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Ma Z, Du X, Sun Y, Sun K, Zhang X, Wang L, Zhu Y, Basang W, Gao Y. RGS2 attenuates alveolar macrophage damage by inhibiting the Gq/11-Ca 2+ pathway during cowshed PM2.5 exposure, and aberrant RGS2 expression is associated with TLR2/4 activation. Toxicol Appl Pharmacol 2024; 487:116976. [PMID: 38777097 DOI: 10.1016/j.taap.2024.116976] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2024] [Revised: 04/07/2024] [Accepted: 05/18/2024] [Indexed: 05/25/2024]
Abstract
Staff and animals in livestock buildings are constantly exposed to fine particulate matter (PM2.5), which affects their respiratory health. However, its exact pathogenic mechanism remains unclear. Regulator of G-protein signaling 2 (RGS2) has been reported to play a regulatory role in pneumonia. The aim of this study was to explore the therapeutic potential of RGS2 in cowshed PM2.5-induced respiratory damage. PM2.5 was collected from a cattle farm, and the alveolar macrophages (NR8383) of the model animal rat were stimulated with different treatment conditions of cowshed PM2.5. The RGS2 overexpression vector was constructed and transfected it into cells. Compared with the control group, cowshed PM2.5 significantly induced a decrease in cell viability and increased the levels of apoptosis and proinflammatory factor expression. Overexpression of RGS2 ameliorated the above-mentioned cellular changes induced by cowshed PM2.5. In addition, PM2.5 has significantly induced intracellular Ca2+ dysregulation. Affinity inhibition of Gq/11 by RGS2 attenuated the cytosolic calcium signaling pathway mediated by PLCβ/IP3R. To further investigate the causes and mechanisms of action of differential RGS2 expression, the possible effects of oxidative stress and TLR2/4 activation were investigated. The results have shown that RGS2 expression was not only regulated by oxidative stress-induced nitric oxide during cowshed PM2.5 cells stimulation but the activation of TLR2/4 had also an important inhibitory effect on its protein expression. The present study demonstrates the intracellular Ca2+ regulatory role of RGS2 during cellular injury, which could be a potential target for the prevention and treatment of PM2.5-induced respiratory injury.
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Affiliation(s)
- Zhenhua Ma
- Department of Veterinary Medicine, College of Animal Science and Technology, Jilin Agricultural University, Changchun 130118, China; Institute of Animal Husbandry and Veterinary Medicine, Tibet Academy of Agricultural and Animal Husbandry Sciences, Lhasa 850009, China
| | - Xiaohui Du
- Department of Veterinary Medicine, College of Animal Science and Technology, Jilin Agricultural University, Changchun 130118, China
| | - Yize Sun
- Department of Veterinary Medicine, College of Animal Science and Technology, Jilin Agricultural University, Changchun 130118, China
| | - Ke Sun
- Department of Veterinary Medicine, College of Animal Science and Technology, Jilin Agricultural University, Changchun 130118, China
| | - Xiqing Zhang
- Department of Veterinary Medicine, College of Animal Science and Technology, Jilin Agricultural University, Changchun 130118, China
| | - Lixia Wang
- Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun 130102, China
| | - Yanbin Zhu
- Institute of Animal Husbandry and Veterinary Medicine, Tibet Academy of Agricultural and Animal Husbandry Sciences, Lhasa 850009, China
| | - Wangdui Basang
- Institute of Animal Husbandry and Veterinary Medicine, Tibet Academy of Agricultural and Animal Husbandry Sciences, Lhasa 850009, China.
| | - Yunhang Gao
- Department of Veterinary Medicine, College of Animal Science and Technology, Jilin Agricultural University, Changchun 130118, China.
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Falzone ME, MacKinnon R. The mechanism of Gαq regulation of PLCβ3-catalyzed PIP2 hydrolysis. Proc Natl Acad Sci U S A 2023; 120:e2315011120. [PMID: 37991948 PMCID: PMC10691244 DOI: 10.1073/pnas.2315011120] [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: 08/30/2023] [Accepted: 10/13/2023] [Indexed: 11/24/2023] Open
Abstract
PLCβ (Phospholipase Cβ) enzymes cleave phosphatidylinositol 4,5-bisphosphate (PIP2) producing IP3 and DAG (diacylglycerol). PIP2 modulates the function of many ion channels, while IP3 and DAG regulate intracellular Ca2+ levels and protein phosphorylation by protein kinase C, respectively. PLCβ enzymes are under the control of G protein coupled receptor signaling through direct interactions with G proteins Gβγ and Gαq and have been shown to be coincidence detectors for dual stimulation of Gαq and Gαi-coupled receptors. PLCβs are aqueous-soluble cytoplasmic enzymes but partition onto the membrane surface to access their lipid substrate, complicating their functional and structural characterization. Using newly developed methods, we recently showed that Gβγ activates PLCβ3 by recruiting it to the membrane. Using these same methods, here we show that Gαq increases the catalytic rate constant, kcat, of PLCβ3. Since stimulation of PLCβ3 by Gαq depends on an autoinhibitory element (the X-Y linker), we propose that Gαq produces partial relief of the X-Y linker autoinhibition through an allosteric mechanism. We also determined membrane-bound structures of the PLCβ3·Gαq and PLCβ3·Gβγ(2)·Gαq complexes, which show that these G proteins can bind simultaneously and independently of each other to regulate PLCβ3 activity. The structures rationalize a finding in the enzyme assay, that costimulation by both G proteins follows a product rule of each independent stimulus. We conclude that baseline activity of PLCβ3 is strongly suppressed, but the effect of G proteins, especially acting together, provides a robust stimulus upon G protein stimulation.
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Affiliation(s)
- Maria E. Falzone
- Laboratory of Molecular Neurobiology and Biophysics, The Rockefeller University, New York, NY10065
- HHMI, The Rockefeller University, New York, NY10065
| | - Roderick MacKinnon
- Laboratory of Molecular Neurobiology and Biophysics, The Rockefeller University, New York, NY10065
- HHMI, The Rockefeller University, New York, NY10065
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Kolbe MR, Hohmann T, Hohmann U, Maronde E, Golbik R, Prell J, Illert J, Strauss C, Dehghani F. Elucidation of GPR55-Associated Signaling behind THC and LPI Reducing Effects on Ki67-Immunoreactive Nuclei in Patient-Derived Glioblastoma Cells. Cells 2023; 12:2646. [PMID: 37998380 PMCID: PMC10670585 DOI: 10.3390/cells12222646] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Revised: 11/09/2023] [Accepted: 11/13/2023] [Indexed: 11/25/2023] Open
Abstract
GPR55 is involved in many physiological and pathological processes. In cancer, GPR55 has been described to show accelerating and decelerating effects in tumor progression resulting from distinct intracellular signaling pathways. GPR55 becomes activated by LPI and various plant-derived, endogenous, and synthetic cannabinoids. Cannabinoids such as THC exerted antitumor effects by inhibiting tumor cell proliferation or inducing apoptosis. Besides its effects through CB1 and CB2 receptors, THC modulates cellular responses among others via GPR55. Previously, we reported a reduction in Ki67-immunoreactive nuclei of human glioblastoma cells after GPR55 activation in general by THC and in particular by LPI. In the present study, we investigated intracellular mechanisms leading to an altered number of Ki67+ nuclei after stimulation of GPR55 by LPI and THC. Pharmacological analyses revealed a strongly involved PLC-IP3 signaling and cell-type-specific differences in Gα-, Gβγ-, RhoA-ROCK, and calcineurin signaling. Furthermore, immunochemical visualization of the calcineurin-dependent transcription factor NFAT revealed an unchanged subcellular localization after THC or LPI treatment. The data underline the cell-type-specific diversity of GPR55-associated signaling pathways in coupling to intracellular G proteins. Furthermore, this diversity might determine the outcome and the individual responsiveness of tumor cells to GPR55 stimulation by cannabin oids.
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Affiliation(s)
- Marc Richard Kolbe
- Department of Anatomy and Cell Biology, Medical Faculty, Martin Luther University Halle-Wittenberg, Grosse Steinstrasse 52, 06108 Halle (Saale), Germany; (M.R.K.); (T.H.); (U.H.)
| | - Tim Hohmann
- Department of Anatomy and Cell Biology, Medical Faculty, Martin Luther University Halle-Wittenberg, Grosse Steinstrasse 52, 06108 Halle (Saale), Germany; (M.R.K.); (T.H.); (U.H.)
| | - Urszula Hohmann
- Department of Anatomy and Cell Biology, Medical Faculty, Martin Luther University Halle-Wittenberg, Grosse Steinstrasse 52, 06108 Halle (Saale), Germany; (M.R.K.); (T.H.); (U.H.)
| | - Erik Maronde
- Department of Anatomy II, Goethe-University, Theodor-Stern-Kai 7, 60590 Frankfurt am Main, Germany;
| | - Ralph Golbik
- Charles Tanford Protein Centre, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Straße 3a, 06120 Halle (Saale), Germany;
| | - Julian Prell
- Department of Neurosurgery, Medical Faculty, Martin Luther University Halle-Wittenberg, Ernst-Grube-Str. 40, 06120 Halle (Saale), Germany; (J.P.); (J.I.); (C.S.)
| | - Jörg Illert
- Department of Neurosurgery, Medical Faculty, Martin Luther University Halle-Wittenberg, Ernst-Grube-Str. 40, 06120 Halle (Saale), Germany; (J.P.); (J.I.); (C.S.)
| | - Christian Strauss
- Department of Neurosurgery, Medical Faculty, Martin Luther University Halle-Wittenberg, Ernst-Grube-Str. 40, 06120 Halle (Saale), Germany; (J.P.); (J.I.); (C.S.)
| | - Faramarz Dehghani
- Department of Anatomy and Cell Biology, Medical Faculty, Martin Luther University Halle-Wittenberg, Grosse Steinstrasse 52, 06108 Halle (Saale), Germany; (M.R.K.); (T.H.); (U.H.)
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Zhu H, Liu X, Wang X, Li Y, Ma F, Tan B, Zhou P, Fu F, Su R. Gβγ subunit inhibitor decreases DOM-induced head twitch response via the PLCβ/IP3/Ca 2+/ERK and cAMP signaling pathways. Eur J Pharmacol 2023; 957:176038. [PMID: 37657742 DOI: 10.1016/j.ejphar.2023.176038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2023] [Revised: 08/17/2023] [Accepted: 08/30/2023] [Indexed: 09/03/2023]
Abstract
AIMS (-)-2,5-dimethoxy-4-methylamphetamine (DOM) induces the head-twitch response (HTR) primarily by activating the serotonin 5-hydroxytryptamine 2A receptor (5-HT2A receptor) in mice. However, the mechanisms underlying 5-HT2A receptor activation and the HTR remain elusive. Gβγ subunits are a potential treatment target in numerous diseases. The present study investigated the mechanism whereby Gβγ subunits influence DOM-induced HTR. MAIN METHODS The effects of the Gβγ inhibitor 3',4',5',6'-tetrahydroxyspiro[2-benzofuran-3,9'-xanthene]-1-one (gallein) and antagonistic peptide βARKct (β-adrenergic receptor kinase C-terminal fragment) on DOM-induced HTR were studied via an HTR test. The activation of the phospholipase C β (PLCβ)/inositol triphosphate (IP3)/calcium (Ca2+) signaling pathway and extracellular signal-regulated kinase (ERK) following Gβγ subunit inhibition was detected by western blotting, Homogeneous Time-Resolved Fluorescence (HTRF) inositol phosphate (IP1) assay and Fluorometric Imaging Plate Reader (FLIPR) calcium 6 assay. The Gβγ subunit-mediated regulation of cyclic adenosine monophosphate (cAMP) was assessed via a GloSensor™ cAMP assay. KEY FINDINGS The Gβγ subunit inhibitors gallein and βARKct reduced DOM-induced HTR in C57BL/6J mice. Like the 5-HT2A receptor-selective antagonist (R)-[2,3-di(methoxy)phenyl]-[1-[2-(4-fluorophenyl)ethyl]piperidin-4-yl]methanol (M100907), gallein inhibited PLCβ phosphorylation (pPLCβ), IP1 production, Ca2+ transients, ERK1/2 phosphorylation (pERK1/2) and cAMP accumulation induced by DOM in human embryonic kidney (HEK) 293T cells stably or transiently transfected with the human 5-HT2A receptor. Moreover, PLCβ protein inhibitor 1-[6-[[(8R,9S,13S,14S,17S)-3-methoxy-13-methyl-6,7,8,9,11,12,14,15,16,17-decahydrocyclopenta[a]phenanthren-17-yl]amino]hexyl]pyrrole-2,5-dione (U73122) (10 nmol/mouse), intracellular Ca2+ blocker 6-[6-[6-[5-acetamido-4,6-dihydroxy-2-(sulfooxymethyl)oxan-3-yl]oxy-2-carboxy-4-hydroxy-5-sulfooxyoxan-3-yl]oxy-2-(hydroxymethyl)-5-(sulfoamino)-4-sulfooxyoxan-3-yl]oxy-3,4-dihydroxy-5-sulfooxyoxane-2-carboxylic acid (heparin) (5 nmol/mouse), L-type Ca2+ channel blocker 3-O-(2-methoxyethyl) 5-O-propan-2-yl 2,6-dimethyl-4-(3-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylate (nimodipine) (4 mg/kg), mitogen extracellular regulating kinase 1/2 (MEK1/2) inhibitor (Z)-3-amino-3-(4-aminophenyl)sulfanyl-2-[2-(trifluoromethyl)phenyl]prop-2-enenitrile (SL327) (30 mg/kg), and Gαs protein selective antagonist 4,4',4″,4‴-(Carbonylbis-(imino-5,1,3-benzenetriylbis(carbonylimino)))tetrakisbenzene-1,3-disulfonic acid (NF449) (10 nmol/mouse) reduced DOM-induced HTR in C57BL/6J mice. SIGNIFICANCE The Gβγ subunits potentially mediate the HTR after 5-HT2A receptor activation via the PLCβ/IP3/Ca2+/ERK1/2 and cAMP signaling pathways. Inhibitors targeting the Gβγ subunits potentially inhibit the hallucinogenic effects of 5-HT2A receptor agonists.
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Affiliation(s)
- Huili Zhu
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Key Laboratory of Neuropsychopharmacology, Beijing Institute of Pharmacology and Toxicology, 27th Taiping Road, Beijing, 100850, China; School of Pharmacy, Yantai University, Yantai, 264005, China
| | - Xiaoqian Liu
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Key Laboratory of Neuropsychopharmacology, Beijing Institute of Pharmacology and Toxicology, 27th Taiping Road, Beijing, 100850, China
| | - Xiaoxuan Wang
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Key Laboratory of Neuropsychopharmacology, Beijing Institute of Pharmacology and Toxicology, 27th Taiping Road, Beijing, 100850, China
| | - Yulei Li
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Key Laboratory of Neuropsychopharmacology, Beijing Institute of Pharmacology and Toxicology, 27th Taiping Road, Beijing, 100850, China
| | - Fang Ma
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Key Laboratory of Neuropsychopharmacology, Beijing Institute of Pharmacology and Toxicology, 27th Taiping Road, Beijing, 100850, China
| | - Bo Tan
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Key Laboratory of Neuropsychopharmacology, Beijing Institute of Pharmacology and Toxicology, 27th Taiping Road, Beijing, 100850, China
| | - Peilan Zhou
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Key Laboratory of Neuropsychopharmacology, Beijing Institute of Pharmacology and Toxicology, 27th Taiping Road, Beijing, 100850, China.
| | - Fenghua Fu
- School of Pharmacy, Yantai University, Yantai, 264005, China
| | - Ruibin Su
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Key Laboratory of Neuropsychopharmacology, Beijing Institute of Pharmacology and Toxicology, 27th Taiping Road, Beijing, 100850, China.
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5
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Daly C, Plouffe B. Gα q signalling from endosomes: A new conundrum. Br J Pharmacol 2023. [PMID: 37740273 DOI: 10.1111/bph.16248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Revised: 08/08/2023] [Accepted: 09/13/2023] [Indexed: 09/24/2023] Open
Abstract
G-protein-coupled receptors (GPCRs) constitute the largest family of membrane receptors, and are involved in the transmission of a variety of extracellular stimuli such as hormones, neurotransmitters, light and odorants into intracellular responses. They regulate every aspect of physiology and, for this reason, about one third of all marketed drugs target these receptors. Classically, upon binding to their agonist, GPCRs are thought to activate G-proteins from the plasma membrane and to stop signalling by subsequent desensitisation and endocytosis. However, accumulating evidence indicates that, upon internalisation, some GPCRs can continue to activate G-proteins in endosomes. Importantly, this signalling from endomembranes mediates alternative cellular responses other than signalling at the plasma membrane. Endosomal G-protein signalling and its physiological relevance have been abundantly documented for Gαs - and Gαi -coupled receptors. Recently, some Gαq -coupled receptors have been reported to activate Gαq on endosomes and mediate important cellular processes. However, several questions relative to the series of cellular events required to translate endosomal Gαq activation into cellular responses remain unanswered and constitute a new conundrum. How are these responses in endosomes mediated in the quasi absence of the substrate for the canonical Gαq -activated effector? Is there another effector? Is there another substrate? If so, how does this alternative endosomal effector or substrate produce a downstream signal? This review aims to unravel and discuss these important questions, and proposes possible routes of investigation.
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Affiliation(s)
- Carole Daly
- Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast, UK
| | - Bianca Plouffe
- Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast, UK
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6
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Falzone ME, MacKinnon R. The mechanism of Gα q regulation of PLCβ3 -catalyzed PIP2 hydrolysis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.29.555394. [PMID: 37693483 PMCID: PMC10491199 DOI: 10.1101/2023.08.29.555394] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
PLCβ enzymes cleave PIP2 producing IP3 and DAG. PIP2 modulates the function of many ion channels, while IP3 and DAG regulate intracellular Ca 2+ levels and protein phosphorylation by protein kinase C, respectively. PLCβ enzymes are under the control of GPCR signaling through direct interactions with G proteins Gβγ and Gα q and have been shown to be coincidence detectors for dual stimulation of Gα q and G α i coupled receptors. PLCβs are aqueous-soluble cytoplasmic enzymes, but partition onto the membrane surface to access their lipid substrate, complicating their functional and structural characterization. Using newly developed methods, we recently showed that Gβγ activates PLCβ3 by recruiting it to the membrane. Using these same methods, here we show that Gα q increases the catalytic rate constant, k cat , of PLCβ3 . Since stimulation of PLCβ3 by Gα q depends on an autoinhibitory element (the X-Y linker), we propose that Gα q produces partial relief of the X-Y linker autoinhibition through an allosteric mechanism. We also determined membrane-bound structures of the PLCβ3-Gα q , and PLCβ3-Gβγ(2)-Gα q complexes, which show that these G proteins can bind simultaneously and independently of each other to regulate PLCβ3 activity. The structures rationalize a finding in the enzyme assay, that co-stimulation by both G proteins follows a product rule of each independent stimulus. We conclude that baseline activity of PLCβ3 is strongly suppressed, but the effect of G proteins, especially acting together, provides a robust stimulus upon G protein stimulation. Significance Statement For certain cellular signaling processes, the background activity of signaling enzymes must be minimal and stimulus-dependent activation robust. Nowhere is this truer than in signaling by PLCβ3 , whose activity regulates intracellular Ca 2+ , phosphorylation by Protein Kinase C, and the activity of numerous ion channels and membrane receptors. In this study we show how PLCβ3 enzymes are regulated by two kinds of G proteins, Gβγ and Gα q . Enzyme activity studies and structures on membranes show how these G proteins act by separate, independent mechanisms, leading to a product rule of co-stimulation when they act together. The findings explain how cells achieve robust stimulation of PLCβ3 in the setting of very low background activity, properties essential to cell health and survival.
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Sanchez GA, Jutkiewicz EM, Ingram S, Smrcka AV. Coincident Regulation of PLC β Signaling by Gq-Coupled and μ-Opioid Receptors Opposes Opioid-Mediated Antinociception. Mol Pharmacol 2022; 102:269-279. [PMID: 36116788 PMCID: PMC11033930 DOI: 10.1124/molpharm.122.000541] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Accepted: 09/05/2022] [Indexed: 11/22/2022] Open
Abstract
Pain management is an important problem worldwide. The current frontline approach for pain management is the use of opioid analgesics. The primary analgesic target of opioids is the μ-opioid receptor (MOR). Deletion of phospholipase Cβ3 (PLCβ3) or selective inhibition of Gβγ regulation of PLCβ3 enhances the potency of the antinociceptive effects of morphine suggesting a novel strategy for achieving opioid-sparing effects. Here we investigated a potential mechanism for regulation of PLC signaling downstream of MOR in human embryonic kidney 293 cells and found that MOR alone could not stimulate PLC but rather required a coincident signal from a Gq-coupled receptor. Knockout of PLCβ3 or pharmacological inhibition of its upstream regulators, Gβγ or Gq, ex vivo in periaqueductal gray slices increased the potency of the selective MOR agonist [D-Ala2, N-Me-Phe4, Gly5-ol]-enkephalin acetate salt in inhibiting presynaptic GABA release. Finally, inhibition of Gq- G protein-coupled receptor coupling in mice enhanced the antinociceptive effects of morphine. These data support a model where Gq and Gβγ-dependent signaling cooperatively regulate PLC activation to decrease MOR-dependent antinociceptive potency. Ultimately, this could lead to identification of new non-MOR targets that would allow for lower-dose utilization of opioid analgesics. SIGNIFICANCE STATEMENT: Previous work demonstrated that deletion of phospholipase Cβ3 (PLCβ3) in mice potentiates μ-opioid receptor (MOR)-dependent antinociception. How PLCβ3 is regulated downstream of MOR had not been clearly defined. We show that PLC-dependent diacylglycerol generation is cooperatively regulated by MOR-Gβγ and Gq-coupled receptor signaling through PLCβ3 and that blockade of either Gq-signaling or Gβγ signaling enhances the potency of opioids in ex vivo brain slices and in vivo. These results reveal potential novel strategies for improving opioid analgesic potency and safety.
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Affiliation(s)
- Gissell A Sanchez
- Department of Pharmacology, University of Michigan, Ann Arbor, Michigan (G.A.S., E.M.J., A.V.S.) and Department of Neurologic Surgery, Oregon Health Sciences University, Portland, Oregon (S.I.)
| | - Emily M Jutkiewicz
- Department of Pharmacology, University of Michigan, Ann Arbor, Michigan (G.A.S., E.M.J., A.V.S.) and Department of Neurologic Surgery, Oregon Health Sciences University, Portland, Oregon (S.I.)
| | - Susan Ingram
- Department of Pharmacology, University of Michigan, Ann Arbor, Michigan (G.A.S., E.M.J., A.V.S.) and Department of Neurologic Surgery, Oregon Health Sciences University, Portland, Oregon (S.I.)
| | - Alan V Smrcka
- Department of Pharmacology, University of Michigan, Ann Arbor, Michigan (G.A.S., E.M.J., A.V.S.) and Department of Neurologic Surgery, Oregon Health Sciences University, Portland, Oregon (S.I.)
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Pulgar VM, Howlett AC, Eldeeb K. WIN55212-2 Modulates Intracellular Calcium via CB 1 Receptor-Dependent and Independent Mechanisms in Neuroblastoma Cells. Cells 2022; 11:2947. [PMID: 36230909 PMCID: PMC9563019 DOI: 10.3390/cells11192947] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Revised: 09/13/2022] [Accepted: 09/16/2022] [Indexed: 11/29/2022] Open
Abstract
The CB1 cannabinoid receptor (CB1R) and extracellular calcium (eCa2+)-stimulated Calcium Sensing receptor (CaSR) can exert cellular signaling by modulating levels of intracellular calcium ([Ca2+]i). We investigated the mechanisms involved in the ([Ca2+]i) increase in N18TG2 neuroblastoma cells, which endogenously express both receptors. Changes in [Ca2+]i were measured in cells exposed to 0.25 or 2.5 mM eCa2+ by a ratiometric method (Fura-2 fluorescence) and expressed as the difference between baseline and peak responses (ΔF340/380). The increased ([Ca2+]i) in cells exposed to 2.5 mM eCa2+ was blocked by the CaSR antagonist, NPS2143, this inhibition was abrogated upon stimulation with WIN55212-2. WIN55212-2 increased [Ca2+]i at 0.25 and 2.5 mM eCa2+ by 700% and 350%, respectively, but this increase was not replicated by CP55940 or methyl-anandamide. The store-operated calcium entry (SOCE) blocker, MRS1845, attenuated the WIN55212-2-stimulated increase in [Ca2+]i at both levels of eCa2+. Simultaneous perfusion with the CB1 antagonist, SR141716 or NPS2143 decreased the response to WIN55212-2 at 0.25 mM but not 2.5 mM eCa2+. Co-perfusion with the non-CB1/CB2 antagonist O-1918 attenuated the WIN55212-2-stimulated [Ca2+]i increase at both eCa2+ levels. These results are consistent with WIN55212-2-mediated intracellular Ca2+ mobilization from store-operated calcium channel-filled sources that could occur via either the CB1R or an O-1918-sensitive non-CB1R in coordination with the CaSR. Intracellular pathway crosstalk or signaling protein complexes may explain the observed effects.
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Affiliation(s)
- Victor M. Pulgar
- Department of Pharmaceutical and Clinical Sciences, College of Pharmacy and Health Sciences, Campbell University, Buies Creek, NC 27506, USA
- Biomedical Research and Infrastructure Center, Winston-Salem State University, Winston-Salem, NC 27101, USA
- Department of Obstetrics & Gynecology, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA
| | - Allyn C. Howlett
- Department of Physiology & Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA
| | - Khalil Eldeeb
- Department of Physiology & Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA
- Jerry M. Wallace School of Osteopathic Medicine, Campbell University, Buies Creek, NC 27506, USA
- AL Azhar Faculty of Medicine, New Damietta 34518, Egypt
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Selvaraj C, Rudhra O, Alothaim AS, Alkhanani M, Singh SK. Structure and chemistry of enzymatic active sites that play a role in the switch and conformation mechanism. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2022; 130:59-83. [PMID: 35534116 DOI: 10.1016/bs.apcsb.2022.02.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Enzymes, which are biological molecules, are constructed from polypeptide chains, and these molecules are activated through reaction mechanisms. It is the role of enzymes to speed up chemical reactions that are used to build or break down cell structures. Activation energy is reduced by the enzymes' selective binding of substrates in a protected environment. In enzyme tertiary structures, the active sites are commonly situated in a "cleft," which necessitates the diffusion of substrates and products. The amino acid residues of the active site may be far apart in the primary structure owing to the folding required for tertiary structure. Due to their critical role in substrate binding and attraction, changes in amino acid structure at or near the enzyme's active site usually alter enzyme activity. At the enzyme's active site, or where the chemical reactions occur, the substrate is bound. Enzyme substrates are the primary targets of the enzyme's active site, which is designed to assist in the chemical reaction. This chapter elucidates the summary of structure and chemistry of enzymes, their active site features, charges and role of water in the structures to clarify the biochemistry of the enzymes in the depth of atomic features.
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Affiliation(s)
- Chandrabose Selvaraj
- Computer Aided Drug Design and Molecular Modelling Lab, Department of Bioinformatics, Science Block, Alagappa University, Karaikudi, Tamil Nadu, India.
| | - Ondipilliraja Rudhra
- Computer Aided Drug Design and Molecular Modelling Lab, Department of Bioinformatics, Science Block, Alagappa University, Karaikudi, Tamil Nadu, India
| | - Abdulaziz S Alothaim
- Department of Biology, College of Science in Zulfi, Majmaah University, Majmaah, Saudi Arabia
| | - Mustfa Alkhanani
- Emergency Service Department, College of Applied Sciences, Al Maarefa University, Riyadh, Saudi Arabia
| | - Sanjeev Kumar Singh
- Computer Aided Drug Design and Molecular Modelling Lab, Department of Bioinformatics, Science Block, Alagappa University, Karaikudi, Tamil Nadu, India.
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10
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Sanjel B, Kim BH, Song MH, Carstens E, Shim WS. Glucosylsphingosine evokes pruritus via activation of 5-HT 2A receptor and TRPV4 in sensory neurons. Br J Pharmacol 2021; 179:2193-2207. [PMID: 34766332 DOI: 10.1111/bph.15733] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2021] [Revised: 10/25/2021] [Accepted: 10/27/2021] [Indexed: 11/02/2022] Open
Abstract
BACKGROUND AND PURPOSE Glucosylsphingosine (GS), an endogenous sphingolipid, is highly accumulated in the epidermis of patients with atopic dermatitis (AD) due to abnormal ceramide metabolism. More importantly, GS can evoke scratching behaviors. However, the precise molecular mechanism by which GS induces pruritus has been elusive. Thus, the present study aimed to elucidate the molecular signaling pathway of GS, especially at the peripheral sensory neuronal levels. EXPERIMENTAL APPROACH Calcium imaging was used to investigate the responses of HEK293T cells or mouse dorsal root ganglion (DRG) neurons to application of GS. Scratching behavior tests were also performed with wild-type and Trpv4 knockout mice. KEY RESULTS GS activated DRG neurons in a manner involving both the 5-HT2A receptor and TRPV4. Furthermore, GS-induced responses were significantly suppressed by various inhibitors, including ketanserin (5-HT2A receptor antagonist), YM254890 (Gαq/11 inhibitor), gallein (Gβγ complex inhibitor), U73122 (phospholipase C inhibitor), bisindolylmaleimide I (PKC inhibitor), and HC067047 (TRPV4 antagonist). Moreover, DRG neurons from Trpv4 knockout mice exhibited significantly reduced responses to GS. Additionally, GS-evoked scratching behaviors were greatly decreased by pretreatment with inhibitors of either 5-HT2A receptor or TRPV4. As expected, GS-evoked scratching behavior was also significantly decreased in Trpv4 knockout mice. CONCLUSION AND IMPLICATIONS Overall, the present study provides evidence for a novel molecular signaling pathway for GS-evoked pruritus, which utilizes both 5-HT2A receptor and TRPV4 in mouse sensory neurons. Considering the high accumulation of GS in the epidermis of patients with AD, GS could be another pruritogen in patients with AD.
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Affiliation(s)
- Babina Sanjel
- College of Pharmacy, Gachon University, Incheon, Republic of Korea.,Gachon Institute of Pharmaceutical Sciences, Incheon, Republic of Korea
| | - Bo-Hyun Kim
- College of Pharmacy, Gachon University, Incheon, Republic of Korea.,Gachon Institute of Pharmaceutical Sciences, Incheon, Republic of Korea
| | - Myung-Hyun Song
- College of Pharmacy, Gachon University, Incheon, Republic of Korea
| | - Earl Carstens
- Department of Neurobiology, Physiology and Behavior, University of California, Davis, California, USA
| | - Won-Sik Shim
- College of Pharmacy, Gachon University, Incheon, Republic of Korea.,Gachon Institute of Pharmaceutical Sciences, Incheon, Republic of Korea
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11
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Kankanamge D, Ubeysinghe S, Tennakoon M, Pantula PD, Mitra K, Giri L, Karunarathne A. Dissociation of the G protein βγ from the Gq-PLCβ complex partially attenuates PIP2 hydrolysis. J Biol Chem 2021; 296:100702. [PMID: 33901492 PMCID: PMC8138763 DOI: 10.1016/j.jbc.2021.100702] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 04/09/2021] [Accepted: 04/21/2021] [Indexed: 01/14/2023] Open
Abstract
Phospholipase C β (PLCβ), which is activated by the Gq family of heterotrimeric G proteins, hydrolyzes the inner membrane lipid phosphatidylinositol 4,5-bisphosphate (PIP2), generating diacylglycerol and inositol 1,4,5-triphosphate (IP3). Because Gq and PLCβ regulate many crucial cellular processes and have been identified as major disease drivers, activation and termination of PLCβ signaling by the Gαq subunit have been extensively studied. Gq-coupled receptor activation induces intense and transient PIP2 hydrolysis, which subsequently recovers to a low-intensity steady-state equilibrium. However, the molecular underpinnings of this equilibrium remain unclear. Here, we explored the influence of signaling crosstalk between Gq and Gi/o pathways on PIP2 metabolism in living cells using single-cell and optogenetic approaches to spatially and temporally constrain signaling. Our data suggest that the Gβγ complex is a component of the highly efficient lipase GαqGTP-PLCβ-Gβγ. We found that over time, Gβγ dissociates from this lipase complex, leaving the less-efficient GαqGTP-PLCβ lipase complex and allowing the significant partial recovery of PIP2 levels. Our findings also indicate that the subtype of the Gγ subunit in Gβγ fine-tunes the lipase activity of Gq-PLCβ, in which cells expressing Gγ with higher plasma membrane interaction show lower PIP2 recovery. Given that Gγ shows cell- and tissue-specific subtype expression, our findings suggest the existence of tissue-specific distinct Gq-PLCβ signaling paradigms. Furthermore, these results also outline a molecular process that likely safeguards cells from excessive Gq signaling.
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Affiliation(s)
- Dinesh Kankanamge
- Department of Chemistry and Biochemistry, The University of Toledo, Toledo, Ohio, USA
| | - Sithurandi Ubeysinghe
- Department of Chemistry and Biochemistry, The University of Toledo, Toledo, Ohio, USA
| | - Mithila Tennakoon
- Department of Chemistry and Biochemistry, The University of Toledo, Toledo, Ohio, USA
| | - Priyanka Devi Pantula
- Department of Chemical Engineering, Indian Institute of Technology, Hyderabad, Sangareddy, Telangana, India
| | - Kishalay Mitra
- Department of Chemical Engineering, Indian Institute of Technology, Hyderabad, Sangareddy, Telangana, India
| | - Lopamudra Giri
- Department of Chemical Engineering, Indian Institute of Technology, Hyderabad, Sangareddy, Telangana, India
| | - Ajith Karunarathne
- Department of Chemistry and Biochemistry, The University of Toledo, Toledo, Ohio, USA.
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12
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Patt J, Alenfelder J, Pfeil EM, Voss JH, Merten N, Eryilmaz F, Heycke N, Rick U, Inoue A, Kehraus S, Deupi X, Müller CE, König GM, Crüsemann M, Kostenis E. An experimental strategy to probe Gq contribution to signal transduction in living cells. J Biol Chem 2021; 296:100472. [PMID: 33639168 PMCID: PMC8024710 DOI: 10.1016/j.jbc.2021.100472] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Revised: 02/22/2021] [Accepted: 02/23/2021] [Indexed: 12/14/2022] Open
Abstract
Heterotrimeric G protein subunits Gαq and Gα11 are inhibited by two cyclic depsipeptides, FR900359 (FR) and YM-254890 (YM), both of which are being used widely to implicate Gq/11 proteins in the regulation of diverse biological processes. An emerging major research question therefore is whether the cellular effects of both inhibitors are on-target, that is, mediated via specific inhibition of Gq/11 proteins, or off-target, that is, the result of nonspecific interactions with other proteins. Here we introduce a versatile experimental strategy to discriminate between these possibilities. We developed a Gαq variant with preserved catalytic activity, but refractory to FR/YM inhibition. A minimum of two amino acid changes were required and sufficient to achieve complete inhibitor resistance. We characterized the novel mutant in HEK293 cells depleted by CRISPR–Cas9 of endogenous Gαq and Gα11 to ensure precise control over the Gα-dependent cellular signaling route. Using a battery of cellular outcomes with known and concealed Gq contribution, we found that FR/YM specifically inhibited cellular signals after Gαq introduction via transient transfection. Conversely, both inhibitors were inert across all assays in cells expressing the drug-resistant variant. These findings eliminate the possibility that inhibition of non-Gq proteins contributes to the cellular effects of the two depsipeptides. We conclude that combined application of FR or YM along with the drug-resistant Gαq variant is a powerful in vitro strategy to discern on-target Gq against off-target non-Gq action. Consequently, it should be of high value for uncovering Gq input to complex biological processes with high accuracy and the requisite specificity.
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Affiliation(s)
- Julian Patt
- Molecular, Cellular and Pharmacobiology Section, Institute for Pharmaceutical Biology, University of Bonn, Bonn, Germany
| | - Judith Alenfelder
- Molecular, Cellular and Pharmacobiology Section, Institute for Pharmaceutical Biology, University of Bonn, Bonn, Germany
| | - Eva Marie Pfeil
- Molecular, Cellular and Pharmacobiology Section, Institute for Pharmaceutical Biology, University of Bonn, Bonn, Germany
| | - Jan Hendrik Voss
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical and Medicinal Chemistry, University of Bonn, Bonn, Germany
| | - Nicole Merten
- Molecular, Cellular and Pharmacobiology Section, Institute for Pharmaceutical Biology, University of Bonn, Bonn, Germany
| | - Funda Eryilmaz
- Molecular, Cellular and Pharmacobiology Section, Institute for Pharmaceutical Biology, University of Bonn, Bonn, Germany
| | - Nina Heycke
- Molecular, Cellular and Pharmacobiology Section, Institute for Pharmaceutical Biology, University of Bonn, Bonn, Germany
| | - Uli Rick
- Molecular, Cellular and Pharmacobiology Section, Institute for Pharmaceutical Biology, University of Bonn, Bonn, Germany
| | - Asuka Inoue
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Miyagi, Japan
| | - Stefan Kehraus
- Institute for Pharmaceutical Biology, University of Bonn, Bonn, Germany
| | - Xavier Deupi
- Laboratory of Biomolecular Research and Condensed Matter Theory Group, Paul Scherrer Institute, Villigen, Switzerland
| | - Christa E Müller
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical and Medicinal Chemistry, University of Bonn, Bonn, Germany
| | - Gabriele M König
- Institute for Pharmaceutical Biology, University of Bonn, Bonn, Germany
| | - Max Crüsemann
- Institute for Pharmaceutical Biology, University of Bonn, Bonn, Germany
| | - Evi Kostenis
- Molecular, Cellular and Pharmacobiology Section, Institute for Pharmaceutical Biology, University of Bonn, Bonn, Germany.
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13
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Muralidharan K, Van Camp MM, Lyon AM. Structure and regulation of phospholipase Cβ and ε at the membrane. Chem Phys Lipids 2021; 235:105050. [PMID: 33422547 DOI: 10.1016/j.chemphyslip.2021.105050] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Revised: 10/28/2020] [Accepted: 01/04/2021] [Indexed: 12/28/2022]
Abstract
Phospholipase C (PLC) β and ε enzymes hydrolyze phosphatidylinositol (PI) lipids in response to direct interactions with heterotrimeric G protein subunits and small GTPases, which are activated downstream of G protein-coupled receptors (GPCRs) and receptor tyrosine kinases (RTKs). PI hydrolysis generates second messengers that increase the intracellular Ca2+ concentration and activate protein kinase C (PKC), thereby regulating numerous physiological processes. PLCβ and PLCε share a highly conserved core required for lipase activity, but use different strategies and structural elements to autoinhibit basal activity, bind membranes, and engage G protein activators. In this review, we discuss recent structural insights into these enzymes and the implications for how they engage membranes alone or in complex with their G protein regulators.
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Affiliation(s)
- Kaushik Muralidharan
- Department of Biological Sciences, 560 Oval Drive, Purdue University, West Lafayette, IN, 47907, United States.
| | - Michelle M Van Camp
- Department of Chemistry, 560 Oval Drive, Purdue University, West Lafayette, IN, 47907, United States.
| | - Angeline M Lyon
- Department of Biological Sciences, 560 Oval Drive, Purdue University, West Lafayette, IN, 47907, United States; Department of Chemistry, 560 Oval Drive, Purdue University, West Lafayette, IN, 47907, United States.
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14
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Pfeil EM, Brands J, Merten N, Vögtle T, Vescovo M, Rick U, Albrecht IM, Heycke N, Kawakami K, Ono Y, Ngako Kadji FM, Hiratsuka S, Aoki J, Häberlein F, Matthey M, Garg J, Hennen S, Jobin ML, Seier K, Calebiro D, Pfeifer A, Heinemann A, Wenzel D, König GM, Nieswandt B, Fleischmann BK, Inoue A, Simon K, Kostenis E. Heterotrimeric G Protein Subunit Gαq Is a Master Switch for Gβγ-Mediated Calcium Mobilization by Gi-Coupled GPCRs. Mol Cell 2020; 80:940-954.e6. [PMID: 33202251 DOI: 10.1016/j.molcel.2020.10.027] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 09/21/2020] [Accepted: 10/16/2020] [Indexed: 12/18/2022]
Abstract
Mechanisms that control mobilization of cytosolic calcium [Ca2+]i are key for regulation of numerous eukaryotic cell functions. One such paradigmatic mechanism involves activation of phospholipase Cβ (PLCβ) enzymes by G protein βγ subunits from activated Gαi-Gβγ heterotrimers. Here, we report identification of a master switch to enable this control for PLCβ enzymes in living cells. We find that the Gαi-Gβγ-PLCβ-Ca2+ signaling module is entirely dependent on the presence of active Gαq. If Gαq is pharmacologically inhibited or genetically ablated, Gβγ can bind to PLCβ but does not elicit Ca2+ signals. Removal of an auto-inhibitory linker that occludes the active site of the enzyme is required and sufficient to empower "stand-alone control" of PLCβ by Gβγ. This dependence of Gi-Gβγ-Ca2+ on Gαq places an entire signaling branch of G-protein-coupled receptors (GPCRs) under hierarchical control of Gq and changes our understanding of how Gi-GPCRs trigger [Ca2+]i via PLCβ enzymes.
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Affiliation(s)
- Eva Marie Pfeil
- Molecular, Cellular and Pharmacobiology Section, Institute for Pharmaceutical Biology, University of Bonn, Nussallee 6, 53115 Bonn, Germany; Research Training Group 1873, University of Bonn, Bonn, Germany
| | - Julian Brands
- Molecular, Cellular and Pharmacobiology Section, Institute for Pharmaceutical Biology, University of Bonn, Nussallee 6, 53115 Bonn, Germany; Research Training Group 1873, University of Bonn, Bonn, Germany
| | - Nicole Merten
- Molecular, Cellular and Pharmacobiology Section, Institute for Pharmaceutical Biology, University of Bonn, Nussallee 6, 53115 Bonn, Germany
| | - Timo Vögtle
- Institute of Experimental Biomedicine I, University Hospital Würzburg and Rudolf Virchow Center, University of Würzburg, 97080 Würzburg, Germany
| | - Maddalena Vescovo
- Molecular, Cellular and Pharmacobiology Section, Institute for Pharmaceutical Biology, University of Bonn, Nussallee 6, 53115 Bonn, Germany
| | - Ulrike Rick
- Molecular, Cellular and Pharmacobiology Section, Institute for Pharmaceutical Biology, University of Bonn, Nussallee 6, 53115 Bonn, Germany
| | - Ina-Maria Albrecht
- Molecular, Cellular and Pharmacobiology Section, Institute for Pharmaceutical Biology, University of Bonn, Nussallee 6, 53115 Bonn, Germany
| | - Nina Heycke
- Molecular, Cellular and Pharmacobiology Section, Institute for Pharmaceutical Biology, University of Bonn, Nussallee 6, 53115 Bonn, Germany
| | - Kouki Kawakami
- Graduate School of Pharmaceutical Science, Tohoku University, Sendai 980-8578, Japan
| | - Yuki Ono
- Graduate School of Pharmaceutical Science, Tohoku University, Sendai 980-8578, Japan
| | | | - Suzune Hiratsuka
- Graduate School of Pharmaceutical Science, Tohoku University, Sendai 980-8578, Japan
| | - Junken Aoki
- Graduate School of Pharmaceutical Science, Tohoku University, Sendai 980-8578, Japan
| | - Felix Häberlein
- Molecular, Cellular and Pharmacobiology Section, Institute for Pharmaceutical Biology, University of Bonn, Nussallee 6, 53115 Bonn, Germany; Research Training Group 1873, University of Bonn, Bonn, Germany
| | - Michaela Matthey
- Department of Systems Physiology, Medical Faculty, Ruhr University Bochum, 44801 Bochum, Germany; Institute of Physiology I, Life and Brain Center, Medical Faculty, University of Bonn, Venusberg-Campus 1, 53127 Bonn, Germany
| | - Jaspal Garg
- Institute of Pharmacology and Toxicology, University Hospital Bonn, University of Bonn, 53127 Bonn, Germany
| | - Stephanie Hennen
- Molecular, Cellular and Pharmacobiology Section, Institute for Pharmaceutical Biology, University of Bonn, Nussallee 6, 53115 Bonn, Germany
| | - Marie-Lise Jobin
- Institute of Pharmacology and Toxicology and Bio-Imaging Center, University of Würzburg, 97078 Würzburg, Germany
| | - Kerstin Seier
- Institute of Pharmacology and Toxicology and Bio-Imaging Center, University of Würzburg, 97078 Würzburg, Germany
| | - Davide Calebiro
- Institute of Pharmacology and Toxicology and Bio-Imaging Center, University of Würzburg, 97078 Würzburg, Germany; Institute of Metabolism and Systems Research and Centre of Membrane Proteins and Receptors, University of Birmingham, B15 2TT Birmingham, UK
| | - Alexander Pfeifer
- Institute of Physiology I, Life and Brain Center, Medical Faculty, University of Bonn, Venusberg-Campus 1, 53127 Bonn, Germany
| | - Akos Heinemann
- Division of Pharmacology, Otto-Loewi Research Center for Vascular Biology, Immunology and Inflammation, Medical University of Graz, 8010 Graz, Austria
| | - Daniela Wenzel
- Department of Systems Physiology, Medical Faculty, Ruhr University Bochum, 44801 Bochum, Germany; Institute of Physiology I, Life and Brain Center, Medical Faculty, University of Bonn, Venusberg-Campus 1, 53127 Bonn, Germany
| | - Gabriele M König
- Institute for Pharmaceutical Biology, University of Bonn, Nussallee 6, 53115 Bonn, Germany
| | - Bernhard Nieswandt
- Institute of Experimental Biomedicine I, University Hospital Würzburg and Rudolf Virchow Center, University of Würzburg, 97080 Würzburg, Germany
| | - Bernd K Fleischmann
- Institute of Physiology I, Life and Brain Center, Medical Faculty, University of Bonn, Venusberg-Campus 1, 53127 Bonn, Germany
| | - Asuka Inoue
- Graduate School of Pharmaceutical Science, Tohoku University, Sendai 980-8578, Japan
| | - Katharina Simon
- Molecular, Cellular and Pharmacobiology Section, Institute for Pharmaceutical Biology, University of Bonn, Nussallee 6, 53115 Bonn, Germany.
| | - Evi Kostenis
- Molecular, Cellular and Pharmacobiology Section, Institute for Pharmaceutical Biology, University of Bonn, Nussallee 6, 53115 Bonn, Germany.
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15
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Katan M, Cockcroft S. Phospholipase C families: Common themes and versatility in physiology and pathology. Prog Lipid Res 2020; 80:101065. [PMID: 32966869 DOI: 10.1016/j.plipres.2020.101065] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 08/14/2020] [Accepted: 09/17/2020] [Indexed: 12/20/2022]
Abstract
Phosphoinositide-specific phospholipase Cs (PLCs) are expressed in all mammalian cells and play critical roles in signal transduction. To obtain a comprehensive understanding of these enzymes in physiology and pathology, a detailed structural, biochemical, cell biological and genetic information is required. In this review, we cover all these aspects to summarize current knowledge of the entire superfamily. The families of PLCs have expanded from 13 enzymes to 16 with the identification of the atypical PLCs in the human genome. Recent structural insights highlight the common themes that cover not only the substrate catalysis but also the mechanisms of activation. This involves the release of autoinhibitory interactions that, in the absence of stimulation, maintain classical PLC enzymes in their inactive forms. Studies of individual PLCs provide a rich repertoire of PLC function in different physiologies. Furthermore, the genetic studies discovered numerous mutated and rare variants of PLC enzymes and their link to human disease development, greatly expanding our understanding of their roles in diverse pathologies. Notably, substantial evidence now supports involvement of different PLC isoforms in the development of specific cancer types, immune disorders and neurodegeneration. These advances will stimulate the generation of new drugs that target PLC enzymes, and will therefore open new possibilities for treatment of a number of diseases where current therapies remain ineffective.
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Affiliation(s)
- Matilda Katan
- Institute of Structural and Molecular Biology, Division of Biosciences, University College London, Gower Street, London WC1E 6BT, UK
| | - Shamshad Cockcroft
- Department of Neuroscience, Physiology and Pharmacology, Division of Biosciences, University College London, 21 University Street, London WC1E 6JJ, UK.
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16
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Santhosh D, Sherman J, Chowdhury S, Huang Z. Harnessing region-specific neurovascular signaling to promote germinal matrix vessel maturation and hemorrhage prevention. Dis Model Mech 2019; 12:dmm.041228. [PMID: 31601549 PMCID: PMC6899033 DOI: 10.1242/dmm.041228] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Accepted: 10/06/2019] [Indexed: 12/13/2022] Open
Abstract
Germinal matrix hemorrhage (GMH), affecting about 1 in 300 births, is a major perinatal disease with lifelong neurological consequences. Yet despite advances in neonatal medicine, there is no effective intervention. GMH is characterized by localized bleeding in the germinal matrix (GM), due to inherent vessel fragility unique to this developing brain region. Studies have shown that reduced TGFβ signaling contributes to this vascular immaturity. We have previously shown that a region-specific G-protein-coupled receptor pathway in GM neural progenitor cells regulates integrin β8, a limiting activator of pro-TGFβ. In this study, we use mice to test whether this regional pathway can be harnessed for GMH intervention. We first examined the endogenous dynamics of this pathway and found that it displays specific patterns of activation. We then investigated the functional effects of altering these dynamics by chemogenetics and found that there is a narrow developmental window during which this pathway is amenable to manipulation. Although high-level activity in this time window interferes with vessel growth, moderate enhancement promotes vessel maturation without compromising growth. Furthermore, we found that enhancing the activity of this pathway in a mouse model rescues all GMH phenotypes. Altogether, these results demonstrate that enhancing neurovascular signaling through pharmacological targeting of this pathway may be a viable approach for tissue-specific GMH intervention. They also demonstrate that timing and level are likely two major factors crucial for success. These findings thus provide critical new insights into both brain neurovascular biology and the intervention of GMH.
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Affiliation(s)
- Devi Santhosh
- Departments of Neuroscience and Neurology, University of Wisconsin-Madison, Madison, WI 53705, USA.,Program in Genetics and Medical Genetics, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Joe Sherman
- Departments of Neuroscience and Neurology, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Shafi Chowdhury
- Departments of Neuroscience and Neurology, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Zhen Huang
- Departments of Neuroscience and Neurology, University of Wisconsin-Madison, Madison, WI 53705, USA .,Program in Genetics and Medical Genetics, University of Wisconsin-Madison, Madison, WI 53705, USA
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17
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Abstract
G protein-coupled receptors (GPCRs) are the largest class of drug targets, largely owing to their druggability, diversity and physiological efficacy. Many drugs selectively target specific subtypes of GPCRs, but high specificity for individual GPCRs may not be desirable in complex multifactorial disease states in which multiple receptors may be involved. One approach is to target G protein subunits rather than the GPCRs directly. This approach has the potential to achieve broad efficacy by blocking pathways shared by multiple GPCRs. Additionally, because many GPCRs couple to multiple G protein signalling pathways, blocking specific G protein subunits can 'bias' GPCR signals by inhibiting only a subset of these signals. Molecules that target G protein α or βγ-subunits have been developed and show strong efficacy in multiple preclinical disease models and biased inhibition of G protein signalling. In this Review, we discuss the development and characterization of G protein α and βγ-subunit ligands and the preclinical evidence that this exciting new approach has potential for therapeutic efficacy in a number of indications, such as pain, thrombosis, asthma and heart failure.
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18
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Kang N, Kang JY, Park S, Shin DM. Increased store-operated Ca 2+ entry mediated by GNB5 and STIM1. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2018; 22:343-348. [PMID: 29719456 PMCID: PMC5928347 DOI: 10.4196/kjpp.2018.22.3.343] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Revised: 02/14/2018] [Accepted: 02/19/2018] [Indexed: 01/27/2023]
Abstract
Recent human genetic studies have shown that Gβ5 is related to various clinical symptoms, such as sinus bradycardia, cognitive disability, and attention deficit hyperactivity disorder. Although the calcium signaling cascade is closely associated with a heterotrimeric G-protein, the function of Gβ5 in calcium signaling and its relevance to clinical symptoms remain unknown. In this study, we investigated the in vitro changes of store-operated calcium entry (SOCE) with exogenous expression of Gβ5. The cells expressing Gβ5 had enhanced SOCE after depletion of calcium ion inside the endoplasmic reticulum. Gβ5 also augmented Stim1- and Orai1-dependent SOCE. An ORAI1 loss-of-function mutant did not show inhibition of Gβ5-induced SOCE, and a STIM1-ERM truncation mutant showed no enhancement of SOCE. These results suggested a novel role of GNB5 and Stim1, and provided insight into the regulatory mechanism of SOCE.
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Affiliation(s)
- Namju Kang
- Department of Oral Biology, BK21 PLUS Project, Yonsei University College of Dentistry, Seoul 03722, Korea
| | - Jung Yun Kang
- Department of Oral Biology, BK21 PLUS Project, Yonsei University College of Dentistry, Seoul 03722, Korea
| | - Soonhong Park
- Department of Oral Biology, BK21 PLUS Project, Yonsei University College of Dentistry, Seoul 03722, Korea
| | - Dong Min Shin
- Department of Oral Biology, BK21 PLUS Project, Yonsei University College of Dentistry, Seoul 03722, Korea
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19
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The Role of Phospholipase C Signaling in Macrophage-Mediated Inflammatory Response. J Immunol Res 2018; 2018:5201759. [PMID: 30057916 PMCID: PMC6051040 DOI: 10.1155/2018/5201759] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2017] [Revised: 10/06/2017] [Accepted: 11/05/2017] [Indexed: 12/15/2022] Open
Abstract
Macrophages are crucial members of the mononuclear phagocyte system essential to protect the host from invading pathogens and are central to the inflammatory response with their ability to acquire specialized phenotypes of inflammatory (M1) and anti-inflammatory (M2) and to produce a pool of inflammatory mediators. Equipped with a broad range of receptors, such as Toll-like receptor 4 (TLR4), CD14, and Fc gamma receptors (FcγRs), macrophages can efficiently recognize and phagocytize invading pathogens and secrete cytokines by triggering various secondary signaling pathways. Phospholipase C (PLC) is a family of enzymes that hydrolyze phospholipids, the most significant of which is phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2]. Cleavage at the internal phosphate ester generates two second messengers, inositol 1,4,5-trisphosphate (IP3) and diacylglycerol (DAG), both of which mediate in diverse cellular functions including the inflammatory response. Recent studies have shown that some PLC isoforms are involved in multiple stages in TLR4-, CD14-, and FcγRs-mediated activation of nuclear factor kappa B (NF-κB), mitogen-activated protein kinase (MAPK), and interferon regulatory factors (IRFs), all of which are associated with the regulation of the inflammatory response. Therefore, secondary signaling by PLC is implicated in the pathogenesis of numerous inflammatory diseases. This review provides an overview of our current knowledge on how PLC signaling regulates the macrophage-mediated inflammatory response.
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20
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Ben-Salem S, Robbins SM, Sobreira NLM, Lyon A, Al-Shamsi AM, Islam BK, Akawi NA, John A, Thachillath P, Hamed SA, Valle D, Ali BR, Al-Gazali L. Defect in phosphoinositide signalling through a homozygous variant in PLCB3 causes a new form of spondylometaphyseal dysplasia with corneal dystrophy. J Med Genet 2018; 55:122-130. [PMID: 29122926 PMCID: PMC8215682 DOI: 10.1136/jmedgenet-2017-104827] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Revised: 09/19/2017] [Accepted: 10/06/2017] [Indexed: 02/05/2023]
Abstract
BACKGROUND Bone dysplasias are a large group of disorders affecting the growth and structure of the skeletal system. METHODS In the present study, we report the clinical and molecular delineation of a new form of syndromic autosomal recessive spondylometaphyseal dysplasia (SMD) in two Emirati first cousins. They displayed postnatal growth deficiency causing profound limb shortening with proximal and distal segments involvement, narrow chest, radiological abnormalities involving the spine, pelvis and metaphyses, corneal clouding and intellectual disability. Whole genome homozygosity mapping localised the genetic cause to 11q12.1-q13.1, a region spanning 19.32 Mb with ~490 genes. Using whole exome sequencing, we identified four novel homozygous variants within the shared block of homozygosity. Pathogenic variants in genes involved in phospholipid metabolism, such as PLCB4 and PCYT1A, are known to cause bone dysplasia with or without eye anomalies, which led us to select PLCB3 as a strong candidate. This gene encodes phospholipase C β 3, an enzyme that converts phosphatidylinositol 4,5 bisphosphate (PIP2) to inositol 1,4,5 triphosphate (IP3) and diacylglycerol. RESULTS The identified variant (c.2632G>T) substitutes a serine for a highly conserved alanine within the Ha2' element of the proximal C-terminal domain. This disrupts binding of the Ha2' element to the catalytic core and destabilises PLCB3. Here we show that this hypomorphic variant leads to elevated levels of PIP2 in patient fibroblasts, causing disorganisation of the F-actin cytoskeleton. CONCLUSIONS Our results connect a homozygous loss of function variant in PLCB3 with a new SMD associated with corneal dystrophy and developmental delay (SMDCD).
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Affiliation(s)
- Salma Ben-Salem
- Department of Pathology, College of Medicine and Heath Sciences, University Al-Ain, Al Ain, AbuDhabi, United Arab Emirates
| | - Sarah M Robbins
- Human genetics and Molecular Biology, Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Nara LM Sobreira
- Human genetics and Molecular Biology, Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Angeline Lyon
- Chemistry and Biological Sciences, West Lafayette, USA
| | - Aisha M Al-Shamsi
- Department of Paediatrics, Tawam Hospital, Al-Ain, United Arab Emirates
| | - Barira K Islam
- Department of Paediatrics, College of Medicine and Heath Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
| | - Nadia A Akawi
- Division of Cardiovascular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, Oxfordshire, UK
| | - Anne John
- Department of Pathology, College of Medicine and Heath Sciences, University Al-Ain, Al Ain, AbuDhabi, United Arab Emirates
| | - Pramathan Thachillath
- Department of Paediatrics, College of Medicine and Heath Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
| | - Sania Al Hamed
- Department of Paediatrics, College of Medicine and Heath Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
| | - David Valle
- Human genetics and Molecular Biology, Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Bassam R Ali
- Department of Pathology, College of Medicine and Heath Sciences, University Al-Ain, Al Ain, AbuDhabi, United Arab Emirates
| | - Lihadh Al-Gazali
- Department of Paediatrics, College of Medicine and Heath Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
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21
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Huang W, Wang X, Endo-Streeter S, Barrett M, Waybright J, Wohlfeld C, Hajicek N, Harden TK, Sondek J, Zhang Q. A membrane-associated, fluorogenic reporter for mammalian phospholipase C isozymes. J Biol Chem 2017; 293:1728-1735. [PMID: 29263090 DOI: 10.1074/jbc.ra117.000926] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2017] [Revised: 12/05/2017] [Indexed: 11/06/2022] Open
Abstract
A diverse group of cell-surface receptors, including many G protein-coupled receptors and receptor tyrosine kinases, activate phospholipase C (PLC) isozymes to hydrolyze phosphatidylinositol 4,5-bisphosphate into the second messengers diacylglycerol and 1,4,5-inositol trisphosphate. Consequently, PLCs control various cellular processes, and their aberrant regulation contributes to many diseases, including cancer, atherosclerosis, and rheumatoid arthritis. Despite the widespread importance of PLCs in human biology and disease, it has been impossible to directly monitor the real-time activation of these enzymes at membranes. To overcome this limitation, here we describe XY-69, a fluorogenic reporter that preferentially partitions into membranes and provides a selective tool for measuring the real-time activity of PLCs as either purified enzymes or in cellular lysates. Indeed, XY-69 faithfully reported the membrane-dependent activation of PLC-β3 by Gαq Therefore, XY-69 can replace radioactive phosphatidylinositol 4,5-bisphosphate used in conventional PLC assays and will enable high-throughput screens to identify both orthosteric and allosteric PLC inhibitors. In the future, cell-permeable variants of XY-69 represent promising candidates for reporting the activation of PLCs in live cells with high spatiotemporal resolution.
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Affiliation(s)
- Weigang Huang
- From the Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy
| | - Xiaoyang Wang
- From the Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy
| | | | | | - Jarod Waybright
- From the Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy
| | - Christian Wohlfeld
- From the Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy
| | | | | | - John Sondek
- Departments of Pharmacology and.,Biochemistry and Biophysics, School of Medicine, and.,the Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Qisheng Zhang
- From the Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, .,Departments of Pharmacology and.,the Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
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The Complement System Component C5a Produces Thermal Hyperalgesia via Macrophage-to-Nociceptor Signaling That Requires NGF and TRPV1. J Neurosci 2017; 36:5055-70. [PMID: 27147658 DOI: 10.1523/jneurosci.3249-15.2016] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Accepted: 03/21/2016] [Indexed: 12/31/2022] Open
Abstract
UNLABELLED The complement cascade is a principal component of innate immunity. Recent studies have underscored the importance of C5a and other components of the complement system in inflammatory and neuropathic pain, although the underlying mechanisms are largely unknown. In particular, it is unclear how the complement system communicates with nociceptors and which ion channels and receptors are involved. Here we demonstrate that inflammatory thermal and mechanical hyperalgesia induced by complete Freund's adjuvant was accompanied by C5a upregulation and was markedly reduced by C5a receptor (C5aR1) knock-out or treatment with the C5aR1 antagonist PMX53. Direct administration of C5a into the mouse hindpaw produced strong thermal hyperalgesia, an effect that was absent in TRPV1 knock-out mice, and was blocked by the TRPV1 antagonist AMG9810. Immunohistochemistry of mouse plantar skin showed prominent expression of C5aR1 in macrophages. Additionally, C5a evoked strong Ca(2+) mobilization in macrophages. Macrophage depletion in transgenic macrophage Fas-induced apoptosis mice abolished C5a-dependent thermal hyperalgesia. Examination of inflammatory mediators following C5a injection revealed a rapid upregulation of NGF, a mediator known to sensitize TRPV1. Preinjection of an NGF-neutralizing antibody or Trk inhibitor GNF-5837 prevented C5a-induced thermal hyperalgesia. Notably, NGF-induced thermal hyperalgesia was unaffected by macrophage depletion. Collectively, these results suggest that complement fragment C5a induces thermal hyperalgesia by triggering macrophage-dependent signaling that involves mobilization of NGF and NGF-dependent sensitization of TRPV1. Our findings highlight the importance of macrophage-to-neuron signaling in pain processing and identify C5a, NGF, and TRPV1 as key players in this cross-cellular communication. SIGNIFICANCE STATEMENT This study provides mechanistic insight into how the complement system, a key component of innate immunity, regulates the development of pain hypersensitivity. We demonstrate a crucial role of the C5a receptor, C5aR1, in the development of inflammatory thermal and mechanical sensitization. By focusing on the mechanisms of C5a-induced thermal hyperalgesia, we show that this process requires recruitment of macrophages and initiation of macrophage-to-nociceptor signaling. At the molecular level, we demonstrate that this signaling depends on NGF and is mediated by the heat-sensitive nociceptive channel TRPV1. This deeper understanding of how immune cells and neurons interact to regulate pain processing is expected to facilitate mechanism-based approaches in the development of new analgesics.
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23
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Qian J, Gu Y, Wu C, Yu F, Chen Y, Zhu J, Yao X, Bei C, Zhu Q. Agonist-induced activation of human FFA1 receptor signals to extracellular signal-regulated kinase 1 and 2 through Gq- and Gi-coupled signaling cascades. Cell Mol Biol Lett 2017; 22:13. [PMID: 28747926 PMCID: PMC5522598 DOI: 10.1186/s11658-017-0043-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Accepted: 07/07/2017] [Indexed: 12/18/2022] Open
Abstract
Background FFA1 is abundantly expressed in the liver, skeletal muscle, monocytes and nervous system, but is particularly abundant in pancreatic β cells. It is widely believed that FFA1 exerts its regulatory roles in a variety of physiological and pathological functions. In response to oleic acid, FFA1 has been shown to induce the activation of extracellular signal-regulated kinase 1 and 2 (ERK1/2) through a mechanism involving EGFR transactivation in a breast cancer cell line. However, the underlying molecular mechanism for ERK1/2 activation mediated by n-6 free fatty acid (LA) in HEK293 cells remains to be further elucidated. Methods A FLAG-FFA1 vector was stably expressed in HEK293 cells. Western blot analysis was applied to investigate the change in LA-induced ERK1/2 phosphorylation change in response to kinase inhibitors. Arrestin-2/3-specific siRNA was used to analyze the effect of arrestin-2/3 knockdown on FFA1-mediated ERK1/2 activation. Results We proved that activation of ERK1/2 by LA was rapid, peaking at 5 min. Further experiments proved that FFA1 couples to a Gq protein and activates PI-PLC, which induces the IP3/Ca2+ and DAG/PKC signal pathways, both of which are involved in ERK1/2 activation. We also showed that there is no EGFR transactivation, arrestin-2/3 or Gβγ pathway participation in ERK1/2 phosphorylation. Treating cells with PTX abolished ERK1/2 activation at a late time point (≥20 min), indicating a critical role for Gi subunits in FFA1-mediated ERK1/2 activation. Conclusions Our study provides a detailed delineation of the LA-mediated activation of ERK1/2 in HEK293 cells that are stably transfected with human FFA1. We also present evidence of Gi/Gq-induced synergism in the regulation of ERK1/2 phosphorylation. These observations may provide new insights into the pharmacological effects of FFA1 and the physiological functions modulated by FFA1-mediated activation of ERK1/2. Electronic supplementary material The online version of this article (doi:10.1186/s11658-017-0043-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Jing Qian
- Huzhou University Schools of Nursing and Medicine, Huzhou University, HuZhou, 313000 China
| | - Yuyang Gu
- Huzhou University Schools of Nursing and Medicine, Huzhou University, HuZhou, 313000 China
| | - Chun Wu
- Institute of Biochemistry, College of Life Science, Zijingang Campus, Zhejiang University, Hangzhou, Zhejiang 310058 China
| | - Feng Yu
- Huzhou University Schools of Nursing and Medicine, Huzhou University, HuZhou, 313000 China
| | - Yuqi Chen
- Huzhou University Schools of Nursing and Medicine, Huzhou University, HuZhou, 313000 China
| | - Jingmei Zhu
- Huzhou University Schools of Nursing and Medicine, Huzhou University, HuZhou, 313000 China
| | - Xingyi Yao
- Huzhou University Schools of Nursing and Medicine, Huzhou University, HuZhou, 313000 China
| | - Chen Bei
- Huzhou University Schools of Nursing and Medicine, Huzhou University, HuZhou, 313000 China
| | - Qingqing Zhu
- Huzhou University Schools of Nursing and Medicine, Huzhou University, HuZhou, 313000 China
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24
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Chan ASL, Lau WWI, Szeto ACH, Wang J, Wong YH. Differential Regulation of CXCL8 Production by Different G Protein Subunits with Synergistic Stimulation by Gi- and Gq-Regulated Pathways. J Mol Biol 2016; 428:3869-84. [PMID: 27040396 DOI: 10.1016/j.jmb.2016.03.026] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Revised: 03/22/2016] [Accepted: 03/24/2016] [Indexed: 01/14/2023]
Abstract
CXCL8 (also known as interleukin-8 or IL-8) is a proinflammatory chemokine that not only modulates the inflammatory and immune responses, but whose upregulation is often associated with diseases including various types of cancer. Although numerous ligands for G protein-coupled receptors (GPCRs) have been shown to stimulate the production of CXCL8, the specificity of the G protein signal remains undefined. By expressing the constitutively active Gα subunits in HEK293 cells, CXCL8 production was herein demonstrated to be most effectively stimulated by Gαq family members, while those of Gαs and Gα12 elicited much weaker activities, and Gαi being totally ineffective. However, in cell lines such as HepG2, HeLa, and MCF-7 that endogenously express Gβγ-responsive phospholipase Cβ isoforms (PLCβ2/3), activation of the Gi-coupled α2-adrenoceptor significantly stimulated CXCL8 production. This Gi-induced CXCL8 production was apparently mediated via specific Gβγ dimers and required the presence of PLCβ2/3. Co-activation of Gi-coupled α2-adrenoceptor and Gq-coupled bradykinin receptor resulted in a synergistic CXCL8 production, with Gβγ-responsive PLCβ2/3, Src, ERK, and STAT3 serving as critical signaling intermediates. The treatment of HepG2 and B-10 endothelial cells with bradykinin stimulated CXCL8 production and cell proliferation. Interestingly, the latter response was driven by CXCL8 autocrine signaling because it was abolished by SB225002, an antagonist that prevents CXCL8 from binding to CXCR2. Collectively, our results provide a mechanistic basis for various G protein subfamilies to regulate the production of CXCL8, which may then lead to paracrine and/or autocrine signaling with major implications in both normal physiology and pathophysiological conditions.
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Affiliation(s)
- Anthony S L Chan
- Division of Life Science and the Biotechnology Research Institute, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Winnie W I Lau
- Division of Life Science and the Biotechnology Research Institute, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Aydan C H Szeto
- Division of Life Science and the Biotechnology Research Institute, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Jiuling Wang
- Division of Life Science and the Biotechnology Research Institute, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Yung H Wong
- Division of Life Science and the Biotechnology Research Institute, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China; State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.
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25
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Abstract
Gαq signals with phospholipase C-β (PLC-β) to modify behavior in response to an agonist-bound GPCR. While the fundamental steps which prime Gαq to interact with PLC-β have been identified, questions remain concerning signal strength with PLC-β and other effectors. Gαq is generally viewed to function as a simple ON and OFF switch for its effector, dependent on the binding of GTP or GDP. However, Gαq does not have a single effector, Gαq has many different effectors. Furthermore, select effectors also regulate Gαq activity. PLC-β is a lipase and a GTPase activating protein (GAP) selective for Gαq. The contribution of G protein regulating activity to signal amplitude remains unclear. The unique PLC-β coiled-coil domain is essential for maximum Gαq response, both lipase and GAP. Nonetheless, coiled-coil domain associations necessary to maximum response have not been revealed by the structural approach. This review discusses progress towards understanding the basis for signal strength with PLC-β and other effectors. Shared and effector-specific interactions have been identified. Finally, the evidence for allosteric regulation of lipase stimulation by protein kinase C, the membrane, phosphatidic acid, phosphatidylinositol-4, 5-bisphosphate and GPCR is explored. Endogenous allosteric regulators can suppress or enhance maximum lipase stimulation dependent on the PLC-β coiled-coil domain. A better understanding of allosteric modulation may therefore identify a wealth of new targets to regulate signal strength and behavior.
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Affiliation(s)
- Irene Litosch
- Department of Molecular and Cellular Pharmacology, Miller School of Medicine University of Miami, Miami, FL 33101-6189, USA.
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26
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Thompson JL, Yang J, Lau B, Liu S, Baimel C, Kerr LE, Liu F, Borgland SL. Age-Dependent D1-D2 Receptor Coactivation in the Lateral Orbitofrontal Cortex Potentiates NMDA Receptors and Facilitates Cognitive Flexibility. Cereb Cortex 2015; 26:4524-4539. [PMID: 26405054 DOI: 10.1093/cercor/bhv222] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The orbitofrontal cortex (OFC) integrates information about the environment to guide decision-making. Glutamatergic synaptic transmission mediated through N-methyl-d-aspartate receptors is required for optimal functioning of the OFC. Additionally, abnormal dopamine signaling in this region has been implicated in impulsive behavior and poor cognitive flexibility. Yet, despite the high prevalence of psychostimulants prescribed for attention deficit/hyperactivity disorder, there is little information on how dopamine modulates synaptic transmission in the juvenile or the adult OFC. Using whole-cell patch-clamp recordings in OFC pyramidal neurons, we demonstrated that while dopamine or selective D2-like receptor (D2R) agonists suppress excitatory synaptic transmission of juvenile or adult lateral OFC neurons; in juvenile lateral OFC neurons, higher concentrations of dopamine can target dopamine receptors that couple to a phospholipase C (PLC) signaling pathway to enhance excitatory synaptic transmission. Interfering with the formation of a putative D1R-D2R interaction blocked the potentiation of excitatory synaptic transmission. Furthermore, targeting the putative D1R-D2R complex with a biased agonist, SKF83959, not only enhanced excitatory synaptic transmission in a PLC-dependent manner, but also improved the performance of juvenile rats on a reversal-learning task. Our results demonstrate that dopamine signaling in the lateral OFC differs between juveniles and adults, through potential crosstalk between dopamine receptor subtypes.
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Affiliation(s)
- Jennifer L Thompson
- Department of Anesthesiology, Pharmacology and Therapeutics, University of British Columbia, Vancouver, BC, Canada V6T 1Z3.,Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada T2N 4N1
| | - Jinhui Yang
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada T2N 4N1
| | - Benjamin Lau
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada T2N 4N1
| | - Shuai Liu
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada T2N 4N1
| | - Corey Baimel
- Department of Anesthesiology, Pharmacology and Therapeutics, University of British Columbia, Vancouver, BC, Canada V6T 1Z3.,Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada T2N 4N1
| | - Lauren E Kerr
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada T2N 4N1
| | - Fang Liu
- Department of Neuroscience, Centre for Addiction and Mental Health, Toronto, ON, Canada
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27
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Histamine H(1)- and H(4)-receptor signaling cooperatively regulate MAPK activation. Biochem Pharmacol 2015; 98:432-9. [PMID: 26385311 DOI: 10.1016/j.bcp.2015.09.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Accepted: 09/11/2015] [Indexed: 11/23/2022]
Abstract
The histamine (HA) receptor subtype 1 (H1R) and H4R are expressed on immune cells and contribute to an inflammatory reaction. Both receptor subtypes individually enhance the intracellular concentrations of calcium and regulate the accumulation of cAMP, increase MAPK activity, and regulate expression of e.g., inflammatory genes. In a previous study we characterized and compared signaling pathways of the murine orthologs of the H1R and the H4R recombinantly expressed at comparable levels in HEK 293 cells. In the present study, we aimed at analyzing possible interactions of the signaling pathways emerging at the mH1R and the mH4R. Therefore, we co-expressed both receptor subtypes at comparable levels in HEK 293 cells and investigated HA-induced signaling parameters such as the concentrations of intracellular calcium and cAMP, phosphorylation of the MAPKs p38, ERK 1, and ERK 2, and of the transcription factor CREB, and expression of the immediate early gene EGR-1. We demonstrate that the intracellular concentrations of calcium and cAMP as well as the EGR-1 expression are regulated exclusively via the mH1R. In contrast, both receptor subtypes H1R and H4R synergize in HA-induced MAPK activation. This synergism most probably relies on signaling pathways independent of the second messenger calcium and cAMP. In summary, we provide evidence that the mH1R inhibits or dampens the function of the co-expressed mH4R regarding specific parameters, while other signaling events are regulated cooperatively by the mH1R and the mH4R.
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28
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Litosch I. Regulating G protein activity by lipase-independent functions of phospholipase C. Life Sci 2015; 137:116-24. [DOI: 10.1016/j.lfs.2015.07.025] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Revised: 06/18/2015] [Accepted: 07/22/2015] [Indexed: 11/27/2022]
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Lyon AM, Begley JA, Manett TD, Tesmer JJG. Molecular mechanisms of phospholipase C β3 autoinhibition. Structure 2015; 22:1844-1854. [PMID: 25435326 DOI: 10.1016/j.str.2014.10.008] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2014] [Revised: 09/29/2014] [Accepted: 10/04/2014] [Indexed: 01/01/2023]
Abstract
Phospholipase C β (PLCβ) enzymes are dramatically activated by heterotrimeric G proteins. Central to this response is the robust autoinhibition of PLCβ by the X-Y linker region within its catalytic core and by the Hα2' helix in the C-terminal extension of the enzyme. The molecular mechanism of each and their mutual dependence are poorly understood. Herein, it is shown that distinct regions within the X-Y linker have specific roles in regulating activity. Most important,an acidic stretch within the linker stabilizes a lid that occludes the active site, consistent with crystal structures of variants lacking this region. Inhibition by the Hα2' helix is independent of the X-Y linker and likely regulates activity by limiting membrane interaction of the catalytic core. Full activation of PLCβ thus requires multiple independent molecular events induced by membrane association of the catalytic core and by the binding of regulatory proteins.
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Affiliation(s)
- Angeline M Lyon
- Life Sciences Institute, University of Michigan, 210 Washtenaw Avenue, Ann Arbor, MI 48109-2216, USA; Department of Pharmacology, University of Michigan, 1150 W. Medical Center Drive, 1301 MSRB III, Ann Arbor, MI 48109, USA; Department of Biological Chemistry, University of Michigan, 1150 W. Medical Center Drive, RM 5301 MSRB III, Ann Arbor, MI 48109-0600, USA
| | - Jessica A Begley
- Life Sciences Institute, University of Michigan, 210 Washtenaw Avenue, Ann Arbor, MI 48109-2216, USA; Department of Pharmacology, University of Michigan, 1150 W. Medical Center Drive, 1301 MSRB III, Ann Arbor, MI 48109, USA; Department of Biological Chemistry, University of Michigan, 1150 W. Medical Center Drive, RM 5301 MSRB III, Ann Arbor, MI 48109-0600, USA
| | - Taylor D Manett
- Life Sciences Institute, University of Michigan, 210 Washtenaw Avenue, Ann Arbor, MI 48109-2216, USA; Department of Pharmacology, University of Michigan, 1150 W. Medical Center Drive, 1301 MSRB III, Ann Arbor, MI 48109, USA; Department of Biological Chemistry, University of Michigan, 1150 W. Medical Center Drive, RM 5301 MSRB III, Ann Arbor, MI 48109-0600, USA
| | - John J G Tesmer
- Life Sciences Institute, University of Michigan, 210 Washtenaw Avenue, Ann Arbor, MI 48109-2216, USA; Department of Pharmacology, University of Michigan, 1150 W. Medical Center Drive, 1301 MSRB III, Ann Arbor, MI 48109, USA; Department of Biological Chemistry, University of Michigan, 1150 W. Medical Center Drive, RM 5301 MSRB III, Ann Arbor, MI 48109-0600, USA.
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O'Neill PR, Giri L, Karunarathne WKA, Patel AK, Venkatesh KV, Gautam N. The structure of dynamic GPCR signaling networks. WILEY INTERDISCIPLINARY REVIEWS-SYSTEMS BIOLOGY AND MEDICINE 2014; 6:115-23. [PMID: 24741711 DOI: 10.1002/wsbm.1249] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
G-protein-coupled receptors (GPCRs) stimulate signaling networks that control a variety of critical physiological processes. Static information on the map of interacting signaling molecules at the basis of many cellular processes exists, but little is known about the dynamic operation of these networks. Here we focus on two questions. First, Is the network architecture underlying GPCR-activated cellular processes unique in comparison with others such as transcriptional networks? We discuss how spatially localized GPCR signaling requires uniquely organized networks to execute polarized cell responses. Second, What approaches overcome challenges in deciphering spatiotemporally dynamic networks that govern cell behavior? We focus on recently developed microfluidic and optical approaches that allow GPCR signaling pathways to be triggered and perturbed with spatially and temporally variant input while simultaneously visualizing molecular and cellular responses. When integrated with mathematical modeling, these approaches can help identify design principles that govern cell responses to extracellular signals. We outline why optical approaches that allow the behavior of a selected cell to be orchestrated continually are particularly well suited for probing network organization in single cells.
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31
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Charpentier TH, Waldo GL, Barrett MO, Huang W, Zhang Q, Harden TK, Sondek J. Membrane-induced allosteric control of phospholipase C-β isozymes. J Biol Chem 2014; 289:29545-57. [PMID: 25193662 PMCID: PMC4207972 DOI: 10.1074/jbc.m114.586784] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Revised: 08/13/2014] [Indexed: 11/06/2022] Open
Abstract
All peripheral membrane proteins must negotiate unique constraints intrinsic to the biological interface of lipid bilayers and the cytosol. Phospholipase C-β (PLC-β) isozymes hydrolyze the membrane lipid phosphatidylinositol 4,5-bisphosphate (PIP2) to propagate diverse intracellular responses that underlie the physiological action of many hormones, neurotransmitters, and growth factors. PLC-β isozymes are autoinhibited, and several proteins, including Gαq, Gβγ, and Rac1, directly engage distinct regions of these phospholipases to release autoinhibition. To understand this process, we used a novel, soluble analog of PIP2 that increases in fluorescence upon cleavage to monitor phospholipase activity in real time in the absence of membranes or detergents. High concentrations of Gαq or Gβ1γ2 did not activate purified PLC-β3 under these conditions despite their robust capacity to activate PLC-β3 at membranes. In addition, mutants of PLC-β3 with crippled autoinhibition dramatically accelerated the hydrolysis of PIP2 in membranes without an equivalent acceleration in the hydrolysis of the soluble analog. Our results illustrate that membranes are integral for the activation of PLC-β isozymes by diverse modulators, and we propose a model describing membrane-mediated allosterism within PLC-β isozymes.
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Affiliation(s)
| | | | | | - Weigang Huang
- the Division of Chemical Biology and Medicinal Chemistry, University of North Carolina School of Pharmacy, Chapel Hill, North Carolina 27599
| | - Qisheng Zhang
- the Division of Chemical Biology and Medicinal Chemistry, University of North Carolina School of Pharmacy, Chapel Hill, North Carolina 27599
| | | | - John Sondek
- From the Departments of Pharmacology and Biochemistry and Biophysics and the Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599 and
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Chabot-Doré AJ, Schuster DJ, Stone LS, Wilcox GL. Analgesic synergy between opioid and α2 -adrenoceptors. Br J Pharmacol 2014; 172:388-402. [PMID: 24641506 DOI: 10.1111/bph.12695] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2013] [Revised: 03/08/2014] [Accepted: 03/12/2014] [Indexed: 12/24/2022] Open
Abstract
UNLABELLED Opioid and α2 -adrenoceptor agonists are potent analgesic drugs and their analgesic effects can synergize when co-administered. These supra-additive interactions are potentially beneficial clinically; by increasing efficacy and/or reducing the total drug required to produce sufficient pain relief, undesired side effects can be minimized. However, combination therapies of opioids and α2 -adrenoceptor agonists remain underutilized clinically, in spite of a large body of preclinical evidence describing their synergistic interaction. One possible obstacle to the translation of preclinical findings to clinical applications is a lack of understanding of the mechanisms underlying the synergistic interactions between these two drug classes. In this review, we provide a detailed overview of the interactions between different opioid and α2 -adrenoceptor agonist combinations in preclinical studies. These studies have identified the spinal cord as an important site of action of synergistic interactions, provided insights into which receptors mediate these interactions and explored downstream signalling events enabling synergy. It is now well documented that the activation of both μ and δ opioid receptors can produce synergy with α2 -adrenoceptor agonists and that α2 -adrenoceptor agonists can mediate synergy through either the α2A or the α2C adrenoceptor subtypes. Current hypotheses surrounding the cellular mechanisms mediating opioid-adrenoceptor synergy, including PKC signalling and receptor oligomerization, and the evidence supporting them are presented. Finally, the implications of these findings for clinical applications and drug discovery are discussed. LINKED ARTICLES This article is part of a themed section on Opioids: New Pathways to Functional Selectivity. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2015.172.issue-2.
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Affiliation(s)
- A-J Chabot-Doré
- Alan Edwards Centre for Research on Pain, McGill University, Montreal, QC, Canada; Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada
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Litosch I. Regulation of phospholipase C-β(1) GTPase-activating protein (GAP) function and relationship to G(q) efficacy. IUBMB Life 2014; 65:936-40. [PMID: 24170560 DOI: 10.1002/iub.1218] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Revised: 09/30/2013] [Accepted: 09/30/2013] [Indexed: 11/08/2022]
Abstract
How cells regulate Gq efficacy (initiation and termination of Gq signaling) to effect response remains a central question in pharmacology and drug discovery. Phospholipase C-β1 (PLC-β1) is an effector and a GTPase activating protein (GAP) specific to Gαq. The physiological function of PLC-β1 GAP remains unclear and controversial. GAPs are generally thought to function in deactivation of Gq signaling. However, PLC-β1 GAP has also been shown to increase signaling efficiency through kinetic coupling with the ligand-activated GPCR. GPCRs function as guanine nucleotide exchange factors (GEF) on the G protein activation cycle. This article sets forth a new hypothesis that could unify these conflicting paradigms as it pertains to physiological signaling and native levels of protein. It is proposed that the physiological function of PLC-β1 GAP is context-dependent and regulated by phosphatidic acid (PA). PA stimulates PLC-β1 GAP activity. In the absence of ligand, PLC-β1 GAP does indeed deactivate Gq signaling, limiting leaky activation to set the threshold for stimulation to sharpen signal kinetics. However in the presence of activating ligand, the increase in levels of PA would stimulate PLC-β1 GAP to kinetically couple with GPCR GEF to increase signaling efficiency. We found that PA-increased Gq efficiency is dependent on signaling via the unique PLC-β1 PA binding domain.
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Abstract
Phospholipase C (PLC) enzymes convert phosphatidylinositol-4,5-bisphosphate into the second messengers diacylglycerol and inositol-1,4,5-triphosphate. The production of these molecules promotes the release of intracellular calcium and activation of protein kinase C, which results in profound cellular changes. The PLCβ subfamily is of particular interest given its prominent role in cardiovascular and neuronal signaling and its regulation by G protein-coupled receptors, as PLCβ is the canonical downstream target of the heterotrimeric G protein Gαq. However, this is not the only mechanism regulating PLCβ activity. Extensive structural and biochemical evidence has revealed regulatory roles for autoinhibitory elements within PLCβ, Gβγ, small molecular weight G proteins, and the lipid membrane itself. Such complex regulation highlights the central role that this enzyme plays in cell signaling. A better understanding of the molecular mechanisms underlying the control of its activity will greatly facilitate the search for selective small molecule modulators of PLCβ.
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Affiliation(s)
- Angeline M Lyon
- Life Sciences Institute and the Departments of Pharmacology and Biological Chemistry, University of Michigan, Ann Arbor, Michigan
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Chun LS, Free RB, Doyle TB, Huang XP, Rankin ML, Sibley DR. D1-D2 dopamine receptor synergy promotes calcium signaling via multiple mechanisms. Mol Pharmacol 2013; 84:190-200. [PMID: 23680635 DOI: 10.1124/mol.113.085175] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
The D(1) dopamine receptor (D(1)R) has been proposed to form a hetero-oligomer with the D(2) dopamine receptor (D(2)R), which in turn results in a complex that couples to phospholipase C-mediated intracellular calcium release. We have sought to elucidate the pharmacology and mechanism of action of this putative signaling pathway. Dopamine dose-response curves assaying intracellular calcium mobilization in cells heterologously expressing the D(1) and D(2) subtypes, either alone or in combination, and using subtype selective ligands revealed that concurrent stimulation is required for coupling. Surprisingly, characterization of a putative D(1)-D(2) heteromer-selective ligand, 6-chloro-2,3,4,5-tetrahydro-3-methyl-1-(3-methylphenyl)-1H-3-benzazepine-7,8-diol (SKF83959), found no stimulation of calcium release, but it did find a broad range of cross-reactivity with other G protein-coupled receptors. In contrast, SKF83959 appeared to be an antagonist of calcium mobilization. Overexpression of G(qα) with the D(1) and D(2) dopamine receptors enhanced the dopamine-stimulated calcium response. However, this was also observed in cells expressing G(qα) with only the D1R. Inactivation of Gi or Gs with pertussis or cholera toxin, respectively, largely, but not entirely, reduced the calcium response in D(1)R and D(2)R cotransfected cells. Moreover, sequestration of G(βγ) subunits through overexpression of G protein receptor kinase 2 mutants either completely or largely eliminated dopamine-stimulated calcium mobilization. Our data suggest that the mechanism of D(1)R/D(2)R-mediated calcium signaling involves more than receptor-mediated G(q) protein activation, may largely involve downstream signaling pathways, and may not be completely heteromer-specific. In addition, SKF83959 may not exhibit selective activation of D(1)-D(2) heteromers, and its significant cross-reactivity to other receptors warrants careful interpretation of its use in vivo.
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Affiliation(s)
- Lani S Chun
- Molecular Neuropharmacology Section, National Institute of Neurologic Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892-9405, USA
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Full-length Gα(q)-phospholipase C-β3 structure reveals interfaces of the C-terminal coiled-coil domain. Nat Struct Mol Biol 2013; 20:355-62. [PMID: 23377541 PMCID: PMC3594540 DOI: 10.1038/nsmb.2497] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2012] [Accepted: 12/18/2012] [Indexed: 01/18/2023]
Abstract
Phospholipase C-β (PLCβ) is directly activated by Gαq, but the molecular basis for how its distal C-terminal domain (CTD) contributes to maximal activity is poorly understood. Herein we present both the crystal structure and cryo-EM 3D reconstructions of human full-length PLCβ3 in complex with murine Gαq. The distal CTD forms an extended, monomeric helical bundle consisting of three anti-parallel segments with structural similarity to membrane-binding bin–amphiphysin–Rvs (BAR) domains. Sequence conservation of the distal CTD identifies putative membrane and protein interaction sites, the latter of which bind the N-terminal helix of Gαq in both the crystal structure and cryo-EM reconstructions. Functional analysis suggests the distal CTD plays roles in membrane targeting and in optimizing the orientation of the catalytic core at the membrane for maximal rates of lipid hydrolysis.
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Abstract
Phospholipase C (PLC) converts phosphatidylinositol 4,5-bisphosphate (PIP(2)) to inositol 1,4,5-trisphosphate (IP(3)) and diacylglycerol (DAG). DAG and IP(3) each control diverse cellular processes and are also substrates for synthesis of other important signaling molecules. PLC is thus central to many important interlocking regulatory networks. Mammals express six families of PLCs, each with both unique and overlapping controls over expression and subcellular distribution. Each PLC also responds acutely to its own spectrum of activators that includes heterotrimeric G protein subunits, protein tyrosine kinases, small G proteins, Ca(2+), and phospholipids. Mammalian PLCs are autoinhibited by a region in the catalytic TIM barrel domain that is the target of much of their acute regulation. In combination, the PLCs act as a signaling nexus that integrates numerous signaling inputs, critically governs PIP(2) levels, and regulates production of important second messengers to determine cell behavior over the millisecond to hour timescale.
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Affiliation(s)
- Ganesh Kadamur
- Department of Pharmacology, Molecular Biophysics Graduate Program and Green Center for Systems Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
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Bal MS, Castro V, Piontek J, Rueckert C, Walter JK, Shymanets A, Kurig B, Haase H, Nürnberg B, Blasig IE. The hinge region of the scaffolding protein of cell contacts, zonula occludens protein 1, regulates interacting with various signaling proteins. J Cell Biochem 2012; 113:934-45. [PMID: 22371973 DOI: 10.1002/jcb.23422] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Zonula occludens protein 1 (ZO-1) is a ubiquitous scaffolding protein, but it is unknown why it functions in very different cellular contacts. We hypothesized that a specific segment, the unique hinge region, can be bound by very different regulatory proteins. Using surface plasmon resonance spectroscopy and binding assays to peptide libraries, we show, for the first time, that the hinge region directly interacts with disparate signal elements such as G-proteins alpha 12 and alpha i2, the regulator of G-protein signaling 5, multifunctional signaling protein ahnak1, and L-type Ca2+-channel beta-2-subunit. The novel binding proteins specifically bound to a coiled coil-helix predicted in the hinge region of ZO-. The interactions were modulated by phosphorylation in the hinge helix. Activation of the G-proteins influenced their association to ZO-1. In colon cells, G alpha i2 and ZO-1 were associated, as shown by coimmunoprecipitation. After cotransfection in kidney cells, G alpha i2 barely colocalized with ZO-1; the colocalization coefficient was significantly increased when epinephrine activated G-protein signaling. In conclusion, proteins with different regulatory potential adhere to and influence cellular functions of ZO-proteins, and the interactions can be modulated via its hinge region and/or the binding proteins.
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Affiliation(s)
- Manjot Singh Bal
- Leibniz-Institut für Molekulare Pharmakologie, Berlin-Buch, Germany
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Reactive oxygen species are second messengers of neurokinin signaling in peripheral sensory neurons. Proc Natl Acad Sci U S A 2012; 109:E1578-86. [PMID: 22586118 DOI: 10.1073/pnas.1201544109] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Substance P (SP) is a prominent neuromodulator, which is produced and released by peripheral damage-sensing (nociceptive) neurons; these neurons also express SP receptors. However, the mechanisms of peripheral SP signaling are poorly understood. We report a signaling pathway of SP in nociceptive neurons: Acting predominantly through NK1 receptors and G(i/o) proteins, SP stimulates increased release of reactive oxygen species from the mitochondrial electron transport chain. Reactive oxygen species, functioning as second messengers, induce oxidative modification and augment M-type potassium channels, thereby suppressing excitability. This signaling cascade requires activation of phospholipase C but is largely uncoupled from the inositol 1,4,5-trisphosphate sensitive Ca(2+) stores. In rats SP causes sensitization of TRPV1 and produces thermal hyperalgesia. However, the lack of coupling between SP signaling and inositol 1,4,5-trisphosphate sensitive Ca(2+) stores, together with the augmenting effect on M channels, renders the SP pathway ineffective to excite nociceptors acutely and produce spontaneous pain. Our study describes a mechanism for neurokinin signaling in sensory neurons and provides evidence that spontaneous pain and hyperalgesia can have distinct underlying mechanisms within a single nociceptive neuron.
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Staljanssens D, Van Camp J, Billiet A, De Meyer T, Al Shukor N, De Vos WH, Smagghe G. Screening of soy and milk protein hydrolysates for their ability to activate the CCK1 receptor. Peptides 2012; 34:226-31. [PMID: 22138720 DOI: 10.1016/j.peptides.2011.11.019] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2011] [Revised: 11/18/2011] [Accepted: 11/18/2011] [Indexed: 11/22/2022]
Abstract
The cholecystokinin receptor-type 1 (CCK1R) is a G-protein coupled receptor localized in the animal gastrointestinal tract. Receptor activation by the natural peptide ligand CCK leads to a feeling of satiety. In this study, hydrolysates from soy and milk proteins were evaluated for their potential to activate the CCK1R, assuming that bioactive peptides with a satiogenic effect can be used as an effective therapeutic strategy for obesity. Different protein hydrolysates were screened with a cell-based bioassay, which relies on the generation of a fluorescent signal upon receptor activation. Fluorescence was monitored using a fluorescence plate reader and confocal microscopy. Results from the fluorescence plate reader were biased by background autofluorescence of the protein hydrolysate matrices, which makes the fluorescence plate reader inappropriate for the evaluation of complex formulations. Measurements with the confocal microscope resulted in reliable and specific results. The latter approach showed that the gastrointestinal digested 7S fraction of soy protein demonstrates CCK1R activity.
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Abstract
The physiological effects of many extracellular neurotransmitters, hormones, growth factors, and other stimuli are mediated by receptor-promoted activation of phospholipase C (PLC) and consequential activation of inositol lipid signaling pathways. These signaling responses include the classically described conversion of phosphatidylinositol(4,5)P(2) to the Ca(2+)-mobilizing second messenger inositol(1,4,5)P(3) and the protein kinase C-activating second messenger diacylglycerol as well as alterations in membrane association or activity of many proteins that harbor phosphoinositide binding domains. The 13 mammalian PLCs elaborate a minimal catalytic core typified by PLC-d to confer multiple modes of regulation of lipase activity. PLC-b isozymes are activated by Gaq- and Gbg-subunits of heterotrimeric G proteins, and activation of PLC-g isozymes occurs through phosphorylation promoted by receptor and non-receptor tyrosine kinases. PLC-e and certain members of the PLC-b and PLC-g subclasses of isozymes are activated by direct binding of small G proteins of the Ras, Rho, and Rac subfamilies of GTPases. Recent high resolution three dimensional structures together with biochemical studies have illustrated that the X/Y linker region of the catalytic core mediates autoinhibition of most if not all PLC isozymes. Activation occurs as a consequence of removal of this autoinhibition.
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Litosch I. RhoA co-ordinates with heterotrimeric G proteins to regulate efficacy. Biochem Biophys Res Commun 2011; 415:215-9. [PMID: 22033406 DOI: 10.1016/j.bbrc.2011.10.063] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2011] [Accepted: 10/11/2011] [Indexed: 01/25/2023]
Abstract
Heterotrimeric G proteins have a critical role in mediating signal transduction by ligand-stimulated GPCRs. While activation of heterotrimeric G proteins is known to proceed via the G protein guanine nucleotide cycle, there is much uncertainty regarding the process that determines efficacy, the extent of response across signaling pathways. Gα(GTP) can interact with multiple binding partners, including several effectors and regulators. Cross-talk by other receptor-signaling pathways can alter the response. It remains unclear whether G protein efficacy is regulated. This lack of clarity impairs our ability to predict and manipulate the pharmacological behavior of activated G proteins. This review will discuss emerging evidence that implicates monomeric RhoA in the process that regulates G(q) efficacy.
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Affiliation(s)
- Irene Litosch
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33101-6189, USA.
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Harden TK, Waldo GL, Hicks SN, Sondek J. Mechanism of activation and inactivation of Gq/phospholipase C-β signaling nodes. Chem Rev 2011; 111:6120-9. [PMID: 21988240 PMCID: PMC3626114 DOI: 10.1021/cr200209p] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- T Kendall Harden
- Department of Pharmacology and the Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599, USA.
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Kremer KN, Clift IC, Miamen AG, Bamidele AO, Qian NX, Humphreys TD, Hedin KE. Stromal cell-derived factor-1 signaling via the CXCR4-TCR heterodimer requires phospholipase C-β3 and phospholipase C-γ1 for distinct cellular responses. THE JOURNAL OF IMMUNOLOGY 2011; 187:1440-7. [PMID: 21705626 DOI: 10.4049/jimmunol.1100820] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The CXCR4 chemokine receptor is a G protein-coupled receptor that signals in T lymphocytes by forming a heterodimer with the TCR. CXCR4 and TCR functions are consequently highly cross regulated, affecting T cell immune activation, cytokine secretion, and T cell migration. The CXCR4-TCR heterodimer stimulates T cell migration and activation of the ERK MAPK and downstream AP-1-dependent cytokine transcription in response to stromal cell-derived factor-1 (SDF-1), the sole chemokine ligand of CXCR4. These responses require Gi-type G proteins as well as TCR ITAM domains and the ZAP70 tyrosine kinase, thus indicating that the CXCR4-TCR heterodimer signals to integrate G protein-coupled receptor-associated and TCR-associated signaling molecules in response to SDF-1. Yet, the phospholipase C (PLC) isozymes responsible for coupling the CXCR4-TCR heterodimer to distinct downstream cellular responses are incompletely characterized. In this study, we demonstrate that PLC activity is required for SDF-1 to induce ERK activation, migration, and CXCR4 endocytosis in human T cells. SDF-1 signaling via the CXCR4-TCR heterodimer uses PLC-β3 to activate the Ras-ERK pathway and increase intracellular calcium ion concentrations, whereas PLC-γ1 is dispensable for these outcomes. In contrast, PLC-γ1, but not PLC-β3, is required for SDF-1-mediated migration via a mechanism independent of LAT. These results increase understanding of the signaling mechanisms employed by the CXCR4-TCR heterodimer, characterize new roles for PLC-β3 and PLC-γ1 in T cells, and suggest that multiple PLCs may also be activated downstream of other chemokine receptors to distinctly regulate migration versus other signaling functions.
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Affiliation(s)
- Kimberly N Kremer
- Department of Immunology, Mayo Clinic College of Medicine, Mayo Clinic, Rochester, MN 55905, USA
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Integrative genomics identifies MCU as an essential component of the mitochondrial calcium uniporter. Nature 2011; 476:341-5. [PMID: 21685886 DOI: 10.1038/nature10234] [Citation(s) in RCA: 1432] [Impact Index Per Article: 110.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2010] [Accepted: 06/02/2011] [Indexed: 12/19/2022]
Abstract
Mitochondria from diverse organisms are capable of transporting large amounts of Ca(2+) via a ruthenium-red-sensitive, membrane-potential-dependent mechanism called the uniporter. Although the uniporter's biophysical properties have been studied extensively, its molecular composition remains elusive. We recently used comparative proteomics to identify MICU1 (also known as CBARA1), an EF-hand-containing protein that serves as a putative regulator of the uniporter. Here, we use whole-genome phylogenetic profiling, genome-wide RNA co-expression analysis and organelle-wide protein coexpression analysis to predict proteins functionally related to MICU1. All three methods converge on a novel predicted transmembrane protein, CCDC109A, that we now call 'mitochondrial calcium uniporter' (MCU). MCU forms oligomers in the mitochondrial inner membrane, physically interacts with MICU1, and resides within a large molecular weight complex. Silencing MCU in cultured cells or in vivo in mouse liver severely abrogates mitochondrial Ca(2+) uptake, whereas mitochondrial respiration and membrane potential remain fully intact. MCU has two predicted transmembrane helices, which are separated by a highly conserved linker facing the intermembrane space. Acidic residues in this linker are required for its full activity. However, an S259A point mutation retains function but confers resistance to Ru360, the most potent inhibitor of the uniporter. Our genomic, physiological, biochemical and pharmacological data firmly establish MCU as an essential component of the mitochondrial Ca(2+) uniporter.
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