1
|
Schwarz JJ, Grundmann L, Kokot T, Kläsener K, Fotteler S, Medgyesi D, Köhn M, Reth M, Warscheid B. Quantitative proteomics identifies PTP1B as modulator of B cell antigen receptor signaling. Life Sci Alliance 2021; 4:4/11/e202101084. [PMID: 34526379 PMCID: PMC8473724 DOI: 10.26508/lsa.202101084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 08/28/2021] [Accepted: 09/01/2021] [Indexed: 11/24/2022] Open
Abstract
This study analyses the function of the protein tyrosine phosphatase 1B identifying its binding partners and dephosphorylation targets for modulating B cell antigen receptor signaling. B cell antigen receptor (BCR) signaling is initiated by protein kinases and limited by counteracting phosphatases that currently are less well studied in their regulation of BCR signaling. Here, we used the B cell line Ramos to identify and quantify human B cell signaling components. Specifically, a protein tyrosine phosphatase profiling revealed a high expression of the protein tyrosine phosphatase 1B (PTP1B) in Ramos and human naïve B cells. The loss of PTP1B leads to increased B cell activation. Through substrate trapping in combination with quantitative mass spectrometry, we identified 22 putative substrates or interactors of PTP1B. We validated Igα, CD22, PLCγ1/2, CBL, BCAP, and APLP2 as specific substrates of PTP1B in Ramos B cells. The tyrosine kinase BTK and the two adaptor proteins GRB2 and VAV1 were identified as direct binding partners and potential substrates of PTP1B. We showed that PTP1B dephosphorylates the inhibitory receptor protein CD22 at phosphotyrosine 807. We conclude that PTP1B negatively modulates BCR signaling by dephosphorylating distinct phosphotyrosines in B cell-specific receptor proteins and various downstream signaling components.
Collapse
Affiliation(s)
- Jennifer J Schwarz
- Biochemistry and Functional Proteomics, Institute of Biology II, Faculty of Biology, University of Freiburg, Freiburg, Germany.,Spemann Graduate School of Biology and Medicine (SGBM), University of Freiburg, Freiburg, Germany
| | - Lorenz Grundmann
- Biochemistry and Functional Proteomics, Institute of Biology II, Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Thomas Kokot
- Integrative Signalling Research, Institute of Biology III, Faculty of Biology, University of Freiburg, Freiburg, Germany.,Signalling Research Centres BIOSS and CIBSS, University of Freiburg, Freiburg, Germany
| | - Kathrin Kläsener
- Department for Molecular Immunology, Institute of Biology III, Faculty of Biology, University of Freiburg, Freiburg, Germany.,Signalling Research Centres BIOSS and CIBSS, University of Freiburg, Freiburg, Germany
| | - Sandra Fotteler
- Biochemistry and Functional Proteomics, Institute of Biology II, Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - David Medgyesi
- Department for Molecular Immunology, Institute of Biology III, Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Maja Köhn
- Integrative Signalling Research, Institute of Biology III, Faculty of Biology, University of Freiburg, Freiburg, Germany.,Signalling Research Centres BIOSS and CIBSS, University of Freiburg, Freiburg, Germany.,Spemann Graduate School of Biology and Medicine (SGBM), University of Freiburg, Freiburg, Germany
| | - Michael Reth
- Department for Molecular Immunology, Institute of Biology III, Faculty of Biology, University of Freiburg, Freiburg, Germany.,Signalling Research Centres BIOSS and CIBSS, University of Freiburg, Freiburg, Germany.,Spemann Graduate School of Biology and Medicine (SGBM), University of Freiburg, Freiburg, Germany
| | - Bettina Warscheid
- Biochemistry and Functional Proteomics, Institute of Biology II, Faculty of Biology, University of Freiburg, Freiburg, Germany .,Signalling Research Centres BIOSS and CIBSS, University of Freiburg, Freiburg, Germany.,Spemann Graduate School of Biology and Medicine (SGBM), University of Freiburg, Freiburg, Germany
| |
Collapse
|
2
|
Ho CH, Cheng CH, Huang TW, Peng SY, Lee KM, Cheng PC. Switched phenotypes of macrophages during the different stages of Schistosoma japonicum infection influenced the subsequent trends of immune responses. JOURNAL OF MICROBIOLOGY, IMMUNOLOGY, AND INFECTION = WEI MIAN YU GAN RAN ZA ZHI 2021; 55:503-526. [PMID: 34330662 DOI: 10.1016/j.jmii.2021.06.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 05/28/2021] [Accepted: 06/24/2021] [Indexed: 10/20/2022]
Abstract
BACKGROUND Macrophages play crucial roles in immune responses during the course of schistosomal infections. METHODS We currently investigated influence of immunocompetent changes in macrophages via microarray-based analysis, mRNA expression analysis, detection of serum cytokines, and subsequent evaluation of the immune phenotypes following the differentiation of infection-induced lymphocytes in a unique T1/T2 double-transgenic mouse model. RESULTS The gradual upregulation of genes encoding YM1, YM2, and interleukin (IL)-4/IL-13 receptors in infected mice indicated the role of type 2 alternatively activated macrophages (M2, AAMφs) in immune responses after Schistosoma japonicum egg production. FACS analysis showed that surface markers MHC class II (IA/IE) and CD8α+ of the macrophages also exhibited a dramatic change at the various time points before and after egg-production. The transgenic mouse experiments further demonstrated that the shifting of macrophage phenotypes influenced the percentage of helper T (Th)-2 cells, which was observed to be higher than that of Th1 cells, which increased only at 3 and 5 weeks post-infection. The differentiation of effector B cells showed a similar but more significant trend toward type-2 immunity. CONCLUSION These results suggest that the infection of mice with S. japonicum resulted in a final Th2- and Be2-skewed immune response. This may be due to phenotypic changes in the macrophages. The influence of alternatively activated macrophages was also activated by S. japonicum egg production. This study elucidated the existence of variations in immune mechanisms at the schistosome infection stages.
Collapse
Affiliation(s)
- Chen-Hsun Ho
- Division of Urology, Department of Surgery, Shin Kong Wu Ho-Su Memorial Hospital, Taipei, Taiwan; School of Medicine, College of Medicine, Fu Jen Catholic University, New Taipei City, Taiwan
| | - Chia-Hsiung Cheng
- Department of Biochemistry and Molecular Cell Biology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan
| | - Tzu-Wen Huang
- Department of Microbiology and Immunology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan
| | - Shih-Yi Peng
- Department of Biochemistry, College of Medicine, Tzu Chi University, Hualien, Taiwan.
| | - Kin-Mu Lee
- School of Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Po-Ching Cheng
- Department of Molecular Parasitology and Tropical Diseases, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan; Center for International Tropical Medicine, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan.
| |
Collapse
|
3
|
Halova I, Bambouskova M, Draberova L, Bugajev V, Draber P. The transmembrane adaptor protein NTAL limits mast cell chemotaxis toward prostaglandin E2. Sci Signal 2018; 11:11/556/eaao4354. [DOI: 10.1126/scisignal.aao4354] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Chemotaxis of mast cells is one of the crucial steps in their development and function. Non–T cell activation linker (NTAL) is a transmembrane adaptor protein that inhibits the activation of mast cells and B cells in a phosphorylation-dependent manner. Here, we studied the role of NTAL in the migration of mouse mast cells stimulated by prostaglandin E2 (PGE2). Although PGE2 does not induce the tyrosine phosphorylation of NTAL, unlike IgE immune complex antigens, we found that loss of NTAL increased the chemotaxis of mast cells toward PGE2. Stimulation of mast cells that lacked NTAL with PGE2 enhanced the phosphorylation of AKT and the production of phosphatidylinositol 3,4,5-trisphosphate. In resting NTAL-deficient mast cells, phosphorylation of an inhibitory threonine in ERM family proteins accompanied increased activation of β1-containing integrins, which are features often associated with increased invasiveness in tumors. Rescue experiments indicated that only full-length, wild-type NTAL restored the chemotaxis of NTAL-deficient cells toward PGE2. Together, these data suggest that NTAL is a key inhibitor of mast cell chemotaxis toward PGE2, which may act through the RHOA/ERM/β1-integrin and PI3K/AKT axes.
Collapse
|
4
|
Knackmuss U, Lindner SE, Aneichyk T, Kotkamp B, Knust Z, Villunger A, Herzog S. MAP3K11 is a tumor suppressor targeted by the oncomiR miR-125b in early B cells. Cell Death Differ 2016; 23:242-52. [PMID: 26138442 PMCID: PMC4678593 DOI: 10.1038/cdd.2015.87] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Revised: 05/05/2015] [Accepted: 05/22/2015] [Indexed: 12/19/2022] Open
Abstract
MicroRNAs (miRNAs) are a class of small, non-coding RNAs that posttranscriptionally regulate gene expression and thereby control most, if not all, biological processes. Aberrant miRNA expression has been linked to a variety of human diseases including cancer, but the underlying molecular mechanism often remains unclear. Here we have screened a miRNA expression library in a growth factor-dependent mouse pre-B-cell system to identify miRNAs with oncogenic activity. We show that miR-125b is sufficient to render pre-B cells growth factor independent and demonstrate that continuous expression of miR-125b is necessary to keep these cells in a transformed state. Mechanistically, we find that the expression of miR-125b protects against apoptosis induced by growth factor withdrawal, and that it blocks the differentiation of pre-B to immature B cells. In consequence, miR-125b-transformed cells maintain expression of their pre-B-cell receptor that provides signals for continuous proliferation and survival even in the absence of growth factor. Employing microarray analysis, we identified numerous targets of miR-125b, but only reconstitution of MAP3K11, a critical regulator of mitogen- and stress-activated kinase signaling, interferes with the cellular fitness of the transformed cells. Together, this indicates that MAP3K11 might function as an important tumor suppressor neutralized by oncomiR-125b in B-cell leukemia.
Collapse
Affiliation(s)
- U Knackmuss
- Centre for Biological Signalling Studies (bioss), Albert-Ludwigs-University Freiburg, Freiburg, Germany
| | - S E Lindner
- Division of Developmental Immunology, Biocenter Innsbruck, Medical University of Innsbruck, Innsbruck, Austria
| | - T Aneichyk
- Division of Molecular Pathophysiology, Biocenter Innsbruck, Medical University of Innsbruck, Innsbruck, Austria
| | - B Kotkamp
- Centre for Biological Signalling Studies (bioss), Albert-Ludwigs-University Freiburg, Freiburg, Germany
| | - Z Knust
- Centre for Biological Signalling Studies (bioss), Albert-Ludwigs-University Freiburg, Freiburg, Germany
| | - A Villunger
- Division of Developmental Immunology, Biocenter Innsbruck, Medical University of Innsbruck, Innsbruck, Austria
| | - S Herzog
- Centre for Biological Signalling Studies (bioss), Albert-Ludwigs-University Freiburg, Freiburg, Germany
- Division of Developmental Immunology, Biocenter Innsbruck, Medical University of Innsbruck, Innsbruck, Austria
| |
Collapse
|
5
|
Maus M, Medgyesi D, Kiss E, Schneider AE, Enyedi A, Szilágyi N, Matkó J, Sármay G. B cell receptor-induced Ca2+ mobilization mediates F-actin rearrangements and is indispensable for adhesion and spreading of B lymphocytes. J Leukoc Biol 2013; 93:537-47. [PMID: 23362305 DOI: 10.1189/jlb.0312169] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
B cells acquire membrane-bound cognate antigens from the surface of the APCs by forming an IS, similar to that seen in T cells. Recognition of membrane-bound antigens on the APCs initiates adhesion of B lymphocytes to the antigen-tethered surface, which is followed by the formation of radial lamellipodia-like structures, a process known as B cell spreading. The spreading response requires the rearrangement of the submembrane actin cytoskeleton and is regulated mainly via signals transmitted by the BCR. Here, we show that cytoplasmic calcium is a regulator of actin cytoskeleton dynamics in B lymphocytes. We find that BCR-induced calcium mobilization is indispensible for adhesion and spreading of B cells and that PLCγ and CRAC-mediated calcium mobilization are critical regulators of these processes. Measuring calcium and actin dynamics in live cells, we found that a generation of actin-based membrane protrusion is strongly linked to the dynamics of a cytoplasmic-free calcium level. Finally, we demonstrate that PLCγ and CRAC channels regulate the activity of actin-severing protein cofilin, linking BCR-induced calcium signaling to the actin dynamics.
Collapse
Affiliation(s)
- Máté Maus
- Eötvös Lóránd University, Pázmány Péter sétány 1/c, Budapest, Hungary
| | | | | | | | | | | | | | | |
Collapse
|
6
|
Zhu M, Fuller DM, Ou-Yang CW, Sullivan SA, Zhang W. Tyrosine phosphorylation-independent regulation of lipopolysaccharide-mediated response by the transmembrane adaptor protein LAB. THE JOURNAL OF IMMUNOLOGY 2012; 188:2733-41. [PMID: 22308309 DOI: 10.4049/jimmunol.1101581] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Linker for activation of B cells (LAB)/non-T cell activation linker is a transmembrane adaptor protein that functions in immunoreceptor-mediated signaling. Published studies have shown that LAB has both positive and negative roles in regulating TCR and high-affinity Fc receptor-mediated signaling and cellular function. In this study, we showed that LAB was also expressed in dendritic cells and that LAB deficiency affected LPS-mediated signaling and cytokine production. LPS-mediated MAPK activation was enhanced in LAB(-/-) bone marrow-derived dendritic cells. These bone marrow-derived dendritic cells also produced more TNF-α, IL-6, and IL-10 than wild-type cells. Moreover, LAB(-/-) mice were hyperresponsive to LPS-induced septic shock. These data indicated that LAB has a negative role in LPS-mediated responses. By using LAB knockin mice, which harbor mutations at five membrane-distal tyrosines, we further showed that, in contrast to its role in immunoreceptor-mediated signaling, LAB function in LPS-mediated signaling pathway did not depend on its tyrosine phosphorylation. Our study suggested a novel mechanism by which LAB functions in the regulation of innate immunity.
Collapse
Affiliation(s)
- Minghua Zhu
- Department of Immunology, Duke University Medical Center, Durham, NC 27710, USA
| | | | | | | | | |
Collapse
|
7
|
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]
|
8
|
Orr SJ, McVicar DW. LAB/NTAL/Lat2: a force to be reckoned with in all leukocytes? J Leukoc Biol 2010; 89:11-9. [PMID: 20643813 DOI: 10.1189/jlb.0410221] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
LAB/NTAL/Lat2 is a transmembrane adaptor protein closely related to LAT. It is expressed in various myeloid and lymphoid cells, many of which also express LAT. Phosphorylation of LAB occurs following engagement of various ITAM- and non-ITAM-linked receptors and can play positive and negative roles following receptor engagement. LAT binds PLCγ directly, resulting in efficient Ca²+ flux and degranulation. However, LAB does not contain a PLCγ-binding motif and only binds PLCγ indirectly, possibly via Grb2, thereby resulting in suboptimal signaling. As LAT can signal more efficiently than LAB, competition between the 2 for space/substrates in the lipid rafts can attenuate signaling. This competition model requires coexpression of LAT; however, LAB is repressive, even in cells lacking substantial LAT expression such as macrophages and mature B cells. The reported interaction between LAB and the ubiquitin E3-ligase c-Cbl suggests 1 possible mechanism for LAT-independent inhibition by LAB, but such a model requires further investigation. Given the wide-reaching expression pattern of LAB, LAB has the ability to modulate signaling in virtually every type of leukocyte. Regardless of its ultimate mode of action, the potent regulatory capability of LAB proves this protein to be a complex adaptor that warrants continued, substantial scrutiny by biochemists and immunologists alike.
Collapse
Affiliation(s)
- Selinda J Orr
- Cancer and Inflammation Program, National Cancer Institute-Frederick, Frederick, MD 21702, USA
| | | |
Collapse
|
9
|
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.
Collapse
Affiliation(s)
- Deirdre M Fuller
- Department of Immunology, Duke University Medical Center, Durham, NC 27710, USA
| | | |
Collapse
|
10
|
Infantino S, Benz B, Waldmann T, Jung M, Schneider R, Reth M. Arginine methylation of the B cell antigen receptor promotes differentiation. J Exp Med 2010; 207:711-9. [PMID: 20231378 PMCID: PMC2856019 DOI: 10.1084/jem.20091303] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2009] [Accepted: 02/11/2010] [Indexed: 12/22/2022] Open
Abstract
Signals processed through the B cell antigen receptor (BCR) control both the proliferation and differentiation of B lymphocytes. How these different signaling modes are established at the BCR is poorly understood. We show that a conserved arginine in the tail sequence of the Igalpha subunit of the BCR is methylated by the protein arginine methyltransferase 1. This modification negatively regulates the calcium and PI-3 kinase pathways of the BCR while promoting signals leading to B cell differentiation. Thus, Igalpha arginine methylation can play an important role in specifying the outcome of BCR signaling.
Collapse
MESH Headings
- Amino Acid Sequence
- Animals
- Arginine/genetics
- Arginine/metabolism
- B-Lymphocyte Subsets/immunology
- B-Lymphocyte Subsets/metabolism
- B-Lymphocyte Subsets/transplantation
- B-Lymphocytes/cytology
- B-Lymphocytes/immunology
- B-Lymphocytes/metabolism
- B-Lymphocytes/transplantation
- Bone Marrow Cells/cytology
- Bone Marrow Cells/immunology
- CD79 Antigens/genetics
- CD79 Antigens/metabolism
- Calcium Signaling/immunology
- Cell Differentiation/drug effects
- Cell Differentiation/immunology
- Cell Line
- Humans
- Interleukin-7/pharmacology
- Intracellular Signaling Peptides and Proteins/metabolism
- Lymphocyte Activation/physiology
- Methylation
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Mice, Transgenic
- Molecular Sequence Data
- Nitrohydroxyiodophenylacetate/immunology
- Phosphorylation/immunology
- Precursor Cells, B-Lymphoid/cytology
- Precursor Cells, B-Lymphoid/drug effects
- Precursor Cells, B-Lymphoid/metabolism
- Protein Binding/immunology
- Protein-Arginine N-Methyltransferases/antagonists & inhibitors
- Protein-Arginine N-Methyltransferases/genetics
- Protein-Arginine N-Methyltransferases/metabolism
- Protein-Tyrosine Kinases/metabolism
- Proto-Oncogene Proteins c-akt/metabolism
- RNA, Small Interfering/genetics
- Receptors, Antigen, B-Cell/genetics
- Receptors, Antigen, B-Cell/metabolism
- Sequence Homology, Amino Acid
- Spleen/cytology
- Spleen/immunology
- Syk Kinase
- Transfection
Collapse
Affiliation(s)
- Simona Infantino
- Center for Biological Signaling Studies, Faculty of Biology and Institute of Pharmaceutical Sciences, Albert-Ludwigs-University of Freiburg, 79104 Freiburg, Germany
- Max-Planck-Institute for Immunobiology, 79108 Freiburg, Germany
| | - Beate Benz
- Center for Biological Signaling Studies, Faculty of Biology and Institute of Pharmaceutical Sciences, Albert-Ludwigs-University of Freiburg, 79104 Freiburg, Germany
- Max-Planck-Institute for Immunobiology, 79108 Freiburg, Germany
| | - Tanja Waldmann
- Max-Planck-Institute for Immunobiology, 79108 Freiburg, Germany
| | - Manfred Jung
- Center for Biological Signaling Studies, Faculty of Biology and Institute of Pharmaceutical Sciences, Albert-Ludwigs-University of Freiburg, 79104 Freiburg, Germany
| | | | - Michael Reth
- Center for Biological Signaling Studies, Faculty of Biology and Institute of Pharmaceutical Sciences, Albert-Ludwigs-University of Freiburg, 79104 Freiburg, Germany
- Max-Planck-Institute for Immunobiology, 79108 Freiburg, Germany
| |
Collapse
|
11
|
Svojgr K, Burjanivova T, Vaskova M, Kalina T, Stary J, Trka J, Zuna J. Adaptor molecules expression in normal lymphopoiesis and in childhood leukemia. Immunol Lett 2009; 122:185-92. [DOI: 10.1016/j.imlet.2008.12.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2008] [Accepted: 12/23/2008] [Indexed: 01/12/2023]
|
12
|
Kulathu Y, Hobeika E, Turchinovich G, Reth M. The kinase Syk as an adaptor controlling sustained calcium signalling and B-cell development. EMBO J 2008; 27:1333-44. [PMID: 18369315 DOI: 10.1038/emboj.2008.62] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2007] [Accepted: 03/03/2008] [Indexed: 12/13/2022] Open
Abstract
Upon B-cell antigen receptor (BCR) activation, the protein tyrosine kinase Syk phosphorylates the adaptor protein SH2 domain-containing leukocyte protein of 65 kDa (SLP-65), thus coupling the BCR to diverse signalling pathways. Here, we report that SLP-65 is not only a downstream target and substrate of Syk but also a direct binding-partner and activator of this kinase. This positive feedback is mediated by the binding of the SH2 domain of SLP-65 to an autophosphorylated tyrosine of Syk. The mutant B cells that cannot form the Syk/SLP-65 complex are defective in BCR-induced extracellular signal-regulated kinase, nuclear factor kappa B and nuclear factor of activated T cells, but not Akt activation, and are blocked in B-cell development. Furthermore, we show that formation of the Syk/SLP-65 complex is required for sustained Ca(2+) responses in activated B cells. We suggest that after activation and internalization of the BCR, Syk remains active as part of a membrane-bound Syk/SLP-65 complex controlling sustained signalling and calcium influx.
Collapse
Affiliation(s)
- Yogesh Kulathu
- Faculty of Biology, Max-Planck Institute for Immunobiology, University of Freiburg, Freiburg, Germany
| | | | | | | |
Collapse
|