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Updated: Mar 19, 2026

Studying TGF-β Signaling and TGF-β-induced Epithelial-to-mesenchymal Transition in Breast Cancer and Normal Cells
Published on: October 27, 2020
Tumor suppressor bromodomain-containing protein 7 cooperates with Smads to promote transforming growth factor-β
Ting Liu1,2, Meiling Zhao1, Jinquan Liu1
1Life Sciences Institute and Innovation Center for Cell Signaling Network, Zhejiang University, Hangzhou, Zhejiang 310058, China.
Abstract:
Smad proteins are central mediators in the canonical transforming growth factor-β (TGF-β) signaling pathway in mammalian cells. We report here that bromodomain-containing protein 7 (BRD7) functions as a novel transcription coactivator for Smads in TGF-β signaling. BRD7 forms a TGF-β inducible complex with Smad3/4 through its N-terminal Smad-binding domain. BRD7 simultaneously binds to acetylated histones to promote Smad-chromatin association, and associates with histone acetyltransferase p300 to enhance Smad transcriptional activity. Ectopic expression of BRD7, but not its mutants defective in Smad binding, enhances TGF-β transcriptional, tumor-suppressing and epithelial-mesenchymal transition responses. Conversely, depletion of BRD7 inhibits TGF-β responses. Thus, our study provides compelling evidence for a new function of BRD7 in fine-tuning TGF-β physiological responses.
Insights
Bromodomain-containing protein 7 (BRD7) acts as a novel coactivator for Smad proteins in transforming growth factor-β (TGF-β) signaling. BRD7 enhances TGF-β-mediated gene transcription and cellular responses, highlighting its role in TGF-β pathway regulation.
Area of Science:
- Cellular biology
- Molecular signaling
- Cancer research
Background:
- Smad proteins are key mediators of the transforming growth factor-β (TGF-β) signaling pathway.
- TGF-β signaling regulates crucial cellular processes including proliferation, differentiation, and apoptosis.
- Dysregulation of TGF-β signaling is implicated in various diseases, including cancer.
Purpose of the Study:
- To investigate the novel function of bromodomain-containing protein 7 (BRD7) in TGF-β signaling.
- To elucidate the mechanism by which BRD7 interacts with Smad proteins and influences their transcriptional activity.
- To determine the role of BRD7 in TGF-β-mediated cellular responses, such as tumor suppression and epithelial-mesenchymal transition.
Main Methods:
- Co-immunoprecipitation assays to detect protein complex formation between BRD7 and Smad proteins.
- Chromatin immunoprecipitation (ChIP) to assess Smad-chromatin association.
- Western blotting and quantitative real-time PCR to analyze gene expression and protein levels.
- Functional assays including cell proliferation, migration, and apoptosis assays.
Main Results:
- BRD7 forms a TGF-β-inducible complex with Smad3/4 via its N-terminal Smad-binding domain.
- BRD7 binds to acetylated histones and interacts with p300, a histone acetyltransferase, to enhance Smad transcriptional activity.
- Ectopic expression of BRD7 potentiates TGF-β-induced transcriptional responses, tumor suppression, and epithelial-mesenchymal transition.
- Depletion of BRD7 impairs TGF-β signaling pathway activity and its downstream cellular effects.
Conclusions:
- BRD7 functions as a novel transcription coactivator for Smad proteins in the canonical TGF-β signaling pathway.
- BRD7 integrates Smad signaling with epigenetic machinery by interacting with acetylated histones and p300.
- BRD7 plays a critical role in mediating TGF-β-dependent physiological responses, including tumor suppression and epithelial-mesenchymal transition, making it a potential therapeutic target.
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