Chromatin remodeling by SWI/SNF results in nucleosome mobilization to preferential positions in the rat osteocalcin gene promoter
Biochemistry & Molecular Pharmacology
Graduate School of Biomedical Sciences; Department of Cell Biology
Medical Subject Headings
Animals; Cell Line, Tumor; Chromatin Assembly and Disassembly; Chromosomal Proteins, Non-Histone; Gene Expression Regulation; Nucleosomes; Osteocalcin; Promoter Regions (Genetics); Rats; Transcription Factors
Life Sciences | Medicine and Health Sciences
Changes in local chromatin structure accompany transcriptional activation of eukaryotic genes. In vivo these changes in chromatin organization can be catalyzed by ATP-dependent chromatin-remodeling complexes, such as SWI/SNF. These complexes alter the tight wrapping of DNA in the nucleosomes and can facilitate the mobilization of the histone octamer to adjacent DNA segments, leaving promoter regulatory elements exposed for transcription factor binding. To gain understanding of how the activity of SWI/SNF complexes may be modulated by the different DNA sequences within a natural promoter, we have reconstituted nucleosomes containing promoter segments of the transcriptionally active cell type-specific osteocalcin (OC) gene and determined how they affect the directional movements of the nucleosomes. Our results indicate that SWI/SNF complexes induce octamer sliding to preferential positions in the OC promoter, leading to a nucleosomal organization that resembles that described in intact cells expressing the OC gene. Our studies demonstrate that the position of the histone octamer is primarily determined by sequences within the OC promoter that include or exclude nucleosomes. We propose that these sequences are critical components of the regulatory mechanisms that mediate expression of this tissue-specific gene.
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Citation: J Biol Chem. 2007 Mar 30;282(13):9445-57. Epub 2007 Feb 1. Link to article on publisher's site
Gutierrez, Jose L.; Paredes, Roberto; Cruzat, Fernando; Hill, David A.; Van Wijnen, Andre J.; Lian, Jane B.; Stein, Gary S.; Stein, Janet L.; Imbalzano, Anthony N.; and Montecino, Martin A., "Chromatin remodeling by SWI/SNF results in nucleosome mobilization to preferential positions in the rat osteocalcin gene promoter" (2007). GSBS Student Publications. 461.