PUMA-G, an IFN-γ-inducible gene in macrophages is a novel member of the seven transmembrane spanning receptor superfamily

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Abstract
IFN‐γ is a key immunoregulatory cytokine that plays a predominant role in innate immunity. By employing PCR‐Select to search for genes differentially expressed in IFN‐γ/TNF‐α stimulated macrophages, we identified a novel IFN‐γ‐induced transcript designated PUMA‐G (protein up‐regulated in macrophages by IFN‐γ). PUMA‐G codes for a protein with seven transmembrane helices, a feature commonly shared with the G protein‐coupled receptor superfamily (GPCR). The PUMA‐G protein is most similar to the human orphan GPCR HM74 (73 % identity) and GPR31 (30 % identity). PUMA‐G mRNA was readily induced in macrophages after stimulation with IFN‐γ, LPS, polyIC and CpG oligonucleotides. In vivo PUMA‐G was up‐regulated in mice suffering from microbial sepsisor from Listeria monocytogenes infection. Characterization of the genomic locus revealed an intronless PUMA‐G open reading frame. Genomic Southern blot analysis indicates that PUMA‐G is a single‐copy gene. PUMA‐G maps to mouse chromosome 5F. Confocal microscopy of transiently transfected 264.7 RAW macrophages and 293T cells with a PUMA‐G‐EGFP fusion construct showed predominant fluorescence at the cell surface, suggesting a localization at the cell membrane. Taken together, our data indicate that PUMA‐G is a new inducible representative of GPCR, with potential importance in macrophage functions.