title: Involvement of a proline-rich motif and RING-H2 finger of Deltex in the regulation of Notch signaling.
abstract: The Notch pathway is an evolutionarily conserved signaling mechanism that is essential for cell-cell interactions. The Drosophila deltex gene regulates Notch signaling in a positive manner, and its gene product physically interacts with the intracellular domain of Notch through its N-terminal domain. Deltex has two other domains that are presumably involved in protein-protein interactions: a proline-rich motif that binds to SH3-domains, and a RING-H2 finger motif. Using an overexpression assay, we have analyzed the functional involvement of these Deltex domains in Notch signaling. The N-terminal domain of Deltex that binds to the CDC10/Ankyrin repeats of the Notch intracellular domain was indispensable for the function of Deltex. A mutant form of Deltex that lacked the proline-rich motif behaved as a dominant-negative form. This dominant-negative Deltex inhibited Notch signaling upstream of an activated, nuclear form of Notch and downstream of full-length Notch, suggesting the dominant-negative Deltex might prevent the activation of the Notch receptor. We found that Deltex formed a homo-multimer, and mutations in the RING-H2 finger domain abolished this oligomerization. The same mutations in the RING-H2 finger motif of Deltex disrupted the function of Deltex in vivo. However, when the same mutant was fused to a heterologous dimerization domain (Glutathione-S-Transferase), the chimeric protein had normal Deltex activity. Therefore, oligomerization mediated by the RING-H2 finger motif is an integral step in the signaling function of Deltex.
authors.affiliation: Department of Biological Science and Technology, Science University of Tokyo, 2641 Yamazaki, Noda, Chiba 278-8510, Japan. matsuno@rs.noda.sut.ac.jp
authors.forename: Kenji
authors.initials: K
authors.lastname: Matsuno
authors.forename: Mikiko
authors.initials: M
authors.lastname: Ito
authors.forename: Kazuya
authors.initials: K
authors.lastname: Hori
authors.forename: Fumiyasu
authors.initials: F
authors.lastname: Miyashita
authors.forename: Satoshi
authors.initials: S
authors.lastname: Suzuki
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Kishi
authors.forename: Spyros
authors.initials: S
authors.lastname: Artavanis-Tsakonas
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Okano
mesh_terms: D020816:Amino Acid Motifs; D000818:Animals; D030801:Animals, Genetically Modified; D004330:Drosophila / Q000235:genetics / Q000254:growth & development; D029721:Drosophila Proteins; D019476:Insect Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D008565:Membrane Proteins / Q000378:metabolism*; D016296:Mutagenesis; D011392:Proline; D051880:Receptors, Notch; D015398:Signal Transduction
chemical_list: C086679:DX protein, Drosophila; D029721:Drosophila Proteins; D019476:Insect Proteins; D008565:Membrane Proteins; C497759:N protein, Drosophila; D051880:Receptors, Notch; D011392:Proline