Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 6 de 6
Filtrar
Mais filtros

Base de dados
Tipo de documento
País de afiliação
Intervalo de ano de publicação
1.
BMC Immunol ; 13: 23, 2012 Apr 26.
Artigo em Inglês | MEDLINE | ID: mdl-22537350

RESUMO

BACKGROUND: Activation signals can be negatively regulated by cell surface receptors bearing immunoreceptor tyrosine-based inhibitory motifs (ITIMs). CD300a, an ITIM bearing type I transmembrane protein, is expressed on many hematopoietic cells, including subsets of lymphocytes. RESULTS: We have taken two approaches to further define the mechanism by which CD300a acts as an inhibitor of immune cell receptor signaling. First, we have expressed in Jurkat T cells a chimeric receptor consisting of the extracellular domains of killer-cell immunoglobulin-like receptor (KIR)2DL2 fused to the transmembrane and cytoplasmic segments of CD300a (KIR-CD300a) to explore surrogate ligand-stimulated inhibition of superantigen stimulated T cell receptor (TCR) mediated cell signaling. We found that intact CD300a ITIMs were essential for inhibition and that the tyrosine phosphorylation of these ITIMs required the src tyrosine kinase Lck. Tyrosine phosphorylation of the CD300a ITIMs created docking sites for both src homology 2 domain containing protein tyrosine phosphatase (SHP)-1 and SHP-2. Suppression of SHP-1 and SHP-2 expression in KIR-CD300a Jurkat T cells with siRNA and the use of DT40 chicken B cell lines expressing CD300a and deficient in several phosphatases revealed that SHP-1, but not SHP-2 or the src homology 2 domain containing inositol 5' phosphatase SHIP, was utilized by CD300a for its inhibitory activity. CONCLUSION: These studies provide new insights into the function of CD300a in tuning T and B cell responses.


Assuntos
Antígenos CD/metabolismo , Linfócitos B/metabolismo , Receptores Imunológicos/metabolismo , Transdução de Sinais/fisiologia , Linfócitos T/metabolismo , Animais , Linhagem Celular , Galinhas , Humanos , Inositol Polifosfato 5-Fosfatases , Células Jurkat , Ativação Linfocitária , Proteína Tirosina Quinase p56(lck) Linfócito-Específica/metabolismo , Monoéster Fosfórico Hidrolases/metabolismo , Proteína Tirosina Fosfatase não Receptora Tipo 11/metabolismo , Proteína Tirosina Fosfatase não Receptora Tipo 6/metabolismo
2.
BMC Immunol ; 12: 62, 2011 Nov 02.
Artigo em Inglês | MEDLINE | ID: mdl-22046970

RESUMO

BACKGROUND: Human memory CD4+ T cells can be either CD300a/c+ or CD300a/c- and subsequent analyses showed that CD4+ effector memory T (T(EM)) cells are mostly CD300a/c+, whereas CD4+ central memory T (T(CM)) cells have similar frequencies of CD300a/c+ and CD300a/c- cells. RESULTS: Extensive phenotypical and functional characterization showed that in both T(CM) and T(EM) cells, the CD300a/c+ subset contained a higher number of TH1 (IFN-γ producing) cells. Alternatively, TH17 (IL-17a producing) cells tend to be CD300a/c-, especially in the T(EM) subset. Further characterization of the IL-17a+ cells showed that cells that produce only this cytokine are mostly CD300a/c-, while cells that produce IL-17a in combination with other cytokines, especially IFN-γ, are mostly CD300a/c+, indicating that the expression of this receptor is associated with cells that produce IFN-γ. Co-ligation of the TCR and CD300a/c in CD4+ T cells inhibited Ca2+ mobilization evoked by TCR ligation alone and modulated IFN-γ production on TH1 polarized cells. CONCLUSION: We conclude that the CD300a/c receptors are differentially expressed on human TH1 and TH17 cells and that their ligation is capable of modulating TCR mediated signals.


Assuntos
Antígenos CD/metabolismo , Antígenos de Superfície/metabolismo , Glicoproteínas de Membrana/metabolismo , Receptores Imunológicos/metabolismo , Subpopulações de Linfócitos T/metabolismo , Células Th1/metabolismo , Células Th17/metabolismo , Antígenos CD/genética , Antígenos CD/imunologia , Antígenos de Superfície/genética , Antígenos de Superfície/imunologia , Sinalização do Cálcio/imunologia , Diferenciação Celular/imunologia , Linhagem da Célula/imunologia , Células Cultivadas , Regulação da Expressão Gênica/imunologia , Humanos , Memória Imunológica , Imunofenotipagem , Interferon gama/metabolismo , Interleucina-17/metabolismo , Ativação Linfocitária , Glicoproteínas de Membrana/genética , Glicoproteínas de Membrana/imunologia , Receptor Cross-Talk/imunologia , Receptores de Antígenos de Linfócitos T alfa-beta/imunologia , Receptores de Antígenos de Linfócitos T alfa-beta/metabolismo , Receptores Imunológicos/genética , Receptores Imunológicos/imunologia , Subpopulações de Linfócitos T/imunologia , Subpopulações de Linfócitos T/patologia , Células Th1/imunologia , Células Th1/patologia , Células Th17/imunologia , Células Th17/patologia
3.
Oncogene ; 22(16): 2493-503, 2003 Apr 24.
Artigo em Inglês | MEDLINE | ID: mdl-12717426

RESUMO

The oncoprotein 70Z/3 Cbl signals in an autonomous fashion or through blockade of endogenous c-Cbl, a negative regulator of signaling. The mechanism of 70Z/3 Cbl-induced signaling was investigated by comparing the molecular requirements for 70Z/3 Cbl- and TCR-induced phospholipase C gamma 1 (PLC gamma 1) activation. 70Z/3 Cbl-induced PLC gamma 1 tyrosine phosphorylation required, in addition to the PLC gamma 1 N-terminal SH2 domain, the C-terminal SH2 and SH3 domains that were dispensable for TCR-induced phosphorylation. Deletion of the leucine zipper of 70Z/3 Cbl did not eliminate 70Z/3 Cbl-induced PLC gamma 1 phosphorylation, suggesting that blockage of c-Cbl via dimerization with 70Z/3 Cbl cannot fully explain 70Z/3 Cbl activating characteristics. The complete elimination of PLC gamma 1 phosphorylation required deleting the SH3 domain-binding region of 70Z/3 Cbl, consistent with 70Z/3 Cbl binding the PLC gamma 1 SH3 domain. 70Z/3 Cbl-induced PLC gamma 1 phosphorylation required Zap-70, as for the TCR, and the tyrosine kinase binding domain of 70Z/3 Cbl, which binds Zap-70, but did not require PLC gamma 1 binding to Lat, a crucial interaction in TCR-induced PLC gamma 1 phosphorylation. Furthermore, 70Z/3 Cbl-induced activation of NFAT, a PLC gamma 1/Ca(2+)-dependent transcriptional event, required Zap-70, but was independent of Slp-76, an adapter required for TCR-induced NFAT activation. These results suggest that 70Z/3 Cbl and PLC gamma 1 form a TCR-, Lat- and Slp-76-independent complex that leads to PLC gamma 1 phosphorylation and activation.


Assuntos
Proteínas Adaptadoras de Transdução de Sinal , Proteínas de Membrana , Proteínas Nucleares , Proteínas Oncogênicas de Retroviridae/genética , Transdução de Sinais/fisiologia , Linfócitos T/metabolismo , Fosfolipases Tipo C/genética , Proteínas de Transporte/metabolismo , Proteínas de Ligação a DNA/metabolismo , Humanos , Células Jurkat , Fatores de Transcrição NFATC , Proteína Oncogênica v-cbl , PTEN Fosfo-Hidrolase , Fosfolipase C gama , Fosfoproteínas/metabolismo , Monoéster Fosfórico Hidrolases/metabolismo , Fosforilação , Proteínas Tirosina Quinases/metabolismo , Receptores de Antígenos de Linfócitos T/metabolismo , Fatores de Transcrição/metabolismo , Proteínas Supressoras de Tumor/metabolismo , Proteína-Tirosina Quinase ZAP-70
5.
J Cell Biol ; 184(3): 451-62, 2009 Feb 09.
Artigo em Inglês | MEDLINE | ID: mdl-19204146

RESUMO

Mechanisms controlling the disassembly of ezrin/radixin/moesin (ERM) proteins, which link the cytoskeleton to the plasma membrane, are incompletely understood. In lymphocytes, chemokine (e.g., SDF-1) stimulation inactivates ERM proteins, causing their release from the plasma membrane and dephosphorylation. SDF-1-mediated inactivation of ERM proteins is blocked by phospholipase C (PLC) inhibitors. Conversely, reduction of phosphatidylinositol 4,5-bisphosphate (PIP2) levels by activation of PLC, expression of active PLC mutants, or acute targeting of phosphoinositide 5-phosphatase to the plasma membrane promotes release and dephosphorylation of moesin and ezrin. Although expression of phosphomimetic moesin (T558D) or ezrin (T567D) mutants enhances membrane association, activation of PLC still relocalizes them to the cytosol. Similarly, in vitro binding of ERM proteins to the cytoplasmic tail of CD44 is also dependent on PIP2. These results demonstrate a new role of PLCs in rapid cytoskeletal remodeling and an additional key role of PIP2 in ERM protein biology, namely hydrolysis-mediated ERM inactivation.


Assuntos
Membrana Celular/metabolismo , Proteínas do Citoesqueleto/metabolismo , Linfócitos , Proteínas de Membrana/metabolismo , Proteínas dos Microfilamentos/metabolismo , Fosfatidilinositol 4,5-Difosfato/metabolismo , Fosfolipases Tipo C/metabolismo , Animais , Quimiocina CXCL12/metabolismo , Proteínas do Citoesqueleto/genética , Citoesqueleto/metabolismo , Ativação Enzimática , Humanos , Receptores de Hialuronatos/metabolismo , Células Jurkat , Linfócitos/citologia , Linfócitos/metabolismo , Proteínas de Membrana/genética , Proteínas dos Microfilamentos/genética , Monoéster Fosfórico Hidrolases/metabolismo , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Transdução de Sinais/fisiologia , Fosfolipases Tipo C/antagonistas & inibidores
6.
Exp Cell Res ; 289(1): 184-94, 2003 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-12941616

RESUMO

We investigated the structural requirements for c-Cbl-mediated inhibition of Ag receptor-induced PLCgamma1 activation. Analysis of site-specific c-Cbl mutants indicated that tyrosine phosphorylation of c-Cbl was required for down-regulation of the PLCgamma1/Ca2+ pathway. Coprecipitation experiments indicated that c-Cbl and PLCgamma1 constitutively interact through a PLCgamma1 SH3 domain-dependent mechanism and that c-Cbl and PLCgamma1 can inducibly interact through the SH2(C) domain of PLCgamma1. Additional data indicate that the SH3 domain of PLCgamma1 binds to both canonical and noncanonical SH3 domain-binding sites in the proline-rich region of c-Cbl. Overexpression of c-Cbl in a PLCgamma-deficient B cell line, P10-14, stably reconstituted with wild-type PLCgamma1 led to a significant decrease in B cell receptor-induced NF-AT-dependent transcription, a PLCgamma- and Ca(2+)-dependent event. In contrast, c-Cbl overexpression in P10-14 cells reconstituted with a PLCgamma1 SH3 domain mutant had little effect on receptor-induced NF-AT activation. These data suggest that c-Cbl-mediated regulation of PLCgamma1 requires an interaction between c-Cbl and PLCgamma1 that is primarily mediated by the SH3 domain of PLCgamma1. The interaction of c-Cbl with PLCgamma1 may negatively effect events required for PLCgamma1 activation.


Assuntos
Linfócitos/metabolismo , Proteínas Nucleares , Proteínas Proto-Oncogênicas/metabolismo , Receptores de Antígenos/metabolismo , Fosfolipases Tipo C/metabolismo , Ubiquitina-Proteína Ligases , Domínios de Homologia de src/imunologia , Animais , Sítios de Ligação/imunologia , Proteínas de Ligação a DNA/metabolismo , Regulação para Baixo/imunologia , Retroalimentação Fisiológica/imunologia , Humanos , Células Jurkat , Linfócitos/imunologia , Mutação/genética , Fatores de Transcrição NFATC , Fosfolipase C gama , Fosforilação , Prolina/imunologia , Ligação Proteica/imunologia , Proteínas Proto-Oncogênicas/genética , Proteínas Proto-Oncogênicas/imunologia , Proteínas Proto-Oncogênicas c-cbl , Receptores de Antígenos/imunologia , Fatores de Transcrição/metabolismo , Ativação Transcricional/imunologia , Fosfolipases Tipo C/imunologia , Tirosina/metabolismo
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA