Differences in protein expression associated with ivermectin resistance in Caenorhabditis elegans / Diferenças na expressão de proteínas associadas à resistência à ivermectina em Caenorhabditis elegans

Abstract The indiscriminate administration of synthetic anthelmintics such as ivermectin contributes to the selection of subpopulations capable of resisting the drugs' effects. To understand the mechanisms of ivermectin resistance in Caenorhabditis elegans, this study attempted to identify molecular targets. C. elegans lineages that were sensitive and resistant to ivermectin were used. Collected nematodes were added to an extraction buffer and macerated in liquid nitrogen for protein extraction. The extracted proteins were separated according to molecular weight by SDS-PAGE to verify their integrity. Subsequently, proteins from both lineages were separated using two-dimensional electrophoresis. The gels were analyzed and the relevant spots were excised and identified by mass spectrometry (NanoESI-Q-TOF and MASCOT®) and subsequently assessed by GO enrichment and STRING® analyses. The increased expression of proteins associated with high metabolic activity, such as ATP-2 and ENOL-1, which are responsible for ATP synthesis, was observed. Furthermore, proteins with involvement in mediating muscular function (MLC-1, ACT-1, and PDI-2), signaling (FAR-1 and FAR-2), and embryo development (VHA-2) were identified. Protein interaction analysis indicated that the majority of the identified proteins in the resistant lineages participated in the same reaction triggered by ivermectin.

Resumo A administração indiscriminada de anti-helmínticos sintéticos, como a ivermectina, contribui para a seleção de subpopulações capazes de resistir ao efeito das drogas. Para entender os mecanismos de resistência à ivermectina em Caenorhabditis elegans, este estudo visou identificar alvos moleculares. Portanto, linhagens de C. elegans sensíveis e resistentes à ivermectina foram utilizadas. Os nematóides coletados foram adicionados ao tampão de extração e macerados em nitrogênio líquido para obtenção das proteínas. As proteínas extraídas foram separadas por peso molecular em SDS-PAGE para verificar sua integridade. Posteriormente, as proteínas de ambas as linhagens foram separadas por eletroforese bidimensional. Os géis foram analisados, os spots relevantes foram excisados e identificados por espectrometria de massa (NanoESI-Q-TOF e MASCOT®), em seguida, analisados ​​em seus termos de GO e STRING®. A expressão aumentada de proteínas associadas à alta atividade metabólica, como as proteínas ATP-2 e ENOL-1, responsáveis ​​pela síntese de ATP, foi observada. Além disso, foram identificadas as proteínas responsáveis ​​pelo controle da função muscular (MLC-1, ACT-1 e PDI-2), sinalização (FAR-1 e FAR-2) e desenvolvimento embrionário (VHA-2). A análise das interações proteicas indicou que a maioria das proteínas identificadas na cepa resistente participa da mesma reação desencadeada pela ivermectina.

Mechanisms involved in anti-aging effects of guarana (Paullinia cupana) in Caenorhabditis elegans

Guarana (Paullinia cupana) is habitually ingested by people in the Amazon region and is a key ingredient in various energy drinks consumed worldwide. Extension in longevity and low prevalence of chronic age-related diseases have been associated to habitual intake of guarana. Anti-aging potential of guarana was also demonstrated in Caenorhabditis elegans; however, the mechanisms involved in its effects are not clear. Herein, we investigated the putative pathways that regulate the effects of guarana ethanolic extract (GEE) on lifespan using C. elegans. The major known longevity pathways were analyzed through mutant worms and RT-qPCR assay (DAF-2, DAF-16, SKN-1, SIR-2.1, HSF-1). The possible involvement of purinergic signaling was also investigated. This study demonstrated that GEE acts through antioxidant activity, DAF-16, HSF-1, and SKN-1 pathways, and human adenosine receptor ortholog (ADOR-1) to extend lifespan. GEE also downregulated skn-1, daf-16, sir-2.1 and hsp-16.2 in 9-day-old C. elegans, which might reflect less need to activate these protective genes due to direct antioxidant effects. Our results contribute to the comprehension of guarana effects in vivo, which might be helpful to prevent or treat aging-associated disorders, and also suggest purinergic signaling as a plausible therapeutic target for longevity studies.

Selenocysteine modulates resistance to environmental stress and confers anti-aging effects in C. elegans

OBJECTIVE: The free radical theory of aging suggests that cellular oxidative damage caused by free radicals is a leading cause of aging. In the present study, we examined the effects of a well-known anti-oxidant amino acid derivative, selenocysteine, in response to environmental stress and aging using Caenorhabditis elegans as a model system. METHOD: The response to oxidative stress induced by H2O2 or ultraviolet irradiation was compared between the untreated control and selenocysteine-treated groups. The effect of selenocysteine on lifespan and fertility was then determined. To examine the effect of selenocysteine on muscle aging, we monitored the change in motility with aging in both the untreated control and selenocysteine-treated groups. RESULTS: Dietary supplementation with selenocysteine significantly increased resistance to oxidative stress. Survival after ultraviolet irradiation was also increased by supplementation with selenocysteine. Treatment with selenocysteine confers a longevity phenotype without an accompanying reduction in fertility, which is frequently observed in lifespan-extending interventions as a trade-off in C. elegans. In addition, the age-related decline in motility was significantly delayed by supplementation of selenocysteine. CONCLUSION: These findings suggest that dietary supplementation of selenocysteine can modulate response to stressors and lead to lifespan extension, thus supporting the free radical theory of aging.

Rosmarinus officinalis L. increases Caenorhabditis elegans stress resistance and longevity in a DAF-16, HSF-1 and SKN-1-dependent manner

Improving overall health and quality of life, preventing diseases and increasing life expectancy are key concerns in the field of public health. The search for antioxidants that can inhibit oxidative damage in cells has received a lot of attention. Rosmarinus officinalis L. represents an exceptionally rich source of bioactive compounds with pharmacological properties. In the present study, we explored the effects of the ethanolic extract of R. officinalis (eeRo) on stress resistance and longevity using the non-parasitic nematode Caenorhabditis elegans as a model. We report for the first time that eeRo increased resistance against oxidative and thermal stress and extended C. elegans longevity in an insulin/IGF signaling pathway-dependent manner. These data emphasize the eeRo beneficial effects on C. elegans under stress.

Antiaging, antistress and ROS scavenging activity of crude extract of Ocimum sanctum (L.) in Caenorhabditis elegans (Maupas, 1900).

Since aging is the most important risk factor for variety of diseases, the discovery of a wide range of chemical modulators of aging in model organisms encourages new strategies for targeting age associated diseases. Simple genetic manipulation leads to long-lived and healthy animals, so any compound which could have similar effect would prove a boon to mankind. In the present study, effect of different pharmacological doses (1.0, 0.1, 0.01 and 0.001 mg/mL) of O. sanctum crude extract were used to determine their impact on life span, thermotolerance and ROS scavenging activities in C. elegans. The results revealed that 1 mg/mL of O. sanctum extract significantly extended the life span of C. elegans. The extract also proved to be a strong free radical scavenger and increased resistance against thermal stress. It is also suggested that the protective and life span extending action of the crude extract is not only due to its antioxidant capacity but may also be mediated by modulation of some signaling pathways. Thus, in addition to all the known medicinal property of Ocimum, it is capable of increasing stress tolerance and life span in C. elegans.

Effect of the tocotrienol-rich fraction on the lifespan and oxidative biomarkers in Caenorhabditis elegans under oxidative stress

OBJECTIVE: This study was performed to determine the effect of the tocotrienol-rich fraction on the lifespan and oxidative status of C. elegans under oxidative stress. METHOD: Lifespan was determined by counting the number of surviving nematodes daily under a dissecting microscope after treatment with hydrogen peroxide and the tocotrienol-rich fraction. The evaluated oxidative markers included lipofuscin, which was measured using a fluorescent microscope, and protein carbonyl and 8-hydroxy-2′-deoxyguanosine, which were measured using commercially available kits. RESULTS: Hydrogen peroxide-induced oxidative stress significantly decreased the mean lifespan of C. elegans, which was restored to that of the control by the tocotrienol-rich fraction when administered before or both before and after the hydrogen peroxide. The accumulation of the age marker lipofuscin, which increased with hydrogen peroxide exposure, was decreased with upon treatment with the tocotrienol-rich fraction (p<0.05). The level of 8-hydroxy-2′-deoxyguanosine significantly increased in the hydrogen peroxide-induced group relative to the control. Treatment with the tocotrienol-rich fraction before or after hydrogen peroxide induction also increased the level of 8-hydroxy-2′-deoxyguanosine relative to the control. However, neither hydrogen peroxide nor the tocotrienol-rich fraction treatment affected the protein carbonyl content of the nematodes. CONCLUSION: The tocotrienol-rich fraction restored the lifespan of oxidative stress-induced C. elegans and reduced the accumulation of lipofuscin but did not affect protein damage. In addition, DNA oxidation was increased. .

Electrolyzed-reduced water increases resistance to oxidative stress, fertility, and lifespan via insulin/IGF-1-like signal in C. elegans

Electrolyzed-reduced water (ERW) scavenges reactive oxygen species and is a powerful anti-oxidant. A positive correlation between oxidative stress and aging has been proved in many model organisms. In Caenorhabditis elegans, many long-lived mutants showed reduced fertility as a trade off against longevity phenotype. We aimed to study the effect of ERW on oxidative stress, fertility and lifespan of C. elegans. We also investigated the genetic pathway involved in the effect of ERW on resistance to oxidative stress and lifespan. We compared lifespan and fertility of worms in media prepared with distilled water and ERW. ERW significantly extended lifespan and increased the number of progeny produced. Then the effect of ERW on resistance to oxidative stress and lifespan of long-lived mutants was determined. ERW increased resistance to oxidative stress and lifespan of eat-2, a genetic model of dietary restriction, but had no effect on those of age-1, which is involved in insulin/insulin-like growth factor (IGF)-1-like signal. In addition, knockdown of daf-16, the downstream mediator of insulin/IGF-1-like signal, completely prevented the effect of ERW on lifespan. These findings suggest that ERW can extend lifespan without accompanying reduced fertility and modulate resistance to oxidative stress and lifespan via insulin/IGF-1-like signal in C. elegans.

-Tocopherol ameliorates cypermethrin-induced toxicity and oxidative stress in the nematode Caenorhabdtis elegans.

Oxidative stress and other effects induced by cypermethrin (CYP, 15 mM) and their amelioration by -tocopherol (400 M) was studied in the nematode Caenorhabditis elegans. The worms exposed for 4 h to CYP showed increased levels of reactive oxygen species (46%), H2O2 (37%) and protein carbonyls (29%), accompanied by decreased lifespan and brood size. However, exposure to both CYP and a-tocopherol resulted in diminution of above alterations with the worms exhibiting relatively lower levels of ROS (30%), H2O2 (15%), protein carbonyls (14%), altered antioxidant enzyme activities and normal lifespan and brood size. The results suggest that CYP induces oxidative stress in C. elegans and the strategy of intervention with -tocopherol could be exploited to offset this induced oxidative stress.

Development and evaluation of an in vivo assay in Caenorhabditis elegans for screening of compounds for their effect on cytochrome P450 expression.

Most drugs and xenobiotics induce the expression of cytochrome P450 (CYP) enzymes, which reduce the bioavailability of the inducer and/or co-administered drugs. Therefore, evaluation of new drug candidates for their effect on CYP expression is an essential step in drug development. The available methods for this purpose are expensive and not amenable to high-throughput screening. We developed a fluorescence-based in vivo assay using transgenic Caenorhabditis elegans worms that express the green fluorescent protein (GFP) under the control of various CYP promoters. Using this assay, we found striking similarities between the worm CYPs and their human orthologs in their response to treatment with various drugs. For example,the antibiotic rifampicin, one of the strongest inducers of the human gene CYP3A4, was the strongest inducer of the worm ortholog CYP13A7. Since worms can be easily grown in liquid medium in microtitre plates, the assay described in this paper is suitable for the screening of a large number of potential lead compounds in the drug discovery process.

Toxigenicity testing of clinical isolates of non-typhoidal salmonellae in Vero cell culture & Caenorhabditis elegans model.

The non-typhoidal salmonellae (NTS) are recognized agents of gastroenteritis worldwide. Some of the NTS do not produces cytotoxic changes in tissue culture and not much is known about the endotoxicity of the clinical isolates of NTS (mostly Salmonella enterica serotype Typhimurium and Salmonella enterica serotype Enteritidis). We examined the exotoxic (cytotoxin) and endotoxic activity of clinical isolates of NTS in two assay models namely Vero cell culture and the nematode, Caenorhabditis elegans. Bacteria-free culture supernatants of 40 isolates NTS were tested in 96 well microtitre plate containing confluent monolayers of Vero cells. For the effects on C. elegans, the worms were exposed to bacteria free culture supernatants in 24 well microtitre plate for 24 h and then transferred to OP50 Escherichia coli lawn culture. The endotoxic activity of the live bacterium was studied by feeding the worms in the lawn culture of NTS separately. No cytopathic effect was observed with NTS tested in Vero cell culture assay. Likewise, the worms exposed to the bacteria-free culture supernatants were found active up to 7 days. In the co-culture killing assay, worms were found dead with characteristic stiff and straight appearance by 16(th) day. The worms were alive up to 21 days in OP50 E. coli. Bacteria-free culture supernatants did not have any deleterious effect on worms or in Vero cell culture, suggesting that there is no soluble toxic factor (diffusible toxin) in the culture supernatants. However, live NTS were found to be lethal to the worms; indicating that direct interaction between viable NTS and C. elegans is necessary for killing.