MOLECULAR-CLONING AND FUNCTIONAL EXPRESSION OF A NEW HUMAN CC-CHEMOKINE RECEPTOR GENE

The cloning of several receptors activated by either CC or CXC chemoki nes and belonging to the G protein-coupled family of receptors has bee n reported recently. In the present work, we describe the cloning of a human gene, named ChemR13, encoding a new CC-chemokine receptor. The gene encodes a protein of 352 amino acids with a calculated molecular mass of 40 600 Da and displaying a single potential site for N-linked glycosylation. Using a set of overlapping lambda clones, the genomic o rganisation of the locus was investigated, demonstrating that the Chem R13 gene is physically linked, and in the same orientation, as the CC- CKR2. gene that encodes a receptor for the monocyte chemoattractant pr otein-1 (MCP-1). A distance of 17.5 kb separates the two coding region s, which share 75% identity in nucleic acid and amino acid sequences. Human ChemR13 was functionally expressed in a stably transfected CHO-K 1 cell line. Physiological responses to chemokines wen monitored using a microphysiometer. Macrophage inflammatory protein-1 alpha (MIP-1 al pha) was the most potent agonist. MIP-1 beta and RANTES were also acti ve at physiological concentrations. The other CC-chemokines, MCP-1, MC P-2 and MCP-3, as well as CXC-chemokines (IL-8, GRO alpha) had no effe ct. ChemR13 receptor transcripts were detected by Northern blotting in the promyeloblastic tell line KG-1A, suggesting a potential role in t he control of granulocytic lineage proliferation or differentiation. C hemR13 is thus a new member of the growing family of chemokine recepto rs that mediate the recruitment of cells involved in immune and inflam matory processes. Being the fifth functionally identified receptor in his class, this new CC-chemokine receptor (CC-CKR) is tentatively desi gnated CC-CKR5.