Department of Biomedical Sciences of Cells and Systems, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands; University of Osnabrück, Department of Biology/Chemistry, Biochemistry section, Osnabrück, Germany; University of Osnabrück, Center of Cellular Nanoanalytics (CellNanOs), Osnabrück, Germany.
Department of Biomedical Sciences of Cells and Systems, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
J Biol Chem. 2023 May;299(5):104712. doi: 10.1016/j.jbc.2023.104712. Epub 2023 Apr 14.
Autophagy is a key process in eukaryotes to maintain cellular homeostasis by delivering cellular components to lysosomes/vacuoles for degradation and reuse of the resulting metabolites. Membrane rearrangements and trafficking events are mediated by the core machinery of autophagy-related (Atg) proteins, which carry out a variety of functions. How Atg9, a lipid scramblase and the only conserved transmembrane protein within this core Atg machinery, is trafficked during autophagy remained largely unclear. Here, we addressed this question in yeast Saccharomyces cerevisiae and found that retromer complex and dynamin Vps1 mutants alter Atg9 subcellular distribution and severely impair the autophagic flux by affecting two separate autophagy steps. We provide evidence that Vps1 interacts with Atg9 at Atg9 reservoirs. In the absence of Vps1, Atg9 fails to reach the sites of autophagosome formation, and this results in an autophagy defect. The function of Vps1 in autophagy requires its GTPase activity. Moreover, Vps1 point mutants associated with human diseases such as microcytic anemia and Charcot-Marie-Tooth are unable to sustain autophagy and affect Atg9 trafficking. Together, our data provide novel insights on the role of dynamins in Atg9 trafficking and suggest that a defect in this autophagy step could contribute to severe human pathologies.
自噬是真核生物中通过将细胞成分递送至溶酶体/液泡进行降解和再利用代谢产物来维持细胞内稳态的关键过程。膜重排和运输事件由自噬相关（Atg）蛋白的核心机制介导，该机制执行多种功能。在自噬过程中，Atg9 如何运输，一种脂质翻转酶，也是该核心 Atg 机制中唯一保守的跨膜蛋白，在很大程度上仍不清楚。在这里，我们在酵母酿酒酵母中解决了这个问题，发现 retromer 复合物和 dynamin Vps1 突变体改变了 Atg9 的亚细胞分布，并通过影响两个独立的自噬步骤严重损害自噬通量。我们提供的证据表明 Vps1 在 Atg9 储库中与 Atg9 相互作用。在没有 Vps1 的情况下，Atg9 无法到达自噬体形成的部位，这导致自噬缺陷。Vps1 在自噬中的功能需要其 GTPase 活性。此外，与人类疾病（如小细胞性贫血和 Charcot-Marie-Tooth）相关的 Vps1 点突变体无法维持自噬并影响 Atg9 运输。总之，我们的数据提供了有关 dynamin 在 Atg9 运输中的作用的新见解，并表明该自噬步骤的缺陷可能导致严重的人类病理。
