敲除时钟基因减弱活性氧介导的软骨细胞衰老通过恢复自噬通量。

Clock knockdown attenuated reactive oxygen species-mediated senescence of chondrocytes through restoring autophagic flux.

机构信息

Department of Orthopaedics, The Fifth Affiliated Hospital of Sun Yat-sen University, Zhuhai 519000, China.

出版信息

Life Sci. 2021 Mar 15;269:119036. doi: 10.1016/j.lfs.2021.119036. Epub 2021 Jan 12.

DOI:10.1016/j.lfs.2021.119036

PMID:33450259

Abstract

AIMS

Articular cartilage degeneration has been recognized as the primary pathological change in osteoarthritis (OA). Mechanisms that govern the shift from cartilage homeostasis to OA remain unknown. Previous studies have reported that intrinsic circadian clock in chondrocytes could function to optimize cartilage repair/remodeling to optimum times of day, but little is known about its molecular mechanisms. This study attempted to investigate the potential role and mechanism of circadian gene Clock in OA pathology.

MATERIALS AND METHODS

The expression of Clock in OA chondrocytes and cartilage was detected by qRT-PCR, western blot and immunohistochemistry. Temporal gene expression changes were analyzed using qRT-PCR in chondrocytes transfected with siClock following dexamethasone synchronization. In addition, the effect of Clock knockdown on senescent phenotypes and autophagic flux was evaluated in chondrocytes treated with siClock or siCntrl.

KEY FINDINGS

The expression of Clock was up-regulated in OA cartilage from humans and mouse models. Clock knockdown had no influence on rhythmic expression of the downstream genes in primary chondrocytes. We also found that Clock knockdown elevated antioxidant enzyme activities, diminished reactive oxygen species (ROS) production and attenuated senescence of chondrocytes via restoring autophagic flux.

SIGNIFICANCE

Clock knockdown can attenuate ROS-mediated senescence of chondrocytes through restoring autophagic flux in non-circadian manner, providing a potential therapeutic target for OA.

摘要

目的

关节软骨退变已被认为是骨关节炎（OA）的主要病理变化。然而，目前尚不清楚控制软骨稳态向 OA 转变的机制。先前的研究报告称，软骨细胞中的内在生物钟可以优化软骨修复/重塑，使其适应一天中的最佳时间，但关于其分子机制知之甚少。本研究试图探讨昼夜节律基因 Clock 在 OA 病理学中的潜在作用和机制。

材料与方法

通过 qRT-PCR、western blot 和免疫组织化学检测 OA 软骨细胞和软骨中的 Clock 表达。用 siClock 转染软骨细胞后，通过 qRT-PCR 分析时钟基因的时间表达变化，以进行地塞米松同步。此外，在接受 siClock 或 siCntrl 处理的软骨细胞中，评估 Clock 敲低对衰老表型和自噬流的影响。