Binding affinities and cooperative interactions with bHLH activators delimit threshold responses to the dorsal gradient morphogen

Jin Jiang, Michael Levine

Research output: Contribution to journalArticlepeer-review

241 Scopus citations

Abstract

The dorsal (dl) morphogen gradient initiates the formation of the mesoderm, neuroectoderm, and dorsal ectoderm by setting different limits of regulatory gene expression along the dorsoventral axis of the early Drosophila embryo. In this paper, we show that low affinity dl-binding sites restrict target gene expression to the ventralmost regions (presumptive mesoderm), where there are peak levels of dl, while high affinity sites permit expression in ventrolateral regions (mesoderm and mesectoderm) containing intermediate levels of the morphogen. Activation by low levels of dl in lateral regions (the presumptive neuroectoderm) depends on cooperative DNA binding interactions between dl and bHLH proteins. The snall repressor blocks this interaction and restricts expression to the neuroectoderm. We discuss how enhancers serve as templates to bring weakly interacting regulatory factors into close proximity so that they can function combinatorially to activate and repress transcription.

Original languageEnglish (US)
Pages (from-to)741-752
Number of pages12
JournalCell
Volume72
Issue number5
DOIs
StatePublished - Mar 12 1993
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Biochemistry, Genetics and Molecular Biology(all)

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