Fat2 controls planar microtubule alignment in the Drosophila follicle epithelium. Christian Dahmann, Ivana Viktorinova. Institute of Genetics, Dresden University of Technology, Dresden, Germany.

   The polarization of cells in the plane of a tissue is an important characteristic of many epithelia, yet how this planar polarity is established is not fully understood. The Drosophila follicle epithelium has emerged as a useful system to study the mechanisms by which planar polarity is established. Planar polarity in the follicle epithelium is apparent by the planar polarized organization of actin filaments and extracellular matrix components. Establishment of proper planar polarity requires the atypical cadherin Fat2. Fat2 protein localization is planar polarized in follicle cells. Here we show that microtubules are planar polarized in the follicle epithelium. Microtubules are preferentially oriented perpendicular to the anteroposterior axis of the egg chamber. Microtubule orientation is randomized in fat2 mutants. Moreover, microtubule destabilization results in a loss of planar polarization of the Fat2 protein. Our results suggest a feedback loop between Fat2 and microtubules in establishing planar polarity in the follicle epithelium.