T cell receptor-dependent S-acylation of ZAP-70 controls activation of T cells

Abstract

ZAP-70 is a cytoplasmic tyrosine kinase essential for T cell-mediated immune responses. Upon engagement of the T cell receptor, ZAP-70 is quickly recruited to the specialized plasma membrane domains, becomes activated and released to phosphorylate its laterally segregated downstream targets. A shift in ZAP-70 distribution at the plasma membrane is recognized as a critical step in T cell receptor signal transduction and amplification. However, the molecular mechanism supporting stimulation-dependent plasma membrane compartmentalization of ZAP-70 remains poorly understood. In this study, we identified previously uncharacterized reversible lipidation (S-acylation) of ZAP-70. We found that this post-translational modification of ZAP-70 is dispensable for its enzymatic activity. However, the lipidation-deficient mutant of ZAP-70 failed to propagate the T cell receptor signaling cascade suggesting that S-acylation is essential for ZAP-70 interaction with its protein substrates. The kinetics of ZAP-70 S-acylation were consistent with early T cell signaling events indicating that agonist-induced S-acylation is a part of the signaling mechanism controlling T cell activation and function.Significance Statement Activation of T cells is a critical part of the adaptive immune response to pathogen exposure. We found that ZAP-70, a regulatory protein essential for T cell activation, can undergo a post-translational modification with long chain fatty acids, known as S-acylation. In this report, we show that S-acylation of ZAP-70 is T cell receptor-dependent and required for its signaling function. We found that loss of ZAP-70 S-acylation resulted in T cell unresponsiveness to T cell receptor stimulation indicating that abnormalities in protein S-acylation can potentially contribute to the T cell immunodeficiency disorders.Competing Interest StatementThe authors have declared no competing interest.View Full Text