Center for Molecular Biology of Heidelberg University (ZMBH), Im Neuenheimer Feld 282, D-69120 Heidelberg, Germany
J Cell Sci. 2020 Sep 9;133(17):jcs246322. doi: 10.1242/jcs.246322.
Autophagy is fundamental for cell and organismal health. Two types of autophagy are conserved in eukaryotes: macroautophagy and microautophagy. During macroautophagy, autophagosomes deliver cytoplasmic constituents to endosomes or lysosomes, whereas during microautophagy lytic organelles take up cytoplasm directly. While macroautophagy has been investigated extensively, microautophagy has received much less attention. Nonetheless, it has become clear that microautophagy has a broad range of functions in biosynthetic transport, metabolic adaptation, organelle remodeling and quality control. This Review discusses the selective and non-selective microautophagic processes known in yeast, plants and animals. Based on the molecular mechanisms for the uptake of microautophagic cargo into lytic organelles, I propose to distinguish between fission-type microautophagy, which depends on ESCRT proteins, and fusion-type microautophagy, which requires the core autophagy machinery and SNARE proteins. Many questions remain to be explored, but the functional versatility and mechanistic diversity of microautophagy are beginning to emerge.
自噬对于细胞和生物机体的健康至关重要。真核生物中存在两种类型的自噬：巨自噬和微自噬。在巨自噬中，自噬体将细胞质成分递送至内体或溶酶体，而在微自噬中，溶酶体直接摄取细胞质。虽然巨自噬已经得到了广泛的研究，但微自噬受到的关注要少得多。然而，微自噬在生物合成运输、代谢适应、细胞器重塑和质量控制方面具有广泛的功能已变得清晰起来。这篇综述讨论了在酵母、植物和动物中已知的选择性和非选择性微自噬过程。基于将微自噬货物摄取到溶酶体的分子机制，我建议区分依赖于 ESCRT 蛋白的分裂型微自噬和需要核心自噬机制和 SNARE 蛋白的融合型微自噬。仍有许多问题有待探索，但微自噬的功能多样性和机制多样性开始显现出来。
