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:FBXW7 modulates stress response by post-translational modification of HSF1 HSF1 orchestrates the heat-shock response upon exposure to heat stress and activates a transcriptional program vital for cancer cells. Genes positively regulated by HSF1 show increeased expression during heat shock while their expression is reduced during recovery. Genes negatively regulated by HSF1 show the opposite pattern. In this study we utilized the HCT116 FBXW7 KO colon cell line and its wild type counterpart to monitor gene expression changes during heat shock (42oC, 1 hour) and recovery (37oC for 2 hours post heat shock) using RNA sequencing. These results revealed that the heat-shock response pathway is prolonged in cells deficient for FBXW7.
Project description:Hyperthermia (HT) is widely used to treat patients with various cancers. In general, HT elicits a wide spectrum of stress responses such as induction of heat shock proteins, protein aggregation and cell death in mammalian cells. Although many biological processes are affected by HT, the overall responses to HT in mammalian cells remain unknown. The effects of heat stress at 41°C for 30 min (mild hyperthermia) on the gene expression in human cervical squamous cell carcinoma HeLa cells were investigated using an Affymetrix GeneChip system.
Project description:FBXW7 modulates stress response by post-translational modification of HSF1 HSF1 orchestrates the heat-shock response upon exposure to heat stress and activates a transcriptional program vital for cancer cells. Genes positively regulated by HSF1 show increeased expression during heat shock while their expression is reduced during recovery. Genes negatively regulated by HSF1 show the opposite pattern. In this study we utilized the HCT116 FBXW7 KO colon cell line and its wild type counterpart to monitor gene expression changes during heat shock (42oC, 1 hour) and recovery (37oC for 2 hours post heat shock) using RNA sequencing. These results revealed that the heat-shock response pathway is prolonged in cells deficient for FBXW7. Whole RNA was extracted from 1 million HCT116 WT or FBXW7KO cells using the RNAeasy kit (Qiagen) according to the manufacturer’s protocol. Poly-A+ (magnetic oligodT-containing beads (Invitrogen)) or Ribominus RNA was used for library preparation. cDNA preparation and strand-specific library construction was performed using the dUTP method. Libraries were sequenced on the Illumina HiSeq 2000 using 50bp single-read method. Differential gene expression analysis was performed for each matched recovery versus heat-shock pairs, separately in each biological replicate and cell line (WT or KO). Two types of comparisons were tested: (a) WT recovery vs WT heat shock, (b) FBXW7 KO recovery vs heat shock.
Project description:Hyperthermia (HT) is widely used to treat patients with various cancers. In general, HT elicits a wide spectrum of stress responses such as induction of heat shock proteins, protein aggregation and cell death in mammalian cells. Although many biological processes are affected by HT, the overall responses to HT in mammalian cells remain unknown. The effects of heat stress at 41M-BM-0C for 30 min (mild hyperthermia) on the gene expression in human cervical squamous cell carcinoma HeLa cells were investigated using an Affymetrix GeneChip system. Human cervical squamous cell carcinoma HeLa cells were treated with heat stress (41M-BM-0C for 30 min) and followed by incubation for 0, 1, or 3 h at 37M-BM-0C. Non-treated cells were served as control. Total RNA samples were prepared from the cells, and quality of the RNA was analyzed using a Bioanalyzer 2100. Gene expression was monitored by an Affymetrix GeneChipM-BM-. system with a Human Genome U133-plus 2.0 array. Sample preparation for array hybridization was carried out as described in the manufacturerM-bM-^@M-^Ys instructions.
Project description:We investigated the root growth of several knockout mutants of heat shock protein family genes and found that heat stress response was compromised in these mutants compared to wild type plants. It suggested that heat shock protein genes including heat shock protein genes including HSP17s, HSP23s, HSP101, and HSFA2 proteins are deployed upon exposure to Cs for plant stress tolerance. Our study provided novel insights into the molecular events occurring in Cs-stressed plants.
Project description:Post-embryonic plant development must be coordinated in response to and with environmental feedback. Development of above-ground organs is orchestrated from stem cells in the center of the shoot apical meristem (SAM). Heat can pose significant abiotic stress to plants and induce a rapid heat shock response, developmental alterations, chromatin decondensation, and activation of transposable elements (TEs). However, most plant heat-stress studies are conducted with seedlings, and we know very little about cell-type-specific responses. Here we use fluorescent-activated nuclear sorting to isolate and characterize stem cells of wild type and mutants defective in TE defense and chromatin compaction after heat shock and after a long recovery. Our results indicate that stem cells can suppress heat shock response pathways to maintain developmental programs. Furthermore, mutants defective in DNA methylation fail to recover efficiently from heat stress and persistently activate heat shock factors and heat-inducible TEs. Heat stress also induces DNA methylation epimutations, especially in the CHG context, and we find hundreds of DNA methylation changes three weeks after stress. Our results underline the importance of disentangling cell type-specific environmental responses for understanding plant development.
Project description:Post-embryonic plant development must be coordinated in response to and with environmental feedback. Development of above-ground organs is orchestrated from stem cells in the center of the shoot apical meristem (SAM). Heat can pose significant abiotic stress to plants and induce a rapid heat shock response, developmental alterations, chromatin decondensation, and activation of transposable elements (TEs). However, most plant heat-stress studies are conducted with seedlings, and we know very little about cell-type-specific responses. Here we use fluorescent-activated nuclear sorting to isolate and characterize stem cells of wild type and mutants defective in TE defense and chromatin compaction after heat shock and after a long recovery. Our results indicate that stem cells can suppress heat shock response pathways to maintain developmental programs. Furthermore, mutants defective in DNA methylation fail to recover efficiently from heat stress and persistently activate heat shock factors and heat-inducible TEs. Heat stress also induces DNA methylation epimutations, especially in the CHG context, and we find hundreds of DNA methylation changes three weeks after stress. Our results underline the importance of disentangling cell type-specific environmental responses for understanding plant development.
Project description:Eukaryotic cells respond to heat shock through several regulatory processes including upregulation of stress responsive chaperones and reversible shutdown cellular activities through formation of protein assemblies. However, the underlying regulatory mechanisms of the recovery of these heat-induced protein assemblies remain largely elusive. Here, we measured the proteome abundance and solubility changes during recovery from severe heat shock in the mouse Neuro2a cell line. We found that prefoldins and translation machinery are rapidly down-regulated as the first step in the heat shock response. Analysis of proteome solubility reveals a rapid mobilization of protein quality control machineries, changes in cellular energy metabolism, changes in translational activity and nucleocytoplasmic transport are fundamental to the early stress responses, while the longer term adaptation to stress involves renewal of core cellular components. Hsp70 inhibition negatively affects the ribosomal machinery and delays the solubility recovery of many nuclear proteins.