Waking the sleeping giant: Single-stranded DNA binds Schlafen 11 to initiate innate immune responses

Area of Science:

• Molecular Biology
• Immunology
• Cell Death Pathways

Background:

• Schlafen 11 (SLFN11) is a protein with known antiviral and anti-proliferative functions.
• The precise mechanisms by which SLFN11 exerts its effects are still under investigation.

Purpose of the Study:

• To elucidate the molecular mechanism by which single-stranded DNA (ssDNA) activates SLFN11.
• To identify the specific DNA motifs recognized by SLFN11.
• To understand how SLFN11 binding to DNA leads to downstream cellular responses.

Main Methods:

• In vitro binding assays to test ssDNA motif recognition by SLFN11.
• Cell-based assays to measure cell death and cytokine production upon SLFN11 activation.
• Biochemical assays to assess SLFN11 ribonuclease activity.

Main Results:

• Single-stranded DNA containing CGT/A motifs was identified as a specific ligand for the helicase domain of SLFN11.
• Binding of this ssDNA to SLFN11 initiates a signaling cascade leading to apoptosis.
• SLFN11 ribonuclease activity is crucial for mediating both cell death and cytokine release.

Conclusions:

• SLFN11 directly binds to CGT/A-containing ssDNA via its helicase domain.
• This interaction serves as a trigger for SLFN11-mediated cell death and inflammatory cytokine production.
• The findings reveal a novel mechanism of innate immune activation and cell fate determination by SLFN11.