Building the heart piece by piece: modularity of cis-elements regulating Nkx2-5 transcription.
Heart formation in Drosophila is dependent on the homeobox gene tinman. The homeobox gene Nkx2-5 is closely related to tinman and is the earliest known marker for cardiogenesis in vertebrate embryos. Recent studies of cis-regulatory elements required for Nkx2-5 expression in the developing mouse heart have revealed an extraordinary array of independent cardiac enhancers, and associated negative regulatory elements, that direct transcription in distinct regions of the embryonic heart. These studies demonstrate the modularity in cardiac transcription, in which different regulatory elements respond to distinct sets of transcription factors to control gene expression in different compartments of the developing heart. We consider the potential mechanisms underlying such transcriptional complexity, its possible significance for cardiac function, and the implications for evolution of the multichambered heart.
Schwartz
R J
RJ
Department of Cell Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA. eolson@hamon.swmed.edu
Olson
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EN
D000818:Animals; D004330:Drosophila; D018507:Gene Expression Regulation, Developmental; D005809:Genes, Regulator / Q000502:physiology; D006321:Heart / Q000033:anatomy & histology / Q000196:embryology*; D000072576:Homeobox Protein Nkx-2.5; D018398:Homeodomain Proteins / Q000235:genetics*; D051379:Mice; D008822:Mice, Transgenic; D008957:Models, Genetic; D015398:Signal Transduction; D014157:Transcription Factors; D014158:Transcription, Genetic; D029867:Xenopus Proteins
D000072576:Homeobox Protein Nkx-2.5; D018398:Homeodomain Proteins; C095552:NKX2-5 protein, human; C484469:Nkx2-5 protein, mouse; D014157:Transcription Factors; D029867:Xenopus Proteins