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Immunity. 2000 May;12(5):525-35.

LAT is essential for Fc(epsilon)RI-mediated mast cell activation.

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Laboratory of Cellular and Molecular Biology, Division of Basic Science, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA.


The linker molecule LAT is a substrate of the tyrosine kinases activated following TCR engagement of T cells. LAT is also expressed in platelets, NK, and mast cells. Although LAT-deficient mice contain normal numbers of mast cells, we found that LAT-deficient mice were resistant to IgE-mediated passive systemic anaphylaxis. LAT-deficient bone marrow-derived mast cells (BMMC) showed normal growth and development. Whereas tyrosine phosphorylation of Fc(epsilon)RI, Syk, and Vav was intact in LAT-deficient BMMCs following Fc(epsilon)RI engagement, tyrosine phosphorylation of SLP-76, PLC-gamma1, and PLC-gamma2 and calcium mobilization were dramatically reduced. LAT-deficient BMMCs also exhibited profound defects in activation of MAPK, degranulation, and cytokine production after Fc(epsilon)RI cross-linking. These results show that LAT plays a critical role in Fc(epsilon)RI-mediated signaling in mast cells.

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