Tat-SF1 is not required for Tat transactivation but does regulate the relative levels of unspliced and spliced HIV-1 RNAs.
Enviado por Mariano Garcia-Blanco el
Título | Tat-SF1 is not required for Tat transactivation but does regulate the relative levels of unspliced and spliced HIV-1 RNAs. |
Publication Type | Journal Article |
Year of Publication | 2009 |
Autores | Miller, HB, Saunders, KO, Tomaras, GD, García-Blanco, MA |
Journal | PLoS One |
Volume | 4 |
Issue | 5 |
Pagination | e5710 |
Date Published | 2009 |
ISSN | 1932-6203 |
Palabras clave | Cell Survival, HeLa Cells, HIV Long Terminal Repeat, HIV-1, Humans, RNA Splicing, RNA, Viral, tat Gene Products, Human Immunodeficiency Virus, Trans-Activators, Transcription, Genetic, Transcriptional Activation, Virus Replication |
Abstract | BACKGROUND: HIV-1 relies on several host proteins for productive viral transcription. HIV-1 Tat-specific factor 1 (Tat-SF1) is among these cofactors that were identified by in vitro reconstituted transcription reactions with immunodepleted nuclear extracts. At the onset of this work, the prevailing hypothesis was that Tat-SF1 was a required cofactor for the viral regulatory protein, Tat; however, this had not previously been formally tested in vivo. METHODOLOGY/PRINCIPAL FINDINGS: To directly address the involvement of Tat-SF1 in HIV-1 gene expression, we depleted Tat-SF1 in HeLa cells by conventional expression of shRNAs and in T- Rex -293 cells containing tetracycline-inducible shRNAs targeting Tat-SF1. We achieved efficient depletion of Tat-SF1 and demonstrated that this did not affect cell viability. HIV-1 infectivity decreased in Tat-SF1-depleted cells, but only when multiple rounds of infection occurred. Neither Tat-dependent nor basal transcription from the HIV-1 LTR was affected by Tat-SF1 depletion, suggesting that the decrease in infectivity was due to a deficiency at a later step in the viral lifecycle. Finally, Tat-SF1 depletion resulted in an increase in the ratio of unspliced to spliced viral transcripts. CONCLUSIONS/SIGNIFICANCE: Tat-SF1 is not required for regulating HIV-1 transcription, but is required for maintaining the ratios of different classes of HIV-1 transcripts. These new findings highlight a novel, post-transcriptional role for Tat-SF1 in the HIV-1 life cycle. |
DOI | 10.1371/journal.pone.0005710 |
Alternate Journal | PLoS ONE |
PubMed ID | 19479034 |