Time-resolved function of cell polarity kinases PRKCZ and PRKCI in CNS myelination

The atypical Protein Kinase C (aPKC) is a critical component of the PAR polarity complex, as well as of cell polarity in general. There are two paralogs of aPKC in the mammalian genome. Their expression pattern and functional role in oligodendrocyte lineage differentiation and development remains heretofore uncharacterized. Here we show that both paralogs of aPKC - PRKCI, the primary transcript of Prkci and PKMz, an alternate transcript of Prkcz - are expressed during oligodendrocyte differentiation, yet are functionally non-redundant. Asymmetric cell division and early specification of the oligodendrocyte fate stage required both paralogs. By contrast, the stage of oligodendrocyte maturation involving membrane polarization and myelination of axons continued to require PKMz, but no longer needed PRKCI. Taken together, our results indicate to a two-stage role of aPKCs and cell polarity in oligodendrocyte differentiation and development.