Gouy H, Cefai D, Christensen S B, Debré P, Bismuth G
Laboratoire d'Immunologie Cellulaire et Tissulaire, CNRS URA 186, CERVI, Paris, France.
Eur J Immunol. 1990 Oct;20(10):2269-75. doi: 10.1002/eji.1830201016.
Thapsigargin (TG), a sesquiterpene lactone and non-phorbol 12-myristate 13-acetate tumor promoter, stimulates a rapid increase in intracellular free Ca2+ [( Ca2+]i) in human T lymphocytes clone P28. The [Ca2+]i response to TG is sustained in the presence of 1 mM extracellular Ca2+, while it becomes transient in Ca2(+)-free medium suggesting that TG activates both the release of Ca2+ from intracellular stores and the entry of Ca2+ from extracellular spaces. TG-induced Ca2+ influx is completely abolished after cell depolarization caused by increased extracellular concentrations of K+. The rise in [Ca2+]i stimulated by TG occurs in the absence of detectable production of inositol phosphates. Moreover, TG does not alter the early biochemical events of T cell activation triggered through the CD2 or the CD3 T cell antigens. Indeed, both inositol phosphate production and intracellular pH increase induced by specific monoclonal antibodies (mAb) remain unchanged after TG treatment. These data suggest that in human T lymphocytes TG releases Ca2+ from an intracellular pool by a mechanism which is independent of the phospholipase C metabolic pathway. Preincubation with TG of T cell clone P28 empties both the CD2 and the CD3-sensitive intracellular Ca2+ pool(s). Conversely, prestimulation of T cell clone P28 by CD3 or CD2-specific mAb inhibits the Ca2(+)-mobilizing effect of TG. Thus it appears that TG and CD2- or CD3-specific mAb mobilize Ca2+ from common Ca2+ pool(s). Taken together, these results demonstrate that Ca2+ influx in human T cells may be linked to mobilization of intracellular Ca2+ pools and by a mechanism independent of phosphoinositide hydrolysis. They further indicate that the release of intracellular Ca2+ pool(s) may play a major role in the opening of cell membrane Ca2+ channels observed during the CD2- or CD3-induced stimulation of human T lymphocytes.
毒胡萝卜素（TG）是一种倍半萜内酯，而非佛波醇12 -肉豆蔻酸酯13 -乙酸酯肿瘤促进剂，它能刺激人T淋巴细胞克隆P28细胞内游离钙离子浓度[Ca2+]i迅速升高。在存在1 mM细胞外钙离子的情况下，[Ca2+]i对TG的反应持续存在，而在无钙离子的培养基中则变为瞬时反应，这表明TG既能激活细胞内钙库释放钙离子，又能促使细胞外钙离子内流。细胞外钾离子浓度升高导致细胞去极化后，TG诱导的钙离子内流完全被阻断。TG刺激引起的[Ca2+]i升高在未检测到肌醇磷酸生成的情况下发生。此外，TG不会改变通过CD2或CD3 T细胞抗原触发的T细胞激活的早期生化事件。实际上，特异性单克隆抗体（mAb）诱导的肌醇磷酸生成和细胞内pH升高在TG处理后保持不变。这些数据表明，在人T淋巴细胞中，TG通过一种独立于磷脂酶C代谢途径的机制从细胞内钙库释放钙离子。用TG预孵育人T细胞克隆P28会排空CD2和CD3敏感的细胞内钙库。相反，用CD3或CD2特异性mAb对人T细胞克隆P28进行预刺激会抑制TG的钙离子动员作用。因此，似乎TG和CD2或CD3特异性mAb从共同的钙库中动员钙离子。综上所述，这些结果表明人T细胞中的钙离子内流可能与细胞内钙库的动员有关，且机制独立于磷酸肌醇水解。它们进一步表明，细胞内钙库的释放可能在CD2或CD3诱导的人T淋巴细胞刺激过程中观察到的细胞膜钙离子通道开放中起主要作用。
