Tooth-specific expression conferred by the regulatory sequences of rat dentin sialoprotein gene in transgenic mice

We have isolated a 3.8-kb DNA fragment containing the 5' flanking region, I st exon, and Ist intron of the rat dentin sialoprotein (rDsp) gene and prod uced transgenic mice carrying a LacZ reporter gene under the control of thi s fragment. Expression of the transgene transcript and beta-galactosidase a ctivity were restricted to dentin and odontoblasts with spatial and tempora l patterns comparable to those of the endogenous mouse Dsp transcript, alth ough beta-galactosidase activity could not be detected visually during embr yonal stages. Other tissues tested, such as alveolar bones, ameloblasts and dental pulps, did not express the transgene. This indicates that the regul atory elements nessesary for tooth-specific expression are present in the f ragment, which contains a TATA box and several consensus sequences for bind ing sites of transcription factors related to tooth development, such as TC F-1/LEF-1, MSX-1 and Dlx-1. The regulatory sequences and the transgenic mic e described here provide useful information for the study of tooth developm ent, (C) 1999 Academic Press.