Higo Takashi, Suzuki Yutaro, Sato Michiaki, Koya Junji, Mizuno Hideaki, Miyauchi Masashi, Masamoto Yosuke, Kataoka Keisuke, Sumitomo Yoshiki, Tsuruta-Kishino Takako, Sato Tomohiko, Kurokawa Mineo
Department of Hematology and Oncology, Graduate School of Medicine, University of Tokyo, Tokyo, Japan.
Department of Hematology and Oncology, Graduate School of Medicine, University of Tokyo, Tokyo, Japan; Department of Cell Therapy and Transplantation, University of Tokyo Hospital, Tokyo, Japan.
Exp Hematol. 2022 May;109:45-54. doi: 10.1016/j.exphem.2022.02.006. Epub 2022 Mar 1.
Somatic mutation of DNMT3A (DNA methyltransferase 3 alpha) is implicated in the development of a wide range of hematological disorders, including clonal hematopoiesis of indeterminate potential. To elucidate the functional roles of endogenous levels of a DNMT3A R882 mutant, we generated a novel Dnmt3a R878C conditional knock-in mouse model. In contrast to viable heterozygotes, mice homozygous for the Dnmt3a R878C mutation in the hematopoietic system were not viable (Dnmt3a R878C is homologous to human DNMT3A R882C). Hematopoietic cell-specific heterozygous expression of Dnmt3a R878C led to significant expansion of adult quiescent hematopoietic stem cells (HSCs); however, these mice had no hematological malignancies. The expanding HSC population in heterozygous Dnmt3a R878C knock-in mice had an accumulation of G0-phase cells. In contrast to aberrantly enhanced self-renewal capacity in vitro, heterozygous Dnmt3a R878C knock-in HSCs had no competitive repopulating advantage in vivo over wild-type HSCs. Considering the capacity of the heterozygous Dnmt3a R878C mutant for HSC pool expansion, our Dnmt3a R878C knock-in mouse line is a useful platform on which to dissect the pathophysiology of clonal hematopoiesis. This mouse line can also help to elucidate the biological and molecular actions of DNMT3A mutations in the malignant transformation of normal HSCs.
DNA甲基转移酶3α（DNMT3A）的体细胞突变与多种血液系统疾病的发生有关，包括意义未明的克隆性造血。为了阐明内源性水平的DNMT3A R882突变体的功能作用，我们构建了一种新型的Dnmt3a R878C条件性敲入小鼠模型。与存活的杂合子不同，造血系统中Dnmt3a R878C突变纯合的小鼠无法存活（Dnmt3a R878C与人类DNMT3A R882C同源）。Dnmt3a R878C的造血细胞特异性杂合表达导致成年静止造血干细胞（HSC）显著扩增；然而，这些小鼠没有血液系统恶性肿瘤。杂合Dnmt3a R878C敲入小鼠中扩增的HSC群体有G0期细胞的积累。与体外异常增强的自我更新能力相反，杂合Dnmt3a R878C敲入HSC在体内相对于野生型HSC没有竞争重建造血优势。考虑到杂合Dnmt3a R878C突变体对HSC库扩增的能力，我们的Dnmt3a R878C敲入小鼠品系是一个有用的平台，可用于剖析克隆性造血的病理生理学。该小鼠品系还可有助于阐明DNMT3A突变在正常HSC恶性转化中的生物学和分子作用。
