The ciD mutation encodes a chimeric protein whose activity is regulated by Wingless signaling

Area of Science:

• Developmental Biology
• Molecular Biology
• Genetics

Background:

• The Drosophila cubitus interruptus (ci) gene is crucial for regulating Hedgehog (Hh) target genes.
• Ci protein activity is normally modulated by Hh signaling pathways.
• Mutations in ci can alter gene regulation mechanisms.

Purpose of the Study:

• To investigate the molecular basis of altered gene regulation in the ciD mutant.
• To determine the role of Wingless (Wg) signaling in the ciD mutant phenotype.
• To elucidate the interaction between Ci, Wg, and Hh signaling pathways.

Main Methods:

• Genetic analysis of the ciD mutation in Drosophila.
• Protein domain analysis to identify chimeric protein composition.
• Assays to study gene transcription regulation by Wg and Hh pathways.
• Co-immunoprecipitation to assess protein interactions.

Main Results:

• The ciD mutation results in a chimeric protein combining dTCF/Pangolin (Pan) regulatory domain with the Ci DNA-binding domain.
• This ciD protein mediates Wg-dependent transcription of Hh target genes.
• Constitutively active Armadillo (Arm) enhances CiD activity and interacts with CiD protein.

Conclusions:

• The Wg-responsive activity of CiD is likely due to the recruitment of Arm's transactivation function to Hh target gene promoters.
• This study suggests that wild-type Ci protein may also recruit a transactivation domain-containing protein for its normal activation mechanism.