CLONING OF A HUMAN 7-TRANSMEMBRANE DOMAIN RECEPTOR, LESTR, THAT IS HIGHLY EXPRESSED IN LEUKOCYTES

Several chemotactic agonists including interleukin-8 (IL-8) and relate d cytokines have been shown to activate and attract leukocytes via sev en-transmembrane domain, GTP-binding protein-coupled receptors. A cDNA clone, LESTR, encoding a protein of 352 amino acids, corresponding to a novel receptor of this type, was isolated from a human blood monocy te cDNA library. The sequence of the deduced protein, LESTR (leukocyte -derived seven-transmembrane domain receptor), has 92.6% identity with that of a recently reported bovine neuropeptide Y (NPY) receptor, boL CR1 (Rimland, J., Xin, W., Sweetnam, P., Saijoh, K., Nestler, E. J., a nd Duman, R. S. (1991) Mol. Pharmacol. 40, 869-875). LESTR, however, i s more similar (>34%) to the IL-8 receptors, IL-SR, and IL-8R2, than t o several NPY receptors of different origin (<20%). In the monocyte li brary, LESTR cDNA fragments were about 20 times as frequent as cDNA co ding for IL-8R, and IL-8R2, and much higher levels of LESTR- than IL-8 R-specific mRNA were found in human blood neutrophils and lymphocytes. LESTR transcripts, by contrast, were low or undetectable in several n euroblastoma cell lines that are widely used to study NPY functions. T ransfected cells expressing high levels of LESTR mRNA did not bind rad iolabeled NPY, IL-8, NAP-2, GROalpha, PF4, IP10, MCP-1, MCP-3, MIP-1al pha, HC14,I309, RANTES, C3a, or LTB4. NPY also failed to bind to neutr ophils, monocytes, and lymphocytes, to elicit responses in vitro such as Ca2+ changes, shape change, chemotaxis, enzyme release, and the res piratory burst, and to induce leukocyte accumulation upon injection in rats and rabbits. Although the ligand for LESTR could not be identifi ed among a large number of chemotactic cytokines, the high expression in white blood cells and the marked sequence relation to IL-8R1 and IL -8R2 suggest that LESTR may function in the activation of inflammatory cells.