INTRODUCTION: Hepatocyte growth factor (HGF) is a multifunctional cytokine that is able to stimulate multiple intracellular signaling pathways to induce a remarkable variety of biological activities in a wide spectrum of cell types. The functions of HGF in modulating diverse biological responses in mesenchymal stem cells have been reported, and our previous study also demonstrated that HGF exerts promoting functions on murine dental papilla cells. However, the potential mechanisms involved are not yet clearly understood. This study investigated the signaling pathway used by HGF in human dental papilla cells (hDPCs) to identify the role of mitogen-activated protein kinase (MAPK) pathways in inducing cell proliferation, differentiation, and migration. METHODS: The activation of P38 kinase and Jun N-terminal kinase (JNK) was analyzed by using specific antibodies against phospho-P38 and phospho-JNK. Proliferation of hDPCS was measured using the WST-8 assay with Cell Counting Kit-8, cell differentiation was determined by using alkaline phosphatase activity and mineralization assays, and migration was investigated by in vitro wound healing and transwell migration assays. Immunofluorescence staining was used to visualize fibrous actin (F-actin). RESULTS: HGF activated JNK and P38 MAPK pathways in hDPCs. Blockage of JNK or P38 pathway in hDPCs significantly reduced cell proliferation, alkaline phosphatase activities, as well as mineral nodule formation induced by HGF. The JNK and P38 inhibitors also influenced F-actin remodeling stimulated by HGF and thus contributed to HGF-induced hDPCs migration. CONCLUSIONS: Data from this study indicated that JNK and P38 MAPK pathways are required in HGF-induced biological responses in hDPCs.
INTRODUCTION:Hepatocyte growth factor (HGF) is a multifunctional cytokine that is able to stimulate multiple intracellular signaling pathways to induce a remarkable variety of biological activities in a wide spectrum of cell types. The functions of HGF in modulating diverse biological responses in mesenchymal stem cells have been reported, and our previous study also demonstrated that HGF exerts promoting functions on murine dental papilla cells. However, the potential mechanisms involved are not yet clearly understood. This study investigated the signaling pathway used by HGF in human dental papilla cells (hDPCs) to identify the role of mitogen-activated protein kinase (MAPK) pathways in inducing cell proliferation, differentiation, and migration. METHODS: The activation of P38 kinase and Jun N-terminal kinase (JNK) was analyzed by using specific antibodies against phospho-P38 and phospho-JNK. Proliferation of hDPCS was measured using the WST-8 assay with Cell Counting Kit-8, cell differentiation was determined by using alkaline phosphatase activity and mineralization assays, and migration was investigated by in vitro wound healing and transwell migration assays. Immunofluorescence staining was used to visualize fibrous actin (F-actin). RESULTS:HGF activated JNK and P38 MAPK pathways in hDPCs. Blockage of JNK or P38 pathway in hDPCs significantly reduced cell proliferation, alkaline phosphatase activities, as well as mineral nodule formation induced by HGF. The JNK and P38 inhibitors also influenced F-actin remodeling stimulated by HGF and thus contributed to HGF-induced hDPCs migration. CONCLUSIONS: Data from this study indicated that JNK and P38 MAPK pathways are required in HGF-induced biological responses in hDPCs.