title: Developmental enhancers are marked independently of zygotic Nodal signals in Xenopus.
abstract: To determine the hierarchy of transcriptional regulation within the in vivo vertebrate embryo, we examined whether developmental enhancers were influenced by Nodal signaling during early embryogenesis in Xenopus tropicalis. We find that developmental enhancers, defined by the active enhancer chromatin marks H3K4me1 and H3K27ac, are established as early as blastula stage and that Smad2/3 only strongly associates with these regions at gastrula stages. Significantly, when we perturb Nodal signaling using the drug SB431542, most enhancers remain marked, including at genes known to be sensitive to Nodal signaling. Overall, as enhancers are in an active conformation prior to Nodal signaling and are established independently of Nodal signaling, we suggest that many developmental enhancers are marked maternally, prior to exposure to extrinsic signals.
authors.affiliation: Department of Genetics, Stanford University, Stanford, CA 94305, USA.
authors.forename: Rakhi
authors.initials: R
authors.lastname: Gupta
authors.affiliation: Department of Genetics, Stanford University, Stanford, CA 94305, USA.
authors.forename: Andrea
authors.initials: A
authors.lastname: Wills
authors.affiliation: Department of Genetics, Stanford University, Stanford, CA 94305, USA.
authors.forename: Duygu
authors.initials: D
authors.lastname: Ucar
authors.affiliation: Department of Genetics, Stanford University, Stanford, CA 94305, USA.|Department of Obstetrics and Gynecology, Stanford University, Stanford, CA 94305, USA.
authors.forename: Julie
authors.initials: J
authors.lastname: Baker
mesh_terms: D000215:Acylation; D000818:Animals; D001483:Base Sequence; D001549:Benzamides / Q000494:pharmacology; D036703:Blastula / Q000196:embryology / Q000378:metabolism; D004149:Dioxoles / Q000494:pharmacology; D004742:Enhancer Elements, Genetic / Q000235:genetics*; D005775:Gastrula / Q000196:embryology / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D006657:Histones / Q000378:metabolism; D008239:Lysine / Q000378:metabolism; D008745:Methylation; D008969:Molecular Sequence Data; D055457:Nodal Protein / Q000235:genetics*; D020411:Oligonucleotide Array Sequence Analysis; D012689:Sequence Homology, Nucleic Acid; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics*; D051899:Smad2 Protein / Q000378:metabolism; D051900:Smad3 Protein / Q000378:metabolism; D013997:Time Factors; D014981:Xenopus / Q000196:embryology / Q000235:genetics*; D029867:Xenopus Proteins / Q000235:genetics* / Q000378:metabolism; D015053:Zygote / Q000378:metabolism
chemical_list: C459179:4-(5-benzo(1,3)dioxol-5-yl-4-pyridin-2-yl-1H-imidazol-2-yl)benzamide; D001549:Benzamides; D004149:Dioxoles; D006657:Histones; D055457:Nodal Protein; D051899:Smad2 Protein; C497785:Smad2 protein, Xenopus; D051900:Smad3 Protein; D029867:Xenopus Proteins; D008239:Lysine
keywords: Enhancer; Gastrulation; H3K27ac; H3K27me3; H3K4me1; H3K4me3; Nodal; Smad2; Xenopus tropicalis