Department of Orthopaedics, The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui Province, People's Republic of China.
Department of Orthopaedics, The Fourth Affiliated Hospital of Anhui Medical University, Hefei, People's Republic of China.
Cartilage. 2021 Dec;13(2_suppl):1237S-1248S. doi: 10.1177/1947603519847736. Epub 2019 May 9.
The aim of this study is to investigate the role of Sirtuin1 (Sirt1) in the regulation of autophagy for human osteoarthritis (OA) chondrocytes.
All cartilage samples were collected from human donors, including young group, aged group, and OA group. Primary chondrocytes were isolated and cultured with Sirt1 activator or inhibitor. Sirt1 expression in cartilage tissue and chondrocytes was evaluated, and the deacetylation activity of Sirt1 was determined. The alteration of autophagy activity after upregulating or downregulating Sirt1 was detected. Chondrocytes were treated with autophagy activator and inhibitor, and then the protein level of Sirt1 was examined. The interactions between Sirt1 and autophagy-related proteins Atg7, microtubule associated protein 1 light chain 3 (LC3), and Beclin-1 were determined by using immunoprecipitation.
The assay of articular cartilage revealed that the expression of Sirt1 might be age-related: highly expressed in of younger people, and respectively decreased in the elderly people and OA patients. study was also validated this result. Further study confirmed that higher levels of Sirt1 significantly increased autophagy in aged chondrocytes, while the lower expression of Sirt1 reduced autophagy in young chondrocytes. Of note, the high levels of Sirt1 reduced autophagy in OA chondrocytes. When the chondrocytes were treated with autophagy activator or inhibitor, we found the expression of Sirt1 was not affected. In addition, we found that Sirt1 could interact with Atg7.
These results suggest that Sirt1 in human chondrocytes regulates autophagy by interacting with autophagy related Atg7, and Sirt1 may become a more important target in OA treatment.
本研究旨在探讨 Sirtuin1（Sirt1）在调节人骨关节炎（OA）软骨细胞自噬中的作用。
所有软骨样本均取自人类供体，包括年轻组、老年组和 OA 组。分离并培养原代软骨细胞，用 Sirt1 激活剂或抑制剂处理。评估软骨组织和软骨细胞中 Sirt1 的表达，并测定 Sirt1 的去乙酰化活性。上调或下调 Sirt1 后检测自噬活性的变化。用自噬激活剂和抑制剂处理软骨细胞，然后检测 Sirt1 的蛋白水平。用免疫沉淀法测定 Sirt1 与自噬相关蛋白 Atg7、微管相关蛋白 1 轻链 3（LC3）和 Beclin-1 之间的相互作用。
关节软骨分析表明，Sirt1 的表达可能与年龄相关：在年轻人中高表达，在老年人和 OA 患者中分别降低。研究还验证了这一结果。进一步的研究证实，Sirt1 水平升高显著增加了老年软骨细胞的自噬，而 Sirt1 表达降低则减少了年轻软骨细胞的自噬。值得注意的是，Sirt1 水平升高降低了 OA 软骨细胞的自噬。当软骨细胞用自噬激活剂或抑制剂处理时，我们发现 Sirt1 的表达不受影响。此外，我们发现 Sirt1 可以与 Atg7 相互作用。
这些结果表明，人软骨细胞中的 Sirt1 通过与自噬相关的 Atg7 相互作用来调节自噬，Sirt1 可能成为 OA 治疗的一个更重要的靶点。
