Cyclin L2 is a critical HIV dependency factor in macrophages that controls SAMHD1 abundance

Area of Science:

• Virology
• Cell Biology
• Immunology

Background:

• The restriction factor SAMHD1 (Sterile alpha motif and HD domain-containing protein 1) inhibits HIV-1 replication in noncycling cells.
• HIV-2 and SIV utilize the Vpx protein to degrade SAMHD1 via DCAF1, facilitating viral replication.
• The mechanisms by which HIV-1 replicates in macrophages, despite SAMHD1 presence, remain unclear.

Purpose of the Study:

• To identify host factors enabling HIV-1 replication in macrophages.
• To elucidate the role of cyclin L2 in HIV-1 replication within macrophages.

Main Methods:

• Yeast two-hybrid screening to identify DCAF1-interacting proteins.
• Gene knockdown experiments to assess the impact of cyclin L2 on HIV-1 replication.
• Co-immunoprecipitation assays to analyze protein complex formation and degradation pathways.

Main Results:

• Cyclin L2 was identified as a DCAF1-interacting protein essential for HIV-1 replication in macrophages.
• Knockdown of cyclin L2 significantly attenuated HIV-1 replication in macrophages, an effect dependent on SAMHD1.
• Cyclin L2 forms a complex with SAMHD1, leading to its proteasomal and DCAF1-dependent degradation.

Conclusions:

• Cyclin L2 is a critical host factor that promotes HIV-1 replication in macrophages.
• Cyclin L2 facilitates viral replication by mediating the degradation of the restriction factor SAMHD1.
• Targeting the cyclin L2-SAMHD1 interaction could offer a novel therapeutic strategy against HIV-1 in macrophages.