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Dev Biol. 2002 Dec 15;252(2):225-40.

Transcriptional integration of competence modulated by mutual repression generates cell-type specificity within the cardiogenic mesoderm.

Author information

1
Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA.

Abstract

The way in which spatially patterned cellular identities are generated is a central question of organogenesis. In the case of Drosophila heart formation, the cardiac progenitors are specified in precise mesodermal positions, giving rise to multiple cell types in a highly ordered arrangement. Here, we study the mechanisms by which positional information conveyed by signaling pathways and a combinatorial code of activating and repressing transcription factors work together to confine the expression of the homeobox gene even-skipped (eve) to a small region of the dorsal mesoderm. By manipulating both expression patterns and binding sites for transcription factors, we show that a complex combination of regulatory activities converge on a single enhancer of eve to generate precisely targeted gene expression within the cardiac mesoderm. In particular, ladybird early (lbe), a homeobox gene expressed adjacent to eve, restricts the positive actions of factors downstream of wingless, decapentaplegic, and ras to generate the eve pattern. Mutation of a Lbe binding site causes dramatic expansion of expression and abolishes the responsiveness to repression by lbe. Conversely, eliminating eve in the mesoderm expands lbe expression into the normal eve-expressing territory, suggesting that mutual repression between eve and lbe is essential for delineating the spatial patterns of gene expression that specify cell types within the cardiac mesoderm.

PMID:
12482712
PMCID:
PMC2693947
DOI:
10.1006/dbio.2002.0846
[Indexed for MEDLINE]
Free PMC Article

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