Entire Photodamaged Chloroplasts Are Transported to the Central Vacuole by Autophagy
Entire Photodamaged Chloroplasts Are Transported to the Central Vacuole by Autophagy
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DOI：
10.1105/tpc.16.00637
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发表时间：
2017-02-01
期刊：
影响因子：
11.6
通讯作者：
Hidema, Jun
中科院分区：
文献类型：
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作者：
Izumi, Masanori;Ishida, Hiroyuki;Hidema, Jun
功能失调的细胞器的周转对于维持真核细胞的稳态是至关重要的。植物叶绿体作为光合作用的细胞器，会受到阳光的伤害。然而，整个受损叶绿体的周转过程仍不清楚。在这里，我们证明，自噬是负责消除阳光损伤，崩溃的叶绿体在拟南芥。我们发现，整个叶绿体的液泡运输，称为食绿，诱导UV-B损伤的叶绿体装置。这种运输没有发生在自噬缺陷的atg突变体，表现出UV-B敏感的表型和积累崩溃的叶绿体。使用荧光蛋白标记的自噬体膜使我们能够图像自噬体介导的运输整个叶绿体的中央液泡。相反，糖饥饿，这优先诱导不同类型的叶绿体靶向自噬，运输基质的一部分，通过Rubisco含体（RCB）途径，光氧化损伤诱导chlorophagy没有事先激活的RCB生产。我们进一步表明，噬绿是由人工可见光或自然阳光引起的叶绿体损伤引起的。因此，本报告确定了自噬过程消除整个叶绿体响应光诱导的损伤。
Turnover of dysfunctional organelles is vital to maintain homeostasis in eukaryotic cells. As photosynthetic organelles, plant chloroplasts can suffer sunlight-induced damage. However, the process for turnover of entire damaged chloroplasts remains unclear. Here, we demonstrate that autophagy is responsible for the elimination of sunlight-damaged, collapsed chloroplasts in Arabidopsis thaliana. We found that vacuolar transport of entire chloroplasts, termed chlorophagy, was induced by UV-B damage to the chloroplast apparatus. This transport did not occur in autophagy-defective atg mutants, which exhibited UV-B-sensitive phenotypes and accumulated collapsed chloroplasts. Use of a fluorescent protein marker of the autophagosomal membrane allowed us to image autophagosome-mediated transport of entire chloroplasts to the central vacuole. In contrast to sugar starvation, which preferentially induced distinct type of chloroplast-targeted autophagy that transports a part of stroma via the Rubisco-containing body (RCB) pathway, photooxidative damage induced chlorophagy without prior activation of RCB production. We further showed that chlorophagy is induced by chloroplast damage caused by either artificial visible light or natural sunlight. Thus, this report establishes that an autophagic process eliminates entire chloroplasts in response to light-induced damage.