CHARACTERIZATION AND PHARMACOLOGY OF RECEPTORS FOR BOMBESIN RELATED PEPTIDES

蛙皮素相关肽（[gastrin-releasing peptide [GRP]，neuromedin B）与两种不同的受体（GRP-R，NMB-R）相互作用，在胃肠道（GI）、中枢神经系统（CNS）以及正常和肿瘤组织的生长中介导多种效应。此外，最近已经描述了两种相关受体，哺乳动物孤儿受体（BRS- 3），其与GRP-R具有60%的同源性，以及两栖动物中的新受体BB-4-R。该项目的目的是了解这些受体的药理学，分子药理学和细胞生物学，以及开发可用于确定其生理作用的特定激动剂和拮抗剂。正在进行的研究包括这些受体在稳定细胞系中的表达，这些细胞系在细胞生物学和药理学上类似于天然受体;研究使用定点诱变和受体嵌合体来确定受体结构决定因素的配体选择性和特异性的激动剂和拮抗剂，BN相关肽的药理学研究以鉴定选择性激动剂/拮抗剂和天然细胞和转染细胞的研究，以确定这些受体的转导级联。在过去的一年中，研究了新描述的NMB受体拮抗剂PD 168368与4类蛙皮素受体中的每一类相互作用的能力（NPET 290，1202，1999）。该化合物被证明对NMB-R具有高度选择性，作为纯拮抗剂发挥作用，然而，其体内应用的潜力可能受到其在水溶液中的溶解度的限制。使用嵌合NMB-R和GRP-R以及定点诱变，目前正在研究PD 16368 NMB-R选择性的分子基础。初步结果表明，与肽拮抗剂相反，其选择性是通过与受体的跨膜区域相互作用来确定的。目前正在进行研究，以确定参与决定选择性的确切区域和氨基酸。- 蛙皮素受体，胃泌素释放肽，神经介肽B，BRS-3

Bombesin-related peptides ([gastrin-releasing peptide [GRP], neuromedin B) interact with two distinct receptors (GRP-R, NMB-R) to mediate a number of effects in the gastrointestinal tract (GI), central nervous sytem (CNS) and on growth of normal and neoplastic tissues. Furthermore, two related receptors, a mammalian orphan receptor (BRS- 3), having 60% homology to GRP-R and a novel receptor in amphibians, BB-4-R has been described recently. The aims of this project are to understand the pharmacology, molecular pharmacology, and cell biology of these receptors as well as to develop specific agonists and antagonists that can be used to determine their physiological roles. Investigations being performed include expression of these receptors in stable cell lines that resemble native receptors in their cell biology and pharmacology; investigations using site-directed mutagenesis and receptor chimeras to define receptor structural determinants of ligand selectivity and specificity for agonists and antagonists, pharmacological studies of BN-related peptides to identify selective agonists/antagonists and studies of native cells and transfected cells to define the transduction cascades of these receptors. During the last year the ability of a newly described NMB receptor antagonist PD 168368 to interact with each of the 4 classes of bombesin receptors was investigated (NPET 290,1202,1999). This compound was demonstrated to be highly selective for the NMB-R, to function as a pure antagonist, however, its potential for in vivo utility may be limited by its solubility in aqueous solutions. Using chimeric NMB-R and GRP-R as well as site-directed mutagenesis, the molecular basis for PD 16368 NMB-R selectivity is now being investigated. Preliminary results suggest that in contrast to peptide antagonists, its selectivity is determined by interacting with the transmembrane regions of the receptor. Studies are now in progress to define the exact region and amino acids involved in determining selectivity. - bombesin receptors, gastrin-releasing peptide, neuromedin B, BRS-3