Related Experiment Video
Updated: Aug 9, 2026
Prediction and Validation of Gene Regulatory Elements Activated During Retinoic Acid Induced Embryonic Stem Cell Differentiation
Published on: June 21, 2016
The estrogen-responsive B box protein is a novel regulator of the retinoid signal
Belamy B Cheung1, Jessica Bell, Anna Raif
1Children's Cancer Institute Australia for Medical Research, Randwick, New South Wales 2031, Australia.
Abstract:
Retinoic acid (RA) induces growth arrest, cell death, and differentiation in many human cancer cells in vitro and has entered routine clinical use for the treatment of several human cancer types. One mechanism by which cancer cells evade retinoid-induced effects is through repression of retinoic acid receptor beta (RARbeta) gene transcription. The RA response element beta (betaRARE) is the essential DNA sequence required for retinoid-induced RARbeta transcription. Here we show that the estrogen-responsive B box protein (EBBP), a member of the RING-B box-coiled-coil protein family, is a betaRARE-binding protein. EBBP undergoes serine threonine phosphorylation and enhanced protein stability after RA treatment. Following RA treatment, we also observed increased nuclear EBBP levels in aggregates with the promyelocytic leukemia protein at promyelocytic leukemia nuclear bodies. EBBP enhanced RA-responsive RARbeta transcription in RA-sensitive and -resistant cancer cells, which were resistant to both a histone deacetylase inhibitor and a demethylating agent. EBBP-specific small interfering RNA reduced basal and RA-induced RARbeta expression. EBBP increased betaRARE-transactivating function through its coiled-coil domain. Taken together, our work suggests that EBBP may have a pivotal role in the retinoid anti-cancer signal.
Insights
Estrogen-responsive B box protein (EBBP) binds to a key DNA sequence, enhancing retinoic acid (RA) signaling. This protein may play a crucial role in retinoid cancer therapy by boosting anti-cancer effects.
Area of Science:
- Molecular Biology
- Cancer Research
- Cell Signaling
Background:
- Retinoic acid (RA) is used clinically to treat cancers by inducing growth arrest, cell death, and differentiation.
- Cancer cells can evade RA effects by repressing retinoic acid receptor beta (RARbeta) gene transcription.
- The betaRARE DNA sequence is essential for RA-induced RARbeta transcription.
Purpose of the Study:
- To identify proteins that bind to the betaRARE DNA sequence.
- To investigate the role of estrogen-responsive B box protein (EBBP) in RA-mediated gene transcription.
- To explore EBBP's potential as a target for overcoming retinoid resistance in cancer.
Main Methods:
- Electrophoretic mobility shift assays to identify betaRARE-binding proteins.
- Western blotting and immunofluorescence to analyze EBBP expression, localization, and post-translational modifications.
- Small interfering RNA (siRNA) knockdown to assess EBBP's function in RARbeta transcription.
- Reporter gene assays to quantify EBBP's effect on betaRARE-mediated transcription.
Main Results:
- Estrogen-responsive B box protein (EBBP) was identified as a betaRARE-binding protein.
- RA treatment induced EBBP phosphorylation, enhanced protein stability, and increased nuclear EBBP levels, often in association with promyelocytic leukemia protein nuclear bodies.
- EBBP significantly enhanced RA-responsive RARbeta transcription in both RA-sensitive and RA-resistant cancer cells.
- EBBP-specific siRNA reduced both basal and RA-induced RARbeta expression, confirming EBBP's role in regulating RARbeta.
- EBBP's coiled-coil domain was found to be critical for its transactivating function on betaRARE.
Conclusions:
- Estrogen-responsive B box protein (EBBP) is a key regulator of retinoic acid receptor beta (RARbeta) transcription.
- EBBP enhances retinoid signaling by binding to the betaRARE and promoting RARbeta expression, even in resistant cancer cells.
- EBBP represents a potential therapeutic target for improving the efficacy of retinoid-based cancer treatments.
Related Concept Videos
01:31Transducer Mechanism: Nuclear Receptors
About 48 different soluble family members of nuclear receptors are identified that can be divided into two main classes:
01:23Negative Regulator Molecules
01:20The Retinoblastoma Gene
The first-ever tumor suppressor gene called Rb was identified in retinoblastoma - a rare eye tumor in children. In inherited forms of the disease, a child inherits one defective copy of the Rb gene, which predisposes them to retinoblastoma. However,...
01:20The Retinoblastoma Gene
The first-ever tumor suppressor gene called Rb was identified in retinoblastoma - a rare eye tumor in children. In inherited forms of the disease, a child inherits one defective copy of the Rb gene, which predisposes them to retinoblastoma. However,...
01:45Regulation of Nuclear Protein Sorting
01:15Receptor Downregulation in MVBs
The EGFR can initiate signaling pathways that lead to cell proliferation, migration, and differentiation. Overexpression of EGFR stimulates cells to proliferate. Excessive EGFR activation may...