title: Nuclear retention of multiply spliced HIV-1 RNA in resting CD4+ T cells.
abstract: HIV-1 latency in resting CD4+ T cells represents a major barrier to virus eradication in patients on highly active antiretroviral therapy (HAART). We describe here a novel post-transcriptional block in HIV-1 gene expression in resting CD4+ T cells from patients on HAART. This block involves the aberrant localization of multiply spliced (MS) HIV-1 RNAs encoding the critical positive regulators Tat and Rev. Although these RNAs had no previously described export defect, we show that they exhibit strict nuclear localization in resting CD4+ T cells from patients on HAART. Overexpression of the transcriptional activator Tat from non-HIV vectors allowed virus production in these cells. Thus, the nuclear retention of MS HIV-1 RNA interrupts a positive feedback loop and contributes to the non-productive nature of infection of resting CD4+ T cells. To define the mechanism of nuclear retention, proteomic analysis was used to identify proteins that bind MS HIV-1 RNA. Polypyrimidine tract binding protein (PTB) was identified as an HIV-1 RNA-binding protein differentially expressed in resting and activated CD4+ T cells. Overexpression of PTB in resting CD4+ T cells from patients on HAART allowed cytoplasmic accumulation of HIV-1 RNAs. PTB overexpression also induced virus production by resting CD4+ T cells. Virus culture experiments showed that overexpression of PTB in resting CD4+ T cells from patients on HAART allowed release of replication-competent virus, while preserving a resting cellular phenotype. Whether through effects on RNA export or another mechanism, the ability of PTB to reverse latency without inducing cellular activation is a result with therapeutic implications.
authors.affiliation: Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
authors.forename: Kara G
authors.initials: KG
authors.lastname: Lassen
authors.forename: Kasra X
authors.initials: KX
authors.lastname: Ramyar
authors.forename: Justin R
authors.initials: JR
authors.lastname: Bailey
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhou
authors.forename: Robert F
authors.initials: RF
authors.lastname: Siliciano
mesh_terms: D000163:Acquired Immunodeficiency Syndrome / Q000235:genetics / Q000503:physiopathology; D023241:Antiretroviral Therapy, Highly Active; D015496:CD4-Positive T-Lymphocytes / Q000737:chemistry* / Q000502:physiology / Q000821:virology; D002467:Cell Nucleus / Q000737:chemistry* / Q000502:physiology / Q000821:virology; D015967:Gene Expression Regulation, Viral; D015694:Gene Products, rev / Q000032:analysis / Q000235:genetics / Q000502:physiology; D015696:Gene Products, tat / Q000032:analysis / Q000235:genetics / Q000502:physiology; D015497:HIV-1 / Q000235:genetics* / Q000472:pathogenicity / Q000502:physiology; D006801:Humans; D008213:Lymphocyte Activation / Q000235:genetics / Q000502:physiology; D038941:Polypyrimidine Tract-Binding Protein / Q000032:analysis / Q000235:genetics / Q000502:physiology; D012326:RNA Splicing; D012367:RNA, Viral / Q000032:analysis* / Q000235:genetics; D017735:Virus Latency / Q000502:physiology; D014779:Virus Replication / Q000235:genetics / Q000502:physiology; D054321:rev Gene Products, Human Immunodeficiency Virus; D054322:tat Gene Products, Human Immunodeficiency Virus
chemical_list: D015694:Gene Products, rev; D015696:Gene Products, tat; D012367:RNA, Viral; D054321:rev Gene Products, Human Immunodeficiency Virus; D054322:tat Gene Products, Human Immunodeficiency Virus; D038941:Polypyrimidine Tract-Binding Protein