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Sequential translocation of tyrosine kinases Lyn and Syk to the activated Fcç receptors during phagocytosis.
Folia Histochem. Cytobiol. 2002: 40 (2) s.131-132, il., bibliogr. 13 poz. - 37 Sympozjum Polskiego Towarzystwa Histochemików i Cytochemików Kraków 02-05.09. 2001
praca związana ze zjazdem
Tyrosine phosphorylation of numerous proteins is one of the earliest events detectable during Fcç receptor-mediated phagocytosis. We demonstrate that IgG-coated particles associated with the surface of macrophages are enriched with numerous rytosine-phosphorylated proteins. During particle internalization the proteins are still associated with particles but their phosphorylation is reduced. Lyn kinase is phosphorylated both at particle binding and internalization steps. The phosphorylated Syk kinase is the major kinase associated with engulfed particles. Immunofluorescent studies confirm spatial and temporal distribution of Lyn and Syk kinases at different stages of phagocytosis. Our data indicate that ligation of Fcç receptors activites Lyn followed by Syk kinase and in the results multimolecular complex of the kinases and several accompanying tyrosine phosphorylated proteins with Fcç receptors is organized leading to local reorganization of actin-based skeleton and particle uptake.
Lyn and syk kinases are sequentially engaged in phagocytosis mediated by FcçR.
J. Immunol. 2002: 169 (12) s.6787-6794, il., tab., bibliogr. 44 poz.
praca opublikowana za granicą
Recent data indicate that phagocytosis mediated by FcçRs is controlled by the Src and Syk families of protein tyrosine kinases. In this study, we demosntrate a sequential involvement of Lyn and Syk in the phagocytosis of IgG-coated particles. The particles isolated at the stage of their binding to FcçRs (4řC) were accompanied by high amounts of Lyn, in addition to the signaling ç-chain of FcçRs. Simultaneously, the particle binding induced rapid tyrosine phosphorylation of numerous proteins. During synchronized internalization of the particle induced by shifting the cell to 37řC, Syk kinase ans Src homology 2-containing tyrosine phosphatase-1 (SHP-1) were associated with the formed phagosomes. At this tep, most of the proteins were dephosphorylated, although some underwent further tyrosine phosphorylation. Quantitative immunoelectron microscopy studies confirmed that Lyn accumulated under the plasma membrane beneath the bound particles. High amounts of the ç-chain and tyrosine-phosphorylated proteins were also observed under the bound particles. When the particles ere internalized, the ç-chain was still detected in the region of the phagosomes, while amounts of Lyn were markedly reduced. In contrast, the vicinity of the phagosomes was heavily decorated with anti-Syk and anti-SHP-1 Abs. The local level of protein tyrosine phosphorylation was reduced. THe data indicate that the accumulation of Lyn during the binding of IgG-coated particles to FcçRs correlated with strong tyrosine phosphorylation of numerous proteins, suggesting an initiating role for Lyn in protein phosphorylation at the onset of the phagocytosis. Syk kinase and SHP-1 phosphatase are mainly engaged at the stage of particle internalization.
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