Both corepressor proteins SMRT and N-CoR exist in large protein complexes containing HDAC3.
We present evidence that both corepressors SMRT and N-CoR exist in large protein complexes with estimated sizes of 1.5-2 MDa in HeLa nuclear extracts. Using a combination of conventional and immunoaffinity chromatography, we have successfully isolated a SMRT complex and identified histone deacetylase 3 (HDAC3) and transducin (beta)-like I (TBL1), a WD-40 repeat-containing protein, as the subunits of the purified SMRT complex. We show that the HDAC3-containing SMRT and N-CoR complexes can bind to unliganded thyroid hormone receptors (TRs) in vitro. We demonstrate further that in Xenopus oocytes, both SMRT and N-CoR also associate with HDAC3 in large protein complexes and that injection of antibodies against HDAC3 or SMRT/N-CoR led to a partial relief of repression by unliganded TR/RXR. These findings thus establish both SMRT and N-CoR complexes as bona fide HDAC-containing complexes and shed new light on the molecular pathways by which N-CoR and SMRT function in transcriptional repression.
Li
J
J
Department of Molecular and Cellular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA.
Wang
J
J
Wang
J
J
Nawaz
Z
Z
Liu
J M
JM
Qin
J
J
Wong
J
J
D000818:Animals; D015153:Blotting, Western; D002467:Cell Nucleus / Q000378:metabolism; D002846:Chromatography, Affinity; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D006367:HeLa Cells; D006655:Histone Deacetylases / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D008024:Ligands; D009687:Nuclear Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D056971:Nuclear Receptor Co-Repressor 1; D056985:Nuclear Receptor Co-Repressor 2; D009865:Oocytes / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D018168:Receptors, Retinoic Acid / Q000378:metabolism; D011988:Receptors, Thyroid Hormone / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D012097:Repressor Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D014158:Transcription, Genetic; D020798:Two-Hybrid System Techniques; D014981:Xenopus; D000099186:Histone Deacetylase 3
D004268:DNA-Binding Proteins; D006655:Histone Deacetylases; D008024:Ligands; D009687:Nuclear Proteins; D056971:Nuclear Receptor Co-Repressor 1; D056985:Nuclear Receptor Co-Repressor 2; D018168:Receptors, Retinoic Acid; D011988:Receptors, Thyroid Hormone; D011994:Recombinant Proteins; D012097:Repressor Proteins; D000099186:Histone Deacetylase 3; C539127:NCOR1 protein, human; C539130:NCOR2 protein, human