RNA helicase DDX5 enables STAT1 mRNA translation and interferon signalling in hepatitis B virus replicating hepatocytes

Abstract

ObjectiveRNA helicase DDX5 is downregulated during HBV replication and poor prognosis HBV-related hepatocellular carcinoma (HCC). The objective of this study is to investigate the role of DDX5 in interferon (IFN) signalling. We provide evidence of a novel mechanism involving DDX5 that enables translation of transcription factor STAT1 mediating the IFN response.Design and resultsMolecular, pharmacological and biophysical assays were used together with cellular models of HBV replication, HCC cell lines and liver tumours. We demonstrate that DDX5 regulates STAT1 mRNA translation by resolving a G-quadruplex (rG4) RNA structure, proximal to the 5′ end of STAT1 5′UTR. We employed luciferase reporter assays comparing wild type (WT) versus mutant rG4 sequence, rG4-stabilising compounds, CRISPR/Cas9 editing of the STAT1-rG4 sequence and circular dichroism determination of the rG4 structure. STAT1-rG4 edited cell lines were resistant to the effect of rG4-stabilising compounds in response to IFN-α, while HCC cell lines expressing low DDX5 exhibited reduced IFN response. Ribonucleoprotein and electrophoretic mobility assays demonstrated direct and selective binding of RNA helicase-active DDX5 to the WT STAT1-rG4 sequence. Immunohistochemistry of normal liver and liver tumours demonstrated that absence of DDX5 corresponded to absence of STAT1. Significantly, knockdown of DDX5 in HBV infected HepaRG cells reduced the anti-viral effect of IFN-α.ConclusionRNA helicase DDX5 resolves a G-quadruplex structure in 5′UTR of STAT1 mRNA, enabling STAT1 translation. We propose that DDX5 is a key regulator of the dynamic range of IFN response during innate immunity and adjuvant IFN-α therapy.

Comprehensive dissection of immune microenvironment in the progression of early gastric cancer at spatial and single-cell resolution

“…B-c0 and B-c5 mainly originated from non-EGC groups while in B-c1, B-c2, B-c3, B-c4 and B-c6, cells from EGC and AG groups predominated (Supplementary Figure 10C). Gene expression analysis showed the similar up-regulated genes between B-c0 and B-c5, DDX5 35 36 , DDX3X 37 and NCL 38 were all anti-pathogens and anti-tumor genes. As plenty of oncogenes significantly up-regulated in B-c1 cluster, we inferred it was deteriorating cell populations induced by tumor cells.…”

RNA helicase DDX5 mediates adaptive response to multi-kinase inhibitors in liver cancer

“…To determine whether the RNA helicase activity of DDX5 is required for ferroptosis, we employed doxycycline-inducible FLAG-DDX5-HepaRG cell lines (23), encoding WT-DDX5 or the inactive DDX5-K144N mutant lacking ATPase activity (42). Following doxycycline induction, overexpression of WT-DDX5 induced ferroptosis upon addition of sorafenib or RSL3, quantified by cell viability and C11-BODIPY 581/591 assays.…”

“…DDX5 is a transcriptional regulator with critical roles in cell growth and differentiation (20), exhibiting diverse functions. In transformed hepatocytes, DDX5 regulates PRC2 function via interaction with lncRNA HOTAIR (22), STAT1 translation by resolving a G- quadruplex located at the 5’UTR of STAT1 mRNA (23), and p62/SQSTM1 degradation markedly reducing its half-life (19).…”

DDX55 promotes hepatocellular carcinoma progression by interacting with BRD4 and participating in exosome‐mediated cell‐cell communication

“…Previous research suggested that members of the DEAD‐box protein family were involved in the response to ethanol stress and the regulation of antiviral innate immunity. 37 , 38 , 39 , 40 , 41 , 42 Thus, the roles and mechanisms of DDX55 in the development of HCC induced by the known and unknown risk factors are worthy of future studies. Consistent with the involvement of DDX55 in colorectal cancer liver metastasis and in the prognosis of lung cancer patients, we confirmed that DDX55 upregulation correlated with tumor progression and served as an independent prognostic indicator of unfavorable RFS and OS of HCC patients regardless of ethnicity, which represented the most prominent prognostic value among the DEAD‐box protein family.…”