title: Regulation of macrophage inflammatory gene expression by the orphan nuclear receptor Nur77.
abstract: Members of the nuclear hormone receptor superfamily have emerged as important regulators of macrophage gene expression in inflammation and disease. Previous studies have shown that the lipid-activated receptors peroxisomal proliferator-activated receptor and liver X receptor inhibit nuclear factor-kappaB (NF-kappaB) signaling and inflammatory gene expression. We recently identified the NR4A subfamily of orphan nuclear receptors (Nur77/NR4A1, Nurr1/NR4A2, and NOR1/NR4A3) as lipopolysaccharide- and NF-kappaB-responsive genes in macrophages. However, the role of these transcription factors in macrophage gene expression is unknown. We demonstrate here that, in contrast to peroxisomal proliferator-activated receptor and liver X receptor, the role of NR4A receptors in macrophages is proinflammatory. Retroviral expression of Nur77 in macrophages leads to the transcriptional activation of multiple genes involved in inflammation, apoptosis, and cell cycle control. One particularly interesting Nur77-responsive gene is the inducible kinase IKKi/IKKepsilon, an important component of the NF-kappaB signaling pathway. The IKKi promoter contains a functional NR4A binding site and is activated by all three NR4A receptors in transient transfection assays. Consistent with the activation of IKKi, expression of Nur77 in macrophages potentiates the induction of inflammatory gene expression in response to lipopolysaccharide. These results identify a new role for NR4A orphan nuclear receptors in the control of macrophage gene expression during inflammation.
authors.affiliation: Howard Hughes Medical Institute, Department of Pathology and Laboratory Medicine, University of California, Los Angeles, California 90095, USA.
authors.forename: Liming
authors.initials: L
authors.lastname: Pei
authors.forename: Antonio
authors.initials: A
authors.lastname: Castrillo
authors.forename: Peter
authors.initials: P
authors.lastname: Tontonoz
mesh_terms: D000818:Animals; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism*; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D051550:I-kappa B Kinase; D007249:Inflammation / Q000235:genetics* / Q000378:metabolism*; D008264:Macrophages / Q000378:metabolism*; D051379:Mice; D057105:Nuclear Receptor Subfamily 4, Group A, Member 1; D020411:Oligonucleotide Array Sequence Analysis; D011401:Promoter Regions, Genetic; D017346:Protein Serine-Threonine Kinases / Q000235:genetics; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics* / Q000378:metabolism*; D011987:Receptors, Steroid / Q000235:genetics* / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism*; D014162:Transfection
chemical_list: D004268:DNA-Binding Proteins; C539818:Nr4a1 protein, mouse; D057105:Nuclear Receptor Subfamily 4, Group A, Member 1; D018160:Receptors, Cytoplasmic and Nuclear; D011987:Receptors, Steroid; D011994:Recombinant Proteins; D014157:Transcription Factors; D017346:Protein Serine-Threonine Kinases; D051550:I-kappa B Kinase