Mesodermal repression of single-minded in Drosophila embryo is mediated by a cluster of Snail-binding sites proximal to the early promoter

• Main Author: Kye Won Park1 & Joung-Woo Hong2,*
• Format: Article
• Language: English
• Published: Korean Society for Biochemistry and Molecular Biology 2012-10-01
• Series: BMB Reports
• Subjects: Direct repression; Drosophila embryo; Mesodermal repression; Single-minded; Snail
• Online Access: http://www.jbmb.or.kr/jbmb/pdf.php?data=MTMwMTIyMTdAcGRmX3JhaW50cmFjZV9sZWV5c0AlNUI0NS0xMCU1RDEyMTAyOTIxMjBfJTI4NTc3LTU4MiUyOUJNQl8xMi0xMDUucGRm

single-minded (sim) is a master regulatory gene that directs differentiationin the central nervous system during Drosophilaembryogenesis. Recent identification of the mesectoderm enhancer(MSE) of sim has led to the hypothesis that two Snail(Sna)-binding sites in the MSE may repress sim expression inthe presumptive mesoderm. We provide evidence here thatthree Sna-binding sites proximal to the sim promoter, but notthose of the MSE, are responsible for the mesodermal repressionof sim in vivo. Using transgenic embryos injectedwith lacZ transgenes, we showed that sim repression in themesoderm requires the three promoter-proximal Sna-bindingsites. These results suggest that Sna represses the mesectodermalexpression of sim by directly repressing the nearby promoter,and not by quenching adjacent transcriptional activatorsin the MSE. These data also showed how the MSE, lackingthe three proximal Sna-binding sites, reproduced the endogenouspattern of sim expression in transgenic embryos.