title: Foxd3 mediates zebrafish myf5 expression during early somitogenesis.
abstract: Myf5, one of the basic helix-loop-helix transcription factors, controls muscle differentiation and is expressed in somites during early embryogenesis. However, the transcription factors bound to the cis-elements of myf5 are poorly understood. In this study, we used the yeast one-hybrid assay and found that Forkhead box d3 (Foxd3) interacted specifically with the -82/-62 cassette, a key element directing somite-specific expression of myf5. The dual-luciferase assay revealed that the expression of Foxd3 potently transactivated the myf5 promoter. Knocking down foxd3 with morpholino oligonucleotide (MO) resulted in a dramatic down-regulation of myf5 in somites and adaxial cells but not in the presomitic mesoderm. On the other hand, myod expression remained unchanged in foxd3 morphants. Foxd3 mediation of myf5 expression is stage-dependent, maintaining myf5 expression in the somites and adaxial cells during the 7- to 18-somite stage. Furthermore, in the pax3 morphant, the expression of foxd3 was down-regulated greatly and the expression of myf5 was similar to that of the foxd3 morphant. Co-injection of foxd3 mRNA and pax3-MO1 greatly restored the expression of myf5 in the somites and adaxial cells, suggesting that pax3 induces foxd3 expression, which then induces the expression of myf5. This report is the first study to show that Foxd3, a well-known regulator in neural crest development, is also involved in myf5 regulation.
authors.affiliation: Institute of Molecular and Cellular Biology, National Taiwan University, No. 1, Section 4, Roosevelt Road, Taipei 106, Taiwan.
authors.forename: Hung-Chieh
authors.initials: HC
authors.lastname: Lee
authors.forename: Hsing-Yen
authors.initials: HY
authors.lastname: Huang
authors.forename: Cheng-Yung
authors.initials: CY
authors.lastname: Lin
authors.forename: Yau-Hung
authors.initials: YH
authors.lastname: Chen
authors.forename: Huai-Jen
authors.initials: HJ
authors.lastname: Tsai
mesh_terms: D000818:Animals; D019556:COS Cells; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D051858:Forkhead Transcription Factors / Q000378:metabolism / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental; D017403:In Situ Hybridization; D008156:Luciferases / Q000378:metabolism; D008648:Mesoderm / Q000378:metabolism; D008954:Models, Biological; D051787:Myogenic Regulatory Factor 5 / Q000096:biosynthesis*; D009432:Neural Crest / Q000196:embryology; D009841:Oligonucleotides / Q000737:chemistry; D000072041:PAX3 Transcription Factor; D051761:Paired Box Transcription Factors / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D012333:RNA, Messenger / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry; D019170:Somites / Q000378:metabolism*; D013997:Time Factors; D015533:Transcriptional Activation; D020798:Two-Hybrid System Techniques; D015027:Zebrafish; D029961:Zebrafish Proteins / Q000378:metabolism / Q000502:physiology*
chemical_list: D018076:DNA, Complementary; D051858:Forkhead Transcription Factors; D051787:Myogenic Regulatory Factor 5; D009841:Oligonucleotides; D000072041:PAX3 Transcription Factor; D051761:Paired Box Transcription Factors; D012333:RNA, Messenger; D011994:Recombinant Proteins; D029961:Zebrafish Proteins; C491002:foxd3 protein, zebrafish; C489412:pax3a protein, zebrafish; D008156:Luciferases