engleski

Histone modifications and transcriptional regulation

Histones undergo a significant number of posttranslational modifications that result in altered patterns of histone‐DNA interactions and, ultimately, change the accessibility of DNA molecule. Extensive studies of several histone modifications revealed their correlation with gene expression or silencing. However, the quantity and extent of the actual contribution to transcription regulation remains unclear. The emerging large quantity of histone modification data originating from high‐throughput experiments such as ChIP‐on‐Chip and ChIP‐Seq serves as a valuable source of information for studying these phenomena with sufficient detail. The fact that multiple histone modifications can co‐exist on a single histone tail has led to the postulation of the 'histone code' hypothesis, which presumes that different histone modifications, on one or more tails, act in a combinatorial or sequential way to bring about different transcriptional outcomes. Furthermore, recent studies show that human promoters exibit mostly a bimodal distribution with either high (HCP) or low (LCP) CpG content and with different types and levels of histone modifications specific to each CpG‐content class. This review focuses on recent studies that investigate the combinatorial nature of histone modifications and its impact on gene regulation, with special attention paid to the effect of CpG‐content‐specific histone modification patterns of different promoter classes on gene expression levels.

histone modifications; transcription

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