Involvement of ganglioside GM3 in G2/M cell cycle arrest of human monocytic cells induced by Actinobacillus actinomycetemcomitans cytolethal distending toxin
Involvement of ganglioside GM3 in G2/M cell cycle arrest of human monocytic cells induced by Actinobacillus actinomycetemcomitans cytolethal distending toxin
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DOI：
10.1128/iai.73.8.4846-4852.2005
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发表时间：
2005-08-01
影响因子：
3.1
通讯作者：
Takehara, T
中科院分区：
文献类型：
--
作者：
Mise, K;Akifusa, S;Takehara, T
伴放线放线杆菌产生一种称为细胞致死性膨胀毒素（CDT）的毒素，其引起宿主细胞DNA损伤，导致DNA损伤检查点途径的诱导。CDT由CdtA、CdtB和CdtC三个亚基组成。CdtB是CDT的活性亚基，并发挥其作为核酸酶的作用，破坏核DNA，触发细胞周期停滞。在本研究中，我们证实，唯一的组合毒素蛋白引起细胞周期阻滞是所有三个重组CDT（rCDT）蛋白亚基。此外，为了使rCDT表现出毒性，CdtA和CdtC有必要在CdtB之前进入细胞。CdtA和CdtC的共存是这些亚基与细胞结合所必需的。用葡糖神经酰胺合成抑制剂1-苯基-2-棕榈酰氨基-3-吗啉代-1-丙醇处理的细胞显示出对rCDT诱导的细胞毒性的抗性。此外，缺乏鞘脂生物合成的LY-B细胞也显示出对rCDT诱导的细胞毒性的抗性。为了评估葡萄糖神经酰胺的每个亚基的结合，我们进行了薄层色谱免疫染色。结果表明，每个亚基与鞘糖脂GM 1、GM 2、GM 3、Gb 3和Gb 4反应。与含有GM 3的脂质体孵育的rCDT混合物显示部分降低的毒性。这些结果表明，GM 3可以作为CDT受体。
Actinobacillus actinomycetemcomitans produces a toxin called cytolethal distending toxin (CDT), which causes host cell DNA damage leading to the induction of DNA damage checkpoint pathways. CDT consists of three subunits, CdtA, CdtB, and CdtC. CdtB is the active subunit of CDT and exerts its effect as a nuclease that damages nuclear DNA, triggering cell cycle arrest. In the present study, we confirmed that the only combination of toxin proteins causing cell cycle arrest was that of all three recombinant CDT (rCDT) protein subunits. Furthermore, in order for rCDT to demonstrate toxicity, it was necessary for CdtA and CdtC to access the cell before CdtB. The coexistence of CdtA and CdtC was necessary for these subunits to bind to the cell. Cells treated with the glucosylceramide synthesis inhibitor 1-phenyl-2-palmitoylamino-3-morpholino-1-propanol showed resistance to the cytotoxicity induced by rCDT. Furthermore, LY-B cells, which are deficient in the biosynthesis of sphingolipid, also showed resistance to the cytotoxicity induced by rCDT. To evaluate the binding of each subunit for glucosylceramides, we performed thin-layer chromatography immunostaining. The results indicated that each subunit reacted with the glycosphingolipids GM1, GM2, GM3, Gb3, and Gb4. The rCDT mixture incubated with liposomes containing GM3 displayed partially reduced toxicity. These results indicate that GM3 can act as a CDT receptor.