A chicken ovalbumin upstream promoter transcription factor I (COUP-TFI) complex represses expression of the gene encoding tumor necrosis factor alpha-induced protein 8 (TNFAIP8).

The orphan nuclear receptor chicken ovalbumin upstream promoter transcription factor I (COUP-TFI) plays key roles in development and homeostasis. A tandem affinity purification procedure revealed that COUP-TFI associated with a number of transcriptional regulatory proteins in HeLa S3 cells, including the nuclear receptor corepressor (NCoR), TIF1beta/KAP-1, HDAC1, and the SWI/SNF family member Brahma. The proapoptotic protein DBC1 was also identified in COUP-TFI complexes. In vitro experiments revealed that COUP-TFI interacted directly with NCoR but in a manner different from that of other nuclear receptors. DBC1 stabilized the interaction between COUP-TFI and NCoR by interacting directly with both proteins. The gene encoding the anti-apoptotic protein TNFAIP8 (tumor necrosis factor alpha (TNFalpha)-induced protein 8) was identified as being repressed by COUP-TFI in a manner that required several of the component proteins of the COUP-TFI complex. Finally, our studies highlight a central role for COUP-TFI in the induction of the TNFAIP8 promoter by TNFalpha. Together, these studies identify a novel COUP-TFI complex that functions as a repressor of transcription and may play a role in the TNFalpha signaling pathways.