scholarly journals Acetylated Thioredoxin Reductase 1 Resists Oxidative Inactivation

2021 ◽  
Vol 9 ◽  
Author(s):  
David. E. Wright ◽  
Nikolaus Panaseiko ◽  
Patrick O’Donoghue
Keyword(s):  
Oxidative Stress ◽  
Thioredoxin Reductase ◽  
Oxygen Species ◽  
Site Specific ◽  
Oxidative Inactivation ◽  
Thioredoxin Reductase 1 ◽  
Lysine Residues ◽  
Canonical Amino Acid ◽  
Genetic Code Expansion ◽  
Low Activity

Thioredoxin Reductase 1 (TrxR1) is an enzyme that protects human cells against reactive oxygen species generated during oxidative stress or in response to chemotherapies. Acetylation of TrxR1 is associated with oxidative stress, but the function of TrxR1 acetylation in oxidizing conditions is unknown. Using genetic code expansion, we produced recombinant and site-specifically acetylated variants of TrxR1 that also contain the non-canonical amino acid, selenocysteine, which is essential for TrxR1 activity. We previously showed site-specific acetylation at three different lysine residues increases TrxR1 activity by reducing the levels of linked dimers and low activity TrxR1 tetramers. Here we use enzymological studies to show that acetylated TrxR1 is resistant to both oxidative inactivation and peroxide-induced multimer formation. To compare the effect of programmed acetylation at specific lysine residues to non-specific acetylation, we produced acetylated TrxR1 using aspirin as a model non-enzymatic acetyl donor. Mass spectrometry confirmed aspirin-induced acetylation at multiple lysine residues in TrxR1. In contrast to unmodified TrxR1, the non-specifically acetylated enzyme showed no loss of activity under increasing and strongly oxidating conditions. Our data suggest that both site-specific and general acetylation of TrxR1 regulate the enzyme’s ability to resist oxidative damage.

scholarly journals Oxidative stress response in regulatory and conventional T cells: a comparison between patients with chronic coronary syndrome and healthy subjects

2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Anna K. Lundberg ◽  
Rosanna W. S. Chung ◽  
Louise Zeijlon ◽  
Gustav Fernström ◽  
Lena Jonasson
Keyword(s):  
Oxidative Stress ◽  
T Cells ◽  
Mononuclear Cells ◽  
Ex Vivo ◽  
Thioredoxin Reductase ◽  
Healthy Controls ◽  
Antioxidant Genes ◽  
Consistent Finding ◽  
Coronary Syndrome ◽  
Thioredoxin Reductase 1

Abstract Background Inflammation and oxidative stress form a vicious circle in atherosclerosis. Oxidative stress can have detrimental effects on T cells. A unique subset of CD4+ T cells, known as regulatory T (Treg) cells, has been associated with atheroprotective effects. Reduced numbers of Treg cells is a consistent finding in patients with chronic coronary syndrome (CCS). However, it is unclear to what extent these cells are sensitive to oxidative stress. In this pilot study, we tested the hypothesis that oxidative stress might be a potential contributor to the Treg cell deficit in CCS patients. Methods Thirty patients with CCS and 24 healthy controls were included. Treg (CD4+CD25+CD127−) and conventional T (CD4+CD25−, Tconv) cells were isolated and treated with increasing doses of H2O2. Intracellular ROS levels and cell death were measured after 2 and 18 h, respectively. The expression of antioxidant genes was measured in freshly isolated Treg and Tconv cells. Also, total antioxidant capacity (TAC) was measured in fresh peripheral blood mononuclear cells, and oxidized (ox) LDL/LDL ratios were determined in plasma. Results At all doses of H2O2, Treg cells accumulated more ROS and exhibited higher rates of death than their Tconv counterparts, p < 0.0001. Treg cells also expressed higher levels of antioxidant genes, including thioredoxin and thioredoxin reductase-1 (p < 0.0001), though without any differences between CCS patients and controls. Tconv cells from CCS patients were, on the other hand, more sensitive to oxidative stress ex vivo and expressed more thioredoxin reductase-1 than Tconv cells from controls, p < 0.05. Also, TAC levels were lower in patients, 0.97 vs 1.53 UAE/100 µg, p = 0.001, while oxLDL/LDL ratios were higher, 29 vs 22, p = 0.006. Conclusion Treg cells isolated from either CCS patients or healthy controls were all highly sensitive to oxidative stress ex vivo. There were signs of oxidant-antioxidant imbalance in CCS patients and we thus assume that oxidative stress may play a role in the reduction of Treg cells in vivo.

scholarly journals Oxidative Stress Response in Regulatory and Conventional T Cells: A Comparison Between Patients with Chronic Coronary Syndrome and Healthy Subjects

2020 ◽  
Author(s):  
Anna K Lundberg ◽  
Rosanna WS Chung ◽  
Louise Zeijlon ◽  
Gustav Fernström ◽  
Lena Jonasson
Keyword(s):  
Oxidative Stress ◽  
T Cells ◽  
Mononuclear Cells ◽  
Ex Vivo ◽  
Thioredoxin Reductase ◽  
Healthy Controls ◽  
Antioxidant Genes ◽  
Consistent Finding ◽  
Coronary Syndrome ◽  
Thioredoxin Reductase 1

Abstract BackgroundInflammation and oxidative stress form a vicious circle in atherosclerosis. Oxidative stress can have detrimental effects on T cells. A unique subset of CD4+ T cells, known as regulatory T (Treg) cells, has been associated with atheroprotective effects. Reduced numbers of Treg cells is a consistent finding in patients with chronic coronary syndrome (CCS). However, it is unclear to what extent these cells are sensitive to oxidative stress. In the present study, we tested the hypothesis that oxidative stress might be a potential contributor to the Treg cell deficit in CCS patients. MethodsThirty patients with CCS and 24 healthy controls were included. Treg (CD4+CD25+CD127-) and conventional T (CD4+CD25-, Tconv) cells were isolated and treated with increasing doses of H2O2. Intracellular ROS levels and cell death were measured after 2 and 18 h, respectively. The expression of antioxidant genes was measured in freshly isolated Treg and Tconv cells. Alxo, total antioxidant capacity (TAC) was measured in fresh peripheral blood mononuclear cells. ResultsAt all doses of H2O2, Treg cells accumulated more ROS and exhibited higher rates of death than their Tconv counterparts, p < 0.0001. Treg cells also expressed higher levels of antioxidant genes, including thioredoxin and thioredoxin reductase-1 (p < 0.0001), though without any differences between CCS patients and controls. Tconv cells from CCS patients were, on the other hand, more sensitive to oxidative stress ex vivo and expressed more thioredoxin reductase-1 than Tconv cells from controls, p < 0.05. Also, TAC levels were lower in patients, 0.97 vs 1.53 UAE/100 µg, p = 0.001. ConclusionTreg cells isolated from either CCS patients or healthy controls were all highly sensitive to oxidative stress ex vivo. There were however signs of oxidant-antioxidant imbalance in CCS patients and we thus assume that oxidative stress plays a role in the reduction of Treg cells in vivo.

scholarly journals Interplay between cytosolic disulfide reductase systems and the Nrf2/Keap1 pathway

2015 ◽  
Vol 43 (4) ◽  
pp. 632-638 ◽  
Author(s):  
Edward E. Schmidt
Keyword(s):  
Oxidative Stress ◽  
Thioredoxin Reductase ◽  
Reducing Power ◽  
Nuclear Factor ◽  
Independent Source ◽  
Nrf2 Pathway ◽  
Thioredoxin Reductase 1 ◽  
Disulfide Reductase ◽  
The Status ◽  
Thioredoxin 1

NADPH transfers reducing power from bioenergetic pathways to thioredoxin reductase-1 (TrxR1) and glutathione reductase (GR) to support essential reductive systems. Surprisingly, it was recently shown that mouse livers lacking both TrxR1 and GR (‘TR/GR-null’) can sustain redox (reduction-oxidation) homoeostasis using a previously unrecognized NADPH-independent source of reducing power fuelled by dietary methionine. The NADPH-dependent systems are robustly redundant in liver, such that disruption of either TrxR1 or GR alone does not cause oxidative stress. However, disruption of TrxR1 induces transcription factor Nrf2 (nuclear factor erythroid-derived 2-like-2) whereas disruption of GR does not. This suggests the Nrf2 pathway responds directly to the status of the thioredoxin-1 (Trx1) system. The proximal regulator of Nrf2 is Keap1 (Kelch-like ECH-associated protein-1), a cysteine (Cys)-rich protein that normally interacts transiently with Nrf2, targeting it for degradation. During oxidative stress, this interaction is stabilized, preventing degradation of newly synthesized Nrf2, thereby allowing Nrf2 accumulation. Within the Trx1 system, TrxR1 and peroxiredoxins (Prxs) contain some of the most reactive nucleophilic residues in the cell, making them likely targets for oxidants or electrophiles. We propose that Keap1 activity and therefore Nrf2 is regulated by interactions of Trx1 system enzymes with oxidants. In TR/GR-null livers, Nrf2 activity is further induced, revealing that TrxR-independent systems also repress Nrf2 and these might be induced by more extreme challenges.

scholarly journals Induction of Oxidative Stress Through Inhibition of Thioredoxin Reductase 1 Is an Effective Therapeutic Approach for Hepatocellular Carcinoma

Hepatology ◽  
2019 ◽  
Vol 69 (4) ◽  
pp. 1768-1786 ◽  
Author(s):  
Derek Lee ◽  
Iris Ming‐Jing Xu ◽  
David Kung‐Chun Chiu ◽  
Josef Leibold ◽  
Aki Pui‐Wah Tse ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Hepatocellular Carcinoma ◽  
Therapeutic Approach ◽  
Thioredoxin Reductase ◽  
Thioredoxin Reductase 1

scholarly journals miR526b and miR655 Induce Oxidative Stress in Breast Cancer

2019 ◽  
Vol 20 (16) ◽  
pp. 4039 ◽  
Author(s):  
Bonita Shin ◽  
Riley Feser ◽  
Braydon Nault ◽  
Stephanie Hunter ◽  
Sujit Maiti ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Oxidative Stress ◽  
Cancer Progression ◽  
Thioredoxin Reductase ◽  
Bioinformatic Analysis ◽  
Conditioned Media ◽  
Mcf7 Cells ◽  
Thioredoxin Reductase 1 ◽  
Cancer Phenotypes

In eukaryotes, overproduction of reactive oxygen species (ROS) causes oxidative stress, which contributes to chronic inflammation and cancer. MicroRNAs (miRNAs) are small, endogenously produced RNAs that play a major role in cancer progression. We established that overexpression of miR526b/miR655 promotes aggressive breast cancer phenotypes. Here, we investigated the roles of miR526b/miR655 in oxidative stress in breast cancer using in vitro and in silico assays. miRNA-overexpression in MCF7 cells directly enhances ROS and superoxide (SO) production, detected with fluorescence assays. We found that cell-free conditioned media contain extracellular miR526b/miR655 and treatment with these miRNA-conditioned media causes overproduction of ROS/SO in MCF7 and primary cells (HUVECs). Thioredoxin Reductase 1 (TXNRD1) is an oxidoreductase that maintains ROS/SO concentration. Overexpression of TXNRD1 is associated with breast cancer progression. We observed that miR526b/miR655 overexpression upregulates TXNRD1 expression in MCF7 cells, and treatment with miRNA-conditioned media upregulates TXNRD1 in both MCF7 and HUVECs. Bioinformatic analysis identifies two negative regulators of TXNRD1, TCF21 and PBRM1, as direct targets of miR526b/miR655. We validated that TCF21 and PBRM1 were significantly downregulated with miRNA upregulation, establishing a link between miR526b/miR655 and TXNRD1. Finally, treatments with oxidative stress inducers such as H2O2 or miRNA-conditioned media showed an upregulation of miR526b/miR655 expression in MCF7 cells, indicating that oxidative stress also induces miRNA overexpression. This study establishes the dynamic functions of miR526b/miR655 in oxidative stress induction in breast cancer.

Sign in / Sign up

Export Citation Format

Share Document