Human immunodeficiency virus type 1 Tat protein inhibits the SIRT1 deacetylase and induces T cell hyperactivation.

Gladstone Institute of Virology and Immunology, University of California, San Francisco, CA 94158, USA.
Cell host & microbe (Impact Factor: 13.02). 04/2008; 3(3):158-67. DOI: 10.1016/j.chom.2008.02.002
Source: PubMed

ABSTRACT Symptoms of T cell hyperactivation shape the course and outcome of HIV-1 infection, but the mechanism(s) underlying this chronic immune activation are not well understood. We find that the viral transactivator Tat promotes hyperactivation of T cells by blocking the nicotinamide adenine dinucleotide (NAD(+))-dependent deacetylase SIRT1. Tat directly interacts with the deacetylase domain of SIRT1 and blocks the ability of SIRT1 to deacetylate lysine 310 in the p65 subunit of NF-kappaB. Because acetylated p65 is more active as a transcription factor, Tat hyperactivates the expression of NF-kappaB-responsive genes, a function lost in SIRT1-/- cells. These results support a model where the normal function of SIRT1 as a negative regulator of T cell activation is suppressed by Tat during HIV infection. These events likely contribute to the state of immune cell hyperactivation found in HIV-infected individuals.

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