Department of Functional Genomics, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, Vrije Universiteit (VU), Amsterdam, Netherlands.
Clinical Genetics, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU medical center, Amsterdam, Netherlands.
Sci Rep. 2018 Feb 14;8(1):2996. doi: 10.1038/s41598-018-20448-4.
The endosomal system is proposed as a mediator of synaptic vesicle recycling, but the molecular recycling mechanism remains largely unknown. Retromer is a key protein complex which mediates endosomal recycling in eukaryotic cells, including neurons. Retromer is important for brain function and mutations in retromer genes are linked to neurodegenerative diseases. In this study, we aimed to determine the role of retromer in presynaptic structure and function. We assessed the role of retromer by knocking down VPS35, the core subunit of retromer, in primary hippocampal mouse neurons. VPS35 depletion led to retromer dysfunction, measured as a decrease in GluA1 at the plasma membrane, and bypassed morphological defects previously described in chronic retromer depletion models. We found that retromer is localized at the mammalian presynaptic terminal. However, VPS35 depletion did not alter the presynaptic ultrastructure, synaptic vesicle release or retrieval. Hence, we conclude that retromer is present in the presynaptic terminal but it is not essential for the synaptic vesicle cycle. Nonetheless, the presynaptic localization of VPS35 suggests that retromer-dependent endosome sorting could take place for other presynaptic cargo.
内体系统被认为是介导突触囊泡循环的介质，但分子循环机制在很大程度上仍不清楚。Retromer 是一种关键的蛋白质复合物，介导真核细胞中的内体循环，包括神经元。Retromer 对大脑功能很重要，Retromer 基因的突变与神经退行性疾病有关。在这项研究中，我们旨在确定 Retromer 在突触前结构和功能中的作用。我们通过在原代海马体小鼠神经元中敲低 Retromer 的核心亚基 VPS35 来评估 Retromer 的作用。VPS35 的耗竭导致 Retromer 功能障碍，表现为质膜上 GluA1 的减少，并且绕过了先前在慢性 Retromer 耗竭模型中描述的形态缺陷。我们发现 Retromer 位于哺乳动物突触前末端。然而，VPS35 的耗竭并没有改变突触前超微结构、突触囊泡释放或回收。因此，我们得出结论，Retromer 存在于突触前末端，但对于突触囊泡循环不是必需的。尽管如此，VPS35 的突触前定位表明，Retromer 依赖性内体分选可能发生在其他突触前货物上。
