Project description:The Heat Shock response (HSR) is a highly conserved transcriptional program induced by the exposure to a variety of environmental stressors. Following an insult, a small subset of genes, known as the Heat Shock genes, are rapidly induced by the Heat Shock Factors (HSFs) to maintain protein homeostasis and ensure cell survival. In this study, we demonstrate that the RNAPII interactor RPRD1B is required for proper transcription of heat shock induced genes and for survival to heat shock.
Project description:The Heat Shock response (HSR) is a highly conserved transcriptional program induced by the exposure to a variety of environmental stressors. Following an insult, a small subset of genes, known as the Heat Shock genes, are rapidly induced by the Heat Shock Factors (HSFs) to maintain protein homeostasis and ensure cell survival. In this study, we demonstrate that the RNAPII interactor RPRD1B is required for proper transcription of heat shock induced genes and for survival to heat shock.
Project description:This is the study of the Heat Shock response of phytopathogenic bacteria Xylella fastidiosa. This series keeps the 25 minutes 40oC stimulus response (Aug 2005). Keywords: stress response; heat shock response
Project description:Recombinant Escherichia coli cultures are used to manufacture numerous therapeutic proteins and industrial enzymes, where many of these processes use elevated temperatures to induce recombinant protein production. The heat-shock response in wild-type E. coli has been well studied. In this study, the transcriptome profiles of recombinant E. coli subjected to a heat-shock and to a dual heat-shock recombinant protein induction were examined. Most classical heat-shock protein genes were identified as regulated in both conditions. The major transcriptome differences between the recombinant and reported wild-type cultures were heavily populated by hypothetical and putative genes, which indicates recombinant cultures utilize many unique genes to respond to a heat-shock. Comparison of the dual stressed culture data with literature recombinant protein induced culture data revealed numerous differences. The dual stressed response encompassed three major response patterns: induced-like, in-between, and greater than either individual stress response. Also, there were no genes that only responded to the dual stress. The most interesting difference between the dual stressed and induced cultures was the amino acid-tRNA gene levels. The amino acid-tRNA genes were elevated for the dual cultures compared to the induced cultures. Since tRNAs facilitate protein synthesis via translation, this observed increase in amino acid-tRNA transcriptome levels, in concert with elevated heat-shock chaperones, might account for improved productivities often observed for thermo-inducible systems. Most importantly, the response of the recombinant cultures to a heat-shock was more profound than wild-type cultures, and further, the response to recombinant protein induction was not a simple additive response of the individual stresses. The objective of the present work is to gain a better understanding of the heat-shock response in recombinant cultures and how this response might impact recombinant protein production. To accomplish this objective, the transcriptome response of recombinant cultures subjected to a heat-shock and a dual heat-shock recombinant protein induction were analyzed. The transcriptome levels were determined using Affymetrix E. coli Antisense DNA microarrays, such that the entire genome was evaluated. These two transcriptome responses were also compared to recombinant cultures at normal growth temperature that were not over-expressing the recombinant protein and a set of literature recombinant culture data that were chemically induced to over-express the recombinant protein. Additionally, the heat-shock response of the recombinant cultures was compared to the literature report of the heat-shock response in wild-type cultures. The results of the global transcriptome analysis demonstrated that recombinant cultures respond differently to a heat-shock stress than wild-type cultures, where the transcriptome response of the recombinant cultures is further modified by production of a recombinant protein.
Project description:Proteotoxic stress such as heat shock causes heat-shock factor (HSF)-dependent transcriptional upregulation of chaperones. Heat shock also leads to a rapid and reversible downregulation of many genes, a process we term stress-induced transcriptional attenuation (SITA). The mechanism underlying this conserved phenomenon is unknown. Here we report that enhanced recruitment of negative transcription elongation factors to gene promoters in human cell lines induces SITA. A chemical inhibitor screen showed that active translation and protein ubiquitination are required for the response. We further find that proteins translated during heat shock are subjected to ubiquitination and that p38 kinase signaling connects cytosolic translation with gene downregulation. Notably, brain samples of subjects with Huntington's disease also show transcriptional attenuation, which is recapitulated in cellular models of protein aggregation similar to heat shock. Thus our work identifies an HSF-independent mechanism that links nascent-protein ubiquitination to transcriptional downregulation during heat shock, with potential ramifications in neurodegenerative diseases.
Project description:Environmental stress, such as oxidative or heat stress, induces the activation of the heat shock response
(HSR) and leads to an increase in the heat shock proteins (HSPs) level. These HSPs act as molecular
chaperones to maintain cellular proteostasis. Controlled by highly intricate regulatory mechanisms,
having stress-induced activation and feedback regulations with multiple partners, the HSR is still
incompletely understood. In this context, we propose a minimal molecular model for the gene
regulatory network of the HSR that reproduces quantitatively different heat shock experiments both
on heat shock factor 1 (HSF1) and HSPs activities. This model, which is based on chemical kinetics
laws, is kept with a low dimensionality without altering the biological interpretation of the model
dynamics. This simplistic model highlights the titration of HSF1 by chaperones as the guiding line of
the network. Moreover, by a steady states analysis of the network, three different temperature stress
regimes appear: normal, acute, and chronic, where normal stress corresponds to pseudo thermal
adaption. The protein triage that governs the fate of damaged proteins or the different stress regimes
are consequences of the titration mechanism. The simplicity of the present model is of interest in
order to study detailed modelling of cross regulation between the HSR and other major genetic
networks like the cell cycle or the circadian clock.
Sivéry, A., Courtade, E., Thommen, Q. (2016). A minimal titration model of the mammalian dynamical heat shock response. Physical biology, 13(6), 066008.
Project description:The transcriptional response to heat shock is essential for cells to function effectively under stress. This is a highly heritable trait but the nature and extent of inter-individual variation in heat shock response are not well established. This dataset consists of the global transcription profiles for a panel of lymphoblastoid cell lines established from 60 founder individuals in the Yoruba HapMap population that have been exposed to heat shock. RNA was extracted from resting cells as well as cells that were exposed to heat shock at 42°C for 1 hour and then allowed to recover for 6 hours at 37°C. In combination with the HapMap genotypes for these individuals this enables the study of the effect of genetic variation on the heat shock response.