Synthesis of procollagen by odontogenic cells of rabbit tooth germ

Studies were performed to determine whether cultured odontogenic cells from rabbit tooth germ (RP cell) could synthesize dentine-like collagen. When cells were cultured with [14C]proline, 33% of the total incorporated proteins present were collagenous. Cultured RP cells were labeled with [14C]proline in the presence of beta-aminopropionitrile. The resulting fractions, on analysis by CM-cellulose chromatography, contained three radioactive protein peaks, alpha 1(I), [alpha 1(III)]3, alpha 2. From the radioactive measurements, RP cells synthesized a significant amount of type III collagen, comparable to type I collagen. DEAE-cellulose chromatography was used to separate collagen molecules from collagen precursors. The results showed that 60% of total collagen precursor was type III precursor and the remainder was type I precursor. CM-cellulose chromatography of CNBr peptides of collagen from culture medium and cell extract revealed the presence of type I and type III collagen. Thus, the RP cell, which is a diploid cell, is unique in the predominance of type III collagen in culture, differing thereby from the character of collagen in vivo.