Ellagic Acid Increases Stress Resistance via Insulin/IGF-1 Signaling Pathway in Caenorhabditis elegans.

Ellagic acid is a natural polyphenol found in various fruits and vegetables. Numerous studies have shown that ellagic acid has beneficial effects on human health. In this study, we investigated the stress resistant action of ellagic acid in Caenorhabditis elegans (C. elegans). Notably, 50 µM ellagic acid prolonged the lifespan of C. elegans by 36.25%, 36.22%, 155.1%, and 79.07% under ultraviolet radiation stress, heat stress, oxidative stress, and Pseudomonas aeruginosa infection stress, respectively. Furthermore, the mechanism by which ellagic acid reduces the damage caused by ultraviolet radiation in C. elegans was explored. Ellagic acid could significantly induce the nucleus translocation of DAF-16 and, thereby, activate a series of target genes to resist ultraviolet radiation stress. Moreover, ellagic acid also significantly increased the expression of SOD-3 by 3.61 times and the activity of superoxide dismutase by 3.70 times to clean out harmful reactive oxygen species in C. elegans exposed to ultraviolet radiation stress. In both daf-16 mutant and daf-2; daf-16 double-mutant worms exposed to ultraviolet radiation, ellagic acid could no longer prolong their lifespan. These results indicate that ellagic acid plays an important role in resisting ultraviolet radiation stress in C. elegans, probably in an insulin/IGF-1 signaling pathway-dependent way.

Ingredients in Zijuan Pu'er Tea Extract Alleviate ß-Amyloid Peptide Toxicity in a Caenorhabditis elegans Model of Alzheimer's Disease Likely through DAF-16.

Amyloid-ß, one of the hallmarks of Alzheimer's disease (AD), is toxic to neurons and can also cause brain cell death. Oxidative stress is known to play an important role in AD, and there is strong evidence that oxidative stress is associated with amyloid-ß. In the present study we report the protective effect of Zijuan Pu'er tea water extract (ZTWE) and the mixture of main ingredients (+)-catechins, caffeine and procyanidin (MCCP) in ZTWE on ß-amyloid-induced toxicity in transgenic Caenorhabditis elegans (C. elegans) CL4176 expressing the human Aß1⁻42 gene. ZTWE, (+)-catechins, caffeine, procyanidin and MCCP delayed the ß-amyloid-induced paralysis to different degrees. The MCCP treatment did not affect the transcript abundance of amyloid-ß transgene (amy-1); however, Thioflavin T staining showed a significant decrease in Aß accumulation compared to untreated worms. Further research using transgenic worms found that MCCP promoted the translocation of DAF-16 from cytoplasm to nucleus and increased the expression of superoxide dismutase 3 (SOD-3). In addition, MCCP decreased the reactive oxygen species (ROS) content and increased the SOD activity in CL4176 worms. In conclusion, the results suggested that MCCP had a significant protective effect on ß-amyloid-induced toxicity in C. elegans by reducing ß-amyloid aggregation and inducing DAF-16 nuclear translocation that could activate the downstream signal pathway and enhance resistance to oxidative stress.

Ethanol Alleviates Amyloid-ß-Induced Toxicity in an Alzheimer's Disease Model of Caenorhabiditis elegans.

Amyloid-ß, a hallmark of Alzheimer's disease, forms toxic intracellular oligomers and extracellular senile plaques resulting in neuronal toxicity. Ethanol is widely consumed worldwide. Moderate ethanol consumption has numerous benefits in humans. We found that ethanol could significantly extend the lifespan of Caenorhabiditis elegans in a previous study. Based on that study, we tested the effect of ethanol on Alzheimer's disease transgenic Caenorhabiditis elegans strain CL4176, which expresses amyloid-ß1-42 peptide in body wall muscle cells. Ethanol delayed paralysis and reduced amyloid-ß oligomers in Caenorhabiditis elegans worms of the CL4176 strain. Moreover, ethanol could induce the nuclear translocation of DAF-16 in the nematodes. However, in worms that were fed daf-16 RNAi bacteria, ethanol no longer delayed the paralysis. The qPCR assays showed that ethanol increases the expression of daf-16, hsf-1 and their common target genes- small heat shock protein genes. In addition, we also found that ethanol could increase lysosome mass in the CL4176 worms. In summary, our study indicated that ethanol attenuated amyloid-ß toxicity in the Alzheimer's disease model of Caenorhabiditis elegans via increasing the level of lysosomes to promote amyloid-ß degradation and upregulating the levels of small heat shock protein genes to reduce amyloid-ß aggregation.

Applying internal coordinate mechanics to model the interactions between 8R-lipoxygenase and its substrate.

BACKGROUND: Lipoxygenases (LOX) play pivotal roles in the biosynthesis of leukotrienes and other biologically active potent signalling compounds. Developing inhibitors for LOX is of high interest to researchers. Modelling the interactions between LOX and its substrate arachidonic acid is critical for developing LOX specific inhibitors. Currently, there are no LOX-substrate structures. Recently, the structure of a coral LOX, 8R-LOX, which is 41% sequence identical to the human 5-LOX was solved to 1.85Å resolution. This structure provides a foundation for modelling enzyme-substrate interactions. METHODS: In this research, we applied a computational method, Internal Coordinate Mechanics (ICM), to model the interactions between 8R-LOX and its substrate arachidonic acid. Docking arachidonic acid to 8R-LOX was performed. The most favoured docked ligand conformations were retained. We compared the results of our simulation with a proposed model and concluded that the binding pocket identified in this study agrees with the proposed model partially. RESULTS: The results showed that the conformation of arachidonic acid docked into the ICM-identified docking site has less energy than that docked into the manually defined docking site for pseudo wild type 8R-LOX. The mutation at I805 resulted in no docking pocket found near Fe atom. The energy of the arachidonic acid conformation docked into the manually defined docking site is higher in mutant 8R-LOX than in wild type 8R-LOX. The arachidonic acid conformations are not productive conformations. CONCLUSIONS: We concluded that, for the wild type 8R-LOX, the conformation of arachidonic acid docked into the ICM-identified docking site is more stable than that docked into the manually defined docking site. Mutation affects the structure of the putative active site pocket of 8R-LOX, and leads no docking pockets around the catalytic Fe atom. The docking simulation in a mutant 8R-LOX demonstrated that the structural change due to the mutation impacts the enzyme activity. Further research and analysis is required to obtain the 8R-LOX-substrate model.

Didymin improves UV irradiation resistance in C. elegans.

Didymin, a type of flavono-o-glycoside compound naturally present in citrus fruits, has been reported to be an effective anticancer agent. However, its effects on stress resistance are unclear. In this study, we treated Caenorhabditis elegans with didymin at several concentrations. We found that didymin reduced the effects of UV stressor on nematodes by decreasing reactive oxygen species levels and increasing superoxide dismutase (SOD) activity. Furthermore, we found that specific didymin-treated mutant nematodes daf-16(mu86) & daf-2(e1370), daf-16(mu86), akt-1(ok525), akt-2(ok393), and age-1(hx546) were susceptible to UV irradiation, whereas daf-2(e1371) was resistant to UV irradiation. In addition, we found that didymin not only promoted DAF-16 to transfer from cytoplasm to nucleus, but also increased both protein and mRNA expression levels of SOD-3 and HSP-16.2 after UV irradiation. Our results show that didymin affects UV irradiation resistance and it may act on daf-2 to regulate downstream genes through the insulin/IGF-1-like signaling pathway.

Using near-infrared enhanced thermozyme and scFv dual-conjugated Au nanorods for detection and targeted photothermal treatment of Alzheimer's disease.

Investigation of targeting inhibitors of Aß aggregation, heme-Aß peroxidase-like activity and efficient detectors of Aß aggregation, are of therapeutic value and diagnostics significance for the treatment of Alzheimer's disease (AD). Due to the complex pathogenesis of AD, theranostics treatment with multiple functions are necessary. Herein we constructed the NIR absorption property of gold nanorods (GNRs) loaded with single chain variable fragment (scFv) 12B4 and thermophilic acylpeptide hydrolase (APH) ST0779 as a smart theranostic complex (GNRs-APH-scFv, GAS), which possesses both rapid detection of Aß aggregates and NIR photothermal treatment that effectively disassembles Aß aggregates and inhibits Aß-mediated toxicity. Methods: We screened targeting anti-Aß scFv 12B4 and thermophilic acylpeptide hydrolase as amyloid-degrading enzyme, synthesized GAS gold nanorods complex. The GAS was evalued by Aß inhibition and disaggregation assays, Aß detection assays, Aß mediated toxicity assays in vitro. In vivo, delaying Aß-induced paralysis in AD model of Caenorhabditis elegans was also tested by GAS. Results: In vitro, GAS has a synergistic effect to inhibit and disassociate Aß aggregates, in addition to decrease heme-Aß peroxidase-like activity. In cultured cells, treatment with GAS reduces Aß-induced cytotoxicity, while also delaying Aß-mediated paralysis in CL4176 C.elegans model of AD. Furthermore, the photothermal effect of the GAS upon NIR laser irradiation not only helps disassociate the Aß aggregates but also boosts APH activity to clear Aß. The GAS, as a targeting detector and inhibitor, allows real-time detection of Aß aggregates. Conclusion: These results firstly highlight the combination of scFv, APH and nanoparticles to be theranostic AD drugs. Taken together, our strategy provides a new thought into the design of smart compounds for use as efficiently therapeutic and preventive agents against AD. Moreover, our design provides broad prospects of biomedical strategy for further theranostics application in those diseases caused by abnormal protein.

Knockdown of LMW-PTP enhances stress resistance in Caenorhabditis elegans.

Low molecular weight protein tyrosine phosphatase (LMW-PTP) is highly conserved across almost all living organisms and is involved in the modulation of a number of cellular proteins related to important signaling pathways. In this study, we isolated lmwptp (Y94H6A.7) of Caenorhabditis elegans, the homolog of human ACP1, and set up an effective feeding-based RNA interference (RNAi) knockdown against this gene. We found that knockdown of lmwptp decreased damage associated with heat shock, oxidative stress and UV irradiation in wild-type worms, however, its deficiency didn't further reduce the stress resistance of daf-16 or hsf-1 mutants and didn't further increase the stress sensitivity associated with age-1, akt-1 or akt-2 mutants, but it enhanced the stress resistance of daf-2 mutants. Further studies demonstrated that this stress tolerance could be attributed to increased daf-16 nuclear accumulation and enhanced expression of both superoxide dismutase-3 protein (SOD-3) and heat shock protein-16.2 (HSP-16.2) in response to stress. Additionally, quantitative real-time PCR results showed that the expression of hsf-1 and its target genes were up-regulated in lmwptp-knockdown worms under stress conditions. Together these results indicated that lmwptp is related to stress resistance of worms, and it is likely associated with the insulin/IGF-1-like signaling (IIS) pathway.

Arbutin increases Caenorhabditis elegans longevity and stress resistance.

Arbutin (p-hydroxyphenyl-ß-D-glucopyranoside), a well-known tyrosinase inhibitor, has been widely used as a cosmetic whitening agent. Although its natural role is to scavenge free radicals within cells, it has also exhibited useful activities for the treatment of diuresis, bacterial infections and cancer, as well as anti-inflammatory and anti-tussive activities. Because function of free radical scavenging is also related to antioxidant and the effects of arbutin on longevity and stress resistance in animals have not yet been confirmed, here the effects of arbutin on Caenorhabditis elegans were investigated. The results demonstrated that optimal concentrations of arbutin could extend lifespan and enhance resistance to oxidative stress. The underlying molecular mechanism for these effects involves decreased levels of reactive oxygen species (ROS), improvement of daf-16 nuclear localization, and up-regulated expression of daf-16 and its downstream targets, including sod-3 and hsp16.2. In this work the roles of arbutin in lifespan and health are studied and the results support that arbutin is an antioxidant for maintaining overall health.