Functional & molecular study of intetinal cholesterol transporters & absorption

功能性

• 批准号: 7896869
• 负责人: PATRICK TSO
• 金额: $ 7.35万
• 依托单位: UNIVERSITY OF CINCINNATI
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-08-15 至 2011-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7896869
• 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; Pathway interactions; Patients; 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

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.

Ezetimibe通过抑制NPC1-L1介导的胆固醇转运抑制胆固醇吸收 肠上皮细胞中的S途径。我们证明了CD36也在胆固醇吸收中发挥作用。它 清道夫受体SR-BI也被证明是另一种可能的胆固醇转运蛋白 在肠道刷状缘膜上。我们假设SR-BI和CD36是体内的胆固醇转运体。 近端和远端的肠分别与NPC1-L1(可能是细胞内的)一起工作以 介导胆固醇从肠腔到细胞内腔的摄取，其中 乳胶粒组装发生。目标1：我们将确定：1)缺少SR-BI、CD36或NPC1L1是否会改变 胆固醇吸收的部位和/或效率(通过改变输液部位或剂量)；以及2)如果 相应的转运蛋白被上调以维持胆固醇的吸收，在缺乏一个或 其他转运蛋白。在淋巴瘘小鼠中，我们还将确定Ezetimibe是否对 抑制这些基因敲除动物的小肠对胆固醇的吸收。目标2：首先，我们将确定 如果亚有效剂量的Ezetimibe与亚有效剂量的熊去氧胆酸盐或 Pluronic F-68(F-68)，抑制大鼠肠道胆固醇吸收。同样，我们也会做出同样的决定 这一现象也适用于鼠标。其次，在上述基因敲除小鼠模型中，我们将 确定Ezetimibe、熊去氧胆酸盐或F-68单独或联合使用是否有效抑制 小肠对胆固醇的吸收。目标3：我们将利用Ezetimibe的能力 抑制肠道胆固醇，以及Pluronic L-81防止乳糜粒形成的能力 途径和数量的胆固醇流出肠细胞通过流出到顶端侧AS 以及通过基底膜分泌的富含甘油三酯的脂蛋白。使用以下组合 Ezetimibe和Pluronic L-81，我们将能够研究胆固醇的摄取和外流 小肠。拟议研究的完成将为我们提供关于胆固醇如何 摄取和淋巴运输由肠道中的各种转运体调节。这些新数据可能 也为临床治疗高胆固醇血症患者提供了新的信息。