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Saint-Martin Willer A, Montani D, Capuano V, Antigny F. Orai1/STIMs modulators in pulmonary vascular diseases. Cell Calcium 2024; 121:102892. [PMID: 38735127 DOI: 10.1016/j.ceca.2024.102892] [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: 02/21/2024] [Revised: 03/27/2024] [Accepted: 04/23/2024] [Indexed: 05/14/2024]
Abstract
Calcium (Ca2+) is a secondary messenger that regulates various cellular processes. However, Ca2+ mishandling could lead to pathological conditions. Orai1 is a Ca2+channel contributing to the store-operated calcium entry (SOCE) and plays a critical role in Ca2+ homeostasis in several cell types. Dysregulation of Orai1 contributed to severe combined immune deficiency syndrome, some cancers, pulmonary arterial hypertension (PAH), and other cardiorespiratory diseases. During its activation process, Orai1 is mainly regulated by stromal interacting molecule (STIM) proteins, especially STIM1; however, many other regulatory partners have also been recently described. Increasing knowledge about these regulatory partners provides a better view of the downstream signalling pathways of SOCE and offers an excellent opportunity to decipher Orai1 dysregulation in these diseases. These proteins participate in other cellular functions, making them attractive therapeutic targets. This review mainly focuses on Orai1 regulatory partners in the physiological and pathological conditions of the pulmonary circulation and inflammation.
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Affiliation(s)
- Anaïs Saint-Martin Willer
- Université Paris-Saclay, Faculté de Médecine, Le Kremlin-Bicêtre, France; INSERM UMR_S 999 Hypertension pulmonaire: Physiopathologie et Innovation Thérapeutique, Hôpital Marie Lannelongue, Le Plessis-Robinson, France
| | - David Montani
- Université Paris-Saclay, Faculté de Médecine, Le Kremlin-Bicêtre, France; INSERM UMR_S 999 Hypertension pulmonaire: Physiopathologie et Innovation Thérapeutique, Hôpital Marie Lannelongue, Le Plessis-Robinson, France; Assistance Publique - Hôpitaux de Paris (AP-HP), Service de Pneumologie et Soins Intensifs Respiratoires, Centre de Référence de l'Hypertension Pulmonaire, Hôpital Bicêtre, Le Kremlin-Bicêtre, France
| | - Véronique Capuano
- Université Paris-Saclay, Faculté de Médecine, Le Kremlin-Bicêtre, France; INSERM UMR_S 999 Hypertension pulmonaire: Physiopathologie et Innovation Thérapeutique, Hôpital Marie Lannelongue, Le Plessis-Robinson, France; Hôptal Marie Lannelongue, Groupe Hospitalier Paris Saint-Joseph, Le Plessis-Robinson, France
| | - Fabrice Antigny
- Université Paris-Saclay, Faculté de Médecine, Le Kremlin-Bicêtre, France; INSERM UMR_S 999 Hypertension pulmonaire: Physiopathologie et Innovation Thérapeutique, Hôpital Marie Lannelongue, Le Plessis-Robinson, France.
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2
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Garner KE, Salter A, Lau CK, Gurusaran M, Villemant CM, Granger EP, McNee G, Woodman PG, Davies OR, Burke BE, Allan VJ. The meiotic LINC complex component KASH5 is an activating adaptor for cytoplasmic dynein. J Cell Biol 2023; 222:e202204042. [PMID: 36946995 PMCID: PMC10071310 DOI: 10.1083/jcb.202204042] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Revised: 12/15/2022] [Accepted: 02/10/2023] [Indexed: 03/23/2023] Open
Abstract
Cytoplasmic dynein-driven movement of chromosomes during prophase I of mammalian meiosis is essential for synapsis and genetic exchange. Dynein connects to chromosome telomeres via KASH5 and SUN1 or SUN2, which together span the nuclear envelope. Here, we show that KASH5 promotes dynein motility in vitro, and cytosolic KASH5 inhibits dynein's interphase functions. KASH5 interacts with a dynein light intermediate chain (DYNC1LI1 or DYNC1LI2) via a conserved helix in the LIC C-terminal, and this region is also needed for dynein's recruitment to other cellular membranes. KASH5's N-terminal EF-hands are essential as the interaction with dynein is disrupted by mutation of key calcium-binding residues, although it is not regulated by cellular calcium levels. Dynein can be recruited to KASH5 at the nuclear envelope independently of dynactin, while LIS1 is essential for dynactin incorporation into the KASH5-dynein complex. Altogether, we show that the transmembrane protein KASH5 is an activating adaptor for dynein and shed light on the hierarchy of assembly of KASH5-dynein-dynactin complexes.
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Affiliation(s)
- Kirsten E.L. Garner
- School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - Anna Salter
- School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
- A*STAR Institute of Medical Biology, Singapore, Singapore
| | - Clinton K. Lau
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge, UK
| | - Manickam Gurusaran
- Wellcome Centre for Cell Biology, Institute of Cell Biology, University of Edinburgh, Edinburgh, UK
| | - Cécile M. Villemant
- School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - Elizabeth P. Granger
- School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - Gavin McNee
- School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - Philip G. Woodman
- School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - Owen R. Davies
- Wellcome Centre for Cell Biology, Institute of Cell Biology, University of Edinburgh, Edinburgh, UK
| | - Brian E. Burke
- A*STAR Institute of Medical Biology, Singapore, Singapore
| | - Victoria J. Allan
- School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
- A*STAR Institute of Medical Biology, Singapore, Singapore
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3
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Patel MA, Knauer MJ, Nicholson M, Daley M, Van Nynatten LR, Cepinskas G, Fraser DD. Organ and cell-specific biomarkers of Long-COVID identified with targeted proteomics and machine learning. Mol Med 2023; 29:26. [PMID: 36809921 PMCID: PMC9942653 DOI: 10.1186/s10020-023-00610-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Accepted: 01/13/2023] [Indexed: 02/24/2023] Open
Abstract
BACKGROUND Survivors of acute COVID-19 often suffer prolonged, diffuse symptoms post-infection, referred to as "Long-COVID". A lack of Long-COVID biomarkers and pathophysiological mechanisms limits effective diagnosis, treatment and disease surveillance. We performed targeted proteomics and machine learning analyses to identify novel blood biomarkers of Long-COVID. METHODS A case-control study comparing the expression of 2925 unique blood proteins in Long-COVID outpatients versus COVID-19 inpatients and healthy control subjects. Targeted proteomics was accomplished with proximity extension assays, and machine learning was used to identify the most important proteins for identifying Long-COVID patients. Organ system and cell type expression patterns were identified with Natural Language Processing (NLP) of the UniProt Knowledgebase. RESULTS Machine learning analysis identified 119 relevant proteins for differentiating Long-COVID outpatients (Bonferonni corrected P < 0.01). Protein combinations were narrowed down to two optimal models, with nine and five proteins each, and with both having excellent sensitivity and specificity for Long-COVID status (AUC = 1.00, F1 = 1.00). NLP expression analysis highlighted the diffuse organ system involvement in Long-COVID, as well as the involved cell types, including leukocytes and platelets, as key components associated with Long-COVID. CONCLUSIONS Proteomic analysis of plasma from Long-COVID patients identified 119 highly relevant proteins and two optimal models with nine and five proteins, respectively. The identified proteins reflected widespread organ and cell type expression. Optimal protein models, as well as individual proteins, hold the potential for accurate diagnosis of Long-COVID and targeted therapeutics.
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Affiliation(s)
- Maitray A Patel
- Epidemiology and Biostatistics, Western University, London, ON, N6A 3K7, Canada
| | - Michael J Knauer
- Pathology and Laboratory Medicine, Western University, London, ON, N6A 3K7, Canada
| | | | - Mark Daley
- Epidemiology and Biostatistics, Western University, London, ON, N6A 3K7, Canada.,Computer Science, Western University, London, ON, N6A 3K7, Canada
| | | | - Gediminas Cepinskas
- Lawson Health Research Institute, London, ON, N6C 2R5, Canada.,Medical Biophysics, Western University, London, ON, N6A 3K7, Canada
| | - Douglas D Fraser
- Lawson Health Research Institute, London, ON, N6C 2R5, Canada. .,Children's Health Research Institute, London, ON, N6C 4V3, Canada. .,Pediatrics, Western University, London, ON, N6A 3K7, Canada. .,Clinical Neurological Sciences, Western University, London, ON, N6A 3K7, Canada. .,Physiology and Pharmacology, Western University, London, ON, N6A 3K7, Canada. .,Room C2-C82, London Health Sciences Centre, 800 Commissioners Road East, London, ON, N6A 5W9, Canada.
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4
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Burchett JR, Dailey JM, Kee SA, Pryor DT, Kotha A, Kankaria RA, Straus DB, Ryan JJ. Targeting Mast Cells in Allergic Disease: Current Therapies and Drug Repurposing. Cells 2022; 11:3031. [PMID: 36230993 PMCID: PMC9564111 DOI: 10.3390/cells11193031] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Revised: 08/31/2022] [Accepted: 09/20/2022] [Indexed: 11/22/2022] Open
Abstract
The incidence of allergic disease has grown tremendously in the past three generations. While current treatments are effective for some, there is considerable unmet need. Mast cells are critical effectors of allergic inflammation. Their secreted mediators and the receptors for these mediators have long been the target of allergy therapy. Recent drugs have moved a step earlier in mast cell activation, blocking IgE, IL-4, and IL-13 interactions with their receptors. In this review, we summarize the latest therapies targeting mast cells as well as new drugs in clinical trials. In addition, we offer support for repurposing FDA-approved drugs to target mast cells in new ways. With a multitude of highly selective drugs available for cancer, autoimmunity, and metabolic disorders, drug repurposing offers optimism for the future of allergy therapy.
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Affiliation(s)
| | | | | | | | | | | | | | - John J. Ryan
- Department of Biology, Virginia Commonwealth University, Richmond, VA 23284, USA
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5
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Longé C, Bratti M, Kurowska M, Vibhushan S, David P, Desmeure V, Huang JD, Fischer A, de Saint Basile G, Sepulveda FE, Blank U, Ménasché G. Rab44 regulates murine mast cell-driven anaphylaxis through kinesin-1-dependent secretory granule translocation. J Allergy Clin Immunol 2022; 150:676-689. [PMID: 35469841 DOI: 10.1016/j.jaci.2022.04.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 03/15/2022] [Accepted: 04/08/2022] [Indexed: 11/16/2022]
Abstract
BACKGROUND Mast cells (MCs) are key effectors of the allergic response. Following the cross-linking of IgE receptors (FcεRIs), they release crucial inflammatory mediators through degranulation. Although degranulation depends critically on secretory granule (SG) trafficking towards the plasma membrane, the molecular machinery underlying this transport has not been fully characterized. OBJECTIVE Here, we analyzed the function of Rab44, a large atypical Rab GTPase highly expressed in MC, in MC degranulation process. METHODS Murine KO mouse models (KORab44 and DKOKif5b/Rab44) were used to perform passive cutaneous anaphylaxis (PCA) experiments and analyze granule translocation in derived bone-marrow-derived MCs (BMMCs) during degranulation. RESULTS We demonstrate that mice lacking Rab44 (KORab44) in their BMMCs are impaired in their ability to translocate and degranulate SGs at the plasma membrane upon FcεRI stimulation. Accordingly, KORab44 mice were less sensitive to IgE-mediated passive cutaneous anaphylaxis in vivo. A lack of Rab44 did not impair early FcεRI-stimulated signaling pathways, microtubule reorganization, lipid mediator or cytokine secretion. Mechanistically, Rab44 appears to interact with and function as part of the previously described kinesin-1-dependent transport pathway. CONCLUSIONS Our results highlight a novel role of Rab44 as a regulator of SG transport during degranulation and anaphylaxis acting through the kinesin-1-dependent microtubule transport machinery. Rab44 can thus be considered as a potential target for modulating MC degranulation and inhibiting IgE-mediated allergic reactions.
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Affiliation(s)
- Cyril Longé
- Université Paris Cité, Imagine Institute, Laboratory of Molecular basis of altered immune homeostasis, INSERM UMR1163, F-75015 Paris France
| | - Manuela Bratti
- Université Paris Cité, Centre de Recherche sur l'Inflammation, INSERM UMR1149, CNRS EMR8252, Faculté de Médecine site Bichat, Paris, France; Laboratoire d'Excellence Inflamex, F-75018, Paris, France
| | - Mathieu Kurowska
- Université Paris Cité, Imagine Institute, Laboratory of Molecular basis of altered immune homeostasis, INSERM UMR1163, F-75015 Paris France
| | - Shamila Vibhushan
- Université Paris Cité, Centre de Recherche sur l'Inflammation, INSERM UMR1149, CNRS EMR8252, Faculté de Médecine site Bichat, Paris, France; Laboratoire d'Excellence Inflamex, F-75018, Paris, France
| | - Pierre David
- Transgenesis Facility, Laboratoire d'Expérimentation Animale et Transgénèse (LEAT), Imagine Institute, Structure Fédérative de Recherche Necker INSERM US24/CNRS UMS3633, F-75015, Paris, France
| | - Valère Desmeure
- Université Paris Cité, Imagine Institute, Laboratory of Molecular basis of altered immune homeostasis, INSERM UMR1163, F-75015 Paris France
| | - Jian-Dong Huang
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong
| | - Alain Fischer
- Université Paris Cité, Imagine Institute, Laboratory of Molecular basis of altered immune homeostasis, INSERM UMR1163, F-75015 Paris France; Immunology and Pediatric Hematology Department, Necker Children's Hospital, AP-HP, F-75015 Paris, France; Collège de France, F-75005 Paris, France
| | - Geneviève de Saint Basile
- Université Paris Cité, Imagine Institute, Laboratory of Molecular basis of altered immune homeostasis, INSERM UMR1163, F-75015 Paris France; Centre d'Etude des Déficits Immunitaires, AP-HP, Hôpital Necker-Enfants Malades, F-75015, Paris, France
| | - Fernando E Sepulveda
- Université Paris Cité, Imagine Institute, Laboratory of Molecular basis of altered immune homeostasis, INSERM UMR1163, F-75015 Paris France; Centre National de la Recherche Scientifique, F-75015, Paris. France
| | - Ulrich Blank
- Université Paris Cité, Centre de Recherche sur l'Inflammation, INSERM UMR1149, CNRS EMR8252, Faculté de Médecine site Bichat, Paris, France; Laboratoire d'Excellence Inflamex, F-75018, Paris, France
| | - Gaël Ménasché
- Université Paris Cité, Imagine Institute, Laboratory of Molecular basis of altered immune homeostasis, INSERM UMR1163, F-75015 Paris France
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6
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Wu B, Woo JS, Sun Z, Srikanth S, Gwack Y. Ca 2+ Signaling Augmented by ORAI1 Trafficking Regulates the Pathogenic State of Effector T Cells. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2022; 208:1329-1340. [PMID: 35217583 PMCID: PMC8916982 DOI: 10.4049/jimmunol.2100871] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Accepted: 01/07/2022] [Indexed: 02/02/2023]
Abstract
Activation of the Ca2+ release-activated Ca2+ (CRAC) channel is crucial for T cell functions. It was recently shown that naked cuticle homolog 2 (NKD2), a signaling adaptor molecule, orchestrates trafficking of ORAI1, a pore subunit of the CRAC channels, to the plasma membrane for sustained activation of the CRAC channels. However, the physiological role of sustained Ca2+ entry via ORAI1 trafficking remains poorly understood. Using NKD2 as a molecular handle, we show that ORAI1 trafficking is crucial for sustained Ca2+ entry and cytokine production, especially in inflammatory Th1 and Th17 cells. We find that murine T cells cultured under pathogenic Th17-polarizing conditions have higher Ca2+ levels that are NKD2-dependent than those under nonpathogenic conditions. In vivo, deletion of Nkd2 alleviated clinical symptoms of experimental autoimmune encephalomyelitis in mice by selectively decreasing effector T cell responses in the CNS. Furthermore, we observed a strong correlation between NKD2 expression and proinflammatory cytokine production in effector T cells. Taken together, our findings suggest that the pathogenic effector T cell response demands sustained Ca2+ entry supported by ORAI1 trafficking.
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Affiliation(s)
- Beibei Wu
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, CA; and
| | - Jin Seok Woo
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, CA; and
| | - Zuoming Sun
- Department of Molecular Imaging and Therapy, Beckman Research Institute of City of Hope, Duarte, CA
| | - Sonal Srikanth
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, CA; and
| | - Yousang Gwack
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, CA; and
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7
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Palty R. CRACR2A associated immunodeficiency - the supporting factor takes center stage. Cell Calcium 2022; 103:102552. [PMID: 35151051 DOI: 10.1016/j.ceca.2022.102552] [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: 01/31/2022] [Revised: 02/03/2022] [Accepted: 02/04/2022] [Indexed: 11/30/2022]
Abstract
Loss of function mutations in one of the core components of the calcium release-activated calcium (CRAC) channel complex, STIM1 and ORAI1, lead to severe immunodeficiency. Whether changes in regulatory components of the CRAC channel may also contribute to a disease state remained unknown. In a recent study, Wu et al. report a case of late onset immunodeficiency in a patient with bi-allelic mutation in CRACR2A, a regulatory component of the CRAC channel.
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Affiliation(s)
- Raz Palty
- Department of Biochemistry, Technion Integrated Cancer Center, Ruth and Bruce Rappaport Faculty of Medicine, Technion - Israel Institute of Technology, Haifa 31096 Israel.
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8
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Large Rab GTPases: Novel Membrane Trafficking Regulators with a Calcium Sensor and Functional Domains. Int J Mol Sci 2021; 22:ijms22147691. [PMID: 34299309 PMCID: PMC8303950 DOI: 10.3390/ijms22147691] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Revised: 07/13/2021] [Accepted: 07/14/2021] [Indexed: 12/28/2022] Open
Abstract
Rab GTPases are major coordinators of intracellular membrane trafficking, including vesicle transport, membrane fission, tethering, docking, and fusion events. Rab GTPases are roughly divided into two groups: conventional “small” Rab GTPases and atypical “large” Rab GTPases that have been recently reported. Some members of large Rab GTPases in mammals include Rab44, Rab45/RASEF, and Rab46. The genes of these large Rab GTPases commonly encode an amino-terminal EF-hand domain, coiled-coil domain, and the carboxyl-terminal Rab GTPase domain. A common feature of large Rab GTPases is that they express several isoforms in cells. For instance, Rab44’s two isoforms have similar functions, but exhibit differential localization. The long form of Rab45 (Rab45-L) is abundantly distributed in epithelial cells. The short form of Rab45 (Rab45-S) is predominantly present in the testes. Both Rab46 (CRACR2A-L) and the short isoform lacking the Rab domain (CRACR2A-S) are expressed in T cells, whereas Rab46 is only distributed in endothelial cells. Although evidence regarding the function of large Rab GTPases has been accumulating recently, there are only a limited number of studies. Here, we report the recent findings on the large Rab GTPase family concerning their function in membrane trafficking, cell differentiation, related diseases, and knockout mouse phenotypes.
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9
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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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10
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Affinity-based proteomics reveals novel binding partners for Rab46 in endothelial cells. Sci Rep 2021; 11:4054. [PMID: 33603063 PMCID: PMC7893075 DOI: 10.1038/s41598-021-83560-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 01/27/2021] [Indexed: 12/22/2022] Open
Abstract
Rab46 is a novel Ca2+-sensing Rab GTPase shown to have important functions in endothelial and immune cells. The presence of functional Ca2+-binding, coiled-coil and Rab domains suggest that Rab46 will be important for coupling rapid responses to signalling in many cell types. The molecular mechanisms underlying Rab46 function are currently unknown. Here we provide the first resource for studying Rab46 interacting proteins. Using liquid chromatography tandem mass spectrometry (LC–MS/MS) to identify affinity purified proteins that bind to constitutively active GFP-Rab46 or inactive GFP-Rab46 expressed in endothelial cells, we have revealed 922 peptides that interact with either the GTP-bound Rab46 or GDP-bound Rab46. To identify proteins that could be potential Rab46 effectors we performed further comparative analyses between nucleotide-locked Rab46 proteins and identified 29 candidate effector proteins. Importantly, through biochemical and imaging approaches we have validated two potential effector proteins; dynein and the Na2+/ K+ ATPase subunit alpha 1 (ATP1α1). Hence, our use of affinity purification and LC–MS/MS to identify Rab46 neighbouring proteins provides a valuable resource for detecting Rab46 effector proteins and analysing Rab46 functions.
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11
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Wu B, Rice L, Shrimpton J, Lawless D, Walker K, Carter C, McKeown L, Anwar R, Doody GM, Srikanth S, Gwack Y, Savic S. Biallelic mutations in calcium release activated channel regulator 2A (CRACR2A) cause a primary immunodeficiency disorder. eLife 2021; 10:72559. [PMID: 34908525 PMCID: PMC8673834 DOI: 10.7554/elife.72559] [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: 07/27/2021] [Accepted: 12/04/2021] [Indexed: 01/19/2023] Open
Abstract
CRAC channel regulator 2 A (CRACR2A) is a large Rab GTPase that is expressed abundantly in T cells and acts as a signal transmitter between T cell receptor stimulation and activation of the Ca2+-NFAT and JNK-AP1 pathways. CRACR2A has been linked to human diseases in numerous genome-wide association studies, however, to date no patient with damaging variants in CRACR2A has been identified. In this study, we describe a patient harboring biallelic variants in CRACR2A [paternal allele c.834 gaG> gaT (p.E278D) and maternal alelle c.430 Aga > Gga (p.R144G) c.898 Gag> Tag (p.E300*)], the gene encoding CRACR2A. The 33-year-old patient of East-Asian origin exhibited late onset combined immunodeficiency characterised by recurrent chest infections, panhypogammaglobulinemia and CD4+ T cell lymphopenia. In vitro exposure of patient B cells to a T-dependent stimulus resulted in normal generation of antibody-secreting cells, however the patient's T cells showed pronounced reduction in CRACR2A protein levels and reduced proximal TCR signaling, including dampened SOCE and reduced JNK phosphorylation, that contributed to a defect in proliferation and cytokine production. Expression of individual allelic mutants in CRACR2A-deleted T cells showed that the CRACR2AE278D mutant did not affect JNK phosphorylation, but impaired SOCE which resulted in reduced cytokine production. The truncated double mutant CRACR2AR144G/E300* showed a pronounced defect in JNK phosphorylation as well as SOCE and strong impairment in cytokine production. Thus, we have identified variants in CRACR2A that led to late-stage combined immunodeficiency characterized by loss of function in T cells.
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Affiliation(s)
- Beibei Wu
- Department of Physiology, David Geffen School of Medicine, UCLALos AngelesUnited States
| | - Laura Rice
- Leeds Institute of Medical Research, University of LeedsLeedsUnited Kingdom
| | - Jennifer Shrimpton
- Division of Haematology and Immunology, Leeds Institute of Medical Research, University of LeedsLeedsUnited Kingdom
| | - Dylan Lawless
- Global Health Institute, School of Life Sciences, École Polytechnique Fédérale de LausanneLausanneSwitzerland
| | - Kieran Walker
- Division of Haematology and Immunology, Leeds Institute of Medical Research, University of LeedsLeedsUnited Kingdom
| | - Clive Carter
- Department of Clinical Immunology and Allergy, St James's University HospitalLeedsUnited Kingdom
| | - Lynn McKeown
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of LeedsLeedsUnited Kingdom
| | - Rashida Anwar
- Leeds Institute of Medical Research, University of LeedsLeedsUnited Kingdom
| | - Gina M Doody
- Division of Haematology and Immunology, Leeds Institute of Medical Research, University of LeedsLeedsUnited Kingdom
| | - Sonal Srikanth
- Department of Physiology, David Geffen School of Medicine, UCLALos AngelesUnited States
| | - Yousang Gwack
- Department of Physiology, David Geffen School of Medicine, UCLALos AngelesUnited States
| | - Sinisa Savic
- Department of Clinical Immunology and Allergy, St James's University HospitalLeedsUnited Kingdom,National Institute for Health Research-Leeds Biomedical Research Centre and Leeds Institute of Rheumatic and Musculoskeletal Medicine, Wellcome Trust Brenner Building, St James's University HospitalLeedsUnited Kingdom
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12
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Sumiyoshi M, Kotani Y, Ikuta Y, Suzue K, Ozawa M, Katakai T, Yamada T, Abe T, Bando K, Koyasu S, Kanaho Y, Watanabe T, Matsuda S. Arf1 and Arf6 Synergistically Maintain Survival of T Cells during Activation. THE JOURNAL OF IMMUNOLOGY 2020; 206:366-375. [PMID: 33310872 DOI: 10.4049/jimmunol.2000971] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Accepted: 11/12/2020] [Indexed: 12/25/2022]
Abstract
ADP-ribosylation factor (Arf) family consisting of six family members, Arf1-Arf6, belongs to Ras superfamily and orchestrates vesicle trafficking under the control of guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins. It is well established that brefeldin A, a potent inhibitor of ArfGEFs, blocks cytokine secretion from activated T cells, suggesting that the Arf pathway plays important roles in T cell functions. In this study, because Arf1 and Arf6 are the best-characterized members among Arf family, we established T lineage-specific Arf1-deficient, Arf6-deficient, and Arf1/6 double-deficient mice to understand physiological roles of the Arf pathway in the immune system. Contrary to our expectation, Arf deficiency had little or no impact on cytokine secretion from the activated T cells. In contrast, the lack of both Arf1 and Arf6, but neither Arf1 nor Arf6 deficiency alone, rendered naive T cells susceptible to apoptosis upon TCR stimulation because of imbalanced expression of Bcl-2 family members. We further demonstrate that Arf1/6 deficiency in T cells alleviates autoimmune diseases like colitis and experimental autoimmune encephalomyelitis, whereas Ab response under Th2-polarizing conditions is seemingly normal. Our findings reveal an unexpected role for the Arf pathway in the survival of T cells during TCR-induced activation and its potential as a therapeutic target in the autoimmune diseases.
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Affiliation(s)
- Mami Sumiyoshi
- Department of Cell Signaling, Institute of Biomedical Science, Kansai Medical University, Hirakata, Osaka 573-1010, Japan
| | - Yui Kotani
- Department of Cell Signaling, Institute of Biomedical Science, Kansai Medical University, Hirakata, Osaka 573-1010, Japan.,Department of Biological Science, Graduate School of Humanities and Sciences, Nara Women's University, Nara 630-8506, Japan
| | - Yuki Ikuta
- Department of Biological Science, Graduate School of Humanities and Sciences, Nara Women's University, Nara 630-8506, Japan
| | - Kazutomo Suzue
- Department of Parasitology, Gunma University Graduate School of Medicine, Maebashi, Gunma 371-8511, Japan
| | - Madoka Ozawa
- Department of Immunology, Niigata University Graduate School of Medical and Dental Sciences, Niigata 951-8510, Japan
| | - Tomoya Katakai
- Department of Immunology, Niigata University Graduate School of Medical and Dental Sciences, Niigata 951-8510, Japan
| | - Taketo Yamada
- Department of Pathology, Saitama Medical University, Iruma-gun, Saitama 350-0495, Japan
| | - Takaya Abe
- Laboratory for Animal Resources and Genetic Engineering, RIKEN Center for Biosystems Dynamics Research, Kobe, Hyogo 650-0047, Japan
| | - Kana Bando
- Laboratory for Animal Resources and Genetic Engineering, RIKEN Center for Biosystems Dynamics Research, Kobe, Hyogo 650-0047, Japan
| | - Shigeo Koyasu
- Laboratory for Immune Cell Systems, RIKEN Center for Integrative Medical Sciences, Yokohama, Kanagawa 230-0045, Japan; and
| | - Yasunori Kanaho
- Department of Physiological Chemistry, Graduate School of Comprehensive Human Sciences, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan
| | - Toshio Watanabe
- Department of Biological Science, Graduate School of Humanities and Sciences, Nara Women's University, Nara 630-8506, Japan
| | - Satoshi Matsuda
- Department of Cell Signaling, Institute of Biomedical Science, Kansai Medical University, Hirakata, Osaka 573-1010, Japan;
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13
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Ogawa K, Kadowaki T, Tokuhisa M, Yamaguchi Y, Umeda M, Tsukuba T. Role of the EF-hand and coiled-coil domains of human Rab44 in localisation and organelle formation. Sci Rep 2020; 10:19149. [PMID: 33154405 PMCID: PMC7645795 DOI: 10.1038/s41598-020-75897-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Accepted: 10/15/2020] [Indexed: 12/26/2022] Open
Abstract
Rab44 is a large Rab GTPase that contains an amino-terminal EF-hand domain, a coiled-coil domain, and a carboxyl-terminal Rab GTPase domain. However, the roles of the EF-hand and coiled-coil domains remain unclear. Here, we constructed various deletion and point mutants of human Rab44. When overexpressed in HeLa cells, the wild-type Rab44 (hWT) formed ring-like structures, and partially localised to lysosomes. The dominant negative mutant, hT847N, localised to lysosomes and the cytosol, while the constitutively active mutant, hQ892L, formed ring-like structures, and partially localised to the plasma membrane and nuclei. The hΔEF, hΔcoil, and h826-1021 mutants also formed ring-like structures; however, their localisation patterns differed from hWT. Analysis of live imaging with LysoTracker revealed that the size of LysoTracker-positive vesicles was altered by all other mutations than the hC1019A and hΔEF. Treatment with ionomycin, a Ca2+ ionophore, induced the translocation of hWT and hΔcoil into the plasma membrane and cytosol, but had no effect on the localisation of the hΔEF and h826-1021 mutants. Thus, the EF- hand domain is likely required for the partial translocation of Rab44 to the plasma membrane and cytosol following transient Ca2+ influx, and the coiled-coil domain appears to be important for localisation and organelle formation.
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Affiliation(s)
- Kohei Ogawa
- Department of Frontier Oral Science, Graduate School of Biomedical Sciences, Nagasaki University, Sakamoto 1-7-1, Nagasaki, 852-8588, Japan.,Department of Dental Pharmacology, Graduate School of Biomedical Sciences, Nagasaki University, Sakamoto 1-7-1, Nagasaki, 852-8588, Japan.,Department of Clinical Oral Oncology, Graduate School of Biomedical Sciences, Nagasaki University, Sakamoto 1-7-1, Nagasaki, 852-8588, Japan
| | - Tomoko Kadowaki
- Department of Frontier Oral Science, Graduate School of Biomedical Sciences, Nagasaki University, Sakamoto 1-7-1, Nagasaki, 852-8588, Japan.
| | - Mitsuko Tokuhisa
- Department of Frontier Oral Science, Graduate School of Biomedical Sciences, Nagasaki University, Sakamoto 1-7-1, Nagasaki, 852-8588, Japan.,Department of Dental Pharmacology, Graduate School of Biomedical Sciences, Nagasaki University, Sakamoto 1-7-1, Nagasaki, 852-8588, Japan.,Department of Clinical Oral Oncology, Graduate School of Biomedical Sciences, Nagasaki University, Sakamoto 1-7-1, Nagasaki, 852-8588, Japan
| | - Yu Yamaguchi
- Department of Dental Pharmacology, Graduate School of Biomedical Sciences, Nagasaki University, Sakamoto 1-7-1, Nagasaki, 852-8588, Japan
| | - Masahiro Umeda
- Department of Clinical Oral Oncology, Graduate School of Biomedical Sciences, Nagasaki University, Sakamoto 1-7-1, Nagasaki, 852-8588, Japan
| | - Takayuki Tsukuba
- Department of Dental Pharmacology, Graduate School of Biomedical Sciences, Nagasaki University, Sakamoto 1-7-1, Nagasaki, 852-8588, Japan.
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14
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The short isoform of extended synaptotagmin-2 controls Ca 2+ dynamics in T cells via interaction with STIM1. Sci Rep 2020; 10:14433. [PMID: 32879390 PMCID: PMC7468131 DOI: 10.1038/s41598-020-71489-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Accepted: 08/14/2020] [Indexed: 11/16/2022] Open
Abstract
Ca2+ release-activated Ca2+ (CRAC) channels elevate cytoplasmic Ca2+ concentration, which is essential for T cell activation, differentiation and effector functions. T cell receptor stimulation induces depletion of the endoplasmic reticulum (ER) Ca2+ stores, which is sensed by stromal interaction molecule 1 (STIM1). STIM1 translocates to the ER-plasma membrane (PM) junctions to interact with ORAI1, the pore subunit of the CRAC channels. Here, we show that two members of the extended synaptotagmin (E-Syt) family, E-Syt1, and the short isoform of E-Syt2 (E-Syt2S), contribute to activation of CRAC channels in T cells. Knockdown or deletion of both ESYT1 and ESYT2 reduced store-operated Ca2+ entry (SOCE) and ORAI1-STIM1 clustering in Jurkat T cells. Further, depletion of E-Syts in primary T cells decreased Ca2+ entry and cytokine production. While the ER-PM junctions were reduced in both HeLa and Jurkat T cells deleted for ESYT1 and ESYT2, SOCE was impaired only in Jurkat T cells, suggesting that the membrane-tethering function of E-Syts is distinct from their role in SOCE. Mechanistically, E-Syt2S, the predominant isoform of E-Syt2 in T cells, recruited STIM1 to the junctions via a direct interaction. This study demonstrates a membrane-tethering-independent role of E-Syts in activation of CRAC channels in T cells.
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15
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Homma Y, Hiragi S, Fukuda M. Rab family of small GTPases: an updated view on their regulation and functions. FEBS J 2020; 288:36-55. [PMID: 32542850 PMCID: PMC7818423 DOI: 10.1111/febs.15453] [Citation(s) in RCA: 193] [Impact Index Per Article: 48.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 05/27/2020] [Accepted: 06/11/2020] [Indexed: 12/13/2022]
Abstract
The Rab family of small GTPases regulates intracellular membrane trafficking by orchestrating the biogenesis, transport, tethering, and fusion of membrane‐bound organelles and vesicles. Like other small GTPases, Rabs cycle between two states, an active (GTP‐loaded) state and an inactive (GDP‐loaded) state, and their cycling is catalyzed by guanine nucleotide exchange factors (GEFs) and GTPase‐activating proteins (GAPs). Because an active form of each Rab localizes on a specific organelle (or vesicle) and recruits various effector proteins to facilitate each step of membrane trafficking, knowing when and where Rabs are activated and what effectors Rabs recruit is crucial to understand their functions. Since the discovery of Rabs, they have been regarded as one of the central hubs for membrane trafficking, and numerous biochemical and genetic studies have revealed the mechanisms of Rab functions in recent years. The results of these studies have included the identification and characterization of novel GEFs, GAPs, and effectors, as well as post‐translational modifications, for example, phosphorylation, of Rabs. Rab functions beyond the simple effector‐recruiting model are also emerging. Furthermore, the recently developed CRISPR/Cas technology has enabled acceleration of knockout analyses in both animals and cultured cells and revealed previously unknown physiological roles of many Rabs. In this review article, we provide the most up‐to‐date and comprehensive lists of GEFs, GAPs, effectors, and knockout phenotypes of mammalian Rabs and discuss recent findings in regard to their regulation and functions.
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Affiliation(s)
- Yuta Homma
- Laboratory of Membrane Trafficking Mechanisms, Department of Integrative Life Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Japan
| | - Shu Hiragi
- Laboratory of Membrane Trafficking Mechanisms, Department of Integrative Life Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Japan
| | - Mitsunori Fukuda
- Laboratory of Membrane Trafficking Mechanisms, Department of Integrative Life Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Japan
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16
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The orphan solute carrier SLC10A7 is a novel negative regulator of intracellular calcium signaling. Sci Rep 2020; 10:7248. [PMID: 32350310 PMCID: PMC7190670 DOI: 10.1038/s41598-020-64006-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Accepted: 04/07/2020] [Indexed: 02/07/2023] Open
Abstract
SLC10A7 represents an orphan member of the Solute Carrier Family SLC10. Recently, mutations in the human SLC10A7 gene were associated with skeletal dysplasia, amelogenesis imperfecta, and decreased bone mineral density. However, the exact molecular function of SLC10A7 and the mechanisms underlying these pathologies are still unknown. For this reason, the role of SLC10A7 on intracellular calcium signaling was investigated. SLC10A7 protein expression was negatively correlated with store-operated calcium entry (SOCE) via the plasma membrane. Whereas SLC10A7 knockout HAP1 cells showed significantly increased calcium influx after thapsigargin, ionomycin and ATP/carbachol treatment, SLC10A7 overexpression reduced this calcium influx. Intracellular Ca2+ levels were higher in the SLC10A7 knockout cells and lower in the SLC10A7-overexpressing cells. The SLC10A7 protein co-localized with STIM1, Orai1, and SERCA2. Most of the previously described human SLC10A7 mutations had no effect on the calcium influx and thus were confirmed to be functionally inactive. In the present study, SLC10A7 was established as a novel negative regulator of intracellular calcium signaling that most likely acts via STIM1, Orai1 and/or SERCA2 inhibition. Based on this, SLC10A7 is suggested to be named as negative regulator of intracellular calcium signaling (in short: RCAS).
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17
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Zhang YJ, Pan Q, Yu Y, Zhong XP. microRNA-519d Induces Autophagy and Apoptosis of Human Hepatocellular Carcinoma Cells Through Activation of the AMPK Signaling Pathway via Rab10. Cancer Manag Res 2020; 12:2589-2602. [PMID: 32346312 PMCID: PMC7167370 DOI: 10.2147/cmar.s207548] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Accepted: 12/09/2019] [Indexed: 12/11/2022] Open
Abstract
Background and Aim Hepatocellular carcinoma (HCC) is a type of cancer with high mortality rates. The overexpression of microRNA-519d (miR-519d) has been explored in different types of cancers, which could significantly help suppress cancer development. This study aimed to investigate the interaction of miR-519d with its target gene, Rab10, as well as its effects on cell proliferation and autophagy in HCC cells through modulation of the AMPK signaling pathway. Methods Microarray analysis was used to analyze the differentially expressed genes in HCC, and the target genes of the screened-out miRNA were predicted and verified. The expression of miR-519d and Rab10, AMPK signaling pathway-related proteins, apoptosis- and autophagy-related proteins was determined by RT-qPCR and Western blot analysis in HCC tissues and cell lines. Lastly, the effects of miR-519d and Rab10 in HCC cell proliferation, apoptosis, and mouse tumour xenograft in vivo were examined through gain- and loss-of-function experiments. Results MiR-519d was down-regulated and Rab10 was upregulated in HCC tissues and cell lines. Overexpression of miR-519d decreased the expression of Rab10, mTOR, and Bcl-2, but increased the expression of Bax, Beclin1, Atg5, and p53. Upregulated miR-519d and downregulated Rab10 expression suppressed cell proliferation and induced cell apoptosis and autophagy in HCC cells. Finally, upregulation of miR-519d inhibited tumour growth in vivo. Conclusion The result obtained in this study indicates that up-regulation of miR-519d inhibits proliferation and promotes apoptosis and autophagy of HCC cells through activation of the AMPK signaling pathway via downregulating Rab10, which provides a potential target for the treatment of HCC.
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Affiliation(s)
- Yi-Jie Zhang
- Department of Hepatobiliary and Organ Transplantation, The First Affiliated Hospital of China Medical University, Shenyang 110001, People's Republic of China.,The Key Laboratory of Organ Transplantation of Liaoning Province, The First Affiliated Hospital of China Medical University, Shenyang 110001, People's Republic of China
| | - Qi Pan
- Department of Hepatobiliary and Organ Transplantation, The First Affiliated Hospital of China Medical University, Shenyang 110001, People's Republic of China.,The Key Laboratory of Organ Transplantation of Liaoning Province, The First Affiliated Hospital of China Medical University, Shenyang 110001, People's Republic of China
| | - Yang Yu
- Department of Hepatobiliary and Organ Transplantation, The First Affiliated Hospital of China Medical University, Shenyang 110001, People's Republic of China.,The Key Laboratory of Organ Transplantation of Liaoning Province, The First Affiliated Hospital of China Medical University, Shenyang 110001, People's Republic of China
| | - Xin-Ping Zhong
- Department of Hepatobiliary and Organ Transplantation, The First Affiliated Hospital of China Medical University, Shenyang 110001, People's Republic of China.,The Key Laboratory of Organ Transplantation of Liaoning Province, The First Affiliated Hospital of China Medical University, Shenyang 110001, People's Republic of China
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18
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Yang PC, Jafri MS. Ca 2+ signaling in T lymphocytes: the interplay of the endoplasmic reticulum, mitochondria, membrane potential, and CRAC channels on transcription factor activation. Heliyon 2020; 6:e03526. [PMID: 32181396 PMCID: PMC7063158 DOI: 10.1016/j.heliyon.2020.e03526] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Revised: 09/12/2018] [Accepted: 02/28/2020] [Indexed: 11/16/2022] Open
Abstract
T cell receptor stimulation initiates a cascade of reactions that cause an increase in intracellular calcium (Ca2+) concentration mediated through inositol 1,4,5-trisphosphate (IP3). To understand the basic mechanisms by which the immune response in T cells is activated, it is useful to understand the signaling pathways that contain important targets for drugs in a quantitative fashion. A computational model helps us to understand how the selected elements in the pathways interact with each other, and which component plays the crucial role in systems. We have developed a mathematical model to explore the mechanism for controlling transcription factor activity, which regulates gene expression, by the modulation of calcium signaling triggered during T cell activation. The model simulates the activation and modulation of Ca2+ release-activated Ca2+ (CRAC) channels by mitochondrial dynamics and depletion of endoplasmic reticulum (ER) store, and also includes membrane potential in T-cells. The model simulates the experimental finding that increases in Ca2+ current enhances the activation of transcription factors and the Ca2+ influx through CRAC is also essential for the NFAT and NFκB activation. The model also suggests that plasma membrane Ca2+-ATPase (PMCA) controls a majority of the extrusion of Ca2+ and modulates the activation of CRAC channels. Furthermore, the model simulations explain how the complex interaction of the endoplasmic reticulum, membrane potential, mitochondria, and ion channels such as CRAC channels control T cell activation.
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Affiliation(s)
- Pei-Chi Yang
- Department of Physiology and Membrane Biology, University of California Davis, Davis, CA, 95616, USA.,Krasnow Institute for Advanced Study and School of Systems Biology, George Mason University, Fairfax, VA, 22030, USA
| | - M Saleet Jafri
- Krasnow Institute for Advanced Study and School of Systems Biology, George Mason University, Fairfax, VA, 22030, USA.,Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD, 20201, USA
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19
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Miteva KT, Pedicini L, Wilson LA, Jayasinghe I, Slip RG, Marszalek K, Gaunt HJ, Bartoli F, Deivasigamani S, Sobradillo D, Beech DJ, McKeown L. Rab46 integrates Ca 2+ and histamine signaling to regulate selective cargo release from Weibel-Palade bodies. J Cell Biol 2019; 218:2232-2246. [PMID: 31092558 PMCID: PMC6605797 DOI: 10.1083/jcb.201810118] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Revised: 03/24/2019] [Accepted: 04/22/2019] [Indexed: 12/12/2022] Open
Abstract
It is unclear how a plethora of stimuli evoke differential cargo secretion from endothelial cells to produce stimulus-appropriate responses. Miteva et al. show that Rab46 integrates histamine signaling and Ca2+ signals to regulate selective cargo release from Weibel-Palade bodies. Endothelial cells selectively release cargo stored in Weibel-Palade bodies (WPBs) to regulate vascular function, but the underlying mechanisms are poorly understood. Here we show that histamine evokes the release of the proinflammatory ligand, P-selectin, while diverting WPBs carrying non-inflammatory cargo away from the plasma membrane to the microtubule organizing center. This differential trafficking is dependent on Rab46 (CRACR2A), a newly identified Ca2+-sensing GTPase, which localizes to a subset of P-selectin–negative WPBs. After acute stimulation of the H1 receptor, GTP-bound Rab46 evokes dynein-dependent retrograde transport of a subset of WPBs along microtubules. Upon continued histamine stimulation, Rab46 senses localized elevations of intracellular calcium and evokes dispersal of microtubule organizing center–clustered WPBs. These data demonstrate for the first time that a Rab GTPase, Rab46, integrates G protein and Ca2+ signals to couple on-demand histamine signals to selective WPB trafficking.
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Affiliation(s)
- Katarina T Miteva
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
| | - Lucia Pedicini
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
| | - Lesley A Wilson
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
| | - Izzy Jayasinghe
- Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | - Raphael G Slip
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
| | - Katarzyna Marszalek
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
| | - Hannah J Gaunt
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
| | - Fiona Bartoli
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
| | - Shruthi Deivasigamani
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
| | - Diego Sobradillo
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
| | - David J Beech
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
| | - Lynn McKeown
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
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20
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Sharma M, Dwivedi D. A CRACker of an adaptor connects dynein-mediated transport to calcium signaling. J Cell Biol 2019; 218:1429-1431. [PMID: 31010854 PMCID: PMC6504887 DOI: 10.1083/jcb.201904069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Many different adaptor proteins activate the processivity of dynein-dynactin complexes and determine the specific cargo for retrograde transport by binding cargo receptors such as Rab GTP-binding (G) proteins. In this issue, Wang et al. (2019. J. Cell Biol. https://doi.org/10.1083/jcb.201806097) identify two GTPases that can function directly as dynein adaptors during endocytosis and are regulated by calcium.
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Affiliation(s)
- Mahak Sharma
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Punjab, India
| | - Devashish Dwivedi
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Punjab, India
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21
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Wang Y, Huynh W, Skokan TD, Lu W, Weiss A, Vale RD. CRACR2a is a calcium-activated dynein adaptor protein that regulates endocytic traffic. J Cell Biol 2019; 218:1619-1633. [PMID: 30814157 PMCID: PMC6504896 DOI: 10.1083/jcb.201806097] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Revised: 12/14/2018] [Accepted: 02/07/2019] [Indexed: 01/12/2023] Open
Abstract
Transport of intracellular cargo generally requires coiled-coil adaptor proteins that connect cargo-bound receptors, usually GTPases, to dynein motor complexes. Wang et al. report that two Rab GTPases, CRACR2a and Rab45, contain coiled-coil domains and can directly act as dynein adaptors with CRACR2a–dynein participating in calcium-regulated endocytic trafficking. Cytoplasmic dynein is a minus end–directed microtubule motor that transports intracellular cargoes. Transport is initiated by coiled-coil adaptors that (a) join dynein and its cofactor dynactin into a motile complex and (b) interact with a cargo-bound receptor, which is frequently a Rab GTPase on an organelle. Here, we report two novel dynein adaptors, CRACR2a and Rab45, that have a coiled-coil adaptor domain, a pair of EF-hands, and a Rab GTPase fused into a single polypeptide. CRACR2a-mediated, but not Rab45-mediated, dynein motility is activated by calcium in vitro. In Jurkat T cells, elevation of intracellular calcium activates CRACR2a-mediated dynein transport. We further found that T cell receptor activation induces the formation of CRACR2a puncta at the plasma membrane, which initially associate with the actin cortex and subsequently detach and travel along microtubules, suggestive of an endocytic process. These results provide the first examples of Rab GTPases that directly act as dynein adaptors and implicate CRACR2a–dynein in calcium-regulated endocytic trafficking.
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Affiliation(s)
- Yuxiao Wang
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA.,Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA
| | - Walter Huynh
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA.,Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA
| | - Taylor D Skokan
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA.,Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA
| | - Wen Lu
- Division of Rheumatology, Rosalind Russell and Ephraim P. Engleman Arthritis Research Center, Department of Medicine, University of California, San Francisco, San Francisco, CA
| | - Arthur Weiss
- Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA.,Division of Rheumatology, Rosalind Russell and Ephraim P. Engleman Arthritis Research Center, Department of Medicine, University of California, San Francisco, San Francisco, CA
| | - Ronald D Vale
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA .,Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA
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22
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Kappel S, Borgström A, Stokłosa P, Dörr K, Peinelt C. Store-operated calcium entry in disease: Beyond STIM/Orai expression levels. Semin Cell Dev Biol 2019; 94:66-73. [PMID: 30630032 DOI: 10.1016/j.semcdb.2019.01.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Revised: 11/29/2018] [Accepted: 01/05/2019] [Indexed: 12/19/2022]
Abstract
Precise intracellular calcium signaling is crucial to numerous cellular functions. In non-excitable cells, store-operated calcium entry (SOCE) is a key step in the generation of intracellular calcium signals. Tight regulation of SOCE is important, and dysregulation is involved in several pathophysiological cellular malfunctions. The current underlying SOCE, calcium release-activated calcium current (ICRAC), was first discovered almost three decades ago. Since its discovery, the molecular components of ICRAC, Orai1 and stromal interaction molecule 1 (STIM1), have been extensively investigated. Several regulatory mechanisms and proteins contribute to alterations in SOCE and cellular malfunctions in cancer, immune and neurodegenerative diseases, inflammation, and neuronal disorders. This review summarizes these regulatory mechanisms, including glycosylation, pH sensing, and the regulatory proteins golli, α-SNAP, SARAF, ORMDL3, CRACR2A, and TRPM4 channels.
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Affiliation(s)
- Sven Kappel
- Institute of Biochemistry and Molecular Medicine, National Center of Competence in Research NCCR TransCure, University of Bern, Bühlstrasse 28, 3012 Bern, Switzerland
| | - Anna Borgström
- Institute of Biochemistry and Molecular Medicine, National Center of Competence in Research NCCR TransCure, University of Bern, Bühlstrasse 28, 3012 Bern, Switzerland
| | - Paulina Stokłosa
- Institute of Biochemistry and Molecular Medicine, National Center of Competence in Research NCCR TransCure, University of Bern, Bühlstrasse 28, 3012 Bern, Switzerland
| | | | - Christine Peinelt
- Institute of Biochemistry and Molecular Medicine, National Center of Competence in Research NCCR TransCure, University of Bern, Bühlstrasse 28, 3012 Bern, Switzerland.
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23
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Woo JS, Srikanth S, Kim KD, Elsaesser H, Lu J, Pellegrini M, Brooks DG, Sun Z, Gwack Y. CRACR2A-Mediated TCR Signaling Promotes Local Effector Th1 and Th17 Responses. THE JOURNAL OF IMMUNOLOGY 2018; 201:1174-1185. [PMID: 29987160 DOI: 10.4049/jimmunol.1800659] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 06/12/2018] [Indexed: 12/24/2022]
Abstract
Ca2+ release-activated Ca2+ channel regulator 2A (CRACR2A) is expressed abundantly in T cells and acts as a signal transmitter between TCR stimulation and activation of the Ca2+/NFAT and JNK/AP1 pathways. CRACR2A has been linked to human diseases in numerous genome-wide association studies and was shown to be one of the most sensitive targets of the widely used statin drugs. However, the physiological role of CRACR2A in T cell functions remains unknown. In this study, using transgenic mice for tissue-specific deletion, we show that CRACR2A promotes Th1 responses and effector function of Th17 cells. CRACR2A was abundantly expressed in Th1 and Th17 cells. In vitro, deficiency of CRACR2A decreased Th1 differentiation under nonpolarizing conditions, whereas the presence of polarizing cytokines compensated this defect. Transcript analysis showed that weakened TCR signaling by deficiency of CRACR2A failed to promote Th1 transcriptional program. In vivo, conditional deletion of CRACR2A in T cells alleviated Th1 responses to acute lymphocytic choriomeningitis virus infection and imparted resistance to experimental autoimmune encephalomyelitis. Analysis of CNS from experimental autoimmune encephalomyelitis-induced mice showed impaired effector functions of both Th1 and Th17 cell types, which correlated with decreased pathogenicity. Collectively, our findings demonstrate the requirement of CRACR2A-mediated TCR signaling in Th1 responses as well as pathogenic conversion of Th17 cells, which occurs at the site of inflammation.
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Affiliation(s)
- Jin Seok Woo
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095
| | - Sonal Srikanth
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095
| | - Kyun-Do Kim
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095
| | - Heidi Elsaesser
- Princess Margaret Cancer Center, University Health Network, Toronto, Ontario M5G 2M9, Canada.,Department of Immunology, University of Toronto, Toronto, Ontario M5G 2M9, Canada
| | - Jing Lu
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, CA 90095; and
| | - Matteo Pellegrini
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, CA 90095; and
| | - David G Brooks
- Princess Margaret Cancer Center, University Health Network, Toronto, Ontario M5G 2M9, Canada.,Department of Immunology, University of Toronto, Toronto, Ontario M5G 2M9, Canada
| | - Zuoming Sun
- Division of Molecular Immunology, Beckman Research Institute of the City of Hope, Duarte, CA 91010
| | - Yousang Gwack
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095;
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24
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Robinson SW, Bourgognon JM, Spiers JG, Breda C, Campesan S, Butcher A, Mallucci GR, Dinsdale D, Morone N, Mistry R, Smith TM, Guerra-Martin M, Challiss RAJ, Giorgini F, Steinert JR. Nitric oxide-mediated posttranslational modifications control neurotransmitter release by modulating complexin farnesylation and enhancing its clamping ability. PLoS Biol 2018; 16:e2003611. [PMID: 29630591 PMCID: PMC5890968 DOI: 10.1371/journal.pbio.2003611] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Accepted: 02/20/2018] [Indexed: 11/18/2022] Open
Abstract
Nitric oxide (NO) regulates neuronal function and thus is critical for tuning neuronal communication. Mechanisms by which NO modulates protein function and interaction include posttranslational modifications (PTMs) such as S-nitrosylation. Importantly, cross signaling between S-nitrosylation and prenylation can have major regulatory potential. However, the exact protein targets and resulting changes in function remain elusive. Here, we interrogated the role of NO-dependent PTMs and farnesylation in synaptic transmission. We found that NO compromises synaptic function at the Drosophila neuromuscular junction (NMJ) in a cGMP-independent manner. NO suppressed release and reduced the size of available vesicle pools, which was reversed by glutathione (GSH) and occluded by genetic up-regulation of GSH-generating and de-nitrosylating glutamate-cysteine-ligase and S-nitroso-glutathione reductase activities. Enhanced nitrergic activity led to S-nitrosylation of the fusion-clamp protein complexin (cpx) and altered its membrane association and interactions with active zone (AZ) and soluble N-ethyl-maleimide-sensitive fusion protein Attachment Protein Receptor (SNARE) proteins. Furthermore, genetic and pharmacological suppression of farnesylation and a nitrosylation mimetic mutant of cpx induced identical physiological and localization phenotypes as caused by NO. Together, our data provide evidence for a novel physiological nitrergic molecular switch involving S-nitrosylation, which reversibly suppresses farnesylation and thereby enhances the net-clamping function of cpx. These data illustrate a new mechanistic signaling pathway by which regulation of farnesylation can fine-tune synaptic release.
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Affiliation(s)
- Susan W. Robinson
- MRC Toxicology Unit, University of Leicester, Leicester, United Kingdom
| | | | - Jereme G. Spiers
- MRC Toxicology Unit, University of Leicester, Leicester, United Kingdom
| | - Carlo Breda
- Department of Genetics and Genome Biology, University of Leicester, Leicester, United Kingdom
| | - Susanna Campesan
- Department of Genetics and Genome Biology, University of Leicester, Leicester, United Kingdom
| | - Adrian Butcher
- MRC Toxicology Unit, University of Leicester, Leicester, United Kingdom
| | - Giovanna R. Mallucci
- MRC Toxicology Unit, University of Leicester, Leicester, United Kingdom
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom
| | - David Dinsdale
- MRC Toxicology Unit, University of Leicester, Leicester, United Kingdom
| | - Nobuhiro Morone
- MRC Toxicology Unit, University of Leicester, Leicester, United Kingdom
| | - Raj Mistry
- Department of Molecular and Cell Biology, University of Leicester, Leicester, United Kingdom
| | - Tim M. Smith
- MRC Toxicology Unit, University of Leicester, Leicester, United Kingdom
| | | | - R. A. John Challiss
- Department of Molecular and Cell Biology, University of Leicester, Leicester, United Kingdom
| | - Flaviano Giorgini
- Department of Genetics and Genome Biology, University of Leicester, Leicester, United Kingdom
| | - Joern R. Steinert
- MRC Toxicology Unit, University of Leicester, Leicester, United Kingdom
- * E-mail:
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25
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Yamaguchi Y, Sakai E, Okamoto K, Kajiya H, Okabe K, Naito M, Kadowaki T, Tsukuba T. Rab44, a novel large Rab GTPase, negatively regulates osteoclast differentiation by modulating intracellular calcium levels followed by NFATc1 activation. Cell Mol Life Sci 2018; 75:33-48. [PMID: 28791425 PMCID: PMC11105776 DOI: 10.1007/s00018-017-2607-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Revised: 07/04/2017] [Accepted: 08/02/2017] [Indexed: 11/29/2022]
Abstract
Rab44 is an atypical Rab GTPase that contains some additional domains such as the EF-hand and coiled-coil domains as well as Rab-GTPase domain. Although Rab44 genes have been found in mammalian genomes, no studies concerning Rab44 have been reported yet. Here, we identified Rab44 as an upregulated protein during osteoclast differentiation. Knockdown of Rab44 by small interfering RNA promotes RANKL-induced osteoclast differentiation of the murine monocytic cell line, RAW-D or of bone marrow-derived macrophages (BMMs). In contrast, overexpression of Rab44 prevents osteoclast differentiation. Rab44 was localized in the Golgi complex and lysosomes, and Rab44 overexpression caused an enlargement of early endosomes. A series of deletion mutant studies of Rab44 showed that the coiled-coil domain and lipidation sites of Rab44 is important for regulation of osteoclast differentiation. Mechanistically, Rab44 affects nuclear factor of activated T-cells c1 (NFATc1) signaling in RANKL-stimulated macrophages. Moreover, Rab44 depletion caused an elevation in intracellular Ca2+ transients upon RANKL stimulation, and particularly regulated lysosomal Ca2+ influx. Taken together, these results suggest that Rab44 negatively regulates osteoclast differentiation by modulating intracellular Ca2+ levels followed by NFATc1 activation.
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Affiliation(s)
- Yu Yamaguchi
- Division of Dental Pharmacology, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, 852-8588, Japan
| | - Eiko Sakai
- Division of Dental Pharmacology, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, 852-8588, Japan
| | - Kuniaki Okamoto
- Division of Dental Pharmacology, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, 852-8588, Japan
| | - Hiroshi Kajiya
- Department of Physiological Science and Molecular Biology, Fukuoka Dental College, Fukuoka, 814-0193, Japan
| | - Koji Okabe
- Department of Physiological Science and Molecular Biology, Fukuoka Dental College, Fukuoka, 814-0193, Japan
| | - Mariko Naito
- Division of Microbiology and Oral Infection, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, 852-8588, Japan
| | - Tomoko Kadowaki
- Division of Frontier Life Science, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, 852-8588, Japan
| | - Takayuki Tsukuba
- Division of Dental Pharmacology, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, 852-8588, Japan.
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26
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Abstract
More than 60 Rab GTPases exist in the human genome to regulate vesicle trafficking between organelles. Rab GTPases are members of the Ras GTPase superfamily that broadly control budding, uncoating, motility and fusion of vesicles in most cell types. Rab proteins interconvert between active, GTP-bound form and inactive, GDP-bound form. In their active conformation, they interact with various effector molecules to carry out diverse functions. Rab GTPases are usually small containing only a GTPase domain with a C-terminal prenylation site for membrane anchoring. Recently, we identified a large G protein, CRACR2A (CRAC channel regulator 2A), which uncovers novel functions of Rab GTPases. First, CRACR2A encodes a large Rab GTPase containing multiple functional domains contrary to small Rab GTPases. Second, CRACR2A plays an unexpected role in regulating intracellular signaling pathways important for T cell activation, unlike the canonical role of small Rab GTPases. Vesicles containing CRACR2A bud out from the proximal Golgi area and translocate into the immunological synapse to activate these signaling pathways. Third, instead of recycling, CRACR2A is consumed by a unidirectional pathway. These events are sequentially regulated by prenylation, GTP binding, protein interaction with a signaling adaptor Vav1, and degradation. Together, our findings reveal a novel function of a large Rab GTPase in intracellular signaling pathways, which may be shared by other large Rab GTPases, Rab44 and Rab45.
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Affiliation(s)
- Sonal Srikanth
- a Department of Physiology , David Geffen School of Medicine, UCLA , Los Angeles , CA , USA
| | - Jin Seok Woo
- a Department of Physiology , David Geffen School of Medicine, UCLA , Los Angeles , CA , USA
| | - Yousang Gwack
- a Department of Physiology , David Geffen School of Medicine, UCLA , Los Angeles , CA , USA
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27
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Immunological Disorders: Regulation of Ca 2+ Signaling in T Lymphocytes. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 993:397-424. [PMID: 28900926 DOI: 10.1007/978-3-319-57732-6_21] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Engagement of T cell receptors (TCRs) with cognate antigens triggers cascades of signaling pathways in helper T cells. TCR signaling is essential for the effector function of helper T cells including proliferation, differentiation, and cytokine production. It also modulates effector T cell fate by inducing cell death, anergy (nonresponsiveness), exhaustion, and generation of regulatory T cells. One of the main axes of TCR signaling is the Ca2+-calcineurin-nuclear factor of activated T cells (NFAT) signaling pathway. Stimulation of TCRs triggers depletion of intracellular Ca2+ store and, in turn, activates store-operated Ca2+ entry (SOCE) to raise the intracellular Ca2+ concentration. SOCE in T cells is mediated by the Ca2+ release-activated Ca2+ (CRAC) channels, which have been very well characterized in terms of their electrophysiological properties. Identification of STIM1 as a sensor to detect depletion of the endoplasmic reticulum (ER) Ca2+ store and Orai1 as the pore subunit of CRAC channels has dramatically advanced our understanding of the regulatory mechanism of Ca2+ signaling in T cells. In this review, we discuss our current understanding of Ca2+ signaling in T cells with specific focus on the mechanism of CRAC channel activation and regulation via protein interactions. In addition, we will discuss the role of CRAC channels in effector T cells, based on the analyses of genetically modified animal models.
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28
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Abstract
More than 60 Rab GTPases exist in the human genome to regulate vesicle trafficking between organelles. Rab GTPases are members of the Ras GTPase superfamily that broadly control budding, uncoating, motility and fusion of vesicles in most cell types. Rab proteins interconvert between active, GTP-bound form and inactive, GDP-bound form. In their active conformation, they interact with various effector molecules to carry out diverse functions. Rab GTPases are usually small containing only a GTPase domain with a C-terminal prenylation site for membrane anchoring. Recently, we identified a large G protein, CRACR2A (CRAC channel regulator 2A), which uncovers novel functions of Rab GTPases. First, CRACR2A encodes a large Rab GTPase containing multiple functional domains contrary to small Rab GTPases. Second, CRACR2A plays an unexpected role in regulating intracellular signaling pathways important for T cell activation, unlike the canonical role of small Rab GTPases. Vesicles containing CRACR2A bud out from the proximal Golgi area and translocate into the immunological synapse to activate these signaling pathways. Third, instead of recycling, CRACR2A is consumed by a unidirectional pathway. These events are sequentially regulated by prenylation, GTP binding, protein interaction with a signaling adaptor Vav1, and degradation. Together, our findings reveal a novel function of a large Rab GTPase in intracellular signaling pathways, which may be shared by other large Rab GTPases, Rab44 and Rab45.
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Affiliation(s)
- Sonal Srikanth
- a Department of Physiology , David Geffen School of Medicine, UCLA , Los Angeles , CA , USA
| | - Jin Seok Woo
- a Department of Physiology , David Geffen School of Medicine, UCLA , Los Angeles , CA , USA
| | - Yousang Gwack
- a Department of Physiology , David Geffen School of Medicine, UCLA , Los Angeles , CA , USA
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