破骨细胞谱系的定型和分化已被广泛研究,尽管转录因子控制破骨细胞终末分化的机制,激活,功能尚不清楚。据报道,CCAAT/增强子结合蛋白α(C/ebpα)是破骨细胞谱系定型的关键调节因子,然而C/ebpα在破骨细胞终末分化中的作用,激活和功能,和骨骼稳态,在生理或病理条件下,尚未进行研究,因为新生的C/ebpα-null小鼠在出生后数小时内死亡。此外,C/ebpα在破骨细胞终末分化中的作用,激活,功能在很大程度上是未知的。在这里,我们通过Ctsk-Cre小鼠产生并分析了破骨细胞特异性C/ebpα条件敲除(CKO)小鼠模型,发现C/ebpα缺陷小鼠由于破骨细胞终末分化受损而表现出严重的骨硬化表型。激活,和功能,包括破骨细胞数量轻度减少,破骨细胞极化受损,肌动蛋白形成,和骨吸收,证明了C/ebpα在细胞功能和终末分化中的新功能。有趣的是,C/ebpα缺乏不影响骨形成或单核细胞/巨噬细胞发育。我们的结果进一步证明,C/ebpα缺乏症抑制了破骨细胞功能基因的表达,例如,编码组织蛋白酶K(Ctsk),Atp6i(Tcirg1),和破骨细胞调节基因,例如,编码c-fos(Fos),和活化T细胞核因子1(Nfatc1),而对Pu.1(Spi1)表达无影响。启动子活性作图和ChIP测定定义了Nfatc1启动子区域的关键顺式调节元件(CCRE),并显示CCRE与C/ebpα直接相关,这增强了启动子的活性。破骨细胞中C/ebpα的缺乏完全阻断了卵巢切除术引起的骨丢失,表明C/ebpα是治疗溶骨性疾病的有希望的新靶点。版权所有©2017年英国和爱尔兰病理学会。由JohnWiley&Sons出版,Ltd.
Osteoclast lineage commitment and differentiation have been studied extensively, although the mechanism by which transcription factor(s) control osteoclast terminal differentiation, activation, and function remains unclear. CCAAT/enhancer-binding protein α (C/ebpα) has been reported to be a key regulator of osteoclast cell lineage commitment, yet C/ebpα\'s roles in osteoclast terminal differentiation, activation and function, and bone homeostasis, under physiological or pathological conditions, have not been studied because newborn C/ebpα-null mice die within several hours after birth. Furthermore, the function of C/ebpα in osteoclast terminal differentiation, activation, and function is largely unknown. Herein, we generated and analyzed an osteoclast-specific C/ebpα conditional knockout (CKO) mouse model via Ctsk-Cre mice and found that C/ebpα-deficient mice exhibited a severe osteopetrosis phenotype due to impaired osteoclast terminal differentiation, activation, and function, including mildly reduced osteoclast number, impaired osteoclast polarization, actin formation, and bone resorption, which demonstrated the novel function of C/ebpα in cell function and terminal differentiation. Interestingly, C/ebpα deficiency did not affect bone formation or monocyte/macrophage development. Our results further demonstrated that C/ebpα deficiency suppressed the expression of osteoclast functional genes, e.g. encoding cathepsin K (Ctsk), Atp6i (Tcirg1), and osteoclast regulator genes, e.g. encoding c-fos (Fos), and nuclear factor of activated T-cells 1 (Nfatc1), while having no effect on Pu.1 (Spi1) expression. Promoter activity mapping and ChIP assay defined the critical cis-regulatory element (CCRE) in the promoter region of Nfatc1, and also showed that the CCREs were directly associated with C/ebpα, which enhanced the promoter\'s activity. The deficiency of C/ebpα in osteoclasts completely blocked ovariectomy-induced bone loss, indicating that C/ebpα is a promising new target for the treatment of osteolytic diseases. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.