Molecular Integration of Inductive and Mesoderm-Intrinsic Inputs Governs even-skipped Enhancer Activity in a Subset of Pericardial and Dorsal Muscle Progenitors

Developmental Biology

Stefan Knirr¹  Manfred Frasch¹ 

[1] Department of Biochemistry and Molecular Biology, Box 1020, Mount Sinai School of Medicine, New York, New York, 10029

关键词: muscle founders;    pericardial cells;    heart;    even-skipped;    induction;    enhancer;   

DOI  :  10.1006/dbio.2001.0397

学科分类：生物科学（综合）

来源: Academic Press

【 摘 要 】

IndividualsomaticmusclesandheartprogenitorsarespecifiedatdefinedpositionswithinthemesodermallayerofDrosophila.Theexpressionofthehomeoboxgeneeven-skipped(eve)identifiesonespecificsubsetofcellsinthedorsalmesoderm,whichgiverisetoparticularpericardialcellsanddorsalbodywallmuscles.Geneticanalysishasshownthattheinductionofeveinthesecellsinvolvesthecombinedactivitiesofgenesencodingmesoderm-intrinsicfactors,suchasTinman(Tin),andspatiallyrestrictedsignalingactivitiesthatarelargelyderivedfromtheectoderm,particularlythoseencodedbywingless(wg)anddecapentaplegic(dpp).HereweshowthataDpp-activatedSmadprotein,phosphorylatedMad,iscolocalizedineve-expressingcellsduringanextendeddevelopmentalperiod.WedemonstratefurtherthatamesodermallyactiveenhancerofevecontainsseveralSmadandTinbindingsitesthatareessentialforenhanceractivityinvivo.ThisenhanceralsocontainsanumberofbindingsitesfortheWg-effectorPangolin(Pan/Lef-1),whicharerequiredforfulllevelsofenhanceractivity.However,wefindthattheirmainfunctionistopreventectopicenhanceractivityinthedorsalmesoderm.Thissuggeststhat,intheabsenceofWgsignaling,PanbindingservestoabrogatethesynergisticactivitiesofSmadsandTinineveactivationwhile,incellsthatreceiveWgsignals,Panisconvertedintoacoactivatorthatpromoteseveinduction.Together,thesedatashowthattheeveenhancerintegratesseveralregulatorypathwaysviathecombinatorialbindingofthemesoderm-intrinsicregulatorTinandtheeffectorsoftheDppandWgsignals.

【 授权许可】

Unknown