Roles of Ubiquitin-Proteasome System in Dengue Virus Infection

• Main Authors: Wei-JhengHuang, 黃偉政
• Other Authors: Michael M.C. Lai
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/87974124851067255029

碩士 === 國立成功大學 === 微生物及免疫學研究所 === 102 === Protein ubiquitination, one of the post-translational modifications, regulates a wide variety of cellular processes and plays important roles for numerous viruses during infection. However, questions remained whether dengue viral proteins can be modified by ubiquitination and how the modification affects viral functions. By two independent screening assays, we found that two structural proteins of dengue virus (DENV), prM and E, were consistently ubiquitinated in infected cells. A kinetic study by pulse treatment of MG132, a proteasome inhibitor, during a single viral replication cycle showed that DENV was drastically inhibited by MG132 at a relatively late stage of replication. These results suggested that ubiquitin-proteasome system (UPS) may regulate DENV replication. By using DENV replicon and subgenomic construct containing a luciferase reporter, we found that neither DENV genomic RNA replication nor translation was the major target of MG132. However, DENV release seems to be attenuated since prM protein and DENV infectivity in the culture supernatant from MG132-treated cells were both reduced. In vitro DENV virion maturation assay showed that the infectivity of DENV, either derived from MG132- or solvent-treated cells, could be further enhanced by incubation with recombinant furin. Interestingly, in vitro furin cleavage assay revealed that prM derived from MG132-treatment, which is highly ubiqutinated, became more sensitive to furin cleavage than that derived from solvent control. Taken together, these findings suggest that prM protein is ubiquitinated to regulate DENV maturation processes. Disturbance of this fine-tuned machinery, such as MG132 treatment, may serve a novel anti-DENV strategy in the future.