HSF-1 regulators DDL-1/2 link insulin-like signaling to heat-shock responses and modulation of longevity

Transposable Elements Drive Regulatory and Functional Innovation of F-box Genes

Protein domains of transposable elements (TEs) and viruses increase the protein diversity of host genomes by recombining with other protein domains. By screening 10 million eukaryotic proteins, we identified several domains that define multicopy gene families and frequently co-occur with TE/viral domains. Among these, a Tc1/Mariner transposase helix-turn-helix (HTH) domain was captured by F-box genes in the Caenorhabditis genus, creating a new class of F-box genes. For specific members of this class, like fbxa-215, we found that the HTH domain is required for diverse processes including germ granule localization, fertility, and thermotolerance. Furthermore, we provide evidence that Heat Shock Factor 1 (HSF-1) mediates the transcriptional integration of fbxa-215 into the heat shock response by binding to Helitron TEs directly upstream of the fbxa-215 locus. The interactome of HTH-bearing F-box factors suggests roles in post-translational regulation and proteostasis, consistent with established functions of F-box proteins. Based on AlphaFold2 multimer proteome-wide screens, we propose that the HTH domain may diversify the repertoire of protein substrates that F-box factors regulate post-translationally. We also describe an independent capture of a TE domain by F-box genes in zebrafish. In conclusion, we identify two independent TE domain captures by F-box genes in eukaryotes and provide insights into how these novel proteins are integrated within host gene regulatory networks.

Stress-dependent activation of PQM-1 orchestrates a second-wave proteostasis response for organismal survival

Stress responses are controlled by specialized stress-responsive proteostasis transcription factors that rapidly upregulate protein quality components to re-establish protein homeostasis and safeguard survival. Here we show that the zinc finger transcription factor PQM-1 is crucial for stress survival in response to thermal and oxidative challenges. We provide mechanistic insight into the regulation of PQM-1 during stress that depends on ILS-DAF-16 signaling, as well as phosphorylation on threonine residue 268 that is located within a conserved AKT motif. Our data show that in reproductively mature adults and during well-fed conditions, PQM-1 induction requires DAF-16 and occurs during the recovery period post heat shock. Moreover, PQM-1 co-localizes with DAF-16 in the nucleus during the stress recovery phase. This regulatory dependency on DAF-16 is bypassed under dietary restriction, allowing PQM-1 to promote stress resilience independent of the ILS pathway. During both conditions, PQM-1 is crucial for the upregulation of cytosolic and endoplasmic reticulum stress response genes required for organismal recovery and stress resilience. Our transcriptional and bioinformatic analysis reveals that PQM-1 regulates a distinct set of target genes during the stress recovery phase, suggesting that PQM-1 may be involved in vital secondary wave stress response. Thus, our findings uncover a previously unrecognized mechanism of stress-dependent PQM-1 activation that integrates multiple environmental cues to ensure proteostasis and organismal survival.

Crassifolin A prolongs lifespan and healthspan in Caenorhabditis elegans via activating autophagy

ETHNOPHARMACOLOGICAL RELEVANCE

The root of Croton crassifolius Geiseler (C. crassifolius), commonly known as "Jiguxiang" in traditional Chinese medicine, is globally recognized for its ethnomedical applications in treating a spectrum of diseases. Crassifolin A (CA), a diterpenoid compound extracted from the roots of C. crassifolius, exhibits anti-herpes simplex virus (HSV), anti-viral and anti-angiogenic properties.

AIM OF THE REVIEW

This study aimed to explore the effects of CA on aging and the mechanisms involved.

MATERIALS AND METHODS

Utilizing Caenorhabditis elegans (C. elegans) as a model organism, we conducted a comprehensive survival analysis and evaluated aging-related phenotypes, including the period of fast body movement and body bending rates. To elucidate the molecular mechanisms of CA's impact on aging, we employed a multifaceted approach, including reverse transcription quantitative polymerase chain reaction (RT-qPCR), western blotting, and fluorescence quantification of transgenic reporter strains.

RESULTS

Our findings demonstrated that CA significantly prolonged both the lifespan and healthspan of C. elegans. The survival benefits conferred by CA were found to correlate with the activation of several key aging-related signaling pathways, including insulin/insulin-like signaling pathway (IIS), dietary restriction (DR) pathway, and germline signaling pathway. Engagement of these pathways led to the activation of transcription factors DAF-16/FOXO, SKN-1/NRF2, HSF-1 and HLH-30/TFEB, as well as the nuclear receptor DAF-12. Consequently, this activation cascade prompted an upregulation of autophagy, a cellular process associated with the maintenance of cellular homeostasis and longevity.

CONCLUSION

Our study delineates novel mechanisms underlying anti-aging strategies, establishing a conceptual framework for the exploitation and advancement of traditional Chinese medicinal herbs as potential therapeutic agents in the fight against aging and its associated pathologies.

Male sex determination maintains proteostasis and extends lifespan of daf-18/PTEN deficient C. elegans

Although females typically have a survival advantage, those with PTEN functional abnormalities face a higher risk of developing tumors than males. However, the differences in how each sex responds to PTEN dysfunction have rarely been studied. We use Caenorhabditis elegans to investigate how male and hermaphrodite worms respond to dysfunction of the PTEN homolog daf-18. Our study reveals that male worms can counterbalance the negative effects of daf-18 deficiency, resulting in longer adult lifespan. The survival advantage depends on the loss of DAF-18 protein phosphatase activity, while its lipid phosphatase activity is dispensable. The deficiency in DAF-18 protein phosphatase activity leads to the failure of dephosphorylation of the endoplasmic reticulum membrane protein C18E9.2/SEC62, causing increased levels of unfolded and aggregated proteins in hermaphrodites. In contrast, males maintain proteostasis through a UNC-23/NEF-mediated protein ubiquitination and degradation process, providing them with a survival advantage. We find that sex determination is a key factor in regulating the differential expression of unc-23 between sexes in response to daf-18 loss. These findings highlight the unique role of the male sex determination pathway in regulating protein degradation.

The neurohormone tyramine stimulates the secretion of an insulin-like peptide from the Caenorhabditis elegans intestine to modulate the systemic stress response

The DAF-2/insulin/insulin-like growth factor signaling (IIS) pathway plays an evolutionarily conserved role in regulating reproductive development, life span, and stress resistance. In Caenorhabditis elegans, DAF-2/IIS signaling is modulated by an extensive array of insulin-like peptides (ILPs) with diverse spatial and temporal expression patterns. However, the release dynamics and specific functions of these ILPs in adapting to different environmental conditions remain poorly understood. Here, we show that the ILP, insulin-3 (INS-3), plays a crucial role in modulating the response to various environmental stressors in C. elegans. ins-3 mutants display increased resistance to heat, oxidative stress, and starvation; however, this advantage is countered by slower reproductive development under favorable conditions. We find that ins-3 expression is downregulated in response to environmental stressors, whereas, the neurohormone tyramine, which is released during the acute flight response, increases ins-3 expression. We show that tyramine induces intestinal calcium (Ca2+) transients through the activation of the TYRA-3 receptor. Our data support a model in which tyramine negatively impacts environmental stress resistance by stimulating the release of INS-3 from the intestine via the activation of a TYRA-3-Gαq-IP3 pathway. The release of INS-3 systemically activates the DAF-2 pathway, resulting in the inhibition of cytoprotective mechanisms mediated by DAF-16/FOXO. These studies offer mechanistic insights into a brain-gut communication pathway that weighs adaptive strategies to respond to acute and long-term stressors.

Low molecular weight polysaccharide of Tremella fuciformis exhibits stronger antioxidant and immunomodulatory activities than high molecular weight polysaccharide

Low molecular weight polysaccharides had higher bio-activity and bioavailability compared to ultra-high molecular weight polysaccharides, this study aimed to obtain low molecular weight polysaccharides from Tremella fuciformis (TFLP) by using high-temperature and high-pressure assisted hydrochloric acid method to degrade Tremella fuciformis polysaccharides (TFP), and the structural characteristics, in vivo antioxidant and immune enhancing activities of TFP and TFLP was explored through Caenorhabditis elegans (C. elegans) and mice model. It was found that TFP and TFLP were acidic polysaccharides with molecular weights of 2238 kDa and 3 kDa, respectively. The glycosidic bonding of TFP and TFLP was mainly composed of different configurations of mannopyranose. TFP and TFLP had excellent in vivo antioxidant activity and stress resistance by regulating the mRNA transcription level and metabolites in C. elegans. Results also showed that TFP and TFLP could enhance the antioxidant capacity and immunity of serum, spleen and small intestine tissues in normal mice and cyclophosphamide-induced immunosuppressive mice through regulating the relative transcription and expression levels of anti-inflammatory related signaling factors, and it has found that TFLP showed better immune enhancement and antioxidant activity than TFP. In addition, Akkermansia, Bacteroides and Alloprevotella were characteristic bacteria at the genus level in immunosuppressed mice intervened with TFLP, with a significant increase in relative abundance. The content of SCFAs significantly increased in immunosuppressed mice by TFLP. These results indicated that TFP and TFLP had potential in vivo antioxidant and immune enhancing activities.

Paeonol promotes longevity and fitness in Caenorhabditis elegans through activating the DAF-16/FOXO and SKN-1/Nrf2 transcription factors

Paeonol, as one of the most abundant plant-derived polyphenols, has multiple bioactivities including anti-inflammatory, anti-tumor, and anti-cardiovascular diseases. Nevertheless, the anti-aging effects and related mechanisms of paeonol are rarely reported. In this study, we found that paeonol significantly prolonged the mean lifespan of Caenorhabditis elegans (C. elegans) by 28.49% at a dose of 200 μM. Moreover, paeonol promoted the health of C. elegans by increasing the body bending and pharyngeal pumping rates and reducing the lipofuscin accumulation level. Meanwhile, paeonol induced the expression of stress-related genes or proteins by activating the transcription factors DAF-16/FOXO, SKN-1/Nrf2, and HSF-1, which in turn enhanced oxidative and thermal stress tolerance. The mechanism behind the anti-aging effect of paeonol occurred by down-regulating the insulin/IGF-1 signaling (IIS) pathway. Our findings shed new light on the application of paeonol for longevity promotion and human health.

The neurohormone tyramine stimulates the secretion of an Insulin-Like Peptide from the intestine to modulate the systemic stress response in C. elegans

The DAF-2/insulin/insulin-like growth factor signaling (IIS) pathway plays an evolutionarily conserved role in regulating reproductive development, lifespan, and stress resistance. In C. elegans , DAF-2/IIS signaling is modulated by an extensive array of insulin-like peptides (ILPs) with diverse spatial and temporal expression patterns. However, the release dynamics and specific functions of these ILPs in adapting to different environmental conditions remain poorly understood. Here, we show that the ILP, INS-3, plays a crucial role in modulating the response to different types of stressors in C. elegans . ins-3 mutants display increased resistance to both heat and oxidative stress; however, under favorable conditions, this advantage is countered by slower reproductive development. ins-3 expression in both neurons and the intestine is downregulated in response to environmental stressors. Conversely, the neurohormone tyramine, which is released during the acute flight response, triggers an upregulation in ins-3 expression. Moreover, we found that tyramine negatively impacts environmental stress resistance by stimulating the release of INS-3 from the intestine. The subsequent release of INS-3 systemically activates the DAF-2 pathway, resulting in the inhibition of cytoprotective mechanisms mediated by DAF-16/FOXO and HSF-1. These studies offer mechanistic insights into the brain-gut communication pathway that weighs adaptive strategies to respond to acute and long-term stress scenarios.

The Effects of Housing on Growth, Immune Function and Antioxidant Status of Young Female Lambs in Cold Conditions

Cold conditions in northern China during winter may reduce sheep growth and affect their health, especially if they are young, unless housing is provided. We allocated 45 two-month-old female lambs to be housed in an enclosed building, a polytunnel, or kept outdoors, for 28 days. The daily weight gain and scalp and ear skin temperature of outdoor lambs were less than those of lambs that were housed in either a house or polytunnel; however, rectal temperature was unaffected by treatment. There was a progressive change in blood composition over time, and by the end of the experiment, outdoor lambs had reduced total antioxidant capacity (T-AOC), catalase (CAT), glutathione peroxidase (GSH-Px) and total superoxide dismutase (T-SOD) and increased malondialdehyde compared to those in the house or polytunnel. In relation to immune responses in the lambs' serum, in the polytunnel, immunoglobulin A (IgA), tumor necrosis factor-α (TNF-α) and interleukin-4 (IL-4) were higher and immunoglobulin G (IgG) lower compared with the concentrations in lambs that were outdoors. Over the course of the experiment, genes expressing heat shock proteins and antioxidant enzymes increased in lambs in the outdoor treatment, whereas they decreased in lambs in the indoor treatments. It is concluded that although there were no treatment effects on core body temperature, the trends for progressive changes in blood composition and gene expression indicate that the outdoor lambs were not physiologically stable; hence, they should not be kept outdoors in these environmental conditions for long periods.

Cronobacter sakazakii infection implicates multifaceted neuro-immune regulatory pathways of Caenorhabditis elegans

The neural pathways of Caenorhabditis elegans play a crucial role in regulating host immunity and inflammation during pathogenic infections. To understand the major neuro-immune signaling pathways, this study aimed to identify the key regulatory proteins in the host C. elegans during C. sakazakii infection. We used high-throughput label-free quantitative proteomics and identified 69 differentially expressed proteins. KEGG analysis revealed that C. sakazakii elicited host immune signaling cascades primarily including mTOR signaling, axon regeneration, metabolic pathways (let-363 and acox-1.4), calcium signaling (mlck-1), and longevity regulating pathways (ddl-2), respectively. The abrogation in functional loss of mTOR-associated players deciphered that C. sakazakii infection negatively regulated the lifespan of mutant worms (akt-1, let-363 and dlk-1), including physiological aberrations, such as reduced pharyngeal pumping and egg production. Additionally, the candidate pathway proteins were validated by transcriptional profiling of their corresponding genes. Furthermore, immunoblotting showed the downregulation of mTORC2/SGK-1 during the later hours of pathogen exposure. Overall, our findings profoundly provide an understanding of the specificity of proteome imbalance in affecting neuro-immune regulations during C. sakazakii infection.

TGF-β pathways in aging and immunity: lessons from Caenorhabditis elegans

The Transforming Growth Factor-β (TGF-β) superfamily of signaling molecules plays critical roles in development, differentiation, homeostasis, and disease. Due to the conservation of these ligands and their signaling pathways, genetic studies in invertebrate systems including the nematode Caenorhabditis elegans have been instrumental in identifying signaling mechanisms. C. elegans is also a premier organism for research in longevity and healthy aging. Here we summarize current knowledge on the roles of TGF-β signaling in aging and immunity.

Lycium barbarum glycopetide prolong lifespan and alleviate Parkinson's disease in Caenorhabditis elegans

Introduction

Lycium barbarum glycopeptide (LbGp) is the main bioactive compound extracted from the traditional Chinese medicine. L. barbarum berries and has been proven to have numerous health benefits, including antioxidative, anti-inflammatory, anticancer, and cytoprotective activities. However, the antiaging effect of LbGp remains unknown.

Methods

The lifespan and body movement of C. elegans were used to evaluate the effect of LbGp on lifespan and health span. The thrashing assay was used to determine the role of LbGp in Parkinson's disease. To investigate the mechanisms of LbGp-induced antiaging effects, we analyzed changes in lifespan, movement, and the expression of longevity-related genes in a series of worm mutants after LbGp treatment.

Results

We found that LbGp treatment prolonged the lifespan and health span of C. elegans. Mechanistically, we found that LbGp could activate the transcription factors DAF-16/FOXO, SKN-1/Nrf2, and HSF-1, as well as the nuclear receptor DAF-12, thereby upregulating longevity-related genes to achieve lifespan extension. In addition, we found that the lifespan extension induced by LbGp partially depends on mitochondrial function. Intriguingly, LbGp also ameliorated neurodegenerative diseases such as Parkinson's disease in a DAF-16-, SKN-1-, and HSF-1-dependent manner.

Conclusion

Our work suggests that LbGp might be a viable candidate for the treatment and prevention of aging and age-related diseases.

Consumption of commonly used artificial food dyes increases activity and oxidative stress in the animal model Caenorhabditis elegans

In recent decades, the consumption of artificial colorants in foods and beverages has increased despite of concerns in the general population raised by studies that have shown possible injurious effects. In this study, tartrazine, sunset yellow, quinoline yellow, ponceau 4R, carmoisine and allura red were employed as pure compounds to explore their effects in vivo in the animal model Caenorhabditis elegans. The exposition of C. elegans to these artificial dyes produced damage related with aging such as oxidative stress and lipofuscin accumulation, as well as a heavy shortening of lifespan, alterations in movement patterns and alterations in the production of dopamine receptors. Besides, microarray analysis performed with worms treated with tartrazine and ponceau 4R showed how the consumption of synthetic colorants is able to alter the expression of genes involved in resistance to oxidative stress and neurodegeneration.

Biological resilience and aging: Activation of stress response pathways contributes to lifespan extension

While aging was traditionally viewed as a stochastic process of damage accumulation, it is now clear that aging is strongly influenced by genetics. The identification and characterization of long-lived genetic mutants in model organisms has provided insights into the genetic pathways and molecular mechanisms involved in extending longevity. Long-lived genetic mutants exhibit activation of multiple stress response pathways leading to enhanced resistance to exogenous stressors. As a result, lifespan exhibits a significant, positive correlation with resistance to stress. Disruption of stress response pathways inhibits lifespan extension in multiple long-lived mutants representing different pathways of lifespan extension and can also reduce the lifespan of wild-type animals. Combined, this suggests that activation of stress response pathways is a key mechanism by which long-lived mutants achieve their extended longevity and that many of these pathways are also required for normal lifespan. These results highlight an important role for stress response pathways in determining the lifespan of an organism.

Proteomics identifies differentially expressed proteins in glioblastoma U87 cells treated with hederagenin

OBJECTIVE

We investigated differentially expressed proteins (DEPs) in human glioblastoma U87 cells after treatment with hederagenin as a therapeutic screening mechanism and provided a theoretical basis for hederagenin in treating glioblastoma.

METHODS

The Cell Counting Kit 8 assay was used to analyze the inhibitory effect of hederagenin on the proliferation of U87 cells. Protein was identified by tandem mass tags and LC-MS/MS analysis techniques. Annotation of DEPs, Gene Ontology enrichment and function, and Kyoto Encyclopedia of Genes and Genomes pathways and domains were all examined by bioinformatics. According to the TMT results, hub protein was selected from DEPs for WB verification.

RESULTS

Protein quantitative analysis found 6522 proteins in total. Compared with the control group, 43 DEPs (P < 0.05) were involved in the highly enriched signaling pathway in the hederagenin group, among which 20 proteins were upregulated, and 23 proteins were downregulated. These different proteins are mainly involved in the longness regulating pathway-WORM, the hedgehog signaling pathway, Staphylococcus aureus infection, complement, coagulation cascades, and mineral absorption. KIF7 and ATAD2B expression were significantly down-regulated and PHEX and TIMM9 expression were significantly upregulated, according to WB analysis, supporting the TMT findings.

CONCLUSION

Hederagenin inhibition of GBM U87 cells may be related to KIF7, which is mainly involved in the hedgehog signaling pathway. Our findings lay a foundation for additional study of the therapeutic mechanism of hederagenin.

Regulation of germline proteostasis by HSF1 and insulin/IGF-1 signaling

Protein homeostasis (proteostasis) is essential for cellular function and organismal health and requires the concerted actions of protein synthesis, folding, transport, and turnover. In sexually reproducing organisms, the immortal germline lineage passes genetic information across generations. Accumulating evidence indicates the importance of proteome integrity for germ cells as genome stability. As gametogenesis involves very active protein synthesis and is highly energy-demanding, it has unique requirements for proteostasis regulation and is sensitive to stress and nutrient availability. The heat shock factor 1 (HSF1), a key transcriptional regulator of cellular response to cytosolic and nuclear protein misfolding has evolutionarily conserved roles in germline development. Similarly, insulin/insulin-like growth factor-1 (IGF-1) signaling, a major nutrient-sensing pathway, impacts many aspects of gametogenesis. Here, we focus on HSF1 and IIS to review insights into their roles in germline proteostasis and discuss the implications on gamete quality control during stress and aging.

Chilo suppressalis heat shock proteins are regulated by heat shock factor 1 during heat stress

Heat shock factor 1 (HSF1) functions to maintain cellular and organismal homeostasis by regulating the expression of target genes, including those encoding heat shock proteins (HSPs). In the present study, the gene encoding HSF1 was cloned from the rice pest Chilo suppressalis, and designated Cshsf1. The deduced protein product, CsHSF1, contained conserved domains typical of the HSF1 family, including a DNA-binding domain, two hydrophobic heptad repeat domains, and a C-terminal transactivation domain. Real-time quantitative PCR showed that Cshsf1 was highly expressed in hemocytes. Expression analysis in different developmental stages of C. suppressalis revealed that Cshsf1 was most highly expressed in male adults. RNAi-mediated silencing of Cshsf1 expression reduced C. suppressalis survival at high temperatures. To investigate the regulatory interactions between Cshsf1 and Cshsps, the promoters and expression patterns of 18 identified Cshsps in C. suppressalis were analysed; four types of heat shock elements (HSEs) were identified in promoter regions including canonical, tail-tail, head-head, and step/gap. The expression of Cshsp19.0, Cshsp21.7B, Cshsp60, Cshsp70 and Cshsp90 was positively regulated by Cshsf1; however, Cshsp22.8, Cshsp702, Cshsp705 and Cshsp706 gene expression was not altered. This study provides a foundation for future studies of HSF1 in insects during thermal stress.

HSF1 and Its Role in Huntington's Disease Pathology

PURPOSE OF REVIEW

Heat shock factor 1 (HSF1) is the master transcriptional regulator of the heat shock response (HSR) in mammalian cells and is a critical element in maintaining protein homeostasis. HSF1 functions at the center of many physiological processes like embryogenesis, metabolism, immune response, aging, cancer, and neurodegeneration. However, the mechanisms that allow HSF1 to control these different biological and pathophysiological processes are not fully understood. This review focuses on Huntington's disease (HD), a neurodegenerative disease characterized by severe protein aggregation of the huntingtin (HTT) protein. The aggregation of HTT, in turn, leads to a halt in the function of HSF1. Understanding the pathways that regulate HSF1 in different contexts like HD may hold the key to understanding the pathomechanisms underlying other proteinopathies. We provide the most current information on HSF1 structure, function, and regulation, emphasizing HD, and discussing its potential as a biological target for therapy.

DATA SOURCES

We performed PubMed search to find established and recent reports in HSF1, heat shock proteins (Hsp), HD, Hsp inhibitors, HSF1 activators, and HSF1 in aging, inflammation, cancer, brain development, mitochondria, synaptic plasticity, polyglutamine (polyQ) diseases, and HD.

STUDY SELECTIONS

Research and review articles that described the mechanisms of action of HSF1 were selected based on terms used in PubMed search.

RESULTS

HSF1 plays a crucial role in the progression of HD and other protein-misfolding related neurodegenerative diseases. Different animal models of HD, as well as postmortem brains of patients with HD, reveal a connection between the levels of HSF1 and HSF1 dysfunction to mutant HTT (mHTT)-induced toxicity and protein aggregation, dysregulation of the ubiquitin-proteasome system (UPS), oxidative stress, mitochondrial dysfunction, and disruption of the structural and functional integrity of synaptic connections, which eventually leads to neuronal loss. These features are shared with other neurodegenerative diseases (NDs). Currently, several inhibitors against negative regulators of HSF1, as well as HSF1 activators, are developed and hold promise to prevent neurodegeneration in HD and other NDs.

CONCLUSION

Understanding the role of HSF1 during protein aggregation and neurodegeneration in HD may help to develop therapeutic strategies that could be effective across different NDs.

Aging of mesenchymal stem cell: machinery, markers, and strategies of fighting

Human mesenchymal stem cells (MSCs) are primary multipotent cells capable of differentiating into osteocytes, chondrocytes, and adipocytes when stimulated under appropriate conditions. The role of MSCs in tissue homeostasis, aging-related diseases, and cellular therapy is clinically suggested. As aging is a universal problem that has large socioeconomic effects, an improved understanding of the concepts of aging can direct public policies that reduce its adverse impacts on the healthcare system and humanity. Several studies of aging have been carried out over several years to understand the phenomenon and different factors affecting human aging. A reduced ability of adult stem cell populations to reproduce and regenerate is one of the main  contributors to the human aging process. In this context, MSCs senescence is a major challenge in front of cellular therapy advancement. Many factors, ranging from genetic and metabolic pathways to extrinsic factors through various cellular signaling pathways, are involved in regulating the mechanism of MSC senescence. To better understand and reverse cellular senescence, this review highlights the underlying mechanisms and signs of MSC cellular senescence, and discusses the strategies to combat aging and cellular senescence.

The Thermal Stress Coping Network of the Nematode Caenorhabditis elegans

Response to hyperthermia, highly conserved from bacteria to humans, involves transcriptional upregulation of genes involved in battling the cytotoxicity caused by misfolded and denatured proteins, with the aim of proteostasis restoration. C. elegans senses and responds to changes in growth temperature or noxious thermal stress by well-defined signaling pathways. Under adverse conditions, regulation of the heat shock response (HSR) in C. elegans is controlled by a single transcription factor, heat-shock factor 1 (HSF-1). HSR and HSF-1 in particular are proven to be central to survival under proteotoxic stress, with additional roles in normal physiological processes. For years, it was a common belief that upregulation of heat shock proteins (HSPs) by HSF-1 was the main and most important step toward thermotolerance. However, an ever-growing number of studies have shown that targets of HSF-1 involved in cytoskeletal and exoskeletal integrity preservation as well as other HSF-1 dependent and independent pathways are equally important. In this review, we follow the thermal stimulus from reception by the nematode nerve endings till the activation of cellular response programs. We analyze the different HSF-1 functions in HSR as well as all the recently discovered mechanisms that add to the knowledge of the heat stress coping network of C. elegans.

The unfolded protein response reverses the effects of glucose on lifespan in chemically-sterilized C. elegans

Metabolic diseases often share common traits, including accumulation of unfolded proteins in the endoplasmic reticulum (ER). Upon ER stress, the unfolded protein response (UPR) is activated to limit cellular damage which weakens with age. Here, we show that Caenorhabditis elegans fed a bacterial diet supplemented high glucose at day 5 of adulthood (HGD-5) extends their lifespan, whereas exposed at day 1 (HGD-1) experience shortened longevity. We observed a metabolic shift only in HGD-1, while glucose and infertility synergistically prolonged the lifespan of HGD-5, independently of DAF-16. Notably, we identified that UPR stress sensors ATF-6 and PEK-1 contributed to the longevity of HGD-5 worms, while ire-1 ablation drastically increased HGD-1 lifespan. Together, we postulate that HGD activates the otherwise quiescent UPR in aged worms to overcome ageing-related stress and restore ER homeostasis. In contrast, young animals subjected to HGD provokes unresolved ER stress, conversely leading to a detrimental stress response.

Nicandra physalodes Extract Exerts Antiaging Effects in Multiple Models and Extends the Lifespan of Caenorhabditis elegans via DAF-16 and HSF-1

The development of safe and effective therapeutic interventions is an important issue for delaying aging and reducing the risk of aging-related diseases. Chinese herbal medicines for the treatment of aging and other complex diseases are desired due to their multiple components and targets. Through screening for effects on lifespan of 836 Chinese herbal medicine extracts, Nicandra physalodes extract (HL0285) was found to exhibit lifespan extension activity in Caenorhabditis elegans (C. elegans). In further experiments, HL0285 improved healthspan, enhanced stress resistance, and delayed the progression of neurodegenerative diseases in C. elegans. Additionally, it ameliorated senescence in human lung fibroblasts (MRC-5 cells) and reversed liver function damage and reduced senescence marker levels in doxorubicin- (Dox-) induced aging mice. In addition, the longevity effect of HL0285 in C. elegans was dependent on the DAF-16 and HSF-1 signaling pathways, as demonstrated by the results of the mutant lifespan, gene level, and GFP level assays. In summary, we discovered that HL0285 had an antiaging effect in C. elegans, MRC-5 cells, and Dox-induced aging mice and deserves to be explored in the future studies on antiaging agents.

Therapeutic Antiaging Strategies

Aging constitutes progressive physiological changes in an organism. These changes alter the normal biological functions, such as the ability to manage metabolic stress, and eventually lead to cellular senescence. The process itself is characterized by nine hallmarks: genomic instability, telomere attrition, epigenetic alterations, loss of proteostasis, deregulated nutrient sensing, mitochondrial dysfunction, cellular senescence, stem cell exhaustion, and altered intercellular communication. These hallmarks are risk factors for pathologies, such as cardiovascular diseases, neurodegenerative diseases, and cancer. Emerging evidence has been focused on examining the genetic pathways and biological processes in organisms surrounding these nine hallmarks. From here, the therapeutic approaches can be addressed in hopes of slowing the progression of aging. In this review, data have been collected on the hallmarks and their relative contributions to aging and supplemented with in vitro and in vivo antiaging research experiments. It is the intention of this article to highlight the most important antiaging strategies that researchers have proposed, including preventive measures, systemic therapeutic agents, and invasive procedures, that will promote healthy aging and increase human life expectancy with decreased side effects.

Longevity-promoting properties of ginger extract in Caenorhabditis elegans via the insulin/IGF-1 signaling pathway

Ginger is a traditional medicinal and edible plant with multiple health-promoting properties. Nevertheless, the effects and potential mechanism of ginger on antiaging remain unknown. The aim of this study was to comprehend the antiaging effects and potential mechanism of ginger in Caenorhabditis elegans (C. elegans). The current findings showed that the lifespan of C. elegans was prolonged by 23.16% with the supplementation of 60 μg mL-1 ginger extract (GE), and the extension of lifespan was mainly attributed to the major bioactive compounds in GE, 6-, 8-, 10-gingerol and 6-, 8-, 10-shogaol. Subsequently, GE promoted healthy aging by improving nematode movement and attenuating lipofuscin accumulation, and enhanced stress tolerance by up-regulating the expression of stress-related genes and activating DAF-16 and SKN-1. Moreover, lifespan assays of relative mutants revealed that GE mediated extension of lifespan via the insulin/IGF-1 signaling (IIS) pathway. In summary, GE endowed nematodes (C. elegans) with longevity and stress resistance in an IIS pathway dependent manner.

Anti-aging effects and mechanisms of anthocyanins and their intestinal microflora metabolites

Aging, a natural and inevitable physiological process, is the primary risk factor for all age-related diseases; it severely threatens the health of individuals and places a heavy burden on the public health-care system. Thus, strategies to extend the lifespan and prevent and treat age-related diseases have been gaining increasing scientific interest. Anthocyanins (ACNs) are a subclass of flavonoids widely distributed in fruits and vegetables. Growing evidence suggests that ACNs delay aging and relieve age-related diseases. However, owing to the low bioavailability of ACNs, their gut metabolites have been proposed to play a critical role in mediating health benefits. In this review, we introduce the biological fate of ACNs after consumption and highlight ACNs metabolites (phenolic acids) from intestinal microorganisms. Additionally, ACNs and gut metabolites exhibit outstanding anti-aging ability in Caenorhabditis elegans, Drosophila melanogaster, and mouse models, probably associated with increasing antioxidation, anti-inflammation, protein homeostasis, antiglycation, mitochondrial function, and inhibition of insulin/IGF-1 signaling (IIS). ACNs and gut metabolites have great application prospects as functional foods and drugs to delay aging and manage age-related diseases. Further investigation should focus on the interaction between ACNs and gut microbiota, including clarifying the complex metabolic pathway and maximizing the health effects of ACNs.

Scorpion Venom Heat–Resistant Synthesized Peptide Increases Stress Resistance and Extends the Lifespan of Caenorhabditis elegans via the Insulin/IGF-1-Like Signal Pathway

Improving healthy life expectancy by targeting aging-related pathological changes has been the spotlight of geroscience. Scorpions have been used in traditional medicine in Asia and Africa for a long time. We have isolated heat-resistant peptides from scorpion venom of Buthusmartensii Karsch (SVHRP) and found that SVHRP can attenuate microglia activation and protect Caenorhabditis elegans (C. elegans) against β-amyloid toxicity. Based on the amino acid sequence of these peptides, scorpion venom heat–resistant synthesized peptide (SVHRSP) was prepared using polypeptide synthesis technology. In the present study, we used C. elegans as a model organism to assess the longevity-related effects and underlying molecular mechanisms of SVHRSP in vivo. The results showed that SVHRSP could prolong the lifespan of worms and significantly improve the age-related physiological functions of worms. SVHRSP increases the survival rate of larvae under oxidative and heat stress and decreases the level of reactive oxygen species and fat accumulation in vivo. Using gene-specific mutation of C. elegans, we found that SVHRSP-mediated prolongation of life depends on Daf-2, Daf-16, Skn-1, and Hsf-1 genes. These results indicate that the antiaging mechanism of SVHRSP in nematodes might be mediated by the insulin/insulin-like growth factor-1 signaling pathway. Meanwhile, SVHRSP could also up-regulate the expression of stress-inducing genes Hsp-16.2, Sod-3, Gei-7, and Ctl-1 associated with aging. In general, our study may have important implications for SVHRSP to promote healthy aging and provide strategies for research and development of drugs to treat age-related diseases.

HSF-1: Guardian of the Proteome Through Integration of Longevity Signals to the Proteostatic Network

Discoveries made in the nematode Caenorhabditis elegans revealed that aging is under genetic control. Since these transformative initial studies, C. elegans has become a premier model system for aging research. Critically, the genes, pathways, and processes that have fundamental roles in organismal aging are deeply conserved throughout evolution. This conservation has led to a wealth of knowledge regarding both the processes that influence aging and the identification of molecular and cellular hallmarks that play a causative role in the physiological decline of organisms. One key feature of age-associated decline is the failure of mechanisms that maintain proper function of the proteome (proteostasis). Here we highlight components of the proteostatic network that act to maintain the proteome and how this network integrates into major longevity signaling pathways. We focus in depth on the heat shock transcription factor 1 (HSF1), the central regulator of gene expression for proteins that maintain the cytosolic and nuclear proteomes, and a key effector of longevity signals.

SIN-3 functions through multi-protein interaction to regulate apoptosis, autophagy, and longevity in Caenorhabditis elegans

SIN3/HDAC is a multi-protein complex that acts as a regulatory unit and functions as a co-repressor/co-activator and a general transcription factor. SIN3 acts as a scaffold in the complex, binding directly to HDAC1/2 and other proteins and plays crucial roles in regulating apoptosis, differentiation, cell proliferation, development, and cell cycle. However, its exact mechanism of action remains elusive. Using the Caenorhabditis elegans (C. elegans) model, we can surpass the challenges posed by the functional redundancy of SIN3 isoforms. In this regard, we have previously demonstrated the role of SIN-3 in uncoupling autophagy and longevity in C. elegans. In order to understand the mechanism of action of SIN3 in these processes, we carried out a comparative analysis of the SIN3 protein interactome from model organisms of different phyla. We identified conserved, expanded, and contracted gene classes. The C. elegans SIN-3 interactome -revealed the presence of  well-known proteins, such as DAF-16, SIR-2.1, SGK-1, and AKT-1/2, involved in autophagy, apoptosis, and longevity. Overall, our analyses propose  potential mechanisms by which SIN3 participates in multiple biological processes and their conservation across species and identifies candidate genes for further experimental analysis.

Pioglitazone Hydrochloride Extends the Lifespan of Caenorhabditis elegans by Activating DAF-16/FOXO- and SKN-1/NRF2-Related Signaling Pathways

Pioglitazone hydrochloride (PGZ), a nuclear receptor peroxisome proliferator-activated receptor gamma (PPAR-γ) agonist, is a universally adopted oral agent for the treatment of type 2 diabetes (T2D). Previous studies reported that PGZ could ameliorate the symptoms of aging-related diseases and Alzheimer's disease. However, whether PGZ participates in aging regulation and the underlying mechanism remain undetermined. Here, we found that PGZ significantly prolonged the lifespan and healthspan of Caenorhabditis elegans (C. elegans). We found that a variety of age-related pathways and age-related genes are required for PGZ-induced lifespan extension. The transcription factors DAF-16/FOXO, HSF-1, and SKN-1/NRF2, as well as the nuclear receptors DAF-12 and NHR-49, all functioned in the survival advantage conferred by PGZ. Moreover, our results demonstrated that PGZ induced lifespan extension through the inhibition of insulin/insulin-like signaling (IIS) and reproductive signaling pathways, as well as the activation of dietary restriction- (DR-) related pathways. Additionally, our results also indicated that beneficial longevity mediated by PGZ is linked to its antioxidative activity. Our research may provide a basis for further research on PGZ, as an anti-T2D drug, to interfere with aging and reduce the incidence of age-related diseases in diabetic patients.

Evolutionarily conserved transcription factors as regulators of longevity and targets for geroprotection

Aging is the single largest risk factor for many debilitating conditions, including heart diseases, stroke, cancer, diabetes, and neurodegenerative disorders. While far from understood in its full complexity, it is scientifically well-established that aging is influenced by genetic and environmental factors, and can be modulated by various interventions. One of aging's early hallmarks are aberrations in transcriptional networks, controlling for example metabolic homeostasis or the response to stress. Evidence in different model organisms abounds that a number of evolutionarily conserved transcription factors, which control such networks, can affect lifespan and healthspan across species. These transcription factors thus potentially represent conserved regulators of longevity and are emerging as important targets in the challenging quest to develop treatments to mitigate age-related diseases, and possibly even to slow aging itself. This review provides an overview of evolutionarily conserved transcription factors that impact longevity or age-related diseases in at least one multicellular model organism (nematodes, flies, or mice), and/or are tentatively linked to human aging. Discussed is the general evidence for transcriptional regulation of aging and disease, followed by a more detailed look at selected transcription factor families, the common metabolic pathways involved, and the targeting of transcription factors as a strategy for geroprotective interventions.

Dihydro-β-agarofuran-type sesquiterpenoids from the seeds of Celastrus virens with lifespan-extending effect on the nematode Caenorhabditis elegans

Twelve dihydro-β-agarofuran-type sesquiterpenoids, including five new ones (1-5), were purified from the seeds of Celastrus virens (Wang et Tang) C. Y. Chent et T. C. Kao. Their chemical structures were characterized via comprehensive spectroscopic analysis, single-crystal X-ray diffraction analysis, and computational prediction of ECD, as well as comparison of observed and reported NMR spectral data. Among the isolates, nine abundant dihydro-β-agarofuran-type sesquiterpenoids were evaluated for their lifespan-extending activity using the nematode Caenorhabditis elegans model. As a result, compounds 1, 2, 5, 6, 8, and 9 (50 μM) significantly extended the mean survival time of C. elegans, respectively, compared with the blank control group (p < 0.05). Further Quantitative RT-PCR showed that the prolonging of lifespan mediated by compounds 1, 6, 8, and 9 were dependent on the transcription factors skn-1 and hsf-1.

Neuropeptide signaling and SKN-1 orchestrate differential responses of the proteostasis network to dissimilar proteotoxic insults

The protein homeostasis (proteostasis) network (PN) encompasses mechanisms that maintain proteome integrity by controlling various biological functions. Loss of proteostasis leads to toxic protein aggregation (proteotoxicity), which underlies the manifestation of neurodegeneration. How the PN responds to dissimilar proteotoxic challenges and how these responses are regulated at the organismal level are largely unknown. Here, we report that, while torsin chaperones protect from the toxicity of neurodegeneration-causing polyglutamine stretches, they exacerbate the toxicity of the Alzheimer's disease-causing Aβ peptide in neurons and muscles. These opposing effects are accompanied by differential modulations of gene expression, including that of three neuropeptides that are involved in tailoring the organismal response to dissimilar proteotoxic insults. This mechanism is regulated by insulin/IGF signaling and the transcription factor SKN-1/NRF. Our work delineates a mechanism by which the PN orchestrates differential responses to dissimilar proteotoxic challenges and points at potential targets for therapeutic interventions.

Beta-cell specific Insr deletion promotes insulin hypersecretion and improves glucose tolerance prior to global insulin resistance

Insulin receptor (Insr) protein is present at higher levels in pancreatic β-cells than in most other tissues, but the consequences of β-cell insulin resistance remain enigmatic. Here, we use an Ins1cre knock-in allele to delete Insr specifically in β-cells of both female and male mice. We compare experimental mice to Ins1cre-containing littermate controls at multiple ages and on multiple diets. RNA-seq of purified recombined β-cells reveals transcriptomic consequences of Insr loss, which differ between female and male mice. Action potential and calcium oscillation frequencies are increased in Insr knockout β-cells from female, but not male mice, whereas only male βInsrKO islets have reduced ATP-coupled oxygen consumption rate and reduced expression of genes involved in ATP synthesis. Female βInsrKO and βInsrHET mice exhibit elevated insulin release in ex vivo perifusion experiments, during hyperglycemic clamps, and following i.p. glucose challenge. Deletion of Insr does not alter β-cell area up to 9 months of age, nor does it impair hyperglycemia-induced proliferation. Based on our data, we adapt a mathematical model to include β-cell insulin resistance, which predicts that β-cell Insr knockout improves glucose tolerance depending on the degree of whole-body insulin resistance. Indeed, glucose tolerance is significantly improved in female βInsrKO and βInsrHET mice compared to controls at 9, 21 and 39 weeks, and also in insulin-sensitive 4-week old males. We observe no improved glucose tolerance in older male mice or in high fat diet-fed mice, corroborating the prediction that global insulin resistance obscures the effects of β-cell specific insulin resistance. The propensity for hyperinsulinemia is associated with mildly reduced fasting glucose and increased body weight. We further validate our main in vivo findings using an Ins1-CreERT transgenic line and find that male mice have improved glucose tolerance 4 weeks after tamoxifen-mediated Insr deletion. Collectively, our data show that β-cell insulin resistance in the form of reduced β-cell Insr contributes to hyperinsulinemia in the context of glucose stimulation, thereby improving glucose homeostasis in otherwise insulin sensitive sex, dietary and age contexts.

Lycium barbarum Extracts Extend Lifespan and Alleviate Proteotoxicity in Caenorhabditis elegans

Lycium barbarum berry (Ningxia Gouqi, Fructus lycii, goji berry, or wolfberry), as a traditional Chinese herb, was recorded beneficial for longevity in traditional Chinese medical scriptures and currently is a natural dietary supplement worldwide. However, under modern experimental conditions, the longevity effect of L. barbarum berry and the underlying mechanisms have been less studied. Here, we reported that total water extracts of L. barbarum berry (LBE), which contains 22% polysaccharides and other components, such as anthocyanins, extended the lifespan of Caenorhabditis elegans without side effects on worm fertility and pharyngeal pumping. Interestingly, we found that the lifespan extension effect was more prominent in worms with shorter mean lifespan as compared to those with longer mean lifespan. Furthermore, we showed that the lifespan extension effect of LBE depended on deacetylase sir-2.1. Remarkably, LBE rescued heat shock transcription factor-1 (hsf-1) deficiency in wild-type worms with different mean lifespans, and this effect also depended on sir-2.1. In addition, we found that LBE extended lifespan and alleviated toxic protein aggregation in neurodegenerative worms with hsf-1 deficiency. Our study suggested that LBE may be a potential antiaging natural dietary supplement especially to individuals with malnutrition or chronic diseases and a potential therapeutic agent for neurodegenerative diseases characterized by hsf-1 deficiency.

Improving Analysis and Annotation of Microarray Data with Protein Interactions

Gene expression microarrays are one of the most widely used high-throughput technologies in molecular biology, with applications such as identification of disease mechanisms and development of diagnostic and prognostic gene signatures. However, the success of these tasks is often limited because microarray analysis does not account for the complex relationships among genes, their products, and overall signaling and regulatory cascades. Incorporating protein-protein interaction data into microarray analysis can help address these challenges. This chapter reviews how protein-protein interactions can help with microarray analysis, leading to benefits such as better explanations of disease mechanisms, more complete gene annotations, improved prioritization of genes for future experiments, and gene signatures that generalize better to new data.

Small berries as health-promoting ingredients: a review on anti-aging effects and mechanisms in Caenorhabditis elegans

Aging is an inevitable, irreversible, and complex process of damage accumulation and functional decline, increasing the risk of various chronic diseases. However, for now no drug can delay aging process nor cure aging-related diseases. Nutritional intervention is considered as a key and effective strategy to promote healthy aging and improve life quality. Small berries, as one of the most common and popular fruits, have been demonstrated to improve cognitive function and possess neuroprotective activities. However, the anti-aging effects of small berries have not been systematically elucidated yet. This review mainly focuses on small berries' anti-aging activity studies involving small berry types, active components, the utilized model organism Caenorhabditis elegans (C. elegans), related signaling pathways, and molecular mechanisms. The purpose of this review is to propose effective strategies to evaluate the anti-aging effects of small berries and provide guidance for the development of anti-aging supplements from small berries.

Transcriptome Analysis of Insulin Signaling-Associated Transcription Factors in C. elegans Reveal Their Genome-Wide Target Genes Specificity and Complexity

Insulin/IGF-1-like signaling (IIS) plays a crucial, conserved role in development, growth, reproduction, stress tolerance, and longevity. In Caenorhabditis elegans, the enhanced longevity under reduced insulin signaling (rIIS) is primarily regulated by the transcription factors (TFs) DAF-16/FOXO, SKN-1/Nrf-1, and HSF1/HSF-1. The specific and coordinated regulation of gene expression by these TFs under rIIS has not been comprehensively elucidated. Here, using RNA-sequencing analysis, we report a systematic study of the complexity of TF-dependent target gene interactions during rIIS under analogous genetic and experimental conditions. We found that DAF-16 regulates only a fraction of the C. elegans transcriptome but controls a large set of genes under rIIS; SKN-1 and HSF-1 show the opposite trend. Both of the latter TFs function as activators and repressors to a similar extent, while DAF-16 is predominantly an activator. For expression of the genes commonly regulated by TFs under rIIS conditions, DAF-16 is the principal determining factor, dominating over the other two TFs, irrespective of whether they activate or repress these genes. The functional annotations and regulatory networks presented in this study provide novel insights into the complexity of the gene regulatory networks downstream of the IIS pathway that controls diverse phenotypes, including longevity.

Trigonelline Extends the Lifespan of C. Elegans and Delays the Progression of Age-Related Diseases by Activating AMPK, DAF-16, and HSF-1

Trigonelline is the main alkaloid with bioactivity presented in fenugreek, which was used in traditional medicine in Asian countries for centuries. It is reported that trigonelline has anti-inflammatory, anti-oxidant, and anti-pathogenic effects. We are wondering whether trigonelline have anti-aging effect. We found that 50 μM of trigonelline had the best anti-aging activity and could prolong the lifespan of Caenorhabditis elegans (C. elegans) by about 17.9%. Trigonelline can enhance the oxidative, heat, and pathogenic stress resistance of C. elegans. Trigonelline could also delay the development of neurodegenerative diseases, such as AD, PD, and HD, in models of C. elegans. Trigonelline could not prolong the lifespan of long-lived worms with loss-of-function mutations in genes regulating energy and nutrition, such as clk-1, isp-1, eat-2, and rsks-1. Trigonelline requires daf-16, hsf-1, and aak-2 to extend the lifespan of C. elegans. Trigonelline can also up-regulate the expression of daf-16 and hsf-1 targeted downstream genes, such as sod-3, gst-4, hsp-16.1, and hsp-12.6. Our results can be the basis for developing trigonelline-rich products with health benefits, as well as for further research on the pharmacological usage of trigonelline.

Ginsenoside Prolongs the Lifespan of C. elegans via Lipid Metabolism and Activating the Stress Response Signaling Pathway

Panax ginseng is a valuable traditional Chinese medicine in Northeast China. Ginsenoside, the active component of ginseng, has not been investigated much for its effects on aging and its underlying mechanism(s) of action. Here, we investigated the effects of total ginsenoside (TG), a mixture of the primary active ginsenosides from Panax ginseng, on the lifespan of Caenorhabditis elegans (C. elegans). We found that TG extended the lifespan of C. elegans and reduced lipofuscin accumulation. Moreover, TG increased the survival of C. elegans in response to heat and oxidative stress via the reduction of ROS. Next, we used RNA-seq to fully define the antiaging mechanism(s) of TG. The KEGG pathway analysis showed that TG can prolong the lifespan and is involved in the longevity regulating pathway. qPCR showed that TG upregulated the expression of nrh-80, daf-12, daf-16, hsf-1 and their downstream genes. TG also reduced the fat accumulation and promoted lipid metabolism. Moreover, TG failed to extend the lifespan of daf-16 and hsf-1 mutants, highlighting their role in the antiaging effects of TG in C. elegans. The four main constitution of TG were then confirmed by HPLC and included ginsenoside Re, Rg1, Rg2 and Rd. Of the ginsenosides, only ginsenoside Rd prolonged the lifespan of C. elegans to levels comparable to TG. These findings provided mechanistic insight into the antiaging effects of ginsenoside in C. elegans.

Insulin/IGF-1 signaling and heat stress differentially regulate HSF1 activities in germline development

Germline development is sensitive to nutrient availability and environmental perturbation. Heat shock transcription factor 1 (HSF1), a key transcription factor driving the cellular heat shock response (HSR), is also involved in gametogenesis. The precise function of HSF1 (HSF-1 in C. elegans) and its regulation in germline development are poorly understood. Using the auxin-inducible degron system in C. elegans, we uncovered a role of HSF-1 in progenitor cell proliferation and early meiosis and identified a compact but important transcriptional program of HSF-1 in germline development. Interestingly, heat stress only induces the canonical HSR in a subset of germ cells but impairs HSF-1 binding at its developmental targets. Conversely, insulin/insulin growth factor 1 (IGF-1) signaling dictates the requirement for HSF-1 in germline development and functions through repressing FOXO/DAF-16 in the soma to activate HSF-1 in germ cells. We propose that this non-cell-autonomous mechanism couples nutrient-sensing insulin/IGF-1 signaling to HSF-1 activation to support homeostasis in rapid germline growth.

Synergistic effects of brain injury and aging: common mechanisms of proteostatic dysfunction

The aftermath of TBI is associated with an acute stress response and the accumulation of insoluble protein aggregates. Even after the symptoms of TBI are resolved, insidious molecular processes continue to develop, which often ultimately result in the development of age-associated neurodegenerative disorders. The precise molecular cascades that drive unhealthy brain aging are still largely unknown. In this review, we discuss proteostatic dysfunction as a converging mechanism contributing to accelerated brain aging after TBI. We examine evidence from human tissue and in vivo animal models, spanning both the aging and injury contexts. We conclude that TBI has a sustained debilitating effect on the proteostatic machinery, which may contribute to the accelerated pathological and cognitive hallmarks of aging that are observed following injury.

HSF-1 and SIR-2.1 linked insulin-like signaling is involved in goji berry (Lycium spp.) extracts promoting lifespan extension of Caenorhabditis elegans

The anti-cancer, vision-improving, and reproduction-enhancing effects of goji berry have been generally recognized, but its role in anti-aging is rarely studied in depth. Therefore, two widely-circulated goji berries, Lycium ruthenicum Murr. (LRM) and Lycium Barbarum. L (LB), were selected to explore their effects on extending lifespan and enhancing defense against extrinsic stress and to uncover the mechanism of action through genetic study. The results showed that supplementation with high-dose LRM (10 mg mL^-1) and LB (100 mg mL^-1) extracts significantly extended the lifespan of Caenorhabditis elegans (C. elegans) by 25.19% and 51.38%, respectively, accompanied by the improved stress tolerance of C. elegans to paraquat-induced oxidation, UV-B irradiation and heat shock. Furthermore, LRM and LB extracts remarkably enhanced the activities of antioxidant enzymes including SOD and CAT in C. elegans, while notably decreased the lipofuscin level. Further genetic research demonstrated that the expression levels of key genes daf-16, sod-2, sod-3, sir-2.1 and hsp-16.2 in C. elegans were up-regulated by the intervention with LRM and LB, while that of the age-1 level was down-regulated. Moreover, the daf-16 (mu86) I, sir-2.1 (ok434) IV and hsf-1 (sy441) I mutants reversed the longevity effect brought about by LRM or LB, which confirmed that these genes were required in goji berry-mediated lifespan extension. Therefore, we conclude that HSF-1 and SIR-2.1 act collaboratively with the insulin/IGF signaling pathway (IIS) in a daf-16-independent mode. The present study indicated goji berry as a potential functional food to alleviate the symptoms of aging.

Ribosome-associated quality control and CAT tailing

Translation is the set of mechanisms by which ribosomes decode genetic messages as they synthesize polypeptides of a defined amino acid sequence. While the ribosome has been honed by evolution for high-fidelity translation, errors are inevitable. Aberrant mRNAs, mRNA structure, defective ribosomes, interactions between nascent proteins and the ribosomal exit tunnel, and insufficient cellular resources, including low tRNA levels, can lead to functionally irreversible stalls. Life thus depends on quality control mechanisms that detect, disassemble and recycle stalled translation intermediates. Ribosome-associated Quality Control (RQC) recognizes aberrant ribosome states and targets their potentially toxic polypeptides for degradation. Here we review recent advances in our understanding of RQC in bacteria, fungi, and metazoans. We focus in particular on an unusual modification made to the nascent chain known as a "CAT tail", or Carboxy-terminal Alanine and Threonine tail, and the mechanisms by which ancient RQC proteins catalyze CAT-tail synthesis.

Temporal requirements of SKN-1/NRF as a regulator of lifespan and proteostasis in Caenorhabditis elegans

Lowering the activity of the Insulin/IGF-1 Signaling (IIS) cascade results in elevated stress resistance, enhanced protein homeostasis (proteostasis) and extended lifespan of worms, flies and mice. In the nematode Caenorhabditis elegans (C. elegans), the longevity phenotype that stems from IIS reduction is entirely dependent upon the activities of a subset of transcription factors including the Forkhead factor DAF-16/FOXO (DAF-16), Heat Shock Factor-1 (HSF-1), SKiNhead/Nrf (SKN-1) and ParaQuat Methylviologen responsive (PQM-1). While DAF-16 determines lifespan exclusively during early adulthood and governs proteostasis in early adulthood and midlife, HSF-1 executes these functions foremost during development. Despite the central roles of SKN-1 as a regulator of lifespan and proteostasis, the temporal requirements of this transcription factor were unknown. Here we employed conditional knockdown techniques and discovered that in C. elegans, SKN-1 is primarily important for longevity and proteostasis during late larval development through early adulthood. Our findings indicate that events that occur during late larval developmental through early adulthood affect lifespan and proteostasis and suggest that subsequent to HSF-1, SKN-1 sets the conditions, partially overlapping temporally with DAF-16, that enable IIS reduction to promote longevity and proteostasis. Our findings raise the intriguing possibility that HSF-1, SKN-1 and DAF-16 function in a coordinated and sequential manner to promote healthy aging.

Evaluation of changes in C. elegans immune response during bacterial infection: A single nematode approach

Routinely, studies were performed using age-synchronized group of C. elegans as host which suggested a collective response by the host system. Here, we report the modulation of immune response in a single nematode against Staphylococcus aureus and Proteus mirabilis. Initially, the survival of wild-type N2 was tested and was found that S. aureus killed single nematode at 42 h while P. mirabilis failed to provoke infection but colonized the nematode's intestine. With this milieu, the pathogenicity of the bacteria was assessed by Fourier Transform Infra-Red (FTIR) spectroscopy and Cyclic Voltammetry (CV) and was found that S. aureus in the presence of host elicited its virulence while P. mirabilis and Escherichia coli OP50 did not show any alteration. Vertical transmission of infection was also deduced by colony forming unit assay using Cyanine dyes. The MALDI-TOF/TOF analysis was also performed to identify the proteome changes in the single nematode that showcased different proteins related to various immune pathways. This study suggested the importance of understanding the infection pathology and traits of individual nematode which could help our understanding on otherwise the disordered processes during host and microbe interactions.

Caffeic and Dihydrocaffeic Acids Promote Longevity and Increase Stress Resistance in Caenorhabditis elegans by Modulating Expression of Stress-Related Genes

Caffeic and dihydrocaffeic acid are relevant microbial catabolites, being described as products from the degradation of different phenolic compounds i.e., hydroxycinnamoyl derivatives, anthocyanins or flavonols. Furthermore, caffeic acid is found both in free and esterified forms in many fruits and in high concentrations in coffee. These phenolic acids may be responsible for a part of the bioactivity associated with the intake of phenolic compounds. With the aim of progressing in the knowledge of the health effects and mechanisms of action of dietary phenolics, the model nematode Caenorhabditis elegans has been used to evaluate the influence of caffeic and dihydrocaffeic acids on lifespan and the oxidative stress resistance. The involvement of different genes and transcription factors related to longevity and stress resistance in the response to these phenolic acids has also been explored. Caffeic acid (CA, 200 μM) and dihydrocaffeic acid (DHCA, 300 μM) induced an increase in the survival rate of C. elegans under thermal stress. Both compounds also increased the mean and maximum lifespan of the nematode, compared to untreated worms. In general, treatment with these acids led to a reduction in intracellular ROS concentrations, although not always significant. Results of gene expression studies conducted by RT-qPCR showed that the favorable effects of CA and DHCA on oxidative stress and longevity involve the activation of several genes related to insulin/IGF-1 pathway, such as daf-16, daf-18, hsf-1 and sod-3, as well as a sirtuin gene (sir-2.1).

HSF-1 displays nuclear stress body formation in multiple tissues in Caenorhabditis elegans upon stress and following the transition to adulthood

The transcription factor heat shock factor-1 (HSF-1) regulates the heat shock response (HSR), a cytoprotective response induced by proteotoxic stresses. Data from model organisms has shown that HSF-1 also has non-stress biological roles, including roles in the regulation of development and longevity. To better study HSF-1 function, we created a C. elegans strain containing HSF-1 tagged with GFP at its endogenous locus utilizing CRISPR/Cas9-guided transgenesis. We show that the HSF-1::GFP CRISPR worm strain behaves similarly to wildtype worms in response to heat and other stresses, and in other physiological processes. HSF-1 was expressed in all tissues assayed. Immediately following the initiation of reproduction, HSF-1 formed nuclear stress bodies, a hallmark of activation, throughout the germline. Upon the transition to adulthood, of HSF-1 nuclear stress bodies appeared in most somatic cells. Genetic loss of the germline suppressed nuclear stress body formation with age, suggesting that the germline influences HSF-1 activity. Interestingly, we found that various neurons did not form nuclear stress bodies after transitioning to adulthood. Therefore, the formation of HSF-1 nuclear stress bodies upon the transition to adulthood does not occur in a synchronous manner in all cell types. In sum, these studies enhance our knowledge of the expression and activity of the aging and proteostasis factor HSF-1 in a tissue-specific manner with age.

Essential Oil of Acorus tatarinowii Schott Ameliorates Aβ-Induced Toxicity in Caenorhabditis elegans through an Autophagy Pathway

Background

Acorus tatarinowii Schott [Shi Chang Pu in Chinese (SCP)] is a traditional Chinese medicine frequently used in the clinical treatment of dementia, amnesia, epilepsy, and other mental disorders. Previous studies have shown the potential efficacy of SCP against Alzheimer's disease (AD). Nevertheless, the active constituents and the modes of action of SCP in AD treatment have not been fully elucidated.

Purpose

The aim of this study was to investigate the protective effects of SCP on abnormal proteins and clarify its molecular mechanisms in the treatment of AD by using a Caenorhabditis elegans (C. elegans) model.

Methods

This study experimentally assessed the effect of SCP-Oil in CL4176 strains expressing human Aβ in muscle cells and CL2355 strains expressing human Aβ in pan-neurons. Western blotting, qRT-PCR, and fluorescence detection were performed to determine the oxidative stress and signaling pathways affected by SCP-Oil in nematodes.

Results

SCP-Oil could significantly reduce the deposition of misfolded Aβ and polyQ proteins and improved serotonin sensitivity and olfactory learning skill in worms. The analysis of pharmacological action mechanism of SCP-Oil showed that its maintaining protein homeostasis is dependent on the autophagy pathway regulated partly by hsf-1 and sir-2.1 genes.

Conclusion

Our results provide new insights to develop treatment strategy for AD by targeting autophagy, and SCP-Oil could be an alternative drug for anti-AD.