Atypical Protein Kinase C Regulates Primary Dendrite Specification of Cerebellar Purkinje Cells by Localizing Golgi Apparatus

Abstract

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.

Synaptic Distributions of GluA2 and PKMζ in the Monkey Dentate Gyrus and Their Relationships with Aging and Memory

“…This antiserum also recognizes phosphorylated PKCι, the other atypical PKC that shares a nearly identical C-terminus with PKCζ (Hernandez et al, 2003). PKCι, however, localizes to the cell body and nucleus (White et al, 2002) and is involved in organization of the Golgi apparatus (Tanabe et al, 2010) and microtubules (Tisdale, 2002), both of which are absent in the dendritic spine. Although PKMζ immunolabeling is indistinguishable from PKCζ immunolabeling due to their identical amino acid sequence, PKMζ is expressed in the forebrain as the major form of ζ in the near absence of PKCζ in rodents (Hernandez et al, 2003; Oster et al, 2004) and in humans (Crary et al, 2006).…”

Apical complex protein Pals1 is required to maintain cerebellar progenitor cells in a proliferative state

“…Polarity complexes include evolutionarily conserved apical complex proteins, such as the Crb complex (comprising Crbs, Pals1, Patj), the Par complex (Par3, Par6, aPKC) and basal complex proteins, such as the Scribble complex (Scribbles, Lgl, Dlg) (Assémat et al, 2008;Pieczynski and Margolis, 2011;Tepass, 2012). Previous studies have demonstrated that apical complex proteins are necessary for self-renewal of neural progenitor cells (Bultje et al, 2009;Costa et al, 2008;Kim et al, 2010), neuronal migration (Famulski et al, 2010;Solecki et al, 2006), axon determination (Chen et al, 2013;Shi et al, 2003), dendrite development (Tanabe et al, 2010), tissue polarity and neuron survival (Kim et al, 2010). However, there is little information about the function of apical complex proteins in the regulation of proliferation and differentiation of CGNPs, which lack typical apical-basal polarity.…”

Atypical Protein Kinase Cι Is Required for Wnt3a-dependent Neurite Outgrowth and Binds to Phosphorylated Dishevelled 2

“…1 entiation of a neurite into an axon (22). Recent studies have indicated that the aPKC-Par3-Par6 complex participates in neurite outgrowth before and after axon differentiation, as well as in dendrite formation (23)(24)(25). Of note, Wnt4 attracts the outgrowth of commissural axons by a mechanism that relies on aPKC (24).…”