CXCL1 Promotes Osteoblast Autophagy and Inhibits Ferroptosis Through the Activation of the TGF-β/Smad Signalling Pathway.

Osteoblast dysfunction plays a central role in osteoporosis. CXC chemokine ligand 1 (CXCL1), a known inflammatory mediator, is increasingly recognised for its role in bone homeostasis. However, its influence on osteoblast survival mechanisms such as ferroptosis and autophagy remains unclear. This study explores the role of CXCL1 in promoting osteoblast differentiation and activity by inhibiting ferroptosis and enhancing autophagy via the TGF-β/Smad signalling pathway. Primary rat osteoblasts were treated with recombinant CXCL1, shRNA constructs and pathway modulators, such as Galunisertib, Fer-1 and Chloroquine (CQ). Osteoblast differentiation, autophagy, ferroptosis and TGF-β/Smad pathway activity were evaluated using qPCR, western blotting, staining and densitometric analysis. CXCL1 knockdown impaired osteoblast proliferation and differentiation, while increasing intracellular iron and ROS and enhancing ACSL4 expression, indicative of ferroptosis. These effects were partially reversed by Fer-1. Besides, CXCL1 activated the TGF-β/Smad signalling cascade, and Galunisertib inhibited this signalling and partially suppressed CXCL1-induced effects. Furthermore, CXCL1 promoted autophagy via increased Beclin-1 and LC3B and reduced p62, which mitigated ferroptosis and supported osteogenesis. Our findings suggest that CXCL1 promotes osteoblast differentiation by inhibiting ferroptosis and enhancing autophagy through activation of the TGF-β/Smad signalling pathway. Collectively, our results highlight CXCL1 as a promising therapeutic target for osteoporosis.