Journal of Dental Research, Vol 64, 1008-1015, Copyright © 1985 by International & American Associations for Dental Research Online Journals
Appearance of dentin gamma-carboxyglutamic acid-containing proteins in developing rat molars in vitro
R. D. Finkelman and W. T. Butler
An in vitro model of mineralization was devised in order to study the
developmental appearance of dentin gamma-carboxyglutamic acid-containing
proteins (DGPs) in relation to the onset of mineralization. Maxillary third
molars from 11-day-old rats were cultured with or without fetal calf serum
(FCS) as modified from Navia et al. (1984). Molars were incubated without
radiolabel, or with either 45CaCl2 (5 microCi/ml) for 24 hr at various
stages of a ten-day culture period or [3H]-leucine (10 microCi/ml) for 24
hr at the eighth day of culture. Molars were lyophilized and extracted with
10% formic acid overnight at 4 degrees C. DGPs in extracts were detected by
immunologic and chromatographic techniques; DGPs in molar sections were
detected by immunolocalization using indirect immunofluorescence. Molar
development was evaluated histologically using the Von Kossa staining
technique. Molars cultured with FCS showed histologic evidence for
mineralized dentin and enamel and a significant increase in 45Ca uptake
after the sixth day in vitro. Eleven-day-old molars in vivo and molars
cultured without FCS showed no evidence of the presence of mineralized
tissues. [3H]-Leucine-labeled DGPs were isolated and identified by affinity
and reversed-phase high-performance liquid chromatography and by gel
electrophoresis from both mineralized and unmineralized molars. DGP
antigens were localized immunohistochemically using rabbit anti-rat
antibodies raised against a highly purified DGP preparation. In the
unmineralized molar, antigenicity was seen in odontoblasts but not in
predentin matrix, preodontoblasts, or in any other cell type. Antigens in
the mineralized molar were localized to odontoblasts and dentin.(ABSTRACT
TRUNCATED AT 250 WORDS)
