Molecular simulations reveal the impact of RAMP1 on ligand binding and dynamics of calcitonin gene-related peptide receptor (CGRPR) heterodimer

Calcitonin gene-related peptide receptor (CGRPR) is a heterodimer protein complex consisting of a class-B G protein-coupled receptor (GPCR) named calcitonin receptor-like receptor (CLR) and an accessory protein, receptor activity modifying protein type 1 (RAMP1). Here in this study, with several molecular modeling approaches and molecular dynamics (MD) simulations, the structural and dynamical effects of RAMP1 on the binding of small molecule CGRPR inhibitors (namely rimegepant and telcagepant) to the CGRPR extracellular ectodomain complex site (site 1) and transmembrane binding site (site 2) are investigated. Results showed that although these molecules stay stable at site 1, they can also bind to site 2, which may be interpreted as non-specificity of the ligands, however, most of these interactions at transmembrane binding site are not sustainable or are weak. Furthermore, to examine the site 2 for gepant binding, different in silico experiments (i.e., alanine scanning mutagenesis, SiteMap, ligand decomposition binding free energy analyses) are also conducted and the results confirmed the putative binding pocket (site 2) of the gepants at the CGRPRs.

Possible involvement of neuropeptide and neurotransmitter receptors in Adenomyosis

BACKGROUND

Accumulating data indicate that sensory nerve derived neuropeptides such as substance P and calcitonin gene related-protein (CGRP) can accelerate the progression of endometriosis via their respective receptors, so can agonists to their respective receptors receptor 1 (NK1R), receptor activity modifying protein 1 (RAMP-1) and calcitonin receptor-like receptor (CRLR). Adrenergic β2 receptor (ADRB2) agonists also can facilitate lesional progression. In contrast, women with endometriosis appear to have depressed vagal activity, concordant with reduced expression of α7 nicotinic acetylcholine receptor (α7nAChR). The roles of these receptors in adenomyosis are completely unknown.

METHODS

Adenomyotic tissue samples from 30 women with adenomyosis and control endometrial tissue samples from 24 women without adenomyosis were collected and subjected to immunohistochemistry analysis of RAMP1, CRLR, NK1R, ADRB2 and α7nAChR, along with their demographic and clinical information. The extent of tissue fibrosis was evaluated by Masson trichrome staining.

RESULTS

We found that the staining levels of NK1R, CRLR, RAMP1 and ADRB2 were all significantly elevated in adenomyotic lesions as compared with control endometrium. In contrast, α7nAChR staining levels were significantly reduced. The severity of dysmenorrhea correlated positively with lesional ADRB2 staining levels.

CONCLUSIONS

Our results suggest that SP, CGRP and noradrenaline may promote, while acetylcholine may stall, the progression of adenomyosis through their respective receptors on adenomyotic lesions. Additionally, through the activation of the hypothalamic-pituitary-adrenal (HPA)-sympatho-adrenal-medullary (SAM) axes and the lesional overexpression of ADRB2, adenomyosis-associated dysmenorrhea and adenomyotic lesions may be mutually promotional, forming a viscous feed-forward cycle.

[Study on the correlation between prognosis of patients with chronic hepatitis B under interferon treatment and polymorphism of both calcitonin gene related peptide and receptor activity modifying protein 1]

Objective: To analyze the association of two single-nucleotide polymorphisms (SNP) [Calcitonin gene related peptide (CGRP) rs155209 and receptor activity modifying protein 1 (RAMP1) rs3754701] and the prognosis of chronic hepatitis B patients who were under interferon therapy. Methods: A total of 317 patients and their anticoagulant blood samples were collected in this study. The SNPs in the CGRP and region RAMP1 were genotyped using matrix-assisted laser desorption/ionization time of flight mass spectrometry. Logistic regression method was used to assess the results from different phenotypic outcomes between cases and controls, after adjusted for sex and age in co-dominant, dominant and recessive genetic models. Results: Data from this study clearly demonstrated the relevance of CGRP rs155209 and RAMP1 rs3754701 with DNA response and ALT response. RAMP1 rs3754701T was strongly associated with both DNA response and ALT response (OR=2.277, 95%CI: 1.386-3.741, P=0.001; OR=1.694, 95%CI: 1.073-2.675, P=0.024). However, CGRP rs155209C was less prone to DNA response and ALT response (OR=0.150, 95%CI: 0.083-0.271, P<0.001; OR=0.583, 95%CI: 0.367-0.925, P=0.022). Conclusions: Results from our study suggested that both RAMP1 rs3754701 and CGRP rs155209 were associated with the prognosis of patients under interferon therapy in Han population, from the northern parts of China while RAMP1 rs3754701T was a protective factor for both ALT response and DNA response, but CGRP rs155209C carriers were less prone to DNA and ALT responses.

Influence of electro-acupuncture on central and peripheral calcitonin gene-related peptide and receptor modifying protein 1 expression in functional dyspepsia rats with liver stagnation and spleen deficiency

AIM: To observe the influence of electric acupuncture (EA) on central and peripheral calcitoningene-related peptide (CGRP) and receptor activity modifying protein 1 (RAMP1) expression in functional dyspepsia (FD) rats with liver stagnation and spleen deficiency.

METHODS: Forty-eight rats were randomly divided into three groups (n = 16 each): a blank group, a model group, and an EA group. Except for the blank group, the other two groups underwent modeling by tail clamp stimulation (14 d, 2 times/d), giving an irregular diet (fasting every other day, with free access to water), and gavage of ice physiological saline (-7 ℃ 0.9% NaCl injection 2 mL, 2 times/d). As FD was successfully induced, EA treatment started (4 wk, once a day). After 28 d, the rats were killed to take tissue samples. The rates of gastric emptying and small intestinal transit were determined; the expression levels of CGRP and its receptor RAMP1 in the hypothalamus, stomach, and intestine were measured by Western blot.

RESULTS: Compared with the blank group, gastric emptying rate significantly increased (P < 0. 001), small intestinal transit rate significantly decreased (P < 0.001), the levels of CGRP and RAMP1 expression in the stomach and intestine significantly increased (P < 0.05), and their expression levels in the hypothalamus significantly increased (P < 0.01) in the model group. Compared with the model group, gastric emptying rate significantly decreased (P < 0.001), small intestinal transit rate significantly increased (P < 0.01), and the expression levels of both central and peripheral CGRP and RAMP1 significantly decreased (P < 0.05) in the EA group.

CONCLUSION: EA treatment can significantly decrease peripheral CGRP and its receptor RAMP1 expression, thereby promoting gastrointestinal motility and reducing the sensitivity of the gastrointestinal tract. Similarly, EA has a significant effect on the expression of CGRP and its receptor in the central nervous system, indicating that EA regulates the brain gut peptide through the brain-gut axis and thereby regulates gastrointestinal activity.