Effect of Combined Stressors on C. elegans Lifespan

Abstract Cellular stress is a fundamental component of age-associated disease. Cells experience many forms of stress (oxidative, heavy metal, etc.), and as we age the burden of stress and resulting damage increases while our cells’ ability to deal with the consequences becomes diminished due to dysregulation of cellular stress response pathways. By understanding how cells respond to stress we aim to slow age-associated deterioration and develop treatment targets for age-associated disease. The majority of past work has focused on understanding responses to individual stressors. In contrast, how pathology and stress responses differ in the presence of multiple stressors is relatively unknown; we investigate that here. We cultured worms on agar plates with different combinations of arsenic, copper, and DTT (which create oxidative/proteotoxic, heavy metal, and endoplasmic reticulum (ER) stress, respectively) at doses that result in 20% lifespan reduction individually and measured the effect on lifespan. We found that arsenic/copper and arsenic/DTT combinations created additive lifespan reductions while the copper/DTT combination created an antagonistic lifespan reduction when compared to controls (p<0.05). This antagonistic toxicity suggests an interaction either between the mechanisms of toxicity or the cellular response to copper and DTT. We are now evaluating the impact of copper and DTT individually and in combination on unfolded protein and heavy metal response pathways to understand the underlying mechanism of the interaction. Additionally, we are continuing to screen stressors to identify combinations that cause non-additive (synergistic or antagonistic) toxicity to build a comprehensive model of the genetic stress response network in C. elegans.

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The Interaction of Osmotic and Heavy Metal Stress in C. elegans

Innovation in Aging ◽

10.1093/geroni/igab046.2561 ◽

2021 ◽

Vol 5 (Supplement_1) ◽

pp. 687-687

Author(s):

Emily Turner ◽

Amanda Furtmann ◽

Hope Dang ◽

Destiny DeNicola ◽

George Sutphin

Keyword(s):

Heavy Metal ◽

Stress Response ◽

Osmotic Stress ◽

Multiple Stressors ◽

Heavy Metal Stress ◽

Metal Stress ◽

Molecular Response ◽

C Elegans ◽

Primary Driver ◽

The Impact

Abstract Cellular stress is an ever-present aspect of aging and a primary driver of many common age-associated diseases such as cancer, diabetes, or neurodegenerative diseases. As we age, stress-induced damage accumulates over time, along with reduced efficacy of stress response pathways at combatting such damage. Molecular stress response pathways are well studied in the context of individual stressors, but there is a lack of understanding of how these responses change when multiple stressors are encountered at the same time. The goal of our work is to explore the impact of multiple simultaneous stressors on health and survival, and to investigate the underlying molecular pathways involved. To accomplish this, we utilize the nematode Caenorhabditis elegans to monitor lifespan changes in response to various stressors. We simultaneously exposed C. elegans to high concentrations of sodium chloride and cadmium chloride, known to induce osmotic and heavy metal stress, respectively. We found that lifespan is drastically decreased by the combined stress, significantly more so than the reduction in lifespan caused by either individual stress. Our results show that glycerol levels, which are normally increased in response to osmotic stress, are significantly lowered when the two stresses are combined compared to levels detected for osmotic stress alone. This suggests that the presence of cadmium may sensitize worms to sodium and other osmotic stressors by blunting cells’ ability to mount an appropriate molecular response. In ongoing work, we will continue to dissect the mechanisms through which cadmium influences glycerol production and other aspects of osmotic stress response.

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Inhibition of Nonsense Mediated RNA Decay in Hypoxic Cells; Implications for Thalassemia.

Blood ◽

10.1182/blood.v110.11.1781.1781 ◽

2007 ◽

Vol 110 (11) ◽

pp. 1781-1781

Author(s):

Lawrence B. Gardner

Keyword(s):

Stress Response ◽

Stress Responses ◽

Cellular Response ◽

Globin Gene ◽

Cellular Stress ◽

Regulation Of Gene Expression ◽

Cellular Stress Response ◽

Rna Decay ◽

Processing Bodies ◽

Nonsense Mediated Rna Decay

Abstract Several common β globin gene mutations found in thalassemia are thought to promote rapid degradation of the aberrant mRNA through a specific mechanism termed nonsense mediated RNA decay (NMD). NMD, elicited through mutations leading to premature termination codons, is thought to be responsible not only for the degradation of the β globin PTC 39 mutation, responsible for >90% of thalassemia in Sardinia, but also for the degradation of 30% of all known human mutations and up to 10% of the genome. However, because NMD has been thought of as a constitutive and not a regulated pathway, the potential role of NMD in the dynamic regulation of gene expression has not been well explored. We have determined that NMD is inhibited in hypoxic cells. This hypoxic inhibition of NMD significantly prolongs the half-life of multiple mRNAs degraded by NMD, including the β globin PTC 39 mutation. We have also identified several additional mRNAs whose stabilities are significantly (>2 fold) 1. Increased when Rent1, an RNA helicase necessary for NMD is silenced 2. Decreased when Rent1 is over-expressed and 3. Increased in hypoxic cells when NMD is inhibited. These include the mRNAs that are integral for the cellular response to multiple stresses found in thalassemia, including hypoxic stress. Indeed, we observed that the cellular stress response is augmented when NMD is inhibited. The central component for many cellular stress responses is the phosphorylation of a translation factor, eIF2α. We and others have demonstrated that eIF2α is phosphorylated in hypoxic cells via the kinase PERK. Phosphorylation of eIF2α leads to the suppression of protein synthesis and the translational and transcriptional up-regulation of stress response genes. We hypothesized that phosphorylation of eIF2α was also responsible for the hypoxic inhibition of NMD. Indeed, when we used cells generated from mice in which wild-type eIF2α has been replaced by an eIF2α that cannot be phosphorylated, we found that hypoxic inhibition of NMD did not occur, demonstrating that is eIF2α phosphorylation is necessary for hypoxic inhibition of NMD. Degradation of NMD targets occurs in cytoplasmic processing bodies, which contain many of the enzymes necessary for mRNA catabolism. We noted that a distinct type of mRNA containing body, termed stress bodies, which do not have the capacity for RNA decay, are induced in hypoxic cells. This formation is dependent on PERK phosphorylation of eIF2α. While there are several potential mechanism by which hypoxic phosphorylation of eIF2α could inhibit NMD, our preliminary data suggests a model in which NMD targets are sequestered in cytoplasmic stress granules in hypoxic cells, thus excluding them from cytoplasmic processing bodies. Thus our studies reveal a novel form of gene regulation in hypoxic cells, regulation of NMD via phosphorylation of eIF2α. This finding has potential significance in many disease states, but particularly in thalassemia, where many of the stresses which phosphorylate eIF2α occur, and where the stress response and regulation of mutated β globin mRNAs may be particularly important.

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Flavonoids: Potential Candidates for the Treatment of Neurodegenerative Disorders

Biomedicines ◽

10.3390/biomedicines9020099 ◽

2021 ◽

Vol 9 (2) ◽

pp. 99

Author(s):

Shweta Devi ◽

Vijay Kumar ◽

Sandeep Kumar Singh ◽

Ashish Kant Dubey ◽

Jong-Joo Kim

Keyword(s):

Stress Response ◽

Stress Responses ◽

Neurodegenerative Disorders ◽

Cell Damage ◽

Cellular Stress ◽

Clinical Manifestations ◽

Cellular Stress Response ◽

Dramatic Rise ◽

Cellular Stress Responses

Neurodegenerative disorders, such as Parkinson’s disease (PD), Alzheimer’s disease (AD), Amyotrophic lateral sclerosis (ALS), and Huntington’s disease (HD), are the most concerning disorders due to the lack of effective therapy and dramatic rise in affected cases. Although these disorders have diverse clinical manifestations, they all share a common cellular stress response. These cellular stress responses including neuroinflammation, oxidative stress, proteotoxicity, and endoplasmic reticulum (ER)-stress, which combats with stress conditions. Environmental stress/toxicity weakened the cellular stress response which results in cell damage. Small molecules, such as flavonoids, could reduce cellular stress and have gained much attention in recent years. Evidence has shown the potential use of flavonoids in several ways, such as antioxidants, anti-inflammatory, and anti-apoptotic, yet their mechanism is still elusive. This review provides an insight into the potential role of flavonoids against cellular stress response that prevent the pathogenesis of neurodegenerative disorders.

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m5U54 tRNA Hypomodification by Lack of TRMT2A Drives the Generation of tRNA-Derived Small RNAs

International Journal of Molecular Sciences ◽

10.3390/ijms22062941 ◽

2021 ◽

Vol 22 (6) ◽

pp. 2941

Author(s):

Marisa Pereira ◽

Diana R. Ribeiro ◽

Miguel M. Pinheiro ◽

Margarida Ferreira ◽

Stefanie Kellner ◽

...

Keyword(s):

Stress Response ◽

Small Rnas ◽

Mammalian Cells ◽

Cellular Stress ◽

Cellular Stress Response ◽

Translation Regulation ◽

Translation Efficiency ◽

Down Regulation ◽

Gene Expression Control ◽

The Impact

Transfer RNA (tRNA) molecules contain various post-transcriptional modifications that are crucial for tRNA stability, translation efficiency, and fidelity. Besides their canonical roles in translation, tRNAs also originate tRNA-derived small RNAs (tsRNAs), a class of small non-coding RNAs with regulatory functions ranging from translation regulation to gene expression control and cellular stress response. Recent evidence indicates that tsRNAs are also modified, however, the impact of tRNA epitranscriptome deregulation on tsRNAs generation is only now beginning to be uncovered. The 5-methyluridine (m5U) modification at position 54 of cytosolic tRNAs is one of the most common and conserved tRNA modifications among species. The tRNA methyltransferase TRMT2A catalyzes this modification, but its biological role remains mostly unexplored. Here, we show that TRMT2A knockdown in human cells induces m5U54 tRNA hypomodification and tsRNA formation. More specifically, m5U54 hypomodification is followed by overexpression of the ribonuclease angiogenin (ANG) that cleaves tRNAs near the anticodon, resulting in accumulation of 5′tRNA-derived stress-induced RNAs (5′tiRNAs), namely 5′tiRNA-GlyGCC and 5′tiRNA-GluCTC, among others. Additionally, transcriptomic analysis confirms that down-regulation of TRMT2A and consequently m5U54 hypomodification impacts the cellular stress response and RNA stability, which is often correlated with tiRNA generation. Accordingly, exposure to oxidative stress conditions induces TRMT2A down-regulation and tiRNA formation in mammalian cells. These results establish a link between tRNA hypomethylation and ANG-dependent tsRNAs formation and unravel m5U54 as a tRNA cleavage protective mark.

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C. elegans discriminates colors to guide foraging

Science ◽

10.1126/science.abd3010 ◽

2021 ◽

Vol 371 (6533) ◽

pp. 1059-1063 ◽

Cited By ~ 1

Author(s):

D. Dipon Ghosh ◽

Dongyeop Lee ◽

Xin Jin ◽

H. Robert Horvitz ◽

Michael N. Nitabach

Keyword(s):

Stress Response ◽

Cellular Stress ◽

Color Discrimination ◽

Cellular Stress Response ◽

Blue Pigment ◽

Natural Environments ◽

C Elegans ◽

Evolutionarily Conserved ◽

Foraging Decisions ◽

Light Guides

Color detection is used by animals of diverse phyla to navigate colorful natural environments and is thought to require evolutionarily conserved opsin photoreceptor genes. We report that Caenorhabditis elegans roundworms can discriminate between colors despite the fact that they lack eyes and opsins. Specifically, we found that white light guides C. elegans foraging decisions away from a blue-pigment toxin secreted by harmful bacteria. These foraging decisions are guided by specific blue-to-amber ratios of light. The color specificity of color-dependent foraging varies notably among wild C. elegans strains, which indicates that color discrimination is ecologically important. We identified two evolutionarily conserved cellular stress response genes required for opsin-independent, color-dependent foraging by C. elegans, and we speculate that cellular stress response pathways can mediate spectral discrimination by photosensitive cells and organisms—even by those lacking opsins.

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Stressors and Stress Responses in Cystic Fibrosis

Endoplasmic Reticulum Stress in Diseases ◽

10.1515/ersc-2018-0002 ◽

2018 ◽

Vol 5 (1) ◽

pp. 11-29 ◽

Cited By ~ 1

Author(s):

Zsuzsa Bebok ◽

Lianwu Fu

Keyword(s):

Cystic Fibrosis ◽

Stress Response ◽

Stress Responses ◽

Genetic Disorder ◽

Cellular Stress ◽

Cellular Stress Response ◽

Bicarbonate Transport ◽

Persistent Infections ◽

Human Disorders ◽

The Unfolded Protein Response

Abstract Cystic fibrosis (CF) is a life-shortening, genetic disorder caused by mutations in the cystic fibrosis transmembrane conductance regulator gene (CFTR). The primary cause of CF is reduced CFTR-mediated chloride and bicarbonate transport, due to mutations in CFTR. However, inflammation and persistent infections influence clinical outcome. Cellular stress response pathways, such as the unfolded protein response (UPR) and the integrated stress response (ISR), referred to here as cellular stress response pathways (SRPs), contribute to the pathology of human disorders. Multiple studies have indicated activation of SRPs in CF tissues. We review our present understanding of how SRPs are activated in CF and their contribution to pathology. We conclude that reduced CFTR function in CF organs establishes a tissue environment in which internal or external insults activate SRPs. SRPs contribute to CF pathogenesis by reducing CFTR expression, enhancing inflammation with consequent tissue remodeling. Understanding the contribution of SRPs to CF pathogenesis is crucial even in the era of CFTR “modulators” that are designed to potentiate, correct or amplify CFTR function, since there is an urgent need for supportive treatments. Importantly, CF patients with established pathology could benefit from the targeted use of drugs that modulate SRPs to reduce the symptoms.

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FOXO3a from the Nucleus to the Mitochondria: A Round Trip in Cellular Stress Response

Cells ◽

10.3390/cells8091110 ◽

2019 ◽

Vol 8 (9) ◽

pp. 1110 ◽

Cited By ~ 17

Author(s):

Candida Fasano ◽

Vittoria Disciglio ◽

Stefania Bertora ◽

Martina Lepore Signorile ◽

Cristiano Simone

Keyword(s):

Stress Response ◽

Protein Kinase ◽

Stress Responses ◽

Target Genes ◽

Cellular Stress ◽

Genotoxic Stress ◽

Cellular Stress Response ◽

Mitogen Activated Protein Kinase ◽

Mitochondrial Functions ◽

Stressed Cells

Cellular stress response is a universal mechanism that ensures the survival or negative selection of cells in challenging conditions. The transcription factor Forkhead box protein O3 (FOXO3a) is a core regulator of cellular homeostasis, stress response, and longevity since it can modulate a variety of stress responses upon nutrient shortage, oxidative stress, hypoxia, heat shock, and DNA damage. FOXO3a activity is regulated by post-translational modifications that drive its shuttling between different cellular compartments, thereby determining its inactivation (cytoplasm) or activation (nucleus and mitochondria). Depending on the stress stimulus and subcellular context, activated FOXO3a can induce specific sets of nuclear genes, including cell cycle inhibitors, pro-apoptotic genes, reactive oxygen species (ROS) scavengers, autophagy effectors, gluconeogenic enzymes, and others. On the other hand, upon glucose restriction, 5′-AMP-activated protein kinase (AMPK) and mitogen activated protein kinase kinase (MEK)/extracellular signal-regulated kinase (ERK) -dependent FOXO3a mitochondrial translocation allows the transcription of oxidative phosphorylation (OXPHOS) genes, restoring cellular ATP levels, while in cancer cells, mitochondrial FOXO3a mediates survival upon genotoxic stress induced by chemotherapy. Interestingly, these target genes and their related pathways are diverse and sometimes antagonistic, suggesting that FOXO3a is an adaptable player in the dynamic homeostasis of normal and stressed cells. In this review, we describe the multiple roles of FOXO3a in cellular stress response, with a focus on both its nuclear and mitochondrial functions.

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The mammalian decidual cell evolved from a cellular stress response

10.1101/246397 ◽

2018 ◽

Author(s):

Eric M. Erkenbrack ◽

Jamie D. Maziarz ◽

Oliver W. Griffith ◽

Cong Liang ◽

Arun R. Chavan ◽

...

Keyword(s):

Stress Response ◽

Stress Responses ◽

Molecular Mechanisms ◽

Cellular Stress ◽

Cell Types ◽

Monodelphis Domestica ◽

Cellular Stress Response ◽

General Mechanism ◽

Decidual Cell ◽

Cell Type

AbstractAmong animal species, cell types vary greatly in terms of number and kind. The broad range of number of cell types among species suggests that cell type origination is a significant source of evolutionary novelty. The molecular mechanisms giving rise to novel cell types, however, are poorly understood. Here we show that a novel cell type of eutherian mammals, the decidual stromal cell (DSC), evolved by rewiring an ancestral cellular stress response. We isolated the precursor cell type of DSCs, endometrial stromal fibroblasts (ESFs), from the opossum Monodelphis domestica. We show that, in opossum ESF, the majority of decidual core regulatory genes respond to decidualizing signals, but do not regulate decidual effector genes. Rather, in opossum ESF, decidual transcription factors function in apoptotic and oxidative stress response. We propose that the rewiring of cellular stress responses could be a general mechanism for the evolution of novel cell types.

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Compositional analysis of ALS-linked stress granule-like structures reveals factors and cellular pathways dysregulated by mutant FUS under stress

10.1101/2021.03.02.433611 ◽

2021 ◽

Author(s):

Haiyan An ◽

Gioana Litscher ◽

Wenbin Wei ◽

Naruaki Watanabe ◽

Tadafumi Hashimoto ◽

...

Keyword(s):

Stress Responses ◽

Cellular Response ◽

Affinity Purification ◽

Cellular Stress ◽

Protein Structures ◽

Protein Translation ◽

Cellular Stress Response ◽

Cytoplasmic Rna ◽

Cellular Pathways ◽

Stressed Cells

AbstractFormation of cytoplasmic RNA-protein structures called stress granules (SGs) is a highly conserved cellular response to stress. Abnormal metabolism of SGs may contribute to the pathogenesis of (neuro)degenerative diseases such as amyotrophic lateral sclerosis (ALS). Many SG proteins are affected by mutations causative of these conditions, including fused in sarcoma (FUS). Mutant FUS variants have high affinity to SGs and also spontaneously form de novo cytoplasmic RNA granules. Mutant FUS-containing assemblies (mFAs), often called “pathological SGs”, are proposed to play a role in ALS-FUS pathogenesis. However, global structural differences between mFAs and physiological SGs remain largely unknown, therefore it is unclear whether and how mFAs may affect cellular stress responses. Here we used affinity purification to characterise the protein and RNA composition of normal SGs and mFAs purified from stressed cells. Comparison of the SG and mFA proteomes revealed that proteasome subunits and certain nucleocytoplasmic transport factors are depleted from mFAs, whereas translation elongation, mRNA surveillance and splicing factors as well as mitochondrial proteins are enriched in mFAs, as compared to SGs. Validation experiments for a hit from our analysis, a splicing factor hnRNPA3, confirmed its RNA-dependent sequestration into mFAs in cells and into pathological FUS inclusions in a FUS transgenic mouse model. Furthermore, silencing of the Drosophila hnRNPA3 ortholog dramatically enhanced FUS toxicity in transgenic flies. Comparative transcriptomic analysis of SGs and mFAs revealed that mFAs recruit a significantly less diverse spectrum of RNAs, including reduced recruitment of transcripts encoding proteins involved in protein translation, DNA damage response, and apoptotic signalling. However mFAs abnormally sequester certain mRNAs encoding proteins involved in stress signalling cascades. Overall, our study establishes molecular differences between physiological SGs and mFAs and identifies the spectrum of proteins, RNAs and respective cellular pathways affected by mFAs in stressed cells. In conclusion, we show that mFAs are compositionally distinct from SGs and that they cannot fully substitute for SG functions while gaining novel, potentially toxic functions in cellular stress response. Results of our study support a pathogenic role for stress-induced cytoplasmic FUS assemblies in ALS-FUS.

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The alkyl side chain of PACA nanoparticles dictates the impact on cellular stress responses and the mode of particle-induced cell death

10.1101/304618 ◽

2018 ◽

Author(s):

Marzena Szwed ◽

Tonje Sønstevold ◽

Anders Øverbye ◽

Nikolai Engedal ◽

Beata Grallert ◽

...

Keyword(s):

Cell Death ◽

Stress Responses ◽

Cellular Response ◽

Cellular Stress ◽

Cell Interaction ◽

Multidrug Resistant ◽

Detailed Knowledge ◽

Promising Alternative ◽

Cellular Stress Responses ◽

The Impact

AbstractFor optimal exploitation of nanoparticles (NPs) in biomedicine, and to predict nanotoxicity, detailed knowledge on the cellular responses to cell-bound or internalized NPs is imperative. The outcome of NP-cell interaction is dictated by the type and magnitude of the NP insult and the cellular response. Here, we have systematically studied the impact of minor differences in NP composition on cellular stress responses and viability by using highly similar poly(alkylcyanoacrylate) (PACA) particles. Surprisingly, PACA particles differing only in their alkyl side chains; butyl (PBCA), ethylbutyl (PEBCA), or octyl (POCA), respectively, induced different stress responses and modes of cell death in human cell lines. POCA particles induced endoplasmic reticulum stress and apoptosis. In contrast, PBCA and PEBCA particles induced lipid peroxidation by depletion of the main cellular antioxidant glutathione (GSH), in a manner depending on the levels of the GSH precursor cystine, and transcription of the cystine transporter SLC7A11 regulated by ATF4 and Nrf2. Intriguingly, these particles activated the recently discovered cell death mechanism ferroptosis, which constitutes a promising alternative for targeting multidrug-resistant cancer stem-like cells. Of the two, PBCA was the strongest inducer. In summary, our findings highlight the cellular sensitivity to nanoparticle composition and have important implications for the choice of PACA monomer in therapeutical settings.

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