Drosophila Rho-associated kinase (Drok) links frizzled-mediated planar cell polarity signaling to the actin cytoskeleton

Frizzled (Fz) and Dishevelled (Dsh) are components of an evolutionarily con served signaling pathway that regulates planar cell polarity. How this sign aling pathway directs asymmetric cytoskeletal reorganization and polarized cell morphology remains unknown. Here, we show that Drosophila Rho-associat ed kinase (Drok) works downstream of Fz/Dsh to mediate a branch of the plan ar polarity pathway involved in ommatidial rotation in the eye and in restr icting actin bundle formation to a single site in developing wing cells. Th e primary output of Drok signaling is regulating the phosphorylation of non muscle myosin regulatory light chain, and hence the activity of myosin II. Drosophila myosin VIIA, the homolog of the human Usher Syndrome 1B gene, al so functions in conjunction with this newly defined portion of the Fz/Dsh s ignaling pathway to regulate the actin cytoskeleton.