Abstract
Nuclear architecture as well as gene nuclear positioning can modulate gene expression. In this work, we have analyzed the nuclear position of the interferon-β (IFN-β) locus, responsible for the establishment of the innate antiviral response, with respect to pericentromeric heterochromatin (PCH) in correlation with virus-induced IFN-β gene expression. Experiments were carried out in two different cell types either non-infected (NI) or during the time course of three different viral infections. In NI cells, we showed a monoallelic IFN-β promoter association with PCH that strongly decreased after viral infection. Dissociation of the IFN-β locus away from these repressive regions preceded strong promoter transcriptional activation and was reversible within 12 h after infection. No dissociation was observed after infection with a virus that abnormally maintained the IFN-β gene in a repressed state. Dissociation induced after virus infection specifically targeted the IFN-β locus without affecting the general structure and nuclear distribution of PCH clusters. Using cell lines stably transfected with wild-type or mutated IFN-β promoters, we identified the proximal region of the IFN-β promoter containing YY1 DNA-binding sites as the region regulating IFN-β promoter association with PCH before as well as during virus infection.