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Nishad R, Betancourt-Solis M, Dey H, Heidelberger R, McNew JA. Regulation of Syntaxin3B-Mediated Membrane Fusion by T14, Munc18, and Complexin. Biomolecules 2023; 13:1463. [PMID: 37892145 PMCID: PMC10604575 DOI: 10.3390/biom13101463] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Revised: 09/22/2023] [Accepted: 09/26/2023] [Indexed: 10/29/2023] Open
Abstract
Retinal neurons that form ribbon-style synapses operate over a wide dynamic range, continuously relaying visual information to their downstream targets. The remarkable signaling abilities of these neurons are supported by specialized presynaptic machinery, one component of which is syntaxin3B. Syntaxin3B is an essential t-SNARE protein of photoreceptors and bipolar cells that is required for neurotransmitter release. It has a light-regulated phosphorylation site in its N-terminal domain at T14 that has been proposed to modulate membrane fusion. However, a direct test of the latter has been lacking. Using a well-controlled in vitro fusion assay, we found that a phosphomimetic T14 syntaxin3B mutation leads to a small but significant enhancement of SNARE-mediated membrane fusion following the formation of the t-SNARE complex. While the addition of Munc18a had only a minimal effect on membrane fusion mediated by SNARE complexes containing wild-type syntaxin3B, a more significant enhancement was observed in the presence of Munc18a when the SNARE complexes contained a syntaxin3B T14 phosphomimetic mutant. Finally, we showed that the retinal-specific complexins (Cpx III and Cpx IV) inhibited membrane fusion mediated by syntaxin3B-containing SNARE complexes in a dose-dependent manner. Collectively, our results establish that membrane fusion mediated by syntaxin3B-containing SNARE complexes is regulated by the T14 residue of syntaxin3B, Munc18a, and Cpxs III and IV.
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Affiliation(s)
- Rajkishor Nishad
- Department of BioSciences, Rice University, 6500 Main Street, MS 601, Houston, TX 77005, USA;
| | - Miguel Betancourt-Solis
- Department of BioSciences, Rice University, 6500 Main Street, MS 601, Houston, TX 77005, USA;
- Lonza Biologics, 14905 Kirby Dr, Houston, TX 77047, USA
| | - Himani Dey
- Department of Neurobiology and Anatomy, McGovern Medical School, The University of Texas Health Science Center, Houston (UTHealth Houston), 6431 Fannin Street, Houston, TX 77030, USA;
| | - Ruth Heidelberger
- Department of Neurobiology and Anatomy, McGovern Medical School, The University of Texas Health Science Center, Houston (UTHealth Houston), 6431 Fannin Street, Houston, TX 77030, USA;
| | - James A. McNew
- Department of BioSciences, Rice University, 6500 Main Street, MS 601, Houston, TX 77005, USA;
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Liu RJY, Al-Molieh Y, Chen SZ, Drobac M, Urban D, Chen CH, Yao HHY, Geng RSQ, Li L, Pluthero FG, Benlekbir S, Rubinstein JL, Kahr WHA. The Sec1/Munc18 protein VPS33B forms a uniquely bidirectional complex with VPS16B. J Biol Chem 2023; 299:104718. [PMID: 37062417 DOI: 10.1016/j.jbc.2023.104718] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2023] [Revised: 03/03/2023] [Accepted: 04/07/2023] [Indexed: 04/18/2023] Open
Abstract
Loss of function variants of VPS33B and VIPAS39 (encoding VPS16B) are causative for arthrogryposis, renal dysfunction and cholestasis (ARC) syndrome, where early lethality of patients indicates that VPS33B and VPS16B play essential cellular roles. VPS33B is a member of the Sec1/Munc18 (SM) protein family, and thus thought to facilitate vesicular fusion via interaction with SNARE complexes, as does its paralog VPS33A in the homotypic fusion and vacuole sorting (HOPS) complex. VPS33B and VPS16B have been shown to associate, but little is known about the composition, structure or function of the VPS33B/VPS16B complex. We show here that human VPS33B/VPS16B is a high molecular weight complex, which we expressed in yeast to obtain material for structural, composition and stability analysis. Circular dichroism data indicate VPS33B/VPS16B has a well-folded α-helical secondary structure, for which size exclusion chromatography-multi angle light scattering revealed a MW of ∼315 kDa. Quantitative immunoblotting indicated the complex has a VPS33B:VPS16B ratio of 2:3. Expression of ARC syndrome-causing VPS33B missense variants showed that L30P disrupts complex formation, but not S243F or H344D. Truncated VPS16B containing amino acids 143-316 was sufficient to form a complex with VPS33B. Small angle X-ray scattering and negative staining electron microscopy revealed a two-lobed shape for VPS33B/VPS16B. Avidin tagging indicated that each lobe contains a VPS33B molecule, and they are oriented in opposite directions. From this we propose a structure for VPS33B/VPS16B that allows the copies of VPS33B at each end to interact with separate SNARE bundles and/or SNAREpins, plus their associated membrane components. Thus our observations reveal the only known potentially bidirectional SM protein complex.
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Affiliation(s)
- Richard J Y Liu
- Department of Biochemistry, University of Toronto, Toronto, ON, M5S 1A8, Canada
| | - Yusef Al-Molieh
- Department of Biochemistry, University of Toronto, Toronto, ON, M5S 1A8, Canada
| | - Shao Z Chen
- Department of Biochemistry, University of Toronto, Toronto, ON, M5S 1A8, Canada
| | - Marko Drobac
- Department of Biochemistry, University of Toronto, Toronto, ON, M5S 1A8, Canada
| | - Denisa Urban
- Department of Biochemistry, University of Toronto, Toronto, ON, M5S 1A8, Canada
| | - Chang H Chen
- Department of Biochemistry, University of Toronto, Toronto, ON, M5S 1A8, Canada
| | - Helen H Y Yao
- Department of Biochemistry, University of Toronto, Toronto, ON, M5S 1A8, Canada
| | - Ryan S Q Geng
- Department of Biochemistry, University of Toronto, Toronto, ON, M5S 1A8, Canada
| | - Ling Li
- Cell Biology Program, Research Institute, Hospital for Sick Children, Toronto, ON, M5G 0A4, Canada
| | - Fred G Pluthero
- Cell Biology Program, Research Institute, Hospital for Sick Children, Toronto, ON, M5G 0A4, Canada
| | - Samir Benlekbir
- Molecular Medicine Program, Research Institute, Hospital for Sick Children, Toronto, ON, M5G 0A4, Canada
| | - John L Rubinstein
- Department of Biochemistry, University of Toronto, Toronto, ON, M5S 1A8, Canada; Molecular Medicine Program, Research Institute, Hospital for Sick Children, Toronto, ON, M5G 0A4, Canada
| | - Walter H A Kahr
- Department of Biochemistry, University of Toronto, Toronto, ON, M5S 1A8, Canada; Cell Biology Program, Research Institute, Hospital for Sick Children, Toronto, ON, M5G 0A4, Canada; Division of Haematology/Oncology, Department of Paediatrics, University of Toronto and The Hospital for Sick Children, Toronto, ON, M5G 1X8, Canada.
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3
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Adhikari P, Ayo TE, Vines JC, Sugita S, Xu H. Exocytic machineries differentially control mediator release from allergen-triggered RBL-2H3 cells. Inflamm Res 2023; 72:639-649. [PMID: 36725743 DOI: 10.1007/s00011-023-01698-z] [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: 10/02/2022] [Revised: 01/06/2023] [Accepted: 01/23/2023] [Indexed: 02/03/2023] Open
Abstract
BACKGROUND Mast cells utilize SNAREs (soluble-N-ethyl-maleimide sensitive factor attachment protein receptors) and SM (Sec1/Munc18) proteins to secrete/exocytose a variety of proinflammatory mediators. However, whether a common SNARE-SM machinery is responsible remains unclear. METHODS Four vesicle/granule-anchored SNAREs (VAMP2, VAMP3, VAMP7, and VAMP8) and two Munc18 homologs (Munc18a and Munc18b) were systematically knocked down or knocked out in RBL-2H3 mast cells and antigen-induced release of β-hexosaminidase, histamine, serotonin, and TNF was examined. Phenotypes were validated by rescue experiments. Immunofluorescence studies were performed to determine the subcellular distribution of key players. RESULTS The reduction of VAMP8 expression inhibited the exocytosis of β-hexosaminidase, histamine, and serotonin but not TNF. Unexpectedly, however, confocal microscopy revealed substantial co-localization between VAMP8 and TNF, and between TNF and serotonin. Meanwhile, the depletion of other VAMPs, including knockout of VAMP3, had no impact on the release of any of the mediators examined. On the other hand, TNF exocytosis was diminished specifically in stable Munc18bknockdown cells, in a fashion that was rescued by exogenous, RNAi-resistant Munc18b. In line with this, TNF was co-localized with Munc18b (47%) to a much greater extent than with Munc18a (13%). CONCLUSION Distinct exocytic pathways exist in mast cells for the release of different mediators.
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Affiliation(s)
- Pratikshya Adhikari
- Center for Molecular and Cellular Biosciences, School of Biological, Environmental, and Earth Sciences, University of Southern Mississippi, Hattiesburg, MS, 39406, USA
| | - Tolulope E Ayo
- Center for Molecular and Cellular Biosciences, School of Biological, Environmental, and Earth Sciences, University of Southern Mississippi, Hattiesburg, MS, 39406, USA
| | - John C Vines
- Center for Molecular and Cellular Biosciences, School of Biological, Environmental, and Earth Sciences, University of Southern Mississippi, Hattiesburg, MS, 39406, USA
| | - Shuzo Sugita
- Division of Fundamental Neurobiology, University Health Network, Toronto, ON, M5T 2S8, Canada
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON, M5S 1A8, Canada
| | - Hao Xu
- Center for Molecular and Cellular Biosciences, School of Biological, Environmental, and Earth Sciences, University of Southern Mississippi, Hattiesburg, MS, 39406, USA.
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Puntman DC, Arora S, Farina M, Toonen RF, Verhage M. Munc18-1 Is Essential for Neuropeptide Secretion in Neurons. J Neurosci 2021; 41:5980-5993. [PMID: 34103363 PMCID: PMC8276746 DOI: 10.1523/jneurosci.3150-20.2021] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 04/29/2021] [Accepted: 05/03/2021] [Indexed: 11/21/2022] Open
Abstract
Neuropeptide secretion from dense-core vesicles (DCVs) controls many brain functions. Several components of the DCV exocytosis machinery have recently been identified, but the participation of a SEC1/MUNC18 (SM) protein has remained elusive. Here, we tested the ability of the three exocytic SM proteins expressed in the mammalian brain, MUNC18-1/2/3, to support neuropeptide secretion. We quantified DCV exocytosis at a single vesicle resolution on action potential (AP) train-stimulation in mouse CNS neurons (of unknown sex) using pHluorin-tagged and/or mCherry-tagged neuropeptide Y (NPY) or brain-derived neurotrophic factor (BDNF). Conditional inactivation of Munc18-1 abolished all DCV exocytosis. Expression of MUNC18-1, but not MUNC18-2 or MUNC18-3, supported DCV exocytosis in Munc18-1 null neurons. Heterozygous (HZ) inactivation of Munc18-1, as a model for reduced MUNC18-1 expression, impaired DCV exocytosis, especially during the initial phase of train-stimulation, when the release was maximal. These data show that neurons critically and selectively depend on MUNC18-1 for neuropeptide secretion. Impaired neuropeptide secretion may explain aspects of the behavioral and neurodevelopmental phenotypes that were observed in Munc18-1 HZ mice.SIGNIFICANCE STATEMENT Neuropeptide secretion from dense-core vesicles (DCVs) modulates synaptic transmission, sleep, appetite, cognition and mood. However, the mechanisms of DCV exocytosis are poorly characterized. Here, we identify MUNC18-1 as an essential component for neuropeptide secretion from DCVs. Paralogs MUNC18-2 or MUNC18-3 cannot compensate for MUNC18-1. MUNC18-1 is the first protein identified to be essential for both neuropeptide secretion and synaptic transmission. In heterozygous (HZ) Munc18-1 neurons, that have a 50% reduced MUNC18-1expression and model the human STXBP1 syndrome, DCV exocytosis is impaired, especially during the initial phase of train-stimulation, when the release is maximal. These data show that MUNC18-1 is essential for neuropeptide secretion and that impaired neuropeptide secretion on reduced MUNC18-1expression may contribute to the symptoms of STXBP1 syndrome.
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Affiliation(s)
- Daniël C Puntman
- Section Functional genomics, Department of Clinical Genetics, Center for Neurogenomics and Cognitive Research, Universitair Medisch Centrum, Amsterdam1081 HV, The Netherlands
| | - Swati Arora
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research, Vrije Universiteit Amsterdam, Amsterdam1081 HV, The Netherlands
| | - Margherita Farina
- Section Functional genomics, Department of Clinical Genetics, Center for Neurogenomics and Cognitive Research, Universitair Medisch Centrum, Amsterdam1081 HV, The Netherlands
| | - Ruud F Toonen
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research, Vrije Universiteit Amsterdam, Amsterdam1081 HV, The Netherlands
| | - Matthijs Verhage
- Section Functional genomics, Department of Clinical Genetics, Center for Neurogenomics and Cognitive Research, Universitair Medisch Centrum, Amsterdam1081 HV, The Netherlands
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research, Vrije Universiteit Amsterdam, Amsterdam1081 HV, The Netherlands
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5
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Blank U, Huang H, Kawakami T. The high affinity IgE receptor: a signaling update. Curr Opin Immunol 2021; 72:51-58. [PMID: 33838574 DOI: 10.1016/j.coi.2021.03.015] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Accepted: 03/22/2021] [Indexed: 01/01/2023]
Abstract
Here we update receptor proximal and distant signaling events of the mast cell high affinity IgE receptor (FcεRI) launching immediate type I hypersensitivity and an inflammatory cytokine-chemokine cascade. Different physiologic antigen concentrations, their affinity, and valency for the IgE ligand produce distinct intracellular signaling events with different outcomes. Investigating mast cell degranulation has revealed a complex molecular machinery that relays proximal signaling to cytoskeletal reorganization, granule transport and membrane fusion. Several new phosphorylation- and calcium-responsive effectors have been described. FcεRI signaling also promotes de novo gene transcription. Recent progress has identified enhancers at genes that are upregulated in mast cells after stimulation through FcεRI using next generation sequencing methods. Enhancers at genes that respond to antigenic stimulation in human mast cells revealed Ca2+-dependency. Stimulation-responsive super enhancers in mouse mast cells have also been identified. Mast cell lineage-determining transcription factor GATA2 primes these enhancers to respond to antigenic stimulation.
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Affiliation(s)
- Ulrich Blank
- Université de Paris, Centre de Recherche sur l'Inflammation, INSERM UMR1149, CNRS ERL8252, Faculté de Médecine site Bichat, Paris, France; Laboratoire d'Excellence Inflamex, Paris, France.
| | - Hua Huang
- Department of Immunology and Genomic Medicine, National Jewish Health, Denver, CO 80206, USA; Department of Immunology and Microbiology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Toshiaki Kawakami
- Laboratory of Allergic Diseases, Center for Autoimmunity and Inflammation, La Jolla Institute for Immunology, La Jolla, CA 92037, USA; Department of Dermatology, School of Medicine, University of California San Diego, La Jolla, CA 92093, USA
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6
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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: 17] [Impact Index Per Article: 5.7] [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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SNAP23 is essential for platelet and mast cell development and required in connective tissue mast cells for anaphylaxis. J Biol Chem 2021; 296:100268. [PMID: 33837726 PMCID: PMC7948755 DOI: 10.1016/j.jbc.2021.100268] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Revised: 12/31/2020] [Accepted: 01/06/2021] [Indexed: 11/23/2022] Open
Abstract
Degranulation, a fundamental effector response from mast cells (MCs) and platelets, is an example of regulated exocytosis. This process is mediated by SNARE proteins and their regulators. We have previously shown that several of these proteins are essential for exocytosis in MCs and platelets. Here, we assessed the role of the SNARE protein SNAP23 using conditional knockout mice, in which SNAP23 was selectively deleted from either the megakaryocyte/platelet or connective tissue MC lineages. We found that removal of SNAP23 in platelets results in severe defects in degranulation of all three platelet secretory granule types, i.e., alpha, dense, and lysosomal granules. The mutation also induces thrombocytopenia, abnormal platelet morphology and activation, and reduction in the number of alpha granules. Therefore, the degranulation defect might not be secondary to an intrinsic failure of the machinery mediating regulated exocytosis in platelets. When we removed SNAP23 expression in MCs, there was a complete developmental failure in vitro and in vivo. The developmental defects in platelets and MCs and the abnormal translocation of membrane proteins to the surface of platelets indicate that SNAP23 is also involved in constitutive exocytosis in these cells. The MC conditional deletant animals lacked connective tissue MCs, but their mucosal MCs were normal and expanded in response to an antigenic stimulus. We used this mouse to show that connective tissue MCs are required and mucosal MCs are not sufficient for an anaphylactic response.
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8
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Tang BL. SNAREs and developmental disorders. J Cell Physiol 2020; 236:2482-2504. [PMID: 32959907 DOI: 10.1002/jcp.30067] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 08/20/2020] [Accepted: 09/09/2020] [Indexed: 12/12/2022]
Abstract
Members of the soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) family mediate membrane fusion processes associated with vesicular trafficking and autophagy. SNAREs mediate core membrane fusion processes essential for all cells, but some SNAREs serve cell/tissue type-specific exocytic/endocytic functions, and are therefore critical for various aspects of embryonic development. Mutations or variants of their encoding genes could give rise to developmental disorders, such as those affecting the nervous system and immune system in humans. Mutations to components in the canonical synaptic vesicle fusion SNARE complex (VAMP2, STX1A/B, and SNAP25) and a key regulator of SNARE complex formation MUNC18-1, produce variant phenotypes of autism, intellectual disability, movement disorders, and epilepsy. STX11 and MUNC18-2 mutations underlie 2 subtypes of familial hemophagocytic lymphohistiocytosis. STX3 mutations contribute to variant microvillus inclusion disease. Chromosomal microdeletions involving STX16 play a role in pseudohypoparathyroidism type IB associated with abnormal imprinting of the GNAS complex locus. In this short review, I discuss these and other SNARE gene mutations and variants that are known to be associated with a variety developmental disorders, with a focus on their underlying cellular and molecular pathological basis deciphered through disease modeling. Possible pathogenic potentials of other SNAREs whose variants could be disease predisposing are also speculated upon.
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Affiliation(s)
- Bor L Tang
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
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Lam HY, Arumugam S, Bae HG, Wang CC, Jung S, St John AL, Hong W, Han W, Tergaonkar V. ELKS1 controls mast cell degranulation by regulating the transcription of Stxbp2 and Syntaxin 4 via Kdm2b stabilization. SCIENCE ADVANCES 2020; 6:6/31/eabb2497. [PMID: 32937583 PMCID: PMC7531903 DOI: 10.1126/sciadv.abb2497] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Accepted: 06/09/2020] [Indexed: 05/06/2023]
Abstract
ELKS1 is a protein with proposed roles in regulated exocytosis in neurons and nuclear factor κB (NF-κB) signaling in cancer cells. However, how these two potential roles come together under physiological settings remain unknown. Since both regulated exocytosis and NF-κB signaling are determinants of mast cell (MC) functions, we generated mice lacking ELKS1 in connective tissue MCs (Elks1f/f Mcpt5-Cre) and found that while ELKS1 is dispensable for NF-κB-mediated cytokine production, it is essential for MC degranulation both in vivo and in vitro. Impaired degranulation was caused by reduced transcription of Syntaxin 4 (STX4) and Syntaxin binding protein 2 (Stxpb2), resulting from a lack of ELKS1-mediated stabilization of lysine-specific demethylase 2B (Kdm2b), which is an essential regulator of STX4 and Stxbp2 transcription. These results suggest a transcriptional role for active-zone proteins like ELKS1 and suggest that they may regulate exocytosis through a novel mechanism involving transcription of key exocytosis proteins.
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Affiliation(s)
- Hiu Yan Lam
- Laboratory of NF-κB Signaling, Institute of Molecular and Cell Biology (IMCB), 61 Biopolis Drive, Proteos, Singapore 138673, Singapore
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore (NUS), Singapore 117596, Singapore
| | - Surendar Arumugam
- Laboratory of NF-κB Signaling, Institute of Molecular and Cell Biology (IMCB), 61 Biopolis Drive, Proteos, Singapore 138673, Singapore
| | - Han Gyu Bae
- Singapore Bioimaging Consortium, Agency for Science, Technology and Research, #02-02 Helios, 11 Biopolis Way, Singapore 138667, Singapore
| | - Cheng Chun Wang
- Institute of Molecular and Cell Biology (IMCB), 61 Biopolis Drive, Proteos, Singapore 138673, Singapore
| | - Sangyong Jung
- Singapore Bioimaging Consortium, Agency for Science, Technology and Research, #02-02 Helios, 11 Biopolis Way, Singapore 138667, Singapore
| | - Ashley Lauren St John
- Program in Emerging Infectious Diseases, Duke-NUS, Singapore 169857, Singapore
- Department of Microbiology and Immunology, NUS, Singapore 119077, Singapore
- Department of Pathology, Duke University Medical Center, Durham, NC, USA
| | - Wanjin Hong
- Institute of Molecular and Cell Biology (IMCB), 61 Biopolis Drive, Proteos, Singapore 138673, Singapore
| | - Weiping Han
- Singapore Bioimaging Consortium, Agency for Science, Technology and Research, #02-02 Helios, 11 Biopolis Way, Singapore 138667, Singapore
| | - Vinay Tergaonkar
- Laboratory of NF-κB Signaling, Institute of Molecular and Cell Biology (IMCB), 61 Biopolis Drive, Proteos, Singapore 138673, Singapore.
- Department of Pathology, Yong Loo Lin School of Medicine, National University of Singapore (NUS), Singapore 119074, Singapore
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10
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Duan XL, Guo Z, He YT, Li YX, Liu YN, Bai HH, Li HL, Hu XD, Suo ZW. SNAP25/syntaxin4/VAMP2/Munc18-1 Complexes in Spinal Dorsal Horn Contributed to Inflammatory Pain. Neuroscience 2020; 429:203-212. [PMID: 31962145 DOI: 10.1016/j.neuroscience.2020.01.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Revised: 12/31/2019] [Accepted: 01/02/2020] [Indexed: 02/06/2023]
Abstract
Soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) have been implicated in the trafficking of postsynaptic glutamate receptors, including N-methyl-d-aspartate (NMDA)-subtype glutamate receptors (NMDARs) that are critical for nociceptive plasticity and behavioral sensitization. However, the components of SNAREs complex involved in spinal nociceptive processing remain largely unknown. Here we found that SNAP25, syntaxin4, VAMP2 and Munc18-1 were localized at postsynaptic sites and formed the complex in the superficial lamina of spinal cord dorsal horn of rats. The complex formation between these SNAREs components were accelerated after intraplantar injection of complete Freund's adjuvant (CFA), pharmacological removal of GABAergic inhibition or activation of NMDAR in intact rats. The increased SNAP25/syntaxin4/VAMP2/Munc18-1 interaction facilitated the surface delivery and synaptic accumulation of NMDAR during inflammatory pain. Disruption of the molecular interaction between SNAP25 with its SNARE partners by using a blocking peptide derived from the C-terminus of SNAP25 effectively repressed the surface and synaptic accumulation of GluN2B-containing NMDARs in CFA-injected rats. This peptide also alleviated inflammatory mechanical allodynia and thermal hypersensitivity. These data suggested that SNAREs complex assembly in spinal cord dorsal horn was involved in the inflammatory pain hypersensitivity through promoting NMDAR synaptic trafficking.
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Affiliation(s)
- Xing-Lian Duan
- Department of Molecular Pharmacology, School of Pharmacy, Lanzhou University, Lanzhou, Gansu 730000, PR China
| | - Zhen Guo
- Department of Molecular Pharmacology, School of Pharmacy, Lanzhou University, Lanzhou, Gansu 730000, PR China
| | - Yong-Tao He
- Department of Molecular Pharmacology, School of Pharmacy, Lanzhou University, Lanzhou, Gansu 730000, PR China
| | - Yin-Xia Li
- Department of Molecular Pharmacology, School of Pharmacy, Lanzhou University, Lanzhou, Gansu 730000, PR China
| | - Yan-Ni Liu
- Department of Molecular Pharmacology, School of Pharmacy, Lanzhou University, Lanzhou, Gansu 730000, PR China
| | - Hu-Hu Bai
- Department of Molecular Pharmacology, School of Pharmacy, Lanzhou University, Lanzhou, Gansu 730000, PR China
| | - Hu-Ling Li
- Department of Molecular Pharmacology, School of Pharmacy, Lanzhou University, Lanzhou, Gansu 730000, PR China
| | - Xiao-Dong Hu
- Department of Molecular Pharmacology, School of Pharmacy, Lanzhou University, Lanzhou, Gansu 730000, PR China
| | - Zhan-Wei Suo
- Department of Molecular Pharmacology, School of Pharmacy, Lanzhou University, Lanzhou, Gansu 730000, PR China.
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11
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Hays CL, Grassmeyer JJ, Wen X, Janz R, Heidelberger R, Thoreson WB. Simultaneous Release of Multiple Vesicles from Rods Involves Synaptic Ribbons and Syntaxin 3B. Biophys J 2019; 118:967-979. [PMID: 31653448 DOI: 10.1016/j.bpj.2019.10.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Revised: 09/25/2019] [Accepted: 10/03/2019] [Indexed: 02/05/2023] Open
Abstract
First proposed as a specialized mode of release at sensory neurons possessing ribbon synapses, multivesicular release has since been described throughout the central nervous system. Many aspects of multivesicular release remain poorly understood. We explored mechanisms underlying simultaneous multivesicular release at ribbon synapses in salamander retinal rod photoreceptors. We assessed spontaneous release presynaptically by recording glutamate transporter anion currents (IA(glu)) in rods. Spontaneous IA(glu) events were correlated in amplitude and kinetics with simultaneously measured miniature excitatory postsynaptic currents in horizontal cells. Both measures indicated that a significant fraction of events is multiquantal, with an analysis of IA(glu) revealing that multivesicular release constitutes ∼30% of spontaneous release events. IA(glu) charge transfer increased linearly with event amplitude showing that larger events involve greater glutamate release. The kinetics of large and small IA(glu) events were identical as were rise times of large and small miniature excitatory postsynaptic currents, indicating that the release of multiple vesicles during large events is highly synchronized. Effects of exogenous Ca2+ buffers suggested that multiquantal, but not uniquantal, release occurs preferentially near Ca2+ channels clustered beneath synaptic ribbons. Photoinactivation of ribbons reduced the frequency of spontaneous multiquantal events without affecting uniquantal release frequency, showing that spontaneous multiquantal release requires functional ribbons. Although both occur at ribbon-style active zones, the absence of cross-depletion indicates that evoked and spontaneous multiquantal release from ribbons involve different vesicle pools. Introducing an inhibitory peptide into rods to interfere with the SNARE protein, syntaxin 3B, selectively reduced multiquantal event frequency. These results support the hypothesis that simultaneous multiquantal release from rods arises from homotypic fusion among neighboring vesicles on ribbons and involves syntaxin 3B.
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Affiliation(s)
- Cassandra L Hays
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska; Department of Ophthalmology and Visual Sciences, Truhlsen Eye Institute, University of Nebraska Medical Center, Omaha, Nebraska
| | - Justin J Grassmeyer
- Department of Ophthalmology and Visual Sciences, Truhlsen Eye Institute, University of Nebraska Medical Center, Omaha, Nebraska; Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, Nebraska
| | - Xiangyi Wen
- Department of Ophthalmology and Visual Sciences, Truhlsen Eye Institute, University of Nebraska Medical Center, Omaha, Nebraska; West China Hospital, Sichuan University, Chengdu, Sichuan, P.R. China
| | - Roger Janz
- Department of Neurobiology and Anatomy, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, Texas; The University of Texas MD Anderson Cancer Center University of Texas Health Graduate School of Biomedical Sciences, Houston, Texas
| | - Ruth Heidelberger
- Department of Neurobiology and Anatomy, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, Texas; The University of Texas MD Anderson Cancer Center University of Texas Health Graduate School of Biomedical Sciences, Houston, Texas
| | - Wallace B Thoreson
- Department of Ophthalmology and Visual Sciences, Truhlsen Eye Institute, University of Nebraska Medical Center, Omaha, Nebraska; Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, Nebraska.
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12
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Jaramillo AM, Piccotti L, Velasco WV, Delgado ASH, Azzegagh Z, Chung F, Nazeer U, Farooq J, Brenner J, Parker-Thornburg J, Scott BL, Evans CM, Adachi R, Burns AR, Kreda SM, Tuvim MJ, Dickey BF. Different Munc18 proteins mediate baseline and stimulated airway mucin secretion. JCI Insight 2019; 4:124815. [PMID: 30721150 PMCID: PMC6483006 DOI: 10.1172/jci.insight.124815] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Accepted: 01/31/2019] [Indexed: 12/15/2022] Open
Abstract
Airway mucin secretion is necessary for ciliary clearance of inhaled particles and pathogens but can be detrimental in pathologies such as asthma and cystic fibrosis. Exocytosis in mammals requires a Munc18 scaffolding protein, and airway secretory cells express all 3 Munc18 isoforms. Using conditional airway epithelial cell-deletant mice, we found that Munc18a has the major role in baseline mucin secretion, Munc18b has the major role in stimulated mucin secretion, and Munc18c does not function in mucin secretion. In an allergic asthma model, Munc18b deletion reduced airway mucus occlusion and airflow resistance. In a cystic fibrosis model, Munc18b deletion reduced airway mucus occlusion and emphysema. Munc18b deficiency in the airway epithelium did not result in any abnormalities of lung structure, particle clearance, inflammation, or bacterial infection. Our results show that regulated secretion in a polarized epithelial cell may involve more than one exocytic machine at the apical plasma membrane and that the protective roles of mucin secretion can be preserved while therapeutically targeting its pathologic roles.
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Affiliation(s)
- Ana M. Jaramillo
- Department of Pulmonary Medicine, University of Texas MD Anderson Cancer Center, Houston, Texas, USA
- Institute of Bioscience and Technology, Texas A&M University Health Science Center, Houston, Texas, USA
| | - Lucia Piccotti
- Department of Pulmonary Medicine, University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Walter V. Velasco
- Department of Pulmonary Medicine, University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | | | - Zoulikha Azzegagh
- Department of Pulmonary Medicine, University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Felicity Chung
- Marsico Lung Institute/Cystic Fibrosis Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Usman Nazeer
- Department of Pulmonary Medicine, University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Junaid Farooq
- Department of Pulmonary Medicine, University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Josh Brenner
- Department of Pulmonary Medicine, University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Jan Parker-Thornburg
- Department of Genetics, University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Brenton L. Scott
- Department of Pulmonary Medicine, University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Christopher M. Evans
- Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado Denver School of Medicine, Aurora, Colorado, USA
| | - Roberto Adachi
- Department of Pulmonary Medicine, University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Alan R. Burns
- College of Optometry, University of Houston, Houston, Texas, USA
| | - Silvia M. Kreda
- Marsico Lung Institute/Cystic Fibrosis Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Michael J. Tuvim
- Department of Pulmonary Medicine, University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Burton F. Dickey
- Department of Pulmonary Medicine, University of Texas MD Anderson Cancer Center, Houston, Texas, USA
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13
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Klein O, Sagi-Eisenberg R. Anaphylactic Degranulation of Mast Cells: Focus on Compound Exocytosis. J Immunol Res 2019; 2019:9542656. [PMID: 31011586 PMCID: PMC6442490 DOI: 10.1155/2019/9542656] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2018] [Accepted: 12/26/2018] [Indexed: 01/15/2023] Open
Abstract
Anaphylaxis is a notorious type 2 immune response which may result in a systemic response and lead to death. A precondition for the unfolding of the anaphylactic shock is the secretion of inflammatory mediators from mast cells in response to an allergen, mostly through activation of the cells via the IgE-dependent pathway. While mast cells are specialized secretory cells that can secrete through a variety of exocytic modes, the most predominant mode exerted by the mast cell during anaphylaxis is compound exocytosis-a specialized form of regulated exocytosis where secretory granules fuse to one another. Here, we review the modes of regulated exocytosis in the mast cell and focus on compound exocytosis. We review historical landmarks in the research of compound exocytosis in mast cells and the methods available for investigating compound exocytosis. We also review the molecular mechanisms reported to underlie compound exocytosis in mast cells and expand further with reviewing key findings from other cell types. Finally, we discuss the possible reasons for the mast cell to utilize compound exocytosis during anaphylaxis, the conflicting evidence in different mast cell models, and the open questions in the field which remain to be answered.
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Affiliation(s)
- Ofir Klein
- Department of Cell and Developmental Biology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Ronit Sagi-Eisenberg
- Department of Cell and Developmental Biology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
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14
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Sanchez E, Gonzalez EA, Moreno DS, Cardenas RA, Ramos MA, Davalos AJ, Manllo J, Rodarte AI, Petrova Y, Moreira DC, Chavez MA, Tortoriello A, Lara A, Gutierrez BA, Burns AR, Heidelberger R, Adachi R. Syntaxin 3, but not syntaxin 4, is required for mast cell-regulated exocytosis, where it plays a primary role mediating compound exocytosis. J Biol Chem 2019; 294:3012-3023. [PMID: 30563839 PMCID: PMC6398129 DOI: 10.1074/jbc.ra118.005532] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Revised: 11/30/2018] [Indexed: 11/06/2022] Open
Abstract
Mast cells (MCs) participate in allergy, inflammation, and defense against pathogens. They release multiple immune mediators via exocytosis, a process that requires SNARE proteins, including syntaxins (Stxs). The identity of the Stxs involved in MC exocytosis remains controversial. Here, we studied the roles of Stx3 and -4 in fully developed MCs from conditional knockout mice by electrophysiology and EM, and found that Stx3, and not Stx4, is crucial for MC exocytosis. The main defect seen in Stx3-deficient MCs was their inability to engage multigranular compound exocytosis, while leaving most single-vesicle fusion events intact. We used this defect to show that this form of exocytosis is not only required to accelerate MC degranulation but also essential to achieve full degranulation. The exocytic defect was severe but not absolute, indicating that an Stx other than Stx3 and -4 is also required for exocytosis in MCs. The removal of Stx3 affected only regulated exocytosis, leaving other MC effector responses intact, including the secretion of cytokines via constitutive exocytosis. Our in vivo model of passive systemic anaphylaxis showed that the residual exocytic function of Stx3-deficient MCs was sufficient to drive a full anaphylactic response in mice.
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Affiliation(s)
- Elizabeth Sanchez
- From the Department of Pulmonary Medicine, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030
- Tecnologico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Monterrey, Nuevo León 64710, México
| | - Erika A Gonzalez
- From the Department of Pulmonary Medicine, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030
- Tecnologico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Monterrey, Nuevo León 64710, México
| | - David S Moreno
- From the Department of Pulmonary Medicine, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030
- Tecnologico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Monterrey, Nuevo León 64710, México
| | - Rodolfo A Cardenas
- From the Department of Pulmonary Medicine, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030
- Tecnologico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Monterrey, Nuevo León 64710, México
| | - Marco A Ramos
- From the Department of Pulmonary Medicine, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030
- Tecnologico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Monterrey, Nuevo León 64710, México
| | - Alfredo J Davalos
- From the Department of Pulmonary Medicine, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030
- Tecnologico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Monterrey, Nuevo León 64710, México
| | - John Manllo
- From the Department of Pulmonary Medicine, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030
- Tecnologico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Monterrey, Nuevo León 64710, México
| | - Alejandro I Rodarte
- From the Department of Pulmonary Medicine, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030
- Tecnologico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Monterrey, Nuevo León 64710, México
| | - Youlia Petrova
- From the Department of Pulmonary Medicine, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030
| | - Daniel C Moreira
- From the Department of Pulmonary Medicine, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030
- Tecnologico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Monterrey, Nuevo León 64710, México
| | - Miguel A Chavez
- From the Department of Pulmonary Medicine, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030
- Tecnologico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Monterrey, Nuevo León 64710, México
| | - Alejandro Tortoriello
- From the Department of Pulmonary Medicine, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030
- Tecnologico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Monterrey, Nuevo León 64710, México
| | - Adolfo Lara
- the Department of Neurobiology and Anatomy, McGovern Medical School at the University of Texas Health Science Center, Houston, Texas 77030, and
| | - Berenice A Gutierrez
- From the Department of Pulmonary Medicine, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030
- Tecnologico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Monterrey, Nuevo León 64710, México
| | - Alan R Burns
- the College of Optometry, University of Houston, Houston, Texas 77204
| | - Ruth Heidelberger
- the Department of Neurobiology and Anatomy, McGovern Medical School at the University of Texas Health Science Center, Houston, Texas 77030, and
| | - Roberto Adachi
- From the Department of Pulmonary Medicine, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030,
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15
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Pezzulo AA, Tudas RA, Stewart CG, Buonfiglio LGV, Lindsay BD, Taft PJ, Gansemer ND, Zabner J. HSP90 inhibitor geldanamycin reverts IL-13- and IL-17-induced airway goblet cell metaplasia. J Clin Invest 2019; 129:744-758. [PMID: 30640172 PMCID: PMC6355221 DOI: 10.1172/jci123524] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Accepted: 11/20/2018] [Indexed: 12/29/2022] Open
Abstract
Goblet cell metaplasia, a disabling hallmark of chronic lung disease, lacks curative treatments at present. To identify novel therapeutic targets for goblet cell metaplasia, we studied the transcriptional response profile of IL-13-exposed primary human airway epithelia in vitro and asthmatic airway epithelia in vivo. A perturbation-response profile connectivity approach identified geldanamycin, an inhibitor of heat shock protein 90 (HSP90) as a candidate therapeutic target. Our experiments confirmed that geldanamycin and other HSP90 inhibitors prevented IL-13-induced goblet cell metaplasia in vitro and in vivo. Geldanamycin also reverted established goblet cell metaplasia. Geldanamycin did not induce goblet cell death, nor did it solely block mucin synthesis or IL-13 receptor-proximal signaling. Geldanamycin affected the transcriptome of airway cells when exposed to IL-13, but not when exposed to vehicle. We hypothesized that the mechanism of action probably involves TGF-β, ERBB, or EHF, which would predict that geldanamycin would also revert IL-17-induced goblet cell metaplasia, a prediction confirmed by our experiments. Our findings suggest that persistent airway goblet cell metaplasia requires HSP90 activity and that HSP90 inhibitors will revert goblet cell metaplasia, despite active upstream inflammatory signaling. Moreover, HSP90 inhibitors may be a therapeutic option for airway diseases with goblet cell metaplasia of unknown mechanism.
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Affiliation(s)
- Alejandro A. Pezzulo
- Department of Internal Medicine, Roy J. and Lucille A. Carver College of Medicine, and
- Pappajohn Biomedical Institute, University of Iowa, Iowa City, Iowa, USA
| | - Rosarie A. Tudas
- Department of Internal Medicine, Roy J. and Lucille A. Carver College of Medicine, and
- Pappajohn Biomedical Institute, University of Iowa, Iowa City, Iowa, USA
| | - Carley G. Stewart
- Department of Internal Medicine, Roy J. and Lucille A. Carver College of Medicine, and
- Pappajohn Biomedical Institute, University of Iowa, Iowa City, Iowa, USA
| | | | - Brian D. Lindsay
- Department of Internal Medicine, Roy J. and Lucille A. Carver College of Medicine, and
| | - Peter J. Taft
- Department of Internal Medicine, Roy J. and Lucille A. Carver College of Medicine, and
- Pappajohn Biomedical Institute, University of Iowa, Iowa City, Iowa, USA
| | - Nicholas D. Gansemer
- Department of Internal Medicine, Roy J. and Lucille A. Carver College of Medicine, and
- Pappajohn Biomedical Institute, University of Iowa, Iowa City, Iowa, USA
| | - Joseph Zabner
- Department of Internal Medicine, Roy J. and Lucille A. Carver College of Medicine, and
- Pappajohn Biomedical Institute, University of Iowa, Iowa City, Iowa, USA
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16
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Cardenas EI, Gonzalez R, Breaux K, Da Q, Gutierrez BA, Ramos MA, Cardenas RA, Burns AR, Rumbaut RE, Adachi R. Munc18-2, but not Munc18-1 or Munc18-3, regulates platelet exocytosis, hemostasis, and thrombosis. J Biol Chem 2019; 294:4784-4792. [PMID: 30696774 DOI: 10.1074/jbc.ra118.006922] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 01/24/2019] [Indexed: 12/17/2022] Open
Abstract
Platelet degranulation, a form of regulated exocytosis, is crucial for hemostasis and thrombosis. Exocytosis in platelets is mediated by SNARE proteins, and in most mammalian cells this process is controlled by Munc18 (mammalian homolog of Caenorhabditis elegans uncoordinated gene 18) proteins. Platelets express all Munc18 paralogs (Munc18-1, -2, and -3), but their roles in platelet secretion and function have not been fully characterized. Using Munc18-1, -2, and -3 conditional knockout mice, here we deleted expression of these proteins in platelets and assessed granule exocytosis. We measured products secreted by each type of platelet granule and analyzed EM platelet profiles by design-based stereology. We observed that the removal of Munc18-2 ablates the release of alpha, dense, and lysosomal granules from platelets, but we found no exocytic role for Munc18-1 or -3 in platelets. In vitro, Munc18-2-deficient platelets exhibited defective aggregation at low doses of collagen and impaired thrombus formation under shear stress. In vivo, megakaryocyte-specific Munc18-2 conditional knockout mice had a severe hemostatic defect and prolonged arterial and venous bleeding times. They were also protected against arterial thrombosis in a chemically induced model of arterial injury. Taken together, our results indicate that Munc18-2, but not Munc18-1 or Munc18-3, is essential for regulated exocytosis in platelets and platelet participation in thrombosis and hemostasis.
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Affiliation(s)
- Eduardo I Cardenas
- From the Department of Pulmonary Medicine, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030.,the Escuela de Ingenieria y Ciencias, Instituto Tecnologico de Monterrey, Monterrey, Nuevo Leon 64849, Mexico
| | - Ricardo Gonzalez
- From the Department of Pulmonary Medicine, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030.,the Escuela de Ingenieria y Ciencias, Instituto Tecnologico de Monterrey, Monterrey, Nuevo Leon 64849, Mexico
| | - Keegan Breaux
- From the Department of Pulmonary Medicine, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030
| | - Qi Da
- the Center for Translational Research on Inflammatory Diseases (CTRID), Michael E. DeBakey Veterans Affairs Medical Center, Houston, Texas 77030.,the Department of Medicine, Baylor College of Medicine, Houston, Texas 77030
| | - Berenice A Gutierrez
- From the Department of Pulmonary Medicine, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030.,the Escuela de Ingenieria y Ciencias, Instituto Tecnologico de Monterrey, Monterrey, Nuevo Leon 64849, Mexico
| | - Marco A Ramos
- From the Department of Pulmonary Medicine, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030
| | - Rodolfo A Cardenas
- From the Department of Pulmonary Medicine, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030.,the Escuela de Medicina y Ciencias de la Salud, Instituto Tecnologico de Monterrey, Monterrey, Nuevo León 64710, México, and
| | - Alan R Burns
- the College of Optometry, University of Houston, Houston, Texas 77204
| | - Rolando E Rumbaut
- the Center for Translational Research on Inflammatory Diseases (CTRID), Michael E. DeBakey Veterans Affairs Medical Center, Houston, Texas 77030.,the Department of Medicine, Baylor College of Medicine, Houston, Texas 77030
| | - Roberto Adachi
- From the Department of Pulmonary Medicine, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030,
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17
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Suzuki A, Iwata J. Molecular Regulatory Mechanism of Exocytosis in the Salivary Glands. Int J Mol Sci 2018; 19:E3208. [PMID: 30336591 PMCID: PMC6214078 DOI: 10.3390/ijms19103208] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2018] [Revised: 10/10/2018] [Accepted: 10/11/2018] [Indexed: 12/12/2022] Open
Abstract
Every day, salivary glands produce about 0.5 to 1.5 L of saliva, which contains salivary proteins that are essential for oral health. The contents of saliva, 0.3% proteins (1.5 to 4.5 g) in fluid, help prevent oral infections, provide lubrication, aid digestion, and maintain oral health. Acinar cells in the lobular salivary glands secrete prepackaged secretory granules that contain salivary components such as amylase, mucins, and immunoglobulins. Despite the important physiological functions of salivary proteins, we know very little about the regulatory mechanisms of their secretion via exocytosis, which is a process essential for the secretion of functional proteins, not only in salivary glands, but also in other secretory organs, including lacrimal and mammary glands, the pancreas, and prostate. In this review, we discuss recent findings that elucidate exocytosis by exocrine glands, especially focusing on the salivary glands, in physiological and pathological conditions.
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Affiliation(s)
- Akiko Suzuki
- Department of Diagnostic & Biomedical Sciences, The University of Texas Health Science Center at Houston School of Dentistry, Houston, TX 77054, USA.
- Center for Craniofacial Research, The University of Texas Health Science Center at Houston School of Dentistry, Houston, TX 77054, USA.
| | - Junichi Iwata
- Department of Diagnostic & Biomedical Sciences, The University of Texas Health Science Center at Houston School of Dentistry, Houston, TX 77054, USA.
- Center for Craniofacial Research, The University of Texas Health Science Center at Houston School of Dentistry, Houston, TX 77054, USA.
- Program of Biochemistry and Cell Biology, The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, TX 77030, USA.
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