Oral and Craniofacial Health Science Institute, School of Dentistry, UNC at Chapel Hill, North Carolina, NC, USA.
Division of Orthodontics, The Ohio State University College of Dentistry, Columbus, OH, 43210, USA.
Exp Mol Med. 2021 Apr;53(4):667-680. doi: 10.1038/s12276-021-00596-w. Epub 2021 Apr 16.
Abnormally increased resorption contributes to bone degenerative diseases such as Paget's disease of bone (PDB) through unclear mechanisms. Recently, the optineurin (OPTN) gene has been implicated in PDB, and global OPTN knockout mice (Optn) were shown to exhibit increased formation of osteoclasts (osteoclastogenesis). Growing evidence, including our own, has demonstrated that intracellular reactive oxygen species (ROS) stimulated by receptor activator of nuclear factor kappa-B ligand (RANKL) can act as signaling molecules to promote osteoclastogenesis. Here, we report that OPTN interacts with nuclear factor erythroid-derived factor 2-related factor 2 (NRF2), the master regulator of the antioxidant response, defining a pathway through which RANKL-induced ROS could be regulated for osteoclastogenesis. In this study, monocytes from Optn and wild-type (Optn) mice were utilized to differentiate into osteoclasts, and both qRT-PCR and tartrate-resistant acid phosphatase (TRAP) staining showed that the Optn monocytes exhibited enhanced osteoclastogenesis compared to the Optn cells. CellROX staining, qRT-PCR, and Western blotting indicated that OPTN deficiency reduced the basal expression of Nrf2, inhibited the expression of NRF2-responsive antioxidants, and increased basal and RANKL-induced intracellular ROS levels, leading to enhanced osteoclastogenesis. Coimmunoprecipitation (co-IP) showed direct interaction, and immunofluorescence staining showed perinuclear colocalization of the OPTN-NRF2 granular structures during differentiation. Finally, curcumin and the other NRF2 activators attenuated the hyperactive osteoclastogenesis induced by OPTN deficiency. Collectively, our findings reveal a novel OPTN-mediated mechanism for regulating the NRF2-mediated antioxidant response in osteoclasts and extend the therapeutic potential of OPTN in the aging process resulting from ROS-triggered oxidative stress, which is associated with PDB and many other degenerative diseases.
异常增加的吸收作用通过不清楚的机制有助于诸如 Pagets 骨病(PDB)等骨骼退行性疾病。最近,optineurin(OPTN)基因已被牵连到 PDB 中,并且已经表明全球 OPTN 敲除小鼠(Optn)表现出破骨细胞(破骨细胞形成)的形成增加。越来越多的证据,包括我们自己的证据,已经表明核因子 kappa-B 配体(RANKL)刺激的细胞内活性氧(ROS)可以作为信号分子来促进破骨细胞形成。在这里,我们报告 OPTN 与核因子红细胞衍生因子 2 相关因子 2(NRF2)相互作用,NRF2 是抗氧化反应的主要调节剂,定义了一条途径,通过该途径可以调节 RANKL 诱导的 ROS 以用于破骨细胞形成。在这项研究中,利用 Optn 和野生型(Optn)小鼠的单核细胞分化为破骨细胞,qRT-PCR 和抗酒石酸酸性磷酸酶(TRAP)染色均表明 Optn 单核细胞比 Optn 细胞表现出增强的破骨细胞形成。CellROX 染色,qRT-PCR 和 Western blot 表明 OPTN 缺乏降低了 Nrf2 的基础表达,抑制了 NRF2 反应性抗氧化剂的表达,并增加了基础和 RANKL 诱导的细胞内 ROS 水平,从而导致破骨细胞形成增强。共免疫沉淀(co-IP)显示直接相互作用,免疫荧光染色显示分化过程中 OPTN-NRF2 颗粒结构的核周共定位。最后,姜黄素和其他 NRF2 激活剂减弱了 OPTN 缺乏引起的破骨细胞过度活跃形成。总之,我们的发现揭示了一种新型 OPTN 介导的机制,用于调节破骨细胞中的 NRF2 介导的抗氧化反应,并扩展了 OPTN 在由 ROS 触发的氧化应激引起的衰老过程中的治疗潜力,这与 PDB 和许多其他退行性疾病有关。
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