caenorhabditis-elegans-as-model-system-for-discovering-bioactive

<em>Caenorhabditis elegans</em> as a Model System for Discovering Bioactive Compounds Against Polyglutamine-Mediated Neurotoxicity

Age-related misfolding and aggregation of pathogenic proteins are responsible for several neurodegenerative diseases. For example, Huntington&#39;s ...

South China University of Technology

Ultrafiltration, ion-exchange chromatography, and gel filtration chromatography were used to purify anti-oxidant peptides from hydrolysates of soybean protein isolates. The <1-kD peptides were found to exhibit much higher anti-oxidant activity as compared to larger ones. Also, the alkaline peptide fractions were shown to have stronger anti-oxidant capacity than acidic and neutral peptides. Interestingly, an anti-oxidant tripeptide, Ser-Phe-Val (352.4 Da), was identified by reversed-phase high-performance liquid chromatography (RP-HPLC) connected online to electrospray ionization mass spectrometry. The tripeptide was further prepared by fluorenylmethoxycarbonyl (Fmoc) solid-phase synthesis and was found to have a dose-dependent protective effect against hydrogen peroxide (H2O2)-induced injuries in rat adrenal pheochromocytoma (PC12) cells.

Purification and identification of anti-oxidant soybean peptides by consecutive chromatography and electrospray ionization-mass spectrometry.

 colonies have been used as food and medicine for centuries, and their main supporting matrix is polysaccharides, which help  cells resist various environmental stresses including oxidative stress. Here we isolated a polysaccharide, nostoglycan, from cultured  colonies and determined its physicochemical properties, which revealed a characteristic infrared absorption spectrum typical of polysaccharides and an amorphous morphology with rough surfaces. We also show that nostoglycan has strong moisture absorption and retention capacities and a high relative viscosity. Using  models, we then demonstrate that nostoglycan is capable of improving overall survival rate of the animals under increased oxidative stress caused by paraquat. Nostoglycan also reduces reactive oxygen species level, inhibits protein carbonyl formation and lipid peroxidation, and increases activities of superoxide dismutase and catalase in paraquat-exposed nematodes. As oxidative stress may drive tumor progression, we further demonstrate that nostoglycan can suppress the proliferation of several types of tumor cells and induce apoptosis of human lung adenocarcinoma A549 cells via caspase-3 activation. Together, our results yield important information on the physicochemical characteristics and demonstrate the antioxidant and anti-proliferative functions of nostoglycan, and thus provide an insight into its potential in food and health industries.

Physicochemical Characterization and Functional Analysis of the Polysaccharide from the Edible Microalga Nostoc sphaeroides.

Liver cells are easily damaged by oxidative stress during progression both in liver development and throughout adult life, resulting in tissue pathology that ranges from simple hepatitis to nonalcoholic fatty liver disease. In this study, we determined the attenuation of oxidative stress in liver cells with pretreatment of rosmarinic acid (RA), which is an antioxidant agent from . The human liver cell line L02 was damaged by hydrogen peroxide (HO). In the RA treatment group, the viability of L02 cells increased and the intracellular reactive oxygen species levels decreased compared with the HO-induced damage group. Analysis of flow cytometry revealed that the percentage of G2/M cell cycle arrest and cell apoptosis decreased in the RA treatment group. This alteration was associated with activation of a G2/M DNA damage and oxidative stress apoptotic signal. Furthermore, we determined the redox-sensitive protein expression of mitogen-activated protein kinases (MAPKs), quinone acceptor oxidoreductase 1 (NQO1), and nuclear factor E2-related factor 2 (Nrf2), and the expression of both MAPKs and Nrf2 was activated in the RA group. Results showed that the relevant protein expression of MAPKs and Nrf2 was activated in the RA group. Thus, RA protected L02 cells from oxidative damage through suppressing cell cycle arrest and cell apoptosis with the activation of MAPK and Nrf2 signaling pathways.

Rosmarinic Acid Ameliorates HO-Induced Oxidative Stress in L02 Cells Through MAPK and Nrf2 Pathways.

The hard clam , which has been traditionally used as medicine and seafood, was used in this study to isolate antioxidant peptides. First, a peptide-rich extract was tested for its protective effect against paraquat-induced oxidative stress using the nematode model . Then, three novel antioxidant peptides; MmP4 (LSDRLEETGGASS), MmP11 (KEGCREPETEKGHR) and MmP19 (IVTNWDDMEK), were identified and were found to increase the resistance of nematodes against paraquat. Circular dichroism spectroscopy revealed that MmP4 was predominantly in beta-sheet conformation, while MmP11 and MmP19 were primarily in random coil conformation. Using transgenic nematode models, the peptides were shown to promote nuclear translocation of the DAF-16/FOXO transcription factor, a pivotal regulator of stress response and lifespan, and induce the expression of superoxide dismutase 3 (SOD-3), an antioxidant enzyme. Analysis of DAF-16 target genes by real-time PCR reveals that  was up-regulated by MmP4, MmP11 and MmP19 while  and  were also up-regulated by MmP4. Further examination of  using RNA interference suggests that the peptide-increased resistance of  to oxidative stress was DAF-16 dependent. Taken together, these data demonstrate the antioxidant activity of  peptides, which are associated with activation of the stress response factor DAF-16 and regulation of the antioxidant enzyme genes.

Novel Bioactive Peptides from  Protect  against Free Radical-Induced Oxidative Stress through the Stress Response Factor DAF-16/FOXO.

Considerable evidence supports the view that high-fructose intake is associated with increased and early incidence of obesity and dyslipidemia. However, knowledge on physiopathological alterations introduced by fructose overconsumption is lacking. Therefore, an integrated omics analysis is carried out to investigate the consequences of short-term fructose overfeeding (SFO) and identify the underlying molecular mechanisms.

Omics Insights into Metabolic Stress and Resilience of Rats in Response to Short-term Fructose Overfeeding.

The inherited polyglutamine (polyQ) expansion diseases are characterized by progressive accumulation of aggregation-prone polyQ proteins, which may provoke proteostasis imbalance and result in significant neurotoxicity. Using polyQ transgenic  models, we find that Kai-Xin-San (KXS), a well-known herbal formula traditionally used to treat mental disorders in China, can alleviate polyQ-mediated neuronal death and associated chemosensory deficiency. Intriguingly, KXS does not reduce polyQ aggregation  as demonstrated by Thioflavin-T test, but does inhibit polyQ aggregation in  models, indicating an indirect aggregation-inhibitory mechanism. Further investigation reveals that KXS can modulate two key arms of the protein quality control system, that is, heat shock response and autophagy, to clear polyQ aggregates, but has little effect on proteasome activity. In addition, KXS is able to reduce oxidative stress, which is involved in proteostasis and neurodegeneration, but has no effect on life span or dietary restriction response. To examine potential interaction of the four component herbs of KXS, a dissection strategy was used to study the effects of differential herbal combinations in  polyQ models. While the four herbs do contribute additively to KXS function,  is found to be the most effective constituent. Taken together, these findings not only demonstrate the neuroprotective ability of KXS but also suggest its potential as a proteostasis regulator in protein aggregation disorders and provide an insight into the mechanism studies of traditionally used complex prescriptions and their rationality.

The Traditional Formula Kai-Xin-San Alleviates Polyglutamine-Mediated Neurotoxicity by Modulating Proteostasis Network in .

Sea cucumbers have been used as food delicacies and traditional medicine for centuries, and their health benefits are partly attributed to their repertoire of proteins. Peptides prepared from the sea cucumber Apostichopus japonicus are reported to have in vitro antioxidant activities. Here, we investigated the in vivo antioxidant capacity of AjPH, a peptide-rich A. japonicus protein hydrolyzate, and found that AjPH is capable of increasing the survival rate and reducing the reactive oxygen species (ROS) level in the animal model Caenorhabditis elegans under increased oxidative stress induced by paraquat. AjPH is also shown to enhance the antioxidant defense system in paraquat-exposed nematodes, including upregulation of superoxide dismutase and catalase activities and reduction of malondialdehyde contents. To explore underpinning antioxidant mechanisms, cellular and chemical assays were used to demonstrate that AjPH not only reduces ROS accumulation in cells but also directly scavenges DPPH free radicals. Further studies indicate that AjPH can decrease age pigments and extend lifespan but does not reduce food intake, body length and brood size of the nematodes, demonstrating its capacity to delay physiological aging. Using activity-guided fractionation by ultrafiltration and gel filtration, we then isolated antioxidant fractions from AjPH and identified the sequences of their composing peptides, which were subjected to in silico analysis for prospective motifs, physicochemical properties and antioxidant potential. Taken together, our results provide an insight into the nutraceutical potential of the sea cucumber protein hydrolyzate for aging and related conditions and also a basis for future mechanistic studies of individual antioxidant peptides.

Antioxidant and anti-aging effects of a sea cucumber protein hydrolyzate and bioinformatic characterization of its composing peptides.

Crassostrea gigas Thunberg and other oysters have been traditionally used in China as folk remedies to invigorate the kidney and as natural aphrodisiacs to combat male impotence.

Enzymatic preparation of Crassostrea oyster peptides and their promoting effect on male hormone production.

Oxidative stress results when the production of oxidants outweighs the capacity of the antioxidant defence mechanisms. This can lead to pathological conditions including cancer and neurodegeneration. Consequently, there is considerable interest in compounds with antioxidant activity, including those from natural sources. Here, we characterise the antioxidant activity of three novel peptides identified in protein hydrolysates from the sea cucumber . Under oxidative stress conditions, synthetic versions of the sea cucumber peptides significantly compensate for glutathione depletion, decrease mitochondrial superoxide levels, and alleviate mitophagy in human neuroblastoma cells. Moreover, orally supplied peptides improve survival of the  after treatment with paraquat, the latter of which leads to the production of excessive oxidative stress. Thus, the sea cucumber peptides exhibit antioxidant activity at both the cellular and organism levels and might prove attractive as nutritional supplements for healthy ageing.

Article	Year
Purification and identification of anti-oxidant soybean peptides by consecutive chromatography and electrospray ionization-mass spectrometry. Rejuvenation research\| PubMed ID: 24147434	2014
Physicochemical Characterization and Functional Analysis of the Polysaccharide from the Edible Microalga Nostoc sphaeroides. Molecules (Basel, Switzerland)\| PubMed ID: 29495302	2018
Rosmarinic Acid Ameliorates HO-Induced Oxidative Stress in L02 Cells Through MAPK and Nrf2 Pathways. Rejuvenation research\| PubMed ID: 30379115	2019
Novel Bioactive Peptides from Protect against Free Radical-Induced Oxidative Stress through the Stress Response Factor DAF-16/FOXO. Marine drugs\| PubMed ID: 30423886	2018
Omics Insights into Metabolic Stress and Resilience of Rats in Response to Short-term Fructose Overfeeding. Molecular nutrition & food research\| PubMed ID: 31482642	2019
The Traditional Formula Kai-Xin-San Alleviates Polyglutamine-Mediated Neurotoxicity by Modulating Proteostasis Network in . Rejuvenation research\| PubMed ID: 31985332	2020
Antioxidant and anti-aging effects of a sea cucumber protein hydrolyzate and bioinformatic characterization of its composing peptides. Food & function\| PubMed ID: 32520032	2020
Enzymatic preparation of Crassostrea oyster peptides and their promoting effect on male hormone production. Journal of ethnopharmacology\| PubMed ID: 32918991	2021
Sea Cucumber-Derived Peptides Alleviate Oxidative Stress in Neuroblastoma Cells and Improve Survival in Exposed to Neurotoxic Paraquat. Oxidative medicine and cellular longevity\| PubMed ID: 33959216	2021

Zebo Huang

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