Bilal Mahmood Y, Zhang Elizabeth Y, Dinkel Brittney, Hardy Daimon, Yankee Thomas M, Houtman Jon C D
Interdisciplinary Graduate Program in Immunology, University of Iowa, Iowa City, IA 52242, United States.
Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, KS 66160, United States.
Cell Signal. 2015 Apr;27(4):841-50. doi: 10.1016/j.cellsig.2015.01.012. Epub 2015 Jan 28.
GRB2 related adaptor protein downstream of Shc (GADS) is a member of the GRB2 family of adaptors and is critical for TCR-induced signaling. The current model is that GADS recruits SLP-76 to the LAT complex, which facilitates the phosphorylation of SLP-76, the activation of PLC-γ1, T cell adhesion and cytokine production. However, this model is largely based on studies of disruption of the GADS/SLP-76 interaction and murine T cell differentiation in GADS deficient mice. The role of GADS in mediating TCR-induced signals in human CD4+ T cells has not been thoroughly investigated. In this study, we have suppressed the expression of GADS in human CD4+ HuT78 T cells. GADS deficient HuT78 T cells displayed similar levels of TCR-induced SLP-76 and PLC-γ1 phosphorylation but exhibited substantial decrease in TCR-induced IL-2 and IFN-γ release. The defect in cytokine production occurred because of impaired calcium mobilization due to reduced recruitment of SLP-76 and PLC-γ1 to the LAT complex. Surprisingly, both GADS deficient HuT78 and GADS deficient primary murine CD8+ T cells had similar TCR-induced adhesion when compared to control T cells. Overall, our results show that GADS is required for calcium influx and cytokine production, but not cellular adhesion, in human CD4+ T cells, suggesting that the current model for T cell regulation by GADS is incomplete.
Shc下游的GRB2相关衔接蛋白（GADS）是衔接蛋白GRB2家族的成员，对TCR诱导的信号传导至关重要。目前的模型认为，GADS将SLP-76招募到LAT复合物中，这有助于SLP-76的磷酸化、PLC-γ1的激活、T细胞黏附和细胞因子的产生。然而，该模型很大程度上基于对GADS缺陷小鼠中GADS/SLP-76相互作用破坏和小鼠T细胞分化的研究。GADS在介导人CD4+T细胞中TCR诱导信号方面的作用尚未得到充分研究。在本研究中，我们抑制了人CD4+HuT78 T细胞中GADS的表达。GADS缺陷的HuT78 T细胞显示出相似水平的TCR诱导的SLP-76和PLC-γ1磷酸化，但TCR诱导的IL-2和IFN-γ释放显著减少。细胞因子产生的缺陷是由于SLP-76和PLC-γ1向LAT复合物的募集减少导致钙动员受损。令人惊讶的是，与对照T细胞相比，GADS缺陷的HuT78和GADS缺陷的原代小鼠CD8+T细胞具有相似的TCR诱导黏附。总体而言，我们的结果表明，GADS是人CD4+T细胞中钙内流和细胞因子产生所必需的，但不是细胞黏附所必需的，这表明目前关于GADS调节T细胞的模型是不完整的。
