National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Inada-cho, Obihiro, Hokkaido 080-8555, Japan.
Biochem Biophys Res Commun. 2010 Jul 9;397(4):668-72. doi: 10.1016/j.bbrc.2010.05.155. Epub 2010 Jun 8.
Malaria parasites undergo two rounding-up transformations in their life cycle: the ookinete-to-oocyst transformation in the mosquito midgut, and the sporozoite-to-EEF (exo-erythrocytic form) differentiation in the host hepatocyte. Both events are characterized by the loss of polarity, implying that cytoskeletal reorganization is involved. In other eukaryotes, regulation of the actin skeleton is fundamental to subcellular remodeling. Although filamentous actin is well known to be involved in the motility of apicomplexan parasites, its participation in their morphological regulation is still largely unexplored. Here we describe the fundamental role of Actin depolymerization factor 2 (ADF2), a vector-stage-specific ADF isoform, in morphological changes accompanying the parasite life cycle. Among protozoan parasites, Plasmodium is unique in having two actin and two ADF genes. Disruption of the ADF2 gene in the rodent malaria parasite P. berghei had no effect on ookinete development or its subsequent invasion of the midgut. However, both the ookinete-to-oocyst and sporozoite-to-EEF transformations showed significant defects. These results indicated that Plasmodium ADF2 plays a pivotal role in transformation in the malaria parasite life cycle.
在蚊子中肠的卵囊虫-卵囊转化，以及在宿主肝细胞中的孢子虫-EEF（外红细胞形态）分化。这两个事件都以极性丧失为特征，这意味着细胞骨架的重排参与其中。在其他真核生物中，肌动蛋白骨架的调节是细胞内重塑的基础。尽管丝状肌动蛋白已被广泛认为参与了锥虫寄生虫的运动，但它在形态调节中的参与仍在很大程度上未被探索。在这里，我们描述了肌动蛋白解聚因子 2 (ADF2)的基本作用，ADF2 是一种载体阶段特异性 ADF 同工型，在伴随寄生虫生命周期的形态变化中发挥作用。在原生动物寄生虫中，疟原虫是唯一具有两种肌动蛋白和两种 ADF 基因的寄生虫。在啮齿动物疟原虫 P. berghei 中破坏 ADF2 基因对卵囊虫的发育或其随后对中肠的入侵没有影响。然而，卵囊虫-卵囊转化和孢子虫-EEF 转化都显示出明显的缺陷。这些结果表明，疟原虫 ADF2 在疟原虫生命周期中的转化中发挥着关键作用。
