Planar cell polarity: the prickle gene acts independently on both the Ds/Ft and the Stan/Fz systems

Epithelial cells are polarised within the plane of the epithelium, forming oriented structures that have a coordinated and consistent polarity (planar cell polarity, PCP). In Drosophila, at least two separate molecular systems generate and interpret intercellular polarity signals: Dachsous/Fat, and the ‘core’ or Starry night/Frizzled system. Here, we study the prickle gene and its protein products Prickle and Spiny leg. Much research on PCP has focused on the asymmetric localisation of core proteins in the cell and as a result prickle was placed in the heart of the Starry night/Frizzled system. We investigate whether this view is correct and how the prickle gene relates to the two systems. We find that prickle can affect, separately, both systems; however, neither Prickle nor Spiny leg are essential components of the Dachsous/Fat or the Starry night/Frizzled system, nor do they act as a functional link between the two systems.