Identification of two rat genes orthologous to the human interleukin-8 receptors.

The genes encoding two functional human interleukin-8 (IL-8) receptors have been identified by molecular cloning techniques and they are members of the rhodopsin G-protein coupled receptor (GCR) superfamily. We report the molecular cloning of two rat GCR genes (rat CXCR1-like and rat CXCR2) whose conceptualized amino acid sequences are approximately 70% identical to the human IL-8 A and B receptor subtypes. The murine GRO-like peptide, macrophage inflammatory peptide-2 (MIP-2), elevates intracellular calcium levels in HEK293 cells expressing the rat CXCR2 receptor. Southern blot analysis of restriction-digested rodent and human genomic DNAs indicate that rat CXCR1-like and CXCR2 are: 1) each single copy genes in the rat genome; 2) most closely related to the human IL-8 receptor genes; and 3) orthologous to two previously identified murine genes. CXCR2 mRNA is detected in adult rat lung, spleen, and neutrophils. CXCR1-like mRNA can be detected in adult rat lung, native rat macrophages, and a rat alveolar macrophage cell line (NR8383). These data identify the rat orthologs of the human IL-8 receptors, and describe cellular and tissue targets of rat C-X-C chemokine peptides.