Different molecular complexes that mediate transcriptional induction and repression by FoxP3

Area of Science:

• Immunology
• Molecular Biology
• Cell Biology

Background:

• The transcription factor FoxP3 is essential for regulatory T cell (Treg) function.
• The precise mechanism by which FoxP3 regulates gene expression (as an activator or repressor) remains poorly understood.

Purpose of the Study:

• To elucidate the mechanism of action of FoxP3 in regulating Treg cell transcription.
• To investigate how FoxP3 interacts with DNA, cofactors, and chromatin.

Main Methods:

• Chromatin analysis to identify FoxP3 binding sites.
• Assessment of FoxP3 mutants' transcriptional activity and interactions.
• Computational integration of data, biochemical interaction assays, and size analyses.
• Super-resolution microscopy to determine subcellular localization of FoxP3 complexes.

Main Results:

• FoxP3 binds to active enhancer elements, not repressed chromatin.
• FoxP3 forms distinct multimolecular complexes with varying transcriptional activity.
• FoxP3 acts as an activator when complexed with RELA, IKZF2, and KAT5.
• FoxP3 is inactive and localizes to the nuclear periphery when complexed with EZH2, YY1, and IKZF3.

Conclusions:

• FoxP3 exhibits multimodal transcriptional activity, acting as a context- and partner-dependent activator or repressor.
• These distinct modes of action are crucial for governing Treg cell phenotypes.