Restoration of genome-wide 5-hydroxymethylation by azacitidine and ascorbate in TET2-deficient human pre-leukemic HSPCs
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ABSTRACT:
PROVIDER: PRJNA817283 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR18361300_1.fastq.gz | Fastqsanger.gz | |||
| SRR18361300_2.fastq.gz | Fastqsanger.gz | |||
| SRR18361400_1.fastq.gz | Fastqsanger.gz | |||
| SRR18361400_2.fastq.gz | Fastqsanger.gz | |||
| SRR18361500_1.fastq.gz | Fastqsanger.gz |
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Project description:The conversion of 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC) is a key step in DNA demethylation that is mediated by ten-eleven-translocation (TET) enzymes, which require ascorbate/vitamin C. Here, we report the 5hmC landscape of normal hematopoiesis and identify cell type-specific 5hmC profiles associated with active transcription and chromatin accessibility of key hematopoietic regulators. We utilized CRISPR/Cas9 to model TET2 loss-of-function mutations in primary human HSPCs. Disrupted cells exhibited increased serial replating and competitive advantage, defective erythroid/megakaryocytic differentiation, and in vivo myeloid skewing coupled with reduction of 5hmC at erythroid regulators. Azacitidine and ascorbate restored 5hmC abundance and slowed/reverted the expansion of TET2-mutant clones in vivo. These results demonstrate the key role of 5hmC in normal hematopoiesis and TET2-mutant phenotypes, and raise the possibility of utilizing these agents to treat pre-leukemia/clonal hematopoiesis and prevent leukemogenesis.
2022-05-01 | GSE198908 | GEO
Project description:Ascorbate (vitamin C) is an important antioxidant in leaves with multiple functions in photosynthesis and its levels are tightly regulated by light quality. The majority of work to date has focussed on regulation of ascorbate levels via biosynthesis. However, the pathway of ascorbate degradation, which is localised in the apoplast may additionally play a significant role. The degradative pathway begins with ascorbate oxidation by the enzyme ascorbate oxidase (AO) and hence we have examined the impact of manipulation of ascorbate oxidase activity on the content of ascorbate and the acclimation of photosynthesis to changing light levels. Leaf ascorbate content was highly light dependent in Nicotiana tobaccum being double in high compared with low light conditions. In contrast ascorbate oxidase activity was not altered by changing light levels. Transgenic tobacco lines with reduced or enhanced AO activity exhibited no morphological phenotype and photosynthesis under high light was similarly impaired irrespective of the measured AO activity. However further investigation between AO activity and leaf acclimation to changing light intensity revealed a suite of metabolic and transcriptome changes indicating a role for the apoplastic ascorbate pool in chloroplast to nucleus communication. In all genotypes, transcripts associated with ascorbate synthesis and recycling were less abundant following transition from high to low light. However transcripts associated with glutathione recycling, light harvesting, reaction centre function and the Calvin cycle were all increased in abundance. Following the transition from high to low light increases in leaf threonate, an ascorbate degradation product, were proportional to AO activity. A number of chloroplast synthesised amino acids were significantly increased both during high light and following transfer back to LL for 12 h. Similarly, several primary carbohydrates and TCA intermediates were significantly enhanced following high light treatment. In addition to light effects, AO activity had a significant impact on ï¢-alanine, aspartate and threonine. Intriguingly, a large number of fatty acids were reduced in antisense AO and wild-type plants immediately after high light stress however the content of these compounds were significantly increased in overexpressing sense lines. We conclude that AO mediated turnover plays an important role in adjusting cellular ascorbate content to photosynthetic need in a fluctuating light environment and that light mediated signals rapidly adjust that the apoplastic ascorbate pool.
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Project description:Ascorbate activates CD30 expression and causes widespread specific demethylation of the epigenome of serum free cultured hESC. The genetic and epigenetic integrity of human Embryonic Stem cells (hESCs) is critical to their future applications in research and medicine. hESC cultured in serum free media can accumulate point mutations, aneuploidy and progressive epigenetic changes over prolonged culture in vitro. We have identified ascorbate as the only molecule in the very widely used Knock-out serum replacement medium that is sufficient to induce expression of CD30, a biomarker for aneuploidy in hESCs. In fact, we show that hESC cultured in the presence of ascorbate for 20 passages not only display demethylation of the CD30 locus, but exhibit widespread and remarkably specific and consistent demethylation of 1,847 genes in both HES2 and HES3 cells. The specific ascorbate induced demethylation changes in the hESC epigenome, of which 86% are shared between the two lines, identify a subset of genes in hESC, including CD30, that are sensitive to serum free culture medium induced epigenetic changes. Experiment. HES2 cells were maintained on 20% Fetal calf serum on mouse embryonic fibroblast feeder layers with mechanical dissection. Using HES2 after 99 mechanical passages (P99), hESC were grown for 17-20 (+17 - +20) passages in the presence of 20% Knock-Out Serum Replacement (Invitrogen) either with (+ASC) or without (-ASC) Ascorbate with enzymatic culturing. RNA (FACs sorted for the presence of the pluripotent stem marker TG30) from three passages (17, 19 and 20) (replicates) for both +ASC and âASC samples were arrayed.
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Project description:We explore where transcriptional regulation of ascorbate concentration lies in plants. Is it in biosynthesis, recycling, regulation or consumption? Arabidopsis thaliana plants were grown under controlled environment at four photon flux density levels (PFD). Rosettes from plants were harvested at the four PFD levels and over a diurnal cycle and after a step change in PFD and analysed for ascorbate concentration and transcript levels measured by RNAseq. Ascorbate concentrations and expression of genes in the L-galactose ascorbate biosynthesis, recycling, consumption pathways and regulation are presented to provide a full analysis of the control of ascorbate by environmentally modulated gene expression. Ascorbate concentration responded to PFD levels but not to time of day and showed only a small response to change of PFD after 2 days. Of the L-galactose pathway genes, only GDP galactose phosphorylase (GGP) showed a significant response in to different PFDs, time of day and to change in PFD. Other genes also showed limited responses. This study compares gene expression of a range of ascorbate related genes to changes in environment in a unified way and supports the concept that GGP is the key regulatory gene in ascorbate biosynthesis and that post transcriptional regulation is also important.
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