Project description:Stress response pathways allow cells to rapidly sense and respond to deleterious environmental changes, including those caused by pathophysiological disease states. A previous screen for small molecules capable of activating the human heat shock response identified the triterpenoid celastrol as a potent activator of the heat shock transcription factor HSF1. We show here that celastrol likewise activates the homologous Hsf1 of Saccharomyces cerevisiae. Celastrol induced Hsf1 hyperphosphorylation and concurrently activated a synthetic transcriptional reporter as well as endogenous inducible Hsp70 proteins at the same effective concentration seen in mammalian cells. Moreover, celastrol treatment conferred significant resistance to subsequent lethal heat shock. Transcriptional profiling experiments revealed that in addition to Hsf1, celastrol treatment induced the Yap1-dependent oxidant defense regulon. Oxidative stress-responsive genes were likewise induced in mammalian cells, demonstrating that celastrol simultaneously activates two major cellular stress-mediating pathways. As the induction of cellular stress pathways has implications in the treatment of a variety of human diseases including neurodegenerative diosorders, cardiovascular disease and cancer, celastrol thus represents an attractive therapeutic compound. Keywords: single-dose, single time-point gene induction by natural small molecule celastrol compared to heat shock in wild type (BY4741) Saccahromyces cerevisiae
Project description:S. cerevisae cells were exposed to different series of mild stresses. Stress type include heat shock, oxidative and osmotic stresses. Microarrays were used to follow the genome-wide transcriptional response to the stresses and to identify genes that can underlie the cross protection phenotype between heat shock and oxidative stress. Experiment Overall Design: Cell sample at different time points after stress application were used for RNA extraction and hybridization on Affymetrix microarrays.
Project description:S. cerevisae cells were exposed to different series of mild stresses. Stress type include heat shock, oxidative and osmotic stresses. Microarrays were used to follow the genome-wide transcriptional response to the stresses and to identify genes that can underlie the cross protection phenotype between heat shock and oxidative stress. Keywords: time course
Project description:To better understand how yeast adapt and respond to sequential stressors, an industrial yeast strain, URM 6670 (also known as BT0510), which is highly flocculent, tolerant to ethanol, osmotic and heat shock stresses, was subjected to three different treatments: 1. osmotic stress followed by ethanol stress, 2. oxidative stress followed by ethanol stress, 3. glucose withdrawal followed by ethanol stress. Samples were collected before the first stress (control), after the first stress and after the second stress (ethanol). RNA was extracted and analyzed by RNAseq.
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:Here we used mass spectrometry-based proteomics technology to explore SEPs with potential cellular stress function in Saccharomyces cerevisiae. Microproteins with unique peptides were identified under six culture conditions: normal, oxidation, starvation, UV radiation, heat shock, and heat shock with starvation.