Iroquois transcription factors recognize a unique motif to mediate transcriptional repression in vivo
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Edited by Michael S. Levine, University of California, Berkeley, CA (received for review March 26, 2005)
Abstract
Iroquois transcription factors regulate diverse aspects of developmental patterning in all metazoans. Despite their widespread importance, the direct targets of the Iroquois are poorly understood. Here, we use in vitro site selection to define the DNA-binding preference of the Drosophila Iroquois Mirror. We use electrophoretic mobility shift assays to determine the critical nucleotides for Mirror binding and to show that this site is recognized by other Drosophila Iroquois transcription factors. This site also is recognized by vertebrate Iroquois transcription factors. Transgenic analysis demonstrates that Drosophila Iroquois proteins recognize this site in vivo to mediate transcriptional repression. We further show that Iroquois transcription factors form homodimers and heterodimers, suggesting that combinatorial binding may contribute to gene regulation by this family.
Footnotes
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↵ † To whom correspondence should be sent at the present address: Samuel Lunenfeld Research Institute, 600 University Avenue, Room 884, Toronto, ON, Canada M5G 1X5. E-mail: mcneill{at}mshri.on.ca.
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↵ * Present address: Centro de Biología Molecular “Severo Ochoa,” Consejo Superior de Investigaciones Cientificas, Universidad Autónoma, Canto Blanco, 28049 Madrid, Spain.
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This paper was submitted directly (Track II) to the PNAS office.
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Abbreviations: HA, hemagglutinin; HD, homeodomain; Iro, Iroquois; IBS, Iro binding site; IP, immunoprecipitated.
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Freely available online through the PNAS open access option.
- Copyright © 2005, The National Academy of Sciences
