Department of Basic Sciences, University of Texas Health Science Center, Dental Branch, Houston 77030, USA. cbegue@mail.db.uth.tmc.edu
Dentin sialoprotein (DSP) and dentin phosphoproteins (DPP) are uniquely expressed by differentiating and fully differentiated mature odontoblasts. It is likely that DSP and DPP actively participate in the conversion of predentin to dentin. To compare the expression patterns of DPP and DSP, we constructed mouse cDNA probes. Northern analyses confirmed their specific expressions in tooth germ-derived RNA and showed that the probes reacted with similar or identical multiple transcripts. In situ hybridization indicated that DSP and DPP transcripts were uniquely detected and codistributed in developing mouse odontoblasts and preameloblasts. These data, as well as the adjacent positioning of the DSP and DPP coding sequences, suggest that common regulatory mechanisms control DSP and DPP expressions. Dental papillae cultures, in which odontoblast differentiation was experimentally induced with TGFbeta1 combined with heparin, were used to show that the two molecules are also coexpressed under in vitro conditions.