Evi1 governs Kdm6b-mediated histone demethylation to regulate the Laptm4b-driven mTOR pathway in hematopoietic progenitor cells
Qiong Wu, Chunjie Yu, Fang Yu, Yiran Guo, Yue Sheng, Liping Li, Yafang Li, Yutao Zhang, Chao Hu, Jue Wang, Tong-chuan He, Yong Huang, Hongyu Ni, Zhiguang Huo, Wenshu Wu, Gang Greg Wang, Jianxin Lyu, Zhijian Qian
Qiong Wu, Chunjie Yu, Fang Yu, Yiran Guo, Yue Sheng, Liping Li, Yafang Li, Yutao Zhang, Chao Hu, Jue Wang, Tong-chuan He, Yong Huang, Hongyu Ni, Zhiguang Huo, Wenshu Wu, Gang Greg Wang, Jianxin Lyu, Zhijian Qian
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Research Article Hematology

Evi1 governs Kdm6b-mediated histone demethylation to regulate the Laptm4b-driven mTOR pathway in hematopoietic progenitor cells

Abstract

Ecotropic viral integration site 1 (EVI1/MECOM) is frequently upregulated in myeloid malignancies. Here, we present an Evi1-transgenic mouse model with inducible expression in hematopoietic stem/progenitor cells (HSPCs). Upon induction of Evi1 expression, mice displayed anemia, thrombocytopenia, lymphopenia, and erythroid and megakaryocyte dysplasia with a significant expansion of committed myeloid progenitor cells, resembling human myelodysplastic syndrome/myeloproliferative neoplasm–like (MDS/MPN–like) disease. Evi1 overexpression prompted HSPCs to exit quiescence and accelerated their proliferation, leading to expansion of committed myeloid progenitors while inhibiting lymphopoiesis. Analysis of global gene expression and Evi1 binding site profiling in HSPCs revealed that Evi1 directly upregulated lysine demethylase 6b (Kdm6b). Subsequently, Kdm6b-mediated H3K27me3 demethylation resulted in activation of various genes, including Laptm4b. Interestingly, KDM6B and LAPTM4B are positively correlated with EVI1 expression in patients with MDS. The EVI1/KDM6B/H3K27me3/LAPTM4B signaling pathway was also identified in EVI1hi human leukemia cell lines. We found that hyperactivation of the LAPTM4B-driven mTOR pathway was crucial for the growth of EVI1hi leukemia cells. Knockdown of Laptm4b partially rescued Evi1-induced abnormal hematopoiesis in vivo. Thus, our study establishes a mouse model to investigate EVI1hi myeloid malignancies, demonstrating the significance of the EVI1-mediated KDM6B/H3K27me3/LAPTM4B signaling axis in their maintenance.

Authors

Qiong Wu, Chunjie Yu, Fang Yu, Yiran Guo, Yue Sheng, Liping Li, Yafang Li, Yutao Zhang, Chao Hu, Jue Wang, Tong-chuan He, Yong Huang, Hongyu Ni, Zhiguang Huo, Wenshu Wu, Gang Greg Wang, Jianxin Lyu, Zhijian Qian

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Figure 7

Evi1 overexpression activates mTOR pathway through Laptm4b.

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Evi1 overexpression activates mTOR pathway through Laptm4b. (A) WB analy...
(A) WB analysis showing the expression level of indicated proteins in WT and Evi1-overexpressing Lin–c-Kit+ mouse BM cells. (B) WB analysis for the indicated proteins in U937 and AML1 cells. (C) WB analysis showing the effect of KDM6B inhibition on protein abundance as indicated. (D) WB analysis showing the effect of LAPTM4B knockdown on mTOR signaling in AML1 cells. (E) WB analysis showing the effect of KDM6B inhibition on protein abundance as indicated in Evi1-overexpressing Lin–c-Kit+ mouse BM cells. (F) Colony-forming assay of U937 and AML1 cells in methylcellulose cultures in the presence or absence of 5 μM GSK-J4. n = 3 for each group. (G) U937 and AML1 cells were treated with 5 μM GSK-J4 for 24 hours followed by flow cytometry analysis for apoptosis. n = 3 for each group. (H) Quantification of colony number of WT and Evi1-overexpressing BM cells cultured in methylcellulose with DMSO or GSK-J4. n = 3 for each group. (I) Frequency of apoptosis in Lin– cells from colony-forming assay. n = 3 for each group. (J and K) Bar plots showing the effect of LAPTM4B knockdown on colony-forming ability (J) and cell apoptosis (K) of U937 and AML1 cells. n = 3 for each group. (L) Growth curve of U937 and AML1 cells transduced with LAPTM4B shRNAs or scramble. n = 3 for each group. Data are representative of at least 2 independent experiments. All bar graph data represent mean ± SD, and P values were determined by multiple t tests. **P < 0.01, ***P < 0.001.