title: Complex cardiac Nkx2-5 gene expression activated by noggin-sensitive enhancers followed by chamber-specific modules.
abstract: We previously reported that an Nkx2-5-GFP bacterial artificial chromosome in transgenic mice recapitulated the endogenous gene activity in the heart. Here, we identified three additional previously uncharacterized distal enhancer modules of Nkx2-5: UH6, which directed transgene expression in the right ventricle, interventricular septum, and atrial ventricular canal; UH5, which directed expression in both atria; and UH4, which directed transgene expression in tongue muscle. Nkx2-5 enhancers drive cardiogenic gene activity from the earliest progenitors to the late-stage embryonic heart, reside within its 27 kb of 5' flanking sequences, organized in a tandem array. Nkx2-5 enhancers involved with stomach-, tongue-, and chamber-restricted expression displayed lacZ transgene activity and chromatin histone acetylation patterns consistent with tissue-specific expression. An examination of Nkx2-5 gene activity in murine embryonic stem cells converted to beating embryoid bodies showed that only the proximal active region 2 and GATA-Smad enhancers were chromatin-remodeled. Chromatin remodeling of active region 2 and GATA-Smad enhancers were blunted by noggin coexpression, which indicated dependence on bone morphogenetic protein signaling for their chromatin activation during activation of Nkx2-5 expression.
authors.affiliation: Graduate Program in Cardiovascular Sciences and Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA.
authors.forename: Xuan
authors.initials: X
authors.lastname: Chi
authors.forename: Pradeep K
authors.initials: PK
authors.lastname: Chatterjee
authors.forename: Willie
authors.initials: W
authors.lastname: Wilson
authors.forename: Shu-Xing
authors.initials: SX
authors.lastname: Zhang
authors.forename: Franco J
authors.initials: FJ
authors.lastname: Demayo
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Schwartz
mesh_terms: D000818:Animals; D019485:Bone Morphogenetic Proteins / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism*; D002478:Cells, Cultured; D042002:Chromatin Assembly and Disassembly / Q000235:genetics; D022202:Chromosomes, Artificial, Bacterial / Q000235:genetics; D004622:Embryo, Mammalian / Q000166:cytology / Q000502:physiology; D004742:Enhancer Elements, Genetic / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental / Q000235:genetics*; D006325:Heart Atria / Q000196:embryology; D006352:Heart Ventricles / Q000196:embryology; D000072576:Homeobox Protein Nkx-2.5; D018398:Homeodomain Proteins / Q000096:biosynthesis* / Q000235:genetics; D051379:Mice; D008822:Mice, Transgenic; D009928:Organ Specificity / Q000235:genetics; D015398:Signal Transduction / Q000235:genetics; D013234:Stem Cells / Q000166:cytology / Q000378:metabolism; D014059:Tongue / Q000196:embryology; D014157:Transcription Factors / Q000096:biosynthesis* / Q000235:genetics; D019076:Transgenes / Q000502:physiology; D000099176:Noggin Protein
chemical_list: D019485:Bone Morphogenetic Proteins; D002352:Carrier Proteins; D000072576:Homeobox Protein Nkx-2.5; D018398:Homeodomain Proteins; D014157:Transcription Factors; D000099176:Noggin Protein; C484469:Nkx2-5 protein, mouse