Binding of aflatoxins to the 20S proteasome: effects on enzyme functionality and implications for oxidative stress and apoptosis

Anemia is common among young children infected with Plasmodium falciparum (Pf) and severe malarial anemia (SMA) is a major cause of their mortality. Two major mechanisms cause malarial anemia: hemolysis of uninfected as well as infected erythrocytes and insufficient erythropoiesis. In a longitudinal birth cohort in Mali, we commonly observed marked hemoglobin reductions during Pf infections with a small proportion that progressed to SMA. We sought biomarkers of these processes using quantitative proteomic analysis on plasma samples from 9 P. falciparum-infected children, comparing those with reduced hemoglobin (with or without SMA) versus those with stable hemoglobin. We identified higher plasma levels of circulating 20S proteasome and lower IGF-1 levels in children with reduced hemoglobin. We confirmed these findings in independent ELISA-based validation studies of subsets of children from the same cohort (20S proteasome, N=71; IGF-1, N=78). We speculate that circulating 20S proteasome plays a role in digesting erythrocyte membrane proteins modified by oxidative stress, resulting in hemolysis, while decreased IGF-1, a critical factor for erythroid maturation, might contribute to insufficient erythropoiesis. Quantitative plasma proteomics identified soluble mediators that may contribute to the major mechanisms underlying malarial anemia.

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Measuring 20S Proteasome and Immunoproteasome Activities in Oxidative Stress

Free Radical Biology and Medicine ◽

10.1016/j.freeradbiomed.2016.10.235 ◽

2016 ◽

Vol 100 ◽

pp. S94

Author(s):

Vicent Bonet-Costa ◽

Kelvin J.A. Davies

Keyword(s):

Oxidative Stress ◽

20S Proteasome

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The immunoproteasome, the 20S proteasome and the PA28αβ proteasome regulator are oxidative-stress-adaptive proteolytic complexes

Biochemical Journal ◽

10.1042/bj20100878 ◽

2010 ◽

Vol 432 (3) ◽

pp. 585-595 ◽

Cited By ~ 202

Author(s):

Andrew M. Pickering ◽

Alison L. Koop ◽

Cheryl Y. Teoh ◽

Gennady Ermak ◽

Tilman Grune ◽

...

Keyword(s):

Oxidative Stress ◽

Dna Replication ◽

De Novo ◽

Physical Activation ◽

20S Proteasome ◽

Oxidized Proteins ◽

Pre Treatment ◽

Sirna Knockdown ◽

Rna Knockdown ◽

Interfering Rna

Oxidized cytoplasmic and nuclear proteins are normally degraded by the proteasome, but accumulate with age and disease. We demonstrate the importance of various forms of the proteasome during transient (reversible) adaptation (hormesis), to oxidative stress in murine embryonic fibroblasts. Adaptation was achieved by ‘pre-treatment’ with very low concentrations of H2O2, and tested by measuring inducible resistance to a subsequent much higher ‘challenge’ dose of H2O2. Following an initial direct physical activation of pre-existing proteasomes, the 20S proteasome, immunoproteasome and PA28αβ regulator all exhibited substantially increased de novo synthesis during adaptation over 24 h. Cellular capacity to degrade oxidatively damaged proteins increased with 20S proteasome, immunoproteasome and PA28αβ synthesis, and was mostly blocked by the 20S proteasome, immunoproteasome and PA28 siRNA (short interfering RNA) knockdown treatments. Additionally, PA28αβ-knockout mutants achieved only half of the H2O2-induced adaptive increase in proteolytic capacity of wild-type controls. Direct comparison of purified 20S proteasome and immunoproteasome demonstrated that the immunoproteasome can selectively degrade oxidized proteins. Cell proliferation and DNA replication both decreased, and oxidized proteins accumulated, during high H2O2 challenge, but prior H2O2 adaptation was protective. Importantly, siRNA knockdown of the 20S proteasome, immunoproteasome or PA28αβ regulator blocked 50–100% of these adaptive increases in cell division and DNA replication, and immunoproteasome knockdown largely abolished protection against protein oxidation.

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The Pep4p vacuolar proteinase contributes to the turnover of oxidized proteins but PEP4 overexpression is not sufficient to increase chronological lifespan in Saccharomyces cerevisiae

Microbiology ◽

10.1099/mic.0.29040-0 ◽

2006 ◽

Vol 152 (12) ◽

pp. 3595-3605 ◽

Cited By ~ 41

Author(s):

Marta Marques ◽

Dominik Mojzita ◽

Maria A. Amorim ◽

Teresa Almeida ◽

Stefan Hohmann ◽

...

Keyword(s):

Oxidative Stress ◽

Gene Expression ◽

Saccharomyces Cerevisiae ◽

Protein Turnover ◽

Yeast Cells ◽

Global Changes ◽

20S Proteasome ◽

Oxidized Proteins ◽

Genes Encoding ◽

Induced Genes

Turnover of damaged molecules is considered to play a key role in housekeeping of cells exposed to oxidative stress, and during the progress of ageing. In this work, global changes in the transcriptome were analysed during recovery of yeast cells after H2O2 stress. Regarding induced genes, those associated with protein fate were the most significantly over-represented. In addition to genes encoding subunits of the 20S proteasome, genes related to vacuolar proteolysis (PEP4 and LAP4), protein sorting into the vacuole, and vacuolar fusion were found to be induced. The upregulation of PEP4 gene expression was associated with an increase in Pep4p activity. The induction of genes related to proteolysis was correlated with an increased protein turnover after H2O2-induced oxidation. Furthermore, protein degradation and the removal of oxidized proteins decreased in Pep4p-deficient cells. Pep4p activity also increased during chronological ageing, and cells lacking Pep4p displayed a shortened lifespan associated with higher levels of carbonylated proteins. PEP4 overexpression prevented the accumulation of oxidized proteins, but did not increase lifespan. These results indicate that Pep4p is important for protein turnover after oxidative damage; however, increased removal of oxidized proteins is not sufficient to enhance lifespan.

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20S Proteasome Beta 5 Subunit is Crucial for Sexually Divergent Adaptive Homeostasis Responses to Oxidative Stress in D. melanogaster

Free Radical Biology and Medicine ◽

10.1016/j.freeradbiomed.2017.10.081 ◽

2017 ◽

Vol 112 ◽

pp. 58-59

Author(s):

Christina Sisliyan ◽

Sarah Wong ◽

Laura Corrales-Diaz Pomatto ◽

John Tower ◽

Kelvin J.A. Davies

Keyword(s):

Oxidative Stress ◽

20S Proteasome

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Redox regulation of diaphragm proteolysis during mechanical ventilation

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00044.2008 ◽

2008 ◽

Vol 294 (5) ◽

pp. R1608-R1617 ◽

Cited By ~ 54

Author(s):

J. M. McClung ◽

M. A. Whidden ◽

A. N. Kavazis ◽

D. J. Falk ◽

K. C. DeRuisseau ◽

...

Keyword(s):

Oxidative Stress ◽

Mechanical Ventilation ◽

Protein Concentration ◽

Redox Regulation ◽

20S Proteasome ◽

Substrate Availability ◽

Sprague Dawley ◽

Α Subunit ◽

Sprague Dawley Rats ◽

Critical Site

Prevention of oxidative stress via antioxidants attenuates diaphragm myofiber atrophy associated with mechanical ventilation (MV). However, the specific redox-sensitive mechanisms responsible for this remain unknown. We tested the hypothesis that regulation of skeletal muscle proteolytic activity is a critical site of redox action during MV. Sprague-Dawley rats were assigned to five experimental groups: 1) control, 2) 6 h of MV, 3) 6 h of MV with infusion of the antioxidant Trolox, 4) 18 h of MV, and 5) 18 h of MV with Trolox. Trolox did not attenuate MV-induced increases in diaphragmatic levels of ubiquitin-protein conjugation, polyubiquitin mRNA, and gene expression of proteasomal subunits (20S proteasome α-subunit 7, 14-kDa E2, and proteasome-activating complex PA28). However, Trolox reduced both chymotrypsin-like and peptidylglutamyl peptide hydrolyzing (PGPH)-like 20S proteasome activities in the diaphragm after 18 h of MV. In addition, Trolox rescued diaphragm myofilament protein concentration (μg/mg muscle) and the percentage of easily releasable myofilament protein independent of alterations in ribosomal capacity for protein synthesis. In summary, these data are consistent with the notion that the protective effect of antioxidants on the diaphragm during MV is due, at least in part, to decreasing myofilament protein substrate availability to the proteasome.

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MtsABC Is Important for Manganese and Iron Transport, Oxidative Stress Resistance, and Virulence of Streptococcus pyogenes

Infection and Immunity ◽

10.1128/iai.71.5.2656-2664.2003 ◽

2003 ◽

Vol 71 (5) ◽

pp. 2656-2664 ◽

Cited By ~ 124

Author(s):

Robert Janulczyk ◽

Susanna Ricci ◽

Lars Björck

Keyword(s):

Oxidative Stress ◽

Streptococcus Pyogenes ◽

Animal Experiments ◽

Dependent Manner ◽

Iron And Zinc ◽

Enzyme Functionality ◽

Dose Dependent ◽

Pronounced Reduction

ABSTRACT MtsABC is a Streptococcus pyogenes ABC transporter which was previously shown to be involved in iron and zinc accumulation. In this study, we showed that an mtsABC mutant has impaired growth, particularly in a metal-depleted medium and an aerobic environment. In metal-depleted medium, growth was restored by the addition of 10 μM MnCl2, whereas other metals had modest or no effect. A characterization of metal radioisotope accumulation showed that manganese competes with iron accumulation in a dose-dependent manner. Conversely, iron competes with manganese accumulation but to a lesser extent. The mutant showed a pronounced reduction (>90%) of 54Mn accumulation, showing that MtsABC is also involved in Mn transport. Using paraquat and hydrogen peroxide to induce oxidative stress, we show that the mutant has an increased susceptibility to reactive oxygen species. Moreover, activity of the manganese-cofactored superoxide dismutase in the mutant is reduced, probably as a consequence of reduced intracellular availability of manganese. The enzyme functionality was restored by manganese supplementation during growth. The mutant was also attenuated in virulence, as shown in animal experiments. These results emphasize the role of MtsABC and trace metals, especially manganese, for S. pyogenes growth, susceptibility to oxidative stress, and virulence.

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Reduced Proteasome Activity and Enhanced Autophagy in Blood Cells of Psoriatic Patients

International Journal of Molecular Sciences ◽

10.3390/ijms21207608 ◽

2020 ◽

Vol 21 (20) ◽

pp. 7608 ◽

Cited By ~ 1

Author(s):

Piotr Karabowicz ◽

Adam Wroński ◽

Halina Ostrowska ◽

Georg Waeg ◽

Neven Zarkovic ◽

...

Keyword(s):

Oxidative Stress ◽

Blood Cells ◽

Protein Adducts ◽

Akt Pathway ◽

20S Proteasome ◽

Carbonyl Groups ◽

Autophagy Flux ◽

Cell Components ◽

Oxidatively Modified ◽

The Relationship

Psoriasis is a skin disease that is accompanied by oxidative stress resulting in modification of cell components, including proteins. Therefore, we investigated the relationship between the intensity of oxidative stress and the expression and activity of the proteasomal system as well as autophagy, responsible for the degradation of oxidatively modified proteins in the blood cells of patients with psoriasis. Our results showed that the caspase-like, trypsin-like, and chymotrypsin-like activity of the 20S proteasome in lymphocytes, erythrocytes, and granulocytes was lower, while the expression of constitutive proteasome and immunoproteasome subunits in lymphocytes was increased cells of psoriatic patients compared to healthy subjects. Conversely, the expression of constitutive subunits in erythrocytes, and both constitutive and immunoproteasomal subunits in granulocytes were reduced. However, a significant increase in the autophagy flux (assessed using LC3BII/LC3BI ratio) independent of the AKT pathway was observed. The levels of 4-HNE, 4-HNE-protein adducts, and proteins carbonyl groups were significantly higher in the blood cells of psoriatic patients. The decreased activity of the 20S proteasome together with the increased autophagy and the significantly increased level of proteins carbonyl groups and 4-HNE-protein adducts indicate a proteostatic imbalance in the blood cells of patients with psoriasis.

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