Carotenoid deficiency triggers autophagy in the model green alga Chlamydomonas reinhardtii
Carotenoid deficiency triggers autophagy in the model green alga Chlamydomonas reinhardtii
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DOI：
10.4161/auto.18864
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发表时间：
2012-03-01
期刊：
影响因子：
13.3
通讯作者：
Crespo, Jose L.
中科院分区：
文献类型：
--
作者：
Esther Perez-Perez, Maria;Couso, Inmaculada;Crespo, Jose L.
所有需氧生物都已经发展出复杂的机制来预防、检测和应对由不可避免的活性氧（ROS）产生所引起的细胞损伤。植物和藻类能够在叶绿体中合成称为类胡萝卜素的特定色素，以防止由光合作用的高活性副产物引起的光氧化损伤。在这项研究中，我们使用的单细胞绿色衣藻来证明类胡萝卜素生物合成的缺陷导致自噬的激活，膜运输过程中，参与回收和降解受损或有毒的细胞成分。八氢番茄红素合成酶的突变或除草剂氟草酮对八氢番茄红素去饱和酶的抑制导致类胡萝卜素耗竭，导致自噬的强烈诱导。我们发现，强光瞬时激活野生型衣原体细胞中的自噬，作为对这种压力的适应反应的一部分。我们的研究结果表明，衣原体突变体在合成特定的类胡萝卜素，在强光胁迫下积累缺陷表现出组成性自噬。此外，抑制ROS生成NADPH氧化酶部分降低了与类胡萝卜素缺乏相关的自噬诱导，这揭示了类胡萝卜素含量降低的衣原体细胞中光氧化损伤、ROS积累和自噬激活之间的联系。
All aerobic organisms have developed sophisticated mechanisms to prevent, detect and respond to cell damage caused by the unavoidable production of reactive oxygen species (ROS). Plants and algae are able to synthesize specific pigments in the chloroplast called carotenoids to prevent photo-oxidative damage caused by highly reactive by-products of photosynthesis. In this study we used the unicellular green alga Chlamydomonas reinhardtii to demonstrate that defects in carotenoid biosynthesis lead to the activation of autophagy, a membrane-trafficking process that participates in the recycling and degradation of damaged or toxic cellular components. Carotenoid depletion caused by either the mutation of phytoene synthase or the inhibition of phytoene desaturase by the herbicide norflurazon, resulted in a strong induction of autophagy. We found that high light transiently activates autophagy in wild-type Chlamydomonas cells as part of an adaptation response to this stress. Our results showed that a Chlamydomonas mutant defective in the synthesis of specific carotenoids that accumulate during high light stress exhibits constitutive autophagy. Moreover, inhibition of the ROS-generating NADPH oxidase partially reduced the autophagy induction associated to carotenoid deficiency, which revealed a link between photo-oxidative damage, ROS accumulation and autophagy activation in Chlamydomonas cells with a reduced carotenoid content.