MbBVs Regulate CypA-AIF Interaction To Induce Insect Cells Apoptosis

S.litura can be parasitized by M.bicoloratus,which release MbBV into the larvae of S.litura.MbBV is unique virus located in wasps such as M.bicoloratus,it can attack host cells and plays a role in innate immunity,growth and development.The aim of our study is to investigate the role of AIF and CypA in the apoptosis induced by MbBV,and to further explain the molecular mechanism that the apoptosis of host hemocytes was induced by MbBV.Firstly,We found that parasitism and MbBV infection can upregulate CypA by enhancing ROS production in parasitized cells or MbBV-infected cells.By immunofluorescence,CypA is distributed in both cytoplasm and nucleus.These results indicate that CypA may contribute to the MbBV-mediated apoptosis.Secondly,during parssitism and MbBV infection,AIF was released from damaged mitochondria and increased in the nucleus,which indicates that AIF undergo cytoplasm-nuclear translocation.Finally,by Co-immunoprecipitation,Pull-Down and EMSA assay,further illustrated that AIF can interact with CypA and bind to DNA directly,which causes DNA fragment and apoptosis.Blocking the combination of CypA and AIF can rescue apoptotic cells induced by MbBV.In summary,these data incicate that MbBV upregulates the expression of CypA and release AIF from mitochondria,MbBV infection can promote the formation of AIF-CypA complex,which leads to apoptosis by cleavage of genomic DNA.Our findings provides a new idea for further understanding the molecular mechanism of MbBV-induced apoptosis and innate immunity.