Stochastic expression of the interferon-β gene

Area of Science:

• Immunology
• Molecular Biology
• Virology

Background:

• Virus infection triggers type I interferons (IFNα and β) production in mammalian cells.
• IFN production is crucial for orchestrating antiviral innate and adaptive immunity.
• Only a fraction of infected cells produce IFN, with mechanisms of this stochasticity poorly understood.

Purpose of the Study:

• To deeply analyze the mechanisms underlying stochastic interferon-beta (IFNβ) expression in virus-infected mouse cells.
• To identify the molecular factors contributing to cell-to-cell variability in IFNβ production.

Main Methods:

• Utilized mouse embryonic fibroblasts engineered with an internal ribosome entry site/yellow fluorescent protein (IRES/YFP) reporter downstream of the IFNβ gene.
• Separated IFN-expressing and non-expressing cells using fluorescence-activated cell sorting (FACS).
• Analyzed molecular differences between sorted cell populations.

Main Results:

• Stochastic IFNβ expression results from cell-to-cell variability in limiting components of the induction pathway.
• Variability observed across multiple levels: viral replication, RNA sensing, signaling pathway activation, and transcription factor levels.
• Identified specific molecular differences between IFN-producing and non-producing cells.

Conclusions:

• Cell-to-cell variability in molecular components drives stochastic IFNβ gene expression.
• This complex stochasticity likely evolved to optimize type I IFN levels and distribution for effective antiviral defense.
• Provides a detailed molecular basis for understanding innate immune response heterogeneity.