Reconstitution of B Cell Antigen Receptor-induced Signaling Events in a Nonlymphoid Cell Line by Expressing the Syk Protein-tyrosine Kinase

Richards, Jennifer C.; Gold, Michael R.; Hourihane, Sharon L.; DeFranco, Anthony L.; Matsuuchi, Linda

doi:10.1074/jbc.271.11.6458

Cited by 52 publications

(39 citation statements)

References 50 publications

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“…Stimulation of the ectopically expressed BCR in mouse pituitary cells fails to elicit tyrosine phosphorylation of downstream signaling elements. Coexpression of Syk restores this response, leading to phosphorylation of Shc and MAPK activation (38). Similarly, MAPK activation following crosslinking of an interleukin 2 (IL-2) receptor-FcεRI ␥-chain chimera in Cos-7 cells is dependent on the coexpression of Syk (48).…”

Section: Fig 11 (A) Sykmentioning

confidence: 99%

“…Syk is activated, either as a direct result of SH2 binding to the phospho-ITAM or through transphosphorylation by a Src family kinase (6,31,40,43,56). Activated Syk can phosphorylate downstream targets (38) and recruits additional SH2-containing proteins that bind to pTyr sites in its SH2-kinase linker region (33). The related tyrosine kinase ZAP-70 appears to play a similar role in signaling from the T-cell receptor (TCR) (2,53).…”

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confidence: 99%

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The Syk Protein Tyrosine Kinase Is Essential for Fcγ Receptor Signaling in Macrophages and Neutrophils

Kiefer

Brumell

Al-Alawi

et al. 1998

Molecular and Cellular Biology

354

307

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The cytoplasmic protein tyrosine kinase Syk has two amino-terminal SH2 domains that engage phosphorylated immunoreceptor tyrosine-based activation motifs in the signaling subunits of immunoreceptors. Syk, in conjunction with Src family kinases, has been implicated in immunoreceptor signaling in both lymphoid and myeloid cells. We have investigated the role of Syk in Fc␥ receptor (Fc␥R)-dependent and -independent responses in bone marrow-derived macrophages and neutrophils by using mouse radiation chimeras reconstituted with fetal liver cells from Syk ؊/؊ embryos. Chimeric mice developed an abdominal hemorrhage starting 2 to 3 months after transplantation that was ultimately lethal. Syk-deficient neutrophils derived from the bone marrow were incapable of generating reactive oxygen intermediates in response to Fc␥R engagement but responded normally to tetradecanoyl phorbol acetate stimulation. Syk-deficient macrophages were defective in phagocytosis induced by Fc␥R but showed normal phagocytosis in response to complement. The tyrosine phosphorylation of multiple cellular polypeptides, including the Fc␥R ␥ chain, as well as Erk2 activation, was compromised in Syk ؊/؊ macrophages after Fc␥R stimulation. In contrast, the induction of nitric oxide synthase in macrophages stimulated with lipopolysaccharide and gamma interferon was not dependent on Syk. Surprisingly, Syk-deficient macrophages were impaired in the ability to survive or proliferate on plastic petri dishes. Taken together, these results suggest that Syk has specific physiological roles in signaling from Fc␥Rs in neutrophils and macrophages and raise the possibility that in vivo, Syk is involved in signaling events other than those mediated by immunoreceptors.The cytoplasmic tyrosine kinase Syk has been implicated in a variety of hematopoietic cell responses, including immunoreceptor (1,3,4,12,22,29,44) and integrin signaling (7, 15). Syk possesses two N-terminal SH2 domains that bind in tandem to closely spaced pTyr sites located within the immunoreceptor tyrosine-based activation motifs (ITAMs) of antigen receptor subunits, such as the ␣ and ␤ chains associated with surface immunoglobulin M (IgM) in B cells (30) or the ␥ and ␤ subunits of FcεRI in mast cells (27,42).Engagement of the B-cell antigen receptor (BCR) has been suggested to result in the activation of Src family kinases, followed by phosphorylation of ITAMs and, consequently, recruitment of the Syk SH2 domains. Syk is activated, either as a direct result of SH2 binding to the phospho-ITAM or through transphosphorylation by a Src family kinase (6,31,40,43,56). Activated Syk can phosphorylate downstream targets (38) and recruits additional SH2-containing proteins that bind to pTyr sites in its SH2-kinase linker region (33). The related tyrosine kinase ZAP-70 appears to play a similar role in signaling from the T-cell receptor (TCR) (2, 53).Targeted mutagenesis of the Syk gene (5, 50) has revealed important functions for this kinase in B-and T-cell development, in BCR signaling, in macrophages, in...

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Section: Fig 11 (A) Sykmentioning

confidence: 99%

mentioning

confidence: 99%

The Syk Protein Tyrosine Kinase Is Essential for Fcγ Receptor Signaling in Macrophages and Neutrophils

Kiefer

Brumell

Al-Alawi

et al. 1998

Molecular and Cellular Biology

354

307

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“…An additional possibility is supported by the fact that Syk is phosphorylated to some extent in response to BCR aggregation in Lyn-de®cient DT40 B cells and in the CD45-de®cient lymphoma cell line J558Lmm3 in which Src-family kinases' recruitment to and activation by the BCR are inhibited. Furthermore, Syk has been shown to co-precipitate with the resting BCR (Hutchcroft et al, 1992), providing a possible mechanism for a Syk-mediated phosphorylation of ITAM tyrosyl residues upon BCR aggregation (Richards et al, 1996). The ability of Syk to tyrosyl phosphorylate both a z-derived ITAM-bearing peptide in-vitro as well as a z-bearing chimera in transiently transfected Cos-1 cells has been demonstrated (Latour et al, 1997).…”

Section: Syk and Zap-70 Recruitment And Activationmentioning

confidence: 99%

Antigen receptor signaling: integration of protein tyrosine kinase functions

1998

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“…Although Ig␣ and Ig␤ both contain ITAMs, Ig␤ may serve to regulate Ig␣ phosphorylation rather than initiate primary signaling (15,36,42,51). Once phosphorylated, the Ig␣ ITAM recruits and activates the tyrosine kinase Syk (50), which is both necessary (38,49) and sufficient (37) to initiate many BCR-mediated signaling pathways. While the processes regulating Syk activation are well defined, the mechanisms linking Syk to downstream effectors are unclear.…”

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confidence: 99%

The Direct Recruitment of BLNK to Immunoglobulin α Couples the B-Cell Antigen Receptor to Distal Signaling Pathways

Kabak

Skaggs

Gold

et al. 2002

Molecular and Cellular Biology

Self Cite

120

121

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Following B-cell antigen receptor (BCR) ligation, the cytoplasmic domains of immunoglobulin ␣ (Ig␣) and Ig␤ recruit Syk to initiate signaling cascades. The coupling of Syk to several distal substrates requires linker protein BLNK. However, the mechanism by which BLNK is recruited to the BCR is unknown. Using chimeric receptors with wild-type and mutant Ig␣ cytoplasmic tails we show that the non-immunoreceptor tyrosinebased activation motif (ITAM) tyrosines, Y176 and Y204, are required to activate BLNK-dependent pathways. Subsequent analysis demonstrated that BLNK bound directly to phospho-Y204 and that fusing BLNK to mutated Ig␣ reconstituted downstream signaling events. Moreover, ligation of the endogenous BCR induced Y204 phosphorylation and BLNK recruitment. These data demonstrate that the non-ITAM tyrosines of Ig␣ couple Syk activation to BLNK-dependent pathways.Specific immune responses to foreign antigens require one or more of a family of multimeric receptors including the B-cell antigen receptor (BCR), the T-cell antigen receptor, and the Fc receptors (2, 9). Each consists of an antigen-specific subunit noncovalently associated with signal-transducing subunits (35). Within the BCR complex, membrane-bound immunoglobulin (Ig) recognizes antigen and the Ig␣/Ig␤ heterodimer activates key signaling molecules including phospholipase C-␥ (PLC-␥), Ras, Rac, extracellular signalregulated kinase (ERK), and c-Jun NH 2 -terminal kinase (JNK) (7,11,13,27,32). Coordinated activation of these effectors controls cell differentiation, proliferation, and development.BCR aggregation induces phosphorylation of conserved tyrosines in the immunoreceptor tyrosine-based activation motifs (ITAMs) (8, 48) present in the cytoplasmic tails of Ig␣ and Ig␤ (20,25). ITAM phosphorylation is mediated by Src family tyrosine kinases assembled with the resting BCR (6, 16). Although Ig␣ and Ig␤ both contain ITAMs, Ig␤ may serve to regulate Ig␣ phosphorylation rather than initiate primary signaling (15,36,42,51). Once phosphorylated, the Ig␣ ITAM recruits and activates the tyrosine kinase Syk (50), which is both necessary (38, 49) and sufficient (37) to initiate many BCR-mediated signaling pathways. While the processes regulating Syk activation are well defined, the mechanisms linking Syk to downstream effectors are unclear.The linker protein BLNK (21), also known as SLP-65 (63) and BASH (22), is preferentially expressed in B cells. BLNK phosphorylation is dependent on Syk, and cotransfection studies indicate that BLNK is a direct substrate (21,22,28,63). (33,34,47,64) and has been implicated in human immunodeficiency (43). Deletion of BLNK in DT40 cells blocks BCR-induced JNK and PLC-␥2 activation (30). Expression of BLNK is required for normal B-cell development in miceBLNK contains a carboxy-terminal Src homology 2 (SH2) domain, a proline-rich region, and 13 potential tyrosine phosphorylation sites (21). Six of these tyrosines are part of YXXP motifs, predicted to bind the SH2 domains of PLC-␥, Vav, and Nck (55,56). In addition, the SH2...

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Reconstitution of B Cell Antigen Receptor-induced Signaling Events in a Nonlymphoid Cell Line by Expressing the Syk Protein-tyrosine Kinase

Cited by 52 publications

References 50 publications

The Syk Protein Tyrosine Kinase Is Essential for Fcγ Receptor Signaling in Macrophages and Neutrophils

The Syk Protein Tyrosine Kinase Is Essential for Fcγ Receptor Signaling in Macrophages and Neutrophils

Antigen receptor signaling: integration of protein tyrosine kinase functions

The Direct Recruitment of BLNK to Immunoglobulin α Couples the B-Cell Antigen Receptor to Distal Signaling Pathways

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