Spatial Localisation of Actin Filaments across Developmental Stages of the Malaria Parasite
Spatial Localisation of Actin Filaments across Developmental Stages of the Malaria Parasite
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DOI：
10.1371/journal.pone.0032188
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发表时间：
2012-02-28
期刊：
影响因子：
3.7
通讯作者：
Baum, Jake
中科院分区：
文献类型：
--
作者：
Angrisano, Fiona;Riglar, David T.;Baum, Jake
在疟疾寄生虫的生命周期中，肌动蛋白的动态参与了多种发育过程。特别是寄生虫的运动，被认为严重依赖于位于寄生虫细胞外层的肌球蛋白马达。然而，由于无法在自然条件下检测到微丝，理解肌动蛋白所扮演的不同角色的努力受到了阻碍。为了可视化肌动蛋白的空间动态，我们产生了一种寄生虫特异的肌动蛋白抗体，它显示了对丝状肌动蛋白的优先识别，并将该工具应用于人和鼠疟疾寄生虫恶性疟原虫和伯氏疟原虫的不同生命周期阶段(裂殖子、子孢子和卵子)，以及来自相关尖端复合体寄生虫弓形虫的速殖子。在人和小鼠疟原虫中，肌动蛋白细丝的分布与三个核心隔室有关：运动寄生虫或侵袭性寄生虫的核周膜、膜膜，以及裂殖子侵入红细胞的紧密连接处的环状分布。位于核周的定位与肌动蛋白在促进寄生虫基因调控方面的新角色是一致的。在入侵过程中，我们发现寄生虫-宿主细胞紧密连接处的肌动蛋白环依赖于动态的细丝周转。超分辨率成像将这个环放置在连接标记RHoptry Neck Protein 4的后面，而不是同心。这意味着运动力依赖于牵引区动态微丝的接触，尽管在入侵过程中不一定直接通过粘连部位的受体-配体相互作用。综上所述，这些观察结果扩展了目前对肌动蛋白在疟疾寄生虫发育和顶端复合体细胞运动中所扮演的不同角色的理解，特别是完善了对寄生虫内部滑动运动与细胞外环境之间联系的理解。
Actin dynamics have been implicated in a variety of developmental processes during the malaria parasite lifecycle. Parasite motility, in particular, is thought to critically depend on an actomyosin motor located in the outer pellicle of the parasite cell. Efforts to understand the diverse roles actin plays have, however, been hampered by an inability to detect microfilaments under native conditions. To visualise the spatial dynamics of actin we generated a parasite-specific actin antibody that shows preferential recognition of filamentous actin and applied this tool to different lifecycle stages (merozoites, sporozoites and ookinetes) of the human and mouse malaria parasite species Plasmodium falciparum and P. berghei along with tachyzoites from the related apicomplexan parasite Toxoplasma gondii. Actin filament distribution was found associated with three core compartments: the nuclear periphery, pellicular membranes of motile or invasive parasite forms and in a ring-like distribution at the tight junction during merozoite invasion of erythrocytes in both human and mouse malaria parasites. Localisation at the nuclear periphery is consistent with an emerging role of actin in facilitating parasite gene regulation. During invasion, we show that the actin ring at the parasite-host cell tight junction is dependent on dynamic filament turnover. Super-resolution imaging places this ring posterior to, and not concentric with, the junction marker rhoptry neck protein 4. This implies motor force relies on the engagement of dynamic microfilaments at zones of traction, though not necessarily directly through receptor-ligand interactions at sites of adhesion during invasion. Combined, these observations extend current understanding of the diverse roles actin plays in malaria parasite development and apicomplexan cell motility, in particular refining understanding on the linkage of the internal parasite gliding motor with the extra-cellular milieu.