Neural precursor-specific expression of multiple Drosophila genes is driven by dual enhancer modules with overlapping...

Area of Science:

• Developmental Biology
• Genetics
• Molecular Biology

Background:

• Transcriptional cis-regulatory modules (CRMs), or enhancers, control gene expression in specific cell types and developmental territories.
• Some genes are regulated by multiple enhancers with overlapping specificities.

Purpose of the Study:

• To investigate the role of dual enhancers in regulating genes specifically expressed in neural precursor (NP) cells in Drosophila.
• To identify and characterize NP-specific enhancer modules and their regulatory mechanisms.

Main Methods:

• Genome-wide computational discovery of binding motifs for proneural activator (P) and basic helix-loop-helix (bHLH) repressor (R) factors (P+R code).
• Identification of NP-specific enhancer modules associated with NP genes.
• In vivo reporter gene assays using wild-type and mutant constructs.
• Genomic rescue constructs for the neuralized (neur) gene.

Main Results:

• Identified NP-specific enhancer modules utilizing a P+R regulatory code, distinct from previously known enhancers.
• Demonstrated that P sites mediate activation and R sites mediate repression, restricting expression to NP cells.
• Showed that each of the two NP-specific enhancers for neur is sufficient for rescuing its function in sensory organ precursor (SOP) specification.

Conclusions:

• Dual, or shadow, enhancers are a common feature of genes active in Drosophila NP cells.
• The P+R regulatory code is crucial for precise spatial and temporal gene expression in NP cells.
• These findings reveal novel regulatory mechanisms in neural development and identify new targets for bHLH repressors.