INTESTINAL CELL MEMBRANES: STRUCTURE AND FUNCTION

长期目标是确定肠细胞的作用 质膜糖蛋白对其分化的调控作用 变成一个功能性吸收细胞。过去25年的工作 已经表明，质膜的寡糖 糖蛋白作为细胞-细胞影响细胞分化 识别和作为细胞黏附因子。后者很重要 在确定分化过程中的组织结构时 尤其是在质膜分离成域的情况下 可能决定载体导向的细胞功能，如吸收。我们的 具体目标是：1)确定 与肠细胞相关的肠细胞质膜低聚糖 分化和细胞极性，以及2)将这些变化联系起来 到肠细胞与肠基底膜(IBM)的黏附，以及 对组织和正常组织至关重要的相互关系 肠道吸收。大鼠肠上皮细胞将在 代表隐窝到绒毛梯度的组分 差异化。不同的结构域(即，微绒毛， 肠细胞质膜的侧向和基面)将被分离 以及高尔基山脉的不同部分。核苷酸-糖 易位和新定义的不同类型的酶 将使用高尔基亚基。一种富含基底的膜将被 糖蛋白抗体免疫细胞学检测 与基质膜相关。IBM有可能 组件与基底膜保持联系或基底膜 域中是否有特定的IBM受体将接受测试。低聚糖 从这些质膜结构域中分离出来的蛋白质将通过 受控水解、底物和凝集素亲和层析 并用气相色谱和高效液相色谱分离。最初的目标将是 确定低聚糖的最具特征的结构 特定的质膜结构域。它们之间的关系 低聚糖对细胞-IBM的粘附性将使用分析方法进行研究 用于细胞黏附；从IBM派生的矩阵将用于测试 组织培养细胞和分离的肠细胞的粘附性。 这些研究应该提供有关肠道细胞极性如何 在分化过程中被发展和维持。不完整 分化和肠道细胞极性降低是普遍现象。 肠细胞损伤和功能障碍在许多情况下的表现 肠道疾病。我们的研究应该有助于 对组织中基本的细胞生物学控制的理解 对肠道吸收和分泌如此重要的组织。

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.