Chemerin‐Derived Peptide C‐20 Suppressed Gonadal Steroidogenesis

Abstract

Problem Chemerin is a novel chemo-attractant and adipokine involved in leukocyte recruitment, inflammation, adipogenesis, lipid/carbohydrate metabolism, and reproduction. Based on the bioinformatic search for putative small peptides in the conserved region of pre-pro-chemerin, an evolutionary conserved region flanked by potential convertase cleavage sites was identified and we named it as C-20. The binding capacity of C-20 to chemerin receptors and its potential bioactivities were investigated in this study. Method of study Radioligand binding assay, receptor internalization assay, and early response gene C-FOS simulation, cAMP assay were carried out in chemokine-like receptor 1 (CMKLR1)/HEK293 transfectants and G protein-coupled receptor 1 (GPR1)/HEK293 transfectants. In vitro transwell chemotaxis assay in CMKLR1/L1.2 transfectants, primary Leydig cell culture, and antral follicle culture was explored to investigate the bioactivity of C-20. Results C-20 bound to chemerin receptors CMKLR1 and GPR1 with high affinity triggered CMKLR1 internalization and stimulated subsequent signal C-FOS expression and cAMP production. C-20, such as chemerin, showed CMKLR1-dependent chemotactic property. Furthermore, in primary Leydig cells and antral follicles, C-20 showed similar but less potent suppressive effect on human chorionic gonadotropin-stimulated testosterone production and progesterone production, compared with chemerin. Conclusion The novel chemerin-derived C-20 peptide binds to chemerin receptors CMKLR1 and GPR1 and showed similar but less potent bioactivity in chemotaxis and the suppression of gonadal steroidogenesis, suggesting that after optimization, C-20 is possible to be a useful experimental tool for the understanding of the biological functions of chemerin/CMKLR1 and chemerin/GPR1 signaling.

International Union of Basic and Clinical Pharmacology CIII: Chemerin Receptors CMKLR1 (Chemerin1) and GPR1 (Chemerin2) Nomenclature, Pharmacology, and Function

“…This confirms that precise cleavage at the C terminus to the serine residue at position 157 is critical for activity. In agreement, the work of Li et al (2014a) reports C20, chemerin138–157 (competition binding IC 50 = 1.6 nM, functional response from 1 nM), as a potent agonist at CMKLR1. C20 corresponds to an evolutionary conserved region of the mature protein flanked by potential cleavage sites.…”

“…Human chemerin21 – 157 is reported to be the most active form; removal of one amino acid (chemerin21 – 156) resulted in a sixfold drop in potency, whereas the addition of one or removal of two or three amino acids strongly affected potency, with no response seen up to 10 μ M ( Wittamer et al, 2004 ). The C terminus is therefore very important for function at CMKLR1, exemplified further by synthetic C-terminal fragments of human chemerin: C9 (or chemerin-9), chemerin149 – 157; C13, chemerin145 – 157 ( Wittamer et al, 2004 ); and C20, chemerin138 – 157 ( Li et al, 2014a ), possessing biologic activity ( Fig. 1C ).…”

The role of GPR1 signaling in mice corpus luteum

“…Other groups added 0.5μg/mL rat IgG (Abcam) as control. Plates were incubated at 37°C, 5% CO 2 ( Li et al . 2014 a ), and follicles and media were collected after 6 h. Media were analyzed for hormone levels by the Beijing North Institute of Biological Technology, and follicles were added to RNAiso Plus and stored at −80°C for qPCR detection of related genes.…”

CMKLR1 deficiency maintains ovarian steroid production in mice treated chronically with dihydrotestosterone

“…Chemokine-like receptor-1 (CMKLR1), an orphan G-protein-coupled receptor (GPCR), is specifically expressed by monocyte-derived dendritic cells, macrophages, and circulating plasmacytoid dendritic cells (pDCs) 1 2 . Several groups have reported that CMKLR1 mRNA is also expressed in adipose tissue, liver, and the testes and ovaries of humans, rats, and mice 1 3 4 5 . The natural ligand for CMKLR1, chemerin, was recently discovered 1 3 6 .…”