Open AccessSeparate signaling events control TCR downregulation and T cell activation in primary human T cells
Author(s) -
Donk Lieve E. H.,
Ates Louis S.,
Spek Jet,
Tukker Laura M.,
Geijtenbeek Teunis B. H.,
Heijst Jeroen W. J.
Publication year - 2021
Publication title -
immunity, inflammation and disease
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.918
H-Index - 18
ISSN - 2050-4527
DOI - 10.1002/iid3.383
Subject(s) - downregulation and upregulation , t cell receptor , fyn , jurkat cells , microbiology and biotechnology , t cell , biology , tyrosine kinase , cd3 , signal transduction , tyrosine protein kinase csk , cd8 , immunology , sh2 domain , antigen , immune system , biochemistry , gene
Abstract Introduction T‐cell antigen receptor (TCR) interaction with cognate peptide:MHC complexes trigger clustering of TCR:CD3 complexes and signal transduction. Triggered TCR:CD3 complexes are rapidly internalized and degraded in a process called ligand‐induced TCR downregulation. Classic studies in immortalized T‐cell lines have revealed a major role for the Src family kinase Lck in TCR downregulation. However, to what extent a similar mechanism operates in primary human T cells remains unclear. Methods Here, we developed an anti‐CD3‐mediated TCR downregulation assay, in which T‐cell gene expression in primary human T cells can be knocked down by microRNA constructs. In parallel, we used CRISPR/Cas9‐mediated knockout in Jurkat cells for validation experiments. Results We efficiently knocked down the expression of tyrosine kinases Lck, Fyn, and ZAP70, and found that, whereas this impaired T cell activation and effector function, TCR downregulation was not affected. Although TCR downregulation was marginally inhibited by the simultaneous knockdown of Lck and Fyn, its full abrogation required broad‐acting tyrosine kinase inhibitors. Conclusions These data suggest that there is substantial redundancy in the contribution of individual tyrosine kinases to TCR downregulation in primary human T cells. Our results highlight that TCR downregulation and T cell activation are controlled by different signaling events and illustrate the need for further research to untangle these processes.