Yasui T, Fujita K, Sasaki S, Sato M, Sugimoto M, Hirota S, Kitamura Y, Nomura S, Kohri K
Department of Urology, Nagoya City University Medical School, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya 467-8601, Japan.
Urol Res. 1999 Aug;27(4):255-61. doi: 10.1007/s002400050119.
Urinary calcium stones are a pathological substance, and they show similarities to physiological mineralization and other pathological mineralizations. The expression of messenger (m) RNAs of osteopontin (OPN), matrix Gla protein (MGP), osteonectin (ON) and osteocalcin (OC) in bones and teeth has been described. We previously identified OPN as an important stone matrix protein. In addition, the spontaneous calcification of arteries and cartilage in mice lacking MGP was recently reported, a finding which indicates that MGP has a function as an inhibitor of mineralization. Here, we examined the mRNA expressions of OPN, MGP, ON, and OC in the kidneys of stone-forming model rats administered an oxalate precursor, ethylene glycol (EG) for up to 28 days. The Northern blotting showed that the mRNA expressions of OPN and MGP were markedly increased with the administration of EG, but their expression patterns differed. The OPN mRNA expression reached the maximal level at day 7 after the initiation of the EG treatment and showed no significant difference after 14 and 28 days, whereas the MGP mRNA expression rose gradually to day 28. The in situ hybridization demonstrated that the cell type expressing OPN mRNA was different from that expressing MGP. We suggest that OPN acts on calcification and MGP acts on suppression.
尿钙结石是一种病理性物质，与生理性矿化及其他病理性矿化有相似之处。骨和牙齿中骨桥蛋白（OPN）、基质Gla蛋白（MGP）、骨连接蛋白（ON）及骨钙素（OC）信使核糖核酸（mRNA）的表达已有相关描述。我们之前已确定OPN是一种重要的结石基质蛋白。此外，最近有报道称，缺乏MGP的小鼠动脉和软骨会自发钙化，这一发现表明MGP具有矿化抑制功能。在此，我们检测了给予草酸盐前体乙二醇（EG）长达28天的结石形成模型大鼠肾脏中OPN、MGP、ON和OC的mRNA表达。Northern印迹法显示，给予EG后OPN和MGP的mRNA表达显著增加，但它们的表达模式有所不同。EG处理开始后第7天，OPN mRNA表达达到最高水平，14天和28天后无显著差异，而MGP mRNA表达在第28天逐渐上升。原位杂交表明，表达OPN mRNA的细胞类型与表达MGP的细胞类型不同。我们认为，OPN作用于钙化，而MGP作用于抑制钙化。
