Stress-responsive Transcription Factor Research Articles

Ectopic expression of common bean ERF transcription factor PvERF35 promotes salt stress tolerance in tobacco.

In the present study, a TINY-like AP2/ERF gene, PvERF35i, was amplified from common bean (Phaseolus vulgaris L.), cloned and functionally characterized by overexpressing in tobacco cv. Petite havana. Transgenic plants overexpressing PvERF35 were generated using Agrobacterium-mediated transformation and used to evaluate the possible roles of the transgene under salt stress conditions. Evaluation of transgenics was completed using both molecular and biochemical analysis. PCR, Southern blot and RT-qPCR assays revealed the correct integration and enhanced expression of the transgene. Physiological and biochemical analysis of transgenic plants showed their better performance compared to the wild type in terms of germination and survival rates and root and shoot growth under salt stress treatment (200mM NaCl). Having a high concentration of proline, APX and POX, the PvERF35 overexpressed plants were physiologically and morphologically less affected by salt stress application. In silico promoter analysis of the PvERF35 gene led to identification of important cis-regulatory elements, MYB, MYC and TGACG-motif, annotated with salt response of plants. The protein-protein interaction network showed that there was a strong association between ABC transporter proteins and PvERF35 protein. Salt stress-related miRNA, miRNA156 and miRNA159, targeting PvERF35 were identified using in silico target finding analysis. These findings suggest that PvERF35 functions as a stress-responsive transcription factor in differential modulation of salt stress tolerance and may have applications in the engineering of economically important crops.

Dissecting the Crosstalk between NRF2 Signaling and Metabolic Processes in Cancer.

Simple SummaryThe stress-responsive transcription factor NRF2 (nuclear factor-erythroid 2 p45-related factor 2) directs cellular metabolic processes that can have diverse effects in the context of cancer. This review addresses how NRF2 and its negative regulator KEAP1 (Kelch-like ECH-associated protein 1) collectively modulate and respond to metabolism. We highlight NRF2-regulated processes relevant to the antioxidant system, cellular proliferation, and survival, including metabolism of amino acids, lipids, NADPH (reduced nicotinamide adenine dinucleotide phosphate), iron, and heme. We also review the stabilization of NRF2 by electrophiles, metabolites, and autophagy. Finally, we discuss topics that warrant further investigation into the KEAP1/NRF2 pathway’s role in tumor progression.The transcription factor NRF2 (nuclear factor-erythroid 2 p45-related factor 2 or NFE2L2) plays a critical role in response to cellular stress. Following an oxidative insult, NRF2 orchestrates an antioxidant program, leading to increased glutathione levels and decreased reactive oxygen species (ROS). Mounting evidence now implicates the ability of NRF2 to modulate metabolic processes, particularly those at the interface between antioxidant processes and cellular proliferation. Notably, NRF2 regulates the pentose phosphate pathway, NADPH production, glutaminolysis, lipid and amino acid metabolism, many of which are hijacked by cancer cells to promote proliferation and survival. Moreover, deregulation of metabolic processes in both normal and cancer-based physiology can stabilize NRF2. We will discuss how perturbation of metabolic pathways, including the tricarboxylic acid (TCA) cycle, glycolysis, and autophagy can lead to NRF2 stabilization, and how NRF2-regulated metabolism helps cells deal with these metabolic stresses. Finally, we will discuss how the negative regulator of NRF2, Kelch-like ECH-associated protein 1 (KEAP1), may play a role in metabolism through NRF2 transcription-independent mechanisms. Collectively, this review will address the interplay between the NRF2/KEAP1 complex and metabolic processes.

Tomato BZR/BES transcription factor SlBZR1 positively regulates BR signaling and salt stress tolerance in tomato and Arabidopsis

Brassinosteroids (BRs) play critical roles in plant growth and development, as well as in responses to abiotic stresses. The BRASSINAZOLE RESISTANT 1 (BZR1) and BRI1-EMS-SUPPRESSOR 1 (BES1) families of transcription factors have been elucidated largely in Arabidopsis and rice but not in other plant species. Here, we studied the functional characterization of a tomato (Solanum lycopersicum) BZR homolog gene, SlBZR1, in BR-regulated plant growth and tolerance to salt stress. SlBZR1 was highly expressed in the flowers and developing fruits of tomato. Both SlBZR1 and SlBZR1D (proline to leucine mutation at the 239th amino acid of SlBZR1) were transcriptional repressors and localized in the nucleus. SlBZR1 or SlBZR1D could interact with SlMYB30, SlMYBL2, SlPIF4, SlHAT1, SlIWS1 and SlREF6 in tomato. Overexpression of SlBZR1D enhanced the BR response and improved tolerance to salt stress in Arabidopsis, consistent with the phenotype of the Arabidopsis bes1-D mutant. Moreover, SlBZR1D-overexpressing tomato lines showed a short plant height, smaller and curly leaves, and delayed flowering. Additionally, SlBZR1D positively regulated salt tolerance in tomato and upregulated the expression of multiple stress-related genes. Our study provides new insights for understanding the function and mechanism of BZR transcription factors in BR-regulated plant growth and abiotic stress responses.

Structure, Antioxidant and Anti-inflammatory Activities of the (4R)- and (4S)-epimers of S-Carboxymethyl-L-cysteine Sulfoxide.

S-Carboxymethyl-L-cysteine (CMC) is an antioxidant and mucolytic commonly prescribed to patients with chronic obstructive pulmonary disease. In humans, CMC is rapidly metabolized to S-carboxymethyl-L-cysteine sulfoxide (CMCO). In this study, we assessed structural and functional similarities between CMC and CMCO. X-Ray diffraction analysis provided detailed structural information about CMCO, which exists as a 1:1 mixture of epimers, due to the emergence of a new chiral center at the sulfur atom. Both CMC and CMCO epimers protected model DNA from copper-mediated hydroxyl free radical damage. Using an insulated transposable construct for reporting activity of the cellular stress-responsive transcription factors Nrf2, p53, NF-κB, and AP-1, we demonstrate that CMCO, especially its (4R)-epimer, is comparable to CMC in their ability to mitigate the effects of oxidative stress and pro-inflammatory stimuli in human alveolar (A549) and bronchial epithelial (BEAS-2B) cells. The results of these in vitro studies suggest that CMCO retains, at least partially, the antioxidant potential of CMC and may inform pharmacodynamics considerations of CMC use in clinics.

Nutrient status shapes selfish mitochondrial genome dynamics across different levels of selection.

Cooperation and cheating are widespread evolutionary strategies. While cheating confers an advantage to individual entities within a group, competition between groups favors cooperation. Selfish or cheater mitochondrial DNA (mtDNA) proliferates within hosts while being selected against at the level of host fitness. How does environment shape cheater dynamics across different selection levels? Focusing on food availability, we address this question using heteroplasmic Caenorhabditis elegans. We find that the proliferation of selfish mtDNA within hosts depends on nutrient status stimulating mtDNA biogenesis in the developing germline. Interestingly, mtDNA biogenesis is not sufficient for this proliferation, which also requires the stress-response transcription factor FoxO/DAF-16. At the level of host fitness, FoxO/DAF-16 also prevents food scarcity from accelerating the selection against selfish mtDNA. This suggests that the ability to cope with nutrient stress can promote host tolerance of cheaters. Our study delineates environmental effects on selfish mtDNA dynamics at different levels of selection.

Abstract PO-051: Intracellular delivery of nuclear localization signal suppresses COVID-19 mediated inflammation by regulating expression of cytokines/chemokines

Abstract The outbreak of coronavirus disease 19 (COVID-19), caused by the recently identified coronavirus named SARS-CoV-2, is leading patients to death (mortality: ~7%) because of cytokine storm. COVID-19 induces excessive secretion of proinflammatory cytokines and chemokines accompanied by the disruption of the bronchi and alveoli, which could ultimately develop into permanent lung impairments such as pulmonary fibrosis. To regulate the uncontrolled expression of proinflammatory cytokines/chemokines, improved cell-permeable nuclear import inhibitor (iCP-NI) has been developed by fusing sequence-optimized hydrophobic cell-penetrating peptide (CPP), namely advanced macromolecule transduction domain (aMTD) with nuclear localization signal (NLS) of stress responsive transcription factors (SRTFs: NF-κB, STAT1/3, AP-1, and NFAT). Intracellularly delivered NLS is supposed to suppress expression of proinflammatory cytokines/chemokines by inhibiting transport of SRTFs from cytoplasm into nucleus. iCP-NI regulated expression of cytokines (TNF-α: -79%, IL-6: -91%, IL-12: -110% and IL-10: +574%) and chemokines (MCP-1: -89%) in bronchoalveolar lavage fluids (BALFs) from RNA virus infection mimetic pneumonitis animals that were induced with inhalation of RNA structure molecule, poly I:C. iCP-NI also significantly decreased pulmonary fibrosis (-61%) in bleomycin-induced pulmonary fibrosis animals. Moreover, iCP-NI protected leukocytes (CD3+ T cell: 100%, CD4+/CD3+ T cell: 96%, B220+ B cell: 85%, CD45+ macrophage: 100%) and reduced apoptotic splenocytes (-97%) in staphylococcal enterotoxin B (SEB) and poly I:C-induced acute pneumonitis animals. These results suggest that iCP-NI has potential as a novel therapeutic measurement for inflammation caused by various infectious diseases including COVID-19 accompanied with cytokine storm and severe sepsis. Citation Format: Danbi Lee, Sanghyeon Yu, Misuk Baek, Jieun Kim, Mingu Kang, Hakyoung Park, Jaewook Lee, Seokwon Lee, Junghun Kwak, Hyemin Yu, Seungwoo Lee, Sujeong Kim, Hyewon Lee, Dasom Shin, Boram Kim, Minyoung Jung, Youngsil Choi, Daewoong Jo, Gyunam Kim, Dongho Kim. Intracellular delivery of nuclear localization signal suppresses COVID-19 mediated inflammation by regulating expression of cytokines/chemokines [abstract]. In: Proceedings of the AACR Virtual Meeting: COVID-19 and Cancer; 2020 Jul 20-22. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(18_Suppl):Abstract nr PO-051.

De novo assembly of transcriptome and genome-wide identification reveal GA3 stress-responsive WRKY transcription factors involved in fiber formation in jute (Corchorus capsularis)

BackgroundWRKY is a group of transcription factors (TFs) that play a vital role in plant growth, development, and stress tolerance. To date, none of jute WRKY (CcWRKY) genes have been identified, even if jute (Corchorus capsularis) is one of the most important natural fiber crops in the world. Little information about the WRKY genes in jute is far from sufficient to understand the molecular mechanism of bast fiber biosynthesis.ResultsA total of 244,489,479 clean reads were generated using Illumina paired-end sequencing. De novo assembly yielded 90,982 unigenes with an average length of 714 bp. By sequence similarity searching for known proteins, 48,896 (53.74%) unigenes were annotated. To mine the CcWRKY TFs and identify their potential function, the search for CcWRKYs against the transcriptome data of jute was performed, and a total of 43 CcWRKYs were identified in this study. The gene structure, phylogeny, conserved domain and three-dimensional structure of protein were analyzed by bioinformatics tools of GSDS2.0, MEGA7.0, DNAMAN5.0, WebLogo 3 and SWISS-MODEL respectively. Phylogenetic analysis showed that 43 CcWRKYs were divided into three groups: I, II and III, containing 9, 28, and 6 members respectively, according to the WRKY conserved domain features and the evolution analysis with Arabidopsis thaliana. Gene structure analysis indicated that the number of exons of these CcWRKYs varied from 3 to 11. Among the 43 CcWRKYs, 10, 2, 2, and 14 genes showed higher expression in leaves, stem sticks, stem barks, and roots at the vigorous vegetative growth stage, respectively. Moreover, the expression of 21 of 43 CcWRKYs was regulated significantly with secondary cell wall biosynthesis genes using FPKM and RT-qPCR by GA3 stress to a typical GA3 sensitive dwarf germplasm in comparison to an elite cultivar in jute. The Cis-element analysis showed that promoters of these 21 CcWRKYs had 1 to 4 cis-elements involved in gibberellin-responsiveness, suggesting that they might regulate the development of bast fiber in response to GA3 stress.ConclusionsA total of 43 CcWRKYs were identified in jute for the first time. Analysis of phylogenetic relationship and gene structure revealed that these CcWRKYs might have a functional diversity. Expression analysis showed 21 TFs as GA3 stress responsive genes. The identification of these CcWRKYs and the characterization of their expression pattern will provide a basis for future clarification of their functions in bast fiber development in jute.

Redefining proteostasis transcription factors in organismal stress responses, development, metabolism, and health.

Eukaryotic organisms have evolved complex and robust cellular stress response pathways to ensure maintenance of proteostasis and survival during fluctuating environmental conditions. Highly conserved stress response pathways can be triggered and coordinated at the cell-autonomous and cell-nonautonomous level by proteostasis transcription factors, including HSF1, SKN-1/NRF2, HIF1, and DAF-16/FOXO that combat proteotoxic stress caused by environmental challenges. While these transcription factors are often associated with a specific stress condition, they also direct "noncanonical" transcriptional programs that serve to integrate a multitude of physiological responses required for development, metabolism, and defense responses to pathogen infections. In this review, we outline the established function of these key proteostasis transcription factors at the cell-autonomous and cell-nonautonomous level and discuss a newly emerging stress responsive transcription factor, PQM-1, within the proteostasis network. We look beyond the canonical stress response roles of proteostasis transcription factors and highlight their function in integrating different physiological stimuli to maintain cytosolic organismal proteostasis.

Regulation of AtKUP2 Expression by bHLH and WRKY Transcription Factors Helps to Confer Increased Salt Tolerance to Arabidopsis thaliana Plants.

Potassium transporters play an essential role in maintaining cellular ion homeostasis, turgor pressure, and pH, which are critical for adaptation under salt stress. We identified a salt responsive Avicennia officinalis KUP/HAK/KT transporter family gene, AoKUP2, which has high sequence similarity to its Arabidopsis ortholog AtKUP2. These genes were functionally characterized in mutant yeast cells and Arabidopsis plants. Both AoKUP2 and AtKUP2 were induced by salt stress, and AtKUP2 was primarily induced in roots. Subcellular localization revealed that AoKUP2 and AtKUP2 are localized to the plasma membrane and mitochondria. Expression of AtKUP2 and AoKUP2 in Saccharomyces cerevisiae mutant strain (BY4741 trk1Δ::loxP trk2Δ::loxP) helped to rescue the growth defect of the mutant under different NaCl and K+ concentrations. Furthermore, constitutive expression of AoKUP2 and AtKUP2 conferred enhanced salt tolerance in Arabidopsis indicated by higher germination rate, better survival, and increased root and shoot length compared to the untreated controls. Analysis of Na+ and K+ contents in the shoots and roots showed that ectopic expression lines accumulated less Na+ and more K+ than the WT. Two stress-responsive transcription factors, bHLH122 and WRKY33, were identified as direct regulators of AtKUP2 expression. Our results suggest that AtKUP2 plays a key role in enhancing salt stress tolerance by maintaining cellular ion homeostasis.

Abstract 5565: Skin-targeted combinatorial DNA immunization overcomes tumor resistance to PD1 therapy

Abstract Despite the remarkable treatment benefits associated with interventional checkpoint blockade for solid tumors, many patients ultimately progress on therapy. The development of novel strategies that can overcome resistance to checkpoint therapy remains a considerable unmet clinical need. In this context, we developed a novel tumor immunization strategy that is multifunctional and combines co-delivery of plasmid DNA encoding antigen and molecules driving immunostimulatory function and antigen targeting. Specifically, we targeted expression of plasmid DNA encoding the stress response transcription factor XBP1 and the melanoma-associated antigen TRP2 fused to heat shock protein HSP70. Transient skin-localized expression promotes a pro-immunogenic skin microenvironment and the induction, recruitment, and maintenance of Type-1 cytotoxic CD8 T cells (Tc1), including Tc1 T-cell infiltrates within the tumor microenvironment (TME), and tumor regression in a PD1-resistant mouse melanoma model. These data suggest a novel therapeutic strategy in which combined effects of localized XBP1 and HSP70 antigen conjugation establishes a PD1-responsive TME for effective and durable treatment of PD1-resistant cancers. Citation Format: Louis D. Falo. Skin-targeted combinatorial DNA immunization overcomes tumor resistance to PD1 therapy [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5565.

Venetoclax causes metabolic reprogramming independent of BCL-2 inhibition

BH3-mimetics are a new class of anti-cancer drugs that inhibit anti-apoptotic Bcl-2 proteins. In doing so, BH3-mimetics sensitise to cell death. Venetoclax is a potent, BCL-2 selective BH3-mimetic that is clinically approved for use in chronic lymphocytic leukaemia. Venetoclax has also been shown to inhibit mitochondrial metabolism, this is consistent with a proposed role for BCL-2 in metabolic regulation. We used venetoclax to understand BCL-2 metabolic function. Similar to others, we found that venetoclax inhibited mitochondrial respiration. In addition, we also found that venetoclax impairs TCA cycle activity leading to activation of reductive carboxylation. Importantly, the metabolic effects of venetoclax were independent of cell death because they were also observed in apoptosis-resistant BAX/BAK-deficient cells. However, unlike venetoclax treatment, inhibiting BCL-2 expression had no effect on mitochondrial respiration. Unexpectedly, we found that venetoclax also inhibited mitochondrial respiration and the TCA cycle in BCL-2 deficient cells and in cells lacking all anti-apoptotic BCL-2 family members. Investigating the basis of this off-target effect, we found that venetoclax-induced metabolic reprogramming was dependent upon the integrated stress response and ATF4 transcription factor. These data demonstrate that venetoclax affects cellular metabolism independent of BCL-2 inhibition. This off-target metabolic effect has potential to modulate venetoclax cytotoxicity.

Role of heat shock transcription factor 2 in the NMDA-dependent neuroplasticity induced by chronic ethanol intake in mouse hippocampus.

Ethanol consumption impairs learning and memory through disturbances of NMDA-type glutamate receptor-dependent synaptic plasticity (long-term depression [LTD] and long-term potentiation [LTP]) in the hippocampus. Recently, we demonstrated that two ethanol binge-like episodes in young adult rats selectively blocked NMDA-LTD in hippocampal slices, increased NMDA receptor sensitivity to a GluN2B subunit antagonist, and induced cognitive deficits. Here, using knockout adult mice, we show that a stress-responsive transcription factor of the heat shock factor family, HSF2, which is involved in the perturbation of brain development induced by ethanol, participates in these processes. In the absence of ethanol, hsf2-/- mice show a selective loss of LTD in the hippocampus, which is associated with an increased sensitivity of NMDA-field excitatory postsynaptic potentials (fEPSPs) to a GluN2B antagonist, compared with wild-type (WT) mice. These results suggest that HSF2 is required for proper glutamatergic synaptic transmission and LTD plasticity. After 1 month of chronic ethanol consumption in a two-bottle choice paradigm, WT mice showed an increase in hippocampal synaptic transmission, an enhanced sensitivity to GluN2B antagonist, and a blockade of LTD. In contrast, such modulation of synaptic transmission and plasticity were absent in hsf2-/- mice. We conclude that HSF2 is an important mediator of both glutamatergic neurotransmission and synaptic plasticity in basal conditions and also mediates ethanol-induced neuroadaptations of the hippocampus network after chronic ethanol intake.

Genome-wide identification, genomic organization and expression profiles of SlARR-B gene family in tomato

The type-B authentic response regulators (ARR-Bs) function as positive regulators of cytokinin signal transduction and play important roles in abiotic stress resistance and plant development. However, little of ARR-B family is known in tomato. In this study, we performed a comprehensive analysis of ARR-B family factors in tomato. In total, 12 genes encoding ARR-B transcription factors (named as SlARR-B1-SlARR-B12) were identified from tomato. We analyzed the structures, chromosome locations, phylogeny, protein motifs, and expression profiles of these SlARR-B genes. Gene structure analysis showed that 5-12 exons and 4-11 introns existed in the SlARR-B genes. These SlARR-B genes were asymmetrically distributed on eight chromosomes in tomato. Phylogenetic tree of SlARR-B genes from tomato and other plant species revealed that SlARR-B genes were classified into 6 subfamilies. SlARR-B proteins had typical conserved domains, including Motif 1 and Motif 2. The investigation of the expression profiles of SlARR-B genes in all the examined tissues demonstrated that these genes were differentially expressed, including roots, stems, leaves, flowers, and fruits at developmental stages. Notably, the expression of SlARR-B11 and SlARR-B12 exhibited high expression levels in flowers. Each gene was induced by at least one of different phytohormones (SA, IAA, ABA, IBA, 6-BA, JA, GA, and ETH) and four abiotic stress treatments (heat, drought, salt, and cold). This study sets a good foundation for further characterization of the SlARR-B transcription factors in plant development and abiotic stress responses of tomato.

NRF2, a Transcription Factor for Stress Response and Beyond.

Nuclear factor erythroid 2-related factor 2 (NRF2) is a transcription factor that regulates the cellular defense against toxic and oxidative insults through the expression of genes involved in oxidative stress response and drug detoxification. NRF2 activation renders cells resistant to chemical carcinogens and inflammatory challenges. In addition to antioxidant responses, NRF2 is involved in many other cellular processes, including metabolism and inflammation, and its functions are beyond the originally envisioned. NRF2 activity is tightly regulated through a complex transcriptional and post-translational network that enables it to orchestrate the cell’s response and adaptation to various pathological stressors for the homeostasis maintenance. Elevated or decreased NRF2 activity by pharmacological and genetic manipulations of NRF2 activation is associated with many metabolism- or inflammation-related diseases. Emerging evidence shows that NRF2 lies at the center of a complex regulatory network and establishes NRF2 as a truly pleiotropic transcription factor. Here we summarize the complex regulatory network of NRF2 activity and its roles in metabolic reprogramming, unfolded protein response, proteostasis, autophagy, mitochondrial biogenesis, inflammation, and immunity.

Supplementation of 17β-Estradiol Normalizes Rapid Gastric Emptying by Restoring Impaired Nrf2 and nNOS Function in Obesity-Induced Diabetic Ovariectomized Mice.

Gastroparesis (Gp) is a multifactorial condition commonly observed in females and is characterized by delayed or rapid gastric emptying (GE). The role of ovarian hormones on GE in the pathogenesis of obesity induced type 2 diabetes mellitus (T2DM) is completely unknown. The aims of our study are to investigate whether supplementation of 17β-estradiol (E2) or progesterone (P4) restores impaired nuclear factor erythroid 2-related factor 2 (Nrf2, an oxidative stress-responsive transcription factor) and nitric oxide (NO)-mediated gastric motility in ovariectomized (OVX) mice consuming a high-fat diet (HFD, a model of T2DM). Groups of OVX+HFD mice were administered daily subcutaneous doses of either E2 or P4 for 12 weeks. The effects of E2 and P4 on body weight, metabolic homeostasis, solid GE, gastric antrum NO-mediated relaxation, total nitrite levels, neuronal nitric oxide synthase (nNOSα), and its cofactor expression levels were assessed in OVX+HFD mice. HFD exacerbated hyperglycemia and insulinemia while accelerating GE (p < 0.05) in OVX mice. Exogenous E2, but not P4, attenuated rapid gastric emptying and restored gastric nitrergic relaxation, total nitrite levels, nNOSα, and cofactor expression via normalizing Nrf2-Phase II enzymes, inflammatory response, and mitogen-activated protein kinase (MAPK) protein expression in OVX+HFD mice. We conclude that E2 is beneficial in normalizing metabolic homeostasis and gastric emptying in obese, diabetic OVX mice consuming a fat-rich diet.

Transgenic Approaches of Improving Tomato (Solanum lycopersicum) to Salt Stress Tolerance

Environmental stresses mainly drought and salinity are now becoming potential threats for global agricultural production. Being a tropical crop, tomato is produced in warm and dry regions of the world, where salt stress is limiting the yield potential of the crop. Plant defense response to salt tolerance is very complex in which many morphological, physiological, and molecular modifications are enhanced. Although considerable effort has been made in developing salt tolerant tomato cultivars through conventional breeding, it has met with limited success due to the complex, multigenic nature of the trait and developmental stage regulated phenomenon of the salt tolerance response. Genetic engineering is an alternative approach to understand the mechanisms of salinity tolerance and apply the knowledge obtained to generate salt tolerant tomatoes. This review aims to highlight the latest developments in biotechnological techniques of improving tomato tolerance to salt stress. Recently, there have been many attempts to enhance tomato tolerance to salt stress including introduction and/or modifications of various genes involved in regulatory, signaling pathways, detoxifying enzymes and genes encoding functional and structural proteins. Plasma membrane Na+/H+ antiporters (SOS) and vacuolar Na+/H+ antiporters (NHXn), Dehydrin (DHN), Choline Oxidase (codA), and ROS scavengers have been the major genes targeted in many studies for developing salt stress tolerant transgenic tomato. Moreover, promising results have reported on the identification and use of various abiotic stress responsive elements and/or transcription factors such as SlDREB2, SL-ZH13, Sl-ERF.B.3, AREB, NAC-Type and WRKY TFs, which positively regulate the expression of the downstream genes in transgenic tomato with response to salt stress. Keywords׃ Salt Stress, Tomato, Transgenic, Transcription Factor DOI: 10.7176/JBAH/10-14-01 Publication date:July 31st 2020

Molecular regulation and function of FoxO3 in chronic kidney disease.

FOXOs are transcription factors that regulate downstream target genes to counteract to cell stress. Here we review the function and regulation of FOXO transcription factors, the mechanism of FOXO3 activation in the kidney, and the role of FOXO3 in delaying the development of chronic kidney disease (CKD). Progressive renal hypoxia from vascular dropout and metabolic perturbation is a pathogenic factor for the initiation and development of CKD. Hypoxia and low levels of α-ketoglutarate generated from the TCA cycle inhibit prolyl hydroxylase domain (PHD)-mediated prolyl hydroxylation of FoxO3, thus reducing FoxO3 protein degradation via the ubiquitin proteasomal pathway, similar to HIF stabilization under hypoxic conditions. FoxO3 accumulation and nuclear translocation activate two key cellular defense mechanisms, autophagy and antioxidative response in renal tubular cells, to reduce cell injury and promote cell survival. FoxO3 directly activates the expression of Atg proteins, which replenishes core components of the autophagic machinery to allow sustained autophagy in the chronically hypoxic kidney. FoxO3 protects mitochondria by stimulating the expression of superoxide dismutase 2 (SOD2), as tubular deletion of FoxO3 in mice results in reduced SOD2 levels and profound mitochondrial damage. Knowledge gained from animal studies may help understand the function of stress responsive transcription factors that could be targeted to prevent or treat CKD.

Neutralization of HSF1 in cells from PIK3CA-related overgrowth spectrum patients blocks abnormal proliferation

PIK3CA-related overgrowth spectrum is caused by mosaicism mutations in the PIK3CA gene. These mutations, which are also observed in various types of cancer, lead to a constitutive activation of the PI3K/AKT/mTOR pathway, increasing cell proliferation. Heat shock transcription factor 1 (HSF1) is the major stress-responsive transcription factor. Recent findings indicate that AKT phosphorylates and activates HSF1 independently of heat-shock in breast cancer cells. Here, we aimed to investigate the role of HSF1 in PIK3CA-related overgrowth spectrum. We observed a higher rate of proliferation and increased phosphorylation of AKT and p70S6K in mutant fibroblasts than in control cells. We also found elevated phosphorylation and activation of HSF1, which is directly correlated to AKT activation. Specific AKT inhibitors inhibit HSF1 phosphorylation as well as HSF1-dependent gene transcription. Finally, we demonstrated that targeting HSF1 with specific inhibitors reduced the proliferation of mutant cells. As there is currently no curative treatment for PIK3CA-related overgrowth spectrum, our results identify HSF1 as a new potential therapeutic target.

Inhibition of neural stem cell aging through the transient induction of reprogramming factors.

Adult stem cells age during long-term in vitro culture, and neural stem cells (NSCs), which can self-renew and differentiate into neurons and glial cells, also display reduced differentiation potential after repeated passaging. However, the mechanistic details underlying this process remain unclear. In this study, we found that long-term in vitro culture of NSCs resulted in aging-related upregulation of inflammatory- and endoplasmic reticulum (ER) stress-related genes, including the proinflammatory cytokines interleukin (IL)1β and IL6, the senescence-associated enzyme matrix metallopeptidase 13 (MMP13), and the ER stress-responsive transcription factor activating transcription factor 4 (ATF4) and C/EBP homologous protein (CHOP). However, the cyclic and transient induction of four reprogramming factors (POU domain, class 5, transcription factor 1, also known as octamer-binding transcription factor 4; SRY [sex determining region Y]-box 2; Kruppel-like factor 4; and myelocytomatosis oncogene; collectively referred to as OSKM) can inhibit NSC aging, as indicated by the decreased expression of the inflammatory and ER stress-related genes. We used ROSA-4F NSCs, which express OSKM from only one allele, to minimize the potential for full reprogramming or tumor formation during NSC rejuvenation. We expect that this novel rejuvenation method will enhance the potential of NSCs as a clinical approach to the treatment of neurological diseases.

Understanding the early cold response mechanism in IR64 indica rice variety through comparative transcriptome analysis

BackgroundCellular reprogramming in response to environmental stress involves alteration of gene expression, changes in the protein and metabolite profile for ensuring better stress management in plants. Similar to other plant species originating in tropical and sub-tropical areas, indica rice is highly sensitive to low temperature that adversely affects its growth and grain productivity. Substantial work has been done to understand cold induced changes in gene expression in rice plants. However, adequate information is not available for early gene expression, especially in indica variety. Therefore, a transcriptome profile was generated for cold shock treated seedlings of IR64 variety to identify early responsive genes.ResultsThe functional annotation of early DEGs shows enrichment of genes involved in altered membrane rigidity and electrolytic leakage, the onset of calcium signaling, ROS generation and activation of stress responsive transcription factors in IR64. Gene regulatory network suggests that cold shock induced Ca2+ signaling activates DREB/CBF pathway and other groups of transcription factors such as MYB, NAC and ZFP; for activating various cold-responsive genes. The analysis also indicates that cold induced signaling proteins like RLKs, RLCKs, CDPKs and MAPKK and ROS signaling proteins. Further, several late-embryogenesis-abundant (LEA), dehydrins and low temperature-induced-genes were upregulated under early cold shock condition, indicating the onset of water-deficit conditions. Expression profiling in different high yielding cultivars shows high expression of cold-responsive genes in Heera and CB1 indica varieties. These varieties show low levels of cold induced ROS production, electrolytic leakage and high germination rate post-cold stress, compared to IR36 and IR64. Collectively, these results suggest that these varieties may have improved adaptability to cold stress.ConclusionsThe results of this study provide insights about early responsive events in Oryza sativa l.ssp. indica cv IR64 in response to cold stress. Our data shows the onset of cold response is associated with upregulation of stress responsive TFs, hydrophilic proteins and signaling molecules, whereas, the genes coding for cellular biosynthetic enzymes, cell cycle control and growth-related TFs are downregulated. This study reports that the generation of ROS is integral to the early response to trigger the ROS mediated signaling events during later stages.