Microplitis Bicoloratus Bracovirus Regulates NF-κB And Its Interactings Proteins,Cactus And Dip3

Microplitis bicoloratus bracovirus(MbBV)is a symbiotic virus of Microplitis bicoloratus.Previous studies have shown that MbBV inhibits cell transcription levels and may be involved in the regulation of NF-κB.However,there is still little research on the relationship between MbBV and NF-κB interacting protein Cactus and Dip3.MbBV contains many IκB-like gene have been found in previous experiments,named Viral ankyrin protein(Vank)uniformly.The structure of viral vanks are similar to the IκB in NF-κB protein.Dorsal-interacting protein 3(Dip3)is a protein that interacts with NF-κB.In this paper,we study MbBV to the NF-κB and its interacting proteins Cactus and Dip3.We dectect NF-κB downstream gene attacin,defensin use MbBV infects three lepidopteran insect cell lines,Spodoptera litura cell line Spli221,Spodoptera exigua cell line Sf9 and Spodoptera exigua cell line High Five,and dectect the relationship between IκB-like protein and Dip3 protein,then detect NF-κB downstream gene Innexins mRNA level.Furthermore we detect cell apoptosis after RNAi Cactus,RNAi Dip3.So we get the following results:The first one is that MbBV regulates transcription of NF-κB downstream antimicrobial peptide genes attacin’s and defensin’s mRNA,in which attacin is down regulated.MbBV gene fragments can be inserted into three lepidopteran insect cell lines,Spli221,Sf9 and High Five.Vank86 and Vank92 gene fragments can be detected in the genome of infected cells,and the transcription patterns are different.Overexpression Vank86 and Vank92 in Spli221 cells didn’t significantly inhibit the expression of attacin and defensin mRNA after LPS stimulation.The second one is that IκB-like proteins Vank86,Vank92,Vank101 and Dip3 form a heterologous dimer.Transient cotransfector discovery of Vank86-Dip3,Vank92-Dip3,and Vank101-Dip3 heterologousdimers,we suggest that BESS domain interacts with Ank-repeat.The study found that Cactus didn’t interact with Dip3,this suggests that it may be related to phosphorylation sites.Simultaneously,we find Cactus protein is distributed in cytoplasm and nucleus,MbBV inhibites protein expression of Cactus and Dip3 proteins.Overexpression Dip3 in cells infected with MbBV can inhibite transcription of NF-κB downstream gene Innexins.The third one is that under Spodoptera litura vitro conditions,dsRNA feeding finds that RNAi silence Cactus and Dip3 induce apoptosis of host blood cells.But the individual silences cann’t inhibit the host head development.These results suggest that MbBV inhibits NF-κB signaling pathway,IκB-like proteins and Dip3 protein form a heterologous dimer,RNAiCactus and RNAi Dip3 can induce apoptosis.These results could offer a reliable experiment basis for further study the mechanism of MbBV regulates immune signaling pathways and search target genes for future.