Genkwanin blocks the interaction between phosphorylated JNK and NFATc1 to promote osteogenic differentiation and collagen Ⅰ α1 production

Abstract

Genkwanin (GWA), a flavonoid compound found abundantly in various traditional Chinese medicines, has demonstrated pharmacological effectiveness against a range of diseases. However, its role in bone formation and the underlying mechanisms remain to be elucidated. The aim of this study is to investigate the effects of GWA on osteogenic differentiation and to uncover the possible mechanisms. Primary bone marrow-derived mesenchymal stem cells (BMSCs) and MC3T3-E1 cells induced for osteogenic differentiation were used as in vitro cell models. An ovariectomy (OVX) mouse model to induce secondary osteoporosis was used to evaluate the in vivo pharmacologic efficacy of GWA. Our studies revealed that GWA facilitated osteogenic differentiation and bio-mineralization of BMSCs and MC3T3-E1 cells in vitro, and could effectively prevent OVX-induced systematic bone loss and collagen Ⅰ α1 (COL1A1) reduction in vivo. Mechanism studies indicated that GWA could directly bind to phosphorylated c-Jun N-terminal kinase (pJNK) to prevent the phosphorylation of nuclear factor of activated T cells 1 (NFATc1) by JNK, thereby promote osteogenic differentiation and COL1A1 production via increasing the nuclear localization of NFATc1. This is distinct from the previously recognized function of the JNK/AP-1/NFATc1 signaling pathway in activating osteoclast differentiation. More importantly, GWA had no significant effects on estrogen-related signaling pathways, indicating a unique advantage in lowering the risk of gynecological cancer. In conclusion, our data suggest that GWA may be a promising candidate for the therapy of diseases associated with bone loss. Targeting pJNK-NFATc1 interaction may represent a new strategy to stimulate osteogenesis.