Gusovsky F, Bitran J A, Yasumoto T, Daly J W
Laboratory of BioOrganic Chemistry, National Institute of Arthritis, Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland.
J Pharmacol Exp Ther. 1990 Feb;252(2):466-73.
The marine toxin maitotoxin (MTX) and the chemotactic peptide fMet-Leu-Phe (fMLP) induce the formation of inositol phosphates in HL-60 cells differentiated with dibutyryl cyclic AMP. The increase in [3H]inositol(1,4,5)-trisphosphate is rapid but transient after fMLP stimulation, whereas MTX-induced increase in [3H]inositol(1,4,5)-trisphosphate occurs at a slower rate and is sustained over time. In both cases increases in [Ca++]i, measured with fura-2, parallel the formation of inositol trisphosphate. MTX-mediated stimulation of inositol phosphate formation is inhibited in the absence of calcium, whereas the response to fMLP is not. The calcium ionophore ionomycin stimulates the formation of inositol phosphates in differentiated HL-60 cells. The magnitude of the response is smaller than that obtained with MTX. Ionomycin also induces a rapid but sustained increase of [Ca++]i. In undifferentiated HL-60 cells, neither fMLP nor ionomycin induce significant inositol phosphate formation, and the increase in [Ca++]i elicited by ionomycin is transient. In contrast, the effects of MTX on phosphoinositide breakdown and on [Ca++]i in undifferentiated cells are nearly identical to those elicited by MTX in differentiated cells. In the presence of the intracellular calcium chelator BAPTA, fMLP, ionomycin and MTX still stimulate the generation of inositol phosphates. Guanyl nucleotides and calcium stimulate phospholipase C activity in membrane preparations from differentiated HL-60 cells. fMLP stimulates the enzyme only in the presence of GTP. MTX has no effect on membrane phospholipase C activity.
海洋毒素刺尾鱼毒素（MTX）和趋化肽N-甲酰甲硫氨酰-亮氨酰-苯丙氨酸（fMLP）可诱导经二丁酰环磷酸腺苷分化的HL-60细胞中肌醇磷酸的形成。fMLP刺激后，[3H]肌醇（1,4,5）-三磷酸迅速增加但呈短暂性，而MTX诱导的[3H]肌醇（1,4,5）-三磷酸增加速率较慢且随时间持续存在。在这两种情况下，用fura-2测量的细胞内钙离子浓度（[Ca++]i）的增加与肌醇三磷酸的形成平行。在无钙情况下，MTX介导的肌醇磷酸形成刺激受到抑制，而对fMLP的反应则不受影响。钙离子载体离子霉素可刺激分化的HL-60细胞中肌醇磷酸的形成。其反应幅度小于MTX所引起的反应。离子霉素还诱导[Ca++]i迅速但持续的增加。在未分化的HL-60细胞中，fMLP和离子霉素均未诱导显著的肌醇磷酸形成，且离子霉素引起的[Ca++]i增加是短暂的。相比之下，MTX对未分化细胞中磷酸肌醇分解和[Ca++]i的影响与MTX对分化细胞所引起的影响几乎相同。在存在细胞内钙螯合剂BAPTA的情况下，fMLP、离子霉素和MTX仍可刺激肌醇磷酸的生成。鸟苷核苷酸和钙离子可刺激分化的HL-60细胞膜制剂中的磷脂酶C活性。fMLP仅在存在GTP的情况下刺激该酶。MTX对膜磷脂酶C活性无影响。
