NUTRIENT REGULATION OF SUCRASE A-DEXTRINASE MATURATION

描述（改编自研究者的摘要和/或目的）： 大鼠的胃肠道经历了戏剧性的成熟变化 在生命的第三周， 动力学和酶活性。 蔗糖酶-α-糊精酶，糖蛋白 水解酶是膳食碳水化合物最终吸收所必需的， 在肠上皮细胞的刷状缘膜表面， 在生命的第三周，它突然出现并迅速上升，作为一个 出生后肠道成熟的主要区别特征。 虽然 调节S-D成熟的机制尚不清楚，但有明确的 有证据表明，管腔营养物质是完全成熟所必需的 S-D的表达。 申请人开发的独特动物模型， 现在已经很好地建立起来，将与先进的 细胞和分子生物学技术，以研究 营养依赖性S-D成熟的机制。 初步研究将 确定鲁米那碳水化合物对体内合成的影响， 使用技术在成熟肠中组装和降解S-D 新生S-D肽的管腔内放射性标记和研究 酶在其合成、装配和最终插入的各个阶段 进入灌木丛边缘 这些研究将确定是否动力学 细胞内转运，S-D前体的结构或 S-D的降解被鲁米那碳水化合物改变。 后续 研究将确定管腔碳水化合物是否调节S-D 通过测量特定mRNA通过转录或翻译成熟 S-D，使用申请人开发的cDNA探针，使用聚合酶链 反应（PCR）技术和分析S-D结构，细胞内 使用糖苷酶探针的组装和插入后加工， 2-双向凝胶电泳和氨基酸序列测定 蛋白 为了确定管腔营养物质是否直接作用于 肠上皮细胞，对肠腔营养的S-D反应 在器官培养物中，将沿着隐窝-绒毛轴的吸收细胞 研究了 在稳态条件下进行的这些研究将 补充了S-D急性诱导的类似研究， 由申请人开发的肠灌注技术， 婴儿动物，以确定是否有单一的机制或 多种机制的组合参与S-D反应。 这些研究 将产生新的信息的机制， 营养素在出生后肠道发育过程中调节S-D成熟。

DESCRIPTION (adapted from investigator's abstract and/or aims): The gastrointestinal tract of the rat undergoes dramatic maturational changes during the third week of life resulting in major changes in cellular kinetics and enzyme activities. Sucrase-alpha-dextrinase, a glycoprotein hydrolase required for final absorption of dietary carbohydrate and located at the brush border membrane surface of the enterocyte, is absent prior to the third week of life when it abruptly appears and rises rapidly, as a major distinguishing feature of postnatal intestinal maturation. Although the mechanisms regulating S-D maturation are not known, there is clear evidence that luminal nutrients are required for full maturational expression of S-D. A unique animal model developed by the applicant which is now well established will be used in combination with advanced techniques of cellular and molecular biology in order to investigate the mechanisms of nutrient-dependent S-D maturation. Initial studies will determine the effect of luminal carbohydrate on the in-vivo synthesis, assembly and degradation of S-D in the maturing intestine using techniques of intraluminal radiolabeling of the nascent S-D peptide and investigating the enzyme at various stages of its synthesis, assembly and final insertion into the brush border. These studies will determine whether the kinetics of intracellular transport, the structure of S-D precursors or the degradation of S-D are altered by luminal carbohydrates. Subsequent studies will determine whether luminal carbohydrate regulates S-D maturation by transcription or translation by measuring specific mRNA for S-D using cDNA probes developed by the applicant using polymerase chain reaction (PCR) techniques and analyzing S-D structure, intracellular assembly and post-insertional processing using glycosidase probes, 2-dimensional gel electrophoresis and amino acid sequencing of the S-D protein. In order to determine whether luminal nutrients act directly on the enterocyte, the S-D response to luminal nutrients of the intestinal absorptive cells along the crypt-villus axis and in organ culture will be studied. These studies performed during steady-state conditions will be complemented by analogous studies of acute induction of S-D using intestinal perfusion techniques developed by the applicant for use in infant animals in order to determine whether a single mechanism or combinations of mechanisms participate in the S-D response. These studies will generate new information on the mechanisms by which intraluminal nutrients regulate S-D maturation during postnatal intestinal development.