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Holloway J, Seeley A, Cobbe N, Turkington RC, Longley DB, Evergren E. The E3 ubiquitin ligase Itch regulates death receptor and cholesterol trafficking to affect TRAIL-mediated apoptosis. Cell Death Dis 2024; 15:40. [PMID: 38216558 PMCID: PMC10786908 DOI: 10.1038/s41419-023-06417-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2023] [Revised: 12/15/2023] [Accepted: 12/22/2023] [Indexed: 01/14/2024]
Abstract
The activation of apoptosis signalling by TRAIL (TNF-related apoptosis-inducing ligand) through receptor binding is a fundamental mechanism of cell death induction and is often perturbed in cancer cells to enhance their cell survival and treatment resistance. Ubiquitination plays an important role in the regulation of TRAIL-mediated apoptosis, and here we investigate the role of the E3 ubiquitin ligase Itch in TRAIL-mediated apoptosis in oesophageal cancer cells. Knockdown of Itch expression results in resistance to TRAIL-induced apoptosis, caspase-8 activation, Bid cleavage and also promotes cisplatin resistance. Whilst the assembly of the death-inducing signalling complex (DISC) at the plasma membrane is not perturbed relative to the control, TRAIL-R2 is mis-localised in the Itch-knockdown cells. Further, we observe significant changes to mitochondrial morphology alongside an increased cholesterol content. Mitochondrial cholesterol is recognised as an important anti-apoptotic agent in cancer. Cells treated with a drug that increases mitochondrial cholesterol levels, U18666A, shows a protection from TRAIL-induced apoptosis, reduced caspase-8 activation, Bid cleavage and cisplatin resistance. We demonstrate that Itch knockdown cells are less sensitive to a Bcl-2 inhibitor, show impaired activation of Bax, cytochrome c release and an enhanced stability of the cholesterol transfer protein STARD1. We identify a novel protein complex composed of Itch, the mitochondrial protein VDAC2 and STARD1. We propose a mechanism where Itch regulates the stability of STARD1. An increase in STARD1 expression enhances cholesterol import to mitochondria, which inhibits Bax activation and cytochrome c release. Many cancer types display high mitochondrial cholesterol levels, and oesophageal adenocarcinoma tumours show a correlation between chemotherapy resistance and STARD1 expression which is supported by our findings. This establishes an important role for Itch in regulation of extrinsic and intrinsic apoptosis, mitochondrial cholesterol levels and provides insight to mechanisms that contribute to TRAIL, Bcl-2 inhibitor and cisplatin resistance in cancer cells.
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Affiliation(s)
- James Holloway
- Patrick G Johnston Centre for Cancer Research, Queen's University Belfast, 97 Lisburn Road, BT9 7AE, Belfast, UK
| | - Aidan Seeley
- Patrick G Johnston Centre for Cancer Research, Queen's University Belfast, 97 Lisburn Road, BT9 7AE, Belfast, UK
| | - Neville Cobbe
- Patrick G Johnston Centre for Cancer Research, Queen's University Belfast, 97 Lisburn Road, BT9 7AE, Belfast, UK
| | - Richard C Turkington
- Patrick G Johnston Centre for Cancer Research, Queen's University Belfast, 97 Lisburn Road, BT9 7AE, Belfast, UK
| | - Daniel B Longley
- Patrick G Johnston Centre for Cancer Research, Queen's University Belfast, 97 Lisburn Road, BT9 7AE, Belfast, UK
| | - Emma Evergren
- Patrick G Johnston Centre for Cancer Research, Queen's University Belfast, 97 Lisburn Road, BT9 7AE, Belfast, UK.
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2
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Kan Y, Paung Y, Seeliger MA, Miller WT. Domain Architecture of the Nonreceptor Tyrosine Kinase Ack1. Cells 2023; 12:900. [PMID: 36980241 PMCID: PMC10047419 DOI: 10.3390/cells12060900] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 03/09/2023] [Accepted: 03/13/2023] [Indexed: 03/17/2023] Open
Abstract
The nonreceptor tyrosine kinase (NRTK) Ack1 comprises a distinct arrangement of non-catalytic modules. Its SH3 domain has a C-terminal to the kinase domain (SH1), in contrast to the typical SH3-SH2-SH1 layout in NRTKs. The Ack1 is the only protein that shares a region of high homology to the tumor suppressor protein Mig6, a modulator of EGFR. The vertebrate Acks make up the only tyrosine kinase (TK) family known to carry a UBA domain. The GTPase binding and SAM domains are also uncommon in the NRTKs. In addition to being a downstream effector of receptor tyrosine kinases (RTKs) and integrins, Ack1 can act as an epigenetic regulator, modulate the degradation of the epidermal growth factor receptor (EGFR), confer drug resistance, and mediate the progression of hormone-sensitive tumors. In this review, we discuss the domain architecture of Ack1 in relation to other protein kinases that possess such defined regulatory domains.
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Affiliation(s)
- Yagmur Kan
- Department of Physiology and Biophysics, School of Medicine, Stony Brook University, Stony Brook, NY 11794-8661, USA
| | - YiTing Paung
- Department of Pharmacology, School of Medicine, Stony Brook University, Stony Brook, NY 11794-8661, USA
| | - Markus A. Seeliger
- Department of Pharmacology, School of Medicine, Stony Brook University, Stony Brook, NY 11794-8661, USA
| | - W. Todd Miller
- Department of Physiology and Biophysics, School of Medicine, Stony Brook University, Stony Brook, NY 11794-8661, USA
- Department of Veterans Affairs Medical Center, Northport, NY 11768-2200, USA
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3
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Yang F, Lin J, Chen W. Post-translational modifications in T cells in systemic erythematosus lupus. Rheumatology (Oxford) 2021; 60:2502-2516. [PMID: 33512488 DOI: 10.1093/rheumatology/keab095] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Revised: 01/21/2021] [Accepted: 01/23/2021] [Indexed: 02/07/2023] Open
Abstract
Systemic erythematosus lupus (SLE) is a classic autoimmune disease characterized by multiple autoantibodies and immune-mediated tissue damage. The aetiology of this disease is still unclear. A new drug, belimumab, which acts against the B-lymphocyte stimulator (BLyS), can effectively improve the condition of SLE patients, but it cannot resolve all SLE symptoms. The discovery of novel, precise therapeutic targets is urgently needed. It is well known that abnormal T-cell function is one of the most crucial factors contributing to the pathogenesis of SLE. Protein post-translational modifications (PTMs), including phosphorylation, glycosylation, acetylation, methylation, ubiquitination and SUMOylation have been emphasized for their roles in activating protein activity, maintaining structural stability, regulating protein-protein interactions and mediating signalling pathways, in addition to other biological functions. Summarizing the latest data in this area, this review focuses on the potential roles of diverse PTMs in regulating T-cell function and signalling pathways in SLE pathogenesis, with the goal of identifying new targets for SLE therapy.
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Affiliation(s)
- Fan Yang
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, National Clinical Research Center for Infectious Diseases, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, Zhejiang, China
| | - Jin Lin
- Division of Rheumatology, the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Weiqian Chen
- Division of Rheumatology, the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
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Dong X, Luo Z, Liu T, Chai J, Ke Q, Shen L. Identification of Integrin β1 as a Novel PAG1-Interacting Protein Involved in the Inherent Radioresistance of Human Laryngeal Carcinoma. J Cancer 2018; 9:4128-4138. [PMID: 30519312 PMCID: PMC6277618 DOI: 10.7150/jca.26885] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Accepted: 08/19/2018] [Indexed: 12/22/2022] Open
Abstract
Inherent radioresistance plays a crucial role in the failure of radiotherapy. Using the inherent radioresistant (Hep-2max) and radiosensitive (Hep-2min) cell lines established from the parental cell line Hep-2, we previously reported that phosphoprotein associated with glycosphingolipid-enriched microdomains 1(PAG1) overexpression in laryngeal carcinoma cells was correlated with inherent radioresistant phenotypes. However, the underlying mechanisms of this effect remain unknown. In the present study, we performed a proteomic screen to investigate the interactome of PAG1 in Hep-2max cells resulting in the identification of several interaction partners. Bioinformatic analysis and immunofluorescence experiments indicated the integrin β1 to be a crucial interaction partner of PAG1. PAG1 was also highly expressed in laryngeal carcinoma radioresistant tissues and showed co-localization with integrin β1. In addition, we demonstrated that integrin β1's binding to PAG1 could be interrupted by MβCD, an inhibitor of lipid rafts formation. Moreover, knockdown of integrin β1 by RNA interference sensitized radioresistant cells to irradiation. Importantly, we identified 2 potential interaction sites (Pro216-Arg232 and Asn356-Gly377) in the cytoplasmic domain of PAG1 using high throughput peptide arrays. Taken together, these results suggest that the binding of PAG1 to integrin β1 in lipid rafts is essential for inherent radioresistance of human laryngeal carcinoma.
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Affiliation(s)
- Xiaoxia Dong
- Department of pharmacology, School of Basic Medical Sciences, Hubei University of Medicine, Shiyan, Hubei 442000, P.R. China
| | - Zhiguo Luo
- Department of Clinical Oncology, Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei 442000, P.R. China
| | - Tiantian Liu
- Department of Clinical Oncology, Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei 442000, P.R. China
| | - Jingjing Chai
- Department of Clinical Oncology, Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei 442000, P.R. China
| | - Qing Ke
- Department of Clinical Oncology, Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei 442000, P.R. China
| | - Li Shen
- Department of Clinical Oncology, Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei 442000, P.R. China
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5
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Li W, Xu L, Che X, Li H, Zhang Y, Song N, Wen T, Hou K, Yang Y, Zhou L, Xin X, Xu L, Zeng X, Shi S, Liu Y, Qu X, Teng Y. C-Cbl reverses HER2-mediated tamoxifen resistance in human breast cancer cells. BMC Cancer 2018; 18:507. [PMID: 29720121 PMCID: PMC5930956 DOI: 10.1186/s12885-018-4387-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Accepted: 04/17/2018] [Indexed: 01/12/2023] Open
Abstract
Background Tamoxifen is a frontline therapy for estrogen receptor (ER)-positive breast cancer in premenopausal women. However, many patients develop resistance to tamoxifen, and the mechanism underlying tamoxifen resistance is not well understood. Here we examined whether ER-c-Src-HER2 complex formation is involved in tamoxifen resistance. Methods MTT and colony formation assays were used to measure cell viability and proliferation. Western blot was used to detect protein expression and protein complex formations were detected by immunoprecipitation and immunofluorescence. SiRNA was used to examine the function of HER2 in of BT474 cells. An in vivo xenograft animal model was established to examine the role of c-Cbl in tumor growth. Results MTT and colony formation assay showed that BT474 cells are resistant to tamoxifen and T47D cells are sensitive to tamoxifen. Immunoprecipitation experiments revealed ER-c-Src-HER2 complex formation in BT474 cells but not in T47D cells. However, ER-c-Src-HER2 complex formation was detected after overexpressing HER2 in T47D cells and these cells were more resistant to tamoxifen. HER2 knockdown by siRNA in BT474 cells reduced ER-c-Src-HER2 complex formation and reversed tamoxifen resistance. ER-c-Src-HER2 complex formation was also disrupted and tamoxifen resistance was reversed in BT474 cells by the c-Src inhibitor PP2 and HER2 antibody trastuzumab. Nystatin, a lipid raft inhibitor, reduced ER-c-Src-HER2 complex formation and partially reversed tamoxifen resistance. ER-c-Src-HER2 complex formation was disrupted by overexpression of c-Cbl but not by the c-Cbl ubiquitin ligase mutant. In addition, c-Cbl could reverse tamoxifen resistance in BT474 cells, but the ubiquitin ligase mutant had no effect. The effect of c-Cbl was validated in BT474 tumor-bearing nude mice in vivo. Immunofluorescence also revealed ER-c-Src-HER2 complex formation was reduced in tumor tissues of nude mice with c-Cbl overexpression. Conclusions Our results suggested that c-Cbl can reverse tamoxifen resistance in HER2-overexpressing breast cancer cells by inhibiting the formation of the ER-c-Src-HER2 complex. Electronic supplementary material The online version of this article (10.1186/s12885-018-4387-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Wei Li
- Department of Medical Oncology, the First Hospital of China Medical University, Shenyang, 110001, Liaoning, China.,Key Laboratory of Anticancer Drugs and Biotherapy of Liaoning Province, the First Hospital of China Medical University, NO. 155, North Nanjing Street, Heping District, Shenyang, 110001, Liaoning, China
| | - Ling Xu
- Department of Medical Oncology, the First Hospital of China Medical University, Shenyang, 110001, Liaoning, China.,Key Laboratory of Anticancer Drugs and Biotherapy of Liaoning Province, the First Hospital of China Medical University, NO. 155, North Nanjing Street, Heping District, Shenyang, 110001, Liaoning, China
| | - Xiaofang Che
- Department of Medical Oncology, the First Hospital of China Medical University, Shenyang, 110001, Liaoning, China.,Key Laboratory of Anticancer Drugs and Biotherapy of Liaoning Province, the First Hospital of China Medical University, NO. 155, North Nanjing Street, Heping District, Shenyang, 110001, Liaoning, China
| | - Haizhou Li
- Jinzhou Center Hospital, Jinzhou, 121000, Liaoning, China
| | - Ye Zhang
- Department of Medical Oncology, the First Hospital of China Medical University, Shenyang, 110001, Liaoning, China.,Key Laboratory of Anticancer Drugs and Biotherapy of Liaoning Province, the First Hospital of China Medical University, NO. 155, North Nanjing Street, Heping District, Shenyang, 110001, Liaoning, China
| | - Na Song
- Department of Medical Oncology, the First Hospital of China Medical University, Shenyang, 110001, Liaoning, China.,Key Laboratory of Anticancer Drugs and Biotherapy of Liaoning Province, the First Hospital of China Medical University, NO. 155, North Nanjing Street, Heping District, Shenyang, 110001, Liaoning, China
| | - Ti Wen
- Department of Medical Oncology, the First Hospital of China Medical University, Shenyang, 110001, Liaoning, China.,Key Laboratory of Anticancer Drugs and Biotherapy of Liaoning Province, the First Hospital of China Medical University, NO. 155, North Nanjing Street, Heping District, Shenyang, 110001, Liaoning, China
| | - Kezuo Hou
- Department of Medical Oncology, the First Hospital of China Medical University, Shenyang, 110001, Liaoning, China.,Key Laboratory of Anticancer Drugs and Biotherapy of Liaoning Province, the First Hospital of China Medical University, NO. 155, North Nanjing Street, Heping District, Shenyang, 110001, Liaoning, China
| | - Yi Yang
- Laboratory Animal Center, China Medical University, Shenyang, 110001, Liaoning, China
| | - Lu Zhou
- Department of Medical Oncology, the First Hospital of China Medical University, Shenyang, 110001, Liaoning, China.,Key Laboratory of Anticancer Drugs and Biotherapy of Liaoning Province, the First Hospital of China Medical University, NO. 155, North Nanjing Street, Heping District, Shenyang, 110001, Liaoning, China
| | - Xing Xin
- Department of Medical Oncology, the First Hospital of China Medical University, Shenyang, 110001, Liaoning, China.,Key Laboratory of Anticancer Drugs and Biotherapy of Liaoning Province, the First Hospital of China Medical University, NO. 155, North Nanjing Street, Heping District, Shenyang, 110001, Liaoning, China
| | - Lu Xu
- Department of Medical Oncology, the First Hospital of China Medical University, Shenyang, 110001, Liaoning, China.,Key Laboratory of Anticancer Drugs and Biotherapy of Liaoning Province, the First Hospital of China Medical University, NO. 155, North Nanjing Street, Heping District, Shenyang, 110001, Liaoning, China
| | - Xue Zeng
- Department of Medical Oncology, the First Hospital of China Medical University, Shenyang, 110001, Liaoning, China.,Key Laboratory of Anticancer Drugs and Biotherapy of Liaoning Province, the First Hospital of China Medical University, NO. 155, North Nanjing Street, Heping District, Shenyang, 110001, Liaoning, China
| | - Sha Shi
- Department of Medical Oncology, the First Hospital of China Medical University, Shenyang, 110001, Liaoning, China.,Key Laboratory of Anticancer Drugs and Biotherapy of Liaoning Province, the First Hospital of China Medical University, NO. 155, North Nanjing Street, Heping District, Shenyang, 110001, Liaoning, China
| | - Yunpeng Liu
- Department of Medical Oncology, the First Hospital of China Medical University, Shenyang, 110001, Liaoning, China.,Key Laboratory of Anticancer Drugs and Biotherapy of Liaoning Province, the First Hospital of China Medical University, NO. 155, North Nanjing Street, Heping District, Shenyang, 110001, Liaoning, China
| | - Xiujuan Qu
- Department of Medical Oncology, the First Hospital of China Medical University, Shenyang, 110001, Liaoning, China. .,Key Laboratory of Anticancer Drugs and Biotherapy of Liaoning Province, the First Hospital of China Medical University, NO. 155, North Nanjing Street, Heping District, Shenyang, 110001, Liaoning, China.
| | - Yuee Teng
- Department of Medical Oncology, the First Hospital of China Medical University, Shenyang, 110001, Liaoning, China. .,Key Laboratory of Anticancer Drugs and Biotherapy of Liaoning Province, the First Hospital of China Medical University, NO. 155, North Nanjing Street, Heping District, Shenyang, 110001, Liaoning, China.
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6
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Schatzlmaier P, Supper V, Göschl L, Zwirzitz A, Eckerstorfer P, Ellmeier W, Huppa JB, Stockinger H. Rapid multiplex analysis of lipid raft components with single-cell resolution. Sci Signal 2015; 8:rs11. [PMID: 26396269 DOI: 10.1126/scisignal.aac5584] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Lipid rafts, a distinct class of highly dynamic cell membrane microdomains, are integral to cell homeostasis, differentiation, and signaling. However, their quantitative examination is challenging when working with rare cells, developmentally heterogeneous cell populations, or molecules that only associate weakly with lipid rafts. We present a fast biochemical method, which is based on lipid raft components associating with the nucleus upon partial lysis during centrifugation through nonionic detergent. Requiring little starting material or effort, our protocol enabled the multidimensional flow cytometric quantitation of raft-resident proteins with single-cell resolution, thereby assessing the membrane components from a few cells in complex cell populations, as well as their dynamics resulting from cell signaling, differentiation, or genetic mutation.
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Affiliation(s)
- Philipp Schatzlmaier
- Institute for Hygiene and Applied Immunology, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Lazarettgasse 19, A-1090 Vienna, Austria
| | - Verena Supper
- Institute for Hygiene and Applied Immunology, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Lazarettgasse 19, A-1090 Vienna, Austria
| | - Lisa Göschl
- Institute of Immunology, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Lazarettgasse 19, A-1090 Vienna, Austria. Division of Rheumatology, Department of Internal Medicine III, Medical University of Vienna, Währinger Gürtel 18-20, A-1090 Vienna, Austria
| | - Alexander Zwirzitz
- Institute for Hygiene and Applied Immunology, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Lazarettgasse 19, A-1090 Vienna, Austria
| | - Paul Eckerstorfer
- Institute for Hygiene and Applied Immunology, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Lazarettgasse 19, A-1090 Vienna, Austria
| | - Wilfried Ellmeier
- Institute of Immunology, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Lazarettgasse 19, A-1090 Vienna, Austria
| | - Johannes B Huppa
- Institute for Hygiene and Applied Immunology, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Lazarettgasse 19, A-1090 Vienna, Austria.
| | - Hannes Stockinger
- Institute for Hygiene and Applied Immunology, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Lazarettgasse 19, A-1090 Vienna, Austria.
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7
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Lim HC, Multhaupt HAB, Couchman JR. Cell surface heparan sulfate proteoglycans control adhesion and invasion of breast carcinoma cells. Mol Cancer 2015; 14:15. [PMID: 25623282 PMCID: PMC4326193 DOI: 10.1186/s12943-014-0279-8] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Accepted: 12/22/2014] [Indexed: 12/31/2022] Open
Abstract
Background Cell surface proteoglycans interact with numerous regulators of cell behavior through their glycosaminoglycan chains. The syndecan family of transmembrane proteoglycans are virtually ubiquitous cell surface receptors that are implicated in the progression of some tumors, including breast carcinoma. This may derive from their regulation of cell adhesion, but roles for specific syndecans are unresolved. Methods The MDA-MB231 human breast carcinoma cell line was exposed to exogenous glycosaminoglycans and changes in cell behavior monitored by western blotting, immunocytochemistry, invasion and collagen degradation assays. Selected receptors including PAR-1 and syndecans were depleted by siRNA treatments to assess cell morphology and behavior. Immunohistochemistry for syndecan-2 and its interacting partner, caveolin-2 was performed on human breast tumor tissue arrays. Two-tailed paired t-test and one-way ANOVA with Tukey’s post-hoc test were used in the analysis of data. Results MDA-MB231 cells were shown to be highly sensitive to exogenous heparan sulfate or heparin, promoting increased spreading, focal adhesion and adherens junction formation with concomitantly reduced invasion and matrix degradation. The molecular basis for this effect was revealed to have two components. First, thrombin inhibition contributed to enhanced cell adhesion and reduced invasion. Second, a specific loss of cell surface syndecan-2 was noted. The ensuing junction formation was dependent on syndecan-4, whose role in promoting actin cytoskeletal organization is known. Syndecan-2 interacts with, and may regulate, caveolin-2. Depletion of either molecule had the same adhesion-promoting influence, along with reduced invasion, confirming a role for this complex in maintaining the invasive phenotype of mammary carcinoma cells. Finally, both syndecan-2 and caveolin-2 were upregulated in tissue arrays from breast cancer patients compared to normal mammary tissue. Moreover their expression levels were correlated in triple negative breast cancers. Conclusion Cell surface proteoglycans, notably syndecan-2, may be important regulators of breast carcinoma progression through regulation of cytoskeleton, cell adhesion and invasion.
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Affiliation(s)
- Hooi Ching Lim
- Department of Biomedical Sciences and Biotech Research & Innovation Center, University of Copenhagen, Biocenter, Ole Maaløes Vej 5, 2200, Copenhagen N, Denmark. .,Current address: Stem Cell Center, Lund University, Lund, Sweden.
| | - Hinke A B Multhaupt
- Department of Biomedical Sciences and Biotech Research & Innovation Center, University of Copenhagen, Biocenter, Ole Maaløes Vej 5, 2200, Copenhagen N, Denmark.
| | - John R Couchman
- Department of Biomedical Sciences and Biotech Research & Innovation Center, University of Copenhagen, Biocenter, Ole Maaløes Vej 5, 2200, Copenhagen N, Denmark.
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8
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Protein tyrosine phosphatase PTPN3 inhibits lung cancer cell proliferation and migration by promoting EGFR endocytic degradation. Oncogene 2014; 34:3791-803. [DOI: 10.1038/onc.2014.312] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Revised: 07/26/2014] [Accepted: 08/16/2014] [Indexed: 12/12/2022]
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Abstract
Tyrosine phosphorylation is one of the key covalent modifications that occur in multicellular organisms. Since its discovery more than 30 years ago, tyrosine phosphorylation has come to be understood as a fundamentally important mechanism of signal transduction and regulation in all eukaryotic cells. The tyrosine kinase Lck (lymphocyte-specific protein tyrosine kinase) plays a crucial role in the T-cell response by transducing early activation signals triggered by TCR (T-cell receptor) engagement. These signals result in the phosphorylation of immunoreceptor tyrosine-based activation motifs present within the cytosolic tails of the TCR-associated CD3 subunits that, once phosphorylated, serve as scaffolds for the assembly of a large supramolecular signalling complex responsible for T-cell activation. The existence of membrane nano- or micro-domains or rafts as specialized platforms for protein transport and cell signalling has been proposed. The present review discusses the signals that target Lck to membrane rafts and the importance of these specialized membranes in the transport of Lck to the plasma membrane, the regulation of Lck activity and the phosphorylation of the TCR.
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10
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OUYANG WEN, YANG CHUNXU, ZHANG SIMIN, LIU YU, YANG BO, ZHANG JUNHONG, ZHOU FUXIANG, ZHOU YUNFENG, XIE CONGHUA. Absence of death receptor translocation into lipid rafts in acquired TRAIL-resistant NSCLC cells. Int J Oncol 2012; 42:699-711. [DOI: 10.3892/ijo.2012.1748] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2012] [Accepted: 11/30/2012] [Indexed: 11/05/2022] Open
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11
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Sunzenauer S, Zojer V, Brameshuber M, Tröls A, Weghuber J, Stockinger H, Schütz GJ. Determination of binding curves via protein micropatterning in vitro and in living cells. Cytometry A 2012; 83:847-54. [PMID: 23125142 DOI: 10.1002/cyto.a.22225] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Revised: 08/23/2012] [Accepted: 10/09/2012] [Indexed: 11/11/2022]
Abstract
Quantification of protein interactions in living cells is of key relevance for understanding cellular signaling. With current techniques, however, it is difficult to determine binding affinities and stoichiometries of protein complexes in the plasma membrane. We introduce here protein micropatterning as a convenient and versatile method for such investigations. Cells are grown on surfaces containing micropatterns of capture antibody to a bait protein, so that the bait gets rearranged in the live cell plasma membrane. Upon interaction with the bait, the fluorescent prey follows the micropatterns, which can be readout with fluorescence microscopy. In this study, we addressed the interaction between Lck and CD4, two central proteins in early T-cell signaling. Binding curves were recorded using the natural fluctuations in the Lck expression levels. Surprisingly, the binding was not saturable up to the highest Lck expression levels: on average, a single CD4 molecule recruited more than nine Lck molecules. We discuss the data in view of protein- and lipid-mediated interactions.
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Affiliation(s)
- Stefan Sunzenauer
- Biophysics Institute, Johannes Kepler University Linz, A-4040 Linz, Austria
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12
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Choi YB, Son M, Park M, Shin J, Yun Y. SOCS-6 negatively regulates T cell activation through targeting p56lck to proteasomal degradation. J Biol Chem 2009; 285:7271-80. [PMID: 20007709 DOI: 10.1074/jbc.m109.073726] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The T cell-specific tyrosine kinase, p56(lck), plays crucial roles in T cell receptor (TCR)-mediated T cell activation. Here, we report that SOCS-6 (suppressor of cytokine signaling-6) is a negative regulator of p56(lck). SOCS-6 was identified as a protein binding to the kinase domain of p56(lck) through yeast two-hybrid screening. SOCS-6 bound specifically to p56(lck) (F505), which mimics the active form of p56(lck), but not to wild type p56(lck). In Jurkat T cells, SOCS-6 binding to p56(lck) was detected 1-2 h after TCR stimulation. Confocal microscopy showed that upon APC-T cell conjugation, SOCS-6 was recruited to the immunological synapse and colocalized with the active form of p56(lck). SOCS-6 promoted p56(lck) ubiquitination and its subsequent targeting to the proteasome. Moreover, SOCS-6 overexpression led to repression of TCR-dependent interleukin-2 promoter activity. These results establish that SOCS-6 acts as a negative regulator of T cell activation by promoting ubiquitin-dependent proteolysis.
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Affiliation(s)
- Young Bong Choi
- Department of Life Science, Ewha Woman's University, 120-750 Seoul, Korea
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13
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Salmond RJ, Filby A, Qureshi I, Caserta S, Zamoyska R. T-cell receptor proximal signaling via the Src-family kinases, Lck and Fyn, influences T-cell activation, differentiation, and tolerance. Immunol Rev 2009; 228:9-22. [PMID: 19290918 DOI: 10.1111/j.1600-065x.2008.00745.x] [Citation(s) in RCA: 270] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
T-cell development in the thymus and activation of mature T cells in secondary lymphoid organs requires the ability of cells to respond appropriately to environmental signals at multiple stages of their development. The process of thymocyte selection insures a functional T-cell repertoire, while activation of naive peripheral T cells induces proliferation, gain of effector function, and, ultimately, long-lived T-cell memory. The T-cell immune response is initiated upon engagement of the T-cell receptor (TCR) and coreceptor, CD4 or CD8, by cognate antigen/major histocompatibility complexes presented by antigen-presenting cells. TCR/coreceptor engagement induces the activation of biochemical signaling pathways that, in combination with signals from costimulator molecules and cytokine receptors, direct the outcome of the response. Activation of the src-family kinases p56(lck) (Lck) and p59(fyn) (Fyn) is central to the initiation of TCR signaling pathways. This review focuses on our current understanding of the mechanisms by which these two proteins orchestrate T-cell function.
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Affiliation(s)
- Robert J Salmond
- Molecular Immunology, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London, UK
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14
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Xu L, Qu X, Zhang Y, Hu X, Yang X, Hou K, Teng Y, Zhang J, Sada K, Liu Y. Oxaliplatin enhances TRAIL-induced apoptosis in gastric cancer cells by CBL-regulated death receptor redistribution in lipid rafts. FEBS Lett 2009; 583:943-8. [PMID: 19223002 DOI: 10.1016/j.febslet.2009.02.014] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2008] [Revised: 02/10/2009] [Accepted: 02/10/2009] [Indexed: 11/18/2022]
Abstract
Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a member of the tumor necrosis factor family that selectively induces apoptosis in cancer cells. However, gastric cancer cells are insensitive to TRAIL. In the present study, we show that oxaliplatin enhanced TRAIL-induced apoptosis of MGC803, BGC823, and SGC7901 cells. Oxaliplatin promoted death receptor 4 (DR4) and death receptor 5 (DR5) clustering into aggregated lipid rafts, while the cholesterol-sequestering agent nystatin partially prevented lipid raft aggregation, DR4 and DR5 clustering, and reduced apoptosis. Furthermore, the expression of the casitas B-lineage lymphoma (Cbl) family was downregulated by oxaliplatin. Transfection of c-Cbl or Cbl-b partially reversed oxaliplatin-induced lipid raft aggregation. These results indicated that oxaliplatin enhanced TRAIL-induced gastric cancer cell apoptosis at least partially through Cbl-regulated death receptor redistribution in lipid rafts.
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Affiliation(s)
- Ling Xu
- Department of Medical Oncology, The First Hospital of China Medical University, Shenyang 110001, China
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15
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Abstract
The immune response to cancer has been long recognized, including both innate and adaptive responses, showing that the immune system can recognize protein products of genetic and epigenetic changes in transformed cells. The accumulation of antigen-specific T cells within the tumor, the draining lymph node, and the circulation, either in newly diagnosed patients or resultant from experimental immunotherapy, proves that tumors produce antigens and that priming occurs. Unfortunately, just as obviously, tumors grow, implying that anti-tumor immune responses are either not sufficiently vigorous to eliminate the cancer or that anti-tumor immunity is suppressed. Both possibilities are supported by current data. In experimental animal models of cancer and also in patients, systemic immunity is usually not dramatically suppressed, because tumor-bearing animals and patients develop T-cell-dependent immune responses to microbes and to either model antigens or experimental cancer vaccines. However, inhibition of specific anti-tumor immunity is common, and several possible explanations of tolerance to tumor antigens or tumor-induced immunesuppression have been proposed. Inhibition of effective anti-tumor immunity results from the tumor or the host response to tumor growth, inhibiting the activation, differentiation, or function of anti-tumor immune cells. As a consequence, anti-tumor T cells cannot respond productively to developmental, targeting, or activation cues. While able to enhance the number and phenotype of anti-tumor T cells, the modest success of immunotherapy has shown the necessity to attempt to reverse tolerance in anti-tumor T cells, and the vanguard of experimental therapy now focuses on vaccination in combination with blockade of immunosuppressive mechanisms. This review discusses several potential mechanisms by which anti-tumor T cells may be inhibited in function.
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Affiliation(s)
- Alan B Frey
- Department of Cell Biology, New York University School of Medicine, New York, NY 10016, USA.
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16
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Chiang YJ, Jordan MS, Horai R, Schwartzberg PL, Koretzky GA, Hodes RJ. Cbl enforces an SLP76-dependent signaling pathway for T cell differentiation. J Biol Chem 2008; 284:4429-38. [PMID: 19074136 PMCID: PMC2640981 DOI: 10.1074/jbc.m808679200] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
A signaling pathway involving ZAP-70, LAT, and SLP76 has been regarded as
essential for receptor-driven T cell development and activation. Consistent
with this model, mice deficient in SLP76 have a complete block at the double
negative 3 stage of T cell development. Recently, however, it has been
reported that inactivation of Cbl, a ubiquitin-protein isopeptide ligase,
partially rescues T cell development in SLP76-deficient mice. To probe the
influence of Cbl on domain-specific SLP76 functions, we reconstituted
SLP76-/- Cbl-/- mice with Slp76 transgenes
bearing mutations in each of three functional domains of SLP76 as follows:
Y3F, in which the amino-terminal tyrosine residues of SLP76 were mutated,
eliminating sites of SLP76 interaction with Vav, Nck, and Itk; Δ20, in
which 20 amino acids in the proline-rich region of SLP76 were deleted,
removing a binding site for Gads; and RK, in which arginine 448 of SLP76 was
replaced by lysine, abolishing function of the Src homology 2 domain. Although
each of these transgenes has been shown to partially rescue T cell development
in SLP76-/- mice, we report here that Cbl inactivation completely
reverses the severe double negative 3 developmental block that occurs in
SLP76-deficient mice expressing the Y3F transgene (Y3F mice) and
partially rescues the defect in positive selection in T cell receptor
transgenic Y3F mice, but in contrast fails to rescue thymic development of
SLP76-deficient mice expressing the Δ20 or RK transgene. Rescue in
SLP76-/-Cbl-/-Y3F double-positive thymocytes is
associated with enhanced tyrosine phosphorylation of signaling molecules,
including Lck, Vav, PLC-γ1, and ERKs, but not Itk, in response to T cell
receptor stimulation. Thus, our data demonstrate that Cbl suppresses
activation of a bypass signaling pathway and thereby enforces SLP76 dependence
of early T cell development.
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Affiliation(s)
- Y Jeffrey Chiang
- Experimental Immunology Branch, NCI, and NIA, National Institutes of Health, Bethesda, Maryland 20892, USA.
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17
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Strasner AB, Natarajan M, Doman T, Key D, August A, Henderson AJ. The Src kinase Lck facilitates assembly of HIV-1 at the plasma membrane. THE JOURNAL OF IMMUNOLOGY 2008; 181:3706-13. [PMID: 18714047 DOI: 10.4049/jimmunol.181.5.3706] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
HIV type 1 (HIV-1) assembly and egress are driven by the viral protein Gag and occur at the plasma membrane in T cells. Recent evidence indicates that secretory vesicles and machinery are essential components of virus packaging in both T cells and macrophages. However, the pathways and cellular mediators of Gag targeting to the plasma membrane are not well characterized. Lck, a lymphoid specific Src kinase critical for T cell activation, is found in the plasma membrane as well as various intracellular compartments and it has been suggested to influence HIV-1 replication. To investigate Lck as a potential regulator of Gag targeting, we assessed HIV-1 replication and Gag-induced virus-like particle release in the presence and absence of Lck. Release of HIV-1 and virus-like particles was reduced in the absence of Lck. This decrease in replication was not due to altered HIV-1 infection, transcription or protein translation. However, in T cells lacking Lck, HIV-1 accumulated intracellularly. In addition, expressing Lck in HeLa cells promoted HIV-1 Gag plasma membrane localization. Palmitoylation of the Lck unique domain, which is essential for directing Lck to the plasma membrane, was critical for its effect on HIV-1 replication. Furthermore, HIV-1 Gag directly interacted with the Lck unique domain in the context of infected cells. These results indicate that Lck plays a key role in targeting HIV-1 Gag to the plasma membrane in T cells.
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Affiliation(s)
- Amy B Strasner
- Intergrated Bioscience Program in Immunobiology, Huck Institute of the Life Sciences, Pennsylvania State University, University Park, PA 16802, USA
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18
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Kang J, Kang S, Kwon HN, He W, Park S. Distinct interactions between ubiquitin and the SH3 domains involved in immune signaling. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2008; 1784:1335-41. [DOI: 10.1016/j.bbapap.2008.04.031] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2008] [Revised: 04/07/2008] [Accepted: 04/26/2008] [Indexed: 11/16/2022]
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19
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Filipp D, Moemeni B, Ferzoco A, Kathirkamathamby K, Zhang J, Ballek O, Davidson D, Veillette A, Julius M. Lck-dependent Fyn activation requires C terminus-dependent targeting of kinase-active Lck to lipid rafts. J Biol Chem 2008; 283:26409-22. [PMID: 18660530 DOI: 10.1074/jbc.m710372200] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mechanisms regulating the activation and delivery of function of Lck and Fyn are central to the generation of the most proximal signaling events emanating from the T cell antigen receptor (TcR) complex. Recent results demonstrate that lipid rafts (LR) segregate Lck and Fyn and play a fundamental role in the temporal and spatial coordination of their activation. Specifically, TcR-CD4 co-aggregation-induced Lck activation outside LR results in Lck translocation to LR where the activation of LR-resident Fyn ensues. Here we report a structure-function analysis toward characterizing the mechanism supporting Lck partitioning to LR and its capacity to activate co-localized Fyn. Using NIH 3T3 cells ectopically expressing FynT, we demonstrate that only LR-associated, kinase-active (Y505F)Lck reciprocally co-immunoprecipitates with and activates Fyn. Mutational analyses revealed a profound reduction in the formation of Lck-Fyn complexes and Fyn activation, using kinase domain mutants K273R and Y394F of (Y505F)Lck, both of which have profoundly compromised kinase activity. The only kinase-active Lck mutants tested that revealed impaired physical and enzymatic engagement with Fyn were those involving truncation of the C-terminal sequence YQPQP. Remarkably, sequential truncation of YQPQP resulted in an increasing reduction of kinase-active Lck partitioning to LR, in both fibroblasts and T cells. This in turn correlated with an ablation of the capacity of these truncates to enhance TcR-mediated interleukin-2 production. Thus, Lck-dependent Fyn activation is predicated by proximity-mediated transphosphorylation of the Fyn kinase domain, and targeting kinase-active Lck to LR is dependent on the C-terminal sequence QPQP.
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Affiliation(s)
- Dominik Filipp
- Sunnybrook Research Institute and the Department of Immunology, University of Toronto, Toronto, Ontario M4N 3M5, Canada
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20
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Xu T, Chen L, Shang X, Cui L, Luo J, Chen C, Ba X, Zeng X. Critical role of Lck in L-selectin signaling induced by sulfatides engagement. J Leukoc Biol 2008; 84:1192-201. [PMID: 18653462 DOI: 10.1189/jlb.0208084] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Recruitment of leukocytes onto inflamed tissues is an important physiological event, in which L-selectin plays an essential role in initial leukocyte capture and at the same time, triggers cell signaling. Lck is a member of the Src family of protein tyrosine kinases and is critical for T cell activation triggered by receptor ligation. Here, we demonstrated that Lck was associated directly with and phosphorylated the L-selectin cytoplasmic tail upon L-selectin engagement with sulfatides. Through the direct interaction with ZAP-70 and c-Abl via its Src homology 2 (SH2) and SH3 domains, Lck organized a signaling complex at the cytoplasmic tail of L-selectin. In the cells with Lck knockdown by small interfering RNA treatment, L-selectin signaling was suppressed dramatically, as indicated by reduced phosphorylation of c-Abl and ZAP-70. Re-expression of wild-type or constitutively active but not kinase-dead murine Lck rescued the phosphorylation completely, but the SH2 domain mutant or the SH3/SH2 double mutant of murine Lck had no effect. These results suggest that Lck plays a critical role in L-selectin signaling upon sulfatides stimulation.
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Affiliation(s)
- Ting Xu
- Northeast Normal University, Changchun, People's Republic of China
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21
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Abstract
Ubiquitylation is a fundamental mechanism of signal transduction that regulates immune responses and many other biological processes. Similar to phosphorylation, ubiquitylation is a reversible process that is counter-regulated by ubiquitylating enzymes and deubiquitylating enzymes (DUBs). Despite the identification of a large number of DUBs, our knowledge of the function and activities of this family of enzymes is just starting to accumulate. As described in this Review, recent studies of several DUBs, in particular CYLD and A20, show that deubiquitylation has an important role in the regulation of both innate and adaptive immune responses.
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Affiliation(s)
- Shao-Cong Sun
- Department of Immunology, The University of Texas MD Anderson Cancer Center, 7455 Fannin Street, BOX 902, Houston, Texas 77030, USA.
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22
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The SH3 domain of Lck modulates T-cell receptor-dependent activation of extracellular signal-regulated kinase through activation of Raf-1. Mol Cell Biol 2007; 28:630-41. [PMID: 17998336 DOI: 10.1128/mcb.00150-07] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Engagement of the T-cell antigen receptor (TCR) results in the proximal activation of the Src family tyrosine kinase Lck. The activation of Lck leads to the downstream activation of the Ras/Raf/MEK/ERK signaling pathway (where ERK is extracellular signal-related kinase). Under conditions of weak, but not strong, stimulation through the TCR, a version of Lck that contains a single point mutation in the SH3 (Src homology 3) domain (W97ALck) fails to support the activation of ERK, despite initiating signaling through the TCR, as demonstrated by the robust activation of ZAP-70, PLC-gamma, and Ras. We determined that the signaling lesion in W97ALck-expressing cells lies at the level of Raf-1 activation and is dependent on the presence of tyrosines 340/341 in the Raf-1 sequence. These data demonstrate a second function for Lck in TCR-mediated signaling to ERK. Additionally, we found that a significant fraction of Lck is localized to the Golgi apparatus and that, compared with wild-type Lck, W97ALck displays aberrant Golgi membrane localization. Our results support a model where under conditions of weak stimulation through the TCR, in addition to activated Ras, Golgi apparatus-localized Lck is needed for the full activation of Raf-1.
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23
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Sharif-Askari E, Gaucher D, Halwani R, Ma J, Jao K, Abdallah A, Haddad EK, Sékaly RP. p56Lck tyrosine kinase enhances the assembly of death-inducing signaling complex during Fas-mediated apoptosis. J Biol Chem 2007; 282:36048-56. [PMID: 17932036 DOI: 10.1074/jbc.m706007200] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Although the death-inducing signaling complex (DISC) is rapidly assembled, several lines of evidence suggest that formation of this complex is not the first consequence of cell surface CD95 (Fas) stimulation but rather a later step in this process. Activation of Fas triggers a cascade of signaling events that culminate in cellular apoptosis. Tyrosine kinases are critical effectors in T cell activation. However, their functional involvement in death receptor-mediated apoptosis is unknown. Here, we used p56(Lck)-deficient cells to show that CD95-induced cell death is highly dependent on p56(Lck) activity and its localization within plasma membrane. We found that p56(Lck) acts upstream of the mitochondria; in the absence of p56(Lck), Bid cleavage and the release of cytochrome c were severely impaired. Moreover, p56(Lck)-deficient cells or cells expressing an inactive form of p56(Lck) displayed defective formation of the DISC post CD95 stimulation. In vivo reconstitution of thymocytes from p56(lck)-deficient mice, which are resistant to apoptosis, with p56(Lck) restored Fas-mediated cell death. Our results support a novel model whereby sensitivity to apoptosis is regulated through quantitative changes in the stoichiometry of DISC components triggered by p56(Lck) activation and localization.
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Affiliation(s)
- Ehssan Sharif-Askari
- Laboratoire d'Immunologie, Centre de Recherche CHUM Saint-Luc, Montréal H2X 1P1, Canada
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24
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Hoff H, Brunner-Weinzierl MC. The tyrosine phosphatase SHP-2 regulates differentiation and apoptosis of individual primary T lymphocytes. Eur J Immunol 2007; 37:1072-86. [PMID: 17330819 DOI: 10.1002/eji.200636240] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Although phosphatases are key players of intracellular processes, not much is known about the phosphatase SHP-2 during T cell differentiation. Here we show that ectopic over-expression of SHP-2 in primary T helper cells directly reduced the frequency of individual lymphocytes expressing pro-inflammatory cytokines after antigen-specific stimulation by a mechanism impairing activation of protein kinase C. In addition we demonstrate that SHP-2 mediates enhanced migration upon CXCR4 signaling in a G-protein-dependent manner. Most strikingly, SHP-2 mediated a dramatic increase in apoptosis by highly enhanced activation of caspases. Co-immunoprecipitations of SHP-2 and c-Cbl from primary T helper cells demonstrated that SHP-2 strongly interacts with the ubiquitin ligase c-Cbl, indicating that c-Cbl could mediate the negative signals of SHP-2. Our results show that SHP-2 signal transduction regulates central checkpoints of T cell differentiation by the activation of distinct signaling cascades.
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Affiliation(s)
- Holger Hoff
- Deutsches Rheuma-Forschungszentrum, Berlin, Germany
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25
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Ozegbe P, Chernajovsky Y, Kabouridis PS. Regulation of expression and function of Lck tyrosine kinase by high cell density. Mol Membr Biol 2006; 22:363-72. [PMID: 16154907 PMCID: PMC2596299 DOI: 10.1080/09687860500187834] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
For many types of cells, an increase in cell density leads to characteristic changes in intracellular signalling and cell function. It is unknown, however, whether cell density affects the function of T lymphocytes. It is presented here that aggregation of Jurkat T cells, murine thymocytes or human peripheral blood T cells, results in gradual modification of the Lck tyrosine kinase. Within one hour of aggregation, Lck in the detergent-insoluble lipid raft fraction is dephosphorylated mainly at the carboxy-terminal tyrosine. Further aggregation leads to gradual loss of Lck protein from both lipid raft and non-raft fractions which is accompanied by increased protein ubiquitination, a process that is more evident in the detergent-soluble fraction. In contrast, the expression of LAT, which like Lck distributes to raft and non-raft membrane, or Csk, a kinase with a structure similar to Lck, is not affected by cell aggregation. Dephosphorylation of lipid raft-associated Lck, albeit with reduced kinetics, is observed in aggregated Jurkat CD45-deficient cells as well, suggesting involvement of additional tyrosine phosphatases. Changes in Lck structure and expression correlate with reduced ability of aggregated cells to fully activate protein tyrosine phosphorylation after stimulation of the TCR, and with changes in the activation of down-stream signalling cascades.
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Affiliation(s)
- Patricia Ozegbe
- Bone & Joint Research Unit, William Harvey Research Institute, Queen Mary's School of Medicine & Dentistry, University of London, London, UK
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26
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Reiley WW, Zhang M, Jin W, Losiewicz M, Donohue KB, Norbury CC, Sun SC. Regulation of T cell development by the deubiquitinating enzyme CYLD. Nat Immunol 2006; 7:411-7. [PMID: 16501569 DOI: 10.1038/ni1315] [Citation(s) in RCA: 181] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2005] [Accepted: 01/27/2006] [Indexed: 11/09/2022]
Abstract
T cell receptor signaling is essential for the generation and maturation of T lymphocyte precursors. Here we identify the deubiquitinating enzyme CYLD as a positive regulator of proximal T cell receptor signaling in thymocytes. CYLD physically interacted with active Lck and promoted recruitment of active Lck to its substrate, Zap70. CYLD also removed both Lys 48- and Lys 63-linked polyubiquitin chains from Lck. Because of a cell-autonomous defect in T cell development, CYLD-deficient mice had substantially fewer mature CD4(+) and CD8(+) single-positive thymocytes and peripheral T cells.
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Affiliation(s)
- William W Reiley
- Department of Microbiology and Immunology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033, USA
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27
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Thien C, Langdon W. c-Cbl and Cbl-b ubiquitin ligases: substrate diversity and the negative regulation of signalling responses. Biochem J 2006; 391:153-66. [PMID: 16212556 PMCID: PMC1276912 DOI: 10.1042/bj20050892] [Citation(s) in RCA: 202] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The activation of signalling pathways by ligand engagement with transmembrane receptors is responsible for determining many aspects of cellular function and fate. While these outcomes are initially determined by the nature of the ligand and its receptor, it is also essential that intracellular enzymes, adaptor proteins and transcription factors are correctly assembled to convey the intended response. In recent years, it has become evident that proteins that regulate the amplitude and duration of these signalling responses are also critical in determining the function and fate of cells. Of these, the Cbl family of E3 ubiquitin ligases and adaptor proteins has emerged as key negative regulators of signals from many types of cell-surface receptors. The array of receptors and downstream signalling proteins that are regulated by Cbl proteins is diverse; however, in most cases, the receptors have a common link in that they either possess a tyrosine kinase domain or they form associations with cytoplasmic PTKs (protein tyrosine kinases). Thus Cbl proteins become involved in signalling responses at a time when PTKs are first activated and therefore provide an initial line of defence to ensure that signalling responses proceed at the desired intensity and duration.
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Affiliation(s)
- Christine B. F. Thien
- School of Surgery and Pathology, University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia
- Correspondence may be addressed to either author (email or )
| | - Wallace Y. Langdon
- School of Surgery and Pathology, University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia
- Correspondence may be addressed to either author (email or )
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28
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Nervi S, Guinamard R, Delaval B, Lécine P, Vialettes B, Naquet P, Imbert J. A rare mRNA variant of the human lymphocyte-specific protein tyrosine kinase LCK gene with intron B retention and exon 7 skipping encodes a putative protein with altered SH3-dependent molecular interactions. Gene 2005; 359:18-25. [PMID: 16107303 DOI: 10.1016/j.gene.2005.06.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2005] [Revised: 06/06/2005] [Accepted: 06/16/2005] [Indexed: 10/25/2022]
Abstract
A rare mRNA variant of the human lymphocyte-specific protein tyrosine kinase LCK gene that retains intron B and excludes exon 7 (B+7-) due to alternative splicing of the canonical LCK transcripts was identified and characterized. LCK B+7- mRNA is detected in all tested peripheral blood T lymphocytes total RNA samples but is apparently sequestered in the nucleus. The presence of intron B sequence does not disrupt the reading frame and results in the insertion of 58 aminoacids, containing a proline-rich region just upstream of p56lck SH3 domain. This putative isoform encodes an unstable 516 aminoacids protein (LckB+7-) which can be expressed in transfected COS-7 cells. Furthermore in Jurkat T cell extracts, a recombinant intron B plus SH3 p56lck domain fails to interact with some TCR-induced tyrosine phosphorylated polypeptides and known p56lck partners such as Sam68 and c-Cbl. The biological function of this rare messenger remains to be elucidated.
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MESH Headings
- Alternative Splicing
- Amino Acid Sequence
- Animals
- Base Sequence
- Blotting, Western
- COS Cells
- Cells, Cultured
- Chlorocebus aethiops
- Cloning, Molecular
- DNA, Complementary/chemistry
- DNA, Complementary/genetics
- Humans
- Introns/genetics
- Isoenzymes/genetics
- Isoenzymes/metabolism
- Jurkat Cells
- Lymphocyte Specific Protein Tyrosine Kinase p56(lck)/genetics
- Lymphocyte Specific Protein Tyrosine Kinase p56(lck)/metabolism
- Molecular Sequence Data
- Mutagenesis, Insertional
- Protein Binding
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Reverse Transcriptase Polymerase Chain Reaction
- Sequence Alignment
- Sequence Analysis, DNA
- Sequence Homology, Nucleic Acid
- T-Lymphocytes/cytology
- T-Lymphocytes/enzymology
- T-Lymphocytes/metabolism
- Transcription, Genetic/genetics
- src Homology Domains/genetics
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Affiliation(s)
- Solange Nervi
- Institut de Cancérologie de Marseille, UMR599 INSERM-Institut Paoli-Calmettes-Université de la Méditerranée, 27 boulevard Leï Roure, 13009 Marseille, France
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29
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Uhlin M, Masucci MG, Levitsky V. Regulation of lck degradation and refractory state in CD8+ cytotoxic T lymphocytes. Proc Natl Acad Sci U S A 2005; 102:9264-9. [PMID: 15958529 PMCID: PMC1166584 DOI: 10.1073/pnas.0406333102] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
After specific activation, CD8+ cytotoxic T lymphocytes (CTLs) enter a refractory state termed activation-induced nonresponsiveness (AINR) that is characterized by the inability of T cells to respond to a secondary stimulus. Here, we show that T cell receptor triggering results in rapid degradation of the src-family protein kinase lck through a mechanism that is proteasome- and lysosome-independent, sensitive to cysteine protease inhibitors, and distinct from the pathways involved in degradation of ZAP-70 kinase or zeta-chain of the CD3 complex. Pharmacologic blockade of lck degradation, as well as transfection of refractory cells with an lck expression vector, increased responsiveness of CTLs to repeated antigenic challenge. The development or maintenance of AINR was not affected by exogenously added IL-2, whereas IL-15 or IFN-alpha restored both lck expression and responsiveness of preactivated CTLs. Our results suggest that lck degradation plays an important role in the development of AINR in human CTLs and that this condition can be reverted by pharmacologic agents or lymphokines that prevent lck degradation or induce its expression.
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Affiliation(s)
- Michael Uhlin
- Microbiology and Tumorbiology Center, Karolinska Institutet, S-171 77 Stockholm, Sweden
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30
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Fawcett VCJ, Lorenz U. Localization of Src homology 2 domain-containing phosphatase 1 (SHP-1) to lipid rafts in T lymphocytes: functional implications and a role for the SHP-1 carboxyl terminus. THE JOURNAL OF IMMUNOLOGY 2005; 174:2849-59. [PMID: 15728495 DOI: 10.4049/jimmunol.174.5.2849] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The protein tyrosine phosphatase Src homology 2 domain-containing phosphatase 1 (SHP-1) has previously been shown to be a negative regulator of signaling mediated via the TCR. A growing body of evidence indicates that the regulated localization of proteins within certain membrane subdomains, referred to as lipid rafts, is important for the successful transduction of signaling events downstream of the TCR. However, considerably less is known about the localization of negative regulators during these lipid raft-dependent signaling events. In this study we have investigated the subcellular localization of SHP-1 and its role in regulation of TCR-mediated signaling. Our studies demonstrate that in a murine T cell hybridoma as well as in primary murine thymocytes, a fraction of SHP-1 localizes to the lipid rafts, both basally and after TCR stimulation. Interestingly, although SHP-1 localized in the nonraft fractions is tyrosine phosphorylated, the SHP-1 isolated from the lipid rafts lacks the TCR-induced tyrosine phosphorylation, suggesting physical and/or functional differences between these two subpopulations. We identify a requirement for the C-terminal residues of SHP-1 in optimal localization to the lipid rafts. Although expression of SHP-1 that localizes to lipid rafts potently inhibits TCR-mediated early signaling events and IL-2 production, the expression of lipid raft-excluded SHP-1 mutants fails to elicit any of the inhibitory effects. Taken together these studies reveal a key role for lipid raft localization of SHP-1 in mediating the inhibitory effects on T cell signaling events.
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MESH Headings
- Animals
- Antibodies, Monoclonal/metabolism
- Binding Sites, Antibody
- Cell Line
- Interleukin-2/antagonists & inhibitors
- Interleukin-2/biosynthesis
- Intracellular Signaling Peptides and Proteins
- Membrane Microdomains/enzymology
- Membrane Microdomains/genetics
- Membrane Microdomains/metabolism
- Mice
- Mice, Inbred C3H
- Mutagenesis, Site-Directed
- Peptide Fragments/genetics
- Peptide Fragments/immunology
- Peptide Fragments/metabolism
- Peptide Fragments/physiology
- Phosphorylation
- Protein Phosphatase 1
- Protein Structure, Tertiary
- Protein Tyrosine Phosphatase, Non-Receptor Type 6
- Protein Tyrosine Phosphatases/biosynthesis
- Protein Tyrosine Phosphatases/genetics
- Protein Tyrosine Phosphatases/metabolism
- Protein Tyrosine Phosphatases/physiology
- Receptor-CD3 Complex, Antigen, T-Cell/antagonists & inhibitors
- Receptor-CD3 Complex, Antigen, T-Cell/physiology
- Sequence Deletion
- Signal Transduction/immunology
- Subcellular Fractions/metabolism
- T-Lymphocytes/cytology
- T-Lymphocytes/enzymology
- Tyrosine/metabolism
- src Homology Domains/genetics
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Affiliation(s)
- Vicki C J Fawcett
- Department of Microbiology and The Beirne Carter Center for Immunology Research, University of Virginia, Charlottesville, VA 22908, USA
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31
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Gavi S, Yin D, Shumay E, Wang HY, Malbon CC. The 15-amino acid motif of the C terminus of the beta2-adrenergic receptor is sufficient to confer insulin-stimulated counterregulation to the beta1-adrenergic receptor. Endocrinology 2005; 146:450-7. [PMID: 15388645 DOI: 10.1210/en.2004-0595] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Insulin counterregulates catecholamine action in part by inducing the sequestration of beta2-adrenergic receptors. Although similar to agonist-induced sequestration, insulin-induced internalization of beta2-adrenergic receptors operates through a distinct and better-understood cellular pathway. The effects of insulin treatment on the function and trafficking of both beta1- and beta2-adrenergic receptors were tested. The beta2-adrenergic receptors were counterregulated and internalized in response to insulin. The beta1-adrenergic receptors, in sharp contrast, are shown to be resistant to the ability of insulin to counterregulate function and induce receptor internalization. Using chimeric receptors composed of beta1-/beta2-adrenergic receptors in tandem with mutagenesis, we explored the role of the C-terminal cytoplasmic tail of the beta2-adrenergic receptors for insulin-induced counterregulation. Substitution of the C-terminal cytoplasmic tail of the beta2-adrenergic receptor on the beta1-adrenergic receptor enabled the chimeric G protein-coupled receptor to be functionally and spatially regulated by insulin. Truncation of the beta2-adrenergic receptor C-terminal cytoplasmic tail to a 15-amino acid motif harboring a potential Src homology 2-binding domain at Y350 and an Akt phosphorylation site at S345,346 was sufficient to enable receptor regulation by insulin.
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Affiliation(s)
- Shai Gavi
- Department of Pharmacology, University Medical Center, State University of New York/Stony Brook, Stony Brook, New York 11794-8651, USA
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32
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Geahlen RL, Handley MD, Harrison ML. Molecular interdiction of Src-family kinase signaling in hematopoietic cells. Oncogene 2004; 23:8024-32. [PMID: 15489920 DOI: 10.1038/sj.onc.1208078] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The ability of Src-family kinases (SFKs) to mediate signaling from cell surface receptors in hematopoietic cells is a function of their catalytic activity, location and binding partners. Kinase activity is regulated in the cell by kinases and phosphatases that alter the state of phosphorylation of key tyrosine residues and by protein binding partners that stabilize the kinase in active or inactive conformations or localize the enzyme to specific subcellular or submembrane domains. Kinase activity and function can be modulated experimentally through the use of small molecule inhibitors designed to directly target catalytic or binding domains or regulate the location of the protein by altering its state of acylation.
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Affiliation(s)
- Robert L Geahlen
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN 47907, USA
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33
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Abstract
Regulation of tyrosine kinase-mediated cellular activation through antigen receptors is of great biological and practical significance. The evolutionarily conserved Cbl family ubiquitin ligases have emerged as key negative regulators of activated tyrosine kinase-coupled receptors, and their impaired function switches a normal immune response into autoimmunity. Cbl proteins facilitate the ubiquitinylation of activated tyrosine kinases and other signaling proteins and of the signaling chains of receptors themselves; monoubiquitin tag promotes sorting of activated receptors and associated proteins into internal vesicles of the multivesicular body, facilitating their lysosomal degradation, whereas polyubiquitin tag promotes proteasomal degradation. Notably, increased expression of Cbl proteins and other ubiquitin ligases is a component of anergic signaling program in T cells. Thus, controlled destruction of the signaling apparatus has emerged as a key to fine-tuning antigen receptor signaling. Further studies of this pathway are likely to elucidate the pathogenesis of autoimmune diseases and offer new therapeutic targets.
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Affiliation(s)
- Lei Duan
- Division of Molecular Oncology, Department of Medicine, Evanston Northwestern Healthcare Research Institute, Feinberg School of Medicine, Northwestern University, IL 60201, USA
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34
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Jury EC, Kabouridis PS, Flores-Borja F, Mageed RA, Isenberg DA. Altered lipid raft–associated signaling and ganglioside expression in T lymphocytes from patients with systemic lupus erythematosus. J Clin Invest 2004. [DOI: 10.1172/jci200420345] [Citation(s) in RCA: 149] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
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35
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Jury EC, Kabouridis PS, Flores-Borja F, Mageed RA, Isenberg DA. Altered lipid raft-associated signaling and ganglioside expression in T lymphocytes from patients with systemic lupus erythematosus. J Clin Invest 2004; 113:1176-87. [PMID: 15085197 PMCID: PMC385405 DOI: 10.1172/jci20345] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2003] [Accepted: 02/17/2004] [Indexed: 12/25/2022] Open
Abstract
Systemic lupus erythematosus (SLE) is characterized by abnormalities in T lymphocyte receptor-mediated signal transduction pathways. Our previous studies have established that lymphocyte-specific protein tyrosine kinase (LCK) is reduced in T lymphocytes from patients with SLE and that this reduction is associated with disease activity and parallels an increase in LCK ubiquitination independent of T cell activation. This study investigated the expression of molecules that regulate LCK homeostasis, such as CD45, C-terminal Src kinase (CSK), and c-Cbl, in lipid raft domains from SLE T cells and investigated the localization of these proteins during T cell receptor (TCR) triggering. Our results indicate that the expression of raft-associated ganglioside, GM1, is increased in T cells from SLE patients and LCK may be differentially regulated due to an alteration in the association of CD45 with lipid raft domains. CD45 tyrosine phosphatase, which regulates LCK activity, was differentially expressed and its localization into lipid rafts was increased in T cells from patients with SLE. Furthermore, T cells allowed to "rest" in vitro showed a reversal of the changes in LCK, CD45, and GM1 expression. The results also revealed that alterations in the level of GM1 expression and lipid raft occupancy cannot be induced by serum factors from patients with SLE but indicated that cell-cell contact, activating aberrant proximal signaling pathways, may be important in influencing abnormalities in T cell signaling and, therefore, function in patients with SLE.
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Affiliation(s)
- Elizabeth C Jury
- Centre for Rheumatology, Royal Free and University College Medical School, University College London, London, United Kingdom.
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36
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Abstract
In the last few years it has become clear that in cells of the immune system, specialized microdomains present in the plasma membrane, called lipid rafts, have been found to play a central role in regulating signalling by immune receptors. Recent studies have looked at whether lipid rafts may be connected to the abnormalities in signalling seen in T lymphocytes isolated from patients with systemic lupus erythematosus (SLE). These early findings show that in SLE T cells, the expression and protein composition of lipid rafts is different when compared with normal T cells. These results also demonstrate changes in the function and localization of critical signalling molecules such as the LCK tyrosine kinase and the CD45 tyrosine phosphatase.
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Affiliation(s)
- E C Jury
- Centre for Rheumatology, Royal Free and University College Medical School, London, UK.
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37
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Miura-Shimura Y, Duan L, Rao NL, Reddi AL, Shimura H, Rottapel R, Druker BJ, Tsygankov A, Band V, Band H. Cbl-mediated ubiquitinylation and negative regulation of Vav. J Biol Chem 2003; 278:38495-504. [PMID: 12881521 DOI: 10.1074/jbc.m305656200] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The Cbl ubiquitin ligase has emerged as a negative regulator of receptor and non-receptor tyrosine kinases. Cbl is known to associate with the proto-oncogene product Vav, a hematopoietic-restricted Rac guanine nucleotide exchange factor, but the consequences of this interaction remain to be elucidated. Using immortalized T cell lines from Cbl(+/+) and Cbl(-/-) mice, and transfection analyses in 293T cells, we demonstrate that Vav undergoes Cbl-dependent ubiquitinylation under conditions that promote Cbl and Vav phosphorylation. Interaction with Cbl also induced the loss of phosphorylated Vav. In addition, we show that an activated Vav mutant (Vav-Y174F) is more sensitive to Cbl-dependent ubiquitinylation. We demonstrate that the Cbl-dependent ubiquitinylation of Vav requires Cbl/Vav association through phosphorylated Tyr-700 on Cbl, and also requires an intact Cbl RING finger domain. Finally, using transfection analyses in the Jurkat T cell line, we show that Cbl, but not its ubiquitin ligase mutant, can inhibit Vav-dependent signaling. Thus, our findings strongly support the role of Cbl, via its ubiquitin ligase activity, as a negative regulator of activated Vav.
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Affiliation(s)
- Yuko Miura-Shimura
- Division of Rheumatology, Immunology and Allergy, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
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38
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Abstract
Adaptor proteins are unique, as they contain modular domains and lack intrinsic enzymatic activity. These proteins are scaffolds for the organization of macromolecular complexes and they recruit other proteins for correct localization during molecular signal transduction. Numerous recent advances have been made through the elucidation of new adaptor proteins and the recognition of novel functions for previously identified molecules. In addition, the roles of adaptors in both the positive and negative regulation of lymphocyte activation have been further clarified.
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Affiliation(s)
- Erin Janssen
- Department of Immunology, Duke University Medical Center, Durham, North Carolina 27710, USA
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39
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Jang IK, Gu H. Negative regulation of TCR signaling and T-cell activation by selective protein degradation. Curr Opin Immunol 2003; 15:315-20. [PMID: 12787757 DOI: 10.1016/s0952-7915(03)00048-7] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Protein degradation was previously considered to be a nonspecific cellular process that eradicated abnormal or damaged proteins. Current evidence indicates, however, that T cells use this mechanism to selectively eliminate activated T-cell receptors (TCRs) and signaling molecules, and consequently control the duration and specificity of TCR signaling.
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Affiliation(s)
- Ihn-Kyung Jang
- Laboratory of Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA
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40
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Jury EC, Kabouridis PS, Abba A, Mageed RA, Isenberg DA. Increased ubiquitination and reduced expression of LCK in T lymphocytes from patients with systemic lupus erythematosus. ARTHRITIS AND RHEUMATISM 2003; 48:1343-54. [PMID: 12746907 DOI: 10.1002/art.10978] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
OBJECTIVE To explore regulation of proximal signaling and composition of lipid rafts in T lymphocytes from patients with systemic lupus erythematosus (SLE). METHODS The expression, phosphorylation, and degradation of lipid raft-associated signaling molecules in T lymphocytes from 50 patients with SLE compared with 28 healthy controls and 22 rheumatoid arthritis patients were investigated. Lipid raft and nonraft fractions from T cells were isolated by ultracentrifugation. Proteins in the lipid raft and nonraft fractions were analyzed by Western blotting and probed for phosphotyrosine activity and for LCK, LAT, and CD3 epsilon. Immunoprecipitation experiments were performed to assess protein ubiquitination in T cell lysates. T cell phenotype and levels of intracellular LCK were determined by flow cytometry. RESULTS LCK, an essential signaling molecule for T cell activation, was significantly reduced in both lipid raft and nonraft fractions of T lymphocytes from patients with active SLE compared with controls, and the reduction was independent of treatment. To identify the likely causes of reduced LCK, we explored the possibility that chronic activation of T lymphocytes underlies LCK degradation. The results revealed an increase in protein ubiquitination, and specifically LCK ubiquitination, in T cells from SLE patients. However, our findings suggest that the increase in ubiquitination is independent of T cell activation. CONCLUSION LCK is reduced in T cell lipid rafts from patients with SLE. This reduction appears to be independent of activation and may be associated with abnormal ubiquitin-mediated regulation mechanisms.
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Affiliation(s)
- Elizabeth C Jury
- Royal Free and University College Medical School, University College, London, UK.
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41
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Holm K, Weclewicz K, Hewson R, Suomalainen M. Human immunodeficiency virus type 1 assembly and lipid rafts: Pr55(gag) associates with membrane domains that are largely resistant to Brij98 but sensitive to Triton X-100. J Virol 2003; 77:4805-17. [PMID: 12663787 PMCID: PMC152122 DOI: 10.1128/jvi.77.8.4805-4817.2003] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The assembly and budding of human immunodeficiency virus type 1 (HIV-1) at the plasma membrane are directed by the viral core protein Pr55(gag). We have analyzed whether Pr55(gag) has intrinsic affinity for sphingolipid- and cholesterol-enriched raft microdomains at the plasma membrane. Pr55(gag) has previously been reported to associate with Triton X-100-resistant rafts, since both intracellular membranes and virus-like Pr55(gag) particles (VLPs) yield buoyant Pr55(gag) complexes upon Triton X-100 extraction at cold temperatures, a phenotype that is usually considered to indicate association of a protein with rafts. However, we show here that the buoyant density of Triton X-100-treated Pr55(gag) complexes cannot be taken as a proof for raft association of Pr55(gag), since lipid analyses of Triton X-100-treated VLPs demonstrated that the detergent readily solubilizes the bulk of membrane lipids from Pr55(gag). However, Pr55(gag) might nevertheless be a raft-associated protein, since confocal fluorescence microscopy indicated that coalescence of GM1-positive rafts at the cell surface led to copatching of membrane-bound Pr55(gag). Furthermore, extraction of intracellular membranes or VLPs with Brij98 yielded buoyant Pr55(gag) complexes of low density. Lipid analyses of Brij98-treated VLPs suggested that a large fraction of the envelope cholesterol and phospholipids was resistant to Brij98. Collectively, these results suggest that Pr55(gag) localizes to membrane microdomains that are largely resistant to Brij98 but sensitive to Triton X-100, and these membrane domains provide the platform for assembly and budding of Pr55(gag) VLPs.
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Affiliation(s)
- Kirsi Holm
- Department of Biosciences at Novum, Karolinska Institutet, S-141 57 Huddinge, Sweden
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42
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Zamoyska R, Basson A, Filby A, Legname G, Lovatt M, Seddon B. The influence of the src-family kinases, Lck and Fyn, on T cell differentiation, survival and activation. Immunol Rev 2003; 191:107-18. [PMID: 12614355 DOI: 10.1034/j.1600-065x.2003.00015.x] [Citation(s) in RCA: 155] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The src-family kinases p56lck (Lck) and p59fyn (Fyn) are expressed in T cells and are among the first signaling molecules to be activated downstream of the T cell receptor (TCR). Evidence is emerging that although closely related, these signaling molecules have discrete functions during development, maintenance and activation of peripheral T cells. For example, during thymopoiesis Lck is uniquely able to provide all the signals required for pre-TCRbeta selection, although Fyn can substitute for a subset of these. Positive selection of CD4 single-positive (SP) cells is also critically dependent on the expression of Lck but not Fyn, while differentiation of CD8 SP cells proceeds relatively efficiently in the absence of Lck. In naïve peripheral T cells either Lck or Fyn can transmit TCR-mediated survival signals, and yet only Lck is able to trigger TCR-mediated expansion signals under conditions of lymphopenia. Stimulation of naïve T cells by antigenic stimuli is also severely compromised in the absence of Lck, but more subtly impaired by the absence of Fyn. We discuss recent experiments addressing how these two src-kinase family members interface with downstream signaling pathways to regulate these diverse aspects of T cell behavior.
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Affiliation(s)
- Rose Zamoyska
- Division of Molecular Immunology, National Institute for Medical Research, London, UK.
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