Transforming growth factor-beta (TGFb) superfamily members are key factors regulating primary tooth formation and extracellular matrix formation. Previous studies have identified the temporal-spatial expression patterns of various members during tooth development. However quantitative differences in the expression of family members during amelogenesis and dentinogenesis are undetermined. Objective: To compare and identify significant variations in transcript levels of TGF-b superfamily members and their receptors between odontoblast and ameloblast cells. Methods: Immortalized mouse odontoblast (MO6-G3) and ameloblast (MEOE-3M) cells were seeded onto 6 well plates and harvested at confluency for in situ alkaline phosphatase (ALP) histochemistry and vonKossa staining. Parallel cell cultures were used to isolate total RNA that was converted to cDNA. Quantitative real time PCR (qRT-PCR) was performed using specific primers designed to amplify transcripts from members of the TGF-b superfamily, their receptors and the housekeeping gene, cyclophilin A (control). In addition, growth curves were determined for each of the cell lines by performing cell counts at days 0, 1, 2, 3, and 4 using a Coulter counter. Results: The odontoblast MO6-G3 cells had a significantly higher growth and ALP staining over that of the ameloblast MEOE-3M cells. VonKossa staining was also augmented in the odontoblast cells when compared to ameloblasts. When normalized to cyclophilin A, qRT-PCR showed reduced levels of transcripts for ALK-1 and ALK-3 in the MEOE-3M cells when compared to MO6-G3. This was in constrat to transcript levels for ALK-2, ALK-3, BMP-2, BMP-4, BMP-6, TGFb-1, TGFb-2, and TGFb-3 that were all significantly increased in the ameloblasts (p<0.05). Conclusion: This study demonstrates high expression levels of TGF b superfamily members by ameloblasts associated with enamel formation. Ameloblasts may serve a unique function in conditioning the tooth matrix with TGF b members that later regulate tertiary dentin formation associated with injury or disease. Support: NIDCR DE11688, DE13221, and DE15028.

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