Purpurin Alleviates Meniscal Senescence and Osteoarthritis by Blocking the Non-Metabolic Function of Hexokinase 2

Meniscal degeneration, characterised by extracellular matrix (ECM) loss and cellular senescence, plays a critical role in osteoarthritis (OA) progression, yet the underlying mechanisms remain unclear. Although hexokinase 2 (HK2) is recognised as a key glycolytic enzyme, its potential non-metabolic functions in the meniscus remain unexplored. In this study, HK2 expression was evaluated in human OA and normal meniscus tissues, and its non-metabolic effects were investigated in primary meniscal cells using overexpression, knockdown, and site-directed mutagenesis; protein interactions were analysed by immunoprecipitation-mass spectrometry (IP-MS) and co-immunoprecipitation (Co-IP). HK2 was significantly upregulated in OA meniscal tissues, and overexpression of catalytically inactive HK2 promoted meniscal ECM degradation and cellular senescence in an MYH10-dependent manner. Mechanistically, HK2 enhanced the MYH10-PRKN interaction, inducing K48-linked ubiquitination of MYH10 at lysine 410 and its subsequent proteasomal degradation, thereby reducing COL1A1 mRNA stability. Purpurin, identified through virtual screening, disrupted the HK2-MYH10 interaction in vitro, prevented MYH10 degradation, and attenuated cellular senescence. In the destabilisation of the medial meniscus (DMM) mouse model, intra-articular injection of adeno-associated virus expressing catalytically inactive HK2 exacerbated OA progression, whereas purpurin treatment alleviated meniscal degeneration, ECM loss, and OA-associated pain. Collectively, HK2 promotes meniscal senescence and OA progression through a non-metabolic, MYH10-dependent mechanism, and purpurin represents a promising lead compound for disease-modifying osteoarthritis drug (DMOAD) development.