Sancho J, Peter M E, Franco R, Danielian S, Kang J S, Fagard R, Woods J, Reed J C, Kamoun M, Terhorst C
Division of Immunology, Beth Israel Hospital, Boston, MA 02215.
J Immunol. 1993 Apr 15;150(8 Pt 1):3230-42.
The zeta-subunit of the TCR binds GTP and is a well characterized substrate for a TCR-activated tyrosine kinase. To examine the possible coupling of GTP-binding to zeta with TCR-mediated signal transduction, a mutant (termed J32-3.2) of the T cell line Jurkat (J32) was used. Anti-TCR/CD3 stimulation of the TCR/CD3+ J32-3.2 cells resulted in a weak stimulation of both the phosphatidyl inositol and tyrosine kinase signal transduction pathways, as measured by changes in the level of free intracellular calcium, tyrosine phosphorylation of TCR-zeta, CD3-epsilon and ZAP-70, p56lck, or p59fyn tyrosine kinase activity and IL-2 gene activation. The impaired responsiveness of J32-3.2 cells to anti-TCR/CD3 mAb correlated with a low basal level of GTP-binding to zeta. Furthermore, in J32-3.2 cells TCR activation by antibody ligation caused a weaker increase in GTP-binding to the zeta-chain, as compared with that of wild-type J32 cells, which indicates for the first time that GTP-binding to zeta can be modulated by extracellular signals and suggest that the role of GTP-binding to zeta is to couple the TCR to intracellular signal transduction mechanisms.
TCR的ζ亚基结合GTP，是TCR激活的酪氨酸激酶的一个特征明确的底物。为了研究ζ亚基的GTP结合与TCR介导的信号转导之间可能的偶联关系，使用了T细胞系Jurkat（J32）的一个突变体（称为J32 - 3.2）。通过测量细胞内游离钙水平的变化、TCR - ζ、CD3 - ε和ZAP - 70的酪氨酸磷酸化、p56lck或p59fyn酪氨酸激酶活性以及IL - 2基因激活情况，发现抗TCR/CD3刺激TCR/CD3 + J32 - 3.2细胞后，磷脂酰肌醇和酪氨酸激酶信号转导途径的刺激作用较弱。J32 - 3.2细胞对抗TCR/CD3单克隆抗体的反应性受损与ζ亚基的低基础GTP结合水平相关。此外，与野生型J32细胞相比，在J32 - 3.2细胞中，抗体连接引起的TCR激活导致ζ链GTP结合的增加较弱，这首次表明ζ亚基的GTP结合可被细胞外信号调节，并提示ζ亚基的GTP结合作用是将TCR与细胞内信号转导机制偶联起来。
