Kimura Shunsuke, Noda Takeshi, Yoshimori Tamotsu
Research Institute for Microbial Diseases, Osaka University, Osaka, Japan.
Cell Struct Funct. 2008;33(1):109-22. doi: 10.1247/csf.08005. Epub 2008 Apr 4.
Autophagy is a membrane trafficking pathway that carries cytosolic components to the lysosome for degradation. During this process, the autophagosome, a double-membraned organelle, is generated de novo, sequesters cytoplasmic proteins and organelles, and delivers them to lysosomes. However, the mechanism by which autophagosomes are targeted to lysosomes has not been determined. Here, we observed the real-time behavior of microtubule-associated protein light chain 3 (LC3), which localizes to autophagosomes, and showed that autophagosomes move in a microtubule- and dynein-dynactin motor complex-dependent manner. After formation, autophagosomes show a rapid vectorial movement in the direction of the centrosome, where lysosomes are usually concentrated. Microinjection of antibodies against LC3 inhibited this movement; furthermore, using FRAP, we showed that anti-LC3 antibody injection caused a defect in targeting of autophagosomes to lysosomes. Collectively, our data demonstrate the functional significance of autophagosome movement that enables effective delivery from the cytosol to lysosomes.
自噬是一种膜运输途径，它将胞质成分运送至溶酶体进行降解。在此过程中，自噬体（一种双膜细胞器）会重新生成，隔离细胞质蛋白和细胞器，并将它们运送至溶酶体。然而，自噬体靶向溶酶体的机制尚未确定。在这里，我们观察了定位于自噬体的微管相关蛋白轻链3（LC3）的实时行为，并表明自噬体以微管和动力蛋白-动力蛋白激活蛋白复合物依赖的方式移动。形成后，自噬体沿中心体方向快速进行矢量移动，而溶酶体通常集中在中心体处。显微注射抗LC3抗体可抑制这种移动；此外，使用荧光漂白恢复技术（FRAP），我们表明注射抗LC3抗体导致自噬体靶向溶酶体出现缺陷。总体而言，我们的数据证明了自噬体移动的功能意义，这种移动能够实现从细胞质到溶酶体的有效递送。
