Project description:Using the Fucci cell cycle indicator system in hESCs, we evaluated the patterns of bivalent histone marks and enhancer histone marks during the cell cycle by ChIP-seq. We further evaluated how the chromatin architecture changed during the cell cycle. We found that bivalent domains are cell cycle regulated, and H3K4me3 specifically peaks during the late G1 stage of the cell cycle. H3K27me3, however, is largely unchanged during the cell cycle. Cell cycle-regulated bivalent domains interact with enhancers and form cell cycle regulated chromatin interactions. FACS-isolated cell cycle fractions (DN, early G1; KO2, late G1; AzL, S-phase; and AzH, G2/M) from Fucci hESCs were subject to ChIP-seq for H3K4me3, H3K27me3, H3K27ac and H3K4me1, and used for sequencing along with input controls for each of the 4 cell cycle fractions (20 samples total), using Illumina platform, or 4C-seq for each cell cycle fraction using viewpoints neighboring the GATA6 or SOX17 promoters.
Project description:Using the Fucci cell cycle indicator system in hESCs, we evaluated the patterns of bivalent histone marks and enhancer histone marks during the cell cycle by ChIP-seq. We further evaluated how the chromatin architecture changed during the cell cycle. We found that bivalent domains are cell cycle regulated, and H3K4me3 specifically peaks during the late G1 stage of the cell cycle. H3K27me3, however, is largely unchanged during the cell cycle. Cell cycle-regulated bivalent domains interact with enhancers and form cell cycle regulated chromatin interactions.
Project description:HUVEC-FUCCI cells were used to demonstrate that different endothelial cell cycle states provide distict windows of opportunity for gene expression in response to extrinsic signals. HUVEC-FUCCI were FACS-isolated into three different cell cycle states. Peptide digests from the resulting lysates showed differentially expressed proteins among the three cell cycles. These studies show that endothelial cell cycle state determines the propensity for arterial vs. venous fate specification.
Project description:Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-cardiomyocytes) are promising sources for the regenerative therapy to treat heart failure. To realize this therapy, the engraftment potential of hiPSC-cardiomyocytes following the injection into the host heart should be improved. Here, we established the efficient method to analyze the cell cycle activity of hiPSC-cardiomyocytes using Fluorescence Ubiquitination-based Cell Cycle Indicator (FUCCI) system. High-throughput screening analysis using FUCCI-expressing hiPSC-cardiomyocytes identified a retinoic acid receptor (RAR) agonist, Am80, as an effective cell cycle activator in hiPSC-cardiomyocytes. The transplantation of hiPSC-cardiomyocytes treated by Am80 prior to the injection significantly enhanced the engraftment into the damaged mouse heart for 6 months. RNA sequencing analysis in Am80-treated iPSC-cardiomyocytes revealed that both RARA and RARB played important roles in the Am80-mediated cell cycle activation in hiPSC-cardiomyocytes. Collectively, this study highlights the effectiveness of FUCCI system to easily analyze the cell cycle status in hiPSC-cardiomyocytes and the cell cycle activation by Am80 is the possible strategy to increase the graft size following the cell transplantation into the damaged heart.
Project description:We report the acetylation of lysine residues in the globular domain of H3 (H3K64ac and H3K122ac) marks active gene promoters and also a subset of active enhancers in mouse embryonic stem cells (mESCs), human erythroleukemic cell line (K562). Moreover, we find a novel class of active functional enhancers in ESCs that are marked by H3K122ac but which lack H3K27ac. This work suggests that a more complex analysis of histone acetylation is required to identify enhancers than was previously considered. Examination of histone modifications in mouse ESCs (2 biological replicates) and K562 cells
Project description:Epigenetic states defined by chromatin can be maintained through mitotic cell division. However, it remains unknown how histone-based information is transmitted. Here we combine nascent chromatin capture (NCC) and triple-SILAC labelling to track histone modifications and histone variants during DNA replication and across the cell cycle. We show that post-translational modifications (PTMs) are transmitted with parental histones to newly replicated DNA. Di- and tri-methylation marks are diluted two-fold upon DNA replication, as a consequence of new histone deposition. Importantly, within one cell cycle all PTMs are restored. In general, new histones are modified to mirror the parental histones. However, H3K9me3 and H3K27me3 are propagated by continuous modification of parental and new histones, because the establishment of these marks extends over several cell generations. Together, our results reveal how histone marks propagate and demonstrate that chromatin states oscillate within the cell cycle.
Project description:Heterogeneity in pluripotent cells marks a metastable state where cells may drift between native and lineage-primed populations. While the role for these heterogeneities are unclear, they may reflect the dynamic equilibriums of signaling networks and have a direct effect on differentiation potentialities. Here, we report the role of the cell cycle in establishing heterogeneity of human pluripotent stem cells. By utilizing the FUCCI cell cycle indicator system coupled to fluorescent activated cell sorting (FACS), we have uncovered that the cell cycle drives heterogeneity at the epigenetic, transcriptional and post-transcriptional levels. Our data show widespread dynamics in 5-hydroxymethylcytosine (5hmC) during the cell cycle. Furthermore, transcript profiling by RNA-sequencing identified >500 genes that were cell cycle-regulated, of which the largest cohort of genes were transcriptional regulators. In sum, we demonstrate the role of the cell cycle in coordinating cellular transitions between metastable states in pluripotent stem cells. mRNA sequencing of the cell cycle phases; early & late G1, S and G2/S from human ES cells in triplicate.
Project description:Heterogeneity in pluripotent cells marks a metastable state where cells may drift between native and lineage-primed populations. While the role for these heterogeneities are unclear, they may reflect the dynamic equilibriums of signaling networks and have a direct effect on differentiation potentialities. Here, we report the role of the cell cycle in establishing heterogeneity of human pluripotent stem cells. By utilizing the FUCCI cell cycle indicator system coupled to fluorescent activated cell sorting (FACS), we have uncovered that the cell cycle drives heterogeneity at the epigenetic, transcriptional and post-transcriptional levels. Our data show widespread dynamics in 5-hydroxymethylcytosine (5hmC) during the cell cycle. Furthermore, transcript profiling by RNA-sequencing identified >500 genes that were cell cycle-regulated, of which the largest cohort of genes were transcriptional regulators. In sum, we demonstrate the role of the cell cycle in coordinating cellular transitions between metastable states in pluripotent stem cells.
Project description:Pervasive phosphorylation of histone H3 at serine 10 (H3S10ph) by Aurora B/C plays an important role in mitosis; however, this mark has also been observed at specific genic promoters and enhancers in interphase, implicating mitosis-independent functions. Using the FUCCI cell cycle reporter, we found that 30% of the genome is persistently marked with H3S10ph in interphase mouse embryonic stem cells (ESCs). H3S10ph demarcates broad gene-rich euchromatic regions in G1 and shows remarkable correlation with domains of early DNA replication timing (RT). Consistent with mitosis-independent H3S10 kinase activity, this pattern was preserved in ESCs treated with hesperidin, a potent inhibitor of Aurora B/C. Disruption of H3S10ph by expression of non-phosphorylatable H3.3S10A results in ectopic spreading of H3K9me2 into adjacent H3S10ph-enriched euchromatic regions, mimicking the phenotype observed in Drosophila JIL-1 kinase mutants. Conversely, H3S10ph domains expand in interphase Glp-/- ESCs, revealing that H3S10ph expansion is restricted by H3K9me2. Strikingly, spreading of H3S10ph at RT transition regions (TTRs) is accompanied by aberrant strand-biased transcription initiation of genes and repetitive elements co-oriented with the replication fork, indicating that H3K9me2 plays a critical role in establishing repressive chromatin on the leading strand. Finally, we show that H3S10ph is also present in interphase murine embryonic fibroblasts (MEFs), but is restricted to intragenic regions of actively transcribing genes. Our study provides a detailed map of interphase H3S10ph in ESCs and MEFs, uncovering a previously unappreciated crosstalk between the opposing marks H3S10ph and H3K9me2, and a role for the latter in ensuring appropriate transcription at TTRs in ESCs.
Project description:Progression through the cell cycle is driven by cyclin dependent kinases that control gene expression, orchestration of the mitotic spindle and cell division. Here we used a Fluorescent Ubiquitination-based Cell Cycle Indicator (FUCCI) and performed transcriptomic analysis of human non-transformed cells. Cell sorting allowed efficient isolation of G1, S and G2 cells from asynchronously growing cell cultures. Altogether, we identified 701 differentially expressed genes in G1 and G2 cells.