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.

中文翻译：

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DDX39B与模式识别受体途径相互作用，以抑制NF-κB并对烷基化化疗敏感。

背景技术核因子-κB（NF-κB）在促进炎症和对DNA损伤疗法的抵抗中起重要作用。我们寻找调节NF-κB反应的蛋白质，作为鉴定影响DNA破坏性化学疗法敏感性的新因素的先决条件。结果使用抗生蛋白链菌素-琼脂糖下拉，我们确定DExD / H-box RNA解旋酶DDX39B是与κBDNA探针差异相互作用的因素。随后，我们使用RNA干扰和CRISPR / Cas9技术，证明了DDX39B通过抑制p65磷酸化的一般机制抑制NF-κB活性。从机理上讲，DDX39B通过与模式识别受体（PRR）LGP2相互作用来介导这种作用，该途径需要细胞对胞质双链RNA（dsRNA）作出反应。从功能的角度来看，DDX39B的缺失促进了胶质母细胞瘤细胞对烷基化化疗的耐药性。对DDX39B的进一步检查表明，它的蛋白质丰度受到促进其多聚泛素化和降解的位点特异性sumoylation的调节。这些翻译后修饰需要SUMO E3连接酶PIASx-β的存在。最后，全基因组分析表明，尽管与PRR系统有联系，但DDX39B通常不会抑制干扰素刺激的基因表达，而是能减弱与细胞外基质，细胞迁移和血管生成相关的因子的表达。结论这些结果表明DDX39B是一种RNA结合蛋白，可阻断炎症反应的一部分，该因子在mRNA剪接和核输出中具有已知功能。