Project description:Full pluripotency of induced pluripotent stem (iPS) cells has been determined as viable all-iPS mice can be generated through tetraploid complementation. Subsequently, activation of imprinted Dlk-Dio3 gene cluster has been suggested to correlate with the pluripotency of iPS cells1. However, evidence from recent studies has demonstrated that loss of imprinting at the Dlk-Dio3 locus did not correlate strictly with the reduced pluripotency of iPS cells. Therefore, it becomes indispensable to exploit other reliable molecular markers for evaluating the quality of iPS cells accurately. In the present study, we successfully utilize the sequential reprogramming approach and produce all-iPS mice to six generations using iPS cell lines derived from different cell lineages which contain the same proviral integration in the genome. By comparing the global gene expression and epigenetic modifications of both “tetra-on” and corresponding “tetra-off” iPS cell lines established from either mesenchymal or hematopoietic lineages through deep sequencing analysis of mRNA expression, small RNA profiling, histone modifications (H3K4m2, H3K4me3 and H3K27me3) and DNA methylation, very few differences are detected among all the iPS cell lines investigated. However, we find that two imprinted genes, disruption of which correlate with the reduced pluripotency of iPS cells. Therefore, our data not only provide the first demonstration that producing of all-iPS mice to six generations is feasible, but reveal that two imprinted regions can be served as pluripotency markers of iPS cells Examination of the expression small RNA in 13 cell types
Project description:Dynamic changes in histone posttranslational modifications (PTMs) are important regulators of chromatin structure and gene transcription in both normal and disease settings. Herein, we describe a novel signaling mechanism of nitric oxide (â?¢NO) by demonstrating its ability to modulate gene expression via alteration of histone PTMs. Having established that â?¢NO exposure induced differential expression of approximately 6500 genes, we set out to determine if there was an epigenetic component to their regulation. â?¢NO exposure led to alterations in the global levels of acetyl and methyl modifications at numerous lysine residues on core histones H3 and H4. Residues H3K9me2/ac were examined further and determined to have differential distribution at various loci throughout the genome in response to â?¢NO. Changes in the enrichment levels of H3K9me2/ac at specific genes correlated with changes in the expression levels of their transcripts. Molecular mechanisms contributing to phenotypic outcomes in â?¢NO-associated cancers remain to be well understood since traditional modes of â?¢NO-signaling do not explain a large proportion of its impact on tumor cell behavior. Our results reveal that â?¢NO drives a significant amount of gene expression changes epigenetically by changing the distribution of numerous histone marks. Cultured cells were treated with 500uM DETA/NO to examine the effects of a physiologically relevant â?¢NO concentration on gene expression. A total of two untreated biological replicates and two â?¢NO-treated biological replicates were harvested. The untreated samples served as control against which comparisons were made to elucidate â?¢NO-mediated changes in the gene expression.
Project description:Obesity is a highly heritable complex disease that results from the interaction of multiple genetic and environmental factors. Formerly obese individuals are susceptible to metabolic disorders later in life, even after lifestyle changes are made to mitigate the obese state. This is reminiscent of the metabolic memory phenomenon originally observed for persistent complications in diabetic patients, despite subsequent glycemic control. Epigenetic modifications represent a potential mediator of this observed memory. We previously demonstrated that a high fat (HF) diet leads to changes in chromatin accessibility in the mouse liver. The regions of greatest chromatin changes in accessibility are largely strain dependent, indicating a genetic component in diet-induced chromatin alterations. We have now examined the persistence of diet-induced chromatin accessibility changes upon diet reversal in two strains of mice. We find that a substantial fraction of loci that undergo chromatin accessibility changes with HF diet remain in the remodeled state after diet reversal in C57BL/6J mice. In contrast, the vast majority of diet-induced chromatin accessibility changes in A/J mice are transient. Our data also indicate that the persistent chromatin accessibility changes observed in C57BL/6J are associated with specific transcription factors and histone posttranslational modifications. The persistent loci identified here are likely to be contributing to the overall phenotype and are attractive targets for therapeutic intervention. Examination of chromatin remodeling with FAIRE-seq in livers of C57BL/6J and A/J mice on three diet regimen: 1) control diet for 16 weeks, 2) high fat diet for 16 weeks, or 3) high fat diet for 8 weeks with control diet for 8 weeks. These chromatin profiles were complemented with gene expression data (RNA-seq)
Project description:Dynamic changes in histone posttranslational modifications (PTMs) are important regulators of chromatin structure and gene transcription in both normal and disease settings. Herein, we describe a novel signaling mechanism of nitric oxide (â¢NO) by demonstrating its ability to modulate gene expression via alteration of histone PTMs. Having established that â¢NO exposure induced differential expression of approximately 6500 genes, we set out to determine if there was an epigenetic component to their regulation. â¢NO exposure led to alterations in the global levels of acetyl and methyl modifications at numerous lysine residues on core histones H3 and H4. Residues H3K9me2/ac were examined further and determined to have differential distribution at various loci throughout the genome in response to â¢NO. Changes in the enrichment levels of H3K9me2/ac at specific genes correlated with changes in the expression levels of their transcripts. Molecular mechanisms contributing to phenotypic outcomes in â¢NO-associated cancers remain to be well understood since traditional modes of â¢NO-signaling do not explain a large proportion of its impact on tumor cell behavior. Our results reveal that â¢NO drives a significant amount of gene expression changes epigenetically by changing the distribution of numerous histone marks. Cultured cells were treated with 500uM DETA/NO to examine the effects of a physiologically relevant â¢NO concentration on differential distribution of H3K9ac/H3K9me2. A total of two untreated biological replicates and two â¢NO-treated biological replicates were harvested. The untreated samples served as control against which comparisons were made to elucidate â¢NO-mediated changes in the histone landscape.
Project description:We report histone modifications in alveolar epithelial type 2 cells in homeostatic mice as well as CTGF-positive alveolar eptihelial cells in mice treated with Bleomycin.
Project description:Spt6 is a highly conserved histone chaperone that interacts directly with both RNA polymerase II and histones to regulate gene expression. To gain a comprehensive understanding of the requirements for this critical factor, we have performed genome-wide analyses of transcription, chromatin structure, and histone modifications in an S. pombe spt6 mutant. Our results demonstrate several dramatic changes to transcription and chromatin structure in the spt6 mutant, including an elevation of antisense transcripts at over 70 percent of all genes and general loss of the +1 nucleosome. Furthermore, Spt6 is required for the trimethylation of histone H3 on lysines 4 and 36, marks associated with active transcription. Taken together, our results indicate that Spt6 is critical for the accuracy of transcription and the integrity of chromatin, likely via its direct interactions with RNA polymerase II and histones. ChIP-seq experiments were performed on wild type and spt6-1 strains on the following proteins: RNA polymerase II (Rpb1), Paf1 Complex (Ctr9), COMPASS (Swd1), Set2, Spt6, histones H2B and H3, histone modifications H3K4me3 and H3K36me3. Experiments were performed in replicates and matching inputs were also sequenced.