SARS-CoV-2 NSP13 interacts with host IRF3, blocking antiviral immune responses.

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), poses an unprecedented threat to human health since late 2019. Notably, the progression of the disease is associated with impaired antiviral interferon (IFN) responses. Although multiple viral proteins were identified as potential IFN antagonists, the underlying molecular mechanisms remain to be fully elucidated. In this study, we firstly demonstrate that SARS-CoV-2 NSP13 protein robustly antagonizes IFN response induced by the constitutively active form of transcription factor IRF3 (IRF3/5D). This induction of IFN response by IRF3/5D is independent of the upstream kinase, TBK1, a previously reported NSP13 target, thus indicating that NSP13 can act at the level of IRF3 to antagonize IFN production. Consistently, NSP13 exhibits a specific, TBK1-independent interaction with IRF3, which, moreover, is much stronger than that of NSP13 with TBK1. Furthermore, the NSP13-IRF3 interaction was shown to occur between the NSP13 1B domain and IRF3 IRF association domain (IAD). In agreement with the strong targeting of IRF3 by NSP13, we then found that NSP13 blocks IRF3-directed signal transduction and antiviral gene expression, counteracting IRF3-driven anti-SARS-CoV-2 activity. These data suggest that IRF3 is likely to be a major target of NSP13 in antagonizing antiviral IFN responses and provide new insights into the SARS-CoV-2-host interactions that lead to viral immune evasion.

SHOX CNE9/10 Knockout in U2OS Osteosarcoma Cells and Its Effects on Cell Growth and Apoptosis.

BACKGROUND Osteosarcoma is a common malignant tumor of musculoskeletal stromal cells. Osteosarcoma clinical behavior depends mostly on the histologic grade, the site of primary tumor, the response to chemotherapy, and the presence of pulmonary metastases. The aim of this study was to knockout SHOX CNE9/10 in U2OS osteosarcoma cells and to analyze the effects on cell growth and apoptosis. MATERIAL AND METHODS U2OS cells with CNE9 knockout and U2OS cells with CNE10 knockout were established via the CRISPR/Cas9 system. Sanger sequencing was used to detect the success of the knockdown experiment. Western blotting and quantitative polymerase chain reaction were used to detect the expression levels of short stature homeobox-containing gene (SHOX) protein and messenger RNA (mRNA) after knockdown of CNE9 and CNE10. The cell viability and apoptotic rate were detected by the Cell Counting Kit-8 method and by flow cytometry. RESULTS The Sanger sequencing results showed that the knockdown experiment was successful. The levels of SHOX mRNA and protein were significantly reduced after knocking down CNE9 and CNE10. Knockdown of CNE9 and CNE10 significantly increased the growth and inhibited the apoptosis of U2OS osteosarcoma cells. CNE9/CNE10 knockdown U2OS cells were successfully constructed. CONCLUSIONS Knockdown of CNE9 and CNE10 promoted U2OS cell growth and inhibited apoptosis by decreasing SHOX expression. This CNE9/CNE10 knockout U2OS cell model could provide a bridge for the research on SHOX and CNEs in osteosarcoma.

CDH17 alters MMP-2 expression via canonical NF-κB signalling in human gastric cancer.

Gastric cancer (GC), one of the most common cancers of the digestive system, results in high morbidity and mortality, but the molecular mechanisms underlying GC remain largely unknown. Cadherin-17 (CDH17) is a nonclassical member of the cadherin (CDH) superfamily of calcium-dependent proteins. Despite recent advances in the understanding of CDH17 biology, the mechanism of CDH17 in GC proliferation, migration, and invasion has not been extensively studied. In the present study, we observed that CDH17 expression was increased in GC tissues compared with para-carcinoma tissues and was correlated with lymph node metastasis and the AJCC stage. Additionally, a significant correlation was found between CDH17 protein expression and the number of blood and lymph vessels in GC tissues. Furthermore, in vitro suppression of CDH17 expression using short-interfering RNA (siRNA) decreased AGS cell proliferation, migration and invasion. Conversely, overexpression of CDH17 through plasmid transfection enhanced the malignant activity of AGS cells. Moreover, CDH17 increased the matrix metallopeptidase 2 (MMP-2) levels via the canonical nuclear factor-kappaB (NF-κB) pathway. Our findings offer new insights into the mechanism of the CDH17/NF-κB/MMP-2 axis, and the associated signalling pathways might represent novel targets for the treatment of GC.