Feb 8, 2007

Cell stress modulates the function of splicing regulatory protein RBM4 in translation control

Proceedings of the National Academy of Sciences of the United States of America
Jung-Chun LinWoan-Yuh Tarn

Abstract

RNA-binding motif protein 4 (RBM4) plays a regulatory role in alternative splicing of precursor mRNA. We show here that cell stress such as arsenite exposure induces phosphorylation of RBM4 at serine 309 and also drives its cytoplasmic accumulation and targeting to stress granule via the MKK(3/6)-p38 signaling pathway. Accordingly, RBM4 suppresses cap-dependent translation in a cis-element-dependent manner. However, RBM4 concomitantly activates internal ribosome entry site (IRES)-mediated translation likely by promoting the association of translation initiation factor eIF4A with IRES-containing mRNAs. Overexpression of RBM4 therefore mimics the effect of cell stress-induced signaling on translation initiation control. Whereas arsenite treatment promotes RBM4 loading onto IRES mRNAs and enhances RBM4-eIF4A interactions, a nonphosphorylatable mutant of RBM4 was unresponsive to arsenite stress and failed to activate IRES-mediated translation. Thus, our results uncover a previously unrecognized paradigm for the RNA-binding protein RBM4 in its phosphorylation-modulated dual action as a suppressor of cap-dependent and enhancer of IRES-mediated translation in response to stress signals.

  • References33
  • Citations52

References

Mentioned in this Paper

Nested Transcripts
Biological Adaptation to Stress
Cytoplasmic mRNA Processing Body
Protein Phosphorylation
Signal Transduction Pathways
Arsenite
Protein Biosynthesis
Anatomic Site
EIF4A2 gene
RBM4 gene

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