title: XNAP, a conserved ankyrin repeat-containing protein with a role in the Notch pathway during Xenopus primary neurogenesis.
abstract: The Notch signaling pathway plays an important role in many cell-fate decisions during development. Here we investigate the regulation and function of the conserved gene XNAP, which is a member of the Delta-Notch synexpression group in Xenopus. XNAP encodes a small protein with two C-terminal tandem ankyrin repeats which is expressed in the neurectoderm and in the presomitic mesoderm in a pattern that resembles that of other component of the Notch pathway. When a myc-tag form of XNAP is overexpressed in Xenopus or Hela cells, XNAP protein is detected both in the nucleus and the cytoplasm. In embryos and in animal cap assays, XNAP expression is activated, perhaps directly, by the Notch pathway and this activation appears to be Su(H) dependent. Overexpression of XNAP in embryos decreases Notch signaling, which leads to an increase in the number of primary neurons that form within the domains of the neural plate where neurogenesis normally occurs. In culture Hela cells, XNAP overexpression interferes with ICD activation of a Notch regulated reporter gene. Together, these data indicate that XNAP is a novel target of the Notch pathway that may, in a feedback loop, modulate its activity.
authors.affiliation: Université Libre de Bruxelles, IBMM, Rue des Professeurs Jeener et Brachet 12, B-6041 Gosselies, Belgium.
authors.forename: Katia
authors.initials: K
authors.lastname: Lahaye
authors.forename: Sadia
authors.initials: S
authors.lastname: Kricha
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Bellefroid
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017089:Ankyrin Repeat; D001483:Base Sequence; D004247:DNA / Q000235:genetics; D006367:HeLa Cells; D006801:Humans; D017403:In Situ Hybridization; D008565:Membrane Proteins / Q000235:genetics*; D051379:Mice; D008969:Molecular Sequence Data; D009420:Nervous System / Q000196:embryology* / Q000254:growth & development; D010641:Phenotype; D051381:Rats; D051880:Receptors, Notch; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D014162:Transfection; D029867:Xenopus Proteins / Q000235:genetics*; D014982:Xenopus laevis / Q000196:embryology* / Q000235:genetics* / Q000254:growth & development
chemical_list: D008565:Membrane Proteins; C434261:Nrarp protein, Xenopus; D051880:Receptors, Notch; D029867:Xenopus Proteins; D004247:DNA