Ezh2 knockout in mesenchymal cells causes enamel hyper-mineralization.

Area of Science:

• Developmental Biology
• Epigenetics
• Biomineralization

Background:

• Enhancer of zeste homolog 2 (EZH2) is key to polycomb repressive complex 2 (PRC2), regulating gene expression via histone methylation (H3K27me3).
• EZH2's role in tooth development, particularly enamel formation, is not fully understood.

Purpose of the Study:

• To investigate the function of EZH2 in tooth development, focusing on its impact on enamel formation.
• To elucidate the molecular mechanisms by which EZH2 influences ameloblast function and enamel properties.

Main Methods:

• Conditional knockout of Ezh2 in mouse mesenchymal cells.
• Microcomputed tomography (microCT) for enamel mineralization analysis.
• Scanning electron microscopy (SEM) and nano-indentation for enamel microstructure and hardness assessment.
• Histological analysis and gene expression studies (Orai1, Orai2, ameloblastin, KLK4) in incisors and cultured ameloblasts.

Main Results:

• Conditional Ezh2 knockout resulted in hyper-mineralized enamel with increased hardness and smaller inter-rod spaces.
• EZH2 inhibition or knockout led to decreased Orai2 and increased Orai1 expression in ameloblasts.
• Histological analysis revealed reduced ameloblastin and accelerated KLK4 expression in knockout mouse incisors.

Conclusions:

• EZH2 depletion in dental mesenchymal cells negatively impacts enamel matrix formation and increases ameloblast protease activity.
• These changes contribute to the observed enamel hyper-mineralization, highlighting the importance of H3K27me3 in regulating enamel development.