Meisosomes, folded membrane platforms, link the epidermis to the cuticle in C. elegans

Apical extracellular matrices (aECMs) form a physical barrier to the environment. In C. elegans, the epidermal aECM is the cuticle, composed mainly of different types of collagen, associated in circumferential ridges separated by furrows. Damage to the cuticle causes stress responses in the underlying epidermis by a process that is poorly understood. Here, we focus on structures connecting the cuticle to the epidermis, that we term meisosomes. We show that meisosomes are composed of stacked parallel folds of the epidermal plasma membrane, filled with cuticle. Before moulting, meisosomes align with the underlying cytoskeleton in between furrows. In collagen mutants lacking furrows, that exhibit a constitutive damage response in the epidermis, meisosomes are smaller and fail to align. A loss of connection between the epidermis and the cuticle is also observed in these mutants, as well as a modification of the biomechanical properties of the skin. Meisosomes are therefore an essential component of the skin, serving as attachment platforms between the cuticle and epidermis. They could also be involved in relaying tensile information from the cuticle to the underlying epidermis as part of an integrated stress response to injury and infection.

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Monogenic Diabetes and Integrated Stress Response Genes Display Altered Gene Expression in Type 1 Diabetes

10.2337/figshare.14612202.v1 ◽

2021 ◽

Author(s):

Helmut Hiller ◽

Dawn E. Beachy ◽

Joseph J. Lebowitz ◽

Stefanie Engler ◽

Justin R. Mason ◽

...

Keyword(s):

Type 1 Diabetes ◽

Stress Response ◽

Stress Responses ◽

Disease Process ◽

Monogenic Diabetes ◽

Integrated Stress Response ◽

Altered Expression ◽

Increased Risk ◽

Gene And Protein Expression

Type 1 diabetes has a multifactorial autoimmune etiology, involving environmental prompts and polygenic predisposition. We hypothesized that pancreata from individuals with and at risk for type 1 diabetes would exhibit dysregulated expression of genes associated with monogenic forms of diabetes caused by non-redundant single-gene mutations. Employing a “monogenetic transcriptomic strategy,” we measured the expression of these genes in human type 1 diabetes, autoantibody positive (autoantibody+), and control pancreas tissues using RTqPCR in accordance with the Minimum Information for Publication of Quantitative Real-Time PCR Experiments (MIQE) guidelines. Gene and protein expression were visualized <i>in situ</i> using immunofluorescence, RNAScope, and confocal microscopy. Two-dozen monogenic diabetes genes showed altered expression in human pancreata from individuals with type 1 diabetes versus unaffected controls. Six of these genes also saw dysregulation in pancreata from autoantibody+ persons at increased-risk for type 1 diabetes. As a subset of these genes are related to cellular stress responses, we measured integrated stress response (ISR) genes and identified 20 with altered expression in type 1 diabetes pancreata, including three of the four eIF2a-dependent kinases. Equally intriguing, we observed significant repression of the three arms of the ISR in autoantibody+ pancreata. Collectively, these efforts suggest monogenic diabetes and ISR genes are dysregulated early in the type 1 diabetes disease process and likely contribute to the disorder’s pathogenesis.

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Translational induction of ATF4 during integrated stress response requires noncanonical initiation factors eIF2D and DENR

Nature Communications ◽

10.1038/s41467-020-18453-1 ◽

2020 ◽

Vol 11 (1) ◽

Cited By ~ 1

Author(s):

Deepika Vasudevan ◽

Sarah D. Neuman ◽

Amy Yang ◽

Lea Lough ◽

Brian Brown ◽

...

Keyword(s):

Stress Response ◽

Er Stress ◽

Stress Responses ◽

Rna Binding ◽

Open Reading Frames ◽

Binding Motif ◽

Integrated Stress Response ◽

Developmental Defects ◽

Initiation Factors

Abstract The Integrated Stress Response (ISR) helps metazoan cells adapt to cellular stress by limiting the availability of initiator methionyl-tRNA for translation. Such limiting conditions paradoxically stimulate the translation of ATF4 mRNA through a regulatory 5′ leader sequence with multiple upstream Open Reading Frames (uORFs), thereby activating stress-responsive gene expression. Here, we report the identification of two critical regulators of such ATF4 induction, the noncanonical initiation factors eIF2D and DENR. Loss of eIF2D and DENR in Drosophila results in increased vulnerability to amino acid deprivation, susceptibility to retinal degeneration caused by endoplasmic reticulum (ER) stress, and developmental defects similar to ATF4 mutants. eIF2D requires its RNA-binding motif for regulation of 5′ leader-mediated ATF4 translation. Consistently, eIF2D and DENR deficient human cells show impaired ATF4 protein induction in response to ER stress. Altogether, our findings indicate that eIF2D and DENR are critical mediators of ATF4 translational induction and stress responses in vivo.

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Antagonistic effects of chemical mixtures on the oxidative stress response are silenced by heat stress and reversed under dietary restriction

Exposome ◽

10.1093/exposome/osab005 ◽

2021 ◽

Author(s):

Karthik Suresh Arulalan ◽

Javier Huayta ◽

Jonathan W Stallrich ◽

Adriana San-Miguel

Keyword(s):

Oxidative Stress ◽

Stress Response ◽

Design Of Experiments ◽

Stress Responses ◽

Current Knowledge ◽

Oxidative Stress Response ◽

Chemical Mixtures ◽

C Elegans ◽

Chemical Agents ◽

Limited Food

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.

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Mammalian orthoreovirusinfection is enhanced in cells pre-treated with sodium arsenite

10.1101/555367 ◽

2019 ◽

Author(s):

Michael M. Lutz ◽

Megan P. Worth ◽

Meleana M. Hinchman ◽

John S. L. Parker ◽

Emily D. Ledgerwood

Keyword(s):

Stress Response ◽

Heat Shock ◽

Protein Expression ◽

Stress Responses ◽

Sodium Arsenite ◽

Integrated Stress Response ◽

Reovirus Infection ◽

Cellular Stress Responses ◽

Pre Treatment ◽

Reovirus Replication

ABSTRACTFollowing reovirus infection, cells activate stress responses that repress canonical cellular translation as a mechanism to limit production of progeny virions. This includes the formation of stress granules (SG) that sequester translationally-stalled cellular transcripts, translation initiation factors, ribosomal proteins, and RNA binding proteins until conditions improve and translation can resume. Work by others suggests that these cellular stress responses, which are part of the integrated stress response, may benefit rather than repress reovirus replication. In agreement with this, we report that stressing cells prior to infection with sodium arsenite (SA), a robust inducer of SG and activator of eIF2α kinases, enhanced viral protein expression, percent infectivity and viral titer in SA-treated cells compared to untreated cells. SA-mediated enhancement of reovirus replication was not strain-specific, but was cell-type specific. While pre-treatment of cells with SA offered the greatest enhancement, treatment of infected cultures as late as 4 h post infection resulted in an increase in the percent of cells infected. SA activates the HRI kinase, which phosphorylates eIF2α and subsequently induces SG formation. Other stresses, such as heat shock (HS) and osmotic shock also activate HRI. Heat shock of cells prior to reovirus infection readily induced SG in greater than 85% of cells. Although HS pre-treatment had no effect on the percentage of infected cells or viral yield, it did enhance viral protein expression. These data suggest that SA pre-treatment perturbs the cell in a way that is beneficial for reovirus and that neither HRI activation nor SG induction is sufficient for reovirus infection enhancement.SIGNIFICANCEAll viruses rely on the host translational machinery for the synthesis of viral proteins. In response to viral infection, cells activate the integrated stress response resulting in the phosphorylation of eIF2α and translation shutoff. Despite this, reovirus replicates to reduced titers in the absence of this response. In this work, we report that sodium arsenite activation of the integrated stress response prior to virus inoculation enhances virus infectivity, protein expression and titer. Together, these data suggest that modulation of conserved cellular stress responses can alter reovirus replication.

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Conserved Roles of C. elegans and Human MANFs in Sulfatide Binding and Cytoprotection

10.1101/263731 ◽

2018 ◽

Author(s):

Meirong Bai ◽

Roman Vozdek ◽

Aleš Hnízda ◽

Chenxiao Jiang ◽

Bingying Wang ◽

...

Keyword(s):

Stress Response ◽

Er Stress ◽

Stress Responses ◽

Mammalian Cells ◽

Dopamine Neurons ◽

Lipid Mediator ◽

Outer Cell ◽

Dependent Manner ◽

C Elegans ◽

Er Stress Response

AbstractMesencephalic Astrocyte-Derived Neurotrophic Factor (MANF) is an endoplasmic reticulum (ER) protein that can be secreted and protect dopamine neurons and cardiomyocytes from ER stress and apoptosis. The mechanism of action of extracellular MANF has long been elusive. From a genetic screen for mutants with abnormal ER stress response, we identified the gene Y54G2A.23 as the evolutionarily conserved C. elegans MANF orthologue. We find that MANF binds to the lipid sulfatide, also known as 3-O-sulfogalactosylceramide present in serum and outer-cell membrane leaflets, directly in isolated forms and in reconstituted lipid micelles. Sulfatide binding promotes cellular MANF uptake and cytoprotection from hypoxia-induced cell death. Heightened ER stress responses of MANF-null C. elegans mutants and mammalian cells are alleviated by human MANF in a sulfatide-dependent manner. Our results demonstrate conserved roles of MANF in sulfatide binding and ER stress response, supporting sulfatide as a long-sought lipid mediator of MANF’s cytoprotection.

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Effect of Combined Stressors on C. elegans Lifespan

Innovation in Aging ◽

10.1093/geroni/igab046.2499 ◽

2021 ◽

Vol 5 (Supplement_1) ◽

pp. 667-667

Author(s):

Bradford Hull ◽

George Sutphin

Keyword(s):

Heavy Metal ◽

Stress Response ◽

Stress Responses ◽

Cellular Response ◽

Multiple Stressors ◽

Cellular Stress ◽

Cellular Stress Response ◽

C Elegans ◽

Arsenic Copper ◽

The Impact

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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Structural Variants of poly(alkylcyanoacrylate) Nanoparticles Differentially Affect LC3 and Autophagic Cargo Degradation

Journal of Biomedical Nanotechnology ◽

10.1166/jbn.2020.2906 ◽

2020 ◽

Vol 16 (4) ◽

pp. 432-445

Author(s):

Tonje Sønstevold ◽

Nikolai Engedal ◽

Ýrr Mørch ◽

Tore Geir Iversen ◽

Tore Skotland ◽

...

Keyword(s):

Stress Response ◽

Er Stress ◽

Stress Responses ◽

Drug Carrier ◽

Drug Carriers ◽

Autophagic Flux ◽

Integrated Stress Response ◽

Alkyl Side Chains ◽

Cellular Stress Responses ◽

Autophagic Degradation

Nanoparticle drug carriers trigger a variety of cellular stress responses, including ER stress and antioxidant responses, but may also affect the intracellular degradative pathway autophagy. This can impose profound effects on drug delivery, cellular treatment responses, and nanoparticle cytotoxicity. We recently demonstrated that even small variations in the alkyl side chains of poly(alkylcyanoacrylate) (PACA) drug carrier nanoparticles, namely butyl (PBCA), ethylbutyl (PEBCA), or octyl (POCA), differentially induce ER stress and redox imbalance in human cell lines. Here, we systematically investigate how these PACA variants affect autophagy. Interestingly, treatment with PEBCA or POCA particles led to intracellular accumulation of the autophagosome marker LC3-II, but via different mechanisms. PEBCA induced an integrated stress response-and ATF4-mediated increase in LC3B mRNA, whereas POCA blocked autophagic degradation of LC3-II and long-lived proteins in bulk. PBCA also increased LC3B mRNA via the integrated stress response and ATF4, but unlike PEBCA, it inhibited LC3 lipidation and autophagic cargo degradation. Our data demonstrate that even subtle variations in NP structure can have profoundly different impacts on autophagy, and that careful monitoring of autophagic flux and cargo degradation is critical for drawing accurate conclusions. Our findings have important implications for the choice of PACA monomer in different therapeutic settings.

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The Fragile X Mental Retardation Protein protects the lung from xenobiotic stress by facilitating the Integrated Stress Response

10.1101/2021.03.16.435743 ◽

2021 ◽

Author(s):

Deblina Sain Basu ◽

Rital Bhavsar ◽

Imtiyaz Gulami ◽

Saimanoz Lingamallu ◽

Ravi Muddashetty ◽

...

Keyword(s):

Mental Retardation ◽

Stress Response ◽

Stress Responses ◽

Fragile X ◽

Air Pollutant ◽

Environmental Toxicants ◽

Integrated Stress Response ◽

Fragile X Mental Retardation ◽

Mental Retardation Protein

Stress response pathways protect the lung from the damaging effects of environmental toxicants. Here we investigate the role of the Fragile X Mental Retardation Protein (FMRP), a multifunctional protein implicated in stress responses, in the lung. We report that FMRP is expressed in murine and human lungs, in the airways and more broadly. Analysis of airway stress responses in mice and in a murine cell line ex vivo, using the well-established Naphthalene (Nap) injury model, reveals that FMRP-deficient cells exhibit increased expression of markers of oxidative and genotoxic stress and increased cell death. We find that FMRP-deficient cells fail to actuate the Integrated Stress Response Pathway (ISR) and upregulate the transcription factor ATF4. Knockdown of ATF4 expression phenocopies the loss of FMRP. We extend our analysis of the role of FMRP to human bronchial BEAS-2B cells, using a 9, 10-Phenanthrenequinone air pollutant model, to find that FMRP-deficient BEAS-2B also fail to actuate the ISR and exhibit greater susceptibility. Taken together, our data suggest that FMRP has a conserved role in protecting the airways by facilitating the ISR.

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Integrated stress response restricts macrophage necroptosis

Life Science Alliance ◽

10.26508/lsa.202101260 ◽

2021 ◽

Vol 5 (1) ◽

pp. e202101260

Author(s):

David E Place ◽

Parimal Samir ◽

RK Subbarao Malireddi ◽

Thirumala-Devi Kanneganti

Keyword(s):

Cell Death ◽

Stress Response ◽

Cell Survival ◽

Stress Responses ◽

Critical Role ◽

Stress Granule ◽

Integrated Stress Response ◽

Signaling Axis ◽

Stressed Cells

The integrated stress response (ISR) regulates cellular homeostasis and cell survival following exposure to stressors. Cell death processes such as apoptosis and pyroptosis are known to be modulated by stress responses, but the role of the ISR in necroptosis is poorly understood. Necroptosis is an inflammatory, lytic form of cell death driven by the RIPK3-MLKL signaling axis. Here, we show that macrophages that have induced the ISR are protected from subsequent necroptosis. Consistent with a reduction in necroptosis, phosphorylation of RIPK1, RIPK3, and MLKL is reduced in macrophages pre-treated with ISR-inducing agents that are challenged with necroptosis-inducing triggers. The stress granule component DDX3X, which is involved in ISR-mediated regulation of pyroptosis, is not required for protecting ISR-treated cells from necroptosis. Disruption of stress granule assembly or knockdown of Perk restored necroptosis in pre-stressed cells. Together, these findings identify a critical role for the ISR in limiting necroptosis in macrophages.

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An inhibitor of HIV-1 protease modulates constitutive eIF2α dephosphorylation to trigger a specific integrated stress response

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1514076113 ◽

2015 ◽

Vol 113 (2) ◽

pp. E117-E126 ◽

Cited By ~ 23

Author(s):

Aude De Gassart ◽

Bojan Bujisic ◽

Léa Zaffalon ◽

Laurent A. Decosterd ◽

Antonia Di Micco ◽

...

Keyword(s):

Stress Response ◽

Stress Responses ◽

Translation Initiation Factor ◽

Hiv Protease ◽

Initiation Factor ◽

Hiv Protease Inhibitors ◽

Integrated Stress Response ◽

Α Subunit ◽

Eif2α Phosphorylation ◽

Program Characteristic

Inhibitors of the HIV aspartyl protease [HIV protease inhibitors (HIV-PIs)] are the cornerstone of treatment for HIV. Beyond their well-defined antiretroviral activity, these drugs have additional effects that modulate cell viability and homeostasis. However, little is known about the virus-independent pathways engaged by these molecules. Here we show that the HIV-PI Nelfinavir decreases translation rates and promotes a transcriptional program characteristic of the integrated stress response (ISR). Mice treated with Nelfinavir display hallmarks of this stress response in the liver, including α subunit of translation initiation factor 2 (eIF2α) phosphorylation, activating transcription factor-4 (ATF4) induction, and increased expression of known downstream targets. Mechanistically, Nelfinavir-mediated ISR bypassed direct activation of the eIF2α stress kinases and instead relied on the inhibition of the constitutive eIF2α dephosphorylation and down-regulation of the phophatase cofactor CReP (Constitutive Repressor of eIF2α Phosphorylation; also known as PPP1R15B). These findings demonstrate that the modulation of eIF2α-specific phosphatase cofactor activity can be a rheostat of cellular homeostasis that initiates a functional ISR and suggest that the HIV-PIs could be repositioned as therapeutics in human diseases to modulate translation rates and stress responses.

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