YY1 is involved in homologous recombination inhibition at guanine quadruplex sites in human cells

Homologous recombination (HR) is a key process for repairing DNA double strand breaks and for promoting genetic diversity, and it occurs unevenly throughout the genome. G-quadruplexes (G4s) are stable secondary structures widely present across the genome, which function in regulating gene transcription and maintaining genome stability. However, elevated G4 levels by BLM (RecQ like helicase unwinding G4) depletion can significantly drive HR at these G4 sites, which may threaten genome stability. Here, we investigated the role of Yin Yang-1 (YY1) in modulating HR at G4 sites. To elucidate G4 sites on the genome, cleavage under targets and tagmentation (CUT&Tag) of BG4, a G4 specific antibody, was conducted. Cleavage under targets and tagmentation (CUT&Tag) for BG4 in HEK293T cells.