Network Analysis Identifies Microsomal Glutathione S-Transferase as a Potential Regulator of Oxidative Stress and Proteasome Dysfunction in Human Osteoarthritic Menisci.

Osteoarthritis (OA)-related meniscal degeneration involves complex interactions between oxidative stress and proteasomal dysfunction. However, the molecular drivers of regional meniscal vulnerability remain poorly defined. This study integrated multiple transcriptomic datasets from OA and control menisci to identify functional networks and hub genes by using weighted gene co-expression network analysis. Human meniscal tissues from medial and lateral compartments were harvested during total knee arthroplasty and subjected to western blot analysis. In vitro assays on the basis of human chondrocytes were exposed to lipopolysaccharide or the proteasome inhibitor MG132 (carbobenzoxy-l-leucyl-l-leucyl-l-leucinal) to evaluate the stimulus-specific regulation of identified network and hub genes. Weighted gene co-expression network analysis revealed microsomal glutathione S-transferase (MGST1) as the hub gene within a module enriched for ubiquitination and proteasome activity. Experimental validation in human meniscal tissues demonstrated pronounced upregulation of MGST1, ubiquitin-conjugating enzyme E2 N (UBE2N), and proteasome activator complex subunit alpha (PSMA) in mechanically overloaded medial compartments compared to lateral regions. In vitro studies demonstrated stimulus-specific modulation: lipopolysaccharide-induced inflammatory stress upregulated MGST1, whereas proteasome inhibition via MG132 led to its downregulation. These findings highlight a dynamic interplay between redox adaptation and proteostasis, where chronic mechanical stress drives MGST1-mediated antioxidant responses and compensatory ubiquitination. Together, these results suggest that joint tissues dynamically adapt to mechanical and inflammatory challenges by modulating oxidative stress defenses and protein quality control mechanisms, processes central to OA pathophysiology.