TAK1 activation of the mouse JunB promoter is mediated through a CCAAT box and NF-Y.

The JunB gene is activated by many stimuli including transforming growth factor beta (TGFbeta) family members and interleukin-6 (IL-6). Here the effect of TGFbeta activated kinase 1 (TAK1), a mitogen activated protein kinase kinase kinase (MAPKKK) implicated in TGFbeta, bone morphogenetic protein (BMP) and interleukin-1 (IL-1) signaling, on JunB promoter activity was investigated. Promoter analysis led to the identification of a CCAAT motif in the JunB gene, essential for activation by TAK1. Transfer of this CCAAT element to a heterologous minimal promoter conferred TAK1-responsiveness. The CCAAT-binding transcription factor, nuclear factor Y (NF-Y), activated the JunB promoter and a dominant negative NF-YA construct inhibited TAK1 activation of JunB. Our results demonstrate that JunB gene activation by TAK1 is mediated by the CCAAT-binding factor NF-Y.