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、代谢和路由机制 由极化的小肠吸收细胞（肠上皮细胞）。的 该实验室的长期目标是利用分子和细胞生物学 研究微量营养素代谢和运输的技术 和患病的哺乳动物小肠。的机制， 肠上皮细胞获得、区室化和代谢脂肪酸， 类维生素A的特征很差。人们认为这些过程 与细胞结合蛋白相互作用。两个显著 丰富的脂肪酸结合蛋白（肠和肝脂肪酸 结合蛋白，I-和L-FABP）存在于人类和啮齿类动物中 肠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，CRBP II）也被 存在于胎儿（和可能的成年）大鼠肠上皮细胞中。这些蛋白质 结合疏水性的小胞质蛋白家族的成员 配体。这些蛋白质的生理功能是未知的。一 用于确定这些结合的功能的潜在有用的系统 蛋白质由人肠细胞系Caco-2提供。该细胞 线分化成极化单层， 脂质代谢能力这项建议有两个具体目标：（1） 测定脂肪酸结合的生理作用 外源性脂肪酸在肠道蛋白质代谢中的作用。具体地说， 这将通过使用重组DNA技术来实现， 系统地改变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， 其它脂质将与脂肪酸结合蛋白相关 细胞的表型。(2)生理作用的测定 CRBP II和CRBP在肠道维生素A代谢中的作用这将是 通过比较Caco-2细胞中维生素A的摄取和代谢来探讨 在引入质粒之前和之后， 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.