De-repression of RaRF-mediated RAR repression by adenovirus E1A in the nucleolus.
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 E1A 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 E1A and RaRF. Further fluorescence microscopy indicated that E1A and RaRF were located in the nucleoplasm and nucleolus, respectively. However, RaRF overexpression promoted nucleolar translocation of E1A 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 E1A 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.
Department of Bioscience & Biotechnology/Institute of Bioscience, BK21 Graduate Program, Sejong University, Seoul 143-747, Republic of Korea.
Soo-Jong
SJ
Um
Department of Bioscience & Biotechnology/Institute of Bioscience, BK21 Graduate Program, Sejong University, Seoul 143-747, Republic of Korea.
Hye Sook
HS
Youn
Department of Molecular Biology, Dankook University, Gyeonggi-do 448-701, Republic of Korea. Electronic address: nbrejk@dankook.ac.kr.
Eun-Joo
EJ
Kim
D000256:Adenoviridae / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D000257:Adenoviridae Infections / Q000378:metabolism* / Q000821:virology; D017500:Adenovirus E1A Proteins / Q000032:analysis / Q000378:metabolism*; D002460:Cell Line; D002466:Cell Nucleolus / Q000378:metabolism / Q000821:virology*; D054884:Host-Pathogen Interactions; D006801:Humans; D060066:Protein Interaction Maps; D017434:Protein Structure, Tertiary; D018168:Receptors, Retinoic Acid / Q000032:analysis / Q000378:metabolism*; D012097:Repressor Proteins / Q000032:analysis / Q000378:metabolism*; D014212:Tretinoin / Q000378:metabolism
D017500:Adenovirus E1A Proteins; D018168:Receptors, Retinoic Acid; D012097:Repressor Proteins; C571203:retinoic acid resistance factor, human; D014212:Tretinoin
Adenovirus E1A; Nucleolus; RAR; RaRF; Transcriptional repression