Sandberg M, Autio-Harmainen H, Vuorio E
Department of Medical Biochemistry, University of Turku, Finland.
Dev Biol. 1988 Nov;130(1):324-34. doi: 10.1016/0012-1606(88)90438-1.
Total RNA extracted from developing calvarial bones of 15- to 18-week human fetuses was studied by Northern hybridization: in addition to high levels of type I collagen mRNAs, the presence of mRNAs for type III and type IV collagen, TGF-beta and c-fos was observed. In situ hybridization of sections containing calvarial bone, overlying connective tissues, and skin was employed to identify the cells containing these mRNAs. Considerable variation was observed in the distribution of pro alpha 1(I) collagen mRNA in osteoblasts: the amount of the mRNA in cells at or near the upper surface of calvarial bone was distinctly greater than that in cells at the lower surface, indicating the direction of bone growth. High levels of type I collagen mRNAs were also detected in fibroblasts of periosteum, dura mater, and skin. Type III collagen mRNA revealed a considerably different distribution: the highest levels were detected in upper dermis, lower levels were seen in fibroblasts of the periosteum and the fibrous mesenchyme between bone spiculas, and none was seen in osteoblasts. Type IV collagen mRNAs were only observed in the endothelial cells of blood capillaries. Immunohistochemical localization of type III and IV collagens agreed well with these observations. The distribution of TGF-beta mRNA resembled that of type I collagen mRNA. In addition, high levels of TGF-beta mRNA were observed in osteoclasts of the calvarial bone. These cells, responsible for bone resorption, were also found to contain high levels of c-fos mRNA. Production of TGF-beta by osteoclasts and its activation by the acidic environment could form a link between bone resorption and new matrix formation.
通过Northern杂交研究了从15至18周龄人类胎儿发育中的颅骨提取的总RNA：除了高水平的I型胶原mRNA外，还观察到III型和IV型胶原、转化生长因子-β（TGF-β）和c-fos的mRNA的存在。采用包含颅骨、覆盖的结缔组织和皮肤的切片进行原位杂交，以鉴定含有这些mRNA的细胞。在成骨细胞中观察到前α1（I）胶原mRNA的分布有相当大的差异：颅骨上表面或其附近细胞中的mRNA量明显大于下表面细胞中的量，表明骨生长的方向。在骨膜、硬脑膜和皮肤的成纤维细胞中也检测到高水平的I型胶原mRNA。III型胶原mRNA显示出明显不同的分布：在真皮上层检测到最高水平，在骨膜和成骨小梁之间的纤维间充质的成纤维细胞中检测到较低水平，而成骨细胞中未检测到。IV型胶原mRNA仅在毛细血管的内皮细胞中观察到。III型和IV型胶原的免疫组织化学定位与这些观察结果非常吻合。TGF-β mRNA的分布类似于I型胶原mRNA。此外，在颅骨的破骨细胞中观察到高水平的TGF-β mRNA。这些负责骨吸收的细胞也被发现含有高水平的c-fos mRNA。破骨细胞产生TGF-β并由酸性环境激活，这可能在骨吸收和新基质形成之间建立联系。
