Davideau J L, Sahlberg C, Thesleff I, Berdal A
INSERM U120, Hôp R. Debré, Paris, France.
Connect Tissue Res. 1995;32(1-4):47-53. doi: 10.3109/03008209509013705.
There is extensive evidence that growth factors play a central part in the autocrine/paracrine regulation of cell growth and differentiation in mineralized tissues. In order to investigate involvement of the EGFr receptor (EGFr) in forming mineralized tissues, its expression was studied by in situ hybridization and immunocytochemistry in mandibles of growing rats, as well as in human embryos. In Hertwig's epithelial root sheath of rat molar, EGFr mRNAs appeared strongly expressed, while dental pulp and dental follicle showed weak labeling. The lingual epithelium of rat incisor showed strong labeling, which decreased after epithelial dislocation. Cells of the adjoining lingual dental pulp and dental follicle, as compared to epithelium, contained a low level of EGFr mRNAs. In contrast, a significant signal with antisense RNA probe was observed in bone. Sense RNA probes provided a regular background or no labeling. Undifferentiated cells located in the periosteum and endosteal spaces were labeled. EGFr mRNAs were also present in osteoblasts and in lesser amounts in some osteocytes. In rat and in human bone, both osteoblasts and osteocytes were positive on immunostaining. Similarly in the Hertwig's root sheath, EGFr immunostaining and in situ hybridization labeling were closely related. These data show that different patterns of EGFr expression in forming mineralized tissues are tissue- and stage-specific. However, in all these cells, the present in situ investigation supports the assumption that EGFr is involved in the early stages of cellular proliferation and differentiation. This report also suggests that EGFr may play a role in differentiated and mature cells of mineralized tissues.
有大量证据表明，生长因子在矿化组织的细胞生长和分化的自分泌/旁分泌调节中起核心作用。为了研究表皮生长因子受体（EGFr）在矿化组织形成中的作用，通过原位杂交和免疫细胞化学方法，对生长中大鼠的下颌骨以及人类胚胎进行了研究。在大鼠磨牙的赫特维希上皮根鞘中，EGFr mRNA呈强表达，而牙髓和牙囊则显示弱阳性。大鼠切牙的舌上皮呈强阳性，上皮脱位后信号减弱。与上皮相比，相邻舌侧牙髓和牙囊细胞中EGFr mRNA水平较低。相反，在骨组织中观察到反义RNA探针有明显信号。正义RNA探针则显示正常背景或无信号。位于骨膜和骨内膜间隙的未分化细胞被标记。EGFr mRNA也存在于成骨细胞中，在一些骨细胞中含量较少。在大鼠和人类骨组织中，成骨细胞和骨细胞免疫染色均呈阳性。同样，在赫特维希根鞘中，EGFr免疫染色和原位杂交标记密切相关。这些数据表明，EGFr在矿化组织形成过程中的表达模式具有组织和阶段特异性。然而，在所有这些细胞中，目前的原位研究支持EGFr参与细胞增殖和分化早期阶段的假设。本报告还表明，EGFr可能在矿化组织的分化和成熟细胞中发挥作用。
