MAP-Kinase Regulated Cytosolic Phospholipase A2 Activity Is Essential for Production of Infectious Hepatitis C Virus Particles
Open Access
- 26 July 2012
- journal article
- research article
- Published by Public Library of Science (PLoS) in PLoS Pathogens
- Vol. 8 (7), e1002829
- https://doi.org/10.1371/journal.ppat.1002829
Abstract
Hepatitis C virus (HCV) has infected around 160 million individuals. Current therapies have limited efficacy and are fraught with side effects. To identify cellular HCV dependency factors, possible therapeutic targets, we manipulated signaling cascades with pathway-specific inhibitors. Using this approach we identified the MAPK/ERK regulated, cytosolic, calcium-dependent, group IVA phospholipase A2 (PLA2G4A) as a novel HCV dependency factor. Inhibition of PLA2G4A activity reduced core protein abundance at lipid droplets, core envelopment and secretion of particles. Moreover, released particles displayed aberrant protein composition and were 100-fold less infectious. Exogenous addition of arachidonic acid, the cleavage product of PLA2G4A-catalyzed lipolysis, but not other related poly-unsaturated fatty acids restored infectivity. Strikingly, production of infectious Dengue virus, a relative of HCV, was also dependent on PLA2G4A. These results highlight previously unrecognized parallels in the assembly pathways of these human pathogens, and define PLA2G4A-dependent lipolysis as crucial prerequisite for production of highly infectious viral progeny. The human genome encodes more than 30 phospholipase A2s. These enzymes cleave fatty acids at the C2 atom of phosphoglycerides and thus modulate membrane properties. Among all PLA2s only PLA2G4A, which is recruited to perinuclear membranes by Ca2+ and activated by extracellular stimuli via the mitogen activated protein kinase pathway, specifically cleaves lipids with arachidonic acid. Metabolism of arachidonic acid yields prostaglandins and leukotriens, important lipid mediators of inflammation. We show that inhibition of PLA2G4A produces aberrant HCV particles and that infectivity is rescued by addition of arachidonic acid. Our results suggest that a specific lipid (arachidonic acid) is essential for production of highly infectious HCV progeny, likely by creating a membrane environment conducive for efficient incorporation of crucial host and viral factors into the lipid envelope of nascent particles. Strikingly, PLA2G4A is also essential for production of highly infectious Dengue Virus (DENV) particles but not for vesicular stomatitis virus (VSV). These observations argue that HCV and DENV which unlike VSV produce particles at intracellular membranes usurp a common host factor (PLA2G4A) for assembly of highly infectious progeny. These findings open new perspectives for antiviral intervention and highlight thus far unrecognized parallels in the assembly pathway of HCV and DENV.Keywords
This publication has 57 references indexed in Scilit:
- Effects of fatty acid unsaturation numbers on membrane fluidity and α-secretase-dependent amyloid precursor protein processingNeurochemistry International, 2011
- Efficient hepatitis C virus particle formation requires diacylglycerol acyltransferase-1Nature Medicine, 2010
- Aging of Hepatitis C Virus (HCV)-Infected Persons in the United States: A Multiple Cohort Model of HCV Prevalence and Disease ProgressionGastroenterology, 2010
- A cell protection screen reveals potent inhibitors of multiple stages of the hepatitis C virus life cycleProceedings of the National Academy of Sciences of the United States of America, 2010
- Apolipoprotein E on hepatitis C virion facilitates infection through interaction with low-density lipoprotein receptorVirology, 2009
- Low pH-dependent Hepatitis C Virus Membrane Fusion Depends on E2 Integrity, Target Lipid Composition, and Density of Virus ParticlesPublished by Elsevier BV ,2009
- Composition and Three-Dimensional Architecture of the Dengue Virus Replication and Assembly SitesCell Host & Microbe, 2009
- Hepatitis C virus production by human hepatocytes dependent on assembly and secretion of very low-density lipoproteinsProceedings of the National Academy of Sciences of the United States of America, 2007
- Construction and characterization of infectious intragenotypic and intergenotypic hepatitis C virus chimerasProceedings of the National Academy of Sciences of the United States of America, 2006
- Production of infectious hepatitis C virus in tissue culture from a cloned viral genomeNature Medicine, 2005