Artemisinin induces calcium-dependent protein secretion in the protozoan parasite Toxoplasma gondii
Artemisinin induces calcium-dependent protein secretion in the protozoan parasite Toxoplasma gondii
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DOI：
10.1128/ec.00262-07
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发表时间：
2007-11-01
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影响因子：
--
通讯作者：
Sibley, L. David
中科院分区：
文献类型：
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作者：
Nagamune, Kisaburo;Beatty, Wandy L.;Sibley, L. David
细胞内钙离子控制着顶复门寄生虫的几个关键细胞事件，包括蛋白质分泌、运动和侵入宿主细胞和从宿主细胞中排出。植物化合物毒胡萝卜素抑制肌质-内质网钙ATP酶（SERCA），导致刚地弓形虫钙升高和蛋白质分泌诱导。青蒿素是一种天然产物，对寄生虫具有有效的选择性活性，可用于治疗疟疾。虽然作用机制尚不确定，但先前的研究表明青蒿素可能抑制SERCA，从而破坏钙稳态。我们在T.弓形虫（TgSERCA），并证明该蛋白定位于内质网的寄生虫。在细胞外寄生虫，TgSERCA部分重新定位到顶端极，一个高度活跃的网站调节分泌的微素。TgSERCA补充钙ATP酶缺陷的酵母突变体，这种活性被毒胡萝卜素或青蒿素抑制。治疗T.与SERCA抑制剂毒胡萝卜素类似，弓形虫与青蒿素一起触发微线蛋白的钙依赖性分泌。青蒿素治疗也改变了寄生虫细胞内钙增加钙振荡的周期性和诱导复发，强烈的钙尖峰，使用Fluo-4标记成像。总的来说，这些结果表明青蒿素扰乱了T。支持Ca 2 +-ATP酶是寄生虫潜在的药物靶点的观点。
Intracellular calcium controls several crucial cellular events in apicomplexan parasites, including protein secretion, motility, and invasion into and egress from host cells. The plant compound thapsigargin inhibits the sarcoplasmic-endoplasmic reticulum calcium ATPase (SERCA), resulting in elevated calcium and induction of protein secretion in Toxoplasma gondii. Artemisinins are natural products that show potent and selective activity against parasites, making them useful for the treatment of malaria. While the mechanism of action is uncertain, previous studies have suggested that artemisinin may inhibit SERCA, thus disrupting calcium homeostasis. We cloned the single-copy gene encoding SERCA in T. gondii (TgSERCA) and demonstrate that the protein localizes to the endoplasmic reticulum in the parasite. In extracellular parasites, TgSERCA partially relocalized to the apical pole, a highly active site for regulated secretion of micronemes. TgSERCA complemented a calcium ATPase-defective yeast mutant, and this activity was inhibited by either thapsigargin or artemisinin. Treatment of T. gondii with artemisinin triggered calcium-dependent secretion of microneme proteins, similar to the SERCA inhibitor thapsigargin. Artemisinin treatment also altered intracellular calcium in parasites by increasing the periodicity of calcium oscillations and inducing recurrent, strong calcium spikes, as imaged using Fluo-4 labeling. Collectively, these results demonstrate that artemisinin perturbs calcium homeostasis in T. gondii, supporting the idea that Ca2+-ATPases are potential drug targets in parasites.