Zhu Lu, Jorgensen Jeff R, Li Ming, Chuang Ya-Shan, Emr Scott D
Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, United States.
Department of Molecular Biology and Genetics, Cornell University, Ithaca, United States.
Elife. 2017 Jun 29;6:e26403. doi: 10.7554/eLife.26403.
The lysosome plays an important role in maintaining cellular nutrient homeostasis. Regulation of nutrient storage can occur by the ubiquitination of certain transporters that are then sorted into the lysosome lumen for degradation. To better understand the underlying mechanism of this process, we performed genetic screens to identify components of the sorting machinery required for vacuole membrane protein degradation. These screens uncovered genes that encode a ubiquitin ligase complex, components of the PtdIns 3-kinase complex, and the ESCRT machinery. We developed a novel ubiquitination system, amycinnduced radation (RapiDeg), to test the sorting defects caused by these mutants. These tests revealed that ubiquitinated vacuole membrane proteins recruit ESCRTs to the vacuole surface, where they mediate cargo sorting and direct cargo delivery into the vacuole lumen. Our findings demonstrate that the ESCRTs can function at both the late endosome and the vacuole membrane to mediate cargo sorting and intra-luminal vesicle formation.
溶酶体在维持细胞营养稳态中发挥着重要作用。营养储存的调节可通过某些转运蛋白的泛素化来实现，这些转运蛋白随后被分选到溶酶体腔中进行降解。为了更好地理解这一过程的潜在机制，我们进行了遗传筛选，以鉴定液泡膜蛋白降解所需的分选机制的组成部分。这些筛选发现了编码泛素连接酶复合物、磷脂酰肌醇3激酶复合物的组成部分以及ESCRT机制的基因。我们开发了一种新型泛素化系统，即氨霉素诱导辐射（RapiDeg），以测试这些突变体引起的分选缺陷。这些测试表明，泛素化的液泡膜蛋白将ESCRT招募到液泡表面，在那里它们介导货物分选并将货物直接递送到液泡腔中。我们的研究结果表明，ESCRT可以在晚期内体和液泡膜上发挥作用，以介导货物分选和腔内囊泡形成。
