👤 Masahiro Mizuhara

Orthodontic treatment enables tooth movement through bone remodeling. The effects of fibroblast growth factor 2 (FGF2) on human periodontal ligament fibroblasts (HPdLFs) in response to mechanical stimulation that occurs during orthodontic treatment remain unexplained. We investigated the effects of FGF2 and mechanical stress on HPdLF differentiation, focusing on cementoblast differentiation. The effects of FGF2 and mechanical stress (applied for 24 hours using a centrifuge) on HPdLFs were evaluated. Changes in marker levels were assessed using real-time reverse transcriptase-polymerase chain reaction and western blotting. Furthermore, the effect of FGF2 treatment on HPdLF mineralization was assessed after 3 and 5 weeks using Alizarin red S staining (BMK-R009: Bio Future Technologies, Tokyo, Japan). Treatment of HPdLFs with 20 ng/mL FGF2 increased the expression of CEMP1 and RUNX2 but did not significantly alter the expression of FGF2, FGFR1, and FGFR2. In HPdLFs exposed to mechanical stress, expression of FGFR1 and OCN was increased, whereas that of FGF2, CEMP1, CAP, GLUT1, ALP, and OPN was reduced considerably. Treatment of mechanically-stressed HPdLFs with FGF2 did not change FGF2 expression, but expression of FGFR1, CEMP1, CAP, and GLUT1 increased significantly. In addition, FGFR1 was significantly upregulated at the protein level, whereas cementoblast differentiation markers showed an upward trend. Mineralization showed no changes at 3 weeks. However, at 5 weeks, considerable mineralization was observed in mechanically-stressed cells continuously exposed to FGF2. Mechanical stress increases FGFR1 expression in HPdLFs. FGF2 promotes the differentiation of mechanical-stressed HPdLFs into cementoblasts and their mineralization. Show less

Mutations in the fibroblast growth factor receptor 2 (FGFR2) gene are responsible for several severe forms of craniosynostotic disorders, such as Apert and Crouzon syndromes. Patients with craniosynostotic disorders caused by a mutation in Fgfr2 present with several clinical symptoms, including hypersalivation. Here we used a transgenic mouse model of Apert syndrome (Fgfr2 Fgfr2 The number of ducts and acini in Fgfr2 These results suggested that increased FGFR1 signaling and apoptosis in the submandibular glands of Fgfr2 Show less

Neuronal differentiation is regulated by many basic-helix-loop-helix (bHLH) family transcriptional activators and repressors, and the balance of activity between these factors is important for the differentiation process. Here, we report the identification of a novel transcriptional repressor, designated Helt. Helt encoded a Hey-related bHLH protein containing the bHLH and Orange domains. Helt could homodimerize, and heterodimerize with Hes5 or Hey2. Both the bHLH and Orange domains were involved in the homodimerization. In contrast, only the bHLH domain was required for the heterodimerization with Hey2, whereas only the Orange domain mediated the interaction between Helt and Hes5. Thus, Helt has two dimerization domains, and these domains independently select a partner. Identification of preferred recognition sequences by CASTing experiments revealed that Helt bound to the E box, which was distinct from the Hes1 optimal sequence around the E box core. Not only the core sequence but also sequences flanking the E box were essential for the recognition by Helt and Hes1. Furthermore, Helt repressed transcription from an artificial promoter through binding to the optimal E box elements, as well as transcription from its own promoter. Using in situ hybridization and immunohistochemistry, Helt expression in embryos was investigated. Helt was mainly expressed in undifferentiated neural progenitors in some of the developing brain regions, including the mesencephalon and diencephalon, at the neurogenesis stage. These results suggest that Helt acts as a transcriptional repressor to regulate neuronal differentiation and/or identity. Show less