Oujiang Laboratory (Zhejiang Lab for Regenerative Medicine, Vision and Brain Health), Department of Orthopaedics, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, 325027, China.
Molecular Pharmacology Research Center, School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, 325035, China.
Acta Pharmacol Sin. 2023 Mar;44(3):610-621. doi: 10.1038/s41401-022-00967-7. Epub 2022 Aug 25.
Mitochondrial dynamics, including mitochondrial fission and fusion, are critical for maintaining mitochondrial functions. Evidence shows that TANK-binding kinase 1 (TBK1) regulates mitochondrial fusion and fission and then mitophagy. Since a previous study demonstrates a strong correlation between mitophagy and osteoarthritis (OA), we herein investigated the potential role of TBK1 in OA process and mitochondrial functions. We demonstrated a strong correlation between TBK1 and OA, evidenced by significantly downregulated expression of TBK1 in cartilage tissue samples of OA patients and in the chondrocytes of aged mice, as well as TNF-α-stimulated phosphorylation of TBK1 in primary mouse chondrocytes. TBK1 overexpression significantly attenuated TNF-α-induced apoptosis and abnormal mitochondrial function in primary mouse chondrocytes. Furthermore, TBK1 overexpression induced remodeling of mitochondrial morphology by directly phosphorylating dynamin-related protein 1 (DRP1) at Ser637, abolishing the fission of DRP1 and preventing its fragmentation function. Moreover, TBK1 recruitment and DRP1 phosphorylation at Ser637 was necessary for engulfing damaged mitochondria by autophagosomal membranes during mitophagy. Moreover, we demonstrated that APMK/ULK1 signaling contributed to TBK1 activation. In OA mouse models established by surgical destabilization of the medial meniscus, intraarticular injection of lentivirus-TBK1 significantly ameliorated cartilage degradation via regulation of autophagy and alleviation of cell apoptosis. In conclusion, our results suggest that the TBK1/DRP1 pathway is involved in OA and pharmacological targeting of the TBK1-DRP1 cascade provides prospective therapeutic benefits for the treatment of OA.
线粒体动力学，包括线粒体的分裂和融合，对于维持线粒体功能至关重要。有证据表明，TANK 结合激酶 1（TBK1）调节线粒体的融合和分裂，进而调节线粒体自噬。由于之前的研究表明线粒体自噬与骨关节炎（OA）之间存在很强的相关性，因此我们在此研究了 TBK1 在 OA 进程和线粒体功能中的潜在作用。我们发现 TBK1 与 OA 之间存在很强的相关性，这一点从 OA 患者的软骨组织样本和老年小鼠的软骨细胞中 TBK1 的表达显著下调，以及 TNF-α刺激的原代小鼠软骨细胞中 TBK1 的磷酸化得到了证实。TBK1 的过表达显著减轻了 TNF-α诱导的原代小鼠软骨细胞凋亡和异常线粒体功能。此外，TBK1 的过表达通过直接在 Ser637 上磷酸化动力相关蛋白 1（DRP1），诱导线粒体形态重塑，从而阻止 DRP1 的分裂及其分裂功能。此外，TBK1 的募集和 DRP1 在 Ser637 的磷酸化对于受损线粒体在自噬体膜中被吞噬至关重要。此外，我们证明了 APMK/ULK1 信号通路有助于 TBK1 的激活。在通过内侧半月板手术不稳定建立的 OA 小鼠模型中，关节内注射携带 TBK1 的慢病毒显著通过调节自噬和减轻细胞凋亡来改善软骨降解。总之，我们的研究结果表明，TBK1/DRP1 通路参与 OA，TBK1-DRP1 级联的药理学靶向为 OA 的治疗提供了有前景的治疗益处。
