Planar polarity in the Drosophila eye: a multifaceted view of signaling specificity and cross-talk

Functional tissues not only polarize their epithelia in the apical-basolate ral axis, but also often display a polarity within the plane of the epithel ium, In Drosophila, all adult structures are derived from epithelia called imaginal discs and display planar polarization; the eye and the wing are pa rticularly well suited for analysis. Studies of their polarization have ide ntified several conserved genes that regulate both nuclear signaling and cy toskeletal architecture. In particular, the Frizzled (Fz) receptor has been identified as a key component of polarity establishment in all tissues. Th e Fz signaling pathway and associated events are beginning to be unraveled, shedding light on a novel Wnt/Fz signaling cascade.