title: Transcriptional regulatory networks in epiblast cells and during anterior neural plate development as modeled in epiblast stem cells.
abstract: Somatic development initiates from the epiblast in post-implantation mammalian embryos. Recent establishment of epiblast stem cell (EpiSC) lines has opened up new avenues of investigation of the mechanisms that regulate the epiblast state and initiate lineage-specific somatic development. Here, we investigated the role of cell-intrinsic core transcriptional regulation in the epiblast and during derivation of the anterior neural plate (ANP) using a mouse EpiSC model. Cells that developed from EpiSCs in one day in the absence of extrinsic signals were found to represent the ANP of ~E7.5 embryos. We focused on transcription factors that are uniformly expressed in the E6.5 epiblast but in a localized fashion within or external to the ANP at E7.5, as these are likely to regulate the epiblast state and ANP development depending on their balance. Analyses of the effects of knockdown and overexpression of these factors in EpiSCs on the levels of downstream transcription factors identified the following regulatory functions: cross-regulation among Zic, Otx2, Sox2 and Pou factors stabilizes the epiblastic state; Zic, Otx2 and Pou factors in combination repress mesodermal development; Zic and Sox2 factors repress endodermal development; and Otx2 represses posterior neural plate development. All of these factors variably activate genes responsible for neural plate development. The direct interaction of these factors with enhancers of Otx2, Hesx1 and Sox2 genes was demonstrated. Thus, a combination of regulatory processes that suppresses non-ANP lineages and promotes neural plate development determines the ANP.
authors.affiliation: Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871,  Japan.
authors.forename: Makiko
authors.initials: M
authors.lastname: Iwafuchi-Doi
authors.forename: Kazunari
authors.initials: K
authors.lastname: Matsuda
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Murakami
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Niwa
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Tesar
authors.forename: Jun
authors.initials: J
authors.lastname: Aruga
authors.forename: Isao
authors.initials: I
authors.lastname: Matsuo
authors.forename: Hisato
authors.initials: H
authors.lastname: Kondoh
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D005260:Female; D053263:Gene Regulatory Networks / Q000235:genetics / Q000502:physiology*; D005855:Germ Layers / Q000166:cytology*; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D054258:Neural Plate / Q000166:cytology / Q000196:embryology* / Q000378:metabolism*; D051857:Otx Transcription Factors / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D055748:SOXB1 Transcription Factors / Q000235:genetics / Q000378:metabolism; D013234:Stem Cells / Q000166:cytology* / Q000378:metabolism*
chemical_list: C489733:Hesx1 protein, mouse; D018398:Homeodomain Proteins; D051857:Otx Transcription Factors; C497660:Otx2 protein, mouse; D012097:Repressor Proteins; D055748:SOXB1 Transcription Factors; C527783:Sox2 protein, mouse