Genes regulating the remote wing margin enhancer in the Drosophila cut locus

Area of Science:

• Developmental Biology
• Genetics
• Molecular Biology

Background:

• Enhancers activate gene promoters over long distances, a process crucial for development.
• The Drosophila suppressor of Hairy-wing (SUHW) protein inhibits enhancer-promoter communication, particularly when gypsy retrotransposons are involved.
• SUHW's mechanism is thought to involve interfering with structural factors facilitating enhancer-promoter interactions, rather than directly blocking enhancer-binding activators.

Purpose of the Study:

• To identify genes encoding factors that facilitate enhancer-promoter interactions.
• To investigate the mechanism by which SUHW disrupts enhancer function.
• To determine if the identified factors are targets of SUHW's enhancer-blocking activity.

Main Methods:

• A genetic screen was performed in Drosophila to find mutations that disrupt the activity of the wing margin enhancer in the cut gene.
• Mutations in known genes (scalloped, mastermind) and a novel gene (Chip) were isolated.
• Analysis of genetic interactions and the effect of mutations on enhancer sensitivity to gypsy insertions.

Main Results:

• Mutations in scalloped, mastermind, and Chip were identified as affecting enhancer function.
• Scalloped protein binds the wing margin enhancer via its TEA DNA-binding domain.
• Chip acts synergistically with scalloped and mastermind, and is essential for enhancer function.
• Chip mutations hypersensitize the wing margin enhancer to gypsy insertions, suggesting Chip is a target of SUHW.

Conclusions:

• Chip is a novel gene essential for enhancer-promoter communication and acts synergistically with other identified factors.
• Chip is a likely target of SUHW's enhancer-blocking activity, mediating the disruption of long-range enhancer function.
• These findings provide insights into the molecular mechanisms underlying enhancer function and regulation by SUHW in Drosophila.