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Zander L, Bemark M. Identification of genes deregulated during serum-free medium adaptation of a Burkitt's lymphoma cell line. Cell Prolif 2008; 41:136-55. [PMID: 18211290 DOI: 10.1111/j.1365-2184.2007.00500.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
OBJECTIVE Serum is usually added to growth media when mammalian cells are cultured in vitro to supply the cells with growth factors, hormones, nutrients and trace elements. Defined proteins and metal ions, such as insulin, growth factors, transferrin and sodium selenite, are sometimes also included and can in some cases substitute serum components. How adaptation to serum free media influences cells has not been studied in detail. MATERIALS AND METHODS We have adapted the Burkitt's lymphoma line Ramos to a serum-free medium that supports long-term survival and studied gene expression changes that occurred during the adaptation process. RESULTS AND CONCLUSIONS The adaptation process was characterized by initial cell population growth arrest, and after that extensive cell death, followed by proliferation and long-term survival of clonal cultures. Proliferation and cell cycle progression of the serum-free cultures closely mimicked that of serum-dependent cells. Affymetrix micro-array technology was used to identify gene expression alterations that had occurred during the adaptation. Most changes were subtle, but frequently the genes with altered expression were involved in basal cellular functions such as cell division, cell cycle regulation, apoptosis and cell signalling. Some alterations were restored when the cells were transferred back to serum-containing medium, indicating that expression of these genes was controlled by components in serum. Others were not, and may represent changes that were selected during the adaptation process. Among these were, for example, several genes within the Wnt signalling pathway.
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Affiliation(s)
- L Zander
- Department of Microbiology and Immunology, Gothenburg University, Göteborg, Sweden
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2
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Portis T, Longnecker R. Epstein-Barr virus LMP2A interferes with global transcription factor regulation when expressed during B-lymphocyte development. J Virol 2003; 77:105-14. [PMID: 12477815 PMCID: PMC140618 DOI: 10.1128/jvi.77.1.105-114.2003] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Epstein-Barr virus (EBV) is associated with the development of malignant lymphomas and lymphoproliferative disorders in immunocompromised individuals. The LMP2A protein of EBV is thought to play a central role in this process by allowing the virus to persist in latently infected B lymphocytes. We have demonstrated that LMP2A, when expressed in B cells of transgenic mice, allows normal B-cell developmental checkpoints to be bypassed. To identify cellular genes targeted by LMP2A that are involved in this process, we have utilized DNA microarrays to compare gene transcription in B cells from wild-type versus LMP2A transgenic mice. In B cells from LMP2A transgenic mice, we observed decreased expression of many genes associated with normal B-cell development as well as reduced levels of the transcription factors that regulate their expression. In particular, expression of the transcription factor E2A was down-regulated in bone marrow and splenic B cells. Furthermore, E2A activity was inhibited in these cells as determined by decreased DNA binding and reduced expression of its target genes, including the transcription factors early B-cell factor and Pax-5. Expression of two E2A inhibitors, Id2 and SCL, was up-regulated in splenic B cells expressing LMP2A, suggesting a possible mechanism for E2A inhibition. These results indicate that LMP2A deregulates transcription factor expression and activity in developing B cells, and this likely allows for a bypass of normal signaling events required for proper B-cell development. The ability of LMP2A to interfere with B-cell transcription factor regulation has important implications regarding its role in EBV latency.
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Affiliation(s)
- Toni Portis
- Department of Microbiology and Immunology, Northwestern University, Chicago, Illinois 60611, USA
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3
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Bannish G, Fuentes-Pananá EM, Cambier JC, Pear WS, Monroe JG. Ligand-independent signaling functions for the B lymphocyte antigen receptor and their role in positive selection during B lymphopoiesis. J Exp Med 2001; 194:1583-96. [PMID: 11733573 PMCID: PMC2193524 DOI: 10.1084/jem.194.11.1583] [Citation(s) in RCA: 118] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Signal transduction through the B cell antigen receptor (BCR) is determined by a balance of positive and negative regulators. This balance is shifted by aggregation that results from binding to extracellular ligand. Aggregation of the BCR is necessary for eliciting negative selection or activation by BCR-expressing B cells. However, ligand-independent signaling through intermediate and mature forms of the BCR has been postulated to regulate B cell development and peripheral homeostasis. To address the importance of ligand-independent BCR signaling functions and their regulation during B cell development, we have designed a model that allows us to isolate the basal signaling functions of immunoglobulin (Ig)alpha/Igbeta-containing BCR complexes from those that are dependent upon ligand-mediated aggregation. In vivo, we find that basal signaling is sufficient to facilitate pro-B --> pre-B cell transition and to generate immature/mature peripheral B cells. The ability to generate basal signals and to drive developmental progression were both dependent on plasma membrane association of Igalpha/Igbeta complexes and intact immunoregulatory tyrosine activation motifs (ITAM), thereby establishing a correlation between these processes. We believe that these studies are the first to directly demonstrate biologically relevant basal signaling through the BCR where the ability to interact with both conventional as well as nonconventional extracellular ligands is eliminated.
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Affiliation(s)
- G Bannish
- University of Pennsylvania School of Medicine, Department of Pathology and Laboratory Medicine, Philadelphia, PA 19104, USA
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4
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Fruehling S, Swart R, Dolwick KM, Kremmer E, Longnecker R. Tyrosine 112 of latent membrane protein 2A is essential for protein tyrosine kinase loading and regulation of Epstein-Barr virus latency. J Virol 1998; 72:7796-806. [PMID: 9733815 PMCID: PMC110092 DOI: 10.1128/jvi.72.10.7796-7806.1998] [Citation(s) in RCA: 112] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/1998] [Accepted: 06/23/1998] [Indexed: 11/20/2022] Open
Abstract
Latent membrane protein 2A (LMP2A) of Epstein-Barr virus (EBV) is expressed on the plasma membrane of B lymphocytes latently infected with EBV and blocks B-cell receptor (BCR) signal transduction in EBV-immortalized B cells in vitro. The LMP2A amino-terminal domain that is essential for the LMP2A-mediated block on BCR signal transduction contains eight tyrosine residues. Association of Syk protein tyrosine kinase (PTK) with LMP2A occurs at the two tyrosines of the LMP2A immunoreceptor tyrosine-based activation motif, and it is hypothesized that Lyn PTK associates with the YEEA amino acid motif at LMP2A tyrosine 112 (Y112). To examine the specific association of Lyn PTK to LMP2A, a panel of LMP2A cDNA expression vectors containing LMP2A mutations were transfected into an EBV-negative B-cell line and analyzed for Lyn and LMP2A coimmunoprecipitation. Lyn associates with wild-type LMP2A and other LMP2A mutant constructs, but Lyn association is lost in the LMP2A construct containing a tyrosine (Y)-to-phenylalanine (F) mutation at LMP2A residue Y112 (LMP2AY112F). Next, the LMP2AY112F mutation was recombined into the EBV genome to generate stable lymphoblastoid cell lines (LCLs) transformed with the LMP2AY112F mutant virus. Analysis of BCR-mediated signal transduction in the LMP2AY112F LCLs revealed loss of the LMP2A-mediated block in BCR signal transduction. In addition, LMP2A was not tyrosine phosphorylated in LMP2AY112F LCLs. Together these data indicate the importance of the LMP2A Y112 residue in the ability of LMP2A to block BCR-mediated signal transduction and place the role of this residue and its interaction with Lyn PTK as essential to LMP2A phosphorylation, PTK loading, and down-modulation of PTKs involved in BCR-mediated signal transduction.
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Affiliation(s)
- S Fruehling
- Department of Microbiology-Immunology, Northwestern University Medical School, Chicago, Illinois 60611, USA
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5
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Thévenin C, Nutt SL, Busslinger M. Early function of Pax5 (BSAP) before the pre-B cell receptor stage of B lymphopoiesis. J Exp Med 1998; 188:735-44. [PMID: 9705955 PMCID: PMC2213350 DOI: 10.1084/jem.188.4.735] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The formation of the pre-B cell receptor (BCR) corresponds to an important checkpoint in B cell development that selects pro-B (pre-BI) cells expressing a functionally rearranged immunoglobulin mu (Igmu) heavy chain protein to undergo the transition to the pre-B (pre-BII) cell stage. The pre-BCR contains, in addition to Igmu, the surrogate light chains lambda5 and VpreB and the signal transducing proteins Igalpha and Igbeta. The absence of one of these pre-BCR components is known to arrest B cell development at the pre-BI cell stage. Disruption of the Pax5 gene, which codes for the B cell-specific activator protein (BSAP), also blocks adult B lymphopoiesis at the pre-BI cell stage. Moreover, expression of the mb-1 (Igalpha) gene and VH-to-DHJH recombination at the IgH locus are reduced in Pax5-deficient B lymphocytes approximately 10- and approximately 50-fold, respectively. Here we demonstrate that complementation of these deficiencies in pre-BCR components by expression of functionally rearranged Ig mu and chimeric Igmu-Igbeta transgenes fails to advance B cell development to the pre-BII cell stage in Pax5 (-/-) mice in contrast to RAG2 (-/-) mice. Furthermore, the pre-BCR is stably expressed on cultured pre-BI cells from Igmu transgenic, Pax5-deficient bone marrow, but is unable to elicit its normal signaling responses. In addition, the early developmental block is unlikely to be caused by the absence of a survival signal, as it could not be rescued by expression of a bcl2 transgene in Pax5-deficient pre-BI cells. Together, these data demonstrate that the absence of Pax5 arrests adult B lymphopoiesis at an early developmental stage that is unresponsive to pre-BCR signaling.
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Affiliation(s)
- C Thévenin
- Research Institute of Molecular Pathology, A-1030 Vienna, Austria
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6
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Kato J, Motoyama N, Taniuchi I, Takeshita H, Toyoda M, Masuda K, Watanabe T. Affinity Maturation in Lyn Kinase-Deficient Mice with Defective Germinal Center Formation. THE JOURNAL OF IMMUNOLOGY 1998. [DOI: 10.4049/jimmunol.160.10.4788] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Abstract
Lyn kinase-deficient (lyn−/−) mice show several abnormalities such as reduced numbers of circulating B cells, hyper-IgM, and low proliferative responses induced by CD40 ligand. Lyn−/− mice also develop splenomegaly, produce autoreactive Abs with age, and finally develop glomerulonephritis. Another abnormality observed in lyn−/− mice is that their disability to form germinal centers (GCs). It has been considered that GCs play an important role in affinity maturation and differentiation to B cell memory upon immunization with thymus-dependent Ag. Since Lyn kinase has been thought to be downstream of the signals from the B cell Ag receptor as well as CD40, we studied whether or not lyn−/− mice could exhibit normal Ag-specific class switching and affinity maturation following somatic hypermutation. The mice were immunized with (4-hydroxy-3-nitrophenyl)acetyl-chicken γ-globulin (NP-CG). Production of NP-specific IgG1 Abs was slightly reduced but clearly detectable. The affinity of Abs produced was comparable to that in wild-type mice. Furthermore, somatic hypermutation occurred in the heavy-chain variable region at the same level as that in wild-type mice. Therefore, we conclude that isotype switching and affinity maturation occur normally in lyn−/− mice without the formation of GCs. The results lead to a speculation that Lyn may not play a role in induction of isotype switching or affinity maturation, despite being downstream of the signals from the B cell Ag receptor complex and CD40, and that GC architecture may not be absolutely essential for affinity maturation.
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Affiliation(s)
- Jun Kato
- Department of Molecular Immunology, Medical Institute of Bioregulation, Kyushu University, Higashi-Ku, Fukuoka, Japan
| | - Noboru Motoyama
- Department of Molecular Immunology, Medical Institute of Bioregulation, Kyushu University, Higashi-Ku, Fukuoka, Japan
| | - Ichiro Taniuchi
- Department of Molecular Immunology, Medical Institute of Bioregulation, Kyushu University, Higashi-Ku, Fukuoka, Japan
| | - Hiromichi Takeshita
- Department of Molecular Immunology, Medical Institute of Bioregulation, Kyushu University, Higashi-Ku, Fukuoka, Japan
| | - Masaki Toyoda
- Department of Molecular Immunology, Medical Institute of Bioregulation, Kyushu University, Higashi-Ku, Fukuoka, Japan
| | - Keiji Masuda
- Department of Molecular Immunology, Medical Institute of Bioregulation, Kyushu University, Higashi-Ku, Fukuoka, Japan
| | - Takeshi Watanabe
- Department of Molecular Immunology, Medical Institute of Bioregulation, Kyushu University, Higashi-Ku, Fukuoka, Japan
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Yasue T, Nishizumi H, Aizawa S, Yamamoto T, Miyake K, Mizoguchi C, Uehara S, Kikuchi Y, Takatsu K. A critical role of Lyn and Fyn for B cell responses to CD38 ligation and interleukin 5. Proc Natl Acad Sci U S A 1997; 94:10307-12. [PMID: 9294206 PMCID: PMC23358 DOI: 10.1073/pnas.94.19.10307] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
CD38 ligation on mouse B cells by CS/2, an anti-mouse CD38 mAb, induced proliferation, interleukin 5 (IL-5) receptor alpha chain expression, and tyrosine phosphorylation of Bruton tyrosine kinase (Btk) from wild-type, but not from X chromosome-linked, immunodeficient mice. B cells from fyn-deficient (Fyn-/-) and lyn-deficient (Lyn-/-) mice showed an impaired response to mAb CS/2 for proliferation and IL-5 receptor alpha chain expression, and B cells from fyn/lyn double-deficient (Fyn/Lyn-/-) mice did not respond at all to mAb CS/2. The Btk activation by CD38 ligation was observed in B cells from Fyn-/- mice, and it was severely impaired in B cells from Lyn-/- and Fyn/Lyn-/- mice. CD38 expression on B cells from three mutant strains was comparable to that on control B cells. We infer from these results that both Fyn and Lyn are required and that their signals are synergistic for B cell triggering after CD38 ligation. Lyn is upstream of Btk activation in the CD38 signaling. Stimulation of B cells with IL-5 together with CD38 ligation induces not only IgM but also IgG1 secretion. Analysis of the synergistic effects of IL-5 and CD38 ligation on IgG1 secretion revealed the impaired IgG1 secretion of B cells from Lyn-/- and Fyn/Lyn-/- mice. These data imply that Lyn is involved in B cell triggering by CD38 ligation plus IL-5 for isotype switching.
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Affiliation(s)
- T Yasue
- Department of Immunology, Institute of Medical Science, University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108 Japan
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8
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Wolven A, Okamura H, Rosenblatt Y, Resh MD. Palmitoylation of p59fyn is reversible and sufficient for plasma membrane association. Mol Biol Cell 1997; 8:1159-73. [PMID: 9201723 PMCID: PMC305721 DOI: 10.1091/mbc.8.6.1159] [Citation(s) in RCA: 140] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Members of the Src family of protein tyrosine kinases are localized to subspecialized regions of the plasma membrane. Herein we show that the N-terminal SH4 region of the Src family member p59fyn (Fyn) is both necessary and sufficient for targeting of Fyn and heterologous proteins to the plasma membrane and detergent-insoluble subdomains. Attachment of the first 16 amino acids of Fyn to a normally cytosolic protein, beta-galactosidase, resulted in distinct plasma membrane localization of the chimeric protein. Mutation of the palmitoylation site (cysteine-3) within Fyn16-beta-galactosidase or wild-type Fyn abrogated plasma membrane localization, resulting in redistribution of the mutant proteins into intracellular membranes. Substitution of the SH4 motif within Fyn with heterologous sequences from other palmitoylated proteins (G alpha o and GAP43) revealed that the presence of palmitate is sufficient to direct plasma membrane localization independent of surrounding amino acid sequences and myristate. Palmitoylated Fyn chimeras were also enriched in the Triton X-100-resistant matrix, whereas nonpalmitoylated forms of these proteins were detected in the detergent-soluble fraction. The palmitate moiety on Fyn exhibited a half-life of 1.5-2 h. In contrast, the half-life of the polypeptide backbone was 8 h, indicating that palmitoylation is a reversible modification. These studies establish that the palmitoylated SH4 sequence of Fyn can be used to specifically target proteins to the plasma membrane in a reversible manner.
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Affiliation(s)
- A Wolven
- Program in Molecular Biology, Cornell University Graduate School of Medical Sciences, New York, New York 10021, USA
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9
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Bewarder N, Weinrich V, Budde P, Hartmann D, Flaswinkel H, Reth M, Frey J. In vivo and in vitro specificity of protein tyrosine kinases for immunoglobulin G receptor (FcgammaRII) phosphorylation. Mol Cell Biol 1996; 16:4735-43. [PMID: 8756631 PMCID: PMC231474 DOI: 10.1128/mcb.16.9.4735] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Human B cells express four immunoglobulin G receptors, FcgammaRIIa, FcgammaRIIb1, FcgammaRIIb2, and FcgammaRIIc. Coligation of either FcgammaRII isoform with the B-cell antigen receptor (BCR) results in the abrogation of B-cell activation, but only the FcgammaRIIa/c and FcgammaIIb1 isoforms become phosphorylated. To identify the FcgammaRII-phosphorylating protein tyrosine kinase (PTK), we used the combination of an in vitro and an in vivo approach. In an in vitro assay using recombinant cytoplasmic tails of the different FcgammaRII isoforms as well as tyrosine exchange mutants, we show that each of the BCR-associated PTKs (Lyn, Blk, Fyn, and Syk) shows different phosphorylation patterns with regard to the different FcgammaR isoforms and point mutants. While each PTK phosphorylated FcgammaRIIa/c, FcgammaRIIb1 was phosphorylated by Lyn and Blk whereas FcgammaRIIb2 became phosphorylated only by Blk. Mutants lacking both tyrosine residues of the immune receptor tyrosine-based activation motif (ITAM) of FcgammaRIIa/c were not phosphorylated by Blk and Fyn, while Lyn-mediated phosphorylation was dependent on the presence of the C-terminal tyrosine of the ITAM. Results obtained in assays using an FcgammaR- B-cell line transfected with wild-type or mutated FcgammaRIIa demonstrated that exchange of the C-terminal tyrosine of the ITAM of FcgammaRIIa/c was sufficient to abolish FcgammaRIIa/c phosphorylation in B cells. Additionally, we could show that Lyn and Fyn bind to FcgammaRIIa/c, with the ITAM being necessary for association. Comparison of the phosphorylation pattern of each PTK observed in vitro with the phosphorylation pattern observed in vivo suggests that Lyn is the most likely candidate for FcgammaRIIa/c and FcgammaRIIb1 phosphorylation in vivo.
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Affiliation(s)
- N Bewarder
- Biochemie II, Fakultät für Chemie, Universität Bielefeld, Germany
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10
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Norvell A, Birkeland ML, Carman J, Sillman AL, Wechsler-Reva R, Monroe JG. Use of isolated immature-stage B cells to understand negative selection and tolerance induction at the molecular level. Immunol Res 1996; 15:191-207. [PMID: 8902576 DOI: 10.1007/bf02918249] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Encounter with antigen by newly developing antigen receptor-positive B cells leads to negative selection. This process positions the B cell antigen receptor (BCR) in a central role for initiating the process of negative selection and suggests developmental regulation of its signaling. The observation that immature B cells are more susceptible to negative selection than are mature B cells has been demonstrated in a number of in vitro and in vivo model systems and support the idea of developmental regulation of BCR-initiated responses. Since identical antigen receptors are expressed on immature and mature B cells, the critical fate-determining distinction between these developmental stages must lie downstream of the receptor-ligand interaction itself, in the form of different BCR-linked signaling processes or with different secondary events occurring subsequent to BCR cross-linking. To address the first possibility, our laboratory and others have sought to define the differences in BCR-mediated signal transduction in immature and mature B lymphocytes. In this review article we will discuss current in vitro systems to study this question in primary, nontransformed murine B lymphocytes. In addition, we will discuss our previously published work in order to illustrate how these model systems have been useful in beginning to unravel the molecular basis for immune B cell negative selection and tolerance.
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Affiliation(s)
- A Norvell
- Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia 19104, USA
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11
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Wang J, Koizumi T, Watanabe T. Altered antigen receptor signaling and impaired Fas-mediated apoptosis of B cells in Lyn-deficient mice. J Exp Med 1996; 184:831-8. [PMID: 9064343 PMCID: PMC2192791 DOI: 10.1084/jem.184.3.831] [Citation(s) in RCA: 128] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Mice deficient in the src related protein tyrosine kinase, Lyn, exhibit splenomegaly and accumulate lymphoblast-like and plasma cells in spleen as they age, resulting in elevated levels of serum IgM (10-20-fold of control) and glomerulonephritis due to the presence of immune complexes containing auto-reactive antibodies. It remains unclear, however, how antibody-producing cells are accumulated in the lymphoid tissues of Lyn-/- mice. To elucidate the role of Lyn in B cell function, we have studied the proliferative responses to various stimuli and Fas-mediated apoptosis in B cells from young Lyn-/- mice which do not yet show apparent abnormality such as splenomegaly. Compared with control B cells, Lyn-/- B cells were hyper responsive to anti-IgM-induced proliferation and defective in Fc gamma RIIB-mediated suppression of B cell antigen receptor (BCR) signaling, indicating that Lyn is involved in the negative regulation of BCR signaling. In addition, the BCR-mediated signal in Lyn-/- B cells, unlike that in control B cells, failed to act in synergy with either CD40- or IL-4 receptor-triggered signal in inducing a strong proliferative response, suggesting that the BCR signaling pathway in Lyn-/- B cells is altered from that in control B cells. Furthermore, Lyn-/- B cells were found to be impaired in the induction of Fas expression after CD40 ligation and exhibited a reduced susceptibility to Fas-mediated apoptosis. Moreover, BCR cross-linking in Lyn-/- B cells suppressed Fas expression induced by costimulation with CD40 ligand and IL-4. Collectively, these results suggest that the accumulation of lymphoblast-like and plasma cells in Lyn-/- mice may be caused in part, by the accelerated activation of B cells in the absence of Lyn, as well as the impaired Fas-mediated apoptosis after the activation.
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Affiliation(s)
- J Wang
- Medical Institute of Bioregulation, Kyushu University, Fukuoka, Japan
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12
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Wienands J, Larbolette O, Reth M. Evidence for a preformed transducer complex organized by the B cell antigen receptor. Proc Natl Acad Sci U S A 1996; 93:7865-70. [PMID: 8755568 PMCID: PMC38840 DOI: 10.1073/pnas.93.15.7865] [Citation(s) in RCA: 141] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The B cell antigen receptor (BCR) consists of the membrane-bound immunoglobulin (mIg) molecule and the Ig-alpha/Ig-beta heterodimer, which functions as signaling subunit of the receptor. Stimulation of the BCR activates protein tyrosine kinases (PTKs) that phosphorylate a number of substrate proteins, including the Ig-alpha/Ig-beta heterodimer of the BCR itself. How the PTKs become activated after BCR engagement is not known at present. Here, we show that BCR-negative J558L cells treated with the protein tyrosine phosphatase inhibitor pervanadate/H2O2 display only a weak substrate phosphorylation. However, in BCR-positive transfectants of J558L, treatment with pervanadate/H2O2 induces a strong phosphorylation of several substrate proteins. Treatment with pervanadate/H2O2 does not result in receptor crosslinking, yet the pattern of protein phosphorylation is similar to that observed after BCR stimulation by antigen. The response requires cellular integrity because tyrosine phosphorylation of most substrates is not visible in cell lysates. Cells that express a BCR containing an Ig-alpha subunit with a mutated immunoreceptor tyrosine-based activation motif display a delayed response. The data suggest that, once expressed on the surface, the BCR organizes protein tyrosine phosphatases, PTKs, and their substrates into a transducer complex that can be activated by pervanadate/H202 in the absence of BCR crosslinking. Assembly of this preformed complex seems to be a prerequisite for BCR-mediated signal transduction.
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Affiliation(s)
- J Wienands
- Max-Planck-Institüt fur Immunbiologie, Freiburg, Germany
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13
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Jung JU, Lang SM, Jun T, Roberts TM, Veillette A, Desrosiers RC. Downregulation of Lck-mediated signal transduction by tip of herpesvirus saimiri. J Virol 1995; 69:7814-22. [PMID: 7494293 PMCID: PMC189725 DOI: 10.1128/jvi.69.12.7814-7822.1995] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
A protein, called tip, of herpesvirus saimiri associates with Lck in transformed T cells. To investigate the effects of complex formation on cellular signal transduction, we constructed human Jurkat-T-cell lines expressing tip. The expression of tip in Jurkat-T cells dramatically suppressed cellular tyrosine phosphorylation and surface expression of lymphocyte antigens. The expression of tip also blocked the induction of tyrosine phosphorylation by anti-CD3 stimulation. The expression of tip in fibroblast cells suppressed the transforming activity of oncogenic F505 Lck. Binding assays showed that the SH3 domain of Lck is sufficient to form a stable complex with tip in vitro. These results demonstrate that tip acts at an early stage of the T-cell signal transduction cascade by associating with Lck and downregulating Lck-mediated activation. Inhibition of Lck-mediated signal transduction by tip in T cells appears to be analogous to the inhibition of Lyn/Syk-mediated signal transduction in B cells by LMP2A of the B-cell-tropic Epstein-Barr virus.
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Affiliation(s)
- J U Jung
- New England Regional Primate Research Center, Department of Microbiology and Molecular Genetics, Harvard Medical School, Southborough, Massachusetts 01772-9102, USA
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14
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Kurosaki T, Johnson SA, Pao L, Sada K, Yamamura H, Cambier JC. Role of the Syk autophosphorylation site and SH2 domains in B cell antigen receptor signaling. J Exp Med 1995; 182:1815-23. [PMID: 7500027 PMCID: PMC2192262 DOI: 10.1084/jem.182.6.1815] [Citation(s) in RCA: 211] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
To explore the mechanism(s) by which the Syk protein tyrosine kinase participates in B cell antigen receptor (BCR) signaling, we have studied the function of various Syk mutants in B cells made Syk deficient by homologous recombination knockout. Both Syk SH2 domains were required for BCR-mediated Syk and phospholipase C (PLC)-gamma 2 phosphorylation, inositol 1,4,5-triphosphate release, and Ca2+ mobilization. A possible explanation for this requirement was provided by findings that recruitment of Syk to tyrosine-phosphorylated immunoglobulin (Ig) alpha and Ig beta requires both Syk SH2 domains. A Syk mutant in which the putative autophosphorylation site (Y518/Y519) of Syk was changed to phenylalanine was also defective in signal transduction; however, this mutation did not affect recruitment to the phosphorylated immunoreceptor family tyrosine-based activation motifs (ITAMs). These findings not only confirm that both SH2 domains are necessary for Syk binding to tyrosine-phosphorylated Ig alpha and Ig beta but indicate that this binding is necessary for Syk (Y518/519) phosphorylation after BCR ligation. This sequence of events is apparently required for coupling the BCR to most cellular protein tyrosine phosphorylation, to the phosphorylation and activation of PLC-gamma 2, and to Ca2+ mobilization.
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Affiliation(s)
- T Kurosaki
- Department of Cardiovascular Molecular Biology, Lederle Laboratories, Pearl River, New York 10965, USA
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15
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Takata M, Homma Y, Kurosaki T. Requirement of phospholipase C-gamma 2 activation in surface immunoglobulin M-induced B cell apoptosis. J Exp Med 1995; 182:907-14. [PMID: 7561693 PMCID: PMC2192286 DOI: 10.1084/jem.182.4.907] [Citation(s) in RCA: 168] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Surface IgM (sIgM) stimulation induces the tyrosine phosphorylation of multiple cellular substrates, including phospholipase C (PLC)-gamma 2, which is involved in the activation of phosphatidylinositol pathway. DT40 B cells underwent apoptotic cell death when activated through sIgM, a phenomenon that is related to elimination of self-reactive B cells. To examine the roles of PLC-gamma 2 in sIgM signaling, we have generated DT40 cells deficient in PLC-gamma 2 Cross-linking of sIgM on PLC-gamma 2-deficient cells evoked neither inositol 1,4,5-trisphosphate nor calcium mobilization. In PLC-gamma 2- or Syk-deficient DT40 cells, the induction of apoptosis was blocked, but was still observed in Lyn-deficient cells. Src homology 2 domains of PLC-gamma 2 were essential for both its activation and sIgM-induced apoptosis. Since tyrosine phosphorylation of PLC-gamma 2 is mediated by Syk, these results indicate that activation of PLC-gamma 2 through Syk is required for sIgM-induced apoptosis.
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Affiliation(s)
- M Takata
- Department of Cardiovascular Molecular Biology, Lederle Laboratories, Pearl River, New York 10965, USA
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16
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Mahajan S, Fargnoli J, Burkhardt AL, Kut SA, Saouaf SJ, Bolen JB. Src family protein tyrosine kinases induce autoactivation of Bruton's tyrosine kinase. Mol Cell Biol 1995; 15:5304-11. [PMID: 7565679 PMCID: PMC230778 DOI: 10.1128/mcb.15.10.5304] [Citation(s) in RCA: 114] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Bruton's tyrosine kinase (Btk) is tyrosine phosphorylated and enzymatically activated following ligation of the B-cell antigen receptor. These events are temporally regulated, and Btk activation follows that of various members of the Src family of protein tyrosine kinases, thus raising the possibility that Src kinases participate in the Btk activation process. We have evaluated the mechanism underlying Btk enzyme activation and have explored the potential regulatory relationship between Btk and Src protein kinases. We demonstrate in COS transient-expression assays that Btk can be activated through intramolecular autophosphorylation at tyrosine 551 and that Btk autophosphorylation is required for Btk catalytic functions. Coexpression of Btk with members of the Src family of protein tyrosine kinases, but not Syk, led to Btk tyrosine phosphorylation and activation. Using a series of point mutations in Blk (a representative Src protein kinase) and Btk, we show that Src kinases activate Btk through an indirect mechanism that requires membrane association of the Src enzymes as well as functional Btk SH3 and SH2 domains. Our results are compatible with the idea that Src protein tyrosine kinases contribute to Btk activation by indirectly stimulating Btk intramolecular autophosphorylation.
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Affiliation(s)
- S Mahajan
- Department of Oncology, Bristol-Myers Squibb Pharmaceutical Research Institute, Princeton, New Jersey 08543, USA
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17
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Appleby MW, Kerner JD, Chien S, Maliszewski CR, Bondada S, Perlmutter RM, Bondadaa S [corrected to Bondada S]. Involvement of p59fynT in interleukin-5 receptor signaling. J Exp Med 1995; 182:811-20. [PMID: 7650487 PMCID: PMC2192161 DOI: 10.1084/jem.182.3.811] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Previous studies implicate the nonreceptor protein tyrosine kinase (PTK) p59fyn in the propagation of signals from the B cell antigen receptor. To elucidate the functions of this kinase, we examined B cell responsiveness in mice engineered to lack the hematopoietic isoform of p59fyn. Remarkably, antigen receptor signaling was only modestly defective in fynTnull B cells. In contrast, signaling from the interleukin (IL)-5 receptor which ordinarily provides a comitogenic stimulus with antiimmunoglobulin, was completely blocked. Our results document the importance of p59fynT in IL-5 responses in B cells, and they support a general model for cytokine receptor signal transduction involving the simultaneous recruitment of at least three families of PTK.
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Affiliation(s)
- M W Appleby
- Howard Hughes Medical Institute, Seattle, Washington 98195, USA
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18
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Bu JY, Shaw AS, Chan AC. Analysis of the interaction of ZAP-70 and syk protein-tyrosine kinases with the T-cell antigen receptor by plasmon resonance. Proc Natl Acad Sci U S A 1995; 92:5106-10. [PMID: 7761456 PMCID: PMC41857 DOI: 10.1073/pnas.92.11.5106] [Citation(s) in RCA: 107] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Tyrosine phosphorylation of a 17-amino acid immunoreceptor tyrosine-based activation motif (ITAM), conserved in each of the signaling subunits of the T-cell antigen receptor (TCR), mediates the recruitment of ZAP-70 and syk protein-tyrosine kinases (PTKs) to the activated receptor. The interaction between the two tandemly arranged Src-homology 2 (SH2) domains of this family of PTKs and each of the phosphotyrosine-containing ITAMs was examined by real-time measurements of kinetic parameters. The association rate and equilibrium binding constants for the ZAP-70 and syk SH2 domains were determined for the CD3 epsilon ITAM. Both PTKs bound with ka and Kd values of 5 x 10(6) M-1.sec-1 and approximately 25 nM, respectively. Bindings to the other TCR ITAMs (zeta 1, zeta 2, gamma, and delta ITAMs) were comparable, although the zeta 3 ITAM bound approximately 2.5-fold less well. Studies of the affinity of a single functional SH2 domain of ZAP-70 provided evidence for the cooperative nature of binding of the dual SH2 domains. Mutation of either single SH2 domain decreased the Kd by > 100-fold. Finally, the critical features of the ITAM for syk binding were found to be similar to those required for ZAP-70 binding. These data provide insight into the mechanism by which the multisubunit TCR interacts with downstream effector molecules.
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MESH Headings
- Amino Acid Sequence
- Binding Sites
- Electrophoresis, Polyacrylamide Gel
- Enzyme Precursors/biosynthesis
- Enzyme Precursors/isolation & purification
- Enzyme Precursors/metabolism
- Glutathione Transferase/biosynthesis
- Humans
- Intracellular Signaling Peptides and Proteins
- Kinetics
- Molecular Sequence Data
- Protein-Tyrosine Kinases/biosynthesis
- Protein-Tyrosine Kinases/isolation & purification
- Protein-Tyrosine Kinases/metabolism
- Receptor-CD3 Complex, Antigen, T-Cell/isolation & purification
- Receptor-CD3 Complex, Antigen, T-Cell/metabolism
- Receptors, Antigen, T-Cell/isolation & purification
- Receptors, Antigen, T-Cell/metabolism
- Recombinant Fusion Proteins/biosynthesis
- Recombinant Fusion Proteins/isolation & purification
- Recombinant Fusion Proteins/metabolism
- Sequence Homology, Amino Acid
- Syk Kinase
- ZAP-70 Protein-Tyrosine Kinase
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Affiliation(s)
- J Y Bu
- Division of Rheumatology, Washington University School of Medicine, St. Louis, MO 63110, USA
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19
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Paolini R, Renard V, Vivier E, Ochiai K, Jouvin MH, Malissen B, Kinet JP. Different roles for the Fc epsilon RI gamma chain as a function of the receptor context. J Exp Med 1995; 181:247-55. [PMID: 7528770 PMCID: PMC2191817 DOI: 10.1084/jem.181.1.247] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The high affinity immunoglobulin E receptor (Fc epsilon RI) and the B and T cell antigen receptors (TCR) are multimeric complexes containing subunits with cytoplasmic antigen recognition activation motifs (ARAMs). The presence of multiple motifs may be a way to amplify a single signal or provide independent activation modules. Here we have compared the signaling capacity of the same Fc epsilon RI gamma motif in the context of two different receptors, Fc epsilon RI and TCR/CD3, simultaneously reconstituted on the surface of the same zeta-deficient T cell line. Both reconstituted receptors mediate early (phosphorylation) and late (interleukin [IL]-2 release) signals. Mutation of the two tyrosine residues of ARAM gamma alters early signaling by both receptors, but the set of substrates phosphorylated via ARAM gamma is different for each receptor and is thus dependent on the receptor context. Furthermore, the mutations prevent Fc epsilon RI- but not TCR/CD3-mediated IL-2 release. These data demonstrate that ARAM gamma is necessary for allowing both receptors to phosphorylate the complete set of substrates, and that the CD3 complex, unlike the Fc epsilon RI beta chain, contains activation modules capable of compensating for the absence of a functional ARAM gamma in generating late signals such as IL-2 release.
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MESH Headings
- Amino Acid Sequence
- Animals
- Electrophoresis, Gel, Two-Dimensional
- In Vitro Techniques
- Interleukin-2/metabolism
- Macromolecular Substances
- Mice
- Molecular Sequence Data
- Phosphoproteins/chemistry
- Phosphotyrosine
- Receptors, Antigen, T-Cell, alpha-beta/chemistry
- Receptors, Antigen, T-Cell, alpha-beta/physiology
- Receptors, IgE/chemistry
- Receptors, IgE/physiology
- Signal Transduction
- Transfection
- Tyrosine/analogs & derivatives
- Tyrosine/metabolism
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Affiliation(s)
- R Paolini
- Molecular Allergy and Immunology Section, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland 20852
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20
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Abstract
In B cells, two classes of protein tyrosine kinases (PTKs), the Src family of PTKs (Lyn, Fyn, Lck, and Blk) and non-Src family of PTKs (Syk), are known to be involved in signal transduction induced by the stimulation of the B-cell antigen receptor (BCR). Previous studies using Lyn-negative chicken B-cell clones revealed that Lyn is necessary for transduction of signals through the BCR. The kinase activity of the Src family of PTKs is negatively regulated by phosphorylation at the C-terminal tyrosine residue, and the PTK Csk has been demonstrated to phosphorylate this C-terminal residue of the Src family of PTKs. To investigate the role of Csk in BCR signaling, Csk-negative chicken B-cell clones were generated. In these Csk-negative cells, Lyn became constitutively active and highly phosphorylated at the autophosphorylation site, indicating that Csk is necessary to sustain Lyn in an inactive state. Since the C-terminal tyrosine phosphorylation of Lyn is barely detectable in the unstimulated, wild-type B cells, our data suggest that the activities of Csk and a certain protein tyrosine phosphatase(s) are balanced to maintain Lyn at a hypophosphorylated and inactive state. Moreover, we show that the kinase activity of Syk was also constitutively activated in Csk-negative cells. The degree of activation of both the Lyn and Syk kinases in Csk-negative cells was comparable to that observed in wild-type cells after BCR stimulation. However, BCR stimulation was still necessary in Csk-negative cells to elicit tyrosine phosphorylation of cellular proteins, as well as calcium mobilization and inositol 1,4,5-trisphosphate generation. These results suggest that not only activation of the Lyn and Syk kinases but also additional signals induced by the cross-linking of the BCR are required for full transduction of BCR signaling.
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21
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Hata A, Sabe H, Kurosaki T, Takata M, Hanafusa H. Functional analysis of Csk in signal transduction through the B-cell antigen receptor. Mol Cell Biol 1994; 14:7306-13. [PMID: 7935444 PMCID: PMC359265 DOI: 10.1128/mcb.14.11.7306-7313.1994] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
In B cells, two classes of protein tyrosine kinases (PTKs), the Src family of PTKs (Lyn, Fyn, Lck, and Blk) and non-Src family of PTKs (Syk), are known to be involved in signal transduction induced by the stimulation of the B-cell antigen receptor (BCR). Previous studies using Lyn-negative chicken B-cell clones revealed that Lyn is necessary for transduction of signals through the BCR. The kinase activity of the Src family of PTKs is negatively regulated by phosphorylation at the C-terminal tyrosine residue, and the PTK Csk has been demonstrated to phosphorylate this C-terminal residue of the Src family of PTKs. To investigate the role of Csk in BCR signaling, Csk-negative chicken B-cell clones were generated. In these Csk-negative cells, Lyn became constitutively active and highly phosphorylated at the autophosphorylation site, indicating that Csk is necessary to sustain Lyn in an inactive state. Since the C-terminal tyrosine phosphorylation of Lyn is barely detectable in the unstimulated, wild-type B cells, our data suggest that the activities of Csk and a certain protein tyrosine phosphatase(s) are balanced to maintain Lyn at a hypophosphorylated and inactive state. Moreover, we show that the kinase activity of Syk was also constitutively activated in Csk-negative cells. The degree of activation of both the Lyn and Syk kinases in Csk-negative cells was comparable to that observed in wild-type cells after BCR stimulation. However, BCR stimulation was still necessary in Csk-negative cells to elicit tyrosine phosphorylation of cellular proteins, as well as calcium mobilization and inositol 1,4,5-trisphosphate generation. These results suggest that not only activation of the Lyn and Syk kinases but also additional signals induced by the cross-linking of the BCR are required for full transduction of BCR signaling.
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Affiliation(s)
- A Hata
- Laboratory of Molecular Oncology, Rockefeller University, New York, New York 10021, USA
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22
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Aoki Y, Isselbacher KJ, Pillai S. Bruton tyrosine kinase is tyrosine phosphorylated and activated in pre-B lymphocytes and receptor-ligated B cells. Proc Natl Acad Sci U S A 1994; 91:10606-9. [PMID: 7524098 PMCID: PMC45070 DOI: 10.1073/pnas.91.22.10606] [Citation(s) in RCA: 151] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The gene encoding Bruton tyrosine kinase (Btk) is known to be mutated in human X chromosome-linked agammaglobulinemia and in the Xid mouse. This kinase was examined in B lymphocytes before and after antigen receptor ligation and also in pre-B cells. Btk was found to be catalytically activated and tyrosine phosphorylated in response to anti-IgM stimulation in B cells. This kinase is also constitutively phosphorylated on tyrosine residues in pre-B cells. These findings point to a functional role for Btk in pre-antigen and antigen receptor signaling during B-cell development and provide a biochemical explanation for the X-linked genetic syndromes already linked to this kinase.
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Affiliation(s)
- Y Aoki
- Massachusetts General Hospital Cancer Center, Boston 02129
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23
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Saouaf SJ, Mahajan S, Rowley RB, Kut SA, Fargnoli J, Burkhardt AL, Tsukada S, Witte ON, Bolen JB. Temporal differences in the activation of three classes of non-transmembrane protein tyrosine kinases following B-cell antigen receptor surface engagement. Proc Natl Acad Sci U S A 1994; 91:9524-8. [PMID: 7524079 PMCID: PMC44845 DOI: 10.1073/pnas.91.20.9524] [Citation(s) in RCA: 194] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
We evaluated in WEHI 231 B cells the time-dependent responses of Lyn, Blk, Btk, Syk, and three members of the Jak family of protein tyrosine kinases following antibody-mediated surface engagement of the B-cell antigen receptor. Our results show that the enzyme activities of Lyn and Blk were stimulated within seconds of antigen receptor engagement and correlated with the initial tyrosine phosphorylation of the Ig alpha and Ig beta subunits of the B-cell antigen receptor. Btk enzyme activity was also transiently stimulated and was maximal at approximately 5 min after B-cell receptor surface binding. Syk activity gradually increased to a maximum at 10-30 min following receptor ligation and was found to parallel the association of Syk with the tyrosine phosphorylated Ig alpha and Ig beta subunits of the receptor. While the specific activities of the Jak1, Jak2, and Tyk2 protein tyrosine kinases were unaltered following B-cell receptor ligation, the abundance of Jak1 and Jak2 were increased 3- to 4-fold within 10 min of receptor engagement. These results demonstrate that multiple families of non-transmembrane protein tyrosine kinases are temporally regulated during the process of B-cell antigen receptor-initiated intracellular signal transduction.
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Affiliation(s)
- S J Saouaf
- Department of Molecular Biology, Bristol-Myers Squibb Pharmaceutical Research Institute, Princeton, NJ 08543
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24
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Wang AV, Scholl PR, Geha RS. Physical and functional association of the high affinity immunoglobulin G receptor (Fc gamma RI) with the kinases Hck and Lyn. J Exp Med 1994; 180:1165-70. [PMID: 8064233 PMCID: PMC2191633 DOI: 10.1084/jem.180.3.1165] [Citation(s) in RCA: 117] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The high affinity immunoglobulin G (IgG) receptor Fc gamma RI (CD64) is expressed constitutively on monocytes and macrophages, and is inducible on neutrophils. Fc gamma RI has recently been shown to be associated with the signal transducing gamma subunit of the high-affinity IgE receptor (Fc epsilon RI gamma). Induction of cytoplasmic protein tyrosine phosphorylation by Fc gamma RI cross-linking is known to be important in mediating Fc gamma RI-coupled effector functions. Recently, syk has been implicated in this role. We now report that the src-type kinases hck and lyn are physically and functionally associated with Fc gamma RI. Hck and lyn coimmunoprecipitated with Fc gamma RI from detergent lysates of normal human monocytes and of the monocytic line THP-1. Hck and lyn showed rapidly increased phosphorylation and increased exogenous substrate kinase activity after cross-linking of Fc gamma RI. These results demonstrate both physical and functional association of the Fc gamma RI/Fc epsilon RI gamma receptor complex with hck and lyn, and suggest a potential signal transducing role for these kinases in monocyte/macrophage activation.
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Affiliation(s)
- A V Wang
- Division of Immunology, Children's Hospital, Boston, Massachusetts
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25
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Mori S, Takanashi M, Shiota M, Choi SH, Yamanashi Y, Watanabe T, Koike M. Down-regulation of membrane immunoglobulin-associated proteins, MB-1, B29 and Lyn, in AIDS-lymphomas and related conditions. Virchows Arch 1994; 424:553-61. [PMID: 8032536 DOI: 10.1007/bf00191443] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
B-lymphocytes infected with Epstein-Barr virus (EBV) can proliferate in immunocompromised hosts to form lymphomas (MLs). Similar MLs are produced in mice with severe combined immune deficiency (SCID) by transfusion of human lymphocytes infected with EBV (SCID-EBV-positive BML). Mb-1 and B29 are recently found transmembrane proteins associated with membrane immunoglobulins (mIg) on the surface of B cells. Lyn is a src family gene product expressed in B cells submembranously, in association with mIg, possibly through Mb-1/B29 heterodimer. These mIg-associated proteins (Mb-1, B29 and Lyn) are known to mediate antigenic stimulation through mIgs. We noted recently that Lyn is decreased selectively in around a half of SCID-EBV-positive BMLs. We extended this line of investigation to other mIg-associated proteins. Five acquired immunodeficiency syndrome (AIDS)-MLs and ten SCID-EBV-positive BMLs were first analysed by immunohistochemistry for the expression of Mb-1, B29 and Lyn. It was found that in AIDS-MLs, all the mIg-associated proteins were heavily down-regulated. In SCID-EBV-positive BMLs, Mb-1 was down regulated in six of ten, B29 in nine of ten and Lyn in six of ten, whereas no down-regulation was noted in eight EBV-free B MLs that were also maintained in SCID mice. An additional flow-cytometric study of two SCID-EBV-positive and two EBV-negative BMLs showed similar down-regulation in the former cases exclusively. Whereas mIg was also decreased in three of five SCID-EBV positive BMLs, it did not necessarily match the decrease of mIg-associated proteins, which contrasts with the recent finding that mIgs coexist with Mb-1 or B29. Some EBV-encoded proteins may activate host molecules located downwardly; this, in turn, may lead to the suppression of these upwardly-located mIg-associated proteins.
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Affiliation(s)
- S Mori
- Department of Pathology, University of Tokyo, Japan
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26
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Aoki Y, Isselbacher KJ, Cherayil BJ, Pillai S. Tyrosine phosphorylation of Blk and Fyn Src homology 2 domain-binding proteins occurs in response to antigen-receptor ligation in B cells and constitutively in pre-B cells. Proc Natl Acad Sci U S A 1994; 91:4204-8. [PMID: 7514299 PMCID: PMC43753 DOI: 10.1073/pnas.91.10.4204] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Proteins that bind to discrete domains of the Blk, Fyn, Lyn, and Btk protein tyrosine kinases were examined in pre-B cells that had not been subjected to any external stimulation, as well as in nonstimulated and antigen-receptor-ligated B cells. Proteins that bind to the Src homology 2 domains of Blk and Fyn were identified in B cells that had been activated with anti-IgM but were not identified in unstimulated B cells. A number of Blk and Fyn Src homology 2 domain-binding phosphoproteins were also observed in pre-B cells that had not been stimulated in vitro. The phosphoproteins seen in activated B cells potentially represent substrates that play a role in the pathway of antigen-receptor-mediated signaling. Distinct signaling pathways involving distinguishable kinase substrates may be relevant in pre-B-cell-receptor-mediated cell survival during ontogeny. These results indirectly support models that predict constitutive ligand-independent signaling by the pre-antigen receptor during lymphoid ontogeny.
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Affiliation(s)
- Y Aoki
- Cancer Center, Massachusetts General Hospital, Boston 02129
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27
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Ig alpha and Ig beta are functionally homologous to the signaling proteins of the T-cell receptor. Mol Cell Biol 1994. [PMID: 8289790 DOI: 10.1128/mcb.14.2.1095] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Signal transduction by antigen receptors and some Fc receptors requires the activation of a family of receptor-associated transmembrane accessory proteins. One common feature of the cytoplasmic domains of these accessory molecules is the presence is at least two YXXA repeats that are potential sites for interaction with Src homology 2 domain-containing proteins. However, the degree of similarity between the different receptor-associated proteins varies from that of T-cell receptor (TCR) zeta and Fc receptor RIIIA gamma chains, which are homologous, to the distantly related Ig alpha and Ig beta proteins of the B-cell antigen receptor. To determine whether T- and B-cell antigen receptors are in fact functionally homologous, we have studied signal transduction by chimeric immunoglobulins bearing the Ig alpha or Ig beta cytoplasmic domain. We found that Ig alpha and Ig beta cytoplasmic domains were able to activate Ca2+ flux, interleukin-2 secretion, and phosphorylation of the same group of cellular substrates as the TCR in transfected T cells. Chimeric proteins were then used to examine the minimal requirements for activation of the Fyn, Lck, and ZAP kinases in T cells. Both Ig alpha and Ig beta were able to trigger Fyn, Lck, and ZAP directly without involvement of TCR components. Cytoplasmic tyrosine residues in Ig beta were required for recruitment and activation of ZAP-70, but these amino acids were not essential for the activation of Fyn and Lck. We conclude that Fyn and Lck are able to recognize a clustered nonphosphorylated immune recognition receptor, but activation of these kinases is not sufficient to induce cellular responses such as Ca2+ flux and interleukin-2 secretion. In addition, the molecular structures involved in antigen receptor signaling pathways are conserved between T and B cells.
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28
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Ren CL, Morio T, Fu SM, Geha RS. Signal transduction via CD40 involves activation of lyn kinase and phosphatidylinositol-3-kinase, and phosphorylation of phospholipase C gamma 2. J Exp Med 1994; 179:673-80. [PMID: 7507510 PMCID: PMC2191357 DOI: 10.1084/jem.179.2.673] [Citation(s) in RCA: 198] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
CD40 is a 50-kD glycoprotein that plays an important role in B cell survival, memory, and immunoglobulin isotype switch. Engagement of the CD40 antigen by monoclonal antibodies (mAbs) results in increased protein tyrosine kinase (PTK) activity, which plays an important role in mediating the biologic effects of CD40. We demonstrate, using an in situ phosphorylation technique, that CD40 cross-linking by the anti-CD40 mAb 626.1 resulted within 1 min in increased phosphorylation of the src type kinase, lyn, in Daudi B cell lines and remained sustained for up to 20 min. The activity of lyn kinase, as measured by immune complex kinase assay, was also increased after CD40 engagement, with similar kinetics. In contrast, the phosphorylation and activity of fyn, fgr, and lck kinases demonstrated minimal changes following stimulation of Daudi cells with mAb 626.1 over this same time period. CD40 engagement also resulted in phosphorylation of phospholipase C gamma 2 of phosphatidylinositol (PLC gamma 2) and phosphatidylinositol (PI)-3-kinase. Phosphorylation of PI-3-kinase was shown to be associated with an increase in its enzymatic activity. These results suggest that lyn plays an important role in CD40-mediated PTK activation and identify PLC gamma 2 and PI-3-kinase targets for CD40-mediated phosphorylation, suggesting a role for these two enzymes in CD40 signal transduction.
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Affiliation(s)
- C L Ren
- Division of Immunology, Children's Hospital, Boston, Massachusetts 02115
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29
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Burkhardt AL, Costa T, Misulovin Z, Stealy B, Bolen JB, Nussenzweig MC. Ig alpha and Ig beta are functionally homologous to the signaling proteins of the T-cell receptor. Mol Cell Biol 1994; 14:1095-103. [PMID: 8289790 PMCID: PMC358465 DOI: 10.1128/mcb.14.2.1095-1103.1994] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Signal transduction by antigen receptors and some Fc receptors requires the activation of a family of receptor-associated transmembrane accessory proteins. One common feature of the cytoplasmic domains of these accessory molecules is the presence is at least two YXXA repeats that are potential sites for interaction with Src homology 2 domain-containing proteins. However, the degree of similarity between the different receptor-associated proteins varies from that of T-cell receptor (TCR) zeta and Fc receptor RIIIA gamma chains, which are homologous, to the distantly related Ig alpha and Ig beta proteins of the B-cell antigen receptor. To determine whether T- and B-cell antigen receptors are in fact functionally homologous, we have studied signal transduction by chimeric immunoglobulins bearing the Ig alpha or Ig beta cytoplasmic domain. We found that Ig alpha and Ig beta cytoplasmic domains were able to activate Ca2+ flux, interleukin-2 secretion, and phosphorylation of the same group of cellular substrates as the TCR in transfected T cells. Chimeric proteins were then used to examine the minimal requirements for activation of the Fyn, Lck, and ZAP kinases in T cells. Both Ig alpha and Ig beta were able to trigger Fyn, Lck, and ZAP directly without involvement of TCR components. Cytoplasmic tyrosine residues in Ig beta were required for recruitment and activation of ZAP-70, but these amino acids were not essential for the activation of Fyn and Lck. We conclude that Fyn and Lck are able to recognize a clustered nonphosphorylated immune recognition receptor, but activation of these kinases is not sufficient to induce cellular responses such as Ca2+ flux and interleukin-2 secretion. In addition, the molecular structures involved in antigen receptor signaling pathways are conserved between T and B cells.
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Affiliation(s)
- A L Burkhardt
- Howard Hughes Medical Institute, Rockefeller University, New York, New York 10021
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30
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Roth PE, Doglio L, Manz JT, Kim JY, Lo D, Storb U. Immunoglobulin gamma 2b transgenes inhibit heavy chain gene rearrangement, but cannot promote B cell development. J Exp Med 1993; 178:2007-21. [PMID: 8245779 PMCID: PMC2191288 DOI: 10.1084/jem.178.6.2007] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Transgenic mice with a gamma 2b transgene were produced to investigate whether gamma 2b can replace mu in the development of B lymphocytes. Transgenic gamma 2b is present on the surface of B cells. Young transgenic mice have a dramatic decrease in B cell numbers, however, older mice have almost normal B cell numbers. Strikingly, all gamma 2b-expressing B cells in the spleen also express mu. The same is true for mice with a hybrid transgene in which the mu transmembrane and intracytoplasmic sequences replace those of gamma 2b (gamma 2b-mumem). The B cell defect is not due to toxicity of gamma 2b since crosses between gamma 2b transgenic and mu transgenic mice have normal numbers of B cells. Presence of the gamma 2b transgene strongly enhances the feedback inhibition of endogenous heavy chain gene rearrangement. Light chain genes are expressed normally, and the early expression of transgenic light chains does not improve B cell maturation. When the endogenous mu locus is inactivated, B cells do not develop at all in gamma 2b transgenic mice. The data suggest that gamma 2b cannot replace mu in promoting the developmental maturation of B cells, but that it can cause feedback inhibition of heavy chain gene rearrangement. Thus, the signals for heavy chain feedback and B cell maturation appear to be different.
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Affiliation(s)
- P E Roth
- Department of Molecular Genetics and Cell Biology, University of Chicago, Illinois 60637
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31
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Mapping of sites on the Src family protein tyrosine kinases p55blk, p59fyn, and p56lyn which interact with the effector molecules phospholipase C-gamma 2, microtubule-associated protein kinase, GTPase-activating protein, and phosphatidylinositol 3-kinase. Mol Cell Biol 1993. [PMID: 8395016 DOI: 10.1128/mcb.13.9.5877] [Citation(s) in RCA: 109] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Engagement of the B-cell antigen receptor complex induces immediate activation of receptor-associated Src family tyrosine kinases including p55blk, p59fyn, p53/56lyn, and perhaps p56lck, and this response is accompanied by tyrosine phosphorylation of distinct cellular substrates. These kinases act directly or indirectly to phosphorylate and/or activate effector proteins including p42 (microtubule-associated protein kinase) (MAPK), phospholipases C-gamma 1 (PLC gamma 1) and C-gamma 2 (PLC gamma 2), phosphatidylinositol 3-kinase (PI 3-K), and p21ras-GTPase-activating protein (GAP). Although coimmunoprecipitation results indicate that the Src family protein tyrosine kinases interact physically with some of these effector molecules, the molecular basis of this interaction has not been established. Here, we show that three distinct sites mediate the interaction of these kinases with effectors. The amino-terminal 27 residues of the unique domain of p56lyn mediate association with PLC gamma 2, MAPK, and GAP. Binding to PI 3-K is mediated through the Src homology 3 (SH3) domains of the Src family kinases. Relatively small proportions of cellular PI 3-K, PLC gamma 2, MAPK, and GAP, presumably those which are tyrosine phosphorylated, bind to the SH2 domains of these kinases. Comparative analysis of binding activities of Blk, Lyn, and Fyn shows that these kinases differ in their abilities to associate with MAPK and PI 3-K, suggesting that they may preferentially bind and subsequently phosphorylate distinct sets of downstream effector molecules in vivo. Fast protein liquid chromatography Mono Q column-fractionated MAPK maintains the ability to bind bacterially expressed Lyn, suggesting that the two kinases may interact directly.
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32
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Pleiman CM, Clark MR, Gauen LK, Winitz S, Coggeshall KM, Johnson GL, Shaw AS, Cambier JC. Mapping of sites on the Src family protein tyrosine kinases p55blk, p59fyn, and p56lyn which interact with the effector molecules phospholipase C-gamma 2, microtubule-associated protein kinase, GTPase-activating protein, and phosphatidylinositol 3-kinase. Mol Cell Biol 1993; 13:5877-87. [PMID: 8395016 PMCID: PMC360336 DOI: 10.1128/mcb.13.9.5877-5887.1993] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Engagement of the B-cell antigen receptor complex induces immediate activation of receptor-associated Src family tyrosine kinases including p55blk, p59fyn, p53/56lyn, and perhaps p56lck, and this response is accompanied by tyrosine phosphorylation of distinct cellular substrates. These kinases act directly or indirectly to phosphorylate and/or activate effector proteins including p42 (microtubule-associated protein kinase) (MAPK), phospholipases C-gamma 1 (PLC gamma 1) and C-gamma 2 (PLC gamma 2), phosphatidylinositol 3-kinase (PI 3-K), and p21ras-GTPase-activating protein (GAP). Although coimmunoprecipitation results indicate that the Src family protein tyrosine kinases interact physically with some of these effector molecules, the molecular basis of this interaction has not been established. Here, we show that three distinct sites mediate the interaction of these kinases with effectors. The amino-terminal 27 residues of the unique domain of p56lyn mediate association with PLC gamma 2, MAPK, and GAP. Binding to PI 3-K is mediated through the Src homology 3 (SH3) domains of the Src family kinases. Relatively small proportions of cellular PI 3-K, PLC gamma 2, MAPK, and GAP, presumably those which are tyrosine phosphorylated, bind to the SH2 domains of these kinases. Comparative analysis of binding activities of Blk, Lyn, and Fyn shows that these kinases differ in their abilities to associate with MAPK and PI 3-K, suggesting that they may preferentially bind and subsequently phosphorylate distinct sets of downstream effector molecules in vivo. Fast protein liquid chromatography Mono Q column-fractionated MAPK maintains the ability to bind bacterially expressed Lyn, suggesting that the two kinases may interact directly.
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Affiliation(s)
- C M Pleiman
- Department of Pediatrics, National Jewish Center for Immunology and Respiratory Medicine, Denver, Colorado 80206
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33
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Yao XR, Scott DW. Antisense oligodeoxynucleotides to the blk tyrosine kinase prevent anti-mu-chain-mediated growth inhibition and apoptosis in a B-cell lymphoma. Proc Natl Acad Sci U S A 1993; 90:7946-50. [PMID: 7690139 PMCID: PMC47264 DOI: 10.1073/pnas.90.17.7946] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Crosslinking of membrane immunoglobulin (mIg) receptors by anti-Ig causes growth inhibition and subsequent cell death due to apoptosis in a murine B-cell lymphoma model. The earliest signal transduction via mIg has recently been shown to be dependent on the activation of one or more protein tyrosine kinases (PTKs). In this study, we utilized the CH31 lymphoma, which is extremely sensitive to growth inhibition by anti-Ig, to examine the role of PTKs in cell cycle arrest. This cell line expresses multiple PTKs, whose activities are stimulated by crosslinking mIg. To determine whether PTK activity is essential for the inhibition of cell growth, we exposed CH31 cells to antisense oligodeoxynucleotides for the blk PTK prior to the growth inhibition assay. We found that exposure of CH31 cells to blk antisense effectively prevented anti-mu-chain-mediated growth inhibition and subsequent apoptosis. Corresponding blk sense or antisense oligonucleotides for other PTKs had no protective effect against anti-mu. Moreover, antisense blk oligonucleotides had no effect on transforming growth factor beta-mediated growth arrest and apoptosis. Further experiments showed significantly reduced endogenous p55blk in blk antisense-treated cells. In addition, anti-mu stimulation of antisense-treated cells failed to induce any detectable increase in kinase activity of p55blk, a result suggesting the uncoupling of blk proteins from normal signal pathways that are essential for growth inhibition. These results implicate a role of blk kinase in anti-mu-mediated pathway to cell cycle arrest.
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Affiliation(s)
- X R Yao
- Division of Immunology and Immunotherapy, University of Rochester Cancer Center, NY 14642
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34
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Inhibition of thyrotropin-stimulated DNA synthesis by microinjection of inhibitors of cellular Ras and cyclic AMP-dependent protein kinase. Mol Cell Biol 1993. [PMID: 8336696 DOI: 10.1128/mcb.13.8.4477] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Microinjection of a dominant interfering mutant of Ras (N17 Ras) caused a significant reduction in thyrotropin (thyroid-stimulating hormone [TSH])-stimulated DNA synthesis in rat thyroid cells. A similar reduction was observed following injection of the heat-stable protein kinase inhibitor of the cyclic AMP-dependent protein kinase. Coinjection of both inhibitors almost completely abolished TSH-induced DNA synthesis. In contrast to TSH, overexpression of cellular Ras protein did not stimulate the expression of a cyclic AMP response element-regulated reporter gene. Similarly, injection of N17 Ras had no effect on TSH-stimulated reporter gene expression. Moreover, overexpression of cellular Ras protein stimulated similar levels of DNA synthesis in the presence or absence of the heat-stable protein kinase inhibitor. Together, these results suggest that in Wistar rat thyroid cells, a full mitogenic response to TSH requires both Ras and cyclic APK-dependent protein kinase.
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35
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Kupperman E, Wen W, Meinkoth JL. Inhibition of thyrotropin-stimulated DNA synthesis by microinjection of inhibitors of cellular Ras and cyclic AMP-dependent protein kinase. Mol Cell Biol 1993; 13:4477-84. [PMID: 8336696 PMCID: PMC360056 DOI: 10.1128/mcb.13.8.4477-4484.1993] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Microinjection of a dominant interfering mutant of Ras (N17 Ras) caused a significant reduction in thyrotropin (thyroid-stimulating hormone [TSH])-stimulated DNA synthesis in rat thyroid cells. A similar reduction was observed following injection of the heat-stable protein kinase inhibitor of the cyclic AMP-dependent protein kinase. Coinjection of both inhibitors almost completely abolished TSH-induced DNA synthesis. In contrast to TSH, overexpression of cellular Ras protein did not stimulate the expression of a cyclic AMP response element-regulated reporter gene. Similarly, injection of N17 Ras had no effect on TSH-stimulated reporter gene expression. Moreover, overexpression of cellular Ras protein stimulated similar levels of DNA synthesis in the presence or absence of the heat-stable protein kinase inhibitor. Together, these results suggest that in Wistar rat thyroid cells, a full mitogenic response to TSH requires both Ras and cyclic APK-dependent protein kinase.
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Affiliation(s)
- E Kupperman
- Department of Medicine, University of California, San Diego, La Jolla 92093
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36
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Hamada F, Aoki M, Akiyama T, Toyoshima K. Association of immunoglobulin G Fc receptor II with Src-like protein-tyrosine kinase Fgr in neutrophils. Proc Natl Acad Sci U S A 1993; 90:6305-9. [PMID: 8327512 PMCID: PMC46917 DOI: 10.1073/pnas.90.13.6305] [Citation(s) in RCA: 104] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The interaction of Fc receptors with antibody-antigen complexes activates multiple biological functions in hematopoietic cells. Recently, protein-tyrosine phosphorylation has been suggested to be involved in Fc receptor-mediated cell signaling. Here we show that the Src-like protein-tyrosine kinase Fgr, which is specifically expressed in mature myelomonocytic cells, coimmunoprecipitates with IgG Fc receptor II (Fc gamma RII), but not with Fc gamma RIII from detergent lysates of human peripheral neutrophils. Crosslinking of Fc gamma RII induced a rapid increase in the tyrosine kinase activity and comodulation of Fgr. These results suggest that Fgr is physically and functionally associated with Fc gamma RII and involved in Fc gamma RII-mediated signal transduction pathways.
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Affiliation(s)
- F Hamada
- Department of Oncogene Research, Osaka University, Japan
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37
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Leprince C, Draves KE, Geahlen RL, Ledbetter JA, Clark EA. CD22 associates with the human surface IgM-B-cell antigen receptor complex. Proc Natl Acad Sci U S A 1993; 90:3236-40. [PMID: 8475064 PMCID: PMC46274 DOI: 10.1073/pnas.90.8.3236] [Citation(s) in RCA: 148] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The B-cell surface molecule CD22, when cross-linked, modulates signaling through the surface IgM (sIgM)-B-cell receptor (BCR) complex. Here we analyzed the basis of this interaction between CD22 and the human sIgM complex. After lysis of B cells or B-cell lines in digitonin, CD22 coimmunoprecipitated a kinase activity that in vitro-phosphorylated two polypeptides of 150 and 130 kDa on tyrosine residues. By immunoblot analysis with a rabbit anti-serum specific for a synthetic peptide of CD22, we found these proteins to be CD22 itself. Furthermore, the phosphorylated 150-kDa CD22 was found in the sIgM-BCR complex maintained by digitonin, along with Ig alpha/mb-1, Ig beta/B29, and a 75-kDa polypeptide precipitated by an antiserum specific to protein-tyrosine kinase PTK72. CD22 is likely to be an important signaling partner in the sIgM-BCR complex since it is very rapidly and strikingly phosphorylated after sIgM is cross-linked and since it contains the antigen recognition homology I (ARHI) motif, present in other antigen receptor molecules.
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MESH Headings
- Amino Acid Sequence
- Animals
- Antigens, CD/genetics
- Antigens, CD/isolation & purification
- Antigens, CD/metabolism
- Antigens, Differentiation, B-Lymphocyte/genetics
- Antigens, Differentiation, B-Lymphocyte/isolation & purification
- Antigens, Differentiation, B-Lymphocyte/metabolism
- B-Lymphocytes/immunology
- B-Lymphocytes/metabolism
- Burkitt Lymphoma
- Cell Adhesion Molecules/isolation & purification
- Cell Adhesion Molecules/metabolism
- Cell Membrane/immunology
- Cell Membrane/metabolism
- Cells, Cultured
- Electrophoresis, Polyacrylamide Gel
- Humans
- Immunoglobulin M/isolation & purification
- Immunoglobulin M/metabolism
- Lectins
- Mice
- Molecular Sequence Data
- Molecular Weight
- Palatine Tonsil/immunology
- Protein Kinases/isolation & purification
- Protein Kinases/metabolism
- Receptors, Antigen, B-Cell/isolation & purification
- Receptors, Antigen, B-Cell/metabolism
- Sequence Homology, Amino Acid
- Sialic Acid Binding Ig-like Lectin 2
- Tumor Cells, Cultured
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Affiliation(s)
- C Leprince
- Department of Microbiology, University of Washington, Seattle 98195
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38
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Yamanashi Y, Okada M, Semba T, Yamori T, Umemori H, Tsunasawa S, Toyoshima K, Kitamura D, Watanabe T, Yamamoto T. Identification of HS1 protein as a major substrate of protein-tyrosine kinase(s) upon B-cell antigen receptor-mediated signaling. Proc Natl Acad Sci U S A 1993; 90:3631-5. [PMID: 7682714 PMCID: PMC46355 DOI: 10.1073/pnas.90.8.3631] [Citation(s) in RCA: 127] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Crosslinking of membrane-bound immunoglobulins, which are B-cell antigen receptors, causes proliferation and differentiation of B cells or inhibition of their growth. The receptor-mediated signaling involves tyrosine phosphorylation of cellular proteins and rapid activation of Src-like kinases. The amino acid sequences of five proteolytic peptides of p75, a major substrate of protein-tyrosine(s) in the signaling, showed that p75 is the human HS1 gene product. The HS1 gene is expressed specifically in hematopoietic cells and encodes p75HS1, which carries both helix-turn-helix and Src homology 3 motifs. p75HS1 showed rapid tyrosine phosphorylation and association with a Src-like kinase, Lyn, after crosslinking of membrane-bound IgM. Thus, p75HS1 may be an important substrate of Lyn and possibly other protein-tyrosine kinases upon B-cell antigen receptor-mediated signaling.
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Affiliation(s)
- Y Yamanashi
- Department of Oncology, University of Tokyo, Japan
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39
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Hurley TR, Amrein KE, Sefton BM. Creation and characterization of temperature-sensitive mutants of the lck tyrosine protein kinase. J Virol 1992; 66:7406-13. [PMID: 1279202 PMCID: PMC240447 DOI: 10.1128/jvi.66.12.7406-7413.1992] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Temperature-sensitive mutants of the lck tyrosine protein kinase were created by the introduction of mutations known to cause temperature sensitivity of the v-src tyrosine protein kinase of Rous sarcoma virus. p56lck activated by mutation of the regulatory site of tyrosine phosphorylation, Tyr-505, to Phe transforms fibroblasts in culture. Mutations identical to those responsible for the temperature-sensitive phenotypes of the tsNY68 and tsNY72-4 v-src mutants rendered this activated lck gene temperature sensitive for both morphological transformation and induction of growth in soft agar. The mutant proteins were incapable of cellular transformation at the nonpermissive temperature in part because of failure of the lck protein to accumulate to normal levels. Morphological transformation of fibroblasts was detectable within 24 h of a shift of cells to the permissive temperature and was essentially complete in 48 to 72 h. These mutants should prove useful for the study of the function of the lck kinase in hematopoietic cells.
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Affiliation(s)
- T R Hurley
- Molecular Biology and Virology Laboratory, Salk Institute, San Diego, California 92186-5800
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40
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Yellen-Shaw AJ, Monroe JG. Developmentally regulated association of a 56-kD member of the surface immunoglobulin M receptor complex. J Exp Med 1992; 176:129-37. [PMID: 1613455 PMCID: PMC2119291 DOI: 10.1084/jem.176.1.129] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Immature and mature B cells differ in the signals generated and transduced through their antigen receptor, surface immunoglobulin M (sIgM). Whereas signals generated through sIgM on mature B cells initiate a program leading to the positive activation of these cells, signaling through this receptor at the immature stage of development leads to a state of induced unresponsiveness or tolerance. Our previous studies have described developmental differences in sIgM transmembrane signaling that are independent of ligand-receptor affinity. In an attempt to understand the molecular basis for signaling differences between immature and mature B cells, we have analyzed the sIgM receptor complex in neonatal and adult mouse splenic B cells. While previously described components of this complex do not exhibit marked developmentally regulated differences in their association with sIgM, we have identified a 56-kD protein that associates with sIgM in mature (antigen-responsive), but not immature (tolerance-sensitive) B cells. This protein (p56) associates with sIgM as a homodimer, is constitutively phosphorylated on tyrosine, and is coimmunoprecipitated with IgM but not IgD. The observed inability to iodinate p56 suggests it is an intracellular component of the receptor complex. Based upon its migration in one- and two-dimensional gel electrophoresis we show, however, that p56 is distinct from the blk, lyn, or fyn src family kinases that have been shown to be associated with sIgM in mature B cells. The developmentally regulated participation of p56 in the B cell antigen receptor complex suggests a role in the differential signaling mediated via sIgM on immature and mature B cells.
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Affiliation(s)
- A J Yellen-Shaw
- Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia 19104
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