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1、Come from： Plant Physiology and Biochemistry 59 (2012) 11-19选自 ：爱思维尔世界领先的科技与医学出版社 植物生理学与生物化学 期刊号 59（2012）11-19Author：Farida Minibayeva*, Svetlana Dmitrieva, Anastasia Ponomareva, Victoria Ryabovol姓名：姓名：专业：专业：学号：学号： (1)自噬的两面性 It promotes survival by degrading proteins and organelles damaged during ox

2、idative stress, but it is also activated as a part of death programs, when the damage cannot be overcome. 自噬如果能退化掉在氧化胁迫中坏死的组织以及蛋白质就能促进生存下来。但是如果损伤不能被退化掉，它也可能作为被激活的死亡部分。 （1）自噬的分阶过程： Two distinct pathways exist in plants.Either autophagosomes can fuse directly with the vacuole (microautophagy) or they

3、can initially be engulfed by a smallerlysosome-like or endosome-like organelle. 自噬体可以直接和微噬体或者液泡融合。或者可以在开始的时候被像溶酶体或者核内体样子的结构吞噬掉。 （2）相对于对酵母、哺乳动物自噬的广泛研究，对植物自噬过程的研究还很少。 Evidence is accumulating that the cellular sites of ROS production and signaling may be primary targets of autophagy。 当时有少量证据表明已经显示活性氧产

4、品产生位点以及发信号位点是自吞噬的首选位点。 autophagosomal targeting of ROS-producing organelles such as chloroplasts (chlorophagy), peroxisomes (pexophagy),and mitochondria (mitophagy) is of particular importance。 其中产氧气组织有叶绿体、叶绿素、过氧化物酶体、线粒体等。 （1） Recent research efforts have shed light on the biochemical autophagic mac

5、hinery and the crucial role of several genes called (ATG)-related genes in the execution of this process. The coremachinery comprises 18 ATG proteins。 自噬往往与ATG基因有关，更进一步说是与ATG蛋白质家族有关。 （2） 主要的核心机制 PAS was known as the preautophagosoma structure PAS被成为前自噬体结构。 （3）前自噬体到自噬体的转换过程 It expand to form autophag

6、osomes with a diameter of 500-1000 nm, and the subsequent fusion of these vesicles with lysosomal or vacuolar compartments for cargo degradation。 它能进一步扩展成为直径为500-1000nm的结构，以及随后的与溶酶体以及液泡的融合为了物质的降解 。 （4）植物中研究最多的是拟南芥。它类似于我们研究阳性细菌使用大肠杆菌、研究真菌使用酵母等。 The Arabidopsis genome has homologs to almost all of the

7、 yeast ATG genes. 对于拟南芥植物而言，有与酵母ATG基因相同的东西 。 In pathway， ROS function as signaling molecules to trigger autophagy . 在这个路径中，ROS就好像促活机制一样，作为信号分子来触发自噬进行。 3.1 ROS-induced oxidative modifications of macromolecules ROS诱导对大分子的氧化修饰 （1）Reactive oxygen species may affect the members of signaling pathways such

8、 as protein kinases, protein phosphatases, and transcription factors。 发信号过程中可能涉及到的相关品种，比如，蛋白激酶、蛋白磷酸化酶以及转录因子等 （2）when plants are subjected to severe stresses ortoxic ROS inducing agents, excess ROS are generated. 当植物遭受严厉的胁迫或者有毒的ros诱导药剂时，过量的ROS会产生。 （3）Other irreversible protein modifications induced b

9、y ROS include di-Tyr formation,protein-protein cross-linking, and Lys and Arg carbonylation . All these oxidative modifications can result in detrimental consequences leading to loss of cell function, and ultimately cell death. 另一种被ROS诱导的蛋白质修饰是二次酪蛋白、蛋白蛋白十字相连、赖氨酸以及精氨酸的羧基化。 所有这些氧化修饰都能导致细胞死亡或者功能缺失等后果。

10、3.2 Autophagy as an antioxidative mechanism （1） Timely isolation ，elimination and degradation of oxidized macromolecules and damaged organelles can be considered as a crucial mechanism of antioxidative defence. 及时隔离、消除和降解被氧化的大分子和损伤的细胞器可以被认为是一种重要的抗氧化防御机制。 （2）Under normal conditions, protein degradati

11、on ismediated by both the autophagic pathway and the ubiquitineproteasome system。 正常条件下，蛋白质的降解是经由自吞噬途径和泛素介导的蛋白酶系统共同完成的。 Disruption of the autophagy pathway at earlier steps also leads to accumulation of ubiquitinated proteins,increased ROS and dysfunctional mitochondria. ATG18 down-regulation in Ara

12、bidopsis plants leads to the accumulation of oxidized proteins. 自噬过程的中断也导致泛素蛋白的积累，比如ROS以及功能失效的线粒体。拟南芥下调ATG18也可能导致氧化型蛋白质的积累。 clearly, autophagy plays an important role in protecting plant cells from oxidative stresses by degrading oxidized proteins 显然，自噬通过降解氧化性蛋白可以使植物细胞免于氧胁迫的深度影响。 Under severe stress

13、, however, the ubiquitine proteasome pathway can be over-whelmed, and the autophagic pathway is then required to increase its activity to compensate for the increased protein damage 在严重胁迫下，泛素介导的蛋白酶途径可能被淹没，自吞噬途径不得不通过增加它的活动来弥补增加蛋白质的损伤。（3） Dysregulation of autophagy 自吞噬的异常调节 It increases in oxidative s

14、tress, as shown by pharmacological inhibitor and knockout studies。 自吞噬异常调节导致氧胁迫增强。例如，药理抑制剂，淘汰赛研究。 ATG mutants display early senescence and accelerated production of floral stems even under optimal growth conditions。 ATG 突变株可以导致早期衰老以及加速植物茎的生长，即使在最佳生长条件下。oxidative stress inwheat roots caused by prooxi

15、dants paraquat and salicylic acid results in intensive formation of autophagosomes similarly to that induced by lithium ions。 在小麦根部由百草枯或者水杨酸导致的氧胁迫诱导自噬。 Salt and osmotic stresses can also increase the production of ROS and cause damage to proteins。 盐以及渗透压力还可以提高ROS的产生以及对蛋白质造成损伤。 Detailed phenotypic an

16、alysis of autophagy-deficient Arabidopsis mutants revealed that autophagy may play some roles in normal developmental processes since atg mutants display early senescence and accelerated production of floral stems even under optimal growth conditions 详细的拟南芥突变体自噬缺陷的表型分析显示，由于突变体显示早起衰落和，并且即使在最佳生长条件下也能加

17、速植物茎的生长，所以自噬在正常发育过程中有重要作用。 Autophagy has also been shown to transport aggregated proteins to the plant vacuole for degradation and damage to proteins during salt or osmotic stress may cause aggregation 自噬也被证明是可以将密集蛋白质运输到降解的植物液泡，可以危害到盐或渗透压作用下的聚合蛋白质。 5.1 ROS generating sites in mitochondria Recent stu

18、dies indicate that plant mitochondria are at a crosspoint in the signaling pathways involving ROS, especially those concerning cell death 最近的研究表明,植物线粒体是一个包含ROS特别是有关细胞死亡的信号传输通道的交错点 5.2. Oxidative modifications of macromolecules in mitochondria In normal conditions the level of O2 in mitochondria is l

19、ow,however under stress conditions when an increased demand for ATP accelerates the electron transfer via ETC, the mitochondrial membrane potential and the rates of ROS production in mitochondria are also elevated. 线粒体中正常水平下的氧气含量很低，然而在外界压力条件下，ATP含量会通过ETC转化和线粒体膜电位而增加，ATP含量的增加致使线粒体中ROS产量升高。 Mitochondr

20、ial mechanisms to survive: the activation of antioxidative defence, energy-dissipating systems,and mitophagy 线粒体生存机制：激活的抗氧化防御系统，耗能系统和线状噬菌体 6.1. Mitochondrial antioxidative systems ROS formation in mitochondria is controlled by several mechanisms including ROS-processing enzymes, non-enzymatic antiox

21、idants and uncoupling of electronflow from phosphorylation. 线粒体活性氧ROS的形成是由几种包括活性氧处理酶、非酶抗氧化剂和磷酸化的解偶联作用。 6.2. Energy-dissipating systems An attractive idea emerging in recent years is that AOX plays a crucial role in regulating the oxygen homeostasis within mitochondria, in particular under stress con

22、ditions, when the possibility of ROS production is increased by uncontrolled electron transfer to oxygen. 最近几年出现了一个有吸引力的观点，当ROS通过自由电子转移到氧分子的产量可能增加时，特别是在外界压力下AOX在调节氧气和线粒体的内部平衡起着关键作用。 6.3. Mitophagy as a selective autophagy Accordingly, damaged, aged or malfunctioning mitochondria are a risk factor for the cell, and proper elimination of such organelles. 损伤或故障的线粒体对细胞而