Department of Infection and Host Defense, Graduate School of Medicine, Chiba University, Chiba 260-8670, Japan.
Department of Biomedical Chemistry, The University of Tokyo, Tokyo 113-8654, Japan.
Cells. 2021 May 19;10(5):1258. doi: 10.3390/cells10051258.
Autophagy is a eukaryotic cellular machinery that is able to degrade large intracellular components, including organelles, and plays a pivotal role in cellular homeostasis. Target materials are enclosed by a double membrane vesicle called autophagosome, whose formation is coordinated by autophagy-related proteins (ATGs). Studies of yeast and Metazoa have identified approximately 40 ATGs. Genome projects for unicellular eukaryotes revealed that some ATGs are conserved in all eukaryotic supergroups but others have arisen or were lost during evolution in some specific lineages. In spite of an apparent reduction in the ATG molecular machinery found in parasitic protists, it has become clear that ATGs play an important role in stage differentiation or organelle maintenance, sometimes with an original function that is unrelated to canonical degradative autophagy. In this review, we aim to briefly summarize the current state of knowledge in parasitic protists, in the light of the latest important findings from more canonical model organisms. Determining the roles of ATGs and the diversity of their functions in various lineages is an important challenge for understanding the evolutionary background of autophagy.
自噬是真核细胞的一种细胞机制，能够降解包括细胞器在内的大型细胞内成分，在细胞稳态中起着关键作用。靶物质被称为自噬体的双层膜囊泡所包裹，其形成由自噬相关蛋白（ATG）协调。对酵母和后生动物的研究已经确定了大约 40 种 ATG。单细胞真核生物的基因组项目表明，一些 ATG 在所有真核超群中都保守，但其他 ATG 在某些特定谱系的进化过程中产生或丢失。尽管寄生原生动物中发现的 ATG 分子机制明显减少，但很明显，ATG 在阶段分化或细胞器维持中发挥重要作用，有时具有与经典降解自噬无关的原始功能。在这篇综述中，我们旨在根据更典型的模式生物的最新重要发现，简要总结寄生原生动物的最新知识状况。确定 ATG 的作用及其在各种谱系中的功能多样性是理解自噬进化背景的重要挑战。
