Cellular internalization of cytolethal distending toxin from Haemophilus ducreyi
Cellular internalization of cytolethal distending toxin from Haemophilus ducreyi
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DOI：
10.1128/iai.68.12.6903-6911.2000
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发表时间：
2000-12-01
影响因子：
3.1
通讯作者：
Thelestam, M
中科院分区：
文献类型：
--
作者：
Cortes-Bratti, X;Chaves-Olarte, E;Thelestam, M
杜氏嗜血杆菌产生一种毒素(HdCDT)，它是最近发现的细胞致死性膨胀毒素(CDTS)家族的成员，这些蛋白毒素阻止细胞周期蛋白依赖的激酶cdc2被激活，从而阻止细胞从G(2)期进入有丝分裂，从而使中毒的细胞在G(2)期停止。目前尚不清楚这些毒素是通过细胞表面的信号起作用，还是仅在细胞内起作用。在这里，我们报道HdCDT在能够发挥作用之前必须至少经历内化，细胞中毒被抑制(I)通过K+耗竭去除笼状蛋白外壳，(Ii)通过药物处理抑制受体聚集到被包裹的凹坑中，以及(Iii)在基因操纵的细胞中被失败的笼状蛋白依赖的内吞作用。在用巴非霉素A1或诺可达唑处理的细胞中，以及在18℃孵育的细胞中，即在已知阻止早期内体与下游隔室融合的条件下，中毒也完全被抑制。此外，用布雷菲尔丁A或伊利马喹酮处理高尔基复合体可阻断中毒。总之，我们的数据表明，HdCDT通过笼蛋白包裹的凹坑进入细胞，并必须通过高尔基复合体运输才能使细胞中毒。这是CDT家族中的第一个成员，其细胞内化和一些途径的细节已经被证明。
The chancroid bacterium Haemophilus ducreyi produces a toxin (HdCDT) which is a member of the recently discovered family of cytolethal distending toxins (CDTs), These protein toxins prevent the cyclin dependent kinase cdc2 from being activated, thus blocking the transition of cells from the G(2) phase into mitosis, with the consequent arrest of intoxicated cells in G(2). It is not known whether these toxins act by signaling from the cell surface or intracellularly only. Here we report that HdCDT has to undergo at least internalization before being able to act, Cellular intoxication was inhibited (i) by removal of clathrin coats via K+ depletion, (ii) by treatment with drugs that inhibit receptor clustering into coated pits, and (iii) in cells genetically manipulated to fail in clathrin-dependent endocytosis. Intoxication was also completely inhibited in cells treated with bafilomycin Al or nocodazole and in cells incubated at 18 degreesC, i.e., under conditions known to block the fusion of early endosomes with downstream compartments. Moreover, disruption of the Golgi complex by treatment with brefeldin A or ilimaquinone blocked intoxication. In conclusion, our data indicate that HdCDT enters cells via clathrin-coated pits and has to be transported via the Golgi complex in order to intoxicate cells. This is the first member of the family of CDTs for which cellular internalization and some details of the pathway have been demonstrated.