The nucleocapsid protein of rice stripe virus in cell nuclei of vector insect regulates viral replication

Rice stripe virus (RSV) transmitted by the small brown planthopper causes severe rice yield losses in Asian countries. Although viral nuclear entry promotes viral replication in host cells, whether this phenomenon occurs in vector cells remains unknown. Therefore, in this study, we systematically evaluated the presence and roles of RSV in the nuclei of vector insect cells. We observed that the nucleocapsid protein (NP) and viral genomic RNAs were partially transported into vector cell nuclei by utilizing the importin α nuclear transport system. When blocking NP nuclear localization, cytoplasmic RSV accumulation significantly increased. In the vector cell nuclei, NP bound the transcription factor YY1 and affected its positive regulation to FAIM. Subsequently, decreased FAIM expression triggered an antiviral caspase-dependent apoptotic reaction. Our results reveal that viral nuclear entry induces completely different immune effects in vector and host cells, providing new insights into the balance between viral load and the immunity pressure in vector insects.

Polypeptide cSN50 inhibits the expression of NF-κB and its downstream factor via Importin α in HepG2 cells / 中国综合临床

Objective To investigate whether polypeptide cSN50,as a transmembrane peptides,can inhibit NF-κB nuclear translocation and its downstream gene expression to play a role to protect cells by blocking the combination of NF-κB with the importinα3 during the alcohol and endotoxin-induced inflammation and apoptosis.Methods Flow cytometry method was used to observe the apoptosis rate of HepG2 by different concentration of alcohol and/or endotoxin.Spectrophotometer method was used to detect Caspase-3 activity.TNF- α in cell culture supernatant was detected by ELISA assay.p50,importinα3,and IκBαunder the stimulation of alcohol and/or endotoxin at selected optimal concentration were detected by Western blot.Indirect immunofluorescence assay was used to measure the activation of p50,IκBα,and importinα3.Results The change of TNF-α and Caspase-3 in the dose-effect course,compared with control group,was significant (P ＜0.05 ).p50 was increased in the nucleus ( P ＜ 0.05 ),and IκBα was decreased in the cytoplasm ( P ＜ 0.05 ).cSN50( 100 μmol/L) partially blocked nuclear translocation of p50 and its downstream factor( P ＜ 0.05 ).Conclusion NF-κB nuclear translocation may play an important role in acute alcoholic liver injury.cSN50 can effectively inhibit NF-κB activity and its downstream gene expression in HepG2 cells.