Role of MIZ-1 in AMELX gene expression

Amelogenin (AMELX) is the main component of the developing tooth enamel matrix and is essential for enamel thickness and structure. However, little is known about its transcriptional regulation. Using gene expression analysis, we found that MIZ-1, a potent transcriptional activator of CDKN1A, is expressed during odontoblastic differentiation of hDPSCs (human dental pulp stem cells), and is essential for odontoblast differentiation and mineralization. We also investigated how MIZ-1 regulates gene expression of AMELX. Oligonucleotide-pull down assays showed that MIZ-1 binds to an MRE (MIZ-1 binding element) of the AMELX proximal promoter region (bp, −170 to −25). Combined, our ChIP, transient transcription assays, and promoter mutagenesis revealed that MIZ-1 directly binds to the MRE of the Amelx promoter recruits p300 and induces Amelx gene transcription. Finally, we show that the zinc finger protein MIZ-1 is an essential transcriptional activator of Amelx, which is critical in odontogenesis and matrix mineralization in the developing tooth.