In situ localization and in vitro expression of osteoblast/osteocyte factor-45 mRNA during bone cell differentiation
In situ localization and in vitro expression of osteoblast/osteocyte factor-45 mRNA during bone cell differentiation
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DOI：
10.1023/a:1021745614872
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发表时间：
2002-01-01
期刊：
影响因子：
--
通讯作者：
Takagi, M
中科院分区：
文献类型：
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作者：
Igarashi, M;Kamiya, N;Takagi, M
从胚胎第 14 天 (E14) 到出生后 90 天的 Wistar 大鼠，在大鼠下颌骨中检查了成骨细胞/骨细胞因子 45 (OF45) mRNA 在骨形成过程中的原位定位。在细胞培养过程中，不仅在原代大鼠成骨细胞样细胞中，而且在不同分化阶段的两种克隆大鼠成骨细胞系 ROB-C26 (C26) 和 ROB-C20 (C20) 中，使用 Northern blot 分析检测了基因表达。 C26细胞是潜在的成骨细胞前体细胞系，而C20细胞是分化程度更高的成骨细胞系。在E15，成骨细胞前体细胞分化成一组成骨细胞，其中一些表达大部分非胶原蛋白，而在这些细胞中没有观察到OF45的表达。被成骨细胞包围的细胞间基质在 E16 时矿化。随后，从成骨细胞前体细胞分化而来的成骨细胞数量随着骨形成而增加。在 E17 时，仅在少数附着于骨基质的成熟成骨细胞中观察到 OF45 mRNA 的首次表达，而在其余不太成熟的成骨细胞中则没有观察到。在E20时，伴随着骨细胞的出现，不仅在部分被骨基质包裹的更加分化的成骨细胞中而且在骨细胞中观察到OF45 mRNA表达。随后，骨细胞数量逐渐增加，并在 90 日龄大鼠中持续表达 OF45 mRNA。对经过或未经地塞米松处理的培养细胞进行 Northern 印迹分析表明，OF45 的基因表达与细胞分化的增加密切相关。这些结果表明，OF45 mRNA 由成熟成骨细胞瞬时表达，随后在骨骼骨化过程中由骨细胞表达，该蛋白代表骨细胞表型的重要标志物，并且很可能参与调节骨细胞功能。
The in situ localization of osteoblast/osteocyte factor 45 (OF45) mRNA during bone formation has been examined in the rat mandible from embryonic day 14 (E14) up to postnatal 90-day-old Wistar rats. Gene expression was also examined during cell culture not only in primary rat osteoblast-like cells but also in two clonal rat osteoblastic cell lines with different stages of differentiation, ROB-C26 (C26) and ROB-C20 (C20) using Northern blot analysis. The C26 cell is a potential osteoblast precursor cell line, whereas the C20 cell is a more differentiated osteoblastic cell line. At E15 osteoblast precursor cells differentiated into a group of osteoblasts, some of which expressed the majority of non-collagenous proteins, whereas no expression of OF45 was observed in these cells. Intercellular matrices surrounded by osteoblasts were mineralized at E16. Subsequently, the number of osteoblasts differentiated from osteoblast precursor cells was increased in association with bone formation. At E17, the first expression of OF45 mRNA was observed only in a minority of mature osteoblasts attached to the bone matrix, but not in the rest of less mature osteoblasts. At E20, concomitant with the appearance of osteocytes, OF45 mRNA expression was observed not only in more differentiated osteoblasts that were encapsulated partly by bone matrix but also in osteocytes. Subsequently, osteocytes increased progressively in number and sustained OF45 mRNA expression in up to 90-day-old rats. Northern blot analysis of the cultured cells with or without dexamethasone treatment revealed that the gene expression of OF45 correlated well with the increased cell differentiation. These results indicate that OF45 mRNA is transiently expressed by mature osteoblasts and subsequently expressed by osteocytes throughout ossification in the skeleton and this protein represents an important marker of the osteocyte phenotype and most likely participates in regulating osteocyte function.