SMYD2-Mediated Histone Methylation Contributes to HIV-1 Latency

Area of Science:

• Molecular Biology
• Virology
• Epigenetics

Background:

• Transcriptional latency of Human Immunodeficiency Virus (HIV) remains a significant obstacle to viral eradication.
• Chromatin remodeling and histone modifications are implicated in regulating HIV-1 reactivation, but mechanisms are not fully understood.

Purpose of the Study:

• To identify key regulators of HIV-1 latency using a large-scale RNAi screen.
• To elucidate the role of lysine methyltransferases in controlling HIV-1 transcriptional activity.

Main Methods:

• Conducted an RNA interference (RNAi)-based screen of human lysine methyltransferases.
• Utilized T cell lines and primary CD4+ T cells to assess HIV-1 reactivation.
• Performed chromatin immunoprecipitation and Western blotting to analyze protein-chromatin interactions and histone modifications.

Main Results:

• Identified SET and MYND domain-containing protein 2 (SMYD2) as a regulator of HIV-1 latency.
• Demonstrated that SMYD2 knockdown or inhibition reactivates latent HIV-1.
• Showed that SMYD2 associates with the latent HIV-1 promoter, which is enriched for histone H4 lysine 20 monomethylation (H4K20me1).
• Found that lethal 3 malignant brain tumor 1 (L3MBTL1), a reader of H4K20me1, is recruited to the HIV-1 promoter in a SMYD2-dependent manner.

Conclusions:

• A SMYD2-H4K20me1-L3MBTL1 axis contributes to maintaining HIV-1 latency.
• Targeting SMYD2 with small-molecule inhibitors represents a potential therapeutic strategy for HIV-1 eradication.