title: Maternal Tgif1 regulates nodal gene expression in Xenopus.
abstract: In Xenopus, the maternal transcription factor VegT is necessary and sufficient to initiate the expression of nodal-related genes, which are central to many aspects of early development. However, little is known about regulation of VegT activity. Using maternal loss-of-function experiments, we show that the maternal homeoprotein, Tgif1, antagonizes VegT and plays a central role in anteroposterior patterning by negatively regulating a subset of nodal-related genes. Depletion of Tgif1 causes the anteriorization of embryos and the up-regulation of nodal paralogues nr5 and nr6. Furthermore, Tgif1 inhibits activation of nr5 by VegT in a manner that requires a C-terminal Sin3 corepressor-interacting domain. Tgif1 has been implicated in the transcriptional corepression of transforming growth factor-beta (TGFbeta) and retinoid signaling. However, we show that Tgif1 does not inhibit these pathways in early development. These results identify an essential role for Tgif1 in the control of nodal expression and provide insight into Tgif1 function and mechanisms controlling VegT activity.
authors.affiliation: University of Iowa, Department of Biology, Iowa City, Iowa 52246-1324, USA.
authors.forename: Tyler C
authors.initials: TC
authors.lastname: Kerr
authors.forename: Tawny N
authors.initials: TN
authors.lastname: Cuykendall
authors.forename: Laura C
authors.initials: LC
authors.lastname: Luettjohann
authors.forename: Douglas W
authors.initials: DW
authors.lastname: Houston
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D030801:Animals, Genetically Modified; D004625:Embryo, Nonmammalian / Q000196:embryology / Q000378:metabolism; D005260:Female; D017353:Gene Deletion; D018507:Gene Expression Regulation, Developmental / Q000235:genetics*; D018398:Homeodomain Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D009035:Mothers; D055457:Nodal Protein / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D012176:Retinoids / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D051899:Smad2 Protein / Q000235:genetics / Q000378:metabolism; D029867:Xenopus Proteins / Q000737:chemistry / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D014982:Xenopus laevis / Q000196:embryology* / Q000235:genetics / Q000378:metabolism*
chemical_list: D018398:Homeodomain Proteins; D055457:Nodal Protein; D012333:RNA, Messenger; D012176:Retinoids; D051899:Smad2 Protein; C497785:Smad2 protein, Xenopus; C533028:Tgif1 protein, Xenopus; D029867:Xenopus Proteins