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De novo DNA methyltransferase is essential for self-renewal, but not for differentiation, in hematopoietic stem cells.

ABSTRACT: DNA methylation is an epigenetic modification essential for development. The DNA methyltransferases Dnmt3a and Dnmt3b execute de novo DNA methylation in gastrulating embryos and differentiating germline cells. It has been assumed that these enzymes generally play a role in regulating cell differentiation. To test this hypothesis, we examined the role of Dnmt3a and Dnmt3b in adult stem cells. CD34(-/low), c-Kit(+), Sca-1(+), lineage marker(-) (CD34(-) KSL) cells, a fraction of mouse bone marrow cells highly enriched in hematopoietic stem cells (HSCs), expressed both Dnmt3a and Dnmt3b. Using retroviral Cre gene transduction, we conditionally disrupted Dnmt3a, Dnmt3b, or both Dnmt3a and Dnmt3b (Dnmt3a/Dnmt3b) in CD34(-) KSL cells purified from mice in which the functional domains of these genes are flanked by two loxP sites. We found that Dnmt3a and Dnmt3b function as de novo DNA methyltransferases during differentiation of hematopoietic cells. Unexpectedly, in vitro colony assays and in vivo transplantation assays showed that both myeloid and lymphoid lineage differentiation potentials were maintained in Dnmt3a-, Dnmt3b-, and Dnmt3a/Dnmt3b-deficient HSCs. However, Dnmt3a/Dnmt3b-deficient HSCs, but not Dnmt3a- or Dnmt3b-deficient HSCs, were incapable of long-term reconstitution in transplantation assays. These findings establish a critical role for DNA methylation by Dnmt3a and Dnmt3b in HSC self-renewal.

SUBMITTER: Tadokoro Y

PROVIDER: S-EPMC2118548 | biostudies-literature | 2007 Apr

REPOSITORIES: biostudies-literature

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De novo DNA methyltransferase is essential for self-renewal, but not for differentiation, in hematopoietic stem cells.

Tadokoro Yuko Y Ema Hideo H Okano Masaki M Li En E Nakauchi Hiromitsu H

The Journal of experimental medicine 20070409 4

DNA methylation is an epigenetic modification essential for development. The DNA methyltransferases Dnmt3a and Dnmt3b execute de novo DNA methylation in gastrulating embryos and differentiating germline cells. It has been assumed that these enzymes generally play a role in regulating cell differentiation. To test this hypothesis, we examined the role of Dnmt3a and Dnmt3b in adult stem cells. CD34(-/low), c-Kit(+), Sca-1(+), lineage marker(-) (CD34(-) KSL) cells, a fraction of mouse bone marrow c ...[more]

PMID: 17420264

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Project description:Hematopoietic stem cells (HSCs) have the capacity for self-renewal to maintain the HSCs' pool and the ability for multilineage differentiation, which are responsible for sustained production of multiple blood lineages. The regulation of HSC development is controlled precisely by complex signal networks and hematopoietic microenvironment, which has been termed the HSCs' niche. The Wnt signaling pathway is one of a variety of signaling pathways that have been involved in HSC self-renewal and maintenance. Previous studies are indeterminant on the regulation of adult HSCs upon canonical Wnt signaling pathways because of the different experimental systems and models used. In this study, we generated the conditional knockout Wnt coreceptor low-density lipoprotein receptor-related protein 5 (Lrp5) and low-density lipoprotein receptor-related protein 6 (Lrp6) mice in adult hematopoiesis via Vav-Cre Loxp system. Inactivation of Lrp5 and -6 in a hematopoietic system diminished the pool of HSCs, but there were no obvious defects in mature immune cells. Lrp5 and -6 double deficiency HSCs showed intrinsic defects in self-renewal and differentiation due to reduced proliferation and increased quiescence of the cell cycle. Analysis of HSC gene expression suggested that the quiescence regulators were significantly up-regulated, such as Egr1, Cdkn1a, Nr4a1, Gata2, Junb and Btg2, and the positive cell cycle regulators were correspondingly down-regulated, such as Ccna2 and Ranbp1. Taken together, we investigated the roles of Lrp5 and -6 in HSCs by functional and bioinformatic assays, and we demonstrated that Lrp5 and -6 are required for the self-renewal and differentiation of adult HSCs. The canonical Wnt pathway may contribute to maintaining the HSC pool and regulate the differentiation of adult HSCs by controlling cell cycle gene regulatory module.-Liu, J., Cui, Z., Wang, F., Yao, Y., Yu, G., Liu, J., Cao, D., Niu, S., You, M., Sun, Z., Lian, D., Zhao, T., Kang, Y., Zhao, Y., Xue, H.-H., Yu, S. Lrp5 and Lrp6 are required for maintaining self-renewal and differentiation of hematopoietic stem cells.

Project description:Spermatogonial stem cells undergo both self-renewal to maintain the stem cell population and differentiation to produce mature sperm. These processes are controlled by both stem cell-intrinsic and external niche factors. DOT1L, the sole H3K79 methyltransferase, is dispensable for mouse embryonic stem cell self-renewal but instead functions as a barrier to somatic cell reprogramming. Here we show that DOT1L is required for spermatogonial stem cell self-renewal. Mice lacking DOT1L in the germ cells show a failure in the maintenance of spermatogonial stem cells without a block in spermatogenic cell differentiation and thus a progressive loss of germ cells, leading to a Sertoli-cell-only syndrome. Chemical inhibition of DOT1L in cultured stem cells reduces the spermatogonial stem cell activity after transplantation. RNA-seq analysis reveals downregulation of Hoxc cluster genes in DOT1L-inhibited spermatogonia stem cells. Single cell RNA-seq analysis demonstrates that inhibition of DOT1L sequesters spermatogonial stem cells in a primitive state and prevents them from transitioning to a progenitor state. These results identify a new function for DOT1L in adult stem cells and provides a paradigm for regulation of spermatogonial stem cell self-renewal. Self-renewal of spermatogonial stem cells is vital to life-long production of male gametes and thus fertility. However, the underlying mechanisms remain enigmatic. Here, we show that DOT1L, the sole H3K79 methyltransferase, is required for spermatogonial stem cell self-renewal. Mice lacking DOT1L fail to maintain spermatogonial stem cells, characterized by a sequential loss of germ cells from spermatogonia to spermatids and ultimately a Sertoli-cell-only syndrome. Inhibition of DOT1L reduces the stem cell activity after transplantation, prevents spermatogonial stem cells from transitioning to a progenitor state, and sequesters them in a primitive state. Furthermore, DOT1L promotes expression of the fate-determining HoxC transcription factors in spermatogonial stem cells. Our findings identify an essential function for DOT1L in adult stem cells and provide an epigenetic paradigm for regulation of spermatogonial stem cells.

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De novo DNA methyltransferase is essential for self-renewal, but not for differentiation, in hematopoietic stem cells.

Publications

De novo DNA methyltransferase is essential for self-renewal, but not for differentiation, in hematopoietic stem cells.

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