Murine osteoclasts secrete serine protease HtrA1 capable of degrading osteoprotegerin in the bone microenvironment
Murine osteoclasts secrete serine protease HtrA1 capable of degrading osteoprotegerin in the bone microenvironment
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DOI：
10.1038/s42003-019-0334-5
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发表时间：
2019-03-01
影响因子：
5.9
通讯作者：
Suda, Tatsuo
中科院分区：
文献类型：
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作者：
Ochiai, Nagahiro;Nakachi, Yutaka;Suda, Tatsuo
破骨细胞是负责骨吸收的多核细胞。破骨细胞从骨髓巨噬细胞 (BMM) 的分化是由 NF.B 配体受体激活剂 (RANKL) 诱导的。骨保护素 (OPG) 是 RANKL 的诱饵受体，通过阻断 RANKL 信号传导来抑制破骨细胞生成。在这里，我们研究了 OPG 的体外降解情况。破骨细胞分泌 OPG 降解酶，但 BMM 不分泌 OPG 降解酶。使用质谱和 RNA 测序分析，我们确定高温需求 A 丝氨酸肽酶 1 (HtrA1) 是一种 OPG 降解酶。 HtrA1 不会降解二硫苏糖醇预还原的 OPG，表明 HtrA1 识别 OPG 的三维结构。 HtrA1首先裂解OPG的亮氨酸90和谷氨酰胺91之间的酰胺键，然后将OPG降解成小片段。通过在 RAW 264.7 细胞培养物中添加 HtrA1，可以抑制 OPG 对 RANKL 诱导的破骨细胞生成的抑制活性。这些结果表明破骨细胞可能准备适合破骨细胞生成的微环境。 HtrA1可能是治疗骨质疏松症的新药物靶点。
Osteoclasts are multinucleated cells responsible for bone resorption. The differentiation of osteoclasts from bone marrow macrophages (BMMs) is induced by receptor activator of NF.B ligand (RANKL). Osteoprotegerin (OPG), a decoy receptor of RANKL, inhibits osteoclastogenesis by blocking RANKL signaling. Here we investigated the degradation of OPG in vitro. Osteoclasts, but not BMMs, secreted OPG-degrading enzymes. Using mass spectrometry and RNA-sequencing analysis, we identified high-temperature requirement A serine peptidase 1 (HtrA1) as an OPG-degrading enzyme. HtrA1 did not degrade OPG pre-reduced by dithiothreitol, suggesting that HtrA1 recognizes the three-dimensional structure of OPG. HtrA1 initially cleaved the amide bond between leucine 90 and glutamine 91 of OPG, then degraded OPG into small fragments. Inhibitory activity of OPG on RANKL-induced osteoclastogenesis was suppressed by adding HtrA1 in RAW 264.7 cell cultures. These results suggest that osteoclasts potentially prepare a microenvironment suitable for osteoclastogenesis. HtrA1 may be a novel drug target for osteoporosis.