Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana, USA; Harper Cancer Research Institute, University of Notre Dame, Notre Dame, Indiana, USA.
Harper Cancer Research Institute, University of Notre Dame, Notre Dame, Indiana, USA; Department of Microbiology and Immunology, Indiana University School of Medicine, South Bend, Indiana, USA.
J Leukoc Biol. 2016 Oct;100(4):665-677. doi: 10.1189/jlb.1HI0915-398RR. Epub 2016 Apr 15.
Ablation of microRNA synthesis by deletion of the microRNA-processing enzyme Dicer has demonstrated that microRNAs are necessary for normal hematopoietic differentiation and function. However, it is still unclear which specific microRNAs are required for hematopoiesis and at what developmental stages they are necessary. This is especially true for immune cell development. We previously observed that overexpression of the products of the mirn23a gene (microRNA-23a, -24-2, and 27a) in hematopoietic progenitors increased myelopoiesis with a reciprocal decrease in B lymphopoiesis, both in vivo and in vitro. In this study, we generated a microRNA-23a, -24-2, and 27a germline knockout mouse to determine whether microRNA-23a, -24-2, and 27a expression was essential for immune cell development. Characterization of hematopoiesis in microRNA-23a, -24-2, and 27a mice revealed a significant increase in B lymphocytes in both the bone marrow and the spleen, with a concomitant decrease in myeloid cells (monocytes/granulocytes). Analysis of the bone marrow progenitor populations revealed a significant increase in common lymphoid progenitors and a significant decrease in both bone marrow common myeloid progenitors and granulocyte monocyte progenitors. Gene-expression analysis of primary hematopoietic progenitors and multipotent erythroid myeloid lymphoid cells showed that microRNA-23a, -24-2, and 27a regulates essential B cell gene-expression networks. Overexpression of microRNA-24-2 target Tribbles homolog 3 can recapitulate the microRNA-23a, -24-2, and 27a phenotype in vitro, suggesting that increased B cell development in microRNA-23a, -24-2, and 27a null mice can be partially explained by a Tribbles homolog 3-dependent mechanism. Data from microRNA-23a, -24-2, and 27a mice support a critical role for this microRNA cluster in regulating immune cell populations through repression of B lymphopoiesis.
通过删除 miRNA 加工酶 Dicer 来阻断 miRNA 的合成，已经证明 miRNA 对于正常的造血分化和功能是必需的。然而，目前仍不清楚哪些特定的 miRNA 对于造血作用是必需的，以及它们在何种发育阶段是必需的。对于免疫细胞的发育来说，情况尤其如此。我们之前观察到，在造血祖细胞中过表达 mirn23a 基因产物（miRNA-23a、-24-2 和 27a）会增加骨髓细胞生成，同时减少 B 淋巴细胞生成，无论是在体内还是体外。在这项研究中，我们生成了 miRNA-23a、-24-2 和 27a 生殖系敲除小鼠，以确定 miRNA-23a、-24-2 和 27a 的表达对于免疫细胞发育是否是必需的。miRNA-23a、-24-2 和 27a 小鼠的造血特征表明，骨髓和脾脏中的 B 淋巴细胞显著增加，而骨髓中的髓系细胞（单核细胞/粒细胞）显著减少。对骨髓祖细胞群体的分析表明，普通淋巴祖细胞显著增加，骨髓普通髓系祖细胞和粒细胞单核细胞祖细胞显著减少。对原代造血祖细胞和多能红系髓系淋巴样细胞的基因表达分析表明，miRNA-23a、-24-2 和 27a 调节着关键的 B 细胞基因表达网络。miRNA-24-2 靶基因 Tribbles 同源物 3 的过表达可以在体外再现 miRNA-23a、-24-2 和 27a 的表型，这表明 miRNA-23a、-24-2 和 27a 缺失小鼠中 B 细胞发育的增加部分可以通过 Tribbles 同源物 3 依赖的机制来解释。miRNA-23a、-24-2 和 27a 小鼠的数据支持了该 miRNA 簇在通过抑制 B 淋巴细胞生成来调节免疫细胞群体方面的关键作用。
