Dentin sialoprotein (DSP) transcripts: developmentally‐sustained expression in odontoblasts and transient expression in pre‐ameloblasts

TLDR

Dentin sialoprotein (DSP) is a 53 kDa glycoprotein traditionally thought to be expressed only in dentin, a view supported by prior immunohistochemical studies. Using rat and mouse DIG‑ and 35S‑labeled DSP riboprobes with in situ hybridization, we examined DSP mRNA expression at specific stages of dentinogenesis. DSP transcripts were detected in young and mature odontoblasts during predentin formation but absent from pulp, enamel organ, ameloblasts, and other soft tissues, while transient expression was observed in pre‑ameloblasts, suggesting a role in epithelial‑mesenchymal interactions.

Abstract

Dentin sialoprotein (DSP), a 53 kDa glycoprotein, is believed to be present exclusively in dentin. Using rat and mouse digoxigenin labeled (DIG)‐DSP and 35 S‐DSP riboprobes, and in situ hybridization techniques, we have studied the presence of DSP mRNA at specific developmental stages of dentinogenesis. In mouse and rat molars and incisors, DSP transcripts were localized in young odontoblasts associated with early stages of predentin formation, as well as in mature odontoblasts, cells with cytoplasmic extensions embedded in the forming dentin. No DSP transcripts were detected in dental pulp, enamel organ, ameloblasts, epithelial root sheath, Meckel's cartilage, alveolar bone or tibia. Furthermore, no DSP mRNA was observed in other soft tissues including heart, lung, kidney, intestine, eye, and muscle. In addition to the intense and prolonged expression by odontoblasts, DSP mRNA was transiently expressed by pre‐ameloblasts in both developing molars and incisors. These observations are consistent with the results of previous immunohistochemical studies (1). The transient expression of DSP in pre‐ameloblasts across from young odontoblasts suggests an involvement of DSP in epithelial‐mesenchymal interactions that are crucial to later stages of tooth development.