Search results for: thioredoxin

Authors: Sunil Mittal, Sukhpreet Singh, Hardeep Kaur

Abstract:

The affinity of thiol group with heavy metals is a well-established phenomenon. The present investigation has been focused on electrochemical response of cysteine and thioredoxin against arsenite (As III) on indium tin oxide (ITO) electrodes. It was observed that both the compounds produce distinct response in free and immobilised form at the electrode. The SEM, FTIR, and impedance studies of the modified electrode were conducted for characterization. Various parameters were optimized to achieve As (III) effect on the reduction potential of the compounds. Cyclic voltammetry and linear sweep voltammetry were employed as the analysis techniques. The optimum response was observed at neutral pH in both the cases, at optimum concentration of 2 mM and 4.27 µM for cysteine and thioredoxin respectively. It was observed that presence of As (III) increases the reduction current of both the moieties. The linear range of detection for As (III) with cysteine was from 1 to 10 mg L⁻¹ with detection limit of 0.8 mg L⁻¹. The thioredoxin was found more sensitive to As (III) and displayed a linear range from 0.1 to 1 mg L⁻¹ with detection limit of 10 µg L⁻¹.

Keywords: arsenite, cyclic voltammetry, cysteine, thioredoxin

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Authors: Narin Salehiyan

Abstract:

The three iodothyronine selenodeiodinases catalyze the start and end of thyroid hormone impacts in vertebrates. Auxiliary examinations of these proteins have been prevented by their indispensably film nature and the wasteful eukaryotic-specific pathway for selenoprotein blend. Hydrophobic cluster examination utilized in combination with Position-specific Iterated Impact uncovers that their extramembrane parcel has a place to the thioredoxin-fold superfamily for which test structure data exists. Besides, a expansive deiodinase locale imbedded within the thioredoxin overlay offers solid similitudes with the dynamic location of iduronidase, a part of the clan GH-A-fold of glycoside hydrolases. This show can clarify a number of comes about from past mutagenesis examinations and grants unused irrefutable experiences into the auxiliary and utilitarian properties of these proteins.

Keywords: glycoside, hydrolase, GH-A-like structure, catalyze

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Authors: Charalampos N. Bompas, Eleni Poulou-Sidiropoulou, Martina Samiotaki, Alexios Vlamis-Gardikas

Abstract:

Ιn all living organisms, antioxidant defenses are orchestrated by the thioredoxin (Trx) and glutaredoxin (Grx) systems. The Trx system of Escherichia coli (E. coli) is comprised of Trx1 and Trx2, both reduced by thioredoxin reductase (TrxR). The Grx system consists of four Grxs (Grx1, Grx2, Grx3, and Grx4), all reduced by glutathione (GSH) except for Grx4, which is reduced by TrxR. Under normal conditions, the GSH reductase of the Grx system keeps GSH at its reduced state. NADPH+ provides the electrons for all reductions in the Trx and Grx systems. Although the role of the E. coli Trx system is widely known, the function of the Grx system reflects the main property of Grx1, which is the reduction of ribonucleotide reductase Ia (RRIa). E. coli Grx3 (encoded by grxC) may also reduce RRIa in vitro but with slow kinetics. The molecule may account for up to 0.4% of total soluble protein and has been the subject of extensive structural studies. Its biological function, however, remains unknown. Herein, affinity chromatography with monothiol Grx3 serving as bait was used to detect the interactions of Grx3 with other proteins. Different types of interactions were identified (covalent, weak, and strong non-covalent) that suggested novel functions for Grx3. In silico approaches were employed to validate selected interactions. In addition, total protein extracts from the null mutant for grxC and the wild-type strain were compared. The overall findings suggest that Grx3 is involved in various metabolic processes, protein synthesis, and stress responses, expanding the recognized functions of Grx3 beyond the possible reduction of RRIa.

Keywords: escherichia coli, glutaredoxin 3, interactome, thiol-disulfide oxidoreductase

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Authors: Chao Wu

Abstract:

Thioredoxin reductase 2 is a mitochondrial enzyme that belongs to the cellular defense against oxidative stress. We deleted mitochondrial Txnrd2 in a KrasG12D-driven pancreatic tumor model. Despite an initial increase in precursor lesions, tumor incidence decreased significantly. We isolated cancer cell lines from these genetically engineered mice and observed an impaired proliferation and colony formation. Reactive Oxygen Species, as determined by DCF fluorescence, were increased. We detected a higher mitochondrial copy number in Txnrd2-deficient cells (KTP). However, measurement of mitochondrial bioenergetics showed no impairment of mitochondrial function and comparable O₂-consumption and extracellular acidification rates. In addition, the mitochondrial complex composition was affected in Txnrd2 deleted cell lines. To gain better insight into the role of Txnrd2, we deleted Txnrd2 in clones from parental KrasG12D cell lines using Crispr/Cas9 technology. The deletion was confirmed by western blot and activity assay. Interestingly, and in line with previous RNA expression analysis, we saw changes in EMT markers in Txnrd2 deleted cell lines and control cell lines. This might help us explain the reduced tumor incidence in KrasG12D; Txnrd2∆panc mice.

Keywords: PDAC, TXNRD2, epithelial-to-mesenchymal-transition, ROS

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Authors: Zi-Han Li, Lu Fang, Liang Wu, Dong-Yuan Chang, Manyuan Dong, Liang Ji, Qi Zhang, Ming-Hui Zhao, Sydney C. W. Tang, Lemin Zheng, Min Chen

Abstract:

Uncoupling of mitochondrial respiration by chemical uncouplers has proven effective in ameliorating obesity, insulin resistance, and hyperglycemia, which were risk factors for diabetic nephropathy (DN). Recently, we found that ANXA1 could improve mitochondrial function to mitigate DN progression. However, the underlying mechanism is not fully clear yet. Here, we identified uncoupling protein 1 (UCP1), an inner membrane protein of mitochondria, as a key to mitochondrial homeostasis improved by ANXA1. Specifically, ANXA1 attenuated mitochondrial dysfunction via appropriately upregulating UCP1 by stabilizing its transcription factor GATA binding protein 3 (GATA3) by combining it with thioredoxin. Moreover, specific overexpression of UCP1 in the renal cortex rescued renal injuries in diabetic Anxa1-KO mice. UCP1 deletion aggravated renal injuries in HFD/STZ-induced diabetic mice. Mechanistically, UCP1 reduced mitochondrial fission through the aristaless-related homeobox (ARX)/cardiolipin synthase 1 (CRLS1) pathway. Therapeutically, CL316243, a UCP1 agonist, could attenuate established DN in db/db mice. This work established an alternative principle to harness the power of uncouplers for the treatment of DN.

Keywords: diabetic nephropathy, uncoupling protein 1, mitochondrial homeostasis, cardiolipin metabolism

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Authors: Zi-Han Li, Lu Fang, Liang Wu, Dong-Yuan Chang, Manyuan Dong, Liang Ji, Qi Zhang, Ming-Hui Zhao, Sydney C.W. Tang, Lemin Zheng, Min Chen

Abstract:

Uncoupling of mitochondrial respiration by chemical uncouplers has proven effective in ameliorating obesity, insulin resistance, and hyperglycemia, which were risk factors for diabetic nephropathy (DN). Recently, it was found that annexin A1(ANXA1) could improve mitochondrial function to mitigate DN progression. However, the underlying mechanism is not fully clear yet. Here, it was identified that uncoupling protein 1 (UCP1), an inner membrane protein of mitochondria, as a key to mitochondrial homeostasis improved by ANXA1. Specifically, ANXA1 attenuated mitochondrial dysfunction via appropriately upregulating UCP1 by stabilizing its transcription factor GATA binding protein 3 (GATA3) through combining with thioredoxin. Moreover, specific overexpression of UCP1 in renal cortex rescued renal injuries in diabetic Anxa1-KO mice. UCP1 deletion aggravated renal injuries in HFD/STZ-induced diabetic mice. Mechanistically, UCP1 reduced mitochondrial fission through the aristaless-related homeobox (ARX)/cardiolipin synthase 1 (CRLS1) pathway. Therapeutically, CL316243, a UCP1 agonist, could attenuate established DN in db/db mice. This work established a novel principle to harness the power of uncouplers for the treatment of DN.

Keywords: diabetic nephropathy, uncoupling protein 1, mitochondrial homeostasis, cardiolipin metabolism

Procedia PDF Downloads 43

Authors: Eleni Poulou-Sidiropoulou, Charalampos N. Bompas, Martina Samiotaki, Alexios Vlamis-Gardikas

Abstract:

The glutaredoxin (Grx) and thioredoxin (Trx) systems keep the intracellular environment reduced in almost all organisms. In Escherichia coli (E. coli), the Grx system relies on NADPH+ to reduce GSH reductase (GR), the latter reducing oxidized diglutathione to glutathione (GSH) which in turn reduces cytosolic Grxs, the electron donors for different intracellular substrates. In the Trx system, GR and GSH are replaced by Trx reductase (TrxR). Three of the Grxs of E. coli (Grx1, 2, 3) are reduced by GSH, while Grx4 is likely reduced by TrxR. Trx1 and Grx1 from E. coli may reduce ribonucleotide reductase Ia to ensure a constant supply of deoxyribonucleotides for the synthesis of DNA. The role of the other three Grxs is relatively unknown, especially for Grx2 that may amount up to 1 % of total cellular protein in the stationary phase of growth. The protein is known as a potent antioxidant, but no specific functions have been attributed to it. Herein, affinity chromatography of cellular extracts on immobilized Grx2, followed by MS analysis of the resulting eluates, was employed to identify protein ligands that could provide insights into the biological role of Grx2. Ionic, strong non-covalent, and covalent (disulfide) interactions with relevant proteins were detected. As a means of verification, the identified ligands were subjected to in silico docking with monothiol Grx2. In other experiments, protein extracts from E. coli cells lacking the gene for Grx2 (grxB) were compared to those of wild type. Taken together, the two approaches suggest that Grx2 is involved in protein synthesis, nucleotide metabolism, DNA damage repair, stress responses, and various metabolic processes. Grx2 appears as a versatile protein that may participate in a wide range of biological pathways beyond its known general antioxidant function.

Keywords: Escherichia coli, glutaredoxin 2, interactome, thiol-disulfide oxidoreductase

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