Y14 Positively Regulates TNF-α–Induced NF-κB Transcriptional Activity via Interacting RIP1 and TRADD Beyond an Exon Junction Complex Protein

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.

High expression of RBM8A predicts poor patient prognosis and promotes tumor progression in hepatocellular carcinoma

“…Ras/MAPK, JAK/STAT3 and NF-κB signaling pathways are confirmed to be closely related to occurrence, development, invasion and metastasis of liver cancer (25)(26)(27). Loss of RBM8A led to changes of all these signaling pathways (23,(28)(29)(30): loss of RBM8A led to reduction of MAPK protein and inhibited Ras/MAPK signaling pathway which resulted in cell apoptosis; loss of RBM8A resulted in inhibition of JAK/ STAT3 signaling pathway and prohibited bindings between DNA and STAT3; loss of RBM8A also led to decrease of phosphorylation of TNF-α/STAT3 signaling pathway and reduced the effect of NF-κB. As a common factor of these three signaling pathways, RBM8A protein plays vital roles in inhibiting cell growth and apoptosis.…”

“…RBM8A is found highly expressed in malignant tumors such as primary liver cancer, pleural endotheliomas, multiple myeloma and other malignant tumors (3,11,12,(20)(21)(22)(23). Further analysis revealed that the function of RBM8A could be that the knockdown of RBM8A in lung adenocarcinoma resulted in cell cycle arrest in G2/M phase.…”

Prognostic value of increased expression of RBM8A in gastric cancer

“…RBM8A is an RNA recognition motif-containing protein that forms heterodimers with MAGOH and serves as a core factor of the RNA surveillance machinery for the exon junction complex. RBM8A is known to be a component of the exon junction complex, which could regulate IL-6-induced STAT3 activation in human cervix carcinoma cell line (17). RBM8A-deficient cells cannot enter the next G1 phase beyond G2/M phase after release from G1/S arrest (9).…”

Caspase‐dependent cleavage regulates protein levels of Epstein–Barr virus‐derived latent membrane protein 1

“…The synthesized FLAG‐tagged LMP1 4xANTD mutant was obtained from GenScript (Piscataway, NJ, USA). STAT3‐LUC and NF‐κB‐LUC were kindly provided by T. Hirano (Osaka University Medical School, Osaka, Japan) and T. Fujita (Kyoto University, Kyoto, Japan) . Anti‐FLAG antibody was purchased from Sigma‐Aldrich (St. Louis, MO, USA).…”