The partner of inscuteable/discs-large complex is required to establish planar polarity during asymmetric cell division in Drosophila

Frizzled (Fz) signaling regulates cell polarity in both vertebrates and inv ertebrates. In Drosophila, Fz orients the asymmetric division of the sensor y organ precursor cell (pl) along the antero-posterior axis of the notum. P lanar polarization involves a remodeling of the apical-basal polarity of th e pi cell. The Discs-large (Dlg) and Partner of Inscuteable (Pins) proteins accumulate at the anterior cortex, while Bazooka (Baz) relocalizes to the posterior cortex. Dig interacts directly with Pins and regulates the locali zation of Pins and Baz. Pins acts with Fz to localize Baz posteriorly, but Baz is not required to localize Pins anteriorly. Finally, Baz and the Dig/P ins complex are required for the asymmetric localization of Numb. Thus, the Dig/Pins complex responds to Fz signaling to establish planar asymmetry in the pl cell.