3D chromatin organization changes modulate adipogenesis and osteogenesis [RNA-seq]
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ABSTRACT: Human mesenchymal stem cells (hMSCs) can be differentiated into adipocytes and osteoblasts. While the transcriptomic and epigenomic changes during adipogenesis and osteogenesis have been characterized, what happens to the chromatin loops is hardly known. Here we induced hMSCs to adipogenic and osteogenic differentiation, and performed 2 kb resolution Hi-C experiments for loop detection and generated RNA-seq, histone modification ChIP-seq and ATAC-seq data for integrative analysis before and after differentiation. We quantitatively identified differential contact loops and unique loops. After integrating with multi-omics data, we demonstrate that strengthened loops after differentiation are associated with gene expression activation. Specially, unique loops are linked with cell fate determination. We also proposed loop-mediated regulatory networks and identified IRS2 and RUNX2 as being activated by cell-specific loops to facilitate adipocytes and osteoblasts commitment, respectively. These results are expected to help better understand the long-range regulation in controlling hMSC differentiation, and provide novel targets for studying adipocytes and osteoblasts determination.
Project description:Human mesenchymal stem cells (hMSCs) can be differentiated into adipocytes and osteoblasts. While the transcriptomic and epigenomic changes during adipogenesis and osteogenesis have been characterized, what happens to the chromatin loops is hardly known. Here we induced hMSCs to adipogenic and osteogenic differentiation, and performed 2 kb resolution Hi-C experiments for loop detection and generated RNA-seq, histone modification ChIP-seq and ATAC-seq data for integrative analysis before and after differentiation. We quantitatively identified differential contact loops and unique loops. After integrating with multi-omics data, we demonstrate that strengthened loops after differentiation are associated with gene expression activation. Specially, unique loops are linked with cell fate determination. We also proposed loop-mediated regulatory networks and identified IRS2 and RUNX2 as being activated by cell-specific loops to facilitate adipocytes and osteoblasts commitment, respectively. These results are expected to help better understand the long-range regulation in controlling hMSC differentiation, and provide novel targets for studying adipocytes and osteoblasts determination.
Project description:Human mesenchymal stem cells (hMSCs) can be differentiated into adipocytes and osteoblasts. While the transcriptomic and epigenomic changes during adipogenesis and osteogenesis have been characterized, what happens to the chromatin loops is hardly known. Here we induced hMSCs to adipogenic and osteogenic differentiation, and performed 2 kb resolution Hi-C experiments for loop detection and generated RNA-seq, histone modification ChIP-seq and ATAC-seq data for integrative analysis before and after differentiation. We quantitatively identified differential contact loops and unique loops. After integrating with multi-omics data, we demonstrate that strengthened loops after differentiation are associated with gene expression activation. Specially, unique loops are linked with cell fate determination. We also proposed loop-mediated regulatory networks and identified IRS2 and RUNX2 as being activated by cell-specific loops to facilitate adipocytes and osteoblasts commitment, respectively. These results are expected to help better understand the long-range regulation in controlling hMSC differentiation, and provide novel targets for studying adipocytes and osteoblasts determination.
Project description:Human mesenchymal stem cells (hMSCs) can be differentiated into adipocytes and osteoblasts. While the transcriptomic and epigenomic changes during adipogenesis and osteogenesis have been characterized, what happens to the chromatin loops is hardly known. Here we induced hMSCs to adipogenic and osteogenic differentiation, and performed 2 kb resolution Hi-C experiments for loop detection and generated RNA-seq, histone modification ChIP-seq and ATAC-seq data for integrative analysis before and after differentiation. We quantitatively identified differential contact loops and unique loops. After integrating with multi-omics data, we demonstrate that strengthened loops after differentiation are associated with gene expression activation. Specially, unique loops are linked with cell fate determination. We also proposed loop-mediated regulatory networks and identified IRS2 and RUNX2 as being activated by cell-specific loops to facilitate adipocytes and osteoblasts commitment, respectively. These results are expected to help better understand the long-range regulation in controlling hMSC differentiation, and provide novel targets for studying adipocytes and osteoblasts determination.
Project description:Cell-fate determination of human mesenchymal stem/stromal cells (hMSCs) is precisely regulated by lineage-specific transcription factors and epigenetic enzymes. We found that CTR9, a key scaffold subunit of Polymerase Associated Factor Complex (PAFc), selectively regulates hMSC differentiation to osteoblasts and chondrocytes, but not to adipocytes. An in vivo ectopic osteogenesis assay confirmed the essentiality of CTR9 in hMSC-derived bone formation. CTR9 counteracts the activity of EZH2, the epigenetic enzyme that deposits H3K27me3, in hMSCs. Accordingly, CTR9 knockdown (1) hMSCs gain H3K27me3 mark, and the osteogenic differentiation defects of CTR9 KD hMSCs can be partially rescued by treatment with EZH2 inhibitors. Transcriptome analyses identified Bone Morphology Protein-2 (BMP-2) as a downstream effector of CTR9. BMP-2 secretion, membrane anchorage, as well as the BMP-SMAD pathway were impaired in CTR9 KD MSCs, and the effects were rescued by BMP-2 supplementation. This study uncovers an epigenetic mechanism engaging CTR9-H3K27me3-BMP-2 axis to regulate osteochondral lineage differentiation of hMSCs. To investigate the function of CTR9 in the gene regulation of early osteogenic committment , we established human MSCs in which CTR9 gene has been knocked down by two individual shRNAs (shControl vs shCTR9#3/#5).
Project description:Genome-wide DNA methylation profiling was performed of human mesenchymal stem cells (hMSCs) differentiating into adipocytes (day 10). The Illumina Infinium 450k Human DNA methylation Beadchip v1.2 was used to measure DNA methylation of hMSC before differentiation (day 0) and of adipocytes at day 10 of differentiation. Our aims were to 1) measure genome-wide DNA methylation changes during adipocyte differentiation in primary hMSCs and 2) investigate the relationship between DNA methylation and gene expression regulation in a panel of 84 adipocyte-related genes. Bisulphite converted DNA from four independent experiments was hybridised to the Illumina Infinium 450k Human Methylation Beadchip. The first comparison was made between undifferentiated hMSCs and differentiated adipocytes at day 10. As a positive control, differentiating cells were continuously exposed to 5-Aza-2â²-deoxycytidine (5-aza-dC). The second comparison was made between differentiated adipocytes at day 10 and 5-aza-dC exposed adipocytes at day 10.
Project description:R-loops are three stranded nucleic acid structures that accumulate on chromatin in neurological diseases and cancers and that contribute to genome instability. Using a proximity-dependent labeling system, we identified distinct classes of proteins that regulate R-loops in vivo through different mechanisms. We show that ATRX suppresses R-loops by interacting with RNAs and preventing R-loop formation. Our proteomics screen also discovered an unexpected enrichment for proteins containing zinc fingers and homeodomains at R-loops. One of the most consistently enriched proteins at R-loops was activity-dependent neuroprotective protein (ADNP), which is frequently mutated in ASD and causal in ADNP syndrome. We find that ADNP is necessary to suppress R-loops in vivo at its genomic targets and that it resolves R-loops in vitro. Furthermore, deletion of the homeodomain severely diminishes R-loop resolution activity in vitro, results in R-loop accumulation at ADNP targets and compromises neuronal differentiation. Notably, patient derived human induced pluripotent stem cells that contain an ADNP syndrome-causing mutation exhibit R-loop and CTCF accumulation at ADNP targets. Our findings point to a specific role for ADNP-mediated R-loop resolution in physiological and pathological neuronal function and, more broadly, to a previously unappreciated role for zinc finger and homeodomain proteins in R-loop regulation, with important implications for developmental disorders and cancers.
Project description:hMSCs (Lonza) were differentiated towards adipocytes with three cycles of adipocyte differentiation induction and maintenance. hMSCs were differentiated towards osteocytes with osteogenic differentiation medium for 3 days and for 7 days. ArrayCGH experiments were performed before differentiation induction, after 2 and 3 cycles of adipogenic differentiation induction and after 3 days and 7 days of osteogenic differentiation induction.
Project description:Gene Expression analysis of a differentiation timeseries of human Mesenchymal Stem Cells (hMSCs) in the presence of adipogenic/osteogenic factors. hMSCs differentiate into fat cells when treated with dexamethasone (10^-6 M), insulin (10 ug/ml), rosiglitazone (10^-7 M) and IBMX (250 uM). TGFbeta (5 ng/ml) inhibits this process and redirects these cells to differentiate into bone cells. Introduction: Patients suffering from osteoporosis show an increased number of adipocytes in their bone marrow, concomitant with a reduction in the pool of human mesenchymal stem cells (hMSCs) that are able to differentiate into osteoblasts, thus leading to suppressed osteogenesis. Methods: In order be able to interfere with this process, we have investigated in vitro culture conditions whereby adipogenic differentiation of hMSCs is impaired and osteogenic differentiation is promoted. By means of gene expression microarray analysis, we have investigated genes which are potential targets for prevention of fat cell differentiation. Results: Our data show that BMP2 promotes both adipogenic and osteogenic differentiation of hMSCs, while TGFβ inhibits differentiation into both lineages. However, when cells are cultured under adipogenic differentiation conditions, which contains cAMP-enhancing agents such as IBMX of PGE2, TGFβ promotes osteogenic differentiation, while at the same time inhibiting adipogenic differentiation. Gene expression and immunoblot analysis indicated that cAMP-induced suppression of HDAC5 levels plays an important role in the inhibitory effect of TGFβ on osteogenic differentiation. By means of gene expression microarray analysis, we have investigated genes which are downregulated by TGFβ under adipogenic differentiation conditions and may therefore be potential targets for prevention of fat cell differentiation. We thus identified 9 genes for which FDA-approved drugs are available. Our results show that drugs directed against the nuclear hormone receptor PPARG, the metalloproteinase ADAMTS5 and the aldo-keto reductase AKR1B10 inhibit adipogenic differentiation in a dose-dependent manner, although in contrast to TGFβ they do not appear to promote osteogenic differentiation. Conclusions: The approach chosen in this study has resulted in the identification of new targets for inhibition of fat cell differentiation, which may not only be relevant for prevention of osteoporosis, but also of obesity. hMSCs were induced to differentiate in the presence dexamethasone, insulin and rosiglitazone, to which was added either 50 ng/ml BMP2; BMP2 + TGFbeta; BMP2 + IBMX; BMP2 + TGFbeta + IBMX.
Project description:Genome-wide DNA methylation profiling was performed of human mesenchymal stem cells (hMSCs) differentiating into adipocytes (day 10). The Illumina Infinium 450k Human DNA methylation Beadchip v1.2 was used to measure DNA methylation of hMSC before differentiation (day 0) and of adipocytes at day 10 of differentiation. Our aims were to 1) measure genome-wide DNA methylation changes during adipocyte differentiation in primary hMSCs and 2) investigate the relationship between DNA methylation and gene expression regulation in a panel of 84 adipocyte-related genes.