Comparative Analyses of H3K4 and H3K27 Trimethylations Between the Mouse Cerebrum and Testis

AbstractThe global features of H3K4 and H3K27 trimethylations (H3K4me3 and H3K27me3) have been well studied in recent years, but most of these studies were performed in mammalian cell lines. In this work, we generated the genome-wide maps of H3K4me3 and H3K27me3 of mouse cerebrum and testis using ChIP-seq and their high-coverage transcriptomes using ribominus RNA-seq with SOLiD technology. We examined the global patterns of H3K4me3 and H3K27me3 in both tissues and found that modifications are closely-associated with tissue-specific expression, function and development. Moreover, we revealed that H3K4me3 and H3K27me3 rarely occur in silent genes, which contradicts the findings in previous studies. Finally, we observed that bivalent domains, with both H3K4me3 and H3K27me3, existed ubiquitously in both tissues and demonstrated an invariable preference for the regulation of developmentally-related genes. However, the bivalent domains tend towards a “winner-takes-all” approach to regulate the expression of associated genes. We also verified the above results in mouse ES cells. As expected, the results in ES cells are consistent with those in cerebrum and testis. In conclusion, we present two very important findings. One is that H3K4me3 and H3K27me3 rarely occur in silent genes. The other is that bivalent domains may adopt a “winner-takes-all” principle to regulate gene expression

The Disequilibrium of Nucleosomes Distribution along Chromosomes Plays a Functional and Evolutionarily Role in Regulating Gene Expression

To further understand the relationship between nucleosome-space occupancy (NO) and global transcriptional activity in mammals, we acquired a set of genome-wide nucleosome distribution and transcriptome data from the mouse cerebrum and testis based on ChIP (H3)-seq and RNA-seq, respectively. We identified a nearly consistent NO patterns among three mouse tissues—cerebrum, testis, and ESCs—and found, through clustering analysis for transcriptional activation, that the NO variations among chromosomes are closely associated with distinct expression levels between house-keeping (HK) genes and tissue-specific (TS) genes. Both TS and HK genes form clusters albeit the obvious majority. This feature implies that NO patterns, i.e. nucleosome binding and clustering, are coupled with gene clustering that may be functionally and evolutionarily conserved in regulating gene expression among different cell types

Selective loading of 5-fluorouracil in the interlayer space of methoxy-modified kaolinite for controlled release

Methoxy-modified kaolinite was used as a novel carrier for anticancer drug 5-fluorouracil (5FU). The selective loading of 5FU into the interlayer space of methoxy-modified kaolinite was achieved because the weakly bonded 5FU on the external surface was removed off by facile water rinse. The intercalated 5FU has strong affinity (electrostatic force and hydrogen bonding) with the interlayer surface of kaolinite, and its release was controlled because of the diffusion restriction of the kaolinite lamellar layers and the strong affinity between 5FU and kaolinite. The controlled release of 5FU from methoxy-modified kaolinite in simulated colonic fluid (pH 5.5) makes it be of potential use to administer an oral formulation of 5FU for colon specific delivery