EXPRESSION OF DENTIN SIALOPROTEIN (DSP) AND OTHER MOLECULAR DETERMINANTS BY A NEW CELL-LINE FROM DENTAL PAPILLAE, MDPC-23

The purpose of this study was to characterize the molecular expression of a spontaneously immortalized and cloned cell line (MDPC-23) derive d from 18-19 day CD-1 fetal mouse molar dental papillae to determine i f these cells were odontoblast-like. Western blots showed that a prote in band, at approximately 105 kDa, reacting positively with anti-DSP a ntibodies and co-migrating with mouse DSP, was present in lysates of c ells from passages 7, 37 and 77, in serum-free conditioned medium from passage 37 cells, and in mouse dentin extract. A minor band at 55 kDa was also apparent in cell lysates, Using a cDNA probe for a 486 bp mo use DSP coding sequence, DSP or DSP-PP mRNA expression was detected by Northern analysis as well as Southern analysis after RT-PCR in all th ree passages. It was also shown that in these cells 1,25 (OH)(2) vitam in D-3 upregulated both osteopontin and osteocalcin mRNA, and dexameth asone downregulated alkaline phosphatase and alpha(2)(I) collagen mRNA , Thus, MDPC-23 cells express proteins which are common to mineralizin g tissue. The expression of DSP and DSP-PP strongly suggests that this cell line is from the odontoblast lineage.