Heat-shock protein HSP101 affects the release of ribosomal protein mRNAs for recovery after heat shock

Heat shock (HS) is known to have a profound impact on gene expression at different levels, such as inhibition of protein synthesis, in which HS blocks translation initiation and induces the sequestration of mRNAs into stress granules (SGs) for temporary storage. SGs prevent the degradation of the stored mRNAs, which can be re-engaged into translation in the recovery period. However, little is known on the mRNAs stored during the stress, how these mRNAs are released from SGs afterward, and what is the functional importance of this process. In this work, we report that in Arabidopsis the knockout mutant of the molecular chaperon HEAT SHOCK PROTEIN101 (HSP101) presented a defect in translation recovery and SG dissociation after HS. Using RNA sequencing and RNA immunoprecipitation approaches, we show that mRNAs encoding ribosomal proteins (RPs) were preferentially stored during HS and that these mRNAs were released and translated in an HSP101-dependent manner during recovery. By isotope incorporation and polysome profile analyses, we observed that these released mRNAs contributed to the production of new ribosomes to enhance translation. We propose that, after HS, HSP101 is required for the efficient release of RP mRNAs from SGs resulting in a rapid restoration of the translation machinery by producing new RPs.


Co-researchers:Rémy Merret, Marie-Christine Carpenier, Jean-Jacques Favory, Claire Picart, Julie Descombin, Cecile Bousquet-Antonelli, Pascal Tillard, Laurence Lejay, Jean-Marc Deragon, Yee-yung Charng