TAK1 regulates NF-ΚB and AP-1 activation in airway epithelial cells following RSV infection

Respiratory syncytial virus (RSV) is the most common cause of epidemic respiratory diseases in infants and young children. RSV infection of airway epithelial cells induces the expression of immune/inflammatory genes through the activation of a subset of transcription factors, including Nuclear Factor-^κB (NF-^κB) and AP-1. In this study, we have investigated the signaling pathway leading to activation of these two transcription factors in response to RSV infection. Our results show that IKKβ plays a key role in viral-induced NF-^κB activation, while JNK regulates AP-1-dependent gene transcription, as demonstrated by using kinase inactive proteins and chemical inhibitors of the two kinases. Inhibition of TAK1 activation, by overexpression of kinase inactive TAK1 or using cells lacking TAK1 expression, significantly reduced RSV-induced NF-^κB and AP-1 nuclear translocation and DNA-binding activity, as well as NF-^κB-dependent gene expression, identifying TAK1 as an important upstream signaling molecule regulating RSV-induced NF-^κB and AP-1 activation.