Zygotic Wnt Activity Is Required for Brachyury Expression in the Early Xenopus laevis Embryo

Developmental Biology

Alin Vonica¹  Barry M. Gumbiner¹ 

[1] Cellular Biochemistry and Biophysics Program, Memorial Sloan–Kettering Cancer Center, New York, New York, 10021

关键词: Wnt;    Xbra;    Tcf;    mesoderm;    induction;    repression;    eFGF;    activin;    zygotic;    VegT;   

DOI  :  10.1006/dbio.2002.0786

学科分类：生物科学（综合）

来源: Academic Press

【 摘 要 】

Thecanonical,β-catenin-dependentWntpathwayisacrucialplayerintheearlyeventsofXenopusdevelopment.Dorsalaxisformationandmesodermpatterningareacceptedeffectsofthispathway,buttheregulationofexpressionofgenesinvolvedinmesodermspecificationisnot.ThisconclusionisbasedlargelyontheinabilityoftheWntpathwaytoinducemesoderminanimalcapexplants.UsinginjectionsofinhibitorsofcanonicalWntsignaling,wedemonstratethatexpressionofthegeneralmesodermalmarkerBrachyury(Xbra)requiresazygotic,ligand-dependentWntactivitythroughoutthemarginalzone.AnalysisoftheXbrapromoterrevealsthatputativeTCF-bindingsitesmediateWntactivation,thefirstsitesinthiswell-studiedpromotertowhichanactivationrolecanbeascribed.However,establishedmesoderminducerslikeeFGFandactivincanbypasstheWntrequirementforXbraexpression.Anothermesodermpromotingfactor,VegT,activatesXbrainaWnt-dependentmanner.Wealsoshowthattheactivin/nodalsignalingisnecessaryforectopicXbrainductionbytheWntpathway,butnotbyVegT.OurdatasignificantlychangetheunderstandingofBrachyuryregulationinXenopus,implyingtheexistenceofanunknownzygoticWntligandinSpemann'sorganizer.SinceBrachyuryisconsideredtohaveamajorroleinmesodermformation,itispossiblethatWntsmightplayaroleinmesodermspecification,inadditiontopatterning.

【 授权许可】

Unknown