scholarly journals Glucose increases the lifespan of post-reproductive C. elegans independently of FOXO

2018 ◽  
Author(s):  
Wang Lei ◽  
Caroline Beaudoin-Chabot ◽  
Guillaume Thibault
Keyword(s):  
Er Stress ◽  
Stress Resistance ◽  
Metabolic Diseases ◽  
Strong Association ◽  
Cellular Damage ◽  
Model Organisms ◽  
Dependent Manner ◽  
C Elegans ◽  
Age Related ◽  
Er Homeostasis

ABSTRACTAging is one of the most critical risk factors for the development of metabolic syndromes1. Prominent metabolic diseases, namely type 2 diabetes and insulin resistance, have a strong association with endoplasmic reticulum (ER) stress2. Upon ER stress, the unfolded protein response (UPR) is activated to limit cellular damage by adapting to stress conditions and restoring ER homeostasis3,4. However, adaptive genes upregulated from the UPR tend to decrease with age5. Although stress resistance correlates with increased longevity in a variety of model organisms, the links between the UPR, ER stress resistance, and longevity remain poorly understood. Here, we show that supplementing bacteria diet with 2% glucose (high glucose diet, HGD) in post-reproductive 7-day-old (7DO) C. elegans significantly extend their lifespan in contrast to shortening the lifespan of reproductive 3-day-old (3DO) animals. The insulin-IGF receptor DAF-2 and its immediate downstream target, phosphoinositide 3-kinase (PI3K) AGE-1, were found to be critical factors in extending the lifespan of 7DO worms on HGD. The downstream transcription factor forkhead box O (FOXO) DAF-16 did not extend the lifespan of 7DO worms on HGD in contrast of its previously reported role in modulating lifespan of 3DO worms6. Furthermore, we identified that UPR activation through the highly conserved ATF-6 and PEK-1 sensors significantly extended the longevity of 7DO worms on HGD but not through the IRE-1 sensor. Our results demonstrate that HGD extends lifespan of post-reproductive worms in a UPR-dependent manner but independently of FOXO. Based on these observations, we hypothesise that HGD activates the otherwise quiescent UPR in aged worms to overcome age-related stress and to restore ER homeostasis. In contrast, young adult animals subjected to HGD leads to unresolved ER stress, conversely leading to a deleterious stress response.

Transcriptional targets of DAF-16 insulin signaling pathway protect C. elegans from extreme hypertonic stress

2005 ◽  
Vol 288 (2) ◽  
pp. C467-C474 ◽  
Author(s):  
S. Todd Lamitina ◽  
Kevin Strange
Keyword(s):  
Insulin Signaling ◽  
Stress Resistance ◽  
Molecular Mechanisms ◽  
Organic Osmolytes ◽  
Dependent Manner ◽  
Animal Cells ◽  
Hypertonic Stress ◽  
C Elegans ◽  
Downstream Target ◽  
Molecular Damage

All cells adapt to hypertonic stress by regulating their volume after shrinkage, by accumulating organic osmolytes, and by activating mechanisms that protect against and repair hypertonicity-induced damage. In mammals and nematodes, inhibition of signaling from the DAF-2/IGF-1 insulin receptor activates the DAF-16/FOXO transcription factor, resulting in increased life span and resistance to some types of stress. We tested the hypothesis that inhibition of insulin signaling in Caenorhabditis elegans also increases hypertonic stress resistance. Genetic inhibition of DAF-2 or its downstream target, the AGE-1 phosphatidylinositol 3-kinase, confers striking resistance to a normally lethal hypertonic shock in a DAF-16-dependent manner. However, insulin signaling is not inhibited by or required for adaptation to hypertonic conditions. Microarray studies have identified 263 genes that are transcriptionally upregulated by DAF-16 activation. We identified 14 DAF-16-upregulated genes by RNA interference screening that are required for age- 1 hypertonic stress resistance. These genes encode heat shock proteins, proteins of unknown function, and trehalose synthesis enzymes. Trehalose levels were elevated approximately twofold in age- 1 mutants, but this increase was insufficient to prevent rapid hypertonic shrinkage. However, age- 1 animals unable to synthesize trehalose survive poorly under hypertonic conditions. We conclude that increased expression of proteins that protect eukaryotic cells against environmental stress and/or repair stress-induced molecular damage confers hypertonic stress resistance in C. elegans daf- 2/ age- 1 mutants. Elevated levels of solutes such as trehalose may also function in a cytoprotective manner. Our studies provide novel insights into stress resistance in animal cells and a foundation for new studies aimed at defining molecular mechanisms underlying these essential processes.

SGLT2 inhibitors as calorie restriction-mimetics: insights on longevity pathways and age-related diseases

Endocrinology ◽  
2021 ◽  
Author(s):  
Caroline W S Hoong ◽  
Marvin W J Chua
Keyword(s):  
Calorie Restriction ◽  
Stress Resistance ◽  
Target Genes ◽  
Metabolic Diseases ◽  
Vascular Inflammation ◽  
Sglt2 Inhibitors ◽  
Acid Oxidation ◽  
The Metabolic Syndrome ◽  
Age Related ◽  
Energy Deprivation

Abstract SGLT2 inhibitors induce glycosuria, reduce insulin levels, promote fatty acid oxidation and ketogenesis. By promoting a nutrient deprivation state, SGLT2 inhibitors upregulate the energy deprivation sensors AMPK and SIRT1, inhibit the nutrient sensors mTOR and insulin/IGF-1, and modulate the closely-linked HIF-2α/HIF-1α pathways. Phosphorylation of AMPK and upregulation of adiponectin and PPAR-α favour a reversal of the metabolic syndrome which have been linked to suppression of chronic inflammation. Downregulation of insulin/IGF1 pathways and mTOR signalling from a reduction in glucose and circulating amino acids promote cellular repair mechanisms including autophagy and proteostasis which confer cellular stress resistance and attenuate cellular senescence. SIRT1, another energy sensor activated by NAD+ in nutrient-deficient states, is reciprocally activated by AMPK, and can deacetylate and activate transcription factors such as PCG-1α, TFAM and NRF2 that regulate mitochondrial biogenesis. FOXO3 transcription factor which target genes in stress resistance, is also activated by AMPK and SIRT1. Modulation of these pathways by SGLT2 inhibitors have been shown to alleviate metabolic diseases, attenuate vascular inflammation and arterial stiffness, improve mitochondrial function and reduce oxidative stress-induced tissue damage. Compared to other calorie restriction mimetics such as metformin, rapamycin, resveratrol and NAD+ precursors, SGLT2 inhibitors appear to be the most promising in the treatment of ageing-related diseases, due to its regulation of multiple longevity pathways that closely resemble that achieved by calorie restriction, and their established efficacy in reduction in cardiovascular events and all-cause mortality. Evidence is compelling for the role of SGLT2 inhibitors as a calorie restriction mimetic in anti-ageing therapeutics.

scholarly journals Lipid droplets modulate proteostasis, SQST-1/SQSTM1 dynamics, and lifespan in C. elegans

2021 ◽  
Author(s):  
Anita Kumar ◽  
Joslyn Mills ◽  
Wesley Parker ◽  
Joshua Leitão ◽  
Celeste Ng ◽  
...  
Keyword(s):  
Translational Regulation ◽  
Lipid Droplets ◽  
Dependent Manner ◽  
Lipase Gene ◽  
Triacylglycerol Lipase ◽  
Selective Autophagy ◽  
C Elegans ◽  
Protein Ubiquitination ◽  
Model Of Alzheimer’S Disease ◽  
Age Related

Abstract The ability of organisms to live long depends largely on the maintenance of proteome stability via proteostatic mechanisms including translational regulation, protein chaperoning and degradation machineries. In several long-lived Caenorhabditis elegans strains, such as insulin/IGF-1 receptor daf-2 mutants, enhanced proteostatic mechanisms are accompanied by elevated intestinal lipid stores, but the role of lipid droplets in longevity has remained obscure. Here, while determining the regulatory network of the selective autophagy receptor SQST-1/SQSTM1, we unexpectedly uncovered a novel role for lipid droplets in proteostasis and longevity. Using an unbiased genomewide RNAi screening approach, we identified several SQST-1 modulators, including proteins found on lipid droplets and those prone to aggregate with age. SQST-1 accumulated on lipid droplets when autophagy was inhibited, suggesting that lipid droplets may serve a role in facilitating selective autophagy. Expansion of intestinal lipid droplets by silencing the conserved cytosolic triacylglycerol lipase gene atgl-1/ATGL enhanced autophagy, and extended lifespan in an HSF-1/HSF1-dependent and CDC-48/VCP-dependent manner. Silencing atgl-1 mitigated the age-related accumulation of SQST-1 and reduced overall ubiquitination of proteins. Reducing atgl-1 also improved proteostasis in a nematode model of Alzheimer’s disease. Subcellular analyses revealed that lipid droplets unexpectedly harbor more ubiquitinated proteins than the cytosol. Accordingly, low lipid droplet levels exacerbated the proteostatic collapse when autophagy or proteasome function was compromised. Altogether, our study uncovers a key role for lipid droplets in C. elegans as a proteostatic mediator that reduces protein ubiquitination, facilitates autophagy, and promotes longevity.

scholarly journals The PERK-Dependent Molecular Mechanisms as a Novel Therapeutic Target for Neurodegenerative Diseases

2020 ◽  
Vol 21 (6) ◽  
pp. 2108 ◽  
Author(s):  
Wioletta Rozpędek-Kamińska ◽  
Natalia Siwecka ◽  
Adam Wawrzynkiewicz ◽  
Radosław Wojtczak ◽  
Dariusz Pytel ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Neurodegenerative Diseases ◽  
Er Stress ◽  
Molecular Mechanisms ◽  
Treatment Strategies ◽  
Stress Conditions ◽  
World Population ◽  
Dependent Manner ◽  
Age Related ◽  
The Unfolded Protein Response

Higher prevalence of neurodegenerative diseases is strictly connected with progressive aging of the world population. Interestingly, a broad range of age-related, neurodegenerative diseases is characterized by a common pathological mechanism—accumulation of misfolded and unfolded proteins within the cells. Under certain circumstances, such protein aggregates may evoke endoplasmic reticulum (ER) stress conditions and subsequent activation of the unfolded protein response (UPR) signaling pathways via the protein kinase RNA-like endoplasmic reticulum kinase (PERK)-dependent manner. Under mild to moderate ER stress, UPR has a pro-adaptive role. However, severe or long-termed ER stress conditions directly evoke shift of the UPR toward its pro-apoptotic branch, which is considered to be a possible cause of neurodegeneration. To this day, there is no effective cure for Alzheimer’s disease (AD), Parkinson’s disease (PD), Huntington’s disease (HD), or prion disease. Currently available treatment approaches for these diseases are only symptomatic and cannot affect the disease progression. Treatment strategies, currently under detailed research, include inhibition of the PERK-dependent UPR signaling branches. The newest data have reported that the use of small-molecule inhibitors of the PERK-mediated signaling branches may contribute to the development of a novel, ground-breaking therapeutic approach for neurodegeneration. In this review, we critically describe all the aspects associated with such targeted therapy against neurodegenerative proteopathies.

scholarly journals The Redox System inC. elegans, a Phylogenetic Approach

2012 ◽  
Vol 2012 ◽  
pp. 1-20 ◽  
Author(s):  
Andrew D. Johnston ◽  
Paul R. Ebert
Keyword(s):  
Oxidative Stress ◽  
Oxidative Damage ◽  
Cellular Damage ◽  
Future Research ◽  
Homologous Proteins ◽  
Redox Biology ◽  
Redox Signalling ◽  
C Elegans ◽  
Age Related

Oxidative stress is a toxic state caused by an imbalance between the production and elimination of reactive oxygen species (ROS). ROS cause oxidative damage to cellular components such as proteins, lipids, and nucleic acids. While the role of ROS in cellular damage is frequently all that is noted, ROS are also important in redox signalling. The “Redox Hypothesis" has been proposed to emphasize a dual role of ROS. This hypothesis suggests that the primary effect of changes to the redox state is modified cellular signalling rather than simply oxidative damage. In extreme cases, alteration of redox signalling can contribute to the toxicity of ROS, as well as to ageing and age-related diseases. The nematode speciesCaenorhabditis elegansprovides an excellent model for the study of oxidative stress and redox signalling in animals. We use protein sequences from central redox systems inHomo sapiens,Drosophila melanogaster, andSaccharomyces cerevisiaeto query Genbank for homologous proteins inC. elegans. We then use maximum likelihood phylogenetic analysis to compare protein families betweenC. elegansand the other organisms to facilitate future research into the genetics of redox biology.

scholarly journals An economical and highly adaptable optogenetics system for individual and population-level manipulation of Caenorhabditis elegans

BMC Biology ◽  
2021 ◽  
Vol 19 (1) ◽  
Author(s):  
M. Koopman ◽  
L. Janssen ◽  
E. A. A. Nollen
Keyword(s):  
Caenorhabditis Elegans ◽  
Light Stimulus ◽  
Cholinergic Neurons ◽  
Model Organisms ◽  
Parameter Study ◽  
Multiple Model ◽  
Excitable Cells ◽  
Specific Expression ◽  
C Elegans ◽  
Age Related

Abstract Background Optogenetics allows the experimental manipulation of excitable cells by a light stimulus without the need for technically challenging and invasive procedures. The high degree of spatial, temporal, and intensity control that can be achieved with a light stimulus, combined with cell type-specific expression of light-sensitive ion channels, enables highly specific and precise stimulation of excitable cells. Optogenetic tools have therefore revolutionized the study of neuronal circuits in a number of models, including Caenorhabditis elegans. Despite the existence of several optogenetic systems that allow spatial and temporal photoactivation of light-sensitive actuators in C. elegans, their high costs and low flexibility have limited wide access to optogenetics. Here, we developed an inexpensive, easy-to-build, modular, and adjustable optogenetics device for use on different microscopes and worm trackers, which we called the OptoArm. Results The OptoArm allows for single- and multiple-worm illumination and is adaptable in terms of light intensity, lighting profiles, and light color. We demonstrate OptoArm’s power in a population-based multi-parameter study on the contributions of motor circuit cells to age-related motility decline. We found that individual components of the neuromuscular system display different rates of age-dependent deterioration. The functional decline of cholinergic neurons mirrors motor decline, while GABAergic neurons and muscle cells are relatively age-resilient, suggesting that rate-limiting cells exist and determine neuronal circuit ageing. Conclusion We have assembled an economical, reliable, and highly adaptable optogenetics system which can be deployed to address diverse biological questions. We provide a detailed description of the construction as well as technical and biological validation of our set-up. Importantly, use of the OptoArm is not limited to C. elegans and may benefit studies in multiple model organisms, making optogenetics more accessible to the broader research community.

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

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.

scholarly journals PGC-1α regulates mitochondrial properties beyond biogenesis with aging and exercise training

2019 ◽  
Vol 317 (3) ◽  
pp. E513-E525 ◽  
Author(s):  
Jens Frey Halling ◽  
Henrik Jessen ◽  
Jacob Nøhr-Meldgaard ◽  
Bjørg Thiellesen Buch ◽  
Natascha Masselkhi Christensen ◽  
...  
Keyword(s):  
Exercise Training ◽  
Network Structure ◽  
Molecular Mechanisms ◽  
Metabolic Diseases ◽  
Adenine Nucleotide ◽  
Dependent Manner ◽  
Mitochondrial Network ◽  
Inner Mitochondrial Membrane ◽  
Respiratory Capacity ◽  
Age Related

Impaired mitochondrial function has been implicated in the pathogenesis of age-associated metabolic diseases through regulation of cellular redox balance. Exercise training is known to promote mitochondrial biogenesis in part through induction of the transcriptional coactivator peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α). Recently, mitochondrial ADP sensitivity has been linked to reactive oxygen species (ROS) emission with potential impact on age-associated physiological outcomes, but the underlying molecular mechanisms remain unclear. Therefore, the present study investigated the effects of aging and exercise training on mitochondrial properties beyond biogenesis, including respiratory capacity, ADP sensitivity, ROS emission, and mitochondrial network structure, in myofibers from inducible muscle-specific PGC-1α-knockout mice and control mice. Aged mice displayed lower running endurance and mitochondrial respiratory capacity than young mice. This was associated with intermyofibrillar mitochondrial network fragmentation, diminished submaximal ADP-stimulated respiration, increased mitochondrial ROS emission, and oxidative stress. Exercise training reversed the decline in maximal respiratory capacity independent of PGC-1α, whereas exercise training rescued the age-related mitochondrial network fragmentation and the impaired submaximal ADP-stimulated respiration in a PGC-1α-dependent manner. Furthermore, lack of PGC-1α was associated with altered phosphorylation and carbonylation of the inner mitochondrial membrane ADP/ATP exchanger adenine nucleotide translocase 1. In conclusion, the present study provides evidence that PGC-1α regulates submaximal ADP-stimulated respiration, ROS emission, and mitochondrial network structure in mouse skeletal muscle during aging and exercise training.

scholarly journals Reticulon proteins modulate autophagy of the endoplasmic reticulum in maize endosperm

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Xiaoguo Zhang ◽  
Xinxin Ding ◽  
Richard Scott Marshall ◽  
Julio Paez-Valencia ◽  
Patrick Lacey ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Er Stress ◽  
Lipid Droplets ◽  
Autophagic Flux ◽  
Dependent Manner ◽  
Maize Endosperm ◽  
Transmembrane Segments ◽  
C Terminus ◽  
Er Homeostasis ◽  
Dose Dependent

Reticulon (Rtn) proteins shape tubular domains of the endoplasmic reticulum (ER), and in some cases are autophagy receptors for selective ER turnover. We have found that maize Rtn1 and Rtn2 control ER homeostasis and autophagic flux in endosperm aleurone cells, where the ER accumulates lipid droplets and synthesizes storage protein accretions metabolized during germination. Maize Rtn1 and Rtn2 are expressed in the endosperm, localize to the ER, and re-model ER architecture in a dose-dependent manner. Rtn1 and Rtn2 interact with Atg8a using four Atg8-interacting motifs (AIMs) located at the C-terminus, cytoplasmic loop, and within the transmembrane segments. Binding between Rtn2 and Atg8 is elevated upon ER stress. Maize rtn2 mutants display increased autophagy and up-regulation of an ER stress-responsive chaperone. We propose that maize Rtn1 and Rtn2 act as receptors for autophagy-mediated ER turnover, and thus are critical for ER homeostasis and suppression of ER stress.

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