scholarly journals Down-Regulation of Yeast Helicase Ded1 by Glucose Starvation or Heat-Shock Differentially Impairs Translation of Ded1-Dependent mRNAs

2021 ◽  
Vol 9 (12) ◽  
pp. 2413
Author(s):  
Neelam Dabas Sen ◽  
Hongen Zhang ◽  
Alan G. Hinnebusch
Keyword(s):  
Heat Shock ◽  
Initiation Factor ◽  
Glucose Starvation ◽  
Down Regulation ◽  
Mrna Targets ◽  
Dead Box ◽  
Select Group ◽  
Mrna Granules ◽  
Stressed Cells ◽  
Mutant Cells

Ded1 is an essential DEAD-box helicase in yeast that broadly stimulates translation initiation and is critical for mRNAs with structured 5′UTRs. Recent evidence suggests that the condensation of Ded1 in mRNA granules down-regulates Ded1 function during heat-shock and glucose starvation. We examined this hypothesis by determining the overlap between mRNAs whose relative translational efficiencies (TEs), as determined by ribosomal profiling, were diminished in either stressed WT cells or in ded1 mutants examined in non-stress conditions. Only subsets of the Ded1-hyperdependent mRNAs identified in ded1 mutant cells exhibited strong TE reductions in glucose-starved or heat-shocked WT cells, and those down-regulated by glucose starvation also exhibited hyper-dependence on initiation factor eIF4B, and to a lesser extent eIF4A, for efficient translation in non-stressed cells. These findings are consistent with recent proposals that the dissociation of Ded1 from mRNA 5′UTRs and the condensation of Ded1 contribute to reduced Ded1 function during stress, and they further suggest that the down-regulation of eIF4B and eIF4A functions also contributes to the translational impairment of a select group of Ded1 mRNA targets with heightened dependence on all three factors during glucose starvation.

scholarly journals The DEAD-box RNA helicase Ded1 has a role in the translational response to TORC1 inhibition

2019 ◽  
Vol 30 (17) ◽  
pp. 2171-2184 ◽  
Author(s):  
Peyman P. Aryanpur ◽  
David M. Renner ◽  
Emily Rodela ◽  
Telsa M. Mittelmeier ◽  
Aaron Byrd ◽  
...  
Keyword(s):  
Translation Initiation ◽  
Rna Helicase ◽  
Initiation Factor ◽  
Untranslated Regions ◽  
Eukaryotic Initiation Factor ◽  
Functional Requirements ◽  
Dead Box ◽  
Eif4f Complex ◽  
Mrna Pool ◽  
Mutant Cells

Ded1 is a DEAD-box RNA helicase with essential roles in translation initiation. It binds to the eukaryotic initiation factor 4F (eIF4F) complex and promotes 48S preinitiation complex assembly and start-site scanning of 5′ untranslated regions of mRNAs. Most prior studies of Ded1 cellular function were conducted in steady-state conditions during nutrient-rich growth. In this work, however, we examine its role in the translational response during target of rapamycin (TOR)C1 inhibition and identify a novel function of Ded1 as a translation repressor. We show that C-terminal mutants of DED1 are defective in down-regulating translation following TORC1 inhibition using rapamycin. Furthermore, following TORC1 inhibition, eIF4G1 normally dissociates from translation complexes and is degraded, and this process is attenuated in mutant cells. Mapping of the functional requirements for Ded1 in this translational response indicates that Ded1 enzymatic activity and interaction with eIF4G1 are required, while homo-oligomerization may be dispensable. Our results are consistent with a model wherein Ded1 stalls translation and specifically removes eIF4G1 from translation preinitiation complexes, thus removing eIF4G1 from the translating mRNA pool and leading to the codegradation of both proteins. Shared features among DED1 orthologues suggest that this role is conserved and may be implicated in pathologies such as oncogenesis.

scholarly journals Crystal structure of yeast initiation factor 4A, a DEAD-box RNA helicase

2000 ◽  
Vol 97 (24) ◽  
pp. 13080-13085 ◽  
Author(s):  
J. M. Caruthers ◽  
E. R. Johnson ◽  
D. B. McKay
Keyword(s):  
Crystal Structure ◽  
Rna Helicase ◽  
Initiation Factor ◽  
Dead Box

scholarly journals In vivo growth of a murine lymphoma cell line alters regulation of expression of HSP72.

1995 ◽  
Vol 15 (2) ◽  
pp. 1071-1078 ◽  
Author(s):  
S Davidson ◽  
P Høj ◽  
T Gabriele ◽  
R L Anderson
Keyword(s):  
Heat Shock ◽  
Cell Line ◽  
B Cell Lymphoma ◽  
Lymphoma Cell ◽  
Lymphoma Cell Line ◽  
Regulation Of Expression ◽  
Heat Shock Element ◽  
Stressed Cells

We have identified a murine B-cell lymphoma cell line, CH1, that has a much-diminished capacity to express increased levels of heat shock proteins in response to heat stress in vitro. In particular, these cells cannot synthesize the inducible 72-kDa heat shock protein (HSP72) which is normally expressed at high levels in stressed cells. We show here that CH1 fails to transcribe HSP72 mRNA after heat shock, even though the heat shock transcription factor, HSF, is activated correctly. After heat shock, HSF from CH1 is found in the nucleus and is phosphorylated, trimerized, and capable of binding the heat shock element. We propose that additional signals which CH1 cells are unable to transduce are normally required to activate hsp72 transcription in vitro. Surprisingly, we have found that when the CH1 cells are heated in situ in a mouse, they show normal expression of HSP72 mRNA and protein. Therefore, CH1 cells have a functional hsp72 gene which can be transcribed and translated when the cells are in an appropriate environment. A diffusible factor present in ascites fluid is capable of restoring normal HSP72 induction in CH1 cells. We conclude that as-yet-undefined factors are required for regulation of the hsp72 gene or, alternatively, that heat shock in vivo causes activation of hsp70 through a novel pathway which the defect in CH1 has exposed and which is distinct from that operating in vitro. This unique system offers an opportunity to study a physiologically relevant pathway of heat shock induction and to biochemically define effectors involved in the mammalian stress response.

scholarly journals Molecular chaperones and heat shock proteins in atherosclerosis

2012 ◽  
Vol 302 (3) ◽  
pp. H506-H514 ◽  
Author(s):  
Qingbo Xu ◽  
Bernhard Metzler ◽  
Marjan Jahangiri ◽  
Kaushik Mandal
Keyword(s):  
Heat Shock ◽  
Heat Shock Proteins ◽  
Molecular Chaperones ◽  
Mammalian Cells ◽  
Vessel Wall ◽  
Protective Role ◽  
Research Field ◽  
Stressed Cells ◽  
Shock Proteins ◽  
Prevention Of Atherosclerosis

In response to stress stimuli, mammalian cells activate an ancient signaling pathway leading to the transient expression of heat shock proteins (HSPs). HSPs are a family of proteins serving as molecular chaperones that prevent the formation of nonspecific protein aggregates and assist proteins in the acquisition of their native structures. Physiologically, HSPs play a protective role in the homeostasis of the vessel wall but have an impact on immunoinflammatory processes in pathological conditions involved in the development of atherosclerosis. For instance, some members of HSPs have been shown to have immunoregulatory properties and modification of innate and adaptive response to HSPs, and can protect the vessel wall from the disease. On the other hand, a high degree of sequence homology between microbial and mammalian HSPs, due to evolutionary conservation, carries a risk of misdirected autoimmunity against HSPs expressed on the stressed cells of vascular endothelium. Furthermore, HSPs and anti-HSP antibodies have been shown to elicit production of proinflammatory cytokines. Potential therapeutic use of HSP in prevention of atherosclerosis involves achieving optimal balance between protective and immunogenic effects of HSPs and in the progress of research on vaccination. In this review, we update the progress of studies on HSPs and the integrity of the vessel wall, discuss the mechanism by which HSPs exert their role in the disease development, and highlight the potential clinic translation in the research field.

scholarly journals dE2F2-Independent Rescue of Proliferation in Cells Lacking an Activator dE2F1

2007 ◽  
Vol 27 (24) ◽  
pp. 8561-8570 ◽  
Author(s):  
Aaron M. Ambrus ◽  
Brandon N. Nicolay ◽  
Vanya I. Rasheva ◽  
Richard J. Suckling ◽  
Maxim V. Frolov
Keyword(s):  
Cell Cycle ◽  
Morphogenetic Furrow ◽  
Independent Manner ◽  
Dead Box ◽  
Cycle Arrest ◽  
Eye Disc ◽  
Severe Reduction ◽  
Functional Inactivation ◽  
Mutant Cells ◽  
Dependent Mechanism

ABSTRACT In Drosophila melanogaster, the loss of activator de2f1 leads to a severe reduction in cell proliferation and repression of E2F targets. To date, the only known way to rescue the proliferation block in de2f1 mutants was through the inactivation of dE2F2. This suggests that dE2F2 provides a major contribution to the de2f1 mutant phenotype. Here, we report that in mosaic animals, in addition to de2f2, the loss of a DEAD box protein Belle (Bel) also rescues proliferation of de2f1 mutant cells. Surprisingly, the rescue occurs in a dE2F2-independent manner since the loss of Bel does not relieve dE2F2-mediated repression. In the eye disc, bel mutant cells fail to undergo a G1 arrest in the morphogenetic furrow, delay photoreceptor recruitment and differentiation, and show a reduction of the transcription factor Ci155. The down-regulation of Ci155 is important since it is sufficient to partially rescue proliferation of de2f1 mutant cells. Thus, mutation of bel relieves the dE2F2-mediated cell cycle arrest in de2f1 mutant cells through a novel Ci155-dependent mechanism without functional inactivation of the dE2F2 repressor.

scholarly journals HSFs drive stress type-specific transcription of genes and enhancers

2021 ◽  
Author(s):  
Samu V Himanen ◽  
Mikael C Puustinen ◽  
Alejandro J Da Silva ◽  
Anniina Vihervaara ◽  
Lea Sistonen
Keyword(s):  
Oxidative Stress ◽  
Heat Shock ◽  
Rna Polymerase Ii ◽  
Molecular Mechanisms ◽  
Gene Promoters ◽  
Heat Shock Factors ◽  
Pol Ii ◽  
Bona Fide ◽  
Stressed Cells ◽  
First Time

Reprogramming of transcription is critical for the survival under cellular stress. Heat shock has provided an excellent model to investigate nascent transcription in stressed cells, but the molecular mechanisms orchestrating RNA synthesis during other types of stress are unknown. We utilized PRO-seq and ChIP-seq to study how Heat Shock Factors, HSF1 and HSF2, coordinate transcription at genes and enhancers upon oxidative stress and heat shock. We show that pause-release of RNA polymerase II (Pol II) is a universal mechanism regulating gene transcription in stressed cells, while enhancers are activated at the level of Pol II recruitment. Moreover, besides functioning as conventional promoter-binding transcription factors, HSF1 and HSF2 bind to stress-induced enhancers to trigger Pol II pause-release from poised gene promoters. Importantly, HSFs act at distinct genes and enhancers in a stress type-specific manner. HSF1 binds to many chaperone genes upon oxidative and heat stress but activates them only in heat-shocked cells. Under oxidative stress, HSF1 and HSF2 trans-activate genes independently of each other, demonstrating, for the first time, that HSF2 is a bona fide transcription factor. Taken together, we show that HSFs function as multi-stress-responsive factors that activate specific genes and enhancers when encountering changes in temperature and redox state.

Effect of heat shock on ribosome structure: appearance of a new ribosome-associated protein

1986 ◽  
Vol 6 (7) ◽  
pp. 2527-2535
Author(s):  
T W McMullin ◽  
R L Hallberg
Keyword(s):  
Heat Shock ◽  
Heat Shock Protein ◽  
Ribosomal Proteins ◽  
Tetrahymena Thermophila ◽  
Small Subunit ◽  
Stoichiometric Ratio ◽  
Two Dimensional ◽  
Hyperthermic Treatment ◽  
Stressed Cells ◽  
Ribosome Association

After a nonlethal but heat shock protein-inducing hyperthermic treatment, ribosomes isolated from Tetrahymena thermophila contained an additional 22-kilodalton protein (p22). When maximally ribosome associated, this protein was found to be on the small subunit in a 1:1 stoichiometric ratio with other ribosomal proteins. Using an antiserum directed against the purified 22-kilodalton protein, we found that non-heat-shocked and heat-shocked cells contain identical amounts of this protein, the only difference being that in the stressed cells p22 is entirely ribosome bound, whereas in the unstressed cells p22 has little or no detectable ribosome association. Because the two-dimensional electrophoretic properties of p22 showed no alterations after heat shock, this change in state of ribosome-p22 interaction does not appear to be caused by a chemical modification of p22. When not strongly ribosome associated, p22 is not found free in the cytoplasm. During that time in heat shock when p22 is first becoming ribosome associated, it is found preferentially on polysomal ribosomes. Subsequently, all ribosomes, whether polysome bound or not, obtain a bound p22. The functional significance of this association is discussed.

scholarly journals P0015SIRT2 REGULATES CISPLATIN-INDUCED ENDOPLASMIC RETICULUM STRESS THROUGH HEAT SHOCK FACTOR 1 DEACETYLATION

2020 ◽  
Vol 35 (Supplement_3) ◽  
Author(s):  
Woong Park ◽  
Hyeongwan Kim ◽  
Yujin Jung ◽  
Kyung Pyo Kang ◽  
Won Kim
Keyword(s):  
Endoplasmic Reticulum ◽  
Heat Shock ◽  
Er Stress ◽  
Knockout Mice ◽  
Malignant Tumors ◽  
Heat Shock Factor ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
Heat Shock Factor 1 ◽  
Caspase 12

Abstract Background and Aims Nephrotoxicity is an important cisplatin-induced adverse reaction and restricts the use of cisplatin to treat malignant tumors. Endoplasmic reticulum (ER) stress is caused by the accumulation of misfolded proteins, and is induced by cisplatin in kidneys. SIRT2 nicotinamide adenine dinucleotide (NAD+)-dependent deacetylase is a member of the sirtuin family, but its role in cisplatin-induced ER stress remains unclear. Method To investigate the effect of SIRT2 on cisplatin-induced ER stress using SIRT2 knockout mice and human proximal tubular epithelial cells (HK-2 cells). We treated cisplatin (20 µg/mL) or induced by intraperitoneal injection of cisplatin (20 mg/kg) and evaluated the changes of ER stress and its signal mechanism. Results Cisplatin administration was found to significantly increase the expressions of PRKR-like ER kinase (PERK), phosphorylation of eukaryotic translation initiation factor 2α (eIF2α), and the C/EBP homologous protein (CHOP) and caspase-12 in the kidneys of SIRT2-wild type mice. However, cisplatin-induced increases in the expressions of p-PERK, p-eIF2α, CHOP and, caspase-12 were diminished in kidneys of SIRT2 knockout mice. In vitro, cisplatin significantly increased the expressions of p-PERK, p-eIF2α, CHOP, and caspase-12 in HK-2 cells. When the effect of SIRT2 on cisplatin-induced ER stress was evaluated using SIRT2-siRNA (ON-TARGET plus human SIRT2 siRNA) or the SIRT2 inhibitors, AGK2 and AK1, knockdown or inhibition of SIRT2 significantly attenuated the cisplatin-induced protein expression of p-PERK, p-eIF2α, CHOP, and caspase-12. Immunoprecipitation studies showed SIRT2 bound physically to heat shock factor (HSF)1 and that HSF1 acetylation was significantly increased by cisplatin. In addition, knockdown of SIRT2 increased cisplatin-induced HSF1 acetylation and increased the expression of heat shock protein (HSP)70. Conclusion These observations suggest that suppression of SIRT2 ameliorates cisplatin-induced ER stress by increasing HSF1 acetylation and HSP expression.

Head-down tilt increases rat cardiac muscle eIF-2 alpha phosphorylation

1995 ◽  
Vol 269 (3) ◽  
pp. C802-C804 ◽  
Author(s):  
V. Menon ◽  
D. B. Thomason
Keyword(s):  
Heat Shock ◽  
Heat Shock Protein 70 ◽  
Center Of Mass ◽  
Electrophoretic Analysis ◽  
Initiation Factor ◽  
Two Dimensional ◽  
Eukaryotic Initiation Factor ◽  
Hsp 70 ◽  
Initiation Rate ◽  
Initiation Factor 2

We previously demonstrated that head-down tilt in rats decreases heart polypeptide initiation rate and proposed a mechanism whereby redistribution of the chaperone heat-shock cognate/heat-shock protein-70 (HSC/HSP-70) facilitates the phosphorylation of eukaryotic initiation factor-2 alpha (eIF-2 alpha). In this study, two-dimensional gel electrophoretic analysis of eIF-2 alpha showed no phosphorylation in control hearts. At 8 h of head-down tilt, there was a 45% increase in total eIF-2 alpha, and 79% was phosphorylated. At 18 h, eIF-2 alpha increased to 142% of control, of which 4% was phosphorylated. This is consistent with the previous study where, at 8 h, there was a 78% increase in polysomal HSC/HSP-70 and a shift in the polysome center-of-mass to lighter polysomes (indicating decreased initiation). After 18 h of suspension, polysomal HSC/HSP-70 levels were 24% relative to control, and the center-of-mass returned toward control. We conclude that the decrease in polypeptide initiation during head-down tilt is mediated by HSC/HSP-70 via phosphorylation of eIF-2 alpha.

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