Graber R, Losa G A
Laboratorio di Patologia Cellulare, Istituto Cantonale di Patologia, Locarno, Switzerland.
Anal Cell Pathol. 1995 Mar;8(2):159-75.
The behaviour of the membrane enzymes PIP2-phospholipase C (PLC), that modulates the extracellular signals, and gamma-glutamyltransferase (gamma-GT), involved in metabolite transport, was followed during the early and active phases of apoptosis induced in CCRF-CEM cells by glucocorticoid (10(-6) M dexamethasone, DEX). The activities of gamma-GT and PLC increased significantly at 15 and 30 s after dexamethasone addition. Both activities decreased to the control level after 2 min but increased again at 5 min. The enzyme activities were high in apoptotic cells. Apoptosis was seen after incubation with 10(-6)M dexamethasone for 48 h, with decreased cell number, cellular activation (MTT) and S-phase percentage; enhanced DNA fragmentation and propidium iodide uptake; and ultrastructural changes in the chromatin and cell membranes. The changes in enzyme activity are indicators which occur much earlier than the cellular events related to the apoptotic death in CD4(+)-T CEM lymphoblastoid cells.
膜酶磷脂酰肌醇-4,5-二磷酸磷脂酶C（PLC）可调节细胞外信号，γ-谷氨酰转移酶（γ-GT）参与代谢物转运。在糖皮质激素（10⁻⁶M地塞米松，DEX）诱导CCRF-CEM细胞凋亡的早期和活跃阶段，对这两种酶的行为进行了跟踪研究。加入地塞米松后15秒和30秒，γ-GT和PLC的活性显著增加。两分钟后，两种酶的活性降至对照水平，但在5分钟时再次升高。凋亡细胞中的酶活性较高。用10⁻⁶M地塞米松孵育48小时后可见细胞凋亡，表现为细胞数量减少、细胞活性（MTT）降低、S期百分比降低；DNA片段化和碘化丙啶摄取增加；染色质和细胞膜出现超微结构变化。酶活性的变化是比CD4⁺-T CEM淋巴母细胞凋亡死亡相关的细胞事件更早出现的指标。
