Guey, BaptisteWischnewski, MarilenaDecout, AlexianeMakasheva, KristinaKaynak, MuratSakar, SelmanFierz, BeatAblasser, Andrea2020-08-202020-08-202020-08-202020-08-1410.1126/science.aaw6421https://infoscience.epfl.ch/handle/20.500.14299/170999The appearance of DNA in the cytosol is perceived as a danger signal that stimulates potent immune responses through cyclic guanosine monophosphate–adenosine monophosphate synthase (cGAS). How cells regulate the activity of cGAS toward self-DNA and guard against potentially damaging autoinflammatory responses is a fundamental biological question. Here, we identify barrier-to-autointegration factor 1 (BAF) as a natural opponent of cGAS activity on genomic self-DNA. We show that BAF dynamically outcompetes cGAS for DNA binding, hence prohibiting the formation of DNA-cGAS complexes that are essential for enzymatic activity. Upon acute loss of nuclear membrane integrity, BAF is necessary to restrict cGAS activity on exposed DNA. Our observations reveal a safeguard mechanism, distinct from physical separation, by which cells protect themselves against aberrant immune responses toward genomic DNA.text::journal::journal article::research article