Porcine enterocyte protein Btnl5 negatively regulates NF-kappa B pathway by interfering p65 nuclear translocation.

Porcine butyrophilin-like 5 (Btnl5) is a novel member of the butyrophilin family, which consists of immune regulators. The expression pattern and the function of this gene remain unclear. In this study, Btnl5 is identified as a negative regulator of the NF-κB pathway. Our study indicates that Btnl5 is mainly expressed in intestinal epithelial cells (IECs) and expressed in membrane systems. Btnl5 inhibits MyD88-mediated activation of the NF-κB pathway. Btnl5 interacts with TNF receptor-associated factor 2 (TRAF2) and transcription factor p65. Besides, Btnl5 inhibits p65-mediated activation of the NF-κB pathway and inhibits nuclear translocation of p65. These results suggest that Btnl5 may inhibit NF-κB pathway through binding and interfere nuclear translocation of p65.