Naringenin alleviates age-related bone loss by targeting Runx2

Senile osteoporosis presents a significant and growing health burden. Currently, no pharmacological agents are specifically approved for this condition. The dietary flavonoid naringenin (NAR) exhibits osteoprotective potential; however, its efficacy and direct molecular target in the context of senile osteoporosis remain undefined.

The effects of NAR were evaluated in a natural ageing mouse model by assessing skeletal mass, microstructure and strength. In vivo analyses included bone histomorphometry, serum bone turnover marker assays and biomechanical testing. Osteogenic and osteoclastogenic differentiation was examined in cell cultures. To identify the molecular target of NAR, we employed RNA sequencing, siRNA transfection, biotin-conjugated pull-down assays, molecular dynamics simulations, competitive pull-down with immunoblotting, SPR, CETSA, DARTS and western blotting.

NAR treatment significantly increased bone mineral density, improved trabecular microarchitecture and enhanced bone strength in ageing mice. It promoted bone formation, elevated the mineral apposition and bone formation rates and concurrently suppressed osteoclast differentiation and bone resorption. In vitro, NAR enhanced osteogenic differentiation and mineralization. Mechanistically, NAR directly bound to the key osteogenic transcription factor Runx2 and activated Runx2-dependent gene expression. Silencing Runx2 markedly attenuated the osteogenic effects of NAR.

These findings demonstrate that NAR promotes bone formation while limiting resorption, thereby alleviating age-related bone loss by activating Runx2. This study identifies Runx2 as a direct molecular target of NAR and supports its potential use in the management of senile osteoporosis.