Tuyển tập các báo cáo nghiên cứu về y học được đăng trên tạp chí y học Wertheim cung cấp cho các bạn kiến thức về ngành y đề tài: Nucleosome rotational setting is associated with transcriptional regulation in promoters of tissue-specific human genes. | Hebert and Roest Crollius Genome Biology 2010 11 R51 http 2010 11 5 R51 w Genome Biology RESEARCH _ Open Access Nucleosome rotational setting is associated with transcriptional regulation in promoters of tissue-specific human genes Charles Hebert and Hugues Roest Crollius Abstract Background The position of a nucleosome both translational along the DNA molecule and rotational between the histone core and the DNA is controlled by many factors including the regular occurrence of specific dinucleotides with a period of approximately 10 bp important for the rotational setting of the DNA around the histone octamer. Results We show that such a 10 bp periodic signal of purine-purine dinucleotides occurs in phase with the transcription start site TSS of human genes and is centered on the position of the first 1 nucleosome downstream of the TSS. These data support a direct link between transcription and the rotational setting of the nucleosome. The periodic signal is most prevalent in genes that contain CpG islands that are expressed at low levels in a tissue-specific manner and are involved in the control of transcription. Conclusions These results together with several lines of evidence from the recent literature support a new model whereby the 1 nucleosome could be more efficiently disassembled from gene promoters by H3K56 acetylation marks if the periodic signal specifies an optimal rotational setting. Background Nucleosomes composed of 147 bp of DNA wrapped around a histone octamer play a fundamental role of compacting DNA molecules inside the nucleus of eukaryotic cells 1 but also in the regulation of gene expression 2 3 . Elucidating the molecular mechanisms that specify the position of nucleosomes in a genome is important to understand their role at the crossroads of essential cellular functions. Factors influencing nucleosome positioning likely include DNA sequence-based information either to specify a favorable or unfavorable DNA structure or to
