Targeting osteoblastic Mig6-EGFR signaling ameliorates osteoarthritis progression via inhibiting aberrant subchondral bone remodeling

Aberrant subchondral bone remodeling is a critical factor in osteoarthritis (OA) pathogenesis. We observed significant downregulation of Mitogen-induced gene-6 (Mig6) and upregulation of EGFR phosphorylation in subchondral bone osteoblasts, strongly correlating with OA severity in human and animal models. Mig6 is the most important factor mediating mechanical stress-activated EGFR, which inhibits osteogenic activity and modulates mechano-responsiveness. Osteoblast-specific Mig6 deletion exacerbated OA progression by promoting subchondral bone remodeling, whereas gefitinib-mediated inhibition of EGFR phosphorylation attenuated OA symptoms in mice, rats, and Mig6 knockout rats. Furthermore, loss of osteoblastic Mig6 disrupted the subchondral bone microenvironment, increasing inflammation, angiogenesis, and neuronal activity. Mechanistically, aberrant mechanical loading downregulated Mig6, activating phosphorylation of EGFR and the downstream JAK-STAT3 pathway, thereby promoting subchondral bone remodeling and accelerating OA progression. These findings reveal a novel mechanism by which osteoblastic Mig6 regulates subchondral bone remodeling in OA, highlighting Mig6 as a potential therapeutic target.