METHODS: We initially validated the in vivo efficacy of TCG in alleviating OA using a rat OA model. Subsequently, we isolated primary bone marrow-derived macrophages in vitro to investigate TCG\'s impact on osteoclastogenesis. We further employed a small molecule pull-down assay to verify TCG\'s binding target within osteoclasts. Finally, we isolated primary mouse chondrocytes in vitro to study TCG\'s regulatory effects and mechanisms on chondrocyte survival.
RESULTS: TCG preserved subchondral bone integrity and protected articular cartilage in a rat OA model. Subsequently, in vitro experiments unveiled TCG\'s capability to inhibit osteoclastogenesis and function through binding to Ras association proximate 1 (Rap1) and inhibiting its activation. Further study demonstrated that TCG inhibited Rap1/integrin αvβ3/c-Src/Pyk2 signaling cascade, and consequently led to failed F-actin ring formation. Besides, TCG promoted the proliferation of mouse primary chondrocytes while suppressing apoptosis in vitro. This is attributed to TCG\'s ability to upregulate HIF1α, thereby promoting glycolysis.
CONCLUSIONS: TCG exerted inhibitory effects on osteoclastogenesis through binding to Rap1 and inhibiting Rap1 activation, consequently preventing subchondral bone loss. Moreover, TCG enhanced chondrocyte survival by upregulating HIF1α and promoting glycolysis. These dual mechanisms collectively provide a novel approach to prevented against cartilage degradation.
方法:我们最初使用大鼠OA模型验证了TCG减轻OA的体内功效。随后,我们在体外分离原代骨髓来源的巨噬细胞,以研究TCG对破骨细胞生成的影响。我们进一步采用小分子下拉测定法来验证破骨细胞内TCG的结合靶标。最后,我们在体外分离原代小鼠软骨细胞,以研究TCG对软骨细胞存活的调节作用和机制。
结果:TCG在大鼠OA模型中保留了软骨下骨的完整性并保护了关节软骨。随后,体外实验揭示了TCG通过与Ras缔合近邻1(Rap1)结合并抑制其激活来抑制破骨细胞生成和功能的能力。进一步研究表明TCG抑制Rap1/整合素αvβ3/c-Src/Pyk2信号级联,并因此导致F-肌动蛋白环形成失败。此外,TCG在体外促进小鼠原代软骨细胞增殖的同时抑制细胞凋亡。这归因于TCG上调HIF1α的能力,从而促进糖酵解。
结论:TCG通过与Rap1结合并抑制Rap1激活对破骨细胞生成有抑制作用,从而防止软骨下骨丢失。此外,TCG通过上调HIF1α和促进糖酵解来增强软骨细胞的存活。这些双重机制共同提供了防止软骨退化的新方法。