Asymmetric colocalization of Flamingo, a seven-pass transmembrane cadherin, and Dishevelled in planar cell polarization

The Drosophila wing provides an appropriate model system for studying genet ic programming of planar cell polarity (PCP) [1-4], Each wing cell respects the proximodistal (PD) axis; i.e., it localizes an assembly of actin bundl es to its distalmost vertex and produces a single prehair, This PD polariza tion requires the redistribution of Flamingo (Fmi), a seven-pass transmembr ane cadherin, to proximal/ distal cell boundaries; otherwise, the cell misl ocalizes the prehair [5], Achievement of the biased Fmi pattern depends on two upstream components in the PCP signaling pathway: Frizzled (Fz), a rece ptor for a hypothetical polarity signal, and an intracellular protein, Dish evelled (Dsh) [6-8]. Here, we visualized endogenous Dsh in the developing w ing. A portion of Dsh colocalized with Fmi, and the distributions of both p roteins were interdependent. Furthermore, Fz controlled the association of Dsh with cell boundaries, which association was correlated with the presenc e of hyperphosphorylated forms of Dsh, Our results, together with a recent study on Fz distribution [9], support the possibility that Fz, Dsh, and Fmi constitute a signaling complex and that its restricted localization direct s cytoskeletal reorganization only at the distal cell edge.