title: Essential requirement for RING finger E3 ubiquitin ligase Hakai in early embryonic development of Drosophila.
abstract: Hakai is a RING finger type E3 ubiquitin ligase that is highly conserved in metazoans. Mammalian Hakai was shown to bind and ubiquitinate the intracellular domain of E-cadherin, and this activity is implicated in down-regulation of E-cadherin during v-Src-induced cellular transformation. To evaluate this model in vivo, we studied the function of the Drosophila homologue of Hakai. In cultured S2 cells, Drosophila Hakai and E-cadherin (Shotgun) formed a complex in a way distinct from the interaction described for mammalian counterparts. Hakai null mutants died during larval stages but this lethality could be offset by a HA-tagged Hakai construct. While zygotic Hakai function was dispensable for cell proliferation and differentiation in the wing disc epithelium, maternal Hakai mutants showed a variety of defects in epithelial integrity, including stochastic loss of E-cadherin expression and reduction of aPKC; defects in cell specification and cell migration were also observed. No increase of E-cadherin, however, was observed. Regulation of multiple target proteins under control of Hakai is, therefore, essential for early embryonic morphogenesis in Drosophila.
authors.affiliation: Riken Center for Developmental Biology, 2-2-3 Minatojima-minamimachi, Chuo-ku, Kobe 650-0047, Japan.
authors.forename: Masako
authors.initials: M
authors.lastname: Kaido
authors.forename: Housei
authors.initials: H
authors.lastname: Wada
authors.forename: Masayo
authors.initials: M
authors.lastname: Shindo
authors.forename: Shigeo
authors.initials: S
authors.lastname: Hayashi
mesh_terms: D000818:Animals; D015820:Cadherins / Q000378:metabolism; D002478:Cells, Cultured; D004330:Drosophila / Q000196:embryology* / Q000201:enzymology / Q000235:genetics; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism; D004625:Embryo, Nonmammalian / Q000378:metabolism; D047108:Embryonic Development / Q000235:genetics; D018507:Gene Expression Regulation, Developmental; D009154:Mutation; D054829:RING Finger Domains / Q000235:genetics*; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism
chemical_list: D015820:Cadherins; D029721:Drosophila Proteins; D044767:Ubiquitin-Protein Ligases