Differential regulation of HSFA1s and HSFA2 after heat shock in Arabidopsis
ABSTRACT: HSFA1s are a gene family of HSFA1 with four members, HSFA1a, HSFA1b, HSFA1d, and HSFA1e. HSFA1s are the master regulators of heat shock response. As a part of the heat shock response, HSFA2 can prolong the heat shock response and amplify the heat shock response in response to repeat heat shock. To identify the heat-shock-responsive genes differentially regulated by HSFA1s and HSFA2, we compared the transcriptomic differences of plants containing only constitutively expressed HSFA1s or HSFA2 after heat stress. hsfa2 (the KO mutant of HSFA2, Col-0 background) and A2QK-10 (CaMV 35S:HSFA2 in QK mutant; QK is HSFA1a/b/d/e quadruple KO mutant) were used to compare the difference of heat shock response when plants lack HSFA1s or HSFA2. The aim is to find the HSFA1s- and HSFA2-preferred regulating genes after heat stress. As the control samples, wild type is the plant with normal heat shock response, and QK (HSFA1s KO mutant, Col-0 and Ws mixed background) is the plant that lost the heat shock response controlled by HSFA1s.
Project description:In order to study the importance of HSFA1 in thermotolerance in Arabidopsis, we generated the HSFA1a, b, d and e quadruple mutant (QK). QK is very sensitive to heat. Therefore, we used microarray to study how many genes regulated by HSFA1 after heat shock. Seven-day-old seedlings of Col-0, Ws and QK grown at 22oC on 0.5x MS plates containing 1% sucrose were incubated for 1 h at 37 °C. Subsequently, samples were collected for RNA extraction. The experiment was repeated, and two biological replicates were processed for analysis.
Project description:In order to study the importance of HSFA1 in thermotolerance in Arabidopsis, we generated the HSFA1a, b, d and e quadruple mutant (QK). QK is very sensitive to heat. Therefore, we used microarray to study how many genes regulated by HSFA1 after heat shock. Overall design: Seven-day-old seedlings of Col-0, Ws and QK grown at 22oC on 0.5x MS plates containing 1% sucrose were incubated for 1 h at 37 °C. Subsequently, samples were collected for RNA extraction. The experiment was repeated, and two biological replicates were processed for analysis.
Project description:Arabidopsis 5’-3’ exoribonuclease, AtXRN4, a homolog of yeast Xrn1p, functions in degradation of uncapped RNAs after de-capping step. While Xrn1p-dependent on plant XRN4’s targets for degradation is still limited. For understanding biological function of AtXRN4, we tested survivability of atxrn4 mutants under heat stress. Our results showed that atxrn4 mutants increased survival rate under short-term degradation is a main mRNA decay in yeast, knowledge heat stress compared with WT plants. Our microarray and mRNA decay assay showed that loss of AtXRN4 function caused reduction of mRNA degradation of heat shock factor A2 (HSFA2) and ethylene response factor 1 (ERF1). HSFA2 has been known as a key regulator in heat acclimation, was found as a target for AtXRN4 for degradation at non-stress condition. Heat stress applied on atxrn4-3 hsfa2 double mutant severely lacked heat tolerance phenotype of atxrn4 mutant. These results suggest that AtXRN4-mediated mRNA degradation linked to suppress heat acclimation. In the study here, 2 week-old WT and atxrn4-3 mutant plants were exposure to non-stress (22oC) and heat-stress (37oC, 1 h). Custom microarray was applied to acquire expression profile of 32788 Arabidopsis genes. 3 biological repeats of WT (non-stress), WT(heat stress), atxrn4-3 (non-stress) and atxrn4-3 (heat stress) were used for microarray analysis
Project description:The expression of heat-shock proteins (Hsps) induced by a non-lethal heat treatment confers acquired thermotolerance (AT) to organisms against a subsequent challenge of otherwise lethal temperature. After stress signal lifted, AT gradually decayed with the decline of Hsps during recovery period. The duration of AT may be critical for sessile organisms, such as plants, to survive repeated heat stress in the environment. To identify heat-induced genes involved in duration of AT, we took a reverse-genetics approach by screening for Arabidopsis T-DNA insertion mutants that show decreased thermotolerance after a long recovery at non-stress condition following a conditioning treatment. Among the tested mutants corresponding to 47 genes, only the HsfA2 knockout mutant showed significant phenotype. The mutant plants were more sensitive to severe heat stress than the wild type after long but not short recovery following a pretreatment at 37oC, which can be complemented by introducing a wild-type copy of the gene. Quantitative hypocotyl elongation assay also revealed that AT decayed faster in the absence of HsfA2. Significant decline of the transcript levels of several highly heat-induced genes was observed in the HsfA2 knockout plants after a 4-h recovery or after 2 h of prolonged heat stress. Immunoblot anlysis showed that Hsa32 and class I small Hsp were lower in the mutant than in the wild type after a long recovery. Our results suggest that HsfA2 as a heat-induced transactivator sustains the post-stress expression of Hsp genes and extends the duration of AT in Arabidopsis. Experiment Overall Design: Total RNA was isolated from the seedlings of 5-d old wild-type and HsfA2 knockout mutant seedlings (a pool of about 100 plants per treatment in duplicates) harvested immediately after heat shock treatment. In this experiment, total 12 chips were used, 1 each for 2 biological replicates of the control and HS-treated samples for the wild type and mutant plants.
Project description:Heat shock proteins (Hsps) are molecular chaperones primarily involved in maintenance of protein homeostasis. Their function has been best characterized in heat stress (HS) response during which Hsps are transcriptionally controlled by heat stress transcription factors (Hsfs). The role of Hsfs and Hsps in HS-response in tomato was initially examined by transcriptome analysis using the Massive Analysis of cDNA Ends (MACE) method. Approximately 9.6% of all genes expressed in leaves are enhanced in response to HS, including a subset of Hsfs and Hsps. The underlying Hsp-Hsf networks with potential functions in stress responses or developmental processes were further explored by meta-analysis of existing microarray datasets. We identified clusters with differential transcript profiles with respect to abiotic stresses, plant organs and developmental stages. The composition of two clusters points toward two major chaperone networks. One cluster consisted of constitutively expressed plastidial chaperones and other genes involved in chloroplast protein homeostasis. The second cluster represents genes strongly induced by heat, drought and salinity stress, including HsfA2 and many stress-inducible chaperones, but also potential targets of HsfA2 not related to protein homeostasis. This observation attributes a central regulatory role to HsfA2 in controlling different aspects of abiotic stress response and tolerance in tomato. 2 samples
Project description:Male reproductive tissues are more sensitive to heat stress compared to vegetative tissues, however the basis of this phenomenon is poorly understood. Heat stress transcription factors (Hsfs) regulate the transcriptional changes required for protection and recovery from heat stress. HsfA2 has been characterized as co-activator of HsfA1a in tomato and is considered as one of the major Hsfs accumulating in response to elevated temperatures. The role of HsfA2 in heat stress response of different tissues was examined by exploring the composition and structure of the tissue-specific regulatory networks in transgenic tomato plants with suppressed HsfA2 expression (A2AS). Transcriptome analysis revealed that HsfA2 acts in condition- and tissue-specific manner and that only a subset of heat stress induced genes require HsfA2 for higher expression. Remarkably, although HsfA2 is not essential for thermotolerance in seedlings and flowering plants, it is required for maintenance pollen viability under stress conditions. We show that the activation of Hsf networks is important for the developmentally regulated priming of heat stress response occurring at early stages of anther and pollen development. Thereby, HsfA2 is involved in pollen thermotolerance by directly regulating heat stress responsive genes but also by stimulating the synthesis of molecular chaperones under non-stress conditions. 8 samples
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:Plants can be primed by a stress cue to mount a faster and stronger activation of defense mechanisms upon a subsequent stress. A crucial component of such stress priming is the modified reactivation of genes upon recurring stress, a phenomenon known as transcriptional memory. The transcriptional memory in response to heat stress is not clear at the genome scale. We used microarrays to identify genes that showed transcriptional memory in response to recurring heat stress. Overall design: Arabidopsis thaliana 7-d-old wild-type (Col-0) seedlings subjected to four different treatments were collected for RNA extraction. Naïve: 7-d-old seedlings kept at normal growth condition without heat stress; Primed: 4-d-old seedlings were treated at 37 °C for 1 h then at normal growth condition for 3 d before sample collection; Triggered: 7-d-old seedlings were treated at 37 °C for 1 h before sample collection; Primed and triggered: 4-d-old seedlings were treated at 37 °C for 1 h, transferred to normal growth condition for 3 d, treated at 37 °C for 1 h again before sample collection. The heat treatment was performed around 10 am of the day. For HSFA2 knockout mutant (SALK_008978), the same treatments were conducted except the primed. The experiment contained at least two biological replicates for each treatment.