Dental pulp is soft connective tissue maintaining the vitality of the tooth, while odontoblasts form the dentin. Our earlier DNA microarray analysis revealed expression of putative tumour suppressor e Show more
Dental pulp is soft connective tissue maintaining the vitality of the tooth, while odontoblasts form the dentin. Our earlier DNA microarray analysis revealed expression of putative tumour suppressor exostosin 1 (EXT-1) in odontoblasts. EXT-1 is essential for heparan sulphate synthesis, which may play a role in the dentin mineralization. Since the absence of the functional EXT-1 causes bone tumours, expression in odontoblasts is interesting. Our aim was to analyse further the EXT-1 expression in human tooth. DNA microarray and PCR techniques were used to study the EXT-1 expression in mature native human odontoblasts and pulp tissue as well as in newly-differentiated cultured odontoblast-like cells. Immunohistochemistry was performed to study EXT-1 protein in mature human teeth, teeth with incomplete root and developing teeth. Markedly higher EXT-1 was observed in mature odontoblasts than in pulp at mRNA level with DNA microarray and PCR techniques. Immunohistochemistry of mature tooth revealed EXT-1 both in odontoblasts and the predentin but not in the dentin. EXT-1 was also observed in the odontoblasts of incomplete root, but the localization of the staining was different. In developing foetal tooth, staining was detected in ameloblasts and the basal lamina. The detection of EXT-1 in both mature and newly-differentiated cells indicates a role in the odontoblast function, and EXT-1 staining in the predentin indicates a function in the dentin formation. Detection of EXT-1 in developing teeth indicates a role in tooth development. Show less
A primary cilium, a sensory organelle present in almost every vertebrate cell, is regularly described in odontoblasts, projecting from the surfaces of the cells. Based on the hypothesis that the prima Show more
A primary cilium, a sensory organelle present in almost every vertebrate cell, is regularly described in odontoblasts, projecting from the surfaces of the cells. Based on the hypothesis that the primary cilium is crucial both for dentin formation and possibly in tooth pain transmission, we have investigated the expression and localization of the main cilium components and involvement of the OFD1 gene in tooth morphogenesis. Odontoblasts in vitro express tubulin, inversin, rootletin, OFD1, BBS4, BBS6, ALMS1, KIF3A, PC1, and PC2. In vivo, cilia are aligned parallel to the dentin walls, with the top part oriented toward the pulp core. Close relationships between cilium and nerve fibers are evidenced. Calcium channels are concentrated in the vicinity of the basal body. Analysis of these data suggests a putative role of cilia in sensing the microenvironment, probably related to dentin secretion. This hypothesis is enhanced by the huge defects observed on molars from Ofd1 knockout mice, showing undifferentiated dentin-forming cells. Show less