Chen Lei, Zhang Chunling, Liang Yuancun, Liu Aixin, Dong Hansong, Zou Shenshen
Department of Plant Pathology, Shandong Agricultural University, Tai'an 271018, China.
J Biosci. 2019 Mar;44(1).
Autophagy is a highly conserved intracellular degradation pathway in eukaryotic cells that responds to environmental changes. Genetic analyses have shown that more than 40 autophagy-related genes (ATG) are directly involved in this process in fungi. In addition to Atg proteins, most vesicle transport regulators are also essential for each step of autophagy. The present study showed that one Endoplasmic Reticulum protein in , Tip20, which controls Golgi-to-ER retrograde transport, was also required for starvation-induced autophagy under high temperature stress. In conditional mutant yeast, the transport of Atg8 was impaired during starvation, resulting in multiple Atg8 puncta dispersed outside the vacuole that could not be transported to the pre-autophagosomal structure/phagophore assembly site (PAS). Several Atg8 puncta were trapped in ER exit sites (ERES). Moreover, the GFP-Atg8 protease protection assay indicated that Tip20 functions before autophagosome closure. Furthermore, genetic studies showed that Tip20 functions downstream of Atg5 and upstream of Atg1, Atg9 and Atg14 in the autophagy pathway. The present data show that Tip20, as a vesicle transport regulator, has novel roles in autophagy.
自噬是真核细胞中一种高度保守的细胞内降解途径，可响应环境变化。遗传分析表明，40多个自噬相关基因（ATG）直接参与真菌的这一过程。除了Atg蛋白外，大多数囊泡运输调节因子对自噬的每个步骤也至关重要。本研究表明，内质网中的一种蛋白质Tip20，它控制高尔基体到内质网的逆行运输，在高温胁迫下饥饿诱导的自噬中也是必需的。在条件性突变酵母中，饥饿期间Atg8的运输受损，导致多个Atg8斑点分散在液泡外，无法运输到自噬前体结构/吞噬体组装位点（PAS）。几个Atg8斑点被困在内质网出口位点（ERES）。此外，GFP-Atg8蛋白酶保护试验表明Tip20在自噬体封闭之前起作用。此外，遗传研究表明Tip20在自噬途径中Atg5的下游以及Atg1、Atg9和Atg14的上游起作用。目前的数据表明，Tip20作为一种囊泡运输调节因子，在自噬中具有新的作用。
