Project description:Induced pluripotent stem cells (iPSCs) are generated from somatic cells by the transduction of defined transcription factors and involves dynamic changes in DNA methylation. While the reprogramming of somatic cells is accompanied by de-methylation of pluripotency genes, the functional importance of de novo DNA methylation has not been clarified. Here, using loss-of-function studies, we generated iPSCs from fibroblasts that were deficient in de novo DNA methylation mediated by Dnmt3a and Dnmt3b. These iPSCs reactivated pluripotency genes, underwent self-renewal and showed restricted developmental potential which was rescued upon re-introduction of Dnmt3a and Dnmt3b. We conclude that de novo DNA methylation by Dnmt3a and Dnmt3b is dispensable for nuclear reprogramming of somatic cells. RNA levels of Dnmt3ab deficient iPSC cell lines were compared to control iPSC cell lines
Project description:Induced pluripotent stem cells (iPSCs) are generated from somatic cells by the transduction of defined transcription factors and involves dynamic changes in DNA methylation. While the reprogramming of somatic cells is accompanied by de-methylation of pluripotency genes, the functional importance of de novo DNA methylation has not been clarified. Here, using loss-of-function studies, we generated iPSCs from fibroblasts that were deficient in de novo DNA methylation mediated by Dnmt3a and Dnmt3b. These iPSCs reactivated pluripotency genes, underwent self-renewal and showed restricted developmental potential which was rescued upon re-introduction of Dnmt3a and Dnmt3b. We conclude that de novo DNA methylation by Dnmt3a and Dnmt3b is dispensable for nuclear reprogramming of somatic cells.
Project description:To investigate the role of YAP/TAZ as factors able to convert differentiated cells into stem cells of the same tissue, we compared the expression profiles of mammary organoids (yOrg) obtained by doxycycline-inducible expression of YAP in luminal differentiated mammary cells with original luminal differentiated mammary cells (Lum) and organoids from native mammary stem cells (Org).
Project description:To investigate the role of YAP/TAZ as factors able to convert differentiated cells into stem cells of the same tissue, we compared the expression profiles of neural stem cells (NSCs) obtained by doxycycline-inducible expression of YAP (yNSCs) in neurons with original neurons and neural stem cells (NSCs) treated in the same way.
Project description:To investigate the role of YAP/TAZ as factors able to convert differentiated cells into stem cells of the same tissue, we compared the expression profiles of pancreatic organoids (yDucts) obtained by doxycycline-inducible expression of YAP in pancreatic acini with original acini and native ducts (Ducts).
Project description:CpG islands (CGIs) including those at imprinting control regions (ICRs) are protected from de novo methylation in somatic cells. However, many cancers often exhibit CGI hypermethylation, implying that the machinery is impaired in cancer cells. Here, we conducted a comprehensive analysis of CGI methylation during the somatic cell reprogramming. Although most CGIs remain hypomethylated, a small subset of CGIs, particularly at several ICRs, were often de novo methylated in reprogrammed pluripotent stem cells (PSCs). Such de novo ICR methylation was linked with the silencing of reprogramming factors, which occurs at a late stage of reprogramming. The ICR-preferred CGI hypermethylation was similarly observed in human PSCs. Mechanistically, ablation of Dnmt3a prevented PSCs from de novo ICR methylation. Notably, the ICR-preferred CGI hypermethylation was observed in pediatric cancers, while adult cancers exhibit genome-wide CGI hypermethylation. These results may have important implications in the pathogenesis of pediatric cancers and the application of PSCs.
Project description:Cytosine methylation is an epigenetic mark usually associated with gene repression. Despite a requirement for de novo DNA methylation for differentiation of embryonic stem cells, its role in somatic stem cells is unknown. Using conditional ablation, we show that loss of either, or both, Dnmt3a or Dnmt3b, progressively impedes hematopoietic stem cell (HSC) differentiation during serial in vivo passage. Concomitantly, HSC self-renewal is immensely augmented in absence of either Dnmt3, particularly Dnmt3a. Dnmt3-KO HSCs show upregulation of HSC multipotency genes and downregulation of early differentiation factors, and the differentiated progeny of Dnmt3-KO HSCs exhibit hypomethylation and incomplete repression of HSC-specific genes. HSCs lacking Dnmt3a manifest hyper-methylation of CpG islands and hypo-methylation of genes which are highly correlated with human hematologic malignancies. These data establish that aberrant DNA methylation has direct pathologic consequences for somatic stem cell development, leading to inefficient differentiation and maintenance of a self-renewal program. Reduced representation bisulfite sequencing (MspI,~40-220bp size fraction) of secondarily-transplanted wild-type and Dnmt3a conditional knockout hematopoietic stem cells. We used microarrays to detail the global expression of genes in secondarily-transplanted control-HSCs and Dnmt3a-KO-HSCs.