Regulation of SMRT corepressor dimerization and composition by MAP kinase phosphorylation.
The SMRT (Silencing Mediator of Retinoid and Thyroid hormone receptors) corepressor mediates gene repression by nuclear receptors and other transcriptional factors. The SMRT protein serves as a key nucleating core that organizes the assembly of a larger corepressor complex. We report here that SMRT interacts with itself to form a protein dimer, and that Erk2, a mitogen-activated protein (MAP) kinase, disrupts this SMRT self-dimerization in vitro and in vivo. Notably Erk2 phosphorylation also results in a re-organization of the overall corepressor complex, characterized by a reduced sedimentation coefficient, partial release of HDAC3, TBL-1, and TBLR-1, and inhibition of transcriptional repression. We propose that SMRT dimers form the central platform on which additional corepressor components assemble, and that kinase signaling modifies the architecture, composition, and function of this complex. These observations contribute to our understanding of how the SMRT corepressor complex assembles and is regulated during cell proliferation and differentiation.
Department of Microbiology, College of Biological Sciences, University of California at Davis, United States.
Natalia
N
Varlakhanova
Johnnie B
JB
Hahm
Martin L
ML
Privalsky
D000818:Animals; D019281:Dimerization; D006801:Humans; D019950:Mitogen-Activated Protein Kinase 1 / Q000235:genetics / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D046912:Multiprotein Complexes / Q000737:chemistry / Q000378:metabolism; D056985:Nuclear Receptor Co-Repressor 2 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D020836:Protein Structure, Quaternary; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction
D046912:Multiprotein Complexes; D056985:Nuclear Receptor Co-Repressor 2; D011993:Recombinant Fusion Proteins; D019950:Mitogen-Activated Protein Kinase 1; D020928:Mitogen-Activated Protein Kinases