Selective inhibition of a two-step egress of malaria parasites from the host erythrocyte
Selective inhibition of a two-step egress of malaria parasites from the host erythrocyte
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DOI：
10.1074/jbc.m305252200
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发表时间：
2003-09-26
影响因子：
4.8
通讯作者：
Cowman, AF
中科院分区：
文献类型：
--
作者：
Wickham, ME;Culvenor, JG;Cowman, AF
恶性疟原虫侵袭期从宿主红细胞中逃脱是疟疾发病机制的一个基本步骤，目前对其知之甚少。在分裂子侵入宿主细胞后，寄生虫被封闭在寄生液泡中，在这个液泡中，寄生虫经历生长，然后进行无性分裂，产生16-32个子代分裂子。这些子细胞在寄生液泡和红细胞膜破裂时释放出来。为了研究分裂子的释放过程，我们使用表达绿色荧光蛋白嵌合蛋白的恶性疟原虫细胞系，靶向分裂子必须离开的隔室：寄生物液泡和宿主红细胞细胞质。这样就可以可视化活寄生虫的分裂子释放。在这里，我们提供了第一个证据，在活的，未经处理的细胞中，分裂子的释放涉及寄生液泡膜的初级破裂，随后是红细胞质膜的继发性破裂。我们已经用免疫电镜证实，在未转染的野生型寄生虫中，寄生液泡膜破裂发生在红细胞质膜破裂之前。我们还证明了使用不同的蛋白酶抑制剂选择性地抑制了这两步退出过程中的每一步，这意味着在这些步骤中每个步骤都涉及不同的蛋白酶。这将有助于鉴定参与裂殖子释放的寄生虫和宿主分子。
Escape from the host erythrocyte by the invasive stage of the malaria parasite Plasmodium falciparum is a fundamental step in the pathogenesis of malaria of which little is known. Upon merozoite invasion of the host cell, the parasite becomes enclosed within a parasitophorous vacuole, the compartment in which the parasite undergoes growth followed by asexual division to produce 16-32 daughter merozoites. These daughter cells are released upon parasitophorous vacuole and erythrocyte membrane rupture. To examine the process of merozoite release, we used P. falciparum lines expressing green fluorescent protein-chimeric proteins targeted to the compartments from which merozoites must exit: the parasitophorous vacuole and the host erythrocyte cytosol. This allowed visualization of merozoite release in live parasites. Herein we provide the first evidence in live, untreated cells that merozoite release involves a primary rupture of the parasitophorous vacuole membrane followed by a secondary rupture of the erythrocyte plasma membrane. We have confirmed, with the use of immunoelectron microscopy, that parasitophorous vacuole membrane rupture occurs before erythrocyte plasma membrane rupture in untransfected wild-type parasites. We have also demonstrated selective inhibition of each step in this two-step process of exit using different protease inhibitors, implicating the involvement of distinct proteases in each of these steps. This will facilitate the identification of the parasite and host molecules involved in merozoite release.