title: Zebrafish smoothened functions in ventral neural tube specification and axon tract formation.
abstract: Sonic hedgehog (Shh) signaling patterns many vertebrate tissues. shh mutations dramatically affect mouse ventral forebrain and floor plate but produce minor defects in zebrafish. Zebrafish have two mammalian Shh orthologs, sonic hedgehog and tiggy-winkle hedgehog, and another gene, echidna hedgehog, that could have overlapping functions. To examine the role of Hedgehog signaling in zebrafish, we have characterized slow muscle omitted (smu) mutants. We show that smu encodes a zebrafish ortholog of Smoothened that transduces Hedgehog signals. Zebrafish smoothened is expressed maternally and zygotically and supports specification of motoneurons, pituitary cells and ventral forebrain. We propose that smoothened is required for induction of lateral floor plate and a subpopulation of hypothalamic cells and for maintenance of medial floor plate and hypothalamic cells.
authors.affiliation: Institute of Neuroscience, 1254 University of Oregon, Eugene, OR 97403, USA. varga@uni-freiburg.de
authors.forename: Z M
authors.initials: ZM
authors.lastname: Varga
authors.forename: A
authors.initials: A
authors.lastname: Amores
authors.forename: K E
authors.initials: KE
authors.lastname: Lewis
authors.forename: Y L
authors.initials: YL
authors.lastname: Yan
authors.forename: J H
authors.initials: JH
authors.lastname: Postlethwait
authors.forename: J S
authors.initials: JS
authors.lastname: Eisen
authors.forename: M
authors.initials: M
authors.lastname: Westerfield
mesh_terms: D000818:Animals; D019521:Body Patterning; D053823:Hedgehog Proteins; D008969:Molecular Sequence Data; D009046:Motor Neurons; D009154:Mutation; D009420:Nervous System / Q000166:cytology / Q000196:embryology*; D010641:Phenotype; D010903:Pituitary Gland, Anterior / Q000166:cytology / Q000196:embryology; D016548:Prosencephalon / Q000166:cytology / Q000196:embryology; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism*; D043562:Receptors, G-Protein-Coupled; D012160:Retina / Q000166:cytology / Q000196:embryology; D015398:Signal Transduction; D000072086:Smoothened Receptor; D013116:Spinal Cord / Q000166:cytology / Q000196:embryology; D015534:Trans-Activators / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics; D014795:Visual Pathways / Q000166:cytology / Q000196:embryology; D015027:Zebrafish / Q000196:embryology*; D029961:Zebrafish Proteins / Q000235:genetics; D000075746:Zinc Finger Protein Gli2
chemical_list: D053823:Hedgehog Proteins; D011956:Receptors, Cell Surface; D043562:Receptors, G-Protein-Coupled; C491022:Smo protein, mouse; D000072086:Smoothened Receptor; D015534:Trans-Activators; D014157:Transcription Factors; D029961:Zebrafish Proteins; D000075746:Zinc Finger Protein Gli2; C118355:gli2a protein, zebrafish; C509240:shhb protein, zebrafish; C491021:smo protein, zebrafish