SP600125 Inhibits Cap-dependent Translation Independently of the c-Jun N-terminal Kinase Pathway

Masatoshi Ito, Hiroshi Kitamura, Chisato Kikuguchi, Koji Hase, Hiroshi Ohno, Osamu Ohara
2011 Cell Structure and Function  
We investigated the effects of SP600125 (formerly called c-Jun N-terminal kinase (JNK) inhibitor II) on translation using cultured mouse cells. SP600125 (50 µM) treatment rapidly repressed overall protein synthesis, accompanied by a reduction in the mRNAs for housekeeping genes such as glyceraldehyde-3-phosphate dehydrogenase in the polysomal fraction. SP600125 decreased polysomes with a concomitant increase in free ribosomal subunits in the cytoplasm, suggesting that global translation was
more » ... translation was inhibited at the initiation step. A reporter analysis using exogenous mRNAs showed that SP600125 inhibited cap-dependent but not internal ribosome entry site-dependent translation. SP600125 significantly attenuated phosphorylation of components in the mTOR pathway, which is responsible for cap-dependent translation. In contrast to SP600125, short hairpin RNAs for JNK1 and JNK2 failed to affect overall protein synthesis. Collectively, SP600125 inhibits cap-dependent translation, independent of the JNK pathway.
doi:10.1247/csf.10025 pmid:21263197 fatcat:y6eb3w6t4va3rhrjk3zqwgxcie