygdala and both the ventral and dorsal subdivisions of the striatum. In this review, we discuss the signaling functions of RGS14 and its role in postsynaptic strength (long-term potentiation) and spine structural plasticity in CA2 hippocampal neurons, and how RGS14 suppression of plasticity impacts linked behaviors such as spatial learning, object memory, and fear conditioning. We also review RGS14 expression in the limbic system and basal ganglia and speculate on its possible roles in regulating plasticity in these regions, with a focus on behaviors related to emotion and motivation. Finally, we explore the functional implications of RGS14 in various brain circuits and speculate on its possible roles in certain disease states such as hippocampal seizures, addiction, and anxiety disorders.
Collapse
Affiliation(s)
| | | | - John R. Hepler
- Department of Pharmacology and Chemical Biology, Emory University School of Medicine, Atlanta, GA, 30322-3090
| |
Collapse
|
5
|
Montañez-Miranda C, Perszyk RE, Harbin NH, Okalova J, Ramineni S, Traynelis SF, Hepler JR. Functional Assessment of Cancer-Linked Mutations in Sensitive Regions of Regulators of G Protein Signaling Predicted by Three-Dimensional Missense Tolerance Ratio Analysis. Mol Pharmacol 2023; 103:21-37. [PMID: 36384958 PMCID: PMC10955721 DOI: 10.1124/molpharm.122.000614] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Revised: 10/04/2022] [Accepted: 10/18/2022] [Indexed: 11/18/2022] Open
Abstract
Regulators of G protein signaling (RGS) proteins modulate G protein-coupled receptor (GPCR) signaling by acting as negative regulators of G proteins. Genetic variants in RGS proteins are associated with many diseases, including cancers, although the impact of these mutations on protein function is uncertain. Here we analyze the RGS domains of 15 RGS protein family members using a novel bioinformatic tool that measures the missense tolerance ratio (MTR) using a three-dimensional (3D) structure (3DMTR). Subsequent permutation analysis can define the protein regions that are most significantly intolerant (P < 0.05) in each dataset. We further focused on RGS14, RGS10, and RGS4. RGS14 exhibited seven significantly tolerant and seven significantly intolerant residues, RGS10 had six intolerant residues, and RGS4 had eight tolerant and six intolerant residues. Intolerant and tolerant-control residues that overlap with pathogenic cancer mutations reported in the COSMIC cancer database were selected to define the functional phenotype. Using complimentary cellular and biochemical approaches, proteins were tested for effects on GPCR-Gα activation, Gα binding properties, and downstream cAMP levels. Identified intolerant residues with reported cancer-linked mutations RGS14-R173C/H and RGS4-K125Q/E126K, and tolerant RGS14-S127P and RGS10-S64T resulted in a loss-of-function phenotype in GPCR-G protein signaling activity. In downstream cAMP measurement, tolerant RGS14-D137Y and RGS10-S64T and intolerant RGS10-K89M resulted in change of function phenotypes. These findings show that 3DMTR identified intolerant residues that overlap with cancer-linked mutations cause phenotypic changes that negatively impact GPCR-G protein signaling and suggests that 3DMTR is a potentially useful bioinformatics tool for predicting functionally important protein residues. SIGNIFICANCE STATEMENT: Human genetic variant/mutation information has expanded rapidly in recent years, including cancer-linked mutations in regulator of G protein signaling (RGS) proteins. However, experimental testing of the impact of this vast catalogue of mutations on protein function is not feasible. We used the novel bioinformatics tool three-dimensional missense tolerance ratio (3DMTR) to define regions of genetic intolerance in RGS proteins and prioritize which cancer-linked mutants to test. We found that 3DMTR more accurately classifies loss-of-function mutations in RGS proteins than other databases thereby offering a valuable new research tool.
Collapse
Affiliation(s)
- Carolina Montañez-Miranda
- Department of Pharmacology and Chemical Biology (C.M.-M., R.E.P., N.H.H., S.R., S.F.T., J.R.H.) and Aflac Cancer and Blood Disorders Center, Department of Pediatrics (J.O.), Emory University School of Medicine, Atlanta, Georgia
| | - Riley E Perszyk
- Department of Pharmacology and Chemical Biology (C.M.-M., R.E.P., N.H.H., S.R., S.F.T., J.R.H.) and Aflac Cancer and Blood Disorders Center, Department of Pediatrics (J.O.), Emory University School of Medicine, Atlanta, Georgia
| | - Nicholas H Harbin
- Department of Pharmacology and Chemical Biology (C.M.-M., R.E.P., N.H.H., S.R., S.F.T., J.R.H.) and Aflac Cancer and Blood Disorders Center, Department of Pediatrics (J.O.), Emory University School of Medicine, Atlanta, Georgia
| | - Jennifer Okalova
- Department of Pharmacology and Chemical Biology (C.M.-M., R.E.P., N.H.H., S.R., S.F.T., J.R.H.) and Aflac Cancer and Blood Disorders Center, Department of Pediatrics (J.O.), Emory University School of Medicine, Atlanta, Georgia
| | - Suneela Ramineni
- Department of Pharmacology and Chemical Biology (C.M.-M., R.E.P., N.H.H., S.R., S.F.T., J.R.H.) and Aflac Cancer and Blood Disorders Center, Department of Pediatrics (J.O.), Emory University School of Medicine, Atlanta, Georgia
| | - Stephen F Traynelis
- Department of Pharmacology and Chemical Biology (C.M.-M., R.E.P., N.H.H., S.R., S.F.T., J.R.H.) and Aflac Cancer and Blood Disorders Center, Department of Pediatrics (J.O.), Emory University School of Medicine, Atlanta, Georgia
| | - John R Hepler
- Department of Pharmacology and Chemical Biology (C.M.-M., R.E.P., N.H.H., S.R., S.F.T., J.R.H.) and Aflac Cancer and Blood Disorders Center, Department of Pediatrics (J.O.), Emory University School of Medicine, Atlanta, Georgia
| |
Collapse
|
6
|
Van Trigt WK, Kelly KM, Hughes CCW. GNAQ mutations drive port wine birthmark-associated Sturge-Weber syndrome: A review of pathobiology, therapies, and current models. Front Hum Neurosci 2022; 16:1006027. [PMID: 36405075 PMCID: PMC9670321 DOI: 10.3389/fnhum.2022.1006027] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Accepted: 10/12/2022] [Indexed: 11/06/2022] Open
Abstract
Port-wine birthmarks (PWBs) are caused by somatic, mosaic mutations in the G protein guanine nucleotide binding protein alpha subunit q (GNAQ) and are characterized by the formation of dilated, dysfunctional blood vessels in the dermis, eyes, and/or brain. Cutaneous PWBs can be treated by current dermatologic therapy, like laser intervention, to lighten the lesions and diminish nodules that occur in the lesion. Involvement of the eyes and/or brain can result in serious complications and this variation is termed Sturge-Weber syndrome (SWS). Some of the biggest hurdles preventing development of new therapeutics are unanswered questions regarding disease biology and lack of models for drug screening. In this review, we discuss the current understanding of GNAQ signaling, the standard of care for patients, overlap with other GNAQ-associated or phenotypically similar diseases, as well as deficiencies in current in vivo and in vitro vascular malformation models.
Collapse
Affiliation(s)
- William K. Van Trigt
- Department of Molecular Biology and Biochemistry, School of Biological Sciences, University of California, Irvine, Irvine, CA, United States,*Correspondence: William K. Van Trigt,
| | - Kristen M. Kelly
- Department of Dermatology, School of Medicine, University of California, Irvine, Irvine, CA, United States
| | - Christopher C. W. Hughes
- Department of Molecular Biology and Biochemistry, School of Biological Sciences, University of California, Irvine, Irvine, CA, United States,Christopher C. W. Hughes,
| |
Collapse
|
7
|
Kir Channel Molecular Physiology, Pharmacology, and Therapeutic Implications. Handb Exp Pharmacol 2021; 267:277-356. [PMID: 34345939 DOI: 10.1007/164_2021_501] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
For the past two decades several scholarly reviews have appeared on the inwardly rectifying potassium (Kir) channels. We would like to highlight two efforts in particular, which have provided comprehensive reviews of the literature up to 2010 (Hibino et al., Physiol Rev 90(1):291-366, 2010; Stanfield et al., Rev Physiol Biochem Pharmacol 145:47-179, 2002). In the past decade, great insights into the 3-D atomic resolution structures of Kir channels have begun to provide the molecular basis for their functional properties. More recently, computational studies are beginning to close the time domain gap between in silico dynamic and patch-clamp functional studies. The pharmacology of these channels has also been expanding and the dynamic structural studies provide hope that we are heading toward successful structure-based drug design for this family of K+ channels. In the present review we focus on placing the physiology and pharmacology of this K+ channel family in the context of atomic resolution structures and in providing a glimpse of the promising future of therapeutic opportunities.
Collapse
|
8
|
Nubbemeyer B, Pepanian A, Paul George AA, Imhof D. Strategies towards Targeting Gαi/s Proteins: Scanning of Protein-Protein Interaction Sites To Overcome Inaccessibility. ChemMedChem 2021; 16:1696-1715. [PMID: 33615736 PMCID: PMC8252600 DOI: 10.1002/cmdc.202100039] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Indexed: 12/16/2022]
Abstract
Heterotrimeric G proteins are classified into four subfamilies and play a key role in signal transduction. They transmit extracellular signals to intracellular effectors subsequent to the activation of G protein-coupled receptors (GPCRs), which are targeted by over 30 % of FDA-approved drugs. However, addressing G proteins as drug targets represents a compelling alternative, for example, when G proteins act independently of the corresponding GPCRs, or in cases of complex multifunctional diseases, when a large number of different GPCRs are involved. In contrast to Gαq, efforts to target Gαi/s by suitable chemical compounds has not been successful so far. Here, a comprehensive analysis was conducted examining the most important interface regions of Gαi/s with its upstream and downstream interaction partners. By assigning the existing compounds and the performed approaches to the respective interfaces, the druggability of the individual interfaces was ranked to provide perspectives for selective targeting of Gαi/s in the future.
Collapse
Affiliation(s)
- Britta Nubbemeyer
- Pharmaceutical Biochemistry and BioanalyticsPharmaceutical InstituteUniversity of BonnAn der Immenburg 453121BonnGermany
| | - Anna Pepanian
- Pharmaceutical Biochemistry and BioanalyticsPharmaceutical InstituteUniversity of BonnAn der Immenburg 453121BonnGermany
| | | | - Diana Imhof
- Pharmaceutical Biochemistry and BioanalyticsPharmaceutical InstituteUniversity of BonnAn der Immenburg 453121BonnGermany
| |
Collapse
|
9
|
Israeli R, Asli A, Avital-Shacham M, Kosloff M. RGS6 and RGS7 Discriminate between the Highly Similar Gα i and Gα o Proteins Using a Two-Tiered Specificity Strategy. J Mol Biol 2019; 431:3302-3311. [PMID: 31153905 DOI: 10.1016/j.jmb.2019.05.037] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Revised: 05/12/2019] [Accepted: 05/23/2019] [Indexed: 11/15/2022]
Abstract
RGS6 and RGS7 are regulators of G protein signaling (RGS) proteins that inactivate heterotrimeric (αβγ) G proteins and mediate diverse biological functions, such as cardiac and neuronal signaling. Uniquely, both RGS6 and RGS7 can discriminate between Gαo and Gαi1-two similar Gα subunits that belong to the same Gi sub-family. Here, we show that the isolated RGS domains of RGS6 and RGS7 are sufficient to achieve this specificity. We identified three specific RGS6/7 "disruptor residues" that can attenuate RGS interactions toward Gα subunits and demonstrated that their insertion into a representative high-activity RGS causes a significant, yet non-specific, reduction in activity. We further identified a unique "modulatory" residue that bypasses this negative effect, specifically toward Gαo. Hence, the exquisite specificity of RGS6 and RGS7 toward closely related Gα subunits is achieved via a two-tier specificity system, whereby a Gα-specific modulatory motif overrides the inhibitory effect of non-specific disruptor residues. Our findings expand the understanding of the molecular toolkit used by the RGS family to achieve specific interactions with selected Gα subunits-emphasizing the functional importance of the RGS domain in determining the activity and selectivity of RGS R7 sub-family members toward particular Gα subunits.
Collapse
Affiliation(s)
- Ran Israeli
- Department of Human Biology, Faculty of Natural Sciences, University of Haifa, Haifa 3498838, Israel
| | - Ali Asli
- Department of Human Biology, Faculty of Natural Sciences, University of Haifa, Haifa 3498838, Israel
| | - Meirav Avital-Shacham
- Department of Human Biology, Faculty of Natural Sciences, University of Haifa, Haifa 3498838, Israel
| | - Mickey Kosloff
- Department of Human Biology, Faculty of Natural Sciences, University of Haifa, Haifa 3498838, Israel.
| |
Collapse
|
10
|
Mohammadi M, Mohammadiarani H, Shaw VS, Neubig RR, Vashisth H. Interplay of cysteine exposure and global protein dynamics in small-molecule recognition by a regulator of G-protein signaling protein. Proteins 2018; 87:146-156. [PMID: 30521141 DOI: 10.1002/prot.25642] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Revised: 11/07/2018] [Accepted: 11/29/2018] [Indexed: 02/06/2023]
Abstract
Regulator of G protein signaling (RGS) proteins play a pivotal role in regulation of G protein-coupled receptor (GPCR) signaling and are therefore becoming an increasingly important therapeutic target. Recently discovered thiadiazolidinone (TDZD) compounds that target cysteine residues have shown different levels of specificities and potencies for the RGS4 protein, thereby suggesting intrinsic differences in dynamics of this protein upon binding of these compounds. In this work, we investigated using atomistic molecular dynamics (MD) simulations the effect of binding of several small-molecule inhibitors on perturbations and dynamical motions in RGS4. Specifically, we studied two conformational models of RGS4 in which a buried cysteine residue is solvent-exposed due to side-chain motions or due to flexibility in neighboring helices. We found that TDZD compounds with aromatic functional groups perturb the RGS4 structure more than compounds with aliphatic functional groups. Moreover, small-molecules with aromatic functional groups but lacking sulfur atoms only transiently reside within the protein and spontaneously dissociate to the solvent. We further measured inhibitory effects of TDZD compounds using a protein-protein interaction assay on a single-cysteine RGS4 protein showing trends in potencies of compounds consistent with our simulation studies. Thermodynamic analyses of RGS4 conformations in the apo-state and on binding to TDZD compounds revealed links between both conformational models of RGS4. The exposure of cysteine side-chains appears to facilitate initial binding of TDZD compounds followed by migration of the compound into a bundle of four helices, thereby causing allosteric perturbations in the RGS/Gα protein-protein interface.
Collapse
Affiliation(s)
| | | | - Vincent S Shaw
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan
| | - Richard R Neubig
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan
| | - Harish Vashisth
- Department of Chemical Engineering, University of New Hampshire, Durham, New Hampshire
| |
Collapse
|
11
|
Squires KE, Montañez-Miranda C, Pandya RR, Torres MP, Hepler JR. Genetic Analysis of Rare Human Variants of Regulators of G Protein Signaling Proteins and Their Role in Human Physiology and Disease. Pharmacol Rev 2018; 70:446-474. [PMID: 29871944 DOI: 10.1124/pr.117.015354] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Regulators of G protein signaling (RGS) proteins modulate the physiologic actions of many neurotransmitters, hormones, and other signaling molecules. Human RGS proteins comprise a family of 20 canonical proteins that bind directly to G protein-coupled receptors/G protein complexes to limit the lifetime of their signaling events, which regulate all aspects of cell and organ physiology. Genetic variations account for diverse human traits and individual predispositions to disease. RGS proteins contribute to many complex polygenic human traits and pathologies such as hypertension, atherosclerosis, schizophrenia, depression, addiction, cancers, and many others. Recent analysis indicates that most human diseases are due to extremely rare genetic variants. In this study, we summarize physiologic roles for RGS proteins and links to human diseases/traits and report rare variants found within each human RGS protein exome sequence derived from global population studies. Each RGS sequence is analyzed using recently described bioinformatics and proteomic tools for measures of missense tolerance ratio paired with combined annotation-dependent depletion scores, and protein post-translational modification (PTM) alignment cluster analysis. We highlight selected variants within the well-studied RGS domain that likely disrupt RGS protein functions and provide comprehensive variant and PTM data for each RGS protein for future study. We propose that rare variants in functionally sensitive regions of RGS proteins confer profound change-of-function phenotypes that may contribute, in newly appreciated ways, to complex human diseases and/or traits. This information provides investigators with a valuable database to explore variation in RGS protein function, and for targeting RGS proteins as future therapeutic targets.
Collapse
Affiliation(s)
- Katherine E Squires
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia (K.E.S., C.M.-M., J.R.H.); and School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia (R.R.P., M.P.T.)
| | - Carolina Montañez-Miranda
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia (K.E.S., C.M.-M., J.R.H.); and School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia (R.R.P., M.P.T.)
| | - Rushika R Pandya
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia (K.E.S., C.M.-M., J.R.H.); and School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia (R.R.P., M.P.T.)
| | - Matthew P Torres
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia (K.E.S., C.M.-M., J.R.H.); and School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia (R.R.P., M.P.T.)
| | - John R Hepler
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia (K.E.S., C.M.-M., J.R.H.); and School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia (R.R.P., M.P.T.)
| |
Collapse
|
12
|
Porcu A, Melis M, Turecek R, Ullrich C, Mocci I, Bettler B, Gessa GL, Castelli MP. Rimonabant, a potent CB1 cannabinoid receptor antagonist, is a Gα i/o protein inhibitor. Neuropharmacology 2018; 133:107-120. [PMID: 29407764 DOI: 10.1016/j.neuropharm.2018.01.024] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Revised: 01/10/2018] [Accepted: 01/18/2018] [Indexed: 12/25/2022]
Abstract
Rimonabant is a potent and selective cannabinoid CB1 receptor antagonist widely used in animal and clinical studies. Besides its antagonistic properties, numerous studies have shown that, at micromolar concentrations rimonabant behaves as an inverse agonist at CB1 receptors. The mechanism underpinning this activity is unclear. Here we show that micromolar concentrations of rimonabant inhibited Gαi/o-type G proteins, resulting in a receptor-independent block of G protein signaling. Accordingly, rimonabant decreased basal and agonist stimulated [35S]GTPγS binding to cortical membranes of CB1- and GABAB-receptor KO mice and Chinese Hamster Ovary (CHO) cell membranes stably transfected with GABAB or D2 dopamine receptors. The structural analog of rimonabant, AM251, decreased basal and baclofen-stimulated GTPγS binding to rat cortical and CHO cell membranes expressing GABAB receptors. Rimonabant prevented G protein-mediated GABAB and D2 dopamine receptor signaling to adenylyl cyclase in Human Embryonic Kidney 293 cells and to G protein-coupled inwardly rectifying K+ channels (GIRK) in midbrain dopamine neurons of CB1 KO mice. Rimonabant suppressed GIRK gating induced by GTPγS in CHO cells transfected with GIRK, consistent with a receptor-independent action. Bioluminescent resonance energy transfer (BRET) measurements in living CHO cells showed that, in presence or absence of co-expressed GABAB receptors, rimonabant stabilized the heterotrimeric Gαi/o-protein complex and prevented conformational rearrangements induced by GABAB receptor activation. Rimonabant failed to inhibit Gαs-mediated signaling, supporting its specificity for Gαi/o-type G proteins. The inhibition of Gαi/o protein provides a new site of rimonabant action that may help to understand its pharmacological and toxicological effects occurring at high concentrations.
Collapse
Affiliation(s)
- Alessandra Porcu
- Department of Biomedical Sciences, University of Cagliari, 09042, Monserrato, Italy; Department of Biomedicine, University of Basel, Klingelbergstrasse 50-70, CH-4056, Basel, Switzerland
| | - Miriam Melis
- Department of Biomedical Sciences, University of Cagliari, 09042, Monserrato, Italy
| | - Rostislav Turecek
- Department of Biomedicine, University of Basel, Klingelbergstrasse 50-70, CH-4056, Basel, Switzerland
| | - Celine Ullrich
- Department of Biomedicine, University of Basel, Klingelbergstrasse 50-70, CH-4056, Basel, Switzerland
| | - Ignazia Mocci
- Institute of Translational Pharmacology, National Research Council of Italy (CNR) U.O.S. of Cagliari, 09010, Pula, Italy
| | - Bernhard Bettler
- Department of Biomedicine, University of Basel, Klingelbergstrasse 50-70, CH-4056, Basel, Switzerland
| | - Gian Luigi Gessa
- Department of Biomedical Sciences, University of Cagliari, 09042, Monserrato, Italy; Guy Everett Laboratory, University of Cagliari, 09042, Monserrato, Italy; Neuroscience Institute, National Research Council of Italy (CNR), Cagliari, Italy; Center of Excellence "Neurobiology of Addiction", University of Cagliari, 09042, Monserrato, Italy
| | - M Paola Castelli
- Department of Biomedical Sciences, University of Cagliari, 09042, Monserrato, Italy; Center of Excellence "Neurobiology of Addiction", University of Cagliari, 09042, Monserrato, Italy.
| |
Collapse
|
13
|
Perschbacher KJ, Deng G, Fisher RA, Gibson-Corley KN, Santillan MK, Grobe JL. Regulators of G protein signaling in cardiovascular function during pregnancy. Physiol Genomics 2018; 50:590-604. [PMID: 29702036 PMCID: PMC6139632 DOI: 10.1152/physiolgenomics.00037.2018] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
G protein-coupled receptor signaling mechanisms are implicated in many aspects of cardiovascular control, and dysfunction of such signaling mechanisms is commonly associated with disease states. Investigators have identified a large number of regulator of G protein signaling (RGS) proteins that variously contribute to the modulation of intracellular second-messenger signaling kinetics. These many RGS proteins each interact with a specific set of second-messenger cascades and receptor types and exhibit tissue-specific expression patterns. Increasing evidence supports the contribution of RGS proteins, or their loss, in the pathogenesis of cardiovascular dysfunctions. This review summarizes the current understanding of the functional contributions of RGS proteins, particularly within the B/R4 family, in cardiovascular disorders of pregnancy including gestational hypertension, uterine artery dysfunction, and preeclampsia.
Collapse
Affiliation(s)
| | - Guorui Deng
- Department of Pharmacology, University of Iowa , Iowa City, Iowa
| | - Rory A Fisher
- Department of Pharmacology, University of Iowa , Iowa City, Iowa
| | - Katherine N Gibson-Corley
- Department of Pathology, University of Iowa , Iowa City, Iowa
- UIHC Center for Hypertension Research, University of Iowa , Iowa City, Iowa
| | - Mark K Santillan
- Department of Obstetrics & Gynecology, University of Iowa , Iowa City, Iowa
- UIHC Center for Hypertension Research, University of Iowa , Iowa City, Iowa
- Abboud Cardiovascular Research Center, University of Iowa , Iowa City, Iowa
| | - Justin L Grobe
- Department of Pharmacology, University of Iowa , Iowa City, Iowa
- UIHC Center for Hypertension Research, University of Iowa , Iowa City, Iowa
- Abboud Cardiovascular Research Center, University of Iowa , Iowa City, Iowa
- Fraternal Order of Eagles' Diabetes Research Center, University of Iowa , Iowa City, Iowa
- Obesity Education & Research Initiative, University of Iowa , Iowa City, Iowa
- Iowa Neuroscience Institute, University of Iowa , Iowa City, Iowa
| |
Collapse
|
14
|
Szutorisz H, Hurd YL. High times for cannabis: Epigenetic imprint and its legacy on brain and behavior. Neurosci Biobehav Rev 2018; 85:93-101. [PMID: 28506926 PMCID: PMC5682234 DOI: 10.1016/j.neubiorev.2017.05.011] [Citation(s) in RCA: 81] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2017] [Revised: 05/09/2017] [Accepted: 05/10/2017] [Indexed: 12/22/2022]
Abstract
Extensive debates continue regarding marijuana (Cannabis spp), the most commonly used illicit substance in many countries worldwide. There has been an exponential increase of cannabis studies over the past two decades but the drug's long-term effects still lack in-depth scientific data. The epigenome is a critical molecular machinery with the capacity to maintain persistent alterations of gene expression and behaviors induced by cannabinoids that have been observed across the individual's lifespan and even into the subsequent generation. Though mechanistic investigations regarding the consequences of developmental cannabis exposure remain sparse, human and animal studies have begun to reveal specific epigenetic disruptions in the brain and the periphery. In this article, we focus attention on long-term disturbances in epigenetic regulation in relation to prenatal, adolescent and parental germline cannabinoid exposure. Expanding knowledge about the protracted molecular memory could help to identify novel targets to develop preventive strategies and treatments for behaviors relevant to neuropsychiatric risks associated with developmental cannabis exposure.
Collapse
Affiliation(s)
- Henrietta Szutorisz
- Friedman Brain Institute, Departments of Psychiatry and Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Yasmin L Hurd
- Friedman Brain Institute, Departments of Psychiatry and Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA; Addiction Institute at Mount Sinai, New York, NY, USA.
| |
Collapse
|
15
|
Bodle CR, Schamp JH, O'Brien JB, Hayes MP, Wu M, Doorn JA, Roman DL. Screen Targeting Lung and Prostate Cancer Oncogene Identifies Novel Inhibitors of RGS17 and Problematic Chemical Substructures. SLAS DISCOVERY 2018; 23:363-374. [PMID: 29351497 DOI: 10.1177/2472555217752301] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Regulator of G protein signaling (RGS) proteins temporally regulate heterotrimeric G protein signaling cascades elicited by G protein-coupled receptor activation and thus are essential for cell homeostasis. The dysregulation of RGS protein expression has been linked to several pathologies, spurring discovery efforts to identify small-molecule inhibitors of these proteins. Presented here are the results of a high-throughput screening (HTS) campaign targeting RGS17, an RGS protein reported to be inappropriately upregulated in several cancers. A screen of over 60,000 small molecules led to the identification of five hit compounds that inhibit the RGS17-Gαo protein-protein interaction. Chemical and biochemical characterization demonstrated that three of these hits inhibited the interaction through the decomposition of parent compound into reactive products under normal chemical library storage/usage conditions. Compound substructures susceptible to decomposition are reported and the decomposition process characterized, adding to the armamentarium of tools available to the screening field, allowing for the conservation of resources in follow-up efforts and more efficient identification of potentially decomposed compounds. Finally, analogues of one hit compound were tested, and the results establish the first ever structure-activity relationship (SAR) profile for a small-molecule inhibitor of RGS17.
Collapse
Affiliation(s)
- Christopher R Bodle
- 1 Department of Pharmaceutical Sciences and Experimental Therapeutics, University of Iowa, Iowa City, IA, USA
| | - Josephine H Schamp
- 1 Department of Pharmaceutical Sciences and Experimental Therapeutics, University of Iowa, Iowa City, IA, USA
| | - Joseph B O'Brien
- 1 Department of Pharmaceutical Sciences and Experimental Therapeutics, University of Iowa, Iowa City, IA, USA
| | - Michael P Hayes
- 1 Department of Pharmaceutical Sciences and Experimental Therapeutics, University of Iowa, Iowa City, IA, USA
| | - Meng Wu
- 1 Department of Pharmaceutical Sciences and Experimental Therapeutics, University of Iowa, Iowa City, IA, USA.,2 University of Iowa High Throughput Screening Facility (UIHTS), University of Iowa, Iowa City, IA, USA.,3 Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Jonathan A Doorn
- 1 Department of Pharmaceutical Sciences and Experimental Therapeutics, University of Iowa, Iowa City, IA, USA
| | - David L Roman
- 1 Department of Pharmaceutical Sciences and Experimental Therapeutics, University of Iowa, Iowa City, IA, USA.,4 Cancer Signaling and Experimental Therapeutics Program, Holden Comprehensive Cancer Center, UIHC, University of Iowa, Iowa City, IA, USA
| |
Collapse
|
16
|
Tomas-Roig J, Benito E, Agis-Balboa RC, Piscitelli F, Hoyer-Fender S, Di Marzo V, Havemann-Reinecke U. Chronic exposure to cannabinoids during adolescence causes long-lasting behavioral deficits in adult mice. Addict Biol 2017; 22:1778-1789. [PMID: 27578457 PMCID: PMC5697667 DOI: 10.1111/adb.12446] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Revised: 08/07/2016] [Accepted: 08/09/2016] [Indexed: 01/23/2023]
Abstract
Regular use of marijuana during adolescence enhances the risk of long-lasting neurobiological changes in adulthood. The present study was aimed at assessing the effect of long-term administration of the synthetic cannabinoid WIN55212.2 during adolescence in young adult mice. Adolescent mice aged 5 weeks were subjected daily to the pharmacological action of WIN55212.2 for 3 weeks and were then left undisturbed in their home cage for a 5-week period and finally evaluated by behavioral testing. Mice that received the drug during adolescence showed memory impairment in the Morris water maze, as well as a dose-dependent memory impairment in fear conditioning. In addition, the administration of 3 mg/kg WIN55212.2 in adolescence increased adult hippocampal AEA levels and promoted DNA hypermethylation at the intragenic region of the intracellular signaling modulator Rgs7, which was accompanied by a lower rate of mRNA transcription of this gene, suggesting a potential causal relation. Although the concrete mechanisms underlying the behavioral observations remain to be elucidated, we demonstrate that long-term administration of 3 mg/kg of WIN during adolescence leads to increased endocannabinoid levels and altered Rgs7 expression in adulthood and establish a potential link to epigenetic changes.
Collapse
Affiliation(s)
- J Tomas-Roig
- Department of Psychiatry and Psychotherapy; University of Göttingen; Germany
- Center Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB); Germany
| | - E Benito
- Research Group for Epigenetic Mechanisms in Dementia; German Center for Neurodegenerative Diseases (DZNE); Germany
| | - RC Agis-Balboa
- Department of Psychiatry and Psychotherapy; University Medical Center Göttingen; Germany
- Instituto de Investigación Sanitaria Galicia Sur; Spain
| | - F Piscitelli
- Endocannabinoid Research Group; Institute of Biomolecular Chemistry; Italy
| | - S Hoyer-Fender
- Johann-Friedrich-Blumenbach Institute for Zoology and Anthropology; Developmental Biology; Germany
| | - V Di Marzo
- Endocannabinoid Research Group; Institute of Biomolecular Chemistry; Italy
| | - U Havemann-Reinecke
- Department of Psychiatry and Psychotherapy; University of Göttingen; Germany
- Center Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB); Germany
| |
Collapse
|
17
|
Hayes MP, Bodle CR, Roman DL. Evaluation of the Selectivity and Cysteine Dependence of Inhibitors across the Regulator of G Protein-Signaling Family. Mol Pharmacol 2017; 93:25-35. [PMID: 29051318 DOI: 10.1124/mol.117.109843] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Accepted: 10/16/2017] [Indexed: 01/03/2023] Open
Abstract
Since their discovery more than 20 years ago, regulators of G protein-signaling (RGS) proteins have received considerable attention as potential drug targets because of their ability to modulate Gα activity. Efforts to identify small molecules capable of inhibiting the protein-protein interactions between activated Gα subunits and RGS proteins have yielded a substantial number of inhibitors, especially toward the well studied RGS4. These efforts also determined that many of these small molecules inhibit the protein-protein interactions through covalent modification of cysteine residues within the RGS domain that are located distal to the Gα-binding interface. As some of these cysteine residues are highly conserved within the RGS family, many of these inhibitors display activity toward multiple RGS family members. In this work, we sought to determine the selectivity of these small-molecule inhibitors against 12 RGS proteins, as well as against the cysteine-null mutants for 10 of these proteins. Using both biochemical and cell-based methods to assess Gα-RGS complex formation and Gα enzymatic activity, we found that several previously identified RGS4 inhibitors were active against other RGS members, such as RGS14, with comparable or greater potency. Additionally, for every compound tested, activity was dependent on the presence of cysteine residues. This work defines the selectivity of commercially available RGS inhibitors and provides insight into the RGS family members for which drug discovery efforts may be most likely to succeed.
Collapse
Affiliation(s)
- Michael P Hayes
- Department of Pharmaceutical Sciences and Experimental Therapeutics University of Iowa (M.P.H., C.R.B., D.L.R.) and Cancer Signaling and Experimental Therapeutics Program, Holden Comprehensive Cancer Center, University of Iowa Hospitals and Clinics (D.L.R.), Iowa City, Iowa
| | - Christopher R Bodle
- Department of Pharmaceutical Sciences and Experimental Therapeutics University of Iowa (M.P.H., C.R.B., D.L.R.) and Cancer Signaling and Experimental Therapeutics Program, Holden Comprehensive Cancer Center, University of Iowa Hospitals and Clinics (D.L.R.), Iowa City, Iowa
| | - David L Roman
- Department of Pharmaceutical Sciences and Experimental Therapeutics University of Iowa (M.P.H., C.R.B., D.L.R.) and Cancer Signaling and Experimental Therapeutics Program, Holden Comprehensive Cancer Center, University of Iowa Hospitals and Clinics (D.L.R.), Iowa City, Iowa
| |
Collapse
|
18
|
Ghosh P, Rangamani P, Kufareva I. The GAPs, GEFs, GDIs and…now, GEMs: New kids on the heterotrimeric G protein signaling block. Cell Cycle 2017; 16:607-612. [PMID: 28287365 DOI: 10.1080/15384101.2017.1282584] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
The canonical process of activation of heterotrimeric G proteins by G protein coupled receptors (GPCRs) is well studied. Recently, a rapidly emerging paradigm has revealed the existence of a new, non-canonical set of cytosolic G protein modulators, guanine exchange modulators (GEMs). Among G proteins regulators, GEMs are uniquely capable of initiating pleiotropic signals: these bifunctional modulators can activate cAMP inhibitory (Gi) proteins and inhibit cAMP-stimulatory (Gs) proteins through a single short evolutionarily conserved module. A prototypical member of the GEM family, GIV/Girdin, integrates signals downstream of a myriad of cell surface receptors, e.g., growth factor RTKs, integrins, cytokine, GPCRs, etc., and translates these signals into G protein activation or inhibition. By their pleiotropic action, GIV and other GEMs modulate several key pathways within downstream signaling network. Unlike canonical G protein signaling that is finite and is triggered directly and exclusively by GPCRs, the temporal and spatial features of non-canonical activation of G protein via GIV-family of cytosolic GEMs are unusually relaxed. GIV uses this relaxed circuitry to integrate, reinforce and compartmentalize signals downstream of both growth factors and G proteins in a way that enables it to orchestrate cellular phenotypes in a sustained manner. Mounting evidence suggests the importance of GIV and other GEMs as disease modulators and their potential to serve as therapeutic targets; however, a lot remains unknown within the layers of the proverbial onion that must be systematically peeled. This perspective summarizes the key concepts of the GEM-dependent G protein signaling paradigm and discusses the multidisciplinary approaches that are likely to revolutionize our understanding of this paradigm from the atomic level to systems biology.
Collapse
Affiliation(s)
- Pradipta Ghosh
- a Departments of Medicine and Cell and Molecular Medicine , University of California at San Diego , La Jolla , CA , USA
| | - Padmini Rangamani
- b Department of Mechanical and Aerospace Engineering , Jacobs School of Engineering, University of California at San Diego , La Jolla , CA , USA
| | - Irina Kufareva
- c Skaggs School of Pharmacy and Pharmaceutical Sciences , University of California at San Diego , La Jolla , CA , USA
| |
Collapse
|
19
|
Li Q, Jin W, Cai Y, Yang F, Chen E, Ye D, Wang Q, Guan X. Regulator of G protein signaling 20 correlates with clinicopathological features and prognosis in triple-negative breast cancer. Biochem Biophys Res Commun 2017; 485:693-697. [PMID: 28237701 DOI: 10.1016/j.bbrc.2017.02.106] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Accepted: 02/20/2017] [Indexed: 12/20/2022]
Abstract
Triple-negative breast cancer (TNBC) is a highly aggressive tumor subtype lacking effective prognostic indicators or therapeutic targets. Therefore, finding a novel molecular biomarker for TNBC to achieve target therapy and predict its prognosis is crucial in preventing inappropriate treatment. Regulator of G-protein signaling (RGS) families of protein can negatively regulate signaling of heterotrimeric G proteins and are known to be upregulated in various tumors. In this study, we demonstrated that RGS20 was more highly expressed in TNBC tumor tissue than in adjacent normal tissue by analyzing the cancer genome atlas (TCGA) database. However, RGS20 expression was low in all breast cancer and luminal breast cancer patients. Validated by the TCGA cohort, RGS20 was upregulated in lymph node-positive TNBC compared with that in lymph node-negative breast cancer. High expression of RGS20 had a risk of lymph node metastasis, ki-67 > 14%, poor N stage, and poor clinical stage in the immunohistochemistry of tissue microarrays. Moreover, K-M plot analysis showed that TNBC patients with high RGS20 expression had poor relapse-free survival. In summary, the findings revealed that RGS20 was a special TNBC oncogene that promoted tumor progression and influenced TNBC prognosis. This study is the first to show that RGS20 was a special oncogene, and its high expression was significantly associated with the progression and prognosis of TNBC. RGS20 may be a novel molecular biomarker for the targeted therapy and prognosis of TNBC.
Collapse
Affiliation(s)
- Quan Li
- Department of Medical Oncology, Jinling Hospital, School of Medicine, Southern Medical University, Guangzhou, 510282, China; Department of Oncological Surgery, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, 325000, China
| | - Wenxu Jin
- Department of Oncological Surgery, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, 325000, China
| | - Yefeng Cai
- Department of Oncological Surgery, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, 325000, China
| | - Fang Yang
- Department of Medical Oncology, Jinling Hospital, Medical School of Nanjing University, Nanjing, 210002, China
| | - Endong Chen
- Department of Oncological Surgery, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, 325000, China
| | - Danrong Ye
- Department of Oncological Surgery, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, 325000, China
| | - Qingxuan Wang
- Department of Oncological Surgery, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, 325000, China
| | - Xiaoxiang Guan
- Department of Medical Oncology, Jinling Hospital, School of Medicine, Southern Medical University, Guangzhou, 510282, China; Department of Medical Oncology, Jinling Hospital, Medical School of Nanjing University, Nanjing, 210002, China.
| |
Collapse
|
20
|
Sjögren B. The evolution of regulators of G protein signalling proteins as drug targets - 20 years in the making: IUPHAR Review 21. Br J Pharmacol 2017; 174:427-437. [PMID: 28098342 DOI: 10.1111/bph.13716] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Revised: 12/11/2016] [Accepted: 01/08/2017] [Indexed: 12/11/2022] Open
Abstract
Regulators of G protein signalling (RGS) proteins are celebrating the 20th anniversary of their discovery. The unveiling of this new family of negative regulators of G protein signalling in the mid-1990s solved a persistent conundrum in the G protein signalling field, in which the rate of deactivation of signalling cascades in vivo could not be replicated in exogenous systems. Since then, there has been tremendous advancement in the knowledge of RGS protein structure, function, regulation and their role as novel drug targets. RGS proteins play an important modulatory role through their GTPase-activating protein (GAP) activity at active, GTP-bound Gα subunits of heterotrimeric G proteins. They also possess many non-canonical functions not related to G protein signalling. Here, an update on the status of RGS proteins as drug targets is provided, highlighting advances that have led to the inclusion of RGS proteins in the IUPHAR/BPS Guide to PHARMACOLOGY database of drug targets.
Collapse
Affiliation(s)
- B Sjögren
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI, USA
| |
Collapse
|
21
|
Development of a bimolecular luminescence complementation assay for RGS: G protein interactions in cells. Anal Biochem 2017; 522:10-17. [PMID: 28115169 DOI: 10.1016/j.ab.2017.01.013] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2016] [Revised: 01/10/2017] [Accepted: 01/18/2017] [Indexed: 02/03/2023]
Abstract
Cell based assessment tools and screening platforms are the preferred paradigm for small molecule identification and validation due to selectively identifying molecules with cellular activity and validation of compound activity against target proteins in their native environment. With respect to Regulator of G Protein Signaling (RGS) proteins, current cell based methodologies are either low throughput or monitor downstream signaling consequences. The increasing number of reports indicating RGS function in various disease pathogeneses highlights the need for a robust RGS inhibitor discovery and characterization paradigm. Promega's NanoBit Protein Complementation Assay utilizes NanoLuc, an engineered luciferase with enhanced luminescence characteristics which allow for both robust and kinetic assessment of protein interaction formation and disruption. Here we characterized 15 separate RGS: G protein interactions using this system. The binding profile of RGS: Gα interactions correlates to prior published biochemical binding profiles of these proteins. Additionally, we demonstrated this system is suitable for high throughput screening efforts via calculation of Z-factors for three of the interactions and demonstrated that a known small molecule inhibitor of RGS4 disrupts the RGS4: Gαi1 protein-protein interaction. In conclusion, the NanoBit Protein Complementation Assay holds promise as a robust platform for discovery and characterization of RGS inhibitors.
Collapse
|
22
|
Syrovatkina V, Alegre KO, Dey R, Huang XY. Regulation, Signaling, and Physiological Functions of G-Proteins. J Mol Biol 2016; 428:3850-68. [PMID: 27515397 DOI: 10.1016/j.jmb.2016.08.002] [Citation(s) in RCA: 265] [Impact Index Per Article: 33.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2016] [Revised: 07/31/2016] [Accepted: 08/03/2016] [Indexed: 12/31/2022]
Abstract
Heterotrimeric guanine-nucleotide-binding regulatory proteins (G-proteins) mainly relay the information from G-protein-coupled receptors (GPCRs) on the plasma membrane to the inside of cells to regulate various biochemical functions. Depending on the targeted cell types, tissues, and organs, these signals modulate diverse physiological functions. The basic schemes of heterotrimeric G-proteins have been outlined. In this review, we briefly summarize what is known about the regulation, signaling, and physiological functions of G-proteins. We then focus on a few less explored areas such as the regulation of G-proteins by non-GPCRs and the physiological functions of G-proteins that cannot be easily explained by the known G-protein signaling pathways. There are new signaling pathways and physiological functions for G-proteins to be discovered and further interrogated. With the advancements in structural and computational biological techniques, we are closer to having a better understanding of how G-proteins are regulated and of the specificity of G-protein interactions with their regulators.
Collapse
Affiliation(s)
- Viktoriya Syrovatkina
- Department of Physiology and Biophysics, Weill Cornell Medical College, of Cornell University, 1300 York Avenue, New York, NY 10065, USA
| | - Kamela O Alegre
- Department of Physiology and Biophysics, Weill Cornell Medical College, of Cornell University, 1300 York Avenue, New York, NY 10065, USA
| | - Raja Dey
- Department of Physiology and Biophysics, Weill Cornell Medical College, of Cornell University, 1300 York Avenue, New York, NY 10065, USA
| | - Xin-Yun Huang
- Department of Physiology and Biophysics, Weill Cornell Medical College, of Cornell University, 1300 York Avenue, New York, NY 10065, USA.
| |
Collapse
|
23
|
Lee J, Ghil S. Regulator of G protein signaling 8 inhibits protease-activated receptor 1/G i/o signaling by forming a distinct G protein-dependent complex in live cells. Cell Signal 2016; 28:391-400. [DOI: 10.1016/j.cellsig.2016.01.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Revised: 01/27/2016] [Accepted: 01/28/2016] [Indexed: 10/22/2022]
|
24
|
Cheng C, Yue W, Li L, Li S, Gao C, Si L, Tian H. Regulator of G-protein signaling 4: A novel tumor suppressor with prognostic significance in non-small cell lung cancer. Biochem Biophys Res Commun 2016; 469:384-91. [DOI: 10.1016/j.bbrc.2015.11.110] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Accepted: 11/24/2015] [Indexed: 12/21/2022]
|
25
|
Blazer LL, Storaska AJ, Jutkiewicz EM, Turner EM, Calcagno M, Wade SM, Wang Q, Huang XP, Traynor JR, Husbands SM, Morari M, Neubig RR. Selectivity and anti-Parkinson's potential of thiadiazolidinone RGS4 inhibitors. ACS Chem Neurosci 2015; 6:911-9. [PMID: 25844489 DOI: 10.1021/acschemneuro.5b00063] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Many current therapies target G protein coupled receptors (GPCR), transporters, or ion channels. In addition to directly targeting these proteins, disrupting the protein-protein interactions that localize or regulate their function could enhance selectivity and provide unique pharmacologic actions. Regulators of G protein signaling (RGS) proteins, especially RGS4, play significant roles in epilepsy and Parkinson's disease. Thiadiazolidinone (TDZD) inhibitors of RGS4 are nanomolar potency blockers of the biochemical actions of RGS4 in vitro. Here, we demonstrate the substantial selectivity (8- to >5000-fold) of CCG-203769 for RGS4 over other RGS proteins. It is also 300-fold selective for RGS4 over GSK-3β, another target of this class of chemical scaffolds. It does not inhibit the cysteine protease papain at 100 μM. CCG-203769 enhances Gαq-dependent cellular Ca(2+) signaling in an RGS4-dependent manner. TDZD inhibitors also enhance Gαi-dependent δ-OR inhibition of cAMP production in SH-SY-5Y cells, which express endogenous receptors and RGS4. Importantly, CCG-203769 potentiates the known RGS4 mechanism of Gαi-dependent muscarinic bradycardia in vivo. Furthermore, it reverses raclopride-induced akinesia and bradykinesia in mice, a model of some aspects of the movement disorder in Parkinson's disease. A broad assessment of compound effects revealed minimal off-target effects at concentrations necessary for cellular RGS4 inhibition. These results expand our understanding of the mechanism and specificity of TDZD RGS inhibitors and support the potential for therapeutic targeting of RGS proteins in Parkinson's disease and other neural disorders.
Collapse
Affiliation(s)
- Levi L. Blazer
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States,
| | - Andrew J. Storaska
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States,
- Department of Pharmacology and Toxicology, Michigan State University, East
Lansing, Michigan 48824, United States
| | - Emily M. Jutkiewicz
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States,
| | - Emma M. Turner
- Department of Pharmacy and Pharmacology, University of Bath, Bath, U.K
| | - Mariangela Calcagno
- Section of Pharmacology, Department of
Medical Science, University of Ferrara, Ferrara, Italy 44121
| | - Susan M. Wade
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States,
| | - Qin Wang
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States,
| | - Xi-Ping Huang
- National Institute of Mental Health Psychoactive Drug
Screening Program (NIMH PDSP), Department of Pharmacology, University of North Carolina, Chapel Hill, North Carolina 27599, United States
| | - John R. Traynor
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States,
| | | | - Michele Morari
- Section of Pharmacology, Department of
Medical Science, University of Ferrara, Ferrara, Italy 44121
| | - Richard R. Neubig
- Department of Pharmacology and Toxicology, Michigan State University, East
Lansing, Michigan 48824, United States
| |
Collapse
|
26
|
GIRK Channels: A Potential Link Between Learning and Addiction. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2015; 123:239-77. [PMID: 26422987 DOI: 10.1016/bs.irn.2015.05.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The ability of drug-associated cues to reinitiate drug craving and seeking, even after long periods of abstinence, has led to the hypothesis that addiction represents a form of pathological learning, in which drugs of abuse hijack normal learning and memory processes to support long-term addictive behaviors. In this chapter, we review evidence suggesting that G protein-gated inwardly rectifying potassium (GIRK/Kir3) channels are one mechanism through which numerous drugs of abuse can modulate learning and memory processes. We will examine the role of GIRK channels in two forms of experience-dependent long-term changes in neuronal function: homeostatic plasticity and synaptic plasticity. We will also discuss how drug-induced changes in GIRK-mediated signaling can lead to changes that support the development and maintenance of addiction.
Collapse
|
27
|
Delesque-Touchard N, Pendaries C, Volle-Challier C, Millet L, Salel V, Hervé C, Pflieger AM, Berthou-Soulie L, Prades C, Sorg T, Herbert JM, Savi P, Bono F. Regulator of G-protein signaling 18 controls both platelet generation and function. PLoS One 2014; 9:e113215. [PMID: 25405900 PMCID: PMC4236145 DOI: 10.1371/journal.pone.0113215] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2014] [Accepted: 10/24/2014] [Indexed: 01/10/2023] Open
Abstract
RGS18 is a myeloerythroid lineage-specific regulator of G-protein signaling, highly expressed in megakaryocytes (MKs) and platelets. In the present study, we describe the first generation of a RGS18 knockout mouse model (RGS18-/-). Interesting phenotypic differences between RGS18-/- and wild-type (WT) mice were identified, and show that RGS18 plays a significant role in both platelet generation and function. RGS18 deficiency produced a gain of function phenotype in platelets. In resting platelets, the level of CD62P expression was increased in RGS18-/- mice. This increase correlated with a higher level of plasmatic serotonin concentration. RGS18-/- platelets displayed a higher sensitivity to activation in vitro. RGS18 deficiency markedly increased thrombus formation in vivo. In addition, RGS18-/- mice presented a mild thrombocytopenia, accompanied with a marked deficit in MK number in the bone marrow. Analysis of MK maturation in vitro and in vivo revealed a defective megakaryopoiesis in RGS18-/- mice, with a lower bone marrow content of only the most committed MK precursors. Finally, RGS18 deficiency was correlated to a defect of platelet recovery in vivo under acute conditions of thrombocytopenia. Thus, we highlight a role for RGS18 in platelet generation and function, and provide additional insights into the physiology of RGS18.
Collapse
Affiliation(s)
| | | | | | | | | | | | | | | | | | - Tania Sorg
- Department of Scientific Operations PhenoPro, Mouse Clinical Institute (MCI), Strasbourg, France
| | | | - Pierre Savi
- Early to Candidate (E2C), Sanofi, Toulouse, France
| | | |
Collapse
|
28
|
Goswami SC, Mishra SK, Maric D, Kaszas K, Gonnella GL, Clokie SJ, Kominsky HD, Gross JR, Keller JM, Mannes AJ, Hoon MA, Iadarola MJ. Molecular signatures of mouse TRPV1-lineage neurons revealed by RNA-Seq transcriptome analysis. THE JOURNAL OF PAIN 2014; 15:1338-1359. [PMID: 25281809 DOI: 10.1016/j.jpain.2014.09.010] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Revised: 09/10/2014] [Accepted: 09/19/2014] [Indexed: 12/22/2022]
Abstract
UNLABELLED Disorders of pain neural systems are frequently chronic and, when recalcitrant to treatment, can severely degrade the quality of life. The pain pathway begins with sensory neurons in dorsal root or trigeminal ganglia, and the neuronal subpopulations that express the transient receptor potential cation channel, subfamily V, member 1 (TRPV1) ion channel transduce sensations of painful heat and inflammation and play a fundamental role in clinical pain arising from cancer and arthritis. In the present study, we elucidate the complete transcriptomes of neurons from the TRPV1 lineage and a non-TRPV1 neuroglial population in sensory ganglia through the combined application of next-gen deep RNA-Seq, genetic neuronal labeling with fluorescence-activated cell sorting, or neuron-selective chemoablation. RNA-Seq accurately quantitates gene expression, a difficult parameter to determine with most other methods, especially for very low and very high expressed genes. Differentially expressed genes are present at every level of cellular function from the nucleus to the plasma membrane. We identified many ligand receptor pairs in the TRPV1 population, suggesting that autonomous presynaptic regulation may be a major regulatory mechanism in nociceptive neurons. The data define, in a quantitative, cell population-specific fashion, the molecular signature of a distinct and clinically important group of pain-sensing neurons and provide an overall framework for understanding the transcriptome of TRPV1 nociceptive neurons. PERSPECTIVE Next-gen RNA-Seq, combined with molecular genetics, provides a comprehensive and quantitative measurement of transcripts in TRPV1 lineage neurons and a contrasting transcriptome from non-TRPV1 neurons and cells. The transcriptome highlights previously unrecognized protein families, identifies multiple molecular circuits for excitatory or inhibitory autocrine and paracrine signaling, and suggests new combinatorial approaches to pain control.
Collapse
Affiliation(s)
- Samridhi C Goswami
- Anesthesia Section, Department of Perioperative Medicine, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - Santosh K Mishra
- Molecular Genetics Unit, Laboratory of Sensory Biology, National Institute of Dental and Craniofacial Research, Bethesda, Maryland
| | - Dragan Maric
- Laboratory of Neurophysiology, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland
| | - Krisztian Kaszas
- Anesthesia Section, Department of Perioperative Medicine, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - Gian Luigi Gonnella
- Anesthesia Section, Department of Perioperative Medicine, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - Samuel J Clokie
- Anesthesia Section, Department of Perioperative Medicine, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - Hal D Kominsky
- Anesthesia Section, Department of Perioperative Medicine, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - Jacklyn R Gross
- Anesthesia Section, Department of Perioperative Medicine, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - Jason M Keller
- Anesthesia Section, Department of Perioperative Medicine, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - Andrew J Mannes
- Anesthesia Section, Department of Perioperative Medicine, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - Mark A Hoon
- Molecular Genetics Unit, Laboratory of Sensory Biology, National Institute of Dental and Craniofacial Research, Bethesda, Maryland
| | - Michael J Iadarola
- Anesthesia Section, Department of Perioperative Medicine, Clinical Center, National Institutes of Health, Bethesda, Maryland.
| |
Collapse
|
29
|
Hassan B, Kim JS, Farrag M, Kaufman MP, Ruiz-Velasco V. Alteration of the mu opioid receptor: Ca2+ channel signaling pathway in a subset of rat sensory neurons following chronic femoral artery occlusion. J Neurophysiol 2014; 112:3104-15. [PMID: 25231620 DOI: 10.1152/jn.00630.2014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The exercise pressor reflex, a crucial component of the cardiovascular response under physiological and pathophysiological states, is activated via metabolic and mechanical mediators that originate from contracting muscles and stimulate group III and IV afferents. We reported previously that stimulation of mu opioid receptors (MOR), expressed in both afferents, led to a significant attenuation of the reflex in rats whose femoral arteries had been occluded for 72 h. The present study examined the effect of arterial occlusion on the signaling components involved in the opioid-mediated modulation of Ca(2+) channels in rat dorsal root ganglion neurons innervating the triceps surae muscles. We focused on neurons that were transfected with cDNA coding for enhanced green fluorescent protein whose expression is driven by the voltage-gated Na(+) channel 1.8 (Na(V)1.8) promoter region, a channel expressed primarily in nociceptive neurons. With the use of a small interference RNA approach, our results show that the pertussis toxin-sensitive Gα(i3) subunit couples MOR with Ca(2+) channels. We observed a significant leftward shift of the MOR agonist [D-Ala2-N-Me-Phe4-Glycol5]-enkephalin concentration-response relationship in neurons isolated from rats with occluded arteries compared with those that were perfused freely. Femoral occlusion did not affect Ca(2+) channel density or the fraction of the main Ca(2+) channel subtype. Furthermore, Western blotting analysis indicated that the leftward shift did not result from either increased Gα(i3) or MOR expression. Finally, all neurons from both groups exhibited an inward current following exposure of the transient potential receptor vanilloid 1 (TRPV1) agonist, 8-methyl-N-vanillyl-6-nonenamide. These findings suggest that sensory neurons mediating the exercise pressor reflex express Na(V)1.8 and TRPV1 channels, and femoral occlusion alters the MOR pharmacological profile.
Collapse
Affiliation(s)
- Bassil Hassan
- Department of Anesthesiology, Penn State College of Medicine, Hershey, Pennsylvania; and
| | - Joyce S Kim
- Heart and Vascular Institute, Penn State College of Medicine, Hershey, Pennsylvania
| | - Mohamed Farrag
- Department of Anesthesiology, Penn State College of Medicine, Hershey, Pennsylvania; and
| | - Marc P Kaufman
- Heart and Vascular Institute, Penn State College of Medicine, Hershey, Pennsylvania
| | - Victor Ruiz-Velasco
- Department of Anesthesiology, Penn State College of Medicine, Hershey, Pennsylvania; and
| |
Collapse
|
30
|
Ostrovskaya O, Xie K, Masuho I, Fajardo-Serrano A, Lujan R, Wickman K, Martemyanov KA. RGS7/Gβ5/R7BP complex regulates synaptic plasticity and memory by modulating hippocampal GABABR-GIRK signaling. eLife 2014; 3:e02053. [PMID: 24755289 PMCID: PMC3988575 DOI: 10.7554/elife.02053] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
In the hippocampus, the inhibitory neurotransmitter GABA shapes the activity of the output pyramidal neurons and plays important role in cognition. Most of its inhibitory effects are mediated by signaling from GABAB receptor to the G protein-gated Inwardly-rectifying K+ (GIRK) channels. Here, we show that RGS7, in cooperation with its binding partner R7BP, regulates GABABR-GIRK signaling in hippocampal pyramidal neurons. Deletion of RGS7 in mice dramatically sensitizes GIRK responses to GABAB receptor stimulation and markedly slows channel deactivation kinetics. Enhanced activity of this signaling pathway leads to decreased neuronal excitability and selective disruption of inhibitory forms of synaptic plasticity. As a result, mice lacking RGS7 exhibit deficits in learning and memory. We further report that RGS7 is selectively modulated by its membrane anchoring subunit R7BP, which sets the dynamic range of GIRK responses. Together, these results demonstrate a novel role of RGS7 in hippocampal synaptic plasticity and memory formation. DOI:http://dx.doi.org/10.7554/eLife.02053.001 Neurons communicate with one another at junctions called synapses. The arrival of an electrical signal known as an action potential at the first cell causes molecules known as neurotransmitters to be released into the synapse. These molecules diffuse across the gap between the neurons and bind to receptors on the receiving cell. Some neurotransmitters, such as glutamate, activate cells when they bind to receptors, thus making it easier for the second neuron to ‘fire’ (i.e., to generate an action potential). By contrast, other neurotransmitters, such as GABA, usually make it harder for the second neuron to fire. Many of the effects of GABA involve a type of receptor called GABAB. When GABA binds to one of these receptors, a molecule called a G-protein is recruited to the receptor. This activates the G-protein, triggering a cascade of events inside the cell that lead ultimately to the opening of potassium ion channels, which as known as GIRKs, in the cell membrane. Positively charged potassium ions then leave the cell through these channels, and this makes it more difficult for the cell to fire. Now, Ostrovskaya et al. have revealed that a complex of three proteins regulates the interaction between GABAB receptors and GIRK channels. In neurons that lack either of these proteins, the receptors have less influence on GIRKs than in normal cells. Moreover, mice that lack one of the proteins (called RGS7) perform less well in various learning and memory tests: for example, they take longer than normal animals to learn the location of an escape platform in a water maze, or to retain a memory of a fearful event. By identifying the proteins that regulate the interaction between GABAB receptors and GIRKs, Ostrovskaya et al. have helped to unravel a key signaling cascade relevant to cognition. Given that GIRK channels have recently been implicated in Down’s syndrome, these insights may also increase understanding of cognitive impairments in neuropsychiatric disorders. DOI:http://dx.doi.org/10.7554/eLife.02053.002
Collapse
Affiliation(s)
- Olga Ostrovskaya
- Department of Neuroscience, The Scripps Research Institute, Jupiter, United States
| | | | | | | | | | | | | |
Collapse
|
31
|
Protection of cardiomyocytes from the hypoxia-mediated injury by a peptide targeting the activator of G-protein signaling 8. PLoS One 2014; 9:e91980. [PMID: 24632710 PMCID: PMC3954831 DOI: 10.1371/journal.pone.0091980] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Accepted: 02/16/2014] [Indexed: 11/19/2022] Open
Abstract
Signaling via heterotrimeric G-protein is involved in the development of human diseases including ischemia-reperfusion injury of the heart. We previously identified an ischemia-inducible G-protein activator, activator of G-protein signaling 8 (AGS8), which regulates Gβγ signaling and plays a key role in the hypoxia-induced apoptosis of cardiomyocytes. Here, we attempted to intervene in the AGS8-Gβγ signaling process and protect cardiomyocytes from hypoxia-induced apoptosis with a peptide that disrupted the AGS8-Gβγ interaction. Synthesized AGS8-peptides, with amino acid sequences based on those of the Gβγ-binding domain of AGS8, successfully inhibited the association of AGS8 with Gβγ. The AGS8-peptide effectively blocked hypoxia-induced apoptosis of cardiomyocytes, as determined by DNA end-labeling and an increase in cleaved caspase-3. AGS8-peptide also inhibited the change in localization/permeability of channel protein connexin 43, which was mediated by AGS8-Gβγ under hypoxia. Small compounds that inhibit a wide range of Gβγ signals caused deleterious effects in cardiomyocytes. In contrast, AGS8-peptide did not cause cell damage under normoxia, suggesting an advantage inherent in targeted disruption of the AGS8-Gβγ signaling pathway. These data indicate a pivotal role for the interaction of AGS8 with Gβγ in hypoxia-induced apoptosis of cardiomyocytes, and suggest that targeted disruption of the AGS8-Gβγ signal provides a novel approach for protecting the myocardium against ischemic injury.
Collapse
|
32
|
Luján R, Marron Fernandez de Velasco E, Aguado C, Wickman K. New insights into the therapeutic potential of Girk channels. Trends Neurosci 2013; 37:20-9. [PMID: 24268819 DOI: 10.1016/j.tins.2013.10.006] [Citation(s) in RCA: 95] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Revised: 10/24/2013] [Accepted: 10/25/2013] [Indexed: 01/01/2023]
Abstract
G protein-dependent signaling pathways control the activity of excitable cells of the nervous system and heart, and are the targets of neurotransmitters, clinically relevant drugs, and drugs of abuse. G protein-gated inwardly rectifying potassium (K(+)) (Girk/Kir3) channels are a key effector in inhibitory signaling pathways. Girk-dependent signaling contributes to nociception and analgesia, reward-related behavior, mood, cognition, and heart-rate regulation, and has been linked to epilepsy, Down syndrome, addiction, and arrhythmias. We discuss recent advances in our understanding of Girk channel structure, organization in signaling complexes, and plasticity, as well as progress on the development of subunit-selective Girk modulators. These findings offer new hope for the selective manipulation of Girk channels to treat a variety of debilitating afflictions.
Collapse
Affiliation(s)
- Rafael Luján
- Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento de Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha, Campus Biosanitario, C/Almansa 14, 02008 Albacete, Spain.
| | | | - Carolina Aguado
- Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento de Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha, Campus Biosanitario, C/Almansa 14, 02008 Albacete, Spain
| | - Kevin Wickman
- Department of Pharmacology, University of Minnesota, 321 Church Street South East, Minneapolis, MN 55455, USA.
| |
Collapse
|
33
|
Labuda M, Laberge S, Brière J, Bérubé D, Krajinovic M. RGS5 gene and therapeutic response to short acting bronchodilators in paediatric asthma patients. Pediatr Pulmonol 2013. [PMID: 23193110 DOI: 10.1002/ppul.22723] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Short-acting β2-adrenergic receptor agonists are commonly used bronchodilators for symptom relief in asthmatics. Recent evidence demonstrated that prolonged exposure of cultured airway smooth muscle cells to β2 agonists directly augments procontractile signaling pathways with the change in expression of regulator of G protein signaling 5 (RGS5). The aim of this study was to test whether genetic variants in RGS5 gene affect the response to short acting β2-agonists. Bronchodilator responsiveness was assessed in 137 asthmatic children by % change in baseline forced expiratory volume in 1 sec (FEV1 ) after administration of albuterol. The analyses were performed in patients with FEV1 /FVC ratio below 0.9 (FVC-forced vital capacity, n = 99). FEV1 % change adjusted for baseline FEV1 values was significantly different between genotypes of rs10917696 C/T polymorphism (P = 0.008). The association remained significant with inclusion of age, sex, atopy, parental smoking, and controller medications into multivariate model (P = 0.005). We also identified additive effect on the treatment outcome with previously published genetic variant G/A rs1544791 in phosphodiesterase 4 (PDE4D) gene. Carriers of two risk alleles (C and G) had adjusted mean % FEV1 change value 4.6 ± 1.3, while carriers of one and none of the risk alleles had 8.1 ± 0.7% and 13.5 ± 2.4%, respectively, P = 0.001. Our work identifies a new genetic variant in RGS5 demonstrating additive effect with PDE4D, both implicated in modulation of asthma treatment.
Collapse
|
34
|
McNeely PM, Naranjo AN, Robinson AS. Structure-function studies with G protein-coupled receptors as a paradigm for improving drug discovery and development of therapeutics. Biotechnol J 2013; 7:1451-61. [PMID: 23213015 DOI: 10.1002/biot.201200076] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2012] [Revised: 10/07/2012] [Accepted: 10/10/2012] [Indexed: 12/21/2022]
Abstract
There are a great variety of human membrane proteins, and these currently form the largest group of targets for marketed drugs. Despite the advances in drug design, however, promiscuity between drug molecules and targets often leads to undesired signaling effects, which result in unintended side effects. In this review, one family of membrane proteins - the G protein-coupled receptors (GPCRs) - is used as a model to review experimental techniques that may be used to examine the activity of membrane proteins. As these receptors are highly relevant to healthy human physiology and represent the largest family of drug targets, they represent an excellent model for membrane proteins in general. We also review experimental evidence that suggests there may be multiple ways to target a GPCR - and by extension, membrane proteins - to more effectively target unhealthy phenotypes while reducing the occurrence and severity of side effects.
Collapse
Affiliation(s)
- Patrick M McNeely
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE, USA
| | | | | |
Collapse
|
35
|
Abstract
The Hippo pathway controls organ size in diverse species, whereas pathway deregulation can induce tumours in model organisms and occurs in a broad range of human carcinomas, including lung, colorectal, ovarian and liver cancer. Despite this, somatic or germline mutations in Hippo pathway genes are uncommon, with only the upstream pathway gene neurofibromin 2 (NF2) recognized as a bona fide tumour suppressor gene. In this Review, we appraise the evidence for the Hippo pathway as a cancer signalling network, and discuss cancer-relevant biological functions, potential mechanisms by which Hippo pathway activity is altered in cancer and emerging therapeutic strategies.
Collapse
Affiliation(s)
- Kieran F Harvey
- Peter MacCallum Cancer Centre, 7 St Andrews Place, East Melbourne, Victoria 3002, Australia.
| | | | | |
Collapse
|
36
|
Louwette S, Van Geet C, Freson K. Regulators of G protein signaling: role in hematopoiesis, megakaryopoiesis and platelet function. J Thromb Haemost 2012; 10:2215-22. [PMID: 22908964 DOI: 10.1111/j.1538-7836.2012.04903.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Regulators of G protein signaling (RGS) are intracellular signaling regulators that bind activated G protein α subunits (Gα) and increase their intrinsic GTPase activity via their common RGS homology domain. In addition to their GTPase accelerating activity (GAP), RGS proteins also contain other domains that regulate their receptor selectivity, their interaction with other proteins such as adenylyl cyclase or their subcellular localization via interaction with scaffold proteins such as tubulin, 14-3-3 or spinophilin. There are at least 37 different RGS family members in humans and numerous physiological functions have been assigned to these proteins, which have rather a tissue-specific expression pattern. The role of some RGS proteins was shown to be important for hematopoiesis. More recent studies also focused on their expression in platelets, and for R4 RGS subfamily members RGS2, RGS16 and RGS18, it could be demonstrated that they regulate megakaryopoiesis and/or platelet function. These functional studies mostly comprised in vitro experiments and in vivo studies using small animal models. Their role in human pathology related to platelet dysfunction remains still largely unknown, except for a case report with a RGS2 gain of function mutation. In addition to an introduction on RGS signaling and different effectors with a special focus on the R4 subfamily members, we here will give an overview of the studies related to the role of RGS proteins in hematopoiesis, megakaryopoiesis and platelet function.
Collapse
Affiliation(s)
- S Louwette
- Center for Molecular and Vascular Biology Departement of Pediatrics, University of Leuven, Leuven, Belgium
| | | | | |
Collapse
|
37
|
Kach J, Sethakorn N, Dulin NO. A finer tuning of G-protein signaling through regulated control of RGS proteins. Am J Physiol Heart Circ Physiol 2012; 303:H19-35. [PMID: 22542620 DOI: 10.1152/ajpheart.00764.2011] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Regulators of G-protein signaling (RGS) proteins are GTPase-activating proteins (GAP) for various Gα subunits of heterotrimeric G proteins. Through this mechanism, RGS proteins regulate the magnitude and duration of G-protein-coupled receptor signaling and are often referred to as fine tuners of G-protein signaling. Increasing evidence suggests that RGS proteins themselves are regulated through multiple mechanisms, which may provide an even finer tuning of G-protein signaling and crosstalk between G-protein-coupled receptors and other signaling pathways. This review summarizes the current data on the control of RGS function through regulated expression, intracellular localization, and covalent modification of RGS proteins, as related to cell function and the pathogenesis of diseases.
Collapse
Affiliation(s)
- Jacob Kach
- Department of Medicine, University of Chicago, Illinois, 60637, USA
| | | | | |
Collapse
|
38
|
Maurice P, Benleulmi-Chaachoua A, Jockers R. Differential assembly of GPCR signaling complexes determines signaling specificity. Subcell Biochem 2012; 63:225-40. [PMID: 23161141 DOI: 10.1007/978-94-007-4765-4_12] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Recent proteomic and biochemical evidence indicates that cellular -signaling is organized in protein modules. G protein-coupled receptors (GPCRs) are privileged entry points for extracellular signals that are transmitted through the plasma membrane into the cell. The adequate cellular response and signaling specificity is regulated by GPCR-associated protein modules. The composition of these modules is dynamic and might depend on receptor stimulation, the proteome of a given cellular context, the subcellular localization of receptor-associated modules, the formation of GPCR oligomers and the variation of expression levels of components of these modules under physiological, for example circadian rhythm, or pathological conditions. The current article will highlight the importance of GPCR-associated protein modules as a biochemical basis for signaling specificity.
Collapse
Affiliation(s)
- Pascal Maurice
- Inserm, U1016, Institut Cochin, 22 rue Méchain, 75014, Paris, France
| | | | | |
Collapse
|