Mechanistic study of <scp>COL6A1</scp> ‐mediated subchondral bone remodeling in osteoarthritis via the <scp>EPAC</scp> / <scp>RAP1</scp> axis

This study aimed to identify key molecular targets that drive osteoclasts (OCs) influenced progression of osteoarthritis (OA) and to explore their mechanisms influencing OCs differentiation and OA progression. We conducted weighted gene co-expression network analysis (WGCNA) and differential expression analysis using OA datasets from the GEO database, cross-referencing these findings with OCs differentiation datasets, ultimately identifying COL6A1 as a hub gene. Validation results indicated that COL6A1 expression was increased during both OA progression and OCs differentiation. Immune-related analysis indicates that the expression level of COL6A1 can influence the immune microenvironment in the subchondral bone of OA. Subsequent in vitro perturbation and rescue experiments demonstrated that COL6A1 enhances OCs differentiation and formation by activating the EPAC/RAP1 signaling axis. In vivo experiments further confirmed that COL6A1 knockdown reduced OC-mediated subchondral bone remodeling and slowed OA progression in DMM mouse models. Additionally, the molecular docking results suggest that ingenol-mebutate is a potential functional inhibitor of COL6A1. In summary, this study indicates that COL6A1 promotes the differentiation and formation of OCs by activating the EPAC/RAP1 signaling axis. Targeted blockade of COL6A1 can alleviate subchondral bone remodeling and OA progression in DMM model mice. Ingenol mebutate is a potential therapeutic drug.