title: IKK epsilon regulates F actin assembly and interacts with Drosophila IAP1 in cellular morphogenesis.
abstract: Differentiated cells assume complex shapes through polarized cell migration and growth. These processes require the restricted organization of the actin cytoskeleton at limited subcellular regions. IKK epsilon is a member of the IkappaB kinase family, and its developmental role has not been clear. Drosophila IKK epsilon was localized to the ruffling membrane of cultured cells and was required for F actin turnover at the cell margin. In IKK epsilon mutants, tracheal terminal cells, bristles, and arista laterals, which require accurate F actin assembly for their polarized elongation, all exhibited aberrantly branched morphology. These phenotypes were sensitive to a change in the dosage of Drosophila inhibitor of apoptosis protein 1 (DIAP1) and the caspase DRONC without apparent change in cell viability. In contrast to this, hyperactivation of IKK epsilon destabilized F actin-based structures. Expression of a dominant-negative form of IKK epsilon increased the amount of DIAP1. The results suggest that at the physiological level, IKK epsilon acts as a negative regulator of F actin assembly and maintains the fidelity of polarized elongation during cell morphogenesis. This IKK epsilon function involves the negative regulation of the nonapoptotic activity of DIAP1.
authors.affiliation: Riken Center for Developmental Biology, 2-2-3 Minatojima-minamimachi, Chuo-ku, Kobe 650-0047, Japan.
authors.forename: Kenzi
authors.initials: K
authors.lastname: Oshima
authors.forename: Michiko
authors.initials: M
authors.lastname: Takeda
authors.forename: Erina
authors.initials: E
authors.lastname: Kuranaga
authors.forename: Ryu
authors.initials: R
authors.lastname: Ueda
authors.forename: Toshiro
authors.initials: T
authors.lastname: Aigaki
authors.forename: Masayuki
authors.initials: M
authors.lastname: Miura
authors.forename: Shigeo
authors.initials: S
authors.lastname: Hayashi
mesh_terms: D000199:Actins / Q000378:metabolism*; D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D015153:Blotting, Western; D002454:Cell Differentiation / Q000502:physiology*; D004330:Drosophila / Q000502:physiology*; D029721:Drosophila Proteins / Q000378:metabolism*; D005820:Genetic Testing; D006651:Histocytochemistry; D051550:I-kappa B Kinase / Q000378:metabolism*; D051034:Inhibitor of Apoptosis Proteins / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D009024:Morphogenesis / Q000502:physiology*; D014132:Trachea / Q000166:cytology / Q000254:growth & development
chemical_list: D000199:Actins; C111891:DIAP1 protein, Drosophila; D029721:Drosophila Proteins; D051034:Inhibitor of Apoptosis Proteins; D051550:I-kappa B Kinase