Protein kinases in dentinogenesis.

Protein modifications such as phosphorylation and dephosphorylation are known to control several cell functions including regulation of the cell cycle, signal transduction and enzyme activation/inactivation. Bone and dentin contain highly phosphorylated anionic proteins that appear to be involved in the regulation of mineralization. This study was designed to identify and characterize the enzyme(s) responsible for phosphorylation (kinases) of dentin phosphoprotein (DPP) during dentinogenesis. DPP-protein kinase activity was demonstrated in a crude homogenate of dental pulp and odontoblast cells. In parallel studies, oligonucleotides to conserved amino acid sequences present in the active site of kinases were constructed and used to screen a lambda-gt11 tooth organ cDNA library. Several cDNA clones were isolated, the size of the insert determined by PCR (polymerase chain reaction) amplification, and in situ hybridization was used to determine cellular localization during tooth organ development. Preliminary evidence provides additional molecular determinants involved with candidate kinases responsible for DPP phosphorylation and dentinogenesis.