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J Mol Endocrinol. 2007 Jun;38(6):587-601.

Activation of the human immunodeficiency virus type I long terminal repeat by 1 alpha,25-dihydroxyvitamin D3.

Author information

1
Instituto de Investigaciones Biomédicas--Universidad Autónoma de Madrid, Madrid, Spain.

Abstract

The genetic predisposition of the host and the virus is the most important determinant for prediction of the course of human immunodeficiency virus type I (HIV-1) viral infection and acquired immune deficiency syndrome (AIDS) progression. Transcription from the HIV-1 long terminal repeat (LTR) is a crucial step for viral replication. Here, we describe a stimulatory role of the vitamin D receptor (VDR) on HIV-1 LTR transactivation. Transient transfections reveal that VDR activates the LTR in HeLa, U937, and Cos-1 cells in a ligand-dependent manner. 1alpha,25-Dihydroxyvitamin D3 (vitD3) promotes activation of a minimal LTR construct (from nucleotides -35 to +89), lacking a previously described hormone response element that binds several nuclear receptors. NF-kappaB (nuclear factor-kappa B) and Sp1-binding sites, which are responsible for most basal LTR activity in HeLa cells, are also dispensable for vitD3-dependent HIV-1 transcription. Although the tat response element element is not required for VDR-mediated HIV-1 gene expression, the viral protein Tat acts in a synergistic manner with the receptor to stimulate LTR activity. Furthermore, our data also show cooperation of the receptor with various cellular coactivators for HIV-1 transactivation by vitD3. Paradoxically, mutations in the VDR ligand-dependent transcriptional activation function-2 that abrogate vitD3-dependent stimulation through classical vitamin D response elements, do not reduce vitD3-mediated LTR transactivation. Furthermore, point mutations in the DNA-binding domain that abolish receptor binding to consensus DNA sequences do not affect ligand-dependent HIV-1 stimulation. These results show that VDR activates the HIV-1 LTR through different mechanisms, including non-classical nuclear receptor transcriptional actions that may ensure viral transcription under different physiological scenarios.

PMID:
17556530
DOI:
10.1677/JME-06-0065
[Indexed for MEDLINE]

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