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Transcription factor AP-2 regulates human immunodeficiency virus type 1 gene expression
N D Perkins1, A B Agranoff, C S Duckett
1Howard Hughes Medical Institute, Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor 48109-0650.
Journal of Virology
|October 1, 1994
Summary
Transcription factor AP-2 binding sites in the human immunodeficiency virus type 1 (HIV-1) enhancer regulate gene expression. AP-2 binding at the NF-kappa B site impacts basal transcription but not TNF-alpha induction.
Area of Science:
- Molecular Biology
- Virology
- Genetics
Background:
- Human immunodeficiency virus type 1 (HIV-1) gene expression relies on enhancer regions with multiple regulatory sites.
- Transcription factors play crucial roles in modulating viral gene activity.
Purpose of the Study:
- To identify and characterize binding sites for the transcription factor AP-2 within the HIV-1 enhancer region.
- To investigate the functional impact of AP-2 binding on HIV-1 gene expression and its interplay with NF-kappa B.
Main Methods:
- DNase I footprinting assays to map AP-2 binding sites.
- Electrophoretic mobility shift assays (EMSA) to confirm AP-2 binding.
- Site-directed mutagenesis to disrupt AP-2 binding sites.
- Reporter gene assays to measure transcriptional activity.
Main Results:
- Two AP-2 binding sites were identified in the HIV-1 long terminal repeat (LTR).
- One AP-2 binding site is located between the two NF-kappa B elements.
- AP-2 and NF-kappa B bind to this region in a mutually exclusive manner.
- Mutations disrupting the AP-2 binding site reduced basal HIV-1 transcription.
- These mutations did not affect NF-kappa B-mediated induction by tumor necrosis factor alpha.
Conclusions:
- AP-2 is a novel regulator of HIV-1 enhancer function.
- The interaction between AP-2 and NF-kappa B at the enhancer is mutually exclusive, influencing basal transcription.
- AP-2 binding site disruption affects basal HIV-1 expression but not inflammatory response-driven induction.