The mouse SKD1, a homologue of yeast Vps4p, is required for normal endosomal trafficking and morphology in mammalian cells
The mouse SKD1, a homologue of yeast Vps4p, is required for normal endosomal trafficking and morphology in mammalian cells
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DOI：
10.1091/mbc.11.2.747
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发表时间：
2000-02-01
影响因子：
3.3
通讯作者：
Ohsumi, Y
中科院分区：
文献类型：
--
作者：
Yoshimori, T;Yamagata, F;Ohsumi, Y
小鼠SKD1是一种AAA型ATPase，与酵母Vps4p同源，参与内体到液泡的运输。为了阐明SKD1在哺乳动物内吞作用中的可能作用，我们产生了一个突变SKD1，其突变(E235Q)相当于Vps4p中的显性负突变(B233Q)。突变的SKD1在培养的哺乳动物细胞中过表达导致转铁蛋白和低密度脂蛋白摄取缺陷。这是由于它们的受体从细胞表面丢失，表面转铁蛋白受体(TFR)的减少与突变蛋白的表达水平有关。突变蛋白呈核周点状分布，与野生型SKD1的扩散模式形成鲜明对比。TFR、溶酶体蛋白LAMP-1、胞内葡聚糖和表皮生长因子，但不是分泌途径的标志物，在突变的SKD1定位的间隔室中积累。抑制表皮生长因子的降解。电子显微镜显示，隔室是放大的多囊泡，有大量的管泡延伸，含有转铁蛋白受体和内吞的辣根过氧化物酶。早期的内体抗原EEA1也被重新分布到这些异常的膜上。综上所述，我们的发现表明SKD1调节内体的形态和通过它们的膜运输。
The mouse SKD1 is an AAA-type ATPase homologous to the yeast Vps4p implicated in transport from endosomes to the vacuole. To elucidate a possible role of SKD1 in mammalian endocytosis, we generated a mutant SKD1, harboring a mutation (E235Q) that is equivalent to the dominant negative mutation (B233Q) in Vps4p. Overexpression of the mutant SKD1 in cultured mammalian cells caused defect in uptake of transferrin and low-density lipoprotein. This was due to loss of their receptors from the cell surface The decrease of the surface transferrin receptor (TfR) was correlated with expression levels of the mutant protein. The mutant protein displayed a perinuclear punctate distribution in contrast to a diffuse pattern of the wild-type SKD1. TfR, the lysosomal protein lamp-1, endocytosed dextran, and epidermal growth factor but not markers for the secretory pathway were accumulated in the mutant SKD1-localized compartments. Degradation of epidermal growth factor was inhibited. Electron microscopy revealed that the compartments were exaggerated multivesicular vacuoles with numerous tubulo-vesicular extensions containing TfR and endocytosed horseradish peroxidase. The early endosome antigen EEA1 was also redistributed to these aberrant membranes. Taken together, our findings suggest that SKD1 regulates morphology of endosomes and membrane traffic through them.