Distinct Patterns of Internalization of Different Calcitonin Gene-Related Peptide Receptors

Calcitonin
gene-related peptide (CGRP) is a neuropeptide that is
involved in the transmission of pain. Drugs targeting CGRP or a CGRP
receptor are efficacious in the treatment of migraine. The canonical
CGRP receptor is a complex of a G protein-coupled receptor, the calcitonin-like
receptor (CLR), with an accessory protein, receptor activity-modifying
protein 1 (RAMP1). A second receptor, the AMY1 receptor,
a complex of the calcitonin receptor with RAMP1, is a dual high-affinity
receptor for CGRP and amylin. Receptor regulatory processes, such
as internalization, are crucial for controlling peptide and drug responsiveness.
Given the importance of CGRP receptor activity in migraine we compared
the internalization profiles of both receptors for CGRP using novel
fluorescent probes and a combination of live cell imaging, fixed cell
imaging, and ELISA. This revealed stark differences in the regulation
of each receptor with the AMY1 receptor unexpectedly showing
little internalization.

降钙素基因相关肽（Calcitonin gene-related peptide, CGRP）是一类参与疼痛信号传递的神经肽。以CGRP或CGRP受体为靶点的药物在偏头痛治疗中具有确切疗效。经典CGRP受体是G蛋白偶联受体降钙素样受体（calcitonin-like receptor, CLR）与辅助蛋白受体活性修饰蛋白1（receptor activity-modifying protein 1, RAMP1）组成的复合物。第二类受体AMY1受体则是降钙素受体与RAMP1形成的复合物，是CGRP与胰淀素（amylin）的双重高亲和力受体。受体内吞等受体调控过程对调控肽类物质与药物的应答反应至关重要。鉴于CGRP受体活性在偏头痛发病中的重要意义，我们采用新型荧光探针，结合活细胞成像、固定细胞成像与酶联免疫吸附测定（ELISA）技术，对比了两种受体对CGRP的内吞特征。结果显示两种受体的调控模式存在显著差异：AMY1受体意外地仅表现出极微弱的内吞现象。