Rosoff P M, Cantley L C
J Biol Chem. 1985 Nov 15;260(26):14053-9.
Three monoclonal antibodies reactive with different structural domains of the T3-T cell receptor complex of the human T cell leukemia line, HPB-ALL, were previously shown to activate a membrane potential-sensitive, La3+-inhibitable Ca2+ influx (Oettgen, H. C., Terhorst, C., Cantley, L. C., and Rosoff, P. M. (1985) Cell 40, 583-590). OKT3 (anti-T3), WT-31 (anti-receptor constant region), and T40/25 (anti-receptor variable region) also enhance the activity of the Na+/H+ exchanger in these cells. The associated rise in pHi was dependent on the presence of external Ca2+ and Na+, was inhibited by dimethylamiloride and La3+, and was maintained for at least 20 min. Phorbol esters, which are co-mitogenic in T cells and activate protein kinase C, also stimulated the exchanger, but by a mechanism not requiring an elevation in cytoplasmic Ca2+; the rise in pHi rapidly peaked and returned to baseline levels within 20 min. Pretreatment with phorbols prevented an increase in pHi by OKT3 although a transient additive effect was observed when the two were added simultaneously. Receptor function was maintained in the presence of phorbol esters as OKT3 still stimulated a Ca2+ influx. These data demonstrate the existence of two interdependent pathways to activate Na+/H+ exchange in T lymphocytes and suggest a pathway of internal regulation of antigen-activated signal transduction.
先前已表明，三种与人类T细胞白血病细胞系HPB-ALL的T3-T细胞受体复合物不同结构域发生反应的单克隆抗体可激活膜电位敏感的、La3+可抑制的Ca2+内流（Oettgen, H. C., Terhorst, C., Cantley, L. C., and Rosoff, P. M. (1985) Cell 40, 583 - 590）。OKT3（抗T3）、WT-31（抗受体恒定区）和T40/25（抗受体可变区）也可增强这些细胞中Na+/H+交换体的活性。细胞内pH值（pHi）的相关升高依赖于细胞外Ca2+和Na+的存在，被二甲基amiloride和La3+抑制，并至少维持20分钟。佛波酯在T细胞中具有协同促有丝分裂作用并激活蛋白激酶C，它也刺激交换体，但通过一种不需要细胞质Ca2+升高的机制；pHi的升高迅速达到峰值，并在20分钟内恢复到基线水平。用佛波酯预处理可阻止OKT3引起的pHi升高，尽管当两者同时添加时会观察到短暂的相加效应。在存在佛波酯的情况下，受体功能得以维持，因为OKT3仍能刺激Ca2+内流。这些数据证明了在T淋巴细胞中存在两条相互依赖的激活Na+/H+交换的途径，并提示了抗原激活信号转导的一种内在调节途径。
