Interferon-dependent R-loop induction by Zika virus contributes to growth attenuation.

Area of Science:

• Molecular Biology
• Virology
• Neuroscience

Background:

• Zika virus (ZIKV) infection of human neural progenitors causes DNA damage and cell cycle arrest, potentially impairing brain development.
• The precise molecular mechanisms underlying ZIKV-induced neural progenitor cell cycle arrest remain incompletely understood.

Purpose of the Study:

• To investigate the link between ZIKV-induced S phase arrest, replication fork stalling, and R-loop formation.
• To elucidate the role of interferon-stimulated genes (ISGs) and R-loops in ZIKV pathogenesis.

Main Methods:

• DNA Damage Response (DDR) assays
• DRIP-seq (DNA-RNA immunoprecipitation sequencing) to identify R-loop locations
• Bromouridine sequencing to analyze nascent transcripts
• Gene knockout (IFN receptor) and overexpression (RNaseH1) studies

Main Results:

• ZIKV infection induces R-loops at specific loci, particularly within interferon-stimulated genes (ISGs).
• Nascent ISG transcripts are prone to R-loop formation during ZIKV infection.
• Eliminating the IFN receptor abolished R-loops on ISGs and partially rescued S-phase arrest.
• RNaseH1 overexpression reduced ZIKV-induced DNA damage and cell cycle arrest.

Conclusions:

• ZIKV-induced unscheduled ISG expression disrupts R-loop homeostasis, leading to replication fork stalling and DNA damage.
• IFN-dependent R-loop induction is a novel nucleic acid-based mechanism contributing to cell cycle arrest in ZIKV-infected neural cells.