Department of Orthopedics, Guangdong Provincial Second Hospital of Traditional Chinese Medicine, Guangzhou, 510095, China.
The Fifth Clinical College of Guangzhou, University of Chinese Medicine, Guangzhou, 510405, China.
Arthritis Res Ther. 2023 Apr 1;25(1):53. doi: 10.1186/s13075-023-03035-5.
Increasing evidence have demonstrated the N6-methyladenosine (mA) plays critical roles in osteoarthritis (OA) progression, but the role of mA in OA has not been completely illuminated. Herein, we investigated the function and underlying mechanism of mA demethylase fat mass and obesity-associated protein (FTO) in OA progression.
The FTO expression was detected in mice OA cartilage tissues and lipopolysaccharide (LPS)-stimulated chondrocytes. Gain-of-function assays was used to evaluate the role of FTO in OA cartilage injury in vitro and in vivo. The miRNA-sequencing, RNA-binding protein immunoprecipitation (RIP), luciferase reporter assay, and in vitro pri-miRNA processing assays were conducted to confirm that FTO modulated the pri-miR-3591 process in an m6A-dependent manner and then the binding sites of miR-3591-5p with PRKAA2.
FTO was outstandingly downregulated in LPS-stimulated chondrocytes and OA cartilage tissues. FTO overexpression enhanced the proliferation, suppressed apoptosis, and decreased degradation of extracellular matrix in LPS-induced chondrocytes, whereas FTO knockdown contributed to the opposite effects. In vivo animal experiments showed that FTO overexpression markedly alleviated OA mice cartilage injury. Mechanically, FTO-mediated m6A demethylation of pri-miR-3591 leaded to a maturation block of miR-3591-5p, which relieved the inhibitory effect of miR-3591-5p on PRKAA2 and then promoted the increase of PRKAA2, thereby alleviating OA cartilage damage.
Our results attested that FTO alleviated the OA cartilage damage by mediating FTO/miR-3591-5p/PRKAA2 axis, which provided fresh insights into the therapeutic strategies for OA.
越来越多的证据表明 N6-甲基腺苷（mA）在骨关节炎（OA）进展中发挥着关键作用，但 mA 在 OA 中的作用尚未完全阐明。本文研究了 mA 去甲基酶脂肪量和肥胖相关蛋白（FTO）在 OA 进展中的功能和作用机制。
检测 FTO 在小鼠 OA 软骨组织和脂多糖（LPS）刺激的软骨细胞中的表达。采用功能获得性实验评估 FTO 在体外和体内 OA 软骨损伤中的作用。进行 miRNA 测序、RNA 结合蛋白免疫沉淀（RIP）、荧光素酶报告基因测定和体外 pri-miRNA 加工实验，以确认 FTO 以 m6A 依赖性方式调节 pri-miR-3591 的加工，然后是 miR-3591-5p 与 PRKAA2 的结合位点。
FTO 在 LPS 刺激的软骨细胞和 OA 软骨组织中显著下调。FTO 过表达增强了 LPS 诱导的软骨细胞的增殖，抑制了凋亡，减少了细胞外基质的降解，而 FTO 敲低则产生相反的效果。体内动物实验表明，FTO 过表达显著减轻 OA 小鼠软骨损伤。机制上，FTO 介导的 pri-miR-3591 的 m6A 去甲基化导致 miR-3591-5p 的成熟受阻，减轻了 miR-3591-5p 对 PRKAA2 的抑制作用，从而促进了 PRKAA2 的增加，从而减轻了 OA 软骨损伤。
我们的研究结果表明，FTO 通过调节 FTO/miR-3591-5p/PRKAA2 轴缓解 OA 软骨损伤，为 OA 的治疗策略提供了新的见解。
