Regulation Of Stress-related Genes Research Articles

Small RNA Differential Expression Analysis Reveals miRNAs Involved in Dormancy Progression in Sweet Cherry Floral Buds.

In sweet cherry (Prunus avium), as in other temperate woody perennials, bud dormancy allows for survival in adverse environmental conditions during winter. During this process, environmental signals such as short days and/or low temperatures trigger internal signals that enable buds to become tolerant to the cold. The process involves tracking chilling units up to chilling the requirement fulfillment to resume growth, a transition involving transcriptional regulation, metabolic signaling, and epigenetic-related regulatory events. Massive sequencing of small RNAs was performed to identify miRNAs involved in sweet cherry dormancy by comparing their expression in field (regular seasonal) and controlled non-stop (continuous) chilling conditions. miRNAs highlighted by sequencing were validated using specific stem-loop PCR quantification, confirming expression patterns for known miRNAs such as miR156e, miR166c, miR172d, miR391, miR482c, and miR535b, as well as for newly proposed miRNAs. In silico prediction of the target genes was used to construct miRNA/target gene nodes. In particular, the involvement of the sweet cherry version for the miR156/SQUAMOSA PROMOTER-BINDING-LIKE PROTEIN genes whose expression was opposite in the two conditions suggests their involvement on dormancy regulation in sweet cherry. miRNA levels indicate that the regulation of stress-related genes and hormone synthesis modulates the expression of calcium metabolism and cell development-associated genes. Understanding the regulatory networks involved in sweet cherry dormancy, particularly in the context of miRNA involvement, represents the first step in the development of new agricultural strategies that may help overcome the increasing challenges presented by global climate change.

No long-term effects of antenatal synthetic glucocorticoid exposure on epigenetic regulation of stress-related genes

Antenatal synthetic glucocorticoid (sGC) treatment is a potent modifier of the hypothalamic-pituitary-adrenal (HPA) axis. In this context, epigenetic modifications are discussed as potential regulators explaining how prenatal exposure to GCs might translate into persistent changes of HPA axis “functioning”. The purpose of this study was to investigate whether DNA methylation and gene expression profiles of stress-associated genes (NR3C1; FKBP5; SLC6A4) may mediate the persistent effects of sGC on cortisol stress reactivity that have been previously observed. In addition, hair cortisol concentrations (hairC) were investigated as a valid biomarker of long-term HPA axis activity. This cross-sectional study comprised 108 term-born children and adolescents, including individuals with antenatal GC treatment and controls. From whole blood, DNA methylation was analyzed by targeted deep bisulfite sequencing. Relative mRNA expression was determined by RT-qPCR experiments and qBase analysis. Acute stress reactivity was assessed by the Trier Social Stress Test (TSST) measuring salivary cortisol by ELISA and hairC concentrations were determined from hair samples by liquid chromatography coupled with tandem mass spectrometry. First, no differences in DNA methylation and mRNA expression levels of the stress-associated genes between individuals treated with antenatal sGC compared to controls were found. Second, DNA methylation and mRNA expression levels were neither associated with cortisol stress reactivity nor with hairC. These findings do not corroborate the belief that DNA methylation and mRNA expression profiles of stress-associated genes (NR3C1; FKBP5; SLC6A4) play a key mediating role of the persistent effects of sGC on HPA axis functioning.

Identification of a bio-signature for barley resistance against Pyrenophora teres infection based on physiological, molecular and sensor-based phenotyping

Necrotic and chlorotic symptoms induced during Pyrenophora teres infection in barley leaves indicate a compatible interaction that allows the hemi-biotrophic fungus Pyrenophora teres to colonise the host. However, it is unexplored how this fungus affects the physiological responses of resistant and susceptible cultivars during infection. To assess the degree of resistance in four different cultivars, we quantified visible symptoms and fungal DNA and performed expression analyses of genes involved in plant defence and ROS scavenging. To obtain insight into the interaction between fungus and host, we determined the activity of 19 key enzymes of carbohydrate and antioxidant metabolism. The pathogen impact was also phenotyped non-invasively by sensor-based multireflectance and –fluorescence imaging.Symptoms, regulation of stress-related genes and pathogen DNA content distinguished the cultivar Guld as being resistant. Severity of net blotch symptoms was also strongly correlated with the dynamics of enzyme activities already within the first day of infection. In contrast to the resistant cultivar, the three susceptible cultivars showed a higher reflectance over seven spectral bands and higher fluorescence intensities at specific excitation wavelengths. The combination of semi high-throughput physiological and molecular analyses with non-invasive phenotyping enabled the identification of bio-signatures that discriminates the resistant from susceptible cultivars.

The calcium-binding protein EpANN from the lichenized fungus Endocarpon pusillum enhances stress tolerance in yeast and plants

Annexins are calcium-phospholipid binding proteins that play a significant role in the Ca2+signaling pathway. These proteins are essential for plants to effectively respond to abiotic stresses. However, their functions and mechanisms remain largely unknown in fungi. In this study, an annexin gene, Epann, was cloned from the lichenized fungus Endocarpon pusillum, a drought resistant organism. Our results showed that Epann was induced by several abiotic stresses in E. pusillum. Heterologous expression of the Epann gene enhanced the stress tolerance of Saccharomyces cerevisiae. Under heat-shock conditions, the EpANN proteins were significantly aggregated and the aggregation sites were located on peroxisomes. In heat-shocked cells, Epann reduced the reactive oxygen species level mainly through its intracellular peroxidase activity and regulation of stress-related genes. Transgenic Arabidopsis plants overexpressing Epann exhibited a higher germination rate under oxidative stress and stronger drought tolerance. Our results provide a mechanistic understanding of the role of annexins in abiotic stress responses and suggest that this lichenized fungal gene could be a promising resource to generate stress-tolerant transgenic organisms.

Cloning and stress response analysis of the PeDREB2A and PeDREB1A genes in moso bamboo (Phyllostachys edulis).

Moso bamboo is a large woody bamboo with the highest ecological, economic, and cultural value among all bamboos in Asia. However, environmental stress influences its growth and development and limits its geographic distribution. Therefore, improving its resistance to environmental stress is extremely important. Dehydration responsive element binding (DREB) transcription factors perform an important role in the regulation of stress-related genes, enhancing the resistance of plants to abiotic stress. In the current study, two novel DREB genes, PeDREB2A and PeDREB1A (Gene ID No. PH01000046G1730 and PH01000668G0350), were isolated from moso bamboo and the sequences were identified and characterized (coding sequence lengths were 795 and 825 bp, respectively). The PeDREB2A and PeDREB1A proteins were estimated to have typical AP2/ERF domains, molecular weights of 28.96 and 28.84 kDa, and isoelectric points of 9.47 and 5.34, respectively. RT-PCR analysis revealed that PeDREB2A and PeDREB1A were tissue-specific genes, expressed in leaves, young stems, and roots, with similar expression levels in leaves and young stems. qRT-PCR analysis of leaves demonstrated that PeDREB2A transcription levels rapidly accumulate following exposure to drought and salt stress, peaking at 12 and 0.5 h, respectively, but only low expression levels were observed under cold stress. PeDREB1A exhibited a strong response to cold stress, reaching a peak in expression 3 h after exposure, but demonstrated only a slight response to drought and salt stress. In roots, PeDREB2A was down-regulated, and PeDREB1A was initially upregulated but then declined, under stress conditions. Two plant expression vectors, pCAMBIA2300- CaMV35S-PeDREB2A and pCAMBIA2300-CaMV35S-PeDREB1A were also successfully constructed.

Isolation and characterization of a buffalograss (Buchloe dactyloides) dehydration responsive element binding transcription factor, BdDREB2

Dehydration responsive element binding (DREB) transcription factors play an important role in the regulation of stress-related genes. These factors contribute to resistance to different abiotic stresses. In the present study, a novel DREB transcription factor, BdDREB2, isolated from Buchloe dactyloides, was cloned and characterized. The BdDREB2 protein was estimated to have a molecular weight of 28.36kDa, a pI of 5.53 and a typical AP2/ERF domain. The expression of BdDREB2 was involved in responses to drought and salt stresses. Overexpression of BdDREB2 in tobacco showed higher relative water and proline content, and was associated with lower MDA content under drought stress, suggesting that the transgenic tobacco may tolerate drought stress better. Results demonstrate that BdDREB2 may play an important role in the regulation of abiotic stress responses, and mediate many physiological pathways that enhance stress tolerance in plants.

AMD-Associated Genes Encoding Stress-Activated MAPK Pathway Constituents Are Identified by Interval-Based Enrichment Analysis

PurposeTo determine whether common DNA sequence variants within groups of genes encoding elements of stress-activated mitogen-activated protein kinase (MAPK) signaling pathways are, in aggregate, associated with advanced AMD (AAMD).MethodsWe used meta-regression and exact testing methods to identify AAMD-associated SNPs in 1177 people with AAMD and 1024 AMD-free elderly peers from 3 large-scale genotyping projects on the molecular genetics of AMD. SNPs spanning independent AAMD-associated genomic intervals were examined with a multi-locus-testing method (INRICH) for enrichment within five sets of genes encoding constituents of stress-activated MAPK signaling cascades.ResultsFour-of-five pathway gene sets showed enrichment with AAMD-associated SNPs; findings persisted after adjustment for multiple testing in two. Strongest enrichment signals (P = 0.006) existed in a c-Jun N-terminal kinase (JNK)/MAPK cascade (Science Signaling, STKE CMP_10827). In this pathway, seven independent AAMD-associated regions were resident in 6 of 25 genes examined. These included sequence variants in: 1) three MAP kinase kinase kinases (MAP3K4, MAP3K5, MAP3K9) that phosphorylate and activate the MAP kinase kinases MAP2K4 and MAP2K7 (molecules that phosphorylate threonine and tyrosine residues within the activation loop of JNK); 2) a target of MAP2K7 (JNK3A1) that activates complexes involved in transcriptional regulation of stress related genes influencing cell proliferation, apoptosis, motility, metabolism and DNA repair; and 3) NR2C2, a transcription factor activated by JNK1A1 (a drugable molecule influencing retinal cell viability in model systems). We also observed AAMD-related sequence variants resident in genes encoding PPP3CA (a drugable molecule that inactivates MAP3K5), and two genes (TGFB2, TGFBR2) encoding factors involved in MAPK sensing of growth factors/cytokines.ConclusionsLinkage disequilibrium (LD)-independent genomic enrichment analysis yielded associations of AAMD with aggregates of functionally related genes encoding constituents of the JNK MAPK signaling pathway. FDA-approved drugs now exist to target constituents of stress-activated MAPK pathways and may offer reasonable approaches to preventing or treating AAMD.

An R2R3 MYB transcription factor in wheat, TaPIMP1, mediates host resistance to Bipolaris sorokiniana and drought stresses through regulation of defense‐ and stress‐related genes

In this study, we report new insights into the function of a wheat (Triticum aestivum) MYB gene TaPIMP1 through overexpression and underexpression, and its underlying mechanism in wheat. Electrophoretic mobility shift and yeast-one-hybrid assays indicated that TaPIMP1 can bind to five MYB-binding sites including ACI, and activate the expression of the genes with the cis-element, confirming that TaPIMP1 is an MYB transcription activator. TaPIMP1-overexpressing transgenic wheat exhibited significantly enhanced resistance to the fungal pathogen Bipolaris sorokiniana and drought stresses, whereas TaPIMP1-underexpressing transgenic wheat showed more susceptibility to the stresses compared with untransformed wheat, revealing that TaPIMP1 positively modulates host-defense responses to B.sorokiniana and drought stresses. Microarray analysis showed that a subset of defense- and stress-related genes were up-regulated by TaPIMP1. These genes, including TaPIMP1, RD22, TLP4 and PR1a, were regulated by ABA and salicylic acid (SA). TaPIMP1-underexpressing transgenic wheat showed compromised induction of these stress-responsive genes following ABA and SA treatments. In summary, TaPIMP1, as a positive molecular linker, mediates resistance to B.sorokiniana and drought stresses by regulation of stress-related genes in ABA- and SA-signaling pathways in wheat. Furthermore, TaPIMP1 may provide a transgenic tool for engineering multiple-resistance wheat in breeding programs.

Molecular dynamics simulations reveal the disparity in specific recognition of GCC‐box by AtERFs transcription factors super family in Arabidopsis

Arabidopsis ethylene responsive element binding factors (AtERFs) form a transcription factor super family. While the functions of most AtERFs are unknown, a number of AtERFs appear to be involved in regulation of stress-related genes through their DNA binding domains (DBD), namely ERF domains, which recognize a consensus motif GCC-box at the regulatory region. In this study, molecular dynamics simulations were performed on the four ERF domain-GCC-box complexes, AtERF1, AtERF4, AtEBP and CFBF1, to determine disparity in specific binding to the GCC-box by the AtERFs. Our results suggested that three amino acid residues Arg29, Glu39 and Arg41, played a vital role in direct readout of DNA. The position of the consensus sequence GCCGCC has an intrinsic disparity on binding with ERF domains. The third C, fourth G and the last C in the GCC motif was compulsory for recognition by ERF domains. Our results provide structural evidence for a sequence-dependent recognition mechanism for AtERFs.

Developmental patterns of NF-κB activation during acute hypoxia in the caudal brainstem of the rat

NF-κB, an ubiquitous transcription factor which plays a major role in the regulation of stress-related genes, is activated during environmental hypoxia in the dorsocaudal brainstem of adult rats. To examine the developmental pattern of NF-κB basal activity in the brainstem and the response to hypoxia, electromobility shift assays and immunohistochemical staining for the P65 subunit of NF-κB were performed in caudal brainstem samples of rats at 2, 5, 10, 15, and 60 days postnatal age, following normoxic or hypoxic (1 h in 10% O 2) exposures. In addition, the expression of IκB-α, and IκB kinases (ikk)-α and -β was also examined using Western blots. Basal NF-κB nuclear activity and nuclear P65 immunoreactivity increased with maturation. In contrast, hypoxia induced enhanced activation of NF-κB and nuclear translocation of P65 in youngest animals. Expression of both IκB-α and ikk-α was highest in the more immature rats, and decreased with postnatal age. In contrast, ikk-β expression was unchanged over time. We conclude that NF-κB activity in caudal brainstem is developmentally regulated, and that hypoxia-induced NF-κB activation is more prominent in youngest rats. We postulate that postnatal regulation of NF-κB complex expression and function may underlie fundamental genomic processes mediating developmental changes in neuronal hypoxic tolerance.