ATPase-defective mammalian VPS4 localizes to aberrant endosomes and impairs cholesterol trafficking
ATPase-defective mammalian VPS4 localizes to aberrant endosomes and impairs cholesterol trafficking
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DOI：
10.1091/mbc.11.1.227
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发表时间：
2000-01-01
影响因子：
3.3
通讯作者：
Woodmane, P
中科院分区：
文献类型：
--
作者：
Bishop, N;Woodmane, P
酵母空泡分选蛋白Vps 4p是一种内体运输所需的ATP酶，其将膜缔合与其ATP酶循环偶联。为了研究哺乳动物VPS 4在内体运输中的功能，我们在培养的细胞中瞬时表达野生型或ATP酶缺陷型人VPS 4（hVPS 4）。野生型hVPS 4是胞质的，而不能结合或水解ATP的hVPS 4的实质性部分定位于膜，包括特异性诱导的空泡。空泡在起源上完全是内吞的，并且扩大的空泡的子集用内吞途径的每个阶段的标记物染色。从早期内体到再循环隔室或到trans-Golgi网络的受体分选没有受到显著影响，并且没有突变体hVPS 4与这些隔室相关。然而，许多hVPS 4诱导的空泡相对于未转染细胞的内体区室实质上富含胆固醇，表明突变体hVPS 4的表达引起内体后胆固醇分选的动力学阻断。这里描述的表型在很大程度上是一致的空泡分选与E类VPS突变体在酵母中的缺陷，并在此背景下讨论了哺乳动物VPS 4的作用。
The yeast vacuolar sorting protein Vps4p is an ATPase required for endosomal trafficking that couples membrane association to its ATPase cycle. To investigate the function of mammalian VPS4 in endosomal trafficking, we have transiently expressed wild-type or ATPase-defective human VPS4 (hVPS4) in cultured cells. Wild-type hVPS4 was cytosolic, whereas a substantial fraction of hVPS4 that was unable to either bind or hydrolyze ATP was localized to membranes, including those of specifically induced vacuoles. Vacuoles were exclusively endocytic in origin, and subsets of enlarged vacuoles stained with markers for each stage of the endocytic pathway. Sorting of receptors from the early endosome to the recycling compartment or to the trans-Golgi network was not significantly affected, and no mutant hVPS4 associated with these compartments. However, many hVPS4-induced vacuoles were substantially enriched in cholesterol relative to the endosomal compartments of untransfected cells, indicating that expression of mutant hVPS4 gives rise to a kinetic block in postendosomal cholesterol sorting. The phenotype described here is largely consistent with the defects in vacuolar sorting associated with class E vps mutants In yeast, and a role for mammalian VPS4 is discussed in this context.