School of Life Sciences, Jawaharlal Nehru University, New Delhi, India.
School of Environmental Sciences, Jawaharlal Nehru University, New Delhi, India.
Cell Microbiol. 2018 Dec;20(12):e12942. doi: 10.1111/cmi.12942. Epub 2018 Sep 7.
Phagocytosis is involved in invasive disease of the parasite Entamoeba histolytica. Upon binding of red blood cells, there is a sequential recruitment of EhC2PK, EhCaBP1, EhAK1, and Arp2/3 complex during the initiation phase. In addition, EhCaBP3 is also recruited to the site and, along with myosin 1B, is thought to be involved in progression of phagocytic cups from initiation to phagosome formation. However, it is not clear how EhCaBP3 gets recruited to the rest of the phagocytic machinery. Here, we show that EhARPC2, a subunit of Arp2/3 complex, interacts with EhCaBP3 in a Ca -dependent manner both in vivo and in vitro. Imaging and pull down experiments suggest that interaction with EhARPC2 is required for the closure of cups and formation of phagosomes. Moreover, downregulation of EhARPC2 prevents localisation of EhCaBP3 to phagocytic cups, suggesting that EhCaBP3 is part of EhC2PK-EhCaBP1-EhAK1-Arp2/3 complex (EhARPC1) pathway. In conclusion, these results suggest that the EhCaBP3-EhARPC2 interaction helps to recruit EhCaBP3 along with myosin 1B to the phagocytic machinery that plays an indispensable role in E. histolytica phagocytosis.
吞噬作用参与寄生虫溶组织内阿米巴的侵袭性疾病。在与红细胞结合后，在起始阶段，EhC2PK、EhCaBP1、EhAK1 和 Arp2/3 复合物依次募集。此外，EhCaBP3 也被募集到该部位，与肌球蛋白 1B 一起，被认为参与吞噬杯从起始到吞噬体形成的进展。然而，EhCaBP3 如何被招募到其余的吞噬机制尚不清楚。在这里，我们表明，EhARPC2，Arp2/3 复合物的一个亚基，在体内和体外以 Ca2+依赖性的方式与 EhCaBP3 相互作用。成像和下拉实验表明，与 EhARPC2 的相互作用是杯闭合和吞噬体形成所必需的。此外，EhARPC2 的下调阻止了 EhCaBP3 定位到吞噬杯，表明 EhCaBP3 是 EhC2PK-EhCaBP1-EhAK1-Arp2/3 复合物（EhARPC1）途径的一部分。总之，这些结果表明，EhCaBP3-EhARPC2 相互作用有助于招募 EhCaBP3 与肌球蛋白 1B 一起参与吞噬机制，该机制在溶组织内阿米巴的吞噬作用中起着不可或缺的作用。
