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.
CITATION STYLE
Arbulo-Echevarria, M. M., Narbona-Sánchez, I., Fernandez-Ponce, C. M., Vico-Barranco, I., Rueda-Ygueravide, M. D., Dustin, M. L., … Aguado, E. (2018). A stretch of negatively charged amino acids of linker for activation of T-cell adaptor has a dual role in T-cell antigen receptor intracellular signaling. Frontiers in Immunology, 9(FEB). https://doi.org/10.3389/fimmu.2018.00115
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