Jordan Martha S, Smith Jennifer E, Burns Jeremy C, Austin Jessica-Elise T, Nichols Kim E, Aschenbrenner Anna C, Koretzky Gary A
Cancer Biology, Abramson Family Cancer Research Institute, 427 BRBII/III, University of Pennsylvania School of Medicine, Philadelphia, PA, 19104, USA.
Immunity. 2008 Mar;28(3):359-69. doi: 10.1016/j.immuni.2008.01.010.
The adaptor protein SLP76 directs signaling downstream of the T cell receptor (TCR) and is essential for thymocyte development. SLP76 contains three N-terminal tyrosines that are critical for its function. To define the role of these residues in thymocyte development, we generated two lines of "knock-in" mice, one expressing a mutation in tyrosine 145 (Y145F) and a second harboring two point mutations at tyrosines 112 and 128 (Y112-128F). We show here that although thymocyte development requires both Y145- and Y112-128-generated signals, selection was more dependent upon Y145. Although several proximal TCR signaling events were defective in both mutant mice, phosphorylation of the guanine nucleotide exchange factor, Vav1, and activation of Itk-dependent pathways were differentially affected by mutations at Y112-128 and Y145, respectively. Analysis of mice expressing one Y145F and one Y112-128F allele revealed that these mutants could complement one another in trans, demonstrating cooperativity between two or more SLP76 molecules. Thus, the N-terminal tyrosines of SLP76 are required for thymocyte selection but can function on separate molecules to support TCR signaling.
衔接蛋白SLP76指导T细胞受体（TCR）下游的信号传导，对胸腺细胞发育至关重要。SLP76含有三个N端酪氨酸，这些酪氨酸对其功能至关重要。为了确定这些残基在胸腺细胞发育中的作用，我们构建了两系“敲入”小鼠，一系表达酪氨酸145（Y145F）的突变，另一系在酪氨酸112和128处有两个点突变（Y112 - 128F）。我们在此表明，虽然胸腺细胞发育需要Y145和Y112 - 128产生的信号，但选择更依赖于Y145。虽然在两种突变小鼠中几个近端TCR信号事件都有缺陷，但鸟嘌呤核苷酸交换因子Vav1的磷酸化以及Itk依赖途径的激活分别受到Y112 - 128和Y145处突变的不同影响。对表达一个Y145F和一个Y112 - 128F等位基因的小鼠的分析表明，这些突变体可以在反式中相互补充，证明了两个或更多SLP76分子之间的协同作用。因此，SLP76的N端酪氨酸是胸腺细胞选择所必需的，但可以在不同分子上发挥作用以支持TCR信号传导。
