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Sulimenko V, Sládková V, Sulimenko T, Dráberová E, Vosecká V, Dráberová L, Skalli O, Dráber P. Regulation of microtubule nucleation in mouse bone marrow-derived mast cells by ARF GTPase-activating protein GIT2. Front Immunol 2024; 15:1321321. [PMID: 38370406 PMCID: PMC10870779 DOI: 10.3389/fimmu.2024.1321321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Accepted: 01/16/2024] [Indexed: 02/20/2024] Open
Abstract
Aggregation of high-affinity IgE receptors (FcϵRIs) on granulated mast cells triggers signaling pathways leading to a calcium response and release of inflammatory mediators from secretory granules. While microtubules play a role in the degranulation process, the complex molecular mechanisms regulating microtubule remodeling in activated mast cells are only partially understood. Here, we demonstrate that the activation of bone marrow mast cells induced by FcϵRI aggregation increases centrosomal microtubule nucleation, with G protein-coupled receptor kinase-interacting protein 2 (GIT2) playing a vital role in this process. Both endogenous and exogenous GIT2 were associated with centrosomes and γ-tubulin complex proteins. Depletion of GIT2 enhanced centrosomal microtubule nucleation, and phenotypic rescue experiments revealed that GIT2, unlike GIT1, acts as a negative regulator of microtubule nucleation in mast cells. GIT2 also participated in the regulation of antigen-induced degranulation and chemotaxis. Further experiments showed that phosphorylation affected the centrosomal localization of GIT2 and that during antigen-induced activation, GIT2 was phosphorylated by conventional protein kinase C, which promoted microtubule nucleation. We propose that GIT2 is a novel regulator of microtubule organization in activated mast cells by modulating centrosomal microtubule nucleation.
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Affiliation(s)
- Vadym Sulimenko
- Laboratory of Biology of Cytoskeleton, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czechia
| | - Vladimíra Sládková
- Laboratory of Biology of Cytoskeleton, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czechia
| | - Tetyana Sulimenko
- Laboratory of Biology of Cytoskeleton, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czechia
| | - Eduarda Dráberová
- Laboratory of Biology of Cytoskeleton, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czechia
| | - Věra Vosecká
- Laboratory of Biology of Cytoskeleton, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czechia
| | - Lubica Dráberová
- Laboratory of Signal Transduction, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czechia
| | - Omar Skalli
- Department of Biological Sciences, The University of Memphis, Memphis, TN, United States
| | - Pavel Dráber
- Laboratory of Biology of Cytoskeleton, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czechia
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Bugajev V, Draberova L, Utekal P, Blazikova M, Tumova M, Draber P. Enhanced Membrane Fluidization and Cholesterol Displacement by 1-Heptanol Inhibit Mast Cell Effector Functions. Cells 2023; 12:2069. [PMID: 37626879 PMCID: PMC10453462 DOI: 10.3390/cells12162069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2023] [Revised: 07/27/2023] [Accepted: 08/09/2023] [Indexed: 08/27/2023] Open
Abstract
Signal transduction by the high-affinity IgE receptor (FcεRI) depends on membrane lipid and protein compartmentalization. Recently published data show that cells treated with 1-heptanol, a cell membrane fluidizer, exhibit changes in membrane properties. However, the functional consequences of 1-heptanol-induced changes on mast cell signaling are unknown. This study shows that short-term exposure to 1-heptanol reduces membrane thermal stability and dysregulates mast cell signaling at multiple levels. Cells treated with 1-heptanol exhibited increased lateral mobility and decreased internalization of the FcεRI. However, this did not affect the initial phosphorylation of the FcεRI-β chain and components of the SYK/LAT1/PLCγ1 signaling pathway after antigen activation. In contrast, 1-heptanol inhibited SAPK/JNK phosphorylation and effector functions such as calcium response, degranulation, and cytokine production. Membrane hyperfluidization induced a heat shock-like response via increased expression of the heat shock protein 70, increased lateral diffusion of ORAI1-mCherry, and unsatisfactory performance of STIM1-ORAI1 coupling, as determined by flow-FRET. Furthermore, 1-heptanol inhibited the antigen-induced production of reactive oxygen species and potentiated stress-induced plasma membrane permeability by interfering with heat shock protein 70 activity. The combined data suggest that 1-heptanol-mediated membrane fluidization does not interfere with the earliest biochemical steps of FcεRI signaling, such as phosphorylation of the FcεRI-β chain and components of the SYK/LAT/PLCγ1 signaling pathway, instead inhibiting the FcεRI internalization and mast cell effector functions, including degranulation and cytokine production.
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Affiliation(s)
- Viktor Bugajev
- Laboratory of Signal Transduction, Institute of Molecular Genetics of the Czech Academy of Sciences, 14220 Prague, Czech Republic; (L.D.); (P.U.); (M.T.)
| | - Lubica Draberova
- Laboratory of Signal Transduction, Institute of Molecular Genetics of the Czech Academy of Sciences, 14220 Prague, Czech Republic; (L.D.); (P.U.); (M.T.)
| | - Pavol Utekal
- Laboratory of Signal Transduction, Institute of Molecular Genetics of the Czech Academy of Sciences, 14220 Prague, Czech Republic; (L.D.); (P.U.); (M.T.)
| | - Michaela Blazikova
- Light Microscopy Core Facility, Institute of Molecular Genetics of the Czech Academy of Sciences, 14220 Prague, Czech Republic;
| | - Magda Tumova
- Laboratory of Signal Transduction, Institute of Molecular Genetics of the Czech Academy of Sciences, 14220 Prague, Czech Republic; (L.D.); (P.U.); (M.T.)
| | - Petr Draber
- Laboratory of Signal Transduction, Institute of Molecular Genetics of the Czech Academy of Sciences, 14220 Prague, Czech Republic; (L.D.); (P.U.); (M.T.)
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Mast cell granule motility and exocytosis is driven by dynamic microtubule formation and kinesin-1 motor function. PLoS One 2022; 17:e0265122. [PMID: 35316306 PMCID: PMC8939832 DOI: 10.1371/journal.pone.0265122] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Accepted: 02/23/2022] [Indexed: 11/19/2022] Open
Abstract
Mast cells are tissue-resident immune cells that have numerous cytoplasmic granules which contain preformed pro-inflammatory mediators. Upon antigen stimulation, sensitized mast cells undergo profound changes to their morphology and rapidly release granule mediators by regulated exocytosis, also known as degranulation. We have previously shown that Rho GTPases regulate exocytosis, which suggests that cytoskeleton remodeling is involved in granule transport. Here, we used live-cell imaging to analyze cytoskeleton remodeling and granule transport in real-time as mast cells were antigen stimulated. We found that granule transport to the cell periphery was coordinated by de novo microtubule formation and not F-actin. Kinesore, a drug that activates the microtubule motor kinesin-1 in the absence of cargo, inhibited microtubule-granule association and significantly reduced exocytosis. Likewise, shRNA knock-down of Kif5b, the kinesin-1 heavy chain, also reduced exocytosis. Imaging showed granules accumulated in the perinuclear region after kinesore treatment or Kif5b knock-down. Complete microtubule depolymerization with nocodazole or colchicine resulted in the same effect. A biochemically enriched granule fraction showed kinesin-1 levels increase in antigen-stimulated cells, but are reduced by pre-treatment with kinesore. Kinesore had no effect on the levels of Slp3, a mast cell granule cargo adaptor, in the granule-enriched fraction which suggests that cargo adaptor recruitment to granules is independent of motor association. Taken together, these results show that granules associate with microtubules and are driven by kinesin-1 to facilitate exocytosis.
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Shapoval O, Sulimenko V, Klebanovych A, Rabyk M, Shapoval P, Kaman O, Rydvalová E, Filipová M, Dráberová E, Dráber P, Horák D. Multimodal fluorescently labeled polymer-coated GdF 3 nanoparticles inhibit degranulation in mast cells. NANOSCALE 2021; 13:19023-19037. [PMID: 34755752 DOI: 10.1039/d1nr06127e] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Multimodal gadolinium fluoride nanoparticles belong to potential contrast agents useful for bimodal optical fluorescence and magnetic resonance imaging. However, the metallic nature of the nanoparticles, similarly to some paramagnetic iron oxides, might induce allergic and anaphylactic reactions in patients after administration. A reduction of these adverse side effects is a priority for the safe application of the nanoparticles. Herein, we prepared paramagnetic poly(4-styrenesulfonic acid-co-maleic acid) (PSSMA)-stabilized GdF3 nanoparticles with surface modified by Atto 488-labeled poly(styrene-grad-2-dimethylaminoethyl acrylate)-block-poly(2-dimethylaminoethyl acrylate) (PSDA-A488) with reactive amino groups for introduction of an additional imaging (luminescence) modality and possible targeting of anticancer drugs. The saturation magnetization of GdF3@PSSMA particles according to SQUID magnetometry reached 157 Am2 kg-1 at 2 K and magnetic field of 7 T. GdF3@PSSMA-PSDA-A488 nanoparticles were well tolerated by human cervical adenocarcinoma (HeLa), mouse bone marrow-derived mast cells (BMMC), and rat basophilic mast cells (RBL-2H3); the particles also affected cell morphology and protein tyrosine phosphorylation in mast cells. Moreover, the nanoparticles interfered with the activation of mast cells by multivalent antigens and inhibited calcium mobilization and cell degranulation. These findings show that the new multimodal GdF3-based nanoparticles possess properties useful for various imaging methods and might minimize mast cell degranulation incurred after future nanoparticle diagnostic administration.
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Affiliation(s)
- Oleksandr Shapoval
- Institute of Macromolecular Chemistry of the Czech Academy of Sciences, Heyrovského nám. 2, 162 06 Prague 6, Czech Republic
| | - Vadym Sulimenko
- Laboratory of Biology of Cytoskeleton, Institute of Molecular Genetics of the Czech Academy of Sciences, Vídeňská 1083, 142 20 Prague 4, Czech Republic
| | - Anastasiya Klebanovych
- Laboratory of Biology of Cytoskeleton, Institute of Molecular Genetics of the Czech Academy of Sciences, Vídeňská 1083, 142 20 Prague 4, Czech Republic
| | - Mariia Rabyk
- Institute of Macromolecular Chemistry of the Czech Academy of Sciences, Heyrovského nám. 2, 162 06 Prague 6, Czech Republic
| | - Pavlo Shapoval
- Department of Physical, Analytical and General Chemistry, Lviv Polytechnic National University, Sv. Yura Sq. 9, 79013 Lviv, Ukraine
| | - Ondřej Kaman
- Institute of Physics of the Czech Academy of Sciences, Cukrovarnická 112/10, 162 00 Prague 6, Czech Republic
| | - Eliška Rydvalová
- Institute of Macromolecular Chemistry of the Czech Academy of Sciences, Heyrovského nám. 2, 162 06 Prague 6, Czech Republic
| | - Marcela Filipová
- Institute of Macromolecular Chemistry of the Czech Academy of Sciences, Heyrovského nám. 2, 162 06 Prague 6, Czech Republic
| | - Eduarda Dráberová
- Laboratory of Biology of Cytoskeleton, Institute of Molecular Genetics of the Czech Academy of Sciences, Vídeňská 1083, 142 20 Prague 4, Czech Republic
| | - Pavel Dráber
- Laboratory of Biology of Cytoskeleton, Institute of Molecular Genetics of the Czech Academy of Sciences, Vídeňská 1083, 142 20 Prague 4, Czech Republic
| | - Daniel Horák
- Institute of Macromolecular Chemistry of the Czech Academy of Sciences, Heyrovského nám. 2, 162 06 Prague 6, Czech Republic
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Crosstalk between ORMDL3, serine palmitoyltransferase, and 5-lipoxygenase in the sphingolipid and eicosanoid metabolic pathways. J Lipid Res 2021; 62:100121. [PMID: 34560079 PMCID: PMC8527048 DOI: 10.1016/j.jlr.2021.100121] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Revised: 08/23/2021] [Accepted: 09/08/2021] [Indexed: 11/21/2022] Open
Abstract
Leukotrienes (LTs) and sphingolipids are critical lipid mediators participating in numerous cellular signal transduction events and developing various disorders, such as bronchial hyperactivity leading to asthma. Enzymatic reactions initiating production of these lipid mediators involve 5-lipoxygenase (5-LO)-mediated conversion of arachidonic acid to LTs and serine palmitoyltransferase (SPT)-mediated de novo synthesis of sphingolipids. Previous studies have shown that endoplasmic reticulum membrane protein ORM1-like protein 3 (ORMDL3) inhibits the activity of SPT and subsequent sphingolipid synthesis. However, the role of ORMDL3 in the synthesis of LTs is not known. In this study, we used peritoneal-derived mast cells isolated from ORMDL3 KO or control mice and examined their calcium mobilization, degranulation, NF-κB inhibitor-α phosphorylation, and TNF-α production. We found that peritoneal-derived mast cells with ORMDL3 KO exhibited increased responsiveness to antigen. Detailed lipid analysis showed that compared with WT cells, ORMDL3-deficient cells exhibited not only enhanced production of sphingolipids but also of LT signaling mediators LTB4, 6t-LTB4, LTC4, LTB5, and 6t-LTB5. The crosstalk between ORMDL3 and 5-LO metabolic pathways was supported by the finding that endogenous ORMDL3 and 5-LO are localized in similar endoplasmic reticulum domains in human mast cells and that ORMDL3 physically interacts with 5-LO. Further experiments showed that 5-LO also interacts with the long-chain 1 and long-chain 2 subunits of SPT. In agreement with these findings, 5-LO knockdown increased ceramide levels, and silencing of SPTLC1 decreased arachidonic acid metabolism to LTs to levels observed upon 5-LO knockdown. These results demonstrate functional crosstalk between the LT and sphingolipid metabolic pathways, leading to the production of lipid signaling mediators.
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Ménasché G, Longé C, Bratti M, Blank U. Cytoskeletal Transport, Reorganization, and Fusion Regulation in Mast Cell-Stimulus Secretion Coupling. Front Cell Dev Biol 2021; 9:652077. [PMID: 33796537 PMCID: PMC8007931 DOI: 10.3389/fcell.2021.652077] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Accepted: 02/03/2021] [Indexed: 01/16/2023] Open
Abstract
Mast cells are well known for their role in allergies and many chronic inflammatory diseases. They release upon stimulation, e.g., via the IgE receptor, numerous bioactive compounds from cytoplasmic secretory granules. The regulation of granule secretion and its interaction with the cytoskeleton and transport mechanisms has only recently begun to be understood. These studies have provided new insight into the interaction between the secretory machinery and cytoskeletal elements in the regulation of the degranulation process. They suggest a tight coupling of these two systems, implying a series of specific signaling effectors and adaptor molecules. Here we review recent knowledge describing the signaling events regulating cytoskeletal reorganization and secretory granule transport machinery in conjunction with the membrane fusion machinery that occur during mast cell degranulation. The new insight into MC biology offers novel strategies to treat human allergic and inflammatory diseases targeting the late steps that affect harmful release from granular stores leaving regulatory cytokine secretion intact.
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Affiliation(s)
- Gaël Ménasché
- Laboratory of Molecular Basis of Altered Immune Homeostasis, Imagine Institute, INSERM UMR 1163, Université de Paris, Paris, France
| | - Cyril Longé
- Laboratory of Molecular Basis of Altered Immune Homeostasis, Imagine Institute, INSERM UMR 1163, Université de Paris, Paris, France
| | - Manuela Bratti
- Centre de Recherche sur l'Inflammation, INSERM UMR 1149, CNRS ERL8252, Faculté de Médecine site Bichat, Université de Paris, Paris, France.,Laboratoire d'Excellence Inflamex, Université de Paris, Paris, France
| | - Ulrich Blank
- Centre de Recherche sur l'Inflammation, INSERM UMR 1149, CNRS ERL8252, Faculté de Médecine site Bichat, Université de Paris, Paris, France.,Laboratoire d'Excellence Inflamex, Université de Paris, Paris, France
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7
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Use of Engineered Nanoparticles (ENPs) for the Study of High-Affinity IgE FcεRI Receptor Engagement and Rat Basophilic Leukemia (RBL) Cell Degranulation. Methods Mol Biol 2020. [PMID: 32766975 DOI: 10.1007/978-1-0716-0696-4_14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
Degranulation of mast cells and basophils occurs after the cross-linking of FcεRI receptor-bound IgE by multivalent allergens, resulting in the release of a range of de novo synthesized and preformed mediators of the allergic response. β-Hexosaminidase release is usually measured as a simple readout for degranulation. Furthermore, the rat basophilic leukemia (RBL)-2H3 cell line is commonly used for measuring degranulation, monitoring β-hexosaminidase release. Here, we describe surface-engineered and modified nanoparticles with specific ligands in order to study the signaling and cellular responses of the RBL-2H3 cell line.
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8
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Abstract
Highly conserved α- and β-tubulin heterodimers assemble into dynamic microtubules and perform multiple important cellular functions such as structural support, pathway for transport and force generation in cell division. Tubulin exists in different forms of isotypes expressed by specific genes with spatially- and temporally-regulated expression levels. Some tubulin isotypes are differentially expressed in normal and neoplastic cells, providing a basis for cancer chemotherapy drug development. Moreover, specific tubulin isotypes are overexpressed and localized in the nuclei of cancer cells and/or show bioenergetic functions through the regulation of the permeability of mitochondrial ion channels. It has also become clear that tubulin isotypes are involved in multiple cellular functions without being incorporated into microtubule structures. Understanding the mutations of tubulin isotypes specifically expressed in tumors and their post-translational modifications might help to identify precise molecular targets for the design of novel anti-microtubular drugs. Knowledge of tubulin mutations present in tubulinopathies brings into focus cellular functions of tubulin in brain pathologies such as Alzheimer’s disease. Uncovering signaling pathways which affect tubulin functions during antigen-mediated activation of mast cells presents a major challenge in developing new strategies for the treatment of inflammatory and allergic diseases. γ-tubulin, a conserved member of the eukaryotic tubulin superfamily specialized for microtubule nucleation is a target of cell cycle and stress signaling. Besides its microtubule nucleation role, γ-tubulin functions in nuclear and cell cycle related processes. This special issue “Tubulin: Structure, Functions and Roles in Disease” contains eight articles, five of which are original research papers and three are review papers that cover diverse areas of tubulin biology and functions under normal and pathological conditions.
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TUBG1 missense variants underlying cortical malformations disrupt neuronal locomotion and microtubule dynamics but not neurogenesis. Nat Commun 2019; 10:2129. [PMID: 31086189 PMCID: PMC6513894 DOI: 10.1038/s41467-019-10081-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 04/05/2019] [Indexed: 01/13/2023] Open
Abstract
De novo heterozygous missense variants in the γ-tubulin gene TUBG1 have been linked to human malformations of cortical development associated with intellectual disability and epilepsy. Here, we investigated through in-utero electroporation and in-vivo studies, how four of these variants affect cortical development. We show that TUBG1 mutants affect neuronal positioning, disrupting the locomotion of new-born neurons but without affecting progenitors’ proliferation. We further demonstrate that pathogenic TUBG1 variants are linked to reduced microtubule dynamics but without major structural nor functional centrosome defects in subject-derived fibroblasts. Additionally, we developed a knock-in Tubg1Y92C/+ mouse model and assessed consequences of the mutation. Although centrosomal positioning in bipolar neurons is correct, they fail to initiate locomotion. Furthermore, Tubg1Y92C/+ animals show neuroanatomical and behavioral defects and increased epileptic cortical activity. We show that Tubg1Y92C/+ mice partially mimic the human phenotype and therefore represent a relevant model for further investigations of the physiopathology of cortical malformations. New mutations and genes associated with malformations of cortical development keep being identified, yet there is little known about the underlying cellular mechanisms controlling these impairments. Here, authors generate and characterize a heterozygous TUBG1 knock-in mouse model bearing one of these known mutations and show that TUBG1 mutation leads to the miss-positioning of neurons in the cortical wall due to migration, because of defective microtubules dynamics, and not proliferation defects during corticogenesis.
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Regulation of Microtubule Nucleation in Mouse Bone Marrow-Derived Mast Cells by Protein Tyrosine Phosphatase SHP-1. Cells 2019; 8:cells8040345. [PMID: 30979083 PMCID: PMC6523986 DOI: 10.3390/cells8040345] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2019] [Revised: 03/30/2019] [Accepted: 04/10/2019] [Indexed: 12/20/2022] Open
Abstract
The antigen-mediated activation of mast cells initiates signaling events leading to their degranulation, to the release of inflammatory mediators, and to the synthesis of cytokines and chemokines. Although rapid and transient microtubule reorganization during activation has been described, the molecular mechanisms that control their rearrangement are largely unknown. Microtubule nucleation is mediated by γ-tubulin complexes. In this study, we report on the regulation of microtubule nucleation in bone marrow-derived mast cells (BMMCs) by Src homology 2 (SH2) domain-containing protein tyrosine phosphatase 1 (SHP-1; Ptpn6). Reciprocal immunoprecipitation experiments and pull-down assays revealed that SHP-1 is present in complexes containing γ-tubulin complex proteins and protein tyrosine kinase Syk. Microtubule regrowth experiments in cells with deleted SHP-1 showed a stimulation of microtubule nucleation, and phenotypic rescue experiments confirmed that SHP-1 represents a negative regulator of microtubule nucleation in BMMCs. Moreover, the inhibition of the SHP-1 activity by inhibitors TPI-1 and NSC87877 also augmented microtubule nucleation. The regulation was due to changes in γ-tubulin accumulation. Further experiments with antigen-activated cells showed that the deletion of SHP-1 stimulated the generation of microtubule protrusions, the activity of Syk kinase, and degranulation. Our data suggest a novel mechanism for the suppression of microtubule formation in the later stages of mast cell activation.
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Rubíková Z, Sulimenko V, Paulenda T, Dráber P. Mast Cell Activation and Microtubule Organization Are Modulated by Miltefosine Through Protein Kinase C Inhibition. Front Immunol 2018; 9:1563. [PMID: 30038620 PMCID: PMC6046399 DOI: 10.3389/fimmu.2018.01563] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Accepted: 06/25/2018] [Indexed: 12/01/2022] Open
Abstract
Mast cells play an effector role in innate immunity, allergy, and inflammation. Antigen-mediated activation of mast cells initiates signaling events leading to Ca2+ response and the release of inflammatory and allergic mediators from granules. Diseases associated with deregulated mast cell functions are hard to treat and there is an increasing demand for new therapeutic strategies. Miltefosine (hexadecylphosphocholine) is a new candidate for treatment of mast cell-driven diseases as it inhibits activation of mast cells. It has been proposed that miltefosine acts as a lipid raft modulator through its interference with the structural organization of surface receptors in the cell membrane. However, molecular mechanisms of its action are not fully understood. Here, we report that in antigen-activated bone marrow-derived mast cells (BMMCs), miltefosine inhibits degranulation, reorganization of microtubules, as well as antigen-induced chemotaxis. While aggregation and tyrosine phosphorylation of IgE receptors were suppressed in activated cells pre-treated with miltefosine, overall tyrosine phosphorylation levels of Lyn and Syk kinases, and Ca2+ influx were not inhibited. In contrast, lipid raft disruptor methyl-β-cyclodextrin attenuated the Ca2+ influx. Tagged-miltefosine rapidly localized into the cell interior, and live-cell imaging of BMMCs with labeled intracellular granules disclosed that miltefosine inhibited movement of some granules. Immunoprecipitation and in vitro kinase assays revealed that miltefosine inhibited Ca2+- and diacylglycerol-regulated conventional protein kinase C (cPKC) isoforms that are important for mast cell degranulation. Inhibition of cPKCs by specific inhibitor Ly333531 affected activation of BMMCs in the same way as miltefosine. Collectively, our data suggest that miltefosine modulates mast cells both at the plasma membrane and in the cytosol by inhibition of cPKCs. This alters intracellular signaling pathway(s) directed to microtubules, degranulation, and migration.
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Affiliation(s)
- Zuzana Rubíková
- Department of Biology of Cytoskeleton, Institute of Molecular Genetics, Czech Academy of Sciences, Prague, Czechia
| | - Vadym Sulimenko
- Department of Biology of Cytoskeleton, Institute of Molecular Genetics, Czech Academy of Sciences, Prague, Czechia
| | - Tomáš Paulenda
- Department of Signal Transduction, Institute of Molecular Genetics, Czech Academy of Sciences, Prague, Czechia
| | - Pavel Dráber
- Department of Biology of Cytoskeleton, Institute of Molecular Genetics, Czech Academy of Sciences, Prague, Czechia
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Dráberová E, Sulimenko V, Vinopal S, Sulimenko T, Sládková V, D'Agostino L, Sobol M, Hozák P, Křen L, Katsetos CD, Dráber P. Differential expression of human γ-tubulin isotypes during neuronal development and oxidative stress points to a γ-tubulin-2 prosurvival function. FASEB J 2017; 31:1828-1846. [PMID: 28119396 DOI: 10.1096/fj.201600846rr] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Accepted: 01/03/2017] [Indexed: 12/11/2022]
Abstract
γ-Tubulins are highly conserved members of the tubulin superfamily essential for microtubule nucleation. Humans possess 2 γ-tubulin genes. It is thought that γ-tubulin-1 represents a ubiquitous isotype, whereas γ-tubulin-2 is found predominantly in the brain, where it may be endowed with divergent functions beyond microtubule nucleation. The molecular basis of the purported functional differences between γ-tubulins is unknown. We report discrimination of human γ-tubulins according to their electrophoretic and immunochemical properties. In vitro mutagenesis revealed that the differences in electrophoretic mobility originate in the C-terminal regions of the γ-tubulins. Using epitope mapping, we discovered mouse monoclonal antibodies that can discriminate between human γ-tubulin isotypes. Real time quantitative RT-PCR and 2-dimensional-PAGE showed that γ-tubulin-1 is the dominant isotype in fetal neurons. Although γ-tubulin-2 accumulates in the adult brain, γ-tubulin-1 remains the major isotype in various brain regions. Localization of γ-tubulin-1 in mature neurons was confirmed by immunohistochemistry and immunofluorescence microscopy on clinical samples and tissue microarrays. Differentiation of SH-SY5Y human neuroblastoma cells by all-trans retinoic acid, or oxidative stress induced by mitochondrial inhibitors, resulted in upregulation of γ-tubulin-2, whereas the expression of γ-tubulin-1 was unchanged. Fractionation experiments and immunoelectron microscopy revealed an association of γ-tubulins with mitochondrial membranes. These data indicate that in the face of predominant γ-tubulin-1 expression, the accumulation of γ-tubulin-2 in mature neurons and neuroblastoma cells during oxidative stress may denote a prosurvival role of γ-tubulin-2 in neurons.-Dráberová, E., Sulimenko, V., Vinopal, S., Sulimenko, T., Sládková, V., D'Agostino, L., Sobol, M., Hozák, P., Křen, L., Katsetos, C. D., Dráber, P. Differential expression of human γ-tubulin isotypes during neuronal development and oxidative stress points to γ-tubulin-2 prosurvival function.
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Affiliation(s)
- Eduarda Dráberová
- Department of Biology of Cytoskeleton, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Vadym Sulimenko
- Department of Biology of Cytoskeleton, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Stanislav Vinopal
- Department of Biology of Cytoskeleton, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Tetyana Sulimenko
- Department of Biology of Cytoskeleton, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Vladimíra Sládková
- Department of Biology of Cytoskeleton, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Luca D'Agostino
- Department of Pediatrics, Drexel University College of Medicine, St. Christopher's Hospital for Children and Hahnemann University Hospital, Philadelphia, Pennsylvania, USA
| | - Margaryta Sobol
- Department of the Nucleus, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Pavel Hozák
- Department of the Nucleus, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Leoš Křen
- Department of Pathology and Laboratory Medicine, Drexel University College of Medicine, St. Christopher's Hospital for Children and Hahnemann University Hospital, Philadelphia, Pennsylvania, USA; and
| | - Christos D Katsetos
- Department of Pediatrics, Drexel University College of Medicine, St. Christopher's Hospital for Children and Hahnemann University Hospital, Philadelphia, Pennsylvania, USA
| | - Pavel Dráber
- Department of Biology of Cytoskeleton, Academy of Sciences of the Czech Republic, Prague, Czech Republic;
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Pacheco J, Vaca L. STIM-TRP Pathways and Microdomain Organization: Auxiliary Proteins of the STIM/Orai Complex. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 993:189-210. [DOI: 10.1007/978-3-319-57732-6_10] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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14
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Poteser M, Leitinger G, Pritz E, Platzer D, Frischauf I, Romanin C, Groschner K. Live-cell imaging of ER-PM contact architecture by a novel TIRFM approach reveals extension of junctions in response to store-operated Ca 2+-entry. Sci Rep 2016; 6:35656. [PMID: 27759093 PMCID: PMC5069484 DOI: 10.1038/srep35656] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Accepted: 09/29/2016] [Indexed: 01/16/2023] Open
Abstract
Nanometer-spaced appositions between endoplasmic reticulum and plasma membrane (ER-PM junctions) stabilized by membrane-joining protein complexes are critically involved in cellular Ca2+-handling and lipid trafficking. ER-PM junctional architecture and plasticity associated with inter-membrane communication are as yet barely understood. Here, we introduce a method to precisely characterize ER-PM junction morphology and dynamics with high temporal resolution and minimal disturbance of junctional intermembrane communication. We show that expression of soluble cytosolic fluorophores in combination with TIRFM enables to delineate ER and PM distance in the range of 10-150 nm. Live-cell imaging of sub-plasmalemmal structures in RBL-2H3 mast cells by this method, designated as fluorescence density mapping (FDM), revealed profound dynamics of ER-PM contact sites in response to store-depletion. We report the existence of a Ca2+-dependent process that expands the junctional ER to enlarge its contact surface with the PM, thereby promoting and stabilizing STIM1-Orai1 competent ER-PM junctions.
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Affiliation(s)
- Michael Poteser
- Institute of Biophysics, Medical University of Graz, Harrachgasse 21/4, 8010 Graz, Austria
| | - Gerd Leitinger
- Institute of Cell Biology, Histology and Embryology Research Unit "Electron Microscopic Techniques", Medical University of Graz, Harrachgasse 21/7, 8010 Graz, Austria
| | - Elisabeth Pritz
- Institute of Cell Biology, Histology and Embryology Research Unit "Electron Microscopic Techniques", Medical University of Graz, Harrachgasse 21/7, 8010 Graz, Austria
| | - Dieter Platzer
- Institute of Biophysics, Medical University of Graz, Harrachgasse 21/4, 8010 Graz, Austria
| | - Irene Frischauf
- Institute of Biophysics, Johannes Kepler University of Linz, Austria, Gruberstrasse 40, 4020 Linz, Austria
| | - Christoph Romanin
- Institute of Biophysics, Johannes Kepler University of Linz, Austria, Gruberstrasse 40, 4020 Linz, Austria
| | - Klaus Groschner
- Institute of Biophysics, Medical University of Graz, Harrachgasse 21/4, 8010 Graz, Austria
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15
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Ang WG, Church AM, Kulis M, Choi HW, Burks AW, Abraham SN. Mast cell desensitization inhibits calcium flux and aberrantly remodels actin. J Clin Invest 2016; 126:4103-4118. [PMID: 27669462 PMCID: PMC5096925 DOI: 10.1172/jci87492] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Accepted: 08/16/2016] [Indexed: 11/17/2022] Open
Abstract
Rush desensitization (DS) is a widely used and effective clinical strategy for the rapid inhibition of IgE-mediated anaphylactic responses. However, the cellular targets and underlying mechanisms behind this process remain unclear. Recent studies have implicated mast cells (MCs) as the primary target cells for DS. Here, we developed a murine model of passive anaphylaxis with demonstrated MC involvement and an in vitro assay to evaluate the effect of DS on MCs. In contrast with previous reports, we determined that functional IgE remains on the cell surface of desensitized MCs following DS. Despite notable reductions in MC degranulation following DS, the high-affinity IgE receptor FcεRI was still capable of transducing signals in desensitized MCs. Additionally, we found that displacement of the actin cytoskeleton and its continued association with FcεRI impede the capacity of desensitized MCs to evoke the calcium response that is essential for MC degranulation. Together, these findings suggest that reduced degranulation responses in desensitized MCs arise from aberrant actin remodeling, providing insights that may lead to improvement of DS treatments for anaphylactic responses.
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Affiliation(s)
- W.X. Gladys Ang
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, USA
| | - Alison M. Church
- GlaxoSmithKline, Rare Diseases Unit, Research Triangle Park, North Carolina, USA
| | - Mike Kulis
- Department of Pediatrics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | | | - A. Wesley Burks
- Department of Pediatrics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Soman N. Abraham
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, USA
- Department of Pathology and
- Department of Immunology, Duke University Medical Center, Durham, North Carolina, USA
- Program in Emerging Infectious Diseases, Duke–National University of Singapore, Singapore
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16
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New Regulatory Roles of Galectin-3 in High-Affinity IgE Receptor Signaling. Mol Cell Biol 2016; 36:1366-82. [PMID: 26929198 DOI: 10.1128/mcb.00064-16] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Accepted: 02/16/2016] [Indexed: 01/18/2023] Open
Abstract
Aggregation of the high-affinity receptor for IgE (FcεRI) in mast cells initiates activation events that lead to degranulation and release of inflammatory mediators. To better understand the signaling pathways and genes involved in mast cell activation, we developed a high-throughput mast cell degranulation assay suitable for RNA interference experiments using lentivirus-based short hairpin RNA (shRNA) delivery. We tested 432 shRNAs specific for 144 selected genes for effects on FcεRI-mediated mast cell degranulation and identified 15 potential regulators. In further studies, we focused on galectin-3 (Gal3), identified in this study as a negative regulator of mast cell degranulation. FcεRI-activated cells with Gal3 knockdown exhibited upregulated tyrosine phosphorylation of spleen tyrosine kinase and several other signal transduction molecules and enhanced calcium response. We show that Gal3 promotes internalization of IgE-FcεRI complexes; this may be related to our finding that Gal3 is a positive regulator of FcεRI ubiquitination. Furthermore, we found that Gal3 facilitates mast cell adhesion and motility on fibronectin but negatively regulates antigen-induced chemotaxis. The combined data indicate that Gal3 is involved in both positive and negative regulation of FcεRI-mediated signaling events in mast cells.
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17
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GIT1/βPIX signaling proteins and PAK1 kinase regulate microtubule nucleation. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2016; 1863:1282-97. [PMID: 27012601 DOI: 10.1016/j.bbamcr.2016.03.016] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Revised: 03/14/2016] [Accepted: 03/18/2016] [Indexed: 12/13/2022]
Abstract
Microtubule nucleation from γ-tubulin complexes, located at the centrosome, is an essential step in the formation of the microtubule cytoskeleton. However, the signaling mechanisms that regulate microtubule nucleation in interphase cells are largely unknown. In this study, we report that γ-tubulin is in complexes containing G protein-coupled receptor kinase-interacting protein 1 (GIT1), p21-activated kinase interacting exchange factor (βPIX), and p21 protein (Cdc42/Rac)-activated kinase 1 (PAK1) in various cell lines. Immunofluorescence microscopy revealed association of GIT1, βPIX and activated PAK1 with centrosomes. Microtubule regrowth experiments showed that depletion of βPIX stimulated microtubule nucleation, while depletion of GIT1 or PAK1 resulted in decreased nucleation in the interphase cells. These data were confirmed for GIT1 and βPIX by phenotypic rescue experiments, and counting of new microtubules emanating from centrosomes during the microtubule regrowth. The importance of PAK1 for microtubule nucleation was corroborated by the inhibition of its kinase activity with IPA-3 inhibitor. GIT1 with PAK1 thus represent positive regulators, and βPIX is a negative regulator of microtubule nucleation from the interphase centrosomes. The regulatory roles of GIT1, βPIX and PAK1 in microtubule nucleation correlated with recruitment of γ-tubulin to the centrosome. Furthermore, in vitro kinase assays showed that GIT1 and βPIX, but not γ-tubulin, serve as substrates for PAK1. Finally, direct interaction of γ-tubulin with the C-terminal domain of βPIX and the N-terminal domain of GIT1, which targets this protein to the centrosome, was determined by pull-down experiments. We propose that GIT1/βPIX signaling proteins with PAK1 kinase represent a novel regulatory mechanism of microtubule nucleation in interphase cells.
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18
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Bugajev V, Halova I, Draberova L, Bambouskova M, Potuckova L, Draberova H, Paulenda T, Junyent S, Draber P. Negative regulatory roles of ORMDL3 in the FcεRI-triggered expression of proinflammatory mediators and chemotactic response in murine mast cells. Cell Mol Life Sci 2016; 73:1265-85. [PMID: 26407610 PMCID: PMC11108389 DOI: 10.1007/s00018-015-2047-3] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2015] [Revised: 08/19/2015] [Accepted: 09/17/2015] [Indexed: 10/23/2022]
Abstract
Single-nucleotide polymorphism studies have linked the chromosome 17q12-q21 region, where the human orosomucoid-like (ORMDL)3 gene is localized, to the risk of asthma and several other inflammatory diseases. Although mast cells are involved in the development of these diseases, the contribution of ORMDL3 to the mast cell physiology is unknown. In this study, we examined the role of ORMDL3 in antigen-induced activation of murine mast cells with reduced or enhanced ORMDL3 expression. Our data show that in antigen-activated mast cells, reduced expression of the ORMDL3 protein had no effect on degranulation and calcium response, but significantly enhanced phosphorylation of AKT kinase at Ser 473 followed by enhanced phosphorylation and degradation of IκBα and translocation of the NF-κB p65 subunit into the nucleus. These events were associated with an increased expression of proinflammatory cytokines (TNF-α, IL-6, and IL-13), chemokines (CCL3 and CCL4), and cyclooxygenase-2 dependent synthesis of prostaglandin D2. Antigen-mediated chemotaxis was also enhanced in ORMDL3-deficient cells, whereas spreading on fibronectin was decreased. On the other hand, increased expression of ORMDL3 had no significant effect on the studied signaling events, except for reduced antigen-mediated chemotaxis. These data were corroborated by increased IgE-antigen-dependent passive cutaneous anaphylaxis in mice with locally silenced ORMDL3 using short interfering RNAs. Our data also show that antigen triggers suppression of ORMDL3 expression in the mast cells. In summary, we provide evidence that downregulation of ORMDL3 expression in mast cells enhances AKT and NF-κB-directed signaling pathways and chemotaxis and contributes to the development of mast cell-mediated local inflammation in vivo.
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Affiliation(s)
- Viktor Bugajev
- Department of Signal Transduction, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, v.v.i., Videnska 1083, 142 20, Prague 4, Czech Republic
| | - Ivana Halova
- Department of Signal Transduction, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, v.v.i., Videnska 1083, 142 20, Prague 4, Czech Republic
| | - Lubica Draberova
- Department of Signal Transduction, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, v.v.i., Videnska 1083, 142 20, Prague 4, Czech Republic
| | - Monika Bambouskova
- Department of Signal Transduction, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, v.v.i., Videnska 1083, 142 20, Prague 4, Czech Republic
| | - Lucie Potuckova
- Department of Signal Transduction, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, v.v.i., Videnska 1083, 142 20, Prague 4, Czech Republic
| | - Helena Draberova
- Department of Signal Transduction, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, v.v.i., Videnska 1083, 142 20, Prague 4, Czech Republic
| | - Tomas Paulenda
- Department of Signal Transduction, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, v.v.i., Videnska 1083, 142 20, Prague 4, Czech Republic
| | - Sergi Junyent
- Department of Signal Transduction, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, v.v.i., Videnska 1083, 142 20, Prague 4, Czech Republic
| | - Petr Draber
- Department of Signal Transduction, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, v.v.i., Videnska 1083, 142 20, Prague 4, Czech Republic.
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19
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Overexpression and Nucleolar Localization of γ-Tubulin Small Complex Proteins GCP2 and GCP3 in Glioblastoma. J Neuropathol Exp Neurol 2015; 74:723-42. [PMID: 26079448 DOI: 10.1097/nen.0000000000000212] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
The expression, cellular distribution, and subcellular sorting of the microtubule (MT)-nucleating γ-tubulin small complex (γTuSC) proteins, GCP2 and GCP3, were studied in human glioblastoma cell lines and in clinical tissue samples representing all histologic grades of adult diffuse astrocytic gliomas (n = 54). Quantitative real-time polymerase chain reaction revealed a significant increase in the expression of GCP2 and GCP3 transcripts in glioblastoma cells versus normal human astrocytes; these were associated with higher amounts of both γTuSC proteins. GCP2 and GCP3 were concentrated in the centrosomes in interphase glioblastoma cells, but punctate and diffuse localizations were also detected in the cytosol and nuclei/nucleoli. Nucleolar localization was fixation dependent. GCP2 and GCP3 formed complexes with γ-tubulin in the nucleoli as confirmed by reciprocal immunoprecipitation experiments and immunoelectron microscopy. GCP2 and GCP3 depletion caused accumulation of cells in G2/M and mitotic delay but did not affect nucleolar integrity. Overexpression of GCP2 antagonized the inhibitory effect of the CDK5 regulatory subunit-associated tumor suppressor protein 3 (C53) on DNA damage G2/M checkpoint activity. Tumor cell GCP2 and GCP3 immunoreactivity was significantly increased over that in normal brains in glioblastoma samples; it was also associated with microvascular proliferation. These findings suggest that γTuSC protein dysregulation in glioblastomas may be linked to altered transcriptional checkpoint activity or interaction with signaling pathways associated with a malignant phenotype.
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20
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Abstract
Aggregation of the high-affinity IgE receptor (FcεRI) on the plasma membrane of mast cells and basophils initiates signaling events leading to a rapid release of preformed inflammatory mediators from secretory granules, and overall changes in cell morphology. Mast cell activation also causes reorganization of cytoskeletal components associated with membrane ruffling, spreading, and migration. Here we describe methods used for visualization of mast cell cytoskeleton, focusing on its two major components, microfilaments and microtubules, and their changes after cell triggering.
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21
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Mast cells in airway diseases and interstitial lung disease. Eur J Pharmacol 2015; 778:125-38. [PMID: 25959386 DOI: 10.1016/j.ejphar.2015.04.046] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Revised: 04/01/2015] [Accepted: 04/07/2015] [Indexed: 12/31/2022]
Abstract
Mast cells are major effector cells of inflammation and there is strong evidence that mast cells play a significant role in asthma pathophysiology. There is also a growing body of evidence that mast cells contribute to other inflammatory and fibrotic lung diseases such as chronic obstructive pulmonary disease and idiopathic pulmonary fibrosis. This review discusses the role that mast cells play in airway diseases and highlights how mast cell microlocalisation within specific lung compartments and their cellular interactions are likely to be critical for their effector function in disease.
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22
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Draber P, Halova I, Polakovicova I, Kawakami T. Signal transduction and chemotaxis in mast cells. Eur J Pharmacol 2015; 778:11-23. [PMID: 25941081 DOI: 10.1016/j.ejphar.2015.02.057] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Revised: 02/09/2015] [Accepted: 02/17/2015] [Indexed: 01/08/2023]
Abstract
Mast cells play crucial roles in both innate and adaptive arms of the immune system. Along with basophils, mast cells are essential effector cells for allergic inflammation that causes asthma, allergic rhinitis, food allergy and atopic dermatitis. Mast cells are usually increased in inflammatory sites of allergy and, upon activation, release various chemical, lipid, peptide and protein mediators of allergic reactions. Since antigen/immunoglobulin E (IgE)-mediated activation of these cells is a central event to trigger allergic reactions, innumerable studies have been conducted on how these cells are activated through cross-linking of the high-affinity IgE receptor (FcεRI). Development of mature mast cells from their progenitor cells is under the influence of several growth factors, of which the stem cell factor (SCF) seems to be the most important. Therefore, how SCF induces mast cell development and activation via its receptor, KIT, has been studied extensively, including a cross-talk between KIT and FcεRI signaling pathways. Although our understanding of the signaling mechanisms of the FcεRI and KIT pathways is far from complete, pharmaceutical applications of the knowledge about these pathways are underway. This review will focus on recent progresses in FcεRI and KIT signaling and chemotaxis.
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Affiliation(s)
- Petr Draber
- Department of Signal Transduction, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, CZ 14220 Prague, Czech Republic.
| | - Ivana Halova
- Department of Signal Transduction, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, CZ 14220 Prague, Czech Republic
| | - Iva Polakovicova
- Department of Signal Transduction, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, CZ 14220 Prague, Czech Republic
| | - Toshiaki Kawakami
- Division of Cell Biology, La Jolla Institute for Allergy and Immunology, 9420 Athena Circle La Jolla, CA 92037, USA; Laboratory for Allergic Disease, RIKEN Center for Integrative Medical Sciences (IMS-RCAI), Yokohama 230-0045, Japan
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23
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Sulimenko V, Hájková Z, Černohorská M, Sulimenko T, Sládková V, Dráberová L, Vinopal S, Dráberová E, Dráber P. Microtubule Nucleation in Mouse Bone Marrow–Derived Mast Cells Is Regulated by the Concerted Action of GIT1/βPIX Proteins and Calcium. THE JOURNAL OF IMMUNOLOGY 2015; 194:4099-111. [DOI: 10.4049/jimmunol.1402459] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Accepted: 02/27/2015] [Indexed: 11/19/2022]
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24
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Transmembrane adaptor protein PAG/CBP is involved in both positive and negative regulation of mast cell signaling. Mol Cell Biol 2014; 34:4285-300. [PMID: 25246632 DOI: 10.1128/mcb.00983-14] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The transmembrane adaptor protein PAG/CBP (here, PAG) is expressed in multiple cell types. Tyrosine-phosphorylated PAG serves as an anchor for C-terminal SRC kinase, an inhibitor of SRC-family kinases. The role of PAG as a negative regulator of immunoreceptor signaling has been examined in several model systems, but no functions in vivo have been determined. Here, we examined the activation of bone marrow-derived mast cells (BMMCs) with PAG knockout and PAG knockdown and the corresponding controls. Our data show that PAG-deficient BMMCs exhibit impaired antigen-induced degranulation, extracellular calcium uptake, tyrosine phosphorylation of several key signaling proteins (including the high-affinity IgE receptor subunits, spleen tyrosine kinase, and phospholipase C), production of several cytokines and chemokines, and chemotaxis. The enzymatic activities of the LYN and FYN kinases were increased in nonactivated cells, suggesting the involvement of a LYN- and/or a FYN-dependent negative regulatory loop. When BMMCs from PAG-knockout mice were activated via the KIT receptor, enhanced degranulation and tyrosine phosphorylation of the receptor were observed. In vivo experiments showed that PAG is a positive regulator of passive systemic anaphylaxis. The combined data indicate that PAG can function as both a positive and a negative regulator of mast cell signaling, depending upon the signaling pathway involved.
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25
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Multiple regulatory roles of the mouse transmembrane adaptor protein NTAL in gene transcription and mast cell physiology. PLoS One 2014; 9:e105539. [PMID: 25153696 PMCID: PMC4143283 DOI: 10.1371/journal.pone.0105539] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2014] [Accepted: 07/21/2014] [Indexed: 12/11/2022] Open
Abstract
Non-T cell activation linker (NTAL; also called LAB or LAT2) is a transmembrane adaptor protein that is expressed in a subset of hematopoietic cells, including mast cells. There are conflicting reports on the role of NTAL in the high affinity immunoglobulin E receptor (FcεRI) signaling. Studies carried out on mast cells derived from mice with NTAL knock out (KO) and wild type mice suggested that NTAL is a negative regulator of FcεRI signaling, while experiments with RNAi-mediated NTAL knockdown (KD) in human mast cells and rat basophilic leukemia cells suggested its positive regulatory role. To determine whether different methodologies of NTAL ablation (KO vs KD) have different physiological consequences, we compared under well defined conditions FcεRI-mediated signaling events in mouse bone marrow-derived mast cells (BMMCs) with NTAL KO or KD. BMMCs with both NTAL KO and KD exhibited enhanced degranulation, calcium mobilization, chemotaxis, tyrosine phosphorylation of LAT and ERK, and depolymerization of filamentous actin. These data provide clear evidence that NTAL is a negative regulator of FcεRI activation events in murine BMMCs, independently of possible compensatory developmental alterations. To gain further insight into the role of NTAL in mast cells, we examined the transcriptome profiles of resting and antigen-activated NTAL KO, NTAL KD, and corresponding control BMMCs. Through this analysis we identified several genes that were differentially regulated in nonactivated and antigen-activated NTAL-deficient cells, when compared to the corresponding control cells. Some of the genes seem to be involved in regulation of cholesterol-dependent events in antigen-mediated chemotaxis. The combined data indicate multiple regulatory roles of NTAL in gene expression and mast cell physiology.
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26
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Masi G, Mercati D, Vannuccini E, Paccagnini E, Riparbelli MG, Lupetti P, Pelicci PG, Baldari CT, Ulivieri C. p66Shc regulates vesicle-mediated secretion in mast cells by affecting F-actin dynamics. J Leukoc Biol 2013; 95:285-92. [DOI: 10.1189/jlb.0313178] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
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27
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Quantification of α-tubulin isotypes by sandwich ELISA with signal amplification through biotinyl-tyramide or immuno-PCR. J Immunol Methods 2013; 395:63-70. [DOI: 10.1016/j.jim.2013.07.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2013] [Revised: 07/02/2013] [Accepted: 07/02/2013] [Indexed: 11/17/2022]
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28
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Bar-Gill AB, Efergan A, Seger R, Fukuda M, Sagi-Eisenberg R. The extra-cellular signal regulated kinases ERK1 and ERK2 segregate displaying distinct spatiotemporal characteristics in activated mast cells. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1833:2070-82. [PMID: 23651922 DOI: 10.1016/j.bbamcr.2013.04.016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Revised: 04/27/2013] [Accepted: 04/29/2013] [Indexed: 11/26/2022]
Abstract
ERK1 and ERK2 are highly homologous isoforms that often play redundant roles in regulating cellular functions. We analyzed the spatiotemporal patterns of ERK1 and ERK2 in resting and activated mast cells. Strikingly, we identified distinct pathways for these kinases. ERK1 localized to the cytosol and translocated to the nucleus upon cell activation and kinase phosphorylation. In contrast, ERK2 distributed between the cytosol and near the microtubule organizing center (MTOC) in resting cells and accumulated further at a pericentrosomal region upon cell trigger. Pericentrosomal accumulation of ERK2 was phosphorylation independent, required an intact microtubule network and was significantly enhanced by the overexpression of Neuronal Calcium Sensor-1 (NCS-1). We also identified γ-tubulin and phosphatidylinositol 4 kinaseβ (PI4Kβ), a downstream effector of NCS-1, as novel partner proteins of ERK2. Taken together, our results imply non-redundant functions of ERK1 and ERK2 in mast cells and implicate NCS-1 and PΙ4Κβ as regulators of ERK2 trafficking.
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Affiliation(s)
- Anat Benado Bar-Gill
- Department of Cell and Developmental Biology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
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29
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Srikanth S, Ribalet B, Gwack Y. Regulation of CRAC channels by protein interactions and post-translational modification. Channels (Austin) 2013; 7:354-63. [PMID: 23454861 DOI: 10.4161/chan.23801] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Store-operated Ca(2+) entry (SOCE) is a widespread mechanism to elevate the intracellular Ca(2+) concentrations and stimulate downstream signaling pathways affecting proliferation, secretion, differentiation and death in different cell types. In immune cells, immune receptor stimulation induces intracellular Ca(2+) store depletion that subsequently activates Ca(2+)-release-activated-Ca(2+) (CRAC) channels, a prototype of store-operated Ca(2+) (SOC) channels. CRAC channel opening leads to activation of diverse downstream signaling pathways affecting proliferation, differentiation, cytokine production and cell death. Recent identification of STIM1 as the endoplasmic reticulum Ca(2+) sensor and Orai1 as the pore subunit of CRAC channels has provided the much-needed molecular tools to dissect the mechanism of activation and regulation of CRAC channels. In this review, we discuss the recent advances in understanding the associating partners and posttranslational modifications of Orai1 and STIM1 proteins that regulate diverse aspects of CRAC channel function.
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Affiliation(s)
- Sonal Srikanth
- Department of Physiology; David Geffen School of Medicine at UCLA; Los Angeles, CA USA
| | - Bernard Ribalet
- Department of Physiology; David Geffen School of Medicine at UCLA; Los Angeles, CA USA
| | - Yousang Gwack
- Department of Physiology; David Geffen School of Medicine at UCLA; Los Angeles, CA USA
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30
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Hálová I, Dráberová L, Bambousková M, Machyna M, Stegurová L, Smrž D, Dráber P. Cross-talk between tetraspanin CD9 and transmembrane adaptor protein non-T cell activation linker (NTAL) in mast cell activation and chemotaxis. J Biol Chem 2013; 288:9801-9814. [PMID: 23443658 DOI: 10.1074/jbc.m112.449231] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Chemotaxis, a process leading to movement of cells toward increasing concentrations of chemoattractants, is essential, among others, for recruitment of mast cells within target tissues where they play an important role in innate and adaptive immunity. Chemotaxis is driven by chemoattractants, produced by various cell types, as well as by intrinsic cellular regulators, which are poorly understood. In this study we prepared a new mAb specific for the tetraspanin CD9. Binding of the antibody to bone marrow-derived mast cells triggered activation events that included cell degranulation, Ca(2+) response, dephosphorylation of ezrin/radixin/moesin (ERM) family proteins, and potent tyrosine phosphorylation of the non-T cell activation linker (NTAL) but only weak phosphorylation of the linker for activation of T cells (LAT). Phosphorylation of the NTAL was observed with whole antibody but not with its F(ab)(2) or Fab fragments. This indicated involvement of the Fcγ receptors. As documented by electron microscopy of isolated plasma membrane sheets, CD9 colocalized with the high-affinity IgE receptor (FcεRI) and NTAL but not with LAT. Further tests showed that both anti-CD9 antibody and its F(ab)(2) fragment inhibited mast cell chemotaxis toward antigen. Experiments with bone marrow-derived mast cells deficient in NTAL and/or LAT revealed different roles of these two adaptors in antigen-driven chemotaxis. The combined data indicate that chemotaxis toward antigen is controlled in mast cells by a cross-talk among FcεRI, tetraspanin CD9, transmembrane adaptor proteins NTAL and LAT, and cytoskeleton-regulatory proteins of the ERM family.
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Affiliation(s)
- Ivana Hálová
- Department of Signal Transduction, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, CZ 14220 Prague, Czech Republic
| | - Lubica Dráberová
- Department of Signal Transduction, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, CZ 14220 Prague, Czech Republic
| | - Monika Bambousková
- Department of Signal Transduction, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, CZ 14220 Prague, Czech Republic
| | - Martin Machyna
- Department of Signal Transduction, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, CZ 14220 Prague, Czech Republic
| | - Lucie Stegurová
- Department of Signal Transduction, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, CZ 14220 Prague, Czech Republic
| | - Daniel Smrž
- Department of Signal Transduction, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, CZ 14220 Prague, Czech Republic
| | - Petr Dráber
- Department of Signal Transduction, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, CZ 14220 Prague, Czech Republic.
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Schmid E, Gu S, Yang W, Münzer P, Schaller M, Lang F, Stournaras C, Shumilina E. Serum- and glucocorticoid-inducible kinase SGK1 regulates reorganization of actin cytoskeleton in mast cells upon degranulation. Am J Physiol Cell Physiol 2012; 304:C49-55. [PMID: 23015548 DOI: 10.1152/ajpcell.00179.2012] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Aggregation of the high-affinity IgE receptor (FcεRI) on mast cells (MCs) causes MC degranulation, a process that involves cortical F-actin disassembly. Actin depolymerization may be triggered by increase of cytosolic Ca(2+). Entry of Ca(2+) through the Ca(2+) release-activated Ca(2+) (CRAC) channels is under powerful regulation by the serum- and glucocorticoid-inducible kinase SGK1. Moreover, FcεRI-dependent degranulation is decreased in SGK1-deficient (sgk1(-/-)) MCs. The present study addressed whether SGK1 is required for actin cytoskeleton rearrangement in MCs and whether modulation of actin architecture could underlie decreased degranulation of sgk1(-/-) MCs. Confirming previous results, release of β-hexosaminidase reflecting FcεRI-dependent degranulation was impaired in sgk1(-/-) MCs compared with sgk1(+/+) MCs. When CRAC channels were inhibited by 2-aminoethoxydiphenyl borate (2-APB; 50 μM), MC degranulation was strongly decreased in both sgk1(+/+) and sgk1(-/-) MCs and the difference between genotypes was abolished. Moreover, degranulation was impaired by actin-stabilizing (phallacidin) and enhanced by actin-disrupting (cytochalasin B) agents to a similar extent in sgk1(+/+) MCs and sgk1(-/-) MCs, implying a regulatory role of actin reorganization in this event. In line with this, measurements of monomeric (G) and filamentous (F) actin content by FACS analysis and Western blotting of detergent-soluble and -insoluble cell fractions indicated an increase of the G/F-actin ratio in sgk1(+/+) MCs but not in sgk1(-/-) MCs upon FcεRI ligation, an observation reflecting actin depolymerization. In sgk1(+/+) MCs, FcεRI-induced actin depolymerization was abolished by 2-APB. The observed actin reorganization was confirmed by confocal laser microscopic analysis. Our observations uncover SGK1-dependent Ca(2+) entry in mast cells as a novel mechanism regulating actin cytoskeleton.
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Affiliation(s)
- Evi Schmid
- Dept. of Physiology, University of Tübingen, Gmelinstr. 5, D-72072 Tübingen, Germany
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Store-independent pathways for cytosolic STIM1 clustering in the regulation of store-operated Ca(2+) influx. Biochem Pharmacol 2012; 84:1024-35. [PMID: 22842488 DOI: 10.1016/j.bcp.2012.07.013] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Revised: 07/08/2012] [Accepted: 07/16/2012] [Indexed: 02/07/2023]
Abstract
STIM1 is a Ca(2+) sensing molecule. Once the Ca(2+) stores are depleted, STIM1 moves towards the plasma membrane (PM) (translocation), forms puncta (clustering), and triggers store-operated Ca(2+) entry (SOCE). Although this process has been regarded as a main mechanism for store-operated Ca(2+) channel activation, the STIM1 clustering is still unclear. Here we discovered a new phenomenon of STIM1 clustering, which is not triggered by endoplasmic reticulum (ER) Ca(2+) depletion. STIM1 subplasmalemmal translocation and clustering can be induced by ER Ca(2+) store depletion with thapsigargin (TG), G-protein-coupled receptor activator trypsin and ryanodine receptor (RyR) agonists caffeine and 4-chloro-3-ethylphenol (4-CEP) in the HEK293 cells stably transfected with STIM1-EYFP. The STIM1 clustering induced by TG was more sustained than that induced by trypsin and RyR agonists. Interestingly, 4-CEP-induced STIM1 clustering also happened in the cytosol without ER Ca(2+) store depletion. Application of some pharmacological regulators including flufenamic acid, 2-APB, and carbonyl cyanide 4-(trifluoromethoxy)phenylhydrazone (FCCP) at concentrations without affecting ER Ca(2+) store also evoked cytosolic STIM1 clustering. However, the direct store-operated ORAI channel blockers (SKF-96365, Gd(3+) and diethylstilbestrol) or the signaling pathway inhibitors (genistein, wortmannin, Y-27632, forskolin and GF109203X) did not change the STIM1 movement. Disruption of cytoskeleton by colchicine and cytochalasin D also showed no effect on STIM1 movement. We concluded that STIM1 clustering and translocation are two dynamic processes that can be pharmacologically dissociated. The ER Ca(2+) store-independent mechanism for STIM1 clustering is a new alternative mechanism for regulating store-operated channel activity, which could act as a new pharmacological target.
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Halova I, Draberova L, Draber P. Mast cell chemotaxis - chemoattractants and signaling pathways. Front Immunol 2012; 3:119. [PMID: 22654878 PMCID: PMC3360162 DOI: 10.3389/fimmu.2012.00119] [Citation(s) in RCA: 125] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2012] [Accepted: 04/24/2012] [Indexed: 01/09/2023] Open
Abstract
Migration of mast cells is essential for their recruitment within target tissues where they play an important role in innate and adaptive immune responses. These processes rely on the ability of mast cells to recognize appropriate chemotactic stimuli and react to them by a chemotactic response. Another level of intercellular communication is attained by production of chemoattractants by activated mast cells, which results in accumulation of mast cells and other hematopoietic cells at the sites of inflammation. Mast cells express numerous surface receptors for various ligands with properties of potent chemoattractants. They include the stem cell factor (SCF) recognized by c-Kit, antigen, which binds to immunoglobulin E (IgE) anchored to the high affinity IgE receptor (FcεRI), highly cytokinergic (HC) IgE recognized by FcεRI, lipid mediator sphingosine-1-phosphate (S1P), which binds to G protein-coupled receptors (GPCRs). Other large groups of chemoattractants are eicosanoids [prostaglandin E2 and D2, leukotriene (LT) B4, LTD4, and LTC4, and others] and chemokines (CC, CXC, C, and CX3C), which also bind to various GPCRs. Further noteworthy chemoattractants are isoforms of transforming growth factor (TGF) β1–3, which are sensitively recognized by TGF-β serine/threonine type I and II β receptors, adenosine, C1q, C3a, and C5a components of the complement, 5-hydroxytryptamine, neuroendocrine peptide catestatin, tumor necrosis factor-α, and others. Here we discuss the major types of chemoattractants recognized by mast cells, their target receptors, as well as signaling pathways they utilize. We also briefly deal with methods used for studies of mast cell chemotaxis and with ways of how these studies profited from the results obtained in other cellular systems.
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Affiliation(s)
- Ivana Halova
- Department of Signal Transduction, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic Prague, Czech Republic
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Dráber P, Sulimenko V, Dráberová E. Cytoskeleton in mast cell signaling. Front Immunol 2012; 3:130. [PMID: 22654883 PMCID: PMC3360219 DOI: 10.3389/fimmu.2012.00130] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2012] [Accepted: 05/05/2012] [Indexed: 11/13/2022] Open
Abstract
Mast cell activation mediated by the high affinity receptor for IgE (FcεRI) is a key event in allergic response and inflammation. Other receptors on mast cells, as c-Kit for stem cell factor and G protein-coupled receptors (GPCRs) synergistically enhance the FcεRI-mediated release of inflammatory mediators. Activation of various signaling pathways in mast cells results in changes in cell morphology, adhesion to substrate, exocytosis, and migration. Reorganization of cytoskeleton is pivotal in all these processes. Cytoskeletal proteins also play an important role in initial stages of FcεRI and other surface receptors induced triggering. Highly dynamic microtubules formed by αβ-tubulin dimers as well as microfilaments build up from polymerized actin are affected in activated cells by kinases/phosphatases, Rho GTPases and changes in concentration of cytosolic Ca(2+). Also important are nucleation proteins; the γ-tubulin complexes in case of microtubules or Arp 2/3 complex with its nucleation promoting factors and formins in case of microfilaments. The dynamic nature of microtubules and microfilaments in activated cells depends on many associated/regulatory proteins. Changes in rigidity of activated mast cells reflect changes in intermediate filaments build up from vimentin. This review offers a critical appraisal of current knowledge on the role of cytoskeleton in mast cells signaling.
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Affiliation(s)
- Pavel Dráber
- Department of Biology of Cytoskeleton, Institute of Molecular Genetics, Academy of Sciences of the Czech RepublicPrague, Czech Republic
| | - Vadym Sulimenko
- Department of Biology of Cytoskeleton, Institute of Molecular Genetics, Academy of Sciences of the Czech RepublicPrague, Czech Republic
| | - Eduarda Dráberová
- Department of Biology of Cytoskeleton, Institute of Molecular Genetics, Academy of Sciences of the Czech RepublicPrague, Czech Republic
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γ-Tubulin 2 nucleates microtubules and is downregulated in mouse early embryogenesis. PLoS One 2012; 7:e29919. [PMID: 22235350 PMCID: PMC3250491 DOI: 10.1371/journal.pone.0029919] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2011] [Accepted: 12/06/2011] [Indexed: 01/09/2023] Open
Abstract
γ-Tubulin is the key protein for microtubule nucleation. Duplication of the γ-tubulin gene occurred several times during evolution, and in mammals γ-tubulin genes encode proteins which share ∼97% sequence identity. Previous analysis of Tubg1 and Tubg2 knock-out mice has suggested that γ-tubulins are not functionally equivalent. Tubg1 knock-out mice died at the blastocyst stage, whereas Tubg2 knock-out mice developed normally and were fertile. It was proposed that γ-tubulin 1 represents ubiquitous γ-tubulin, while γ-tubulin 2 may have some specific functions and cannot substitute for γ-tubulin 1 deficiency in blastocysts. The molecular basis of the suggested functional difference between γ-tubulins remains unknown. Here we show that exogenous γ-tubulin 2 is targeted to centrosomes and interacts with γ-tubulin complex proteins 2 and 4. Depletion of γ-tubulin 1 by RNAi in U2OS cells causes impaired microtubule nucleation and metaphase arrest. Wild-type phenotype in γ-tubulin 1-depleted cells is restored by expression of exogenous mouse or human γ-tubulin 2. Further, we show at both mRNA and protein levels using RT-qPCR and 2D-PAGE, respectively, that in contrast to Tubg1, the Tubg2 expression is dramatically reduced in mouse blastocysts. This indicates that γ-tubulin 2 cannot rescue γ-tubulin 1 deficiency in knock-out blastocysts, owing to its very low amount. The combined data suggest that γ-tubulin 2 is able to nucleate microtubules and substitute for γ-tubulin 1. We propose that mammalian γ-tubulins are functionally redundant with respect to the nucleation activity.
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Shaw PJ, Feske S. Physiological and pathophysiological functions of SOCE in the immune system. Front Biosci (Elite Ed) 2012. [PMID: 22202035 DOI: 10.2741/540] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Calcium signals play a critical role in many cell-type specific effector functions during innate and adaptive immune responses. The predominant mechanism to raise intracellular (Ca²⁺) used by most immune cells is store-operated Ca²⁺ entry (SOCE), whereby the depletion of endoplasmic reticulum (ER) Ca²⁺ stores triggers the influx of extracellular Ca²⁺. SOCE in immune cells is mediated by the highly Ca²⁺ selective Ca²⁺-release-activated Ca²⁺ (CRAC) channel, encoded by ORAI1, ORAI2 and ORAI3 genes. ORAI proteins are activated by stromal interaction molecules (STIM) 1 and 2, which act as sensors of ER Ca²⁺ store depletion. The importance of SOCE mediated by STIM and ORAI proteins for immune function is evident from the immunodeficiency and autoimmunity in patients with mutations in STIM1 and ORAI1 genes. These patients and studies in gene-targeted mice have revealed an essential role for ORAI/STIM proteins in the function of several immune cells. This review focuses on recent advances made towards understanding the role of SOCE in immune cells with an emphasis on the immune dysregulation that results from defects in SOCE in human patients and transgenic mice.
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Affiliation(s)
- Patrick J Shaw
- Department of Pathology, New York University Langone Medical Center, New York, NY 10016, USA
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