Osteoarthritis (OA) is a degenerative joint disease that affects the cartilage and surrounding tissues. The transcription factor Kruppel-like family factor 9 (KLF9) has been identified as a regulator of tumorigenesis. However, its role in OA is still not fully understood. Herein, this study aimed to access the potential role and molecular mechanism by which KLF9 regulates OA development. KLF9 was upregulated in cartilage tissues of OA patients and medial meniscotibial ligament (MMTL)-induced OA rats, as well as in IL-1β-treated chondrocytes. Furthermore, knockdown of KLF9 inhibited OA-related cartilage injury, as evidenced by inhibiting chondrocyte extracellular matrix (ECM) degradation, increasing chondrocyte viability, and decreasing apoptosis. Conversely, overexpression of KLF9 had the opposite effect. The downstream mechanism of KLF9 was confirmed. KLF9 mediated the transcription of G protein-coupled receptor kinase 5 (GRK5) by directly targeting the GRK5 promoter. GRK5 knockdown eliminated the effects of KLF9 overexpression on chondrocyte dysfunction. It was also found that GRK5 combined with histone deacetylase 6 (HDAC6) and promoted HDAC6 phosphorylation. The use of the HDAC6 inhibitor TubastatinA also abolished the effects of GRK5 overexpression on chondrocyte ECM degradation and apoptosis. These results demonstrate that the KLF9-GRK5-HDAC6 axis plays a crucial role in promoting the progression of OA.
Yilin Huang,Huan Ru,Chanlin Fang,Shanshan Di,You Weng,Mingrong Qian,Yuanxiang Jin
Abstract 6PPD, as an antioxidant in tire rubber, constitutes an emerging pollutant together with nanoplastics (NPs) widely present in the environment. This study explored the potential combined toxicity risk of 6PPD and 50 nm polystyrene nanoplastics (PS-NPs) to aquatic ecosystems. The study found that the presence of PS-NPs altered the physicochemical behavior of 6PPD and was associated with reduced cardiac accumulation of 6PPD and its oxidation product 6PPD-Q. The experiment showed that 6PPD activated the p53 signaling pathway by upregulating the expression of GRK5, thereby inhibiting the expression of SLC7A11 and GPX4, leading to increased ROS, iron overload, lipid peroxidation, and mitochondrial damage in zebrafish heart and rat cardiomyocytes (H9C2), thereby triggering ferroptosis. After coexposure of PS-NPs and 6PPD, physicochemical interactions between PS-NPs and 6PPD altered the colloidal state and environmental behavior of the mixture, while the cardiac levels of both 6PPD and 6PPD-Q were reduced, accompanied by weakened ferroptosis-related responses. This study revealed the cardiotoxic mechanism of 6PPD and the mitigation effect of PS-NPs after coexposure, providing a basis for environmental pollution risk assessment.
危险品化学品经营许可证（带存储）