Multiple roles of a trimeric G protein in Drosophila cell polarization

Polarization of the cellular cytoskeleton underlies many cellular processes including axon growth cone guidance, chemotaxis and yeast mating. Planar cell polarity (PCP) is a similar phenomenon in which cells in an epithelium become uniformly polarized to generate a field of aligned structures such as the hair cells of the cochlea. In Drosophila PCP is under the hierarchical control of Frizzled (Fz) - a serpentine receptor (that also functions in the Wnt signaling pathway). Serpentine receptors are routinely transduced by trimeric G-proteins, but until recently the general consensus was that Fzs were not G-protein linked. In Drosophila a G-protein (Gα_o) has now been identified that functions in both the Wnt and PCP pathways. Here we review the cell polarity phenotypes of Gα_o mutants and discuss the evidence that it plays multifarious roles in PCP and the organization of the cytoskeleton.