Oliver K R, Kane S A, Salvatore C A, Mallee J J, Kinsey A M, Koblan K S, Keyvan-Fouladi N, Heavens R P, Wainwright A, Jacobson M, Dickerson I M, Hill R G
Merck Research Laboratories, Neuroscience Research Centre, Harlow, Essex CM20 QR, UK.
Eur J Neurosci. 2001 Aug;14(4):618-28. doi: 10.1046/j.0953-816x.2001.01688.x.
Calcitonin gene-related peptide (CGRP), adrenomedullin (ADM), amylin and calcitonin (CT) are structurally and functionally related neuropeptides. It has recently been shown that the molecular pharmacology of CGRP and ADM is determined by coexpression of one of three receptor activity-modifying proteins (RAMPs) with calcitonin receptor-like receptor (CRLR). Furthermore, RAMP proteins have also been shown to govern the pharmacology of the calcitonin receptor, which in association with RAMP1 or RAMP3, binds amylin with high affinity. In this study, we have cloned the rat RAMP family and characterized the pharmacology of rat CGRP and ADM receptors. Rat RAMP1, RAMP2 and RAMP3 shared 72%, 69% and 85% homology with their respective human homologues. As expected CRLR-RAMP1 coexpression conferred sensitivity to CGRP, whilst association of RAMP2 or RAMP3 with CRLR conferred high affinity ADM binding. Using specific oligonucleotides we have determined the expression of RAMP1, RAMP2 and RAMP3 mRNAs in the rat central nervous system by in situ hybridization. The localization of RAMP mRNAs was heterogeneous. RAMP1 mRNA was predominantly expressed in cortex, caudate putamen and olfactory tubercles; RAMP2 mRNA was most abundant in hypothalamus; and RAMP3 was restrictively expressed in thalamic nuclei. Interestingly, in specific brain areas only a single RAMP mRNA was often detected, suggesting mutual exclusivity in expression. These data allow predictions to be made of where each RAMP protein may heterodimerize with its partner G-protein-coupled receptor(s) at the cellular level and consequently advance current understanding of cellular sites of action of CGRP, ADM, amylin and CT. Furthermore, these localization data suggest that the RAMP family may associate and modify the behaviour of other, as yet unidentified neurotransmitter receptors.
降钙素基因相关肽（CGRP）、肾上腺髓质素（ADM）、胰淀素和降钙素（CT）是结构和功能相关的神经肽。最近研究表明，CGRP和ADM的分子药理学是由三种受体活性修饰蛋白（RAMP）之一与降钙素受体样受体（CRLR）共表达所决定的。此外，RAMP蛋白还被证明可调控降钙素受体的药理学特性，该受体与RAMP1或RAMP3结合时，能以高亲和力结合胰淀素。在本研究中，我们克隆了大鼠RAMP家族，并对大鼠CGRP和ADM受体的药理学特性进行了表征。大鼠RAMP1、RAMP2和RAMP3与其各自的人类同源物分别具有72%、69%和85%的同源性。正如预期的那样，CRLR - RAMP1共表达赋予了对CGRP的敏感性，而RAMP2或RAMP3与CRLR的结合则赋予了对ADM的高亲和力结合。我们使用特异性寡核苷酸通过原位杂交确定了大鼠中枢神经系统中RAMP1、RAMP2和RAMP3 mRNA的表达。RAMP mRNA的定位是异质性的。RAMP1 mRNA主要在皮质、尾状壳核和嗅结节中表达；RAMP2 mRNA在下丘脑中含量最丰富；而RAMP3则在丘脑核中限制性表达。有趣的是，在特定脑区通常仅检测到单一的RAMP mRNA，这表明表达上存在相互排斥性。这些数据使得我们能够预测每个RAMP蛋白可能在细胞水平上与其伴侣G蛋白偶联受体异源二聚化的位置，从而推进目前对CGRP、ADM、胰淀素和CT细胞作用位点的理解。此外，这些定位数据表明RAMP家族可能与其他尚未确定的神经递质受体相互作用并改变其行为。
