The Keap1/Nrf2 protein axis plays a role in osteoclast differentiation by regulating intracellular reactive oxygen species signaling.
The Keap1/Nrf2 protein axis plays a role in osteoclast differentiation by regulating intracellular reactive oxygen species signaling.
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DOI：
10.1074/jbc.m113.478545
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发表时间：
2013-08-09
期刊：
影响因子：
--
通讯作者：
Kodama T
中科院分区：
文献类型：
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作者：
Kanzaki H;Shinohara F;Kajiya M;Kodama T
背景：核因子 E2 相关因子 2 (Nrf2) 是细胞保护酶的主要调节因子。结果：Nrf2 过表达介导的细胞保护酶的增强通过细胞内 ROS 减弱阻断 RANKL 信号传导，从而阻止骨破坏。结论：Nrf2依赖性细胞保护酶表达通过控制细胞内ROS在破骨细胞生成的调节中发挥作用。意义：Keap1/Nrf2 轴可能成为治疗骨破坏性疾病的新治疗靶点。活性氧 (ROS) 在调节核因子 κB 配体受体激活剂 (RANKL) 依赖性破骨细胞分化过程中充当细胞内信号分子，但它们也具有细胞毒性作用，包括脂质过氧化以及蛋白质和 DNA 的氧化损伤。针对氧化应激的细胞保护机制包括转录因子核因子 E2 相关因子 2 (Nrf2) 对细胞保护酶的转录控制。本研究调查了 Nrf2 与破骨细胞生成之间的关系。用 RANKL 刺激破骨细胞前体（小鼠原代腹膜巨噬细胞和 RAW 264.7 细胞）导致 kelch 样 ECH 相关蛋白 1 (Keap1)（Nrf2 的负调节因子）上调。它还降低了 Nrf2/Keap1 比率，并下调了细胞保护酶（血红素加氧酶-1、γ-谷氨酰半胱氨酸合成酶和葡萄糖-6-磷酸脱氢酶）。 Nrf2过表达上调细胞保护酶的表达，降低ROS水平，减少抗酒石酸酸性磷酸酶阳性多核细胞的数量，减少破骨细胞分化的标记基因，并减轻体外和体内模型中的骨破坏。 Keap1 的过度表达或 Nrf2 的 RNAi 敲低发挥了相反的作用。此外，体内局部 Nrf2 过表达减弱了脂多糖介导的 RANKL 依赖性颅骨破坏。这是第一项研究表明 Keap1/Nrf2 轴通过细胞保护酶的表达调节细胞内 ROS 信号传导来调节 RANKL 依赖性破骨细胞生成。这提出了令人兴奋的可能性，即 Keap1-Nrf2 轴可能成为治疗骨破坏性疾病的治疗靶点。
Background: Nuclear factor E2-related factor 2 (Nrf2) is a master regulator of cytoprotective enzymes. Results: Nrf2 overexpression-mediated cytoprotective enzymes' augmentation blocked RANKL signaling via intracellular ROS attenuation and thereby blocked bone destruction. Conclusion: Nrf2-dependent cytoprotective enzyme expressions play a role in the regulation of osteoclastogenesis by controlling intracellular ROS. Significance: The Keap1/Nrf2 axis could be a novel therapeutic target for the treatment of bone destructive disease. Reactive oxygen species (ROS) act as intracellular signaling molecules in the regulation of receptor activator of nuclear factor-κB ligand (RANKL)-dependent osteoclast differentiation, but they also have cytotoxic effects that include peroxidation of lipids and oxidative damage to proteins and DNA. Cellular protective mechanisms against oxidative stress include transcriptional control of cytoprotective enzymes by the transcription factor, nuclear factor E2-related factor 2 (Nrf2). This study investigated the relationship between Nrf2 and osteoclastogenesis. Stimulation of osteoclast precursors (mouse primary peritoneal macrophages and RAW 264.7 cells) with RANKL resulted in the up-regulation of kelch-like ECH-associated protein 1 (Keap1), a negative regulator of Nrf2. It also decreased the Nrf2/Keap1 ratio, and it down-regulated cytoprotective enzymes (heme oxygenase-1, γ-glutamylcysteine synthetase, and glucose-6-phosphate dehydrogenase). Nrf2 overexpression up-regulated the expression of cytoprotective enzymes, decreased ROS levels, decreased the number of tartrate-resistant acid phosphatase-positive multinucleated cells, reduced marker genes for osteoclast differentiation, and attenuated bone destruction in both in vitro and in vivo models. Overexpression of Keap1 or RNAi knockdown of Nrf2 exerted the opposite actions. In addition, in vivo local Nrf2 overexpression attenuated lipopolysaccharide-mediated RANKL-dependent cranial bone destruction in vivo. This is the first study to show that the Keap1/Nrf2 axis regulates RANKL-dependent osteoclastogenesis through modulation of intracellular ROS signaling via expression of cytoprotective enzymes. This raises the exciting possibility that the Keap1-Nrf2 axis may be a therapeutic target for the treatment of bone destructive disease.