Subcellular localization of ankyrin repeats cofactor-1 regulates its corepressor activity.
The ankyrin repeats cofactor-1 (ANCO-1) was recently identified as a novel nuclear receptor corepressor that regulates receptor-mediated transcription through interactions with p160 coactivators and histone deacetylases. Interestingly, exogenously expressed ANCO-1 is localized at distinct subnuclear domains. The relevance of these subnuclear domains and the mechanisms of nucleocytoplasmic translocation of ANCO-1 have not been determined. We report here the identification of an N-terminal signaling motif that is essential for both nuclear/subnuclear localization and transcription corepressor function of ANCO-1. This N-terminal motif at residues 80-86 of ANCO-1 constitutes a classical nuclear localization signal (NLS1). Disruption of NLS1 causes complete cytoplasmic accumulation of the full-length ANCO-1, and abolishes its corepressor function on receptor-mediated transcription. A second NLS (NLS2) is found at the C-terminal residues 2384-2390; however, its disruption abolishes only nuclear localization of isolated C-terminal fragments. We also identify a leucine-rich nuclear export signal (NES) at residues 2415-2424 of ANCO-1, and show that both the NLSs and NES sequences are capable of mediating nuclear import and export of heterologous protein, respectively. In addition, attachment of the NES sequence to a transcription factor impairs its activation function. These results suggest that ANCO-1 subnuclear localization is regulated by both nuclear import and export signals, and that proper subcellular localization of ANCO-1 is essential for its corepressor function.
Zhang
Aihua
A
Department of Pharmacology, University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, Piscataway, New Jersey 08854-5635, USA.
Li
Chia-Wei
CW
Tsai
Shih-Chieh
SC
Chen
J Don
JD
D000595:Amino Acid Sequence; D000818:Animals; D017089:Ankyrin Repeat; D019556:COS Cells; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism*; D002522:Chlorocebus aethiops; D004252:DNA Mutational Analysis; D017405:Herpes Simplex Virus Protein Vmw65 / Q000235:genetics; D006801:Humans; D008969:Molecular Sequence Data; D019913:Nuclear Localization Signals / Q000737:chemistry* / Q000378:metabolism*; D010446:Peptide Fragments / Q000378:metabolism; D021381:Protein Transport; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012097:Repressor Proteins / Q000737:chemistry* / Q000378:metabolism*; D013347:Subcellular Fractions; D014158:Transcription, Genetic
D017405:Herpes Simplex Virus Protein Vmw65; D019913:Nuclear Localization Signals; D010446:Peptide Fragments; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins