RESUMEN
ZAP-70 is a tyrosine kinase essential for T cell immune responses. Upon engagement of the T cell receptor (TCR), ZAP-70 is recruited to the specialized plasma membrane domains, becomes activated, and is released to phosphorylate its laterally segregated targets. A shift in ZAP-70 distribution at the plasma membrane is recognized as a critical step in TCR 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 lipidation (S-acylation) of ZAP-70 using Acyl-Biotin Exchange assay, a technique that selectively captures S-acylated proteins. We found that this posttranslational modification of ZAP-70 is dispensable for its enzymatic activity. However, the lipidation-deficient mutant of ZAP-70 failed to propagate the TCR pathway suggesting that S-acylation is essential for ZAP-70 interaction with its protein substrates. The kinetics of ZAP-70 S-acylation were consistent with TCR signaling events indicating that agonist-induced S-acylation is a part of the signaling mechanism controlling T cell activation and function. Taken together, our results suggest that TCR-induced S-acylation of ZAP-70 can serve as a critical regulator of T cell-mediated immunity.
Asunto(s)
Inmunidad Celular/genética , Receptores de Antígenos de Linfocitos T/genética , Linfocitos T/inmunología , Proteína Tirosina Quinasa ZAP-70/genética , Acilación/genética , Aciltransferasas/química , Aciltransferasas/genética , Membrana Celular/química , Membrana Celular/genética , Regulación Enzimológica de la Expresión Génica/genética , Humanos , Inmunidad Celular/inmunología , Lipoilación/genética , Mutación/genética , Procesamiento Proteico-Postraduccional/genética , Receptores de Antígenos de Linfocitos T/inmunología , Transducción de Señal/genética , Especificidad por Sustrato/genética , Linfocitos T/química , Proteína Tirosina Quinasa ZAP-70/químicaRESUMEN
S-acylation reversible-post-translational lipidation of cysteine residues-is emerging as an important regulatory mechanism in T cell signaling. Dynamic S-acylation is critical for protein recruitment into the T cell receptor complex and initiation of the subsequent signaling cascade. However, the enzymatic control of protein S-acylation in T cells remains poorly understood. Here, we report a previously uncharacterized role of DHHC21, a member of the mammalian family of DHHC protein acyltransferases, in regulation of the T cell receptor pathway. We found that loss of DHHC21 prevented S-acylation of key T cell signaling proteins, resulting in disruption of the early signaling events and suppressed expression of T cell activation markers. Furthermore, downregulation of DHHC21 prevented activation and differentiation of naïve T cells into effector subtypes. Together, our study provides the first direct evidence that DHHC protein acyltransferases can play an essential role in regulation of T cell-mediated immunity.
