CPSF6 promotes HIV-1 preintegration complex function

Area of Science:

• Virology
• Molecular Biology
• Genetics

Background:

• Cleavage and polyadenylation specificity factor 6 (CPSF6) is a host factor involved in mRNA processing and HIV-1 replication.
• CPSF6 binds to the HIV-1 capsid (CA) and influences viral DNA integration targeting into gene-dense genomic regions.
• The precise role of CPSF6 in the function of the HIV-1 preintegration complex (PIC) remained largely uncharacterized.

Purpose of the Study:

• To investigate the effect of CPSF6 on the activity of the HIV-1 preintegration complex (PIC).
• To determine the role of the CPSF6-CA interaction in HIV-1 DNA integration and targeting.
• To elucidate how CPSF6 influences HIV-1 integration site selection within the host genome.

Main Methods:

• Extraction of PICs from CPSF6-depleted or CA-binding mutant cells for in vitro integration assays.
• Reconstitution experiments using purified recombinant CPSF6.
• Infection of CPSF6-mutant cells with HIV-1 and measurement of viral DNA integration, reverse transcription, and nuclear entry.
• Sequencing analysis of HIV-1 integration sites in CPSF6-mutant versus control cells.

Main Results:

• PICs from CPSF6-depleted or CA-binding mutant cells showed significantly reduced viral DNA integration activity.
• Addition of recombinant CPSF6 restored integration activity in mutant PICs, indicating a direct role.
• HIV-1 integration was significantly reduced in CPSF6-mutant cells, independent of reverse transcription or nuclear entry.
• Disruption of CPSF6-CA binding redirected HIV-1 integration away from gene-dense regions to gene-poor areas.

Conclusions:

• The CPSF6-CA interaction is crucial for stimulating HIV-1 preintegration complex (PIC) function.
• CPSF6 plays a direct role in promoting efficient viral DNA integration.
• The CPSF6-CA interaction dictates HIV-1 integration site selection, favoring gene-dense genomic regions.