tailieunhanh - Báo cáo khoa học: Structure and function of active chromatin and DNase I hypersensitive sites

Chromatin is by its very nature a repressive environment which restricts the recruitment of transcription factors and acts as a barrier to polymerases. Therefore the complex process of gene activation must operate at two levels. In the first instance, localized chromatin decondensation and nucleosome displacement is required to make DNA accessible. | IFEBS Journal MINIREVIEW Structure and function of active chromatin and DNase I hypersensitive sites Peter N. Cockerill ExperimentalHaematology Leeds Institute of Molecular Medicine University of Leeds UK Keywords chromatin DNase I hypersensitive gene regulation nucleosome transcription Correspondence P. N. Cockerill ExperimentalHaematology Leeds Institute of Molecular Medicine University of Leeds Wellcome Trust Brenner Building St James s University Hospital Leeds LS9 7TF UK Fax 44 113 343 8502 Tel 44 113 343 8639 E-mail Chromatin is by its very nature a repressive environment which restricts the recruitment of transcription factors and acts as a barrier to polymerases. Therefore the complex process of gene activation must operate at two levels. In the first instance localized chromatin decondensation and nucleosome displacement is required to make DNA accessible. Second sequence-specific transcription factors need to recruit chromatin modifiers and remodellers to create a chromatin environment that permits the passage of polymerases. In this review I will discuss the chromatin structural changes that occur at active gene loci and at regulatory elements that exist as DNase I hypersensitive sites. Received 18 December 2010 revised 10 February 2011 accepted 5 April 2011 doi Introduction Our current understanding of chromatin structure really began in the 1970s when it was demonstrated that chromatin was built up from nucleosomes 1 2 and it was found that histones could be acetylated 3 . In the late 1970s and early 1980s it was then recognized that chromatin structure was likely to play a significant role in gene regulation. It was discovered that a histone acetylation is enriched in active genes 4 b active genes adopt a more accessible chromatin conformation 5-7 and c gene regulatory elements are associated with nucleosome-free regions that came to be known as DNase I hypersensitive sites DHSs 7-10 . This .

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