1
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Li K, Ran B, Wang Y, Liu L, Li W. PLCγ2 impacts microglia-related effectors revealing variants and pathways important in Alzheimer’s disease. Front Cell Dev Biol 2022; 10:999061. [PMID: 36147734 PMCID: PMC9485805 DOI: 10.3389/fcell.2022.999061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Accepted: 08/15/2022] [Indexed: 11/30/2022] Open
Abstract
Alzheimer’s disease (AD) is an irreversible neurodegenerative disease mainly characterized by memory loss and cognitive decline. The etiology of AD is complex and remains incompletely understood. In recent years, genome-wide association studies (GWAS) have increasingly highlighted the central role of microglia in AD pathology. As a trans-membrane receptor specifically present on the microglia in the central nervous system, phosphatidylinositol-specific phospholipase C gamma 2 (PLCγ2) plays an important role in neuroinflammation. GWAS data and corresponding pathological research have explored the effects of PLCG2 variants on amyloid burden and tau pathologies that underline AD. The link between PLCγ2 and other AD-related effectors in human and mouse microglia has also been established, placing PLCγ2 downstream of the triggering receptor expressed on myeloid cells 2 (TREM2), toll-like receptor 4 (TLR4), Bruton’s tyrosine kinase (BTK), and colony-stimulating factor 1 receptor (CSF1R). Because the research on PLCγ2’s role in AD is still in its early stages, few articles have been published, therefore in this paper, we integrate the relevant research published to date, review the structural features, expression patterns, and related pathways of PLCγ2, and summarize the recent studies on important PLCG2 variants related to AD. Furthermore, the possibility and challenge of using PLCγ2 to develop therapeutic drugs for AD are also discussed.
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2
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Arthur R, Wathen A, Lemm EA, Stevenson FK, Forconi F, Linley AJ, Steele AJ, Packham G, Valle-Argos B. BTK-independent regulation of calcium signalling downstream of the B-cell receptor in malignant B-cells. Cell Signal 2022; 96:110358. [PMID: 35597428 DOI: 10.1016/j.cellsig.2022.110358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 05/13/2022] [Accepted: 05/14/2022] [Indexed: 11/20/2022]
Abstract
BTK inhibitors (BTKi) have dramatically improved outcomes for patients with chronic lymphocytic leukaemia (CLL) and some forms of B-cell lymphoma. However, new strategies are needed to enhance responses. Here we have performed a detailed analysis of the effects of BTKi on B-cell receptor (BCR)-induced signalling using primary malignant cells from CLL patients and B-lymphoma cell lines. Although BTK is considered as a key activator of PLCγ2, BTKi (ibrutinib and acalabrutinib) failed to fully inhibit calcium responses in CLL samples with strong BCR signalling capacity. This BTKi-resistant calcium signalling was sufficient to engage downstream calcium-dependent transcription and suppress CLL cell apoptosis and was entirely independent of BTK and not just its kinase activity as similar results were obtained using a BTK-degrading PROTAC. BTK-independent calcium signalling was also observed in two B-lymphoma cell lines where BTKi had little effect on the initial phase of the calcium response but did accelerate the subsequent decline in intracellular calcium. In contrast to BTKi, calcium responses were completely blocked by inhibition of SYK in CLL and lymphoma cells. Engagement of BTK-independent calcium responses was associated with BTK-independent phosphorylation of PLCγ2 on Y753 and Y759 in both CLL and lymphoma cells. Moreover, in CLL samples, inhibition of RAC, which can mediate BTK-independent activation of PLCγ2, cooperated with ibrutinib to suppress calcium responses. BTK-independent calcium signalling may limit the effectiveness of BTKi to suppress BCR signalling responses and our results suggest inhibition of SYK or dual inhibition of BTK and RAC as alternative strategies to strengthen pathway blockade.
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Affiliation(s)
- Rachael Arthur
- Cancer Sciences, Faculty of Medicine, University of Southampton, Southampton SO16 6YD, United Kingdom
| | - Alexander Wathen
- Cancer Sciences, Faculty of Medicine, University of Southampton, Southampton SO16 6YD, United Kingdom
| | - Elizabeth A Lemm
- Cancer Sciences, Faculty of Medicine, University of Southampton, Southampton SO16 6YD, United Kingdom
| | - Freda K Stevenson
- Cancer Sciences, Faculty of Medicine, University of Southampton, Southampton SO16 6YD, United Kingdom
| | - Francesco Forconi
- Cancer Sciences, Faculty of Medicine, University of Southampton, Southampton SO16 6YD, United Kingdom
| | - Adam J Linley
- Department of Molecular Physiology and Cell Signalling, University of Liverpool, Institute of Systems, Molecular and Integrative Biology, 5(th) Floor Nuffield Building, Crown Street, Liverpool L69 3BX, United Kingdom
| | - Andrew J Steele
- Cancer Sciences, Faculty of Medicine, University of Southampton, Southampton SO16 6YD, United Kingdom
| | - Graham Packham
- Cancer Sciences, Faculty of Medicine, University of Southampton, Southampton SO16 6YD, United Kingdom.
| | - Beatriz Valle-Argos
- Cancer Sciences, Faculty of Medicine, University of Southampton, Southampton SO16 6YD, United Kingdom
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3
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Le Huray KIP, Bunney TD, Pinotsis N, Kalli AC, Katan M. Characterization of the membrane interactions of phospholipase Cγ reveals key features of the active enzyme. SCIENCE ADVANCES 2022; 8:eabp9688. [PMID: 35749497 PMCID: PMC9232102 DOI: 10.1126/sciadv.abp9688] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Accepted: 05/06/2022] [Indexed: 06/15/2023]
Abstract
PLCγ enzymes are autoinhibited in resting cells and form key components of intracellular signaling that are also linked to disease development. Insights into physiological and aberrant activation of PLCγ require understanding of an active, membrane-bound form, which can hydrolyze inositol-lipid substrates. Here, we demonstrate that PLCγ1 cannot bind membranes unless the autoinhibition is disrupted. Through extensive molecular dynamics simulations and experimental evidence, we characterize membrane binding by the catalytic core domains and reveal previously unknown sites of lipid interaction. The identified sites act in synergy, overlap with autoinhibitory interfaces, and are shown to be critical for the phospholipase activity in cells. This work provides direct evidence that PLCγ1 is inhibited through obstruction of its membrane-binding surfaces by the regulatory region and that activation must shift PLCγ1 to a conformation competent for membrane binding. Knowledge of the critical sites of membrane interaction extends the mechanistic framework for activation, dysregulation, and therapeutic intervention.
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Affiliation(s)
- Kyle I. P. Le Huray
- Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT UK
- Leeds Institute of Cardiovascular and Metabolic Medicine, School of Medicine, University of Leeds, Leeds LS2 9JT, UK
| | - Tom D. Bunney
- Institute of Structural and Molecular Biology, Division of Biosciences, University College London, Gower St., London WC1E 6BT, UK
| | - Nikos Pinotsis
- Institute of Structural and Molecular Biology, Birkbeck College, London, WC1E 6BT, UK
| | - Antreas C. Kalli
- Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
- Leeds Institute of Cardiovascular and Metabolic Medicine, School of Medicine, University of Leeds, Leeds LS2 9JT, UK
| | - Matilda Katan
- Institute of Structural and Molecular Biology, Division of Biosciences, University College London, Gower St., London WC1E 6BT, UK
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4
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Jackson JT, Mulazzani E, Nutt SL, Masters SL. The role of PLCγ2 in immunological disorders, cancer, and neurodegeneration. J Biol Chem 2021; 297:100905. [PMID: 34157287 PMCID: PMC8318911 DOI: 10.1016/j.jbc.2021.100905] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 06/15/2021] [Accepted: 06/18/2021] [Indexed: 02/06/2023] Open
Abstract
Phosphatidylinositol-specific phospholipase Cγ2 (PLCγ2) is a critical signaling molecule activated downstream from a variety of cell surface receptors that contain an intracellular immunoreceptor tyrosine-based activation motif. These receptors recruit kinases such as Syk, BTK, and BLNK to phosphorylate and activate PLCγ2, which then generates 1D-myo-inositol 1,4,5-trisphosphate and diacylglycerol. These well-known second messengers are required for diverse membrane functionality including cellular proliferation, endocytosis, and calcium flux. As a result, PLCγ2 dysfunction is associated with a variety of diseases including cancer, neurodegeneration, and immune disorders. The diverse pathologies associated with PLCγ2 are exemplified by distinct genetic variants. Inherited mutations at this locus cause PLCγ2-associated antibody deficiency and immune dysregulation, in some cases with autoinflammation. Acquired mutations at this locus, which often arise as a result of BTK inhibition to treat chronic lymphocytic leukemia, result in constitutive downstream signaling and lymphocyte proliferation. Finally, a third group of PLCγ2 variants actually has a protective effect in a variety of neurodegenerative disorders, presumably by increased uptake and degradation of deleterious neurological aggregates. Therefore, manipulating PLCγ2 activity either up or down could have therapeutic benefit; however, we require a better understanding of the signaling pathways propagated by these variants before such clinical utility can be realized. Here, we review the signaling roles of PLCγ2 in hematopoietic cells to help understand the effect of mutations driving immune disorders and cancer and extrapolate from this to roles which may relate to protection against neurodegeneration.
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Affiliation(s)
- Jacob T Jackson
- Immunology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia; Inflammation Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
| | - Elisabeth Mulazzani
- Inflammation Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia; Department of Medical Biology, University of Melbourne, Parkville, Victoria, Australia
| | - Stephen L Nutt
- Immunology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia; Department of Medical Biology, University of Melbourne, Parkville, Victoria, Australia
| | - Seth L Masters
- Inflammation Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia; Department of Medical Biology, University of Melbourne, Parkville, Victoria, Australia; Immunology Laboratory, Guangzhou Institute of Paediatrics, Guangzhou Women and Children's Medical Centre, Guangzhou, Guangdong, China.
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5
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Hajicek N, Keith NC, Siraliev-Perez E, Temple BRS, Huang W, Zhang Q, Harden TK, Sondek J. Structural basis for the activation of PLC-γ isozymes by phosphorylation and cancer-associated mutations. eLife 2019; 8:e51700. [PMID: 31889510 PMCID: PMC7004563 DOI: 10.7554/elife.51700] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Accepted: 12/30/2019] [Indexed: 12/14/2022] Open
Abstract
Direct activation of the human phospholipase C-γ isozymes (PLC-γ1, -γ2) by tyrosine phosphorylation is fundamental to the control of diverse biological processes, including chemotaxis, platelet aggregation, and adaptive immunity. In turn, aberrant activation of PLC-γ1 and PLC-γ2 is implicated in inflammation, autoimmunity, and cancer. Although structures of isolated domains from PLC-γ isozymes are available, these structures are insufficient to define how release of basal autoinhibition is coupled to phosphorylation-dependent enzyme activation. Here, we describe the first high-resolution structure of a full-length PLC-γ isozyme and use it to underpin a detailed model of their membrane-dependent regulation. Notably, an interlinked set of regulatory domains integrates basal autoinhibition, tyrosine kinase engagement, and additional scaffolding functions with the phosphorylation-dependent, allosteric control of phospholipase activation. The model also explains why mutant forms of the PLC-γ isozymes found in several cancers have a wide spectrum of activities, and highlights how these activities are tuned during disease.
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Affiliation(s)
- Nicole Hajicek
- Department of PharmacologyThe University of North Carolina at Chapel HillChapel HillUnited States
| | - Nicholas C Keith
- Department of PharmacologyThe University of North Carolina at Chapel HillChapel HillUnited States
| | - Edhriz Siraliev-Perez
- Department of Biochemistry and BiophysicsThe University of North Carolina at Chapel HillChapel HillUnited States
| | - Brenda RS Temple
- Department of Biochemistry and BiophysicsThe University of North Carolina at Chapel HillChapel HillUnited States
- R L Juliano Structural Bioinformatics Core FacilityThe University of North Carolina at Chapel HillChapel HillUnited States
| | - Weigang Huang
- Division of Chemical Biology and Medicinal ChemistryThe University of North Carolina at Chapel HillChapel HillUnited States
| | - Qisheng Zhang
- Department of PharmacologyThe University of North Carolina at Chapel HillChapel HillUnited States
- Division of Chemical Biology and Medicinal ChemistryThe University of North Carolina at Chapel HillChapel HillUnited States
- Lineberger Comprehensive Cancer CenterThe University of North Carolina at Chapel HillChapel HillUnited States
| | - T Kendall Harden
- Department of PharmacologyThe University of North Carolina at Chapel HillChapel HillUnited States
| | - John Sondek
- Department of PharmacologyThe University of North Carolina at Chapel HillChapel HillUnited States
- Department of Biochemistry and BiophysicsThe University of North Carolina at Chapel HillChapel HillUnited States
- Lineberger Comprehensive Cancer CenterThe University of North Carolina at Chapel HillChapel HillUnited States
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6
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Conway OJ, Carrasquillo MM, Wang X, Bredenberg JM, Reddy JS, Strickland SL, Younkin CS, Burgess JD, Allen M, Lincoln SJ, Nguyen T, Malphrus KG, Soto AI, Walton RL, Boeve BF, Petersen RC, Lucas JA, Ferman TJ, Cheshire WP, van Gerpen JA, Uitti RJ, Wszolek ZK, Ross OA, Dickson DW, Graff-Radford NR, Ertekin-Taner N. ABI3 and PLCG2 missense variants as risk factors for neurodegenerative diseases in Caucasians and African Americans. Mol Neurodegener 2018; 13:53. [PMID: 30326945 PMCID: PMC6190665 DOI: 10.1186/s13024-018-0289-x] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Accepted: 10/04/2018] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND Rare coding variants ABI3_rs616338-T and PLCG2_rs72824905-G were identified as risk or protective factors, respectively, for Alzheimer's disease (AD). METHODS We tested the association of these variants with five neurodegenerative diseases in Caucasian case-control cohorts: 2742 AD, 231 progressive supranuclear palsy (PSP), 838 Parkinson's disease (PD), 306 dementia with Lewy bodies (DLB) and 150 multiple system atrophy (MSA) vs. 3351 controls; and in an African-American AD case-control cohort (181 AD, 331 controls). 1479 AD and 1491 controls were non-overlapping with a prior report. RESULTS Using Fisher's exact test, there was significant association of both ABI3_rs616338-T (OR = 1.41, p = 0.044) and PLCG2_rs72824905-G (OR = 0.56, p = 0.008) with AD. These OR estimates were maintained in the non-overlapping replication AD-control analysis, albeit at reduced significance (ABI3_rs616338-T OR = 1.44, p = 0.12; PLCG2_rs72824905-G OR = 0.66, p = 0.19). None of the other cohorts showed significant associations that were concordant with those for AD, although the DLB cohort had suggestive findings (Fisher's test: ABI3_rs616338-T OR = 1.79, p = 0.097; PLCG2_rs72824905-G OR = 0.32, p = 0.124). PLCG2_rs72824905-G showed suggestive association with pathologically-confirmed MSA (OR = 2.39, p = 0.050) and PSP (OR = 1.97, p = 0.061), although in the opposite direction of that for AD. We assessed RNA sequencing data from 238 temporal cortex (TCX) and 224 cerebellum (CER) samples from AD, PSP and control patients and identified co-expression networks, enriched in microglial genes and immune response GO terms, and which harbor PLCG2 and/or ABI3. These networks had higher expression in AD, but not in PSP TCX, compared to controls. This expression association did not survive adjustment for brain cell type population changes. CONCLUSIONS We validated the associations previously reported with ABI3_rs616338-T and PLCG2_rs72824905-G in a Caucasian AD case-control cohort, and observed a similar direction of effect in DLB. Conversely, PLCG2_rs72824905-G showed suggestive associations with PSP and MSA in the opposite direction. We identified microglial gene-enriched co-expression networks with significantly higher levels in AD TCX, but not in PSP, a primary tauopathy. This co-expression network association appears to be driven by microglial cell population changes in a brain region affected by AD pathology. Although these findings require replication in larger cohorts, they suggest distinct effects of the microglial genes, ABI3 and PLCG2 in neurodegenerative diseases that harbor significant vs. low/no amyloid ß pathology.
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Affiliation(s)
- Olivia J Conway
- Department of Neuroscience, Mayo Clinic Florida, Jacksonville, FL, 32224, USA
| | | | - Xue Wang
- Department of Neuroscience, Mayo Clinic Florida, Jacksonville, FL, 32224, USA
| | - Jenny M Bredenberg
- Department of Neuroscience, Mayo Clinic Florida, Jacksonville, FL, 32224, USA
| | - Joseph S Reddy
- Department of Health Sciences Research, Mayo Clinic Florida, Jacksonville, FL, 32224, USA
| | | | - Curtis S Younkin
- Department of Neuroscience, Mayo Clinic Florida, Jacksonville, FL, 32224, USA
| | - Jeremy D Burgess
- Department of Neuroscience, Mayo Clinic Florida, Jacksonville, FL, 32224, USA
| | - Mariet Allen
- Department of Neuroscience, Mayo Clinic Florida, Jacksonville, FL, 32224, USA
| | - Sarah J Lincoln
- Department of Neuroscience, Mayo Clinic Florida, Jacksonville, FL, 32224, USA
| | - Thuy Nguyen
- Department of Neuroscience, Mayo Clinic Florida, Jacksonville, FL, 32224, USA
| | - Kimberly G Malphrus
- Department of Neuroscience, Mayo Clinic Florida, Jacksonville, FL, 32224, USA
| | - Alexandra I Soto
- Department of Neuroscience, Mayo Clinic Florida, Jacksonville, FL, 32224, USA
| | - Ronald L Walton
- Department of Neuroscience, Mayo Clinic Florida, Jacksonville, FL, 32224, USA
| | - Bradley F Boeve
- Department of Neurology, Mayo Clinic Minnesota, Rochester, MN, 55905, USA
| | - Ronald C Petersen
- Department of Neurology, Mayo Clinic Minnesota, Rochester, MN, 55905, USA
| | - John A Lucas
- Department of Psychiatry and Psychology, Mayo Clinic Florida, Jacksonville, FL, 32224, USA
| | - Tanis J Ferman
- Department of Psychiatry and Psychology, Mayo Clinic Florida, Jacksonville, FL, 32224, USA
| | - William P Cheshire
- Department of Neurology, Mayo Clinic Florida, Jacksonville, FL, 32224, USA
| | - Jay A van Gerpen
- Department of Neurology, Mayo Clinic Florida, Jacksonville, FL, 32224, USA
| | - Ryan J Uitti
- Department of Neurology, Mayo Clinic Florida, Jacksonville, FL, 32224, USA
| | - Zbigniew K Wszolek
- Department of Neurology, Mayo Clinic Florida, Jacksonville, FL, 32224, USA
| | - Owen A Ross
- Department of Neuroscience, Mayo Clinic Florida, Jacksonville, FL, 32224, USA
| | - Dennis W Dickson
- Department of Neuroscience, Mayo Clinic Florida, Jacksonville, FL, 32224, USA
| | | | - Nilüfer Ertekin-Taner
- Department of Neuroscience, Mayo Clinic Florida, Jacksonville, FL, 32224, USA. .,Department of Neurology, Mayo Clinic Florida, Jacksonville, FL, 32224, USA.
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7
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Walliser C, Wist M, Hermkes E, Zhou Y, Schade A, Haas J, Deinzer J, Désiré L, Li SSC, Stilgenbauer S, Milner JD, Gierschik P. Functional characterization of phospholipase C-γ 2 mutant protein causing both somatic ibrutinib resistance and a germline monogenic autoinflammatory disorder. Oncotarget 2018; 9:34357-34378. [PMID: 30344948 PMCID: PMC6188132 DOI: 10.18632/oncotarget.26173] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Accepted: 09/08/2018] [Indexed: 12/17/2022] Open
Abstract
Depending on its occurrence in the germline or somatic context, a single point mutation, S707Y, of phospholipase C-γ2 (PLCγ2) gives rise to two distinct human disease states: acquired resistance of chronic lymphocytic leukemia cells (CLL) to inhibitors of Brutons´s tyrosine kinase (Btk) and dominantly inherited autoinflammation and PLCγ2-associated antibody deficiency and immune dysregulation, APLAID, respectively. The functional relationships of the PLCγ2S707Y mutation to other PLCG2 mutations causing (i) Btk inhibitor resistance of CLL cells and (ii) the APLAID-related human disease PLCγ2-associated antibody deficiency and immune dysregulation, PLAID, revealing different clinical characteristics including cold-induced urticaria, respectively, are currently incompletely understood. Here, we show that PLCγ2S707 point mutants displayed much higher activities at 37° C than the CLL Btk inhibitor resistance mutants R665W and L845F and the two PLAID mutants, PLCγ2Δ19 and PLCγ2Δ20-22. Combinations of CLL Btk inhibitor resistance mutations synergized to enhance PLCγ2 activity, with distinct functional consequences for different temporal orders of the individual mutations. Enhanced activity of PLCγ2S707Y was not observed in a cell-free system, suggesting that PLCγ2 activation in intact cells is dependent on regulatory rather than mutant-enzyme-inherent influences. Unlike the two PLAID mutants, PLCγ2S707Y was insensitive to activation by cooling and retained marked hyperresponsiveness to activated Rac upon cooling. In contrast to the PLAID mutants, which are insensitive to activation by endogenously expressed EGF receptors, the S707Y mutation markedly enhanced the stimulatory effect of EGF, explaining some of the pathophysiological discrepancies between immune cells of PLAID and APLAID patients in response to receptor-tyrosine-kinase activation.
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Affiliation(s)
- Claudia Walliser
- Institute of Pharmacology and Toxicology, Ulm University Medical Center, Ulm 89070, Germany
| | - Martin Wist
- Institute of Pharmacology and Toxicology, Ulm University Medical Center, Ulm 89070, Germany
| | - Elisabeth Hermkes
- Institute of Pharmacology and Toxicology, Ulm University Medical Center, Ulm 89070, Germany
| | - Yuan Zhou
- Institute of Pharmacology and Toxicology, Ulm University Medical Center, Ulm 89070, Germany
| | - Anja Schade
- Institute of Pharmacology and Toxicology, Ulm University Medical Center, Ulm 89070, Germany
| | - Jennifer Haas
- Institute of Pharmacology and Toxicology, Ulm University Medical Center, Ulm 89070, Germany
| | - Julia Deinzer
- Institute of Pharmacology and Toxicology, Ulm University Medical Center, Ulm 89070, Germany
| | | | - Shawn S C Li
- Department of Biochemistry and The Siebens-Drake Medical Research Institute, Schulich School of Medicine, University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Stephan Stilgenbauer
- Department of Internal Medicine III, Ulm University Medical Center, Ulm 89070, Germany
| | - Joshua D Milner
- Laboratory of Allergic Diseases, NIAID, NIH, Bethesda, MD 20892, USA
| | - Peter Gierschik
- Institute of Pharmacology and Toxicology, Ulm University Medical Center, Ulm 89070, Germany
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8
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Walliser C, Hermkes E, Schade A, Wiese S, Deinzer J, Zapatka M, Désiré L, Mertens D, Stilgenbauer S, Gierschik P. The Phospholipase Cγ2 Mutants R665W and L845F Identified in Ibrutinib-resistant Chronic Lymphocytic Leukemia Patients Are Hypersensitive to the Rho GTPase Rac2 Protein. J Biol Chem 2016; 291:22136-22148. [PMID: 27542411 PMCID: PMC5063995 DOI: 10.1074/jbc.m116.746842] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Revised: 08/18/2016] [Indexed: 12/29/2022] Open
Abstract
Mutations in the gene encoding phospholipase C-γ2 (PLCγ2) have been shown to be associated with resistance to targeted therapy of chronic lymphocytic leukemia (CLL) with the Bruton's tyrosine kinase inhibitor ibrutinib. The fact that two of these mutations, R665W and L845F, imparted upon PLCγ2 an ∼2-3-fold ibrutinib-insensitive increase in the concentration of cytosolic Ca2+ following ligation of the B cell antigen receptor (BCR) led to the assumption that the two mutants exhibit constitutively enhanced intrinsic activity. Here, we show that the two PLCγ2 mutants are strikingly hypersensitive to activation by Rac2 such that even wild-type Rac2 suffices to activate the mutant enzymes upon its introduction into intact cells. Enhanced "basal" activity of PLCγ2 in intact cells is shown using the pharmacologic Rac inhibitor EHT 1864 and the PLCγ2F897Q mutation mediating Rac resistance to be caused by Rac-stimulated rather than by constitutively enhanced PLCγ2 activity. We suggest that R665W and L845F be referred to as allomorphic rather than hypermorphic mutations of PLCG2 Rerouting of the transmembrane signals emanating from BCR and converging on PLCγ2 through Rac in ibrutinib-resistant CLL cells may provide novel drug treatment strategies to overcome ibrutinib resistance mediated by PLCG2 mutations or to prevent its development in ibrutinib-treated CLL patients.
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MESH Headings
- Adenine/analogs & derivatives
- Amino Acid Substitution
- Animals
- COS Cells
- Chlorocebus aethiops
- Drug Resistance, Neoplasm/drug effects
- Drug Resistance, Neoplasm/genetics
- Humans
- Leukemia, Lymphocytic, Chronic, B-Cell/drug therapy
- Leukemia, Lymphocytic, Chronic, B-Cell/enzymology
- Leukemia, Lymphocytic, Chronic, B-Cell/genetics
- Mutation, Missense
- Neoplasm Proteins/antagonists & inhibitors
- Neoplasm Proteins/genetics
- Neoplasm Proteins/metabolism
- Phospholipase C gamma/antagonists & inhibitors
- Phospholipase C gamma/genetics
- Phospholipase C gamma/metabolism
- Piperidines
- Pyrazoles/pharmacology
- Pyrimidines/pharmacology
- Pyrones/pharmacology
- Quinolines/pharmacology
- Receptors, Antigen, B-Cell/genetics
- Receptors, Antigen, B-Cell/metabolism
- Signal Transduction/drug effects
- Signal Transduction/genetics
- rac GTP-Binding Proteins/genetics
- rac GTP-Binding Proteins/metabolism
- RAC2 GTP-Binding Protein
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Affiliation(s)
| | | | - Anja Schade
- From the Institute of Pharmacology and Toxicology and
| | - Sebastian Wiese
- the Core Unit Mass Spectrometry and Proteomics, Medical Faculty, Ulm University, 89081 Ulm, Germany
| | - Julia Deinzer
- From the Institute of Pharmacology and Toxicology and
| | - Marc Zapatka
- the Division of Molecular Genetics, German Cancer Research Center (DKFZ), 69121 Heidelberg, Germany, and
| | - Laurent Désiré
- the Diaxonhit, 63-65 Boulevard Masséna, 75013 Paris, France
| | - Daniel Mertens
- Department of Internal Medicine III, Ulm University Medical Center, 89070 Ulm, Germany
| | - Stephan Stilgenbauer
- Department of Internal Medicine III, Ulm University Medical Center, 89070 Ulm, Germany
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9
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Cool-temperature-mediated activation of phospholipase C-γ2 in the human hereditary disease PLAID. Cell Signal 2016; 28:1237-1251. [PMID: 27196803 DOI: 10.1016/j.cellsig.2016.05.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2016] [Revised: 05/10/2016] [Accepted: 05/12/2016] [Indexed: 12/24/2022]
Abstract
Deletions in the gene encoding signal-transducing inositol phospholipid-specific phospholipase C-γ2 (PLCγ2) are associated with the novel human hereditary disease PLAID (PLCγ2-associated antibody deficiency and immune dysregulation). PLAID is characterized by a rather puzzling concurrence of augmented and diminished functions of the immune system, such as cold urticaria triggered by only minimal decreases in temperature, autoimmunity, and immunodeficiency. Understanding of the functional effects of the genomic alterations at the level of the affected enzyme, PLCγ2, is currently lacking. PLCγ2 is critically involved in coupling various cell surface receptors to regulation of important functions of immune cells such as mast cells, B cells, monocytes/macrophages, and neutrophils. PLCγ2 is unique by carrying three Src (SH) and one split pleckstrin homology domain (spPH) between the two catalytic subdomains (spPHn-SH2n-SH2c-SH3-spPHc). Prevailing evidence suggests that activation of PLCγ2 is primarily due to loss of SH-region-mediated autoinhibition and/or enhanced plasma membrane translocation. Here, we show that the two PLAID PLCγ2 mutants lacking portions of the SH region are strongly (>100-fold), rapidly, and reversibly activated by cooling by only a few degrees. We found that the mechanism(s) underlying PLCγ2 PLAID mutant activation by cool temperatures is distinct from a mere loss of SH-region-mediated autoinhibition and dependent on both the integrity and the pliability of the spPH domain. The results suggest a new mechanism of PLCγ activation with unique thermodynamic features and assign a novel regulatory role to its spPH domain. Involvement of this mechanism in other human disease states associated with cooling such as exertional asthma and certain acute coronary events appears an intriguing possibility.
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10
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Regulatory role of guanine nucleotide exchange factor (GEF) Dock180 phosphorylation on Tyr/Ser in mediation of gastric mucosal Rac1 activation in response to Helicobacter pylori and ghrelin. Inflammopharmacology 2015; 23:111-8. [PMID: 25957600 DOI: 10.1007/s10787-015-0235-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Accepted: 04/28/2015] [Indexed: 01/26/2023]
Abstract
A small GTPase, Rac1, is recognized as an important modulator of the inflammatory responses to bacterial lipopolysaccharide (LPS) by affecting the processes of phospholipase C activation. The activation of Rac1 involves the exchange of GDP for GTP and is catalyzed by the guanine nucleotide exchange factors (GEFs). Here, we report on the gastric mucosal GEF, Dock180, activation in response to H. pylori PS, and the hormone, ghrelin. We show that stimulation of gastric mucosal cells with the LPS leads to up-regulation in Dock180 phosphorylation on Tyr and Ser that is accompanied by a massive rise in Rac1-GTP level, while the effect of ghrelin, manifested by a drop in Dock180 phosphorylation on Ser, is associated with a decrease in Rac1-GTP formation. Furthermore, we demonstrate that phosphorylation on Tyr remains under the control of the Src family protein tyrosine kinases (SFK-PTKs), and is accompanied by Dock180 membrane translocation, while phosphorylation of the membrane-localized Dock180 on Ser represents the stimulatory contribution of protein kinase Cδ (PKCδ) to Dock180 activation. Moreover, we reveal that the interaction between Dock180 and PKCδ is dependent on Dock180 Tyr phosphorylation as well as the activity of PKCδ. Thus, our findings point to the involvement of PKCδ in the LPS-induced up-regulation of Dock180 activation, and suggest the modulatory mechanism of ghrelin influence on the gastric mucosal inflammatory responses to H. pylori.
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11
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Slomiany BL, Slomiany A. Mechanism of Rac1-induced amplification in gastric mucosal phospholipase Cγ2 activation in response to Helicobacter pylori: modulatory effect of ghrelin. Inflammopharmacology 2015; 23:101-9. [PMID: 25796615 DOI: 10.1007/s10787-015-0231-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Accepted: 03/04/2015] [Indexed: 12/27/2022]
Abstract
Membrane recruitment followed by targeted phosphorylation of specific Tyr and Ser residues and the interaction with Rac GTPases are the crucial parts of an elaborate mechanism of PLCγ2 activation essential for its role in linking the specific receptor responses to a variety of hormones and bacterial endotoxins with the intended intracellular targets. Here, we explored the involvement of Rac in mediation of PLCγ2 activation associated with gastric mucosal inflammatory responses to H. pylori LPS and the hormone, ghrelin. We show that stimulation of gastric mucosal cells with the LPS leads to the membrane translocation of Rac1 as well as PLCγ2, while the effect of ghrelin is manifested by elevation in the membrane PLCγ2 activation and suppression in Rac1 translocation. However, blocking the LPS-induced Rac1 translocation, while detrimental to the PLCγ2 activation, has no effect on its membrane translocation. We reveal further that PLCγ2, localized in the membrane in association with Rac1 following the LPS stimulation, exhibits a marked increase in phosphorylation on Ser, while the modulatory effect of ghrelin, manifested by a drop in Rac1 translocation, is associated with a distinct decrease in PLCγ2 phosphorylation on Ser. Thus, the results suggest that H. pylori-elicited increase in gastric mucosal PLCγ2 phosphorylation on Ser serves as an essential platform for Rac1 colocalization and amplification in PLCγ2 activation.
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Affiliation(s)
- B L Slomiany
- Research Center C875, Rutgers School of Dental Medicine Rutgers, The State University of New Jersey, 110 Bergen Street, PO Box 1709, Newark, NJ, 07103-2400, USA,
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12
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Wang X, Hills LB, Huang YH. Lipid and Protein Co-Regulation of PI3K Effectors Akt and Itk in Lymphocytes. Front Immunol 2015; 6:117. [PMID: 25821452 PMCID: PMC4358224 DOI: 10.3389/fimmu.2015.00117] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Accepted: 03/02/2015] [Indexed: 12/21/2022] Open
Abstract
The phosphoinositide 3-kinase (PI 3-kinase, PI3K) pathway transduces signals critical for lymphocyte function. PI3K generates the phospholipid PIP3 at the plasma membrane to recruit proteins that contain pleckstrin homology (PH) domains – a conserved domain found in hundreds of mammalian proteins. PH domain–PIP3 interactions allow for rapid signal propagation and confer a spatial component to these signals. The kinases Akt and Itk are key PI3K effectors that bind PIP3 via their PH domains and mediate vital processes – such as survival, activation, and differentiation – in lymphocytes. Here, we review the roles and regulation of PI3K signaling in lymphocytes with a specific emphasis on Akt and Itk. We also discuss these and other PH domain-containing proteins as they relate more broadly to immune cell function. Finally, we highlight the emerging view of PH domains as multifunctional protein domains that often bind both lipid and protein substrates to exert their effects.
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Affiliation(s)
- Xinxin Wang
- California Institute for Biomedical Research , La Jolla, CA , USA
| | - Leonard Benjamin Hills
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth , Lebanon, NH , USA
| | - Yina Hsing Huang
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth , Lebanon, NH , USA ; Department of Pathology, Geisel School of Medicine at Dartmouth , Lebanon, NH , USA
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13
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Koss H, Bunney TD, Behjati S, Katan M. Dysfunction of phospholipase Cγ in immune disorders and cancer. Trends Biochem Sci 2014; 39:603-11. [PMID: 25456276 DOI: 10.1016/j.tibs.2014.09.004] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Revised: 09/19/2014] [Accepted: 09/24/2014] [Indexed: 12/15/2022]
Abstract
The surge in genetic and genomic investigations over the past 5 years has resulted in many discoveries of causative variants relevant to disease pathophysiology. Although phospholipase C (PLC) enzymes have long been recognized as important components in intracellular signal transmission, it is only recently that this approach highlighted their role in disease development through gain-of-function mutations. In this review we describe the new findings that link the PLCγ family to immune disorders and cancer, and illustrate further efforts to elucidate the molecular mechanisms that underpin their dysfunction.
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Affiliation(s)
- Hans Koss
- Institute of Structural and Molecular Biology, Division of Biosciences, University College London, London, UK; Division of Molecular Structure, Medical Research Council (MRC) National Institute for Medical Research, London, UK
| | - Tom D Bunney
- Institute of Structural and Molecular Biology, Division of Biosciences, University College London, London, UK.
| | - Sam Behjati
- Cancer Genome Project, Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, UK
| | - Matilda Katan
- Institute of Structural and Molecular Biology, Division of Biosciences, University College London, London, UK.
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14
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Role of amplification in phospholipase Cγ2 activation in modulation of gastric mucosal inflammatory responses to Helicobacter pylori: effect of ghrelin. Inflammopharmacology 2014; 23:37-45. [PMID: 25362585 DOI: 10.1007/s10787-014-0220-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Accepted: 10/18/2014] [Indexed: 12/21/2022]
Abstract
Phosphoinositide-specific phospholipase C (PLC) enzymes are crucial elements of signal transduction pathways that provide a common link of communication integrating specific receptor responses to a variety of hormones, growth factors, and bacterial endotoxins with the intended intracellular targets. Here, we examined the involvement of PLC in modulation of gastric mucosal inflammatory responses to Helicobacter pylori LPS by peptide hormone, ghrelin. We show that stimulation of gastric mucosal cells with the LPS leads to the activation and membrane translocation of the γ2 isoform of PLC, phosphorylated on Tyr as well as Ser, while the effect of ghrelin is reflected in the translocation and phosphorylation of membrane-associated PLCγ2 on Tyr mainly. Moreover, we demonstrate that PLCγ2 phosphorylation on Tyr remains under the control of the Src family protein tyrosine kinases (SFK-PTKs), and is intimately linked to PLCγ2 membrane localization, while the LPS-induced phosphorylation of membrane-recruited PLCγ2 on Ser displays dependence on protein kinase Cδ (PKCδ) and leads to the amplification in PLCγ2 activation. Thus, our findings link the extent of H. pylori-elicited gastric mucosal inflammatory involvement to the PKCδ-mediated amplification in PLCγ2 activation through phosphorylation on Ser.
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15
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Wang J, Sohn H, Sun G, Milner JD, Pierce SK. The autoinhibitory C-terminal SH2 domain of phospholipase C-γ2 stabilizes B cell receptor signalosome assembly. Sci Signal 2014; 7:ra89. [PMID: 25227611 DOI: 10.1126/scisignal.2005392] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The binding of antigen to the B cell receptor (BCR) stimulates the assembly of a signaling complex (signalosome) composed initially of the kinases Lyn, spleen tyrosine kinase (Syk), and Bruton's tyrosine kinase (Btk), as well as the adaptor protein B cell linker (BLNK). Together, these proteins recruit and activate phospholipase C-γ2 (PLC-γ2), a critical effector that stimulates increases in intracellular Ca(2+) and activates various signaling pathways downstream of the BCR. Individuals with one copy of a mutant PLCG2 gene, which encodes a variant PLC-γ2 that lacks the autoinhibitory C-terminal Src homology 2 (cSH2) domain, exhibit PLC-γ2-associated antibody deficiency and immune dysregulation (PLAID). Paradoxically, although COS-7 cells expressing the variant PLC-γ2 show enhanced basal and stimulated PLC-γ2 activity, B cells from PLAID patients show defective intracellular Ca(2+) responses upon cross-linking of the BCR. We found that the cSH2 domain of PLC-γ2 played a critical role in stabilizing the early signaling complex that is stimulated by BCR cross-linking. In the presence of the variant PLC-γ2, Syk, Btk, and BLNK were only weakly phosphorylated and failed to stably associate with the BCR. Thus, BCRs could not form stable clusters, resulting in dysregulation of downstream signaling and trafficking of the BCR. Thus, the cSH2 domain functions not only to inhibit the active site of PLC-γ2 but also to directly or indirectly stabilize the early BCR signaling complex.
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Affiliation(s)
- Jing Wang
- Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA
| | - Haewon Sohn
- Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA
| | - Guangping Sun
- Laboratory of Allergic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Joshua D Milner
- Laboratory of Allergic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Susan K Pierce
- Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA.
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16
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Timsah Z, Ahmed Z, Lin CC, Melo FA, Stagg LJ, Leonard PG, Jeyabal P, Berrout J, O'Neil RG, Bogdanov M, Ladbury JE. Competition between Grb2 and Plcγ1 for FGFR2 regulates basal phospholipase activity and invasion. Nat Struct Mol Biol 2014; 21:180-8. [DOI: 10.1038/nsmb.2752] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Accepted: 12/02/2013] [Indexed: 12/23/2022]
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17
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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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18
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Bernal-Quirós M, Wu YY, Alarcón-Riquelme ME, Castillejo-López C. BANK1 and BLK act through phospholipase C gamma 2 in B-cell signaling. PLoS One 2013; 8:e59842. [PMID: 23555801 PMCID: PMC3608554 DOI: 10.1371/journal.pone.0059842] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Accepted: 02/19/2013] [Indexed: 12/22/2022] Open
Abstract
The B cell adaptor protein with ankyrin repeats (BANK1) and the B lymphoid tyrosine kinase (BLK) have been genetically associated with autoimmunity. The proteins of these genes interact physically and work in concert during B-cell signaling. Little is know about their interactions with other B-cell signaling molecules or their role in the process. Using yeast two hybrid (Y2H) we sought for factors that interact with BANK1. We found that the molecular switch PLCg2 interacts with BANK1 and that the interaction is promoted by B-cell receptor (BCR) stimulation. We found further that the kinase activity of BLK enhanced BANK1- PLCg2 binding and that the interaction was suppressed upon BLK depletion. Immunoprecipitation and mutational analysis demonstrated that the interaction between BANK1 and PLCg2 was dependent on specific tyrosine and proline residues on the adaptor protein. Our results provide new information important to understand the role of these two genes in basic B-cell physiology and immune-related diseases.
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Affiliation(s)
- Manuel Bernal-Quirós
- Centro de Genómica e Investigación Oncológica, Pfizer-Universidad de Granada-Junta de Andalucía, Granada, Spain
| | - Ying-Yu Wu
- Arthritis and Clinical Immunology Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma, United States of America
| | - Marta E. Alarcón-Riquelme
- Centro de Genómica e Investigación Oncológica, Pfizer-Universidad de Granada-Junta de Andalucía, Granada, Spain
- Arthritis and Clinical Immunology Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma, United States of America
- * E-mail: (CCL); (MEAR)
| | - Casimiro Castillejo-López
- Centro de Genómica e Investigación Oncológica, Pfizer-Universidad de Granada-Junta de Andalucía, Granada, Spain
- * E-mail: (CCL); (MEAR)
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19
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Bunney T, Esposito D, Mas-Droux C, Lamber E, Baxendale R, Martins M, Cole A, Svergun D, Driscoll P, Katan M. Structural and functional integration of the PLCγ interaction domains critical for regulatory mechanisms and signaling deregulation. Structure 2012; 20:2062-75. [PMID: 23063561 PMCID: PMC3532599 DOI: 10.1016/j.str.2012.09.005] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2012] [Revised: 09/03/2012] [Accepted: 09/07/2012] [Indexed: 11/30/2022]
Abstract
Multidomain proteins incorporating interaction domains are central to regulation of cellular processes. The elucidation of structural organization and mechanistic insights into many of these proteins, however, remain challenging due to their inherent flexibility. Here, we describe the organization and function of four interaction domains in PLCγ1 using a combination of structural biology and biochemical approaches. Intramolecular interactions within the regulatory region center on the cSH2 domain, the only domain that also interacts with the PLC-core. In the context of fibroblast growth-factor receptor signaling, the coordinated involvement of nSH2 and cSH2 domains mediates efficient phosphorylation of PLCγ1 resulting in the interruption of an autoinhibitory interface by direct competition and, independently, dissociation of PLCγ1 from the receptor. Further structural insights into the autoinhibitory surfaces provide a framework to interpret gain-of-function mutations in PLCγ isoforms linked to immune disorders and illustrate a distinct mechanism for regulation of PLC activity by common interaction domains.
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MESH Headings
- Amino Acid Motifs
- Amino Acid Substitution
- Animals
- Catalytic Domain
- Cell Line
- Crystallography, X-Ray
- Enzyme Activation
- Humans
- Inositol Phosphates/chemistry
- Kinetics
- Models, Molecular
- Mutagenesis, Site-Directed
- Nuclear Magnetic Resonance, Biomolecular
- Phospholipase C gamma/chemistry
- Phospholipase C gamma/genetics
- Phospholipase C gamma/metabolism
- Phosphorylation
- Protein Binding
- Protein Interaction Domains and Motifs
- Protein Processing, Post-Translational
- Protein Structure, Secondary
- Receptor, Fibroblast Growth Factor, Type 1/metabolism
- Receptor, Fibroblast Growth Factor, Type 1/physiology
- Signal Transduction
- Sus scrofa
- Thermodynamics
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Affiliation(s)
- Tom D. Bunney
- Institute of Structural and Molecular Biology, Division of Biosciences, University College London, Gower Street, London WC1E 6BT, UK
| | - Diego Esposito
- Division of Molecular Structure, MRC-National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
| | - Corine Mas-Droux
- Institute of Structural and Molecular Biology, Division of Biosciences, University College London, Gower Street, London WC1E 6BT, UK
| | - Ekatarina Lamber
- Research Institute of Molecular Pathology, Dr. Bohr-Gasse 7, 1030 Vienna, Austria
| | - Rhona W. Baxendale
- Institute of Structural and Molecular Biology, Division of Biosciences, University College London, Gower Street, London WC1E 6BT, UK
| | - Marta Martins
- Institute of Structural and Molecular Biology, Division of Biosciences, University College London, Gower Street, London WC1E 6BT, UK
| | | | - Dmitri Svergun
- European Molecular Biology Laboratory, Hamburg Outstation c/o DESY, Notkestrasse 85, 22603 Hamburg, Germany
| | - Paul C. Driscoll
- Division of Molecular Structure, MRC-National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
| | - Matilda Katan
- Institute of Structural and Molecular Biology, Division of Biosciences, University College London, Gower Street, London WC1E 6BT, UK
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20
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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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21
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Goñi FM, Montes LR, Alonso A. Phospholipases C and sphingomyelinases: Lipids as substrates and modulators of enzyme activity. Prog Lipid Res 2012; 51:238-66. [DOI: 10.1016/j.plipres.2012.03.002] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2012] [Revised: 03/23/2012] [Accepted: 03/26/2012] [Indexed: 11/30/2022]
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22
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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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23
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Ehrlich LS, Medina GN, Carter CA. ESCRT machinery potentiates HIV-1 utilization of the PI(4,5)P(2)-PLC-IP3R-Ca(2+) signaling cascade. J Mol Biol 2011; 413:347-58. [PMID: 21875593 PMCID: PMC3193579 DOI: 10.1016/j.jmb.2011.08.038] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2011] [Revised: 08/05/2011] [Accepted: 08/16/2011] [Indexed: 01/09/2023]
Abstract
Human immunodeficiency virus type 1 (HIV-1) release efficiency is directed by late (L) domain motifs in the viral structural precursor polyprotein Gag, which serve as links to the ESCRT (endosomal sorting complex required for transport) machinery. Linkage is normally through binding of Tsg101, an ESCRT-1 component, to the P(7)TAP motif in the p6 region of Gag. In its absence, budding is directed by binding of Alix, an ESCRT adaptor protein, to the LY(36)PX(n)L motif in Gag. We recently showed that budding requires activation of the inositol 1,4,5-triphosphate receptor (IP3R), a protein that "gates" Ca(2+) release from intracellular stores, triggers Ca(2+) cell influx and thereby functions as a major regulator of Ca(2+) signaling. In the present study, we determined whether the L domain links Gag to Ca(2+) signaling machinery. Depletion of IP3R and inactivation of phospholipase C (PLC) inhibited budding whether or not Tsg101 was bound to Gag. PLC hydrolysis of phosphatidylinositol-(4,5)-bisphosphate generates inositol (1,4,5)-triphosphate, the ligand that activates IP3R. However, with Tsg101 bound, Gag release was independent of Gq-mediated activation of PLC, and budding was readily enhanced by pharmacological stimulation of PLC. Moreover, IP3R was redistributed to the cell periphery and cytosolic Ca(2+) was elevated, events indicative of induction of Ca(2+) signaling. The results suggest that L domain function, ESCRT machinery and Ca(2+) signaling are linked events in Gag release.
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Affiliation(s)
- Lorna S. Ehrlich
- Dept. of Molecular Genetics & Microbiology, Stony Brook University, Stony Brook, NY 11794-5222, USA
| | - Gisselle N. Medina
- Dept. of Molecular Genetics & Microbiology, Stony Brook University, Stony Brook, NY 11794-5222, USA
| | - Carol A. Carter
- Dept. of Molecular Genetics & Microbiology, Stony Brook University, Stony Brook, NY 11794-5222, USA
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