To explore the role of low expression of Pitx1 in degenerative cartilage tissue. A cartilage injury model was established by using the cartilage scratch method. The newly generated tissue by BrdU labeled in injured cartilage region expressed SOX-9 and Col2A1 in 5-week-old rats. Compared with that, the number of BrdU-positive cells was lower in 4-month-old cartilage injury model rats. Compared with that in lateral cartilage, the expression of Pitx1 was lower in medial cartilage. Compared with chondrocytes derived from the lateral cartilage, chondrocytes derived from the medial cartilage exhibited significantly increased cell aging, as determined by SA-β-GAL staining; downregulated Pitx1 expression; reduced autophagy levels; and decreased Col2A1 expression in a chondrogenic differentiation assay. Inhibition of Pitx1 expression in chondrocytes from the lateral cartilage significantly increased the ratio of cell senescence. Overexpression of Pitx1 in chondrocytes derived from the medial cartilage decreased the cell senescence ratio. In a luciferase assay, Pitx1 was found to promote Sirt1 gene transcription. Decreased Pitx1 expression is an essential cause of cartilage degeneration in the medial tibial plateau. The described self-controlled model is an excellent way to study OA etiology and screen therapeutic drugs for OA.

中文翻译：

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Pitx1的过表达减弱了骨关节炎退行性软骨软骨细胞的衰老——一种用于研究骨关节炎病因和治疗的自控模型

探讨Pitx1低表达在退行性软骨组织中的作用。采用软骨划伤法建立软骨损伤模型。在 5 周龄大鼠的受伤软骨区域中，由 BrdU 标记的新生成的组织表达 SOX-9 和 Col2A1。与此相比，4月龄软骨损伤模型大鼠的BrdU阳性细胞数量较少。与外侧软骨相比，Pitx1在内侧软骨中的表达较低。SA-β-GAL 染色确定，与来自外侧软骨的软骨细胞相比，来自内侧软骨的软骨细胞表现出显着增加的细胞老化；下调 Pitx1 表达；自噬水平降低；并在软骨分化试验中降低 Col2A1 的表达。来自外侧软骨的软骨细胞中 Pitx1 表达的抑制显着增加了细胞衰老的比率。Pitx1 在源自内侧软骨的软骨细胞中的过表达降低了细胞衰老率。在荧光素酶测定中，发现 Pitx1 促进 Sirt1 基因转录。Pitx1 表达降低是胫骨内侧平台软骨退化的重要原因。所描述的自控模型是研究 OA 病因和筛选 OA 治疗药物的极好方法。Pitx1 表达降低是胫骨内侧平台软骨退化的重要原因。所描述的自控模型是研究 OA 病因和筛选 OA 治疗药物的极好方法。Pitx1 表达降低是胫骨内侧平台软骨退化的重要原因。所描述的自控模型是研究 OA 病因和筛选 OA 治疗药物的极好方法。