Prolonged cold exposure induces non-shivering thermogenesis primarily through -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 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 -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 AR-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.