Kurkewich Jeffrey L, Boucher Austin, Klopfenstein Nathan, Baskar Ramdas, Kapur Reuben, Dahl Richard
Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, USA; Harper Cancer Research Institute, South Bend, IN, USA.
Harper Cancer Research Institute, South Bend, IN, USA; Department of Microbiology and Immunology, Indiana University School of Medicine, South Bend, IN, USA.
Exp Hematol. 2018 Mar;59:14-29. doi: 10.1016/j.exphem.2017.12.007. Epub 2017 Dec 27.
Mice deficient for microRNA (miRNA) cluster mirn23a exhibit increased B lymphopoiesis at the expense of myelopoiesis, whereas hematopoietic stem and progenitor cell (HSPC) populations are unchanged. Mammals possess a paralogous mirn23b gene that can give rise to three mature miRNAs (miR-23b, miR-24-1, and miR-27b) that have identical seed/mRNA-targeting sequences to their mirn23a counterparts. To assess whether compound deletion of mirn23a and mirn23b exacerbates the hematopoietic phenotype observed in mirn23a mice, we generated a compound mirn23amirn23b:Mx1-Cre conditional knockout mouse and assayed hematopoietic development after excision of mirn23b. Loss of both genes in adult bone marrow further skewed HSPC differentiation toward B cells at the expense of myeloid cells, demonstrating a dosage-dependent effect on regulating cell differentiation. Strikingly, double-knockout (DKO) mice had decreased bone marrow cellularity with significantly decreased hematopoietic stem cell and HSPC populations, a phenotype not observed in mice deficient for mirn23a alone. Competitive transplantation assays showed decreased contribution of mirn23amirn23b HSPCs to hematopoietic lineages at 6 and 12 weeks after transplantation. Defects in the proliferation of mirn23ab HSPCs was not observed; however, DKO cells were more apoptotic compared with both wild-type and mirn23a cells. Together, our data show that complete loss of mirn23a/mirn23b miRNAs results in decreased blood production and affects lineage output in a concentration-dependent manner.
缺乏微小RNA（miRNA）簇mirn23a的小鼠，其B淋巴细胞生成增加，代价是髓细胞生成减少，而造血干细胞和祖细胞（HSPC）群体未发生变化。哺乳动物拥有一个同源的mirn23b基因，它可产生三种成熟的miRNA（miR - 23b、miR - 24 - 1和miR - 27b），它们与mirn23a对应的miRNA具有相同的种子序列/靶向mRNA序列。为了评估mirn23a和mirn23b的复合缺失是否会加剧在mirn23a小鼠中观察到的造血表型，我们构建了一种复合mirn23a/mirn23b:Mx1 - Cre条件性敲除小鼠，并在切除mirn23b后检测造血发育情况。成年骨髓中这两个基因的缺失进一步使HSPC分化偏向B细胞，以髓系细胞为代价，表明对调节细胞分化存在剂量依赖性效应。令人惊讶的是，双敲除（DKO）小鼠的骨髓细胞数量减少，造血干细胞和HSPC群体显著减少，这是单独缺乏mirn23a的小鼠未观察到的表型。竞争性移植试验表明，移植后6周和12周，mirn23a/mirn23b HSPC对造血谱系的贡献减少。未观察到mirn23a/b HSPC增殖存在缺陷；然而，与野生型和mirn23a细胞相比，DKO细胞的凋亡更多。总之，我们的数据表明，mirn23a/mirn23b miRNA的完全缺失导致血液生成减少，并以浓度依赖的方式影响谱系输出。
