Szabò I, Lepple-Wienhues A, Kaba K N, Zoratti M, Gulbins E, Lang F
Department of Physiology, University of Tuebingen, Gmelinstrasse 5, 72076 Tuebingen, Germany.
Proc Natl Acad Sci U S A. 1998 May 26;95(11):6169-74. doi: 10.1073/pnas.95.11.6169.
CD95/Fas/APO-1 mediated apoptosis is an important mechanism in the regulation of the immune response. Here, we show that CD95 receptor triggering activates an outwardly rectifying chloride channel (ORCC) in Jurkat T lymphocytes. Ceramide, a lipid metabolite synthesized upon CD95 receptor triggering, also induces activation of ORCC in cell-attached patch clamp experiments. Activation is mediated by Src-like tyrosine kinases, because it is abolished by the tyrosine kinase inhibitor herbimycin A or by genetic deficiency of p56lck. In vitro incubation of excised patches with purified p56lck results in activation of ORCC, which is partially reversed upon addition of anti-phosphotyrosine antibody. Inhibition of ORCC by four different drugs correlates with a 30-65% inhibition of apoptosis. Intracellular acidification observed upon CD95 triggering is abolished by inhibition of either ORCC or p56lck. The results suggest that tyrosine kinase-mediated activation of ORCC may play a role in CD95-induced cell death in T lymphocytes.
CD95/Fas/APO-1介导的细胞凋亡是免疫反应调节中的一种重要机制。在此，我们表明CD95受体触发可激活Jurkat T淋巴细胞中的外向整流氯离子通道（ORCC）。神经酰胺是一种在CD95受体触发时合成的脂质代谢产物，在细胞贴附式膜片钳实验中也能诱导ORCC的激活。激活由Src样酪氨酸激酶介导，因为它可被酪氨酸激酶抑制剂赫曲霉素A或p56lck的基因缺陷所消除。用纯化的p56lck对切除的膜片进行体外孵育会导致ORCC激活，加入抗磷酸酪氨酸抗体后这种激活会部分逆转。四种不同药物对ORCC的抑制与细胞凋亡30 - 65%的抑制相关。抑制ORCC或p56lck可消除CD95触发时观察到的细胞内酸化。结果表明酪氨酸激酶介导的ORCC激活可能在T淋巴细胞中CD95诱导的细胞死亡中起作用。
