1
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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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2
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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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3
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Le Huray KIP, Bunney TD, Pinotsis N, Kalli AC, Katan M. Characterization of the membrane interactions of phospholipase Cγ reveals key features of the active enzyme. SCIENCE ADVANCES 2022; 8:eabp9688. [PMID: 35749497 PMCID: PMC9232102 DOI: 10.1126/sciadv.abp9688] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Accepted: 05/06/2022] [Indexed: 06/15/2023]
Abstract
PLCγ enzymes are autoinhibited in resting cells and form key components of intracellular signaling that are also linked to disease development. Insights into physiological and aberrant activation of PLCγ require understanding of an active, membrane-bound form, which can hydrolyze inositol-lipid substrates. Here, we demonstrate that PLCγ1 cannot bind membranes unless the autoinhibition is disrupted. Through extensive molecular dynamics simulations and experimental evidence, we characterize membrane binding by the catalytic core domains and reveal previously unknown sites of lipid interaction. The identified sites act in synergy, overlap with autoinhibitory interfaces, and are shown to be critical for the phospholipase activity in cells. This work provides direct evidence that PLCγ1 is inhibited through obstruction of its membrane-binding surfaces by the regulatory region and that activation must shift PLCγ1 to a conformation competent for membrane binding. Knowledge of the critical sites of membrane interaction extends the mechanistic framework for activation, dysregulation, and therapeutic intervention.
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Affiliation(s)
- Kyle I. P. Le Huray
- Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT UK
- Leeds Institute of Cardiovascular and Metabolic Medicine, School of Medicine, University of Leeds, Leeds LS2 9JT, UK
| | - Tom D. Bunney
- Institute of Structural and Molecular Biology, Division of Biosciences, University College London, Gower St., London WC1E 6BT, UK
| | - Nikos Pinotsis
- Institute of Structural and Molecular Biology, Birkbeck College, London, WC1E 6BT, UK
| | - Antreas C. Kalli
- Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
- Leeds Institute of Cardiovascular and Metabolic Medicine, School of Medicine, University of Leeds, Leeds LS2 9JT, UK
| | - Matilda Katan
- Institute of Structural and Molecular Biology, Division of Biosciences, University College London, Gower St., London WC1E 6BT, UK
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4
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Cooke M, Kazanietz MG. Overarching roles of diacylglycerol signaling in cancer development and antitumor immunity. Sci Signal 2022; 15:eabo0264. [PMID: 35412850 DOI: 10.1126/scisignal.abo0264] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Diacylglycerol (DAG) is a lipid second messenger that is generated in response to extracellular stimuli and channels intracellular signals that affect mammalian cell proliferation, survival, and motility. DAG exerts a myriad of biological functions through protein kinase C (PKC) and other effectors, such as protein kinase D (PKD) isozymes and small GTPase-regulating proteins (such as RasGRPs). Imbalances in the fine-tuned homeostasis between DAG generation by phospholipase C (PLC) enzymes and termination by DAG kinases (DGKs), as well as dysregulation in the activity or abundance of DAG effectors, have been widely associated with tumor initiation, progression, and metastasis. DAG is also a key orchestrator of T cell function and thus plays a major role in tumor immunosurveillance. In addition, DAG pathways shape the tumor ecosystem by arbitrating the complex, dynamic interaction between cancer cells and the immune landscape, hence representing powerful modifiers of immune checkpoint and adoptive T cell-directed immunotherapy. Exploiting the wide spectrum of DAG signals from an integrated perspective could underscore meaningful advances in targeted cancer therapy.
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Affiliation(s)
- Mariana Cooke
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.,Department of Medicine, Einstein Medical Center Philadelphia, Philadelphia, PA 19141, USA
| | - Marcelo G Kazanietz
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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5
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Phan HTN, Kim NH, Wei W, Tall GG, Smrcka AV. Uveal melanoma-associated mutations in PLCβ4 are constitutively activating and promote melanocyte proliferation and tumorigenesis. Sci Signal 2021; 14:eabj4243. [PMID: 34905385 DOI: 10.1126/scisignal.abj4243] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
[Figure: see text].
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Affiliation(s)
- Hoa T N Phan
- Department of Pharmacology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Nam Hoon Kim
- Department of Pharmacology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Wenhui Wei
- Department of Pharmacology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Gregory G Tall
- Department of Pharmacology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Alan V Smrcka
- Department of Pharmacology, University of Michigan, Ann Arbor, MI 48109, USA
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6
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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: 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: 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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7
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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: 14] [Impact Index Per Article: 4.7] [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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8
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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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9
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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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10
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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: 40] [Impact Index Per Article: 10.0] [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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11
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Activation of Phospholipase C β by Gβγ and Gα q Involves C-Terminal Rearrangement to Release Autoinhibition. Structure 2020; 28:810-819.e5. [PMID: 32402248 DOI: 10.1016/j.str.2020.04.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Revised: 01/13/2020] [Accepted: 04/15/2020] [Indexed: 01/15/2023]
Abstract
Phospholipase C (PLC) enzymes hydrolyze phosphoinositide lipids to inositol phosphates and diacylglycerol. Direct activation of PLCβ by Gαq and/or Gβγ subunits mediates signaling by Gq and some Gi coupled G-protein-coupled receptors (GPCRs), respectively. PLCβ isoforms contain a unique C-terminal extension, consisting of proximal and distal C-terminal domains (CTDs) separated by a flexible linker. The structure of PLCβ3 bound to Gαq is known, however, for both Gαq and Gβγ; the mechanism for PLCβ activation on membranes is unknown. We examined PLCβ2 dynamics on membranes using hydrogen-deuterium exchange mass spectrometry (HDX-MS). Gβγ caused a robust increase in dynamics of the distal C-terminal domain (CTD). Gαq showed decreased deuterium incorporation at the Gαq binding site on PLCβ. In vitro Gβγ-dependent activation of PLC is inhibited by the distal CTD. The results suggest that disruption of autoinhibitory interactions with the CTD leads to increased PLCβ hydrolase activity.
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12
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Hajicek N, Keith NC, Siraliev-Perez E, Temple BRS, Huang W, Zhang Q, Harden TK, Sondek J. Structural basis for the activation of PLC-γ isozymes by phosphorylation and cancer-associated mutations. eLife 2019; 8:e51700. [PMID: 31889510 PMCID: PMC7004563 DOI: 10.7554/elife.51700] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Accepted: 12/30/2019] [Indexed: 12/14/2022] Open
Abstract
Direct activation of the human phospholipase C-γ isozymes (PLC-γ1, -γ2) by tyrosine phosphorylation is fundamental to the control of diverse biological processes, including chemotaxis, platelet aggregation, and adaptive immunity. In turn, aberrant activation of PLC-γ1 and PLC-γ2 is implicated in inflammation, autoimmunity, and cancer. Although structures of isolated domains from PLC-γ isozymes are available, these structures are insufficient to define how release of basal autoinhibition is coupled to phosphorylation-dependent enzyme activation. Here, we describe the first high-resolution structure of a full-length PLC-γ isozyme and use it to underpin a detailed model of their membrane-dependent regulation. Notably, an interlinked set of regulatory domains integrates basal autoinhibition, tyrosine kinase engagement, and additional scaffolding functions with the phosphorylation-dependent, allosteric control of phospholipase activation. The model also explains why mutant forms of the PLC-γ isozymes found in several cancers have a wide spectrum of activities, and highlights how these activities are tuned during disease.
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Affiliation(s)
- Nicole Hajicek
- Department of PharmacologyThe University of North Carolina at Chapel HillChapel HillUnited States
| | - Nicholas C Keith
- Department of PharmacologyThe University of North Carolina at Chapel HillChapel HillUnited States
| | - Edhriz Siraliev-Perez
- Department of Biochemistry and BiophysicsThe University of North Carolina at Chapel HillChapel HillUnited States
| | - Brenda RS Temple
- Department of Biochemistry and BiophysicsThe University of North Carolina at Chapel HillChapel HillUnited States
- R L Juliano Structural Bioinformatics Core FacilityThe University of North Carolina at Chapel HillChapel HillUnited States
| | - Weigang Huang
- Division of Chemical Biology and Medicinal ChemistryThe University of North Carolina at Chapel HillChapel HillUnited States
| | - Qisheng Zhang
- Department of PharmacologyThe University of North Carolina at Chapel HillChapel HillUnited States
- Division of Chemical Biology and Medicinal ChemistryThe University of North Carolina at Chapel HillChapel HillUnited States
- Lineberger Comprehensive Cancer CenterThe University of North Carolina at Chapel HillChapel HillUnited States
| | - T Kendall Harden
- Department of PharmacologyThe University of North Carolina at Chapel HillChapel HillUnited States
| | - John Sondek
- Department of PharmacologyThe University of North Carolina at Chapel HillChapel HillUnited States
- Department of Biochemistry and BiophysicsThe University of North Carolina at Chapel HillChapel HillUnited States
- Lineberger Comprehensive Cancer CenterThe University of North Carolina at Chapel HillChapel HillUnited States
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13
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Bae J, Kumazoe M, Takeuchi C, Hidaka S, Fujimura Y, Tachibana H. Epigallocatechin-3-O-gallate induces acid sphingomyelinase activation through activation of phospholipase C. Biochem Biophys Res Commun 2019; 520:186-191. [PMID: 31585731 DOI: 10.1016/j.bbrc.2019.09.102] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Accepted: 09/24/2019] [Indexed: 02/06/2023]
Abstract
Epigallocatechin-3-O-gallate (EGCG)-induced cyclic guanosine monophosphate (cGMP) plays a crucial role in EGCG-induced cell death in various types of cancer cells. However, little is known regarding the early molecular events after cGMP induction. In this study, we showed that cGMP induction is sufficient to induce the phosphorylation of protein kinase C delta (PKCδ) at Ser664, the crucial kinase for EGCG-induced activation of acid sphingomyelinase (ASM). Using a chemical inhibitor library, we revealed that the inhibitors of the negative regulators of diacylglycerol strongly increase the effect of EGCG. We also showed that EGCG treatment increased phospholipase C (PLC) activity, and the same results were obtained with cGMP inducer treatment. EGCG-induced ASM activation was completely suppressed by pharmacological inhibition of PLC. Collectively, EGCG-induced cGMP activated the cGMP/PLC/PKCδ/ASM signaling axis in multiple myeloma cells.
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Affiliation(s)
- Jaehoon Bae
- Division of Applied Biological Chemistry, Department of Bioscience and Biotechnology, Faculty of Agriculture, Kyushu University, Fukuoka, 819-0395, Japan
| | - Motofumi Kumazoe
- Division of Applied Biological Chemistry, Department of Bioscience and Biotechnology, Faculty of Agriculture, Kyushu University, Fukuoka, 819-0395, Japan
| | - Chieri Takeuchi
- Division of Applied Biological Chemistry, Department of Bioscience and Biotechnology, Faculty of Agriculture, Kyushu University, Fukuoka, 819-0395, Japan
| | - Shiori Hidaka
- Division of Applied Biological Chemistry, Department of Bioscience and Biotechnology, Faculty of Agriculture, Kyushu University, Fukuoka, 819-0395, Japan
| | - Yoshinori Fujimura
- Division of Applied Biological Chemistry, Department of Bioscience and Biotechnology, Faculty of Agriculture, Kyushu University, Fukuoka, 819-0395, Japan
| | - Hirofumi Tachibana
- Division of Applied Biological Chemistry, Department of Bioscience and Biotechnology, Faculty of Agriculture, Kyushu University, Fukuoka, 819-0395, Japan.
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14
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Intramolecular electrostatic interactions contribute to phospholipase Cβ3 autoinhibition. Cell Signal 2019; 62:109349. [PMID: 31254604 DOI: 10.1016/j.cellsig.2019.109349] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Revised: 06/22/2019] [Accepted: 06/23/2019] [Indexed: 01/21/2023]
Abstract
Phospholipase Cβ (PLCβ) enzymes regulate second messenger production following the activation of G protein-coupled receptors (GPCRs). Under basal conditions, these enzymes are maintained in an autoinhibited state by multiple elements, including an insertion within the catalytic domain known as the X-Y linker. Although the PLCβ X-Y linker is variable in sequence and length, its C-terminus is conserved and features an acidic stretch, followed by a short helix. This helix interacts with residues near the active site, acting as a lid to sterically prevent substrate binding. However, deletions that remove the acidic stretch of the X-Y linker increase basal activity to the same extent as deletion of the entire X-Y linker. Thus, the acidic stretch may be the linchpin in autoinhibition mediated by the X-Y linker. We used site-directed mutagenesis and biochemical assays to investigate the importance of this acidic charge in mediating PLCβ3 autoinhibition. Loss of the acidic charge in the X-Y linker increases basal activity and decreases stability, consistent with loss of autoinhibition. However, introduction of compensatory electrostatic mutations on the surface of the PLCβ3 catalytic domain restore activity to basal levels. Thus, intramolecular electrostatics modulate autoinhibition by the X-Y linker.
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15
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Lu SM, Fairn GD. 7-Ketocholesterol impairs phagocytosis and efferocytosis via dysregulation of phosphatidylinositol 4,5-bisphosphate. Traffic 2018; 19:591-604. [PMID: 29693767 DOI: 10.1111/tra.12576] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 04/16/2018] [Accepted: 04/18/2018] [Indexed: 12/27/2022]
Abstract
The plasma membrane is inhomogeneously organized containing both highly ordered and disordered nanodomains. 7-Ketocholesterol (7KC), an oxysterol formed from the nonenzymatic oxidation of cholesterol, is a potent disruptor of membrane order. Importantly, 7KC is a component of oxidized low-density lipoprotein and accumulates in macrophage and foam cells found in arterial plaques. Using a murine macrophage cell line, J774, we report that both IgG-mediated and phosphatidylserine-mediated phagocytic pathways are inhibited by the accumulation of 7KC. Examination of the well-studied Fcγ receptor pathway revealed that the cell surface receptor abundance and ligand binding are unaltered while downstream signaling and activation of spleen tyrosine kinase is not affected. However, while the recruitment of phospholipase Cγ1 was unaffected its apparent enzymatic activity was compromised resulting in sustained phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2 ] levels and polymerized actin at the base of the phagocytic cup. Additionally, we found that 7KC prevented the activation of PLCβ downstream of the P2Y6 G-protein coupled receptor and that 7KC impaired PLCγ activity in response to a direct elevation of cytosolic calcium induced by ionomycin. Finally, we demonstrate that 7KC partly attenuates the activity of rapamycin recruitable constitutively active PLCβ3. Together, our results demonstrate that the accumulation of 7KC impairs macrophage function by altering PtdIns(4,5)P2 catabolism and, thus, impairing actin depolymerization required for the completion of phagocytosis.
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Affiliation(s)
- Stella M Lu
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada.,Keenan Research Centre for Biomedical Sciences, St. Michael's Hospital, Toronto, ON, Canada
| | - Gregory D Fairn
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada.,Keenan Research Centre for Biomedical Sciences, St. Michael's Hospital, Toronto, ON, Canada.,Department of Surgery and Institute of Medical Science, University of Toronto, Toronto, ON, Canada
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16
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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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17
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Hudson BN, Hyun SH, Thompson DH, Lyon AM. Phospholipase Cβ3 Membrane Adsorption and Activation Are Regulated by Its C-Terminal Domains and Phosphatidylinositol 4,5-Bisphosphate. Biochemistry 2017; 56:5604-5614. [PMID: 28945350 DOI: 10.1021/acs.biochem.7b00547] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Phospholipase Cβ (PLCβ) enzymes hydrolyze phosphatidylinositol 4,5-bisphosphate to produce second messengers that regulate intracellular Ca2+, cell proliferation, and survival. Their activity is dependent upon interfacial activation that occurs upon localization to cell membranes. However, the molecular basis for how these enzymes productively interact with the membrane is poorly understood. Herein, atomic force microscopy demonstrates that the ∼300-residue C-terminal domain promotes adsorption to monolayers and is required for spatial organization of the protein on the monolayer surface. PLCβ variants lacking this C-terminal domain display differences in their distribution on the surface. In addition, a previously identified autoinhibitory helix that binds to the PLCβ catalytic core negatively impacts membrane binding, providing an additional level of regulation for membrane adsorption. Lastly, defects in phosphatidylinositol 4,5-bisphosphate hydrolysis also alter monolayer adsorption, reflecting a role for the active site in this process. Together, these findings support a model in which multiple elements of PLCβ modulate adsorption, distribution, and catalysis at the cell membrane.
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Affiliation(s)
- Brianna N Hudson
- Department of Chemistry and ‡Department of Biological Sciences, Purdue University , West Lafayette, Indiana 47907, United States
| | - Seok-Hee Hyun
- Department of Chemistry and ‡Department of Biological Sciences, Purdue University , West Lafayette, Indiana 47907, United States
| | - David H Thompson
- Department of Chemistry and ‡Department of Biological Sciences, Purdue University , West Lafayette, Indiana 47907, United States
| | - Angeline M Lyon
- Department of Chemistry and ‡Department of Biological Sciences, Purdue University , West Lafayette, Indiana 47907, United States
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18
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Navaratnarajah P, Gershenson A, Ross EM. The binding of activated Gα q to phospholipase C-β exhibits anomalous affinity. J Biol Chem 2017; 292:16787-16801. [PMID: 28842497 DOI: 10.1074/jbc.m117.809673] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Revised: 08/22/2017] [Indexed: 01/01/2023] Open
Abstract
Upon activation by the Gq family of Gα subunits, Gβγ subunits, and some Rho family GTPases, phospholipase C-β (PLC-β) isoforms hydrolyze phosphatidylinositol 4,5-bisphosphate to the second messengers inositol 1,4,5-trisphosphate and diacylglycerol. PLC-β isoforms also function as GTPase-activating proteins, potentiating Gq deactivation. To elucidate the mechanism of this mutual regulation, we measured the thermodynamics and kinetics of PLC-β3 binding to Gαq FRET and fluorescence correlation spectroscopy, two physically distinct methods, both yielded Kd values of about 200 nm for PLC-β3-Gαq binding. This Kd is 50-100 times greater than the EC50 for Gαq-mediated PLC-β3 activation and for the Gαq GTPase-activating protein activity of PLC-β. The measured Kd was not altered either by the presence of phospholipid vesicles, phosphatidylinositol 4,5-bisphosphate and Ca2+, or by the identity of the fluorescent labels. FRET-based kinetic measurements were also consistent with a Kd of 200 nm We determined that PLC-β3 hysteresis, whereby PLC-β3 remains active for some time following either Gαq-PLC-β3 dissociation or PLC-β3-potentiated Gαq deactivation, is not sufficient to explain the observed discrepancy between EC50 and Kd These results indicate that the mechanism by which Gαq and PLC-β3 mutually regulate each other is far more complex than a simple, two-state allosteric model and instead is probably kinetically determined.
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Affiliation(s)
- Punya Navaratnarajah
- From the Department of Pharmacology and Green Center for Systems Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9041 and
| | - Anne Gershenson
- the Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, Massachusetts 01003-9292
| | - Elliott M Ross
- From the Department of Pharmacology and Green Center for Systems Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9041 and
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19
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Levin R, Hammond GRV, Balla T, De Camilli P, Fairn GD, Grinstein S. Multiphasic dynamics of phosphatidylinositol 4-phosphate during phagocytosis. Mol Biol Cell 2016; 28:128-140. [PMID: 28035045 PMCID: PMC5221617 DOI: 10.1091/mbc.e16-06-0451] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Revised: 10/21/2016] [Accepted: 11/01/2016] [Indexed: 01/22/2023] Open
Abstract
Phosphatidylinositol 4-phosphate undergoes striking multiphasic changes during phagosome formation and maturation. The molecular mechanisms underlying these changes and the role of phosphatidylinositol 4-phosphate in phagolysosome formation are investigated. We analyzed the distribution, fate, and functional role of phosphatidylinositol 4-phosphate (PtdIns4P) during phagosome formation and maturation. To this end, we used genetically encoded probes consisting of the PtdIns4P-binding domain of the bacterial effector SidM. PtdIns4P was found to undergo complex, multiphasic changes during phagocytosis. The phosphoinositide, which is present in the plasmalemma before engagement of the target particle, is transiently enriched in the phagosomal cup. Soon after the phagosome seals, PtdIns4P levels drop precipitously due to the hydrolytic activity of Sac2 and phospholipase C, becoming undetectable for ∼10 min. PtdIns4P disappearance coincides with the emergence of phagosomal PtdIns3P. Conversely, the disappearance of PtdIns3P that signals the transition from early to late phagosomes is accompanied by resurgence of PtdIns4P, which is associated with the recruitment of phosphatidylinositol 4-kinase 2A. The reacquisition of PtdIns4P can be prevented by silencing expression of the kinase and can be counteracted by recruitment of a 4-phosphatase with a heterodimerization system. Using these approaches, we found that the secondary accumulation of PtdIns4P is required for proper phagosomal acidification. Defective acidification may be caused by impaired recruitment of Rab7 effectors, including RILP, which were shown earlier to displace phagosomes toward perinuclear lysosomes. Our results show multimodal dynamics of PtdIns4P during phagocytosis and suggest that the phosphoinositide plays important roles during the maturation of the phagosome.
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Affiliation(s)
- Roni Levin
- Division of Cell Biology, Hospital for Sick Children, Toronto, ON M5G 1X8, Canada.,Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Gerald R V Hammond
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
| | - Tamas Balla
- Program in Developmental Neuroscience, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892
| | - Pietro De Camilli
- Departments of Neuroscience and Cell Biology, Howard Hughes Medical Institute, Kavli Institute for Neuroscience, Yale University Medical School, New Haven, CT 06510
| | - Gregory D Fairn
- Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada.,Department of Surgery, University of Toronto, Toronto, ON M5T 1P5, Canada.,Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Toronto, ON M5B 1W8, Canada
| | - Sergio Grinstein
- Division of Cell Biology, Hospital for Sick Children, Toronto, ON M5G 1X8, Canada .,Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada.,Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Toronto, ON M5B 1W8, Canada
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20
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Phospholipase Cβ1 induces membrane tubulation and is involved in caveolae formation. Proc Natl Acad Sci U S A 2016; 113:7834-9. [PMID: 27342861 DOI: 10.1073/pnas.1603513113] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Lipid membrane curvature plays important roles in various physiological phenomena. Curvature-regulated dynamic membrane remodeling is achieved by the interaction between lipids and proteins. So far, several membrane sensing/sculpting proteins, such as Bin/amphiphysin/Rvs (BAR) proteins, are reported, but there remains the possibility of the existence of unidentified membrane-deforming proteins that have not been uncovered by sequence homology. To identify new lipid membrane deformation proteins, we applied liposome-based microscopic screening, using unbiased-darkfield microscopy. Using this method, we identified phospholipase Cβ1 (PLCβ1) as a new candidate. PLCβ1 is well characterized as an enzyme catalyzing the hydrolysis of phosphatidylinositol-4,5-bisphosphate (PIP2). In addition to lipase activity, our results indicate that PLCβ1 possessed the ability of membrane tubulation. Lipase domains and inositol phospholipids binding the pleckstrin homology (PH) domain of PLCβ1 were not involved, but the C-terminal sequence was responsible for this tubulation activity. Computational modeling revealed that the C terminus displays the structural homology to the BAR domains, which is well known as a membrane sensing/sculpting domain. Overexpression of PLCβ1 caused plasma membrane tubulation, whereas knockdown of the protein reduced the number of caveolae and induced the evagination of caveolin-rich membrane domains. Taken together, our results suggest a new function of PLCβ1: plasma membrane remodeling, and in particular, caveolae formation.
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21
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Muntean BS, Martemyanov KA. Association with the Plasma Membrane Is Sufficient for Potentiating Catalytic Activity of Regulators of G Protein Signaling (RGS) Proteins of the R7 Subfamily. J Biol Chem 2016; 291:7195-204. [PMID: 26811338 PMCID: PMC4807299 DOI: 10.1074/jbc.m115.713446] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2015] [Revised: 01/21/2016] [Indexed: 12/23/2022] Open
Abstract
Regulators of G protein Signaling (RGS) promote deactivation of heterotrimeric G proteins thus controlling the magnitude and kinetics of responses mediated by G protein-coupled receptors (GPCR). In the nervous system, RGS7 and RGS9-2 play essential role in vision, reward processing, and movement control. Both RGS7 and RGS9-2 belong to the R7 subfamily of RGS proteins that form macromolecular complexes with R7-binding protein (R7BP). R7BP targets RGS proteins to the plasma membrane and augments their GTPase-accelerating protein (GAP) activity, ultimately accelerating deactivation of G protein signaling. However, it remains unclear if R7BP serves exclusively as a membrane anchoring subunit or further modulates RGS proteins to increase their GAP activity. To directly answer this question, we utilized a rapidly reversible chemically induced protein dimerization system that enabled us to control RGS localization independent from R7BP in living cells. To monitor kinetics of Gα deactivation, we coupled this strategy with measuring changes in the GAP activity by bioluminescence resonance energy transfer-based assay in a cellular system containing μ-opioid receptor. This approach was used to correlate changes in RGS localization and activity in the presence or absence of R7BP. Strikingly, we observed that RGS activity is augmented by membrane recruitment, in an orientation independent manner with no additional contributions provided by R7BP. These findings argue that the association of R7 RGS proteins with the membrane environment provides a major direct contribution to modulation of their GAP activity.
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Affiliation(s)
- Brian S Muntean
- From the Department of Neuroscience, The Scripps Research Institute, Jupiter, Florida 33458
| | - Kirill A Martemyanov
- From the Department of Neuroscience, The Scripps Research Institute, Jupiter, Florida 33458
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22
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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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23
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Smrcka AV. Regulation of phosphatidylinositol-specific phospholipase C at the nuclear envelope in cardiac myocytes. J Cardiovasc Pharmacol 2016; 65:203-10. [PMID: 25658460 DOI: 10.1097/fjc.0000000000000195] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Phosphatidylinositol 4,5-bisphosphate hydrolysis at the plasma membrane by phospholipase C is one of the major hormone regulated intracellular signaling systems. The system generates the diffusible second messenger IP3 and the membrane bound messenger diacylglycerol. Spatial regulation of this system has been thought to be through specific subcellular distributions of the IP3 receptor or PKC. As is becoming increasingly apparent, receptor-stimulated signaling systems are also found at intracellular membranes. As discussed in this issue, G protein-coupled receptors have been identified at the nuclear envelope implying intracellular localization of the signaling systems that respond to G protein-coupled receptors. Here, we discuss the evidence for the existence of PLC signals that regulate nuclear processes, as well as the evidence for nuclear and nuclear envelope localization of PLC signaling components, and their implications for cardiac physiology and disease.
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Affiliation(s)
- Alan V Smrcka
- Department of Pharmacology and Physiology, University of Rochester School of Medicine and Dentistry, Rochester, NY
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24
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Lo Vasco VR, Leopizzi M, Di Maio V, Della Rocca C. U-73122 reduces the cell growth in cultured MG-63 ostesarcoma cell line involving Phosphoinositide-specific Phospholipases C. SPRINGERPLUS 2016; 5:156. [PMID: 27026853 PMCID: PMC4766154 DOI: 10.1186/s40064-016-1768-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Accepted: 02/12/2016] [Indexed: 11/24/2022]
Abstract
The definition of the number and nature of the signal transduction pathways involved in the pathogenesis and the identification of the molecules promoting metastasis spread might improve the knowledge of the natural history of osteosarcoma, also allowing refine the prognosis and opening the way to novel therapeutic strategies. Phosphatydil inositol (4,5) bisphosphate (PIP2), belonging to the Phosphoinositide (PI) signal transduction pathway, was related to the regulation of ezrin, an ezrin-radixin-moesin protein involved in metastatic osteosarcoma spread. The levels of PIP2 are regulated by means of the PI-specific Phospholipase C (PLC) enzymes. Recent literature data suggested that in osteosarcoma the panel of expression of PLC isoforms varies in a complex and unclear manner and is related to ezrin, probably networking with Ras GTPases, such as RhoA and Rac1. We analyzed the expression and the subcellular localization of PLC enzymes in cultured human osteosarcoma MG-63 cells, commonly used as an experimental model for human osteoblasts, using U-73122 PLC inhibitor, U-73343 inactive analogue, and by silencing ezrin. The treatment with U-73122 significantly reduces the number of MG-63 viable cells and contemporarily modifies the expression and the subcellular localization of selected PLC isoforms. U-73122 reduces the cell growth in cultured MG-63 ostesarcoma cell line involving PI-specific Phospholipases C.
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Affiliation(s)
- Vincenza Rita Lo Vasco
- />Sensory Organs Department, Policlinico Umberto I, Faculty of Medicine and Dentistry, Sapienza University of Rome, viale dell’Università, 33, 00157 Rome, Italy
| | - Martina Leopizzi
- />Medico-Surgical Sciences and Biotechnology Department, Polo Pontino- Sapienza University of Rome, 04100 Latina, Italy
| | - Valeria Di Maio
- />Medico-Surgical Sciences and Biotechnology Department, Polo Pontino- Sapienza University of Rome, 04100 Latina, Italy
| | - Carlo Della Rocca
- />Medico-Surgical Sciences and Biotechnology Department, Polo Pontino- Sapienza University of Rome, 04100 Latina, Italy
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25
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Charge Shielding of PIP2 by Cations Regulates Enzyme Activity of Phospholipase C. PLoS One 2015; 10:e0144432. [PMID: 26658739 PMCID: PMC4676720 DOI: 10.1371/journal.pone.0144432] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Accepted: 11/18/2015] [Indexed: 11/19/2022] Open
Abstract
Hydrolysis of phosphatidylinositol 4,5-bisphosphate (PIP2) of the plasma membrane by phospholipase C (PLC) generates two critical second messengers, inositol-1,4,5-trisphosphate and diacylglycerol. For the enzymatic reaction, PIP2 binds to positively charged amino acids in the pleckstrin homology domain of PLC. Here we tested the hypothesis that positively charged divalent and multivalent cations accumulate around the negatively charged PIP2, a process called electrostatic charge shielding, and therefore inhibit electrostatic PIP2-PLC interaction. This charge shielding of PIP2 was measured quantitatively with an in vitro enzyme assay using WH-15, a PIP2 analog, and various recombinant PLC proteins (β1, γ1, and δ1). Reduction of PLC activity by divalent cations, polyamines, and neomycin was well described by a theoretical model considering accumulation of cations around PIP2 via their electrostatic interaction and chemical binding. Finally, the charge shielding of PIP2 was also observed in live cells. Perfusion of the cations into cells via patch clamp pipette reduced PIP2 hydrolysis by PLC as triggered by M1 muscarinic receptors with a potency order of Mg2+ < spermine4+ < neomycin6+. Accumulation of divalent cations into cells through divalent-permeable TRPM7 channel had the same effect. Altogether our results suggest that Mg2+ and polyamines modulate the activity of PLCs by controlling the amount of free PIP2 available for the enzymes and that highly charged biomolecules can be inactivated by counterions electrostatically.
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Pascoe HG, Wang Y, Zhang X. Structural mechanisms of plexin signaling. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2015; 118:161-8. [PMID: 25824683 DOI: 10.1016/j.pbiomolbio.2015.03.006] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Revised: 02/20/2015] [Accepted: 03/20/2015] [Indexed: 02/03/2023]
Abstract
Signaling through plexin, the major cell surface receptor for semaphorin, plays critical roles in regulating processes such as neuronal axon guidance, angiogenesis and immune response. Plexin is normally kept inactive in the absence of semaphorin. Upon binding of semaphorin to the extracellular region, plexin is activated and transduces signal to the inside of the cell through its cytoplasmic region. The GTPase Activating Protein (GAP) domain in the plexin cytoplasmic region mediates the major intracellular signaling pathway. The substrate specificity and regulation mechanisms of the GAP domain have only been revealed recently. Many intracellular proteins serve as either upstream regulators or downstream transducers by directly interacting with plexin. The mechanisms of action for some of these proteins also start to emerge from recent studies. We review here these advances in the mechanistic understanding of plexin intracellular signaling from a structural perspective.
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Affiliation(s)
- Heath G Pascoe
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Yuxiao Wang
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Xuewu Zhang
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX, USA; Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, USA.
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