Negative cross-talk between the human orphan nuclear receptor Nur77/NAK-1/TR3 and nuclear factor-kappaB.
The effect of orphan nuclear receptor Nur77 overexpression on activation of an interleukin-2 (IL-2) promoter-luciferase construct was analyzed in the human leukemic cell line Jurkat. Cotransfection of the IL-2 promoter construct together with the Nur77 expression plasmid resulted in a significant repression of IL-2 promoter activation compared to control cells. The repression by Nur77 requires the N-terminal activation function-1 domain. The repressive effect of Nur77 on IL-2 promoter activation is mediated through inhibition of the transcription factor complex nuclear factor-kappaB (NF-kappaB), since blocking or alteration of the IL-2 NF-kappaB binding sites resulted in abrogation of the repressive effect of Nur77. Moreover, further examination of a reporter gene construct containing multiple copies of the IL-2 CD28 response element (CD28RE) showed that Nur77 can inhibit transactivation mediated by the NF-kappaB components p65 and c-Rel. However, no effect of Nur77 was seen on p65-mediated transactivation of a construct containing multiple NF-kappaB binding sites of the HIV LTR. Our data suggest that Nur77 is able to block activation through NF-kappaB when bound to low-affinity NF-kappaB binding sites, such as those located in the IL-2 promoter.
Novartis Institute for BioMedical Research, A-1235 Vienna, Austria. Hanna.Harant@novartis.com
Hanna
H
Harant
Ivan J D
IJ
Lindley
D000595:Amino Acid Sequence; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D015536:Down-Regulation; D005786:Gene Expression Regulation; D006801:Humans; D007376:Interleukin-2 / Q000235:genetics; D019169:Jurkat Cells; D016328:NF-kappa B / Q000378:metabolism*; D057105:Nuclear Receptor Subfamily 4, Group A, Member 1; D011401:Promoter Regions, Genetic; D017434:Protein Structure, Tertiary; D018160:Receptors, Cytoplasmic and Nuclear; D011987:Receptors, Steroid; D012097:Repressor Proteins / Q000737:chemistry / Q000378:metabolism*; D015398:Signal Transduction; D014157:Transcription Factors / Q000737:chemistry / Q000378:metabolism*; D015533:Transcriptional Activation
D004268:DNA-Binding Proteins; D007376:Interleukin-2; D016328:NF-kappa B; C539821:NR4A1 protein, human; D057105:Nuclear Receptor Subfamily 4, Group A, Member 1; D018160:Receptors, Cytoplasmic and Nuclear; D011987:Receptors, Steroid; D012097:Repressor Proteins; D014157:Transcription Factors