Dissection of autophagosome biogenesis into distinct nucleation and expansion steps.
Dissection of autophagosome biogenesis into distinct nucleation and expansion steps.
复制标题
自噬体生物发生分解为不同的成核和膨胀步骤。
DOI：
10.1083/jcb.151.5.1025
复制
发表时间：
2000-11-27
期刊：
影响因子：
--
通讯作者：
Klionsky DJ
中科院分区：
文献类型：
--
作者：
Abeliovich H;Dunn WA Jr;Kim J;Klionsky DJ
雷帕霉素是一种抗真菌大环内酯类抗生素，通过激活一般的G0程序来模拟酿酒酵母的饥饿状态，该程序包括对翻译和转录的广泛影响。巨噬，一种分解代谢膜运输现象，是这种反应的重要组成部分。诱导自噬可以考虑两种观点。首先，自噬相关蛋白的上调导致自噬的诱导，这意味着自噬是由Tor引导到转录和翻译机制的信号转导机制的结果。另一种假设假设存在一种专门的信号转导机制，直接诱导自噬。我们通过分析环己亚胺和特定突变对诱导自噬的影响来验证这些可能性。我们发现，自噬的诱导发生在缺乏从头蛋白合成的情况下，包括在雷帕霉素反应中上调的特异性自噬相关蛋白的合成。我们还发现，与自噬发生相关的信号转导事件Apg13p的去磷酸化也独立于新蛋白的合成。最后，我们的数据表明，在没有蛋白质合成的情况下形成的自噬体明显小于正常情况，这表明从头合成蛋白质在调节自噬体扩张中的作用。我们的研究结果确定了信号转导依赖性成核步骤和单独的自噬体扩展步骤的存在，它们共同协调自噬体的生物发生。
Rapamycin, an antifungal macrolide antibiotic, mimics starvation conditions in Saccharomyces cerevisiae through activation of a general G0 program that includes widespread effects on translation and transcription. Macroautophagy, a catabolic membrane trafficking phenomenon, is a prominent part of this response. Two views of the induction of autophagy may be considered. In one, up-regulation of proteins involved in autophagy causes its induction, implying that autophagy is the result of a signal transduction mechanism leading from Tor to the transcriptional and translational machinery. An alternative hypothesis postulates the existence of a dedicated signal transduction mechanism that induces autophagy directly. We tested these possibilities by assaying the effects of cycloheximide and specific mutations on the induction of autophagy. We find that induction of autophagy takes place in the absence of de novo protein synthesis, including that of specific autophagy-related proteins that are up-regulated in response to rapamycin. We also find that dephosphorylation of Apg13p, a signal transduction event that correlates with the onset of autophagy, is also independent of new protein synthesis. Finally, our data indicate that autophagosomes that form in the absence of protein synthesis are significantly smaller than normal, indicating a role for de novo protein synthesis in the regulation of autophagosome expansion. Our results define the existence of a signal transduction-dependent nucleation step and a separate autophagosome expansion step that together coordinate autophagosome biogenesis.