234|NATURE|VOL545|11MAy2017LETTERdoi:10.1038/nature22306SurrogateWntagoniststhatphenocopycanonicalWntandβ-cateninsignallingClaudiay.Janda1*,LukeT.Dang2*,Changjiangyou3,JunleiChang4,WimdeLau5,ZhendongA.Zhong6,KelleyS.yan4,OwenMarecic7,DirkSiepe1,XingnanLi4,JamesD.Moody2,BartO.Williams6,HansClevers5,JacobPiehler3,DavidBaker2,CalvinJ.Kuo4&K.ChristopherGarcia1Wntproteinsmodulatecellproliferationanddifferentiationandtheself-renewalofstemcellsbyinducingβ-catenin-dependentsignallingthroughtheWntreceptorfrizzled(FZD)andtheco-receptorsLRP5andLRP6toregulatecellfatedecisionsandthegrowthandrepairofseveraltissues1.The19mammalianWntproteinsarecross-reactivewiththe10FZDreceptors,andthishascomplicatedtheattributionofdistinctbiologicalfunctionstospecificFZDandWntsubtypeinteractions.Furthermore,Wntproteinsaremodifiedpost-translationallybypalmitoylation,whichisessentialfortheirsecretion,functionandinteractionwithFZDreceptors2–4.Asaresultoftheiracylation,Wntproteinsareveryhydrophobicandrequiredetergentsforpurification,whichpresentsmajorobstaclestothepreparationandapplicationofrecombinantWntproteins.ThishydrophobicityhashinderedthedeterminationofthemolecularmechanismsofWntsignallingactivationandthefunctionalimportanceofFZDsubtypes,andtheuseofWntproteinsastherapeuticagents.HerewedevelopsurrogateWntagonists,water-solubleFZD–LRP5/LRP6heterodimerizers,withFZD5/FZD8-specificandbroadlyFZD-reactivebindingdomains.SimilartoWNT3A,theseWntagonistselicitacharacteristicβ-cateninsignallingresponseinaFZD-selectivefashion,enhancetheosteogeniclineagecommitmentofprimarymouseandhumanmesenchymalstemcells,andsupportthegrowthofabroadrangeofprimaryhumanorganoidcultures.Inaddition,thesurrogatescanbesystemicallyexpressedandexhibitWntactivityinvivointhemouseliver,regulatingmetabolicliverzonationandpromotinghepatocyteproliferation,resultinginhepatomegaly.ThesesurrogatesdemonstratethatcanonicalWntsignallingcanbeactivatedbybi-specificligandsthatinducereceptorheterodimerization.Furthermore,theseeasilyproduce...
