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Distinct steady-state nuclear receptor coregulator complexes exist in vivo
N J McKenna1, Z Nawaz, S Y Tsai
1Department of Cell Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA.
Summary
Nuclear receptor coregulators form distinct complexes in vivo. These preformed subcomplexes may assemble into larger structures for transcriptional regulation by activated nuclear receptors.
Area of Science:
- Molecular Biology
- Gene Regulation
- Biochemistry
Background:
- Transcriptional regulation by nuclear hormone receptors involves coregulators.
- Coregulator subclasses include SRC-1, p300/CBP, SWI/SNF proteins, and E3 ubiquitin-protein ligases.
- Evidence suggests coregulators may form higher-order complexes.
Purpose of the Study:
- To analyze steady-state complexes of different coregulator subclasses in vivo.
- To investigate the in vivo assembly of nuclear receptor coregulator complexes.
Main Methods:
- Biochemical fractionation of T47D and HeLa cell lysates.
- Immunoblotting using coregulator-specific antibodies.
- Analysis of in vivo coregulator complex formation.
Main Results:
- Different coregulator subclasses exhibit distinct fractionation profiles.
- SRC-1 family members can form heteromultimeric complexes in vivo.
- Liganded progesterone receptor (PR) forms stable complexes with SRC-1 and transcription intermediary factor 2 (TIF2) in vivo.
Conclusions:
- Nuclear receptor coregulators exist as distinct subcomplexes in vivo.
- Preformed coregulator subcomplexes likely assemble into larger modular structures.
- This assembly mechanism is involved in transcriptional regulation by activated nuclear receptors.