u-0126 and Fractures--Bone

Forkhead box protein A2 (FOXA2) is a core transcription factor that controls cell differentiation and may have an important role in bone metabolism. However, the role of FOXA2 during osteogenic differentiation of bone marrow-derived mesenchymal stem cells (BMSCs) remains largely unknown. In this study, decreased expression of FOXA2 was observed during osteogenic differentiation of rat BMSCs (rBMSCs). FOXA2 knockdown significantly increased osteoblast-specific gene expression, the number of mineral deposits and alkaline phosphatase activity, whereas FOXA2 overexpression inhibited osteogenesis-specific activities. Moreover, extracellular signal-regulated protein kinase (ERK) signalling was upregulated following knockdown of FOXA2. The enhanced osteogenesis due to FOXA2 knockdown was partially rescued by an ERK inhibitor. Using a rat tibial defect model, a rBMSC sheet containing knocked down FOXA2 significantly improved bone healing. Collectively, these findings indicated that FOXA2 had an essential role in osteogenic differentiation of BMSCs, partly by activation of the ERK signalling pathway.

Topics: Animals; Bone Marrow Cells; Butadienes; Cell Differentiation; Extracellular Signal-Regulated MAP Kinases; Fractures, Bone; Hepatocyte Nuclear Factor 3-beta; MAP Kinase Signaling System; Mesenchymal Stem Cell Transplantation; Mesenchymal Stem Cells; Nitriles; Osteoblasts; Osteogenesis; Rats; Rats, Sprague-Dawley; RNA Interference; RNA, Small Interfering; Tissue Scaffolds

Activation of osteoblasts in bone formation and osteoclasts in bone resorption is important during the bone fracture healing process. There has been a long interest in identifying and developing a natural therapy for bone fracture healing. In this study, we investigated the regulation of osteoclast differentiation by baicalin, which is a natural molecule extracted from Eucommiaulmoides (small tree native to China). It was determined that baicalin enhanced osteoclast maturation and bone resorption activity in a dose-dependent manner. Moreover, this involves the activation of MAPK, increased Mitf nuclear translocation and up-regulation of downstream osteoclast-related target genes expression. The baicalin-induced effect on osteoclast differentiation can be mimicked by specific inhibitors of p-ERK (U0126) and the Mitf-specific siRNA, respectively. Protein-ligand docking prediction identified that baicalin might bind to RANK, which is the upstream receptor of p-ERK/Mitf signalling in osteoclasts. This indicated that RANK might be the binding target of baicalin. In sum, our findings revealed baicalin increased osteoclast maturation and function via p-ERK/Mitf signalling. In addition, the results suggest that baicalin can potentially be used as a natural product for the treatment of bone fracture.

Topics: Animals; Bone Resorption; Butadienes; Cell Differentiation; Flavonoids; Fractures, Bone; Humans; MAP Kinase Kinase 1; Mice; Microphthalmia-Associated Transcription Factor; Nitriles; Osteoclasts; Osteogenesis; Protein Binding; RAW 264.7 Cells; Receptor Activator of Nuclear Factor-kappa B; Signal Transduction