Action of substance P and PAMP(9-20) on different excitation sites of MRGPRX2 induces differences in mast cell activation.

Abstract

MRGPRX2 on mast cells (MCs) is the target that directly mediates MC activation through the activity of small molecular substances. Previous work has attempted to prove that substance P (SP) and PAMP(9-20) induce an MRGPRX2-mediated MC degranulation reaction. However, SP activates MRGPRX2-induced histamine release, which may lead to allergic airway inflammation, while PAMP(9-20)-induced MrgprB2 activation releases more tryptase and fewer monoamines. Due to the lack of direct available comparisons, the different types of sensitizing mediators released by the action of SP and PAMP(9-20) inducing pseudo-allergic reactions via MRGPRX2 are unclear. To investigate whether the action sites of excited MRGPRX2 are different for SP and PAMP(9-20), leading to different effects, the release of inflammatory mediators was measured using MC degranulation reactions and RNA-seq assay in vitro. Mice were treated to observe local inflammation and MC degranulation in vivo. Moreover, site-directed mutagenesis was used to verify the excited sites of SP and PAMP(9-20). SP and PAMP(9-20) both activated MRGPRX2 and led MCs to release inflammatory mediators. Significantly different levels of histamine, tryptase, TNF-α, MCP-1, and other cytokines were released in vivo and in vitro. G165E, D184N, W243R, and H259Y were necessary for SP to activate MRGPRX2, while only D184N and W243R were important for PAMP(9-20). The downstream signaling pathways activated by SP and PAMP(9-20) also differed in the phosphorylation level of PKC. There were differences in the sites via which SP and PAMP(9-20) activate MRGPRX2 and also in the activated downstream signaling pathways, which led to the differences the activation of the pathways and effects of SP- and PAMP(9-20)-induced MRGPRX2 activation.

• Authors: Delu Che, Yi Zheng, Yajing Hou, Xueshan Du, Tao Jia, Qiang Zhao, Xiangjin Song, Tong Zhou, Songmei Geng
• Journal: International immunopharmacology (Int Immunopharmacol) Vol. 101 Issue Pt B Pg. 108342 (Dec 2021) ISSN: 1878-1705 [Electronic] Netherlands
• PMID: 34753104 (Publication Type: Journal Article)
• Copyright: Copyright © 2021 Elsevier B.V. All rights reserved.

Chemical References

• Chemokine CCL2
• Mrgprx2 protein, mouse
• Receptors, G-Protein-Coupled
• Tumor Necrosis Factor-alpha
• proadrenomedullin (9-20)
• Adrenomedullin
• Substance P

Topics

• Adrenomedullin (analogs & derivatives, metabolism)
• Animals
• Cell Degranulation
• Cell Line
• Chemokine CCL2 (metabolism)
• Humans
• Male
• Mast Cells (physiology)
• Mice
• Mice, Inbred C57BL
• Protein Binding
• Receptors, G-Protein-Coupled (genetics, metabolism)
• Signal Transduction
• Substance P (metabolism)
• Tumor Necrosis Factor-alpha (metabolism)