The DEAD-box RNA Helicase DDX3 Interacts With NF-?B Subunit P65 And Suppresses P65-mediated Transcription

RNA helicase family members exhibit diverse cellular functions, including transcription, pre-mRNA processing, RNA decay, ribosome biogenesis, and RNA export and translation. RNA helicase DEAD-box family member DDX3 has been characterized as a tumour suppressor and transcriptional co-activator/regulator. Here, we demonstrate that DDX3 interacts with nuclear factor (NF)-kB subunit p65 and suppresses NF-KB-dependent reporter gene transcription. The downregulation of DDX3 by RNA interference induces the upregulation of NF-kB transcription. Moreover, the binding of ATP-dependent RNA helicase domain of DDX3 and the N-terminal Rel homology domain (RHD) of p65 is involved in NF-kB-regulated gene transcriptional inhibition. In summary, the results suggest that DDX3 functions in the suppression of the transcriptional regulatory activity of the NF-kB subunit p65.