Tat-SF1 is not required for Tat transactivation but does regulate the relative levels of unspliced and spliced HIV-1 RNAs

Heather B. Miller, Kevin O. Saunders, Georgia D. Tomaras, Mariano Garcia-Blanco

Research output: Contribution to journalArticle

12 Citations (Scopus)

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.

Original languageEnglish (US)
Article numbere5710
JournalPLoS One
Volume4
Issue number5
DOIs
StatePublished - May 27 2009
Externally publishedYes

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transcriptional activation
Transcription
Human immunodeficiency virus 1
Transcriptional Activation
HIV-1
RNA
Viral Regulatory and Accessory Proteins
transcription (genetics)
HIV Long Terminal Repeat
Tetracycline
Gene expression
Life cycle
pathogenicity
Cells
Viral Proteins
Life Cycle Stages
HeLa Cells
viral proteins
regulatory proteins
cells

ASJC Scopus subject areas

  • Agricultural and Biological Sciences(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Medicine(all)

Cite this

Tat-SF1 is not required for Tat transactivation but does regulate the relative levels of unspliced and spliced HIV-1 RNAs. / Miller, Heather B.; Saunders, Kevin O.; Tomaras, Georgia D.; Garcia-Blanco, Mariano.

In: PLoS One, Vol. 4, No. 5, e5710, 27.05.2009.

Research output: Contribution to journalArticle

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