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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.
2023-09-30 | GSE223850 | GEO
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.
2023-09-30 | GSE223914 | GEO
Project description:Protein quality control (proteostasis) depends on constant protein degradation and resynthesis, and is essential for proper homeostasis in systems from single cells to whole organisms. Cells possess several mechanisms and processes to maintain proteostasis. At one end of the spectrum, the heat shock proteins modulate protein folding and repair. At the other end, the proteasome and autophagy as well as other lysosome-dependent systems, function in the degradation of dysfunctional proteins. In this review, we examine how these systems interact to maintain proteostasis. Both the direct cellular data on heat shock control over autophagy and the time course of exercise-associated changes in humans support the model that heat shock response and autophagy are tightly linked. Studying the links between exercise stress and molecular control of proteostasis provides evidence that the heat shock response and autophagy coordinate and undergo sequential activation and downregulation, and that this is essential for proper proteostasis in eukaryotic systems.
| S-EPMC4502786 | biostudies-literature
Project description:Understanding how plants sense and respond to heat stress is central to improve crop tolerance and productivity. Recent findings in Physcomitrella patens demonstrated that the controlled passage of calcium ions across the plasma membrane regulates the heat shock response (HSR). To investigate the effect of membrane lipid composition on the plant HSR, we acclimated P. patens to a slightly elevated yet physiological growth temperature and analysed the signature of calcium influx under a mild heat shock. Compared to tissues grown at 22°C, tissues grown at 32°C had significantly higher overall membrane lipid saturation level and, when submitted to a short heat shock at 35°C, displayed a noticeably reduced calcium influx and a consequent reduced heat shock gene expression. These results show that temperature differences, rather than the absolute temperature, determine the extent of the plant HSR and indicate that membrane lipid composition regulates the calcium-dependent heat-signaling pathway.
| S-EPMC3115095 | biostudies-literature
Project description:The most abundant mRNA post-transcriptional modification is N(6)-methyladenosine (m(6)A), which has broad roles in RNA biology. In mammalian cells, the asymmetric distribution of m(6)A along mRNAs results in relatively less methylation in the 5' untranslated region (5'UTR) compared to other regions. However, whether and how 5'UTR methylation is regulated is poorly understood. Despite the crucial role of the 5'UTR in translation initiation, very little is known about whether m(6)A modification influences mRNA translation. Here we show that in response to heat shock stress, certain adenosines within the 5'UTR of newly transcribed mRNAs are preferentially methylated. We find that the dynamic 5'UTR methylation is a result of stress-induced nuclear localization of YTHDF2, a well-characterized m(6)A 'reader'. Upon heat shock stress, the nuclear YTHDF2 preserves 5'UTR methylation of stress-induced transcripts by limiting the m(6)A 'eraser' FTO from demethylation. Remarkably, the increased 5'UTR methylation in the form of m(6)A promotes cap-independent translation initiation, providing a mechanism for selective mRNA translation under heat shock stress. Using Hsp70 mRNA as an example, we demonstrate that a single m(6)A modification site in the 5'UTR enables translation initiation independent of the 5' end N(7)-methylguanosine cap. The elucidation of the dynamic features of 5'UTR methylation and its critical role in cap-independent translation not only expands the breadth of physiological roles of m(6)A, but also uncovers a previously unappreciated translational control mechanism in heat shock response.
| S-EPMC4851248 | biostudies-literature
Project description:Heat stress resistance and response were studied in strains of Lactobacillus plantarum. Stationary-phase cells of L. plantarum DPC2739 had decimal reduction times (D values) (D value was the time that it took to reduce the number of cells by 1 log cycle) in sterile milk of 32.9, 14.7, and 7.14 s at 60, 72, and 75 degrees C, respectively. When mid-exponential-phase cells were used, the D values decreased. The temperature increases which caused a 10-fold reduction in the D value ranged from 9 to 20 degrees C, depending on the strain. Part of the cell population treated at 72 degrees C for 90 s recovered viability during incubation at 7 degrees C in sterile milk for 20 days. When mid-exponential- or stationary-phase cells of L. plantarum DPC2739 were adapted to 42 degrees C for 1 h, the heat resistance at 72 degrees C for 90 s increased ca. 3 and 2 log cycles, respectively. Heat-adapted cells also showed increased growth at pH 5 and in the presence of 6% NaCl. Two-dimensional gel electrophoresis of proteins expressed by control and heat-adapted cells revealed changes in the levels of expression of 31 and 18 proteins in mid-exponential- and stationary-phase cells, respectively. Twelve proteins were commonly induced. Nine proteins induced in the heat-adapted mid-exponential- and/or stationary-phase cells of L. plantarum DPC2739 were subjected to N-terminal sequencing. These proteins were identified as DnaK, GroEL, trigger factor, ribosomal proteins L1, L11, L31, and S6, DNA-binding protein II HlbA, and CspC. All of these proteins have been found to play a role in the mechanisms of stress adaptation in other bacteria. Antibodies against GroES detected a protein which was induced moderately, while antibodies against DnaJ and GrpE reacted with proteins whose level of expression did not vary after heat adaptation. This study showed that the heat resistance of L. plantarum is a complex process involving proteins with various roles in cell physiology, including chaperone activity, ribosome stability, stringent response mediation, temperature sensing, and control of ribosomal function. The physiological mechanisms of response to pasteurization in L. plantarum are fundamental for survival in cheese during manufacture.
| S-EPMC368309 | biostudies-literature
Project description:The heat shock response of the hyperthermophilic archaeon Archaeoglobus fulgidus strain VC-16 was studied using whole-genome microarrays. On the basis of the resulting expression profiles, approximately 350 of the 2,410 open reading frames (ORFs) (ca. 14%) exhibited increased or decreased transcript abundance. These span a range of cell functions, including energy production, amino acid metabolism, and signal transduction, where the majority are uncharacterized. One ORF called AF1298 was identified that contains a putative helix-turn-helix DNA binding motif. The gene product, HSR1, was expressed and purified from Escherichia coli and was used to characterize specific DNA recognition regions upstream of two A. fulgidus genes, AF1298 and AF1971. The results indicate that AF1298 is autoregulated and is part of an operon with two downstream genes that encode a small heat shock protein, Hsp20, and cdc48, an AAA+ ATPase. The DNase I footprints using HSR1 suggest the presence of a cis-binding motif upstream of AF1298 consisting of CTAAC-N5-GTTAG. Since AF1298 is negatively regulated in response to heat shock and encodes a protein only distantly related to the N-terminal DNA binding domain of Phr of Pyrococcus furiosus, these results suggest that HSR1 and Phr may belong to an evolutionarily diverse protein family involved in heat shock regulation in hyperthermophilic and mesophilic Archaea organisms.
| S-EPMC1196131 | biostudies-literature
Project description:Accumulation of misfolded protein in the endoplasmic reticulum (ER) causes stress. The unfolded protein response (UPR), a transcriptional induction pathway, is activated to relieve ER stress. Although UPR is not essential for viability, UPR-deficient cells are more sensitive to ER stress; ire1Delta cells cannot grow when challenged with tunicamycin or by overexpression of misfolded CPY(*). In these cells, multiple functions are defective, including translocation, ER-associated degradation (ERAD), and ER-to-Golgi transport. We tested whether heat shock response (HSR) can relieve ER stress. Using a constitutively active Hsf1 transcription factor to induce HSR without temperature shift, we find that HSR rescues growth of stressed ire1Delta cells, and partially relieves defects in translocation and ERAD. Cargo-specific effects of constitutively active Hsf1 on ER-to-Golgi transport are correlated with enhanced protein levels of the respective cargo receptors. In vivo, HSR is activated by ER stress, albeit to a lower level than that caused by heat. Genomic analysis of HSR targets reveals that >25% have function in common with UPR targets. We propose that HSR can relieve stress in UPR-deficient cells by affecting multiple ER activities.
| S-EPMC2323268 | biostudies-literature
Project description:The Babesia gibsoni heat shock protein 90 (BgHSP90) gene was cloned and sequenced. The length of the gene was 2,610 bp with two introns. This gene was amplified from cDNA corresponding to full length coding sequence (CDS) with an open reading frame of 2,148 bp. A phylogenetic analysis of the CDS of HSP90 gene showed that B. gibsoni was most closely related to B. bovis and Babesia sp. BQ1/Lintan and lies within a phylogenetic cluster of protozoa. Moreover, mRNA transcription profile for BgHSP90 exposed to high temperature were examined by quantitative real-time reverse transcription-polymerase chain reaction. BgHSP90 levels were elevated when the parasites were incubated at 43°C for 1 hr.
| S-EPMC5053942 | biostudies-literature
Project description:The molecular basis of heat shock response (HSR), a cellular defense mechanism against various stresses, is not well understood. In this, the first comprehensive analysis of gene expression changes in response to heat shock and MG132 (a proteasome inhibitor), both of which are known to induce heat shock proteins (Hsps), we compared the responses of normal mouse fibrosarcoma cell line, RIF-1, and its thermotolerant variant cell line, TR-RIF-1 (TR), to the two stresses. The cellular responses we examined included Hsp expressions, cell viability, total protein synthesis patterns, and accumulation of poly-ubiquitinated proteins. We also compared the mRNA expression profiles and kinetics, in the two cell lines exposed to the two stresses, using microarray analysis. In contrast to RIF-1 cells, TR cells resist heat shock caused changes in cell viability and whole-cell protein synthesis. The patterns of total cellular protein synthesis and accumulation of poly-ubiquitinated proteins in the two cell lines were distinct, depending on the stress and the cell line. Microarray analysis revealed that the gene expression pattern of TR cells was faster and more transient than that of RIF-1 cells, in response to heat shock, while both RIF-1 and TR cells showed similar kinetics of mRNA expression in response to MG132. We also found that 2,208 genes were up-regulated more than 2 fold and could sort them into three groups: 1) genes regulated by both heat shock and MG132, (e.g. chaperones); 2) those regulated only by heat shock (e.g. DNA binding proteins including histones); and 3) those regulated only by MG132 (e.g. innate immunity and defense related molecules). This study shows that heat shock and MG132 share some aspects of HSR signaling pathway, at the same time, inducing distinct stress response signaling pathways, triggered by distinct abnormal proteins.
| S-EPMC3127947 | biostudies-literature