HTLV-1 Tax Stabilizes MCL-1 via TRAF6-Dependent K63-Linked Polyubiquitination to Promote Cell Survival and Transformation

Young Bong Choi, Edward William Harhaj

Research output: Contribution to journalArticlepeer-review

Abstract

The human T-cell leukemia virus type 1 (HTLV-1) Tax protein hijacks the host ubiquitin machinery to activate IκB kinases (IKKs) and NF-κB and promote cell survival; however, the key ubiquitinated factors downstream of Tax involved in cell transformation are unknown. Using mass spectrometry, we undertook an unbiased proteome-wide quantitative survey of cellular proteins modified by ubiquitin in the presence of Tax or a Tax mutant impaired in IKK activation. Tax induced the ubiquitination of 22 cellular proteins, including the anti-apoptotic BCL-2 family member MCL-1, in an IKK-dependent manner. Tax was found to promote the nondegradative lysine 63 (K63)-linked polyubiquitination of MCL-1 that was dependent on the E3 ubiquitin ligase TRAF6 and the IKK complex. Tax interacted with and activated TRAF6, and triggered its mitochondrial localization, where it conjugated four carboxyl-terminal lysine residues of MCL-1 with K63-linked polyubiquitin chains, which stabilized and protected MCL-1 from genotoxic stress-induced degradation. TRAF6 and MCL-1 played essential roles in the survival of HTLV-1 transformed cells and the immortalization of primary T cells by HTLV-1. Therefore, K63-linked polyubiquitination represents a novel regulatory mechanism controlling MCL-1 stability that has been usurped by a viral oncogene to precipitate cell survival and transformation.

Original languageEnglish (US)
JournalPLoS pathogens
Volume10
Issue number10
DOIs
StatePublished - Oct 1 2014

ASJC Scopus subject areas

  • Parasitology
  • Microbiology
  • Immunology
  • Molecular Biology
  • Genetics
  • Virology

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