Mature osteoclast-derived apoptotic bodies promote osteogenic differentiation via RANKL-mediated reverse signaling
Mature osteoclast-derived apoptotic bodies promote osteogenic differentiation via RANKL-mediated reverse signaling
复制标题
成熟破骨细胞衍生的凋亡小体通过 RANKL 介导的反向信号促进成骨分化
DOI：
10.1074/jbc.ra119.007625
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发表时间：
2019-07-19
影响因子：
4.8
通讯作者：
Dou, Ce
中科院分区：
文献类型：
--
作者：
Ma, Qinyu;Liang, Mengmeng;Dou, Ce
在骨重建过程中，破骨细胞在大约2周的寿命后，在每个骨周转周期中都会发生凋亡，从而产生大量的凋亡体(Abs)。然而，破骨细胞衍生的ABS(OC-ABS)在骨重建中的生物学作用尚未被研究，目前仍不清楚。在本研究中，我们用核因子-kappaB受体激活剂(RANKL)刺激骨髓巨噬细胞获得破骨前细胞和成熟破骨细胞(MOCs)。然后，我们用阿伦磷酸钠诱导破骨前细胞和巨噬细胞的凋亡，生成相应的ABS，并用流式细胞仪和免疫印迹技术对提取的ABS的大小和免疫原性进行表征。我们发现MOC-ABS被成骨前细胞MC3T3-E1吞噬，并促进了这些细胞的活性。在所有破骨细胞来源的细胞外小泡中，MOC-ABS成骨能力最高。我们进一步观察到，在所有类型的破骨细胞来源的细胞外小泡中，MOC-ABS具有最高的NF-kappa B囊泡受体激活剂(RANK)水平。值得注意的是，用可溶性RANKL掩蔽泡的等级强烈地取消了破骨细胞来源的ABS的成骨能力。从机制上讲，我们发现MOC-ABS通过激活PI3K/AKT/机械靶标雷帕霉素(MTOR)/核糖体蛋白S6激酶信号来诱导成骨细胞分化。结论：OC-ABS通过激活RANKL反向信号刺激成骨细胞分化，从而促进成骨细胞分化。这些发现为了解骨重建过程中骨吸收和形成阶段之间的逆转阶段提供了重要的见解，并确定了破骨细胞-成骨细胞偶联中依赖AB的细胞信号机制。
In bone remodeling, after a lifespan of similar to 2 weeks, osteoclasts undergo apoptosis in each bone turnover cycle, resulting in generation of a large number of apoptotic bodies (ABs). However, the biological roles of osteoclast-derived ABs (OC-ABs) in bone remodeling have not been investigated and remain unknown. In this study, we stimulated bone marrow macrophages with receptor activator of NF-kappa B ligand (RANKL) to obtain both preosteoclasts and mature osteoclasts (mOCs). We then used alendronate to induce apoptosis in preosteoclasts and mOCs and generate the respective ABs and used flow cytometry and immunoblotting to characterize the sizes and immunogenic characteristics of the extracted ABs. We show that mOC-ABs are engulfed by preosteoblastic MC3T3-E1 cells and promote the viability of these cells. Among all osteoclast-derived extracellular vesicles, mOC-ABs had the highest osteogenic potency. We further observed that mOC-ABs had the highest vesicular receptor activator of NF-kappa B (RANK) levels among all types of osteoclast-derived extracellular vesicles. Of note, masking of vesicular RANK by soluble RANKL strongly abolished the osteogenic potency of osteoclast-derived ABs. Mechanistically, we found that mOC-ABs induce osteoblast differentiation by activatingPI3K/AKT/mechanistic target of rapamycin (mTOR)/ribosomal protein S6 kinase signaling. In conclusion, OC-ABs promote osteogenic differentiation by stimulating osteoblast differentiation via activation of RANKL reverse signaling. These findings provide important insights into the reversal phase between the bone resorption and formation stages during bone remodeling and identify an AB-dependent cellular signaling mechanism in osteoclast-osteoblast coupling.