RESUMO
Lymphocyte enhancer-binding factor 1 (Lef1), a HMG-domain protein, is thought to play important roles in inductive tissue interaction during tooth development. Lef1 knockdown in mice causes arrest at the bud stage in tooth development. As this gene participates in the regulation of a large and diverse set of peptide growth factors in ectomesenchymal cell differentiation of dental papilla, Lef1 appears to be a key factor in odontoblast differentiation. However, the relationship between Lef1 and odontoblast differentiation is still unclear. To analyze the biological roles of Lef1 in regulating odontoblast differentiation, we transiently overexpressed or suppressed Lef1 in cultured dental pulp cells. Lef1-overexpressing cells expressed higher levels of dentin sialoprotein (DSPP), osteocalcin and alkaline phosphatase (ALP) mRNA and formed larger numbers of mineralized nodules compared to control cells. However, Msx-1 expression or cell proliferation was unaffected by overexpression of Lef1. To further examine the role of Lef1 in dental pulp cells, we knocked down Lef1 expression in dental pulp cells using short interfering RNA (siRNA). Transient expression of siRNA against Lef1 markedly reduced Lef1 mRNA levels, and Lef1-suppressed cells expressed lower levels of DSPP, osteocalcin and ALP mRNA compared to control cells. Furthermore, the formation of mineralized nodules was inhibited by siRNA against Lef1; however, neither Msx-1 expression or cell proliferation was inhibited by siRNA against Lef1. These results outline the role of Lef1 in accelerating odontoblast differentiation by regulating DSP and osteocalcin mRNA expression in dental pulp cells, confirming that Lef1 is a key factor for odontoblast differentiation.
Assuntos
Diferenciação Celular , Polpa Dentária/metabolismo , Dentinogênese , Fator 1 de Ligação ao Facilitador Linfoide/fisiologia , Odontoblastos/metabolismo , Fosfatase Alcalina/genética , Fosfatase Alcalina/metabolismo , Animais , Células Cultivadas , Polpa Dentária/citologia , Proteínas da Matriz Extracelular/genética , Proteínas da Matriz Extracelular/metabolismo , Feminino , Regulação da Expressão Gênica , Inativação Gênica , Genes Reporter , Incisivo , Fator 1 de Ligação ao Facilitador Linfoide/biossíntese , Fator 1 de Ligação ao Facilitador Linfoide/genética , Odontoblastos/citologia , Osteocalcina/genética , Osteocalcina/metabolismo , Fosfoproteínas/genética , Fosfoproteínas/metabolismo , RNA Mensageiro/metabolismo , RNA Interferente Pequeno , Ratos , Ratos Sprague-Dawley , Sialoglicoproteínas/genética , Sialoglicoproteínas/metabolismo , Calcificação de DenteRESUMO
As an initial step to study the effect of sodium fluoride on the oral environment, we investigated how sodium fluoride (NaF) affects the branching morphogenesis of fetal mouse submandibular gland (SMG). When mouse SMG was prepared from the embryo at 13 days post prenatal stage and cultured, gradual development of branching morphogenesis was observed. Addition of NaF affected this morphological change in bimodal fashions. At a lower concentration of NaF (< 2 microM), the branching morphogenesis was slightly enhanced, whereas at a higher concentration of NaF (4 - 8 microM), it was almost completely inhibited. The inhibitory effect of NaF at the higher concentration was abrogated by stimultaneous addition of epidermal growth factor (EGF), but not by 5alpha-dihydrotestosterone (DHT) or insulin-like growth factor (IGF). These data demonstrate that EGF can effectively reduce the cytotoxic activity of NaF at micromolar concentration.
Assuntos
Fator de Crescimento Epidérmico/farmacologia , Morfogênese/efeitos dos fármacos , Fluoreto de Sódio/toxicidade , Glândula Submandibular/efeitos dos fármacos , Animais , Di-Hidrotestosterona/farmacologia , Relação Dose-Resposta a Droga , Camundongos , Camundongos Endogâmicos ICR , Técnicas de Cultura de Órgãos , Somatomedinas/farmacologia , Glândula Submandibular/embriologiaRESUMO
INTRODUCTION: Sclerostin is the product of the SOST gene. Loss-of-function mutations in the SOST gene result in a high bone mass phenotype, thus confirming that sclerostin is a negative regulator of bone mass. SOST knockdown in humans also causes oral and dental malformations. However, the relationship between sclerostin and tooth development is unclear. METHODS: Using immunohistochemical techniques, we investigated sclerostin expression during fetal mouse tooth development and adult mouse tooth morphogenesis. RESULTS: Sclerostin was expressed in the secretory odontoblasts located along the ameloblasts of fetal mouse tooth germ and adult incisor. Sclerostin expression was also observed in the fetal and adult osteocytes in the jaw bone. CONCLUSION: These results suggest that sclerostin, one of the important regulatory factors of differentiated odontoblast function, may usable in vital pulp therapy.