CRYSTAL GROWTH INHIBITOR PROTEIN & NEPHROLITHIASIS

肾钙蛋白（NC）是一种钙结合糖蛋白， 从人尿液和人肾脏组织培养物中分离出来，并且 在体外抑制草酸钙晶体的生长。分子 在从混合尿液中分离的NC中发现了异常， 钙结石形成剂，其降低了其对晶体表面的亲和力， 并因此降低其减缓晶体生长的能力。这种异常包括 缺乏γ-羧基谷氨酸（GLA）。尚不清楚是否 NC的结构和功能异常有助于肾脏 在某些个体中形成结石。本提案的目的是 开始研究NC在个体钙结石形成中的作用 石成型机，并研究调节生产的因素， 蛋白 在PI以前的研究中，已经使用了蛋白质的抗体 估计正常男性和女性的NC排泄率， 这与尿液抑制草酸钙的能力有关 在籽晶晶体生长系统中的晶体生长。我们的研究也 表明维生素D可能在调节NC排泄中起作用。 最后，从肾皮质组织中分离出一种类似的蛋白质 培养上清液，为体外研究提供模型， 调节蛋白质的产生。 为了调查一些石器制造者制造异常的 NC分子，数量或抑制晶体的能力降低 生长，并了解更多关于异常本身，三种类型 I）已知代谢性钙结石形成者 将使用ELISA分析研究缺陷和结石成分， 测量NC排泄，并测定晶体生长以检测 抑制活性的异常。异常的分离和研究 II）服用香豆素的患者也将被研究。 如果缺乏GLA是关键的缺陷，这些患者可能会显示 与结石形成者相似的异常。（三）研究 蛋白质生产的调节将在细胞培养中进行。 维生素D、PTH、中钙、维生素K缺乏等均可 进行评估。 抑制物异常可能参与了发病机制 石头的一个子集。具体知识 导致抑制晶体生长的能力受损的异常， 调节这种蛋白质产生的因素可能会导致 有效的治疗措施。

Nephrocalcin (NC) is a calcium-binding glycoprotein that has been isolated from human urine and human kidney tissue culture, and that inhibits growth of the calcium oxalate crystals in vitro. Molecular abnormalities have been found in NC isolated from the pooled urine of calcium stone formers, which decrease its affinity for crystal surface, and thus its ability to slow crystal growth. This abnormality includes a deficiency of gamma-carboxglutamic acid (GLA). It is unknown whether abnormalities in the structure and function of NC contribute to kidney stone formation in certain individuals. The goal of this proposal is to begin to study the role of NC in stone-formation in individual calcium stone-formers, and to study the factors that regulate production of the protein. In previous studies by the PI, antibodies to the protein have been used to estimate excretion rates of NC in normal men and women, and to correlate this with the ability of the urine to inhibit calcium oxalate crystal growth in a seeded crystal growth system. Our studies have also shown that Vitamin D may play a role in regulation of NC excretion. Finally a similar protein has been isolated from kidney cortical tissue culture supernatants, providing a model for in vitro studies of regulation of protein production. To investigate the possibility that some stone-formers make an abnormal NC molecule, decreased either in amount or in ability to inhibit crystal growth, and to learn more about the abnormalities themselves, three types of studies are proposed; I) Calcium stone formers with known metabolic defects and stone composition will be studied using ELISA assay to measure NC excretion, and assays of crystal growth to detect abnormalities in inhibitory activity. Isolation and study of abnormal proteins will be done II) Patients taking coumadin will also be studied. If lack of GLA is the crucial defect, these patients may display abnormalities similar to those of stone-formers. III)Studies of regulation of protein production will be carried out in cell culture. Effect of vitamin D, PTH, medium calcium, vitamin K deficiency, etc. can be assessed. It is likely that inhibitor abnormalities contribute to the pathogenesis of stones in a subset of stone-formers. Knowledge about the specific abnormalities that lead to impaired ability to inhibit crystal growth and of the factors that regulate production of this protein may lead to effective therapeutic interventions.