Odd paired transcriptional activation of decapentaplegic in the Drosophila eye/antennal disc is cell autonomous but indirect.

The gene odd paired (opa), a Drosophila homolog of the Zinc finger protein of the cerebellum (Zic) family of mammalian transcription factors, plays roles in embryonic segmentation and development of the adult head. We have determined the preferred DNA binding sequence of Opa by SELEX and shown that it is necessary and sufficient to activate transcription of reporter gene constructs under Opa control in transgenic flies. We have found a related sequence in the enhancer region of an opa-responsive gene, sloppy paired 1. This site also responds to Opa in reporter constructs in vivo. However, nucleotide alterations that abolish the ability of Opa to bind this site in vitro have no effect on the ability of Opa to activate expression from constructs bearing these mutations in vivo. These data suggest that while Opa can function in vivo as a sequence specific transcriptional regulator, it does not require DNA binding for transcriptional activation.