Bazooka and atypical protein kinase C are required to regulate oocyte differentiation in the Drosophila ovary

The par genes, identified by their role in the establishment of anterior-po sterior polarity in the Caenorhabditis elegans zygote, subsequently have be en shown to regulate cellular polarity in diverse cell types by means of an evolutionarily conserved protein complex including PAR-3, PAR-6, and atypi cal protein kinase C (aPKC). The Drosophila homologs of par-1, par-3 (bazoo ka, baz), par-6 (DmPar-6), and pkc-3 (Drosophila aPKC, DaPKC) each are know n to play conserved roles in the generation of cell polarity in the germ li ne as well as in epithelial and neural precursor cells within the embryo. i n light of this functional conservation, we examined the potential role of baz and DaPKC in the regulation of oocyte polarity. Our analyses reveal ger m-line autonomous roles for baz and DaPKC in the establishment of initial a nterior-posterior polarity within germ-line cysts and maintenance of oocyte cell fate. Germ-line clonal analyses indicate both proteins are essential for two key aspects of oocyte determination: the posterior translocation of oocyte specification factors and the posterior establishment of the microt ubule organizing center within the presumptive oocyte. We demonstrate BAZ a nd DaPKC colocalize to belt-like structures between germarial cyst cells. H owever, in contrast to their regulatory relationship in the Drosophila and C. elegans embryos, these proteins are not mutually dependent for their ger m-line localization, nor is either protein specifically required for PAR-1 localization to the fusome. Therefore, whereas BAZ, DaPKC, and PAR-1 are fu nctionally conserved in establishing oocyte polarity, the regulatory relati onships among these genes are not well conserved, indicating these molecule s function differently in different cellular contexts.