title: Zygotic VegT is required for Xenopus paraxial mesoderm formation and is regulated by Nodal signaling and Eomesodermin.
abstract: The T-box gene VegT plays a crucial role during mesendoderm specification of the amphibian embryo. While the function of maternal VegT (mVegT) has been extensively investigated, little is known about the function and transcriptional regulation of zygotic VegT (zVegT). In the present study, we used comparative genomics and a knockdown experiment to demonstrate that zVegT is the orthologous gene of zebrafish Spadetail/Tbx16 and chick Tbx6L/Tbx6, and has an essential role in paraxial mesodermal formation. zVegT knockdown embryos show several defects in the patterning of trunk mesoderm, such as abnormal segmentation of somites, a reduction in muscle, and the formation of an abnormal mass of cells at the tail tip. We also identified the cis-regulatory elements of zVegT that are necessary and sufficient for mesoderm-specific expression. These cis-regulatory elements are located in two separate upstream regions of zVegT, corresponding to the first intron of mVegT. The results of in vitro binding and functional assays indicate that Forkhead box H1 (FoxH1) and Eomesodermin (Eomes) are the trans-acting factors required for zVegT expression. Our results highlight the essential role of zVegT in organization of paraxial mesoderm, and reveal that zVegT is regulated by a coherent feedforward loop of Nodal signaling via Eomes.
authors.affiliation: Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Japan.
authors.forename: Masakazu
authors.initials: M
authors.lastname: Fukuda
authors.forename: Shuji
authors.initials: S
authors.lastname: Takahashi
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Haramoto
authors.forename: Yasuko
authors.initials: Y
authors.lastname: Onuma
authors.forename: Yeon-Jin
authors.initials: YJ
authors.lastname: Kim
authors.forename: Chang-Yeol
authors.initials: CY
authors.lastname: Yeo
authors.forename: Shoichi
authors.initials: S
authors.lastname: Ishiura
authors.forename: Makoto
authors.initials: M
authors.lastname: Asashima
mesh_terms: D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D019521:Body Patterning; D002645:Chickens; D024202:Electrophoretic Mobility Shift Assay; D004625:Embryo, Nonmammalian / Q000378:metabolism; D005260:Female; D005786:Gene Expression Regulation; D007124:Immunoenzyme Techniques; D017403:In Situ Hybridization; D008648:Mesoderm / Q000502:physiology*; D008969:Molecular Sequence Data; D055457:Nodal Protein / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012045:Regulatory Sequences, Nucleic Acid; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D020825:T-Box Domain Proteins / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic; D029867:Xenopus Proteins / Q000235:genetics / Q000378:metabolism*; D014982:Xenopus laevis / Q000196:embryology; D015027:Zebrafish; D015053:Zygote / Q000166:cytology / Q000378:metabolism*
chemical_list: C103223:EOMES protein, Xenopus; D055457:Nodal Protein; D012333:RNA, Messenger; D020825:T-Box Domain Proteins; C103966:VegT protein, Xenopus; D029867:Xenopus Proteins