Transforming growth factor-β superfamily members expressed in rat incisor pulp

The transforming growth factor (TGF)-β superfamily comprises more than 35 structurally related genes that have been implicated in embryonic induction and morphogenesis. Different superfamily members may have distinct regulatory roles in tooth development and maintenance. Degenerate primer sets derived from the highly conserved carboxy terminal region of the TGF-β superfamily were used for reverse transcriptase–polymerase with poly(A)+ RNA from the rat incisor pulp as a template. TGF-β superfamily members expressed in the pulp with known potential to differentiate into odontoblasts and to form dentine were identified. Nucleotide-sequence analysis of the amplified cDNAs identified those encoding activin-βB; bone morphogenic protein (BMP)-2, -4, -7 and -8; growth/differentiation factor (GDF)-1, -5 and -6; and glial cell line-derived neurotrophic factor. In addition, Northern blot analysis detected TGF-β1, -β2 and -β3; activin-βA; BMP-6 and GDF-7 mRNA transcripts in the pulp. Coordinated expression of TGF-β superfamily members in pulp may be critical in tooth development and repair.