title: Epithelial cell shape is regulated by Lulu proteins via myosin-II.
abstract: Cell-shape change in epithelial structures is fundamental to animal morphogenesis. Recent studies identified myosin-II as the major generator of driving forces for cell-shape changes during morphogenesis. Lulu (Epb41l5) is a major regulator of morphogenesis, although the downstream molecular and cellular mechanisms remain obscure in mammals. In Drosophila and zebrafish, Lulu proteins were reported to negatively regulate Crumbs, an apical domain regulator, thus regulating morphogenesis. In this study, we show that mammalian Lulu activates myosin-II, thus regulating epithelial cell shape. In our experiments, Lulu expression in epithelial cells resulted in apical constriction and lateral elongation in the cells, accompanied by upregulation of myosin-II. The inhibition of myosin-II activity almost completely blocked this Lulu-driven cell-shape change. We further found that Rock participates in the myosin-II activation. Additionally, RNAi-mediated depletion of Lulu in epithelial cells resulted in disorganization of myosin-II and a concomitant loss of proper lateral domain organization in the cells. From these results, we propose that Lulu regulates epithelial cell shape by controlling myosin-II activity.
authors.affiliation: Global COE Program for Integrative Membrane Biology, Graduate School of Medicine, Kobe University, Chuo-ku, Kobe 650-0017, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Nakajima
authors.forename: Takuji
authors.initials: T
authors.lastname: Tanoue
mesh_terms: D000199:Actins / Q000502:physiology; D000818:Animals; D001483:Base Sequence; D018938:Caco-2 Cells; D002460:Cell Line; D016764:Cell Polarity / Q000502:physiology; D048430:Cell Shape / Q000502:physiology*; D004285:Dogs; D004847:Epithelial Cells / Q000166:cytology* / Q000502:physiology*; D006801:Humans; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D051379:Mice; D008954:Models, Biological; D024462:Myosin Type II / Q000502:physiology*; D009219:Myosin-Light-Chain Kinase / Q000502:physiology; D017434:Protein Structure, Tertiary; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017384:Sequence Deletion; D054460:rho-Associated Kinases / Q000502:physiology
chemical_list: D000199:Actins; D008565:Membrane Proteins; D034741:RNA, Small Interfering; D011993:Recombinant Fusion Proteins; D054460:rho-Associated Kinases; D009219:Myosin-Light-Chain Kinase; D024462:Myosin Type II