Planar cell polarity, the polarization of cells within the plane of the epithelium, orthogonal to the apical‐basal axis, is essential for a growing list of developmental events, and – over the last 15 years – has evolved from a little‐studied curiosity in Drosophila to the subject of a substantial research enterprise. In that time, it has been recognized that two molecular systems are responsible for polarization of most tissues: Both the “core” Frizzled system and the “global” Fat/Dachsous/Four‐jointed system produce (...) molecular asymmetry within cells, and contribute to morphological polarization. In this review, we discuss recent findings on the molecular mechanism that links “global” directional signals with local coordinated polarity. (shrink)

The mechanisms by which cells become polarised in the plane of an epithelium have been studied in Drosophila for many years. Work has focussed on two key questions: firstly, how individual cells adopt a defined polarity, and secondly how the polarity of each cell within a tissue is aligned with its neighbours. It has been established that asymmetric subcellular localisation of a number of polarity proteins is an essential mechanism underlying polarisation of single cells. The process by which this polarity (...) is coordinated between cells however is less well understood, but is thought to involve gradients of activity of the atypical cadherins Dachsous and Fat. Subsequently, this long‐range polarity signal is refined by local cell–cell interactions involving the transmembrane molecules Frizzled, Strabismus and Flamingo. The role of these factors in coordinating polarity will be discussed. BioEssays 27:1218–1227, 2005. © 2005 Wiley Periodicals, Inc. (shrink)