Anaphylatoxin GPCR Assays
Background of Anaphylatoxin Receptors
The anaphylatoxin receptors are a superfamily of G protein-coupled receptors binding to anaphylatoxins, including complement peptide C3a receptor (C3AR1) and complement peptide C5a1 receptor (C5AR1). The anaphylatoxins are pro-inflammatory polypeptides formed when C3 and C5 are proteolytically cleaved in response to complement activation. Pathogen-, cell-, or contact system-derived proteases can also produce anaphylatoxins locally within tissues. The ligation of anaphylatoxin receptors with anaphylatoxins act a role in many biologic activities, including chemotaxis and activation of granulocytes, mast cells, and macrophages. Besides, the anaphylatoxins also interact with the antigen-presenting cells and T cells, mediating cell apoptosis lipid metabolism, and innate and adaptive immune responses, which are of vital importance in many diseases, including allergies, infections, autoimmunity diseases, neurodegenerative diseases, and cancers.
Fig.1. Structure of the complement C5a1 receptor (C5AR1) bound to the extra-helical antagonist NDT9513727. (Cianciulli, 2020)
Distribution and Function of Anaphylatoxin Receptors
Anaphylatoxin receptors are expressed on myeloid cells such as neutrophils, basophils, eosinophils, mast cells, monocytes/macrophages, dendritic cells, and non-myeloid cells, including astrocytes, endothelial cells, T cells. They are distributed in the lungs, liver, kidney, heart, and brain. C3AR1 is also expressed in muscle and testis. C5AR1 is also found in skin, spleen, and intestine. Overexpressed anaphylatoxin receptors can result in cell recruitment and induce cellular degranulation, and thus cause inflammatory diseases, such as allergies, asthma, arthritis, sepsis, lupus, diabetes, and so on.
Subtypes and Mechanisms of Anaphylatoxin Receptors
Anaphylatoxin receptors are divided into two subtypes, the C3a receptor and the C5a1 receptor, belonging to the family of complement peptide receptors. They couple the G proteins, which promote subsequent signal transduction.
| Receptor | Gene | Mechanism | Agonists | Antagonists |
| C3a receptor | C3AR1 |
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| C5a1 receptor | C5AR1 |
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Assay List of Anaphylatoxin Receptors
Creative Biolabs can provide a range of assays of anaphylatoxin receptors. You can choose the assay in the list or contact us for more information:
| Assay No. | Assay Name | Host Cell | Assay Type | Datasheet |
|---|---|---|---|---|
| [35S]GTPγS Binding Assay | ||||
| S01YF-1122-KX214 | Magic™ Human C5AR1 In Vitro [35S]GTPγS binding Assay | CHO-K1 | [35S]GTPγS binding Assay | |
| Assay No. | Assay Name | Host Cell | Assay Type | Datasheet |
|---|---|---|---|---|
| Radioligand Binding Assay | ||||
| S01YF-1122-KX215 | Magic™ Human C5AR2 In Vitro Radioligand Binding Assay | CHO-K1 | Radioligand Binding Assay | |
Published Data
| Paper Title | Potent thiophene antagonists of human complement C3a receptor with anti-inflammatory activity |
| Journal | Journal of Medicinal Chemistry |
| Published | 2020 |
| Abstract | Structure-activity relationships of small-molecule thiophene analogs exhibit potent and selective antagonism of human complement C3a receptors. In this report, three assays were used to examine the antagonistic effects of the novel antagonist JR14a on C3aR in vitro, including (a) inhibition of intracellular calcium release (IC50 10 nM) induced in human monocyte-derived macrophages by 100 nM C3a, (b) inhibition of β-hexosaminidase secretion (IC50 8 nM) from human LAD2 mast cells degranulated by 100 nM C3a, and (c) selectivity for human C3aR over C5aR. The treatment effect has proved that the JR14a has the ability to suppress rat paw inflammation by in vivo assay. C3aR antagonists are ideal for investigating the activation and suppressing effects of C3aR-mediated inflammation in mammalian physiology and diseases. |
| Result |
The study investigated the thiophene analogue, such as JR14a, potently inhibited intracellular Ca2+ release related to C3a in human macrophages in vitro, while having no agonist-inhibiting effects in the same concentration range as C5a. Thiophene analogues may act as antagonists of C3a-induced degranulation measured by secreted β-hexosaminidase in LAD2 human mast cells. Thiophene analogues reduce rat paw inflammation induced by a C3aR agonist. Compound 14a (JR14a) was the most potent and effective C3aR antagonist in this study. Thiophene analogs as small molecule modulators for human complement protein C3a may provide new insights into the pharmacology of C3a and related GPCRs in mammalian physiology and disease mechanisms.
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Fig.2. Evaluation of new C3aR antagonists in vitro. (Rowley, 2020)
References
- Cianciulli A.; et al. Complement peptide receptors (version 2020.3) in the IUPHAR/BPS Guide to Pharmacology Database. IUPHAR/BPS Guide to Pharmacology CITE. 2020, 2020(3).
- Rowley, J. A.; et al. Potent thiophene antagonists of human complement C3a receptor with anti-inflammatory activity. Journal of Medicinal Chemistry. 2020, 63(2): 529-541.
