Alpha Interferon Potently Enhances the Anti-Human Immunodeficiency Virus Type 1 Activity of APOBEC3G in Resting Primary CD4 T Cells

Abstract

The interferon (IFN) system, including various IFNs and IFN-inducible gene products, is well known for its potent innate immunity against wide-range viruses. Recently, a family of cytidine deaminases, functioning as another innate immunity against retroviral infection, has been identified. However, its regulation remains largely unknown. In this report, we demonstrate that through a regular IFN-␣/␤ signal transduction pathway, IFN-␣ can significantly enhance the expression of apolipoprotein B mRNA-editing enzyme-catalytic polypeptide-like 3G (APOBEC3G) in human primary resting but not activated CD4 T cells and the amounts of APOBEC3G associated with a low molecular mass. Interestingly, short-time treatments of newly infected resting CD4 T cells with IFN-␣ will significantly inactivate human immunodeficiency virus type 1 (HIV-1) at its early stage. This inhibition can be counteracted by APOBEC3G-specific short interfering RNA, indicating that IFN-␣-induced APOBEC3G plays a key role in mediating this anti-HIV-1 process. Our data suggest that APOBEC3G is also a member of the IFN system, at least in resting CD4 T cells. Given that the IFN-␣/ APOBEC3G pathway has potent anti-HIV-1 capability in resting CD4 T cells, augmentation of this innate immunity barrier could prevent residual HIV-1 replication in its native reservoir in the post-highly active antiretroviral therapy era.

N-Terminal Hemagglutinin Tag Renders Lysine-Deficient APOBEC3G Resistant to HIV-1 Vif-Induced Degradation by Reduced Polyubiquitination

“…Since the major function of HIV-1 Vif is to exclude A3G from HIV-1 virions, enhancement of A3G viral incorporation will have a significant impact on anti-AIDS pharmacologic strategies. Indeed, when A3G manages to be packaged into HIV-1 virions through upregulation of expression, the exosomal pathway, enhancement of packaging, or resistance to Vif-induced degradation, it can inhibit the replication of even Vif-proficient HIV-1 (1,4,13,31,33,57,68). Here, we showed that lysinedeficient A3G (A3G20K/R) was resistant to Vif-induced degradation when an HA tag was fused to the N terminus of A3G20K/R (Fig.…”

Derepression of MicroRNA-mediated Protein Translation Inhibition by Apolipoprotein B mRNA-editing Enzyme Catalytic Polypeptide-like 3G (APOBEC3G) and Its Family Members

“…Cell Isolation, Culture, and Transfection-Primary CD4ϩ T lymphocytes were isolated from peripheral blood mononuclear cells using the CD4ϩ T cell isolation kit II (Miltenyi, Auburn, CA) and subsequently activated by treating with phytohemagglutinin (PHA) (42). The purity of CD4 T-cells can reach 98%.…”

“…Monocytes were further cultured in complete RPMI in the presence of 0.5 ng/ml recombinant human macrophage colony stimulating factor (M-CSF, R&D Systems) and 0.5 ng/ml granulocyte colony-stimulating factor (G-CSF, R&D Systems) for 7 days. The activated CD4ϩ T cells and H9 T cells were transfected using an Amaxa nucleofector apparatus (Amaxa Biosystems, Gaithersburg, MD), as described (42 miRNA Array Analysis-Total RNA (10 g) from 293T cells transfected with pcDNA-A3G-HA or the pcDNA3 parent vector was isolated with TRIzol reagent (Invitrogen). The following RNA processing, microarray fabrication, array hybridization, and data acquisition were performed at LC Sciences (Houston, TX).…”

Role of retroviral restriction factors in the interferon-α–mediated suppression of HIV-1 in vivo

“…The antiretroviral activity of the IFN-α cytokine was demonstrated in vitro almost immediately after the discovery of HIV-1, and includes inhibition of HIV-1 reverse transcription, viral assembly, and virion release (26). IFN-α has been reported to suppress HIV-1 viremia in chronically infected individuals (27)(28)(29), and is known to induce APOBEC3 and BST-2 expression in a number of tissues and cell types in vitro (7,(30)(31)(32). However, to date, no data describe the effects of exogenous IFN-α treatment on the expression of these restriction factors in vivo, and the relevance of these factors to virologic control in chronically infected individuals is unknown.…”