Institute of Molecular Medicine and Genetics, and Department of Neurology, Medical College of Georgia, Georgia Health Sciences University , Augusta, GA 30912 , USA.
Biol Open. 2012 Dec 15;1(12):1248-57. doi: 10.1242/bio.20122451. Epub 2012 Oct 11.
VPS35, a major component of the retromer, plays an important role in the selective endosome-to-Golgi retrieval of membrane proteins. Dysfunction of retromer is a risk factor for neurodegenerative disorders, but its function in developing mouse brain remains poorly understood. Here we provide evidence for VPS35 promoting dendritic growth and maturation, and axonal protein transport in developing mouse hippocampal neurons. Embryonic hippocampal CA1 neurons suppressing Vps35 expression by in utero electroporation of its micro RNAs displayed shortened apical dendrites, reduced dendritic spines, and swollen commissural axons in the neonatal stage, those deficits reflecting a defective protein transport/trafficking in developing mouse neurons. Further mechanistic studies showed that Vps35 depletion in neurons resulted in an impaired retrograde trafficking of BACE1 (β1-secretase) and altered BACE1 distribution. Suppression of BACE1 expression in CA1 neurons partially rescued both dendritic and axonal deficits induced by Vps35-deficiency. These results thus demonstrate that BACE1 acts as a critical cargo of retromer in vitro and in vivo, and suggest that VPS35 plays an essential role in regulating apical dendritic maturation and in preventing axonal spheroid formation in developing hippocampal neurons.
VPS35 是 retromer 的主要组成部分，在膜蛋白的选择性内体-高尔基体回收到中发挥重要作用。retromer 的功能障碍是神经退行性疾病的一个风险因素，但它在发育中的老鼠大脑中的功能仍知之甚少。在这里，我们提供了证据表明 VPS35 促进了发育中的老鼠海马神经元的树突生长和成熟以及轴突蛋白运输。通过对其 microRNAs 进行体内电穿孔抑制 Vps35 表达的胚胎海马 CA1 神经元在新生儿期表现出短的顶树突、减少的树突棘和膨胀的连合轴突，这些缺陷反映了发育中的老鼠神经元中存在缺陷的蛋白运输/运输。进一步的机制研究表明，神经元中的 Vps35 耗竭导致 BACE1（β1-分泌酶）的逆行转运受损，并且 BACE1 分布发生改变。在 CA1 神经元中抑制 BACE1 表达部分挽救了由 Vps35 缺陷引起的树突和轴突缺陷。这些结果表明 BACE1 在体外和体内作为 retromer 的关键货物，并且表明 VPS35 在调节发育中的海马神经元中的顶树突成熟和防止轴突球体形成中发挥重要作用。
