Protective effect of Terminalia chebula Retz. extract against Aß aggregation and Aß-induced toxicity in Caenorhabditis elegans.

ETHNOPHARMACOLOGICAL RELEVANCE: Terminalia chebula Retz. (T.chebula) is an important medicinal plant in Tibetan medicine and Ayurveda. T.chebula is known as the "King of Tibetan Medicine", due to its widespread clinical pharmacological activity such as anti-inflammatory, antioxidative, antidiabetic as well as anticancer in lots of in vivo and in vitro models. In this study, we use transgenic and/or RNAi Caenorhabditis elegans (C.elegans) model to simulation the AD pathological features induced by Aß, to detect the effect of TWE on improving Aß-induced toxicity and the corresponding molecular mechanism. AIM OF STUDY: The study aimed to tested the activities and its possible mechanism of T.chebula to against Aß1-42 induced toxicity and Aß1-42 aggregation. MATERIALS AND METHODS: Using transgenic C.elegans strain CL2006 and CL4176 as models respond to paralytic induced by Aß toxicity. The transcription factors DAF-16 and SKN-1 were analyzed used a fluorescence microscope in transgenic strains (DAF-16:GFP, SKN-1:GFP). The function of DAF-16 and SKN-1 was further investigated using loss-of-function strains by feeding RNA interference (RNAi) bacteria. To evaluate the aggregation level of Aß in the transgenic C.elegans, Thioflavin S (ThS) staining and WB visualized the levels of Aß monomers and oligomers. RESULTS: TWE treatment can significantly improve the paralysis of transgenic C.elegans caused by Aß aggregation (up to 14%). The Aß aggregates in transgenic C.elegans are significantly inhibited under TWE exposure (up to 70%). TWE increases the nuclear localization of the key transcription factor DAF-16 and HSF-1, which in turn leads to the expression of downstream Hsp-16.2 protein and exerts its inhibitory effect on Aß aggregation. Meanwhile, paralysis improved has not observed in SKN-1 mutation and/or RNAi C.elegans. CONCLUSION: Our results indicate that TWE can protect C.elegans against the Aß1-42-induced toxicity, inhibition Aß1-42 aggregation and delaying Aß-induced paralysis. The neuroprotective effect of TWE involves the activation of DAF-16/HSF-1/Hsp-16.2 pathway.

Ability of selenium species to inhibit metal-induced Aß aggregation involved in the development of Alzheimer's disease.

Extracellular accumulation of amyloid beta peptide (Aß) is believed to be one of the main factors responsible for neurodegeneration in Alzheimer's disease (AD). Metals could induce Aß aggregation, by their redox activity or binding properties to amyloid ß fibrils, leading to their accumulation and deposition outside neurons. For this reason, metal chelation may have an acknowledged part to play in AD prevention and treatment. In the current work, the role of different selenium species, including selenium nanoparticles, in Aß aggregation, was studied by evaluating their metal-chelating properties and their ability both to inhibit metal-induced Aß1-42 aggregation fibrils and to disaggregate them once formed. Transition biometals such as Fe(II), Cu(II), and Zn(II) at 50 µM were selected to establish the in vitro models. The DPPH assay was used to determine the antioxidant capacity of the evaluated selenium species. Selenium nanoparticles stabilized with chitosan (Ch-SeNPs) and with both chitosan and chlorogenic acid polyphenol (CGA@ChSeNPs) showed the highest antioxidant properties with EC50 of 0.9 and 0.07 mM, respectively. UV-Vis and d1(UV-Vis) spectra also revealed that selenium species, in particular selenomethionine (SeMet), were able to interact with metals. Regarding Aß1-42 incubation experiments, Fe(II), Cu(II), and Zn(II) induced Aß aggregation, in a similar way to most of the evaluated selenium species. However, Ch-SeNPs produced a high inhibition of metal-induced Aß aggregation, as well as a high disaggregation capacity of Aß fibrils in both the presence and absence of biometals, in addition to reducing the length and width (20% of reduction in the presence of Zn(II)) of the generated Aß fibrils. Graphical abstract.

Targeting the NPL4 Adaptor of p97/VCP Segregase by Disulfiram as an Emerging Cancer Vulnerability Evokes Replication Stress and DNA Damage while Silencing the ATR Pathway.

Research on repurposing the old alcohol-aversion drug disulfiram (DSF) for cancer treatment has identified inhibition of NPL4, an adaptor of the p97/VCP segregase essential for turnover of proteins involved in multiple pathways, as an unsuspected cancer cell vulnerability. While we reported that NPL4 is targeted by the anticancer metabolite of DSF, the bis-diethyldithiocarbamate-copper complex (CuET), the exact, apparently multifaceted mechanism(s) through which the CuET-induced aggregation of NPL4 kills cancer cells remains to be fully elucidated. Given the pronounced sensitivity to CuET in tumor cell lines lacking the genome integrity caretaker proteins BRCA1 and BRCA2, here we investigated the impact of NPL4 targeting by CuET on DNA replication dynamics and DNA damage response pathways in human cancer cell models. Our results show that CuET treatment interferes with DNA replication, slows down replication fork progression and causes accumulation of single-stranded DNA (ssDNA). Such a replication stress (RS) scenario is associated with DNA damage, preferentially in the S phase, and activates the homologous recombination (HR) DNA repair pathway. At the same time, we find that cellular responses to the CuET-triggered RS are seriously impaired due to concomitant malfunction of the ATRIP-ATR-CHK1 signaling pathway that reflects an unorthodox checkpoint silencing mode through ATR (Ataxia telangiectasia and Rad3 related) kinase sequestration within the CuET-evoked NPL4 protein aggregates.

Effect of hemin, baicalein and heme oxygenase-1 (HO-1) enzyme activity inhibitors on Cd-induced accumulation of HO-1, HSPs and aggresome-like structures in Xenopus kidney epithelial cells.

Cadmium is a highly toxic environmental pollutant that can cause many adverse effects including cancer, neurological disease and kidney damage. Aquatic amphibians are particularly susceptible to this toxicant as it was shown to cause developmental abnormalities and genotoxic effects. In mammalian cells, the accumulation of heme oxygenase-1 (HO-1), which catalyzes the breakdown of heme into CO, free iron and biliverdin, was reported to protect cells against potentially lethal concentrations of CdCl2. In the present study, CdCl2 treatment of A6 kidney epithelial cells, derived from the frog, Xenopus laevis, induced the accumulation of HO-1, heat shock protein 70 (HSP70) and HSP30 as well as an increase in the production of aggregated protein and aggresome-like structures. Treatment of cells with inhibitors of HO-1 enzyme activity, tin protoporphyrin (SnPP) and zinc protoporphyrin (ZnPP), enhanced CdCl2-induced actin cytoskeletal disorganization and the accumulation of HO-1, HSP70, aggregated protein and aggresome-like structures. Treatment of cells with hemin and baicalein, which were previously shown to provide cytoprotection against various stresses, induced HO-1 accumulation in a concentration-dependent manner. Also, treatment of cells with hemin and baicalein suppressed CdCl2-induced actin dysregulation and the accumulation of aggregated protein and aggresome-like structures. This cytoprotective effect was inhibited by SnPP. These results suggest that HO-1-mediated protection against CdCl2 toxicity includes the maintenance of actin cytoskeletal and microtubular structure and the suppression of aggregated protein and aggresome-like structures.

Multifunctional 8-hydroxyquinoline-appended cyclodextrins as new inhibitors of metal-induced protein aggregation.

Mounting evidence suggests a pivotal role of metal imbalances in protein misfolding and amyloid diseases. As such, metal ions represent a promising therapeutic target. In this context, the synthesis of chelators that also contain complementary functionalities to combat the multifactorial nature of neurodegenerative diseases is a highly topical issue. We report two new 8-hydroxyquinoline-appended cyclodextrins and highlight their multifunctional properties, including their Cu(II) and Zn(II) binding abilities, and capacity to act as antioxidants and metal-induced antiaggregants. In particular, the latter property has been applied in the development of an effective assay that exploits the formation of amyloid fibrils when ß-lactoglobulin A is heated in the presence of metal ions.