PI KINASES, CANALICULAR TRANSPORTERS AND CHOLESTASIS

PI 激酶、小管转运蛋白和胆汁淤积

• 批准号: 2910977
• 负责人: IRWIN Monroe ARIAS
• 金额: $ 32.97万
• 依托单位: TUFTS UNIVERSITY BOSTON
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-09-01 至 2004-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2910977
• 关键词: bile circulation; cations; cholates; cholestasis; confocal scanning microscopy; enzyme inhibitors; fluorescence microscopy; genetically modified animals; intracellular membranes; intracellular transport; laboratory mouse; membrane transport proteins; microtubules; phosphatidylinositol 3 kinase

Mechanisms responsible for intracellular cholestasis and regulation of intracellular trafficking of the ATP-dependent canalicular transporters spgp (taurocholate), mrp2 (nonbile acid organic anions), mdr1 (organic cations), mdr3 (phosphatidylcholine translocase) and newly described mrp3 (glycocholate) are poorly understood. An intact microtubular network and vesicular trafficking originating in the trans-Golgi network and concluding in the bile canalicular membrane are required. Both are associated with PI 3-kinase activity and are blocked by Wortmannin and LY294002, which are PI 3-kinase inhibitors. Activation of PI 3- kinase in intact cells accelerates bile acid secretion. We propose that PI 3-kinase lipid products are essential for vesicular trafficking of the ATP-dependent canalicular transporters as well as for their activity in the canalicular membrane. We also postulate that generation of these phospholipids is defective in certain forms of cholestasis. Using biochemical, molecular and confocal fluorescence microscopic techniques and novel reagents and experimental models, including genetically engineered p85-/- PI 3- kinase mice, the specific trafficking of canalicular transporters and the role of PI 3-kinase and its lipid producers in bile secretion will be determined. These studies should elucidate intracellular mechanisms of cholestasis. Furthermore, activation of specific PI 3-kinase functions may selectively enhance canalicular transport and have therapeutic potential in cholestasis.

细胞内胆汁淤滞的机制和atp依赖性小管转运体spgp（牛磺酸胆酸）、mrp2（非胆汁酸有机阴离子）、mdr1（有机阳离子）、mdr3（磷脂酰胆碱转位酶）和新近描述的mrp3（胆酸糖）的细胞内运输调控尚不清楚。需要一个完整的微管网络和起源于反高尔基网络并最终进入胆小管膜的囊泡运输。两者都与PI 3-激酶活性相关，并被PI 3-激酶抑制剂Wortmannin和LY294002阻断。激活完整细胞中的pi3 -激酶可加速胆汁酸的分泌。我们认为PI 3-激酶脂质产物对于atp依赖性小管转运蛋白的囊泡运输及其在小管膜中的活性至关重要。我们还假设，在某些形式的胆汁淤积症中，这些磷脂的生成是有缺陷的。利用生物化学、分子和共聚焦荧光显微技术以及新型试剂和实验模型，包括基因工程p85-/- PI 3-激酶小鼠，将确定小管转运蛋白的特异性运输以及PI 3-激酶及其脂质产生物在胆汁分泌中的作用。这些研究应阐明胆汁淤积的细胞内机制。此外，激活特定的PI 3激酶功能可能选择性地增强小管运输，并具有治疗胆汁淤积的潜力。