LIVER/INTESTINAL METABOLISM OF BILE ACIDS AND LIPIDS

该计划的总体目标是：a）扩大我们的 了解胆固醇和胆汁酸代谢的调节 B）确定途径和酶 参与肠道细菌形成次级胆汁酸; 和c）确定疏水胆汁盐引起细胞凋亡的机制， 损伤，并探讨肝保护作用的基础 熊去氧胆酸盐 这项建议的具体目标是： 1）胆汁中关键酶的纯化、表征和克隆 酸生物合成途径（胆固醇7 α-羟化酶（C7 α H）， 3 β-羟基类固醇脱氢酶/异构酶（3 β-HSD）和12 α- 羟化酶（12 α H）; 2）确定胆汁 酸，胆固醇和选定的激素调节C7 α H; 3）研究 3 β-HSD和12 α H的调节; 4）确定 胆汁酸对HMG-CoA还原酶（HMG-CoA-R）的调节; 5） 肝胆固醇酯的纯化、鉴定和克隆 6）研究胆汁酸对CEH的调节， 胆固醇和其他调节剂与其他酶联合 参与维持肝脏胆固醇稳态; 7） 纯化、表征和克隆负责 将初级胆汁酸细菌转化为次级胆汁酸; 8）克隆 和细菌胆汁酸转运（结合）蛋白的测序， 选择的细菌; 9）阐明疏水性的机制， 胆汁酸引起肝损伤，熊去氧胆酸， 代表性的亲水性胆汁盐保护膜免受毒性胆汁 10）确定不同胆汁盐单独或与 与UDCA联合，对膜流动性梯度采用 荧光探针，以评估在不同深度内的各向异性 膜;和11）以确定疏水性胆汁 盐影响胆固醇和磷脂的转移。

The overall objectives of this program project are to: a) broaden our understanding of the regulation of cholesterol and bile acid metabolism in the liver and in the intestines; b) define the pathway and enzymes involved in the formation of secondary bile acids by intestinal bacteria; and c) determine the mechanism by which hydrophobic bile salts cause cell injury and explore the basis for hepatoprotective action of ursodeoxycholate. The specific aims of this proposal are: 1)purification, characterization, and cloning of key enzymes in the bile acid biosynthetic pathway (cholesterol 7alpha-hydroxylase (C7alphaH), 3beta-hydroxysteroid dehydrogenase/isomerase (3beta-HSD) and 12alpha- hydroxylase (12alphaH); 2) determination of molecular basis by which bile acids, cholesterol and selected hormones regulate C7alphaH; 3) to study the regulation of 3beta-HSD and 12alphaH; 4)determine the mechanism of regulation of HMG-CoA reductase (HMG-CoA-R) by bile acids; 5) purification, characterization and cloning of hepatic cholesteryl ester hydrolase (CEH); 6) to study the regulation of CEH by bile acids, cholesterol and other regulatory agents in conjunction with other enzymes involved in the maintenance of hepatic cholesterol homeostasis; 7) purification, characterization and cloning of enzymes responsible for bacterial transformation of primary to secondary bile acids; 8) cloning and sequencing of bacterial bile acid transport (binding) protein from selected bacteria; 9) elucidation of the mechanism by which hydrophobic bile acids cause hepatic injury, and by which ursodeoxycholic acid, a representative hydrophilic bile salt protects membranes from toxic bile salts; 10) to determine the effects of different bile salts alone or in combination with UDCA, on the membrane fluidity gradient employing fluoroscopic probes to assess anisotropy at different depths within the membranes; and 11) to determine the mechanism by which hydrophobic bile salts affect cholesterol and phospholipid transfer.