Detection of collagenase mRNA in odontoclasts of bovine root-resorbing tissue by In situ hybridization

Abstract

The odontoclast, which is morphologically similar to osteoclast, is thought to play a major role in root resorption of deciduous teeth. High collagenolytic activity has been detected in the root resorbing tissue. In order to identify collagenase-producing cells and the role of collagenase in root resorption of deciduous tooth, in situ hybridization of collagenase mRNA in bovine root-resorbing tissue sections was performed using a digoxigenin-labeled, nonradioactive RNA probe. Collagenase mRNA expression was clearly observed in odontoclasts in addition to the macrophages, fibroblasts, odontoblasts, and cementoblasts. Multinuclear odontoclasts showed intense tartrate-resistant acid phosphatase (TRAP) activity. We also examined interleukin-1 (IL-1) mRNA expression in the root-resorbing tissue by in situ hybridization. IL-1 transcripts were found to be expressed in odontoclasts, fibroblasts, and macrophages suggesting that IL-1 might be an important factor for promoting root resorption. These results suggest that the collagenase produced by odontoclasts may play a key role in dentin collagen degradation in root resorption.

Effect of tetracyclines which have metalloproteinase inhibitory capacity on basal and heparin-stimulated bone resorption by chick osteoclasts

“…Osteoblasts may synthesize procollagenase which becomes trapped in the mineralized matrix for subsequent activation by the OC [30]. In TRAP positive odontoclasts, which resemble OC and resorb dentin, collagenase mRNA has been localized by in situ hybridization [31]. The mechanism of action of TETs on collagenase may relate to binding of the compound to Zn z + at the enzyme's active site.…”

Cytochemical and ultrastructural examination of apoptotic odontoclasts induced by bisphosphonate administration

“…In contrast, Sasaki and Ueno-Matsuda (1992) have demonstrated that odontoclasts secrete cathepsin B and G into the resorption lacunae of dentine. Although collagenase has been described as being mainly synthesized by osteoblasts but not by osteoclasts (S. Sakamoto and Sakamoto 1982, Okamura et al (1993) have detected the expression of collagenase by in situ hybridization in odontoclasts but not in cementoblasts or the surrounding periodontal fibroblastic cells. In contrast to osteoclasts broadly observable in bone, odontoclasts are temporary and spatially restricted to the formation and localization on root dentine of deciduous teeth, thereby enabling adequate root resorption of the deciduous teeth.…”

Role of microscopy in elucidating the mechanism and regulation of the osteoclast resorptive apparatus

“…The major source of collagenase in bone is osteoblasts (Vaes et al, 19921, although immunoreactive collagenase in osteoclasts has not been reported , suggesting that collagenase found in resorption lacunae may be secreted by osteoclasts. Further support for this view is provided by the detection of collagenase mRNA by in situ hybridization in odontoclasts (Okamura et al, 1993). The role of collagenase in resorption pits provides an intriguing problem since collagenase is inactive at a low pH.…”