title: GSK3beta positively regulates Hedgehog signaling through Sufu in mammalian cells.
abstract: Hedgehog signaling plays important roles in embryonic patterning of multicellular organisms. This pathway is ultimately transmitted by the zinc-finger transcriptional factor Gli, of which activity is suppressed by Sufu, a negative regulator of this signaling. To clarify this regulation to more detail, we screened for Sufu-binding proteins. We identified GSK3beta as a specific binding partner of Sufu by mass spectrometric analysis. GSK3beta bound to Sufu both in vitro and in vivo. Down-regulation of GSK3beta expression by RNAi in Hedgehog-responsive cells attenuated Hedgehog signaling, suggesting that GSK3beta functions as a positive regulator of Hedgehog signaling. In addition, an in vitro kinase assay showed that GSK3beta phosphorylates Sufu and phosphorylation-mimicking mutant of Sufu showed significantly decreased ability to bind Gli1 and could not suppress the Gli-mediated expression of a reporter gene efficiently. These results strongly suggest that GSK3beta phosphorylates Sufu to positively regulate Hedgehog signaling in mammalian cells.
authors.affiliation: Division of Cancer Genomics, Institute of Medical Science, University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan. takenaka@ims.u-tokyo.ac.jp
authors.forename: Kei
authors.initials: K
authors.lastname: Takenaka
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Kise
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Miki
mesh_terms: D000818:Animals; D002460:Cell Line; D005347:Fibroblasts / Q000378:metabolism*; D053823:Hedgehog Proteins / Q000378:metabolism*; D051379:Mice; D012097:Repressor Proteins / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*
chemical_list: C514503:GSKIP protein, human; D053823:Hedgehog Proteins; D012097:Repressor Proteins; C490763:Sufu protein, mouse