u-0126 and baicalin

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

Natural medicinal materials are a significant resource for the identification of compounds with specific biological properties. In this study, we employed multipotent C17.2 neural stem cells as a model for screening natural compounds that possess neural differentiation-inducing properties. We show here for the first time that, out of the 67 compounds tested, the flavonoid baicalin is a potent differentiation-inducing agent. Baicalin increased the number of cells bearing extended neurites and the expression levels of a number of neuronal markers. Importantly, baicalin promoted the expression of several key neurogenic transcriptional factors. Moreover, we demonstrated that baicalin enhanced the phosphorylation/activation of Erk1/2. Inhibition of Erk1/2 activation by the MEK inhibitor U0126 attenuated the neuronal differentiation-inducing effect of baicalin. Taken together, our findings suggest that baicalin induces neuronal differentiation of C17.2 neural stem cells and that this is mediated by activation of Erk1/2. Our work lays the foundation for exploring baicalin for the promotion of neural regeneration after injury or disease.

Topics: Animals; Butadienes; Cell Differentiation; Flavonoids; Gene Expression Regulation; Mice; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Nerve Growth Factors; Neural Stem Cells; Nitriles; Phosphorylation