Integrin αVβ3 mediates estrogen to enhance osteoblast proliferation, differentiation, and alleviate OVX-induced postmenopausal osteoporosis

Abstract

Estrogen plays a critical role in maintaining bone homeostasis, and its deficiency leads to postmenopausal osteoporosis. This study investigated the role of integrin αVβ3 in estrogen-mediated osteoblast function and its therapeutic potential in osteoporosis. Using CRISPR/Cas9 technology, we established an integrin αvβ3 knockout model in MC3T3-E1 cells and primary mouse osteoblasts. Estradiol was found to significantly upregulate integrin αVβ3 expression in osteoblasts, as confirmed by Western blotting, RT-qPCR, and immunofluorescence. Functional assays, including CCK8, flow cytometry, ALP staining, and ARS staining, demonstrated that estradiol enhanced osteoblast proliferation, migration, and differentiation, whereas these effects were markedly attenuated in integrin αVβ3-deficient cells. In vivo studies using an ovariectomized (OVX) mouse model revealed that AAV9-mediated knockdown of integrin αVβ3 impaired the protective effects of estradiol against bone loss. Molecular docking analysis further supported these findings, showing strong binding affinity between estradiol and integrin αVβ3, with binding scores of −7.4 kcal/mol for integrin αV and −7.3 kcal/mol for integrin β3. These results collectively indicate that integrin αVβ3 is a key mediator of estrogen's osteogenic effects, promoting osteoblast activity and mitigating postmenopausal osteoporosis. Our findings underscore the potential of targeting integrin αVβ3 as a therapeutic strategy for estrogen deficiency-induced bone loss.