Calyculin a sensitive protein phosphatase is required for Bacillus anthracis lethal toxin induced cytotoxicity
Calyculin a sensitive protein phosphatase is required for Bacillus anthracis lethal toxin induced cytotoxicity
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DOI：
10.1007/s00284-001-0059-8
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发表时间：
2002-02-01
影响因子：
2.6
通讯作者：
Lin, HC
中科院分区：
文献类型：
--
作者：
Kau, JH;Lin, CG;Lin, HC
既往研究表明，炭疽芽孢杆菌致死毒素可诱导小鼠巨噬细胞样J774A.1细胞发生坏死和凋亡，这取决于毒素浓度和磷酸酶活性。在这项研究中，几种蛋白激酶或磷酸酶抑制剂被用来评估致命毒素通过蛋白质磷酸化过程诱导细胞死亡的假设。丝氨酸/苏氨酸磷酸酶抑制剂Calyculin a （300 nM）预处理能抑制约78%由致死毒素引起的细胞死亡，而激酶抑制剂如H7、HA、sphingosin和Genestein，而其他磷酸酶抑制剂如Okadaic acid、Tautomycin和Cyclosporin a则没有作用。此外，最近的报道表明，MEK1蛋白可能在其n端内作为致命因子切割的蛋白水解靶点。在这项研究中，Calyculin A被证明可以增强MEK1蛋白的磷酸化。这阻止了致命因子对MEK1的切割。这些结果表明，推测的Calyculin a敏感蛋白磷酸酶参与了炭疽毒素诱导的细胞毒性，Calyculin a对致死因子细胞毒性的阻断作用可能是通过MEK信号通路介导的。
Previous studies have shown that the Bacillus anthracis lethal toxin can induce both necrosis and apoptosis in mouse macrophage-like J774A.1 cells depending on both the toxin concentration and the phosphatase activity. In this study several protein kinase or phosphatase inhibitors were employed to evaluate the hypothesis that the lethal toxin induces cell death via protein phosphorylation processes. Pretreatment with a serine/threonine phosphatase inhibitor Calyculin A (300 nM) could inhibit about 78% of cell death induced by the lethal toxin, whereas inhibitors of kinases, such as H7, HA, Sphingosine, and Genestein, but other inhibitors of phosphatases, such as Okadaic acid, Tautomycin, and Cyclosporin A, did not. In addition, recent reports have demonstrated that the MEK1 protein may serve as a proteolytic target within its N-terminus for lethal factor cleavage. In this study, Calyculin A is shown to enhance the phosphorylation of the MEK1 protein. This prevents the cleavage of the MEK1 by lethal factor. These results suggest that a putative Calyculin A-sensitive protein phosphatase is involved in anthrax toxin induced cytotoxicity and that the blocking effect of Calyculin A on lethal factor cytotoxicity may be mediated through the MEK signaling pathway.