Molecular biological study on the physiologic function of periodntal ligament of human deciduous tooth

采用逆转录-聚合酶链式反应(RT-PCR)技术检测体外培养的人乳牙牙周膜(HPLF-D)、恒牙(HPLF-P)、牙槽骨突(HOB)和牙周成纤维细胞(HGF)中骨保护素(OPG)、受体激活剂核转录因子B配体(RANKL)和巨噬细胞集落刺激因子(M-CSF)基因的表达。所有培养的细胞均表达几乎相同水平的OPG基因。M-CSF mRNA在各类型细胞上均有表达。与膜结合型相比，分泌型M-CSF在mRNA水平上占主导地位。而在HPLF-D、HPLF-P和HOB上，除HGF外，RANKL信息均有表达。而HPLF-D的RANKL基因表达水平与HOB相似，高于HPLF-P。结果表明：1)牙周组织细胞表达大量的M-α和OPG，具有调节破骨细胞分化的作用；2)由成骨细胞或HPLF产生的RANKL是影响牙周组织破骨细胞分化的最重要因素；3)RANKL基因的表达受多种因素的影响，如：D3)能诱导破骨细胞(或破牙细胞)分化。4)骨吸收因子在诱导破骨细胞(或破牙细胞)分化中影响乳牙牙周膜细胞，且作用大于恒牙的牙周膜。

The expression of mRNA of osteoprotegerin(OPG), receptor activator nuclear kappa B ligand(RANKL) and macrophage colony stimulating factor(M-CSF) was investigated by RT-PCR on the cultured cells derived from periodontal ligament of human deciduous teeth(HPLF-D) and permanent teeth(HPLF-P), alveolar bone process(hOB) and gingival fibroblast(hGF). All of the cultured cells express mRNA of OPG at almost same level. The expression of M-CSF mRNA was also observed on all types of the cells. The mRNA level of secreted form of M-CSF was dominant compared to membrane-bound form. On the other hand, the expression of RANKL message was observed on HPLF-D, HPLF-P and hOB, excepted on hGF. However, the level of RANKL mRNA on HPLF-D was almost same level of hOB and it was higher than that on HPLF-P. The level of RANKL message was increased by the addition of 1 α,25 dihydroxyvitamin D_3(D_3) in dose dependent manner.These data suggested as follows1)The cells in periodontal tissues express a considerable level of mRNA of M-CSF and OPG, those are able to regulate osteoclast differentiation.2)RANKL, which is produced by osteoblasts or HPLF, is the most important factor on osteoclast differentiation in periodontal tissues.3)The level of RANKL mRNA increased by the factors playing important roll on bone metabolism (for example, D_3) is able to induce the differentiation of osteoclasts (or odontoclasts).4)Bone resorbing factors affect the cells in periodontal ligament of deciduous tooth on inducing the differentiation of osteoclst (or odontoclast), and the effect is greater than that on periodontal ligament of permanent tooth.