Organising cells into tissues: new roles for cell adhesion molecules in planar cell polarity

Planar cell polarity (PCP) is the coordinated organization of cells within the plane of the epithelium, first described in Drosophila. A Frizzled signalling pathway dedicated to PCP (the non-canonical Frizzled pathway) acts through Dishevelled and small G proteins, as does the classical Wnt pathway, but then diverges downstream of Dishevelled. Recent studies have demonstrated a crucial role for several atypical cadherin molecules (Fat, Dachsous and Flamingo) in controlling PCP signalling. Recent work has also indicated that the first sign of PCP during development is the polarized localization of PCP proteins (Frizzled, Flamingo, Dishevelled, etc). Exciting new data reveal that this PCP pathway is conserved to man.