Orphan nuclear receptor NOR-1 enhances 3',5'-cyclic adenosine 5'-monophosphate-dependent uncoupling protein-1 gene transcription.
Prolonged cold exposure induces nonshivering thermogenesis primarily through beta-adrenergic- and cAMP-mediated regulation of uncoupling protein-1 (UCP1) in brown adipose tissue. Molecular mechanisms involved in this induction of Ucp1 gene transcription consists of an intricate interplay between many nuclear receptors in coordination with coactivators/corepressors. Recently, it has been shown that members of the nuclear receptor-4A (NR4A) family of orphan nuclear receptors (Nur77, Nurr1, and NOR-1) are highly responsive to cAMP-second messenger pathways. Here we have identified a new regulatory motif in the Ucp1 promoter that binds NR4As to stimulate Ucp1 gene transcription. Upon cold exposure of mice, or beta-agonist treatment of mouse and human adipocytes, the expression of NR4A nuclear receptors is rapidly induced, with NOR-1 being the most robust, and this precedes increases in Ucp1 expression. A dominant-negative mutant Nur-77 receptor that prevents the transcriptional activity of NR4A receptors blocked beta-adrenergic receptor-stimulated Ucp1 gene transcription. By gel shift and chromatin immunoprecipitation assays, we defined the sequence (-5.64 kb) in the Ucp1 promoter to which NOR-1 binds. In transient reporter assays, this element significantly augments the activity of a 3.7-kb Ucp1 promoter. These results extend our understanding of the combinatorial complexity in the signaling pathways that control this tissue-specific gene.
Kumar
Naresh
N
Division of Translational Biology, The Hamner Institutes for Health Sciences, Research Triangle Park, North Carolina 27709, USA.
Liu
Dianxin
D
Wang
Haibo
H
Robidoux
Jacques
J
Collins
Sheila
S
D041721:3T3-L1 Cells; D002001:Adipose Tissue, Brown / Q000378:metabolism; D052436:Adipose Tissue, White / Q000378:metabolism; D000818:Animals; D019556:COS Cells; D002460:Cell Line; D002522:Chlorocebus aethiops; D047369:Chromatin Immunoprecipitation; D000242:Cyclic AMP / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D006801:Humans; D015151:Immunoblotting; D007473:Ion Channels / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism*; D057105:Nuclear Receptor Subfamily 4, Group A, Member 1; D057126:Nuclear Receptor Subfamily 4, Group A, Member 2; D011485:Protein Binding; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics / Q000378:metabolism*; D011987:Receptors, Steroid / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic; D000071256:Uncoupling Protein 1
D004268:DNA-Binding Proteins; D007473:Ion Channels; D024101:Mitochondrial Proteins; C539821:NR4A1 protein, human; C539882:NR4A2 protein, human; C539818:Nr4a1 protein, mouse; C539883:Nr4a2 protein, mouse; D057105:Nuclear Receptor Subfamily 4, Group A, Member 1; D057126:Nuclear Receptor Subfamily 4, Group A, Member 2; D018160:Receptors, Cytoplasmic and Nuclear; D011987:Receptors, Steroid; D014157:Transcription Factors; C000604371:UCP1 protein, human; C000604372:Ucp1 protein, mouse; D000071256:Uncoupling Protein 1; D000242:Cyclic AMP