Region-specific activity of the Diego protein in Planar Cell Polarity. Simon Collier¹, Hugh Cahill². 1) Dept Biological Sci, Marshall Univ, Huntington, WV; 2) School of Medicine, Marshall Univ, Huntington, WV.

   The ankyrin-repeat protein Diego (Dgo) is a regulator of Frizzled (Fz) Planar Cell Polarity (PCP) signaling in Drosophila. Previous studies have shown that Dgo is required for normal ommatidial polarity in the eye, and hair polarity on the wing. In wing cells, Dgo is proposed to bind the Dishevelled (Dsh) protein at the distal end of the cell, prior to the distal initiation of a polarized cell hair. We have studied the effects of loss or gain of Dgo activity in a number of adult tissues. In the wing, both loss and gain of Dgo activity result in disruption of normal hair polarity, implying that there is a dose-specific requirement for Dgo in normal wing PCP. In contrast, neither loss nor gain of Dgo activity in the leg disrupt hair, bristle, or tarsal joint polarity, suggesting that the PCP specification in the leg is not sensitive to Dgo activity. In the thorax and abdomen, both loss and gain of Dgo activity affect hair and bristle polarity in the posterior compartment of each segment, whereas the anterior compartment remains unaffected. This leads to the surprising conclusion that different regions of the same tissue may have differing sensitivity to Dgo activity. We will present a model that proposes two distinct, region-specific, outcomes of Fz PCP signaling, only one of which is sensitive to Dgo activity.