Hematopoietic stem cells acquire survival advantage by loss of RUNX1 methylation identified in familial leukemia
Hematopoietic stem cells acquire survival advantage by loss of RUNX1 methylation identified in familial leukemia
复制标题
DOI：
10.1182/blood.2019004292
复制
发表时间：
2020-10-22
期刊：
影响因子：
20.3
通讯作者：
Suda, Toshio
中科院分区：
文献类型：
--
作者：
Matsumura, Takayoshi;Nakamura-Ishizu, Ayako;Suda, Toshio
RUNX 1是人类白血病中最常见的突变基因之一，在骨髓增生异常综合征和急性髓性白血病（AML）中发现了RUNX 1功能的丧失或显性负抑制。然而，RUNX 1的翻译后修饰（PTM）如何影响其体内功能，以及RUNX 1的PTM失调是否会导致白血病在很大程度上是未知的。我们对一个发生3次AML的家族进行了靶向深度测序，并确定了一种新的RUNX 1突变R237 K。突变的R237残基是蛋白质精氨酸甲基转移酶1的甲基化位点，据报道甲基化的丧失会损害RUNX 1的体外转录活性。为了探索RUNX 1甲基化在体内的生物学意义，我们使用了RUNX 1 R233 K/R237 K双突变小鼠，其中2个赖氨酸-赖氨酸突变排除了RUNX 1甲基化。RUNX 1甲基化的基因消除导致造血干细胞（HSC）的静止和扩增丧失，并且它将表型HSC的基因组和表观基因组特征改变为稳定的祖细胞状态。此外，RUNX 1 R233/R237甲基化的缺失抑制了内质网应激诱导的未折叠蛋白反应基因，包括Atf 4，Ddit 3和Gadd 34;辐射诱导的p53下游基因Bbc 3，Pmaip 1和Cdkn 1a;以及随后的HSC凋亡。从机制上讲，转录激活因子4被确定为RUNX 1的直接转录靶点。总的来说，HSC中RUNX 1甲基化的缺陷赋予了对凋亡的抵抗力和在应激条件下的生存优势，这是白血病前克隆的标志，可能使受影响的个体易患白血病。我们的研究将有助于更好地了解PTM的失调如何有助于白血病的发生。
RUNX1 is among the most frequently mutated genes in human leukemia, and the loss or dominant-negative suppression of RUNX1 function is found in myelodysplastic syndrome and acute myeloid leukemia (AML). How posttranslational modifications (PTMs) of RUNX1 affect its in vivo function, however, and whether PTM dysregulation of RUNX1 can cause leukemia are largely unknown. We performed targeted deep sequencing on a family with 3 occurrences of AML and identified a novel RUNX1 mutation, R237K. The mutated R237 residue is a methylation site by protein arginine methyltransferase 1, and loss of methylation reportedly impairs the transcriptional activity of RUNX1 in vitro. To explore the biologic significance of RUNX1 methylation in vivo, we used RUNX1 R233K/R237K double-mutant mice, in which 2 arginine-to-lysine mutations precluded RUNX1 methylation. Genetic ablation of RUNX1 methylation led to loss of quiescence and expansion of hematopoietic stem cells (HSCs), and it changed the genomic and epigenomic signatures of phenotypic HSCs to a poised progenitor state. Furthermore, loss of RUNX1 R233/R237 methylation suppressed endoplasmic reticulum stress-induced unfolded protein response genes, including Atf4, Ddit3, and Gadd34; the radiation-induced p53 downstreamgenes Bbc3, Pmaip1, andCdkn1a; and subsequent apoptosis inHSCs. Mechanistically, activating transcription factor 4 was identified as a direct transcriptional target of RUNX1. Collectively, defects in RUNX1 methylation in HSCs confer resistance to apoptosis and survival advantage under stress conditions, a hallmark of a preleukemic clone that may predispose affected individuals to leukemia. Our study will lead to a better understanding of how dysregulation of PTMs can contribute to leukemogenesis.