Expression of TGF-βs and Their Receptors during Implantation and Organogenesis of the Mouse Embryo

[摘要] Thespatialandtemporalexpressionofthetransforminggrowthfactorβ(TGF-β)receptorstypeIII,typeII,andtwotypesI(ALK-5andTsk7L)andtheirligandsTGF-β1andTGF-β2inpostimplantationmousedevelopmentwereexaminedusingthereversetranscriptionpolymerasechainreaction(RT-PCR),insituhybridization,andimmunohistochemistry.WithRT-PCR,expressionofthesignalingTGF-βreceptors(typesIIandALK-5)wasshowntobeabsentinisolatedgermlayersof6.0-7.5dayspostcoitum(dpc)embryos,whereasthetypeIIIreceptorandTsk7Lweredifferentiallyexpressedatthesestages.Incontrast,allTGF-βreceptortypeswereexpressedatthesestagesinthepregnantuterusanddecidua.TGF-β1andTGF-β2transcriptsweredetectedbeforegastrulationat6.5dpconlyinthevisceralembryonicendoderm,whereasduringgastrulation,at7.5dpcTGF-β1andTGF-β2mRNAwasdetectedinallthreegermlayers.InsituhybridizationandimmunohistochemistryoftheexpressionoftheTGF-βtypeIIreceptorconfirmedthedataobtainedbyRT-PCR.Furthermore,thetypeIIreceptorwasdetectedintheextraembryonicectodermof7.5dpcembryos.Intheembryoproper,TGF-βtypeIIreceptorexpressionwasdetectedonlylaterindifferentiatingtissuesanddevelopingorgans,butnotinthebrainandneuraltube.SincetheexpressionofthetypeIIreceptormayessentiallydeterminewhetheracellisabletorespondtoTGF-β,theresultsareconsistentwiththeviewthatTGF-βsmightbeimplicatedinembryoimplantationandorganogenesis,butarenotinvolvedingastrulationoftheembryo.