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The DEAD-Box RNA Helicase DDX3 Interacts with NF-κB Subunit p65 and Suppresses p65-Mediated Transcription

Nian Xiang1, Miao He1, Musarat Ishaq1

  • 1State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, P. R. China.

Plos One
|October 14, 2016
PubMed

Insights

The RNA helicase DDX3 protein interacts with nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) p65, suppressing its transcriptional activity. DDX3 downregulation increases NF-κB-mediated transcription, impacting cytokine expression.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Cancer Research

Background:

  • RNA helicases, including the DEAD-box family member DDX3, are involved in numerous cellular processes.
  • DDX3 is recognized as a tumor-associated factor and a regulator of transcription.
  • Nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) is a key transcription factor involved in immune responses and cancer.

Purpose of the Study:

  • To investigate the interaction between DDX3 and NF-κB.
  • To elucidate the role of DDX3 in regulating NF-κB transcriptional activity.
  • To understand the molecular mechanism by which DDX3 affects NF-κB signaling.

Main Methods:

  • Co-immunoprecipitation to assess DDX3-p65 interaction.
  • RNA interference to downregulate DDX3 expression.
  • Quantitative PCR and ELISA to measure NF-κB target gene and cytokine expression (IL-6, IL-8).
  • Analysis of protein domains involved in the interaction.

Main Results:

  • DDX3 directly interacts with the NF-κB subunit p65.
  • Downregulation of DDX3 leads to increased NF-κB (p65/p50)-mediated transcription.
  • Increased transcription correlates with elevated expression of downstream cytokines IL-6 and IL-8.
  • The RNA helicase domain of DDX3 binds to the Rel homology domain (RHD) of p65, inhibiting transcription.

Conclusions:

  • DDX3 acts as a suppressor of NF-κB (p65/p50)-mediated transcriptional activity.
  • The interaction between DDX3 and p65 is crucial for regulating NF-κB target gene expression.
  • DDX3's function in suppressing NF-κB signaling may have implications in cancer biology.

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