Molecular mechanisms behind the generation of pro-oncogenic HIV-1 matrix protein p17 variants

Area of Science:

• Virology
• Molecular Biology
• Oncology

Background:

• HIV-1 matrix protein p17 variants (vp17s) with COOH-terminal insertions exhibit distinct biological activities compared to wild-type p17.
• vp17s demonstrate potent B cell growth and clonogenic activity.
• Increased prevalence of vp17s in people living with HIV-1 (PLWH) with lymphoma suggests a role in lymphomagenesis.

Purpose of the Study:

• To investigate the molecular mechanisms underlying vp17 generation.
• To assess the role of HIV-1 Reverse Transcriptase (RT) in processing the genomic region associated with vp17s.
• To define the recombinogenic properties of mutation hotspots within the HIV-1 matrix gene.

Main Methods:

• Analysis of HIV-1 RT processing efficiency at specific genomic regions.
• Identification of mutation hotspots within the HIV-1 Gag gene, particularly near the matrix protein's end.
• Development of plasmid vectors for expressing Gag and modified Gag variants.
• Measurement of homologous recombination via next-generation sequencing following cell co-nucleofection.

Main Results:

• Hotspots of mutation were identified in the Gag gene, specifically at the C-terminus of the matrix protein, near the matrix-capsid junction.
• These hotspots are characterized by inverted repeats, palindromic sequences, and high Adenine content, which can cause HIV-1 RT pausing.
• Recombination events were observed at these hotspots, with imperfect recombination events potentially leading to the generation of vp17s.

Conclusions:

• The study elucidates potential mechanisms for vp17 generation, implicating specific mutation hotspots in the HIV-1 Gag gene.
• HIV-1 RT pausing at these hotspots, influenced by sequence features, contributes to genetic instability.
• Imperfect homologous recombination at these sites is proposed as the primary mechanism for generating biologically active vp17s, potentially linking them to lymphomagenesis in PLWH.