Clade III cytokinin response factors share common roles in response to oxidative stress responses linked to cytokinin synthesis

2021 ◽  
Vol 72 (8) ◽  
pp. 3294-3306
Author(s):  
Ariel M Hughes ◽  
H Tucker Hallmark ◽  
Lenka Plačková ◽  
Ondrej Novák ◽  
Aaron M Rashotte

Abstract Cytokinin response factors (CRFs) are transcription factors that are involved in cytokinin (CK) response, as well as being linked to abiotic stress tolerance. In particular, oxidative stress responses are activated by Clade III CRF members, such as AtCRF6. Here we explored the relationships between Clade III CRFs and oxidative stress. Transcriptomic responses to oxidative stress were determined in two Clade III transcription factors, Arabidopsis AtCRF5 and tomato SlCRF5. AtCRF5 was required for regulated expression of >240 genes that are involved in oxidative stress response. Similarly, SlCRF5 was involved in the regulated expression of nearly 420 oxidative stress response genes. Similarities in gene regulation by these Clade III members in response to oxidative stress were observed between Arabidopsis and tomato, as indicated by Gene Ontology term enrichment. CK levels were also changed in response to oxidative stress in both species. These changes were regulated by Clade III CRFs. Taken together, these findings suggest that Clade III CRFs play a role in oxidative stress response as well as having roles in CK signaling.

2021 ◽  
Vol 9 (6) ◽  
pp. 1116
Author(s):  
Laurens Maertens ◽  
Pauline Cherry ◽  
Françoise Tilquin ◽  
Rob Van Houdt ◽  
Jean-Yves Matroule

Bacteria encounter elevated copper (Cu) concentrations in multiple environments, varying from mining wastes to antimicrobial applications of copper. As the role of the environment in the bacterial response to Cu ion exposure remains elusive, we used a tagRNA-seq approach to elucidate the disparate responses of two morphotypes of Caulobacter crescentus NA1000 to moderate Cu stress in a complex rich (PYE) medium and a defined poor (M2G) medium. The transcriptome was more responsive in M2G, where we observed an extensive oxidative stress response and reconfiguration of the proteome, as well as the induction of metal resistance clusters. In PYE, little evidence was found for an oxidative stress response, but several transport systems were differentially expressed, and an increased need for histidine was apparent. These results show that the Cu stress response is strongly dependent on the cellular environment. In addition, induction of the extracytoplasmic function sigma factor SigF and its regulon was shared by the Cu stress responses in both media, and its central role was confirmed by the phenotypic screening of a sigF::Tn5 mutant. In both media, stalked cells were more responsive to Cu stress than swarmer cells, and a stronger basal expression of several cell protection systems was noted, indicating that the swarmer cell is inherently more Cu resistant. Our approach also allowed for detecting several new transcription start sites, putatively indicating small regulatory RNAs, and additional levels of Cu-responsive regulation.


2021 ◽  
Vol 22 (1) ◽  
pp. 458
Author(s):  
Deborah Fratantonio ◽  
Fabio Virgili ◽  
Alessandro Zucchi ◽  
Kate Lambrechts ◽  
Tiziana Latronico ◽  
...  

The term “normobaric oxygen paradox” (NOP), describes the response to the return to normoxia after a hyperoxic event, sensed by tissues as oxygen shortage, and resulting in up-regulation of the Hypoxia-inducible factor 1α (HIF-1α) transcription factor activity. The molecular characteristics of this response have not been yet fully characterized. Herein, we report the activation time trend of oxygen-sensitive transcription factors in human peripheral blood mononuclear cells (PBMCs) obtained from healthy subjects after one hour of exposure to mild (MH), high (HH) and very high (VHH) hyperoxia, corresponding to 30%, 100%, 140% O2, respectively. Our observations confirm that MH is perceived as a hypoxic stress, characterized by the activation of HIF-1α and Nuclear factor (erythroid-derived 2)-like 2 (NRF2), but not Nuclear Factor kappa-light-chain-enhancer of activated B cells (NF-κB). Conversely, HH is associated to a progressive loss of NOP response and to an increase in oxidative stress leading to NRF2 and NF-kB activation, accompanied by the synthesis of glutathione (GSH). After VHH, HIF-1α activation is totally absent and oxidative stress response, accompanied by NF-κB activation, is prevalent. Intracellular GSH and Matrix metallopeptidase 9 (MMP-9) plasma levels parallel the transcription factors activation pattern and remain elevated throughout the observation time. In conclusion, our study confirms that, in vivo, the return to normoxia after MH is sensed as a hypoxic trigger characterized by HIF-1α activation. On the contrary, HH and VHH induce a shift toward an oxidative stress response, characterized by NRF2 and NF-κB activation in the first 24 h post exposure.


Exposome ◽  
2021 ◽  
Author(s):  
Karthik Suresh Arulalan ◽  
Javier Huayta ◽  
Jonathan W Stallrich ◽  
Adriana San-Miguel

Abstract Chemical agents released into the environment can induce oxidative stress in organisms, which is detrimental for health. Although environmental exposures typically include multiple chemicals, organismal studies on oxidative stress derived from chemical agents commonly study exposures to individual compounds. In this work, we explore how chemical mixtures drive the oxidative stress response under various conditions in the nematode C. elegans, by quantitatively assessing levels of gst-4 expression. Our results indicate that naphthoquinone mixtures drive responses differently than individual components, and that altering environmental conditions, such as increased heat and reduced food availability, result in dramatically different oxidative stress responses mounted by C. elegans. When exposed to heat, the oxidative stress response is diminished. Notably, when exposed to limited food, the oxidative stress response specific to juglone is significantly heightened, while identified antagonistic interactions between some naphthoquinone components in mixtures are abolished. This implies that organismal responses to xenobiotics is confounded by environment and stressor interactions. Given the high number of variables under study, and their potential combinations, a simplex centroid design was used to capture such non-trivial response over the design space. This makes the case for the adoption of Design of Experiments approaches as they can greatly expand the experimental space probed in noisy biological readouts, and in combinatorial experiments. Our results also reveal gaps in our current knowledge of the organismal oxidative stress response, which can be addressed by employing sophisticated design of experiments approaches to identify significant interactions.


2020 ◽  
Author(s):  
Nathaniel L. Hepowit ◽  
Kevin N. Pereira ◽  
Jessica M. Tumolo ◽  
Walter J. Chazin ◽  
Jason A. MacGurn

ABSTRACTUbiquitination regulates many different cellular processes, including protein quality control, membrane trafficking, and stress responses. The diversity of ubiquitin functions in the cell is partly due to its ability to form chains with distinct linkages that can alter the fate of substrate proteins in unique ways. The complexity of the ubiquitin code is further enhanced by post-translational modifications on ubiquitin itself, the biological functions of which are not well understood. Here, we present genetic and biochemical evidence that serine 57 (Ser57) phosphorylation of ubiquitin functions in stress responses in Saccharomyces cerevisiae, including the oxidative stress response. We also identify and characterize the first known Ser57 ubiquitin kinases in yeast and human cells, and we report that two Ser57 ubiquitin kinases regulate the oxidative stress response in yeast. These studies implicate ubiquitin phosphorylation at the Ser57 position as an important modifier of ubiquitin function, particularly in response to proteotoxic stress.


2021 ◽  
Vol 5 (Supplement_1) ◽  
pp. 684-684
Author(s):  
Raul Castro-Portuguez ◽  
Jeremy Meyers ◽  
Sam Freitas ◽  
Hope Dang ◽  
Emily Turner ◽  
...  

Abstract Aging is characterized by a progressive decline in the normal physiological functions of an organism, ultimately leading to mortality. Metabolic changes throughout the aging process disrupt the balance and homeostasis of the cell. The kynurenine metabolic pathway is the sole de novo biosynthetic pathway for producing NAD+ from ingested tryptophan. Altered kynurenine pathway activity is associated with both aging and a variety of age-associated diseases, and kynurenine-based interventions can extend lifespan in Caenorhabditis elegans. Our laboratory recently demonstrated knockdown of the kynurenine pathway enzymes kynureninase (KYNU) or 3-hydroxyanthranilic acid dioxygenase (HAAO) increases lifespan by 20-30% in C elegans. However, the mechanism of how these interventions may modulate response against different stressors during the aging process has yet to be explored. Fluorescent reporter strains show the stress-responsive transcription factors skn-1 (ortholog of NRF2/NFE2L2; oxidative stress response) and hif-1 (ortholog of HIF1A; hypoxic stress response) to be highly upregulated when the kynurenine pathway is inhibited. We also demonstrated the increase expression of gst-4 and gcs-1 (transcriptional targets skn-1), which are involved in production of the antioxidant glutathione (GSH), as well as upregulation of cysl-2 (transcriptional target of hif-1), a regulator of cysteine biosynthesis from serine. We hypothesize that lifespan extension resulting from kynurenine pathway inhibition is mediated, at least in part, by upregulation of these transcription factors, providing elevated defense against oxidative stress and hypoxic stress.


2019 ◽  
Vol 7 (8) ◽  
pp. 225 ◽  
Author(s):  
Shao ◽  
Tu ◽  
Wang ◽  
Jiang ◽  
Ma ◽  
...  

Oxidative stress response protects organisms from deleterious effects of reactive oxygen species (ROS), which can damage cellular components and cause disturbance of the cellular homeostasis. Although the defensive biochemical mechanisms have been extensively studied in yeast and other filamentous fungi, little information is available about Aspergillus oryzae. We investigated the effect of two oxidant agents (menadione sodium bisulfite, MSB, and hydrogen peroxide, H2O2) on cellular growth and antioxidant enzyme induction in A. oryzae. Results indicated severe inhibition of biomass and conidia production when high concentration of oxidants was used. Transcriptomic analysis showed an up-regulated expression of genes involved in oxidoreduction, such as catalase, glutathione peroxidase, and superoxide dismutase. In addition, it was observed that oxidative stress stimuli enhanced the expression of Yap1 and Skn7 transcription factors. Further, metabolomic analysis showed that glutathione content was increased in the oxidative treatments when compared with the control. Moreover, the content of unsaturated fatty acid decreased with oxidative treatment accompanying with the down-regulated expression of genes involved in linoleic acid biosynthesis. This study provided a global transcriptome characterization of oxidative stress response in A. oryzae, and can offer multiple target genes for oxidative tolerance improvement via genetic engineering.


2009 ◽  
Vol 184 (1) ◽  
pp. 45-55 ◽  
Author(s):  
Ashraf N. Malhas ◽  
Chiu Fan Lee ◽  
David J. Vaux

Interaction of lamins with chromatin and transcription factors regulate transcription. Oct-1 has previously been shown to colocalize partly with B-type lamins and is essential for transcriptional regulation of oxidative stress response genes. Using sequential extraction, co-immunoprecipitation (IP), fluorescence loss in photobleaching, and fluorescence resonance energy transfer, we confirm Oct-1–lamin B1 association at the nuclear periphery and show that this association is lost in Lmnb1Δ/Δ cells. We show that several Oct-1–dependent genes, including a subset involved in oxidative stress response, are dysregulated in Lmnb1Δ/Δ cells. Electrophoretic mobility shift assay and chromatin IP reveal that Oct-1 binds to the putative octamer-binding sequences of the dysregulated genes and that this activity is increased in cells lacking functional lamin B1. Like Oct1−/− cells, Lmnb1Δ/Δ cells have elevated levels of reactive oxygen species and are more susceptible to oxidative stress. Sequestration of Oct-1 at the nuclear periphery by lamin B1 may be a mechanism by which the nuclear envelope can regulate gene expression and contribute to the cellular response to stress, development, and aging.


2019 ◽  
Author(s):  
Jay Leipheimer ◽  
Amanda L. M. Bloom ◽  
Christopher S. Campomizzi ◽  
Yana Salei ◽  
John C. Panepinto

AbstractCryptococcus neoformans is one of the few environmental fungi that can survive within a mammalian host and cause disease. Although many of the factors responsible for establishing virulence have been recognized, how they are expressed in response to certain host derived cellular stresses is rarely addressed. Here we characterize the temporal translational response of C. neoformans to oxidative stress. We find that translation is largely inhibited through the phosphorylation of the critical initiation factor elF2α by a sole kinase. Preventing elF2α mediated translational suppression resulted in growth sensitivity to hydrogen peroxide (H2O2). Our work suggests that translational repression in response to H2O2 partly facilitates oxidative stress adaptation by accelerating the decay of abundant non-stress related transcripts while facilitating the proper expression of critical oxidative stress response factors. Carbon starvation, which seems to induce translational suppression that is independent elF2α, partly restored transcript decay and the expression of the critical oxidative stress response transcript Thioredoxin Reductase 1 (TRR1). Our results illustrate translational suppression as a key determinant of select mRNA decay, gene expression, and subsequent survival in response to oxidative stress.ImportanceFungal survival in a mammalian host requires the coordinated expression and downregulation of a large cohort of genes in response to cellular stresses. Initial infection with C. neoformans occurs at the lungs, where it interacts with host macrophages. Surviving macrophage derived cellular stresses, such as the production of reactive oxygen and nitrogen species, is believed to promote dissemination into the central nervous system. Therefore, investigating how an oxidative stress resistant phenotype is brought about in C. neoformans furthers our understanding of not only fungal pathogenesis but also unveils mechanisms of stress induced gene reprogramming. We discovered that H2O2 derived oxidative stress resulted in severe translational suppression and that this suppression was necessary for the accelerated decay and expression of tested transcripts. Surprisingly, compounding oxidative stress with carbon starvation resulted in a decrease in peroxide mediated killing, revealing unexpected synergy between stress responses.


2020 ◽  
Author(s):  
Vishantie Dostal ◽  
Silas D. Wood ◽  
Cody T. Thomas ◽  
Yu Han ◽  
Edward Lau ◽  
...  

AbstractThe heart is sensitive to oxidative damage but a global view on how the cardiac proteome responds to oxidative stressors has yet to fully emerge. Using quantitative tandem mass spectrometry, we assessed the effects of acute exposure of the oxidative stress inducer paraquat on protein expression in mouse hearts. We observed widespread protein expression changes in the paraquat-exposed heart especially in organelle-containing subcellular fractions. During cardiac response to acute oxidative stress, proteome changes are consistent with a rapid reduction of mitochondrial metabolism, coupled with activation of multiple antioxidant proteins, reduction of protein synthesis and remediation of proteostasis. In addition to differential expression, we saw evidence of spatial reorganizations of the cardiac proteome including the translocation of hexokinase 2 to more soluble fractions. Treatment with the antioxidants Tempol and MitoTEMPO reversed many proteomic signatures of paraquat but this reversal was incomplete. We also identified a number of proteins with unknown function in the heart to be triggered by paraquat, suggesting they may have functions in oxidative stress response. Surprisingly, protein expression changes in the heart correlate poorly with those in the lung, consistent with differential sensitivity or stress response in these two organs. The results provide insights into oxidative stress responses in the heart and may avail the search for new therapeutic targets.


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