Immunocytochemistry of keratan sulfate proteoglycan and dermatan sulfate proteoglycan in porcine tooth-germ dentin

Abstract

Keratan sulfate proteoglycan and dermatan sulfate proteoglycan have been reported to inhibit collagen fibrillogenesis. We investigated t heir distribution in order to evaluate the role of proteoglycan in dentinogenesis.Specimens of porcine tooth-germ dentin and erupted teeth were the materials, on which antibodies of keratin sulfate and dermatan sulfate proteoglycan were used. Predentin was found to be positive for both antibodies, and the reaction ceased in the calcification front. Uniformly thick collagen fibrils (30-70 nm in diameter) were distributed in the predentin matrix, which would become intertubular dentin in the future.Both antibodies reacted positively along these fibrils. On the other hand, the surface layer of dentin in the tooth germ and that in erupted teeth, collagen fibrils of 10-300 nm in diameter were occasionally noted in dentinal tubules whose odontoblastic processes had disappeared, and these heterogeneous fibrils were negative for both antibodies.Our findings suggest that keratan sulfate proteoglycan and dermatan sulfate proteoglycan distributed in the predentin inhibit calcification of collagen fibrils in the uncalcified matrix and disappear in the calcification 3 front. It was further suggested that keratin sulfate proteoglycan and dermatan sulfate proteoglycan distributed along collagen fibrils in the predentin matrix maintain uniform thickness, whereas collagen fibrils in dentinal tubules varied in thickness because of the absence of involvement of both proteoglycans. Keratan sulfate proteoglycan and dermatan sulfate proteoglycan were therefore thought to be involved in both calcification and matrix formation.

Intracellular precipitation of hydroxyapatite mineral and implications for pathologic calcification

“…Whereas several studies have shown a disappearance of proteoglycans at sites of initial mineralization (Moriguchi et al, 2004;Waddington et al, 2003), in contrast we show increased proteoglycan immunoreactivity (for decorin) and increased sulfur content in mineralized areas within the MDCK cultures. While little is known about the role of decorin in mineralization, one hypothesis is that its modulation of collagen fibrillogenesis in the extracellular matrix indirectly affects hydroxyapatite crystal growth (Fischer et al, 2004).…”

“…Proteoglycans-proteins with glycosaminoglycan side chains-are ubiquitously expressed and have a wide range of functions (Lander and Selleck, 2000). With regard to mineralization, most studies have focused on the function of proteoglycans in the extracellular matrix, with some studies reporting that proteoglycans control the size and shape of hydroxyapatite by binding to crystal surfaces (Boskey et al, 1997a(Boskey et al, , 1997bCampo and Betz, 1987;Moriguchi et al, 2004;Rees et al, 2001;Waddington and Langley, 1998). Whereas substantial characterization has been done, and functional roles determined, for the large proteoglycans of cartilage and intervertebral disc, much less is known about the small leucine-rich proteoglycans (SLRPs) in mineralized tissues (Young et al, 2006), whose family members include decorin, biglycan, fibromodulin and lumican.…”

Glycosaminoglycans accelerate biomimetic collagen mineralization in a tissue-based in vitro model

“…In bone, for instance, decorin is degraded right before collagen mineralization and it was suggested that negatively charged GAGs might be responsible for inhibition of HAp formation (54). Moriguchi et al suggested that KS and DS in predentin inhibit calcification of collagen and they disappear at mineralization front (55). Some PGs such as asporin can inhibit mineralization indirectly by down-regulation of BMP-2 activity (56).…”

Expression, localization and synthesis of small leucine-rich proteoglycans in developing mouse molar tooth germ

“…Several studies have also confirmed the involvement of SLRPs in tooth development in humans 13,19,20 and other species. [21][22][23] SLRPs have been proposed to play several roles in tooth development, including cellular differentiation, collagen fibrillogenesis, dental mineralization, and tooth eruption. 24 To elucidate the exact roles of SLRPs in tooth formation, gene-knockout studies have been carried out.…”