Viperin Differentially Induces Interferon-Stimulated Genes in Distinct Cell Types

Area of Science:

• Immunology
• Molecular Biology
• Virology

Background:

• Viperin is an interferon-stimulated gene (ISG)-encoded protein with diverse cellular functions, including antiviral activity and regulation of signaling pathways.
• Previous studies indicate viperin has contrasting roles in interferon (IFN) production in different immune cells.
• The effect of viperin on ISG induction in cell types beyond macrophages remains largely unexplored.

Purpose of the Study:

• To investigate the cell type-dependent effects of viperin on the induction of interferon-stimulated genes (ISGs).
• To compare viperin's role in ISG regulation in macrophages versus fibroblasts.
• To elucidate how viperin influences innate immune responses in different cell types.

Main Methods:

• Utilized wild type and viperin knockout mice to isolate bone marrow-derived macrophages (BMDMs) and murine embryonic fibroblasts (MEFs).
• Stimulated cells with type I/II IFN, polyinosinic-polycytidylic acid, CpG DNA, or murine cytomegalovirus (MCMV).
• Quantified the expression levels of key ISGs (e.g., bone marrow stromal cell antigen-2, Isg15, Isg54) and assessed viral entry efficiency.

Main Results:

• Viperin downregulates ISG expression in murine embryonic fibroblasts (MEFs) upon treatment with type I or II IFN.
• Conversely, viperin upregulates ISG expression in both bone marrow-derived macrophages (BMDMs) and MEFs when stimulated with nucleic acid analogs or infected with MCMV.
• Higher ISG expression levels correlated with reduced viral entry efficiency in both cell types.

Conclusions:

• Viperin exhibits differential regulation of ISG induction in a cell type-dependent manner.
• These distinct regulatory roles of viperin contribute to varied innate immune responses in macrophages and fibroblasts against viral infections.
• Viperin's context-specific function highlights its complex role in host defense mechanisms.