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Updated: Apr 30, 2026
Real-time Visualization and Analysis of Chondrocyte Injury Due to Mechanical Loading in Fully Intact Murine Cartilage Explants
Published on: January 7, 2019
Glycogen synthase kinase 3 inhibition stimulates human cartilage destruction and exacerbates murine osteoarthritis
Gary J Litherland1, Wang Hui, Martina S Elias
1University of the West of Scotland, Paisley Campus, Paisley, UK.
Objective:
To assess the role of glycogen synthase kinase 3 (GSK-3) as a regulator of cartilage destruction in human tissue and a murine model of osteoarthritis (OA).
Methods:
Surgical destabilization of the medial meniscus (DMM) was performed to induce experimental murine OA, and joint damage was assessed histologically. Bovine nasal and human OA cartilage samples were incubated with interleukin-1 (IL-1) plus oncostatin M (OSM) and GSK-3 inhibitor. Collagen and proteoglycan release was assessed by hydroxyproline measurement and dye binding assay, collagenase activity was assessed by bioassay, and gene expression was analyzed by real-time polymerase chain reaction. Human articular chondrocytes were isolated by enzymatic digestion and cultured prior to gene silencing and immunoblotting of cell lysates and nuclear fractions.
Results:
Mice treated with GSK-3 inhibitor exhibited significantly greater cartilage damage compared with sham-operated control mice. GSK-3 inhibition in bovine cartilage dramatically accelerated IL-1 plus OSM-stimulated degradation, concomitant with a profound increase in collagenase activity. GSK-3 inhibitor induced collagen release from human OA cartilage in the presence of IL-1 plus OSM and increased proteoglycan loss. Gene expression profiling of resorbing OA cartilage revealed a marked procatabolic switch in gene expression upon GSK-3 inhibition. This was mirrored in human articular chondrocytes following GSK3 silencing, particularly with the GSK-3β isoform. GSK-3 inhibition or silencing led to enhanced IL-1 plus OSM-stimulated abundance and activity of Jun, and silencing of c-jun ameliorated GSK-3 inhibitor-mediated procatabolic gene expression.
Conclusion:
GSK-3 is an important regulator of matrix metalloproteinase (MMP)-mediated joint destruction, the inhibition of which by proinflammatory stimuli de-represses catabolic gene expression. Therapeutic strategies that maintain cartilage GSK-3 activity may therefore help curtail aberrant MMP activity during pathologic joint destruction.
Insights
Inhibiting glycogen synthase kinase 3 (GSK-3) accelerates osteoarthritis cartilage destruction by increasing matrix metalloproteinase activity. Maintaining GSK-3 activity may protect joints from pathological destruction.
Area of Science:
- Biochemistry
- Molecular Biology
- Rheumatology
Background:
- Osteoarthritis (OA) is characterized by progressive cartilage destruction.
- Glycogen synthase kinase 3 (GSK-3) plays a role in cellular signaling pathways.
- The specific role of GSK-3 in OA pathogenesis requires further elucidation.
Purpose of the Study:
- To investigate the role of GSK-3 in regulating cartilage destruction in osteoarthritis.
- To assess the impact of GSK-3 inhibition on matrix metalloproteinase (MMP) activity in human and murine OA models.
Main Methods:
- Experimental osteoarthritis was induced in mice via surgical destabilization of the medial meniscus (DMM).
- Cartilage explants (bovine and human OA) were treated with interleukin-1 (IL-1) plus oncostatin M (OSM) and a GSK-3 inhibitor.
- Collagen and proteoglycan release, collagenase activity, and gene expression were analyzed.
Main Results:
- GSK-3 inhibition significantly exacerbated cartilage damage in murine OA models.
- Inhibition of GSK-3 in bovine and human OA cartilage accelerated IL-1 plus OSM-induced degradation, increasing collagenase activity.
- GSK-3 inhibition led to a procatabolic gene expression switch, involving enhanced Jun activity, in chondrocytes.
Conclusions:
- GSK-3 is a critical regulator of MMP-mediated cartilage destruction in OA.
- Proinflammatory stimuli can inhibit GSK-3, leading to de-repression of catabolic gene expression.
- Therapeutic strategies aimed at maintaining GSK-3 activity may offer a novel approach to manage OA progression.
