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Madukwe JC, Garland-Kuntz EE, Lyon AM, Smrcka AV. G protein βγ subunits directly interact with and activate phospholipase Cϵ. J Biol Chem 2018. [PMID: 29535186 DOI: 10.1074/jbc.ra118.002354] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Phospholipase C (PLC) enzymes hydrolyze membrane phosphatidylinositol 4,5 bisphosphate (PIP2) and regulate Ca2+ and protein kinase signaling in virtually all mammalian cell types. Chronic activation of the PLCϵ isoform downstream of G protein-coupled receptors (GPCRs) contributes to the development of cardiac hypertrophy. We have previously shown that PLCϵ-catalyzed hydrolysis of Golgi-associated phosphatidylinositol 4-phosphate (PI4P) in cardiac myocytes depends on G protein βγ subunits released upon stimulation with endothelin-1. PLCϵ binds and is directly activated by Ras family small GTPases, but whether they directly interact with Gβγ has not been demonstrated. To identify PLCϵ domains that interact with Gβγ, here we designed various single substitutions and truncations of WT PLCϵ and tested them for activation by Gβγ in transfected COS-7 cells. Deletion of only a single domain in PLCϵ was not sufficient to completely block its activation by Gβγ, but blocked activation by Ras. Simultaneous deletion of the C-terminal RA2 domain and the N-terminal CDC25 and cysteine-rich domains completely abrogated PLCϵ activation by Gβγ, but activation by the GTPase Rho was retained. In vitro reconstitution experiments further revealed that purified Gβγ directly interacts with a purified fragment of PLCϵ (PLCϵ-PH-RA2) and increases PIP2 hydrolysis. Deletion of the RA2 domain decreased Gβγ binding and eliminated Gβγ stimulation of PIP2 hydrolysis. These results provide first evidence that Gβγ directly interacts with PLCϵ and yield insights into the mechanism by which βγ subunits activate PLCϵ.
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Affiliation(s)
- Jerry C Madukwe
- From the Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, Rochester, New York 14267.,Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan 48109
| | | | - Angeline M Lyon
- Department of Chemistry Purdue University, West Lafayette, Indiana 47907, and
| | - Alan V Smrcka
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan 48109
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Balsevich G, Petrie GN, Hill MN. Endocannabinoids: Effectors of glucocorticoid signaling. Front Neuroendocrinol 2017; 47:86-108. [PMID: 28739508 DOI: 10.1016/j.yfrne.2017.07.005] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Revised: 07/17/2017] [Accepted: 07/19/2017] [Indexed: 01/17/2023]
Abstract
For decades, there has been speculation regarding the interaction of cannabinoids with glucocorticoid systems. Given the functional redundancy between many of the physiological effects of glucocorticoids and cannabinoids, it was originally speculated that the biological mechanisms of cannabinoids were mediated by direct interactions with glucocorticoid systems. With the discovery of the endocannabinoid system, additional research demonstrated that it was actually the opposite; glucocorticoids recruit endocannabinoid signaling, and that the engagement of endocannabinoid signaling mediated many of the neurobiological and physiological effects of glucocorticoids. With the development of advances in pharmacology and genetics, significant advances in this area have been made, and it is now clear that functional interactions between these systems are critical for a wide array of physiological processes. The current review acts a comprehensive summary of the contemporary state of knowledge regarding the biological interactions between glucocorticoids and endocannabinoids, and their potential role in health and disease.
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Affiliation(s)
- Georgia Balsevich
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
| | - Gavin N Petrie
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
| | - Matthew N Hill
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada; Mathison Centre for Mental Health Research and Education, University of Calgary, Calgary, AB, Canada; Departments of Cell Biology and Anatomy and Psychiatry, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada.
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Di Marzo V, Stella N, Zimmer A. Endocannabinoid signalling and the deteriorating brain. Nat Rev Neurosci 2015; 16:30-42. [PMID: 25524120 DOI: 10.1038/nrn3876] [Citation(s) in RCA: 266] [Impact Index Per Article: 29.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Ageing is characterized by the progressive impairment of physiological functions and increased risk of developing debilitating disorders, including chronic inflammation and neurodegenerative diseases. These disorders have common molecular mechanisms that can be targeted therapeutically. In the wake of the approval of the first cannabinoid-based drug for the symptomatic treatment of multiple sclerosis, we examine how endocannabinoid (eCB) signalling controls--and is affected by--normal ageing and neuroinflammatory and neurodegenerative disorders. We propose a conceptual framework linking eCB signalling to the control of the cellular and molecular hallmarks of these processes, and categorize the key components of endocannabinoid signalling that may serve as targets for novel therapeutics.
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Affiliation(s)
- Vincenzo Di Marzo
- Endocannabinoid Research Group, Institute of Biomolecular Chemistry, Consiglio Nazionale delle Ricerche, Via Campi Flegrei 34, 80078 Pozzuoli, Naples, Italy
| | - Nephi Stella
- 1] Department of Pharmacology, University of Washington. [2] Department of Psychiatry and Behavioral Science, University of Washington, 1959 Pacific Avenue North, Seattle, Washington 98103, USA
| | - Andreas Zimmer
- Institute for Molecular Psychiatry, University of Bonn, Sigmund Freud Straße 25, Bonn 53127, Germany
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Kan W, Adjobo-Hermans M, Burroughs M, Faibis G, Malik S, Tall GG, Smrcka AV. M3 muscarinic receptor interaction with phospholipase C β3 determines its signaling efficiency. J Biol Chem 2014; 289:11206-11218. [PMID: 24596086 DOI: 10.1074/jbc.m113.538546] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Phospholipase Cβ (PLCβ) enzymes are activated by G protein-coupled receptors through receptor-catalyzed guanine nucleotide exchange on Gαβγ heterotrimers containing Gq family G proteins. Here we report evidence for a direct interaction between M3 muscarinic receptor (M3R) and PLCβ3. Both expressed and endogenous M3R interacted with PLCβ in coimmunoprecipitation experiments. Stimulation of M3R with carbachol significantly increased this association. Expression of M3R in CHO cells promoted plasma membrane localization of YFP-PLCβ3. Deletion of the PLCβ3 C terminus or deletion of the PLCβ3 PDZ ligand inhibited coimmunoprecipitation with M3R and M3R-dependent PLCβ3 plasma membrane localization. Purified PLCβ3 bound directly to glutathione S-transferase (GST)-fused M3R intracellular loops 2 and 3 (M3Ri2 and M3Ri3) as well as M3R C terminus (M3R/H8-CT). PLCβ3 binding to M3Ri3 was inhibited when the PDZ ligand was removed. In assays using reconstituted purified components in vitro, M3Ri2, M3Ri3, and M3R/H8-CT potentiated Gαq-dependent but not Gβγ-dependent PLCβ3 activation. Disruption of key residues in M3Ri3N and of the PDZ ligand in PLCβ3 inhibited M3Ri3-mediated potentiation. We propose that the M3 muscarinic receptor maximizes the efficiency of PLCβ3 signaling beyond its canonical role as a guanine nucleotide exchange factor for Gα.
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Affiliation(s)
- Wei Kan
- Departments of Pharmacology and Physiology and University of Rochester School of Medicine and Dentistry, Rochester, New York 14642
| | - Merel Adjobo-Hermans
- Department of Biochemistry, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical Centre, Geert Grooteplein 28, 6525 GA Nijmegen, The Netherlands
| | - Michael Burroughs
- Departments of Pharmacology and Physiology and University of Rochester School of Medicine and Dentistry, Rochester, New York 14642
| | - Guy Faibis
- Departments of Pharmacology and Physiology and University of Rochester School of Medicine and Dentistry, Rochester, New York 14642
| | - Sundeep Malik
- Departments of Pharmacology and Physiology and University of Rochester School of Medicine and Dentistry, Rochester, New York 14642
| | - Gregory G Tall
- Departments of Pharmacology and Physiology and University of Rochester School of Medicine and Dentistry, Rochester, New York 14642
| | - Alan V Smrcka
- Departments of Pharmacology and Physiology and University of Rochester School of Medicine and Dentistry, Rochester, New York 14642; Biochemistry and Biophysics and University of Rochester School of Medicine and Dentistry, Rochester, New York 14642; Aab Institute of Cardiovascular Research, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642 and.
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Chan P, Gabay M, Wright FA, Kan W, Oner SS, Lanier SM, Smrcka AV, Blumer JB, Tall GG. Purification of heterotrimeric G protein alpha subunits by GST-Ric-8 association: primary characterization of purified G alpha(olf). J Biol Chem 2010; 286:2625-35. [PMID: 21115479 DOI: 10.1074/jbc.m110.178897] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Ric-8A and Ric-8B are nonreceptor G protein guanine nucleotide exchange factors that collectively bind the four subfamilies of G protein α subunits. Co-expression of Gα subunits with Ric-8A or Ric-8B in HEK293 cells or insect cells greatly promoted Gα protein expression. We exploited these characteristics of Ric-8 proteins to develop a simplified method for recombinant G protein α subunit purification that was applicable to all Gα subunit classes. The method allowed production of the olfactory adenylyl cyclase stimulatory protein Gα(olf) for the first time and unprecedented yield of Gα(q) and Gα(13). Gα subunits were co-expressed with GST-tagged Ric-8A or Ric-8B in insect cells. GST-Ric-8·Gα complexes were isolated from whole cell detergent lysates with glutathione-Sepharose. Gα subunits were dissociated from GST-Ric-8 with GDP-AlF(4)(-) (GTP mimicry) and found to be >80% pure, bind guanosine 5'-[γ-thio]triphosphate (GTPγS), and stimulate appropriate G protein effector enzymes. A primary characterization of Gα(olf) showed that it binds GTPγS at a rate marginally slower than Gα(s short) and directly activates adenylyl cyclase isoforms 3, 5, and 6 with less efficacy than Gα(s short).
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Affiliation(s)
- PuiYee Chan
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, New York 14642, USA
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Park MS, Dessal AL, Smrcka AV, Stern HA. Evaluating docking methods for prediction of binding affinities of small molecules to the G protein betagamma subunits. J Chem Inf Model 2009; 49:437-43. [PMID: 19434844 DOI: 10.1021/ci800384q] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Several studies have suggested that disrupting interactions of the G protein betagamma subunits with downstream binding partners might be a valuable study for pharmaceutical development. Recently, small molecules have been found which bind to Gbetagamma with high apparent affinity in an enzyme-linked immunosorbent assay (ELISA), have demonstrated selective inhibition of interactions of Gbetagamma with downstream signaling partners, and have been shown to increase antinociceptive effects of morphine and inhibit inflammation in vivo. In this paper we examine several docking and scoring protocols for estimating binding affinities for a set of 830 ligands from the NCI diversity set to the Gbeta1gamma2 subunit and compared these with IC50s measured in a competition ELISA with a high-affinity peptidic ligand. The best-performing docking protocol used a consensus score and ensemble docking and resulted in a 6-fold enrichment of high-affinity compounds in the top-ranked 5% of the ligand data set.
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Affiliation(s)
- Min-Sun Park
- Departments of Biochemistry and Biophysics, University of Rochester, Rochester, New York 14627, USA
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Abstract
G protein betagamma subunits are central participants in G protein-coupled receptor signaling pathways. They interact with receptors, G protein alpha subunits and downstream targets to coordinate multiple, different GPCR functions. Much is known about the biology of Gbetagamma subunits but mysteries remain. Here, we will review what is known about general aspects of structure and function of Gbetagamma as well as discuss emerging mechanisms for regulation of Gbetagamma signaling. Recent data suggest that Gbetagamma is a potential therapeutic drug target. Thus, a thorough understanding of the molecular and physiological functions of Gbetagamma has significant implications.
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Affiliation(s)
- A V Smrcka
- Department of Pharmacology and Physiology, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642, USA.
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