Highly Oxidized Peroxisomes Are Selectively Degraded via Autophagy in Arabidopsis
Highly Oxidized Peroxisomes Are Selectively Degraded via Autophagy in Arabidopsis
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DOI：
10.1105/tpc.113.116947
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发表时间：
2013-12-01
期刊：
影响因子：
11.6
通讯作者：
Nishimura, Mikio
中科院分区：
文献类型：
--
作者：
Shibata, Michitaro;Oikawa, Kazusato;Nishimura, Mikio
过氧化物酶体在细胞中的定位是一个与其功能密切相关的调控过程。利用过氧化物酶体定位的这一特征作为标准，我们鉴定了三种含有聚集过氧化物酶体的拟南芥突变体（过氧化物酶体异常定位1 [peup1]， peup2和peup4）。我们发现PEUP1、PEUP2和PEUP4分别与参与自噬系统的Autophagy-related2 （ATG2）、ATG18a和ATG7相同。peup1突变体中过氧化物酶体数量增加，过氧化物酶体蛋白高度积累，表明peup1突变体缺乏自噬降解过氧化物酶体。这些聚集的过氧化物酶体含有高水平的无活性过氧化氢酶，并且比野生型的过氧化氢酶更具氧化性，这表明过氧化物酶体聚集物包括受损的过氧化物酶体。此外，过氧化氢在野生型植物中诱导过氧化物酶体聚集。cat2突变体也含有过氧化物酶体聚集体。这些发现表明过氧化氢酶失活后的过氧化氢是过氧化物酶体聚集的诱导剂。此外，自噬体标志物ATG8经常与过氧化物酶体聚集体共定位，表明过氧化氢损伤的过氧化物酶体在野生型中被自噬选择性降解。我们的数据提供了自噬对拟南芥过氧化物酶体质量控制机制至关重要的证据。
The positioning of peroxisomes in a cell is a regulated process that is closely associated with their functions. Using this feature of the peroxisomal positioning as a criterion, we identified three Arabidopsis thaliana mutants (peroxisome unusual positioning1 [peup1], peup2, and peup4) that contain aggregated peroxisomes. We found that the PEUP1, PEUP2, and PEUP4 were identical to Autophagy-related2 (ATG2), ATG18a, and ATG7, respectively, which are involved in the autophagic system. The number of peroxisomes was increased and the peroxisomal proteins were highly accumulated in the peup1 mutant, suggesting that peroxisome degradation by autophagy (pexophagy) is deficient in the peup1 mutant. These aggregated peroxisomes contained high levels of inactive catalase and were more oxidative than those of the wild type, indicating that peroxisome aggregates comprise damaged peroxisomes. In addition, peroxisome aggregation was induced in wild-type plants by exogenous application of hydrogen peroxide. The cat2 mutant also contained peroxisome aggregates. These findings demonstrate that hydrogen peroxide as a result of catalase inactivation is the inducer of peroxisome aggregation. Furthermore, an autophagosome marker, ATG8, frequently colocalized with peroxisome aggregates, indicating that peroxisomes damaged by hydrogen peroxide are selectively degraded by autophagy in the wild type. Our data provide evidence that autophagy is crucial for quality control mechanisms for peroxisomes in Arabidopsis.