Functional & molecular study of intetinal cholesterol transporters & absorption

功能性

• 批准号: 7314490
• 负责人: PATRICK TSO
• 金额: $ 31.98万
• 依托单位: UNIVERSITY OF CINCINNATI
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-08-01 至 2012-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7314490
• 关键词: Animals; Anticholesteremic Agents; Apical; CD36 gene; Carrier Proteins; Cholesterol; Chylomicrons; Clinical Management; Data; Detergents; Distal; Dose; Enterocytes; Fistula; In Vitro; Infusion procedures; Intestines; Knock-out; Knockout Mice; Laboratories; Lipoproteins; Location; Lymph; Lymphatic; Mediating; Molecular; Mus; Numbers; Pathway interactions; Patients; Personal Satisfaction; Play; Pluronic F-68; Pluronic L81; Property; Proteins; Rattus; Reporting; Research Personnel; Role; Schering-Plough brand of ezetimibe; Side; Site; Small Intestines; Structure; Testing; Triglycerides; Work; Writing; absorption; basolateral membrane; bile salts; brush border membrane; cholesterol absorption; cholesterol trafficking; cholesterol transporters; ezetimibe; feeding; in vivo; insight; knockout animal; mouse model; prevent; programs; scavenger receptor; uptake; ursodeoxycholate

DESCRIPTION (provided by applicant): Zetia (Ezetimibe) inhibits cholesterol absorption via inhibition of NPC1-L1 mediated cholesterol transport pathway(s) in the enterocytes. We demonstrated that CD36 also plays a role in cholesterol absorption. It has also been demonstrated that the scavenger receptor SR-BI as another putative cholesterol transporter on intestinal brush border membrane. We hypothesize that SR-BI and CD36 are cholesterol transporters in the proximal and distal intestine, respectively, working in conjunction with NPC1-L1 (may be intracellular) to mediate cholesterol uptake from the lumen to intracellular compartments of the enterocytes where chylomicron assembly occurs. Aim 1: We will determine: 1) if the lack of SR-BI, CD36, or NPC1L1 alters the site and/or efficiency of cholesterol absorption (by varying the site or dose of infusion); and 2) if the counterpart transporters are upregulated to maintain cholesterol absorption in the absence of one or the other transporter protein. In lymph fistula mice, we will also determine if Ezetimibe remains effective in inhibiting cholesterol uptake by the small intestine in these knockout animals. Aim 2: First, we will determine if sub-effective doses of Ezetimibe, in combination with sub-effective doses of either ursodeoxycholate or Pluronic F-68 (F-68), inhibits intestinal cholesterol absorption in the rat. Also, we will determine the same phenomenon also works in the mouse. Second, in the knockout mice models described above, we will determine if Ezetimibe or ursodeoxycholate or F-68 alone or in combination is/are effective in inhibiting cholesterol absorption by the small intestine. Aim 3: We will take advantage of the ability of Ezetimibe to inhibit intestinal cholesterol, and the ability of Pluronic L-81 to prevent chylomicron formation to identify the pathway and quantify the amount of cholesterol exiting the enterocytes through efflux to the apical side as well as secreted through the basolateral membrane as triglyceride-rich lipoproteins. Using a combination of both Ezetimibe and Pluronic L-81, we will be able to study both the uptake and efflux of cholesterol by the small intestine. Completion of the proposed studies will provide us with new insights into how cholesterol uptake and lymphatic transport are regulated by the various transporters in the gut. These new data may also provide us with new information in the clinical management of hypercholestermic patients.

描述（由申请人提供）：Zetia（依泽替米贝）通过抑制肠细胞中 NPC1-L1 介导的胆固醇转运途径来抑制胆固醇吸收。我们证明 CD36 也在胆固醇吸收中发挥作用。还已证明清道夫受体 SR-BI 是肠刷状缘膜上另一种假定的胆固醇转运蛋白。我们假设 SR-BI 和 CD36 分别是近端和远端肠道中的胆固醇转运蛋白，与 NPC1-L1（可能在细胞内）协同作用，介导胆固醇从管腔摄取到发生乳糜微粒组装的肠细胞的细胞内区室。目标 1：我们将确定：1) SR-BI、CD36 或 NPC1L1 的缺乏是否会改变胆固醇吸收的部位和/或效率（通过改变输注部位或剂量）； 2) 在缺乏一种或另一种转运蛋白的情况下，是否上调对应的转运蛋白以维持胆固醇吸收。在淋巴瘘小鼠中，我们还将确定依折麦布是否仍能有效抑制这些基因敲除动物的小肠摄取胆固醇。目标 2：首先，我们将确定亚有效剂量的依折麦布与亚有效剂量的熊去氧胆酸盐或 Pluronic F-68 (F-68) 联合使用是否会抑制大鼠肠道胆固醇吸收。此外，我们将确定同样的现象也适用于鼠标。其次，在上述基因敲除小鼠模型中，我们将确定依泽替米贝或熊去氧胆酸盐或F-68单独或组合是否能有效抑制小肠的胆固醇吸收。目标 3：我们将利用依折麦布抑制肠道胆固醇的能力以及 Pluronic L-81 防止乳糜微粒形成的能力来确定途径并量化通过流出到顶端侧而离开肠上皮细胞的胆固醇量与富含甘油三酯的脂蛋白一样通过基底外侧膜分泌。使用依泽替米贝和 Pluronic L-81 的组合，我们将能够研究小肠对胆固醇的摄取和流出。完成拟议的研究将为我们提供关于肠道中各种转运蛋白如何调节胆固醇摄取和淋巴转运的新见解。这些新数据也可能为我们高胆固醇血症患者的临床管理提供新信息。