Division of Oral Pathology, Department of Tissue Regeneration and Reconstruction, Niigata University Graduate School of Medical and Dental Sciences, 2-5274 Gakkocho-dori, Chuo-ku, Niigata 951-8514, Japan.
Matrix Biol. 2011 Sep;30(7-8):379-88. doi: 10.1016/j.matbio.2011.08.001. Epub 2011 Sep 13.
Perlecan, a heparan sulfate proteoglycan, is enriched in the intercellular space of the enamel organ. To understand the role of perlecan in tooth morphogenesis, we used a keratin 5 promoter to generate transgenic (Tg) mice that over-express perlecan in epithelial cells, and examined their tooth germs at tissue and cellular levels. Immunohistochemistry showed that perlecan was more strongly expressed in the enamel organ cells of Tg mice than in wild-type mice. Histopathology showed wider intercellular spaces in the stellate reticulum of the Tg molars and loss of cellular polarity in the enamel organ, especially in its cervical region. Hertwig's epithelial root sheath (HERS) cells in Tg mice were irregularly aligned due to excessive deposits of perlecan along the inner, as well as on the outer sides of the HERS. Tg molars had dull-ended crowns and outward-curved tooth roots and their enamel was poorly crystallized, resulting in pronounced attrition of molar cusp areas. In Tg mice, expression of integrin β1 mRNA was remarkably higher at E18, while expression of bFGF, TGF-β1, DSPP and Shh was more elevated at P1. The overexpression of perlecan in the enamel organ resulted in irregular morphology of teeth, suggesting that the expression of perlecan regulates growth factor signaling in a stage-dependent manner during each step of the interaction between ameloblast-lineage cells and mesenchymal cells.
层粘连蛋白聚糖是一种富含硫酸乙酰肝素蛋白聚糖的细胞外基质分子，在釉质器官的细胞外基质中高度富集。为了研究层粘连蛋白聚糖在牙齿形态发生中的作用，我们利用角蛋白 5 启动子在釉质上皮细胞中过表达层粘连蛋白聚糖，在组织和细胞水平上检测其牙胚。免疫组化结果显示，转基因（Tg）小鼠的釉质器官细胞中层粘连蛋白聚糖的表达比野生型小鼠更强。组织病理学观察显示，Tg 磨牙的星状网状层细胞间空间更宽，釉质器官的细胞极性丧失，特别是在颈部区域。由于沿上皮根鞘（HERS）内侧面以及 HERS 外侧面有大量层粘连蛋白聚糖沉积，Tg 小鼠的 HERS 细胞排列不规则。Tg 磨牙的牙冠呈钝端，牙根向外弯曲，釉质结晶不良，导致磨牙牙尖区域明显磨损。在 Tg 小鼠中，E18 时整合素 β1 mRNA 的表达显著升高，而 P1 时 bFGF、TGF-β1、DSPP 和 Shh 的表达水平升高更为明显。釉质器官中层粘连蛋白聚糖的过度表达导致牙齿形态不规则，表明层粘连蛋白聚糖的表达在成釉细胞谱系细胞与间充质细胞相互作用的每个步骤中以阶段依赖性方式调节生长因子信号。
