Heat shock and ethanol stress provoke distinctly different responses in 3′-processing and nuclear export of HSP mRNA in Saccharomyces cerevisiae

Abstract

Under conditions of heat shock at 42 degrees C, mRNAs of HSP (heat shock protein) genes are exported out of the nucleus, whereas bulk poly(A)(+) (polyadenylated) mRNA shows a nuclear accumulation in Saccharomyces cerevisiae. Such a selective mRNA export seems an efficacious strategy of yeast cells to adapt rapidly to stress. Although ethanol stress (10%, v/v) as well as heat shock blocks the export of bulk poly(A)(+) mRNA, the differences and/or similarity between heat shock and ethanol stress in the mechanisms of selective mRNA export still remain to be clarified. We found that ethanol stress induced transcriptional activation of a subset of yeast HSP genes; however, intriguingly, most such transcripts remained in the nucleus in a hyperadenylated state and, as a consequence, were not translated into HSPs. Elimination of ethanol resulted in a rapid shortening of the poly(A) tails of HSP mRNAs, loss of their nuclear retention, and the coincidental synthesis of the respective HSPs. Since HSP mRNAs are selectively exported from the nucleus in heat-shocked cells, yeast cells respond differently to ethanol stress and heat shock in the 3'-processing and transport of HSP mRNAs. Furthermore, these results also suggest that hyperadenylation and nuclear retention of mRNAs might be used as a means to control eukaryotic gene expression under stressed conditions.

Transcriptome analysis of differential responses of diploid and haploid yeast to ethanol stress

“…Although transcription of genes related to transcription and translation was upregulated, cell density was not enhanced in the presence of ethanol, which might be partly explained by the inhibition of mRNA processing and retaining the export of mRNA out of nucleus for translation (Izawa et al, 2008). The strains used here were the strain with tolerance to ethanol and its derivatives, and the results were consistent with the previous observation that genes related to ribosome proteins were upregulated in the presence of 10% ethanol in ethanol tolerant strain (Dinh et al, 2009).…”

Genetic and environmental changes in SUMO homeostasis lead to nuclear mRNA retention in plants

“…A correlation between altered SUMO homeostasis and mRNA nuclear retention during heat and ethanol stress In heat-shocked and ethanol-stressed yeast cells, mRNA accumulates in the nucleus (Rollenhagen et al 2004;Izawa et al 2008). In plants, the eVects of heat stress and ethanol stress on mRNA transport has not been investigated.…”

Prioritized Expression of BTN2 of Saccharomyces cerevisiae under Pronounced Translation Repression Induced by Severe Ethanol Stress

“…Similarly, some factor(s) that promote efficient translation under severe stress might be recruited to HSEs in yeast cells. However, presence of HSEs in promoter regions may not be sufficient for inducing effective translation under severe ethanol stress, unlike that observed during glucose deprivation, because translation of HSE-containing genes such as HSP30 and HSP82 is negligible under severe ethanol stress despite of their transcription ( Figure 1 ) (Izawa et al, 2008). Mechanisms underlying preferential translation under severe ethanol stress might be different from those underlying preferential translation under glucose deprivation.…”