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TIF1beta/KAP-1 is a coactivator of the orphan nuclear receptor NGFI-B/Nur77.

Authors: Rambaud, J  Desroches, J  Balsalobre, A  Drouin, J 
Citation: Rambaud J, etal., J Biol Chem. 2009 May 22;284(21):14147-56. doi: 10.1074/jbc.M809023200. Epub 2009 Mar 25.
Pubmed: (View Article at PubMed) PMID:19321449
DOI: Full-text: DOI:10.1074/jbc.M809023200

In efforts to define mechanisms of transcriptional activation by the orphan nuclear receptor NGFI-B (Nur77), we identified TIF1beta by mass spectrometry within a nuclear protein complex containing NGFI-B. TIF1beta, also known as KAP-1 (KRAB domain-associated protein) or KRIP-1, acts as a transcriptional corepressor for many transcription factors, in particular for the Kruppel-associated box domain-containing zinc finger transcription factors. TIF1beta is also an intrinsic component of two chromatin remodeling and histone deacetylase complexes, the N-CoR1 and nucleosome remodeling and deacetylation complexes. In contrast to these activities, we report that TIF1beta is a coactivator of NGFI-B and that it is as potent as the SRC coactivators in this context. Using pull-down assays and immunoprecipitation, we showed that TIF1beta interacts directly with NGFI-B and with other Nur family members. NGFI-B is an important mediator of hypothalamic corticotropin-releasing hormone (CRH) activation of proopiomelanocortin (POMC) transcription, and TIF1beta enhances transcription mediated through the NGFI-B target, the Nur response element (NurRE). The NurRE binds Nur factor dimers and is responsive to signaling pathways. In keeping with the role of NGFI-B as mediator of CRH signaling, we found that TIF1beta is recruited to the POMC promoter following CRH stimulation and that TIF1beta potentiates CRH and protein kinase A signaling through the NurRE; it acts synergistically with the SRC2 coactivator. However, the actions of TIF1beta and SRC2 were mapped to different NGFI-B AF-1 subdomains. Taken together, these results indicate that TIF1beta is an important coactivator of NGFI-B-dependent transcription.

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CRRD Object Information
CRRD ID: 10047236
Created: 2015-07-11
Species: All species
Last Modified: 2015-07-11
Status: ACTIVE



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RGD is funded by grant HL64541 from the National Heart, Lung, and Blood Institute on behalf of the NIH.