Evolution of extracellular Dpp modulators in insects: The roles of tolloid and twisted-gastrulation in dorsoventral patterning of the Tribolium embryo

摘要

TheformationoftheBMPgradientwhichpatternstheDVaxisinfliesandvertebratesrequiresseveralextracellularmodulatorsliketheinhibitoryproteinSog/Chordin,themetalloproteaseTolloid(Tld),whichcleavesSog/Chordin,andtheCRdomainproteinTwistedgastrulation(Tsg).Whilefliesandvertebrateshaveonlyoneemsog/em/emchordin/emgenetheypossessseveralparaloguesofemtld/emandemtsg/em.Asimplerandprobablyancestralsituationisobservedintheshort-germbeetleemTriboliumcastaneum/em(emTc/em),whichpossessesonlyoneemtld/emandoneemtsg/emgene.HereweshowthatinemT.castaneumtld/emisrequiredforearlyBMPsignallingexceptintheheadregionandemTc-tld/emfunctionis,asexpected,dependentonemTc-sog/em.Incontrast,emTc-tsg/emisrequiredforallaspectsofearlyBMPsignallingandactsinaemTc-sog/em-independentmanner.ForcomparisonwithemDrosophilamelanogaster/emweconstructedflyembryoslackingallearlyTsgactivity(tsg;;srwdoublemutants)andshowthattheystillestablishaBMPsignallinggradient.Thus,ourresultssuggestthattheroleofTsgproteinsforBMPgradientformationhaschangedduringinsectevolution./p/div