INTESTINAL CELL MEMBRANES: STRUCTURE AND FUNCTION

长期目标是确定肠上皮细胞的作用， 质膜糖蛋白在其分化的控制 转化为功能性吸收细胞 过去25年的工作 已经表明质膜的寡糖 糖蛋白影响细胞间分化 识别和作为细胞粘附因子。 后者很重要 在分化过程中决定组织结构 特别是当质膜分离成结构域时 可以决定载体导向的细胞功能，如吸收。 我们 具体目标是：1）确定结构变化， 肠细胞质膜低聚糖 分化和细胞极性，以及2）将这些变化 肠细胞与肠基底膜（IBM）粘附，以及 对组织组织和正常 肠吸收 大鼠肠细胞将在 代表隐窝-绒毛梯度的组分 分化 不同的域（即，微绒毛， 外侧和基底）的肠上皮细胞质膜将被分离 以及高尔基体的不同部分。 核苷酸糖 易位和新定义的酶特异性不同 将使用高尔基体亚基。 基底富集膜将被 通过免疫细胞学的糖蛋白抗体检测 与基底质膜相连。 IBM可能 成分与基底膜保持联系，或者基底膜 域具有特定的IBM受体将被测试。 寡糖 从这些质膜结构域分离的蛋白质将通过 控制水解、底物和凝集素亲和层析 并通过GLC和HPLC分离。 最初的目标是 确定最具特征的寡糖结构， 特别是质膜结构域。 这些关系 将使用测定来研究寡糖与细胞-IBM粘附 用于细胞粘附;来自IBM的基质将用于测试 组织培养细胞和分离的肠上皮细胞的粘附。 这些研究应该提供肠上皮细胞极性 是在分化过程中形成和维持的。 不完全 分化和肠上皮细胞极性降低是普遍的 肠上皮细胞损伤和功能障碍的表达在许多 肠道疾病。 我们的研究应该有助于 了解组织中的基本细胞生物学控制 组织对肠道吸收和分泌非常重要。

The long-term objective is to define the role of enterocyte plasmelemmal glyco-proteins in the control of its differentiation into a functional absorptive cell. Work over the last 25-years have indicated that the oligosaccharides of plasmalemmal glycoproteins influence cell differentiation as cell-cell recognition and as cell adhesion factors. The latter are important in determining tissue organization during differentiation particularly where the separation of the plasmalemma into domains may determine vector-directed cell function as in absorption. Our specific aims are; 1) to determine the structural changes in enterocyte plasmalemmal oligosaccharides associated with enterocyte differentiation and cell polarity, and 2) to relate these changes to enterocyte-to-intestinal basement membrane (IBM) adhesion, and interrelationship critical to tissue organization and normal intestinal absorption. Rat enterocytes will be isolated in fractions representative of the crypt-to-villus gradient of differentiation. The different domains (i.e., microvillus, lateral, and basal) of the enterocyte plasmalemma will be separated as well as the different parts of the Golgi. Nucleotide-sugar translocation and newly defined enzymes specific for different Golgi subunits will be used. A basal-enriched membrane will be detected by antibodies to glycoproteins immunocytologically associated with the basal plasmalemma. The possibility that IBM components retain association with basal membrane or that the basal domain has specific IBM receptors will be tested. Oligosaccharides isolated from these plasmalemmal domains will be analyzed by controlled hydrolysis, substrate and lectin affinity chromatography and by GLC and HPLC separation. Initially the goal will be to determine the oligosaccharide structures most characteristic of a particular plasmalemmal domain. The relationship of these oligosaccharides to cell-IBM adhesion will be studied using assays for cell adhesion; matrices derived from IBM will be used to test adhesion of tissue culture cells and of isolated enterocytes. these studies should provide information on how enterocyte polarity is developed and maintained during differentiation. Incomplete differentiation and decreased enterocyte polarity are general expressions of enterocyte injury and malfunction seen in many intestinal diseases. Our research should contribute to an understanding of the fundamental cell biology controls in tissue organization so important to intestinal absorption and secretion.