Adebanjo O A, Moonga B S, Haddad J G, Huang C L, Zaidi M
Center for Osteoporosis and Skeletal Aging, Veterans Affairs Medical Center, Philadelphia, Pennsylvania, USA.
Biochem Biophys Res Commun. 1998 Aug 28;249(3):668-71. doi: 10.1006/bbrc.1998.9037.
Upon removal of its sialic acid or galactose residue, vitamin D-binding protein (DBP) becomes a potent macrophage-activating factor, DBP-MAF. Here we document a new function of DBP-MAF and its parent molecule, DBP, in osteoclast control. We show that all DBPs potently inhibit extracellular Ca2+ (cation) sensing at low nanomolar concentrations with the following rank order of potency: native DBP = sialidase-treated DBP > beta-galactosidase-treated DBP. This attenuation remains unaffected despite co-incubation either with the native DBP ligand, 1,25-dihydroxyvitamin D3, or with an asialoglycoprotein receptor modulator, asialoorosomucoid. Taken together, the results suggest that circulating DBP may play a role in the systemic control of osteoclastic bone resorption, a hitherto unrecognized action of the protein.
去除其唾液酸或半乳糖残基后，维生素D结合蛋白（DBP）成为一种有效的巨噬细胞激活因子，即DBP-MAF。在此，我们记录了DBP-MAF及其母体分子DBP在破骨细胞控制方面的新功能。我们发现，所有DBP在低纳摩尔浓度下均能有效抑制细胞外Ca2+（阳离子）传感，其效力顺序如下：天然DBP = 经唾液酸酶处理的DBP > 经β-半乳糖苷酶处理的DBP。无论与天然DBP配体1,25-二羟基维生素D3共同孵育，还是与去唾液酸糖蛋白受体调节剂去唾液酸血清类黏蛋白共同孵育，这种抑制作用均不受影响。综上所述，结果表明循环中的DBP可能在破骨细胞性骨吸收的全身控制中发挥作用，这是该蛋白迄今为止未被认识到的一种作用。
