Activation of inositol phospholipid breakdown in HL60 cells by P2-purinergic receptors for extracellular ATP. Evidence for mediation by both pertussis toxin-sensitive and pertussis toxin-insensitive mechanisms.
Activation of inositol phospholipid breakdown in HL60 cells by P2-purinergic receptors for extracellular ATP. Evidence for mediation by both pertussis toxin-sensitive and pertussis toxin-insensitive mechanisms.
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发表时间：
1988-12
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通讯作者：
G. Dubyak;D. S. Cowen;L. Meuller
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作者：
G. Dubyak;D. S. Cowen;L. Meuller
在HL60人早幼粒细胞白血病细胞系中，研究了胞外ATP的P2-嘌呤能受体与肌醇磷脂信号系统偶联的机制。无论是未分化的HL60细胞还是分化的HL60细胞，用不同的蛋白激酶C、钙离子/磷脂依赖酶激活剂(如佛波酯)进行短暂的预处理，细胞外诱导细胞内钙离子动员的能力降低了50倍。三磷酸肌醇(InsP3)在4-β-佛波醇、12-肉豆蔻酸酯-13-乙酸酯处理的细胞中积累速率增加，其特征是InsP3的最大积累速率降低了40%。NaF与细胞孵育后，细胞外释放的钙离子也被动员起来，这间接证明了P2-嘌呤能受体的跨膜信号作用可能是由GTP结合的调节蛋白介导的。用百日咳毒素处理未分化或已分化的HL60细胞产生了对ATP诱导的信号活动的显著但部分的抑制，这进一步支持了后一种可能性。这包括：1)InsP3的最大积累速率降低60-70%，2)动员细胞内钙离子所需的半最大有效[ATP]增加1.5个对数单位。在百日咳毒素和4-β-佛波醇12-肉豆蔻酸酯-13-乙酸酯处理的细胞中，ATP诱导的InsP3积聚的最大速率降低了80%，并几乎完全抑制了ATP诱导的钙动员。值得注意的是，在相同的分化的HL60细胞样本中，观察到残留的、百日咳毒素不敏感的ATP诱导信号部分，其中百日咳毒素处理导致InsP3积聚和钙动员完全取消，以响应趋化性多肽受体的占用。这些结果表明，P2-嘌呤能受体激活HL60细胞的肌醇磷脂降解可能由百日咳毒素敏感和毒素不敏感两种机制介导，提示这些髓系祖细胞可能表达两种不同类型的与磷脂酶C偶联的GTP结合蛋白。
The mechanisms whereby P2-purinergic receptors for extracellular ATP are coupled to the inositol phospholipid-signaling system were studied in the HL60 human promyelocytic leukemia cell line. Brief pretreatment of either undifferentiated or differentiated HL60 cells with various activators of protein kinase C Ca2+/phospholipid-dependent enzyme (e.g. phorbol myristate acetate) produced a 50-fold decrease in the potency of extracellular ATP to induce mobilization of intracellular Ca2+. The ATP-induced increase in rate of inositol trisphosphate (InsP3) accumulation in these 4-beta-phorbol 12-myristate-13-acetate-treated cells was characterized by a 40% decrease in the maximal rate of InsP3 accumulation. Incubation of the cells with NaF also induced mobilization of the same Ca2+ stores released in response to extracellular ATP; this provided indirect evidence that the transmembrane signaling actions of P2-purinergic receptors may be mediated by GTP-binding regulatory proteins. This latter possibility was further supported by the finding that treatment of either undifferentiated or differentiated HL60 cells with pertussis toxin produced a significant, but partial, inhibition of ATP-induced signaling actions. These included: 1) a 60-70% decrease in the maximum rate of InsP3 accumulation, and 2) a 1.5 log unit increase in the half-maximally effective [ATP] required for mobilization of intracellular Ca2+. In cells treated with both pertussis toxin and 4-beta-phorbol 12-myristate-13-acetate, there was an 80% decrease in maximal rate of ATP-induced InsP3 accumulation and near-complete inhibition of ATP-induced Ca2+ mobilization. Significantly, the residual, pertussis toxin-insensitive portion of ATP-induced signaling was observed in the same samples of differentiated HL60 cells wherein pertussis toxin treatment produced complete abolition of InsP3 accumulation and Ca2+ mobilization in response to occupation of chemotactic peptide receptors. These results indicate that the activation of inositol phospholipid breakdown by P2-purinergic receptors in HL60 cells may be mediated by both pertussis toxin-sensitive and toxin-insensitive mechanisms; this suggests that these myeloid progenitor cells may express two distinct types of GTP-binding proteins coupled to phospholipase C.