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BRCA1 splice variants BRCA1a and BRCA1b associate with CBP co-activator
1Division of Cancer Genetics, Department of Human Genetics, Allegheny University of the Health Sciences, M.S. 481, New College Building, Broad and Vine Streets, Philadelphia, PA 19102, USA.
Oncology Reports
|May 9, 1998
Summary
The tumor suppressor BRCA1 protein interacts with transcription factor CBP, suggesting a mechanism for gene regulation. This interaction recruits CBP
Area of Science:
- Molecular Biology
- Cancer Research
- Gene Regulation
Background:
- BRCA1 is a crucial tumor suppressor gene.
- BRCA1 functions as a nuclear phosphoprotein associated with RNA polymerase II holoenzyme.
- CBP (CREB-binding protein) is a known component of the RNA polymerase II holoenzyme.
Purpose of the Study:
- To investigate the interaction between BRCA1 splice variants (BRCA1a/p110 and BRCA1b/p100) and the transcription factor CBP.
- To elucidate the functional consequences of this interaction in gene regulation.
Main Methods:
- Mammalian two-hybrid assays to detect in vivo interactions.
- Co-immunoprecipitation and Western blot studies for protein complex validation.
- GST binding assays for in vitro interaction analysis.
- Histone acetyl transferase (HAT) assays on BRCA1 immunoprecipitates.
Main Results:
- The carboxy-terminal domain of CBP interacts with full-length BRCA1a and BRCA1b proteins both in vivo and in vitro.
- BRCA1 immunoprecipitates from human breast cancer cells exhibit HAT activity.
- Evidence suggests CBP-associated HAT/FAT activity is recruited by BRCA1 proteins.
Conclusions:
- BRCA1 proteins may function by recruiting CBP-associated HAT/FAT activity.
- This recruitment facilitates the acetylation of BRCA1 proteins, general transcription factors, or both.
- Acetylation of target molecules at specific promoters likely results in transcriptional activation, contributing to BRCA1's tumor suppressor function.