Howard Hughes Medical Institute, Department of Physiology, University of California, San Francisco, San Francisco, CA 94158, USA.
Neuron. 2012 Dec 6;76(5):921-30. doi: 10.1016/j.neuron.2012.10.008.
Microtubule nucleation is essential for proper establishment and maintenance of axons and dendrites. Centrosomes, the primary site of nucleation in most cells, lose their function as microtubule organizing centers during neuronal development. How neurons generate acentrosomal microtubules remains unclear. Drosophila dendritic arborization (da) neurons lack centrosomes and therefore provide a model system to study acentrosomal microtubule nucleation. Here, we investigate the origin of microtubules within the elaborate dendritic arbor of class IV da neurons. Using a combination of in vivo and in vitro techniques, we find that Golgi outposts can directly nucleate microtubules throughout the arbor. This acentrosomal nucleation requires gamma-tubulin and CP309, the Drosophila homolog of AKAP450, and contributes to the complex microtubule organization within the arbor and dendrite branch growth and stability. Together, these results identify a direct mechanism for acentrosomal microtubule nucleation within neurons and reveal a function for Golgi outposts in this process.
微管核形成对于轴突和树突的正确建立和维持至关重要。中心体是大多数细胞中核形成的主要场所，在神经元发育过程中失去了作为微管组织中心的功能。神经元如何产生无中心体的微管仍然不清楚。果蝇树突分支（da）神经元缺乏中心体，因此为研究无中心体微管核形成提供了一个模型系统。在这里，我们研究了 IV 类 da 神经元复杂的树突分支内微管的起源。通过体内和体外技术的结合，我们发现高尔基体突出物可以在整个树突中直接核形成微管。这种无中心体核形成需要γ-微管蛋白和 CP309，即果蝇 AKAP450 的同源物，并有助于树突分支生长和稳定性以及树突分支内的复杂微管组织。这些结果确定了神经元内无中心体微管核形成的直接机制，并揭示了高尔基体突出物在这个过程中的作用。
