scholarly journals Dihydroceramide desaturase regulates the compartmentalization of Rac1 for neuronal oxidative stress

2020 ◽  
Author(s):  
Fei-Yang Tzou ◽  
Tsu-Yi Su ◽  
Yu-Lian Yu ◽  
Yu-Han Yeh ◽  
Chung-Chih Liu ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Nadph Oxidase ◽  
Neurological Disorders ◽  
De Novo ◽  
Neuronal Cells ◽  
Membrane Microdomains ◽  
List Type ◽  
Dihydroceramide Desaturase ◽  
Human Neuronal Cells ◽  
And Oxidative Stress

SummaryDisruption of sphingolipid homeostasis has been shown to cause neurological disorders. How specific sphingolipid species modulate the pathogenesis remains unknown. The last step of sphingolipid de novo synthesis is the conversion of dihydroceramide to ceramide catalyzed by dihydroceramide desaturase (human DEGS1; Drosophila Ifc). Loss of ifc leads to dihydroceramide accumulation and oxidative stress, resulting in photoreceptors degeneration, while DEGS1 variants were associated with leukodystrophy and neuropathy. Here, we demonstrated that ifc regulates Rac1 compartmentalization in fly photoreceptors and further showed that dihydroceramide alters the association of active Rac1 to membranes mimicking specific organelles. We also revealed that the major source of ROS originated from Rac1 and NADPH oxidase (NOX) in the cytoplasm, as the NOX inhibitor apocynin ameliorated the oxidative stress and functional defects in both fly ifc-KO photoreceptors and human neuronal cells with disease-associated variant DEGS1H132R. Therefore, DEGS1/ifc deficiency causes dihydroceramide accumulation, resulting in Rac1 translocation and NOX-dependent neurodegeneration.Graphical AbstractADEGS1/ifc converts dihydroceramide to ceramide in neuronal cells, and the endolysosomal NOX complex is not activated.B Dihydroceramide accumulates without functional DEGS1/ifc and causes alterations in membrane microdomains and recruits active Rac1 to endolysosomes. The activation of endolysosomal Rac1-NOX complex elevates cytosolic ROS levels, causing neurodegeneration.In Brief (eTOC blurb)Deficiency in dihydroceramide desaturase causes oxidative stress-mediated neurological disorders. Tzou and Su et al. show that increased dihydroceramide causes the relocalization of active Rac1, whilst inhibition of the Rac1-NOX ameliorates the oxidative stress and neuronal defects. NOX inhibitor apocynin may provide new direction of treatments for patients with DEGS1 variants.HighlightsDeficiency in dihydroceramide (dhCer) desaturase induces cytoplasmic ROS elevationdhCer alters the binding of active Rac1 to reconstituted organelle membranesActive Rac1 is enriched in endolysosomes in ifc-KO neurons for ROS genesisRac1-NADPH oxidase elicits ROS, degenerating leukodystrophy-related neuronal cells

scholarly journals Amino Acid Transporter LAT1 (SLC7A5) Mediates MeHg-Induced Oxidative Stress Defense in the Human Placental Cell Line HTR-8/SVneo

2021 ◽  
Vol 22 (4) ◽  
pp. 1707
Author(s):  
Sebastian Granitzer ◽  
Raimund Widhalm ◽  
Martin Forsthuber ◽  
Isabella Ellinger ◽  
Gernot Desoye ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Amino Acid ◽  
De Novo ◽  
Structural Similarity ◽  
Amino Acid Transporter ◽  
Cell Number ◽  
Mehg Exposure ◽  
Acid Transporter ◽  
And Oxidative Stress

The placental barrier can protect the fetus from contact with harmful substances. The potent neurotoxin methylmercury (MeHg), however, is very efficiently transported across the placenta. Our previous data suggested that L-type amino acid transporter (LAT)1 is involved in placental MeHg uptake, accepting MeHg-L-cysteine conjugates as substrate due to structural similarity to methionine. The aim of the present study was to investigate the antioxidant defense of placental cells to MeHg exposure and the role of LAT1 in this response. When trophoblast-derived HTR-8/SVneo cells were LAT1 depleted by siRNA-mediated knockdown, they accumulated less MeHg. However, they were more susceptible to MeHg-induced toxicity. This was evidenced in decreased cell viability at a usually noncytotoxic concentration of 0.03 µM MeHg (~6 µg/L). Treatment with ≥0.3 µM MeHg increased cytotoxicity, apoptosis rate, and oxidative stress of HTR-8/SVneo cells. These effects were enhanced under LAT1 knockdown. Reduced cell number was seen when MeHg-exposed cells were cultured in medium low in cysteine, a constituent of the tripeptide glutathione (GSH). Because LAT1-deficient HTR-8/SVneo cells have lower GSH levels than control cells (independent of MeHg treatment), we conclude that LAT1 is essential for de novo synthesis of GSH, required to counteract oxidative stress. Genetic predisposition to decreased LAT1 function combined with MeHg exposure could increase the risk of placental damage.

Abstract 5858: Role of Oxygen Tension and Oxidative Stress in Human Saphenous Vein Remodeling

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Binata Joddar ◽  
Rashmeet K Reen ◽  
Michael Firstenberg ◽  
Keith J Gooch
Keyword(s):  
Oxidative Stress ◽  
Oxygen Tension ◽  
Ex Vivo ◽  
Neointimal Hyperplasia ◽  
Fold Increase ◽  
List Type ◽  
Saphenous Veins ◽  
Arterial Po2 ◽  
And Oxidative Stress

Vessels cultured ex vivo maintain viability and vasoactivity for weeks and can remodel in response to mechanical cues. When cultured in the presence of 5% CO2/balance air veins develop neointimal hyperplasia (IH) while arteries do not suggesting that exposure to significant increases in pO2 levels might stimulate IH. Neointimal hyperplasia (IH) is a known mechanism by which saphenous veins have a decreased patency compared to arterial conduits when used for coronary artery bypass. We sought to explore the role of oxygen tension and oxidative stress in IH. Test the hypothesis that exposure of human saphenous veins (HSV) to arterial pO2 stimulates IH via ROS-mediated pathways. Almost 40 HSV remnants acquired following CABG were cultured ex vivo with arterial (~95mmHg) pO2 or venous (~40mmHg) pO2 for 14 days. All differences reported have a p<0.05 via Student’s t-test. Results: HSV cultured at arterial pO2 exhibited significant IH as evidenced by disruption of the IEL, invasion of cells from the media, and a 2.8-fold greater intimal area than fresh HSV, a 5.8-fold increase in cell proliferation compared to fresh HSV, increased ROS levels and oxidative stress as evidenced by 4-fold increase in 4-HNE level (a marker of oxidative stress), increased DHE staining (indicative of superoxide generation), and a progressive increase in total ROS levels with time as assessed by DCF fluorescence, and a 3-fold increase in phosphorylated p38-MAPK, which is implicated in SMC proliferation. In stark contrast vessels culture at arterial pO2, HSV cultured with venous pO2 did not develop increased IH and were indistinguishable from fresh vessels with respect to proliferation, markers of oxidative stress, and MAPK expression levels. Supplementing culture medium with antioxidants including Tiron or NAC blocked the pO2-induced changes. These data indicate that exposure to arterial pO2 increases cellular proliferation and stimulates IH, potentially via oxidative stress or ROS signaling and also suggest that exposure to elevated arterial pO2 might stimulate pathological remodeling of veins grafted into the arterial circulation. This research has received full or partial funding support from the American Heart Association, AHA Great Rivers Affiliate (Delaware, Kentucky, Ohio, Pennsylvania & West Virginia).

scholarly journals Recurrent insulin-induced hypoglycemia induces AngII and COX2 leading to renal (pro)renin receptor expression and oxidative stress

2017 ◽  
Vol 5 (1) ◽  
pp. 71 ◽  
Author(s):  
Wael Alanazi ◽  
Mohammad Uddin ◽  
Selim Fakhruddin ◽  
Keith Jackson
Keyword(s):  
Oxidative Stress ◽  
Nadph Oxidase ◽  
Kidney Injury ◽  
Organ Damage ◽  
Day Surgery ◽  
Receptor Expression ◽  
Sprague Dawley ◽  
Subunit Expression ◽  
Renal Biomarker ◽  
And Oxidative Stress

Background: Recurrent insulin-induced hypoglycemia (RIIH) is an avoidable consequence in the therapeutic management of diabetes mellitus. RIIH has been implicated in causing hypertension through an increase in renal and systemic AngII production.Objective: The present study was performed to assess the hypothesis that chronic insulin treatment enhances AngII and COX2 formation which in turn increases (pro) renin receptor (PRR) expression and NADPH oxidase-mediated oxidative stress, leading to renal and cardiac injury.Methods: The present studies were conducted in Male Sprague Dawley rats treated with daily subcutaneous injections of 7u/kg insulin or saline for 14 days. On the 14th day, surgery was performed for treatment infusion (captopril 12mg/kg, NS398 0.3mg/kg or vehicle), and renal interstitial fluid sample and urine collections for biomarker measurements. At the end of the experiments, kidneys and hearts were harvested to evaluate PRR and NOX2 (NADPH oxidase subunit) expression and oxidative stress.Results: We found that RIIH enhanced AngII and COX2 activity, leading to renal PRR expression and NADPH oxidase-induced oxidative stress in the heart and kidney. 8-isoprostane was evaluated as a renal biomarker of oxidative stress, which was induced in insulin treated animals and modulated by captopril and NS398. In addition, there was a slight increase in NGAL, a urinary biomarker of acute kidney injury (AKI), in insulin treated animals when compared to control.Conclusion: These results demonstrate that RIIH induces renal PRR expression and oxidative stress through increasing AngII and COX2 in the heart and kidney, leading to end-organ damage.

scholarly journals Coenzyme Q10, Ageing and the Nervous System: An Overview

Antioxidants ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 2
Author(s):  
David Mantle ◽  
Robert A. Heaton ◽  
Iain P. Hargreaves
Keyword(s):  
Oxidative Stress ◽  
Coenzyme Q10 ◽  
Neurological Disorders ◽  
Neurological Disease ◽  
Age Related ◽  
Increased Risk ◽  
Potential Therapeutic Role ◽  
Ageing Brain ◽  
And Oxidative Stress

The ageing brain is characterised by changes at the physical, histological, biochemical and physiological levels. This ageing process is associated with an increased risk of developing a number of neurological disorders, notably Alzheimer’s disease and Parkinson’s disease. There is evidence that mitochondrial dysfunction and oxidative stress play a key role in the pathogenesis of such disorders. In this article, we review the potential therapeutic role in these age-related neurological disorders of supplementary coenzyme Q10, a vitamin-like substance of vital importance for normal mitochondrial function and as an antioxidant. This review is concerned primarily with studies in humans rather than in vitro studies or studies in animal models of neurological disease. In particular, the reasons why the outcomes of clinical trials supplementing coenzyme Q10 in these neurological disorders is discussed.

Testosterone induces leucocyte migration by NADPH oxidase-driven ROS- and COX2-dependent mechanisms

2015 ◽  
Vol 129 (1) ◽  
pp. 39-48 ◽  
Author(s):  
Andreia Z. Chignalia ◽  
Maria Aparecida Oliveira ◽  
Victor Debbas ◽  
Randal O. Dull ◽  
Francisco R.M. Laurindo ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Cardiovascular Risk ◽  
Cardiovascular Diseases ◽  
Nadph Oxidase ◽  
Vascular Disease ◽  
Leucocyte Migration ◽  
And Oxidative Stress

Testosterone triggers leucocyte migration and oxidative stress, important features in inflammation and in the development of cardiovascular diseases. The mechanisms by which testosterone increase cardiovascular risk are unknown. We describe one pathway whereby testosterone can potentially contribute to vascular disease.

scholarly journals Aging increases vulnerability to stress-induced depression via upregulation of NADPH oxidase in mice

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Jung-Eun Lee ◽  
Hye-Jin Kwon ◽  
Juli Choi ◽  
Ji-Seon Seo ◽  
Pyung-Lim Han
Keyword(s):  
Oxidative Stress ◽  
Nadph Oxidase ◽  
Chronic Stress ◽  
Brain Aging ◽  
Aged Mice ◽  
Upstream Regulator ◽  
Underlying Mechanisms ◽  
Old Mice ◽  
And Oxidative Stress ◽  
Young Mice

AbstractBrain aging proceeds with cellular and molecular changes in the limbic system. Aging-dependent changes might affect emotion and stress coping, yet the underlying mechanisms remain unclear. Here, we show aged (18-month-old) mice exhibit upregulation of NADPH oxidase and oxidative stress in the hippocampus, which mirrors the changes in young (2-month-old) mice subjected to chronic stress. Aged mice that lack p47phox, a key subunit of NADPH oxidase, do not show increased oxidative stress. Aged mice exhibit depression-like behavior following weak stress that does not produce depressive behavior in young mice. Aged mice have reduced expression of the epigenetic factor SUV39H1 and its upstream regulator p-AMPK, and increased expression of Ppp2ca in the hippocampus—changes that occur in young mice exposed to chronic stress. SUV39H1 mediates stress- and aging-induced sustained upregulation of p47phox and oxidative stress. These results suggest that aging increases susceptibility to stress by upregulating NADPH oxidase in the hippocampus.

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