Xia Duo, Yu Chun, Zhou Xuan-Ping, Huang Lei, Yang Shu
Department of Orthopedics, Hunan Provincial People's Hospital (The First-Affiliated Hospital of Hunan Normal University), Changsha, Hunan Province, People's Republic of China.
Clinical Research Center of Sports Medicine in Hunan Province, Changsha, Hunan Province, People's Republic of China.
FASEB J. 2025 Aug 31;39(16):e70953. doi: 10.1096/fj.202500241R.
Osteoarthritis (OA) is a common joint disease, and chondrocyte extracellular matrix (ECM) degradation was closely associated with its progression. This study investigated the regulatory mechanisms of ECM degradation during OA development. A rat model of OA was established by anterior cruciate ligament transection (ACL-T) and interleukin-1 beta (IL-1β)-stimulated rat chondrocytes were used to simulate OA in vitro. Cartilage damage was evaluated by hematoxylin-eosin (HE) and safranin O-fast green staining. The ECM content in chondrocytes was assessed by alcian blue staining. Real-time quantitative PCR (RT-qPCR), Western Blotting, immunohistochemical staining, and immunofluorescent staining were adopted to analyze associated molecule expression. Molecular mechanisms were elucidated by Co-immunoprecipitation (Co-IP) and GST pull-down assay. We found that Aurora kinase A (AURKA), p-eukaryotic translation initiation factor 4E (eIF4E), and ADAM metallopeptidase with thrombospondin type 1 motif 12 (ADAMTS12) levels were elevated in the human and rat cartilage tissues of OA, as well as IL-1β-exposed chondrocytes. AURKA inhibition restrained ECM degradation to relieve OA via down-regulation of ADAMTS12. AURKA overexpression phosphorylated eIF4E, which promoted cap-dependent translation of ADAMTS12. Moreover, DNA methyltransferase 1 (DNMT1)-mediated methylation down-regulated HECT domain E3 ubiquitin protein ligase 1 (HECTD1) in the OA model and consequently enhanced AURKA expression via inhibiting its ubiquitination. HECTD1 knockdown or ubiquitination repression intensified ECM degradation in IL-1β-stimulated chondrocytes. Taken together, low expression of HECTD1 repressed AURKA ubiquitination to elevate AURKA protein level and subsequently facilitated eIF4E-mediated cap-dependent translation of ADAMTS12, thus resulting in ECM degradation during OA progression.
骨关节炎（OA）是一种常见的关节疾病，软骨细胞外基质（ECM）降解与其进展密切相关。本研究调查了OA发展过程中ECM降解的调控机制。通过前交叉韧带横断（ACL-T）建立OA大鼠模型，并使用白细胞介素-1β（IL-1β）刺激的大鼠软骨细胞在体外模拟OA。通过苏木精-伊红（HE）和番红O-固绿染色评估软骨损伤。通过阿尔辛蓝染色评估软骨细胞中的ECM含量。采用实时定量PCR（RT-qPCR）、蛋白质免疫印迹、免疫组织化学染色和免疫荧光染色分析相关分子表达。通过免疫共沉淀（Co-IP）和谷胱甘肽S-转移酶（GST）下拉试验阐明分子机制。我们发现，在OA的人及大鼠软骨组织以及IL-1β处理的软骨细胞中，极光激酶A（AURKA）、磷酸化真核翻译起始因子4E（eIF4E）和含血小板反应蛋白基序的金属蛋白酶12（ADAMTS12）水平升高。抑制AURKA可通过下调ADAMTS12来抑制ECM降解，从而缓解OA。AURKA过表达使eIF4E磷酸化，促进ADAMTS12的帽依赖性翻译。此外，在OA模型中，DNA甲基转移酶1（DNMT1）介导的甲基化下调了HECT结构域E3泛素蛋白连接酶1（HECTD1），从而通过抑制其泛素化增强了AURKA表达。敲低HECTD1或抑制泛素化会加剧IL-1β刺激的软骨细胞中的ECM降解。综上所述，HECTD1低表达抑制AURKA泛素化，提高AURKA蛋白水平，随后促进eIF4E介导的ADAMTS12帽依赖性翻译，从而在OA进展过程中导致ECM降解。
