Expression, localisation and synthesis of versican by the enamel organ of developing mouse molar tooth germ: an in vivo and in vitro study.
OBJECTIVE
Versican is a large, aggregating chondroitin sulphate proteoglycan. In dental tissue, versican expression occurs primarily in mesenchymal tissue but rarely in epithelial tissue. We investigated the expression, localisation and synthesis of versican in the enamel organ of the developing tooth germ.


METHODS
To elucidate versican localisation in vivo, in situ hybridisation and immunohistochemistry were conducted in foetal ICR mice at E11.5-E18.5. Epithelium and mesenchyme from the lower first molars at E16.0 were enzymatically separated and versican mRNA expression was investigated by semi-quantitative RT-PCR. Organ culture of the separated samples combined with metabolic labelling with [(35)S], followed by gel filtration, was performed to analyse secreted proteoglycans.


RESULTS
Versican mRNA was first expressed in the thickened dental epithelium at E12.0 and continued to be expressed in the enamel organ until the bell stage. Versican immunostaining was detected in the stellate reticulum areas from the bud stage to the apposition stage. The enamel organ at E16.0 expressed versican mRNA at a level comparable to that in dental mesenchyme. Furthermore, when compared to dental mesenchyme, about 1/2-3/4 of the [(35)S]-labelled versican-like large proteoglycan was synthesised and released into tissue explants by the enamel organ.


CONCLUSIONS
The dental epithelium of developing tooth germ is able to synthesise significant amounts of versican.
Jiang
Bei-Zhan
BZ
Division of Histology, Department of Oral Growth and Development, School of Dentistry, Health Sciences University of Hokkaido, Kanazawa 1757 Tobetsu-cho, Ishikari-gun, Hokkaido 061-0293, Japan.
Yokohama-Tamaki
Tamaki
T
Wang
Zuo-Lin
ZL
Obara
Nobuko
N
Shibata
Shunichi
S
D000818:Animals; D002809:Chondroitin Sulfates / Q000032:analysis; D002850:Chromatography, Gel; D003771:Dental Papilla / Q000196:embryology; D003795:Dental Sac / Q000196:embryology; D004658:Enamel Organ / Q000196:embryology* / Q000378:metabolism; D004848:Epithelium / Q000196:embryology; D005865:Gestational Age; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D053547:Keratin-14 / Q000032:analysis; D008648:Mesoderm / Q000196:embryology; D051379:Mice; D008813:Mice, Inbred ICR; D008963:Molar / Q000196:embryology; D009924:Organ Culture Techniques; D011509:Proteoglycans / Q000032:analysis; D019275:Radiopharmaceuticals; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013462:Sulfur Radioisotopes; D014083:Tooth Germ / Q000196:embryology* / Q000378:metabolism; D053675:Versicans / Q000032:analysis* / Q000096:biosynthesis; D014746:Vimentin / Q000032:analysis
D053547:Keratin-14; D011509:Proteoglycans; D019275:Radiopharmaceuticals; D013462:Sulfur Radioisotopes; C508323:Vcan protein, mouse; D014746:Vimentin; D053675:Versicans; D002809:Chondroitin Sulfates