Baculovirus apoptosis suppressor gene IAP1 promotes nuclear accumulation of CyclinB in Bombyx mori

Abstract:

[Objective]Bombyx mori nucleopolyhedrovirus (BmNPV) is one of the most serious pathogens in sericulture.BmNPV infection blocked the cell cycle at G2/M phase in BmN-SWU1 cells.CyclinB is an important cyclin that regulates the transition from G2 phase to M phase of cell cycle.Therefore,studying the changes of CyclinB after BmNPV infection is of great significance to elucidate the mechanism of viral regulation of cell cycle and meanwhile,exploring the viral proteins interacting with CyclinB during this process can provide molecular targets for the construction of transgenic strains of Bombyx mori.[Methods] Quantitative real-time polymerase chain reaction (qRT-PCR) was used to detect the expression of BmCyclinB after BmNPV infection.The localization change of BmCyclinB after viral infection was observed by immunofluorescence and verified by cytoplasmic and nuclear protein separation experiment.Co-immunoprecipitation was employed to catch the viral proteins that interacted with BmCyclinB.The proportion of BmCyclinB into the nucleus was observed by knocking down BmNPV IAP1 after BmNPV infection.[Results]The transcription level of BmCyclinB was down-regulated after BmNPV infection and BmCyclinB was mainly located in cytoplasm before BmNPV infection and in nucleus after infection.BmNPV infection of BmN-SWU1 cells promoted the nuclear accumulation of BmCyclinB.A total of 7 viral proteins interacting with BmCyclinB were identified.The interaction between BmNPV IAP1 and BmCyclinB was confirmed by co-immunoprecipitation and cell co-localization.The amount of BmCyclinB entering the nucleus was significantly reduced after BmNPVIAP1 was knocked out during BmNPV infection. [Conclusion]BmNPV IAP1 can promote the accumulation of BmCyclinB in the nucleus by interacting with BmCyclinB.