Characterization And Pharmacology Of Receptors For Gastr

对两组胃肠(GI)多肽进行了药理和分子药理研究。VIP相关多肽[VIP相关多肽[VIP，PACAP]在胃肠道和中枢神经系统具有广泛的作用。VIP-PACAP相关多肽的作用由三种受体(VPAC1、VPAC2、PACAP-R)介导。该项目的研究旨在了解这些不同受体的作用的分子基础，并开发具有激动剂或拮抗剂功能的代谢稳定的选择性配体。为了明确VIP受体的药理作用，我们克隆了VPAC1和VPAC2受体，并将其稳定地导入CHO和PANC1细胞中。VIP药效团正在通过丙氨酸和D-氨基酸筛选为每个VPAC-R亚型确定，以尝试识别选择性配体。去年报告了VPAC1的结果，今年我们已经完成了人和大鼠VPAC2药效团的定义。VIP的3、6、7、10、12、22和23位氨基酸是高亲和力所必需的，而2、8、9、16、19、20、21、24和25位氨基酸侧链则不是必需的。与VPAC1的比较表明，7、10、11、22位的侧链对VPAC2的高亲和力更为重要。大鼠VPAC2与人VPAC2之间存在显著的物种差异。本研究为开发简化的VIP类似物和VPAC各亚型的选择性配体奠定了基础。蛙皮素相关肽(胃泌素释放肽[GRP]、神经介素B)与两种不同的受体(GRP-R、NMB-R)相互作用，在胃肠道和中枢神经系统(CNS)中发挥多种作用。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。我们的结果表明，第三胞外区(EC-3)的关键氨基酸对GRP的选择性起作用。尤其重要的是，与NMBR相比，GRPR中用ILE代替了Phe185，用ILE代替了Ala198。定点突变研究表明，这种选择性主要是由这些配体和受体之间的氢键和pi-阳离子相互作用所介导的。我们的结果表明，GRPR的Phe185芳环与GRP之间的相互作用对GRP的选择性是最重要的。目前，NMBR正在进行类似的研究。

The pharmacology and molecular pharmacology of two groups of gastrointestinal (GI)peptides were investigated. VIP-related peptides [VIP-related peptides [VIP, PACAP] have widespread effects in the GI tract and central nervous system. The actions of VIP-PACAP-related peptides are mediated by three receptors (VPAC1, VPAC2, PACAP-R). Studies in this project are aimed at understanding the molecular basis of action of these different receptors and at developing selective metabolically stable ligands that function as agonists or antagonists. To define the pharmacology of VIP receptors, the VPAC1 and VPAC2 receptors have been cloned and stably transfected in CHO and PANC1 cells. The VIP pharmacophore is being determined for each VPAC-R subtype by alanine and D-amino acid screening, to attempt to identify selective ligands. Last year results for the VPAC1 were reported and this year we have completed the definition of the human and rat VPAC2 pharmacophore. Amino acids in position 3,6,7,10,12,22 and 23 of VIP were essential for high affinity whereas side chains of amino acids in 2,8,9,16,19,20,21,24, and 25 were not essential. Comparison with VPAC1 show side chains in position 7,10,11,22 were more important for high affinity for VPAC2. There were significant species differences between rat and human VPAC2. This study provides a basis for development of simplified VIP analogues and selective ligands for each VPAC subtype. 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 GI tract and central nervous sytem (CNS). The aims of this project are to understand the pharmacology, molecular pharmacology, and cell biology of these receptors. Our results demonstrate the critical amino acids in the 3rd extracellular domain (EC-3) are responsible for GRP selectivity. Particularly important is the substitution of the Ile for Phe185 and Ile for Ala198 in the GRPR compared to the NMBR. Site-directed mutagenesis studies showed this selectivity was primarily mediated by hydrogen bonding and pi-cation interactions between these ligands and the receptor. Our results suggest an interaction between the aromatic ring of Phe185 of the GRPR with GRP is the most important for GRP selectivity. Similar studies are now underway with the NMBR.