Supplementary Material for: The Role of Epithelial <b><i>Stat3</i></b> in Amelogenesis during Mouse Incisor Renewal

The aim of this study was to evaluate the role of epithelial signal transducer and activator of transcription 3 (STAT3) in mouse incisor amelogenesis. Since <i>Stat3</i> is expressed in the epithelial component of developing and adult mouse teeth, we generated and analyzed <i>Krt14</i>^Cre/+;<i>Stat3</i>^fl/fl mutant mice in which <i>Stat3</i> was inactivated in epithelia including ameloblast progenitors and ameloblasts, the cells responsible for enamel formation. Histological analysis showed little enamel matrix in mutant incisors compared to controls. Delayed incisor enamel mineralization was demonstrated using micro-computed X-ray tomography analysis and was supported by an increase in the pre-expression distance of enamel-enriched proteins such as amelogenin, ameloblastin, and kallikrein-4. Lastly, scanning electron microscopy analysis showed little enamel mineralization in mutant incisors underneath the mesial root of the 1st molar; however, the micro-architecture of enamel mineralization was similar in the erupted portion of control and mutant incisors. Taken together, our findings demonstrate for the first time that the absence of epithelial <i>Stat3</i> in mice leads to delayed incisor amelogenesis.