scholarly journals Transient intracellular acidification regulates the core transcriptional heat shock response

2018 ◽  
Author(s):  
Catherine G. Triandafillou ◽  
Christopher D. Katanski ◽  
Aaron R. Dinner ◽  
D. Allan Drummond

AbstractHeat shock induces a conserved transcriptional program regulated by heat shock factor 1 (Hsf1) in eukaryotic cells. Activation of this heat-shock response is triggered by heat-induced misfolding of newly synthesized polypeptides, and so has been thought to depend on ongoing protein synthesis. Here, using the the budding yeastSaccharomyces cerevisiae, we report the discovery that Hsf1 can be robustly activated when protein synthesis is inhibited, so long as cells undergo cytosolic acidification. Heat shock has long been known to cause transient intracellular acidification which, for reasons which have remained unclear, is associated with increased stress resistance in eukaryotes. We demonstrate that acidification is required for heat shock response induction in translationally inhibited cells, and specifically affects Hsf1 activation. Physiological heat-triggered acidification also increases population fitness and promotes cell cycle reentry following heat shock. Our results uncover a previously unknown adaptive dimension of the well-studied eukaryotic heat shock response.

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Catherine G Triandafillou ◽  
Christopher D Katanski ◽  
Aaron R Dinner ◽  
D Allan Drummond

Heat shock induces a conserved transcriptional program regulated by heat shock factor 1 (Hsf1) in eukaryotic cells. Activation of this heat shock response is triggered by heat-induced misfolding of newly synthesized polypeptides, and so has been thought to depend on ongoing protein synthesis. Here, using the budding yeast Saccharomyces cerevisiae, we report the discovery that Hsf1 can be robustly activated when protein synthesis is inhibited, so long as cells undergo cytosolic acidification. Heat shock has long been known to cause transient intracellular acidification which, for reasons which have remained unclear, is associated with increased stress resistance in eukaryotes. We demonstrate that acidification is required for heat shock response induction in translationally inhibited cells, and specifically affects Hsf1 activation. Physiological heat-triggered acidification also increases population fitness and promotes cell cycle reentry following heat shock. Our results uncover a previously unknown adaptive dimension of the well-studied eukaryotic heat shock response.


Author(s):  
Catherine G. Triandafillou ◽  
Christopher D. Katanski ◽  
Aaron R. Dinner ◽  
D. Allan Drummond

Author(s):  
Rena Onoguchi-Mizutani ◽  
Yoshihiro Kishi ◽  
Yoko Ogura ◽  
Yuuki Nishimura ◽  
Naoto Imamachi ◽  
...  

Abstract The heat-shock response is a crucial system for survival of organisms under heat stress. During heat-shock stress, gene expression is globally suppressed, but expression of some genes, such as chaperone genes, is selectively promoted. These selectively activated genes have critical roles in the heat-shock response, so it is necessary to discover heat-inducible genes to reveal the overall heat-shock response picture. The expression profiling of heat-inducible protein-coding genes has been well-studied, but that of non-coding genes remains unclear in mammalian systems. Here, we used RNA-seq analysis of heat shock-treated A549 cells to identify seven novel long non-coding RNAs that responded to heat shock. We focussed on CTD-2377D24.6 RNA, which is most significantly induced by heat shock, and found that the promoter region of CTD-2377D24.6 contains the binding site for transcription factor HSF1 (heat shock factor 1), which plays a central role in the heat-shock response. We confirmed that HSF1 knockdown cancelled the induction of CTD-2377D24.6 RNA upon heat shock. These results suggest that CTD-2377D24.6 RNA is a novel heat shock-inducible transcript that is transcribed by HSF1.


1988 ◽  
Vol 90 (1) ◽  
pp. 51-58 ◽  
Author(s):  
A. Muller-Taubenberger ◽  
J. Hagmann ◽  
A. Noegel ◽  
G. Gerisch

Ubiquitin is a highly conserved, multifunctional protein, which is implicated in the heat-shock response of eukaryotes. The differential expression of the multiple ubiquitin genes in Dictyostelium discoideum was investigated under various stress conditions. Growing D. discoideum cells express four major ubiquitin transcripts of sizes varying from 0.6 to 1.9 kb. Upon heat shock three additional ubiquitin mRNAs of 0.9, 1.2 and 1.4 kb accumulate within 30 min. The same three transcripts are expressed in response to cold shock or cadmium treatment. Inhibition of protein synthesis by cycloheximide leads to a particularly strong accumulation of the larger ubiquitin transcripts, which code for polyubiquitins. Possible mechanisms regulating the expression of ubiquitin transcripts upon heat shock and other stresses are discussed.


2002 ◽  
Vol 205 (20) ◽  
pp. 3231-3240 ◽  
Author(s):  
Bradley A. Buckley ◽  
Gretchen E. Hofmann

SUMMARYThe intracellular build-up of thermally damaged proteins following exposure to heat stress results in the synthesis of a family of evolutionarily conserved proteins called heat shock proteins (Hsps) that act as molecular chaperones, protecting the cell against the aggregation of denatured proteins. The transcriptional regulation of heat shock genes by heat shock factor 1(HSF1) has been extensively studied in model systems, but little research has focused on the role HSF1 plays in Hsp gene expression in eurythermal organisms from broadly fluctuating thermal environments. The threshold temperature for Hsp induction in these organisms shifts with the recent thermal history of the individual but the mechanism by which this plasticity in Hsp induction temperature is achieved is unknown. We examined the effect of thermal acclimation on the heat-activation of HSF1 in the eurythermal teleost Gillichthys mirabilis. After a 5-week acclimation period (at 13, 21 or 28°C) the temperature of HSF1 activation was positively correlated with acclimation temperature. HSF1 activation peaked at 27°C in fish acclimated to 13°C, at 33°C in the 21°C group, and at 36°C in the 28°C group. Concentrations of both HSF1 and Hsp70 in the 28°C group were significantly higher than in the colder acclimated fish. Plasticity in HSF1 activation may be important to the adjustable nature of the heat shock response in eurythermal organisms and the environmental control of Hsp gene expression.


2000 ◽  
Vol 13 (4) ◽  
pp. 297-302 ◽  
Author(s):  
Ziya Akçetin ◽  
Reinhard Pregla ◽  
Dorothea Darmer ◽  
Hans-Jürgen Brömme ◽  
Jürgen Holtz

2000 ◽  
Vol 203 (15) ◽  
pp. 2331-2339 ◽  
Author(s):  
G.E. Hofmann ◽  
B.A. Buckley ◽  
S. Airaksinen ◽  
J.E. Keen ◽  
G.N. Somero

The heat-shock response, the enhanced expression of one or more classes of molecular chaperones termed heat-shock proteins (hsps) in response to stress induced by high temperatures, is commonly viewed as a ‘universal’ characteristic of organisms. We examined the occurrence of the heat-shock response in a highly cold-adapted, stenothermal Antarctic teleost fish, Trematomus bernacchii, to determine whether this response has persisted in a lineage that has encountered very low and stable temperatures for at least the past 14–25 million years. The patterns of protein synthesis observed in in vivo metabolic labelling experiments that involved injection of (35)S-labelled methionine and cysteine into whole fish previously subjected to a heat stress of 10 degrees C yielded no evidence for synthesis of any size class of heat-shock protein. Parallel in vivo labelling experiments with isolated hepatocytes similarly showed significant amounts of protein synthesis, but no indication of enhanced expression of any class of hsp. The heavy metal cadmium, which is known to induce synthesis of hsps, also failed to alter the pattern of proteins synthesized in hepatocytes. Although stress-induced chaperones could not be detected under any of the experimental condition used, solid-phase antibody (western) analysis revealed that a constitutively expressed 70 kDa chaperone was present in this species, as predicted on the basis of requirements for chaperoning during protein synthesis. Amounts of the constitutively expressed 70 kDa chaperone increased in brain, but not in gill, during 22 days of acclimation to 5 degrees C. The apparent absence of a heat-shock response in this highly stenothermal species is interpreted as an indication that a physiological capacity observed in almost all other organisms has been lost as a result of the absence of positive selection during evolution at stable sub-zero temperatures. Whether the loss of the heat-shock response is due to dysfunctional genes for inducible hsps (loss of open reading frames or functional regulatory regions), unstable messenger RNAs, the absence of a functional heat-shock factor or some other lesion remains to be determined.


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