IMMUNOHISTOCHEMICAL SIMILARITIES AND DIFFERENCES BETWEEN AMELOGENIN AND TUFTELIN GENE-PRODUCTS DURING TOOTH DEVELOPMENT

Amelogenins and tuftelins are highly specialized proteins secreted int o the developing enamel matrix during mammalian enamel formation. Both tuftelins and amelogenins have been associated with Various functions during nucleation and maturation of the developing enamel matrix. In this study we conducted experiments to investigate whether tuftelins a nd portions of the amelogenin molecule were deposited and processed in spatially distinguished portions of the developing enamel matrix, usi ng antibodies specific against tuftelin or amelogenins. The amelogenin antibodies were raised against recombinant and native amelogenins and also included an antibody against a polypeptide encoded by amelogenin exon 4. To compare spatial expression patterns of enamel protein epit opes, 3-day postnatal mouse molar tooth organs were processed for para ffin histology and cut into serial sections. Adjacent sections were ex posed to antibodies against either tuftelin or various amelogenin epit opes. To investigate age-related changes of enamel protein expression, amelogenin and tuftelin antibodies were applied to tooth organs of de velopmental stages E19 and 1, 3, 5, 7, 9 and 11 postnatal days. Tuftel in was detected within the odontoblast processes during earlier stages of development (E19 and 1 day postnatal), whereas during later stages (3-11 days) it was recognized in a portion of the enamel layer adjace nt to the dentine-enamel junction. In contrast, all four antibodies ag ainst amelogenins reacted with parts of the ameloblast cytoplasm and t he entire enamel layer. Using immunohistochemistry, we were not able t o detect any differences in the spatial distribution of the four amelo genin epitopes investigated. The spatial differences in the distributi on of amelogenin and tuftelin as observed in this study may be intepre ted as an indication of functional differences between both proteins d uring early enamel biomineralization.