Hypertension and dysregulated proinflammatory cytokine production in receptor activity-modifying protein 1-deficient mice

Abstract

Calcitonin gene-related peptide (CGRP) is thought to be a prominent neuropeptide in cardiovascular regulation and neuroimmune modulation. There are two isoforms of CGRP (␣CGRP and ␤CGRP), and the main CGRP receptors are probably composed of a calcitonin receptor-like receptor (CLR) and a receptor activity-modifying protein (RAMP)1. However, the physiological functions of CGRP that are mediated through the CLR/RAMP1 receptors remain to be clarified. For an improved understanding of the functions, we generated mice deficient in RAMP1, a specific subunit of CGRP receptors, by a conditional gene-targeting technique. The RAMP1-deficient mice (RAMP1 ؊/؊ ) exhibited high blood pressure, with no changes in heart rate. ␣CGRP was found to have a potent vascular relaxant activity compared with ␤CGRP in the artery of the WT (RAMP1 ؉/؉ ) mice. The activities of both CGRP isoforms were remarkably suppressed in the arteries of the RAMP1 ؊/؊ mice. The LPS-induced inflammatory responses of the RAMP1 ؊/؊ mice revealed a transient and significant increase in the serum CGRP levels and high serum levels of proinflammatory cytokines compared with the RAMP1 ؉/؉ mice. ␣CGRP and ␤CGRP equally suppressed the production of TNF-␣ and IL-12 in bone marrow-derived dendritic cells stimulated with lipopolysaccharide. Their inhibitory effects were not observed in the bone marrow-derived dendritic cells of the RAMP1 ؊/؊ mice. These results indicate that CGRP signaling through CLR/RAMP1 receptors plays a crucial role in the regulation of both blood pressure by vascular relaxation and proinflammatory cytokine production from dendritic cells.gene-disrupted mice ͉ calcitonin gene-related peptide ͉ adrenomedullin ͉ neuropeptide ͉ dendritic cells C alcitonin gene-related peptide (CGRP) is a 37-aa neuropeptide that is produced in the neural body of dorsal root ganglion cells and released from sensory nerve endings. There are two isoforms of CGRP: ␣ and ␤ in rats and mice and I and II in humans. These differ in their peptide sequences by 1 aa (rats) and 3 aa (mice and humans) of the 37 aa (1). ␣CGRP is produced mainly in the nervous system by the tissue-specific alternative splicing of the primary RNA transcript of the calcitonin/CGRP gene. On the other hand, ␤CGRP is produced not only in the neuronal tissues but also in the enteric nerves of the intestine (2) and in immune cells such as T cells (3). Pharmacologically, ␣CGRP is known to have the most potent vasodilatory activity (4). Most blood vessels are surrounded by a dense perivascular CGRPergic neural network, suggesting the physiological importance of CGRP in vasodilatory regulation (5). ␣CGRP also contributes to local neurogenic inflammation and nociception (6). Moreover, the functions of immune cells such as macrophages (7,8), Langerhans cells (8), and T cells (9, 10) are modulated by ␣CGRP. However, the precise functional differences between ␣CGRP and ␤CGRP remain unclear.Historically, CGRP receptors have been classified into two classes: CGRP 1 and CGRP 2 receptors. The CGRP 1 receptors are m...

Calcitonin Gene-Related Peptide and Cyclic Adenosine 5′-Monophosphate/Protein Kinase A Pathway Promote IL-9 Production in Th9 Differentiation Process

“…Lck-Cre transgenic mice were purchased from The Jackson Laboratory (Bar Harbor, ME). RAMP1-deficient mice were generated (32), and heterozygous knockout mice were backcrossed for 12 generations to C57BL/6 or BALB/c mice and used to generate the offspring used in the current study. All procedures, including experimental animals, were approved by the Experimental Animal Care and Use Committee of the Graduate School of Pharmaceutical Sciences, Osaka University.…”

“…1B). Incidentally, we estimate that the physiological concentration of CGRP is between 0.1 and 10 nM based on measurements of the CGRP concentration in serum (32). Therefore, the concentration (1 nM) of CGRP for promoting IL-9 seems to be adequate.…”

“…Finally, we investigated the physiological role of CGRP in Th9 cell development using RAMP1-deficient mice, which indicates a specific deletion of CGRP signaling (32). OVA-induced airway inflammation is a type I hypersensitivity, and this model is characterized by the infiltration of inflammation cells and airway resistance.…”

Haplotype-based case–control study of receptor (calcitonin) activity-modifying protein-1 gene in cerebral infarction

“…In addition, aCGRP and bCGRP appear to equally suppress the production of tumour necrosis factor-a and interleukin-12 in bone marrow-derived dendritic cells stimulated with lipopolysaccharide. 7 Um et al reported that the expression of IL-1 in the brain was increased during the early and chronic stage of CI. 8 The aim of this study was to investigate the relationship between CI and human RAMP 1 gene using single-nucleotide polymorphisms (SNPs) and haplotypes in a Japanese population.…”

“…RAMP1-deficient mice (RAMP1(À/À)) show inflammatory responses and CGRP signalling through CLR/ RAMP1 receptors, which have a crucial role in the regulation of proinflammatory cytokine production in dendritic cells. 7 Furthermore, Sundararajan et al 20 reported that the administration of troglitazone or pioglitazone 24 h before PPAR-g ligands markedly reduces infarction volume and improves neurological function following middle cerebral artery occlusion in rats. It is known that drugtreated animals show reduced inflammation, as evidenced by decreased immunoreactivity for microglial/macrophage markers and reduced interleukin-1b, cyclooxygenase-2 and inducible nitric oxide synthase.…”