Department of Genetics & Development, College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA.
Biochem Biophys Res Commun. 2010 Jul 9;397(4):691-6. doi: 10.1016/j.bbrc.2010.06.008. Epub 2010 Jun 4.
Osteocalcin was recently identified as an osteoblast-secreted hormone regulating insulin secretion and sensitivity. In mice and humans, osteocalcin can be present in the serum in carboxylated or undercarboxylated forms and it has been shown that it is the undercarboxylated form of osteocalcin which acts as a hormone. The study of osteocalcin different circulating forms in mouse serum, however, has been hampered by the absence of quantitative methodology. Here we described a triple enzyme-linked immunosorbent assay (ELISA) system for quantification of mouse total, carboxylated and uncarboxylated osteocalcin. That carboxylation of osteocalcin was decreased in mouse osteoblasts cultures treated with warfarin, an inhibitor of carboxylation validated this assay. This ELISA could also detect elevated levels of undercarboxylated osteocalcin in the serum of mice treated with warfarin and in the serum of Esp -/- mice, a mouse model known to have more undercarboxylated, i.e., active osteocalcin. These results show that this new ELISA system is a reliable method to assess carboxylation status of osteocalcin in cell culture supernatants as well as in mouse serum. Its use should facilitate the analysis of culture system or mouse model in which the hormonal activity of osteocalcin needs to be evaluated.
骨钙素最近被确定为一种成骨细胞分泌的激素，可调节胰岛素的分泌和敏感性。在小鼠和人类中，骨钙素可以以羧化或未羧化的形式存在于血清中，并且已经表明，作为激素起作用的是未羧化的骨钙素形式。然而，由于缺乏定量方法，对小鼠血清中骨钙素不同循环形式的研究受到了阻碍。在这里，我们描述了一种用于定量检测小鼠总骨钙素、羧化骨钙素和未羧化骨钙素的三酶联免疫吸附测定（ELISA）系统。骨钙素的羧化作用在经华法林（一种羧化抑制剂）处理的小鼠成骨细胞培养物中降低，验证了该测定方法。该 ELISA 还可以检测到用华法林处理的小鼠血清中和 Esp -/- 小鼠（已知具有更多未羧化的、即具有活性的骨钙素的小鼠模型）血清中未羧化骨钙素水平升高。这些结果表明，这种新的 ELISA 系统是一种可靠的方法，可用于评估细胞培养上清液和小鼠血清中骨钙素的羧化状态。它的使用应该有助于分析需要评估骨钙素激素活性的培养系统或小鼠模型。
