Dengue virus reduces expression of low-density lipoprotein receptor-related protein 1 to facilitate replication in Aedes aegypti

Abstract

Aedes aegypti is the primary vector of a number of viruses pathogenic to humans including dengue virus (DENV). DENV infection leads to widespread transcriptomic and proteomic alterations in mosquito cells. Here we identified alterations to the mosquito cell secretome during DENV infection by performing liquid chromatography tandem mass spectrometry. We found that an extracellular fragment of low-density lipoprotein receptor-related protein 1 (LRP-1) was present during infection. Previous literature suggests that LRP-1 regulates cholesterol homeostasis. Therefore, we hypothesized that DENV modifies LRP-1 protein expression to maintain host-derived intracellular cholesterol, which would facilitate virus replication within membrane-associated replication compartments. Accordingly, stimuli that are present during flavivirus infection reduced LRP-1 protein expression. We also found that dsRNA knockdown of LRP-1 increased intracellular cholesterol and DENV viral RNA. Further, depletion of intracellular lipids reduced infection. Together, these data suggest that DENV reduces LRP-1 protein expression, possibly through regulated intramembrane proteolysis (RIP), to increase intracellular cholesterol and facilitate replication in Ae. aegypti .

The low-density lipoprotein receptor-related protein-1 is essential for Dengue virus infection

“…Were LRP1 to play a role in the entry of DENV into mosquito cells similar to that described here in human cells, it would position this receptor as a prime target for the development of antiviral strategies. However, in contrast with our results, silencing of LRP1 orthologs in mosquito cells actually increases the copy number of viral RNA in infected cells [28]. This paradoxical result, according to the data published by Tree et al ., stems from the involvement of LRP1 in the regulation of intracellular cholesterol, whereby lower LRP1 levels would increase the amount of intracellular cholesterol and, therefore, facilitate viral replication [28].…”

“…However, in contrast with our results, silencing of LRP1 orthologs in mosquito cells actually increases the copy number of viral RNA in infected cells [28]. This paradoxical result, according to the data published by Tree et al ., stems from the involvement of LRP1 in the regulation of intracellular cholesterol, whereby lower LRP1 levels would increase the amount of intracellular cholesterol and, therefore, facilitate viral replication [28]. Undoubtedly, the precise role of LRP1 in DENV infection of human and mosquito cells deserves the focus of further research efforts.…”

“…Regulation of lipid metabolism influences significantly the efficiency of DENV infection and replication in vitro e in vivo [25–28]. Sequence stretches on DENV E and capsid proteins resemble receptor binding motifs of ApoE [29].…”

Lipid hijacking: A unifying theme in vector-borne diseases

“…Insects are cholesterol auxotrophs; therefore, mosquito-borne viruses must co-opt different processes to obtain lipids in the vector. To maintain intracellular cholesterol, DENV downregulates expression of the low-density lipoprotein receptor-related protein 1 (LRP-1), a protein involved in cholesterol export that facilitates viral replication in mosquitoes ( Tree et al, 2019 ). Interestingly, while the induction of DENV replication vesicles is conserved between mammals and mosquitoes, infected mosquito cells do not display convoluted ER membranes, possibly due to the lack of cholesterol synthesis ( Junjhon et al, 2014 ).…”

“…They both store excess lipids in the form of triacylglycerols and intracellular lipid droplets, they synthesize fatty acids and phospholipids for cellular membranes, and hematophagous arthropods acquire mammalian lipids (e.g. cholesterol) during blood meal and incorporate them in their cellular processes ( Arrese and Soulages, 2010 ; Tree et al, 2019 ). Although many of these processes are conserved across species, the role of metabolism in dual host adaptation remains to be defined.…”