Kurkewich Jeffrey L, Hansen Justin, Klopfenstein Nathan, Zhang Helen, Wood Christian, Boucher Austin, Hickman Joseph, Muench David E, Grimes H Leighton, Dahl Richard
Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, United States of America.
Harper Cancer Research Institute, South Bend, IN, United States of America.
PLoS Genet. 2017 Jul 13;13(7):e1006887. doi: 10.1371/journal.pgen.1006887. eCollection 2017 Jul.
MicroRNA cluster mirn23a has previously been shown to promote myeloid development at the expense of lymphoid development in overexpression and knockout mouse models. This polarization is observed early in hematopoietic development, with an increase in common lymphoid progenitors (CLPs) and a decrease in all myeloid progenitor subsets in adult bone marrow. The pool size of multipotential progenitors (MPPs) is unchanged; however, in this report we observe by flow cytometry that polarized subsets of MPPs are changed in the absence of mirn23a. Additionally, in vitro culture of MPPs and sorted MPP transplants showed that these cells have decreased myeloid and increased lymphoid potential in vitro and in vivo. We investigated the mechanism by which mirn23a regulates hematopoietic differentiation and observed that mirn23a promotes myeloid development of hematopoietic progenitors through regulation of hematopoietic transcription factors and signaling pathways. Early transcription factors that direct the commitment of MPPs to CLPs (Ikzf1, Runx1, Satb1, Bach1 and Bach2) are increased in the absence of mirn23a miRNAs as well as factors that commit the CLP to the B cell lineage (FoxO1, Ebf1, and Pax5). Mirn23a appears to buffer transcription factor levels so that they do not stochastically reach a threshold level to direct differentiation. Intriguingly, mirn23a also inversely regulates the PI3 kinase (PI3K)/Akt and BMP/Smad signaling pathways. Pharmacological inhibitor studies, coupled with dominant active/dominant negative biochemical experiments, show that both signaling pathways are critical to mirn23a's regulation of hematopoietic differentiation. Lastly, consistent with mirn23a being a physiological inhibitor of B cell development, we observed that the essential B cell transcription factor EBF1 represses expression of mirn23a. In summary, our data demonstrates that mirn23a regulates a complex array of transcription and signaling pathways to modulate adult hematopoiesis.
此前在过表达和基因敲除小鼠模型中已表明，微小RNA簇mirn23a以牺牲淋巴细胞发育为代价促进髓系发育。这种分化偏向在造血发育早期即可观察到，成年骨髓中常见淋巴细胞祖细胞（CLP）数量增加，所有髓系祖细胞亚群数量减少。多能祖细胞（MPP）的细胞库大小未变；然而，在本报告中我们通过流式细胞术观察到，在缺乏mirn23a的情况下，MPP的分化偏向亚群发生了变化。此外，MPP的体外培养和分选后的MPP移植表明，这些细胞在体外和体内的髓系潜能降低，淋巴细胞潜能增加。我们研究了mirn23a调节造血分化的机制，发现mirn23a通过调节造血转录因子和信号通路促进造血祖细胞的髓系发育。在缺乏mirn23a微小RNA的情况下，指导MPP分化为CLP的早期转录因子（Ikzf1、Runx1、Satb1、Bach1和Bach2）以及使CLP分化为B细胞谱系的因子（FoxO1、Ebf1和Pax5）均增加。Mirn23a似乎缓冲了转录因子水平，使其不会随机达到指导分化的阈值水平。有趣的是，mirn23a还反向调节PI3激酶（PI3K）/Akt和BMP/Smad信号通路。药理学抑制剂研究以及显性激活/显性负性生化实验表明，这两条信号通路对于mirn23a调节造血分化都至关重要。最后，与mirn23a作为B细胞发育的生理抑制剂一致，我们观察到关键的B细胞转录因子EBF1可抑制mirn23a的表达。总之，我们的数据表明mirn23a调节一系列复杂的转录和信号通路，以调节成体造血。
