Chronic Circadian Rhythm Disturbance Accelerates Knee Cartilage Degeneration in Rats Accompanied by the Activation of the Canonical Wnt/β-Catenin Signaling Pathway

Abstract

With the gradual deepening of understanding of systemic health and quality of life, the factors affecting osteoarthritis (OA) are not limited to mechanical injury, metabolic abnormality, age and obesity, etc., but circadian rhythm, which plays a non-negligible role in human daily life. The purpose of this study was to explore the molecular mechanism of chronic circadian rhythm disturbance (CRD) inducing cartilage OA-like degeneration. Rats with the anterior cruciate ligament excision transection (ACLT) were used to establish the early-stage OA model (6-week). The light/dark (LD) cycle shifted 12 h per week for 22 weeks in order to establish a chronic CRD model. BMAL1 knockdown (KD) and Wnt/β-catenin pathway inhibition were performed in chondrocytes. The contents of proinflammatory factors and OA biomarkers in serum and chondrocyte secretions were detected by ELISA. Pathological and immunohistochemical staining of articular cartilage indicated the deterioration of cartilage. WB and qPCR were used to evaluate the relationship between matrix degradation and the activation of Wnt/β-catenin signaling pathway in chondrocytes. We found that chronic CRD could cause OA-like pathological changes in knee cartilage of rats, accelerating cartilage matrix degradation and synovial inflammation. The expression of MMP-3, MMP-13, ADAMTS-4, and β-catenin increased significantly; BMAL1, Aggrecan, and COL2A1 decreased significantly in either LD-shifted cartilage or BMAL1-KD chondrocytes. The expression of β-catenin and p-GSK-3β elevated, while p-β-catenin and GSK-3β diminished. The inhibitor XAV-939 was able to mitigated the increased inflammation produced by transfected siBMAL1. Our study demonstrates that chronic CRD disrupts the balance of matrix synthesis and catabolic metabolism in cartilage and chondrocytes, and it is related to the activation of the canonical Wnt/β-catenin signaling pathway.

Sex-dependent variation in cartilage adaptation: from degeneration to regeneration

“…The β-catenin signaling pathway is activated by chronic dysregulation of circadian rhythm due to downregulation of brain and muscle ARNT-Like 1 (BMAL1) [ 132 ]. BMAL1 is a protein that helps generate circadian rhythms in cartilage; dysfunctional BMAL1 in OA results in increased expression of β-catenin, MMP3, MMP13, ADAMTS4, and subsequent cartilage degeneration [ 132 ]. Circadian rhythm dysregulation is also associated with dysregulation of TGFβ signaling in chondrocytes, which is an essential signaling pathway for cartilage homeostasis [ 133 ].…”

Analyses of Transcriptomics upon IL-1β-Stimulated Mouse Chondrocytes and the Protective Effect of Catalpol through the NOD2/NF-κB/MAPK Signaling Pathway

“…Then, the primary antibodies in blocking buffer were added for overnight incubation at 4 °C. The excess primary antibody was washed off with Tris-buffered saline and 0.1% Tween-20 (TBST) three times for 5 min, followed by incubation with the secondary antibody at room temperature for 1 h. After being rinsed by TBST three times for 5 min, the band density was quantified using ImageJ software (LI-COR Biosciences) [ 31 ].…”

Hypoxic Conditions Modulate Chondrogenesis through the Circadian Clock: The Role of Hypoxia-Inducible Factor-1α

“…Additionally, PER2 was found to respond to dimethyloxalylglycine (DMOG, a PHD inhibitor; in other words, an HIF pathway activator) in an HIF-1α-dependent manner. Furthermore, an in vivo study described a connection between circadian rhythms and the balance of collagen anabolism and catabolism [ 96 ]. The regulation of HIF-1α by BMAL1 was also confirmed in the mouse intervertebral disc; the inhibition of BMAL1 led to a reduced matrix-to-cell ratio in the nucleus pulposus, resulting in shorter discs during development [ 97 ].…”