Helicase Research Articles

Separation of telomere protection from length regulation by two different point mutations at amino acid 492 of RTEL1.

RTEL1 is an essential DNA helicase that plays multiple roles in genome stability and telomere length regulation. A variant of RTEL1 with a lysine at position 492 is associated with short telomeres in Mus spretus , while a conserved methionine at this position is found in M. musculus , which has ultra-long telomeres. In humans, a missense mutation at this position ( Rtel1 M492I ) causes a fatal telomere biology disease termed Hoyeraal-Hreidarsson syndrome (HHS). Introducing the Rtel1 M492K mutation into M. musculus shortened the telomeres of the resulting strain, termed 'Telomouse', to the length of human telomeres. Here, we report on a mouse strain carrying the Rtel1 M492I mutation, termed 'HHS mouse'. The HHS mouse telomeres are not as short as those of Telomice but nevertheless they display higher levels of telomeric DNA damage, fragility and recombination, associated with anaphase bridges and micronuclei. These observations indicate that the two mutations separate critical functions of RTEL1: M492K mainly reduces the telomere length setpoint, while M492I predominantly disrupts telomere protection. The two mouse models enable dissecting the mechanistic roles of RTEL1 and the different contributions of short telomeres and DNA damage to telomere biology diseases, genomic instability, cancer, and aging.

Unlocking fertility in the female gametophyte: a DEAD-box RNA helicase is essential for embryo sac development and seed setting.

This article comments on: Huang J, Qiao Z, Yu H, Lu Z, Chen W, Lu J, Wu J, Bao Y, Shahid MQ, Liu X. 2024. OsRH52A, a DEAD-box protein, regulates functional megaspore specification and is required for embryo sac development in rice. Journal of Experimental Botany 75, 4802–4821. https://doi.org/10.1093/jxb/erae180

DEAD-box RNA helicase RH20 positively regulates RNAi-based antiviral immunity in plants by associating with SGS3/RDR6 bodies.

RNA silencing plays a crucial role in defending against viral infections in diverse eukaryotic hosts. Despite extensive studies on core components of the antiviral RNAi pathway such as DCLs, AGOs and RDRs proteins, host factors involved in antiviral RNAi remain incompletely understood. In this study, we employed the proximity labelling approach to identify the host factors required for antiviral RNAi in Nicotiana benthamiana. Using the barley stripe mosaic virus (BSMV)-encoded γb, a viral suppressor of RNA silencing (VSR), as the bait protein, we identified the DEAD-box RNA helicase RH20, a broadly conserved protein in plants and animals with a homologous human protein known as DDX5. We demonstrated the interaction between RH20 and BSMV γb. Knockdown or knockout of RH20 attenuates the accumulation of viral small interfering RNAs, leading to increased susceptibility to BSMV, while overexpression of RH20 enhances resistance to BSMV, a process requiring the cytoplasmic localization and RNA-binding activity of RH20. In addition to BSMV, RH20 also negatively regulates the infection of several other positive-sense RNA viruses, suggesting the broad-spectrum antiviral activity of RH20. Mechanistic analysis revealed the colocalization and interaction of RH20 with SGS3/RDR6, and disruption of either SGS3 or RDR6 undermines the antiviral function of RH20, suggesting RH20 as a new component of the SGS3/RDR6 bodies. As a counter-defence, BSMV γb VSR subverts the RH20-mediated antiviral defence by interfering with the RH20-SGS3 interaction. Our results uncover RH20 as a new positive regulator of antiviral RNAi and provide new potential targets for controlling plant viral diseases.

RNA helicase D1PAS1 resolves R-loops and forms a complex for mouse pachytene piRNA biogenesis required for male fertility.

During meiosis, RNA polymerase II transcribes pachytene piRNA precursors with unusually long and unspliced transcripts from discrete autosomal loci in the mouse genome. Despite the importance of piRNA for male fertility and a well-defined maturation process, the transcriptional machinery remains poorly understood. Here, we document that D1PAS1, an ATP-dependent RNA helicase, is critical for pachytene piRNA expression from multiple genomic loci and subsequent translocation into the cytoplasm to ensure mature piRNA biogenesis. Depletion of D1PAS1 in gene-edited mice results in the accumulation of R-loops in pachytene spermatocytes, leading to DNA-damage-induced apoptosis, disruption of piRNA biogenesis, spermatogenic arrest, and male infertility. Transcriptome, genome-wide R-loop profiling, and proteomic analyses document that D1PAS1 regulates pachytene piRNA transcript elongation and termination. D1PAS1 subsequently forms a complex with nuclear export components to ensure pachytene piRNA precursor translocation from the nucleus to the cytoplasm for processing into small non-coding RNAs. Thus, our study defines D1PAS1 as a specific transcription activator that promotes R-loop unwinding and is a critical factor in pachytene piRNA biogenesis.

Visual Evidence for the Recruitment of Four Enzymes with RNase Activity to the Bacillus subtilis Replication Forks.

Removal of RNA/DNA hybrids for the maturation of Okazaki fragments on the lagging strand, or due to misincorporation of ribonucleotides by DNA polymerases, is essential for all types of cells. In prokaryotic cells such as Escherichia coli, DNA polymerase 1 and RNase HI are supposed to remove RNA from Okazaki fragments, but many bacteria lack HI-type RNases, such as Bacillus subtilis. Previous work has demonstrated in vitro that four proteins are able to remove RNA from RNA/DNA hybrids, but their actual contribution to DNA replication is unclear. We have studied the dynamics of DNA polymerase A (similar to Pol 1), 5'->3' exonuclease ExoR, and the two endoribonucleases RNase HII and HIII in B. subtilis using single-molecule tracking. We found that all four enzymes show a localization pattern similar to that of replicative DNA helicase. By scoring the distance of tracks to replication forks, we found that all four enzymes are enriched at DNA replication centers. After inducing UV damage, RNase HIII was even more strongly recruited to the replication forks, and PolA showed a more static behavior, indicative of longer binding events, whereas RNase HII and ExoR showed no response. Inhibition of replication by 6(p hydroxyphenylazo)-uracil (HPUra) demonstrated that both RNase HII and RNase HIII are directly involved in the replication. We found that the absence of ExoR increases the likelihood of RNase HIII at the forks, indicating that substrate availability rather than direct protein interactions may be a major driver for the recruitment of RNases to the lagging strands. Thus, B. subtilis replication forks appear to be an intermediate between E. coli type and eukaryotic replication forks and employ a multitude of RNases, rather than any dedicated enzyme for RNA/DNA hybrid removal.

Screening and Characterization of a New Iflavirus Virus in the Fruit Tree Pest Pyrops candelaria.

Pyrops candelaria is one of the common pests of fruit trees, but the research on the pathogenic microorganisms it may carry is very limited. Therefore, it is essential to reveal the pathogenic microbes it carries and their potential hazards. This study found a new virus from the transcriptome of P. candelaria, which was first reported in P. candelaria and named PyCaV (Pyrops candelaria associated virus). RACE and bioinformatics assay revealed that the full length of PyCaV is 10,855 bp with the polyA tail, containing a single open-reading frame (ORF) encoding a polyprotein consisting of 3171 amino acid (aa). The virus has a typical iflavirus structure, including two rhv domains, an RNA helicase domain (HEL), a 3C cysteine protease domain (Pro), and an RNA-dependent RNA polymerase domain (RdRp). Further phylogenetic analysis revealed that this virus belongs to family Iflaviridae and sequence alignments analysis suggested PyCaV is a new member in an unassigned genus of family Iflaviridae. Further in-depth analysis of the virus infection showed that PyCaV is distributed throughout the whole P. candelaria, including its head, chest, and abdomen, but more PyCaV was identified in the chest. The distribution of PyCaV in different parts of P. candelaria was further explored, which showed that more PyCaV was detected in its piercing-sucking mouthparts and chest viscera. Statistical analysis showed that the PyCaV infection was affected by time and location.

PRRSV hijacks DDX3X protein and induces ferroptosis to facilitate viral replication

Porcine reproductive and respiratory syndrome virus (PRRSV) is a severe disease with substantial economic consequences for the swine industry. The DEAD-box helicase 3 (DDX3X) is an RNA helicase that plays a crucial role in regulating RNA metabolism, immunological response, and even RNA virus infection. However, it is unclear whether it contributes to PRRSV infection. Recent studies have found that the expression of DDX3X considerably increases in Marc-145 cells when infected with live PRRSV strains Ch-1R and SD16; however, it was observed that inactivated viruses did not lead to any changes. By using the RK-33 inhibitor or DDX3X-specific siRNAs to reduce DDX3X expression, there was a significant decrease in the production of PRRSV progenies. In contrast, the overexpression of DDX3X in host cells substantially increased the proliferation of PRRSV. A combination of transcriptomics and metabolomics investigations revealed that in PRRSV-infected cells, DDX3X gene silencing severely affected biological processes such as ferroptosis, the FoxO signalling pathway, and glutathione metabolism. The subsequent transmission electron microscopy (TEM) imaging displayed the typical ferroptosis features in PRRSV-infected cells, such as mitochondrial shrinkage, reduction or disappearance of mitochondrial cristae, and cytoplasmic membrane rupture. Conversely, the mitochondrial morphology was unchanged in DDX3X-inhibited cells. Furthermore, silencing of the DDX3X gene changed the expression of ferroptosis-related genes and inhibited the virus proliferation, while the drug-induced ferroptosis inversely promoted PRRSV replication. In summary, these results present an updated perspective of how PRRSV infection uses DDX3X for self-replication, potentially leading to ferroptosis via various mechanisms that promote PRRSV replication.

The Study of Metalloproteome of DNA Viruses: Identification, Functional Annotation, and Diversity Analysis of Viral Metal-Binding Proteins.

Metalloproteins are fundamental to diverse biological processes but still lack extensive investigation in viral contexts. This study reveals the prevalence and functional diversity of metal-binding proteins in DNA viruses. Among a subset of 1432 metalloproteins, zinc and magnesium-binding proteins are notably abundant, indicating their importance in viral biology. Furthermore, significant numbers of proteins binding to iron, manganese, copper, nickel, mercury, and cadmium were also detected. Human-infecting viral proteins displayed a rich landscape of metalloproteins, with MeBiPred (964 proteins) and Pfam (666) yielding the highest numbers. Interestingly, many essential viral proteins exhibited metal-binding capabilities, including polymerases, DNA binding proteins, helicases, dUPTase, thymidine kinase, and various structural and accessory proteins. This study sheds light on the ubiquitous presence of metalloproteins, their functional signatures, subcellular placements, and metal-utilization patterns, providing valuable insights into viral biology. A similar metal utilization pattern was observed in similar functional proteins across the various DNA viruses. Furthermore, these findings provide a foundation for identifying potential drug targets for combating viral infections.

Nonequilibrium phases of a biomolecular condensate facilitated by enzyme activity.

Biomolecular condensates represent a frontier in cellular organization, existing as dynamic materials driven out of equilibrium by active cellular processes. Here we explore active mechanisms of condensate regulation by examining the interplay between DEAD-box helicase activity and RNA base-pairing interactions within ribonucleoprotein condensates. We demonstrate how the ATP-dependent activity of DEAD-box helicases-a key class of enzymes in condensate regulation-acts as a nonequilibrium driver of condensate properties through the continuous remodeling of RNA interactions. By combining the LAF-1 DEAD-box helicase with a designer RNA hairpin concatemer, we unveil a complex landscape of dynamic behaviors, including time-dependent alterations in RNA partitioning, evolving condensate morphologies, and shifting condensate dynamics. Importantly, we reveal an antagonistic relationship between RNA secondary structure and helicase activity which promotes condensate homogeneity via a nonequilibrium steady state. By elucidating these nonequilibrium mechanisms, we gain a deeper understanding of cellular organization and expand the potential for active synthetic condensate systems.

DNA damage-induced phosphorylation of a replicative DNA helicase results in inhibition of DNA replication through attenuation of helicase function.

A major function of the DNA damage responses (DDRs) that act during the replicative phase of the cell cycle is to inhibit initiation and elongation of DNA replication. It has been shown that DNA replication of the polyomavirus, SV40, is inhibited and its replication fork is slowed by cellular DDR responses. The inhibition of SV40 DNA replication is associated with enhanced DDR kinase phosphorylation of SV40 Large T-antigen (LT), the viral DNA helicase. Mass spectroscopy was used to identify a novel highly conserved DDR kinase site, T518, on LT. In cell-based assays expression of a phosphomimetic form of LT at T518 (T518D) resulted in dramatically decreased levels of SV40 DNA replication, but LT-dependent transcriptional activation was unaffected. Purified WT and LT T518D wereanalyzed in vitro. In concordance with the cell-based data, reactions using SV40 LT-T518D, but not T518A, showed dramatic inhibition of SV40 DNA replication. A myriad of LT protein-protein interactions and LT's biochemical functions were unaffected by the LT T518D mutation; however, LT's DNA helicase activity was dramatically decreased on long, but not very short, DNA templates. These results suggest that DDR phosphorylation at T518 inhibits SV40 DNA replication by suppressing LT helicase activity.

Uncovering chikungunya virus-encoded miRNAs and host-specific targeted genes associated with antiviral immune responses: an integrated bioinformatics approach

Chikungunya virus (CHIKV) is a single-stranded RNA virus belonging to the genus Alphavirus and is responsible for causing Chikungunya fever, a type of arboviral fever. Despite extensive research, the pathogenic mechanism of CHIKV within host cells remains unclear. In this study, an in-silico approach was used to predict that CHIKV produces micro-RNAs that target host-specific genes associated with host cellular regulatory pathways. Putative micro-RNAs of CHIKV were predicted using the miRNAFold and Vmir RNA structure web servers, and secondary structure prediction was performed using RNAfold. Host-specific target genes were then predicted, and hub genes were identified using CytoHubba and module selection through MCODE. Functional annotations of hub genes revealed their association with various pathways, including osteoclast differentiation, neuroactive ligand-receptor interaction, and mRNA surveillance. We used the freely available dataset GSE49985 to determine the level of expression of host-specific target genes and found that two genes, F-box and leucine-rich repeat protein 16 (FBXL16) and retinoic acid receptor alpha (RARA), were down-regulated, while four genes, RNA binding protein with serine-rich domain 1 (RNPS1), RNA helicase and ATPase (UPF1), neuropeptide S receptor 1 (NPSR1), and vasoactive intestinal peptide receptor 1 (VIPR1), were up-regulated. These findings provide insight into novel miRNAs and hub genes associated with CHIKV infection and suggest potential targets for therapeutic intervention. Further experimental validation of these targets could lead to the development of effective treatments for CHIKV-mediated diseases.

Identification of Rocaglate Acyl Sulfamides as Selective Inhibitors of Glioblastoma Stem Cells.

Glioblastoma (GBM) is the most aggressive and frequently occurring type of malignant brain tumor in adults. The initiation, progression, and recurrence of malignant tumors are known to be driven by a small subpopulation of cells known as tumor-initiating cells or cancer stem cells (CSCs). GBM CSCs play a pivotal role in orchestrating drug resistance and tumor relapse. As a prospective avenue for GBM intervention, the targeted suppression of GBM CSCs holds considerable promise. In this study, we found that rocaglates, compounds which are known to inhibit translation via targeting of the DEAD-box helicase eIF4A, exert a robust, dose-dependent cytotoxic impact on GBM CSCs with minimal killing of nonstem GBM cells. Subsequent optimization identified novel rocaglate derivatives (rocaglate acyl sulfamides or Roc ASFs) that selectively inhibit GBM CSCs with nanomolar EC50 values. Furthermore, comparative evaluation of a lead CSC-optimized Roc ASF across diverse mechanistic and target profiling assays revealed suppressed translation inhibition relative to that of other CSC-selective rocaglates, with enhanced targeting of the DEAD-box helicase DDX3X, a recently identified secondary target of rocaglates. Overall, these findings suggest a promising therapeutic strategy for targeting GBM CSCs.

SCI1, a flower regulator of cell proliferation, and its partners NtCDKG2 and NtRH35 interact with the splicing machinery.

Successful plant reproduction depends on the adequate development of flower organs controlled by cell proliferation and other processes. The SCI1 gene regulates cell proliferation and affects the final size of the female reproductive organ. To unravel the molecular mechanism exerted by SCI1 in cell proliferation control, we searched for its interaction partners through semi-in vivo pulldown experiments, uncovering a cyclin-dependent kinase, NtCDKG;2. Bimolecular fluorescence complementation (BiFC) and co-localization experiments showed that SCI1 interacts with NtCDKG;2 and its cognate NtCyclin L in nucleoli and splicing speckles. The screening of a yeast two-hybrid (Y2H) cDNA library using SCI1 as bait revealed a novel DEAD-box RNA helicase (NtRH35). The interaction between the NtCDKG;2-NtCyclin L complex, and NtRH35 was also shown. Subcellular localization experiments showed that SCI1, NtRH35, and the NtCDKG;2-NtCyclin L complex associate with each other within splicing speckles. The Y2H screening of NtCDKG;2 and NtRH35 identified the conserved spliceosome components U2a', NKAP, and CACTIN. This work presents SCI1 and its interactors NtCDKG;2-NtCyclin L complex, and NtRH35 as new spliceosome-associated proteins. Our findings reveal a network of interactions and suggest that SCI1 may regulate cell proliferation through the splicing process. This study provides new valuable insights into the intricate molecular pathways governing plant development.

Helicase HELQ: Molecular Characters Fit for DSB Repair Function.

The protein sequence and spatial structure of DNA helicase HELQ are highly conserved, spanning from archaea to humans. Aside from its helicase activity, which is based on DNA binding and translocation, it has also been recently reconfirmed that human HELQ possesses DNA-strand-annealing activity, similar to that of the archaeal HELQ homolog StoHjm. These biochemical functions play an important role in regulating various double-strand break (DSB) repair pathways, as well as multiple steps in different DSB repair processes. HELQ primarily facilitates repair in end-resection-dependent DSB repair pathways, such as homologous recombination (HR), single-strand annealing (SSA), microhomology-mediated end joining (MMEJ), as well as the sub-pathways' synthesis-dependent strand annealing (SDSA) and break-induced replication (BIR) within HR. The biochemical functions of HELQ are significant in end resection and its downstream pathways, such as strand invasion, DNA synthesis, and gene conversion. Different biochemical activities are required to support DSB repair at various stages. This review focuses on the functional studies of the biochemical roles of HELQ during different stages of diverse DSB repair pathways.

RNA helicase SKIV2L limits antiviral defense and autoinflammation elicited by the OAS-RNase L pathway

The OAS-RNase L pathway is one of the oldest innate RNA sensing pathways that leads to interferon (IFN) signaling and cell death. OAS recognizes viral RNA and then activates RNase L, which subsequently cleaves both cellular and viral RNA, creating “processed RNA” as an endogenous ligand that further triggers RIG-I-like receptor signaling. However, the IFN response and antiviral activity of the OAS-RNase L pathway are weak compared to other RNA-sensing pathways. Here, we discover that the SKIV2L RNA exosome limits the antiviral capacity of the OAS-RNase L pathway. SKIV2L-deficient cells exhibit remarkably increased interferon responses to RNase L-processed RNA, resulting in heightened antiviral activity. The helicase activity of SKIV2L is indispensable for this function, acting downstream of RNase L. SKIV2L depletion increases the antiviral capacity of OAS-RNase L against RNA virus infection. Furthermore, SKIV2L loss exacerbates autoinflammation caused by human OAS1 gain-of-function mutations. Taken together, our results identify SKIV2L as a critical barrier to OAS-RNase L-mediated antiviral immunity that could be therapeutically targeted to enhance the activity of a basic antiviral pathway.

ATG10-dependent autophagy is required for DDX10 to regulate cell proliferation, apoptosis and stemness in colorectal cancer

Colorectal cancer (CRC) remains a highly prevalent gastrointestinal neoplasm, presenting significant prevalence and lethality rate. DEAD/H box RNA helicase 10 (DDX10) has been proposed as a potential oncogene in CRC, the specific action mechanism by which DDX10 modulates the aggressive biological cellular events in CRC remains implicitly elucidated, however. During this study, DDX10 expression was detected via RT-qPCR and Western blotting. Cell proliferation was estimated via EDU staining. TUNEL staining and Western blotting appraised cell apoptosis. Cell stemness was evaluated by sphere formation assay, RT-qPCR, Western blotting as well as immunofluorescence staining. Relevant assay kit examined aldehyde dehydrogenase (ALDH) activity. Western blotting and immunofluorescence staining also detected autophagy. DDX10 was hyper-expressed in CRC cells. Down-regulation of DDX10 hampered cell proliferation, aggravated the apoptosis while eliminated the ability to form spheroid cells in CRC. In addition, DDX10 deletion improved ATG10 expression and therefore activated autophagy in CRC cells. Consequently, ATG10 depletion or treatment with autophagy inhibitor 3-Methyladenine (3-MA) partially compensated the influences of DDX10 silencing on the proliferation, apoptosis and stemness of CRC cells. Accordingly, DDX10 deficiency may aggravate autophagy mediated by ATG10 to impede cell proliferation, stemness and facilitate cell apoptosis, hence blocking the progression of CRC.

UPF1 deficiency enhances mitochondrial ROS which promotes an immunosuppressive microenvironment in pancreatic ductal adenocarcinoma

Upstream frameshift 1 (UPF1) is an RNA helicase involved in a number of mRNA regulatory processes including nonsense-mediated decay. Mutations in the UPF1 locus that reduce its expression have been associated with adenosquamous carcinoma of the pancreas, a particularly aggressive form of the disease. To determine the effect of Upf1 suppression in a murine model of pancreatic adenocarcinoma, we silenced with shRNA Upf1 in cells derived from an autochthonous tumor in an LSL-Kras G12D/+ ; Trp53 R172H/+ ; Pdx-1 Cre/+ mouse (KPC) and orthotopically implanted these cells in the pancreas of C57BL/6 mice. Tumors derived from Upf1-deficient cells were markedly larger than those derived from control cells, a difference observed only in immunocompetent mice. The immune infiltrate of Upf1-deficient tumors was enriched in myeloid-derived suppressor cells (MDSCs) and depleted of CD8 + cells compared to control KPC tumors. Upf1-deficient KPC cells secreted inflammatory cytokines including G-CSF and CXCL2, known to recruit MDSCs. Cytokine secretion from Upf1-deficient KPC cells was induced by increased levels of mitochondrial reactive oxygen species (ROS), which in turn were due to an increase in complex I activity in the electron transport chain. Thus, Upf1 helicase deficiency leads to increased mitochondrial complex I activity which produces ROS that signals for cytokine release that drives immune suppression and enhanced tumor growth.

DDX21 functions as a potential novel oncopromoter in pancreatic ductal adenocarcinoma: a comprehensive analysis of the DExD box family

BackgroundPancreatic ductal adenocarcinoma (PDAC) is a highly lethal tumor with an ill-defined pathogenesis. DExD box (DDX) family genes are widely distributed and involved in various RNA metabolism and cellular biogenesis; their dysregulation is associated with aberrant cellular processes and malignancies. However, the prognostic significance and expression patterns of the DDX family in PDAC are not fully understood. The present study aimed to explore the clinical value of DDX genes in PDAC.MethodsDifferentially expressed DDX genes were identified. DDX genes related to prognostic signatures were further investigated using LASSO Cox regression analysis. DDX21 protein expression was analyzed using the UALCAN and human protein atlas (HPA) online tools and confirmed in 40 paired PDAC and normal tissues through Tissue Microarrays (TMA). The independent prognostic significance of DDX21 in PDAC was determined through the construction of nomogram models and calibration curves. The functional roles of DDX21 were investigated using gene ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and Gene Set Enrichment Analysis (GSEA). Cell proliferation, invasion, and migration were assessed using Cell Counting Kit-8, colony formation, Transwell, and wound healing assays.ResultsUpregulation of genes related to prognostic signatures (DDX10, DDX21, DDX60, and DDX60L) was significantly associated with poor prognosis of patients with PDAC based on survival and recurrence time. Considering the expression profile and prognostic values of the signature-related genes, DDX21 was finally selected for further exploration. DDX21 was overexpressed significantly at both the mRNA and protein levels in PDAC compared to normal pancreatic tissues. DDX21 expression, pathological stage, and residual tumor were significant independent prognostic indicators in PDAC. Moreover, functional enrichment analysis revealed that Genes co-expressed with DDX21 are predominantly involved in RNA metabolism, helicase activity, ribosome biogenesis, cell cycle, and various cancer-related pathways, such as PI3K/Akt signaling pathway and TGF-β signaling pathway. Furthermore, in vitro experiments confirmed that the knockdown of DDX21 significantly reduced MIA PaCa-2 cell viability, proliferation, migration, and invasion.ConclusionsFour signature-related genes could relatively precisely predict the prognosis of patients with PDAC. Specifically, DDX21 upregulation may signal an unfavorable prognosis by negatively affecting the biological properties of PDAC cells. DDX21 may be considered as a candidate therapeutic target in PDAC.

DDX19A promotes gastric cancer cell proliferation and migration by activating the PI3K/AKT pathway

BackgroundDEAD-box RNA helicase 19 A (DDX19A) is overexpressed in cervical squamous cell carcinoma. However, its role in gastric cancer remains unclear. The present study aimed to explore the role and underlying mechanism of DDX19A in the development of gastric cancer.MethodsThe expression of DDX19A in gastric cancer and paracancerous tissues was evaluated through quantitative polymerase chain reaction, western blotting, and immunohistochemical staining. The biological functions of DDX19A in gastric cancer were determined using CCK8, plate colony-forming, and Transwell migration assays. The specific mechanism of DDX19A in gastric cancer cells was studied using western blotting, RNA-binding protein immunoprecipitation, mRNA half-life detection, and nuclear and cytoplasmic RNA isolation.ResultsDDX19A was highly expressed in gastric cancer and positively associated with malignant clinicopathological features and poor prognosis. Additionally, DDX19A promoted gastric cancer cell proliferation, migration, and epithelial–mesenchymal transition phenotypes. Mechanistically, DDX19A activated the PI3K/AKT pathway by upregulating phosphatidylinositol-3-kinase (PIK3CA) expression. Furthermore, DDX19A interacted with PIK3CA mRNA, stabilized it, and facilitated its export from the nucleus.ConclusionsOur study reveals a novel mechanism whereby DDX19A promotes the proliferation and migration of gastric cancer cells by enhancing the stability and nuclear export of PIK3CA mRNA, thereby activating the PI3K/AKT pathway.

ERCC2 mutations alter the genomic distribution pattern of somatic mutations and are independently prognostic in bladder cancer

Excision repair cross-complementation group 2 (ERCC2) encodes the DNA helicase xeroderma pigmentosum group D, which functions in transcription and nucleotide excision repair. Point mutations in ERCC2 are putative drivers in around 10% of bladder cancers (BLCAs) and a potential positive biomarker for cisplatin therapy response. Nevertheless, the prognostic significance directly attributed to ERCC2 mutations and its pathogenic role in genome instability remain poorly understood. We first demonstrated that mutant ERCC2 is an independent predictor of prognosis in BLCA. We then examined its impact on the somatic mutational landscape using a cohort of ERCC2 wild-type (n= 343) and mutant (n= 39) BLCA whole genomes. The genome-wide distribution of somatic mutations is significantly altered in ERCC2 mutants, including T[C>T]N enrichment, altered replication time correlations, and CTCF-cohesin binding site mutation hotspots. We leverage these alterations to develop a machine learning model for predicting pathogenic ERCC2 mutations, which may be useful to inform treatment of patients with BLCA.