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Mol Immunol. 1998 Dec;35(18):1171-8.

HIV Tat represses transcription of the beta 2-microglobulin promoter.

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  • 1Molecular Regulation Section, Experimental Immunology Branch, National Cancer Institute, NIH, Bethesda, MD 20892, USA.


The MHC class I complex, which binds and presents peptide antigen, is composed of a class I heavy chain and the beta2-microglobulin light chain. HIV-1, which induces a profound immunodeficiency in infected individuals, encodes proteins that cause decreased expression of class I heavy chain. We now report that the HIV Tat protein, which is a potent transactivator of viral transcription, is also a potent repressor of the beta2-microglobulin gene. Repression is mediated through the basal promoter of the beta2-microglobulin gene, which is shown to be predominantly regulated by an initiator element. Tat repression is further augmented by the short viral transcript, TAR, which interacts with Tat. Tat-mediated repression of beta2-microglobulin expression, together with its known repression of class I gene transcription, provides an effective mechanism by which HIV could prevent cell surface expression of the MHC class I complex and avoid immune surveillance.

[PubMed - indexed for MEDLINE]
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