title: XSu(H)2 is an essential factor for gene expression and morphogenesis of the Xenopus gastrula embryo.
abstract: The CSL (CBF-1, Suppressor of Hairless, Lag-1) transcriptional factor is an important mediator of Notch signal transduction. It plays a key role in cell fate determination by cell-cell interaction. CSL functions as a transcriptional repressor before the activation of Notch signaling. However, once Notch signaling is activated, CSL is converted into a transcriptional activator. It remains unclear if CSL has any function during early development before neurogenesis, while transcriptional products exist from the maternal stage. Here, we analyzed the function of Xenopus Suppressor of Hairless (XSu(H)) using morpholino antisense oligonucleotides (MO), which interfere with the translation of transcripts. In Xenopus embryos, maternal transcripts of both XSu(H)1 and XSu(H)2 were ubiquitously observed until the blastula stage and thereafter only XSu(H)1 was zygotically transcribed. Knockdown experiments with MO demonstrated that XSu(H)2 depletion caused a decrease in the expression of the Xbrachyury, MyoD and JNK1 genes. Morphological and histological examinations indicated that XSu(H)2 depletion caused abnormal gastrulation, which resulted in severe defects of the notochord and somitic mesoderm. The effect of XSu(H)2-MO was completely rescued by co-injection of XSu(H)2 mRNAs, but not by XSu(H)1 mRNAs. XESR-1, a Notch signaling target gene, inhibited Xbrachyury expression. However, expression of the XESR-1 gene was not induced by depletion of XSu(H)2. Co-injection of the dominant-negative form of XESR-1 could not rescue the suppression of Xbrachyury expression in the XSu(H)2-depleted embryo. These results suggest that XSu(H)2 is involved in mesoderm formation and the cell movement of gastrula embryos in a different manner from the XESR-1-mediated Notch signaling pathway.
authors.affiliation: Department of Bioscience, School of Science and Technology, Kwansei Gakuin University, Hyogo, Japan.
authors.forename: Motoaki
authors.initials: M
authors.lastname: Ito
authors.forename: Tomohisa
authors.initials: T
authors.lastname: Katada
authors.forename: Seiji
authors.initials: S
authors.lastname: Miyatani
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Kinoshita
mesh_terms: D000818:Animals; D005326:Fetal Proteins / Q000235:genetics; D005775:Gastrula / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D009024:Morphogenesis / Q000235:genetics*; D020320:Oligoribonucleotides, Antisense; D016372:RNA, Antisense; D023121:RNA, Messenger, Stored / Q000235:genetics / Q000378:metabolism; D051880:Receptors, Notch / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics; D015398:Signal Transduction; D020825:T-Box Domain Proteins / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation; D029867:Xenopus Proteins / Q000235:genetics / Q000378:metabolism*; D014982:Xenopus laevis / Q000196:embryology* / Q000235:genetics; D000098908:Brachyury Protein
chemical_list: D005326:Fetal Proteins; D020320:Oligoribonucleotides, Antisense; D016372:RNA, Antisense; D023121:RNA, Messenger, Stored; D051880:Receptors, Notch; D012097:Repressor Proteins; D020825:T-Box Domain Proteins; D014157:Transcription Factors; D029867:Xenopus Proteins; D000098908:Brachyury Protein; C504431:Esr1 protein, Xenopus; C517888:suppressor of hairless 2 protein, Xenopus