Editors' ChoiceHEAT SHOCK

Linking HSF1 Activation to Translation

Science's STKE  28 Mar 2006:
Vol. 2006, Issue 328, pp. tw105
DOI: 10.1126/stke.3282006tw105

Cells can survive heat stress by increasing the abundance of heat shock proteins (HSPs) and other cytoprotective proteins to prevent toxicity from excess improperly folded proteins. In addition, heat shock inhibits translation and disrupts the cytoskeleton. The increased expression of HSPs is mediated by activation of the transcription factor HSF1, which is kept in inactive monomeric state in unstressed cells. Shamovsky et al. found that translation elongation factor eEF1a and a noncoding RNA that they called heat shock RNA-1 (HSR1) in cell lysates from heat-shocked cells bound to immobilized recombinant HSF1. When eluted from HSF1, this eEF1a-HSR1 complex activated HSF1 in vitro based on measurements of electrophoretic mobility shift, DNA binding activity, and trimerization of HSF1. Antisense oligonucleotides or short interfering RNA (siRNA) experiments with cultured cells demonstrated that HSR1 was crucial for the activation of HSF1 and stimulation of HSP72 synthesis (which is encoded by an HSF1 target gene) and that cells lacking HSR1 succumbed more quickly to lethal heat stress. These results demonstrate a role for a noncoding RNA in activation of gene expression during heat shock response and indicate that eEF1a represents a mechanism for connecting cessation of translation induced by heat with stimulation of the heat shock response.

I. Shamovsky, M. Ivannikov, E. S. Kandel, D. Gershon, E. Nudler, RNA-mediated response to heat shock in mammalian cells. Nature 440, 556-560 (2006). [PubMed]