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J Virol. 2007 Dec;81(24):13735-42. Epub 2007 Oct 17.

The human T-cell leukemia virus type 1 Tax oncoprotein requires the ubiquitin-conjugating enzyme Ubc13 for NF-kappaB activation.

Author information

  • 1Department of Microbiology and Immunology, Sylvester Comprehensive Cancer Center, the University of Miami, Miller School of Medicine, 1550 NW 10 Avenue, Miami, FL 33136, USA.

Abstract

Ubiquitination of the human T-cell leukemia virus 1 Tax oncoprotein provides an important regulatory mechanism that promotes the Tax-mediated activation of NF-kappaB. However, the type of polyubiquitin chain linkages and the host factors that are required for Tax ubiquitination have not been identified. Here, we demonstrate that Tax polyubiquitin chains are composed predominantly of lysine 63-linked chains. Furthermore, the ubiquitination of Tax is critically dependent on the E2 ubiquitin-conjugating enzyme Ubc13. Tax interacts with Ubc13, and small interfering RNA-mediated knockdown of Ubc13 expression abrogates Tax ubiquitination and the activation of NF-kappaB. Mouse fibroblasts lacking Ubc13 exhibit impaired Tax activation of NF-kappaB despite normal tumor necrosis factor- and interleukin-1-mediated NF-kappaB activation. Finally, the interaction of Tax with NEMO is disrupted in the absence of Tax ubiquitination and Ubc13 expression, suggesting that Tax ubiquitination is critical for NEMO binding. Collectively, our results reveal that Ubc13 is essential for Tax ubiquitination, its interaction with NEMO, and Tax-mediated NF-kappaB activation.

PMID:
17942533
[PubMed - indexed for MEDLINE]
PMCID:
PMC2168884
Free PMC Article

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