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Akkenepally SV, Yombo DJK, Yerubandi S, Reddy GB, Deshpande DA, McCormack FX, Madala SK. Interleukin 31 receptor α promotes smooth muscle cell contraction and airway hyperresponsiveness in asthma. Nat Commun 2023; 14:8207. [PMID: 38081868 PMCID: PMC10713652 DOI: 10.1038/s41467-023-44040-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Accepted: 11/28/2023] [Indexed: 12/18/2023] Open
Abstract
Asthma is a chronic inflammatory airway disease characterized by airway hyperresponsiveness (AHR), inflammation, and goblet cell hyperplasia. Multiple cytokines, including IFNγ, IL-4, and IL-13 are associated with asthma; however, the mechanisms underlying the effects of these cytokines remain unclear. Here, we report a significant increase in the expression of IL-31RA, but not its cognate ligand IL-31, in mouse models of allergic asthma. In support of this, IFNγ, IL-4, and IL-13 upregulated IL-31RA but not IL-31 in both human and mice primary airway smooth muscle cells (ASMC) isolated from the airways of murine and human lungs. Importantly, the loss of IL-31RA attenuated AHR but had no effect on inflammation and goblet cell hyperplasia in mice challenged with allergens or treated with IL-13 or IFNγ. We show that IL-31RA functions as a positive regulator of muscarinic acetylcholine receptor 3 expression, augmenting calcium levels and myosin light chain phosphorylation in human and murine ASMC. These findings identify a role for IL-31RA in AHR that is distinct from airway inflammation and goblet cell hyperplasia in asthma.
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Affiliation(s)
- Santhoshi V Akkenepally
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Internal Medicine, University of Cincinnati, Cincinnati, OH, USA
- Division of Biochemistry, National Institute of Nutrition, Hyderabad, Telangana, India
| | - Dan J K Yombo
- Division of Pulmonary Medicine, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - Sanjana Yerubandi
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Internal Medicine, University of Cincinnati, Cincinnati, OH, USA
- Division of Pulmonary Medicine, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | | | - Deepak A Deshpande
- Division of Pulmonary, Allergy, and Critical Care Medicine, Center for Translational Medicine, Jane and Leonard Korman Respiratory Institute, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, USA
| | - Francis X McCormack
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Internal Medicine, University of Cincinnati, Cincinnati, OH, USA
| | - Satish K Madala
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Internal Medicine, University of Cincinnati, Cincinnati, OH, USA.
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2
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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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3
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Akkenepally S, Yombo DJK, Yerubandi S, Geereddy BR, McCormack FX, Madala SK. Interleukin 31 receptor alpha augments muscarinic acetylcholine receptor 3-driven calcium signaling and airway hyperresponsiveness in asthma. RESEARCH SQUARE 2023:rs.3.rs-2564484. [PMID: 36824812 PMCID: PMC9949265 DOI: 10.21203/rs.3.rs-2564484/v1] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Asthma is a chronic inflammatory airway disease characterized by airway hyperresponsiveness (AHR), inflammation, and goblet cell hyperplasia. Both Th1 and Th2 cytokines, including IFN-γ, IL-4, and IL-13 have been shown to induce asthma; however, the underlying mechanisms remain unclear. We observed a significant increase in the expression of IL-31RA, but not its cognate ligand IL-31 during allergic asthma. In support of this, IFN-γ and Th2 cytokines, IL-4 and IL-13, upregulated IL-31RA but not IL-31 in airway smooth muscle cells (ASMC). Importantly, the loss of IL-31RA attenuated AHR but had no effects on inflammation and goblet cell hyperplasia in allergic asthma or mice treated with IL-13 or IFN-γ. Mechanistically, we demonstrate that IL-31RA functions as a positive regulator of muscarinic acetylcholine receptor 3 expression and calcium signaling in ASMC. Together, these results identified a novel role for IL-31RA in AHR distinct from airway inflammation and goblet cell hyperplasia in asthma.
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Affiliation(s)
- Santoshi Akkenepally
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Internal Medicine, University of Cincinnati, Cincinnati, Ohio USA
- Division of Biochemistry, National Institute of Nutrition, Hyderabad, Telangana, India
| | - Dan JK Yombo
- Division of Pulmonary Medicine, Department of Pediatrics, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio USA
| | - Sanjana Yerubandi
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Internal Medicine, University of Cincinnati, Cincinnati, Ohio USA
- Division of Pulmonary Medicine, Department of Pediatrics, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio USA
| | | | - Francis X. McCormack
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Internal Medicine, University of Cincinnati, Cincinnati, Ohio USA
| | - Satish K Madala
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Internal Medicine, University of Cincinnati, Cincinnati, Ohio USA
- Division of Pulmonary Medicine, Department of Pediatrics, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio USA
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4
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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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5
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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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6
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Phillygenin, a lignan compound, inhibits hypertension by reducing PLCβ3-dependent Ca2+ oscillation. J Funct Foods 2019. [DOI: 10.1016/j.jff.2019.103432] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
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7
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Scarlata S. The role of phospholipase Cβ on the plasma membrane and in the cytosol: How modular domains enable novel functions. Adv Biol Regul 2019; 73:100636. [PMID: 31409535 DOI: 10.1016/j.jbior.2019.100636] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Revised: 07/14/2019] [Accepted: 07/25/2019] [Indexed: 01/14/2023]
Abstract
Phospholipase Cβ (PLCβ) is a signaling enzyme activated by G proteins to generate calcium signals. The catalytic core of PLCβ is surrounded by modular domains that mediate the interaction of the enzyme with known protein partners on the plasma membrane. The C-terminal region PLCβ contains a novel coiled-coil domain that is required for Gαq binding and activation. Recent work has shown that this domain also binds a number of cytosolic proteins that regulate protein translation, and that these proteins compete with Gαq for PLCβ binding. The ability of PLCβ to shuttle between the cytosol to impact protein translation and the plasma membrane to mediate calcium signals puts PLCβ in a central role in cell function.
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Affiliation(s)
- Suzanne Scarlata
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, 100 Institute Rd., Worcester, MA, 01609, United States.
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8
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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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9
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Garland-Kuntz EE, Vago FS, Sieng M, Van Camp M, Chakravarthy S, Blaine A, Corpstein C, Jiang W, Lyon AM. Direct observation of conformational dynamics of the PH domain in phospholipases Cϵ and β may contribute to subfamily-specific roles in regulation. J Biol Chem 2018; 293:17477-17490. [PMID: 30242131 PMCID: PMC6231117 DOI: 10.1074/jbc.ra118.003656] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Revised: 09/17/2018] [Indexed: 12/19/2022] Open
Abstract
Phospholipase C (PLC) enzymes produce second messengers that increase the intracellular Ca2+ concentration and activate protein kinase C (PKC). These enzymes also share a highly conserved arrangement of core domains. However, the contributions of the individual domains to regulation are poorly understood, particularly in isoforms lacking high-resolution information, such as PLCϵ. Here, we used small-angle X-ray scattering (SAXS), EM, and functional assays to gain insights into the molecular architecture of PLCϵ, revealing that its PH domain is conformationally dynamic and essential for activity. We further demonstrate that the PH domain of PLCβ exhibits similar dynamics in solution that are substantially different from its conformation observed in multiple previously reported crystal structures. We propose that this conformational heterogeneity contributes to subfamily-specific differences in activity and regulation by extracellular signals.
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Affiliation(s)
| | - Frank S Vago
- Biological Sciences, Purdue University, West Lafayette, Indiana 47907 and
| | | | | | - Srinivas Chakravarthy
- the Biophysics Collaborative Access Team, Illinois Institute of Technology, Sector 18ID, Advanced Photon Source, Argonne National Laboratory, Lemont, Illinois 60439
| | | | | | - Wen Jiang
- Biological Sciences, Purdue University, West Lafayette, Indiana 47907 and
| | - Angeline M Lyon
- From the Departments of Chemistry and
- Biological Sciences, Purdue University, West Lafayette, Indiana 47907 and
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10
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Roberts MF, Khan HM, Goldstein R, Reuter N, Gershenson A. Search and Subvert: Minimalist Bacterial Phosphatidylinositol-Specific Phospholipase C Enzymes. Chem Rev 2018; 118:8435-8473. [DOI: 10.1021/acs.chemrev.8b00208] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Mary F. Roberts
- Department of Chemistry, Boston College, Chestnut Hill, Massachusetts 02467, United States
| | | | - Rebecca Goldstein
- Department of Chemistry, Boston College, Chestnut Hill, Massachusetts 02467, United States
| | | | - Anne Gershenson
- Department of Biochemistry and Molecular Biology, University of Massachusetts Amherst, Amherst, Massachusetts 01003, United States
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11
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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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12
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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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13
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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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14
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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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15
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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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16
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Qin Y, Zhong Y, Yang G, Ma T, Jia L, Huang C, Li Z. Profiling of concanavalin A-binding glycoproteins in human hepatic stellate cells activated with transforming growth factor-β1. Molecules 2014; 19:19845-67. [PMID: 25460309 PMCID: PMC6270946 DOI: 10.3390/molecules191219845] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2014] [Revised: 11/18/2014] [Accepted: 11/24/2014] [Indexed: 12/20/2022] Open
Abstract
Glycoproteins play important roles in maintaining normal cell functions depending on their glycosylations. Our previous study indicated that the abundance of glycoproteins recognized by concanavalin A (ConA) was increased in human hepatic stellate cells (HSCs) following activation by transforming growth factor-β1 (TGF-β1); however, little is known about the ConA-binding glycoproteins (CBGs) of HSCs. In this study, we employed a targeted glycoproteomics approach using lectin-magnetic particle conjugate-based liquid chromatography-tandem mass spectrometry to compare CBG profiles between LX-2 HSCs with and without activation by TGF-β1, with the aim of discovering novel CBGs and determining their possible roles in activated HSCs. A total of 54 and 77 proteins were identified in the quiescent and activated LX-2 cells, respectively. Of the proteins identified, 14.3% were glycoproteins and 73.3% were novel potential glycoproteins. Molecules involved in protein processing in the endoplasmic reticulum (e.g., calreticulin) and calcium signaling (e.g., 1-phosphatidylinositol-4,5-bisphosphate phosphodiesterase β-2 [PLCB2]) were specifically identified in activated LX-2 cells. Additionally, PLCB2 expression was upregulated in the cytoplasm of the activated LX-2 cells, as well as in the hepatocytes and sinusoidal cells of liver cirrhosis tissues. In conclusion, the results of this study may aid future investigations to find new molecular mechanisms involved in HSC activation and antifibrotic therapeutic targets.
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Affiliation(s)
- Yannan Qin
- Department of Genetics and Molecular Biology, Xi'an Jiaotong University College of Medicine, Xi'an 710061, Shaanxi, China.
| | - Yaogang Zhong
- Laboratory for Functional Glycomics, College of Life Sciences, Northwest University, Xi'an 710069, Shaanxi, China.
| | - Ganglong Yang
- Laboratory for Functional Glycomics, College of Life Sciences, Northwest University, Xi'an 710069, Shaanxi, China.
| | - Tianran Ma
- Laboratory for Functional Glycomics, College of Life Sciences, Northwest University, Xi'an 710069, Shaanxi, China.
| | - Liyuan Jia
- Laboratory for Functional Glycomics, College of Life Sciences, Northwest University, Xi'an 710069, Shaanxi, China.
| | - Chen Huang
- Department of Genetics and Molecular Biology, Xi'an Jiaotong University College of Medicine, Xi'an 710061, Shaanxi, China.
| | - Zheng Li
- Laboratory for Functional Glycomics, College of Life Sciences, Northwest University, Xi'an 710069, Shaanxi, China.
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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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18
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Kan W, Adjobo-Hermans M, Burroughs M, Faibis G, Malik S, Tall GG, Smrcka AV. M3 muscarinic receptor interaction with phospholipase C β3 determines its signaling efficiency. J Biol Chem 2014; 289:11206-11218. [PMID: 24596086 DOI: 10.1074/jbc.m113.538546] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Phospholipase Cβ (PLCβ) enzymes are activated by G protein-coupled receptors through receptor-catalyzed guanine nucleotide exchange on Gαβγ heterotrimers containing Gq family G proteins. Here we report evidence for a direct interaction between M3 muscarinic receptor (M3R) and PLCβ3. Both expressed and endogenous M3R interacted with PLCβ in coimmunoprecipitation experiments. Stimulation of M3R with carbachol significantly increased this association. Expression of M3R in CHO cells promoted plasma membrane localization of YFP-PLCβ3. Deletion of the PLCβ3 C terminus or deletion of the PLCβ3 PDZ ligand inhibited coimmunoprecipitation with M3R and M3R-dependent PLCβ3 plasma membrane localization. Purified PLCβ3 bound directly to glutathione S-transferase (GST)-fused M3R intracellular loops 2 and 3 (M3Ri2 and M3Ri3) as well as M3R C terminus (M3R/H8-CT). PLCβ3 binding to M3Ri3 was inhibited when the PDZ ligand was removed. In assays using reconstituted purified components in vitro, M3Ri2, M3Ri3, and M3R/H8-CT potentiated Gαq-dependent but not Gβγ-dependent PLCβ3 activation. Disruption of key residues in M3Ri3N and of the PDZ ligand in PLCβ3 inhibited M3Ri3-mediated potentiation. We propose that the M3 muscarinic receptor maximizes the efficiency of PLCβ3 signaling beyond its canonical role as a guanine nucleotide exchange factor for Gα.
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Affiliation(s)
- Wei Kan
- Departments of Pharmacology and Physiology and University of Rochester School of Medicine and Dentistry, Rochester, New York 14642
| | - Merel Adjobo-Hermans
- Department of Biochemistry, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical Centre, Geert Grooteplein 28, 6525 GA Nijmegen, The Netherlands
| | - Michael Burroughs
- Departments of Pharmacology and Physiology and University of Rochester School of Medicine and Dentistry, Rochester, New York 14642
| | - Guy Faibis
- Departments of Pharmacology and Physiology and University of Rochester School of Medicine and Dentistry, Rochester, New York 14642
| | - Sundeep Malik
- Departments of Pharmacology and Physiology and University of Rochester School of Medicine and Dentistry, Rochester, New York 14642
| | - Gregory G Tall
- Departments of Pharmacology and Physiology and University of Rochester School of Medicine and Dentistry, Rochester, New York 14642
| | - Alan V Smrcka
- Departments of Pharmacology and Physiology and University of Rochester School of Medicine and Dentistry, Rochester, New York 14642; Biochemistry and Biophysics and University of Rochester School of Medicine and Dentistry, Rochester, New York 14642; Aab Institute of Cardiovascular Research, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642 and.
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19
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Lyon AM, Taylor VG, Tesmer JJG. Strike a pose: Gαq complexes at the membrane. Trends Pharmacol Sci 2013; 35:23-30. [PMID: 24287282 DOI: 10.1016/j.tips.2013.10.008] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Revised: 10/16/2013] [Accepted: 10/21/2013] [Indexed: 12/20/2022]
Abstract
The heterotrimeric G protein Gαq is a central player in signal transduction, relaying signals from activated G-protein-coupled receptors (GPCRs) to effectors and other proteins to elicit changes in intracellular Ca(2+), the actin cytoskeleton, and gene transcription. Gαq functions at the intracellular surface of the plasma membrane, as do its best-characterized targets, phospholipase C-β, p63RhoGEF, and GPCR kinase 2 (GRK2). Recent insights into the structure and function of these signaling complexes reveal several recurring themes, including complex multivalent interactions between Gαq, its protein target, and the membrane, that are likely essential for allosteric control and maximum efficiency in signal transduction. Thus, the plasma membrane is not only a source of substrates but also a key player in the scaffolding of Gαq-dependent signaling pathways.
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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, MI, USA
| | - Veronica G Taylor
- Life Sciences Institute and the Departments of Pharmacology and Biological Chemistry, University of Michigan, Ann Arbor, MI, USA
| | - John J G Tesmer
- Life Sciences Institute and the Departments of Pharmacology and Biological Chemistry, University of Michigan, Ann Arbor, MI, USA.
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20
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Abstract
Rapid progress has recently been made regarding how phospholipase C (PLC)-β functions downstream of G protein-coupled receptors and how PLC-β functions in the nucleus. PLC-β has also been shown to interplay with tyrosine kinase-based signaling pathways, specifically to inhibit Stat5 activation by recruiting the protein-tyrosine phosphatase SHP-1. In this regard, a new multimolecular signaling platform, named SPS complex, has been identified. The SPS complex has important regulatory roles in tumorigenesis and immune cell activation. Furthermore, a growing body of work suggests that PLC-β also participates in the differentiation and activation of immune cells that control both the innate and adaptive immune systems.
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Affiliation(s)
- Wenbin Xiao
- Department of Pathology, University Hospital Case Medical Center, Case Western Reserve University, Cleveland, OH 44106, USA.
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21
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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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22
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Pokotylo I, Kolesnikov Y, Kravets V, Zachowski A, Ruelland E. Plant phosphoinositide-dependent phospholipases C: variations around a canonical theme. Biochimie 2013; 96:144-57. [PMID: 23856562 DOI: 10.1016/j.biochi.2013.07.004] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Accepted: 07/04/2013] [Indexed: 01/01/2023]
Abstract
Phosphoinositide-specific phospholipase C (PI-PLC) cleaves, in a Ca(2+)-dependent manner, phosphatidylinositol-4,5-bisphosphate (PI-4,5-P2) into diacylglycerol (DAG) and inositol triphosphate (IP3). PI-PLCs are multidomain proteins that are structurally related to the PI-PLCζs, the simplest animal PI-PLCs. Like these animal counterparts, they are only composed of EF-hand, X/Y and C2 domains. However, plant PI-PLCs do not have a conventional EF-hand domain since they are often truncated, while some PI-PLCs have no EF-hand domain at all. Despite this simple structure, plant PI-PLCs are involved in many essential plant processes, either associated with development or in response to environmental stresses. The action of PI-PLCs relies on the mediators they produce. In plants, IP3 does not seem to be the sole active soluble molecule. Inositol pentakisphosphate (IP5) and inositol hexakisphosphate (IP6) also transmit signals, thus highlighting the importance of coupling PI-PLC action with inositol-phosphate kinases and phosphatases. PI-PLCs also produce a lipid molecule, but plant PI-PLC pathways show a peculiarity in that the active lipid does not appear to be DAG but its phosphorylated form, phosphatidic acid (PA). Besides, PI-PLCs can also act by altering their substrate levels. Taken together, plant PI-PLCs show functional differences when compared to their animal counterparts. However, they act on similar general signalling pathways including calcium homeostasis and cell phosphoproteome. Several important questions remain unanswered. The cross-talk between the soluble and lipid mediators generated by plant PI-PLCs is not understood and how the coupling between PI-PLCs and inositol-kinases or DAG-kinases is carried out remains to be established.
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Affiliation(s)
- Igor Pokotylo
- Institute of Bioorganic Chemistry and Petrochemistry, NAS of Ukraine, Kiev, Ukraine.
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23
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Abstract
Phosphoinositides (PIs) make up only a small fraction of cellular phospholipids, yet they control almost all aspects of a cell's life and death. These lipids gained tremendous research interest as plasma membrane signaling molecules when discovered in the 1970s and 1980s. Research in the last 15 years has added a wide range of biological processes regulated by PIs, turning these lipids into one of the most universal signaling entities in eukaryotic cells. PIs control organelle biology by regulating vesicular trafficking, but they also modulate lipid distribution and metabolism via their close relationship with lipid transfer proteins. PIs regulate ion channels, pumps, and transporters and control both endocytic and exocytic processes. The nuclear phosphoinositides have grown from being an epiphenomenon to a research area of its own. As expected from such pleiotropic regulators, derangements of phosphoinositide metabolism are responsible for a number of human diseases ranging from rare genetic disorders to the most common ones such as cancer, obesity, and diabetes. Moreover, it is increasingly evident that a number of infectious agents hijack the PI regulatory systems of host cells for their intracellular movements, replication, and assembly. As a result, PI converting enzymes began to be noticed by pharmaceutical companies as potential therapeutic targets. This review is an attempt to give an overview of this enormous research field focusing on major developments in diverse areas of basic science linked to cellular physiology and disease.
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Affiliation(s)
- Tamas Balla
- Section on Molecular Signal Transduction, Program for Developmental Neuroscience, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA.
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24
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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: 67] [Impact Index Per Article: 6.1] [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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25
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Adjobo-Hermans MJ, Crosby KC, Putyrski M, Bhageloe A, van Weeren L, Schultz C, Goedhart J, Gadella TW. PLCβ isoforms differ in their subcellular location and their CT-domain dependent interaction with Gαq. Cell Signal 2013; 25:255-63. [DOI: 10.1016/j.cellsig.2012.09.022] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2012] [Revised: 09/08/2012] [Accepted: 09/16/2012] [Indexed: 11/15/2022]
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26
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Philip F, Guo Y, Aisiku O, Scarlata S. Phospholipase Cβ1 is linked to RNA interference of specific genes through translin-associated factor X. FASEB J 2012; 26:4903-13. [PMID: 22889834 PMCID: PMC3509058 DOI: 10.1096/fj.12-213934] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2012] [Accepted: 08/06/2012] [Indexed: 12/26/2022]
Abstract
Phospholipase Cβ1 (PLCβ1) is a G-protein-regulated enzyme whose activity results in proliferative and mitogenic changes in the cell. We have previously found that in solution PLCβ1 binds to the RNA processing protein translin-associated factor X (TRAX) with nanomolar affinity and that this binding competes with G proteins. Here, we show that endogenous PLCβ1 and TRAX interact in SK-N-SH cells and also in HEK293 cells induced to overexpress PLCβ1. In HEK293 cells, TRAX overexpression ablates Ca(2+) signals generated by G protein-PLCβ1 activation. TRAX plays a key role in down-regulation of proteins by small, interfering RNA, and PLCβ1 overexpression completely reverses the 2- to 4-fold down-regulation of GAPDH by siRNA in HEK293 and HeLa cells as seen by an ∼4-fold recovery in both the transcript and protein levels. Also, down-regulation of endogenous PLCβ1 in HEK293 and HeLa cells allows for an ∼20% increase in siRNA(GAPDH) silencing. While PLCβ1 overexpression results in a 50% reversal of cell death caused by siRNA(LDH), it does not affect cell survival or silencing of other genes (e.g., cyclophilin, Hsp90, translin). PLCβ1 overexpression in HEK293 and HeLa cells causes a 30% reduction in the total amount of small RNAs. LDH and GAPDH are part of a complex that promotes H2B synthesis that allows cells to progress through the S phase. We find that PLCβ1 reverses the cell death and completely rescues H2B levels caused by siRNA knockdown of LDH or GAPDH. Taken together, our study shows a novel role of PLCβ1 in gene regulation through TRAX association.
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Affiliation(s)
- Finly Philip
- Department of Physiology and Biophysics, Stony Brook University, Stony Brook, New York, USA
| | - Yuanjian Guo
- Department of Physiology and Biophysics, Stony Brook University, Stony Brook, New York, USA
| | | | - Suzanne Scarlata
- Department of Physiology and Biophysics, Stony Brook University, Stony Brook, New York, USA
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27
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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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28
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Awasthi M, Batra J, Kateriya S. Disulphide bridges of phospholipase C of Chlamydomonas reinhardtii modulates lipid interaction and dimer stability. PLoS One 2012; 7:e39258. [PMID: 22737232 PMCID: PMC3380823 DOI: 10.1371/journal.pone.0039258] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2012] [Accepted: 05/22/2012] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Phospholipase C (PLC) is an enzyme that plays pivotal role in a number of signaling cascades. These are active in the plasma membrane and triggers cellular responses by catalyzing the hydrolysis of membrane phospholipids and thereby generating the secondary messengers. Phosphatidylinositol-PLC (PI-PLC) specifically interacts with phosphoinositide and/or phosphoinositol and catalyzes specific cleavage of sn-3- phosphodiester bond. Several isoforms of PLC are known to form and function as dimer but very little is known about the molecular basis of the dimerization and its importance in the lipid interaction. PRINCIPAL FINDINGS We herein report that, the disruption of disulphide bond of a novel PI-specific PLC of C. reinhardtii (CrPLC) can modulate its interaction affinity with a set of phospholipids and also the stability of its dimer. CrPLC was found to form a mixture of higher oligomeric states with monomer and dimer as major species. Dimer adduct of CrPLC disappeared in the presence of DTT, which suggested the involvement of disulphide bond(s) in CrPLC oligomerization. Dimer-monomer equilibrium studies with the isolated fractions of CrPLC monomer and dimer supported the involvement of covalent forces in the dimerization of CrPLC. A disulphide bridge was found to be responsible for the dimerization and Cys7 seems to be involved in the formation of the disulphide bond. This crucial disulphide bond also modulated the lipid affinity of CrPLC. Oligomers of CrPLC were also captured in in vivo condition. CrPLC was mainly found to be localized in the plasma membrane of the cell. The cell surface localization of CrPLC may have significant implication in the downstream regulatory function of CrPLC. SIGNIFICANCE This study helps in establishing the role of CrPLC (or similar proteins) in the quaternary structure of the molecule its affinities during lipid interactions.
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Affiliation(s)
- Mayanka Awasthi
- Department of Biochemistry, University of Delhi, South Campus, New Delhi, India
| | - Jyoti Batra
- Department of Biochemistry, University of Delhi, South Campus, New Delhi, India
| | - Suneel Kateriya
- Department of Biochemistry, University of Delhi, South Campus, New Delhi, India
- * E-mail:
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29
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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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30
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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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31
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Yasudo H, Ando T, Xiao W, Kawakami Y, Kawakami T. Short Stat5-interacting peptide derived from phospholipase C-β3 inhibits hematopoietic cell proliferation and myeloid differentiation. PLoS One 2011; 6:e24995. [PMID: 21949826 PMCID: PMC3176784 DOI: 10.1371/journal.pone.0024995] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2011] [Accepted: 08/22/2011] [Indexed: 11/18/2022] Open
Abstract
Constitutive activation of the transcription factor Stat5 in hematopoietic stem/progenitor cells leads to various hematopoietic malignancies including myeloproliferative neoplasm (MPN). Our recent study found that phospholipase C (PLC)-β3 is a novel tumor suppressor involved in MPN, lymphoma and other tumors. Stat5 activity is negatively regulated by the SH2 domain-containing protein phosphatase SHP-1 in a PLC-β3-dependent manner. PLC-β3 can form the multimolecular SPS complex together with SHP-1 and Stat5. The close physical proximity of SHP-1 and Stat5 brought about by interacting with the C-terminal segment of PLC-β3 (PLC-β3-CT) accelerates SHP-1-mediated dephosphorylation of Stat5. Here we identify the minimal sequences within PLC-β3-CT required for its tumor suppressor function. Two of the three Stat5-binding noncontiguous regions, one of which also binds SHP-1, substantially inhibited in vitro proliferation of Ba/F3 cells. Surprisingly, an 11-residue Stat5-binding peptide (residues 988-998) suppressed Stat5 activity in Ba/F3 cells and in vivo proliferation and myeloid differentiation of hematopoietic stem/progenitor cells. Therefore, this study further defines PLC-β3-CT as the Stat5- and SHP-1-binding domain by identifying minimal functional sequences of PLC-β3 for its tumor suppressor function and implies their potential utility in the control of hematopoietic malignancies.
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Affiliation(s)
- Hiroki Yasudo
- Division of Cell Biology, La Jolla Institute for Allergy and Immunology, La Jolla, California, United States of America
| | - Tomoaki Ando
- Division of Cell Biology, La Jolla Institute for Allergy and Immunology, La Jolla, California, United States of America
| | - Wenbin Xiao
- Division of Cell Biology, La Jolla Institute for Allergy and Immunology, La Jolla, California, United States of America
| | - Yuko Kawakami
- Division of Cell Biology, La Jolla Institute for Allergy and Immunology, La Jolla, California, United States of America
| | - Toshiaki Kawakami
- Division of Cell Biology, La Jolla Institute for Allergy and Immunology, La Jolla, California, United States of America
- * E-mail:
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32
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Weinstein H, Scarlata S. The correlation between multidomain enzymes and multiple activation mechanisms--the case of phospholipase Cβ and its membrane interactions. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1808:2940-7. [PMID: 21906583 DOI: 10.1016/j.bbamem.2011.08.028] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2011] [Revised: 08/23/2011] [Accepted: 08/23/2011] [Indexed: 10/17/2022]
Abstract
Phospholipase Cβ2 (PLCβ2) is a large, multidomain enzyme that catalyzes the hydrolysis of the signaling lipid phosphoinositol 4,5 bisphosphate (PIP2) to promote mitogenic and proliferative changes in the cell. PLCβ2 is activated by Gα and Gβγ subunits of heterotrimeric G proteins, as well as small G proteins and specific peptides. Activation depends on the nature of the membrane surface. Recent crystal structures suggest one model of activation involving the movement of a small autoinhibitory loop upon membrane binding of the enzyme. Additionally, solution studies indicate multiple levels of activation that involve changes in the membrane orientation as well as interdomain movement. Here, we review the wealth of biochemical studies of PLCβ2-G protein activation and propose a comprehensive model that accounts for both the crystallographic and solution results.
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Affiliation(s)
- Harel Weinstein
- Department of Physiology and Biophysics, Weill Cornell Medical College, Cornell University, 1300 York Avenue, New York, NY 10065, USA
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33
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An autoinhibitory helix in the C-terminal region of phospholipase C-β mediates Gαq activation. Nat Struct Mol Biol 2011; 18:999-1005. [PMID: 21822282 PMCID: PMC3168981 DOI: 10.1038/nsmb.2095] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2011] [Accepted: 06/01/2011] [Indexed: 01/28/2023]
Abstract
Phospholipase C-β (PLCβ) is a key regulator of intracellular calcium levels whose activity is controlled by heptahelical receptors that couple to Gq. We have determined atomic structures of two invertebrate homologs of PLCβ (PLC21) from cephalopod retina and identified a helix from the C-terminal regulatory region that interacts with a conserved surface of the catalytic core of the enzyme. Mutations designed to disrupt the analogous interaction in human PLCβ3 dramatically increase basal activity and diminish stimulation by Gαq. Gαq binding requires displacement of the autoinhibitory helix from the catalytic core, thus providing an allosteric mechanism for activation of PLCβ.
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34
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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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35
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Abstract
Heterotrimeric G proteins and G protein-coupled receptors represent conserved protein families with origins in the prokaryotes, but the various G protein-regulated effectors are heterogeneous in structure and function. The effectors apparently evolved ways to listen to G proteins late in their evolutionary histories. The structure of a complex between the effector protein phospholipase C-β3 (PLC-β3) and its activator, Gα(q), suggests that several effectors independently evolved a structurally similar helix-turn-helix segment for G protein recognition. PLC-βs are also guanosine triphosphatase (GTPase)-activating proteins (GAPs) for the G(q) that activates them. In a second example of convergent evolution, the GAP activity of these proteins depends on a flexible asparagine-containing loop that resembles the GAP site on RGS proteins, another family of G protein GAPs. Together, these two sites are proposed to cooperate to enable fast binding to activated Gα(q), followed by fast deactivation. This cycle allows rapid sampling of the activation state of G(q)-coupled receptors while providing efficient signal transduction.
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Affiliation(s)
- Elliott M Ross
- Department of Pharmacology, University of Texas Southwestern Medical Center, 6001 Forest Park Road, Dallas, TX 75390-9041, USA.
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Aisiku OR, Runnels LW, Scarlata S. Identification of a novel binding partner of phospholipase cβ1: translin-associated factor X. PLoS One 2010; 5:e15001. [PMID: 21124736 PMCID: PMC2993962 DOI: 10.1371/journal.pone.0015001] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2010] [Accepted: 10/05/2010] [Indexed: 11/25/2022] Open
Abstract
Mammalian phospholipase Cβ1 (PLCβ1) is activated by the ubiquitous Gαq family of G proteins on the surface of the inner leaflet of plasma membrane where it catalyzes the hydrolysis of phosphatidylinositol 4,5 bisphosphate. In general, PLCβ1 is mainly localized on the cytosolic plasma membrane surface, although a substantial fraction is also found in the cytosol and, under some conditions, in the nucleus. The factors that localize PLCβ1in these other compartments are unknown. Here, we identified a novel binding partner, translin-associated factor X (TRAX). TRAX is a cytosolic protein that can transit into the nucleus. In purified form, PLCβ1 binds strongly to TRAX with an affinity that is only ten-fold weaker than its affinity for its functional partner, Gαq. In solution, TRAX has little effect on the membrane association or the catalytic activity of PLCβ1. However, TRAX directly competes with Gαq for PLCβ1 binding, and excess TRAX reverses Gαq activation of PLCβ1. In C6 glia cells, endogenous PLCβ1 and TRAX colocalize in the cytosol and the nucleus, but not on the plasma membrane where TRAX is absent. In Neuro2A cells expressing enhanced yellow and cyano fluorescent proteins (i.e., eYFP- PLCβ1 and eCFP-TRAX), Förster resonance energy transfer (FRET) is observed mostly in the cytosol and a small amount is seen in the nucleus. FRET does not occur at the plasma membrane where TRAX is not found. Our studies show that TRAX, localized in the cytosol and nucleus, competes with plasma-membrane bound Gαq for PLCβ1 binding thus stabilizing PLCβ1 in other cellular compartments.
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Affiliation(s)
- Omozuanvbo R. Aisiku
- Department of Physiology and Biophysics, Stony Brook University, Stony Brook, New York, United States of America
| | - Loren W. Runnels
- Department of Pharmacology, University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, New Brunswick, New Jersey, United States of America
| | - Suzanne Scarlata
- Department of Physiology and Biophysics, Stony Brook University, Stony Brook, New York, United States of America
- * E-mail:
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Kim JK, Lim S, Kim J, Kim S, Kim JH, Ryu SH, Suh PG. Subtype-specific roles of phospholipase C-β via differential interactions with PDZ domain proteins. ACTA ACUST UNITED AC 2010; 51:138-51. [PMID: 21035486 DOI: 10.1016/j.advenzreg.2010.10.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2010] [Accepted: 10/05/2010] [Indexed: 12/13/2022]
Abstract
Since we first identified the PLC-β isozyme, enormous studies have been conducted to investigate the functional roles of this protein (Min et al., 1993; Suh et al.,1988). It is now well-known that the four PLC-β subtypes are major effector molecules in GPCR-mediated signaling, especially for intracellular Ca2+ signaling. Nonetheless, it is still poorly understood why multiple PLC-β subtype exist. Most cells express multiple subtypes of PLC-β in different combinations, and each subtype is involved in somewhat different signaling pathways. Therefore, studying the differential roles of each PLC-β subtype is a very interesting issue. In this regard, we focus here on PDZ domain proteins which are novel PLC-β interacting proteins. As scaffolders, PDZ domain proteins recruit various target proteins ranging from membrane receptors to cytoskeletal proteins to assemble highly organized signaling complexes; this can give rise to efficiency and diversity in cellular signaling. Because PLC-β subtypes have different PDZ-binding motifs, it is possible that they are engaged with different PDZ domain proteins, and in turn participate in distinct physiological responses. To date, several PDZ domain proteins, such as the NHERF family, Shank2, and Par-3, have been reported to selectively interact with certain PLC-β subtypes and GPCRs. Systematic predictions of potential binding partners also suggests differential binding properties between PLC-β subtypes. Furthermore, we elucidated parallel signaling processes for multiple PLC-β subtypes, which still perform distinct functions resulting from differential interactions with PDZ domain proteins within a single cell. Therefore, these results highlight the novel function of PDZ domain proteins as intermediaries in subtype-specific role of PLC-β in GPCR-mediated signaling. Future studies will focus on the physiological meanings of this signaling complex formation by different PDZ domain proteins and PLC-β subtypes. It has been observed for a long time that the expression of certain PLC-β subtype fluctuates during diverse physiological conditions. For example, the expression of PLC-β1 is selectively increased during myoblast and adipocyte differentiation (Faenza et al., 2004; O'Carroll et al., 2009). Likewise, PLC-β2 is highly up-regulated during breast cancer progression and plays a critical role in cell migration and mitosis (Bertagnolo et al., 2007). Although PLC-β3 is selectively down-regulated in neuroendocrine tumors, the expression of PLC-β1 is increased in small cell lung carcinoma (Stalberg et al., 2003; Strassheim et al., 2000). In our hypothetical model, it is most likely that up- and down regulation of certain PLC-β subtypes are due to their selective coupling with specific GPCR-mediated signaling, implicated in these pathophysiologic conditions. Therefore, better understanding of selective coupling between PLC-β subtypes, PDZ domain proteins, and GPCRs will shed light on new prognosis and therapy of diverse diseases, and provide potential targets for drug development.
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Affiliation(s)
- Jung Kuk Kim
- School of Nano-Biotechnology & Chemical Engineering, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
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Bunney TD, Katan M. PLC regulation: emerging pictures for molecular mechanisms. Trends Biochem Sci 2010; 36:88-96. [PMID: 20870410 DOI: 10.1016/j.tibs.2010.08.003] [Citation(s) in RCA: 142] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2010] [Revised: 08/20/2010] [Accepted: 08/23/2010] [Indexed: 11/28/2022]
Abstract
Phosphoinositide-specific phospholipase C (PLC) enzymes are common signalling components linked to the activation of most cellular receptors. All PLC families are complex, modular, multi-domain proteins and together cover a broad spectrum of regulatory interactions, including direct binding to G protein subunits, small GTPases from Rho and Ras families, receptor and non-receptor tyrosine kinases and lipid components of cellular membranes. Recent structural determinations of PLC components and their complexes with regulatory proteins and direct mechanistic studies, together with earlier work, have provided the foundation to propose molecular mechanisms that stringently regulate PLC activity.
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Affiliation(s)
- Tom D Bunney
- The Institute of Cancer Research, Section for Cell and Molecular Biology, Chester Beatty Laboratories, Fulham Road, London SW3 6JB, UK
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Philip F, Kadamur G, Silos RG, Woodson J, Ross EM. Synergistic activation of phospholipase C-beta3 by Galpha(q) and Gbetagamma describes a simple two-state coincidence detector. Curr Biol 2010; 20:1327-35. [PMID: 20579885 DOI: 10.1016/j.cub.2010.06.013] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2010] [Revised: 05/31/2010] [Accepted: 06/01/2010] [Indexed: 01/12/2023]
Abstract
BACKGROUND Receptors that couple to G(i) and G(q) often interact synergistically in cells to elicit cytosolic Ca(2+) transients that are several-fold higher than the sum of those driven by each receptor alone. Such synergism is commonly assumed to be complex, requiring regulatory interaction between components, multiple pathways, or multiple states of the target protein. RESULTS We show that cellular G(i)-G(q) synergism derives from direct supra-additive stimulation of phospholipase C-beta3 (PLC-beta3) by G protein subunits Gbetagamma and Galpha(q), the relevant components of the G(i) and G(q) signaling pathways. No additional pathway or proteins are required. Synergism is quantitatively explained by the classical and simple two-state (inactive<-->active) allosteric mechanism. We show generally that synergistic activation of a two-state enzyme reflects enhanced conversion to the active state when both ligands are bound, not merely the enhancement of ligand affinity predicted by positive cooperativity. The two-state mechanism also explains why synergism is unique to PLC-beta3 among the four PLC-beta isoforms and, in general, why one enzyme may respond synergistically to two activators while another does not. Expression of synergism demands that an enzyme display low basal activity in the absence of ligand and becomes significant only when basal activity is </= 0.1% of maximal. CONCLUSIONS Synergism can be explained by a simple and general mechanism, and such a mechanism sets parameters for its occurrence. Any two-state enzyme is predicted to respond synergistically to multiple activating ligands if, but only if, its basal activity is strongly suppressed.
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Affiliation(s)
- Finly Philip
- Department of Pharmacology, University of Texas Southwestern Medical Center, 6001 Forest Park Road, Dallas, TX 75390-9041, USA
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40
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Phosphatidic acid potentiates G(alpha)q stimulation of phospholipase C-beta1 signaling. Biochem Biophys Res Commun 2009; 390:603-7. [PMID: 19818737 DOI: 10.1016/j.bbrc.2009.10.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2009] [Accepted: 10/04/2009] [Indexed: 01/08/2023]
Abstract
Phosphatidic acid (PA) is interactive with G(alpha)q-linked agonists to stimulate GPCR signaling via phospholipase C-beta(1) (PLC-beta(1)). Phorbol 12-myristate 13-acetate (PMA) increases cellular levels of PA and phospholipase D activity (PLD). This study evaluated whether PMA can stimulate PLC-beta(1) activity via PA, independent of GPCR input in transfected COS 7 cells. PMA alone had little effect on PLC activity in cells co-transfected with PLC-beta(1) and G(alpha)q. Activated G(alpha)q, induced by co-transfecting muscarinic cholinergic receptor (m1R), was necessary for stimulation of PLC-beta(1) activity by PMA. Stimulation by PMA was dependent on the PA-regulatory motif of PLC-beta(1) implicating PA in this mechanism. PLD1 knockdown by antisense decreased responsiveness of PLC-beta(1) to both PMA and carbachol. PA alone thus has little effect on PLC-beta(1) activity, but PA and PLD1 synergize with activated G(alpha)q to stimulate PLC-beta(1) signaling. Coordinate interaction with activated G(alpha)q may serve as an important mechanism to fine tune response to ligands while preventing spurious initiation of PLC-beta signaling by PA in cells.
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41
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Zhang Y, Kwon SH, Vogel WK, Filtz TM. PI(3,4,5)P3 potentiates phospholipase C-beta activity. J Recept Signal Transduct Res 2009; 29:52-62. [PMID: 19519170 DOI: 10.1080/10799890902729449] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Phospholipase C-beta (PLC-beta) isozymes are key effectors in G protein-coupled signaling pathways. Previously, we showed that PLC-beta1 and PLC-beta3 bound immobilized PIP(3). In this study, PIP(3) was found to potentiate Ca(2+)-stimulated PLC-beta activities using an in vitro reconstitution assay. LY294002, a specific PI 3-kinase inhibitor, significantly inhibited 10 min of agonist-stimulated total IP accumulation. Both LY294002 and wortmannin inhibited 90 sec of agonist-stimulated IP(3) accumulation in intact cells. Moreover, transfected p110CAAX, a constitutively activated PI 3-kinase catalytic subunit, increased 90 sec of oxytocin-stimulated IP(3) accumulation. Receptor-ligand binding assays indicated that LY294002 did not affect G protein-coupled receptors directly, suggesting a physiological role for PIP(3) in directly potentiating PLC-beta activity. When coexpressed with p110CAAX, fluorescence-tagged PLC-beta3 was increasingly localized to the plasma membrane. Additional observations suggest that the PH domain of PLC-beta is not important for p110CAAX-induced membrane association.
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Affiliation(s)
- Yong Zhang
- Department of Pharmaceutical Sciences, Oregon State University, Corvallis, OR 97331, USA
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42
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Litosch I, Pujari R, Lee SJ. Phosphatidic acid regulates signal output by G protein coupled receptors through direct interaction with phospholipase C-β1. Cell Signal 2009; 21:1379-84. [DOI: 10.1016/j.cellsig.2009.04.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2009] [Accepted: 04/27/2009] [Indexed: 12/25/2022]
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43
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Xiao W, Hong H, Kawakami Y, Kato Y, Wu D, Yasudo H, Kimura A, Kubagawa H, Bertoli LF, Davis RS, Chau LA, Madrenas J, Hsia CC, Xenocostas A, Kipps TJ, Hennighausen L, Iwama A, Nakauchi H, Kawakami T. Tumor suppression by phospholipase C-beta3 via SHP-1-mediated dephosphorylation of Stat5. Cancer Cell 2009; 16:161-71. [PMID: 19647226 PMCID: PMC2744338 DOI: 10.1016/j.ccr.2009.05.018] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/24/2008] [Revised: 03/20/2009] [Accepted: 05/28/2009] [Indexed: 01/22/2023]
Abstract
Given its catalytic activity to generate diacylglycerol and inositol 1,4,5-trisphosphate, phospholipase C (PLC) is implicated in promoting cell growth. However, we found that PLC-beta3-deficient mice develop myeloproliferative disease, lymphoma, and other tumors. The mutant mice have increased numbers of hematopoietic stem cells with increased proliferative, survival, and myeloid-differentiative abilities. These properties are dependent on Stat5 and can be antagonized by the protein phosphatase SHP-1. Stat5-dependent cooperative transformation by active c-Myc and PLC-beta3 deficiency was suggested in mouse lymphomas in PLC-beta3(-/-) and in Emicro-myc;PLC-beta3(+/-) mice and human Burkitt's lymphoma cells. The same mechanism for malignant transformation seems to be operative in other human lymphoid and myeloid malignancies. Thus, PLC-beta3 is likely a tumor suppressor.
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Affiliation(s)
- Wenbin Xiao
- Division of Cell Biology, La Jolla Institute for Allergy and Immunology, La Jolla, CA, 92037, USA
| | - Hong Hong
- Division of Cell Biology, La Jolla Institute for Allergy and Immunology, La Jolla, CA, 92037, USA
| | - Yuko Kawakami
- Division of Cell Biology, La Jolla Institute for Allergy and Immunology, La Jolla, CA, 92037, USA
| | - Yuko Kato
- Department of Cellular and Molecular Medicine, Graduate School of Medicine, Chiba University, Chiba 260-8670, Japan
| | - Dianqing Wu
- Program for Vascular Biology and Therapeutics and Department of Pharmacology, Yale University School of Medicine, New Haven, CT, 06520, USA
| | - Hiroki Yasudo
- Division of Cell Biology, La Jolla Institute for Allergy and Immunology, La Jolla, CA, 92037, USA
| | - Akiko Kimura
- Laboratory of Genetics and Physiology, National Institutes of Health/NIDDK, Bethesda, MD 20892, USA
| | - Hiromi Kubagawa
- Department of Pathology, University of Alabama, Birmingham, AL, 35294, USA
| | - Luigi F. Bertoli
- Department of Medicine, University of Alabama, Birmingham, AL, 35294, USA
| | | | - Luan A. Chau
- Department of Microbiology and Immunology, University of Western Ontario, London, ON, N6A 5K8, Canada
| | - Joaquin Madrenas
- Department of Microbiology and Immunology, University of Western Ontario, London, ON, N6A 5K8, Canada
| | - Cyrus C. Hsia
- Department of Medicine, University of Western Ontario, London, ON, N6A4G5, Canada
| | - Anargyros Xenocostas
- Department of Medicine, University of Western Ontario, London, ON, N6A4G5, Canada
| | - Thomas J. Kipps
- Department of Internal Medicine, University of California at San Diego, La Jolla, CA, 92093, USA
| | - Lothar Hennighausen
- Laboratory of Genetics and Physiology, National Institutes of Health/NIDDK, Bethesda, MD 20892, USA
| | - Atsushi Iwama
- Department of Cellular and Molecular Medicine, Graduate School of Medicine, Chiba University, Chiba 260-8670, Japan
| | - Hiromitsu Nakauchi
- Laboratory of Stem Cell Therapy, Center of Experimental Medicine, Institute of Medical Science, University of Tokyo, Tokyo 108-8639, Japan
| | - Toshiaki Kawakami
- Division of Cell Biology, La Jolla Institute for Allergy and Immunology, La Jolla, CA, 92037, USA
- Correspondence: Toshiaki Kawakami, M.D., Ph.D., Division of Cell Biology, La Jolla Institute for Allergy and Immunology, 9420 Athena Circle, La Jolla, California 92037, USA Tel: (858) 752-6814; Fax: (858) 752-6986;
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O'Carroll SJ, Mitchell MD, Faenza I, Cocco L, Gilmour RS. Nuclear PLCbeta1 is required for 3T3-L1 adipocyte differentiation and regulates expression of the cyclin D3-cdk4 complex. Cell Signal 2009; 21:926-35. [PMID: 19385066 DOI: 10.1016/j.cellsig.2009.02.002] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
A phosphoinositide signalling cycle is present in the nucleus, independent of that which occurs at the plasma membrane. The key enzyme involved in this cycle is phospholipase (PLC) beta1. This nuclear cycle has been shown to be involved in both cell proliferation and differentiation. Here, we report that nuclear PLCbeta1 activity is upregulated during differentiation of 3T3-L1 adipocytes. During differentiation there are two phases of PLCbeta1 activity; the first occurs within 5 min of treatment with differentiation media, does not require new PLCbeta1 to enter the nucleus and is regulated by pERK and PKC alpha while the second phase occurs from day 2 of differentiation, requires new PLCbeta1 protein to enter the nucleus and is independent of regulation by pERK and PKC alpha. Over-expression with the PLC mutants, Deltamk (which lacks the ERK phosphorylation site) and M2B (which lacks the nuclear localisation sequence), revealed that both phases of PLCbeta1 activity are required for terminal differentiation to occur. Inhibition of PLCbeta1 activity prevents the upregulation of cyclinD3 and cdk4 protein, suggesting that PLCbeta1 plays a role in the control of the cell cycle during differentiation. These results indicate nuclear PLCbeta1 as a key regulator of adipocyte differentiation.
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45
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Aziziyeh AI, Li TT, Pape C, Pampillo M, Chidiac P, Possmayer F, Babwah AV, Bhattacharya M. Dual regulation of lysophosphatidic acid (LPA1) receptor signalling by Ral and GRK. Cell Signal 2009; 21:1207-17. [PMID: 19306925 DOI: 10.1016/j.cellsig.2009.03.011] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2009] [Revised: 02/15/2009] [Accepted: 03/12/2009] [Indexed: 11/29/2022]
Abstract
Lysophosphatidic acid (LPA) is a major constituent of blood and is involved in a variety of physiological and pathophysiological processes. LPA signals via the ubiquitously expressed G protein-coupled receptors (GPCRs), LPA(1) and LPA(2) that are specific for LPA. However, in large, the molecular mechanisms that regulate the signalling of these receptors are unknown. We show that the small GTPase RalA associates with both LPA(1) and LPA(2) in human embryonic kidney (HEK 293) cells and that stimulation of LPA(1) receptors with LPA triggers the activation of RalA. While RalA was not found to play a role in the endocytosis of LPA receptors, we reveal that LPA(1) receptor stimulation promoted Ral-dependent phospholipase C activity. Furthermore, we found that GRK2 is required for the desensitization of LPA(1) and LPA(2) and have identified a novel interaction between RalA and GRK2, which is promoted by LPA(1) receptor activity. Taken together, these results establish RalA and GRK2 as key regulators of LPA receptor signalling and demonstrate for the first time that LPA(1) activity facilitates the formation of a novel protein complex between these two proteins.
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Affiliation(s)
- Adel I Aziziyeh
- Department of Physiology and Pharmacology, The University of Western Ontario, London, Ontario, Canada
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46
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Adjobo-Hermans MJW, Goedhart J, Gadella TWJ. Regulation of PLCβ1a membrane anchoring by its substrate phosphatidylinositol (4,5)-bisphosphate. J Cell Sci 2008; 121:3770-7. [DOI: 10.1242/jcs.029785] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Basic knowledge as to the subcellular location and dynamics of PLCβ isozymes is scant. Here, we report on the subcellular location of GFP-PLCβ1a and the use of total internal reflection fluorescence (TIRF) microscopy to examine the dynamics of GFP-PLCβ1a at the plasma membrane upon stimulation of Gq-coupled receptors. Using this technique, we observed PLCβ1a dissociation from the plasma membrane upon addition of agonist. An increase in intracellular calcium and a decrease in PtdIns(4,5)P2 both coincided with a translocation of PLCβ1a from the plasma membrane into the cytosol. In order to differentiate between calcium and PtdIns(4,5)P2, rapamycin-induced heterodimerization of FRB and FKBP12 fused to 5-phosphatase IV was used to instantaneously convert PtdIns(4,5)P2 into PtdIns(4)P. Addition of rapamycin caused PLCβ1a to dissociate from the plasma membrane, indicating that removal of PtdIns(4,5)P2 is sufficient to cause translocation of PLCβ1a from the plasma membrane. In conclusion, PLCβ1a localization is regulated by its own substrate.
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Affiliation(s)
- Merel J. W. Adjobo-Hermans
- Swammerdam Institute for Life Sciences, Section of Molecular Cytology, Centre for Advanced Microscopy, University of Amsterdam, Kruislaan 316, NL-1098 SM, Amsterdam, The Netherlands
| | - Joachim Goedhart
- Swammerdam Institute for Life Sciences, Section of Molecular Cytology, Centre for Advanced Microscopy, University of Amsterdam, Kruislaan 316, NL-1098 SM, Amsterdam, The Netherlands
| | - Theodorus W. J. Gadella
- Swammerdam Institute for Life Sciences, Section of Molecular Cytology, Centre for Advanced Microscopy, University of Amsterdam, Kruislaan 316, NL-1098 SM, Amsterdam, The Netherlands
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47
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Zhou Y, Sondek J, Harden TK. Activation of human phospholipase C-eta2 by Gbetagamma. Biochemistry 2008; 47:4410-7. [PMID: 18361507 DOI: 10.1021/bi800044n] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Phospholipase C-eta2 (PLC-eta2) was recently identified as a novel broadly expressed phosphoinositide-hydrolyzing isozyme [Zhou, Y., et al. (2005) Biochem. J. 391, 667-676; Nakahara, M., et al. (2005) J. Biol. Chem. 280, 29128-29134]. In this study, we investigated the direct regulation of PLC-eta2 by Gbetagamma subunits of heterotrimeric G proteins. Coexpression of PLC-eta2 with Gbeta 1gamma 2, as well as with certain other Gbetagamma dimers, in COS-7 cells resulted in increases in inositol phosphate accumulation. Gbeta 1gamma 2-dependent increases in phosphoinositide hydrolysis also were observed with a truncation mutant of PLC-eta2 that lacks the long alternatively spliced carboxy-terminal domain of the isozyme. To begin to define the enzymatic properties of PLC-eta2 and its potential direct activation by Gbetagamma, a construct of PLC-eta2 encompassing the canonical domains conserved in all PLCs (PH domain through C2 domain) was purified to homogeneity after expression from a baculovirus in insect cells. Enzyme activity of purified PLC-eta2 was quantified after reconstitution with PtdIns(4,5)P 2-containing phospholipid vesicles, and values for K m (14.4 microM) and V max [12.6 micromol min (-1) (mg of protein) (-1)] were similar to activities previously observed with purified PLC-beta or PLC-epsilon isozymes. Moreover, purified Gbeta 1gamma 2 stimulated the activity of purified PLC-eta2 in a concentration-dependent manner similar to that observed with purified PLC-beta2. Activation was dependent on the presence of free Gbeta 1gamma 2 since its sequestration in the presence of Galpha i1 or GRK2-ct reversed Gbeta 1gamma 2-promoted activation. The PH domain of PLC-eta2 is not required for Gbeta 1gamma 2-mediated regulation since a purified fragment encompassing the EF-hand through C2 domains but lacking the PH domain nonetheless was activated by Gbeta 1gamma 2. Taken together, these studies illustrate that PLC-eta2 is a direct downstream effector of Gbetagamma and, therefore, of receptor-activated heterotrimeric G proteins.
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Affiliation(s)
- Yixing Zhou
- Department of Pharmacology, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599, USA
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48
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Roztocil E, Nicholl SM, Davies MG. Sphingosine-1-phosphate-induced oxygen free radical generation in smooth muscle cell migration requires Galpha12/13 protein-mediated phospholipase C activation. J Vasc Surg 2008; 46:1253-1259. [PMID: 18155002 DOI: 10.1016/j.jvs.2007.08.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2007] [Revised: 07/28/2007] [Accepted: 08/05/2007] [Indexed: 10/22/2022]
Abstract
BACKGROUND Sphingosine-1-phosphate (S-1-P) is a bioactive sphingolipid that stimulates the migration of vascular smooth muscle cell (VSMC) through G-protein coupled receptors; it has been shown to activate reduced nicotinamide dinucleotide phosphate hydrogen (NAD[P]H) oxidase. The role of phospholipase C (PLC) in oxygen free radical generation, and the regulation of VSMC migration in response to S-1-P, are poorly understood. METHODS Rat arterial VSMC were cultured in vitro. Oxygen free radical generation was measured by fluorescent redox indicator assays in response to S-1-P (0.1microM) in the presence and absence of the active PLC inhibitor (U73122; U7, 10nM) or its inactive analog U73343 (InactiveU7, 10nM). Activation of PLC was assessed by immunoprecipitation and Western blotting for the phosphorylated isozymes (beta and gamma). Small interfering (si) RNA to the G-proteins Galphai, Galphaq, and Galpha12/13 was used to downregulate specific proteins. Statistics were by one-way analysis of variance (n = 6). RESULTS S-1-P induced time-dependent activation of PLC-beta and PLC-gamma; PLC-beta but not PLC-gamma activation was blocked by U7 but not by InactiveU7. PLC-beta activation was Galphai-independent (not blocked by pertussis toxin, a Galphai inhibitor, or Galphai2 and Galphai3 siRNA) and Galphaq-independent (not blocked by glycoprotein [GP] 2A, a Galphaq inhibitor, or Galphaq siRNA). PLC-beta activation and cell migration was blocked by siRNA to Galpha12/13. Oxygen free radical generation induced by S-1-P, as measured by dihydroethidium staining, was significantly inhibited by U7 but not by InactiveU7. Inhibition of oxygen free radicals with the inhibitor diphenyleneiodonium resulted in decreased cell migration to S-1-P. VSMC mitogen-activated protein kinase activation and VSMC migration in response to S-1-P was inhibited by PLC- inhibition. CONCLUSION S-1-P induces oxygen free radical generation through a Galpha12/13, PLC-beta-mediated mechanism that facilitates VSMC migration. To our knowledge, this is the first description of PLC-mediated oxygen free radical generation as a mediator of S-1-P VSMC migration and illustrates the need for the definition of cell signaling to allow targeted strategies in molecular therapeutics for restenosis.
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Affiliation(s)
- Eliza Roztocil
- Vascular Biology and Therapeutics Program, Department of Surgery, University of Rochester, Rochester, NY 14642, USA
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Echevarría-Machado I, Martínez-Estévez M, Muñoz-Sánchez JA, Loyola-Vargas VM, Hernández-Sotomayor SMT, De Los Santos-Briones C. Membrane-associated phosphoinositides-specific phospholipase C forms from Catharanthus roseus transformed roots. Mol Biotechnol 2007; 35:297-309. [PMID: 17652793 DOI: 10.1007/bf02686015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/1999] [Revised: 11/30/1999] [Accepted: 11/30/1999] [Indexed: 01/16/2023]
Abstract
We have previously reported that Catharanthus roseus transformed roots contain at least two phosphatidylinositol 4,5-bisphosphate-phospholipase C (PLC) activities, one soluble and the other membrane associated. Detergent, divalent cations, and neomycin differentially regulate these activities and pure protein is required for a greater understanding of the function and regulation of this enzyme. In this article we report a partia purification of membrane-associated PLC. We found that there are at least two forms of membraneassociated PLC in transformed roots of C. roseus. These forms were separated on the basis of their affinity for heparin. One form shows an affinity for heparin and elutes at approx 600 mM KCl. This form has a molecular mass of 67 kDa by size exclusion chromatography and Western blot analysis, whereas the other form does not bind to heparin and has a molecular mass of 57 kDa. Possible differential regulation of these forms during transformed root growth is discussed.
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Affiliation(s)
- Ileana Echevarría-Machado
- Unidad de Bioquímica y Biología Molecular de Plantas, Centro de Investigaciòn Científica de Yucatán A.C., Calle 43 No. 130, Chuburná de Hidalgo, C. P. 97200, Mérida, Yucatán, México
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Laroche G, Giguère PM, Dupré E, Dupuis G, Parent JL. The N-terminal coiled-coil domain of the cytohesin/ARNO family of guanine nucleotide exchange factors interacts with Galphaq. Mol Cell Biochem 2007; 306:141-52. [PMID: 17846866 DOI: 10.1007/s11010-007-9564-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2007] [Accepted: 07/12/2007] [Indexed: 01/06/2023]
Abstract
Cytohesins are guanine-nucleotide exchange factors (GEF) for the Arf family of GTPases. One member of the Arf family, ARF6, plays an active role in the intracellular trafficking of G protein-coupled receptors. We have previously reported that Galphaq signaling leads to the activation of ARF6, possibly through a direct interaction with cytohesin-2/ARNO. Here, we report that Galphaq can directly interact with cytohesin-1, another Arf-GEF of the ARNO/cytohesin family. Cytohesin-1 preferentially associated with a constitutively active mutant of Galphaq (Galphaq-Q209L) compared to wild-type Galphaq in HEK293 cells. Stimulation of TPbeta, a Galphaq-coupled receptor, to activate Galphaq resulted in the promotion of a protein complex between Galphaq and cytohesin-1. Confocal immunofluorescence microscopy revealed that wild-type Galphaq and cytohesin-1 co-localized in intracellular compartments and at or near the plasma membrane. In contrast, expression of Galphaq-Q209L induced a drastic increase in the localization of cytohesin-1 at the plasma membrane. Expression of a dominant-negative mutant of cytohesin-1 reduced by 40% the agonist-induced internalization of TPbeta, a process that we previously demonstrated to be dependent on Galphaq-mediated signaling and Arf6 activation. Using deletion mutants, we show that cytohesin-1 interacts with Galphaq through its N-terminal coiled-coil domain. Cytohesin-1 and cytohesin-2/ARNO mutants lacking the coiled-coil domain were unable to relay Galphaq-mediated activation of Arf6. This is the first report of an interaction between the coiled-coil domain of the cytohesin/ARNO family of Arf-GEFs and a member of the heterotrimeric G proteins.
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Affiliation(s)
- Geneviève Laroche
- Division of Rheumatology, Department of Medicine, Faculty of Medicine, Centre de Recherche Clinique Etienne-Lebel, University of Sherbrooke, 3001, 12th Avenue North, J1H 5N4 Fleurimont, Sherbrooke, QC, Canada
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