鳞翅目昆虫中自噬相关分子Atg8的研究进展

自噬是细胞通过溶酶体自主降解以实现细胞内物质循环利用的过程,在昆虫细胞分化和个体发育中起着重要作用。鳞翅目昆虫属于完全变态昆虫,会通过自噬和凋亡完成蜕变重建过程,是研究自噬机制的模式生物。自噬相关蛋白Atg8是哺乳动物微管相关蛋白1轻链3的同系物,是自噬相关蛋白的核心蛋白家族,对自噬小体形成、膜的延伸、特定物质识别等具有重要意义。文中就鳞翅目昆虫Atg8在自噬信号通路中的作用、Atg8结构特点、Atg8表达分布及Atg8-PE/Atg8水平与自噬活性关系进行了综述。Atg8-PE是自噬信号通路中两个类泛素结合系统之一,在自噬中起着关键作用。序列分析表明,鳞翅目昆虫Atg8与其他真核生物同源蛋白的整体结构相似,尤其与其他昆虫同源蛋白的氨基酸序列高度一致,体现了Atg8的高度保守性。鳞翅目昆虫发育不同阶段,Atg8在中肠、唾液腺、卵巢、脂肪体、丝腺等器官中的表达分布各不相同。并且,Atg8在核质中分布也存在差异,Atg8在细胞核与细胞质之间的穿梭可能存在蛹化前阶段的某些细胞中。通过检测Atg8-PE在细胞内的表达水平或Atg8含量的变化,可以评价细胞自噬的发生程度。

Progress in the research of autophagy related molecule Atg8 in lepidopteran insects

Autophagy, a process of the cells to achieve the intracellular material recycling through the self-degradation of lysosome, plays an important role in insect cellular differentiation and individual development. Lepidopteran insects, belonging to the complete metamorphosis insects, could actualize metamorphosis reconstruction process by autophagy and apoptosis, and are the model organisms for studying the mechanisms of autophagy. Atg8 of lepidopteran insects, which is a homolog of microtubule associated protein 1 light chain 3 of mammals and the core protein family of autophagy-related protein, plays important roles in the formation of autophagosomes, the extension of membrane, the identification of specific substances, and so on. In this article we reviewed the Atg8 effect in autophagy pathway, the characterization of Atg8, the expression and distribution of Atg8, and the relationship between Atg8-PE/Atg8 and autophagic activity in lepidopteran insects. Atg8-PE is one of the ubiquitin-like conjugation systems, and plays a key role in autophagy. Sequence analysis showed that the structure of Atg8 in lepidopteran species is very similar to the homologous proteins of other eukaryotes, and especially its amino acid sequence is highly consistent with the homologous proteins of other insect species, revealing the highly conservative property of Atg8. During the different developmental stages of lepidopteran species, the expression and distribution of Atg8 are various in organs such as the midgut, salivary glands, ovary, fat body and silk glands, and different in nucleus and cytoplasm. The shuttling of Atg8 between nucleus and cytoplasm might exist in some cells at the pre-pupal stage. Through detecting the expression level of Atg8-PE or the change of Atg8 abundance inside the cell, we can evaluate the process of autophagy.