MUCIN AND NON-MUCIN PROTEINS IN GALLSTONE PATHOGENESIS

本研究提案的总体目标是了解 粘蛋白和非粘蛋白胆汁糖蛋白在胆汁中的作用 胆固醇结石的发病机制。胆固醇结石是 发达国家的主要结石类型和内科或外科 对症状性结石的治疗是住院的主要原因。 胆囊粘蛋白，粘弹性凝胶的主要成分 胆囊壁上皮在胆结石的形成中起着中心作用。 来自动物和人类的实验证据表明，胆囊黏蛋白 对胆固醇结晶成核起关键作用 胆汁过饱和是胆结石形成的初始事件，在胆结石形成过程中 这些晶体随后的生长和凝聚成成熟 胆结石。除粘蛋白外，胆汁中似乎还含有粘蛋白。 或更多的非粘蛋白糖蛋白，它们也是快速 胆固醇结晶成核。这些蛋白质是不完全的 胆结石的特点及其对早期事件的贡献 队形未知。 这项建议的具体目的是确定核苷酸序列 胆囊黏蛋白基因的克隆及蛋白特异性序列的鉴定 核心对结合胆汁脂类和促进 成核作用。由于这些活性已定位于粘液 非糖基化结构域，这些结构域将被表达，并有能力 表达的多肽与胆汁脂类结合并促进 胆固醇结晶成核量测定。病理性高分泌 胆结石形成的草原犬模型中粘蛋白的表达 将用于利用粘蛋白特异性抗体研究粘蛋白基因的表达 和cDNA探针。前列腺素作为粘蛋白中介物的作用 将对过度分泌进行调查。最后，非粘蛋白糖蛋白 已被证明是有效的胆固醇结晶成核剂 从致石的草原犬胆汁和胆泥中分离出来。这些 蛋白质的结构特征和它们的调控 对胆固醇摄取的反应将在草原上进行研究 狗。粘蛋白和非粘蛋白增加的动力学比较 这个模型系统中的蛋白质将提供对这些 蛋白质在胆结石发病机制中的作用综合起来，结果是 这些研究可能会导致改善预防和治疗的方法 治疗这种常见病的疗法。

The overall goal of this research proposal is to understand the contribution of mucin and non-mucin biliary glycoproteins to the pathogenesis of cholesterol gallstones. Cholesterol gallstones are the predominant type of stone in developed countries and medical or surgical treatment of symptomatic stones is a leading cause for hospitalization. Gallbladder mucin, the major component of the visco-elastic gel that lines the gallbladder epithelium, plays a central role in gallstone formation. Experimental evidence from animals and man indicate that gallbladder mucin is critical for both cholesterol crystal nucleation from cholesterol supersaturated bile, the initial event in gallstone formation, and in the subsequent growth and agglomeration of these crystals into mature gallstones. In addition to mucin, gallbladder bile appears to contain one or more non-mucin glycoproteins which also act as promotors of rapid cholesterol crystal nucleation. These proteins have been incompletely characterized and their contribution to the early events in gallstone formation are unknown. The specific aims of this proposal are to determine the nucleotide sequence of gall bladder mucin cDNA and identify specific sequences on the protein core which are critical for binding biliary lipids and promoting nucleation. Since these activities have been localized to mucin non-glycosylated domains, these domains will be expressed, and the ability of the expressed polypeptides to bind biliary lipids and promote cholesterol crystal nucleation determined. The pathologic hypersecretion of mucin in the cholesterol-fed prairie dog model of gallstone formation will be used to study mucin gene expression using mucin specific antibodies and cDNA probes. The role of prostaglandins as mediators of mucin hypersecretion will be investigated. Finally, nonmucin glycoproteins which have been shown to be potent cholesterol crystal nucleators will be isolated from lithogenic prairie dog bile and biliary sludge. These proteins will be structurally characterized and regulation of their synthesis in response to cholesterol feeding will be studied in prairie dogs. Comparison of the kinetics of increases of mucin and non-mucin proteins in this model system will provide insights into the roles of these proteins in gallstone pathogenesis. Taken together, the results of these studies may lead to improved therapies for the prevention and treatment of this common disease.