Abstract
Enhancers integrate spatiotemporal information to generate precise patterns of gene expression. How complex is the regulatory logic of a typical developmental enhancer, and how important is its internal organization? Here, we examine in detail the structure and function of sparkling, a Notch- and EGFR/MAPK-regulated, cone cell-specific enhancer of the Drosophila Pax2 gene, in vivo. In addition to its 12 previously identified protein-binding sites, sparkling is densely populated with previously unmapped regulatory sequences, which interact in complex ways to control gene expression. One segment is essential for activation at a distance, yet dispensable for other activation functions and for cell type patterning. Unexpectedly, rearranging sparkling's regulatory sites converts it into a robust photoreceptor-specific enhancer. Our results show that a single combination of regulatory inputs can encode multiple outputs, and suggest that the enhancer's organization determines the correct expression pattern by facilitating certain short-range regulatory interactions at the expense of others.
Copyright 2010 Elsevier Inc. All rights reserved.
Publication types
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Research Support, N.I.H., Extramural
MeSH terms
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Animals
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Animals, Genetically Modified
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Base Sequence
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Binding Sites / genetics
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DNA / genetics
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DNA-Binding Proteins / genetics*
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DNA-Binding Proteins / metabolism
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Drosophila / genetics*
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Drosophila / growth & development*
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Drosophila / metabolism
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Drosophila Proteins / genetics*
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Drosophila Proteins / metabolism*
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Drosophila melanogaster / genetics
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Drosophila melanogaster / growth & development
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Drosophila melanogaster / metabolism
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Enhancer Elements, Genetic
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ErbB Receptors / genetics
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ErbB Receptors / metabolism*
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Evolution, Molecular
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Eye / growth & development*
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Eye / metabolism
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Eye Proteins / genetics*
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Eye Proteins / metabolism
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Gene Expression Regulation, Developmental
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Genes, Insect
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MAP Kinase Signaling System
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Molecular Sequence Data
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Mutagenesis
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PAX2 Transcription Factor / genetics
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PAX2 Transcription Factor / metabolism
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Photoreceptor Cells, Invertebrate / cytology
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Photoreceptor Cells, Invertebrate / metabolism
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Receptors, Invertebrate Peptide / genetics
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Receptors, Invertebrate Peptide / metabolism*
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Receptors, Notch / genetics
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Receptors, Notch / metabolism*
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Sequence Homology, Nucleic Acid
Substances
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DNA-Binding Proteins
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Drosophila Proteins
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Eye Proteins
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N protein, Drosophila
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PAX2 Transcription Factor
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Receptors, Invertebrate Peptide
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Receptors, Notch
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sv protein, Drosophila
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DNA
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Egfr protein, Drosophila
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ErbB Receptors