Ubiquitin-dependent recruitment of SLFN11 to chromatin is regulated by deubiquitinase (DUB) and RNF168

Area of Science:

• Molecular biology
• Cancer research
• Chromatin dynamics

Background:

• SLFN11 (Schlafen family member 11) is a key protein involved in DNA damage response and transcription regulation.
• The precise mechanisms governing SLFN11's recruitment to chromatin are not fully understood.
• Understanding SLFN11's recruitment is crucial for developing targeted cancer therapies.

Purpose of the Study:

• To elucidate the molecular mechanisms of SLFN11 chromatin recruitment.
• To identify specific molecular triggers and pathways involved in SLFN11 recruitment.
• To differentiate SLFN11 recruitment mechanisms induced by different stimuli.

Main Methods:

• High-throughput imaging of U2OS cells with inducible SLFN11 expression.
• Screening of 162 oncology-focused compounds, including deubiquitinase (DUB) inhibitors.
• Utilizing specific inhibitors like VLX-1570 and TAK243 to probe ubiquitylation pathways.
• Investigating the role of RNF168 in SLFN11 ubiquitylation and chromatin association.

Main Results:

• Deubiquitinase inhibitors, such as VLX-1570, induce robust SLFN11 chromatin recruitment, primarily at promoter regions, suppressing transcription.
• This DUB inhibitor-induced recruitment is ubiquitin-dependent and distinct from DNA damage-induced recruitment (e.g., camptothecin).
• TAK243 inhibits SLFN11 chromatin recruitment by both DUB inhibitors and DNA damage, confirming ubiquitylation dependency.
• RNF168 is essential for SLFN11 ubiquitylation and subsequent chromatin association, specifically at lysines 390, 391, and 429 via K27-linked polyubiquitin chains.

Conclusions:

• SLFN11 chromatin recruitment is critically dependent on its ubiquitylation, particularly by RNF168.
• Ubiquitylation, mediated by K27-linked polyubiquitin chains at specific sites, is essential for SLFN11's association with chromatin.
• These findings highlight the role of SLFN11 ubiquitylation in its transcriptional regulatory functions at promoter regions, offering new therapeutic avenues.