Mutation of the glycine residue preceding the sixth tyrosine of the LAT adaptor severely alters T cell development and activation

Mikel M Arbulo-Echevarria (1) , Inmaculada Vico-Barranco (1) , Fanghui Zhang (2, 3) , Luis M Fernandez-Aguilar (1) , Martyna Chotomska (1) , Isaac Narbona-Sánchez (1) , Lichen Zhang (3) , Bernard Malissen (2, 4) , Yinming Liang (3) , Enrique Aguado (1)

1 Universidad de Cádiz, Biotechnology and Public Health (Immunology)
2 CIML - Centre d'Immunologie de Marseille - Luminy
3 Xinxiang Medical University
4 CIPHE - Centre d'Immunophénomique

The LAT transmembrane adaptor is essential to transduce intracellular signals triggered by the TCR. Phosphorylation of its four C-terminal tyrosine residues (136, 175, 195, and 235 in mouse LAT) recruits several proteins resulting in the assembly of the LAT signalosome. Among those tyrosine residues, the one found at position 136 of mouse LAT plays a critical role for T cell development and activation. The kinetics of phosphorylation of this residue is delayed as compared to the three other C-terminal tyrosines due to a conserved glycine residue found at position 135. Mutation of this glycine into an aspartate residue (denoted LAT G135D ) increased TCR signaling and altered antigen recognition in human Jurkat T cells and ex vivo mouse T cells. Here, using a strain of LAT G135D knockin mice, we showed that the LAT G135D mutation modifies thymic development, causing an increase in the percentage of CD4+CD8+ double-positive cells, and a reduction in the percentage of CD4+ and CD8+ single-positive cells. Interestingly, the LAT G135D mutation alters thymic development even in a heterozygous state. In the periphery, the LAT G135D mutation reduces the percentage of CD8+ T cells and results in a small increment of γδ T cells. Remarkably, the LAT G135D mutation dramatically increases the percentage of central memory CD8+ T cells. Finally, analysis of the proliferation and activation of T lymphocytes shows increased responses of T cells from mutant mice. Altogether, our results reinforce the view that the residue preceding Tyr136 of LAT constitutes a crucial checkpoint in T cell development and activation.

Mots clés: linker for activation of T cell; TCR (T cell receptor); T cell development; anergy; T cell memory; T cell

Domaines: Sciences du Vivant [q-bio]

Mikel M Arbulo-Echevarria, Inmaculada Vico-Barranco, Fanghui Zhang, Luis M Fernandez-Aguilar, Martyna Chotomska, et al.. Mutation of the glycine residue preceding the sixth tyrosine of the LAT adaptor severely alters T cell development and activation. Frontiers in Immunology, 2022, 13, ⟨10.3389/fimmu.2022.1054920⟩. ⟨hal-03933550⟩