Regulation of Chemerin Chemoattractant and Antibacterial Activity by Human Cysteine Cathepsins

Abstract

Chemerin, a ligand for the G-protein coupled receptor CMKLR1 (chemokine-like receptor 1), requires C-terminal proteolytic processing to unleash its chemoattractant activity. Proteolytically-processed chemerin selectively attracts specific subsets of immunoregulatory antigen presenting cells, including CMKLR1+ immature plasmacytoid dendritic cells (pDC). Chemerin is predicted to belong to the structural cathelicidin/cystatin family of proteins comprised of antibacterial polypeptide cathelicidins and inhibitors of cysteine proteinases (cystatins). We therefore hypothesized that chemerin may interact directly with cysteine proteases and that it might also function as an antibacterial agent. Here we show that chemerin does not inhibit human cysteine proteases, but rather is a new substrate for cathepsin K and L. Cathepsin K and L-cleaved chemerin triggered robust migration of human blood-derived pDC ex vivo. Furthermore, cathepsin K and L-truncated chemerin also displayed antibacterial activity against Enterobacteriaceae. Cathepsins may therefore contribute to host defense by activating chemerin to directly inhibit bacterial growth and to recruit pDC to sites of infection.

Development by Genetic Immunization of Monovalent Antibodies (Nanobodies) Behaving as Antagonists of the Human ChemR23 Receptor

“…However, prochemerin is expressed constitutively by different tissues in noninflammatory conditions, and its bioactivity depends primarily on the complex proteolytic processing of its C terminus. Numerous proteases belonging to different classes and involved in various pathways were described to regulate chemerin bioactivity (14,(35)(36)(37)(38)(39), rendering the regulation of this system particularly complex. In addition, ChemR23 expression was described in many cell populations other than leukocytes, including preadipocytes and adipocytes (5,6), skeletal muscle cells (9), and endothelial cells (10), and additional roles for the chemerin/ChemR23 system were proposed in the control of lipid and glucose metabolism (9,17,40), blood pressure (41), and angiogenesis (10).…”

Crosstalk between skin inflammation and adipose tissue-derived products: pathogenic evidence linking psoriasis to increased adiposity

“…The real function of chemerin in the skin is not fully clear, but it has been reported to act as antimicrobial protein [104,106]. Apparently, chemerin mainly works as chemoattractant for CMKLR1+ plasmacytoid dendritic cells (pDCs), macrophages and NK cells, promoting their recruitment at site of tissue damage, and amplifying immune response [107]. Indeed, bacteria and acute phase cytokines, as well as oncostatin M and IL-1β, up-regulate its production, while IL-17 and IL-22 decrease it [110].…”

“…It is released as inactive precursor and converted in its active form by proteinases [107,108], in order to work as ligand for G protein-associated receptor chemokine-like receptor 1 (CMKLR1) [109].…”

Effects of novel human cathepsin S inhibitors on cell migration in human cancer cells

“…The active site cysteine is part of a conserved ''catalytic triad'' formed by cysteine pairing with a histidine, which in turn is paired with an asparagine 18,28 . To determine whether the seven candidate compounds of low IC 50 specifically inhibit Cat S activity 5 , the enzyme activity of recombinant Cat S, Cat L and Cat K were determined after treatment with compounds 6a, 6b, 6e, 6n, 6p, 6r, 6w or E-64 for 10 min (Figure 1).…”

“…Recombinant human Cat S (re-Cat S) was prepared following the procedures mentioned above 5 . Substrates Z-Phe-Arg-AMC for Cat L, and Cat K and Z-Val-Val-Arg-AMC (Z: Benzyloxycarbonyl; AMC: 7-amino-4-methyl coumarin) for Cat S were obtained from BACHEM (Torrance, CA) 18 . Cat S activity was determined by Cathepsin S Activity Assay Kit from BioVison, Inc. (Mountain View, CA) (Catalog number: K144-100), which utilizes the preferred Cat-S substrate, Z-VVR labeled with AFC (AFC: amino-4-trifluoromethyl coumarin, C-terminal).…”