Molecular Mechanisms of GI Peptide Hormone Processing

描述（由申请人提供）：胃肠道肽类激素 广泛的翻译后修饰之前，他们实现其 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产生不同的 生物活性肽在过去的资助期间，我们描述了两个 重要的加工反应-蛋白质内水解和C-末端酰胺化。在 初步数据我们注意到，促生长素抑制素（proSS）在单个和 双碱性氨基酸残基由不同的酶进行， 形成2种不同的肽（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 广泛表征的是，很少有人知道的monoblycerprohormone加工。 在其他研究中，我们注意到酰胺化的直接加工前体 胃泌素（甘氨酸延伸的胃泌素，G-Gly）是胃泌素的独特终产物 生物合成与营养作用介导的受体不同， 胃泌素/CCK 8受体介导酰胺化胃泌素的作用。的 G-Gly向酰胺化胃泌素的转化是由库珀依赖的 酶，肽基-甘氨酸α-酰胺化单加氧酶（PAM）。最近我们 合作者已经分离出一个重要的基因编码铜转运蛋白 （Menkes蛋白）。在目前的建议中，我们将扩大我们以前的 观察并检查Menkes蛋白在肽酰胺化中的作用， 胃泌素生物合成和胃肠功能。因此，为了实现 阐明肽加工的分子决定因素及其 与胃肠道生理学的关系，我们将扩大我们以前的 工作，并专注于以下具体目标：1）表征分子 激素原内蛋白水解的决定因素 促生长素抑制素原;和2）定义Menkes蛋白在肽中的作用 利用内分泌细胞系的酰胺化和胃肠功能， 良好表征的铜转运紊乱的小鼠模型，以及在人类中 来自门克斯综合征和相关疾病患者的血清。由于这些 加工反应对于多种神经内分泌前体是常见的， 这些调查的结果也将有助于我们了解 调节其他肠道激素原加工的分子机制， 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.