title: Global identification of SMAD2 target genes reveals a role for multiple co-regulatory factors in zebrafish early gastrulas.
abstract: Nodal and Smad2/3 signals play pivotal roles in mesendoderm induction and axis determination during late blastulation and early gastrulation in vertebrate embryos. However, Smad2/3 direct target genes during those critical developmental stages have not been systematically identified. Here, through ChIP-chip assay, we show that the promoter/enhancer regions of 679 genes are bound by Smad2 in the zebrafish early gastrulas. Expression analyses confirm that a significant proportion of Smad2 targets are indeed subjected to Nodal/Smad2 regulation at the onset of gastrulation. The co-existence of DNA-binding sites of other transcription factors in the Smad2-bound regions allows the identification of well known Smad2-binding partners, such as FoxH1 and Lef1/β-catenin, as well as many previously unknown Smad2 partners, including Oct1 and Gata6, during embryogenesis. We demonstrate that Oct1 physically associates with and enhances the transcription and mesendodermal induction activity of Smad2, whereas Gata6 exerts an inhibitory role in Smad2 signaling and mesendodermal induction. Thus, our study systemically uncovers a large number of Smad2 targets in early gastrulas and suggests cooperative roles of Smad2 and other transcription factors in controlling target gene transcription, which will be valuable for studying regulatory cascades during germ layer formation and patterning of vertebrate embryos.
authors.affiliation: State Key Laboratory of Biomembrane and Membrane Biotechnology, Biology, Institute of Zoology, Chinese Academy of Sciences, 100101 Beijing, China.
authors.forename: Zhaoting
authors.initials: Z
authors.lastname: Liu
authors.forename: Xiwen
authors.initials: X
authors.lastname: Lin
authors.forename: Zhaoping
authors.initials: Z
authors.lastname: Cai
authors.forename: Zhuqiang
authors.initials: Z
authors.lastname: Zhang
authors.forename: Chunsheng
authors.initials: C
authors.lastname: Han
authors.forename: Shunji
authors.initials: S
authors.lastname: Jia
authors.forename: Anming
authors.initials: A
authors.lastname: Meng
authors.forename: Qiang
authors.initials: Q
authors.lastname: Wang
mesh_terms: D000818:Animals; D019521:Body Patterning / Q000502:physiology; D051858:Forkhead Transcription Factors / Q000235:genetics / Q000378:metabolism; D050980:GATA Transcription Factors / Q000235:genetics / Q000378:metabolism; D005775:Gastrula / Q000166:cytology / Q000378:metabolism*; D008648:Mesoderm / Q000166:cytology / Q000196:embryology*; D055457:Nodal Protein / Q000235:genetics / Q000378:metabolism; D027702:Organic Cation Transporter 1 / Q000235:genetics / Q000378:metabolism; D020218:Response Elements / Q000502:physiology*; D051899:Smad2 Protein / Q000235:genetics / Q000378:metabolism*; D051900:Smad3 Protein / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic / Q000502:physiology*; D015027:Zebrafish / Q000196:embryology* / Q000235:genetics; D029961:Zebrafish Proteins / Q000235:genetics / Q000378:metabolism*; D051176:beta Catenin / Q000235:genetics / Q000378:metabolism
chemical_list: D051858:Forkhead Transcription Factors; D050980:GATA Transcription Factors; C525956:Gata6 protein, zebrafish; C507321:LEF1 protein, zebrafish; D055457:Nodal Protein; D027702:Organic Cation Transporter 1; D051899:Smad2 Protein; D051900:Smad3 Protein; D014157:Transcription Factors; D029961:Zebrafish Proteins; D051176:beta Catenin; C491116:foxh1 protein, zebrafish; C497786:smad2 protein, zebrafish