1
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Sun Y, Xu C, Jiang Z, Jiang X. DEF6(differentially exprehomolog) exacerbates pathological cardiac hypertrophy via RAC1. Cell Death Dis 2023; 14:483. [PMID: 37524688 PMCID: PMC10390462 DOI: 10.1038/s41419-023-05948-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Revised: 06/15/2023] [Accepted: 07/04/2023] [Indexed: 08/02/2023]
Abstract
Pathological cardiac hypertrophy involves multiple regulators and several signal transduction pathways. Currently, the mechanisms of it are not well understood. Differentially expressed in FDCP 6 homolog (DEF6) was reported to participate in immunity, bone remodeling, and cancers. The effects of DEF6 on pathological cardiac hypertrophy, however, have not yet been fully characterized. We initially determined the expression profile of DEF6 and found that DEF6 was upregulated in hypertrophic hearts and cardiomyocytes. Our in vivo results revealed that DEF6 deficiency in mice alleviated transverse aortic constriction (TAC)-induced cardiac hypertrophy, fibrosis, dilation and dysfunction of left ventricle. Conversely, cardiomyocyte-specific DEF6-overexpression aggravated the hypertrophic phenotype in mice under chronic pressure overload. Similar to the animal experiments, the in vitro data showed that adenovirus-mediated knockdown of DEF6 remarkably inhibited phenylephrine (PE)-induced cardiomyocyte hypertrophy, whereas DEF6 overexpression exerted the opposite effects. Mechanistically, exploration of the signal pathways showed that the mitogen-activated extracellular signal-regulated kinase 1/2 (MEK1/2)-extracellular signal-regulated kinase 1/2 (ERK1/2) cascade might be involved in the prohypertrophic effect of DEF6. Coimmunoprecipitation and GST (glutathione S-transferase) pulldown analyses demonstrated that DEF6 can directly interact with small GTPase Ras-related C3 botulinum toxin substrate 1 (Rac1), and the Rac1 activity assay revealed that the activity of Rac1 is altered with DEF6 expression in TAC-cardiac hypertrophy and PE-triggered cardiomyocyte hypertrophy. In the end, western blot and rescue experiments using Rac1 inhibitor NSC23766 and the constitutively active mutant Rac1(G12V) verified the requirement of Rac1 and MEK1/2-ERK1/2 activation for DEF6-mediated pathological cardiac hypertrophy. Our study substantiates that DEF6 acts as a deleterious regulator of cardiac hypertrophy by activating the Rac1 and MEK1/2-ERK1/2 signaling pathways, and suggests that DEF6 may be a potential treatment target for heart failure.
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Affiliation(s)
- Yan Sun
- Department of Gastroenterology, Shengjing Hospital of China Medical University, 110022, Shenyang, Liaoning Province, China
| | - Changlu Xu
- Department of Cardiology, Shengjing Hospital of China Medical University, 110022, Shenyang, Liaoning Province, China
| | - Zhongxiu Jiang
- Department of Oncology, Shengjing Hospital of China Medical University, 110022, Shenyang, Liaoning Province, China
| | - Xi Jiang
- Department of Cardiology, Shengjing Hospital of China Medical University, 110022, Shenyang, Liaoning Province, China.
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2
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Chen Z, Flores Castro D, Gupta S, Phalke S, Manni M, Rivera-Correa J, Jessberger R, Zaghouani H, Giannopoulou E, Pannellini T, Pernis AB. Interleukin-13 Receptor α1-Mediated Signaling Regulates Age-Associated/Autoimmune B Cell Expansion and Lupus Pathogenesis. Arthritis Rheumatol 2022; 74:1544-1555. [PMID: 35438841 PMCID: PMC9427689 DOI: 10.1002/art.42146] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Revised: 02/11/2022] [Accepted: 04/12/2022] [Indexed: 11/11/2022]
Abstract
OBJECTIVE Age-associated/autoimmune B cells (ABCs) are an emerging B cell subset with aberrant expansion in systemic lupus erythematosus. ABC generation and differentiation exhibit marked sexual dimorphism, and Toll-like receptor 7 (TLR-7) engagement is a key contributor to these sex differences. ABC generation is also controlled by interleukin-21 (IL-21) and its interplay with interferon-γ and IL-4. This study was undertaken to investigate whether IL-13 receptor α1 (IL-13Rα1), an X-linked receptor that transmits IL-4/IL-13 signals, regulates ABCs and lupus pathogenesis. METHODS Mice lacking DEF-6 and switch-associated protein 70 (double-knockout [DKO]), which preferentially develop lupus in females, were crossed with IL-13Rα1-knockout mice. IL-13Rα1-knockout male mice were also crossed with Y chromosome autoimmune accelerator (Yaa) DKO mice, which overexpress TLR-7 and develop severe disease. ABCs were assessed using flow cytometry and RNA-Seq. Lupus pathogenesis was evaluated using serologic and histologic analyses. RESULTS ABCs expressed higher levels of IL-13Rα1 than follicular B cells. The absence of IL-13Rα1 in either DKO female mice or Yaa DKO male mice decreased the accumulation of ABCs, the differentiation of ABCs into plasmablasts, and autoantibody production. Lack of IL-13Rα1 also prolonged survival and delayed the development of tissue inflammation. IL-13Rα1 deficiency diminished in vitro generation of ABCs, an effect that, surprisingly, could be observed in response to IL-21 alone. RNA-Seq revealed that ABCs lacking IL-13Rα1 down-regulated some histologic characteristics of B cells but up-regulated myeloid markers and proinflammatory mediators. CONCLUSION Our findings indicate a novel role for IL-13Rα1 in controlling ABC generation and differentiation, suggesting that IL-13Rα1 contributes to these effects by regulating a subset of IL-21-mediated signaling events. These results also suggest that X-linked genes besides TLR7 participate in the regulation of ABCs in lupus.
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Affiliation(s)
- Zhu Chen
- Autoimmunity and Inflammation Program, Hospital for Special Surgery, New York, NY, USA
- Department of Rheumatology and Immunology, the First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, China
| | - Danny Flores Castro
- Autoimmunity and Inflammation Program, Hospital for Special Surgery, New York, NY, USA
| | - Sanjay Gupta
- Autoimmunity and Inflammation Program, Hospital for Special Surgery, New York, NY, USA
| | - Swati Phalke
- Autoimmunity and Inflammation Program, Hospital for Special Surgery, New York, NY, USA
| | - Michela Manni
- Autoimmunity and Inflammation Program, Hospital for Special Surgery, New York, NY, USA
| | - Juan Rivera-Correa
- Autoimmunity and Inflammation Program, Hospital for Special Surgery, New York, NY, USA
| | - Rolf Jessberger
- Institute of Physiological Chemistry, Medical Faculty, Technische Universitat, Dresden, Germany
| | - Habib Zaghouani
- Department of Molecular Microbiology and Immunology, University of Missouri School of Medicine, Columbia, MO
- Department of Neurology, University of Missouri School of Medicine, Columbia, MO
- Department of Child Health, University of Missouri School of Medicine, Columbia, MO
| | - Evgenia Giannopoulou
- David Z. Rosensweig Genomics Research Center, Hospital for Special Surgery, New York, NY, USA
- Biological Sciences Department, New York City College of Technology, City University of New York, Brooklyn, NY, USA
| | - Tania Pannellini
- Research Division and Precision Medicine Laboratory, Hospital for Special Surgery, New York, NY, USA
| | - Alessandra B. Pernis
- Autoimmunity and Inflammation Program, Hospital for Special Surgery, New York, NY, USA
- David Z. Rosensweig Genomics Research Center, Hospital for Special Surgery, New York, NY, USA
- Department of Medicine, Weill Cornell Medicine, New York, NY, USA
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3
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Lu L. Mobilizing ER IP3 receptors as a mechanism to enhance calcium signaling. Cell Mol Immunol 2021; 18:2284-2285. [PMID: 34253857 PMCID: PMC8429457 DOI: 10.1038/s41423-021-00725-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Accepted: 06/09/2021] [Indexed: 02/06/2023] Open
Affiliation(s)
- Linrong Lu
- grid.13402.340000 0004 1759 700XInstitute of Immunology, and Department of Rheumatology in Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, P. R. China ,grid.13402.340000 0004 1759 700XZhejiang University-University of Edinburgh Institute, Zhejiang University School of Medicine, Haining, P. R. China ,grid.13402.340000 0004 1759 700XDr. Li Dak Sum and Yip Yio Chin Center for Stem Cells and Regenerative Medicine, Zhejiang University School of Medicine, Hangzhou, P. R. China
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4
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Ricker E, Manni M, Flores-Castro D, Jenkins D, Gupta S, Rivera-Correa J, Meng W, Rosenfeld AM, Pannellini T, Bachu M, Chinenov Y, Sculco PK, Jessberger R, Prak ETL, Pernis AB. Altered function and differentiation of age-associated B cells contribute to the female bias in lupus mice. Nat Commun 2021; 12:4813. [PMID: 34376664 PMCID: PMC8355159 DOI: 10.1038/s41467-021-25102-8] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Accepted: 07/15/2021] [Indexed: 12/11/2022] Open
Abstract
Differences in immune responses to viruses and autoimmune diseases such as systemic lupus erythematosus (SLE) can show sexual dimorphism. Age-associated B cells (ABC) are a population of CD11c+T-bet+ B cells critical for antiviral responses and autoimmune disorders. Absence of DEF6 and SWAP-70, two homologous guanine exchange factors, in double-knock-out (DKO) mice leads to a lupus-like syndrome in females marked by accumulation of ABCs. Here we demonstrate that DKO ABCs show sex-specific differences in cell number, upregulation of an ISG signature, and further differentiation. DKO ABCs undergo oligoclonal expansion and differentiate into both CD11c+ and CD11c- effector B cell populations with pathogenic and pro-inflammatory function as demonstrated by BCR sequencing and fate-mapping experiments. Tlr7 duplication in DKO males overrides the sex-bias and further augments the dissemination and pathogenicity of ABCs, resulting in severe pulmonary inflammation and early mortality. Thus, sexual dimorphism shapes the expansion, function and differentiation of ABCs that accompanies TLR7-driven immunopathogenesis.
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Affiliation(s)
- Edd Ricker
- Autoimmunity and Inflammation Program, Hospital for Special Surgery, New York, NY, USA
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York, NY, USA
| | - Michela Manni
- Autoimmunity and Inflammation Program, Hospital for Special Surgery, New York, NY, USA
| | - Danny Flores-Castro
- Autoimmunity and Inflammation Program, Hospital for Special Surgery, New York, NY, USA
| | - Daniel Jenkins
- Autoimmunity and Inflammation Program, Hospital for Special Surgery, New York, NY, USA
| | - Sanjay Gupta
- Autoimmunity and Inflammation Program, Hospital for Special Surgery, New York, NY, USA
| | - Juan Rivera-Correa
- Autoimmunity and Inflammation Program, Hospital for Special Surgery, New York, NY, USA
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York, NY, USA
| | - Wenzhao Meng
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, Philadelphia, PA, USA
| | - Aaron M Rosenfeld
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, Philadelphia, PA, USA
| | - Tania Pannellini
- Research Division and Precision Medicine Laboratory, Hospital for Special Surgery, New York, NY, USA
| | - Mahesh Bachu
- Arthritis and Tissue Degeneration Program, Hospital for Special Surgery, New York, NY, USA
| | - Yurii Chinenov
- David Z. Rosensweig Genomics Research Center, Hospital for Special Surgery, New York, NY, USA
| | - Peter K Sculco
- Department of Orthopedic Surgery, Hospital for Special Surgery, New York, NY, USA
| | - Rolf Jessberger
- Institute of Physiological Chemistry, Technische Universitat, Dresden, Germany
| | - Eline T Luning Prak
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, Philadelphia, PA, USA
| | - Alessandra B Pernis
- Autoimmunity and Inflammation Program, Hospital for Special Surgery, New York, NY, USA.
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York, NY, USA.
- David Z. Rosensweig Genomics Research Center, Hospital for Special Surgery, New York, NY, USA.
- Department of Medicine, Weill Cornell Medicine, New York, NY, USA.
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5
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Popović J, Wellstein I, Pernis A, Jessberger R, Ocaña-Morgner C. Control of GM-CSF-Dependent Dendritic Cell Differentiation and Maturation by DEF6 and SWAP-70. THE JOURNAL OF IMMUNOLOGY 2020; 205:1306-1317. [PMID: 32709659 DOI: 10.4049/jimmunol.2000020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Accepted: 06/30/2020] [Indexed: 11/19/2022]
Abstract
Although GM-CSF has been widely used in dendritic cell (DC) research, the mechanisms, factors, and signals regulating steady-state differentiation and maturation of GM-CSF-dependent DCs are insufficiently known. We found that the absence, individually or combined, of the related proteins DEF6 and SWAP-70 strongly enhances differentiation of murine GM-CSF-derived DCs. Contrasting SWAP-70, control through DEF6 does not depend on RHOA activation. DEF6 deficiency leads to expression of the DC-specific transcription factor ZBTB46 and prolonged STAT5 activation in GM-CSF cultures. SWAP-70 and DEF6-mediated restriction of DC differentiation converges mechanistically at the NF-κB pathway. DEF6 acts at early stages of DC differentiation in CD115-cKIT+ myeloid DC progenitors, whereas SWAP-70 acts subsequently. SWAP-70 and DEF6 regulate steady-state DC cytokine expression as well as in vivo accumulation in lymphatic tissue of migratory DCs. Our studies thus elucidate previously unknown roles of two closely related factors with distinct and complementary activities in DC differentiation and steady-state DC function.
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Affiliation(s)
- Jelena Popović
- Institut für Physiologische Chemie, Medizinische Fakultät Carl Gustav Carus, Technische Unversität Dresden, D-01307 Dresden, Germany; and
| | - Inga Wellstein
- Institut für Physiologische Chemie, Medizinische Fakultät Carl Gustav Carus, Technische Unversität Dresden, D-01307 Dresden, Germany; and
| | - Alessandra Pernis
- Autoimmunity and Inflammation Program, Hospital for Special Surgery, New York, NY 10021
| | - Rolf Jessberger
- Institut für Physiologische Chemie, Medizinische Fakultät Carl Gustav Carus, Technische Unversität Dresden, D-01307 Dresden, Germany; and
| | - Carlos Ocaña-Morgner
- Institut für Physiologische Chemie, Medizinische Fakultät Carl Gustav Carus, Technische Unversität Dresden, D-01307 Dresden, Germany; and
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6
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Deng S, Zhou X, Xu J. Checkpoints Under Traffic Control: From and to Organelles. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1248:431-453. [DOI: 10.1007/978-981-15-3266-5_18] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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7
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Human DEF6 deficiency underlies an immunodeficiency syndrome with systemic autoimmunity and aberrant CTLA-4 homeostasis. Nat Commun 2019; 10:3106. [PMID: 31308374 PMCID: PMC6629652 DOI: 10.1038/s41467-019-10812-x] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Accepted: 05/29/2019] [Indexed: 12/15/2022] Open
Abstract
Immune responses need to be controlled tightly to prevent autoimmune diseases, yet underlying molecular mechanisms remain partially understood. Here, we identify biallelic mutations in three patients from two unrelated families in differentially expressed in FDCP6 homolog (DEF6) as the molecular cause of an inborn error of immunity with systemic autoimmunity. Patient T cells exhibit impaired regulation of CTLA-4 surface trafficking associated with reduced functional CTLA-4 availability, which is replicated in DEF6-knockout Jurkat cells. Mechanistically, we identify the small GTPase RAB11 as an interactor of the guanine nucleotide exchange factor DEF6, and find disrupted binding of mutant DEF6 to RAB11 as well as reduced RAB11+CTLA-4+ vesicles in DEF6-mutated cells. One of the patients has been treated with CTLA-4-Ig and achieved sustained remission. Collectively, we uncover DEF6 as player in immune homeostasis ensuring availability of the checkpoint protein CTLA-4 at T-cell surface, identifying a potential target for autoimmune and/or cancer therapy. CTLA-4 is critical for balancing protective immunity with self-tolerance. Here the authors identify homozygous DEF6 mutations in patients with severe autoimmunity, one of which received and responds to CTLA-4-Ig, and show that DEF6 is crucial for CTLA-4 cell surface trafficking and immune regulatory function.
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8
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Anguita E, Villalobo A. Ca 2+ signaling and Src-kinases-controlled cellular functions. Arch Biochem Biophys 2018; 650:59-74. [DOI: 10.1016/j.abb.2018.05.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Revised: 04/26/2018] [Accepted: 05/07/2018] [Indexed: 12/16/2022]
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9
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Zhang MS, Tran PM, Wolff AJ, Tremblay MM, Fosdick MG, Houtman JCD. Glycerol monolaurate induces filopodia formation by disrupting the association between LAT and SLP-76 microclusters. Sci Signal 2018; 11:11/528/eaam9095. [PMID: 29717064 DOI: 10.1126/scisignal.aam9095] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Glycerol monolaurate (GML) is a monoglyceride with potent antimicrobial properties that suppresses T cell receptor (TCR)-induced signaling and T cell effector function. Actin rearrangement is needed for the interaction of T cells with antigen-presenting cells and for migration to sites of infection. Because of the critical role actin rearrangement plays in T cell effector function, we analyzed the effect of GML on the rearrangement of the actin cytoskeleton after TCR activation. We found that GML-treated human T cells were less adherent than untreated T cells and did not form actin ring structures but instead developed numerous inappropriate actin-mediated filopodia. The formation of these filopodia was not due to disruption of TCR-proximal regulators of actin or microtubule polymerization. Instead, total internal reflection fluorescence microscopy demonstrated mislocalization of actin nucleation protein Arp2 microclusters, but not those containing the adaptor proteins SLP-76 and WASp, or the actin nucleation protein ARPC3, which are necessary for TCR-induced actin rearrangement. Additionally, SLP-76 microclusters colocalized with WASp and WAVE microclusters but not with LAT. Together, our data suggest that GML alters actin cytoskeletal rearrangements and identify diverse functions for GML as a T cell-suppressive agent.
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Affiliation(s)
- Michael S Zhang
- Department of Microbiology and Immunology, University of Iowa, Iowa City, IA 52242, USA
| | - Phuong M Tran
- Department of Microbiology and Immunology, University of Iowa, Iowa City, IA 52242, USA
| | - Alexander J Wolff
- Department of Microbiology and Immunology, University of Iowa, Iowa City, IA 52242, USA
| | - Mikaela M Tremblay
- Department of Microbiology and Immunology, University of Iowa, Iowa City, IA 52242, USA
| | - Micaela G Fosdick
- Biomedical Sciences Program, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Jon C D Houtman
- Department of Microbiology and Immunology, University of Iowa, Iowa City, IA 52242, USA. .,Biomedical Sciences Program, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
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10
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Genome-wide CRISPR screen identifies FAM49B as a key regulator of actin dynamics and T cell activation. Proc Natl Acad Sci U S A 2018; 115:E4051-E4060. [PMID: 29632189 DOI: 10.1073/pnas.1801340115] [Citation(s) in RCA: 70] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Despite decades of research, mechanisms controlling T cell activation remain only partially understood, which hampers T cell-based immune cancer therapies. Here, we performed a genome-wide CRISPR screen to search for genes that regulate T cell activation. Our screen confirmed many of the known regulators in proximal T cell receptor signaling and, importantly, also uncovered a previously uncharacterized regulator, FAM49B (family with sequence similarity 49 member B). FAM49B deficiency led to hyperactivation of Jurkat T cells following T cell receptor stimulation, as indicated by enhancement of CD69 induction, PAK phosphorylation, and actin assembly. FAM49B directly interacted with the active form of the small GTPase Rac, and genetic disruption of the FAM49B-Rac interaction compromised FAM49B function. Thus, FAM49B inhibits T cell activation by repressing Rac activity and modulating cytoskeleton reorganization.
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11
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Regulation of age-associated B cells by IRF5 in systemic autoimmunity. Nat Immunol 2018; 19:407-419. [PMID: 29483597 PMCID: PMC6095139 DOI: 10.1038/s41590-018-0056-8] [Citation(s) in RCA: 94] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Accepted: 01/23/2018] [Indexed: 12/20/2022]
Abstract
Age-associated B cells (ABCs) are a T-bet–dependent B cell subset,
which accumulates prematurely in autoimmune settings. The pathways regulating
ABCs in autoimmunity are largely unknown. SWAP-70 and
DEF6 (also known as IBP or SLAT) are the only two
members of the SWEF family, a unique family of Rho GTPase-regulatory proteins
that controls both cytoskeletal dynamics and IRF4 activity. Notably,
DEF6 is a newly identified human SLE-risk variant. Here we
show that the lupus syndrome that developed in SWEF-deficient mice is
accompanied by the accumulation of ABCs, which produce autoantibodies upon
stimulation. ABCs from SWEF-deficient mice exhibited a distinctive transcriptome
and a unique chromatin landscape characterized by enrichment in motifs bound by
transcription factors of the IRF family, AP-1/BATF, and T-bet. Enhanced ABC
formation in SWEF-deficient mice was controlled by interleukin 21 (IL-21) and
IRF5, whose variants are strongly associated with lupus. The lack of SWEF
proteins led to dysregulated IRF5 activity in response to IL-21 stimulation.
These studies thus uncover a new genetic pathway controlling ABCs in
autoimmunity.
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12
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Joshi RN, Binai NA, Marabita F, Sui Z, Altman A, Heck AJR, Tegnér J, Schmidt A. Phosphoproteomics Reveals Regulatory T Cell-Mediated DEF6 Dephosphorylation That Affects Cytokine Expression in Human Conventional T Cells. Front Immunol 2017; 8:1163. [PMID: 28993769 PMCID: PMC5622166 DOI: 10.3389/fimmu.2017.01163] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Accepted: 09/01/2017] [Indexed: 12/25/2022] Open
Abstract
Regulatory T cells (Tregs) control key events of immune tolerance, primarily by suppression of effector T cells. We previously revealed that Tregs rapidly suppress T cell receptor (TCR)-induced calcium store depletion in conventional CD4+CD25− T cells (Tcons) independently of IP3 levels, consequently inhibiting NFAT signaling and effector cytokine expression. Here, we study Treg suppression mechanisms through unbiased phosphoproteomics of primary human Tcons upon TCR stimulation and Treg-mediated suppression, respectively. Tregs induced a state of overall decreased phosphorylation as opposed to TCR stimulation. We discovered novel phosphosites (T595_S597) in the DEF6 (SLAT) protein that were phosphorylated upon TCR stimulation and conversely dephosphorylated upon coculture with Tregs. Mutation of these DEF6 phosphosites abrogated interaction of DEF6 with the IP3 receptor and affected NFAT activation and cytokine transcription in primary Tcons. This novel mechanism and phosphoproteomics data resource may aid in modifying sensitivity of Tcons to Treg-mediated suppression in autoimmune disease or cancer.
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Affiliation(s)
- Rubin N Joshi
- Unit of Computational Medicine, Center for Molecular Medicine, Department of Medicine Solna, Karolinska University Hospital, Science for Life Laboratory, Karolinska Institutet, Stockholm, Sweden
| | - Nadine A Binai
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, Netherlands.,Netherlands Proteomics Centre, Utrecht, Netherlands
| | - Francesco Marabita
- Unit of Computational Medicine, Center for Molecular Medicine, Department of Medicine Solna, Karolinska University Hospital, Science for Life Laboratory, Karolinska Institutet, Stockholm, Sweden
| | - Zhenhua Sui
- Division of Cell Biology, La Jolla Institute for Allergy and Immunology, La Jolla, CA, United States
| | - Amnon Altman
- Division of Cell Biology, La Jolla Institute for Allergy and Immunology, La Jolla, CA, United States
| | - Albert J R Heck
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, Netherlands.,Netherlands Proteomics Centre, Utrecht, Netherlands
| | - Jesper Tegnér
- Unit of Computational Medicine, Center for Molecular Medicine, Department of Medicine Solna, Karolinska University Hospital, Science for Life Laboratory, Karolinska Institutet, Stockholm, Sweden.,Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia.,Computer, Electrical and Mathematical Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - Angelika Schmidt
- Unit of Computational Medicine, Center for Molecular Medicine, Department of Medicine Solna, Karolinska University Hospital, Science for Life Laboratory, Karolinska Institutet, Stockholm, Sweden
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13
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The mTORC1-4E-BP-eIF4E axis controls de novo Bcl6 protein synthesis in T cells and systemic autoimmunity. Nat Commun 2017; 8:254. [PMID: 28811467 PMCID: PMC5557982 DOI: 10.1038/s41467-017-00348-3] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Accepted: 06/12/2017] [Indexed: 01/24/2023] Open
Abstract
Post-transcriptional modifications can control protein abundance, but the extent to which these alterations contribute to the expression of T helper (TH) lineage-defining factors is unknown. Tight regulation of Bcl6 expression, an essential transcription factor for T follicular helper (TFH) cells, is critical as aberrant TFH cell expansion is associated with autoimmune diseases, such as systemic lupus erythematosus (SLE). Here we show that lack of the SLE risk variant Def6 results in deregulation of Bcl6 protein synthesis in T cells as a result of enhanced activation of the mTORC1–4E-BP–eIF4E axis, secondary to aberrant assembly of a raptor–p62–TRAF6 complex. Proteomic analysis reveals that this pathway selectively controls the abundance of a subset of proteins. Rapamycin or raptor deletion ameliorates the aberrant TFH cell expansion in mice lacking Def6. Thus deregulation of mTORC1-dependent pathways controlling protein synthesis can result in T-cell dysfunction, indicating a mechanism by which mTORC1 can promote autoimmunity. Excessive expansion of the T follicular helper (TFH) cell pool is associated with autoimmune disease and Def6 has been identified as an SLE risk variant. Here the authors show that Def6 limits proliferation of TFH cells in mice via alteration of mTORC1 signaling and inhibition of Bcl6 expression.
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14
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Chandrasekaran U, Yi W, Gupta S, Weng CH, Giannopoulou E, Chinenov Y, Jessberger R, Weaver CT, Bhagat G, Pernis AB. Regulation of Effector Treg Cells in Murine Lupus. Arthritis Rheumatol 2017; 68:1454-66. [PMID: 26816213 DOI: 10.1002/art.39599] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Accepted: 01/14/2016] [Indexed: 01/05/2023]
Abstract
OBJECTIVE Treg cells need to acquire an effector phenotype to function in settings of inflammation. Whether effector Treg cells can limit disease severity in lupus is unknown. Interferon regulatory factor 4 (IRF-4) is an essential controller of effector Treg cells and regulates their ability to express interleukin-10 (IL-10). In non-Treg cells, IRF-4 activity is modulated by interactions with DEF-6 and its homolog switch-associated protein 70 (SWAP-70). Although mice lacking both DEF-6 and SWAP-70 (double-knockout [DKO] mice) develop lupus, they display normal survival, suggesting that in DKO mice, Treg cells can moderate disease development. The purpose of this study was to investigate whether Treg cells from DKO mice have an increased capacity to become effector Treg cells due to the ability of DEF-6 and SWAP-70 to restrain IRF-4 activity. METHODS Treg cells were evaluated by fluorescence-activated cell sorting. The B lymphocyte-induced maturation protein 1 (BLIMP-1)/IL-10 axis was assessed by crossing DKO mice with BLIMP-1-YFP-10BiT dual-reporter mice. Deletion of IRF-4 in Treg cells from DKO mice was achieved by generating FoxP3(Cre) IRF-4(fl/fl) DKO mice. RESULTS The concomitant absence of DEF-6 and SWAP-70 led to increased numbers of Treg cells, which acquired an effector phenotype in a cell-intrinsic manner. In addition, Treg cells from DKO mice exhibited enhanced expression of the BLIMP-1/IL-10 axis. Notably, DKO effector Treg cells survived and expanded as disease progressed. The accumulation of Treg cells from DKO mice was associated with the up-regulation of genes controlling autophagy. IRF-4 was required for the expansion and function of effector Treg cells from DKO mice. CONCLUSION This study revealed the existence of mechanisms that, by acting on IRF-4, can fine-tune the function and survival of effector Treg cells in lupus. These findings suggest that the existence of a powerful effector Treg cell compartment that successfully survives in an unfavorable inflammatory environment could limit disease development.
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Affiliation(s)
| | - Woelsung Yi
- Hospital for Special Surgery, New York, New York
| | - Sanjay Gupta
- Hospital for Special Surgery, New York, New York
| | - Chien-Huan Weng
- Hospital for Special Surgery and Weill Cornell Graduate School of Medical Sciences, New York, New York
| | - Eugenia Giannopoulou
- Hospital for Special Surgery, New York, and New York City College of Technology, City University of New York, Brooklyn, New York
| | | | | | | | - Govind Bhagat
- Columbia University Medical Center and New York Presbyterian Hospital, New York, New York
| | - Alessandra B Pernis
- Hospital for Special Surgery, Weill Cornell Graduate School of Medical Sciences, and Weill Cornell Medicine, Cornell University, New York, New York
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15
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Identification of a Novel Alternatively Spliced Form of Inflammatory Regulator SWAP-70-Like Adapter of T Cells. Int J Inflam 2017; 2017:1324735. [PMID: 28523202 PMCID: PMC5421089 DOI: 10.1155/2017/1324735] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2017] [Accepted: 03/27/2017] [Indexed: 11/18/2022] Open
Abstract
Activation of naive CD4+ T cells results in the development of several distinct subsets of effector Th cells, including Th2 cells that play a pivotal role in allergic inflammation and helminthic infections. SWAP-70-like adapter of T cells (SLAT), also known as Def6 or IBP, is a guanine nucleotide exchange factor for small GTPases, which regulates CD4+ T cell inflammatory responses by controlling Ca2+/NFAT signaling. In this study, we have identified a novel alternatively spliced isoform of SLAT, named SLAT2, which lacks the region encoded by exons 2-7 of the Def6 gene. SLAT2 was selectively expressed in differentiated Th2 cells after the second round of in vitro stimulation, but not in differentiated Th1, Th17, or regulatory T (Treg) cells. Functional assays revealed that SLAT2 shared with SLAT the ability to enhance T cell receptor- (TCR-) mediated activation of NFAT and production of IL-4 but was unable to enhance TCR-induced adhesion to ICAM-1. Ectopic expression of SLAT2 or SLAT in Jurkat T cells resulted in the expression of distinct forms of filopodia, namely, short versus long ones, respectively. These results demonstrate that modulating either SLAT2 or SLAT protein expression could play critical roles in cytokine production and actin reorganization during inflammatory immune responses.
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16
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Comrie WA, Burkhardt JK. Action and Traction: Cytoskeletal Control of Receptor Triggering at the Immunological Synapse. Front Immunol 2016; 7:68. [PMID: 27014258 PMCID: PMC4779853 DOI: 10.3389/fimmu.2016.00068] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2015] [Accepted: 02/12/2016] [Indexed: 01/03/2023] Open
Abstract
It is well known that F-actin dynamics drive the micron-scale cell shape changes required for migration and immunological synapse (IS) formation. In addition, recent evidence points to a more intimate role for the actin cytoskeleton in promoting T cell activation. Mechanotransduction, the conversion of mechanical input into intracellular biochemical changes, is thought to play a critical role in several aspects of immunoreceptor triggering and downstream signal transduction. Multiple molecules associated with signaling events at the IS have been shown to respond to physical force, including the TCR, costimulatory molecules, adhesion molecules, and several downstream adapters. In at least some cases, it is clear that the relevant forces are exerted by dynamics of the T cell actomyosin cytoskeleton. Interestingly, there is evidence that the cytoskeleton of the antigen-presenting cell also plays an active role in T cell activation, by countering the molecular forces exerted by the T cell at the IS. Since actin polymerization is itself driven by TCR and costimulatory signaling pathways, a complex relationship exists between actin dynamics and receptor activation. This review will focus on recent advances in our understanding of the mechanosensitive aspects of T cell activation, paying specific attention to how F-actin-directed forces applied from both sides of the IS fit into current models of receptor triggering and activation.
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Affiliation(s)
- William A Comrie
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia, Perelman School of Medicine, University of Pennsylvania , Philadelphia, PA , USA
| | - Janis K Burkhardt
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia, Perelman School of Medicine, University of Pennsylvania , Philadelphia, PA , USA
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17
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Côte M, Fos C, Canonigo-Balancio AJ, Ley K, Bécart S, Altman A. SLAT promotes TCR-mediated, Rap1-dependent LFA-1 activation and adhesion through interaction of its PH domain with Rap1. J Cell Sci 2015; 128:4341-52. [PMID: 26483383 DOI: 10.1242/jcs.172742] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Accepted: 10/09/2015] [Indexed: 01/13/2023] Open
Abstract
SLAT (also known as DEF6) promotes T cell activation and differentiation by regulating NFAT-Ca(2+) signaling. However, its role in TCR-mediated inside-out signaling, which induces integrin activation and T cell adhesion, a central process in T cell immunity and inflammation, has not been explored. Here, we show that SLAT is crucial for TCR-induced adhesion to ICAM-1 and affinity maturation of LFA-1 in CD4(+) T cells. Mechanistic studies revealed that SLAT interacts, through its PH domain, with a key component of inside-out signaling, namely the active form of the small GTPase Rap1 (which has two isoforms, Rap1A and Rap1B). This interaction has been further shown to facilitate the interdependent recruitment of Rap1 and SLAT to the T cell immunological synapse upon TCR engagement. Furthermore, a SLAT mutant lacking its PH domain drastically inhibited LFA-1 activation and CD4(+) T cell adhesion. Finally, we established that a constitutively active form of Rap1, which is present at the plasma membrane, rescues the defective LFA-1 activation and ICAM-1 adhesion in SLAT-deficient (Def6(-/-)) T cells. These findings ascribe a new function to SLAT, and identify Rap1 as a target of SLAT function in TCR-mediated inside-out signaling.
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Affiliation(s)
- Marjorie Côte
- Division of Cell Biology, La Jolla Institute for Allergy & Immunology, La Jolla, CA 92037, USA
| | - Camille Fos
- Division of Cell Biology, La Jolla Institute for Allergy & Immunology, La Jolla, CA 92037, USA
| | - Ann J Canonigo-Balancio
- Division of Cell Biology, La Jolla Institute for Allergy & Immunology, La Jolla, CA 92037, USA
| | - Klaus Ley
- Division of Inflammation Biology, La Jolla Institute for Allergy & Immunology, La Jolla, CA 92037, USA
| | - Stéphane Bécart
- Division of Cell Biology, La Jolla Institute for Allergy & Immunology, La Jolla, CA 92037, USA
| | - Amnon Altman
- Division of Cell Biology, La Jolla Institute for Allergy & Immunology, La Jolla, CA 92037, USA
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18
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Lei P, Xie J, Wang L, Yang X, Dai Z, Hu Y. microRNA-145 inhibits osteosarcoma cell proliferation and invasion by targeting ROCK1. Mol Med Rep 2014; 10:155-60. [PMID: 24789502 DOI: 10.3892/mmr.2014.2195] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Accepted: 03/12/2014] [Indexed: 11/05/2022] Open
Abstract
Osteosarcoma (OS), a malignant mesenchymal sarcoma, is the most frequent primary bone tumor, with a peak incidence in young children and adolescents. The downregulation of microRNA‑145 (miRNA/miR‑145) has previously been identified to be associated with the aggressiveness and metastasis of OS. However, the detailed regulatory mechanism by which miR‑145 inhibits OS remains largely unknown. The present study demonstrated that miR‑145 was significantly downregulated in OS tissues and KHOS and U2OS cell lines. Rho‑associated protein kinase 1 (ROCK1), a key regulator of actin cytoskeleton reorganization, was identified as a novel target of miR‑145. Ectopic expression of miR‑145 notably suppressed the protein expression of ROCK1 without affecting its mRNA level. Furthermore, the expression of ROCK1 was significantly increased in the OS tissues and in the KHOS and U2OS cells. It was further demonstrated that the overexpression of miR‑145 downregulated KHOS and U2OS cell proliferation and invasion, which was reversed by restoration of ROCK1. To the best of our knowledge, the present study demonstrates for the first time that, as a tumor suppressor, miRNA‑145 inhibits OS cell proliferation and invasion, at least in part by directly targeting ROCK1. These results indicate that miR‑145 may be a potential candidate for the diagnosis and treatment of OS.
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Affiliation(s)
- Pengfei Lei
- Department of Orthopedics, Xiangya Hospital of Central South University, Changsha, Hunan 410008, P.R. China
| | - Jie Xie
- Department of Orthopedics, Xiangya Hospital of Central South University, Changsha, Hunan 410008, P.R. China
| | - Long Wang
- Department of Orthopedics, Xiangya Hospital of Central South University, Changsha, Hunan 410008, P.R. China
| | - Xucheng Yang
- Department of Orthopedics, Xiangya Hospital of Central South University, Changsha, Hunan 410008, P.R. China
| | - Zixun Dai
- Department of Orthopedics, Xiangya Hospital of Central South University, Changsha, Hunan 410008, P.R. China
| | - Yihe Hu
- Department of Orthopedics, Xiangya Hospital of Central South University, Changsha, Hunan 410008, P.R. China
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19
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Wan X, Cheng Q, Peng R, Ma Z, Chen Z, Cao Y, Jiang B. ROCK1, a novel target of miR-145, promotes glioma cell invasion. Mol Med Rep 2014; 9:1877-82. [PMID: 24573110 DOI: 10.3892/mmr.2014.1982] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2013] [Accepted: 02/07/2014] [Indexed: 12/13/2022] Open
Abstract
Malignant glioma is the most common type of cancer in the central nervous system, with highly invasive characteristics. The Rho-associated protein kinase (ROCK1) has been found to act as key regulator of actin cytoskeleton reorganization, a process closely associated with cancer cell invasion. microRNA-145 (miRNA-145) has been recently shown to act as a suppressor in several types of tumor, including glioma. However, the exact regulatory mechanism by which miR-145 inhibits glioma still remains to be uncovered. In this study, we report that the miR-145 level was significantly reduced in glioma tissues and in the human glioma cell lines U87 and U251, as compared to matched adjacent and normal brain tissues. We then identified the ROCK1 gene as a novel target of miR-145. The expression of ROCK1 was markedly upregulated in glioma tissues, as well as in U87 and U251 cells. Moreover, miR-145 significantly inhibited ROCK1 protein expression in U87 cells. We further show that miR-145 transfection considerably reduced the invasive ability of U87 cells, and was accompanied by the downregulation of matrix metalloproteinase 2 and 9, an effect which could be attenuated by overexpression of ROCK1. In conclusion, the present study suggests that miR-145 can inhibit U87 glioma cell invasion, at least partially via downregulation of the RhoA/ROCK1 pathway. In conclusion, this is the first study to report that ROCK1, as a novel target of miR-145, acts as a positive regulator of glioma cell invasion. Therefore, ROCK1 may constitute a promising target for glioma treatment.
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Affiliation(s)
- Xin Wan
- Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, Hunan 410008, P.R. China
| | - Quan Cheng
- Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, Hunan 410008, P.R. China
| | - Renjun Peng
- Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, Hunan 410008, P.R. China
| | - Zhiming Ma
- Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, Hunan 410008, P.R. China
| | - Zigui Chen
- Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, Hunan 410008, P.R. China
| | - Yiqiang Cao
- Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, Hunan 410008, P.R. China
| | - Bing Jiang
- Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, Hunan 410008, P.R. China
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20
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T cell antigen receptor activation and actin cytoskeleton remodeling. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1838:546-56. [PMID: 23680625 DOI: 10.1016/j.bbamem.2013.05.004] [Citation(s) in RCA: 112] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 03/20/2013] [Accepted: 05/02/2013] [Indexed: 12/20/2022]
Abstract
T cells constitute a crucial arm of the adaptive immune system and their optimal function is required for a healthy immune response. After the initial step of T cell-receptor (TCR) triggering by antigenic peptide complexes on antigen presenting cell (APC), the T cell exhibits extensive cytoskeletal remodeling. This cytoskeletal remodeling leads to the formation of an "immunological synapse" [1] characterized by regulated clustering, segregation and movement of receptors at the interface. Synapse formation regulates T cell activation and response to antigenic peptides and proceeds via feedback between actin cytoskeleton and TCR signaling. Actin polymerization participates in various events during the synapse formation, maturation, and eventually its disassembly. There is increasing knowledge about the actin effectors that couple TCR activation to actin rearrangements [2,3], and how defects in these effectors translate into impairment of T cell activation. In this review we aim to summarize and integrate parts of what is currently known about this feedback process. In addition, in light of recent advancements in our understanding of TCR triggering and translocation at the synapse, we speculate on the organizational and functional diversity of microfilament architecture in the T cell. This article is part of a Special Issue entitled: Reciprocal influences between cell cytoskeleton and membrane channels, receptors and transporters. Guest Editor: Jean Claude Hervé.
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21
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Feau S, Schoenberger SP, Altman A, Bécart S. SLAT regulates CD8+ T cell clonal expansion in a Cdc42- and NFAT1-dependent manner. THE JOURNAL OF IMMUNOLOGY 2012. [PMID: 23197258 DOI: 10.4049/jimmunol.1201685] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
After antigenic stimulation, CD8(+) T cells undergo clonal expansion and differentiation into CTLs that can mount a strong defense against intracellular pathogens and tumors. SWAP-70-like adapter of T cells (SLAT), also known as Def6, is a novel guanine nucleotide exchange factor for the Cdc42 GTPase and plays a role in CD4(+) T cell activation and Th cell differentiation by controlling Ca(2+)/NFAT signaling, but its requirement in CD8(+) T cell response has not been explored. Using a range of transgenic and knockout in vivo systems, we show that SLAT is required for efficient expansion of CD8(+) T cells during the primary response but is not necessary for CTL differentiation. The reduced clonal expansion observed in the absence of SLAT resulted from a CD8(+) T cell-intrinsic proliferation defect and a reduced IL-2-dependent cell survival. On a molecular level, we show that Def6 deficiency resulted in defective TCR/CD28-induced NFAT translocation to the nucleus in CD8(+) T cells. Constitutively active Cdc42 or NFAT1 mutants fully restored the impaired expansion of Def6(-/-) CD8(+) T cells. Taken together, these data describe a new and pivotal role of SLAT-mediated NFAT activation in CD8(+) T cells, providing new insight into the signaling pathways involved in CD8(+) T cell proliferation.
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Affiliation(s)
- Sonia Feau
- Division of Developmental Immunology, La Jolla Institute for Allergy and Immunology, La Jolla, CA 92037, USA
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22
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Izsepi E, Himer L, Szilagyi O, Hajdu P, Panyi G, Laszlo G, Matko J. Membrane microdomain organization, calcium signal, and NFAT activation as an important axis in polarized Th cell function. Cytometry A 2012. [DOI: 10.1002/cyto.a.22234] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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23
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Abstract
Small GTPases like Rac2 are crucial regulators of many cell functions central to life itself. Our laboratory has recently found that phospholipase D2 (PLD2) can act as a guanine nucleotide exchange factor (GEF) for Rac2. PLD2 has a Pleckstrin Homology (PH) domain but does not bear a Dbl homology (DH) or DOCK homology region (DHR) domain. It has, however, a Phox (PX) domain upstream of its PH domain. To better understand the novel finding of PLD2 as an enhancer of GDP/GTP exchange, we modeled the N-terminal portion of PLD2 (as the crystal structure of this protein has not as of yet been resolved), and studied the correlation with two known GEFs, SWAP-70 and the Leukemic Associated RhoGEF (LARG). Structural similarities between PLD2's PH and SWAP-70s or LARG's PH domain are very extensive, while similarities between PLD2's PX and SWAP-70s or LARG's DH domains are less evident. This indicates that PLD functions as a GEF utilizing its PH domain and part of its PX domain and possibly other regions. All this makes PLD unique, and an entirely new class of GEF. By bearing two enzymatic activities (break down of PC and GDP/GTP exchange), it is realistic to assume that PLD is an important signaling node for several intracellular pathways. Future experiments will ascertain how the newly described PLD2's GEF is regulated in the context of cell activation.
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24
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Rougerie P, Delon J. Rho GTPases: masters of T lymphocyte migration and activation. Immunol Lett 2011; 142:1-13. [PMID: 22207038 DOI: 10.1016/j.imlet.2011.12.003] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2011] [Revised: 11/24/2011] [Accepted: 12/07/2011] [Indexed: 12/15/2022]
Abstract
Rho GTPases are key signal transducer elements activated in T cells by both chemokine and antigen receptors. These two signalling pathways control the two main functions of T lymphocytes: motility and activation. Rho GTPases are thus crucial for the development of an adequate immune response. In this review, we mostly focus on the roles of RhoA, Rac1 and Cdc42 in T cells. We show their importance in phenomena such as adhesion, morphological polarization, migration and antigen recognition.
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Affiliation(s)
- Pablo Rougerie
- Institut Cochin, Université Paris Descartes, Sorbonne Paris Cité, CNRS (UMR 8104), Paris, France; Inserm, U1016, Paris, France
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25
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Impairment of non-muscle myosin IIA in human CD4+ T cells contributes to functional deficits in the elderly. Cell Mol Immunol 2011; 9:86-96. [PMID: 21983869 DOI: 10.1038/cmi.2011.41] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Physiological aging imposes significant alterations in the repertoire of T cells and all associated functions. Although several studies have reported defects upon antigen-induced activation of T cells during aging, the molecular mechanisms that control T-cell receptor (TCR) downmodulation remain to be fully defined. While previous studies have assessed the role of F-actin in regulating activation-induced TCR internalization, few have delineated the roles of motor proteins, such as non-muscle myosin IIA (NMMIIA). In this study, we describe a series of experiments supporting the hypothesis that effective TCR downmodulation requires not only efficient reorganization of the actin cytoskeleton, but also functional NMMIIA. For the first time, we show that CD4(+) T cells from elderly human donors have dysfunctional NMMIIA that contributes to delaying activation-induced TCR internalization and impairing calcium mobilization. Additionally, our results demonstrate that chemical inhibition of NMMIIA in CD4(+) T cells from young donors also results in complete abrogation of TCR internalization, strongly supporting the fundamental role of NMMIIA in modulating this event. Recent observations that the generation of an efficient T-cell response requires migration prompted us to investigate whether NMMIIA also plays a regulatory role in CD4(+) T-cell migration. We show that chemical inhibition of NMMIIA downmodulates chemotactic migration in CD4(+) T cells from both young and elderly donors. Together, these data demonstrate a significant contribution of dysfunctional NMMIIA to TCR-mediated functional defects during aging.
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26
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Veillette A. Organization of immunoreceptor signaling by adapters. Immunol Rev 2009; 232:5-6. [PMID: 19909351 DOI: 10.1111/j.1600-065x.2009.00847.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- André Veillette
- Clinical Research Institute of Montreal, Montreal, QC, Canada.
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