Drosophila Mi-2 negatively regulates dDREF by inhibiting its DNA-binding activity

Area of Science:

• * Molecular biology
• * Genetics
• * Developmental biology

Background:

• * Drosophila melanogaster DNA replication-related element (DRE) factor (dDREF) regulates gene expression via the 5'-TATCGATA DRE sequence.
• * dDREF's potential role in insulator activity and chromatin boundary elements is suggested.
• * Understanding dDREF's regulatory network is crucial for comprehending gene expression control.

Purpose of the Study:

• * To identify proteins interacting with dDREF using yeast two-hybrid screening.
• * To elucidate the functional relationship between dDREF and its interacting partners.
• * To investigate the role of Mi-2 in dDREF-mediated gene regulation.

Main Methods:

• * Saccharomyces cerevisiae two-hybrid screening to identify DREF-interacting proteins.
• * Biochemical analyses and electrophoretic mobility shift assays (EMSA) to characterize protein-DNA interactions.
• * In vivo studies using Drosophila eye imaginal discs and polytene chromosome immunostaining.

Main Results:

• * Mi-2 was identified as a dDREF-interacting protein, with binding occurring between the C-terminal region of dMi-2 and the DNA-binding domain of dDREF.
• * dMi-2 inhibits the DNA-binding activity of dDREF.
• * Co-expression of dDREF and dMi-2 in Drosophila eye imaginal discs suppressed rough-eye phenotypes, while dMi-2 gene reduction enhanced dDREF-induced phenotypes.
• * Immunostaining revealed mutually exclusive binding of dDREF and dMi-2 on polytene chromosomes.

Conclusions:

• * Mi-2 negatively regulates dDREF transcriptional activity by inhibiting its DNA-binding.
• * dMi-2 plays a novel role in controlling dDREF function.
• * dDREF and dMi-2 may exhibit reciprocal regulation, suggesting a complex regulatory feedback loop.