Role of β-catenin and TCF/LEF family members in transcriptional activity of HIV in astrocytes

J Virol. 2012 Feb;86(4):1911-21. doi: 10.1128/JVI.06266-11. Epub 2011 Dec 7.

Abstract

The Wnt/β-catenin pathway is involved in diverse cell functions governing development and disease. β-Catenin, a central mediator of this pathway, binds to members of the TCF/LEF family of transcription factors to modulate hundreds of genes. Active Wnt/β-catenin/TCF-4 signaling plays a significant role in repression of HIV-1 replication in multiple cell targets, including astrocytes. To determine the mechanism by which active β-catenin/TCF-4 leads to inhibition of HIV replication, we knocked down β-catenin or TCF/LEF members in primary astrocytes and astrocytomas transiently transfected with an HIV long terminal repeat (LTR)-luciferase reporter that contained an integrated copy of the HIV LTR-luciferase construct. Knockdown of either β-catenin or TCF-4 induced LTR activity by 2- to 3-fold under both the episomal and integrated conditions. This knockdown also increased presence of serine 2-phosphorylated RNA polymerase II (Pol II) on the HIV LTR as well as enhanced its processivity. Knockdown of β-catenin/TCF-4 also impacted tethering of other transcription factors on the HIV promoter. Specifically, knockdown of TCF-4 enhanced binding of C/EBPβ, C/EBPδ, and NF-κB to the HIV LTR, while β-catenin knockdown increased binding of C/EBPβ and C/EBPδ but had no effect on NF-κB. Approximately 150 genes in astrocytes were impacted by β-catenin knockdown, including genes involved in inflammation/immunity, uptake/transport, vesicular transport/exocytosis, apoptosis/cellular stress, and cytoskeleton/trafficking. These findings indicate that modulation of the β-catenin/TCF-4 axis impacts the basal level of HIV transcription in astrocytes, which may drive low level/persistent HIV in astrocytes that can contribute to ongoing neuroinflammation, and this axis also has profound effects on astrocyte biology.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Astrocytes / metabolism*
  • Astrocytes / virology
  • Basic Helix-Loop-Helix Leucine Zipper Transcription Factors / genetics
  • Basic Helix-Loop-Helix Leucine Zipper Transcription Factors / metabolism*
  • Cell Line, Tumor
  • Cells, Cultured
  • Gene Expression Regulation, Viral
  • HIV Infections / genetics
  • HIV Infections / metabolism*
  • HIV Infections / virology
  • HIV Long Terminal Repeat
  • HIV-1 / genetics*
  • HIV-1 / physiology
  • Humans
  • Molecular Sequence Data
  • Signal Transduction
  • Transcription Factor 4
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*
  • Transcriptional Activation*
  • beta Catenin / genetics
  • beta Catenin / metabolism*

Substances

  • Basic Helix-Loop-Helix Leucine Zipper Transcription Factors
  • TCF4 protein, human
  • Transcription Factor 4
  • Transcription Factors
  • beta Catenin

Associated data

  • GENBANK/HQ882192