Characterization And Pharmacology Of Receptors For Gastrointestinal Peptides

胃肠肽受体的表征和药理学

• 批准号: 7593650
• 负责人: Robert Jensen
• 金额: $ 35.97万
• 依托单位: NATIONAL INSTITUTE OF DIABETES AND DIGESTIVE AND KIDNEY DISEASES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/7593650
• 关键词: Affinity; Agonist; Amino Acid Substitution; Amino Acids; BRS3 gene; Binding; Bombesin; Bombesin Receptor; Camptothecin; Cytotoxic agent; Family; GRP gene; Gastrin releasing peptide; Gastrointestinal Hormone Receptors; Gastrointestinal Hormones; Gastrointestinal tract structure; Goals; Human; Ligands; Mediating; Molecular; Neuraxis; Numbers; Orphan; PACAP27; Pathologic Processes; Peptide Receptor; Peptides; Pharmacology; Physiological; Protocols documentation; Role; Secretin; Site-Directed Mutagenesis; Somatostatin; Structure; Therapeutic; Topoisomerase Inhibitors; Vasoactive Intestinal Peptide; Vasoactive Intestinal Peptide Receptors; analog; bombesin receptor subtype 3; cancer cell; gastrointestinal; member; molecular modeling; neoplastic cell; neuromedin B; receptor; somatostatin analog; vasoactive intestinal peptide receptor 1

The pharmacology and molecular pharmacology of various gastrointestinal (GI) peptides are being investigated. Three peptide receptor families investigated during the year are those for bombesin- (Bn) related peptides, somatatostatin (SS) family and for VIP-related peptides. Bn-related peptides (GRP, NMB) interact primarily with three distinct receptors (GRP-R, NMB-R)and the orphan receptor, BRS-3 to mediate a number of effects in the GI tract and central nervous system (CNS). Using information from structure-function studies by us and others we have synthesized high affinity Bn, VIP and somatostatin analogues that were metabolically stable and that be could to cytotoxic agents such as the topoisomerase inhibitor, camptothecin (CPT), which had potent antitumor activity against various human tumor cells. We demonstrated using inactive chemically identical analogues that this tumoricidal effect was mediated by the peptide receptors expressed on the cancer cells. To identify key amino acids responsible for selective high affinity binding of various agonists for different members of the bombesin receptor family we used an analysis of the structural homologies of different receptors of this family and site-directed mutagenesis. Between the GRP receptor and BRS-3 receptor which different by >1000 in their affinity for bombesin (BN) we found 14 important amino acid differences which were then substituted in each receptor. Molecular modeling and pharmacology studies showed 7 of these were important for high affinity for Bn and contributed to the selectivity of these receptors demonstrating this is a useful approach to identify amino acid important for selectivity and affinity. A second aspect of our studies is to develop selective receptor ligands for Bn or VIP receptor subtypes that could be metabolically stable. To accomplish this for the human BRS-3 receptor, which has no selective ligands, we made N-Methyl substitutions, D-amino acid substitutions, truncations and substitutions of various amino acids in a nonselective ligand that we had discovered that interacted with this receptor with high affinity. One analog DTyr6, Apa-4 Cl, Phe13, Nle14-Bn (6-14) was found to have a marked enhanced selectivity for the human BRS3 receptor over the other receptors of this family. This analogue was found to have greater affinity and selectivity than other recently described BRS-3 selective ligands and thus should be useful to investigate its role in physiological and pathological processes. Furthermore, using our previous ligand structure function studies we were able to construct simplified analogs of the 28 amino acid peptide VIP that were metabolically stable and had high affinity and selectivity for VPAC1 receptors.

各种胃肠道（GI）肽的药理学和分子药理学正在研究中。今年研究的三个肽受体家族是铃蟾肽 (Bn) 相关肽、生长抑素 (SS) 家族和 VIP 相关肽。 Bn 相关肽（GRP、NMB）主要与三种不同的受体（GRP-R、NMB-R）和孤儿受体 BRS-3 相互作用，介导胃肠道和中枢神经系统 (CNS) 中的多种作用。利用我们和其他人的结构功能研究的信息，我们合成了高亲和力的 Bn、VIP 和生长抑素类似物，这些类似物代谢稳定，可用于拓扑异构酶抑制剂喜树碱 (CPT) 等细胞毒性药物，对拓扑异构酶抑制剂喜树碱 (CPT) 具有有效的抗肿瘤活性。各种人类肿瘤细胞。我们使用化学性质相同的无活性类似物证明，这种杀肿瘤作用是由癌细胞上表达的肽受体介导的。 为了鉴定负责各种激动剂对铃蟾肽受体家族不同成员的选择性高亲和力结合的关键氨基酸，我们使用了该家族不同受体的结构同源性分析和定点诱变。 在 GRP 受体和 BRS-3 受体之间，它们对铃蟾肽 (BN) 的亲和力相差 > 1000，我们发现了 14 个重要的氨基酸差异，然后在每个受体中进行了替换。 分子模型和药理学研究表明，其中 7 个对于 Bn 的高亲和力很重要，并有助于这些受体的选择性，证明这是鉴定对选择性和亲和力重要的氨基酸的有用方法。我们研究的第二个方面是开发代谢稳定的 Bn 或 VIP 受体亚型的选择性受体配体。为了对没有选择性配体的人类 BRS-3 受体实现这一目标，我们在我们发现与该受体相互作用的非选择性配体中进行了 N-甲基取代、D-氨基酸取代、截短和各种氨基酸的取代具有高亲和力。研究发现，与该家族的其他受体相比，一种类似物 DTyr6、Apa-4 Cl、Phe13、Nle14-Bn (6-14) 对人 BRS3 受体的选择性显着增强。人们发现这种类似物比其他最近描述的 BRS-3 选择性配体具有更大的亲和力和选择性，因此应该有助于研究其在生理和病理过程中的作用。 此外，利用我们之前的配体结构功能研究，我们能够构建 28 个氨基酸肽 VIP 的简化类似物，其代谢稳定，并且对 VPAC1 受体具有高亲和力和选择性。