GUT NUTRIENT METABOLISM: MOLECULAR CELLULAR APPROACHES

肠道生理学的基本挑战之一是阐明 微量营养素的吸收、代谢和转运机制 通过极化的小肠吸收细胞(肠细胞)。这个 这个实验室的长期目标是利用分子和细胞生物学 研究正常人群微量营养素代谢和转运的技术 和患病的哺乳动物小肠。通过这些机制， 肠细胞获取、分割和代谢脂肪酸和 维甲酸的特性很差。据认为，这些过程 涉及与细胞结合蛋白的相互作用。值得注意的是，两个 丰富的脂肪酸结合蛋白(肠道和肝脏脂肪酸 结合蛋白I-和L-FABP)存在于人和啮齿动物体内 肠道细胞。两种视黄醇结合蛋白(细胞视黄醇结合 蛋白质、CRBP和细胞视黄醇结合蛋白II)也是 存在于胎鼠(也可能是成年鼠)的肠道细胞中。这些蛋白质是 疏水蛋白家族中结合疏水性的小的胞质蛋白家族的成员 配基。这些蛋白质的生理功能尚不清楚。一个 用于确定这些绑定的功能的潜在有用的系统 蛋白质由人类肠道细胞系Caco-2提供。这间牢房 LINE分化成一个已经很发达的偏振单分子层 脂类，代谢能力。这项建议有两个具体目标：(一) 脂肪酸结合的生理作用的测定(S) 外源脂肪酸在肠道代谢中的蛋白质。具体来说， 这将通过使用重组DNA技术来实现 系统改变Caco-2中脂肪酸结合蛋白的含量 细胞。长链脂肪酸代谢过程的变化和 其他脂类将与脂肪酸结合蛋白相关。 细胞的表型。(二)生理角色的确定(S) CRBP II和CRBP在肠道维生素A代谢中的作用这将是 比较Caco-2细胞对维生素A的摄取和代谢 在引入指导合成的质粒之前和之后 CRBP II和/或CRBP mRNA。

One of the fundamental challenges in intestinal physiology is to elucidate the mechanisms by which micronutrients are absorbed, metabolized and routed by the polarized small intestinal absorptive cell (enterocyte). The long-term goal of this laboratory is to use molecular and cell biological techniques to study micronutrient metabolism and trafficking in the normal and diseased mammalian small intestine. The mechanisms by which the enterocyte acquires, compartmentalizes and metabolizes fatty acids and retinoids are poorly characterized. It is thought that these processes involve interactions with cellular binding proteins. Two remarkably abundant fatty acid binding proteins (intestinal and liver fatty acid binding proteins, I- and L-FABP) are present in human and rodent enterocytes. Two retinol binding proteins (cellular retinol binding protein, CRBP and cellular retinol binding protein II, CRBP II) are also present in fetal (and possibly adult) rat enterocytes. These proteins are members of a family of small, cytosolic proteins that bind hydrophobic ligands. The physiological functions of these proteins are unknown. A potentially useful system for determining the functions of these binding proteins is provided by the human intestinal cell line, Caco-2. This cell line differentiates into a polarized monolayer which has well developed lipid, metabolic capabilities. This proposal has two specific aims: (1) determination of the physiological role(s) of the fatty acid binding proteins in intestinal metabolism of exogenous fatty acids. Specifically, this will be accomplished by using recombinant DNA techniques to systematically alter the content of fatty acid binding proteins in Caco-2 cells. Changes in the metabolic processing of long chain fatty acids and other lipids will be correlated with the fatty acid binding protein phenotype of the cells. (2) determination of the physiological role(s) of CRBP II and CRBP in intestinal vitamin A metabolism. This will be approached by comparing vitamin A uptake and metabolism in Caco-2 cells before and after the introduction of plasmids that direct the synthesis of CRBP II and/or CRBP mRNA.