HIV-1 Vpr modulates macrophage metabolic pathways: a SILAC-based quantitative analysis

Area of Science:

• Virology
• Proteomics
• Cell Biology

Background:

• Human immunodeficiency virus type 1 (HIV-1) Vpr protein is crucial for macrophage infection and survival.
• Macrophages serve as viral reservoirs, but the impact of Vpr on their proteome remains unclear.

Purpose of the Study:

• To characterize the proteomic changes in macrophages in response to HIV-1 Vpr expression.
• To elucidate the mechanisms by which Vpr influences macrophage function and survival.

Main Methods:

• Stable-isotope labeling by amino acids in cell culture (SILAC) coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) was employed.
• U937 monocytic cells differentiated into macrophages and transduced with an adenovirus construct expressing Vpr.
• Proteomic data were analyzed using Ingenuity computational pathway analysis and validated by Western blot.

Main Results:

• Overexpression of Vpr in macrophages significantly altered the proteome, with 136 out of 600 quantified proteins showing significant changes.
• Increased abundance of glycolytic pathway enzymes (pentose phosphate and pyruvate metabolism) and downregulation of key mitochondrial enzymes (GLUD2, AK2, TKT) were observed.
• Vpr-induced changes suggest hijacking of glucose metabolism via the Vpr-hypoxia inducible factor 1 alpha (HIF-1 alpha) axis.

Conclusions:

• HIV-1 Vpr manipulates macrophage glucose metabolism, upregulating key enzymes like hexokinase (HK), glucose-6-phosphate dehydrogenase (G6PD), and pyruvate kinase muscle type 2 (PKM2).
• This metabolic reprogramming facilitates viral replication, biogenesis, and prolonged macrophage survival, contributing to viral reservoirs.
• Dysregulation of mitochondrial glutamate metabolism may link to neurodegeneration in NeuroAIDS through neuroexcitotoxicity.