ABSTRACT
To identify critical host factors necessary for human immunodeficiency virus 1 (HIV-1) replication, large libraries of short-peptide-aptamers were expressed retrovirally. The target of one inhibitor peptide, Pep80, identified in this screen was determined to be Snapin, a protein associated with the soluble N-ethyl maleimide sensitive factor adaptor protein receptor (SNARE) complex that is critical for calcium-dependent exocytosis during neurotransmission. Pep80 inhibited Ca²âº release from intracellular stores and blocked downstream signaling by direct interruption of the association between Snapin and an intracellular calcium release channel, the ryanodine receptor (RyR). NFAT signaling was preferentially abolished by Pep80. Expression of Snapin overcame Pep80-mediated inhibition of Ca²âº/NFAT signaling and HIV-1 replication. Furthermore, Snapin induced HIV-1 replication in primary CD4⺠T cells. Thus, through its interaction with RyR, Snapin is a critical regulator of Ca²âº signaling and T cell activation. Use of the genetically selected intracellular aptamer inhibitors allowed us to define unique mechanisms important to HIV-1 replication and T cell biology.
Subject(s)
Calcium/metabolism , HIV-1/physiology , Ryanodine Receptor Calcium Release Channel/metabolism , T-Lymphocytes/metabolism , T-Lymphocytes/virology , Vesicular Transport Proteins/metabolism , Cell Line , Flow Cytometry , Humans , Immunoblotting , Immunoprecipitation , Jurkat Cells , Microscopy, Confocal , Protein Binding , Ryanodine Receptor Calcium Release Channel/genetics , Two-Hybrid System Techniques , Vesicular Transport Proteins/geneticsABSTRACT
T cell activation is crucial for the productive HIV-1 infection of primary T cells; however, little is known about the host molecules involved in this process. We show that the host transcription factor NF-IL6 (also called C/EBPbeta) renders primary CD4(+) T cells highly permissive for HIV-1 replication. NF-IL6 facilitates reverse transcription of the virus by binding to and inhibiting the antiviral cytidine deaminase APOBEC3G. A mutation in NF-IL6 at Ser-288 weakened its binding to APOBEC3G and strongly inhibited HIV-1 replication. NF-IL6 also induced the replication of a Vif-deficient strain of HIV-1 in nonpermissive HUT78 cells. These data indicate that NF-IL6 is a natural inhibitor of APOBEC3G that facilitates HIV-1 replication. Host factors, such as NF-IL6, that are involved in early HIV-1 replication are potential targets for anti-HIV-1 therapy. Our findings shed light on the activation of HIV-1 replication by T cell host molecules and reveal a unique regulation of DNA deamination by APOBEC3G and NF-IL6.
