Fig. 1.

The 3.9- and 5.2-kb Enam-LacZ reporter constructs and their transgenic expression. a The smaller construct (3.9-kb Enam-LacZ) contained 3,931 bp of Enam 5′ untranslated region extending from bases 1,555 to 5,485. The larger construct (5.2-kb Enam-LacZ) contained 5,217 bp of Enam from bases 269 to 5,485. Both Enam constructs contained the putative transcription initiation site at the start of exon 1 (at base 4,750) and the noncoding exons 1 and 2, as well as the beginning of exon 3 up to, but not including, the translation initiation site, which was supplied by the bacterial β-galactosidase cDNA (β-gal) fused to a nuclear localization sequence (NLS) and followed by a downstream polyadenylation sequence. b Transient transfection in an ameloblastic cell line (LS8). Both the 3.9- and 5.2-kb constructs were sufficient to drive the expression of β-galactosidase in the nucleus of the LS8 line. Cells transfected with a promoterless LacZ construct lacked β-galactosidase staining (left panel). Whole embryo (center) and paw (right panel) from postnatal day 1 transgenic and wild-type (WT) mice showed no β-galactosidase expression for the wild-type mice, tooth-specific expression for the 5.2-kb transgenic mice and ectopic bone expression for the 3.9-kb transgenic mice.