Y14 positively regulates TNF-α-induced NF-κB transcriptional activity via interacting RIP1 and TRADD beyond an exon junction complex protein

J Immunol. 2013 Aug 1;191(3):1436-44. doi: 10.4049/jimmunol.1300501. Epub 2013 Jul 1.

Abstract

Although Y14 is known to be a component of the exon junction complex, we previously reported that Y14 regulates IL-6-induced STAT3 activation. In this study, we showed that endogenous Y14 positively regulated TNF-α-induced IL-6 expression in HeLa cells. Small interfering RNA-mediated Y14-knockdown reduced TNF-α-induced and NF-κB-mediated transcriptional activity, phosphorylation/degradation of IκBα, and nuclear localization of NF-κB/p65. As in the case of IL-6 stimuli, Y14 enhanced TNF-α-induced STAT3 phosphorylation, which is important for its nuclear retention. However, our manipulation of Y14 expression indicated that it is involved in TNF-α-induced IL-6 expression via both STAT3-dependent and -independent mechanisms. We screened signaling molecules in the TNF-α-NF-κB pathway and found that Y14 endogenously associated with receptor-interacting protein 1 (RIP1) and TNFR-associated death domain (TRADD). Overexpression of RIP1, but not TRADD, restored TNF-α-induced NF-κB activation in Y14-knockdown cells, and Y14 overexpression restored TNF-α-induced NF-κB activation in TRADD-knockdown cells, but not in RIP1-knockdown cells, indicating that Y14 lies downstream of TRADD and upstream of RIP1. Of importance, Y14 significantly enhanced the binding between RIP1 and TRADD, and this is a possible new mechanism for Y14-mediated modification of TNF-α signals. Although Y14 associates with MAGOH in the exon junction complex, Y14's actions in the TNF-α-NF-κB pathway are unlikely to require MAGOH. Therefore, Y14 positively regulates signals for TNF-α-induced IL-6 production at multiple steps beyond an exon junction complex protein.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Line, Tumor
  • HEK293 Cells
  • HeLa Cells
  • Humans
  • I-kappa B Proteins / metabolism
  • Interleukin-6 / biosynthesis
  • Interleukin-6 / genetics
  • NF-KappaB Inhibitor alpha
  • NF-kappa B / genetics
  • NF-kappa B / metabolism*
  • Nuclear Pore Complex Proteins / genetics
  • Nuclear Pore Complex Proteins / metabolism*
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism
  • Phosphorylation
  • Promoter Regions, Genetic
  • RNA Interference
  • RNA, Small Interfering
  • RNA-Binding Proteins / genetics
  • RNA-Binding Proteins / metabolism*
  • STAT1 Transcription Factor
  • STAT3 Transcription Factor / genetics
  • STAT3 Transcription Factor / metabolism
  • TNF Receptor-Associated Death Domain Protein / genetics
  • TNF Receptor-Associated Death Domain Protein / metabolism*
  • TNF Receptor-Associated Factor 2 / genetics
  • Transcription Factor RelA / metabolism
  • Transcription, Genetic
  • Tumor Necrosis Factor-alpha / metabolism*

Substances

  • AGFG1 protein, human
  • I-kappa B Proteins
  • Interleukin-6
  • MAGOH protein, human
  • NF-kappa B
  • NFKBIA protein, human
  • Nuclear Pore Complex Proteins
  • Nuclear Proteins
  • RBM8A protein, human
  • RNA, Small Interfering
  • RNA-Binding Proteins
  • STAT1 Transcription Factor
  • STAT3 Transcription Factor
  • STAT3 protein, human
  • TNF Receptor-Associated Death Domain Protein
  • TNF Receptor-Associated Factor 2
  • Transcription Factor RelA
  • Tumor Necrosis Factor-alpha
  • NF-KappaB Inhibitor alpha