Geometric variations in nucleosomal DNA dictate higher-order chromatin structure and enhancer-promoter communication.

The dynamic organization of chromatin plays an essential role in the regulation of genetic activity, interconverting between open and compact forms at the global level. The mechanisms underlying these large-scale changes remain a topic of widespread interest. The simulations of nucleosome-decorated DNA reported herein reveal profound effects of the nucleosome itself on overall chromatin properties.

[Opposite Effects of Histone H1 and HMGN5 Protein on Distant Interactions in Chromatin].

Transcriptional enhancers in the cell nuclei typically interact with the target promoters over long stretches of chromatin, but the mechanism of this communication remains unknown. Previously we have developed a defined system for quantitative analysis of the rate of distant enhancer-promoter communication (EPC) and have shown that the chromatin fibers maintain efficient distant EPC . Here we investigate the roles of linker histone H1 and HMGN5 protein in EPC.

Histone Chaperone FACT and Curaxins: Effects on Genome Structure and Function.

The histone chaperone FACT plays important roles in essentially every chromatin-associated process and is an important indirect target of the curaxin class of anti-cancer drugs. Curaxins are aromatiс compounds that intercalate into DNA and can trap FACT in bulk chromatin, thus interfering with its distribution and its functions in cancer cells. Recent studies have provided mechanistic insight into how FACT and curaxins cooperate to promote unfolding of nucleosomes and chromatin fibers, resulting in genome-wide disruption of contact chromatin domain boundaries, perturbation of higher order chromatin organization, and global disregulation of gene expression.

The anti-cancer drugs curaxins target spatial genome organization.

Recently we characterized a class of anti-cancer agents (curaxins) that disturbs DNA/histone interactions within nucleosomes. Here, using a combination of genomic and in vitro approaches, we demonstrate that curaxins strongly affect spatial genome organization and compromise enhancer-promoter communication, which is necessary for the expression of several oncogenes, including MYC. We further show that curaxins selectively inhibit enhancer-regulated transcription of chromatinized templates in cell-free conditions.

Towards quantitative analysis of gene regulation by enhancers.

Enhancers are regulatory DNA sequences that can activate transcription over large distances. Recent studies have revealed the widespread role of distant activation in eukaryotic gene regulation and in the development of various human diseases, including cancer. Here we review recent progress in the field, focusing on new experimental and computational approaches that quantify the role of chromatin structure and dynamics during enhancer-promoter interactions in vitro and in vivo.