DDX39B interacts with the pattern recognition receptor pathway to inhibit NF-κB and sensitize to alkylating chemotherapy

Abstract

Background: Nuclear factor-κB (NF-κB) plays a prominent role in promoting inflammation and resistance to DNA damaging therapy. We searched for proteins that modulate the NF-κB response as a prerequisite to identifying novel factors that affect sensitivity to DNA damaging chemotherapy. Results: Using streptavidin-agarose pull-down, we identified the DExD/H-box RNA helicase, DDX39B, as a factor that differentially interacts with κB DNA probes. Subsequently, using both RNA interference and CRISPR/Cas9 technology, we demonstrated that DDX39B inhibits NF-κB activity by a general mechanism involving inhibition of p65 phosphorylation. Mechanistically, DDX39B mediates this effect by interacting with the pattern recognition receptor (PRR), LGP2, a pathway that required the cellular response to cytoplasmic double-stranded RNA (dsRNA). From a functional standpoint, loss of DDX39B promoted resistance to alkylating chemotherapy in glioblastoma cells. Further examination of DDX39B demonstrated that its protein abundance was regulated by site-specific sumoylation that promoted its poly-ubiquitination and degradation. These post-translational modifications required the presence of the SUMO E3 ligase, PIASx-β. Finally, genome-wide analysis demonstrated that despite the link to the PRR system, DDX39B did not generally inhibit interferon-stimulated gene expression, but rather acted to attenuate expression of factors associated with the extracellular matrix, cellular migration, and angiogenesis. Conclusions: These results identify DDX39B, a factor with known functions in mRNA splicing and nuclear export, as an RNA-binding protein that blocks a subset of the inflammatory response. While these findings identify a pathway by which DDX39B promotes sensitization to DNA damaging therapy, the data also reveal a mechanism by which this helicase may act to mitigate autoimmune disease.

Plasma‐Derived Exosomal hsa‐miR‐4488 and hsa‐miR‐1228‐5p: Novel Biomarkers for Dermatomyositis‐Associated Interstitial Lung Disease with Anti‐Melanoma Differentiation‐Associated Protein 5 Antibody‐Positive Subset

“…It was identified that DDX39B may possibly be a target gene of hsa-miR-4488 according to the multiMiR database. It has been reported that DDX39B interacts with the pattern recognition receptor pathway to inhibit NF- κ B signaling [ 32 ]. In the present study, hsa-miR-4488 was significantly upregulated in DM-ILD-MDA5 Ab(+) when compared to DM-nonILD-MSA16(-) and HC, suggesting that miR-4488 may contribute to systemic inflammation in DM-ILD-MDA5 Ab(+) by upregulating NF- κ B signaling through repression of DDX39B.…”

LncRNA SNHG20 promoted proliferation, invasion and inhibited cell apoptosis of lung adenocarcinoma via sponging miR‐342 and upregulating DDX49

“…Loss of DDX39B has been reported to promote resistance to alkylating chemotherapy in glioblastoma cells. 37 Similarly, DDX19 impaired type I interferon production, resulting in suppression of encephalomyocarditis virus replication. 38 In this study, we discovered that DDX49 was overexpressed in lung adenocarcinoma tissues and cell lines in comparison with paracancerous tissues and normal cells.…”

“…DExD RNA helicases play great roles in cancers. Loss of DDX39B has been reported to promote resistance to alkylating chemotherapy in glioblastoma cells 37 . Similarly, DDX19 impaired type I interferon production, resulting in suppression of encephalomyocarditis virus replication 38 .…”

Applications of CRISPR-Cas9 Technology to Genome Editing in Glioblastoma Multiforme

“…An investigation used CRISPR-Cas9 to knockdown DDX39B (DExD-box helicase 39B) gene in U87MG cell line and found that down regulation of the expression of angiogenesis-related factors [ 70 ]. Similarly, it has been shown that CRISPR-Cas9 mediated knockdown of Notch1 gene significantly impaired expression of angiogenesis and related factors in response to radiotherapy in U87MG and U251 cells [ 33 ].…”