Hospital of Stomatology, Guanghua School of Stomatology, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Stomatology, Guangzhou, 510055, China.
Arch Biochem Biophys. 2022 Dec 15;732:109464. doi: 10.1016/j.abb.2022.109464. Epub 2022 Nov 8.
Abnormal increases in osteoclast differentiation and activity contribute to excessive bone resorption in inflammatory bone diseases. The specific mA-binding protein YT521-B homology domain family 1 (YTHDF1) participates in many physiopathological processes by regulating mRNA stability or translation. However, whether YTHDF1 is involved in the regulation of inflammatory osteoclastogenesis remains a mystery. This study revealed that YTHDF1 expression was upregulated during lipopolysaccharide (LPS)-stimulated osteoclast differentiation. Knockdown of Ythdf1 inhibited osteoclast formation, bone resorption and the expression of osteoclast-related genes (Tnfrsf11a, Traf6, Mmp9 and Acp5). Analysis of RNA sequencing data showed that the genes downregulated by Ythdf1 knockdown were closely associated with endoplasmic reticulum (ER) stress and osteoclast differentiation. Western blotting confirmed that Ythdf1 depletion suppressed activation of the ER stress-related PERK, IRE1α and ATF6 signaling pathways. The ER stress activator tunicamycin (Tm) partially rescued the decreased expression of Mmp9 and Acp5 caused by Ythdf1 deficiency. Meanwhile, Ythdf1 depletion inhibited the phosphorylation levels of key proteins in the NF-κB, MAPK and PI3K-AKT signaling pathways and decreased the mRNA stability of Tnfrsf11a, which is the major upstream signaling molecule that mediates the activation of these pathways during osteoclast differentiation. In conclusion, our findings suggest that Ythdf1 knockdown inhibits inflammatory osteoclast differentiation and function by suppressing ER stress signaling pathways. Ythdf1 knockdown also inactivates the signaling pathways involved in osteoclast differentiation by inhibiting Tnfrsf11a mRNA stability. These findings will help shed light on the molecular mechanisms of mA-mediated epigenetic regulation in inflammatory osteoclastogenesis.
破骨细胞分化和活性的异常增加导致炎症性骨病中骨吸收过度。特定的 mA 结合蛋白 YT521-B 同源结构域家族 1（YTHDF1）通过调节 mRNA 稳定性或翻译参与许多生理病理过程。然而，YTHDF1 是否参与炎症性破骨细胞发生的调节仍然是一个谜。本研究表明，YTHDF1 的表达在脂多糖（LPS）刺激的破骨细胞分化过程中上调。Ythdf1 敲低抑制破骨细胞形成、骨吸收和破骨细胞相关基因（Tnfrsf11a、Traf6、Mmp9 和 Acp5）的表达。RNA 测序数据分析表明，Ythdf1 敲低下调的基因与内质网（ER）应激和破骨细胞分化密切相关。Western blot 证实，Ythdf1 耗竭抑制 ER 应激相关 PERK、IRE1α 和 ATF6 信号通路的激活。ER 应激激活剂衣霉素（Tm）部分挽救了 Ythdf1 缺乏引起的 Mmp9 和 Acp5 表达下调。同时，Ythdf1 耗竭抑制 NF-κB、MAPK 和 PI3K-AKT 信号通路中关键蛋白的磷酸化水平，并降低 Tnfrsf11a 的 mRNA 稳定性，Tnfrsf11a 是介导破骨细胞分化过程中这些通路激活的主要上游信号分子。总之，我们的研究结果表明，Ythdf1 敲低通过抑制 ER 应激信号通路抑制炎症性破骨细胞分化和功能。Ythdf1 敲低还通过抑制 Tnfrsf11a mRNA 稳定性使参与破骨细胞分化的信号通路失活。这些发现将有助于揭示 mA 介导的表观遗传调控在炎症性破骨细胞发生中的分子机制。
