Ku70 Is a Novel Cytosolic DNA Sensor that Induces Type-III Rather than Type-I IFN

摘要

Cytosolic foreign DNA is detected by pattern recognition receptors and mainly induces Type-I IFN production. We found that transfection of different types of DNA into various untreated cells induces Type-III IFN (IFN-lambda1) rather than Type-I IFN, indicating the presence of uncharacterized DNA sensor(s). A pull-down assay using cytosolic proteins identified that Ku70 and Ku80 are the DNA binding proteins. The knockdown studies and the reporter assay revealed that Ku70 is a novel DNA sensor inducing the IFN-lambda1 activation. The functional analysis of IFNL1 promoter revealed that PRDI and ISRE sites are predominantly involved in the DNA-mediated IFNL1 activation. A pull-down assay using nuclear proteins demonstrated that the IFN-lambda1 induction is associated with the activation of IRF-1 and IRF-7. Thus we show for the first time that Ku70 mediates type III IFN induction by DNA.