Prolonged Stress Conditions Research Articles

TFEB and TFE3 are novel components of the integrated stress response.

To reestablish homeostasis and mitigate stress, cells must activate a series of adaptive intracellular signaling pathways. The participation of the transcription factors TFEB and TFE3 in cellular adaptation to starvation is well established. Here, we show that TFEB and TFE3 also play an important role in the cellular response to ER stress. Treatment with ER stressors causes translocation of TFEB and TFE3 to the nucleus in a process that is dependent on PERK and calcineurin but not on mTORC1. Activated TFEB and TFE3 enhance cellular response to stress by inducing direct transcriptional upregulation of ATF4 and other UPR genes. Under conditions of prolonged ER stress, TFEB and TFE3 contribute to cell death, thus revealing an unexpected role for these proteins in controlling cell fate. This work evidences a broader role of TFEB and TFE3 in the cellular response to stress than previously anticipated and reveals an integrated cooperation between different cellular stress pathways.

Mutualistic fungal endophytes produce phytohormones and organic acids that promote japonica rice plant growth under prolonged heat stress.

This study identifies the potential role in heat-stress mitigation of phytohormones and other secondary metabolites produced by the endophytic fungus Paecilomyces formosus LWL1 in japonica rice cultivar Dongjin. The japonica rice was grown in controlled chamber conditions with and without P. formosus LWL1 under no stress (NS) and prolonged heat stress (HS) conditions. Endophytic association under NS and HS conditions significantly improved plant growth attributes, such as plant height, fresh weight, dry weight, and chlorophyll content. Furthermore, P. formosus LWL1 protected the rice plants from HS compared with controls, indicated by the lower endogenous level of stress-signaling compounds such as abscisic acid (25.71%) and jasmonic acid (34.57%) and the increase in total protein content (18.76%-33.22%). Such fungal endophytes may be helpful for sustainable crop production under high environmental temperatures.

Role of the Porphyromonas gingivalis iron-binding protein PG1777 in oxidative stress resistance.

Whole genome sequencing of the response of Porphyromonas gingivalis W83 to hydrogen peroxide revealed an upregulation of several uncharacterized, novel genes. Under conditions of prolonged oxidative stress in P. gingivalis, increased expression of a unique transcriptional unit carrying the grpE, dnaJ and three other hypothetical genes (PG1777, PG1778 and PG1779) was observed. The transcriptional start site of this operon appears to be located 91 bp upstream of the translational start, with a potential -10 region at -3 nt and a -35 region at -39 nt. Isogenic P. gingivalis mutants FLL273 (PG1777 : : ermF-ermAM) and FLL293 (PG1779 : : ermF-ermAM) showed increased sensitivity to and decreased survival after treatment with hydrogen peroxide. P. gingivalis FLL273 showed a fivefold increase in the formation of spontaneous mutants when compared with the parent strain after exposure to hydrogen peroxide. The recombinant PG1777 protein displayed iron-binding properties when incubated with FeSO4 and Fe(NH4)2(SO4).6H2O. The rPG1777 protein protected DNA from degradation when exposed to hydrogen peroxide in the presence of iron. Taken together, the data suggest that the grpE-dnaJ-PG1777-PG1778-PG1779 transcriptional unit may play an important role in oxidative stress resistance in P. gingivalis via its ability to protect against DNA damage.

Metabolomic and proteomic responses of Staphylococcus aureus to prolonged cold stress.

Work in our laboratory has shown that prolonged exposure of S. aureus to cold stress can result in the formation of small colony variants (SCVs) associated with significant alterations in the cell wall composition. Further studies revealed that S. aureus altered cell size and cell wall thickness in response to exposure to cold temperatures, alterations in pH and exposure to antibiotics. The current study has utilised the prolonged exposure to cold stress as a model system to explore changes in the proteome and associated metabolic homeostasis following environmental challenges. The study provides an improved understanding of how S. aureus adapts to the changing environment whilst in transition between human hosts. The results indicated an unexpected production of 9 ribosomal proteins and citric acid in response to cold stress suggesting specific survival roles for these proteins and citric acid as an adaptation mechanism for empowering survival under these conditions.

Epidermal growth factor receptor signaling and the progression of diabetic nephropathy.

Epidermal growth factor receptor signaling and the progression of diabetic nephropathy.

Endoplasmic reticulum stress response and transcriptional reprogramming.

Endoplasmic reticulum stress response and transcriptional reprogramming.

P58IPK is an inhibitor of the eIF2α kinase GCN2 and its localization and expression underpin protein synthesis and ER processing capacity.

One of the key cellular responses to stress is the attenuation of mRNA translation and protein synthesis via the phosphorylation of eIF2α (eukaryotic translation initiation factor 2α). This is mediated by four eIF2α kinases and it has been suggested that each kinase is specific to the cellular stress imposed. In the present study, we show that both PERK (PKR-like endoplasmic reticulum kinase/eIF2α kinase 3) and GCN2 (general control non-derepressible 2/eIF2α kinase 4) are required for the stress responses associated with conditions encountered by cells overexpressing secreted recombinant protein. Importantly, whereas GCN2 is the kinase that is activated following cold-shock/hypothermic culturing of mammalian cells, PERK and GCN2 have overlapping functions since knockdown of one of these at the mRNA level is compensated for by the cell by up-regulating levels of the other. The protein p58IPK {also known as DnaJ3C [DnaJ heat-shock protein (hsp) 40 homologue, subfamily C, member 3]} is known to inhibit the eIF2α kinases PKR (dsRNA-dependent protein kinase/eIF2α kinase 2) and PERK and hence prevent or delay eIF2α phosphorylation and consequent inhibition of translation. However, we show that p58IPK is a general inhibitor of the eIF2α kinases in that it also interacts with GCN2. Thus forced overexpression of cytoplasmic p58 delays eIF2α phosphorylation, suppresses GCN2 phosphorylation and prolongs protein synthesis under endoplasmic reticulum (ER), hypothermic and prolonged culture stress conditions. Taken together, our data suggest that there is considerable cross talk between the eIF2α kinases to ensure that protein synthesis is tightly regulated. Their activation is controlled by p58 and the expression levels and localization of this protein are crucial in the capacity the cells to respond to cellular stress via control of protein synthesis rates and subsequent folding in the ER.

POSTHARVEST WATER STRESS LEADING TO PEEL DISORDERS IN CITRUS FRUIT INVOLVES REGULATION OF PHOSPHOLIPASES BY ABA

The interplay between abscisic acid (ABA) and phospholipases A2 and D (PLA2 and PLD) in the response of citrus fruit to water stress was investigated during postharvest storage using ‘Navelate’ orange and its ABA-deficient mutant ‘Pinalate’. Fruits from both varieties were subjected to prolonged water stress conditions inducing non-chilling peel pitting in the rind. Treatment with phospholipase inhibitors reduced the disorder in both varieties suggesting that phospholipid metabolism is involved in citrus peel quality. Expression of genes encoding PLA2 and PLD was studied by real time RT-PCR during water stress and in response to ABA. Expression of CssPLA2I± was dependant on ABA in fruit from both varieties, since ABA application restored expression in the mutant, showing for the first time the involvement of this hormone in the activation of PLA2. CsPLDI± expression increased with dehydration in mature-green fruit from ‘Navelate’ but not from ‘Pinalate’, and ABA did not counteract this effect. Together, results show that susceptibility to stem-end rind breakdown (SERB) and regulation of phospholipase gene expression varies with maturation and that ABA action is upstream phospholipase activation in response to water stress.

S2-2 - Regulation and involvement of the ubiquitin ligases in muscle atrophy

The ability to activate compensatory mechanisms in response to environmental stress is an important factor for survival and maintenance of cellular functions. A system that is often activated both in short and prolonged stress conditions is ubiquitin proteasome system (UPS). UPS is required to clear the cell from dysfunctional and altered proteins and is reported to increase during catabolic conditions. This increase contributes to the loss of contractile proteins and, when is exacerbated, to cachexia. Here I'll present the last data about UPS regulation, the role of UPS in protein turnover in skeletal muscles and the pathogenetic implications of deregulated UPS in muscle disorders.

Involvement of PG2212 zinc finger protein in the regulation of oxidative stress resistance in Porphyromonas gingivalis W83.

The adaptation of Porphyromonas gingivalis to H2O2-induced stress while inducible is modulated by an unknown OxyR-independent mechanism. Previously, we reported that the PG_2212 gene was highly upregulated in P. gingivalis under conditions of prolonged oxidative stress. Because this gene may have regulatory properties, its function in response to H2O2 was further characterized. PG2212, annotated as a hypothetical protein of unknown function, is a 10.3-kDa protein with a cysteine 2-histidine 2 (Cys2His2) zinc finger domain. The isogenic mutant P. gingivalis FLL366 (ΔPG_2212) showed increased sensitivity to H2O2 and decreased gingipain activity compared to the parent strain. Transcriptome analysis of P. gingivalis FLL366 revealed that approximately 11% of the genome displayed altered expression (130 downregulated genes and 120 upregulated genes) in response to prolonged H2O2-induced stress. The majority of the modulated genes were hypothetical or of unknown function, although some are known to participate in oxidative stress resistance. The promoter region of several of the most highly modulated genes contained conserved motifs. In electrophoretic mobility shift assays, the purified rPG2212 protein did not bind its own promoter region but bound a similar region in several of the genes modulated in the PG_2212-deficient mutant. A metabolome analysis revealed that PG2212 can regulate a number of genes coding for proteins involved in metabolic pathways critical for its survival under the conditions of oxidative stress. Collectively, our data suggest that PG2212 is a transcriptional regulator that plays an important role in oxidative stress resistance and virulence regulation in P. gingivalis.

Change in the terpenoid profile and secondary growth in declining stands of <em>Pinus sylvestris</em> L. under mediterranean influence as a response to local factors

The terpenoid profile could give information about the water status in Scots pine, especially for trees growing in the same geographical area but under contrasting local environmental conditions. Terpenes were analyzed by gas chromatography-mass spectrometry in needles, twigs and wood of ten affected and ten unaffected Scots pines in the southern “Sistema Iberico” range (Teruel, Spain), where forest decline has been recently reported. Soil depth and secondary growth was also studied in both types of trees. Needles and twigs total resin acids were significantly higher in affected trees. The pimarane type resin acids were also higher in the twigs of affected trees. Secondary growth was lower in affected trees and it showed higher climate sensitivity. The use of the terpenoid profile may be used as an additional tool for the estimation of the water status, especially for situations inducing moderate but relatively prolonged stress conditions.

A.I.1: Basics of autophagy in muscle – Cellular mechanisms

The ability to activate compensatory mechanisms in response to environmental stress is an important factor for survival and maintenance of cellular functions. A system that is often activated both in short and prolonged stress conditions is autophagy. Autophagy is required to clear the cell from dysfunctional organelles and altered proteins and is reported to decline during diseases or ageing. This reduction might contribute to the pathogenesis of organ dysfunction and, in general, to ageing. Here I will present the last data about the role of autophagy in organelle and protein turnover in skeletal muscles and the pathogenetic implications of deregulated autophagy in muscle disorders. Moreover, I will describe the importance of autophagy in physical performance and in exercise-dependent metabolic adaptations.

Social isolation disrupts hippocampal neurogenesis in young non-human primates.

Social relationships are crucial for the development and maintenance of normal behavior in non-human primates. Animals that are raised in isolation develop abnormal patterns of behavior that persist even when they are later reunited with their parents. In rodents, social isolation is a stressful event and is associated with a decrease in hippocampal neurogenesis but considerably less is known about the effects of social isolation in non-human primates during the transition from adolescence to adulthood. To investigate how social isolation affects young marmosets, these were isolated from other members of the colony for 1 or 3 weeks and evaluated for alterations in their behavior and hippocampal cell proliferation. We found that anxiety-related behaviors like scent-marking and locomotor activity increased after social isolation when compared to baseline levels. In agreement, grooming—an indicative of attenuation of tension—was reduced among isolated marmosets. These results were consistent with increased cortisol levels after 1 and 3 weeks of isolation. After social isolation (1 or 3 weeks), reduced proliferation of neural cells in the subgranular zone of dentate granule cell layer was identified and a smaller proportion of BrdU-positive cells underwent neuronal fate (doublecortin labeling). Our data is consistent with the notion that social deprivation during the transition from adolescence to adulthood leads to stress and produces anxiety-like behaviors that in turn might affect neurogenesis and contribute to the deleterious consequences of prolonged stressful conditions.

Conserved and plant-unique strategies for overcoming endoplasmic reticulum stress

Stress caused by environmental conditions or physiological growth can lead to an accumulation of unfolded proteins in the endoplasmic reticulum (ER) causing ER stress, which in turn triggers a cytoprotective mechanism termed the unfolded protein response (UPR). Under mild-short stress conditions the UPR can restore ER functioning and cell growth, such as reducing the load of unfolded proteins through the upregulation of genes involved in protein folding and in degrading mis-folded proteins, and through autophagy activation, but it can also lead to cell death under prolonged and severe stress conditions. A diversified suite of sensors has been evolved in the eukaryotic lineages to orchestrate the UPR most likely to suit the cell’s necessity to respond to the different kinds of stress in a conserved as well as species-specific manner. In plants three UPR sensors cooperate with non-identical signaling pathways: the protein kinase inositol-requiring enzyme (IRE1), the ER-membrane-associated transcription factor bZIP28, and the GTP-binding protein β1 (AGB1). In this mini-review, we show how plants differ from the better characterized metazoans and fungi, providing an overview of the signaling pathways of the UPR, and highlighting the overlapping and the peculiar roles of the different UPR branches in light of evolutionary divergences in eukaryotic kingdoms.

Effect of prolonged water stress on specialized secondary metabolites, peltate glandular trichomes, and pathway gene expression in Artemisia annua L.

Artemisia annua L. accumulates substantial quantities of unique sesquiternoid artemisinin and related phytomolecules and characteristic essential oil in glandular trichomes, present on its leaves and inflorescence. Water stress is a major concern in controlling plant growth and productivity. In this study, our aim was to find out the modulation of artemisinin and essential oil constituents in plants grown under prolonged water stress conditions. A. annua CIM-Arogya plants grown in pots were subjected to mild (60% ± 5) and moderate (40% ± 5) water stress treatment and continued during entire developmental period. Results revealed that artemisinin, arteannuin-B, artemisinic acid, dihydroartemisinic acid and essential oil content were positively controlled by the growth and development however negatively modulated by water deficit stress. Interestingly, some of minor monoterpenes, all sesquiterpenes and other low molecular weight volatiles of essential oil components were induced by water deficit treatment. Camphor which is the major essential oil constituents did not alter much while 1, 8 cineole was modulated during development of plant as well as under water stress conditions. Water deficit stress induces a decrease in glandular trichome density and size as well. The dynamics of various secondary metabolites is discussed in the light of growth responses, trichomes and pathway gene expression in plants grown under two levels of prolonged water stress conditions.

Silver birch telomeres shorten in tissue culture

Shortening of telomeres has been connected with ageing and loss of cell replication or regeneration capacity. The aim of the present study was to examine potential variation in the length of telomeric repeats in silver birch (Betula pendula Roth) using clonal materials consisting of different-aged outdoor trees and tissue cultures of seven genotypes. The overall average length of telomeres was 13.6 kb (±0.3), the minimum length of repeats in the different genotypes varied from 5.9 kb (±0.5) to 9.6 kb (±0.6), and the maximum length varied from 15.3 kb (±1.1) to 22.8 kb (±0.4). When germinated seeds and leaf and cambium samples from 15- and 80-year-old trees were compared, no correlation of ageing and the length of telomeric repeats was found. Positional variation in the telomere length was, however, observed in the cambium of mature trees, the stem base having longer repeats than the upper parts of the tree. Tissue cultures were found to have shorter telomeres than outdoor trees: prolonged culture, callus culture and stressful conditions were all observed to shorten telomeric repeats and should thus be avoided in birch micropropagation. There were significant differences among the studied silver birch genotypes in their telomere length, and these differences were consistent over the sample types. This is the first report on variation of telomeric repeats in a long-living organism studied with clonal materials.

Novel heteroclitic XBP1 peptides evoking antigen-specific cytotoxic T lymphocytes targeting various solid tumors.

3067 Background: Activation of the unfolded protein response (UPR) allows for tumor cells to survive prolonged endoplasmic reticulum stress and hypoxic conditions. XBP1 is an upstream element and a critical transcriptional activator of the UPR, and its up-regulation in a variety of human solid tumor cancers makes it as a promising immunotherapeutic target. The purpose of these studies was to evaluate immunogenic HLA-A2 XBP1-specific peptides for their ability to elicit cytotoxic T lymphocytes (CTL) against a variety of solid tumor cell lines. Methods: Upon the validation of XBP1 peptides for their strong HLA-A2 bindings and stabilities, peptide-specific CTL were generated ex vivo by repeated stimulation of CD3+ T lymphocytes obtained from HLA-A2+normal donors with XBP1 peptides-pulsed antigen-presenting cells, either dendritic cells or T2 cells. Results: A cocktail of heteroclitic XBP1 US184-192 (YISPWILAV) and heteroclitic XBP1 SP367-375 (YLFPQLISV) peptides with significantly improved HLA-A2 affinity and stability from their native counterparts were used to evoke XBP1 antigen-specific CTL. The CTL were predominantly CD3+CD8+ T cells (>80%) containing a high percentage of Effector Memory (EM; CCR7-CD45RO+) cells, which were distinctively evoked by repeated stimulation with the XBP1 peptides. In addition, the XBP1-CTL displayed a high level of cellular activation (CD69+/CD3+CD8+). The XBP1-CTL demonstrated effective anti-tumor responses including cell proliferation and IFN-g production, as well as degranulation (cytotoxic activity) against HLA-A2+breast cancer (MB231, MCF7), colon cancer (LS180, SW480) and pancreatic cancer (8902, Panc1, PL45) cell lines, which over-express both unspliced and spliced XBP1 antigens. Importantly, the specific anti-tumor activities were detected primarily in the EM CTL subset. Conclusions: These results suggest the immunotherapeutic potential of a cocktail of heteroclitic XBP1 US184-192 and XBP1 SP367-375 peptides to elicit effective anti-tumor responses against various solid tumors, and provide the framework for clinical development of vaccine trials to improve patient outcome.

Mild to prolonged stress increased rice tillering and source-to-sink nutrient translocation under SRI management

System of rice intensification (SRI) is a water-saving agro-technique being popularized in Southern Asia including India. A particular key practice in SRI, reduced water application (no continuous flooding), needs to be more farmer-friendly for its mass adoption under traditional and non-traditional cultivation. A field experiment was conducted maintaining different water regimes throughout the crop season (vegetative as well as reproductive stages) by scheduling irrigation applications at 1, 3, or 5 days after disappearance of ponded water (DADPW), using two different plant spacings and two different varieties. With an increase in the period of water stress, tiller production was increased significantly (P ≤ 0.05) and found to be maximum under prolonged stress, i.e., 5 days after disappearance of ponded water (5 DADPW). Increased tiller production did not result in yield increments, but yield-contributing parameters (panicle weight, grain weight per panicle, filled grain percentage, and test weight) were confirmed as critical determinants of yield. Plant nutrient (NPK) uptake was reduced under stress conditions, but the translocation of phosphorus and potassium from sources to sink was increased significantly in this study. Nutrient utilization efficiency was also enhanced under mild (3 DADPW) to prolonged (5 DADPW) water stress conditions. No significant reduction in yield was recorded under mild water stress, and this resulted in increased water productivity; however, significant yield loss was observed under prolonged water stress (5 DADPW).

Enhanced seed production under prolonged heat stress conditions inArabidopsis thalianaplants deficient in cytosolic ascorbate peroxidase 2

Reactive oxygen species play a key role in the response of plants to abiotic stress conditions. Their level is controlled in Arabidopsis thaliana by a large network of genes that includes the H2O2-scavenging enzymes cytosolic ascorbate peroxidase (APX) 1 and 2. Although the function of APX1 has been established under different growth conditions, genetic evidence for APX2 function, as well as for the mode of cooperation between APX1 and APX2, is very limited. This study characterized the response of Arabidopsis mutants deficient in APX1, APX2, and APX1/APX2 to heat, salinity, light, and oxidative stresses. The findings reveal that deficiency in APX2 resulted in a decreased tolerance to light stress, as well as an enhanced tolerance to salinity and oxidative stresses. Interestingly, plants lacking APX2 were more sensitive to heat stress at the seedling stage, but more tolerant to heat stress at the reproductive stage. Cooperation between APX1 and APX2 was evident during oxidative stress, but not during light, salinity, or heat stress. The findings demonstrate a role for APX2 in the response of plants to light, heat, salinity, and oxidative stresses. The finding that plants lacking APX2 produced more seeds under prolonged heat stress conditions suggests that redundant mechanisms activated in APX2-deficient plants during heat stress play a key role in the protection of reproductive tissues from heat-related damage. This finding is very important because heat-associated damage to reproductive tissues in different crops is a major cause for yield loss in agriculture production worldwide.

Vasopressin in Health and Disease with a Focus on Affective Disorders

The therapies of mood and anxiety disorders are not solved, because current antidepressants have delayed onset of therapeutic action and a significant number of patients are non-responsive. Research on the field was leaning towards neuropeptides as therapeutic targets. Vasopressin (VP) is a hot candidate, as beyond its peripheral actions VP is implicated in interneuronal communication and modulates the hypothalamo-pituitary-adrenal (HPA), the key stress axis, as well as behavioural functions. Affective disorders are stress related disorders and the most frequently occurring abnormality in depressed subjects is hyperactivity of the HPA. VP with nucleus paraventricularis hypothalami origin is a direct adrenocorticotrophin secretagogue through its V1b receptor. VP seems to have special importance under prolonged stress conditions, which are known to be strong predictive factor of depressive disorder and can induce depressive-like symptoms. Preclinical and clinical data summarized in this review underline the importance of VP in the development of anxiety- and depressive-like symptoms. Orally active nonpeptiderg V1b antagonists were developed and seemed to have effective anxiolytic and antidepressant profile in preclinical studies, which was not fully confirmed by clinical observations. It seems that V1a receptors on special brain areas could have same importance. Taken together current knowledge strongly implies an importance of vasopressinergic regulation in affective disorders and consider VP as endogenous anxiogenic/depressogenic substance. However, wide range of side effects could develop as a result of an intervention on the VP system; therefore there is a need for area-specific targeting of VP receptors (e.g. with modified nanoparticles).