Developmental Biology | |
Nodal Signaling in Xenopus Gastrulae Is Cell-Autonomous and Patterned by β-Catenin | |
Minako K. Hashimoto-Partyka1  Masahiro Yuge1  Ken W.Y. Cho1  | |
[1] Department of Developmental and Cell Biology, University of California, Irvine, California, 92697-2300 | |
关键词: Wnt; TGF-β; Xnr; cmXnr-2; β-catenin; short-range; Xenopus; | |
DOI : 10.1006/dbio.2002.0867 | |
学科分类:生物科学(综合) | |
来源: Academic Press | |
【 摘 要 】
Theclassicalthree-signalmodelofamphibianmesoderminductionandmorerecentmodificationstogetherproposethatanactivin-likesignalingactivityisuniformlydistributedacrossthevegetalhalfoftheXenopusblastulaandthatthisactivitycontributestomesoderminduction.Insupportofthis,wehavepreviouslyshownthattheactivin-responseelement(DE)ofthegoosecoidpromoterisuniformlyactivatedacrossthevegetalhalfofmidgastrula-stageembryos.Here,wefurtherexaminethenatureofthisactivitybymeasuringDEactivationbyendogenoussignalsovertime.WefindthatthespatiotemporalpatternofDEactivationismuchmoredynamicthanwaspreviouslyappreciatedandalsoconcludethatDE(6X)Lucactivityreflectsendogenousnodalsignalingintheembryo.UsingboththeDE(6X)LucconstructandendogenousXbraandXgscexpressionasread-outsfornodalactivity,andthecleavage-mutantversionofXnr2(CmXnr2)toregionallysuppressendogenousnodalactivity,wedemonstratethatnodalsignalsactcell-autonomouslyinXenopusgastrulae.Nodal-expressingcellsareunabletorescueeitherreportergeneactivationortargetgeneexpressionindistantnodal-deficientcells,suggestingthatnodalsfunctionatshortrangeinthiscontext.Finally,weshowthatDEactivationbyendogenoussignalsoccursintheabsenceofdorsalβ-catenin-mediatedsignaling,butthatthetimingofdorsalinitiationisaltered.WeconcludethatnodalsignalsinXenopusgastrulaefunctioncellautonomouslyatshortrangesandthatthespatiotemporalpatternofthissignalingalongthedorsoventralaxisisregulatedbymaternalWnt-likesignaling.
【 授权许可】
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