Wakizaka K, Masuda Y, Saito T
Center for Biomedical Science, Third Department of Internal Medicine, Chiba University School of Medicine, Japan.
Eur J Immunol. 1998 Feb;28(2):636-45. doi: 10.1002/(SICI)1521-4141(199802)28:02<636::AID-IMMU636>3.0.CO;2-A.
Ligation of the TCR-CD3 complex initiates a cascade of tyrosine phosphorylation that results in T cell activation. Initial activation of tyrosine kinases depends on the phosphorylation of activation motifs on CD3 chains. We previously found that a 90-kDa protein was tyrosine phosphorylated upon TCR cross-linking and the induction of the phosphorylation was dependent on the structure of the CD3 complex. In this study, we further characterized p90 phosphorylation. Phosphorylation of p90 was induced only by stimulation through the TCR-CD3 complex but not by other kinds of stimulation including CD28- or hydrogen peroxide-mediated activation and was dynamically regulated. Phosphorylated p90 was associated with the TCR-CD3 complex upon T cell activation. In a normal T cell population, thymocytes but not splenic T cells induced the tyrosine phosphorylation of p90 upon TCR cross-linking. These results suggest that p90 is a novel phosphoprotein associated with the TCR-CD3 complex and may play a role in TCR signaling during thymocyte differentiation.
TCR - CD3复合物的连接引发了一系列酪氨酸磷酸化反应，从而导致T细胞活化。酪氨酸激酶的初始活化取决于CD3链上活化基序的磷酸化。我们之前发现，一种90 kDa的蛋白质在TCR交联时会发生酪氨酸磷酸化，且磷酸化的诱导依赖于CD3复合物的结构。在本研究中，我们进一步对p90磷酸化进行了表征。p90的磷酸化仅由通过TCR - CD3复合物的刺激诱导产生，而不由包括CD28或过氧化氢介导的活化在内的其他类型刺激诱导产生，并且其受到动态调节。在T细胞活化时，磷酸化的p90与TCR - CD3复合物相关联。在正常T细胞群体中，胸腺细胞而非脾T细胞在TCR交联时会诱导p90的酪氨酸磷酸化。这些结果表明，p90是一种与TCR - CD3复合物相关的新型磷蛋白，可能在胸腺细胞分化过程中的TCR信号传导中发挥作用。
