Pawlak J B, Wetzel-Strong S E, Dunn M K, Caron K M
Department of Cell Biology and Physiology, 111 Mason Farm Rd., 6312B MBRB CB# 7545, The University of North Carolina, Chapel Hill, NC 27599, USA.
Ferring Research Institute, Inc., 4245 Sorrento Valley Blvd., San Diego, CA 92121, USA.
Peptides. 2017 Feb;88:1-7. doi: 10.1016/j.peptides.2016.12.002. Epub 2016 Dec 8.
Adrenomedullin (AM) and calcitonin gene-related peptide (CGRP) are potent vasodilator peptides and serve as ligands for the G-protein coupled receptor (GPCR) calcitonin receptor-like receptor (CLR/Calcrl). Three GPCR accessory proteins called receptor activity-modifying proteins (RAMPs) modify the ligand binding affinity of the receptor such that the CLR/RAMP1 heterodimer preferably binds CGRP, while CLR/RAMP2 and CLR/RAMP3 have a stronger affinity for AM. Here we determine the contribution of each of the three RAMPs to blood pressure control in response to exogenous AM and CGRP by measuring the blood pressure of mice with genetic reduction or deletion of the receptor components. Thus, the cardiovascular response of Ramp1, Ramp2, Ramp3, Ramp1/Ramp3 double-knockout (dKO), and Calcrl mice to AM and CGRP were compared to wildtype mice. While under anesthesia, Ramp1 male mice had significantly higher basal blood pressure than wildtype males; a difference which was not present in female mice. Additionally, anesthetized Ramp1, Ramp3, and Calcrl male mice exhibited significantly higher basal blood pressure than females of the same genotype. The hypotensive response to intravenously injected AM was greatly attenuated in Ramp1 mice, and to a lesser extent in Ramp3 and Calcrl mice. However, Ramp1/Ramp3 dKO mice retained some hypotensive response to AM. These results suggest that the hypotensive effect of AM is primarily mediated through the CLR/RAMP1 heterodimer, but that AM signaling via CLR/RAMP2 and CLR/RAMP3 also contributes to some hypotensive action. On the other hand, CGRP's hypotensive activity seems to be predominantly through the CLR/RAMP1 heterodimer. With this knowledge, therapeutic AM or CGRP peptides could be designed to cause less hypotension while maintaining canonical receptor-RAMP mediated signaling.
肾上腺髓质素(AM)和降钙素基因相关肽(CGRP)是强效血管舒张肽,作为G蛋白偶联受体(GPCR)降钙素受体样受体(CLR/Calcrl)的配体。三种称为受体活性修饰蛋白(RAMP)的GPCR辅助蛋白可改变受体的配体结合亲和力,使得CLR/RAMP1异二聚体优先结合CGRP,而CLR/RAMP2和CLR/RAMP3对AM具有更强的亲和力。在此,我们通过测量受体成分基因减少或缺失的小鼠的血压,来确定三种RAMP各自对响应外源性AM和CGRP时血压控制的贡献。因此,将Ramp1、Ramp2、Ramp3、Ramp1/Ramp3双敲除(dKO)和Calcrl小鼠对AM和CGRP的心血管反应与野生型小鼠进行了比较。在麻醉状态下,Ramp1雄性小鼠的基础血压显著高于野生型雄性小鼠;雌性小鼠中不存在这种差异。此外,麻醉状态下的Ramp1、Ramp3和Calcrl雄性小鼠的基础血压显著高于相同基因型的雌性小鼠。Ramp1小鼠对静脉注射AM的降压反应大大减弱,Ramp3和Calcrl小鼠的减弱程度较小。然而,Ramp1/Ramp3 dKO小鼠对AM仍保留一些降压反应。这些结果表明,AM的降压作用主要通过CLR/RAMP1异二聚体介导,但通过CLR/RAMP2和CLR/RAMP3的AM信号传导也对某些降压作用有贡献。另一方面,CGRP的降压活性似乎主要通过CLR/RAMP1异二聚体。有了这些知识,就可以设计治疗性AM或CGRP肽,在维持经典受体-RAMP介导信号传导的同时,减少低血压的发生。