Small-molecule inhibitors of SETD8 with cellular activity

Area of Science:

• Biochemistry
• Molecular Biology
• Epigenetics

Background:

• SETD8 (also known as SET8, Pr-SET7, KMT5A) is the only known protein lysine methyltransferase (PKMT) that monomethylates histone H4 at lysine 20 (H4K20me1) in vivo.
• SETD8's enzymatic activity is crucial for fundamental cellular processes, including DNA replication, DNA damage response, transcriptional regulation, and cell cycle progression.

Purpose of the Study:

• To develop and validate cellularly active inhibitors of SETD8 for pharmacological studies.
• To investigate the distinct inhibition mechanisms and structural motifs of validated SETD8 inhibitors.

Main Methods:

• High-throughput screening (HTS) to identify initial hits.
• Validation of identified compounds (SPS8I1-3: NSC663284, BVT948, ryuvidine) as potent SETD8 inhibitors.
• Assessment of cellular activity, including H4K20me1 mark suppression and cell cycle analysis.

Main Results:

• Three compounds, SPS8I1-3, were confirmed as potent SETD8 inhibitors with diverse structural features and inhibition modes.
• These inhibitors effectively reduced the H4K20me1 mark in cells.
• SPS8I1-3 treatment induced S/G2/M-phase cell cycle defects, mirroring those seen with SETD8 knockdown via RNA interference.

Conclusions:

• The validated compounds (SPS8I1-3) demonstrate cellular efficacy in inhibiting SETD8 activity and its downstream effects.
• The distinct yet complementary mechanisms of SPS8I1-3 support their collective use for robust pharmacological perturbation of SETD8.
• These inhibitors provide valuable tools for further research into SETD8's multifaceted roles in cellular functions.