Structural rules and complex regulatory circuitry constrain expression of a Notch- and EGFR-regulated eye enhancer.
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.
Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109, USA.
Christina I
CI
Swanson
Nicole C
NC
Evans
Scott
S
Barolo
D000818:Animals; D030801:Animals, Genetically Modified; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D004247:DNA / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D004330:Drosophila / Q000235:genetics* / Q000254:growth & development* / Q000378:metabolism; D029721:Drosophila Proteins / Q000235:genetics* / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D004742:Enhancer Elements, Genetic; D066246:ErbB Receptors / Q000235:genetics / Q000378:metabolism*; D019143:Evolution, Molecular; D005123:Eye / Q000254:growth & development* / Q000378:metabolism; D005136:Eye Proteins / Q000235:genetics* / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D017344:Genes, Insect; D020935:MAP Kinase Signaling System; D008969:Molecular Sequence Data; D016296:Mutagenesis; D051762:PAX2 Transcription Factor / Q000235:genetics / Q000378:metabolism; D017956:Photoreceptor Cells, Invertebrate / Q000166:cytology / Q000378:metabolism; D018010:Receptors, Invertebrate Peptide / Q000235:genetics / Q000378:metabolism*; D051880:Receptors, Notch / Q000235:genetics / Q000378:metabolism*; D012689:Sequence Homology, Nucleic Acid
D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D005136:Eye Proteins; C497759:N protein, Drosophila; D051762:PAX2 Transcription Factor; D018010:Receptors, Invertebrate Peptide; D051880:Receptors, Notch; C107990:sv protein, Drosophila; D004247:DNA; C066532:Egfr protein, Drosophila; D066246:ErbB Receptors