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Paillon N, Ung TPL, Dogniaux S, Stringari C, Hivroz C. Label-free single-cell live imaging reveals fast metabolic switch in T lymphocytes. Mol Biol Cell 2024; 35:ar11. [PMID: 37971737 PMCID: PMC10881169 DOI: 10.1091/mbc.e23-01-0009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Revised: 09/29/2023] [Accepted: 11/06/2023] [Indexed: 11/19/2023] Open
Abstract
T-cell activation induces a metabolic switch generating energy for proliferation, survival, and functions. We used noninvasive label-free two-photon fluorescence lifetime microscopy (2P-FLIM) to map the spatial and temporal dynamics of the metabolic NAD(P)H co-enzyme during T lymphocyte activation. This provides a readout of the OXPHOS and glycolysis rates at a single-cell level. Analyzes were performed in the CD4+ leukemic T cell line Jurkat, and in human CD4+ primary T cells. Cells were activated on glass surfaces coated with activating antibodies mimicking immune synapse formation. Comparing the fraction of bound NAD(P)H between resting and activated T cells, we show that T-cell activation induces a rapid switch toward glycolysis. This occurs after 10 min and remains stable for one hour. Three-dimensional analyzes revealed that the intracellular distribution of fraction of bound NAD(P)H increases at the immune synapse in activated cells. Finally, we show that fraction of bound NAD(P)H tends to negatively correlate with spreading of activated T cells, suggesting a link between actin remodeling and metabolic changes. This study highlights that 2P-FLIM measurement of fraction of bound NAD(P)H is well suited to follow a fast metabolic switch in three dimensions, in single T lymphocytes with subcellular resolution.
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Affiliation(s)
- Noémie Paillon
- Institut Curie, PSL Research University, INSERM, U932 “Integrative analysis of T cell activation” team, 75005 Paris, France
| | - Thi Phuong Lien Ung
- Laboratory for Optics and Biosciences, École Polytechnique, CNRS, Inserm, Institut Polytechnique de Paris, 91128 Palaiseau, France
| | - Stéphanie Dogniaux
- Institut Curie, PSL Research University, INSERM, U932 “Integrative analysis of T cell activation” team, 75005 Paris, France
| | - Chiara Stringari
- Laboratory for Optics and Biosciences, École Polytechnique, CNRS, Inserm, Institut Polytechnique de Paris, 91128 Palaiseau, France
| | - Claire Hivroz
- Institut Curie, PSL Research University, INSERM, U932 “Integrative analysis of T cell activation” team, 75005 Paris, France
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2
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Henriques SN, Oliveira L, Santos RF, Carmo AM. CD6-mediated inhibition of T cell activation via modulation of Ras. Cell Commun Signal 2022; 20:184. [PMID: 36414966 PMCID: PMC9682754 DOI: 10.1186/s12964-022-00998-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Accepted: 10/16/2022] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND CD6 is one of many cell surface receptors known to regulate signal transduction upon T cell activation. However, whether CD6 mediates costimulatory or inhibitory signals is controversial. When T cells engage with antigen presenting cells (APCs), CD6 interacts with its ligand CD166 at the cell-cell interface while the cytosolic tail assembles a complex signalosome composed of adaptors and effector enzymes, that may either trigger activating signaling cascades, or instead modulate the intensity of signaling. Except for a few cytosolic adaptors that connect different components of the CD6 signalosome, very little is known about the mechanistic effects of the cytosolic effectors that bind CD6. METHODS Jurkat model T cells were transfected to express wild-type (WT) CD6, or a cytoplasmic truncation, signaling-disabled mutant, CD6Δcyt. The two resulting cell lines were directly activated by superantigen (sAg)-loaded Raji cells, used as APCs, to assess the net signaling function of CD6. The Jurkat cell lines were further adapted to express a FRET-based unimolecular HRas biosensor that reported the activity of this crucial GTPase at the immunological synapse. RESULTS We show that deletion of the cytosolic tail of CD6 enhances T-cell responses, indicating that CD6 restrains T-cell activation. One component of the CD6-associated inhibitory apparatus was found to be the GTPase activating protein of Ras (RasGAP), that we show to associate with CD6 in a phosphorylation-dependent manner. The FRET HRas biosensor that we developed was demonstrated to be functional and reporting the activation of the T cell lines. This allowed to determine that the presence of the cytosolic tail of CD6 results in the down-regulation of HRas activity at the immunological synapse, implicating this fundamental GTPase as one of the targets inhibited by CD6. CONCLUSIONS This study provides the first description of a mechanistic sequence of events underlying the CD6-mediated inhibition of T-cell activation, involving the modulation of the MAPK pathway at several steps, starting with the coupling of RasGAP to the CD6 signalosome, the repression of the activity of Ras, and culminating in the reduction of ERK1/2 phosphorylation and of the expression of the T-cell activation markers CD69 and IL-2R α chain. Video abstract.
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Affiliation(s)
- Sónia N. Henriques
- grid.5808.50000 0001 1503 7226i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal ,grid.5808.50000 0001 1503 7226IBMC - Instituto de Biologia Molecular e Celular, Porto, Portugal ,grid.5808.50000 0001 1503 7226Programa Doutoral em Biologia Molecular e Celular (MCbiology), Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Universidade do Porto, Porto, Portugal
| | - Liliana Oliveira
- grid.5808.50000 0001 1503 7226i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal ,grid.5808.50000 0001 1503 7226IBMC - Instituto de Biologia Molecular e Celular, Porto, Portugal
| | - Rita F. Santos
- grid.5808.50000 0001 1503 7226i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal ,grid.5808.50000 0001 1503 7226IBMC - Instituto de Biologia Molecular e Celular, Porto, Portugal
| | - Alexandre M. Carmo
- grid.5808.50000 0001 1503 7226i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal ,grid.5808.50000 0001 1503 7226IBMC - Instituto de Biologia Molecular e Celular, Porto, Portugal
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3
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Altable M, de la Serna JM. Protection against COVID-19 in African population: Immunology, genetics, and malaria clues for therapeutic targets. Virus Res 2021; 299:198347. [PMID: 33631219 PMCID: PMC7898966 DOI: 10.1016/j.virusres.2021.198347] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2020] [Revised: 02/14/2021] [Accepted: 02/15/2021] [Indexed: 02/06/2023]
Abstract
BACKGROUND There is a marked discrepancy between SARS-CoV-2 seroprevalence and COVID-19 cases and deaths in Africa. MAIN: SARS-CoV-2 stimulates humoral and cellular immunity systems, as well as mitogen-activated protein kinase (MAPK) and nuclear NF-kB signalling pathways, which regulate inflammatory gene expression and immune cell differentiation. The result is pro-inflammatory cytokines release, hyperinflammatory condition, and cytokine storm, which provoke severe lung alterations that can lead to multi-organ failure in COVID-19. Multiple genetic and immunologic factors may contribute to the severity of COVID-19 in African individuals when compared to the rest of the global population. In this article, the role of malaria, NF-kB and MAPK pathways, caspase-12 expression, high level of LAIR-1-containing antibodies, and differential glycophorins (GYPA/B) expression in COVID-19 are discussed. CONCLUSION Understanding pathophysiological mechanisms can help identify target points for drugs and vaccines development against COVID-19. To our knowledge, this is the first study that explores this link and proposes a biological and molecular answer to the epidemiologic discrepancy in COVID-19 in Africa.
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Affiliation(s)
- Marcos Altable
- Private Practice of Neurology, Neuroceuta. (Virgen de África Clinic), Ceuta, Spain.
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4
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Ye Y, Liang Z, Xue L. Neuromedin U: potential roles in immunity and inflammation. Immunology 2020; 162:17-29. [PMID: 32888314 DOI: 10.1111/imm.13257] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Revised: 08/17/2020] [Accepted: 08/21/2020] [Indexed: 02/05/2023] Open
Abstract
Since the discovery of neuromedin U (NmU) from porcine spinal cord in 1985, this neuropeptide has been subsequently identified in many other species with multiple physiological and pathophysiological roles detected, ranging from smooth muscle contraction, feeding, energy balance to tumorigenesis. Intriguingly, NmU is also emerging to play pro-inflammatory roles involving immune cell activation and cytokine release in a neuron-dependent or neuron-independent manner. The NmU-mediated inflammatory responses have already been observed in worm infection, sepsis, autoimmune arthritis and allergic animal models. In this review, we focus on the roles of NmU in immunity and inflammation by highlighting the interactions between NmU and immune cells, summarizing the signalling mechanism involved in their reactions and discussing its potential contributions to inflammatory diseases.
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Affiliation(s)
- Yuan Ye
- The Respiratory Medicine Unit, Oxford NIHR Biomedical Research Centre, University of Oxford, Oxford, UK.,Department of Respiratory and Critical Care Medicine, West China School of Medicine and West China Hospital, Sichuan University, Chengdu, China
| | - Zongan Liang
- Department of Respiratory and Critical Care Medicine, West China School of Medicine and West China Hospital, Sichuan University, Chengdu, China
| | - Luzheng Xue
- The Respiratory Medicine Unit, Oxford NIHR Biomedical Research Centre, University of Oxford, Oxford, UK
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5
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Jha MK, Sarode AY, Saha B. Ras isoforms selectively regulate antigen-specific immune response. Cytokine 2019; 126:154914. [PMID: 31707328 DOI: 10.1016/j.cyto.2019.154914] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Revised: 10/05/2019] [Accepted: 10/30/2019] [Indexed: 12/30/2022]
Abstract
H-/K-Ras and N-Ras isoforms were proposed to lack functional specificities due to similarity in 1-165 amino acids. As recent studies implied Ras isoform-specific developmental effects, we examined their functional specificity using Leishmania major infection, anti-hapten antibody response and carrier-specific T cell response. While N-Ras overexpression increased L. major infection in resistant C57BL/6 mice, H-Ras or K-Ras overexpression reduced the infection in susceptible BALB/c mice. These Ras isoforms differentially regulated anti-TNP antibody response in TNP-Ova-primed, but not in TNP-Ficoll- or TNP-LPS-primed, BALB/c mice. Ras isoform-specific silencing selectively modulated Ova-specific T cell response. The data indicate Ras isoform-specific regulation of antigen-specific immune response.
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Affiliation(s)
- Mukesh Kumar Jha
- National Centre for Cell Science, Ganeshkhind, Pune 411007, India
| | - Aditya Y Sarode
- National Centre for Cell Science, Ganeshkhind, Pune 411007, India
| | - Bhaskar Saha
- National Centre for Cell Science, Ganeshkhind, Pune 411007, India.
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6
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Wei X, Zhao T, Zhang Y, Ai K, Li H, Yang J. Involvement of H-Ras in the adaptive immunity of Nile tilapia by regulating lymphocyte activation. FISH & SHELLFISH IMMUNOLOGY 2019; 89:281-289. [PMID: 30953781 DOI: 10.1016/j.fsi.2019.04.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 03/24/2019] [Accepted: 04/02/2019] [Indexed: 06/09/2023]
Abstract
H-Ras is a guanosine triphosphatase (GTPase), which acts as a molecular switch and controls multiple important cellular processes including lymphocyte activation and function. However, regulatory mechanism of adaptive immune response by H-Ras remains unclear in non-mammalian animals. In the present study, we investigated the involvement of H-Ras in lymphocyte activation with a teleost model Oreochromis niloticus. H-Ras from O. niloticus (On-H-Ras) is highly conserved with those from other vertebrates. The mRNA of On-H-Ras showed a wide expression pattern in the lymphoid-tissues and with the highest level in liver. After Aeromonas hydrophila infection, transcription of On-H-Ras was significantly induced on day 8 but came back to basal level on day 16, suggesting that On-H-Ras potentially participated in primary response during the adaptive immunity. Furthermore, On-H-Ras mRNA was obviously up-regulated when leukocytes were activated by T lymphocyte mitogen PHA in vitro. Meanwhile, protein level of H-Ras was also augmented once leukocytes were stimulated with lymphocyte receptor signaling agonist PMA and ionomycin. More importantly, once Ras activity was inhibited by specific inhibitor, the up-regulation of lymphocyte activation marker CD122 was obviously impaired during lymphocyte activation process. Therefore, On-H-Ras regulated lymphocyte activation through both mRNA and protein level. Altogether, our results illustrated the involvement of H-Ras in teleost adaptive immunity via controlling lymphocyte activation, and thus provided a novel perspective to understand evolution of the lymphocyte-mediated adaptive immunity.
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Affiliation(s)
- Xiumei Wei
- State Key Laboratory of Estuarine and Coastal Research, Laboratory of Aquatic Comparative Immunology, School of Life Sciences, East China Normal University, Shanghai, 200241, China
| | - Tianyu Zhao
- State Key Laboratory of Estuarine and Coastal Research, Laboratory of Aquatic Comparative Immunology, School of Life Sciences, East China Normal University, Shanghai, 200241, China
| | - Yu Zhang
- State Key Laboratory of Estuarine and Coastal Research, Laboratory of Aquatic Comparative Immunology, School of Life Sciences, East China Normal University, Shanghai, 200241, China
| | - Kete Ai
- State Key Laboratory of Estuarine and Coastal Research, Laboratory of Aquatic Comparative Immunology, School of Life Sciences, East China Normal University, Shanghai, 200241, China
| | - Huiying Li
- State Key Laboratory of Estuarine and Coastal Research, Laboratory of Aquatic Comparative Immunology, School of Life Sciences, East China Normal University, Shanghai, 200241, China
| | - Jialong Yang
- State Key Laboratory of Estuarine and Coastal Research, Laboratory of Aquatic Comparative Immunology, School of Life Sciences, East China Normal University, Shanghai, 200241, China; Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China.
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7
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Boddicker RL, Razidlo GL, Feldman AL. Genetic alterations affecting GTPases and T-cell receptor signaling in peripheral T-cell lymphomas. Small GTPases 2017; 10:33-39. [PMID: 27898263 DOI: 10.1080/21541248.2016.1263718] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
Peripheral T-cell lymphomas (PTCLs) are rare, heterogeneous tumors with poor response to standard therapy and few targeted treatments available. The identification of mutations in the T-cell receptor (TCR) signaling pathway that either directly or indirectly affect Ras- and Rho-family GTPases is an emerging theme across PTCL subtypes. This review summarizes the role of GTPases in TCR signaling and highlights the constellation of mutations in this pathway among PTCLs. In particular, focus is given to the functional impact of the mutations and opportunities for targeted therapy. These mutations include activating mutations and gene fusions involving the guanine nucleotide exchange factor, VAV1, as well as activating and dominant negative mutations in the GTPases KRAS and RHOA, respectively. In addition to mutations directly affecting the GTPase pathway, TCR signaling mutations indirectly affecting Ras- and Rho-family GTPases involving genes such as CD28, FYN, LCK, and PLCG1 are also reviewed.
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Affiliation(s)
- Rebecca L Boddicker
- a Department of Laboratory Medicine and Pathology , Mayo Clinic , Rochester , MN , USA
| | - Gina L Razidlo
- b Center for Basic Research in Digestive Diseases, Division of Gastroenterology & Hepatology, Mayo Clinic , Rochester , MN , USA.,c Department of Biochemistry and Molecular Biology , Mayo Clinic , Rochester , MN , USA
| | - Andrew L Feldman
- a Department of Laboratory Medicine and Pathology , Mayo Clinic , Rochester , MN , USA
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8
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The azetidine derivative, KHG26792 protects against ATP-induced activation of NFAT and MAPK pathways through P2X7 receptor in microglia. Neurotoxicology 2015; 51:198-206. [PMID: 26522449 DOI: 10.1016/j.neuro.2015.10.013] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Revised: 09/21/2015] [Accepted: 10/26/2015] [Indexed: 01/01/2023]
Abstract
Azetidine derivatives are of interest for drug development because they may be useful therapeutic agents. However, their mechanisms of action remain to be completely elucidated. Here, we have investigated the effects of 3-(naphthalen-2-yl(propoxy)methyl)azetidine hydrochloride (KHG26792) on ATP-induced activation of NFAT and MAPK through P2X7 receptor in the BV-2 mouse microglial cell line. KHG26792 decreased ATP-induced TNF-α release from BV-2 microglia by suppressing, at least partly, P2X7 receptor stimulation. KHG26792 also inhibited the ATP-induced increase in IL-6, PGE2, NO, ROS, CXCL2, and CCL3. ATP induced NFAT activation through P2X7 receptor, with KHG26792 reducing the ATP-induced NFAT activation. KHG26792 inhibited an ATP-induced increase in iNOS protein and ERK phosphorylation. KHG26792 prevented an ATP-induced increase in MMP-9 activity through the P2X7 receptor as a result of degradation of TIMP-1 by cathepsin B. Our data provide mechanistic insights into the role of KHG26792 in the inhibition of TNF-α produced via P2X7 receptor-mediated activation of NFAT and MAPK pathways in ATP-treated BV-2 cells. This study highlights the potential use of KHG26792 as a therapeutic agent for the many diseases of the CNS related to activated microglia.
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9
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Purow B. Molecular Pathways: Targeting Diacylglycerol Kinase Alpha in Cancer. Clin Cancer Res 2015; 21:5008-12. [PMID: 26420856 DOI: 10.1158/1078-0432.ccr-15-0413] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Accepted: 09/10/2015] [Indexed: 02/02/2023]
Abstract
Lipid kinases have largely been neglected as targets in cancer, and an increasing number of reports suggest diacylglycerol kinase alpha (DGKα) may be one with promising therapeutic potential. DGKα is one of 10 DGK family members that convert diacylglycerol (DAG) to phosphatidic acid (PA), and both DAG and PA are critical lipid second messengers in the plasma membrane. A host of important oncogenic proteins and pathways affect cancer cells in part through DGKα, including the c-Met and VEGF receptors. Others partially mediate the effects of DGKα inhibition in cancer, such as mTOR and HIF-1α. DGKα inhibition can directly impair cancer cell viability, inhibits angiogenesis, and notably may also boost T-cell activation and enhance cancer immunotherapies. Although two structurally similar inhibitors of DGKα were established decades ago, they have seen minimal in vivo usage, and it is unlikely that either of these older DGKα inhibitors will have utility for cancer. An abandoned compound that also inhibits serotonin receptors may have more translational potential as a DGKα inhibitor, but more potent and specific DGKα inhibitors are sorely needed. Other DGK family members may also provide therapeutic targets in cancer, but require further investigation.
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Affiliation(s)
- Benjamin Purow
- Department of Neurology, University of Virginia, Charlottesville, Virginia.
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10
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Saito S, Kawamura T, Higuchi M, Kobayashi T, Yoshita-Takahashi M, Yamazaki M, Abe M, Sakimura K, Kanda Y, Kawamura H, Jiang S, Naito M, Yoshizaki T, Takahashi M, Fujii M. RASAL3, a novel hematopoietic RasGAP protein, regulates the number and functions of NKT cells. Eur J Immunol 2015; 45:1512-23. [PMID: 25652366 DOI: 10.1002/eji.201444977] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Revised: 01/12/2015] [Accepted: 01/29/2015] [Indexed: 01/30/2023]
Abstract
Ras GTPase-activating proteins negatively regulate the Ras/Erk signaling pathway, thereby playing crucial roles in the proliferation, function, and development of various types of cells. In this study, we identified a novel Ras GTPase-activating proteins protein, RASAL3, which is predominantly expressed in cells of hematopoietic lineages, including NKT, B, and T cells. We established systemic RASAL3-deficient mice, and the mice exhibited a severe decrease in NKT cells in the liver at 8 weeks of age. The treatment of RASAL3-deficient mice with α-GalCer, a specific agonist for NKT cells, induced liver damage, but the level was less severe than that in RASAL3-competent mice, and the attenuated liver damage was accompanied by a reduced production of interleukin-4 and interferon-γ from NKT cells. RASAL3-deficient NKT cells treated with α-GalCer in vitro presented augmented Erk phosphorylation, suggesting that there is dysregulated Ras signaling in the NKT cells of RASAL3-deficient mice. Taken together, these results suggest that RASAL3 plays an important role in the expansion and functions of NKT cells in the liver by negatively regulating Ras/Erk signaling, and might be a therapeutic target for NKT-associated diseases.
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Affiliation(s)
- Suguru Saito
- Division of Virology, Niigata University Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan
| | - Toshihiko Kawamura
- Division of Immunology, Niigata University Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan
| | - Masaya Higuchi
- Division of Virology, Niigata University Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan
| | - Takahiro Kobayashi
- Division of Immunology, Niigata University Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan
| | - Manami Yoshita-Takahashi
- Division of Virology, Niigata University Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan.,Center for Fostering Innovative Leadership, Niigata University, Niigata, Japan
| | - Maya Yamazaki
- Division of Neurocellular Biology, Brain Research Center, Niigata University, Niigata, Japan
| | - Manabu Abe
- Division of Neurocellular Biology, Brain Research Center, Niigata University, Niigata, Japan
| | - Kenji Sakimura
- Division of Neurocellular Biology, Brain Research Center, Niigata University, Niigata, Japan
| | - Yasuhiro Kanda
- Division of Immunology, Niigata University Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan
| | - Hiroki Kawamura
- Department of Clinical Engineering and Medical Technology, Faculty of Medical Technology, Niigata University of Health and Welfare, Niigata, Japan
| | - Shuying Jiang
- Division of Pathology, Niigata University Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan.,Niigata College of Medical Technology, Niigata, Japan
| | - Makoto Naito
- Division of Pathology, Niigata University Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan
| | - Takumi Yoshizaki
- Division of Virology, Niigata University Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan
| | - Masahiko Takahashi
- Division of Virology, Niigata University Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan
| | - Masahiro Fujii
- Division of Virology, Niigata University Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan
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Huang K, Kiefer C, Kamal A. Novel role for NFAT3 in ERK-mediated regulation of CXCR4. PLoS One 2014; 9:e115249. [PMID: 25514788 PMCID: PMC4267837 DOI: 10.1371/journal.pone.0115249] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Accepted: 11/20/2014] [Indexed: 01/09/2023] Open
Abstract
The G-protein coupled chemokine (C-X-C motif) receptor CXCR4 is linked to cancer, HIV, and WHIM (Warts, Hypogammaglobulinemia, Infections, and Myelokathexis) syndrome. While CXCR4 is reported to be overexpressed in multiple human cancer types and many hematological cancer cell lines, we have observed poor in vitro cell surface expression of CXCR4 in many solid tumor cell lines. We explore further the possible factors and pathways involved in regulating CXCR4 expression. Here, we showed that MEK-ERK signaling pathway and NFAT3 transcriptional factor plays a novel role in regulating CXCR4 expression. When cultured as 3D spheroids, HeyA8 ovarian tumor cells showed a dramatic increase in surface CXCR4 protein levels as well as mRNA transcripts. Furthermore, HeyA8 3D spheroids showed a decrease in phospho-ERK levels when compared to adherent cells. The treatment of adherent HeyA8 cells with an inhibitor of the MEK-ERK pathway, U0126, resulted in a significant increase in surface CXCR4 expression. Additional investigation using the PCR array assay comparing adherent to 3D spheroid showed a wide range of transcription factors being up-regulated, most notably a > 20 fold increase in NFAT3 transcription factor mRNA. Finally, chromatin immunoprecipitation (ChIP) analysis showed that direct binding of NFAT3 on the CXCR4 promoter corresponds to increased CXCR4 expression in HeyA8 ovarian cell line. Taken together, our results suggest that high phospho-ERK levels and NFAT3 expression plays a novel role in regulating CXCR4 expression.
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Affiliation(s)
- Keven Huang
- Department of Oncology Research, MedImmune, Gaithersburg, Maryland, United States of America
- * E-mail:
| | - Christine Kiefer
- Department of Antibody Discovery and Protein Engineering, MedImmune, Gaithersburg, Maryland, United States of America
| | - Adeela Kamal
- Department of Oncology Research, MedImmune, Gaithersburg, Maryland, United States of America
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Samstag Y, John I, Wabnitz GH. Cofilin: a redox sensitive mediator of actin dynamics during T-cell activation and migration. Immunol Rev 2013; 256:30-47. [PMID: 24117811 PMCID: PMC3884758 DOI: 10.1111/imr.12115] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Cofilin is an actin-binding protein that depolymerizes and/or severs actin filaments. This dual function of cofilin makes it one of the major regulators of actin dynamics important for T-cell activation and migration. The activity of cofilin is spatio-temporally regulated. Its main control mechanisms comprise a molecular toolbox of phospho-, phospholipid, and redox regulation. Phosphorylated cofilin is inactive and represents the dominant cofilin fraction in the cytoplasm of resting human T cells. A fraction of dephosphorylated cofilin is kept inactive at the plasma membrane by binding to phosphatidylinositol 4,5-bisphosphate. Costimulation via the T-cell receptor/CD3 complex (signal 1) together with accessory receptors (signal 2) or triggering through the chemokine SDF1α (stromal cell-derived factor 1α) induce Ras-dependent dephosphorylation of cofilin, which is important for immune synapse formation, T-cell activation, and T-cell migration. Recently, it became evident that cofilin is also highly sensitive for microenvironmental changes, particularly for alterations in the redox milieu. Cofilin is inactivated by oxidation, provoking T-cell hyporesponsiveness or necrotic-like programmed cell death. In contrast, in a reducing environment, even phosphatidylinositol 4,5-bisphosphate-bound cofilin becomes active, leading to actin dynamics in the vicinity of the plasma membrane. In addition to the well-established three signals for T-cell activation, this microenvironmental control of cofilin delivers a modulating signal for T-cell-dependent immune reactions. This fourth modulating signal highly impacts both initial T-cell activation and the effector phase of T-cell-mediated immune responses.
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Affiliation(s)
- Yvonne Samstag
- Institute for Immunology, Ruprecht-Karls-UniversityHeidelberg, Germany
| | - Isabel John
- Institute for Immunology, Ruprecht-Karls-UniversityHeidelberg, Germany
| | - Guido H Wabnitz
- Institute for Immunology, Ruprecht-Karls-UniversityHeidelberg, Germany
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13
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van Vliet SJ, Vuist IM, Lenos K, Tefsen B, Kalay H, García-Vallejo JJ, van Kooyk Y. Human T cell activation results in extracellular signal-regulated kinase (ERK)-calcineurin-dependent exposure of Tn antigen on the cell surface and binding of the macrophage galactose-type lectin (MGL). J Biol Chem 2013; 288:27519-27532. [PMID: 23918927 DOI: 10.1074/jbc.m113.471045] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The C-type lectin macrophage galactose-type lectin (MGL) exerts an immunosuppressive role reflected by its interaction with terminal GalNAc moieties, such as the Tn antigen, on CD45 of effector T cells, thereby down-regulating T cell receptor signaling, cytokine responses, and induction of T cell death. Here, we provide evidence for the pathways that control the specific expression of GalNAc moieties on human CD4(+) T cells. GalNAc epitopes were readily detectable on the cell surface after T cell activation and required de novo protein synthesis. Expression of GalNAc-containing MGL ligands was completely dependent on PKC and did not involve NF-κB. Instead, activation of the downstream ERK MAPK pathway led to decreased mRNA levels and activity of the core 1 β3GalT enzyme and its chaperone Cosmc, favoring the expression of Tn antigen. In conclusion, expression of GalNAc moieties mirrors the T cell activation status, and thus only highly stimulated T cells are prone to the suppressive action of MGL.
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Affiliation(s)
- Sandra J van Vliet
- Department of Molecular Cell Biology and Immunology, VU University Medical Center, 1081 BT Amsterdam, The Netherlands.
| | - Ilona M Vuist
- Department of Molecular Cell Biology and Immunology, VU University Medical Center, 1081 BT Amsterdam, The Netherlands
| | - Kristiaan Lenos
- Department of Molecular Cell Biology and Immunology, VU University Medical Center, 1081 BT Amsterdam, The Netherlands
| | - Boris Tefsen
- Department of Molecular Cell Biology and Immunology, VU University Medical Center, 1081 BT Amsterdam, The Netherlands
| | - Hakan Kalay
- Department of Molecular Cell Biology and Immunology, VU University Medical Center, 1081 BT Amsterdam, The Netherlands
| | - Juan J García-Vallejo
- Department of Molecular Cell Biology and Immunology, VU University Medical Center, 1081 BT Amsterdam, The Netherlands
| | - Yvette van Kooyk
- Department of Molecular Cell Biology and Immunology, VU University Medical Center, 1081 BT Amsterdam, The Netherlands
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14
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CD81 controls sustained T cell activation signaling and defines the maturation stages of cognate immunological synapses. Mol Cell Biol 2013; 33:3644-58. [PMID: 23858057 DOI: 10.1128/mcb.00302-13] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In this study, we investigated the dynamics of the molecular interactions of tetraspanin CD81 in T lymphocytes, and we show that CD81 controls the organization of the immune synapse (IS) and T cell activation. Using quantitative microscopy, including fluorescence recovery after photobleaching (FRAP), phasor fluorescence lifetime imaging microscopy-Föster resonance energy transfer (phasorFLIM-FRET), and total internal reflection fluorescence microscopy (TIRFM), we demonstrate that CD81 interacts with ICAM-1 and CD3 during conjugation between T cells and antigen-presenting cells (APCs). CD81 and ICAM-1 exhibit distinct mobilities in central and peripheral areas of early and late T cell-APC contacts. Moreover, CD81-ICAM-1 and CD81-CD3 dynamic interactions increase over the time course of IS formation, as these molecules redistribute throughout the contact area. Therefore, CD81 associations unexpectedly define novel sequential steps of IS maturation. Our results indicate that CD81 controls the temporal progression of the IS and the permanence of CD3 in the membrane contact area, contributing to sustained T cell receptor (TCR)-CD3-mediated signaling. Accordingly, we find that CD81 is required for proper T cell activation, regulating CD3ζ, ZAP-70, LAT, and extracellular signal-regulated kinase (ERK) phosphorylation; CD69 surface expression; and interleukin-2 (IL-2) secretion. Our data demonstrate the important role of CD81 in the molecular organization and dynamics of the IS architecture that sets the signaling threshold in T cell activation.
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Osei-Sarfo K, de Castro IP, Pellicer A. p15(INK4b) plays a crucial role in murine lymphoid development and tumorigenesis. Carcinogenesis 2012; 33:708-13. [PMID: 22227036 DOI: 10.1093/carcin/bgs003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
To investigate if the cooperation between the Rgr oncogene and the inactivation of INK4b (a CDK inhibitor), as described previously in a sarcoma model, would be operational in a lymphoid system in vivo, we generated a transgenic/knockout murine model. Transgenic mice expressing the Rgr oncogene under a CD4 promoter were crossed into a p15(INK4b)-deficient background. Unexpectedly, mice with a complete ablation of both p15(INK4b) alleles had a lower tumor incidence and higher survival rate when compared with CD4-Rgr progeny with homozygous or heterozygous expression of p15(INK4b). Also, a similar survival pattern was observed in a parallel model in which transgenic mice expressing a constitutively activated N-Ras mutant were crossed into a p15(INK4b)-deficient background. To analyze this paradoxical event, we investigated the hypothesis that the absence of both p15(INK4b) alleles in the presence of the Rgr oncogene could be deleterious for proper thymocyte development. When analyzed, thymocyte development was blocked at the double negative (DN) 3 and DN4 stages in mice missing one or both alleles of p15(INK4b), respectively. We found reduction in overall apoptotic levels in the thymocytes of mice expressing Rgr, compared with their wild-type mice, supporting thymocyte escape from programmed cell death and subsequently facilitating the onset of thymic lymphomas but less for those missing both p15 alleles. These findings provide evidence of the complex interplay between oncogenes and tumor suppressor genes in tumor development and indicate that in the lymphoid tissue the inactivation of both p15 alleles is unlikely to be the first event in tumor development.
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Affiliation(s)
- Kwame Osei-Sarfo
- Department of Pathology, New York University Langone Medical Center, New York, NY 10016, USA
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16
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Mor A, Aizman E, George J, Kloog Y. Ras inhibition induces insulin sensitivity and glucose uptake. PLoS One 2011; 6:e21712. [PMID: 21738773 PMCID: PMC3126849 DOI: 10.1371/journal.pone.0021712] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2011] [Accepted: 06/06/2011] [Indexed: 02/06/2023] Open
Abstract
Background Reduced glucose uptake due to insulin resistance is a pivotal mechanism in the pathogenesis of type 2 diabetes. It is also associated with increased inflammation. Ras inhibition downregulates inflammation in various experimental models. The aim of this study was to examine the effect of Ras inhibition on insulin sensitivity and glucose uptake, as well as its influence on type 2 diabetes development. Methods and Findings The effect of Ras inhibition on glucose uptake was examined both in vitro and in vivo. Ras was inhibited in cells transfected with a dominant-negative form of Ras or by 5-fluoro-farnesylthiosalicylic acid (F-FTS), a small-molecule Ras inhibitor. The involvement of IκB and NF-κB in Ras-inhibited glucose uptake was investigated by immunoblotting. High fat (HF)-induced diabetic mice were treated with F-FTS to test the effect of Ras inhibition on induction of hyperglycemia. Each of the Ras-inhibitory modes resulted in increased glucose uptake, whether in insulin-resistant C2C12 myotubes in vitro or in HF-induced diabetic mice in vivo. Ras inhibition also caused increased IκB expression accompanied by decreased expression of NF-κB . In fat-induced diabetic mice treated daily with F-FTS, both the incidence of hyperglycemia and the levels of serum insulin were significantly decreased. Conclusions Inhibition of Ras apparently induces a state of heightened insulin sensitization both in vitro and in vivo. Ras inhibition should therefore be considered as an approach worth testing for the treatment of type 2 diabetes.
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Affiliation(s)
- Adi Mor
- Department of Neurobiology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel-Aviv, Israel
| | - Elizabeta Aizman
- Department of Neurobiology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel-Aviv, Israel
| | - Jacob George
- Department of Cardiology, Kaplan Medical Center, Rehovot, affiliated to the Hebrew University—Hadassah Medical School, Jerusalem, Israel
| | - Yoel Kloog
- Department of Neurobiology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel-Aviv, Israel
- * E-mail:
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17
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Shiratori M, Tozaki-Saitoh H, Yoshitake M, Tsuda M, Inoue K. P2X7 receptor activation induces CXCL2 production in microglia through NFAT and PKC/MAPK pathways. J Neurochem 2010; 114:810-9. [PMID: 20477948 DOI: 10.1111/j.1471-4159.2010.06809.x] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Microglia plays an important role in many neurodegenerative conditions. ATP leaked or released by damaged cells triggers microglial activation through P2 receptors, and stimulates the release of oxygen radicals, proinflammatory cytokines and chemokines from activated microglia. However, little is known about mechanisms underlying ATP-induced chemokine release from microglia. In this study, we found that a high concentration of ATP induces the mRNA expression and release of CXCL2 from microglia. A similar effect was observed following treatment of microglia with a P2X7 receptor (P2X7R) agonist, 2'-and 3'-O-(4-benzoylbenzoyl) ATP, and this was inhibited by pre-treatment with a P2X7R antagonist, Brilliant Blue G. ATP induced both activation of nuclear factor of activated T cells (NFAT) and MAPKs (p38, ERK, and JNK) through P2X7R. ATP-induced mRNA expression of CXCL2 was inhibited by INCA-6 (an NFAT inhibitor), SB203580 (a p38 inhibitor), U0126 (a MEK-ERK inhibitor) and JNK inhibitor II (a JNK inhibitor). However, MAPK inhibitors did not inhibit activation of NFAT. In addition, protein kinase C inhibitors suppressed ATP-induced ERK and JNK activation, and also inhibited ATP-induced CXCL2 expression in microglia. These results suggest that ATP increased CXCL2 production via both NFAT and protein kinase C/MAPK signaling pathways through P2X7 receptor stimulation in microglia.
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Affiliation(s)
- Miho Shiratori
- Department of Molecular and System Pharmacology, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
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18
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Andrade WA, Silva AM, Alves VS, Salgado APC, Melo MB, Andrade HM, Dall'Orto FV, Garcia SA, Silveira TN, Gazzinelli RT. Early endosome localization and activity of RasGEF1b, a toll-like receptor-inducible Ras guanine-nucleotide exchange factor. Genes Immun 2010; 11:447-57. [PMID: 20090772 DOI: 10.1038/gene.2009.107] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Guanine-nucleotide exchange factors (GEFs) stimulate the intrinsic GDP/GTP exchange activity of Ras and promote the formation of active Ras-GTP, which in turn controls diverse signalling networks important for the regulation of cell proliferation, survival, differentiation, vesicular trafficking, and gene expression. RasGEF1b is a GEF, whose expression is induced in macrophages on stimulation with toll-like receptor (TLR) agonists. Here, we showed that in vitro RasGEF1b expression by macrophages is mostly induced by TLR3 (poly I:C) and TLR4 (lipopolysaccharyde) through the MyD88-independent pathway. In vivo infection with the protozoan parasites Trypanosoma cruzi and Plasmodium chabaudi induced RasGEF1b in an MyD88-, TRIF-, and IFN-gamma-dependent manner. Ectopically expressed RasGEF1b was found, mostly, in the heavy membrane fraction of HEK 293T, and by confocal microscopy, it was found to be located at early endosomes. Computational modelling of the RasGEF1b-Ras interaction revealed that RasGEF1b interacts with the binding domain site of Ras, a critical region for interacting with GEFs involved in the activation of Ras-Raf-MEK-ERK pathway. More important, RasGEF1b was found to be closely associated with Ras in live cells and to trigger Ras activity. Altogether, these results indicate that on TLR activation, RasGEF1b may trigger Ras-like proteins and regulate specific biological activities described for this subtype of GTPases.
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Affiliation(s)
- W A Andrade
- Department of Biochemistry and Immunology, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
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19
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Bécart S, Altman A. SWAP-70-like adapter of T cells: a novel Lck-regulated guanine nucleotide exchange factor coordinating actin cytoskeleton reorganization and Ca2+ signaling in T cells. Immunol Rev 2009; 232:319-33. [PMID: 19909373 PMCID: PMC2801603 DOI: 10.1111/j.1600-065x.2009.00839.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
SWAP-70-like adapter of T cells (SLAT) is a recently identified guanine nucleotide exchange factor (GEF) for Cdc42 and Rac1, which is highly expressed in both thymocytes and peripheral T cells. Here, we present and discuss findings resulting from biochemical and genetic analyses aimed at unveiling the role of SLAT in CD4+ T-cell development, activation, and T-helper (Th) cell differentiation. Slat(-/-) mice display a developmental defect at one of the earliest stages of thymocyte differentiation, the double negative 1 (DN1) stage, leading to decreased peripheral T-cell numbers. Slat(-/-) peripheral CD4+ T cells demonstrate impaired T-cell receptor/CD28-induced proliferation and IL-2 production. Moreover, SLAT positively regulates the development of Th1 and Th2 inflammatory responses by controlling Ca2+/NFAT signaling. SLAT is also a positive regulator of the recently emerging Th subset, i.e., Th17 cells, as evidenced by its critical role in Th17 cell-mediated central nervous system inflammation. Furthermore, TCR engagement induces SLAT translocation to the immunological synapse, a process mediated by its Lck-dependent phosphorylation, which thereafter facilitates the triggering of SLAT GEF activity towards Cdc42 and Rac1, leading to NFAT activation and Th1/Th2 differentiation. Future work will aim to dissect the interacting partners of SLAT and may thus shed light on the poorly understood events that coordinate and link actin cytoskeleton reorganization to Ca2+ signaling and gene transcription in T cells.
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Affiliation(s)
- Stéphane Bécart
- Division of Cell Biology, La Jolla Institute for Allergy and Immunology, La Jolla, CA, USA
| | - Amnon Altman
- Division of Cell Biology, La Jolla Institute for Allergy and Immunology, La Jolla, CA, USA
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20
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Praveen K, Zheng Y, Rivas F, Gajewski TF. Protein kinase Ctheta focusing at the cSMAC is a consequence rather than cause of TCR signaling and is dependent on the MEK/ERK pathway. THE JOURNAL OF IMMUNOLOGY 2009; 182:6022-30. [PMID: 19414753 DOI: 10.4049/jimmunol.0800897] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Correlation between protein kinase Ctheta focusing within the central supramolecular activation cluster (cSMAC) of the immunological synapse and optimal TCR/costimulatory receptor ligation was interpreted to imply that PKCtheta focusing is required for productive signaling. However, this notion has been called into question and competing data suggest that the cSMAC contributes to receptor down-modulation. The observation that PKCtheta focusing at the cSMAC is promoted by CD28 coligation, and also that it occurs late after proximal tyrosine phosphorylation events have been initiated, has led us to investigate an alternative possibility that PKCtheta focusing might be a consequence rather than a cause of productive integrated signaling. Indeed, we found that inhibition of the downstream signaling molecules MEK and PI3K (but not of calcineurin, NF-kappaB, JNK, or p38 MAPK) significantly prevented the focusing of PKCtheta at the cSMAC. It recently has been suggested that the cSMAC may be associated with TCR degradation and signal termination. Using MEK inhibition as a tool, we observed that absence of detectable PKCtheta focusing had no significant effect on TCR down-modulation or duration of CD3zeta phosphorylation. Our results suggest that PKCtheta focusing at the cSMAC occurs as a consequence of productive integrated downstream signaling at least at the level of MEK. If PKCtheta focusing accurately reflects the cSMAC as a whole, then our data also argue against the cSMAC as being required for proximal TCR signal termination.
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Affiliation(s)
- Kesavannair Praveen
- Department of Pathology, Committees on Immunology and Cancer Biology, Pritzker School of Medicine, University of Chicago, Chicago, IL 60637, USA
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21
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Siliceo M, Mérida I. T cell receptor-dependent tyrosine phosphorylation of beta2-chimaerin modulates its Rac-GAP function in T cells. J Biol Chem 2009; 284:11354-63. [PMID: 19201754 DOI: 10.1074/jbc.m806098200] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The actin cytoskeleton has an important role in the organization and function of the immune synapse during antigen recognition. Dynamic rearrangement of the actin cytoskeleton in response to T cell receptor (TCR) triggering requires the coordinated activation of Rho family GTPases that cycle between active and inactive conformations. This is controlled by GTPase-activating proteins (GAP), which regulate inactivation of Rho GTPases, and guanine exchange factors, which mediate their activation. Whereas much attention has centered on guanine exchange factors for Rho GTPases in T cell activation, the identity and functional roles of the GAP in this process are largely unknown. We previously reported beta2-chimaerin as a diacylglycerol-regulated Rac-GAP that is expressed in T cells. We now demonstrate Lck-dependent phosphorylation of beta2-chimaerin in response to TCR triggering. We identify Tyr-153 as the Lck-dependent phosphorylation residue and show that its phosphorylation negatively regulates membrane stabilization of beta2-chimaerin, decreasing its GAP activity to Rac. This study establishes the existence of TCR-dependent regulation of beta2-chimaerin and identifies a novel mechanism for its inactivation.
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Affiliation(s)
- María Siliceo
- Department of Immunology and Oncology, Centro Nacional de Biotecnología/Consejo Superior de Investigaciones Científicas, E-28049 Madrid, Spain
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22
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Mor A, Keren G, Kloog Y, George J. N-Ras or K-Ras inhibition increases the number and enhances the function of Foxp3 regulatory T cells. Eur J Immunol 2008; 38:1493-502. [PMID: 18461565 DOI: 10.1002/eji.200838292] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Naturally occurring regulatory T cells (Treg) driven by their transcriptional controller Foxp3 are compromised in immune-mediated disorders and confer protection when adoptively transferred. We examined the Ras-inhibitory effect on functional determinants of Treg in vivo and in vitro. Ras was inhibited in Jurkat T cells by transfection with a dominant-negative form of Ras, or by shRNA for N-Ras, K-Ras, and H-Ras, or by farnesylthiosalycylic acid, a small-molecule inhibitor. Except for H-Ras transduction with shRNA, each inhibitory mode increased expression of Foxp3 and nuclear factor of activated T cell proteins, and surface expression of CD25. Ras inhibition in PBMC and spleen-derived lymphocytes reproduced these findings. The heightened Foxp3 expression reflected both increased basal cellular protein and peripheral conversion of non-Treg to Treg. Ras inhibition enhanced Treg-induced suppression; thus, when adoptively transferred to mice, Ras-inhibited Treg reduced the incidence of diabetes. Inhibition of Foxp3 by respective siRNA reversed the enhancement. Thus, inhibition of the N- or K-Ras isoform triggers an anti-inflammatory effect by up-regulating, via Foxp3 elevation, the numbers and functional suppressive properties of Treg.
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Affiliation(s)
- Adi Mor
- Cardiovascular Research Center, Department of Cardiology, Tel Aviv Sourasky Medical Center, Affiliated with the Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
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23
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Potential role of phospholipase D2 in increasing interleukin-2 production by T-lymphocytes through activation of mitogen-activated protein kinases ERK1/ERK2. Biochim Biophys Acta Mol Cell Biol Lipids 2008; 1781:263-9. [DOI: 10.1016/j.bbalip.2008.03.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2007] [Revised: 03/05/2008] [Accepted: 03/17/2008] [Indexed: 11/23/2022]
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24
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Ruiz S, Castro-Castro A, Bustelo XR. CD147 inhibits the nuclear factor of activated T-cells by impairing Vav1 and Rac1 downstream signaling. J Biol Chem 2007; 283:5554-66. [PMID: 18160397 DOI: 10.1074/jbc.m708566200] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
CD147 is a transmembrane protein that plays crucial roles in the development and function of the reproductive, visual, and nervous systems. CD147 also exerts positive and negative actions in T-cells by still obscure mechanisms. In this study, we have analyzed the expression, localization, and function of CD147 during T-cell receptor signaling responses. We show here that CD147 is an integral component of the T-cell immune synapse and that its overexpression leads to the inhibition of NF-AT (nuclear factor of activated T-cells) activity induced by Vav1, a Rac1 exchange factor. This inhibitory activity is mediated by the CD147 intracellular tail and is totally independent of its extracellular or transmembrane regions. The molecular dissection of the influence of CD147 on the Vav1 pathway indicates that its inhibitory action takes place downstream of Vav1 and Rac1 but upstream of the serine/threonine kinases JNK and Pak1. The interference of CD147 with these pathways is highly specific because the overexpression of CD147 does not affect the activity of other GDP/GTP exchange factors or the stimulation of the ERK cascade. Finally, we show that the CD147 knockdown in Jurkat cells promotes higher levels of NF-AT stimulation and Pak1 phosphorylation upon T-cell receptor cross-linking. Instead, the lack of CD147 does not affect other signaling cascades that participate in the same cellular response. Taken together, these results indicate that CD147, via the selective inhibition of specific downstream elements of the Vav1/Rac1 route, contributes to the negative regulation of T-cell responses.
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Affiliation(s)
- Sergio Ruiz
- Centro de Investigación del Cáncer and Instituto de Biología Molecular y Celular del Cáncer, Consejo Superior de Investigaciones Científicas-University of Salamanca, Campus Unamuno, E-37007 Salamanca, Spain
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25
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Abstract
The Ras superfamily consists of over 50 low-molecular-weight proteins that cycle between an inactive guanosine diphosphate-bound state and an active guanosine triphosphate (GTP)-bound state. They are involved in a variety of signal transduction pathways that regulate cell growth, intracellular trafficking, cell migration, and apoptosis. Several methods have been devised to measure the activation state of Ras proteins, defined as the percent of Ras molecules in the active GTP-bound state. We have previously developed a quantitative biochemical method that can be applied to animal and human tissues and have used it to measure the activation state of Ras, Rap1, Rheb, and Rho proteins in cultured cells and in animal and human tumors. Ras, Rac, and Rho all play roles in regulating the functions of T and B lymphocytes and dendritic cells, and these proteins are clearly important in maintaining normal immune system function.
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Affiliation(s)
- Juergen S Scheele
- Co-ordinating Center for Clinical Trials, Martin Luther University, Halle, Germany
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26
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Turner SD, Yeung D, Hadfield K, Cook SJ, Alexander DR. The NPM-ALK tyrosine kinase mimics TCR signalling pathways, inducing NFAT and AP-1 by RAS-dependent mechanisms. Cell Signal 2007; 19:740-7. [PMID: 17110082 DOI: 10.1016/j.cellsig.2006.09.007] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2006] [Accepted: 09/16/2006] [Indexed: 01/19/2023]
Abstract
Nucleophosmin-anaplastic lymphoma kinase (NPM-ALK) expression is associated with the lymphoid malignancy anaplastic large cell lymphoma (ALCL) and results from a t(2;5) chromosomal translocation. We show that NPM-ALK induces Ras activation and phosphorylation of the ERK MAP Kinase consistent with activation of the Ras-MAP Kinase pathway. Furthermore, we demonstrate that activation of Ras is necessary for inducing transcription via NFAT/AP-1 composite transcriptional binding sites. This activity is dependent on NPM-ALK forming complexes with proteins that bind to autophosphorylated tyrosine residues at positions 156, 567 and 664, associated with binding to IRS-1, Shc and PLCgamma, respectively. Specifically, NPM-ALK activates transcription from the TRE promoter element, an AP-1 binding region, an activity dependent on both Ras and Shc activity. Our results show that NPM-ALK mimics activated T-cell receptor signalling by inducing pathways associated with the activation of NFAT/AP-1 transcription factors that bind to promoter elements found in a broad array of cytokine genes.
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Affiliation(s)
- Suzanne D Turner
- Division of Molecular Histopathology, Department of Pathology, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK.
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27
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Deckert M, Rottapel R. The adapter 3BP2: how it plugs into leukocyte signaling. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2007; 584:107-14. [PMID: 16802602 DOI: 10.1007/0-387-34132-3_8] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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28
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Vogelsgesang M, Pautsch A, Aktories K. C3 exoenzymes, novel insights into structure and action of Rho-ADP-ribosylating toxins. Naunyn Schmiedebergs Arch Pharmacol 2006; 374:347-60. [PMID: 17146673 DOI: 10.1007/s00210-006-0113-y] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2006] [Accepted: 10/18/2006] [Indexed: 12/19/2022]
Abstract
The family of C3-like exoenzymes comprises seven bacterial ADP-ribosyltransferases of different origin. The common hallmark of these exoenzymes is the selective N-ADP-ribosylation of the low molecular mass GTP-binding proteins RhoA, B, and C and inhibition of signal pathways controlled by Rho GTPases. Therefore, C3-like exoenzymes were applied as pharmacological tools for analyses of cellular functions of Rho protein in numerous studies. Recent structural and functional analyses of C3-like exoenzymes provide detailed information on the molecular mechanisms and functional consequences of ADP-ribosylation catalyzed by these toxins. More recently additional non-enzymatic actions of C3-like ADP-ribosyltransferases have been identified showing that C3 transferases from Clostridium botulinum and Clostridium limosum form a GDI-like complex with the Ras-like low molecular mass GTPase Ral without ADP-ribosylation. These results add novel information on the molecular mode of action(s) of C3-like exoenzymes and are discussed in this review.
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Affiliation(s)
- Martin Vogelsgesang
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Albert-Ludwigs-University Freiburg, Otto-Krayer-Haus, Albertstrasse 25, Freiburg, Germany
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29
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Nandiwada SL, Li W, Zhang R, Mueller DL. p300/Cyclic AMP-responsive element binding-binding protein mediates transcriptional coactivation by the CD28 T cell costimulatory receptor. THE JOURNAL OF IMMUNOLOGY 2006; 177:401-13. [PMID: 16785536 DOI: 10.4049/jimmunol.177.1.401] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
During Ag stimulation of T cells, the recognition of B7 molecules by the CD28 costimulatory receptor increases the level of c-Fos, a component of the AP-1 transactivator known to bind the 5' Il2 gene enhancer. In this study, we show that the costimulation of Fos transcription by CD28 is associated with increased binding of p300/CREB-binding protein (CBP) molecules at the Fos promoter, and is blocked by an adenoviral E1A molecular antagonist of p300/CBP. Furthermore, transcriptional activation by a C-terminal domain of CBP is strengthened when CD28 molecules are actively signaling. This increased amount and activity of p300/CBP molecules at the Fos gene correlated with higher histone H4 acetylation and RNA polymerase II association with the promoter. These data suggest a global mechanism whereby CD28 signaling influences the rate and intensity of new gene expression during Ag recognition via direct control over the coactivator function of p300/CBP.
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Affiliation(s)
- Sarada L Nandiwada
- Rheumatic and Autoimmune Diseases Division, and Center for Immunology, University of Minnesota Medical School, 312 Church Street SE, Minneapolis, MN 55455, USA
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Ishiguro K, Avruch J, Landry A, Qin S, Ando T, Goto H, Xavier R. Nore1B regulates TCR signaling via Ras and Carma1. Cell Signal 2006; 18:1647-54. [PMID: 16520020 PMCID: PMC3204664 DOI: 10.1016/j.cellsig.2006.01.015] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2005] [Accepted: 01/11/2006] [Indexed: 11/20/2022]
Abstract
Nore1A was originally identified as a potential Ras effector, and Nore1B is an alternatively spliced isoform. Both share a Ras/Rap association domain (RA domain) but only Nore1A contains sequence motifs that predict SH3 domain binding and diacylglycerol/phorbol ester binding in the amino-terminal region. Here we report that Carma1 binds to Nore1A and Nore1B through the RA domain and that Carma1 interacts with active Ras in the presence of Nore1B. RNA interference against Nore1B attenuates NF-kappaB activation induced by T cell receptor (TCR) ligation, but not NF-kappaB activation induced by TNFalpha or lipoteichoic acid. In addition, Nore1B is also required for KiRas GV12-mediated ERK1 activation and Elk1 reporter activity in T cells. We also provide evidence that knockdown of Nore1B also impairs polarized redistribution of Ras at the B cell-T cell immune interface. Together, these findings suggest that endogenous Nore1B recruits active Ras to the APC-T cell interface and mediates the interaction between Ras and Carma1.
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Affiliation(s)
- Kazuhiro Ishiguro
- Department of Medicine, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114, USA
- Therapeutic Medicine, Nagoya University School of Medicine, Showa-ku, Nagoya 466-8550, Japan
| | - Joe Avruch
- Department of Medicine, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114, USA
- Department of Molecular Biology, Massachusetts General Hospital, 185 Cambridge Street, Boston, MA 02114, USA
| | - Aimee Landry
- Center for Computational and Integrative Biology, Massachusetts General Hospital, 185 Cambridge Street, Boston, MA 02114, USA
| | - Shan Qin
- Center for Computational and Integrative Biology, Massachusetts General Hospital, 185 Cambridge Street, Boston, MA 02114, USA
| | - Takafumi Ando
- Therapeutic Medicine, Nagoya University School of Medicine, Showa-ku, Nagoya 466-8550, Japan
| | - Hidemi Goto
- Therapeutic Medicine, Nagoya University School of Medicine, Showa-ku, Nagoya 466-8550, Japan
| | - Ramnik Xavier
- Department of Medicine, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114, USA
- Center for Computational and Integrative Biology, Massachusetts General Hospital, 185 Cambridge Street, Boston, MA 02114, USA
- Corresponding author. Center for Computational and Integrative Biology, Massachusetts General Hospital, 185 Cambridge Street, Boston, MA 02114, USA. Tel.: +1 617 643 3331; fax: +1 617 643 3328. (R. Xavier)
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Kogkopoulou O, Tzakos E, Mavrothalassitis G, Baldari CT, Paliogianni F, Young HA, Thyphronitis G. Conditional up-regulation of IL-2 production by p38 MAPK inactivation is mediated by increased Erk1/2 activity. J Leukoc Biol 2006; 79:1052-60. [PMID: 16478922 DOI: 10.1189/jlb.0705418] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
The p38 mitogen-activated protein kinase regulates many cellular processes in almost all eukaryotic cell types. In T cells, p38 was shown to regulate thymic development and cytokine production. Here, the role of p38 on interleukin-2 (IL-2) production by human peripheral blood CD4+ T cells was examined. When T cells were stimulated under weak stimulation conditions, pharmaceutical and molecular p38 inhibitors induced a dramatic increase of IL-2 production. In contrast, IL-2 levels were not affected significantly when strong stimulation was provided to T cells. The increase in IL-2 production, following p38 inhibition, was associated with a strong up-regulation of extracellular signal-regulated kinase (Erk)1/2 activity. Furthermore the Erk inhibitor U0126 was able to counteract the effect of p38 inhibition on IL-2 production, supporting the conclusion that p38 mediates its effect through Erk. These results suggest that the p38 kinase, through its ability to control Erk activation levels, acts as a gatekeeper, which prevents inappropriate IL-2 production. Also, the finding that p38 acts in a strength-of-stimulation-dependent way provides an explanation for previously reported, contradictory results regarding the role of this kinase in IL-2 expression.
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Affiliation(s)
- Olga Kogkopoulou
- Department of Pathophysiology, School of Medicine, University of Athens, Greece
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Abstract
Rho proteins are master regulators of a large array of cellular functions, including control of cell morphology, cell migration and polarity, transcriptional activation, and cell cycle progression. They are the eukaryotic targets of various bacterial protein toxins and effectors, which activate or inactivate the GTPases. Here Rho-inactivating toxins and effectors are reviewed, including the families of large clostridial cytotoxins and C3-like transferases, which inactivate Rho GTPases by glucosylation and ADP-ribosylation, respectively.
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Affiliation(s)
- K Aktories
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Albertstrasse 25, 79104 Freiburg, Germany.
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Sanna B, Bueno OF, Dai YS, Wilkins BJ, Molkentin JD. Direct and indirect interactions between calcineurin-NFAT and MEK1-extracellular signal-regulated kinase 1/2 signaling pathways regulate cardiac gene expression and cellular growth. Mol Cell Biol 2005; 25:865-78. [PMID: 15657416 PMCID: PMC544001 DOI: 10.1128/mcb.25.3.865-878.2005] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
MEK1, a member of the mitogen-activated protein kinase (MAPK) cascade that directly activates extracellular signal-regulated kinase (ERK), induces cardiac hypertrophy in transgenic mice. Calcineurin is a calcium-regulated protein phosphatase that also functions as a positive regulator of cardiac hypertrophic growth through a direct mechanism involving activation of nuclear factor of activated T-cell (NFAT) transcription factors. Here we determined that calcineurin-NFAT and MEK1-ERK1/2 signaling pathways are interdependent in cardiomyocytes, where they directly coregulate the hypertrophic growth response. For example, genetic deletion of the calcineurin Abeta gene reduced the hypertrophic response elicited by an activated MEK1 transgene in the heart, while inhibition of calcineurin or NFAT in cultured neonatal cardiomyocytes also blunted the hypertrophic response driven by activated MEK1. Conversely, targeted inhibition of MEK1-ERK1/2 signaling in cultured cardiomyocytes attenuated the hypertrophic growth response directed by activated calcineurin. However, targeted inhibition of MEK1-ERK1/2 signaling did not directly affect calcineurin-NFAT activation, nor was MEK1-ERK1/2 activation altered by targeted inhibition of calcineurin-NFAT. Mechanistically, we show that MEK1-ERK1/2 signaling augments NFAT transcriptional activity independent of calcineurin, independent of changes in NFAT nuclear localization, and independent of alterations in NFAT transactivation potential. In contrast, MEK1-ERK1/2 signaling enhances NFAT-dependent gene expression through an indirect mechanism involving induction of cardiac AP-1 activity, which functions as a necessary NFAT-interacting partner. As a second mechanism, MEK1-ERK1/2 and calcineurin-NFAT proteins form a complex in cardiac myocytes, resulting in direct phosphorylation of NFATc3 within its C terminus. MEK1-ERK1/2-mediated phosphorylation of NFATc3 directly augmented its DNA binding activity, while inhibition of MEK1-ERK1/2 signaling reduced NFATc3 DNA binding activity. Collectively, these results indicate that calcineurin-NFAT and MEK1-ERK1/2 pathways constitute a codependent signaling module in cardiomyocytes that coordinately regulates the growth response through two distinct mechanisms.
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Affiliation(s)
- Bastiano Sanna
- Division of Molecular Cardiovascular Biology, Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave., MLC7020, Cincinnati, OH 45229-3039, USA
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Foucault I, Le Bras S, Charvet C, Moon C, Altman A, Deckert M. The adaptor protein 3BP2 associates with VAV guanine nucleotide exchange factors to regulate NFAT activation by the B-cell antigen receptor. Blood 2004; 105:1106-13. [PMID: 15345594 DOI: 10.1182/blood-2003-08-2965] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Engagement of the B-cell antigen receptor (BCR) activates kinases of the Src and Syk families and signaling complexes assembled by adaptor proteins, which dictate B-cell fate and function. The adaptor 3BP2/SH3BP2, an Abl Src homology domain 3 (SH3)-binding and Syk-kinases interacting protein, exhibits positive regulatory roles in T, natural killer (NK), and basophilic cells. However, its involvement in BCR signaling is completely unknown. Here we show that 3BP2 is tyrosine phosphorylated following BCR aggregation on B lymphoma cells, and that 3BP2 is a substrate for Syk and Fyn, but not Btk. To further explore the function of 3BP2 in B cells, we screened a yeast 2-hybrid B-lymphocyte library and found 3BP2 as a binding partner of Vav proteins. The interaction between 3BP2 and Vav proteins involved both constitutive and inducible mechanisms. 3BP2 also interacted with other components of the BCR signaling pathway, including Syk and phospholipase C gamma (PLC-gamma). Furthermore, overexpression and RNAi blocking experiments showed that 3BP2 regulated BCR-mediated activation of nuclear factor of activated T cells (NFATs). Finally, evidence was provided that 3BP2 functionally cooperates with Vav proteins and Rho GTPases to activate NFATs. Our results show that 3BP2 may regulate BCR-mediated gene activation through Vav proteins.
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Affiliation(s)
- Isabelle Foucault
- Institut National de la Santé et de la Recherche Médicale Unité 576, Nice, France
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Tsukamoto H, Irie A, Nishimura Y. B-Raf contributes to sustained extracellular signal-regulated kinase activation associated with interleukin-2 production stimulated through the T cell receptor. J Biol Chem 2004; 279:48457-65. [PMID: 15339934 DOI: 10.1074/jbc.m403087200] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A T cell receptor (TCR) recognizes and responds to an antigenic peptide in the context of major histocompatibility complex-encoded molecules. This provokes T cells to produce interleukin-2 (IL-2) through extracellular signal-regulated kinase (ERK) activation. We investigated the roles of B-Raf in TCR-mediated IL-2 production coupled with ERK activation in the Jurkat human T cell line. We found that TCR cross-linking could induce up-regulation of both B-Raf and Raf-1 activities, but Raf-1 activity was decreased rapidly. On the other hand, TCR-stimulated kinase activity of B-Raf was sustained. Expression of a dominant-negative mutant of B-Raf abrogated sustained but not transient TCR-mediated MEK/ERK activation. The inhibition of sustained ERK activation by either expression of a dominant-negative B-Raf or treatment with a MEK inhibitor resulted in a decrease of the TCR-stimulated nuclear factor of activated T cells (NFAT) activity and IL-2 production. Collectively, our data provide the first direct evidence that B-Raf is a positive regulator of TCR-mediated sustained ERK activation, which is required for NFAT activation and the full production of IL-2.
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Affiliation(s)
- Hirotake Tsukamoto
- Department of Immunogenetics, Graduate School of Medical Sciences, Kumamoto University, Honjo 1-1-1, Kumamoto 860-8556, Japan
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Laurent MN, Ramirez DM, Alberola-Ila J. Kinase Suppressor of Ras Couples Ras to the ERK Cascade during T Cell Development. THE JOURNAL OF IMMUNOLOGY 2004; 173:986-92. [PMID: 15240686 DOI: 10.4049/jimmunol.173.2.986] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Ras signaling is critical for many developmental processes and requires the precise coordination of interactions among multiple downstream components. One mechanism by which this regulation is achieved is through the use of scaffolding molecules that coordinate the assembly of multimolecular complexes. Recently, the scaffolding molecule kinase suppressor of Ras (KSR) was isolated in genetic screens as a modifier of Ras signaling, although its contribution to regulating Ras-mediated activation of its different downstream effectors is not well understood. We have analyzed the role of KSR in linking Ras to the ERK cascade during positive selection. Our results demonstrate that KSR overexpression interferes with T cell development, an effect that requires the direct interaction between KSR and MEK. This functional effect correlates with the ability of KSR to uncouple Ras from the ERK cascade when overexpressed.
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Affiliation(s)
- Micheline N Laurent
- Division of Biology, California Institute of Technology, Pasadena, CA 91125, USA
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37
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Abstract
Guanine nucleotide binding proteins rapidly cycle between a guanosine diphosphate (GDP)-bound and guanosine triphosphate (GTP)-bound state, and they operate as binary switches that control cell activation in response to environmental cues. GTPases adopt different conformations when binding GTP vs. GDP. The GTP-bound state is generally considered to be the active conformation that allows GTPases to interact with downstream effectors and thereby initiate downstream signaling pathways, which regulate many important biological processes. Many members of the Ras family of GTPases, notably Ras and Rap1A, and the Rho family GTPases, Cdc42Hs, Rac1, Rac2 and RhoA, are important components of signal transduction pathways used by antigen receptors, costimulatory, cytokine and chemokine receptors to regulate the immune response. This review discusses current knowledge and ideas about the regulation and function of these GTPases in lymphocytes.
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Affiliation(s)
- Doreen Ann Cantrell
- Division of Cell Biology and Immunology, School of Life Sciences, MSI/WTB Complex, University of Dundee, Dundee, UK.
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Astoul E, Laurence AD, Totty N, Beer S, Alexander DR, Cantrell DA. Approaches to define antigen receptor-induced serine kinase signal transduction pathways. J Biol Chem 2003; 278:9267-75. [PMID: 12515807 DOI: 10.1074/jbc.m211252200] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In the present report we describe the properties of a novel phospho-specific antiserum that has opened a route to the characterization of antigen receptor-activated serine kinase pathways in lymphocytes. The basis for the present work was that Ser-21 in glycogen synthase kinase 3alpha is robustly phosphorylated following antigen receptor triggering. We predicted accordingly that antigen receptors would also stimulate phosphorylation of other proteins with a similar sequence. To test this idea we raised an antibody against the phospho-peptide RARTSpSFAEP, where pS is a phospho-serine corresponding to the glycogen synthase kinase 3alpha Ser-21 sequence. The resulting antiserum was called phospho antibody for proteomics-1 (PAP-1). The present study describes the properties of PAP-1 and shows that it can reveal quite striking differences in the phospho-proteome of different cell types and is able to pinpoint new targets in important signal transduction pathways. PAP-1 was used to map protein phosphorylations regulated by the antigen receptor in T cells. One of these PAP-1-reactive proteins was purified and revealed to be a previously unrecognized target for antigen receptor signal transduction, namely an "orphan" adapter SLY (Src homology 3 (SH3) domain-containing protein expressed in lymphocytes). The use of sera detecting specific phosphorylation sites is thus proved as a powerful method for the discovery of novel downstream components of antigen receptor signals in T cells.
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Affiliation(s)
- Emmanuelle Astoul
- Lymphocyte Activation Laboratory, Cancer Research UK London Research Institute, Lincoln's Inn Fields Laboratories, 44 Lincoln's Inn Fields, London WC2A 3PX, United Kingdom
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39
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Abstract
Immature double positive (DP) thymocytes bearing a T cell receptor (TCR) that interacts with self-major histocompatibility complex (MHC) molecules receive signals that induce either their differentiation (positive selection) or apoptosis (negative selection). Furthermore, those cells that are positively selected develop into two different lineages, CD4 or CD8, depending on whether their TCRs bind to MHC class II or I, respectively. Positive selection therefore involves rescue from the default fate (death), lineage commitment, and progression to the single positive (SP) stage. These are probably temporally distinct events that may require both unique and overlapping signals. Work in the past several years has started to unravel the signaling networks that control these processes. One of the first pathways identified as important for positive selection was Ras and its downstream effector, the Erk mitogen-activated protein kinase (MAPK) cascade. In this review we examine the factors that connect the TCR to the Ras/Erk cascade in DP thymocytes, as well as what we know about the downstream effectors of the Ras/Erk cascade important for positive selection. We also consider the possible role of this cascade in CD4/CD8 lineage development, and the possible interactions of the Ras/Erk cascade with Notch during these cell fate determination processes.
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Affiliation(s)
- José Alberola-Ila
- Division of Biology, California Institute of Technology, Pasadena, CA 91125, USA.
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40
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Abstract
Transmembrane adapter proteins (TRAPs) are a relatively new and growing family of proteins that include linker for activation of T cells (LAT), phosphoprotein associated with glycosphingolipid-enriched micro domains (PAG)/C-terminal Src kinase (Csk) binding protein (Cbp), SHP2-interacting transmembrane adapter protein (SIT), T cell receptor interacting molecule (TRIM), and the recently identified non-T cell activation linker (NTAL) and pp30. TRAPs share several common structural features, but more importantly they possess multiple sites of tyrosine phosphorylation, by which they act as scaffolds for recruiting cytosolic adapter and/or effector proteins. The membrane association of TRAPs places them near to the immunoreceptors, a position from which they coordinate and modulate the signals they receive to produce an appropriate cellular response.
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41
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Vigorito E, Billadeu DD, Savoy D, McAdam S, Doody G, Fort P, Turner M. RhoG regulates gene expression and the actin cytoskeleton in lymphocytes. Oncogene 2003; 22:330-42. [PMID: 12545154 DOI: 10.1038/sj.onc.1206116] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
RhoG, a member of the Rho family of GTPases, has been implicated as a regulator of the actin cytoskeleton. In this study, we show a novel function for the small GTPase RhoG on the regulation of the interferon-gamma promoter and nuclear factor of activated T cells (NFAT) gene transcription in lymphocytes. Optimal function of RhoG for the expression of these genes requires a calcium signal, normally provided by the antigen receptor. In addition, RhoG potentiation of NFAT requires the indirect activity of Rac and Cdc42; however, pathways distinct from those activated by Rac and Cdc42 mediate RhoG activation of NFAT-dependent transcription. Using effector domain mutants of RhoG we found that its ability to potentiate NFAT-dependent transcription correlates with its capacity to increase actin polymerization, supporting the suggestion that NFAT-dependent transcription is an actin-dependent process. RhoG also promotes T-cell spreading on fibronectin, a property that is independent of its ability to enhance NFAT-dependent transcription. Hence, these results implicate RhoG in leukocyte trafficking and the control of gene expression induced in response to antigen encounter.
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Affiliation(s)
- Elena Vigorito
- Laboratory for Lymphocyte Signalling and Development, Molecular Immunology Programme, The Babraham Institute, Cambridge, UK.
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42
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Faehling M, Kroll J, Föhr KJ, Fellbrich G, Mayr U, Trischler G, Waltenberger J. Essential role of calcium in vascular endothelial growth factor A-induced signaling: mechanism of the antiangiogenic effect of carboxyamidotriazole. FASEB J 2002; 16:1805-7. [PMID: 12354692 DOI: 10.1096/fj.01-0938fje] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Vascular endothelial growth factor-A (VEGF-A) plays a major role in tumor angiogenesis and raises the concentration of intracellular free calcium ([Ca2+]i). Carboxyamidotriazole (CAI), an inhibitor of calcium influx and of angiogenesis, is under investigation as a tumoristatic agent. We studied the effect of CAI and the role of [Ca2+]i in VEGF-A signaling in human endothelial cells. VEGF-A induced a biphasic [Ca2+]i signal. VEGF-A increased the level of intracellular inositol 1,4,5-trisphosphate (IP3), which suggests that VEGF-A releases Ca2+ from IP3-sensitive stores and induces store-operated calcium influx. Reduction of either extracellular or intracellular free Ca2+ inhibited VEGF-A-induced proliferation. CAI inhibited IP3 formation, both phases of the calcium signal, nitric oxide (NO) release, and proliferation induced by VEGF-A. CAI prevented neither activation of VEGF receptor-2 (VEGFR-2) (KDR/Flk-1), phospholipase C-g, or mitogen-activated protein kinase (MAP kinase) nor translocation of nuclear factor of activated T cells (NFAT). We conclude that calcium signaling is necessary for VEGF-A-induced proliferation. MAP kinase activation occurs independently of [Ca2+]i but is not sufficient to induce proliferation in the absence of calcium signaling. Inhibition of the VEGF-A-induced [Ca2+]i signal and proliferation by CAI can be explained by inhibition of IP3 formation and may contribute to the antiangiogenic action of CAI. Calcium-dependent NO formation may represent a link between calcium signaling and proliferation.
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Affiliation(s)
- Martin Faehling
- Department of Internal Medicine II, University of Ulm, 89081 Ulm, Germany
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43
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Allen MP, Xu M, Linseman DA, Pawlowski JE, Bokoch GM, Heidenreich KA, Wierman ME. Adhesion-related kinase repression of gonadotropin-releasing hormone gene expression requires Rac activation of the extracellular signal-regulated kinase pathway. J Biol Chem 2002; 277:38133-40. [PMID: 12138087 DOI: 10.1074/jbc.m200826200] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Recent studies suggest that adhesion-related kinase (Ark) plays a role in gonadotropin-releasing hormone (GnRH) neuronal physiology. Ark promotes migration of GnRH neurons via Rac GTPase and concomitantly suppresses GnRH gene expression via homeodomain and myocyte enhancer factor-2 (MEF2) transcription factors. Here, we investigated the signaling cascade required for Ark inhibition of the GnRH promoter in GT1-7 GnRH neuronal cells. Ark repression was blocked by the MEK/ERK pathway inhibitor, PD98059, and dominant negative MEK1 but was unaffected by dominant negative Ras. Inhibitors of the Rho family GTPases, Clostridium difficile toxin B (Rho/Rac/Cdc42 inhibitor) and Clostridium sordellii lethal toxin (Rac/Cdc42 inhibitor), blocked Ark inhibition of GnRH transcription. Moreover, dominant negative Rac blunted both Ark activation of ERK and repression of the GnRH promoter, demonstrating an essential role for Rac in coupling Ark to ERK activation. Like Ark, a constitutively active mutant of Rac suppressed GnRH transcription in an ERK-dependent manner. Finally, Ark-mediated repression was significantly attenuated by a dominant negative MEF2C, whereas repression induced by constitutively active Rac was unaffected, indicating that MEF2 proteins are not targets of the Ark --> Rac --> MEK --> ERK cascade. The data suggest that Ark suppresses GnRH gene expression via the coordinated activation of a Rac --> ERK signaling pathway and a distinct MEF2- dependent mechanism.
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Affiliation(s)
- Melissa P Allen
- Department of Medicine, University of Colorado Health Sciences Center, Denver, Colorado 80262, USA
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44
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Yablonski D, Weiss A. Mechanisms of signaling by the hematopoietic-specific adaptor proteins, SLP-76 and LAT and their B cell counterpart, BLNK/SLP-65. Adv Immunol 2002; 79:93-128. [PMID: 11680012 DOI: 10.1016/s0065-2776(01)79003-7] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Adaptor proteins lack catalytic activity and contain only protein-protein interaction domains. They have been shown to interact with an ever-growing number of signaling proteins and to play essential roles in many signaling pathways. SLP-76 and LAT are cell-type-specific adaptor proteins expressed in T cells, NK cells, platelets, and mast cells. In these cell types, SLP-76 and LAT are required for signaling by immunoreceptor tyrosine-based activation motif(ITAM)-containing receptors, including the T cell receptor (TCR), the pre-TCR, the high-affinity Fc epsilon receptor, and the platelet GPVI collagen receptor. In B cells, an analogous adaptor, BLNK/SLP-65, is required for signaling by the ITAM-containing B cell receptor. This review summarizes recent research on SLP-76, LAT, and BLNK. A major challenge in understanding adaptor protein function has been to sort out the many interactions mediated by adaptor proteins and to define the mechanisms by which adaptors mediate critical signaling events. In the case of LAT, SLP-76, and BLNK, the availability of tractable genetic systems, deficient in expression of each of these adaptor proteins, has facilitated in-depth investigation of their signaling functions and mechanisms of action. The picture that has emerged is one in which multiple adaptor proteins cooperate to bring about the formation of a large signaling complex, localized to specialized lipid microdomains within the cell membrane and known as GEMs. Adaptors not only recruit signaling proteins, but also play an active role in regulating the conformation and activation of many of the proteins recruited to the complex. In particular, recent research has shed light on the mechanisms by which multiple adaptor proteins cooperate to bring about the recruitment and activation of phospholipase C gamma in response to the activation of ITAM-containing receptors.
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Affiliation(s)
- D Yablonski
- Department of Pharmacology, Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Bat Galim, Haifa 31096, Israel
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45
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Shen R, Ouyang YB, Qu CK, Alonso A, Sperzel L, Mustelin T, Kaplan MH, Feng GS. Grap negatively regulates T-cell receptor-elicited lymphocyte proliferation and interleukin-2 induction. Mol Cell Biol 2002; 22:3230-6. [PMID: 11971956 PMCID: PMC133801 DOI: 10.1128/mcb.22.10.3230-3236.2002] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Grb-2-related adaptor protein (Grap) is a Grb2-like SH3-SH2-SH3 adaptor protein with expression restricted to lymphoid tissues. Grap(-/-) lymphocytes isolated from targeted Grap-deficient mice exhibited enhanced proliferation, interleukin-2 production, and c-fos induction in response to mitogenic T-cell receptor (TCR) stimulation, compared to wild-type cells. Ectopic expression of Grap led to a suppression of Elk-1-directed transcription induced by the Ras/Erk pathway, without having effects on gene expression mediated by Jnk and p38 mitogen-activated protein kinases. Together, these data suggest that Grap, unlike Grb2, acts as a negative regulator of TCR-stimulated intracellular signaling by downregulating signal relay through the Ras/Erk pathway.
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Affiliation(s)
- Randy Shen
- Program in Signal Transduction Research, The Burnham Institute, La Jolla, California 92037, USA
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46
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Nel AE. T-cell activation through the antigen receptor. Part 1: signaling components, signaling pathways, and signal integration at the T-cell antigen receptor synapse. J Allergy Clin Immunol 2002; 109:758-70. [PMID: 11994696 DOI: 10.1067/mai.2002.124259] [Citation(s) in RCA: 134] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Part 1 of this review will highlight the basic components and signaling pathways by which the T-cell antigen receptor (TCR) activates mature extrathymic T cells. TCR signaling commences with an early wave of protein tyrosine kinase activation, which is mediated by the Src kinases Lck and Fyn, the 70-kd zeta-associated protein kinase, and members of the Tec kinase family. This early wave of protein tyrosine phosphorylation leads to the activation of downstream signaling pathways, including an increase in intracellular free calcium, protein kinase C, nuclear factor kappaB and Ras-mitogen-activated protein kinase activation. These pathways activate transcription factors, such as activator protein 1, nuclear factor of activated T cells, and Rel proteins, which ultimately lead to the expression of genes that control cellular proliferation, differentiation, anergy, or apoptosis. This review also describes how costimulatory receptors assist in signal transduction and assembly of macromolecular complexes at the TCR contact site with the antigen-presenting cell, also known as the immune synapse. These basic concepts of TCR signal transduction will be used in part 2 to explain how T-cell function can be altered by therapeutic targeting of TCR signaling components, as well as to explain modification of TCR signaling during T(H)1/T(H)2 differentiation, tolerance, and immune senescence.
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Affiliation(s)
- Andre E Nel
- Division of Clinical Immunology/Allergy, Department of Medicine, UCLA School of Medicine, University of California, Los Angeles 90095-1680, USA
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Albrecht B, D'Souza CD, Ding W, Tridandapani S, Coggeshall KM, Lairmore MD. Activation of nuclear factor of activated T cells by human T-lymphotropic virus type 1 accessory protein p12(I). J Virol 2002; 76:3493-501. [PMID: 11884573 PMCID: PMC136046 DOI: 10.1128/jvi.76.7.3493-3501.2002] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Human T-lymphotropic virus type 1 (HTLV-1) is the agent of an aggressive malignancy of CD4(+) T lymphocytes, called adult T-cell lymphoma/leukemia, and is associated with numerous immune-mediated diseases. To establish infection, HTLV-1 must activate targeted T cells during early stages of infection. We recently demonstrated that the HTLV-1 accessory protein p12(I) is critical for persistent infection in vivo and for viral infectivity in quiescent primary lymphocytes, suggesting a role for p12(I) in lymphocyte activation. To test whether p12(I) modulates signaling pathways required for T-lymphocyte activation, we examined AP-1-, NF-kappaB-, and nuclear factor of activated T cells (NFAT)-driven reporter gene activity in p12(I)-expressing Jurkat T cells compared to vector-transfected control cells. HTLV-1 p12(I) specifically induced NFAT-mediated transcription approximately 20-fold in synergy with the Ras/mitogen-activated protein kinase pathway, but did not influence AP-1- or NF-kappaB-dependent gene expression. Inhibition of calcium-dependent signals by cyclosporin A, BAPTA-AM [glycine, N,N'-1,2-ethanediylbis(oxy-2,1-phenylene)-bis-N-2-(acetyloxy)methoxy-2-oxoethyl]-[bis(acetyloxy)methyl ester], and a dominant negative mutant of NFAT2 abolished the p12(I)-mediated activation of NFAT-dependent transcription. In contrast, inhibition of phospholipase C-gamma and LAT (linker for activation of T cells) did not affect p12(I)-induced NFAT activity. Importantly, p12(I) functionally substituted for thapsigargin, which selectively depletes intracellular calcium stores. Our data are the first to demonstrate a role for HTLV-1 p12(I) in calcium-dependent activation of NFAT-mediated transcription in lymphoid cells. We propose a novel mechanism by which HTLV-1, a virus associated with lymphoproliferative disease, dysregulates common T-cell activation pathways critical for the virus to establish persistent infection.
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Affiliation(s)
- Björn Albrecht
- Center for Retrovirus Research and Department of Veterinary Biosciences, College of Medicine and Public Health, The Ohio State University, Columbus, Ohio 43210, USA
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Brenner BC, Kadel S, Grigorovich S, Linderkamp O. Mechanisms of L-selectin-induced activation of the nuclear factor of activated T lymphocytes (NFAT). Biochem Biophys Res Commun 2002; 291:237-44. [PMID: 11846396 DOI: 10.1006/bbrc.2002.6451] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Selectins are mediating transient contacts of leukocytes with endothelium during inflammatory processes and in the development of the immune system. L-selectin expressed on almost all leukocytes also functions as a signaling receptor. Recently, we have identified different signaling pathways in T lymphocytes by L-selectin. One signaling cascade leads via the tyrosine kinase p56lck to the small G-proteins Ras and Rac and to MAP-kinases. A second independent pathway results in ceramide release. In this study, an L-selectin-induced translocation of the transcription factor NFAT to the nucleus was identified. Using genetically modified JCaM1.6 cells, pharmacological inhibitors, and antisense molecules, it was shown that L-selectin-induced NFAT activation depends on src-tyrosine kinases, calcineurin and small G-proteins. MAP-kinases and actin filaments were identified as Ras effectors involved in NFAT translocation. We conclude that L-selectin cross-linking results in activation of NFAT by different signaling pathways. The activation of NFAT might modulate the immune response of leukocytes interacting with endothelial cells.
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Affiliation(s)
- Birgit C Brenner
- Department of Cardiology, Children's Hospital, Moorenstrasse 5, Düsseldorf, Germany.
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Alterations in signal transduction inT lymphocytes and neutrophils with ageing. ACTA ACUST UNITED AC 2002. [DOI: 10.1016/s1566-3124(02)13006-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Gringhuis SI, Papendrecht-van der Voort EAM, Leow A, Nivine Levarht EW, Breedveld FC, Verweij CL. Effect of redox balance alterations on cellular localization of LAT and downstream T-cell receptor signaling pathways. Mol Cell Biol 2002; 22:400-11. [PMID: 11756537 PMCID: PMC139732 DOI: 10.1128/mcb.22.2.400-411.2002] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The integral membrane protein linker for activation of T cells (LAT) is a central adapter protein in the T-cell receptor (TCR)-mediated signaling pathways. The cellular localization of LAT is extremely sensitive to intracellular redox balance alterations. Reduced intracellular levels of the antioxidant glutathione (GSH), a hallmark of chronic oxidative stress, resulted in the membrane displacement of LAT, abrogated TCR-mediated signaling and consequently hyporesponsiveness of T lymphocytes. The membrane displacement of LAT is accompanied by a considerable difference in the mobility of LAT upon native and nonreducing denaturing polyacrylamide gel electrophoresis analysis, a finding indicative of a conformational change. Targeted mutation of redox-sensitive cysteine residues within LAT created LAT mutants which remain membrane anchored under conditions of chronic oxidative stress. The expression of redox-insensitive LAT mutants allows for restoration of TCR-mediated signal transduction, whereas CD28-mediated signaling pathways remained impaired. These results are indicative that the membrane displacement of LAT as a result of redox balance alterations is a consequence of a conformational change interfering with the insertion of LAT into the plasma membrane. Conclusively, the data suggest a role for LAT as a crucial intermediate in the sensitivity of TCR signaling and hence T lymphocytes toward chronic oxidative stress.
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Affiliation(s)
- Sonja I Gringhuis
- Department of Rheumatology, Leiden University Medical Center, 2300 RC Leiden, The Netherlands.
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