Song Qian, Liu Hongjin, Zhen Hui, Zhao Bosheng
Laboratory of Developmental and Evolutionary Biology, Shandong University of Technology, Zibo, 255049 Shandong China.
Cell Biosci. 2020 Sep 21;10:111. doi: 10.1186/s13578-020-00467-3. eCollection 2020.
Acting as a cellular cleaner by packaging and transporting defective proteins and organelles to lysosomes for breakdown, autophagic process is involved in the regulation of cell remodeling after cell damage or cell death in both vertebrate and invertebrate. In human, limitations on the regenerative capacity of specific tissues and organs make it difficult to recover from diseases. Comprehensive understanding on its mechanism within invertebrate have strong potential provide helpful information for challenging these diseases.
In this study, recent findings on the autophagy function in three invertebrates including planarian, hydra and leech with remarkable regenerative ability were summarized. Furthermore, molecular phylogenetic analyses of DjATGs and HvATGs were performed on these three invertebrates compared to that of , , , and .
In comparison with , , , and human, our analysis exhibits the following characteristics of autophagy and its function in regeneration within invertebrate. Phylogenetical analysis of ATGs revealed that most autophagy-related genes (ATGs) were highly similar to their homologs in other species, which indicates that autophagy is a highly conservative biological function in both vertebrate and invertebrate. Structurally, almost all the core amino acids necessary for the function of ATG8 in mammal were observed in invertebrate HvATG8s and DjATG8s. For instance, ubiquitin-like domain as a signature structure in each ATG8, was observed in all ATG8s in three invertebrates. Basically, autophagy plays a key role in the regulation of regeneration in planarian. DjATG8-2 and DjATG8-3 associated with mTOR signaling pathway are sophisticated in the invertebrate tissue/organ regeneration. Furthermore, autophagy is involved in the pathway of neutralization of toxic molecules input from blood digestion in the leech.
The recent investigations on autophagy in invertebrate including planarian, hydra and leech suggest that autophagy is evolutionally conserved from yeast to mammals. The fundamental role of its biological function in the invertebrate contributing to the regeneration and maintenance of cellular homeostasis in these three organisms could make tremendous information to confront life threatening diseases in human including cancers and cardiac disorders.
自噬过程通过将有缺陷的蛋白质和细胞器包装并运输到溶酶体进行分解，从而充当细胞清洁剂，参与脊椎动物和无脊椎动物细胞损伤或细胞死亡后细胞重塑的调节。在人类中，特定组织和器官再生能力的限制使得疾病难以恢复。全面了解其在无脊椎动物体内的机制具有很大潜力，可为攻克这些疾病提供有用信息。
在本研究中，总结了近期关于三种具有显著再生能力的无脊椎动物（涡虫、水螅和水蛭）自噬功能的研究结果。此外，对这三种无脊椎动物的DjATGs和HvATGs进行了分子系统发育分析，并与[具体物种1]、[具体物种2]、[具体物种3]、[具体物种4]和人类的进行了比较。
与[具体物种1]、[具体物种2]、[具体物种3]、[具体物种4]和人类相比，我们的分析揭示了无脊椎动物自噬及其在再生中的功能具有以下特征。对自噬相关基因（ATGs）的系统发育分析表明，大多数自噬相关基因与其在其他物种中的同源基因高度相似，这表明自噬在脊椎动物和无脊椎动物中都是一种高度保守的生物学功能。在结构上，在无脊椎动物的HvATG8s和DjATG8s中观察到了哺乳动物中ATG8功能所需的几乎所有核心氨基酸。例如，泛素样结构域作为每个ATG8中的标志性结构，在三种无脊椎动物的所有ATG8中都有观察到。基本上，自噬在涡虫再生调节中起关键作用。与mTOR信号通路相关的DjATG8-2和DjATG8-3在无脊椎动物组织/器官再生中很复杂。此外，自噬参与了水蛭血液消化中输入的有毒分子的中和途径。
近期对包括涡虫、水螅和水蛭在内的无脊椎动物自噬的研究表明，自噬从酵母到哺乳动物在进化上是保守的。其生物学功能在无脊椎动物中对这三种生物的再生和细胞内稳态维持的基本作用，可为应对包括癌症和心脏病在内的人类生命威胁性疾病提供大量信息。
