Chromatin Regulation of Estrogen-Mediated Transcription in Breast Cancer: Rules for Binding Sites in Nucleosomes and Modified Histones that Enhance ER Binding
Abstract
Binding of ER to estrogen-regulated promoters has been extensively characterized in assays that utilize naked DNA as a template. In contrast, the factors that allow binding of the ER to the estrogen response element (ERE) within the context of chromatin e.g. within a nucleosome, are largely unknown. To investigate this process, we have reconstituted nucleosomes that contain an ERE located at different translational positions e,g, center, side or edge. Using gel shift assays, we tested whether ER can bind these nucleosomes. We have also found that the non-histone chromatin protein HMOB2 enhances binding of ER to an ERE located at the center of the nucleosome. We determine whether HMGB2 facilitates binding of ER to ERE located at other positions. The results of these studies indicate: 1.) ER binding to the nucleosome is dependent on the location of the ERE. Binding at the edge is better than at the center or side. 2.) Binding of ER is enhanced by HMGB2 regardless of the position of the ERE and at each position, HMGB2-ER-nucleosome complexes can be detected. 3.) Binding of recombinant ER to ERE sites within the nucleosome was greatly reduced compared to ER obtained from nuclear extracts. This suggests that additional proteins contribute to the ability of ER to bind nucleosomes.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 2005
- Accession Number
- ADA443200
Entities
People
- John C. Chrivia
Organizations
- Saint Louis University