SECRETONEURIN AND CHEMOATTRACTANT RECEPTOR INTERACTIONS

Secretoneurin (SN) is a 33-amino acid peptide derived from secretogran in II (chromogranin C) which induces chemotaxis of monocytes but not n eutrophils. In this study, we found that SN interacted with specific c ell surface binding sites on human monocytes. The chemoattractants MCP -1, MCP-2 or fMLP could not compete for SN binding sites suggesting SN may bind to a novel chemotactic receptor. Additional studies showed t hat neither SN nor MCP-2 induced a rise in cytosolic Ca2+, and chemota xis to SN was inhibited by cholera toxin (CT) and pertussis toxin (PT) . Chemotactic desensitization studies demonstrated that fMLP, MCP-1, S N, and MCP-2 could all desensitize monocytes to subsequent SN stimulat ion. Our results indicate that SN binds to a cell surface receptor exp ressed on monocytes and activates signaling pathways which are sensiti ve to CT and PT. (C) 1998 Elsevier Science B.V. All rights reserved.