Laboratory for Vertebrate Axis Formation, RIKEN Center for Developmental Biology, Kobe, Hyogo 650-0047, Japan.
J Neurosci. 2010 Dec 15;30(50):16983-92. doi: 10.1523/JNEUROSCI.3352-10.2010.
Neurons have highly polarized structures that determine what parts of the soma elaborate the axon and dendrites. However, little is known about the mechanisms that establish neuronal polarity in vivo. Cerebellar Purkinje cells extend a single primary dendrite from the soma that ramifies into a highly branched dendritic arbor. We used the zebrafish cerebellum to investigate the mechanisms by which Purkinje cells acquire these characteristics. To examine dendritic morphogenesis in individual Purkinje cells, we marked the cell membrane using a Purkinje cell-specific promoter to drive membrane-targeted fluorescent proteins. We found that zebrafish Purkinje cells initially extend multiple neurites from the soma and subsequently retract all but one, which becomes the primary dendrite. In addition, the Golgi apparatus specifically locates to the root of the primary dendrite, and its localization is already established in immature Purkinje cells that have multiple neurites. Inhibiting secretory trafficking through the Golgi apparatus reduces dendritic growth, suggesting that the Golgi apparatus is involved in the dendritic morphogenesis. We also demonstrated that in a mutant of an atypical protein kinase C (aPKC), Prkci, Purkinje cells retain multiple primary dendrites and show disrupted localization of the Golgi apparatus. Furthermore, a mosaic inhibition of Prkci in Purkinje cells recapitulates the aPKC mutant phenotype. These results suggest that the aPKC cell autonomously controls the Golgi localization and thereby regulates the specification of the primary dendrite of Purkinje cells.
神经元具有高度极化的结构，决定了胞体的哪些部分延伸出轴突和树突。然而，对于在体内建立神经元极性的机制知之甚少。小脑浦肯野细胞从胞体延伸出一个单一的初级树突，该树突分支成高度分支的树突树。我们使用斑马鱼小脑来研究浦肯野细胞获得这些特征的机制。为了检查单个浦肯野细胞的树突形态发生，我们使用浦肯野细胞特异性启动子标记细胞膜，以驱动膜靶向荧光蛋白。我们发现，斑马鱼浦肯野细胞最初从胞体延伸出多个神经突，然后缩回除一个之外的所有神经突，这个神经突成为初级树突。此外，高尔基器专门定位到初级树突的根部，并且其定位在具有多个神经突的未成熟浦肯野细胞中已经建立。通过高尔基器抑制分泌转运会减少树突生长，表明高尔基器参与了树突形态发生。我们还证明，在一个非典型蛋白激酶 C（aPKC）突变体 Prkci 中，浦肯野细胞保留多个初级树突，并且高尔基器的定位被打乱。此外，在浦肯野细胞中对 Prkci 进行马赛克抑制可重现 aPKC 突变体的表型。这些结果表明，aPKC 细胞自主控制高尔基器的定位，从而调节浦肯野细胞的初级树突的特化。
