Cytomegalovirus Restructures Lipid Rafts via a US28/CDC42-Mediated Pathway, Enhancing Cholesterol Efflux from Host Cells

• HCMV modifies lipid rafts through viral protein US28 and host CDC42
• Lipid raft modification enhances binding of apoA-I and cholesterol efflux
• US28 modifies multiple aspects of host lipid metabolism
• Inflammatory response is blunted in US28-transfected macrophages

SummaryCytomegalovirus (HCMV) contains cholesterol, but how HCMV interacts with host cholesterol metabolism is unknown. We found that, in human fibroblasts, HCMV infection increased the efflux of cellular cholesterol, despite reducing the abundance of ABCA1. Mechanistically, viral protein US28 was acting through CDC42, rearranging actin microfilaments, causing association of actin with lipid rafts, and leading to a dramatic change in the abundance and/or structure of lipid rafts. These changes displaced ABCA1 from the cell surface but created new binding sites for apolipoprotein A-I, resulting in enhanced cholesterol efflux. The changes also reduced the inflammatory response in macrophages. HCMV infection modified the host lipidome profile and expression of several genes and microRNAs involved in cholesterol metabolism. In mice, murine CMV infection elevated plasma triglycerides but did not affect the level and functionality of high-density lipoprotein. Thus, HCMV, through its protein US28, reorganizes lipid rafts and disturbs cell cholesterol metabolism.

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