ALKBH1 was recently discovered as a demethylase for DNA N6-methyladenine （N6-mA）, a new epigenetic modification, and interacts with the core transcriptional pluripotency network of embryonic stem cells. However, the...ALKBH1 was recently discovered as a demethylase for DNA N6-methyladenine （N6-mA）, a new epigenetic modification, and interacts with the core transcriptional pluripotency network of embryonic stem cells. However, the role of ALKBH1 and DNA N6-mA in regulating osteogenic differentiation is largely unknown. In this study, we demonstrated that the expression of ALKBH1 in human mesenchymal stem cells （MSCs） was upregulated during osteogenic induction. Knockdown of ALKBH1 increased the genomic DNA N6-mA levels and significantly reduced the expression of osteogenic-related genes, alkaline phosphatase activity, and mineralization. ALKBHl-depleted MSCs also exhibited a restricted capacity for bone formation in vivo. By contrast, the ectopic overexpression of ALKBH1 enhanced osteoblastic differentiation. Mechanically, we found that the depletion of ALKBH1 resulted in the accumulation of N6-mA on the promoter region of ATF4, which subsequently silenced ATF4 transcription. In addition, restoring the expression of ATP by adenovirus-mediated transduction successfully rescued osteogenic differentiation. Taken together, our results demonstrate that ALKBH1 is indispensable for the osteogenic differentiation of MSCs and indicate that DNA N6-mA modifications area new mechanism for the epigenetic regulation of stem cell differentiation.展开更多
Many eukaryotic genes are members of multi-gene families due to gene duplications, which generate new copies that allow functional divergence. However, the relationship between
Leaf senescence is driven by the expression of senescence-associated genes(SAGs).Development-specific genes often undergo DNA demethylation in their promoter and other regions,which regulates gene expression.Whether a...Leaf senescence is driven by the expression of senescence-associated genes(SAGs).Development-specific genes often undergo DNA demethylation in their promoter and other regions,which regulates gene expression.Whether and how DNA demethylation regulates the expression of SAGs and thus leaf senescence remain elusive.Whole-genome bisulfite sequencing(WGBS)analyses of wild-type(WT)and demeter-like 3(dml3)Arabidopsis leaves at three developmental stages revealed hypermethylation during leaf senescence in dml3 compared with WT,and 20556 differentially methylated regions(DMRs)were identified by comparing the methylomes of dml3 and WT in the CG,CHG,and CHH contexts.Furthermore,we identified that 335 DMR-associated genes(DMGs),such as NAC016 and SEN1,are upregulated during leaf senescence,and found an inverse correlation between the DNA methylation levels(especially in the promoter regions)and the transcript abundances of the related SAGs in WT.In contrast,in dml3 the promoters of SAGs were hypermethylated and their transcript levels were remarkably reduced,and leaf senescence was significantly delayed.Collectively,our study unraveled a novel epigenetic regulatory mechanism underlying leaf senescence in which DML3 is expressed at the onset of and during senescence to demethylate promoter,gene body or 3'UTR regions to activate a set of SAGs.展开更多
基金supported by grants from the National Natural Science Foundation of China (No.81271178 and 81470777)
文摘ALKBH1 was recently discovered as a demethylase for DNA N6-methyladenine （N6-mA）, a new epigenetic modification, and interacts with the core transcriptional pluripotency network of embryonic stem cells. However, the role of ALKBH1 and DNA N6-mA in regulating osteogenic differentiation is largely unknown. In this study, we demonstrated that the expression of ALKBH1 in human mesenchymal stem cells （MSCs） was upregulated during osteogenic induction. Knockdown of ALKBH1 increased the genomic DNA N6-mA levels and significantly reduced the expression of osteogenic-related genes, alkaline phosphatase activity, and mineralization. ALKBHl-depleted MSCs also exhibited a restricted capacity for bone formation in vivo. By contrast, the ectopic overexpression of ALKBH1 enhanced osteoblastic differentiation. Mechanically, we found that the depletion of ALKBH1 resulted in the accumulation of N6-mA on the promoter region of ATF4, which subsequently silenced ATF4 transcription. In addition, restoring the expression of ATP by adenovirus-mediated transduction successfully rescued osteogenic differentiation. Taken together, our results demonstrate that ALKBH1 is indispensable for the osteogenic differentiation of MSCs and indicate that DNA N6-mA modifications area new mechanism for the epigenetic regulation of stem cell differentiation.
文摘Many eukaryotic genes are members of multi-gene families due to gene duplications, which generate new copies that allow functional divergence. However, the relationship between
基金This work was supported by the National Key Research and Development Program of China(grant no.2019YFD1000300,to L.Chen)by Cornell University 1843351(to S.G.).
文摘Leaf senescence is driven by the expression of senescence-associated genes(SAGs).Development-specific genes often undergo DNA demethylation in their promoter and other regions,which regulates gene expression.Whether and how DNA demethylation regulates the expression of SAGs and thus leaf senescence remain elusive.Whole-genome bisulfite sequencing(WGBS)analyses of wild-type(WT)and demeter-like 3(dml3)Arabidopsis leaves at three developmental stages revealed hypermethylation during leaf senescence in dml3 compared with WT,and 20556 differentially methylated regions(DMRs)were identified by comparing the methylomes of dml3 and WT in the CG,CHG,and CHH contexts.Furthermore,we identified that 335 DMR-associated genes(DMGs),such as NAC016 and SEN1,are upregulated during leaf senescence,and found an inverse correlation between the DNA methylation levels(especially in the promoter regions)and the transcript abundances of the related SAGs in WT.In contrast,in dml3 the promoters of SAGs were hypermethylated and their transcript levels were remarkably reduced,and leaf senescence was significantly delayed.Collectively,our study unraveled a novel epigenetic regulatory mechanism underlying leaf senescence in which DML3 is expressed at the onset of and during senescence to demethylate promoter,gene body or 3'UTR regions to activate a set of SAGs.
