R11: a cis-regulatory node of the sea urchin embryo gene network that controls early expression of SpDelta in micromeres

摘要

Ageneregulatorynetwork(GRN)controlstheprocessbywhichtheendomesodermoftheseaurchinembryoisspecified.InthisGRN,theprogramofgeneexpressionuniquetotheskeletogenicmicromerelineageissetintrainbyactivationoftheempmar1/emgene.Throughadoublerepressionsystem,thisgeneisresponsibleforlocalizationofexpressionofdownstreamregulatoryandsignalinggenestocellsofthislineage.Oneofthesegenes,emdelta/em,encodesaNotchligand,anditsexpressionintherightplaceandtimeiscrucialtothespecificationoftheendomesoderm.Herewereportaemcis/em-regulatoryelementR11thatisresponsibleforlocalizingtheexpressionofemdelta/embymeansofitsresponsetotheempmar1/emrepressionsystem.R11wasidentifiedasanevolutionarilyconservedgenomicsequencelocatedabout13kbdownstreamofthelastexonoftheemdelta/emgene.Wedemonstrateherethatthisemcis/em-regulatoryelementisabletodrivetheexpressionofareportergeneinthesamecellsandatthesametimethattheendogenousemdelta/emgeneisexpressed,andthattemporally,spatially,andquantitativelyitrespondstotheempmar1/emrepressionsystemjustaspredictedfortheemdelta/emgeneintheendomesodermGRN.Thisworkillustratestheapplicationofemcis/em-regulatoryanalysistothevalidationofpredictionsoftheGRNmodel.Inaddition,weintroducenewmethodologicaltoolsforquantitativemeasurementoftheoutputofexpressionconstructsthatpromisetobeofgeneralvalueforemcis/em-regulatoryanalysisinseaurchinembryos./p/div