Plasma Membrane Proteomic Profile Discovers Macrophage-capping Protein Related to Latent HIV-1

Background: Due to the persistence of latent HIV-infected cellular reservoirs, HIV virus can not be eradicated completely. Objective: To identify proteins related to HIV latency, we performed a subcellular proteomic study in HIV latent cell lines. Methods: An established HIV-1 latent cell model (J-Lat Tat-GFP Clone A7 cells, A7 cells) and its parental cell line (Jurkat cells) were used. The plasma membrane (PM) fraction from cultured cells was enriched through aqueous two-phase partition. PM proteins were extracted and then separated using two-dimensional electrophoresis (2DE). Differentially expressed proteins were identified by mass spectrometry, and verified by western blotting. Results: Thirteen non-redundant proteins were identified to be differentially expressed in the A7 PM fraction compared to those in the Jurkat PM. Eight had a PM location through Gene Ontology (GO) analysis. A differential protein network of CAPG-ACTR3-CD3D was detected to have interactions with HIV Vpr, Tat, gp160, etc. through STRING software analysis. One of the differential proteins (Macrophage-capping protein (CAPG)) was verified by western blotting to be down- regulated in two cell lines and HIV resting CD4+ T cells negatively selected from patients. Conclusion: We identified 13 proteins in A7 compared to Jurkat cells. CAPG may be a potential biomarker related to HIV latency.