Non-additive interactions involving two distinct elements mediate sloppy-paired regulation by pair-rule transcription factors

摘要

Therelativelysimplecombinatorialrulesresponsibleforestablishingtheinitialmetamericexpressionofemsloppy-paired-1/em(emslp1/em)intheDrosophilablastodermembryomakethissystemanattractivemodelforinvestigatingthemechanismofregulationbypair-ruletranscriptionfactors.Thisinvestigationofemslp1/emcis-regulatoryarchitectureidentifiestwodistinctelements,aproximalearlystripeelement(PESE)andadistalearlystripeelement(DESE)locatedfromminus;#xA0;3.1#xA0;kbtominus;#xA0;2.5#xA0;kbandfromminus;#xA0;8.1#xA0;kbtominus;#xA0;7.1#xA0;kbupstreamoftheemslp1/empromoter,respectively,thatmediatethisearlyregulation.Theproximalelementexpressesonlyeven-numberedstripesandmediatesrepressionbyEven-skipped(Eve)aswellasbythecombinationofRuntandFushi-tarazu(Ftz).A272basepairsub-elementofPESEretainsanEve-dependentrepression,butisexpressedthroughouttheeven-numberedparasegmentsduetothelossofrepressionbyRuntandFtz.Incontrast,thedistalelementexpressesbothoddandeven-numberedstripesandalsodrivesinappropriateexpressionintheanteriorhalfoftheodd-numberedparasegmentsduetoaninabilitytorespondtorepressionbyEve.Importantly,acompositereportergenecontainingbothearlystripeelementsrecapitulatespair-rulegene-dependentregulationinamannerbeyondwhatisexpectedfromcombiningtheirindividualpatterns.Theseresultsindicatethatinteractionsinvolvingdistinctcis-elementscontributetotheproperintegrationofpair-ruleregulatoryinformation.Amodelfullyaccountingfortheseresultsproposesthatmetamericemslp1/emexpressionisachievedthroughtheRunt-dependentregulationofinteractionsbetweenthesetwopair-ruleresponseelementsandtheemslp1/empromoter./p/div