Centriole planar polarity assessment in Drosophila wings

In vertebrates, planar polarization of ciliary basal bodies has been associated with actin polymerization that acts downstream of the Frizzled-planar cell polarity (Fz-PCP) pathway. In Drosophila wing epithelial cells, which do not have cilia, centrioles also polarize in a Fz-PCP dependent manner, although the relationship with actin polymerization remains unknown. By combining existing and new quantitative methods, we unexpectedly found that known PCP effectors linked to actin polymerization phenotypes affect neither final centriole polarization nor apical centriole distribution. But actin polymerization is required upstream of Fz-PCP to maintain the centrioles in restricted areas in the apical-most planes of those epithelial cells before and after the actin-based hair is formed. Furthermore, in the absence of proper core Fz-PCP signaling, actin polymerization is insufficient to drive this off-centred centriole migration. Altogether, the results reveal that there are at least two pathways controlling centriole positioning in Drosophila pupal wings – an upstream actin-dependent mechanism involved in centriole distribution which is PCP independent, and an unknown mechanism that links core Fz-PCP and centriole polarization.