Transcriptional regulators form diverse groups with context-dependent regulatory functions

Area of Science:

• Molecular Biology
• Genetics
• Developmental Biology

Background:

• Gene expression is controlled by transcription factors (TFs) and cofactors regulating enhancers.
• TF binding is studied, but their combinatorial control of enhancer function remains unclear.
• Understanding TF roles in combinatorial activation and functional grouping is crucial.

Purpose of the Study:

• To systematically assess the regulatory roles of TFs and cofactors in combinatorial enhancer control.
• To identify functional groups of TFs and understand their context-dependent activities.
• To explore TF substitution and TF-cofactor cooperation in enhancer function.

Main Methods:

• Utilized enhancer complementation assays in Drosophila S2 cells.
• Tested 812 GAL4-DNA-binding-domain fused TFs and cofactors across 24 enhancer contexts.
• Performed 82,752 luciferase assays to measure enhancer activity.

Main Results:

• Most tested factors showed context-dependent functionality, with effects ranging from repression to 289-fold activation.
• Defined 15 functional TF groups based on activity patterns, developmental roles, and sequence features.
• Demonstrated TF motif exchange for enhancer re-engineering and identified cooperating/interacting TF-cofactor pairs.

Conclusions:

• TF and cofactor regulatory functions are diverse and highly context-dependent.
• Functional grouping and substitution principles offer insights into combinatorial enhancer control.
• Systematic characterization advances understanding of gene regulation by enhancers.