Transcriptional activity of the retinoic acid receptor (RAR) is regulated by diverse binding partners, including classical corepressors and coactivators, in response to its ligand retinoic acid (RA). Recently, we identified a novel corepressor of RAR called the retinoic acid resistance factor (RaRF) (manuscript submitted). Here, we report how adenovirus El A stimulates RAR activity by associating with RaRF. Based on immunoprecipitation (IP) assays, E1A interacts with RaRF through the conserved region 2 (CR2), which is also responsible for pRb binding. The first coiled-coil domain of RaRF was sufficient for this interaction. An in vitro glutathione-S-transferase (GST) pull-down assay was used to confirm the direct interaction between El A and RaRF. Further fluorescence microscopy indicated that El A and RaRF were located in the nucleoplasm and nucleolus, respectively. However, RaRF overexpression promoted nucleolar translocation of El A from the nucleoplasm. Both the RA-dependent interaction of RAR with RaRF and RAR translocation to the nucleolus were disrupted by E1A. RaRF-mediated RAR repression was impaired by wild-type E1A, but not by the RaRF binding-defective El A mutant. Taken together, our data suggest that E1A is sequestered to the nucleolus by RaRF through a specific interaction, thereby leaving RAR in the nucleoplasm for transcriptional activation. (C) 2014 Elsevier Inc. All rights reserved.