Expression Patterns of Tbx1 during Development of the Mouse Mandibular First Molar

Bok, Se Mi; Chung, Kyung Chul; Cho, Eui Sic

Abstract

A T-box transcription factor gene, Tbx1 is a principal candidate of the most frequent chromosomal deletion syndrome found in human, DiGeorge/velocardiofacial syndrome which is a complex developmental disorder associated with cardiac outflow tract abnormalities, mid facial dysmorphology, velopharyngeal insufficiency and submucosal cleft palate. We performed in situ hybridization against mouse embryo from E13.5 (bud stage) to E18.5 (late bell stage) in order to analyze the expression patterns of Tbx1 in the developing mouse first molar, a derivative of the first pharyngeal arch. Tbx1 transcripts were found in the dental lamina and its surrounding mesenchyme at E13.5 and in the dental organ except enamel knot at E14.5 (cap stage). Tbx1 was strongly expressed in the cervical loop and stratum intermedium but was weak in the dental papilla and dental follicle at E15.5 (early bell stage). At E18.5, Tbx1 was strongly expressed not only in the dental organ (bell stage) except stellate reticulum but also dental papilla and dental follicle adjacent to the inner dental epithelium. In conclusion, Tbx1 transcripts were specifically expressed both in the dental epithelium and surrounding mesenchyme of developing tooth from initiation to bell stage, which were the most similar with those of Sox9 but little different from those of Pitx2 and ectodin. These results strongly suggested that Tbx1 may play a role as a transcription factor regulating proliferation and differentiation of both dental epithelium and mesenchyme through the tooth development.