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Long intergenic non-coding RNA- Nucleotide Metabolism Regulator (lincNMR ) is a long non-coding RNA (lncRNA) which is induced in hepatocellular carcinoma. Its depletion invokes a proliferation defect, triggers senescence and inhibits colony formation in liver, but also breast and lung cancer cells. Triple-label SILAC proteomics profiles reveal a deregulation of key cell cycle regulators in lincNMR -depleted cells like the key dNTP synthesizing enzymes RRM2, TYMS and TK1, implicating lincNMR in regulating nucleotide metabolism. LincNMR silencing decreases dNTP levels, while exogenous dNTPs rescues the proliferation defect induced by lincNMR depletion. In vivo RNA Antisense Purification (RAP-MS) identifies YBX1 as a direct interaction partner of lincNMR which regulates RRM2, TYMS and TK1 expression and binds to their promoter regions. In a Chick Chorioallantoic Membrane (CAM) in vivo model, lincNMR -depleted tumors are significantly smaller. In summary, we discover a lincRNA, lincNMR , which regulates tumor cell proliferation through a YBX1-RRM2-TYMS-TK1 axis governing nucleotide metabolism. Despite some well-characterized functions in cancer, the impact of most long non-coding RNAs remains unknown. Here, the authors discover the lncRNA lincNMR which is upregulated in cancer and drives cell proliferation by interacting with YBX1 and controlling nucleotide metabolism.

Characterizing the interactions that SARS-CoV-2 viral RNAs make with host cell proteins during infection can improve our understanding of viral RNA functions and the host innate immune response. Using RNA antisense purification and mass spectrometry, we identified up to 104 human proteins that directly and specifically bind to SARS-CoV-2 RNAs in infected human cells. We integrated the SARS-CoV-2 RNA interactome with changes in proteome abundance induced by viral infection and linked interactome proteins to cellular pathways relevant to SARS-CoV-2 infections. We demonstrated by genetic perturbation that cellular nucleic acid-binding protein (CNBP) and La-related protein 1 (LARP1), two of the most strongly enriched viral RNA binders, restrict SARS-CoV-2 replication in infected cells and provide a global map of their direct RNA contact sites. Pharmacological inhibition of three other RNA interactome members, PPIA, ATP1A1, and the ARP2/3 complex, reduced viral replication in two human cell lines. The identification of host dependency factors and defence strategies as presented in this work will improve the design of targeted therapeutics against SARS-CoV-2. Interactions between SARS-CoV-2 viral RNAs and host cell proteins during infection are evaluated to improve our understanding of viral RNA functions and the host innate immune response.

The human genome contains thousands of long non-coding RNAs 1 , but specific biological functions and biochemical mechanisms have been discovered for only about a dozen 2 – 7 . A specific long non-coding RNA—non-coding RNA activated by DNA damage ( NORAD )—has recently been shown to be required for maintaining genomic stability 8 , but its molecular mechanism is unknown. Here we combine RNA antisense purification and quantitative mass spectrometry to identify proteins that directly interact with NORAD in living cells. We show that NORAD interacts with proteins involved in DNA replication and repair in steady-state cells and localizes to the nucleus upon stimulation with replication stress or DNA damage. In particular, NORAD interacts with RBMX, a component of the DNA-damage response, and contains the strongest RBMX-binding site in the transcriptome. We demonstrate that NORAD controls the ability of RBMX to assemble a ribonucleoprotein complex—which we term NORAD -activated ribonucleoprotein complex 1 (NARC1)—that contains the known suppressors of genomic instability topoisomerase I (TOP1), ALYREF and the PRPF19–CDC5L complex. Cells depleted for NORAD or RBMX display an increased frequency of chromosome segregation defects, reduced replication-fork velocity and altered cell-cycle progression—which represent phenotypes that are mechanistically linked to TOP1 and PRPF19–CDC5L function. Expression of NORAD in trans can rescue defects caused by NORAD depletion, but rescue is significantly impaired when the RBMX-binding site in NORAD is deleted. Our results demonstrate that the interaction between NORAD and RBMX is important for NORAD function, and that NORAD is required for the assembly of the previously unknown topoisomerase complex NARC1, which contributes to maintaining genomic stability. In addition, we uncover a previously unknown function for long non-coding RNAs in modulating the ability of an RNA-binding protein to assemble a higher-order ribonucleoprotein complex. The long non-coding RNA NORAD interacts with proteins involved in DNA replication and repair, and controls the ability of RBMX to form a ribonucleoprotein complex that helps to maintain genomic stability.

The antiviral immune response to SARS-CoV-2 infection can limit viral spread and prevent development of pneumonic COVID-19. However, the protective immunological response associated with successful viral containment in the upper airways remains unclear. Here, we combine a multi-omics approach with longitudinal sampling to reveal temporally resolved protective immune signatures in non-pneumonic and ambulatory SARS-CoV-2 infected patients and associate specific immune trajectories with upper airway viral containment. We see a distinct systemic rather than local immune state associated with viral containment, characterized by interferon stimulated gene (ISG) upregulation across circulating immune cell subsets in non-pneumonic SARS-CoV2 infection. We report reduced cytotoxic potential of Natural Killer (NK) and T cells, and an immune-modulatory monocyte phenotype associated with protective immunity in COVID-19. Together, we show protective immune trajectories in SARS-CoV2 infection, which have important implications for patient prognosis and the development of immunomodulatory therapies. Infection with SARS-COV-2 can result in self-limited upper airway infection or progress to a more systemic inflammatory condition including pneumonic COVID-19. Here the authors utilise a multi-omics approach to interrogate the immune response of patients with self-limiting upper respiratory SARS-CoV-2 infection and reveal a temporal immune trajectory they associate with viral containment and restriction from pneumonic progressive disease.

Increased production of fetal hemoglobin (HbF) can ameliorate the severity of sickle cell disease and β-thalassemia 1 . BCL11A represses the genes encoding HbF and regulates human hemoglobin switching through variation in its expression during development 2 – 7 . However, the mechanisms underlying the developmental expression of BCL11A remain mysterious. Here we show that BCL11A is regulated at the level of messenger RNA (mRNA) translation during human hematopoietic development. Despite decreased BCL11A protein synthesis earlier in development, BCL11A mRNA continues to be associated with ribosomes. Through unbiased genomic and proteomic analyses, we demonstrate that the RNA-binding protein LIN28B, which is developmentally expressed in a pattern reciprocal to that of BCL11A, directly interacts with ribosomes and BCL11A mRNA. Furthermore, we show that BCL11A mRNA translation is suppressed by LIN28B through direct interactions, independently of its role in regulating let-7 microRNAs, and that BCL11A is the major target of LIN28B-mediated HbF induction. Our results reveal a previously unappreciated mechanism underlying human hemoglobin switching that illuminates new therapeutic opportunities. Experiments in developing human erythroid cells show that LIN28B controls hemoglobin switching by directly suppressing BCL11A translation, independently of its role in regulating let-7 microRNA biogenesis.

Many positive strand RNA viruses encode helicases, but their distinct functions in viral replication cycles is poorly understood. Here, we identify a mutation in the helicase domain of HCV non-structural protein 3 (NS3h), D1467G, which specifically affects (−) strand synthesis, phenocopying mutations in the 3’ untranslated region of the genome. D1467G does not impair helicase activity in vitro or the binding of NS3h to critical cis-acting RNA elements, but reduces the interaction of NS3h and NS5B polymerase, potentially contributing to defective (−) strand synthesis. AlphaFold predictions of complexes between NS3h, RNA and/or NS5B suggest that NS3h both remodels the cis-acting RNA elements and unwinds the terminal stem-loop of the HCV genome rendering the template accessible for de novo initiation of (−) strand synthesis by NS5B. Overall, our study provides evidence for a defined function of a viral helicase in (−) strand genome synthesis of a positive strand RNA virus. Specific functions of viral helicases in genome replication of RNA viruses are widely unknown. This study suggests that hepatitis C virus NS3 helicase unwinds stem loop structures at the 3’end of the genome, thereby facilitating (−) strand synthesis.

Efficient reverse genetics systems are essential for understanding SARS-CoV-2 pathogenesis, host-virus interactions, and potential therapeutic interventions. Here, we developed a cost-effective PCR-based reverse genetics platform that splits the SARS-CoV-2 genome into only six bacterial plasmids, enabling cloning, manipulation, and the rescue of recombinant SARS-CoV-2 (rSARS-CoV-2) with high fidelity and high viral titers after a single passage. Using this system, we generated and characterized spike protein mutants Y453F and N501Y, as well as a U76G mutation in the 5'-UTR. Y453F showed reduced replication kinetics, lower cell binding, and diminished fitness, while N501Y exhibited comparable replication and fitness, highlighting the distinct effects of these spike protein mutations. The U76G mutation is located within a novel NSP9 binding site in the 5'-UTR and leads to impaired RNA synthesis and reduced viral replication efficiency, suggesting an important role in transcription and replication. Our findings highlight the robustness and adaptability of this reverse genetics system, providing a versatile, cost-effective tool for studying SARS-CoV-2 mutations and their effects on replication and fitness, with potential applications in vaccine and therapeutic development.

Maintaining a healthy proteome involves all layers of gene expression regulation. By quantifying temporal changes of the transcriptome, translatome, proteome, and RNA-protein interactome in cervical cancer cells, we systematically characterize the molecular landscape in response to proteostatic challenges. We identify shared and specific responses to misfolded proteins and to oxidative stress, two conditions that are tightly linked. We reveal new aspects of the unfolded protein response, including many genes that escape global translation shutdown. A subset of these genes supports rerouting of energy production in the mitochondria. We also find that many genes change at multiple levels, in either the same or opposing directions, and at different time points. We highlight a variety of putative regulatory pathways, including the stress-dependent alternative splicing of aminoacyl-tRNA synthetases, and protein-RNA binding within the 3’ untranslated region of molecular chaperones. These results illustrate the potential of this information-rich resource.

Viral infections have a large impact on society, leading to major human and economic losses and even global instability. So far, many viral infections, including human cytomegalovirus (HCMV) infection, are treated with a small repertoire of drugs, often accompanied by the occurrence of resistant mutants. Interferon-stimulated gene products (ISGs) play a crucial role in early infection control. The ISG zinc finger CCCH-type antiviral protein 1 (ZAP/ZC3HAV1) antagonizes several RNA viruses by binding to CG-rich RNA sequences, whereas its effect on DNA viruses is less well understood. Here, we decipher the role of ZAP in the context of human cytomegalovirus (HCMV) infection, a β-herpesvirus that is associated with high morbidity in immunosuppressed individuals and newborns. We show that expression of the two major isoforms of ZAP, ZAP-S and ZAP-L, is induced during HCMV infection and that both negatively affect HCMV replication. Transcriptome and proteome analyses demonstrated that the expression of ZAP results in reduced viral mRNA and protein levels and decelerates the progression of HCMV infection. Metabolic RNA labeling combined with high-throughput sequencing (SLAM-seq) revealed that most of the gene expression changes late in infection result from the general attenuation of HCMV. Furthermore, at early stages of infection, ZAP restricts HCMV by destabilizing a distinct subset of viral mRNAs, particularly those from the previously uncharacterized UL4-UL6 HCMV gene locus. Through enhanced cross-linking immunoprecipitation and sequencing analysis (eCLIP-seq), we identified the transcripts expressed from this HCMV locus as the direct targets of ZAP. Moreover, our data show that ZAP preferentially recognizes not only CG, but also other cytosine-rich sequences, thereby expanding its target specificity. In summary, this report is the first to reveal direct targets of ZAP during HCMV infection, which strongly indicates that transcripts from the UL4-UL6 locus may play an important role for HCMV replication. IMPORTANCE Viral infections have a large impact on society, leading to major human and economic losses and even global instability. So far, many viral infections, including human cytomegalovirus (HCMV) infection, are treated with a small repertoire of drugs, often accompanied by the occurrence of resistant mutants. There is no licensed HCMV vaccine in sight to protect those most at risk, particularly immunocompromised individuals or pregnant women who might otherwise transmit the virus to the fetus. Thus, the identification of novel intervention strategies is urgently required. In this study, we show that ZAP decelerates the viral gene expression cascade, presumably by selectively handpicking a distinct set of viral transcripts for degradation. Our study illustrates the potent role of ZAP as an HCMV restriction factor and sheds light on a possible role for UL4 and/or UL5 early during infection, paving a new avenue for the exploration of potential targets for novel therapies.

A typo in the ‘Reviewer information’ section of this Letter was corrected online.