title: Hes6 is required for MyoD induction during gastrulation.
abstract: The specification of mesoderm into distinct compartments sharing the same lineage restricted fates is a crucial step occurring during gastrulation, and is regulated by morphogenic signals such as the FGF/MAPK and activin pathways. One target of these pathways is the transcription factor XmyoD, which in early gastrulation is expressed in the lateral and ventral mesoderm. Expression of the hairy/enhancer of split transcription factor hes6, is also restricted to lateral and ventral mesoderm in gastrula stage Xenopus embryos, leading us to investigate whether it has a role in XmyoD regulation. In vivo, Xhes6 is required for FGF-mediated induction of XmyoD expression but not for induction of early mesoderm. The WRPW domain of Xhes6, which binds Groucho family transcriptional co-regulators, is essential for the XmyoD-inducing activity of Xhes6. Two Groucho proteins, Xgrg2 and Xgrg4, are expressed in lateral and ventral mesoderm, and inhibit expression of XmyoD. Xhes6 binds both Xgrg2 and Xgrg4 and relieves their inhibition of XmyoD expression. We also find that lowering Xhes6 expression levels blocks normal myogenic differentiation at tail bud stage. We conclude that Xhes6 is essential for XmyoD induction and acts by relieving Groucho-mediated repression of gene expression.
authors.affiliation: MRC Cancer Cell Unit, Hutchison-MRC Research Centre, Addenbrooke's Hospital, Cambridge CB2 0XZ, UK.
authors.forename: Kasumi
authors.initials: K
authors.lastname: Murai
authors.forename: Ann E
authors.initials: AE
authors.lastname: Vernon
authors.forename: Anna
authors.initials: A
authors.lastname: Philpott
authors.forename: Phil
authors.initials: P
authors.lastname: Jones
mesh_terms: D028341:Activins / Q000378:metabolism; D000818:Animals; D019521:Body Patterning / Q000187:drug effects; D056970:Co-Repressor Proteins; D004268:DNA-Binding Proteins / Q000378:metabolism; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D005346:Fibroblast Growth Factors / Q000494:pharmacology; D054262:Gastrulation / Q000187:drug effects; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D020935:MAP Kinase Signaling System / Q000187:drug effects; D008648:Mesoderm / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D024510:Muscle Development / Q000187:drug effects; D017570:MyoD Protein / Q000235:genetics*; D055457:Nodal Protein; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D011485:Protein Binding / Q000187:drug effects; D012097:Repressor Proteins / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D051899:Smad2 Protein / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000378:metabolism; D029867:Xenopus Proteins / Q000235:genetics / Q000378:metabolism*; D014982:Xenopus laevis / Q000196:embryology* / Q000378:metabolism
chemical_list: D056970:Co-Repressor Proteins; D004268:DNA-Binding Proteins; D017570:MyoD Protein; C057363:MyoD1 myogenic differentiation protein; D055457:Nodal Protein; D016376:Oligonucleotides, Antisense; D012097:Repressor Proteins; D051899:Smad2 Protein; C523700:TLE4 protein, Xenopus; D016212:Transforming Growth Factor beta; D029867:Xenopus Proteins; D028341:Activins; D005346:Fibroblast Growth Factors