title: Identification and characterization of a novel nuclear protein complex involved in nuclear hormone receptor-mediated gene regulation.
abstract: NRC/NCoA6 plays an important role in mediating the effects of ligand-bound nuclear hormone receptors as well as other transcription factors. NRC interacting factor 1 (NIF-1) was cloned as a novel factor that interacts in vivo with NRC. Although NIF-1 does not directly interact with nuclear hormone receptors, it enhances activation by nuclear hormone receptors presumably through its interaction with NRC. To further understand the cellular and biological function of NIF-1, we identified NIF-1-associated proteins by in-solution proteolysis followed by mass spectrometry. The identified components revealed factors involved in histone methylation and cell cycle control and include Ash2L, RbBP5, WDR5, HCF-1, DBC-1, and EMSY. Although the NIF-1 complex contains Ash2L, RbBP5, and WDR5, suggesting that the complex might methylate histone H3-Lys-4, we found that the complex contains a H3 methyltransferase activity that modifies a residue other than H3-Lys-4. The identified components form at least two distinctly sized NIF-1 complexes. DBC-1 and EMSY were identified as integral components of an NIF-1 complex of approximately 1.5 MDa and were found to play an important role in the regulation of nuclear receptor-mediated transcription. Stimulation of the Sox9 and HoxA1 genes by retinoic acid receptor-alpha was found to require both DBC-1 and EMSY in addition to NIF-1 for maximal transcriptional activation. Interestingly, NRC was not identified as a component of the NIF-1 complex, suggesting that NIF-1 and NRC do not exist as stable in vitro purified complexes, although the separate NIF-1 and NRC complexes appear to functionally interact in the cell.
authors.affiliation: Department of Pharmacology, New York University School of Medicine, New York, New York 10016, USA.
authors.forename: Shivani
authors.initials: S
authors.lastname: Garapaty
authors.forename: Chong-Feng
authors.initials: CF
authors.lastname: Xu
authors.forename: Patrick
authors.initials: P
authors.lastname: Trojer
authors.forename: Muktar A
authors.initials: MA
authors.lastname: Mahajan
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Neubert
authors.forename: Herbert H
authors.initials: HH
authors.lastname: Samuels
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism; D002453:Cell Cycle / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000378:metabolism; D005786:Gene Expression Regulation / Q000502:physiology*; D006367:HeLa Cells; D011495:Histone-Lysine N-Methyltransferase / Q000378:metabolism; D006657:Histones / Q000378:metabolism; D018398:Homeodomain Proteins / Q000378:metabolism; D051863:Host Cell Factor C1 / Q000378:metabolism; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D008745:Methylation; D046912:Multiprotein Complexes / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism; D056918:Nuclear Receptor Coactivators; D011496:Protein Methyltransferases / Q000378:metabolism*; D018168:Receptors, Retinoic Acid / Q000378:metabolism*; D012097:Repressor Proteins / Q000378:metabolism; D000072482:Retinoic Acid Receptor alpha; D054840:Retinol-Binding Proteins, Cellular / Q000378:metabolism; D055758:SOX9 Transcription Factor / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism; D000099261:Homeobox A1 Protein
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D004268:DNA-Binding Proteins; D011495:Histone-Lysine N-Methyltransferase; D006657:Histones; D018398:Homeodomain Proteins; D051863:Host Cell Factor C1; D047908:Intracellular Signaling Peptides and Proteins; D046912:Multiprotein Complexes; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D056918:Nuclear Receptor Coactivators; D011496:Protein Methyltransferases; D018168:Receptors, Retinoic Acid; D012097:Repressor Proteins; D000072482:Retinoic Acid Receptor alpha; D054840:Retinol-Binding Proteins, Cellular; D055758:SOX9 Transcription Factor; D014157:Transcription Factors; D000099261:Homeobox A1 Protein; C485622:ASH2L protein, human; C527450:CCAR2 protein, human; C480344:EMSY protein, human; C497692:HCFC1 protein, human; C486559:NCOA6 protein, human; C000607071:RARA protein, human; C526967:RBP5 protein, human; C527932:SOX9 protein, human; C502547:WDR5 protein, human; C466083:ZNF335 protein, human