HIV-1Vpr Suppresses The Cytomegalovirus Promoter In A CRL4(DCAF1) E3Ligase Independent Manner

AIDS has made a development into a significant infectious disease since thesimian immunodeficiency virus had evolved into human immunodeficiency virus, andalso aroused concern in the field of both clinical medicine and basis. Twenty yearsago, after finding out the viral genomic structure and the particle protein compositionscientist realized the indispensable role played by these viral accessory proteinsduring viral series of life cycle, such as invasion, infection and replication. Among theaccessory proteins, Vpr is a multifunctional one in inducing G2cell cycle arrest orapoptosis, viral particle package, nuclear location and transactivate the HIV LTR orsome host factor expression. In our research, it’s the first time to report Vpr couldsuppress the cytomegalovirus promoter, which leads us to consider Vpr as an inhibitorof CMV. Cytomegalovirus infects a wide range from human to mammal and iscommon in organ transplantation and embryo congenital deformity. The treatment istough and few available drugs could be chosen. In our research, we apply thepromoter who takes charge in regulating CMV major immediate-early transcriptionexpression, is strong transactivator DNA fragment. It is critical for regulating thewhole CMV genome expression in transcriptional level and the mechanism is stillunclear as a result of DNA component and structure complexity. Therefore, ourdiscovery contributes to recognize the pathway of CMV promoter regulating in. Herewe have discovered an exogenous factor aimed at negatively regulating CMVpromoter transcriptionally. In our experiments, Vpr plasmid and CMV promoterexpression construct were co-transfected into HEK293T cells, Luciferase reporter andGFP were acted as tags respectively attached after CMV promoter and the relevantassays were chosen. Both of the results showed Vpr decreased CMV promoterexpression obviously. It demonstrated convincingly that Vpr has the potential to bedesigned into CMV vaccine. It reflects a first significant meaning of our project.Nowadays the pathway in which Vpr inhibits HIV-1LTR is puzzling theresearchers, either. We considered the classical CRL4(DCAF1) E3ligase firstly when solving the mechanism of Vpr suppression on CMV promoter transcriptionalexpression. HIV viral proteins degrade specially host restrict factors via traditionalubiquitin-proteasome pathway, meanwhile Vif, Vpx and Vpr fixed CRL-E3ligasesysterm. Three various tests identified Vpr inhibition occuring in a CRL4(DCAF1) E3ligase-independent manner. Meanwhile, there is another discovery that a negativedominant mutant A30/V31failing to suppress the CMV promoter. The mutant locatesin the first α-Helix and is highly conserved through comparing among differentspecies. What’s more, former figure told that the A30/V31also disable to induce cellcycle arrest. Next we verified Vpr also has regulation on the UNG2promoter andA30/V31loses the ability to transcript as well. It’s clear that A30/V31is a criticaldomain for Vpr playing the role in transcription, however, the mechanism of themutant’s disability is unknown and under discussed in the following research ifhaving relationship with G2arrest. The new domain is responsible for Vpr regulatingtranscription and guides to inhibit viral life cycle, which shows a second significance.Therefore we hypothesized a model for Vpr regulating transcription whose keypoint aimed at Vpr competitively interacting on host transcriptional factor reportedpreviously, such as NFkB and C/EBP, result in Vpr regulating host protein positivelyor negatively. It’s beneficial for HIV personal transcription. These transcriptionfactors have the potential to be developed into a drug for resisting HIV after they aremodified. Transforming basic researching into clinical application is a third meaningof our project.Given to the former model constructed according to the arm-race relationshipbetween viral protein and host restrictors, combining Vpr functions, we found HIV-1Vpr regulation on CMV promoter is species specific since partial SIV Vpr disable tocontrol transcription. The discovery reflects Vpr’s new role was chosen from viralprotein competing with host restrictors process and it could help to discuss themechanism. It’s the forth point in our research.As a result, combining Vpr inhibition on CMV promoter with the vital domain,learning about the mechanism will make a difference for developing anti-virus drugs and vaccine in practical application.