Zebrafish smoothened functions in ventral neural tube specification and axon tract formation

• Published in: Development (Cambridge) Vol. 128; no. 18; pp. 3497 - 3509
• Main Authors: Varga, Z M, Amores, A, Lewis, K E, Yan, Y L, Postlethwait, J H, Eisen, J S, Westerfield, M
• Format: Journal Article
• Language: English
• Published: England The Company of Biologists Limited 01-09-2001
• Subjects: Animals; Body Patterning; Danio rerio; Freshwater; hedgehog protein; Hedgehog Proteins; Molecular Sequence Data; Motor Neurons; Mutation; Nervous System - cytology; Nervous System - embryology; Phenotype; Pituitary Gland, Anterior - cytology; Pituitary Gland, Anterior - embryology; Prosencephalon - cytology; Prosencephalon - embryology; Receptors, Cell Surface - genetics; Receptors, Cell Surface - metabolism; Receptors, G-Protein-Coupled; Retina - cytology; Retina - embryology; shh gene; Signal Transduction; slow muscle omitted gene; smoothened gene; Smoothened Receptor; Sonic hedgehog protein; Spinal Cord - cytology; Spinal Cord - embryology; tiggy-winkle hedgehog gene; Trans-Activators - metabolism; Transcription Factors - genetics; Visual Pathways - cytology; Visual Pathways - embryology; Zebrafish - embryology; Zebrafish Proteins - genetics; Zinc Finger Protein Gli2
• ISSN: 0950-1991; 1477-9129
• DOI: 10.1242/dev.128.18.3497

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.