Differential expression of decorin and biglycan genes during mouse tooth development

Small leucine-rich proteoglycans (SLRPs) have a number of biological functi ons and some of them are thought to regulate collagen mineralizaton in bone and tooth. We have previously identified and immunolocalized two members o f the SLRPs family, decorin and biglycan, in bovine tooth/periodontium. To investigate their potential roles in tooth development, we examined the mRN A expression patterns of decorin, biglycan and type I collagen in newborn ( day 19) mice tooth germs by in situ hybridization. At this developmental st age, the first maxillary and mandibular molars include stages before and af ter secretion of the predentin matrix, respectively. The expression of deco rin mRNA coincided with that of type I collagen mRNA and was mostly observe d in secretory odontoblasts, while the biglycan mRNA was expressed througho ut the tooth germ, including pre-secretory odontoblasts/ameloblasts, dental papilla and stellate reticulum. However, its signal in secretory odontobla sts was not as evident as that of decorin. In mandibular incisors, where a significant amount of predentin matrix and a small amount of enamel matrix were already secreted, a similar differential expression pattern was observ ed. In secretory ameloblasts the biglycan mRNA expression was apparent, whi le that of decorin was not. These differential expression patterns suggest the distinct roles of biglycan and decorin in the process of tooth developm ent. (C) 2001 Elsevier Science B.V./International Society of Matrix Biology . All rights reserved.