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Intracellular calcium chelation abolishes a redox effect of tocopherol isomers on HyPerexpressing Caco-2 cells. Time courses of HyPer signal showing the effect of the three tocopherol isomers (50 μM) in nontreated cells (filled circles) and cells treated with 75 μM BAPTA (open circles). Isomer addition is shown by a dotted line and a white bar on each plot. (A), α-tocopherol was applied in 34 control cells from four experiments and 12 cells treated with BAPTA from three experiments. (B), changes in HyPer ratio induced by α-tocopherol exposure expressed as the difference between the signals obtained after 3 min of tocopherol addition and its respective baselines; this analysis was done for control and BAPTA-treated cells. As for (A,B), (C) shows the effect of adding of γ-tocopherol, whereas data analysis is depicted in (D). Data correspond to the average ± SE from 44 control cells from four experiments and 16 BAPTA-treated cells from three independent experiments. (E) The effect of δ-tocopherol is shown in 24 control cells from four experiments and 12 BAPTA-treated cells from three independent experiments. Data are expressed as the average ± SE. Data analysis is shown in (F). Asterisks (*) mean significant differences between control and BAPTA-treated groups (nonpaired t-Student test).
Source publication
Most of the biological impacts of Vitamin E, including the redox effects, have been raised from studies with α-tocopherol only, despite the fact that tocopherol-containing foods carry mixed tocopherol isomers. Here, we investigated the cellular mechanisms involved in the immediate antioxidant responses evoked by α-, γ- and δ-tocopherol in Caco-2 ce...
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Context 1
... to establish if Ca 2+ increment induced by tocopherol isomers were effectively mediating changes in the antioxidant capacity of the cytoplasm, which are reported by HyPer as a diminishment in the ratio signal, we treated the cells with BAPTA and then applied 50 μM of each tocopherol isomer, a concentration that induces redox changes for the three isomers evaluated as can be observed in Figure S4. None of the evaluated isomers were able to induce a diminishment in the signal of HyPer of BAPTA-treated Caco-2 cells, confirming that elevations in cytoplasmic calcium are required to induce acute redox responses ( Figure 6). This finding expands the level of interaction of tocopherols beyond their potential as ROS scavengers, by adding calcium signalling as part of its repertoire to induce redox responses in intact mammalian cells. ...
Context 2
... to establish if Ca 2+ increment induced by tocopherol isomers were effectively mediating changes in the antioxidant capacity of the cytoplasm, which are reported by HyPer as a diminishment in the ratio signal, we treated the cells with BAPTA and then applied 50 µM of each tocopherol isomer, a concentration that induces redox changes for the three isomers evaluated as can be observed in Figure S4. None of the evaluated isomers were able to induce a diminishment in the signal of HyPer of BAPTA-treated Caco-2 cells, confirming that elevations in cytoplasmic calcium are required to induce acute redox responses ( Figure 6). This finding expands the level of interaction of tocopherols beyond their potential as ROS scavengers, by adding calcium signalling as part of its repertoire to induce redox responses in intact mammalian cells. ...
Citations
... Tocopherol and cyclodextrin have been reported to be used as therapeutic small drugs to alleviate lipid accumulation and recuperate enlarged lysosomes in several LSDs as they enhance lysosomal exocytosis through increment of cytosolic and lysosomal Ca 2+ level [19]. The exact mechanism of action is unclear, but it was reported that tocopherol isomers evoked fast Ca 2+ responses with an increase in cytosolic Ca 2+ [20]. It was also shown that tocopherol caused exocytosis of related vesicles, such as endocytic ones [21]. ...
Introduction. The Tay-Sachs disease is a progressive neurodegenerative disorder that is caused by a genetic mutation in the HEXA gene coding the lysosomal α-subunit of β-hexosaminidase A. Currently, there is no effective treatment for Tay-Sachs. Induction of exocytosis as a potential treatment approach is suggested to restore lysosomal enlargement in several lysosomal storage diseases. Here, we aimed to test the therapeutic potential of two small molecules, δ-tocopherol and hydroxypropyl-β-cyclodextrin, in fibroblast and neuroglia cells derived from Hexa-/-Neu3-/- mice and Tay-Sachs patients. Method. The effect of two small molecules on lysosomal enlargement and GM2 accumulation in lysosomes was examined by LysoTracker staining and immunocytochemical colocalization analysis for GM2 and LAMP1. qRT-PCR and fluorometric enzyme assay were also used to investigate the effect of combined treatment on the level of neuraminidase 1, a negative regulator of exocytosis. Results. Single treatment with δ-tocopherol (5-40 μM) and hydroxypropyl-β-cyclodextrin (10-50 μM) for 48 hours led to significant induction of lysosomal exocytosis. We demonstrated that the combined treatment with δ-tocopherol (10 μM) and hydroxypropyl-β-cyclodextrin (25 μM) resulted in a significant reduction of lysosomal GM2 and downregulation of lysosomal Neu1 expression. Conclusion. In this study, we demonstrated that inducing exocytosis by δ-tocopherol and hydroxypropyl-β-cyclodextrin might have therapeutic potential to reduce GM2 storage and pathology in Tay-Sachs cells.
... Vitamin E has been actively investigated for its effects in managing pre-eclampsia, because it could tackle several pathophysiological pathways of the disease, theoretically. Firstly, vitamin E is a well-established antioxidant [45,46] that can suppress the oxidative damage caused by repeated placental ischaemia/reperfusion. Secondly, vitamin E and its metabolites are anti-inflammatory agents [47][48][49] that could suppress systemic inflammation caused by the release of damage-associated molecules. ...
The pathophysiology of pre-eclampsia involves two major pathways, namely systemic oxidative stress and subsequent generalised inflammatory response, which eventually culminates in endothelial cell injury and the syndrome of pre-eclampsia with multi-organ dysfunction. Aspirin has been used to reduce the risk of pre-eclampsia, but it only possesses anti-inflammatory properties without any antioxidant effect. Hence, it can only partially alleviate the problem. Tocotrienols are a unique form of vitamin E with strong antioxidant and anti-inflammatory properties that can be exploited as a preventive agent for pre-eclampsia. Many preclinical models showed that tocotrienol can also prevent hypertension and ischaemic/reperfusion injury, which are the two main features in pre-eclampsia. This review explores the mechanism of action of tocotrienol in relation to the pathophysiology of pre-eclampsia. In conclusion, the study provides sufficient justification for the establishment of a large clinical trial to thoroughly assess the capability of tocotrienol in preventing pre-eclampsia.
... This is supported by extensive research over several decades (Sen et al., 2006;Traber and Atkinson, 2007;Zingg, 2019). More recently, however, it has become increasingly clear that tocopherols and tocotrienols can serve as signaling molecules to activate kinases and transcription factors alter gene expression Ghani et al., 2019;Gugliandolo et al., 2019;Mehrabi et al., 2019;Zingg, 2019;Hidalgo et al., 2020;Moore et al., 2020;Ding et al., 2021;Ungurianu et al., 2021;Willems et al., 2021). ...
The purpose of this study was to determine if different vitamin E components exhibit similar efficacy and mechanism of action in protecting Retinal pigment epithelium (RPE) cells from oxidative damage. We hypothesized that α-tocopherol (αT) is unique among vitamin E components in its cytoprotective mechanism of action against oxidative stress in RPE cells and that it requires protein synthesis for optimal antioxidant effect. We used cell viability assays, fluorescent chemical labeling of DNA and actin and immuno-labeling of the antioxidant proteins Nrf2 and Sod2 and of the tight junction protein, ZO-1, and confocal microscopy to determine the effects of αT and γT against oxidative stress in immortalized human RPE cells (hTERT-RPE). Using the four main vitamin E components, αT, γT, δ-tocopherol (δT) and α-tocotrienol (αTr), we ascertained that they exhibit similar, but not identical, antioxidant activity as αT when used at equimolar concentrations. In addition, we determined that the exposure time of RPE cells to α-tocopherol is critical for its ability to protect against oxidative damage. Lastly, we determined that αT, but not γT, partially requires the synthesis of new proteins within a 24-h period and prior to exposure to tBHP for optimal cytoprotection. We conclude that, unlike γT and δT, αT appears to be unique in its requirement for transport and/or signaling for it to be an effective antioxidant. As a result, more focus should be paid to which vitamin E components are used for antioxidant interventions.
... In colon cancer cell lines, TFs were found to exhibit an anti-inflammatory effect and promoted apoptosis (especially δ-TF) in an IFNγ/PMA model [87], suppressing the activation of NF-κB (α-TF and γ-TF) and enhancing the Nrf2 pathway (δ-TF) [88]; their overall effect on antioxidant defense also seemed to be dependent on an elevation of cytoplasmic Ca 2+ [89]. Moreover, γ-TF increased PPARγ mRNA and protein expression (more efficiently versus α-TF or troglitazone), with possibly important implications in inflammatory diseases [90]. ...
... Rapid increase in cytosolic calcium for all isomers Intracellular calcium elevation is necessary for the TF-induced antioxidant impact [89] SW 480 human colon cancer cell lines VEGF-vascular endothelial growth factor; AP-1-activator protein 1; IGF-insulin growth factor; EGF-epidermal growth factor; ER-endoplasmic reticulum; JNK-c-Jun N-terminal kinase; p38-p38 mitogen-activated protein kinase; HIF-1α-hypoxia-inducible factor 1α; DPPP-1,3-Bis(diphenylphosphino)propane; GSH-glutathione; GSSG-oxidized glutathione; PI3K-phosphoinositide 3-kinase; GSK-3-glycogen synthase kinase 3; PARP-poly (ADP-ribose) polymerase; ATF3-activating transcription factor 3; AMPK-AMP kinase; FOXO3-forkhead box O-3; mTOR-mammalian target of rapamycin; GLUT-1-glucose transporter 1; Myc-proto-oncogenes; Akt-protein kinase B; Bax-Bcl-2-like protein 4; Ki-67-marker of proliferation Ki-67. ...
Vitamin E, comprising tocopherols and tocotrienols, is mainly known as an antioxidant. The aim of this review is to summarize the molecular mechanisms and signaling pathways linked to inflammation and malignancy modulated by its vitamers. Preclinical reports highlighted a myriad of cellular effects like modulating the synthesis of pro-inflammatory molecules and oxidative stress response, inhibiting the NF-κB pathway, regulating cell cycle, and apoptosis. Furthermore, animal-based models have shown that these molecules affect the activity of various enzymes and signaling pathways, such as MAPK, PI3K/Akt/mTOR, JAK/STAT, and NF-κB, acting as the underlying mechanisms of their reported anti-inflammatory, neuroprotective, and anti-cancer effects. In clinical settings, not all of these were proven, with reports varying considerably. Nonetheless, vitamin E was shown to improve redox and inflammatory status in healthy, diabetic, and metabolic syndrome subjects. The anti-cancer effects were inconsistent, with both pro- and anti-malignant being reported. Regarding its neuroprotective properties, several studies have shown protective effects suggesting vitamin E as a potential prevention and therapeutic (as adjuvant) tool. However, source and dosage greatly influence the observed effects, with bioavailability seemingly a key factor in obtaining the preferred outcome. We conclude that this group of molecules presents exciting potential for the prevention and treatment of diseases with an inflammatory, redox, or malignant component.
... Real-time monitoring of HyPer, a redox biosensor, allows the possibility to observe if the interaction of compounds with cellular components leads to a redox response. Additionally, the redox properties of cytoplasm in living cells become exposed by challenging the cells to an exogenous H 2 O 2 stimulus, an experimental strategy useful to assign biologically relevant antioxidant impact (Hernández et al., 2018, Hidalgo et al., 2020. Accordingly, a compound that induces an antioxidant response in intact cells might improve oxidative stress, condition implicated in β-cell dysfunction, impaired glucose tolerance, insulin resistance, and eventually, T2DM (Gunathilaka et al., 2019). ...
Metabolic syndrome is a condition whose incidence has been increasing around the world. It promotes a metabolic state of chronic systemic inflammation, correlated to cellular stress and genetic mutations, and subsequently with deadly chronic diseases, such as type 2 diabetes mellitus, cardiovascular diseases, and cancer. A randomized placebo-controlled study (n = 156) was conducted to determine the effects of consuming an enriched bread with 0.05% of a 1:1 mixture of (−)-epicatechin and quercetin on anthropometric and biochemical parameters of the participants. As a result, total cholesterol, LDL-cholesterol, total triglycerides, and fasting plasma glucose significantly decreased after three months of daily enriched bread consumption. Nuclear abnormalities in buccal epithelium cells also decreased (15.8 ± 3.2 down to 8.3 ± 1.0), showing a genoprotective effect. The antioxidant properties of these compounds were observed by monitoring changes in the cytoplasmic redox tone of intact Caco-2 cells expressing HyPer, a fluorescent redox biosensor. The combination of (–)-epicatechin and quercetin changes the cytoplasmic redox ambient in living cells and significantly improves biochemical parameters related to metabolic syndrome, and decreases the number of cell abnormalities in buccal epithelium cells of patients.
