Marek's Disease Virus Disables the ATR-Chk1 Pathway by Activating STAT3

Novel lncRNA 803 related to Marek's disease inhibits apoptosis of DF-1 cells

Marek's disease (MD) is a neoplastic disease that significantly affects the poultry industry. Long non-coding RNAs (lncRNAs) are crucial regulatory factors in various biological processes, including tumourigenesis. However, the involvement of novel lncRNAs in the course of MD virus (MDV) infection is still underexplored. Here, we present the first comprehensive characterization of differentially expressed lncRNAs in chicken spleen at different stages of MDV infection. A series of differentially expressed lncRNAs was identified at each stage of MDV infection through screening. Notably, our investigation revealed a novel lncRNA, lncRNA 803, which exhibited significant differential expression at different stages of MDV infection and was likely to be associated with the p53 pathway. Further analyses demonstrated that the overexpression of lncRNA 803 positively regulated the expression of p53 and TP53BP1 in DF-1 cells, leading to the inhibition of apoptosis. This is the first study to focus on the lncRNA expression profiles in chicken spleens during MDV pathogenesis. Our findings highlight the potential role of the p53-related novel lncRNA 803 in MD pathogenesis and provide valuable insights for decoding the molecular mechanism of MD pathogenesis involving non-coding RNA.RESEARCH HIGHLIGHTS Differentially expressed lncRNAs in spleens of chickens infected with Marek's disease virus at different stages were identified for the first time.The effects of novel lncRNA 803 on p53 pathway and apoptosis of DF-1 cells were reported for the first time.

Non-canonical role for the ataxia-telangiectasia-Rad3 pathway in STAT3 activation in human multiple myeloma cells

PURPOSE

The goal of this study was to characterize the relationship between ATR and STAT3 interactions in human multiple myeloma (MM) cells.

METHODS

Various MM cell lines, including IL-6-dependent cells were exposed to ATR inhibitors and effects on STAT3 Tyr705 and Ser727 were monitored by WB analysis and ImageStream analysis. Parallel studies examined induction of cell death, STAT3 DNA binding activity, and expression of STAT3 downstream targets (BCL-XL, MCL-1, c-MYC). Validation was obtained in ATR shRNA knock-down cells, and in cells ectopically expressing BCL-XL, MCL-1, or c-MYC. Analogous studies were performed in primary MM cells and in a MM xenograft model.

RESULTS

Multiple pharmacologic ATR inhibitors inhibited STAT3 Tyr705 (but not Ser727) phosphorylation at low uM concentrations and down-regulated BCL-XL, MCL-1, c-MYC in association with cell death induction. Compatible results were observed in ATR shRNA knock-down cells. Cell death induced by ATR inhibitors was significantly attenuated in cells ectopically expressing constitutively active STAT3, BCL-XL, MCL-1, or c-MYC. Concordant results were observed in primary human MM cells and in an in vivo MM xenograft model.

CONCLUSIONS

Collectively, these findings argue for a non-canonical role for the ATR kinase in STAT3 activation in MM cells, and suggest that STAT3 inactivation contributes to the lethal actions of ATR inhibitors in MM.

HDAC6 Triggers the ATM-Dependent DNA Damage Response To Promote PRV Replication

Pseudorabies virus (PRV) infection is modulated by various cellular host factors. In this study, we investigated the role of histone deacetylase 6 (HDAC6) in this process. We determined HDAC6 expression in vitro and performed gene knockout, pharmacological inhibition analyses, immunofluorescence assays, and statistical analyses. We found that the pharmacological and genetic inhibition of HDAC6 significantly decreased PRV replication, whereas its overexpression promoted PRV replication. Additionally, we demonstrated that PRV infection can induce the phosphorylation of histone H2AX and lead to DNA damage response (DDR), and the ataxia telangiectasia mutated (ATM) inhibitor KU55933 inhibits DDR and PRV infection. Mechanistically, the HDAC6 inhibitor tubacin and HDAC6 knockout can decrease DDR. The results of this study suggested that HDAC6 may be a crucial factor in PRV-induced ATM-dependent DDR to promote PRV replication. IMPORTANCE Pseudorabies virus (PRV) is a member of the subfamily Alphaherpesvirinae of the family Herpesviridae. PRV infection in swine can lead to high morbidity and mortality of swine, causing huge economic losses. In particular, PRV variants can cause severe damage to the nervous and respiratory systems of humans, revealing that PRV may be a potential zoonotic pathogen. Vaccines for PRV have been developed that can delay or reduce the epidemic, but they currently cannot eliminate this disease completely. Therefore, studies should investigate new targets for the prevention and control of PRV infection. In this study, we demonstrated that HDAC6 can induce ataxia telangiectasia mutated-dependent DNA damage response to foster PRV replication, indicating that HDAC6 is a therapeutic target for PRV infection.

Receptor interacting protein 1 knockdown induces cell death in liver cancer by suppressing STAT3/ATR activation in a p53-dependent manner

The survival and death of eukaryotic cells are tightly controlled by a variety of proteins in response to the cellular environment. Receptor-interacting serine/threonine-protein kinase 1 (RIPK1) is a receptor-interacting Ser/Thr kinase that has recently been reported as an important regulator of cell survival, apoptosis, and necroptosis; however, its role in liver cancer remains unclear. In this study, we examined the effect of siRNA-mediated RIPK1 knockdown on the survival and death of liver cancer cells. Treatment with siRIPK1 decreased the growth rate of liver cancer cells and increased apoptotic, but not necrotic cell death, which was higher in wild-type p53 (wt-p53) cells than in mutant-type p53 (mt-p53) cells. In addition, RIPK1 knockdown increased p53 expression and G1 phase arrest in wt-p53 cells. Although suppressing p53 did not alter RIPK1 expression, it did attenuate siRIPK1-induced cell death. Interestingly, RIPK1 knockdown also increased the generation of reactive oxygen species and DNA damage by inhibiting signal transduced and activator of transcription 3 (STAT3) and ATM and RAD3-related (ATR) in wt-p53 cells but not in mt-p53 cells. Moreover, STAT3 or ATR inhibition in p53 mutant cells restored siRIPK1-mediated cell death. Together, the results of this study suggest that RIPK1 suppression induces apoptotic cell death by inhibiting the STAT3/ATR axis in a p53-dependent manner. Furthermore, these findings suggest that RIPK1, alone or in combination, may be a promising target for treating liver cancer.

Inhibitory effect of tanshinone IIA, resveratrol and silibinin on enterovirus 68 production through inhibiting ATM and DNA-PK pathway

BACKGROUND

Human enterovirus 68 (EV68) is a primary etiological agent for respiratory illnesses, while no effective drug has yet used in clinics largely because the pathogenesis of EV68 is not clear. DNA damage response (DDR) responds to cellular DNA breaks and is also involved in viral replication. Three DDR pathways includes ataxia telangiectasia mutated (ATM), ATM and Rad3-related (ATR), and DNA-dependent protein kinase (DNA-PK). Natural products proved to be an excellent source for the discovery and isolation of novel antivirals. Among them, tanshinone IIA, resveratrol, silibinin, rutin and quercetin are reported to target DDR, therefore their roles in anti-EV68 are investigated in this study.

PURPOSE

This study investigated the anti-EV68 ability of various natural compounds related to DDR.

STUDY DESIGN AND METHODS

The methods include cell counting, flow cytometry, western blot, Immunofluorescence staining, comet assays, quantitative real-time RT PCR and short interfering RNAs (siRNAs) for analysis of cell number, cell cycle, protein expression, protein location, DNA damage, mRNA level and knock down target gene, respectively.

RESULTS

EV68 infection induced DDR. Down-regulation or inhibition of ATM or DNA-PK lowered DDR in EV68-infected cells and mitigated viral protein expression, however, down-regulation or inhibition of ATR unexpectedly up-regulated DDR, and promoted viral protein expression. Meanwhile tanshinone IIA, resveratrol, and silibinin inhibited ATM and/or DNA-PK activation and decreased viral proliferation, while rutin and quercetin inhibited ATR activation and promoted viral production. The role of them in ATM, DNA-PK and ATR activation was consistent with previous reports.

CONCLUSION

Tanshinone IIA, resveratrol and silibinin inhibited EV68 proliferation through inhibiting ATM and/or DNA-PK activation, and they were effective anti-EV68 candidates.

Exploration of the Mechanism of the Control of Coccidiosis in Chickens Based on Network Pharmacology and Molecular Docking With the Addition of Modified Gegen Qinlian Decoction

Gegen Qinlian Decoction is a long-established Chinese herbal compound for the treatment of diarrhea and dysentery, while Magnolia officinalis has been demonstrated to have some anthelmintic activity. The preliminary screening of this study showed that the addition of Modified Gegen Qinlian Decoction has some effective on the prevention and treatment of coccidiosis in chickens. However, the mechanism of its treatment of chicken coccidiosis is not clear. The network pharmacology study was based on the screening of chemical components and related targets from TCMSP and PharmMapper server databases. Genes related to chicken coccidiosis were obtained from the SRA database, and those genes that intersected with the target genes of Modified Gegen Qinlian Decoction were screened. By exploring the target interactions through the String system and enrichment analysis by the Metascape system, the mechanism of action of Modified Gegen Qinlian Decoction in chicken coccidiosis was identified. Using real-time quantitative polymerase chain reaction (RT-qPCR) to analyze the mRNA levels of the relevant factors in chicken coccidiosis, molecular docking was used to reveal the extent of binding of the key target genes predicted in the network pharmacology by the action of Modified Gegen Qinlian Decoction. Compound and target screening suggested that the 99 chemical targets of Modified Gegen Qinlian Decoction were involved in chicken coccidiosis, and the enrichment results of KEGG pathway suggested that Modified Gegen Qinlian Decoction was significantly associated with PI3K/AKT signaling pathway in chicken coccidiosis. The Hubba gene module in Cytoscape_v3.7.1 software was used to analyze the network topology to obtain the Hubba gene SRC, STAT3, and PPARG, etc. The molecular docking results showed that SRC, STAT3, and PPARG were key targets in the treatment of coccidiosis in chickens by Modified Gegen Qinlian Decoction, which was in agreement with the RT-qPCR results. Through network pharmacology, molecular docking and in vitro experiments, it was confirmed that Modified Gegen Qinlian Decoction fights against chicken coccidiosis through key targets such as SRC, STAT3, and PPARG.

Pseudorabies virus kinase UL13 phosphorylates H2AX to foster viral replication

The DNA damage response (DDR) pathway is critical for maintaining genomic integrity and sustaining organismal development. Viruses can either utilize or circumvent the DDR to facilitate their replication. Pseudorabies virus (PRV) infection was shown to induce apoptosis via stimulating DDR. However, the underlying mechanisms have not been fully explored to date. This study showed that PRV infection robustly activates the ATM and DNA-PK signaling pathways shortly after infection. However, inhibition of ATM, but not DNA-PK, could dampen PRV replication in cells. Importantly, we found that PRV-encoded serine/threonine kinase UL13 interacts with and subsequently phosphorylates H2AX. Furthermore, we found that UL13 deletion largely attenuates PRV neuroinvasiveness and virulence in vivo. In addtion, we showed that UL13 contributes to H2AX phosphorylation upon PRV infection both in vitro and in vivo, but does not affect ATM phosphorylation. Finally, we showed that knockdown of H2AX reduces PRV replication, while this reduction can be further enhanced by deletion of UL13. Taken together, we conclude that PRV-encoded kinase UL13 regulates DNA damage marker γH2AX and UL13-mediated H2AX phosphorylation plays a pivotal role in efficient PRV replication and progeny production.

Antiviral drug screen identifies DNA-damage response inhibitor as potent blocker of SARS-CoV-2 replication

SARS-CoV-2 has currently precipitated the COVID-19 global health crisis. We developed a medium-throughput drug-screening system and identified a small-molecule library of 34 of 430 protein kinase inhibitors that were capable of inhibiting the SARS-CoV-2 cytopathic effect in human epithelial cells. These drug inhibitors are in various stages of clinical trials. We detected key proteins involved in cellular signaling pathways mTOR-PI3K-AKT, ABL-BCR/MAPK, and DNA-damage response that are critical for SARS-CoV-2 infection. A drug-protein interaction-based secondary screen confirmed compounds, such as the ATR kinase inhibitor berzosertib and torin2 with anti-SARS-CoV-2 activity. Berzosertib exhibited potent antiviral activity against SARS-CoV-2 in multiple cell types and blocked replication at the post-entry step. Berzosertib inhibited replication of SARS-CoV-1 and the Middle East respiratory syndrome coronavirus (MERS-CoV) as well. Our study highlights key promising kinase inhibitors to constrain coronavirus replication as a host-directed therapy in the treatment of COVID-19 and beyond as well as provides an important mechanism of host-pathogen interactions.