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James J, Coelho A, Lahore GF, Hernandez CM, Forster F, Malissen B, Holmdahl R. Redox Regulation of LAT Enhances T Cell-Mediated Inflammation. Antioxidants (Basel) 2024; 13:499. [PMID: 38671946 PMCID: PMC11047684 DOI: 10.3390/antiox13040499] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2024] [Revised: 04/04/2024] [Accepted: 04/07/2024] [Indexed: 04/28/2024] Open
Abstract
The positional cloning of single nucleotide polymorphisms (SNPs) of the neutrophil cytosolic factor 1 (Ncf1) gene, advocating that a low oxidative burst drives autoimmune disease, demands an understanding of the underlying molecular causes. A cellular target could be T cells, which have been shown to be regulated by reactive oxygen species (ROS). However, the pathways by which ROS mediate T cell signaling remain unclear. The adaptor molecule linker for activation of T cells (LAT) is essential for coupling T cell receptor-mediated antigen recognition to downstream responses, and it contains several cysteine residues that have previously been suggested to be involved in redox regulation. To address the possibility that ROS regulate T cell-dependent inflammation through LAT, we established a mouse strain with cysteine-to-serine mutations at positions 120 and 172 (LATSS). We found that redox regulation of LAT through C120 and C172 mediate its localization and phosphorylation. LATSS mice had reduced numbers of double-positive thymocytes and naïve peripheral T cells. Importantly, redox insensitivity of LAT enhanced T cell-dependent autoimmune inflammation in collagen-induced arthritis (CIA), a mouse model of rheumatoid arthritis (RA). This effect was reversed on an NCF1-mutated (NCF1m1j), ROS-deficient, background. Overall, our data show that LAT is redox-regulated, acts to repress T cell activation, and is targeted by ROS induced by NCF1 in antigen-presenting cells (APCs).
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Affiliation(s)
- Jaime James
- Medical Inflammation Research, Division of Immunology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, 17177 Stockholm, Sweden; (J.J.); (A.C.); (G.F.L.); (C.M.H.); (F.F.)
| | - Ana Coelho
- Medical Inflammation Research, Division of Immunology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, 17177 Stockholm, Sweden; (J.J.); (A.C.); (G.F.L.); (C.M.H.); (F.F.)
| | - Gonzalo Fernandez Lahore
- Medical Inflammation Research, Division of Immunology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, 17177 Stockholm, Sweden; (J.J.); (A.C.); (G.F.L.); (C.M.H.); (F.F.)
| | - Clara M. Hernandez
- Medical Inflammation Research, Division of Immunology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, 17177 Stockholm, Sweden; (J.J.); (A.C.); (G.F.L.); (C.M.H.); (F.F.)
| | - Florian Forster
- Medical Inflammation Research, Division of Immunology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, 17177 Stockholm, Sweden; (J.J.); (A.C.); (G.F.L.); (C.M.H.); (F.F.)
| | - Bernard Malissen
- Centre d’Immunophénomique, Aix Marseille Université, INSERM, 13288 Marseille, France;
| | - Rikard Holmdahl
- Medical Inflammation Research, Division of Immunology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, 17177 Stockholm, Sweden; (J.J.); (A.C.); (G.F.L.); (C.M.H.); (F.F.)
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Sheikh K, Memon KN, Usman H, Abdel-Maksoud MA, Ullah S, Almanaa TN, Chaudhary A, Jamil M, Gill OBQ, Yar MA, Hussein AM, Zakri AM. Identification of useful biomolecular markers in kidney renal clear cell carcinoma: an in silico and in vitro analysis-based study. Am J Transl Res 2023; 15:5574-5593. [PMID: 37854221 PMCID: PMC10579006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Accepted: 08/28/2023] [Indexed: 10/20/2023]
Abstract
BACKGROUND Kidney renal clear cell carcinoma (KIRC) is the most prevalent type of renal cell carcinoma (RCC), with a high incidence and mortality rate. There is a lack of sensitive biomarkers. Therefore, the discovery of accurate biomarkers for KIRC patients is critical to improve prognosis. METHODS We determined hub genes and their associated pathways involved in the pathogenesis of KIRC from the GSE66272 dataset consisting of KIRC (n = 26) and corresponding control (n = 26) samples and later validated the expression and methylation level of the identified hub genes on The Cancer Genomic Atlas (TCGA) datasets and Human RCC 786-O and normal HK-2 cell lines through RNA sequencing (RNA-seq), Reverse transcription-quantitative polymerase chain reaction (RT-qPCR), and targeted bisulfite sequencing (bisulfite-seq) analyses. RESULTS The identified up-regulated four hub genes include TYROBP (Transmembrane Immune Signaling Adaptor TYROBP), PTPRC (Protein tyrosine phosphatase, receptor type, C), LCP2 (Lymphocyte cytosolic protein 2), and ITGB2 (Integrin Subunit Beta 2). Moreover, the higher expression of TYROBP, PTPRC, LCP2, and ITGB2 in KIRC patients insignificantly correlates with a poor prognosis in KIRC patients. In addition, hub genes were involved in the "Fc epsilon RI signaling pathway, asthma, natural cell killer mediated cytotoxicity, T cell receptor signaling pathway, primary immunodeficiency, Fc gamma R-mediated phagocytosis, malaria, leukocyte transendothelial migration, and legionellosis" pathways and associated with the infiltration level of CD8+ T, CD4+ T, and macrophage cells. CONCLUSION Our integrated in silico and in vitro analysis identified important hub genes (TYROBP, PTPRC, LCP2, and ITGB2) involved in the pathogenesis of KIRC as possible diagnostic biomarkers.
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Affiliation(s)
- Khalida Sheikh
- Liaquat University of Medical and Health Sciences (LUMHS)Jamshoro 76090, Pakistan
| | | | - Humera Usman
- Fazaia Medical College, Air UniversityIslamabad 44000, Pakistan
| | | | | | | | - Aqsa Chaudhary
- Department of Biochemistry, University of Central PunjabLahore, Pakistan
| | - Muhammad Jamil
- PARC Arid Zone Research CenterDera Ismail Khan 29050, Pakistan
| | | | - Muhammad Ahmed Yar
- Mufti Mehmood Memorial Teaching HospitalDera Ismail Khan 29050, KPK, Pakistan
| | - Ahmed M Hussein
- Department of Pharmaceutical Sciences, Division of Pharmacology and Toxicology, University of ViennaVienna 1090, Austria
| | - Adel M Zakri
- Plant Production Department, College of Food and Agricultural Sciences, King Saud UniversityRiyadh 11451, Saudi Arabia
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Fernández-Aguilar LM, Vico-Barranco I, Arbulo-Echevarria MM, Aguado E. A Story of Kinases and Adaptors: The Role of Lck, ZAP-70 and LAT in Switch Panel Governing T-Cell Development and Activation. BIOLOGY 2023; 12:1163. [PMID: 37759563 PMCID: PMC10525366 DOI: 10.3390/biology12091163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Revised: 08/18/2023] [Accepted: 08/20/2023] [Indexed: 09/29/2023]
Abstract
Specific antigen recognition is one of the immune system's features that allows it to mount intense yet controlled responses to an infinity of potential threats. T cells play a relevant role in the host defense and the clearance of pathogens by means of the specific recognition of peptide antigens presented by antigen-presenting cells (APCs), and, to do so, they are equipped with a clonally distributed antigen receptor called the T-cell receptor (TCR). Upon the specific engagement of the TCR, multiple intracellular signals are triggered, which lead to the activation, proliferation and differentiation of T lymphocytes into effector cells. In addition, this signaling cascade also operates during T-cell development, allowing for the generation of cells that can be helpful in the defense against threats, as well as preventing the generation of autoreactive cells. Early TCR signals include phosphorylation events in which the tyrosine kinases Lck and ZAP70 are involved. The sequential activation of these kinases leads to the phosphorylation of the transmembrane adaptor LAT, which constitutes a signaling hub for the generation of a signalosome, finally resulting in T-cell activation. These early signals play a relevant role in triggering the development, activation, proliferation and apoptosis of T cells, and the negative regulation of these signals is key to avoid aberrant processes that could generate inappropriate cellular responses and disease. In this review, we will examine and discuss the roles of the tyrosine kinases Lck and ZAP70 and the membrane adaptor LAT in these cellular processes.
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Grants
- PY20_01297 Consejería de Transformación Económica, Industria, Conocimiento y Universidades, Junta de Andalucía, Spain
- PID2020-113943RB-I00 Agencia Estatal de Investigación, Ministerio de Ciencia e Innovación, Spain
- PR2022-037 University of Cádiz
- PAIDI2020/DOC_01433 Consejería de Transformación Económica, Industria, Conocimiento y Universidades, Junta de Andalucía, Spain
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Affiliation(s)
- Luis M. Fernández-Aguilar
- Institute for Biomedical Research of Cadiz (INIBICA), 11009 Cadiz, Spain; (L.M.F.-A.); (I.V.-B.); (M.M.A.-E.)
- Department of Biomedicine, Biotechnology and Public Health (Immunology), University of Cadiz, 11002 Cadiz, Spain
| | - Inmaculada Vico-Barranco
- Institute for Biomedical Research of Cadiz (INIBICA), 11009 Cadiz, Spain; (L.M.F.-A.); (I.V.-B.); (M.M.A.-E.)
- Department of Biomedicine, Biotechnology and Public Health (Immunology), University of Cadiz, 11002 Cadiz, Spain
| | - Mikel M. Arbulo-Echevarria
- Institute for Biomedical Research of Cadiz (INIBICA), 11009 Cadiz, Spain; (L.M.F.-A.); (I.V.-B.); (M.M.A.-E.)
- Department of Biomedicine, Biotechnology and Public Health (Immunology), University of Cadiz, 11002 Cadiz, Spain
| | - Enrique Aguado
- Institute for Biomedical Research of Cadiz (INIBICA), 11009 Cadiz, Spain; (L.M.F.-A.); (I.V.-B.); (M.M.A.-E.)
- Department of Biomedicine, Biotechnology and Public Health (Immunology), University of Cadiz, 11002 Cadiz, Spain
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Title: Bioinformatic Identification of Genes Involved in Diabetic Nephropathy Fibrosis and their Clinical Relevance. Biochem Genet 2023:10.1007/s10528-023-10336-6. [PMID: 36715962 DOI: 10.1007/s10528-023-10336-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2022] [Accepted: 01/09/2023] [Indexed: 01/31/2023]
Abstract
Tubulointerstitial fibrosis is an important pathological feature of diabetic nephropathy that is associated with impaired renal function. However, the mechanism by which fibrosis occurs in diabetic nephropathy is unclear. Differentially expressed genes were identified from transcriptome profiles of renal tissue from diabetic patients and unilateral ureteral obstruction mice and intersected to obtain genes that may be involved in diabetic fibrosis. Biological function analysis and protein-protein interaction network analysis were performed. ROC curve and Pearson correlation analysis between hub genes were performed and glomerular filtration rate estimated. Finally, the RNA levels of hub genes were measured using real-time PCR. A total of 283 genes were identified as potentially involved in diabetic nephropathy fibrosis. TYROBP, CTSS, LCP2, LUM and TLR7 were identified as aberrantly expressed hub genes. Immune cell infiltration analysis demonstrated higher numbers of cytotoxic lymphocytes, B lineage cells, monocyte lineage cells, myeloid dendritic cells, neutrophils, and fibroblasts in the diabetic nephropathy group. The areas under ROC curves for TYROBP, CTSS, LCP2, LUM and TLR7 were 0.9167, 0.9583, 0.9917, 0.93333, and 0.9583, respectively (P < 0.001), and their correlation coefficients with estimated glomerular filtration rate were - 0.8332, - 0.752, - 0.7875, - 0.7567, and - 0.7136, respectively (P < 0.001). The RNA levels of TYROBP, CTSS, LUM and TLR7 were upregulated in high-glucose-treated human renal tubular epithelial cells (P < 0.005). Our study identified TYROBP, CTSS, LCP2, LUM and TLR7 as potentially involved in diabetic nephropathy fibrosis. Furthermore, TYROBP, CTSS, LUM and TLR7 may be associated with epithelial-mesenchymal transition of tubular epithelial cells.
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Liang J, Chen J, Hua S, Qin Z, Lu J, Lan C. Bioinformatics analysis of the key genes in osteosarcoma metastasis and immune invasion. Transl Pediatr 2022; 11:1656-1670. [PMID: 36345453 PMCID: PMC9636461 DOI: 10.21037/tp-22-402] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Accepted: 09/08/2022] [Indexed: 11/07/2022] Open
Abstract
BACKGROUND This study sought to identify potential key genes for osteosarcoma metastasis and analyze their immune infiltration patterns using bioinformatic methods. METHODS We obtained transcriptomic data related to osteosarcoma and osteosarcoma with metastasis from the Therapeutically Applicable Research to Generate Effective Treatment (TARGET) and The Gene Expression Omnibus (GEO) databases and identified the differentially expressed genes (DEGs). We also identified potential key genes for osteosarcoma metastasis by a protein-protein interaction network analysis, and we conducted a Gene Ontology (GO) functional annotation analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis to identify the core genes for prognosis, immune cell infiltration, and drug sensitivity, and the risk prediction and prognosis models of metastasis were constructed. RESULTS By comparing the transcriptome data of osteosarcomas without metastasis and those with metastasis, a total of 19 core DEGs were identified, and the GO and KEGG analyses revealed an association between these DEGs and the regulation of cell division, secretory granule lumen, the Ras-associated protein 1 (Rap1) signaling pathway, and the mitogen-activated protein kinase (MAPK) signaling pathway. Compared with other immune cells, macrophage infiltration was predominant in osteosarcoma samples with metastatic osteosarcoma, and insulin-like growth factors-1 (IGF1) and myelocytomatosis protein 2 (MYC2) genes were predicted to more than 50 targeted therapeutic agents. A metastasis prediction model with 5 genes [i.e., ecotropic viral integration site 2B (EVI2B), CCAAT/enhancer binding protein (CEBPA), lymphocyte cytosolic protein 2 (LCP2), selectin L (SELL), and Niemann-Pick disease, type C2A (NPC2A)], and a prognostic model with 4 genes [i.e., insulin-like growth factors-2 (IGF2), cathepsin O (CTSO), Niemann-Pick disease, type C2 (NPC2), and amyloid beta (A4) precursor protein-binding, family B, member 1 interacting protein (APBB1IP)] were developed. CONCLUSIONS We constructed a metastasis prediction model with 5 genes (i.e., EVI2B, CEBPA, LCP2, SELL, and NPC2A), and a prognostic model with 4 genes (i.e., IGF2, CTSO, NPC2, and APBB1IP) that may be potential biomarkers for osteosarcoma metastasis. Macrophages are the predominant immune infiltrating cells in osteosarcoma metastasis and may provide a new direction for the treatment of osteosarcoma.
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Affiliation(s)
- Junqing Liang
- Department of Joint Surgery, The People's Hospital of Baise, Baise, China
| | - Jun Chen
- Department of Joint Surgery, The People's Hospital of Baise, Baise, China
| | - Shuliang Hua
- Department of Joint Surgery, The People's Hospital of Baise, Baise, China
| | - Zhuangguang Qin
- Department of Joint Surgery, The People's Hospital of Baise, Baise, China
| | - Jili Lu
- Department of Joint Surgery, The People's Hospital of Baise, Baise, China
| | - Changgong Lan
- Department of Joint Surgery, The Affiliated Hospital of Youjiang Medical University for Nationalities, Baise, China
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Huo Y, Zhang K, Han S, Feng Y, Bao Y. Lymphocyte cytosolic protein 2 is a novel prognostic marker in lung adenocarcinoma. J Int Med Res 2021; 49:3000605211059681. [PMID: 34816740 PMCID: PMC8649447 DOI: 10.1177/03000605211059681] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
OBJECTIVE Lymphocyte cytosolic protein 2 (LCP2) is often ectopically expressed in various human tumors. However, the clinical significance and role of LCP2 in lung adenocarcinoma (LUAD) remain unclear. This study explored the prognostic significance of LCP2 in LUAD patients. METHODS LCP2 expression in LUAD tissues was analyzed using data from The Cancer Genome Atlas and Genotype-Tissue Expression databases. Western blotting was employed to detect LCP2 expression in LUAD. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses were performed to explore signaling pathways mediated by LCP2 co-regulatory genes. Immunohistochemistry was used to examine levels of LCP2 and programmed death ligand 1 (PD-L1) in 68 LUAD patients. Associations between LCP2 expression and clinicopathological features, prognoses, and PD-L1 levels among the LUAD in-patients were analyzed. RESULTS Among the 68 LUAD in-patients, LCP2 expression was correlated with clinical stage and lymph node metastasis. LUAD patients with high LCP2 expression were associated with increased overall survival. LCP2 expression may be associated with an enrichment of several immune functions. Moreover, our immunohistochemistry results demonstrated that LCP2 expression was positively correlated with PD-L1 expression in LUAD tissues. CONCLUSIONS In the study, LCP2 was found to be a favorable prognostic biomarker in LUAD patients.
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Affiliation(s)
- Yishan Huo
- Clinical Oncology Center, The First Affiliated Hospital of Xinjiang Medical University, Urumqi, Xinjiang Uygur Autonomous Region, China.,Clinical Laboratory Center, 74790Xinjiang Medical University, Tumor Hospital Affiliated to Xinjiang Medical University, Urumqi, Xinjiang Uygur Autonomous Region, China
| | - Kainan Zhang
- Xinjiang Medical University, Urumqi, Xinjiang Uygur Autonomous Region, China
| | - Songtao Han
- Clinical Laboratory Center of Xinjiang Medical University Affiliated Traditional Chinese Medicine Hospital, Urumqi, Xinjiang Uygur Autonomous Region, China
| | - Yangchun Feng
- Clinical Laboratory Center, 74790Xinjiang Medical University, Tumor Hospital Affiliated to Xinjiang Medical University, Urumqi, Xinjiang Uygur Autonomous Region, China
| | - Yongxing Bao
- Clinical Oncology Center, The First Affiliated Hospital of Xinjiang Medical University, Urumqi, Xinjiang Uygur Autonomous Region, China
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Dinur-Schejter Y, Zaidman I, Mor-Shaked H, Stepensky P. The Clinical Aspect of Adaptor Molecules in T Cell Signaling: Lessons Learnt From Inborn Errors of Immunity. Front Immunol 2021; 12:701704. [PMID: 34456914 PMCID: PMC8397411 DOI: 10.3389/fimmu.2021.701704] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Accepted: 07/26/2021] [Indexed: 12/22/2022] Open
Abstract
Adaptor molecules lack enzymatic and transcriptional activities. Instead, they exert their function by linking multiple proteins into intricate complexes, allowing for transmitting and fine-tuning of signals. Many adaptor molecules play a crucial role in T-cell signaling, following engagement of the T-cell receptor (TCR). In this review, we focus on Linker of Activation of T cells (LAT) and SH2 domain-containing leukocyte protein of 76 KDa (SLP-76). Monogenic defects in these adaptor proteins, with known roles in T-cell signaling, have been described as the cause of human inborn errors of immunity (IEI). We describe the current knowledge based on defects in cell lines, murine models and human patients. Germline mutations in Adhesion and degranulation adaptor protein (ADAP), have not resulted in a T-cell defect.
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Affiliation(s)
- Yael Dinur-Schejter
- Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem, Israel.,The Bone Marrow Transplantation and Cancer Immunotherapy Department, Hadassah Ein Kerem Medical Center, Jerusalem, Israel.,Allergy and Clinical Immunology Unit, Hadassah Ein-Kerem Medical Center, Jerusalem, Israel
| | - Irina Zaidman
- Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem, Israel.,The Bone Marrow Transplantation and Cancer Immunotherapy Department, Hadassah Ein Kerem Medical Center, Jerusalem, Israel
| | - Hagar Mor-Shaked
- Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem, Israel.,Monique and Jacques Roboh Department of Genetic Research, Hadassah Ein Kerem Medical Center, Jerusalem, Israel
| | - Polina Stepensky
- Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem, Israel.,The Bone Marrow Transplantation and Cancer Immunotherapy Department, Hadassah Ein Kerem Medical Center, Jerusalem, Israel
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Kent A, Longino NV, Christians A, Davila E. Naturally Occurring Genetic Alterations in Proximal TCR Signaling and Implications for Cancer Immunotherapy. Front Immunol 2021; 12:658611. [PMID: 34012443 PMCID: PMC8126620 DOI: 10.3389/fimmu.2021.658611] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Accepted: 04/06/2021] [Indexed: 11/13/2022] Open
Abstract
T cell-based immunotherapies including genetically engineered T cells, adoptive transfer of tumor-infiltrating lymphocytes, and immune checkpoint blockade highlight the impressive anti-tumor effects of T cells. These successes have provided new hope to many cancer patients with otherwise poor prognoses. However, only a fraction of patients demonstrates durable responses to these forms of therapies and many develop significant immune-mediated toxicity. These heterogeneous clinical responses suggest that underlying nuances in T cell genetics, phenotypes, and activation states likely modulate the therapeutic impact of these approaches. To better characterize known genetic variations that may impact T cell function, we 1) review the function of early T cell receptor-specific signaling mediators, 2) offer a synopsis of known mutations and genetic alterations within the associated molecules, 3) discuss the link between these mutations and human disease and 4) review therapeutic strategies under development or in clinical testing that target each of these molecules for enhancing anti-tumor T cell activity. Finally, we discuss novel engineering approaches that could be designed based on our understanding of the function of these molecules in health and disease.
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Affiliation(s)
- Andrew Kent
- Division of Medical Oncology, Department of Medicine, University of Colorado, Aurora, CO, United States
- Human Immunology and Immunotherapy Initiative, University of Colorado, Aurora, CO, United States
- University of Colorado Comprehensive Cancer Center, Aurora, CO, United States
| | - Natalie V. Longino
- Division of Medical Oncology, Department of Medicine, University of Colorado, Aurora, CO, United States
- Human Immunology and Immunotherapy Initiative, University of Colorado, Aurora, CO, United States
- University of Colorado Comprehensive Cancer Center, Aurora, CO, United States
- Department of Medicine, University of Colorado, Aurora, CO, United States
| | - Allison Christians
- Division of Medical Oncology, Department of Medicine, University of Colorado, Aurora, CO, United States
- Human Immunology and Immunotherapy Initiative, University of Colorado, Aurora, CO, United States
- University of Colorado Comprehensive Cancer Center, Aurora, CO, United States
| | - Eduardo Davila
- Division of Medical Oncology, Department of Medicine, University of Colorado, Aurora, CO, United States
- Human Immunology and Immunotherapy Initiative, University of Colorado, Aurora, CO, United States
- University of Colorado Comprehensive Cancer Center, Aurora, CO, United States
- Department of Medicine, University of Colorado, Aurora, CO, United States
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A Novel, LAT/Lck Double Deficient T Cell Subline J.CaM1.7 for Combined Analysis of Early TCR Signaling. Cells 2021; 10:cells10020343. [PMID: 33562083 PMCID: PMC7915312 DOI: 10.3390/cells10020343] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 02/02/2021] [Accepted: 02/03/2021] [Indexed: 11/21/2022] Open
Abstract
Intracellular signaling through the T cell receptor (TCR) is essential for T cell development and function. Proper TCR signaling requires the sequential activities of Lck and ZAP-70 kinases, which result in the phosphorylation of tyrosine residues located in the CD3 ITAMs and the LAT adaptor, respectively. LAT, linker for the activation of T cells, is a transmembrane adaptor protein that acts as a scaffold coupling the early signals coming from the TCR with downstream signaling pathways leading to cellular responses. The leukemic T cell line Jurkat and its derivative mutants J.CaM1.6 (Lck deficient) and J.CaM2 (LAT deficient) have been widely used to study the first signaling events upon TCR triggering. In this work, we describe the loss of LAT adaptor expression found in a subline of J.CaM1.6 cells and analyze cis-elements responsible for the LAT expression defect. This new cell subline, which we have called J.CaM1.7, can re-express LAT adaptor after Protein Kinase C (PKC) activation, which suggests that activation-induced LAT expression is not affected in this new cell subline. Contrary to J.CaM1.6 cells, re-expression of Lck in J.CaM1.7 cells was not sufficient to recover TCR-associated signals, and both LAT and Lck had to be introduced to recover activatory intracellular signals triggered after CD3 crosslinking. Overall, our work shows that the new LAT negative J.CaM1.7 cell subline could represent a new model to study the functions of the tyrosine kinase Lck and the LAT adaptor in TCR signaling, and their mutual interaction, which seems to constitute an essential early signaling event associated with the TCR/CD3 complex.
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Tremblay MM, Ollinger T, Houtman JCD. The membrane proximal proline-rich region and correct order of C-terminal tyrosines on the adaptor protein LAT are required for TCR-mediated signaling and downstream functions. Cell Signal 2020; 76:109790. [PMID: 32979494 DOI: 10.1016/j.cellsig.2020.109790] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 09/21/2020] [Accepted: 09/22/2020] [Indexed: 12/11/2022]
Abstract
The primary activating receptor for T cells is the T cell receptor (TCR), which is stimulated upon binding to an antigen/MHC complex. TCR activation results in the induction of regulated signaling pathways vital for T cell differentiation, cellular adhesion and cytokine release. A critical TCR-induced signaling protein is the adaptor protein LAT. Upon TCR stimulation, LAT is phosphorylated on conserved tyrosines, which facilitates the formation of multiprotein complexes needed for propagation of signaling pathways. Although the role of the conserved tyrosines in LAT-mediated signaling has been investigated, few studies have examined the role of larger regions of LAT in TCR-induced pathways. In this study, a sequence alignment of 97 mammalian LAT proteins was used to identify several "functional" domains on LAT. Using LAT mutants expressed in Jurkat E6.1 cells, we observed that the membrane proximal, proline-rich region of LAT and the correct order of domains containing conserved tyrosines are necessary for optimal TCR-mediated early signaling, cytokine production, and cellular adhesion. Together, these data show that LAT contains distinct regions whose presence and correct order are required for the propagation of TCR-mediated signaling pathways.
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Affiliation(s)
- Mikaela M Tremblay
- Department of Microbiology and Immunology, Carver College of Medicine, University of Iowa, USA
| | - Tomye Ollinger
- Department of Microbiology and Immunology, Carver College of Medicine, University of Iowa, USA
| | - Jon C D Houtman
- Department of Microbiology and Immunology, Carver College of Medicine, University of Iowa, USA.
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Yablonski D. Bridging the Gap: Modulatory Roles of the Grb2-Family Adaptor, Gads, in Cellular and Allergic Immune Responses. Front Immunol 2019; 10:1704. [PMID: 31402911 PMCID: PMC6669380 DOI: 10.3389/fimmu.2019.01704] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Accepted: 07/08/2019] [Indexed: 01/07/2023] Open
Abstract
Antigen receptor signaling pathways are organized by adaptor proteins. Three adaptors, LAT, Gads, and SLP-76, form a heterotrimeric complex that mediates signaling by the T cell antigen receptor (TCR) and by the mast cell high affinity receptor for IgE (FcεRI). In both pathways, antigen recognition triggers tyrosine phosphorylation of LAT and SLP-76. The recruitment of SLP-76 to phospho-LAT is bridged by Gads, a Grb2 family adaptor composed of two SH3 domains flanking a central SH2 domain and an unstructured linker region. The LAT-Gads-SLP-76 complex is further incorporated into larger microclusters that mediate antigen receptor signaling. Gads is positively regulated by dimerization, which promotes its cooperative binding to LAT. Negative regulation occurs via phosphorylation or caspase-mediated cleavage of the linker region of Gads. FcεRI-mediated mast cell activation is profoundly impaired in LAT- Gads- or SLP-76-deficient mice. Unexpectedly, the thymic developmental phenotype of Gads-deficient mice is much milder than the phenotype of LAT- or SLP-76-deficient mice. This distinction suggests that Gads is not absolutely required for TCR signaling, but may modulate its sensitivity, or regulate a particular branch of the TCR signaling pathway; indeed, the phenotypic similarity of Gads- and Itk-deficient mice suggests a functional connection between Gads and Itk. Additional Gads binding partners include costimulatory proteins such as CD28 and CD6, adaptors such as Shc, ubiquitin regulatory proteins such as USP8 and AMSH, and kinases such as HPK1 and BCR-ABL, but the functional implications of these interactions are not yet fully understood. No interacting proteins or function have been ascribed to the evolutionarily conserved N-terminal SH3 of Gads. Here we explore the biochemical and functional properties of Gads, and its role in regulating allergy, T cell development and T-cell mediated immunity.
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Affiliation(s)
- Deborah Yablonski
- The Immune Cell Signaling Lab, Department of Immunology, Ruth and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
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12
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Yablonski D. Bridging the Gap: Modulatory Roles of the Grb2-Family Adaptor, Gads, in Cellular and Allergic Immune Responses. Front Immunol 2019; 10:1704. [PMID: 31402911 DOI: 10.3389/fimmu.2019.01704/full] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Accepted: 07/08/2019] [Indexed: 05/22/2023] Open
Abstract
Antigen receptor signaling pathways are organized by adaptor proteins. Three adaptors, LAT, Gads, and SLP-76, form a heterotrimeric complex that mediates signaling by the T cell antigen receptor (TCR) and by the mast cell high affinity receptor for IgE (FcεRI). In both pathways, antigen recognition triggers tyrosine phosphorylation of LAT and SLP-76. The recruitment of SLP-76 to phospho-LAT is bridged by Gads, a Grb2 family adaptor composed of two SH3 domains flanking a central SH2 domain and an unstructured linker region. The LAT-Gads-SLP-76 complex is further incorporated into larger microclusters that mediate antigen receptor signaling. Gads is positively regulated by dimerization, which promotes its cooperative binding to LAT. Negative regulation occurs via phosphorylation or caspase-mediated cleavage of the linker region of Gads. FcεRI-mediated mast cell activation is profoundly impaired in LAT- Gads- or SLP-76-deficient mice. Unexpectedly, the thymic developmental phenotype of Gads-deficient mice is much milder than the phenotype of LAT- or SLP-76-deficient mice. This distinction suggests that Gads is not absolutely required for TCR signaling, but may modulate its sensitivity, or regulate a particular branch of the TCR signaling pathway; indeed, the phenotypic similarity of Gads- and Itk-deficient mice suggests a functional connection between Gads and Itk. Additional Gads binding partners include costimulatory proteins such as CD28 and CD6, adaptors such as Shc, ubiquitin regulatory proteins such as USP8 and AMSH, and kinases such as HPK1 and BCR-ABL, but the functional implications of these interactions are not yet fully understood. No interacting proteins or function have been ascribed to the evolutionarily conserved N-terminal SH3 of Gads. Here we explore the biochemical and functional properties of Gads, and its role in regulating allergy, T cell development and T-cell mediated immunity.
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Affiliation(s)
- Deborah Yablonski
- The Immune Cell Signaling Lab, Department of Immunology, Ruth and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
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13
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Arbulo-Echevarria MM, Narbona-Sánchez I, Fernandez-Ponce CM, Vico-Barranco I, Rueda-Ygueravide MD, Dustin ML, Miazek A, Duran-Ruiz MC, García-Cózar F, Aguado E. A Stretch of Negatively Charged Amino Acids of Linker for Activation of T-Cell Adaptor Has a Dual Role in T-Cell Antigen Receptor Intracellular Signaling. Front Immunol 2018; 9:115. [PMID: 29456532 PMCID: PMC5801411 DOI: 10.3389/fimmu.2018.00115] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Accepted: 01/15/2018] [Indexed: 11/13/2022] Open
Abstract
The adaptor protein linker for activation of T cells (LAT) has an essential role transducing activatory intracellular signals coming from the TCR/CD3 complex. Previous reports have shown that upon T-cell activation, LAT interacts with the tyrosine kinase Lck, leading to the inhibition of its kinase activity. LAT-Lck interaction seemed to depend on a stretch of negatively charged amino acids in LAT. Here, we have substituted this segment of LAT between amino acids 113 and 126 with a non-charged segment and expressed the mutant LAT (LAT-NIL) in J.CaM2 cells in order to analyze TCR signaling. Substitution of this segment in LAT prevented the activation-induced interaction with Lck. Moreover, cells expressing this mutant form of LAT showed a statistically significant increase of proximal intracellular signals such as phosphorylation of LAT in tyrosine residues 171 and 191, and also enhanced ZAP70 phosphorylation approaching borderline statistical significance (p = 0.051). Nevertheless, downstream signals such as Ca2+ influx or MAPK pathways were partially inhibited. Overall, our data reveal that LAT-Lck interaction constitutes a key element regulating proximal intracellular signals coming from the TCR/CD3 complex.
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Affiliation(s)
- Mikel M Arbulo-Echevarria
- Department of Biomedicine, Biotechnology and Public Health (Immunology), Core Research Facility for Health Sciences, University of Cádiz and Puerto Real University Hospital Research Unit, Cádiz, Spain
| | - Isaac Narbona-Sánchez
- Department of Biomedicine, Biotechnology and Public Health (Immunology), Core Research Facility for Health Sciences, University of Cádiz and Puerto Real University Hospital Research Unit, Cádiz, Spain
| | - Cecilia M Fernandez-Ponce
- Department of Biomedicine, Biotechnology and Public Health (Immunology), Core Research Facility for Health Sciences, University of Cádiz and Puerto Real University Hospital Research Unit, Cádiz, Spain
| | - Inmaculada Vico-Barranco
- Department of Biomedicine, Biotechnology and Public Health (Immunology), Core Research Facility for Health Sciences, University of Cádiz and Puerto Real University Hospital Research Unit, Cádiz, Spain
| | | | - Michael L Dustin
- Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, The Kennedy Institute of Rheumatology, The University of Oxford, Headington, United Kingdom
| | - Arkadiusz Miazek
- Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Wroclaw, Poland
| | - Mª Carmen Duran-Ruiz
- Department of Biomedicine, Biotechnology and Public Health (Biochemistry), University of Cádiz, Cádiz, Spain.,Institute of Biomedical Research Cadiz (INIBICA), Cádiz, Spain
| | - Francisco García-Cózar
- Department of Biomedicine, Biotechnology and Public Health (Immunology), Core Research Facility for Health Sciences, University of Cádiz and Puerto Real University Hospital Research Unit, Cádiz, Spain.,Institute of Biomedical Research Cadiz (INIBICA), Cádiz, Spain
| | - Enrique Aguado
- Department of Biomedicine, Biotechnology and Public Health (Immunology), Core Research Facility for Health Sciences, University of Cádiz and Puerto Real University Hospital Research Unit, Cádiz, Spain.,Institute of Biomedical Research Cadiz (INIBICA), Cádiz, Spain
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14
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Myers DR, Zikherman J, Roose JP. Tonic Signals: Why Do Lymphocytes Bother? Trends Immunol 2017; 38:844-857. [PMID: 28754596 DOI: 10.1016/j.it.2017.06.010] [Citation(s) in RCA: 79] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Revised: 06/23/2017] [Accepted: 06/27/2017] [Indexed: 01/09/2023]
Abstract
Since the 1990s it has been known that B and T lymphocytes exhibit low-level, constitutive signaling in the basal state (tonic signaling). These lymphocytes display a range of affinity for self, which in turn generates a range of tonic signaling. Surprisingly, what signaling pathways are active in the basal state and the functional relevance of the observed tonic signaling heterogeneity remain open questions today. Here we summarize what is known about the mechanistic and functional details of tonic signaling. We highlight recent advances that have increased our understanding of how the amount of tonic signal impacts immune function, describing novel tools that have moved the field forward and toward a molecular understanding of tonic signaling.
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Affiliation(s)
- Darienne R Myers
- Department of Anatomy, School of Medicine, University of California, San Francisco, CA 94143, USA
| | - Julie Zikherman
- Division of Rheumatology, Rosalind Russell and Ephraim P. Engleman Arthritis Research Center, Department of Medicine, University of California, San Francisco, CA 94143, USA
| | - Jeroen P Roose
- Department of Anatomy, School of Medicine, University of California, San Francisco, CA 94143, USA.
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15
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Keller B, Zaidman I, Yousefi OS, Hershkovitz D, Stein J, Unger S, Schachtrup K, Sigvardsson M, Kuperman AA, Shaag A, Schamel WW, Elpeleg O, Warnatz K, Stepensky P. Early onset combined immunodeficiency and autoimmunity in patients with loss-of-function mutation in LAT. J Exp Med 2016; 213:1185-99. [PMID: 27242165 PMCID: PMC4925012 DOI: 10.1084/jem.20151110] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Accepted: 05/04/2016] [Indexed: 12/13/2022] Open
Abstract
Keller et al. describe for the first time human LAT deficiency, which causes severe immune dysregulation with autoimmunity, lymphoproliferation, and progressive immunodeficiency. The adapter protein linker for activation of T cells (LAT) is a critical signaling hub connecting T cell antigen receptor triggering to downstream T cell responses. In this study, we describe the first kindred with defective LAT signaling caused by a homozygous mutation in exon 5, leading to a premature stop codon deleting most of the cytoplasmic tail of LAT, including the critical tyrosine residues for signal propagation. The three patients presented from early childhood with combined immunodeficiency and severe autoimmune disease. Unlike in the mouse counterpart, reduced numbers of T cells were present in the patients. Despite the reported nonredundant role of LAT in Ca2+ mobilization, residual T cells were able to induce Ca2+ influx and nuclear factor (NF) κB signaling, whereas extracellular signal-regulated kinase (ERK) signaling was completely abolished. This is the first report of a LAT-related disease in humans, manifesting by a progressive combined immune deficiency with severe autoimmune disease.
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Affiliation(s)
- Baerbel Keller
- Center for Chronic Immunodeficiency (CCI), University Medical Center and University of Freiburg, 79106 Freiburg, Germany
| | - Irina Zaidman
- Department of Pediatric Hematology Oncology, Ruth Rappaport Children's Hospital, Rambam Health Care Campus, Haifa 3109601, Israel
| | - O Sascha Yousefi
- Center for Chronic Immunodeficiency (CCI), University Medical Center and University of Freiburg, 79106 Freiburg, Germany Department of Molecular Immunology, Faculty of Biology, BIOSS Centre for Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany Spemann Graduate School of Biology and Medicine (SGBM), Albert Ludwigs University Freiburg, 79104 Freiburg, Germany
| | - Dov Hershkovitz
- Department of Pathology, Rambam Health Care Campus, Haifa 3109601, Israel
| | - Jerry Stein
- Department of Pediatric Hematology Oncology and Bone Marrow Transplantation Unit, Schneider Children's Medical Center of Israel, Petah-Tikva 49202, Israel
| | - Susanne Unger
- Center for Chronic Immunodeficiency (CCI), University Medical Center and University of Freiburg, 79106 Freiburg, Germany
| | - Kristina Schachtrup
- Center for Chronic Immunodeficiency (CCI), University Medical Center and University of Freiburg, 79106 Freiburg, Germany
| | - Mikael Sigvardsson
- Department of Clinical and Experimental Medicine, Experimental Hematopoiesis Unit, Faculty of Health Sciences, Linköping University, 581 85 Linköping, Sweden
| | - Amir A Kuperman
- Blood Coagulation Service and Pediatric Hematology Clinic, Galilee Medical Center, Nahariya 22100, Israel Faculty of Medicine in the Galilee, Bar-Ilan University, Safed 5290002, Israel
| | - Avraham Shaag
- Monique and Jacques Roboh Department of Genetic Research, Hadassah Medical Center, Hebrew University, Jerusalem 91120, Israel
| | - Wolfgang W Schamel
- Center for Chronic Immunodeficiency (CCI), University Medical Center and University of Freiburg, 79106 Freiburg, Germany Department of Molecular Immunology, Faculty of Biology, BIOSS Centre for Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany
| | - Orly Elpeleg
- Monique and Jacques Roboh Department of Genetic Research, Hadassah Medical Center, Hebrew University, Jerusalem 91120, Israel
| | - Klaus Warnatz
- Center for Chronic Immunodeficiency (CCI), University Medical Center and University of Freiburg, 79106 Freiburg, Germany
| | - Polina Stepensky
- Monique and Jacques Roboh Department of Genetic Research, Hadassah Medical Center, Hebrew University, Jerusalem 91120, Israel Department of Pediatric Hematology-Oncology and Bone Marrow Transplantation, Hadassah Medical Center, Hebrew University, Jerusalem 91120, Israel
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16
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Balagopalan L, Kortum RL, Coussens NP, Barr VA, Samelson LE. The linker for activation of T cells (LAT) signaling hub: from signaling complexes to microclusters. J Biol Chem 2015; 290:26422-9. [PMID: 26354432 DOI: 10.1074/jbc.r115.665869] [Citation(s) in RCA: 84] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Since the cloning of the critical adapter, LAT (linker for activation of T cells), more than 15 years ago, a combination of multiple scientific approaches and techniques continues to provide valuable insights into the formation, composition, regulation, dynamics, and function of LAT-based signaling complexes. In this review, we will summarize current views on the assembly of signaling complexes nucleated by LAT. LAT forms numerous interactions with other signaling molecules, leading to cooperativity in the system. Furthermore, oligomerization of LAT by adapter complexes enhances intracellular signaling and is physiologically relevant. These results will be related to data from super-resolution microscopy studies that have revealed the smallest LAT-based signaling units and nanostructure.
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Affiliation(s)
- Lakshmi Balagopalan
- From the Laboratory of Cellular and Molecular Biology, Center for Cancer Research, NCI, National Institutes of Health, Bethesda, Maryland 20892-4256
| | - Robert L Kortum
- the Department of Pharmacology, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814, and
| | - Nathan P Coussens
- the Division of Pre-Clinical Innovation, National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland 20850
| | - Valarie A Barr
- From the Laboratory of Cellular and Molecular Biology, Center for Cancer Research, NCI, National Institutes of Health, Bethesda, Maryland 20892-4256
| | - Lawrence E Samelson
- From the Laboratory of Cellular and Molecular Biology, Center for Cancer Research, NCI, National Institutes of Health, Bethesda, Maryland 20892-4256,
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17
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Kłossowicz M, Marek-Bukowiec K, Arbulo-Echevarria MM, Ścirka B, Majkowski M, Sikorski AF, Aguado E, Miazek A. Identification of functional, short-lived isoform of linker for activation of T cells (LAT). Genes Immun 2014; 15:449-56. [PMID: 25008862 DOI: 10.1038/gene.2014.35] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2014] [Revised: 05/04/2014] [Accepted: 05/23/2014] [Indexed: 12/13/2022]
Abstract
Linker for activation of T cells (LAT) is a transmembrane adaptor protein playing a key role in the development, activation and maintenance of peripheral homeostasis of T cells. In this study we identified a functional isoform of LAT. It originates from an intron 6 retention event generating an in-frame splice variant of LAT mRNA denoted as LATi6. Comparison of LATi6 expression in peripheral blood leukocytes of human and several other mammalian species revealed that it varied from being virtually absent in the mouse to being predominant in the cow. Analysis of LAT isoform frequency expressed from minigene splicing reporters carrying loss- or gain-of-function point mutations within intronic polyguanine sequences showed that these elements are critical for controlling the intron 6 removal. The protein product of LATi6 isoform (LATi6) ectopically expressed in LAT-deficient JCam 2.5 cell line localized correctly to subcellular compartments and supported T-cell receptor signaling but differed from the canonical LAT protein by displaying a shorter half-life and mediating an increased interleukin-2 secretion upon prolonged CD3/CD28 crosslinking. Altogether, our data suggest that the appearance of LATi6 isoform is an evolutionary innovation that may contribute to a more efficient proofreading control of effector T-cell response.
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Affiliation(s)
- M Kłossowicz
- Laboratory of Tumor Immunology, Department of Tumor Immunology, Ludwik Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Wroclaw, Poland
| | - K Marek-Bukowiec
- Laboratory of Tumor Immunology, Department of Tumor Immunology, Ludwik Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Wroclaw, Poland
| | - M M Arbulo-Echevarria
- Department of Biomedicine, Biotechnology and Public Health (Immunology), Core Research Facility for Health Sciences, University of Cadiz and Puerto Real University Hospital Research Unit, School of Medicine, Department of Biomedicine, Biotechnology and Public Health (Immunology), Cadiz, Spain
| | - B Ścirka
- Laboratory of Tumor Immunology, Department of Tumor Immunology, Ludwik Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Wroclaw, Poland
| | - M Majkowski
- Laboratory of Cytobiochemistry, Biotechnology Faculty, University of Wrocław, Wroclaw, Poland
| | - A F Sikorski
- Laboratory of Cytobiochemistry, Biotechnology Faculty, University of Wrocław, Wroclaw, Poland
| | - E Aguado
- Department of Biomedicine, Biotechnology and Public Health (Immunology), Core Research Facility for Health Sciences, University of Cadiz and Puerto Real University Hospital Research Unit, School of Medicine, Department of Biomedicine, Biotechnology and Public Health (Immunology), Cadiz, Spain
| | - A Miazek
- 1] Laboratory of Tumor Immunology, Department of Tumor Immunology, Ludwik Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Wroclaw, Poland [2] Department of Biochemistry, Pharmacology and Toxicology, Wroclaw University of Environmental and Life Sciences, Wroclaw, Poland
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18
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Krishnamoorthy S, Liu Z, Hong A, Zhu R, Chen H, Li T, Zhou X, Gao X. A Novel Phosphopeptide Microarray Based Interactome Map in Breast Cancer Cells Reveals Phosphoprotein-GRB2 Cell Signaling Networks. PLoS One 2013; 8:e67634. [PMID: 23826330 PMCID: PMC3694890 DOI: 10.1371/journal.pone.0067634] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2012] [Accepted: 05/21/2013] [Indexed: 11/23/2022] Open
Abstract
The architecture of cellular proteins connected to form signaling pathways in response to internal and external cues is much more complex than a group of simple protein-protein interactions. Post translational modifications on proteins (e.g., phosphorylation of serine, threonine and tyrosine residues on proteins) initiate many downstream signaling events leading to protein-protein interactions and subsequent activation of signaling cascades leading to cell proliferation, cell differentiation and cell death. As evidenced by a rapidly expanding mass spectrometry database demonstrating protein phosphorylation at specific motifs, there is currently a large gap in understanding the functional significance of phosphoproteins with respect to their specific protein connections in the signaling cascades. A comprehensive map that interconnects phospho-motifs in pathways will enable identification of nodal protein interactions that are sensitive signatures indicating a disease phenotype from the physiological hemostasis and provide clues into control of disease. Using a novel phosphopeptide microarray technology, we have mapped endogenous tyrosine-phosphoproteome interaction networks in breast cancer cells mediated by signaling adaptor protein GRB2, which transduces cellular responses downstream of several RTKs through the Ras-ERK signaling cascade. We have identified several previously reported motif specific interactions and novel interactions. The peptide microarray data indicate that various phospho-motifs on a single protein are differentially regulated in various cell types and shows global downregulation of phosphoprotein interactions specifically in cells with metastatic potential. The study has revealed novel phosphoprotein mediated signaling networks, which warrants further detailed analysis of the nodes of protein-protein interaction to uncover their biomarker or therapeutic potential.
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Affiliation(s)
- Srinivasan Krishnamoorthy
- Department of Biology and Biochemistry, University of Houston, Houston, Texas, United States of America
- * E-mail: (SK); (XG)
| | - Zhonghua Liu
- Department of Biology and Biochemistry, University of Houston, Houston, Texas, United States of America
| | - Ailing Hong
- LC Sciences, Houston, Texas, United States of America
| | - Ruijuan Zhu
- Department of Biology and Biochemistry, University of Houston, Houston, Texas, United States of America
| | - Haosi Chen
- Department of Biology and Biochemistry, University of Houston, Houston, Texas, United States of America
| | - Tongbin Li
- LC Sciences, Houston, Texas, United States of America
| | | | - Xiaolian Gao
- Department of Biology and Biochemistry, University of Houston, Houston, Texas, United States of America
- * E-mail: (SK); (XG)
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19
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Kortum RL, Rouquette-Jazdanian AK, Miyaji M, Merrill RK, Markegard E, Pinski JM, Wesselink A, Nath NN, Alexander CP, Li W, Kedei N, Roose JP, Blumberg PM, Samelson LE, Sommers CL. A phospholipase C-γ1-independent, RasGRP1-ERK-dependent pathway drives lymphoproliferative disease in linker for activation of T cells-Y136F mutant mice. THE JOURNAL OF IMMUNOLOGY 2012; 190:147-58. [PMID: 23209318 DOI: 10.4049/jimmunol.1201458] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Mice expressing a germline mutation in the phospholipase C-γ1-binding site of linker for activation of T cells (LAT) show progressive lymphoproliferation and ultimately die at 4-6 mo age. The hyperactivated T cells in these mice show defective TCR-induced calcium flux but enhanced Ras/ERK activation, which is critical for disease progression. Despite the loss of LAT-dependent phospholipase C-γ1 binding and activation, genetic analysis revealed RasGRP1, and not Sos1 or Sos2, to be the major Ras guanine exchange factor responsible for ERK activation and the lymphoproliferative phenotype in these mice. Analysis of isolated CD4(+) T cells from LAT-Y136F mice showed altered proximal TCR-dependent kinase signaling, which activated a Zap70- and LAT-independent pathway. Moreover, LAT-Y136F T cells showed ERK activation that was dependent on Lck and/or Fyn, protein kinase C-θ, and RasGRP1. These data demonstrate a novel route to Ras activation in vivo in a pathological setting.
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Affiliation(s)
- Robert L Kortum
- Laboratory of Cellular and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
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20
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Bartelt RR, Houtman JCD. The adaptor protein LAT serves as an integration node for signaling pathways that drive T cell activation. WILEY INTERDISCIPLINARY REVIEWS-SYSTEMS BIOLOGY AND MEDICINE 2012; 5:101-10. [PMID: 23150273 DOI: 10.1002/wsbm.1194] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
T cells are essential for the adaptive immune response to pathogens. However, dysfunctional T cell activity has been implicated in numerous diseases, including the failure of organ transplants, allergic reactions, asthma, autoimmune disorders, and coronary artery disease. T cell responses to pathogens require the induction of the primary activating receptor, the T cell receptor (TCR), along with other costimulatory and adhesion receptors. Signal transduction pathways activated downstream of these receptors drive T cell responses required for the immune response and disease progression. A key question in our understanding of the mechanism of T cell activation is how signaling pathways emanating from multiple receptors integrate together to alter T cell effector functions. One integration node for intracellular signaling is the membrane-associated adaptor protein linker for the activation of T cells or LAT. Upon stimulation of the TCR and other receptors, LAT is phosphorylated at several tyrosines residues on its cytoplasmic tail. This leads to the binding of SH2 domain-containing proteins and their associated molecules and the formation of large multiprotein complexes. These dynamic and highly regulated signaling complexes facilitate the production of second messengers, activate downstream pathways, induce actin cytoskeleton polymerization, and stimulate the activity of multiple transcription factors. Thus, signaling pathways from several receptors feed into LAT, which then integrates this information and selectively induces pathways critical for T cell activation and the adaptive immune response.
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21
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Shen S, Chuck MI, Zhu M, Fuller DM, Yang CWO, Zhang W. The importance of LAT in the activation, homeostasis, and regulatory function of T cells. J Biol Chem 2010; 285:35393-405. [PMID: 20837489 PMCID: PMC2975163 DOI: 10.1074/jbc.m110.145052] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2010] [Revised: 08/17/2010] [Indexed: 12/13/2022] Open
Abstract
LAT (linker for activation of T cells) is a transmembrane adaptor protein that plays an essential role in TCR-mediated signaling and thymocyte development. Because LAT-deficient mice have an early block in thymocyte development, we utilized an inducible system to delete LAT in primary T cells to study LAT function in T cell activation, homeostasis, and survival. Deletion of LAT caused primary T cells to become unresponsive to stimulation from the TCR and impaired T cell homeostatic proliferation and long term survival. Furthermore, deletion of LAT led to reduced expression of Foxp3, CTLA-4, and CD25 in T(reg) cells and impaired their function. Consequently, mice with LAT deleted developed a lymphoproliferative syndrome similar to that in LATY136F mice, although less severe. Our data implicate that LAT has positive and negative roles in the regulation of mature T cells.
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MESH Headings
- Adaptor Proteins, Signal Transducing/genetics
- Adaptor Proteins, Signal Transducing/immunology
- Adaptor Proteins, Signal Transducing/metabolism
- Animals
- Autoimmune Lymphoproliferative Syndrome/genetics
- Autoimmune Lymphoproliferative Syndrome/immunology
- Autoimmune Lymphoproliferative Syndrome/metabolism
- Blotting, Western
- Cell Proliferation/drug effects
- Cell Survival/drug effects
- Cell Survival/immunology
- Female
- Flow Cytometry
- Forkhead Transcription Factors/immunology
- Forkhead Transcription Factors/metabolism
- Homeostasis/drug effects
- Homeostasis/immunology
- Lymphocyte Activation/drug effects
- Lymphocyte Activation/immunology
- Male
- Membrane Proteins/genetics
- Membrane Proteins/immunology
- Membrane Proteins/metabolism
- Mice
- Mice, Knockout
- Phosphoproteins/genetics
- Phosphoproteins/immunology
- Phosphoproteins/metabolism
- Receptors, Antigen, T-Cell/immunology
- Receptors, Antigen, T-Cell/metabolism
- Signal Transduction/immunology
- Spleen/cytology
- Spleen/immunology
- Spleen/metabolism
- T-Lymphocytes/cytology
- T-Lymphocytes/immunology
- T-Lymphocytes/metabolism
- T-Lymphocytes, Regulatory/immunology
- T-Lymphocytes, Regulatory/metabolism
- Tamoxifen/pharmacology
- Thymus Gland/cytology
- Thymus Gland/immunology
- Thymus Gland/metabolism
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Affiliation(s)
- Shudan Shen
- From the Department of Immunology, Duke University Medical Center, Durham, North Carolina 27710
| | - Mariana I. Chuck
- From the Department of Immunology, Duke University Medical Center, Durham, North Carolina 27710
| | - Minghua Zhu
- From the Department of Immunology, Duke University Medical Center, Durham, North Carolina 27710
| | - Deirdre M. Fuller
- From the Department of Immunology, Duke University Medical Center, Durham, North Carolina 27710
| | - Chih-wen Ou Yang
- From the Department of Immunology, Duke University Medical Center, Durham, North Carolina 27710
| | - Weiguo Zhang
- From the Department of Immunology, Duke University Medical Center, Durham, North Carolina 27710
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22
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Martínez-Florensa M, García-Blesa A, Yélamos J, Muñoz-Suano A, Domínguez-Villar M, Valdor R, Alonso A, García-Cózar F, Aparicio P, Malissen B, Aguado E. Serine residues in the LAT adaptor are essential for TCR-dependent signal transduction. J Leukoc Biol 2010; 89:63-73. [PMID: 20940326 DOI: 10.1189/jlb.0509342] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The adaptor protein LAT has a prominent role in the transduction of intracellular signals elicited by the TCR/CD3 complex. Upon TCR engagement, LAT becomes tyrosine-phosphorylated and thereby, recruits to the membrane several proteins implicated in the activation of downstream signaling pathways. However, little is known about the role of other conserved motifs present in the LAT sequence. Here, we report that the adaptor LAT contains several conserved serine-based motifs, which are essential for proper signal transduction through the TCR. Mutation of these serine motifs in the human T cell line Jurkat prevents proper calcium influx, MAPK activation, and IL-2 production in response to TCR/CD3 stimulation. Moreover, this mutant form of LAT has a reduced ability to bind to PLC-γ1 and SLP-76, although phosphorylation of tyrosine residues 132, 171, and 191 is not decreased, raising a possible role for the serine-based motifs of LAT for the binding of important partners. The functional role of LAT serine-based motifs in signal transduction could be mediated by an effect on tyrosine phosphorylation, as their mutation significantly diminishes the phosphorylation of tyrosine residue 226. In addition, these serine motifs seem to have a regulatory role, given that upon their mutation, ZAP-70 shows enhanced phosphorylation. Therefore, the LAT serine-based motifs likely regulate signaling pathways that are essential for T cell physiology.
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Affiliation(s)
- Mario Martínez-Florensa
- Departamento de Bioquimíca, Biología Molecular B e Inmunología, Facultad de Medicina, Universidad de Murcia, Murcia, Spain
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Hořejší V, Otáhal P, Brdička T. LAT - an important raft-associated transmembrane adaptor protein. Delivered on 6 July 2009 at the 34th FEBS Congress in Prague, Czech Republic. FEBS J 2010; 277:4383-97. [DOI: 10.1111/j.1742-4658.2010.07831.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Balagopalan L, Coussens NP, Sherman E, Samelson LE, Sommers CL. The LAT story: a tale of cooperativity, coordination, and choreography. Cold Spring Harb Perspect Biol 2010; 2:a005512. [PMID: 20610546 DOI: 10.1101/cshperspect.a005512] [Citation(s) in RCA: 133] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The adapter molecule LAT is a nucleating site for multiprotein signaling complexes that are vital for the function and differentiation of T cells. Extensive investigation of LAT in multiple experimental systems has led to an integrated understanding of the formation, composition, regulation, dynamic movement, and function of LAT-nucleated signaling complexes. This review discusses interactions of signaling molecules that bind directly or indirectly to LAT and the role of cooperativity in stabilizing LAT-nucleated signaling complexes. In addition, it focuses on how imaging studies visualize signaling assemblies as signaling clusters and demonstrate their dynamic nature and cellular fate. Finally, this review explores the function of LAT based on the interpretation of mouse models using various LAT mutants.
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Fuller DM, Zhang W. Regulation of lymphocyte development and activation by the LAT family of adapter proteins. Immunol Rev 2010; 232:72-83. [PMID: 19909357 DOI: 10.1111/j.1600-065x.2009.00828.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Transmembrane adapter proteins (TRAPs) are critical components of signaling pathways in lymphocytes, linking antigen receptor engagement to downstream cellular processes. While these proteins lack intrinsic enzymatic activity, their phosphorylation following receptor ligation allows them to function as scaffolds for the assembly of multi-molecular signaling complexes. Many TRAPs have recently been discovered, and numerous studies demonstrate their roles in the positive and negative regulation of lymphocyte maturation, activation, and differentiation. One such example is the linker for activation of T cells (LAT) family of adapter proteins. While LAT has been shown to play an indispensable role in T-cell and mast cell function, the other family members, linker for activation of B cells (LAB) and linker for activation of X cells (LAX), are necessary to fine-tune immune responses. In addition to its well-established role in the positive regulation of lymphocyte activation, LAT exerts an inhibitory effect on T-cell receptor-mediated signaling. Furthermore, LAT, along with LAB and LAX, plays a crucial role in establishing and maintaining tolerance. Here, we review recent data concerning the regulation of lymphocyte development and activation by the LAT family of proteins.
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Affiliation(s)
- Deirdre M Fuller
- Department of Immunology, Duke University Medical Center, Durham, NC 27710, USA
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SH2 domain containing leukocyte phosphoprotein of 76-kDa (SLP-76) feedback regulation of ZAP-70 microclustering. Proc Natl Acad Sci U S A 2010; 107:10166-71. [PMID: 20534575 DOI: 10.1073/pnas.0909112107] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
T cell receptor (TCR) signaling involves CD4/CD8-p56lck recruitment of ZAP-70 to the TCR receptor, ZAP-70 phosphorylation of LAT that is followed by LAT recruitment of the GADS-SLP-76 complex. Back regulation of ZAP-70 by SLP-76 has not been documented. In this paper, we show that anti-CD3 induced ZAP-70 cluster formation is significantly reduced in the absence of SLP-76 (i.e., J14 cells) and in the presence of a mutant of SLP-76 (4KE) in Jurkat and primary T cells. Both the number of cells with clusters and the number of clusters per cell were reduced. This effect was not mediated by SLP-76 SH2 domain binding to ZAP-70 because SLP-76 failed to precipitate ZAP-70 and an inactivating SH2 domain mutation (i.e., R448L) on SLP-76 4KE did not reverse the inhibition of ZAP-70 clustering. Mutation of R448 on WT SLP-76 still supported ZAP-70 clustering. Intriguingly, by contrast, LAT clustering occurred normally in the absence of SLP-76, or the presence of 4KE SLP-76 indicating that this transmembrane adaptor can operate independently of ZAP-70-GADS-SLP-76. Our findings reconfigure the TCR signaling pathway by showing SLP-76 back-regulation of ZAP-70, an event that could ensure that signaling components are in balance for optimal T cell activation.
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Chuck MI, Zhu M, Shen S, Zhang W. The role of the LAT-PLC-gamma1 interaction in T regulatory cell function. THE JOURNAL OF IMMUNOLOGY 2010; 184:2476-86. [PMID: 20130215 DOI: 10.4049/jimmunol.0902876] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The interaction between the linker for activation of T cells (LAT) with PLC-gamma1 is important for TCR-mediated Ca(2+) signaling and MAPK activation. Knock-in mice harboring a mutation at the PLC-gamma1 binding site (Y136) of LAT develop a severe lymphoproliferative syndrome. These mice have defective thymic development and selection and lack natural regulatory T cells, implicating a breakdown of both central and peripheral tolerance. To bypass this developmental defect, we developed a conditional knock-in line in which only LATY136F is expressed in mature T cells after deletion of the wild type LAT allele. Analysis of LATY136F T cells indicated that the interaction between LAT and PLC-gamma1 plays an important role in TCR-mediated signaling, proliferation, and IL-2 production. Furthermore, the deletion of LAT induced development of the lymphoproliferative syndrome in these mice. Although Foxp3(+) natural Treg cells were present in these mice after deletion, they were unable to suppress the proliferation of conventional T cells. Our data indicate that the binding of LAT to PLC-gamma1 is essential for the suppressive function of CD4(+)CD25(+) regulatory T cells.
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Affiliation(s)
- Mariana I Chuck
- Department of Immunology, Duke University Medical Center, Durham, NC 27710, USA
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Genetic evidence for the role of Erk activation in a lymphoproliferative disease of mice. Proc Natl Acad Sci U S A 2009; 106:14502-7. [PMID: 19667175 DOI: 10.1073/pnas.0903894106] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Germline mutation of the linker for activation of T cells (LAT) gene at the phospholipase C-gamma1 (PLC-gamma1)-binding site leads to a fatal lymphoproliferative disease in mice. The hyperactivated T cells that develop in these mice have defective T-cell antigen receptor (TCR)-induced calcium flux but enhanced mitogen-activated protein kinase (MAPK) activation. We used genetic analysis to investigate genes whose products might suppress MAPK activation and lymphoproliferative disease in LAT mutant mice. B-lymphocyte adaptor molecule of 32 kDa (Bam32) is a known mediator of MAPK activation in B cells. We recently reported that in CD4(+) T cells, Bam32 deficiency decreased MAPK activation and specifically extracellular-signal-regulated kinase (Erk) signaling, following TCR stimulation. By crossing the Bam32 null mutation onto the LAT knock-in background, we found that the Bam32 null mutation delayed the onset and decreased the severity of lymphoproliferative disease in LAT knock-in mice. The pulmonary lymphocyte infiltration seen in LAT knock-in mice was also markedly decreased in double-mutant mice. Additionally, Erk activation was diminished in LAT knock-in Bam32 knockout CD4(+) T cells. To more accurately determine the role of Erk in this delay of lymphoproliferative disease, we also bred a transgenic, hypersensitive Erk allele (the Erk2 sevenmaker mutant) onto the LAT knock-in Bam32 knockout double-mutant background. These triple transgenic mice demonstrated a role for Erk activation in lymphoproliferative disease caused by the LAT knock-in mutation.
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Clarke RL, Thiemann S, Refaeli Y, Werlen G, Potter TA. A new function for LAT and CD8 during CD8-mediated apoptosis that is independent of TCR signal transduction. Eur J Immunol 2009; 39:1619-31. [PMID: 19449311 DOI: 10.1002/eji.200839062] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The majority (>95%) of thymocytes undergo apoptosis during selection in the thymus. Several mechanisms have been proposed to explain how apoptosis of thymocytes that are not positively selected occurs; however, it is unknown whether thymocytes die purely by "neglect" or whether signaling through a cell-surface receptor initiates an apoptotic pathway. We have previously demonstrated that on double positive thymocytes the ligation of CD8 in the absence of TCR engagement results in apoptosis and have postulated this is a mechanism to remove thymocytes that have failed positive selection. On mature single positive T cells CD8 acts as a co-receptor to augment signaling through the TCR that is dependent on the phosphorylation of the adaptor protein, linker for activation of T cells (LAT). Here, we show that during CD8-mediated apoptosis of double positive thymocytes there is an increase in the association of CD8 with LAT and an increase in LAT tyrosine phosphorylation. Decreasing LAT expression and mutation of tyrosine residues of LAT reduced apoptosis upon crosslinking of CD8. Our results identify novel functions for both CD8 and LAT that are independent of TCR signal transduction and suggest a mechanism for signal transduction leading to apoptosis upon CD8 crosslinking.
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Affiliation(s)
- Raedun L Clarke
- Integrated Department of Immunology, National Jewish Health, Denver, CO 80206, USA.
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Shen S, Zhu M, Lau J, Chuck M, Zhang W. The essential role of LAT in thymocyte development during transition from the double-positive to single-positive stage. THE JOURNAL OF IMMUNOLOGY 2009; 182:5596-604. [PMID: 19380807 DOI: 10.4049/jimmunol.0803170] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The linker for activation of T cells (LAT) is an adaptor protein that couples TCR engagement to downstream signaling cascades. LAT is important in early thymocyte development as LAT-deficient mice have a complete block at the double-negative (DN) 3 stage. To study the role of LAT beyond the DN3 stage, we generated mice in which the lat gene could be deleted by the Cre recombinase. Analysis of these mice showed that deletion of LAT after the DN3 stage allowed thymocytes to develop past the DN3 to DN4 checkpoint and to generate double-positive thymocytes. However, LAT-deficient DP thymocytes were severely defective in responding to stimulation via the TCR and failed to differentiate into single-positive thymocytes efficiently. Consequently, few LAT-deficient mature T cells could be found in the periphery. These T cells had undergone extensive homeostatic proliferation and expressed low levels of the TCR on their surface. Collectively, our data indicate that in addition to its role in pre-TCR signaling, LAT also plays an essential role in thymocyte development during transition from the double-positive to single-positive stage.
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Affiliation(s)
- Shudan Shen
- Department of Immunology, Duke University Medical Center, Durham, NC 27710, USA
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Park I, Yun Y. Transmembrane adaptor proteins positively regulating the activation of lymphocytes. Immune Netw 2009; 9:53-7. [PMID: 20107544 PMCID: PMC2803307 DOI: 10.4110/in.2009.9.2.53] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2009] [Accepted: 04/03/2009] [Indexed: 12/25/2022] Open
Abstract
Engagement of the immunoreceptors initiates signaling cascades resulting in lymphocyte activation and differentiation to effector cells, which are essential for the elimination of pathogens from the body. For the transduction of these immunoreceptor-mediated signals, several linker proteins termed transmembrane adaptor proteins (TRAPs) were shown to be required. TRAPs serve as platforms for the assembly and membrane targeting of the specific signaling proteins. Among seven TRAPs identified so far, LAT and LIME were shown to act as a positive regulator in TCR-mediated signaling pathways. In this review, we will discuss the functions of LAT and LIME in modulating T cell development, activation and differentiation.
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Affiliation(s)
- Inyoung Park
- Department of Life Science, Ewha Womans' University, Seoul 120-750, Korea
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Abstract
The analysis of lymphocyte signaling was greatly enhanced by the advent of gene targeting, which allows the selective inactivation of a single gene. Although this gene 'knockout' approach is often informative, in many cases, the phenotype resulting from gene ablation might not provide a complete picture of the function of the corresponding protein. If a protein has multiple functions within a single or several signaling pathways, or stabilizes other proteins in a complex, the phenotypic consequences of a gene knockout may manifest as a combination of several different perturbations. In these cases, gene targeting to 'knock in' subtle point mutations might provide more accurate insight into protein function. However, to be informative, such mutations must be carefully based on structural and biophysical data.
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Affiliation(s)
- Alexander Saveliev
- Medical Research Council National Institute for Medical Research, London, UK
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Torgersen KM, Aandahl EM, Taskén K. Molecular architecture of signal complexes regulating immune cell function. Handb Exp Pharmacol 2008:327-63. [PMID: 18491059 DOI: 10.1007/978-3-540-72843-6_14] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Signals transmitted via multichain immunoreceptors control the development, differentiation and activation of hematopoetic cells. The cytoplasmic parts of these receptors contain immunoreceptor tyrosine-based activation motifs (ITAMs) that upon phosphorylation by members of the Src tyrosine kinase family orchestrate a complex set of signaling events involving tyrosine phosphorylation, generation of second messengers like DAG, IP3 and Ca2+, activation of effector molecules like Ras and MAPKs and the translocation and activation of transcription factors like NFAT, API and NF-kB. Spatial and temporal organization of these signaling events is essential both to connect the receptors to downstream cascades as well as to control the functional outcome of the immune activation. Throughout this process control and fine-tuning of the different signals are necessary both for effective immune function and in order to avoid inappropriate or exaggerated immune activation and autoimmunity. This control includes modulating mechanisms that set the threshold for activation and reset the activation status after an immune response has been launched. One immunomodulating pathway is the cAMP-protein kinase A-Csk pathway scaffolded by a supramolecular complex residing in lipid rafts with the A kinase-anchoring protein (AKAP) ezrin, the Csk-binding protein PAG and a linker between the two, EBP50. Failure of correct scaffolding and loss of spatiotemporal control can potentially have severe consequences, leading to immune failure or autoimmunity. The clinical relevance of supramolecular complexes specifically organized by scaffolding proteins in regulating immune activity and the specter of genetic diseases linked to different signaling components suggest that protein-protein contact surfaces can be potential targets for drug intervention. It is also of interest to note that different pathogens have evolved strategies to specifically modulate signal integration, thereby rewiring the signal in a way beneficial for their survival. In addition to demonstrating the importance of different signal processes, these adaptations are elegant illustrations of the potential for drug targeting of protein assembly. This chapter reviews some of the important scaffolding events downstream of immunoreceptors with focus on signaling transduction through the T-cell receptor (TCR).
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Affiliation(s)
- K M Torgersen
- The Biotechnology Centre of Oslo, Gaustadalléen 21, PO Box 1125 Blindern, Oslo, Norway
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36
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Iwaki S, Spicka J, Tkaczyk C, Jensen BM, Furumoto Y, Charles N, Kovarova M, Rivera J, Horejsi V, Metcalfe DD, Gilfillan AM. Kit- and Fc epsilonRI-induced differential phosphorylation of the transmembrane adaptor molecule NTAL/LAB/LAT2 allows flexibility in its scaffolding function in mast cells. Cell Signal 2007; 20:195-205. [PMID: 17993265 DOI: 10.1016/j.cellsig.2007.10.013] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2007] [Accepted: 10/07/2007] [Indexed: 01/06/2023]
Abstract
The transmembrane adaptor protein (TRAP), NTAL, is phosphorylated in mast cells following FcvarepsilonRI aggregation whereby it cooperates with LAT to induce degranulation. The Kit ligand, stem cell factor (SCF), enhances antigen-induced degranulation and this also appears to be NTAL-dependent. However, Kit and FcvarepsilonRI appear to utilize different mechanisms to induce NTAL phosphorylation. Thus, we examined whether the responsible kinases selectively phosphorylated distinct tyrosines in NTAL and explored the implications for downstream signaling. Whereas FcvarepsilonRI required Lyn and Syk for NTAL phosphorylation, Kit appeared to directly phosphorylate NTAL. Furthermore, co-transfection studies with NTAL constructs revealed that Lyn, Syk, and Kit phosphorylate different tyrosines in NTAL. The tyrosines principally phosphorylated by Syk were recognized as Grb2-binding sites, whereas Lyn and Kit phosphorylated other tyrosines, both inside and outside of these motifs. Pull down studies revealed that PLCgamma1 associated with the two terminal Syk-phosphorylated Grb2-binding sites, which would help to explain the observed decrease in antigen-induced calcium signal and degranulation in NTAL-knock down-human mast cells. The observations reported herein support the conclusion that NTAL may be differentially utilized by specific receptors for relaying alternative signals and this suggests a flexibility in the function of TRAPs not previously appreciated.
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Affiliation(s)
- Shoko Iwaki
- Laboratory of Allergic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 10 Center Drive, MSC 1881, Bethesda, MD 20892-1881, USA
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37
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Abstract
Adapters are multidomain molecules that recruit effector proteins during signal transduction by immunoreceptors and integrins. The absence of these scaffolding molecules profoundly affects development and function of various hematopoietic lineages, underscoring their importance as regulators of signaling cascades. An emerging aspect of the mechanism by which engaged immunoreceptors and integrins transmit signals within the cell is by differential usage of various adapters that function to nucleate formation of distinct signaling complexes in a specific location within the cell. In this review, we discuss the mechanisms by which adapter proteins coordinate signal transduction with an emphasis on the role of subcellular compartmentalization in adapter function.
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Affiliation(s)
- Natalie Bezman
- Abramson Family Cancer Research Institute, University of Pennsylvania, Philadelphia, PA 19104, USA
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Ragab A, Séverin S, Gratacap MP, Aguado E, Malissen M, Jandrot-Perrus M, Malissen B, Ragab-Thomas J, Payrastre B. Roles of the C-terminal tyrosine residues of LAT in GPVI-induced platelet activation: insights into the mechanism of PLC gamma 2 activation. Blood 2007; 110:2466-74. [PMID: 17579183 DOI: 10.1182/blood-2007-02-075432] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Linker for activation of T cells (LAT) is an adaptor protein required for organization of the signaling machinery downstream of the platelet collagen receptor, the glycoprotein VI (GPVI). Here, we investigated the effect of LAT mutations on specific signaling pathways and on platelet functions in response to GPVI triggering by convulxin (Cvx). Using mice containing tyrosine to phenylalanine mutations of the adaptor, we show the crucial role played by the tyrosine residues at positions 175, 195, and 235 in the phosphorylation of LAT and in the whole pattern of protein tyrosine phosphorylation in response to Cvx. These 3 C-terminal tyrosine residues are important to recruit the tyrosine kinase Fyn, which may be involved in LAT phosphorylation. Efficient phosphoinositide 3-kinase (PI3K) activation requires the 3 C-terminal tyrosine residues of LAT but not its tyrosine 136. Interestingly, single mutation of the tyrosine 136 results in the loss of phospholipase C gamma2 (PLCgamma2) activation without affecting its PI3K-dependent membrane association, and is sufficient to impair platelet responses to Cvx. Thus, activation of PLCgamma2 via GPVI is dependent on 2 complementary events: its interaction with the tyrosine 136 of LAT and its membrane location, which itself requires events mediated by the 3 C-terminal tyrosines of LAT.
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Affiliation(s)
- Ashraf Ragab
- Institut National de la Santé et de la Recherche Médicale (INSERM), U563, Centre de Physiopathologie de Toulouse Purpan, Département Oncogenèse, Signalisation et Innovation Thérapeutique, Toulouse, France
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39
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Aguado E, Martínez-Florensa M, Aparicio P. Activation of T lymphocytes and the role of the adapter LAT. Transpl Immunol 2006; 17:23-6. [PMID: 17157209 DOI: 10.1016/j.trim.2006.09.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2006] [Accepted: 09/13/2006] [Indexed: 11/21/2022]
Abstract
The adapter molecule LAT (Linker for the Activation of T cells) is a membrane protein that becomes phosphorylated on conserved tyrosine residues upon TCR/CD3 complex engagement in T lymphocytes. Tyrosine phosphorylation of this adapter recruits to the membrane many signaling proteins through the interaction with the phosphotyrosine binding domains of these proteins, allowing the activation of several intracellular signaling pathways. Initial studies performed in T cell lines suggested that the adapter LAT acts primarily as a platform for the distribution of activation signals coming from the TCR/CD3 complex, and the phenotype of LAT deficient mice, in which T cell development is arrested at an early stage, supported this "activatory" function. However, the analysis of several knock-in mice strains in which some tyrosine residues have been mutated, has revealed the development of lymphoproliferative disorders caused by polyclonal T lymphocytes producing high titers of T helper-type 2 (T(H)2) cytokines. Very recently, it has been demonstrated that raft localization of LAT is altered in anergic T lymphocytes. Therefore, LAT show unexpected regulatory functions in T cell development and homeostasis.
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Affiliation(s)
- Enrique Aguado
- Departamento de Bioquímica, Biología Molecular B e Inmunología, Facultad de Medicina, Campus de Espinardo, Apartado de Correos 4021, Universidad de Murcia, 30100 Murcia, Spain.
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Lovatt M, Filby A, Parravicini V, Werlen G, Palmer E, Zamoyska R. Lck regulates the threshold of activation in primary T cells, while both Lck and Fyn contribute to the magnitude of the extracellular signal-related kinase response. Mol Cell Biol 2006; 26:8655-65. [PMID: 16966372 PMCID: PMC1636771 DOI: 10.1128/mcb.00168-06] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2006] [Revised: 02/28/2006] [Accepted: 08/24/2006] [Indexed: 11/20/2022] Open
Abstract
The src family kinases p56lck (Lck) and p59fyn (Fyn) are the most proximal signaling molecules to be activated downstream of the T-cell receptor. Using an inducible transgenic model, we can regulate the expression of Lck in primary T cells and ask how the signaling cascade and differentiation potential are affected by the absence or the presence of reduced levels of Lck. We show that in naïve T cells, Lck controls the threshold of activation by preferentially regulating multiple signaling pathways that result in the mobilization of Ca2+ through activation of phospholipase C-gamma and protein kinase C as well as activation of the extracellular signal-regulated kinase (ERK)/mitogen-activated protein kinase (MAPK) pathway. Fyn is also able to stimulate the ERK/MAPK pathway in primary T cells but has little influence on the mobilization of Ca2+. Only Lck efficiently stimulates production of diacylglycerol and therefore RasGRP1 recruitment to the plasma membrane and phosphorylation of Shc, suggesting that Fyn activates ERK via a different upstream signaling route. Finally, we show that signals through Lck are essential for the development of T-cell-effector potential, particularly for effective cytokine transcription.
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Affiliation(s)
- Matthew Lovatt
- Molecular Immunology, MRC National Institute for Medical Research, The Ridgeway, London NW71AA, United Kingdom
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Trampont P, Zhang L, Ravichandran KS. ShcA mediates the dominant pathway to extracellular signal-regulated kinase activation during early thymic development. Mol Cell Biol 2006; 26:9035-44. [PMID: 16982683 PMCID: PMC1636838 DOI: 10.1128/mcb.00988-06] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
During thymic development, the beta selection checkpoint is regulated by pre-T-cell receptor-initiated signals. Progression through this checkpoint is influenced by phosphorylation and activation of the serine/threonine kinases extracellular signal-regulated kinase 1 (ERK1) and ERK2, but the in vivo relevance of specific upstream players leading to ERK activation is not known. Here, using mice with a conditional loss of the shc1 gene or expressing mutants of ShcA, we demonstrate that the adapter protein ShcA is responsible for up to 70% of ERK activation in double-negative (DN) thymocytes in vivo and ex vivo. We also identify two specific tyrosines on ShcA that promote ERK phosphorylation in vivo, and mice expressing ShcA with mutations of these tyrosines show impaired DN thymocyte development. This work provides the first in vivo demonstration of the relative requirement of upstream adapters in controlling ERK activation during beta selection and suggests a dominant role for ShcA.
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Affiliation(s)
- Paul Trampont
- Carter Immunology Center, MR4-4072D, Box 801386, University of Virginia, Charlottesville, VA 22908, USA
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42
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Gilfillan AM, Tkaczyk C. Integrated signalling pathways for mast-cell activation. Nat Rev Immunol 2006; 6:218-30. [PMID: 16470226 DOI: 10.1038/nri1782] [Citation(s) in RCA: 705] [Impact Index Per Article: 39.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Mast-cell activation mediated by the high-affinity receptor for IgE (FcepsilonRI) is considered to be a key event in the allergic inflammatory response. However, in a physiological setting, other receptors, such as KIT, might also markedly influence the release of mediators by mast cells. Recent studies have provided evidence that FcepsilonRI-dependent degranulation is regulated by two complementary signalling pathways, one of which activates phospholipase Cgamma and the other of which activates phosphatidylinositol 3-kinase, using specific transmembrane and cytosolic adaptor molecules. In this Review, we discuss the evidence for these interacting pathways and describe how the capacity of KIT, and other receptors, to influence FcepsilonRI-dependent mast-cell-mediator release might be a function of the relative abilities of these receptors to activate these alternative pathways.
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Affiliation(s)
- Alasdair M Gilfillan
- Laboratory of Allergic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Building 10, Room 11C206, 10 Center Drive, MSC 1881, Bethesda, Maryland 20892-1881, USA.
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43
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Abstract
Dynamic protein-protein interactions are involved in most physiological processes and, in particular, for the formation of multiprotein signaling complexes at transmembrane receptors, adapter proteins and effector molecules. Because the unregulated induction of signaling complexes has substantial clinical relevance, the investigation of these complexes is an active area of research. These studies strive to answer questions about the composition and function of multiprotein signaling complexes, along with the molecular mechanisms of their formation. In this review, the adapter protein, linker for activation of T cells (LAT), will be employed as a model to exemplify how signaling complexes are characterized using a range of techniques. The intensive investigation of LAT highlights how the systematic use of complementary techniques leads to an integrated understanding of the formation, composition and function of multiprotein signaling complexes that occur at receptors, adapter proteins and effector molecules.
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Affiliation(s)
- Jon C D Houtman
- Laboratory of Cellular and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
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44
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Houtman JCD, Houghtling RA, Barda-Saad M, Toda Y, Samelson LE. Early phosphorylation kinetics of proteins involved in proximal TCR-mediated signaling pathways. THE JOURNAL OF IMMUNOLOGY 2005; 175:2449-58. [PMID: 16081816 PMCID: PMC1414060 DOI: 10.4049/jimmunol.175.4.2449] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Activation of T cells via the stimulation of the TCR plays a central role in the adaptive immunological response. Although much is known about TCR-stimulated signaling pathways, there are still gaps in our knowledge about the kinetics and sequence of events during early activation and about the in vivo specificity of kinases involved in these proximal signaling pathways. This information is important not only for understanding the activation of signaling pathways important for T cell function but also for the development of drug targets and computer-based molecular models. In this study, phospho-specific Abs directed toward individual sites on signaling proteins were used to investigate the early phosphorylation kinetics of proteins involved in proximal TCR-induced pathways. These studies indicate that linker for activation of T cells' tyrosines have substantially different phosphorylation kinetics and that Src homology 2 domain-containing leukocyte protein of 76 kDa has rapid, transient phosphorylation kinetics compared to other proteins. In additions, we provide evidence that ZAP-70 is the primary in vivo kinase for LAT tyrosine 191 and that Itk plays a role in the phosphorylation of tyrosine 783 on phospholipase C-gamma1. In total, these studies give new insight into the sequence, kinetics and specificity of early TCR-mediated signaling events that are vital for T cell activation.
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Affiliation(s)
- Jon C D Houtman
- Laboratory of Cellular and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
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45
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Arévalo JC, Pereira DB, Yano H, Teng KK, Chao MV. Identification of a switch in neurotrophin signaling by selective tyrosine phosphorylation. J Biol Chem 2005; 281:1001-7. [PMID: 16284401 DOI: 10.1074/jbc.m504163200] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Neurotrophins, such as nerve growth factor and brain-derived neurotrophic factor, activate Trk receptor tyrosine kinases through receptor dimerization at the cell surface followed by autophosphorylation and recruitment of intracellular signaling molecules. The intracellular pathways used by neurotrophins share many common protein substrates that are used by other receptor tyrosine kinases (RTK), such as Shc, Grb2, FRS2, and phospholipase C-gamma. Here we describe a novel RTK mechanism that involves a 220-kilodalton membrane tetraspanning protein, ARMS/Kidins220, which is rapidly tyrosine phosphorylated in primary neurons after neurotrophin treatment. ARMS/Kidins220 undergoes multiple tyrosine phosphorylation events and also serine phosphorylation by protein kinase D. We have identified a single tyrosine (Tyr(1096)) phosphorylation event in ARMS/Kidins220 that plays a critical role in neurotrophin signaling. A reassembled complex of ARMS/Kidins220 and CrkL, an upstream component of the C3G-Rap1-MAP kinase cascade, is SH3-dependent. However, Tyr(1096) phosphorylation enables ARMS/Kidins220 to recruit CrkL through its SH2 domain, thereby freeing the CrkL SH3 domain to engage C3G for MAP kinase activation in a neurotrophin dependent manner. Accordingly, mutation of Tyr(1096) abolished CrkL interaction and sustained MAPK kinase activity, a response that is not normally observed in other RTKs. Therefore, Trk receptor signaling involves an inducible switch mechanism through an unconventional substrate that distinguishes neurotrophin action from other growth factor receptors.
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Affiliation(s)
- Juan Carlos Arévalo
- Molecular Neurobiology Program, Skirball Institute of Biomolecular Medicine, Department of Cell Biology, New York University School of Medicine, NY 10016, USA
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46
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Meiri KF. Lipid rafts and regulation of the cytoskeleton during T cell activation. Philos Trans R Soc Lond B Biol Sci 2005; 360:1663-72. [PMID: 16147530 PMCID: PMC1569545 DOI: 10.1098/rstb.2005.1704] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The ability of polarized cells to initiate and sustain directional responses to extracellular signals is critically dependent on direct communication between spatially organized signalling modules in the membrane and the underlying cytoskeleton. Pioneering work in T cells has shown that the assembly of signalling modules critically depends on the functional compartmentalization of membrane lipids into ordered microdomains or lipid rafts. The significance of rafts in T cell activation lies not only in their ability to recruit the signalling partners that eventually assemble into a mature immunological synapse but also in their ability to regulate actin dynamics and recruit cytoskeletal associated proteins, thereby achieving the structural polarization underlying stability of the synapse-a critical prerequisite for activation to be sustained. Lipid rafts vary quite considerably in size and visualizing the smallest of them in vivo has been challenging. Nonetheless it is now been shown quite convincingly that a surprisingly large proportion-in the order of 50%-of external membrane lipids (chiefly cholesterol and glycosphingolipids) can be dynamically localized in these liquid ordered rafts. Complementary inner leaflet rafts are less well characterized, but contain phosphoinositides as an important functional component that is crucial for regulating the behaviour of the actin cytoskeleton. This paper provides an overview of the interdependency between signalling and cytoskeletal polarization, and in particular considers how regulation of the cytoskeleton plays a crucial role in the consolidation of rafts and their stabilization into the immunological synapse.
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Affiliation(s)
- Karina F Meiri
- Department of Anatomy and Cellular Biology , Tufts University School of Medicine, Boston, MA 02111, USA.
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47
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Abstract
A plethora of genes involved in murine B and T cell development have been identified, and developmental pathways within the primary lymphoid tissues have been well delineated. The generation of a functional, but non-self reacting lymphocyte repertoire results from the completion of several checkpoints during lymphocyte development and competition for survival factors in the periphery. Improved knowledge of these developmental checkpoints and homeostatic mechanisms is critical for understanding human immunodeficiency, leukaemia/lymphoma and autoimmunity, which are conditions where checkpoints and homeostasis are likely to be deregulated.
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Affiliation(s)
- Lisa A Miosge
- Immunogenomics Laboratory, Division of Immunology and Genetics, John Curtin School of Medical Research, Australian National University, Canberra, Australia
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48
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Hayes SM, Li L, Love PE. TCR Signal Strength Influences αβ/γδ Lineage Fate. Immunity 2005; 22:583-93. [PMID: 15894276 DOI: 10.1016/j.immuni.2005.03.014] [Citation(s) in RCA: 211] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2004] [Revised: 03/16/2005] [Accepted: 03/28/2005] [Indexed: 10/25/2022]
Abstract
Signals transduced by T cell antigen receptors (TCRs) have been shown to be critical for alphabeta and gammadelta T cell development, but their role in lineage determination remains poorly defined. Two models have been forwarded for alphabeta/gammadelta lineage choice: the instructive model and the stochastic model. Recent data, however, are inconsistent with either model. In this study, we devised an experimental system in which lineage fate was controlled exclusively by the gammadeltaTCR. We then analyzed the impact of TCR signal strength on alphabeta/gammadelta lineage development by altering the surface expression or signaling potential of the gammadeltaTCR complex. We found that increasing the gammadeltaTCR signal strength favored gammadelta lineage development, whereas weakening the gammadeltaTCR signal favored alphabeta lineage development. These results support a model in which the strength of the TCR signal is a critical determinant in the lineage fate decision.
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MESH Headings
- Animals
- Base Sequence
- Cell Differentiation/immunology
- DNA, Complementary/genetics
- Humans
- In Vitro Techniques
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Mice, Transgenic
- Models, Immunological
- Receptors, Antigen, T-Cell, alpha-beta/deficiency
- Receptors, Antigen, T-Cell, alpha-beta/genetics
- Receptors, Antigen, T-Cell, alpha-beta/metabolism
- Receptors, Antigen, T-Cell, gamma-delta/deficiency
- Receptors, Antigen, T-Cell, gamma-delta/genetics
- Receptors, Antigen, T-Cell, gamma-delta/metabolism
- Recombinant Proteins/genetics
- Recombinant Proteins/metabolism
- Signal Transduction
- T-Lymphocyte Subsets/cytology
- T-Lymphocyte Subsets/immunology
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Affiliation(s)
- Sandra M Hayes
- Laboratory of Mammalian Genes and Development, National Institute of Child Health and Human Development/NIH, Bethesda, MD 20892, USA
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49
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Sommers CL, Lee J, Steiner KL, Gurson JM, Depersis CL, El-Khoury D, Fuller CL, Shores EW, Love PE, Samelson LE. Mutation of the phospholipase C-gamma1-binding site of LAT affects both positive and negative thymocyte selection. ACTA ACUST UNITED AC 2005; 201:1125-34. [PMID: 15795236 PMCID: PMC1538971 DOI: 10.1084/jem.20041869] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Linker for activation of T cells (LAT) is a scaffolding adaptor protein that is critical for T cell development and function. A mutation of LAT (Y136F) that disrupts phospholipase C-γ1 activation and subsequent calcium influx causes a partial block in T cell development and leads to a severe lymphoproliferative disease in homozygous knock-in mice. One possible contribution to the fatal disease of LAT Y136F knock-in mice could be from autoreactive T cells generated in these mice because of altered thymocyte selection. To examine the impact of the LAT Y136F mutation on thymocyte positive and negative selection, we bred this mutation onto the HY T cell receptor (TCR) transgenic, recombination activating gene-2 knockout background. Female mice with this genotype showed a severe defect in positive selection, whereas male mice exhibited a phenotype resembling positive selection (i.e., development and survival of CD8hi HY TCR-specific T cells) instead of negative selection. These results support the hypothesis that in non-TCR transgenic, LAT Y136F knock-in mice, altered thymocyte selection leads to the survival and proliferation of autoreactive T cells that would otherwise be negatively selected in the thymus.
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Affiliation(s)
- Connie L Sommers
- Laboratory of Cellular and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
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50
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Su YW, Herzog S, Lotz M, Feldhahn N, Müschen M, Jumaa H. The molecular requirements for LAT-mediated differentiation and the role of LAT in limiting pre-B cell expansion. Eur J Immunol 2005; 34:3614-22. [PMID: 15549729 DOI: 10.1002/eji.200425445] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Successful recombination of the heavy-chain locus in developing B cells results in the expression of the pre-BCR, which induces the proliferation and expansion of pre-B cells. To avoid uncontrolled proliferation, pre-BCR signals transmitted via the adaptor protein SLP-65 (SH2-domain-containing leukocyte protein of 65 kDa) lead to the down-regulation of pre-BCR expression and to pre-B cell differentiation. Here, we show that, similarly to SLP-65, the adaptor protein LAT (linker for activation of T cells) limits pre-B cell proliferation and reduces the potential of a tumorgenic pre-B cell line to develop leukemia in immune-deficient mice. We further show that the four distal tyrosines are required for LAT activity in pre-B cells. Mutation at Y136 completely abolishes LAT activity, whereas single point-mutations at Y175, Y195 or Y235 impair, but do not block, LAT-induced pre-B cell differentiation. As LAT is also expressed in human pre-B cells, our results suggest that LAT cooperates with SLP-65 to promote the differentiation and control the proliferation of both murine and human pre-B cells.
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Affiliation(s)
- Yu-Wen Su
- Institute for Biology III, Albert-Ludwigs University of Freiburg and Max Planck Institute for Immunobiology, Freiburg, Germany
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