Thymic epithelial cells (TEC) create the unique environment for the selection of T cells that are tolerant to self but reactive to foreign antigens. For this purpose, TEC express an almost comprehensive repertoire of self-antigens, through a process referred to as promiscuous gene expression (PGE). The precise molecular mechanisms that account for PGE remain incompletely defined although a subset of promiscuously expressed genes rely for their efficient expression on the presence of t...