Klf5 Mediates Odontoblastic Differentiation through Regulating Dentin-Specific Extracellular Matrix Gene Expression during Mouse Tooth Development

Klf5, a member of the Kruppel-like transcription factor family, has essential roles during embryonic development, cell proliferation, differentiation, migration and apoptosis. This study was to define molecular mechanism of Klf5 during the odontoblastic differentiation. The expression of Klf5, odontoblast-differentiation markers, Dspp and Dmp1 was co-localized in odontoblastic cells at different stages of mouse tooth development and mouse dental papilla mesenchymal cells. Klf5 was able to promote odontoblastic differentiation and enhance mineral formation of mouse dental papilla mesenchymal cells. Furthermore, overexpression of Klf5 could up-regulate Dspp and Dmp1 gene expressions in mouse dental papilla mesenchymal cells. In silico analysis identified that several putative Klf5 binding sites in the promoter and first intron of Dmp1 and Dspp genes that are homologous across species lines. Electrophoretic mobility shift assay and chromatin immunoprecipitation analysis indicated that Klf5 bound to these motifs in vitro and in intact cells. The responsible regions of Dmp1 gene were located in the promoter region while effect of Klf5 on Dspp activity was in the first intron of Dspp gene. Our results identify Klf5 as an activator of Dmp1 and Dspp gene transcriptions by different mechanisms and demonstrate that Klf5 plays a pivotal role in odontoblast differentiation.