Egami Youhei, Araki Nobukazu
Department of Histology and Cell Biology, School of Medicine, Kagawa University, Miki, Kagawa 761-0793, Japan.
Microscopy (Oxf). 2018 Apr 1;67(2):68-74. doi: 10.1093/jmicro/dfx131.
M-Ras, a member of the Ras superfamily, is known to be involved in diverse cellular processes. However, its involvement in FcγR-mediated phagocytosis remains unknown. We examined the spatiotemporal localization of M-Ras during the engulfment of IgG-opsonized erythrocytes (IgG-Es) in RAW264 macrophages. By the live-cell imaging of fluorescent protein-fused M-Ras, we found that M-Ras was localized to the membrane of phagocytic cups during the early stage of phagosome formation. Notably, ratiometric image analysis revealed that M-Ras was concentrated in the membrane of forming phagosomes. Moreover, our analysis of M-Ras mutant expression showed that phagosome formation was significantly inhibited in cells expressing GDP-locked mutant M-Ras-S27N. In contrast, the expression of wild-type M-Ras or GTP-locked mutant M-Ras-G22V facilitated the uptake of IgG-Es. These data suggest that M-Ras is a novel component of the FcγR-mediated phagocytic pathway and may regulate phagosome formation in macrophages.
M-Ras是Ras超家族的成员之一，已知其参与多种细胞过程。然而，它在FcγR介导的吞噬作用中的作用尚不清楚。我们研究了RAW264巨噬细胞吞噬IgG调理红细胞（IgG-Es）过程中M-Ras的时空定位。通过对荧光蛋白融合的M-Ras进行活细胞成像，我们发现M-Ras在吞噬体形成的早期定位于吞噬杯的膜上。值得注意的是，比率图像分析显示M-Ras集中在正在形成的吞噬体膜上。此外，我们对M-Ras突变体表达的分析表明，在表达GDP锁定突变体M-Ras-S27N的细胞中，吞噬体形成受到显著抑制。相反，野生型M-Ras或GTP锁定突变体M-Ras-G22V的表达促进了IgG-Es的摄取。这些数据表明M-Ras是FcγR介导的吞噬途径的一个新组分，可能调节巨噬细胞中的吞噬体形成。
