INOSITOL 1,4,5-TRISPHOSPHATE RECEPTOR EXPRESSION IN ODONTOBLAST CELLS

The cellular distribution of inositol 1,4,5-trisphosphate receptors wa s examined in rodent maxillary incisor teeth. In situ hybridization st udies with a transmembrane probe of type I inositol 1,4,5-trisphosphat e receptor indicated that this receptor/channel was highly expressed i n odontoblast cells of incisor teeth. In contrast, very low labeling w as observed in dental pulp. Northern analysis showed a message size of approximately 9.5 kilobases for this receptor, and demonstrated that type III inositol 1,4,5-trisphosphate receptor was expressed in inciso r teeth. Immunocytochemical studies confirmed that types I and III ino sitol 1,4,5-trisphosphate receptors were both highly expressed in odon toblasts while very low expression was detected in dental pulp. Finall y, antibodies that recognized alpha subunits of the G(q) class of GTP binding proteins also stained odontoblasts. These results indicate tha t receptor-mediated regulation of calcium release through inositol 1,4 ,5-trisphosphate receptors may occur in odontoblasts of rat incisor te eth. These findings also suggest that inositol 1,4,5-trisphosphate rec eptor/channels regulate calcium flux in odontoblasts during mineraliza tion of dentin, or in growth and differentiation of incisor tissue. (C ) 1997 Elsevier Science B.V.