Molecular Mechanisms of GI Peptide Hormone Processing

描述(申请人提供)：胃肠激素 在他们实现其目标之前进行广泛的翻译后修改 与生物相关的形式。阐明这些过程是很重要的 机制，因为它们导致组织特异性地产生不同的 生物活性多肽。在过去的资助期间，我们描述了两个 重要的加工反应--内切蛋白分解和c-末端酰胺化。在……里面 我们注意到的初步数据是，前列腺素S(Pross)在单个和 双碱性氨基酸残基由不同的酶执行，导致 形成2个不同的多肽(分别为SS-28和SS-14)。虽然 用于二元加工的酶和分子决定因素已经被 其特点广泛，但对单细胞激素原的作用知之甚少。 在其他研究中，我们注意到酰胺化的直接加工前体 胃泌素(甘氨酸延伸胃泌素，G-Gly)是胃泌素的一种独特的终产物 具有营养效应的生物合成由不同于 介导酰胺化胃泌素效应的胃泌素/CCK8受体。这个 G-甘氨酸转化为酰胺化胃泌素是由库珀依赖的 肽甘氨酸α-酰胺化单加氧酶(PAM)。最近，我们的 合作者分离出一种编码铜转运蛋白的重要基因 (Menkes蛋白)。在本提案中，我们将延长以前的 观察和研究Menkes蛋白在多肽酰胺化中的作用， 胃泌素的生物合成和胃肠功能。因此，朝着...的目标 多肽加工及其分子决定因素的研究进展 与胃肠生理学的关系，我们将在以前的基础上扩展 工作和重点放在以下具体目标上：1)表征分子 前激素内切蛋白分解的决定因素 前生长抑素；以及2)确定Menkes蛋白在多肽中的作用 利用内分泌细胞系的酰胺化和胃肠功能 铜转运紊乱的小鼠模型，以及在人类中 门克斯综合征及相关疾病患者的血清。因为这些 加工反应是多种神经内分泌前体的共同特征， 这些调查的结果也将有助于我们了解 调节其他肠道和肠道激素原处理的分子机制 神经内分泌组织。

DESCRIPTION (provided by applicant): Gastrointestinal peptide hormones undergo extensive post-translational modification before they achieve their biologically relevant forms. It is important to elucidate these processing mechanisms since they result in the tissue-specific generation of distinct bioactive peptides. During the past funding period we characterized two important processing reactions-endoproteolysis and c-terminal amidation. In preliminary data we noted that prosomatostatin (proSS) is cleaved at single and double basic amino acid residues are performed by distinct enzymes leading to the formation of 2 distinct peptides (SS-28 and SS-14, respectively). Although the enzymes and molecular determinants for dibasic processing have been extensively characterized, little is known of monobasic prohormone processing. In other studies, we noted that the immediate processing precursor of amidated gastrin (glycine-extended gastrin, G-Gly) is a distinct end product of gastrin biosynthesis with trophic effects mediated by a receptor distinct from the gastrin/CCK8 receptors that mediate the effects of amidated gastrin. The conversion of G-Gly to amidated gastrin is mediated by a cooper-dependent enzyme, peptidyl-glycine alpha-amidating monooxygenase (PAM). Recently, our collaborators have isolated an important gene encoding a copper transporter (Menkes protein). In the present proposal we will extend our previous observations and examine the role of the Menkes protein in peptide amidation, gastrin biosynthesis and gastrointestinal function. Thus, toward the goal of elucidating the molecular determinants of peptide processing and its relationships to gastrointestinal physiology we will expand upon our previous work and focus on the following specific aims: 1) Characterize the molecular determinants of prohormone endoproteolysis single basic amino acids found in prosomatostatin; and 2) define the role of the Menkes protein in peptide amidation and gastrointestinal function utilizing endocrine cell lines, a well-characterized mouse model of disordered copper transport, and in human sera from patients with Menkes syndrome and related disorders. Since these processing reactions are common to a wide variety of neuroendocrine precursors, the results of these investigations will also aid in our understanding of the molecular mechanisms that regulate prohormone processing in other gut and neuroendocrine tissues.