Department of Pathology, Harvard Medical School, Boston, Massachusetts, United States of America.
PLoS Biol. 2011 May;9(5):e1001060. doi: 10.1371/journal.pbio.1001060. Epub 2011 May 10.
The elaboration of dendrites in neurons requires secretory trafficking through the Golgi apparatus, but the mechanisms that govern Golgi function in neuronal morphogenesis in the brain have remained largely unexplored. Here, we report that the E3 ubiquitin ligase Cul7(Fbxw8) localizes to the Golgi complex in mammalian brain neurons. Inhibition of Cul7(Fbxw8) by independent approaches including Fbxw8 knockdown reveals that Cul7(Fbxw8) is selectively required for the growth and elaboration of dendrites but not axons in primary neurons and in the developing rat cerebellum in vivo. Inhibition of Cul7(Fbxw8) also dramatically impairs the morphology of the Golgi complex, leading to deficient secretory trafficking in neurons. Using an immunoprecipitation/mass spectrometry screening approach, we also uncover the cytoskeletal adaptor protein OBSL1 as a critical regulator of Cul7(Fbxw8) in Golgi morphogenesis and dendrite elaboration. OBSL1 forms a physical complex with the scaffold protein Cul7 and thereby localizes Cul7 at the Golgi apparatus. Accordingly, OBSL1 is required for the morphogenesis of the Golgi apparatus and the elaboration of dendrites. Finally, we identify the Golgi protein Grasp65 as a novel and physiologically relevant substrate of Cul7(Fbxw8) in the control of Golgi and dendrite morphogenesis in neurons. Collectively, these findings define a novel OBSL1-regulated Cul7(Fbxw8) ubiquitin signaling mechanism that orchestrates the morphogenesis of the Golgi apparatus and patterning of dendrites, with fundamental implications for our understanding of brain development.
树突在神经元中的发育需要通过高尔基体进行分泌运输，但控制大脑神经元形态发生中高尔基体功能的机制在很大程度上仍未被探索。在这里，我们报告 E3 泛素连接酶 Cul7（Fbxw8）在哺乳动物大脑神经元中定位于高尔基体复合物。通过包括 Fbxw8 敲低在内的独立方法抑制 Cul7（Fbxw8），我们发现 Cul7（Fbxw8）选择性地需要原始神经元和体内发育中的大鼠小脑中的树突生长和发育，但不需要轴突。Cul7（Fbxw8）的抑制也严重破坏了高尔基体复合物的形态，导致神经元中的分泌运输缺陷。使用免疫沉淀/质谱筛选方法，我们还发现细胞骨架衔接蛋白 OBSL1 是高尔基体形态发生和树突发育中 Cul7（Fbxw8）的关键调节因子。OBSL1 与支架蛋白 Cul7 形成物理复合物，从而将 Cul7 定位在高尔基体上。因此，OBSL1 是高尔基体形态发生和树突发育所必需的。最后，我们确定了高尔基蛋白 Grasp65 是 Cul7（Fbxw8）在控制神经元中高尔基体和树突形态发生的新的和生理相关的底物。总之，这些发现定义了一种新的 OBSL1 调节的 Cul7（Fbxw8）泛素信号机制，该机制协调了高尔基体的形态发生和树突的模式形成，对我们理解大脑发育具有重要意义。
