Zinc finger (ZnF) proteins represent one of the largest families of human proteins, although most remain uncharacterized. Given that numerous ZnF proteins are able to interact with DNA and poly(ADP ribose), there is growing interest in understanding their mechanism of action in the maintenance of genome integrity. We now report that the ZnF protein E4F transcription factor 1 (E4F1) is an actor in DNA repair. Indeed, E4F1 is rapidly recruited, in a poly(ADP ribose) polymerase (PARP)-dependent manner, to DNA breaks and promotes ATR/CHK1 signaling, DNA-end resection, and subsequent homologous recombination. Moreover, we identify E4F1 as a regulator of the ATP-dependent chromatin remodeling SWI/SNF complex in DNA repair. E4F1 binds to the catalytic subunit BRG1/SMARCA4 and together with PARP-1 mediates its recruitment to DNA lesions. We also report that a proportion of human breast cancers show amplification and overexpression of E4F1 or BRG1 that are mutually exclusive with BRCA1/2 alterations. Together, these results reveal a function of E4F1 in the DNA damage response that orchestrates proper signaling and repair of double-strand breaks and document a molecular mechanism for its essential role in maintaining genome integrity and cell survival.
Keywords: BRG1; E4F1; PARP-1; breast cancer; double-strand break.