Dataset Information

Transcriptome-wide m⁶A methylome during osteogenic differentiation of human adipose-derived stem cells.

ABSTRACT:

Objectives

Adipose-derived stem cells are frequently used for bone regeneration both in vitro and in vivo. N⁶-methyladenosine (m⁶A) is the most abundant post-transcriptional modification on eukaryotic RNAs and plays multifaceted roles in development and diseases. However, the regulatory mechanisms of m⁶A in osteogenic differentiation of human adipose-derived stem cells (hASCs) remain elusive. The present study aimed to build the transcriptome-wide m⁶A methylome during the osteogenic differentiation of hASCs.

Materials and methods

hASCs were harvested after being cultured in a basic or osteogenic medium for 7 days, and the osteogenic differentiation was validated by alkaline phosphatase (ALP) and Alizarin Red S staining, ALP activity assay, and qRT-PCR analysis of ALP, RUNX2, BGLAP, SPP1, SP7, and COL1A1 genes. The m⁶A level was colorimetrically measured, and the expression of m⁶A regulators was confirmed by qRT-PCR and western blot. Moreover, m⁶A MeRIP-seq and RNA-seq were performed to build the transcriptome and m⁶A methylome. Furthermore, bioinformatic analyses including volcano plots, Venn plots, clustering analysis, Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway, gene sets enrichment analysis, and protein-protein interaction analysis were conducted.

Results

In total, 1145 differentially methylated peaks, 2261 differentially expressed genes, and 671 differentially methylated and expressed genes (DMEGs) were identified. GO and KEGG pathway analyses conducted for these DMEGs revealed extensive and osteogenic biological functions. The "PI3K-Akt signaling pathway"; "MAPK signaling pathway"; "parathyroid hormone synthesis, secretion, and action"; and "p53 signaling pathway" were significantly enriched, and the DMEGs in these pathways were identified as m⁶A-specific key genes. A protein-protein interaction network based on DMEGs was built, and VEGFA, CD44, MMP2, HGF, and SPARC were speculated as the hub DMEGs.

Conclusions

The total m⁶A level was reduced with osteogenic differentiation of hASCs. The transcriptome-wide m⁶A methylome built in the present study indicated quite a few signaling pathways, and hub genes were influenced by m⁶A modification. Future studies based on these epigenetic clues could promote understanding of the mechanisms of osteogenic differentiation of hASCs.

SUBMITTER: Sun W

PROVIDER: S-EPMC8411547 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Multipotent mesenchymal stem/stromal cells (MSCs) exhibit great potential for cell-based therapy. Proper epigenomic signatures in MSCs are important for the maintenance and the subsequent differentiation potential. The DNA methyltransferase 3-like (DNMT3L) that was mainly expressed in the embryonic stem (ES) cells and the developing germ cells plays an important role in shaping the epigenetic landscape. Here, we report the reduced colony forming ability and impaired in vitro osteogenesis in Dnmt3l-knockout-mice-derived MSCs (Dnmt3l KO MSCs). By comparing the transcriptome between undifferentiated Dnmt3l KO MSCs and the MSCs from the wild-type littermates, some of the differentially regulated genes (DEGs) were found to be associated with bone-morphology-related phenotypes. On the third day of osteogenic induction, differentiating Dnmt3l KO MSCs were enriched for genes associated with nucleosome structure, peptide binding and extracellular matrix modulation. Differentially expressed transposable elements in many subfamilies reflected the change of corresponding regional epigenomic signatures. Interestingly, DNMT3L protein is not expressed in cultured MSCs. Therefore, the observed defects in Dnmt3l KO MSCs are unlikely a direct effect from missing DNMT3L in this cell type; instead, we hypothesized them as an outcome of the pre-deposited epigenetic signatures from the DNMT3L-expressing progenitors. We observed that 24 out of the 107 upregulated DEGs in Dnmt3l KO MSCs were hypermethylated in their gene bodies of DNMT3L knock-down ES cells. Among these 24 genes, some were associated with skeletal development or homeostasis. However, we did not observe reduced bone development, or reduced bone density through aging in vivo. The stronger phenotype in vitro suggested the involvement of potential spreading and amplification of the pre-deposited epigenetic defects over passages, and the contribution of oxidative stress during in vitro culture. We demonstrated that transient deficiency of epigenetic co-factor in ES cells or progenitor cells caused compromised property in differentiating cells much later. In order to facilitate safer practice in cell-based therapy, we suggest more in-depth examination shall be implemented for cells before transplantation, even on the epigenetic level, to avoid long-term risk afterward.

Project description:In the current study, we have performed a high-throughput CpG methylation analysis of well characterized and defined populations of human adipose-derived stem cells (hASCs) before and after in vitro induction of osteogenic and myogenic differentiation that allows identifying DNA methylation- regulated differentiation genes. We have also address the extent of the epigenetic programming of hASCs- derived differentiated cells by comparing the methylation profiling of these cells with their somatic counterparts from primary tissues. Finally, we also compared the patterns of CpG methylation of hASCs (and their derivatives) with the methylation profiles of myosarcoma and osteosrcoma cell lines. All the CpG methylation studies have been performed with the Infinium 27K methylation arrays (from Illumina). DNA from adipose M-bM-^@M-^Sderived stem cells (n=4), in vitro induced myocytes (n=3), in vitro induced osteocytes (n=3), primary osteocytes obtained from ribs (n=1), primary myocytes (n=1), osteosarcoma cell line (MG63) and myosarcoma cell lines (Te 32.T and RD) was isolated applying the QIAampM-BM-. DNA Mini Kit (Qiagen Iberia, Spain). Microarray- based DNA methylation profiling was performed with the HumanMethylation27 BeadChip Infinium Methylation ArraysM-BM-. (Illumina, Inc.).The panel was designed to compare the DNA methylation status of each group of samples, which allow interrogating 27,578 CpG loci covering 14,495 genes at single-nucleotide resolution by typing bisulfite-converted DNA. The sequences included in the panel are derived from the well-annotated NCBI CCDS database (Genome Build 36) and is supplemented with more than 1,000 cancer-related genes described in published literature. Probe content has been enriched to deeply cover more than 150 well-established cancer genes known to show differential methylation patterns. Methylation array content also targets the promoter regions of 110 miRNA genes. Methylation arrays were performed as follows. Briefly, bisulfite conversion of 1 M-NM-<g of genomic DNA was done using the CpGenomicTM DNA Modification Kit (Intergen Company, Purchase, NY, USA). After sodium bisulfite treatment, the remaining assay steps used Infinium technology and using Illumina-supplied reagents and conditions. A thermocycling program with a short denaturation step included for bisulfite conversion (16 cycles of 95M-BM-:C for 30 seconds followed by 50M-BM-:C for 1 hour) was performed to improve bisulfite conversion efficiency. After bisulfite conversion, each sample was whole-genome amplified (WGA) and enzymatically fragmented. The bisulfite-converted WGA-DNA samples were purified and applied to the BeadChips. During hybridization, the WGA-DNA molecules anneal to locus-specific DNA oligomers linked to individual bead types. The two bead types correspond to each CpG locus -one to the methylated and the other to the unmethylated state. Allele-specific primer annealing is followed by single-base extension using DNP- and Biotin-labeled dNTPs. Both bead types for the same CpG locus will incorporate the same type of labelled nucleotide, determined by the base preceding the interrogated cytosine in the CpG locus, and therefore will be detected in the same colour channel. After extension, the array is fluorescently stained, scanned, and the intensities of the unmethylated and methylated bead types measured. DNA methylation values, described as beta values, are recorded for each locus in each sample via BeadStudio software. DNA methylation beta values are continuous variables between 0 (completely unmethylated) and 1 (completely methylated), representing the ratio of the intensity of the methylated bead type to the combined locus intensity.

Dataset Information

Transcriptome-wide m⁶A methylome during osteogenic differentiation of human adipose-derived stem cells.

Objectives

Materials and methods

Results

Conclusions

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Transcriptome-wide m⁶A methylome during osteogenic differentiation of human adipose-derived stem cells.