Neco Patricia, Rossetto Ornella, Gil Anabel, Montecucco Cesare, Gutiérrez Luis M
Instituto de Neurociencias, Centro Mixto CSIC-Universidad Miguel Hernández, Alicante, Spain.
J Neurochem. 2003 Apr;85(2):329-37. doi: 10.1046/j.1471-4159.2003.01682.x.
Adrenomedullary bovine chromaffin cells were used to study the uptake and cellular effects of the phospholipase type A2 (PLA2) neurotoxin taipoxin in a neuroendocrine model. This toxin entered rapidly inside cultured cells. Within 1 h, taipoxin accumulated on the plasma membrane, independently of calcium presence, and caused fragmentation of the F-actin cytoskeleton. Toxin-induced cell death occurred after 24 h of incubation with the appearance of toxin containing large vesicles. Secretory experiments performed in cell populations showed an increased exocytosis in taipoxin-treated cells stimulated by depolarization or by incubation with the calcium-ionophore A23187. Like F-actin fragmentation, this effect is abolished by replacement of Ca2+ with Sr2+ during toxin incubation. The effect of taipoxin on exocytosis is not enhanced by latrunculin A, a F-actin disassembling drug altering secretion. Secretory studies in single taipoxin-treated cells using amperometry, showed an increase in the number of released vesicles without modification of the kinetic parameters of individual vesicle fusions. Taken together, these results suggest that taipoxin causes F-actin fragmentation and enhances secretion by redistribution of vesicles among secretory pools.
肾上腺髓质牛嗜铬细胞被用于在神经内分泌模型中研究磷脂酶A2（PLA2）神经毒素 taipoxin 的摄取及细胞效应。这种毒素能迅速进入培养细胞内部。在1小时内，taipoxin 积聚在质膜上，与钙离子的存在无关，并导致F-肌动蛋白细胞骨架的断裂。在与含有大囊泡的毒素共同孵育24小时后出现毒素诱导的细胞死亡。在细胞群体中进行的分泌实验表明，在经去极化或与钙离子载体A23187共同孵育刺激的taipoxin处理细胞中，胞吐作用增强。与F-肌动蛋白断裂一样，在毒素孵育期间用Sr2+替代Ca2+可消除这种效应。改变分泌的F-肌动蛋白拆解药物latrunculin A不会增强taipoxin对胞吐作用的影响。使用电流分析法对单个taipoxin处理细胞进行的分泌研究表明，释放囊泡的数量增加，而单个囊泡融合的动力学参数未发生改变。综上所述，这些结果表明，taipoxin 通过囊泡在分泌池之间的重新分布导致F-肌动蛋白断裂并增强分泌。
