https://ror.org/04j7mzp05 Department of Histology and Cell Biology, School of Medicine, Kagawa University, Miki, Japan
https://ror.org/04j7mzp05 Department of Histology and Cell Biology, School of Medicine, Kagawa University, Miki, Japan.
Life Sci Alliance. 2024 Jul 31;7(10). doi: 10.26508/lsa.202402651. Print 2024 Oct.
Phagocytosis is an important immune response that protects the host from pathogen invasion. Rit1 GTPase is known to be involved in diverse cellular processes. However, its role in FcγR-mediated phagocytosis remains unclear. Our live-cell imaging analysis revealed that Rit1 was localized to the membranes of F-actin-rich phagocytic cups in RAW264 macrophages. Rit1 knockout and expression of the GDP-locked Rit1 mutant suppressed phagosome formation. We also found that TBC1D10B, a GAP for the Rab family GTPases, colocalizes with Rit1 in the membranes of phagocytic cups. Expression and knockout studies have shown that TBC1D10B decreases phagosome formation in both Rab-GAP activity-dependent and -independent manners. Notably, the expression of the GDP-locked Rit1 mutant or Rit1 knockout inhibited the dissociation of TBC1D10B from phagocytic cups. In addition, the expression of the GTP-locked Rit1 mutant promoted the dissociation of TBC1D10B in phagocytic cups and restored the rate of phagosome formation in TBC1D10B-expressing cells. These data suggest that Rit1-TBC1D10B signaling regulates FcγR-mediated phagosome formation in macrophages.
吞噬作用是一种重要的免疫反应，可保护宿主免受病原体入侵。Rit1 GTPase 已知参与多种细胞过程。然而，其在 FcγR 介导的吞噬作用中的作用尚不清楚。我们的活细胞成像分析显示，Rit1 定位于 RAW264 巨噬细胞中 F-肌动蛋白丰富的吞噬杯中。Rit1 敲除和表达 GDP 锁定的 Rit1 突变体抑制吞噬体形成。我们还发现，Rab 家族 GTPases 的 GAP TBC1D10B 与 Rit1 在吞噬杯中膜共定位。表达和敲除研究表明，TBC1D10B 以 Rab-GAP 活性依赖和非依赖的方式降低吞噬体形成。值得注意的是，表达 GDP 锁定的 Rit1 突变体或 Rit1 敲除抑制了 TBC1D10B 从吞噬杯中分离。此外，表达 GTP 锁定的 Rit1 突变体促进了 TBC1D10B 在吞噬杯中解离，并恢复了 TBC1D10B 表达细胞中吞噬体形成的速率。这些数据表明 Rit1-TBC1D10B 信号调节巨噬细胞中 FcγR 介导的吞噬体形成。
