How BAF (SWI/SNF) chromatin remodeling complexes regulate cis-regulatory chromatin organization

Le December 04 2025 at 15h00 Séminaire

BAF (SWI/SNF) remodeling complexes shape nucleosome organization and transcription factor binding at cis-regulatory elements, but their specific functions remain poorly defined. We examined how the three BAF subfamilies regulate chromatin structure at promoters, enhancers, and REST or CTCF sites. Our results show that canonical BAF (cBAF), unlike PBAF or ncBAF, drives the earliest step of pre-initiation complex assembly at active promoters and enhancers. At promoters, BRG1 and SMARCB1 generate fragile nucleosomes and subnucleosomal particles, while ARID1A promotes TBP/TFIIA recruitment independently of BRG1. At enhancers, these factors cooperate to organize chromatin and enable transcription factor binding. Distinct PBAF subunits, in turn, modulate chromatin at REST repressor sites. Together, these findings reveal non-redundant roles of BAF subunits in structuring cis-regulatory chromatin and initiating transcription.