Department of Health Science, Hamamatsu University School of Medicine, 1-20-1 Handa-yama, Higashi-ku, Hamamatsu 431-3192, Japan.
Biochem Biophys Res Commun. 2011 Jul 1;410(2):371-5. doi: 10.1016/j.bbrc.2011.06.023. Epub 2011 Jun 12.
During phagosome maturation, the late endosomal marker Rab7 and the lysosomal marker LAMP1 localize to the phagosomes. We investigated the mobility of Rab7 and LAMP1 on the phagosomes in macrophages by fluorescence recovery after photobleaching (FRAP) analysis. Rab7 was mobile between the phagosomal membrane and the cytosol in macrophages that ingested latex beads during phagosome maturation. The addition of interferon-γ (IFN-γ) restricted this mobility, suggesting that Rab7 is forced to bind to the phagosomal membrane by IFN-γ-mediated activation. Immobilization of LAMP1 on the phagosomes was observed irrespective of IFN-γ-activation. We further examined the mobility of Rab7 on the phagosomes containing Mycobacterium bovis BCG by FRAP analysis. The rate of fluorescence recovery for Rab7 on mycobacterial phagosomes was lower than that on the phagosomes containing latex beads, suggesting that mycobacteria impaired the mobility of Rab7 and arrested phagosome maturation.
在吞噬体成熟过程中，晚期内体标记 Rab7 和溶酶体标记 LAMP1 定位于吞噬体。我们通过荧光恢复后漂白（FRAP）分析研究了巨噬细胞中 Rab7 和 LAMP1 在吞噬体上的流动性。在吞噬体成熟过程中吞噬乳胶珠的巨噬细胞中，Rab7 在吞噬体膜和细胞质之间是可移动的。干扰素-γ（IFN-γ）的添加限制了这种流动性，表明 Rab7 被 IFN-γ 介导的激活强制结合到吞噬体膜上。无论 IFN-γ是否激活，LAMP1 都固定在吞噬体上。我们通过 FRAP 分析进一步研究了含有牛分枝杆菌 BCG 的吞噬体上 Rab7 的流动性。荧光恢复的 Rab7 在分枝杆菌吞噬体上的速度低于在含有乳胶珠的吞噬体上的速度，表明分枝杆菌削弱了 Rab7 的流动性并阻止了吞噬体成熟。
