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AIMP2 (aminoacyl-tRNA synthetase interacting multifunctional protein 2; also known as JTV-1) was first identified as p38 in a macromolecular protein complex that consisted of nine different aminoacyl-tRNA synthetases and two other auxiliary factors. AIMP2 also plays pivotal roles in the regulation of cell proliferation and death. Although AIMP2 was previously shown to augment TNFα-induced cell death, its working mechanism in this signal pathway was not understood. Here, we investigate the functional significance and mode of action of AIMP2 in TNFα signaling. TNFα-induced cell death was compromised in AIMP2-deficient or -suppressed cells and exogenous supplementation of AIMP2 augmented apoptotic sensitivity to TNFα signaling. This activity was confirmed by the AIMP2-dependent increase of IκB and suppression of NFκB. We found binding of AIMP2 to TRAF2, a key player in the TNFα signaling pathway. AIMP2 augmented the association of an E3 ubiquitin ligase, c-IAP1, with TRAF2, causing ubiquitin-dependent degradation of TRAF2. These findings suggest that AIMP2 can mediate the pro-apoptotic activity of TNFα via the downregulation of TRAF2 expression.


  • This work was supported by the grants of Acceleration Research of KOSEF (2009-0063498), the 21st Frontier Functional Proteomics Research (FPR0881-250) and R31-2008-000-10103-0 from the WCU project of the MEST and the KOSEF.

  • Accepted April 28, 2009.
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