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The adaptor protein linker for activation of T cells (LAT) has an essential role transducing activatory intracellular signals coming from the TCR/CD3 complex. Previous reports have shown that upon T-cell activation, LAT interacts with the tyrosine kinase Lck, leading to the inhibition of its kinase activity. LAT-Lck interaction seemed to depend on a stretch of negatively charged amino acids in LAT. Here, we have substituted this segment of LAT between amino acids 113 and 126 with a non-charged segment and expressed the mutant LAT (LAT-NIL) in J.CaM2 cells in order to analyze TCR signaling. Substitution of this segment in LAT prevented the activation-induced interaction with Lck. Moreover, cells expressing this mutant form of LAT showed a statistically significant increase of proximal intracellular signals such as phosphorylation of LAT in tyrosine residues 171 and 191, and also enhanced ZAP70 phosphorylation approaching borderline statistical significance (p = 0.051). Nevertheless, downstream signals such as Ca2+ influx or MAPK pathways were partially inhibited. Overall, our data reveal that LAT-Lck interaction constitutes a key element regulating proximal intracellular signals coming from the TCR/CD3 complex.

Original publication

DOI

10.3389/fimmu.2018.00115

Type

Journal article

Journal

Front immunol

Publication Date

2018

Volume

9

Keywords

CD3, LAT, Lck, TCR, signaling, Adaptor Proteins, Signal Transducing, Amino Acids, Cell Line, Humans, Lymphocyte Specific Protein Tyrosine Kinase p56(lck), Membrane Proteins, Receptors, Antigen, T-Cell, ZAP-70 Protein-Tyrosine Kinase