The winged helix transcription factor Foxc1a is essential for somitogenesis in zebrafish

• Published in: Genes & development Vol. 15; no. 18; pp. 2483 - 2493
• Main Authors: Topczewska, J M, Topczewski, J, Shostak, A, Kume, T, Solnica-Krezel, L, Hogan, B L
• Format: Journal Article
• Language: English
• Published: United States Cold Spring Harbor Laboratory Press 15.09.2001
• Subjects: Amino Acid Sequence; Animals; Base Sequence; COS Cells; Danio rerio; deltaC gene; deltaD gene; DNA Primers; Embryonic Development; ephA4 gene; ephrinB2 gene; Forkhead Transcription Factors; Foxc1 gene; Foxc1a gene; Foxc1a protein; foxc1b gene; Freshwater; mesp-b gene; Molecular Sequence Data; notch5 gene; notch6 gene; paraxis gene; Phenotype; Research Paper; Somites; somitogenesis; Transcription Factors - chemistry; Transcription Factors - genetics; Transcription Factors - physiology; Zebrafish - embryology; Zebrafish Proteins
• ISSN: 0890-9369; 1549-5477
• DOI: 10.1101/gad.907401

Previous studies identified zebrafish foxc1a and foxc1b as homologs of the mouse forkhead gene, Foxc1. Both genes are transcribed in the unsegmented presomitic mesoderm (PSM), newly formed somites, adaxial cells, and head mesoderm. Here, we show that inhibiting synthesis of Foxc1a (but not Foxc1b) protein with two different morpholino antisense oligonucleotides blocks formation of morphological somites, segment boundaries, and segmented expression of genes normally transcribed in anterior and posterior somites and expression of paraxis implicated in somite epithelialization. Patterning of the anterior PSM is also affected, as judged by the absence of mesp-b, ephrinB2, and ephA4 expression, and the down-regulation of notch5 and notch6. In contrast, the expression of other genes, including mesp-a and papc, in the anterior of somite primordia, and the oscillating expression of deltaC and deltaD in the PSM appear normal. Nevertheless, this expression is apparently insufficient for the maturation of the presumptive somites to proceed to the stage when boundary formation occurs or for the maintenance of anterior/posterior patterning. Mouse embryos that are compound null mutants for Foxc1 and the closely related Foxc2 have no morphological somites and show abnormal expression of Notch signaling pathway genes in the anterior PSM. Therefore, zebrafish foxc1a plays an essential and conserved role in somite formation, regulating both the expression of paraxis and the A/P patterning of somite primordia.