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Objectives: A decline in mitochondrial function and increased susceptibility to oxidative stress is a hallmark of ageing. Exercise endogenously generates reactive oxygen species (ROS) in skeletal muscle and promotes mitochondrial remodelling resulting in improved mitochondrial function. It is unclear how exercise induced redox signalling results in alterations in mitochondrial dynamics and morphology. Methods: In this study, a Caenorhabditis elegans model of exercise and ageing was used to determine the mechanistic role of Peroxiredoxin 2 (PRDX-2) in regulating mitochondrial morphology. Mitochondrial morphology was analysed using transgenic reporter strains and transmission electron microscopy, complimented with the analysis of the effects of ageing and exercise on physiological activity. Results: The redox state of PRDX-2 was altered with exercise and ageing, hyperoxidised peroxiredoxins were detected in old worms along with basally elevated intracellular ROS. Exercise generated intracellular ROS and rapid mitochondrial remodelling, which was disrupted with age. The exercise intervention promoted mitochondrial ER contact sites (MERCS) assembly and increased DAF-16/FOXO nuclear localisation. The prdx-2 mutant strain had a disrupted mitochondrial network as evidenced by increased mitochondrial fragmentation. In the prdx-2 mutant strain, exercise did not activate DAF-16/FOXO, mitophagy or increase MERCS assembly. The results demonstrate that exercise generated ROS increased DAF-16/FOXO transcription factor nuclear localisation required for activation of mitochondrial fusion events that were blunted with age. Conclusions: The data demonstrate the critical role of PRDX-2 in orchestrating mitochondrial remodelling in response to a physiological stress by regulating redox dependent DAF-16/FOXO nuclear localisation.

Abstract Background Intraventricular hemorrhage (IVH) and associated hydrocephalus are significant complications of intracerebral and subarachnoid hemorrhage. Despite proximity to IVH, the immune cell response at the choroid plexus (ChP) has been relatively understudied. This study employs CX3CR-1GFP mice, which marks multiple immune cell populations, and immunohistochemistry to outline that response. Methods This study had four parts all examining male adult CX3CR-1GFP mice. Part 1 examined naïve mice. In part 2, mice received an injection 30 µl of autologous blood into right ventricle and were euthanized at 24 h. In part 3, mice underwent intraventricular injection of saline, iron or peroxiredoxin 2 (Prx-2) and were euthanized at 24 h. In part 4, mice received intraventricular iron injection and were treated with either control or clodronate liposomes and were euthanized at 24 h. All mice underwent magnetic resonance imaging to quantify ventricular volume. The ChP immune cell response was examined by combining analysis of GFP(+) immune cells and immunofluorescence staining. Results IVH and intraventricular iron or Prx-2 injection in CX3CR-1GFP mice all induced ventriculomegaly and activation of ChP immune cells. There were very marked increases in the numbers of ChP epiplexus macrophages, T lymphocytes and neutrophils. Co-injection of clodronate liposomes with iron reduced the ventriculomegaly which was associated with fewer epiplexus and stromal macrophages but not reduced T lymphocytes and neutrophils. Conclusion There is a marked immune cell response at the ChP in IVH involving epiplexus cells, T lymphocytes and neutrophils. The blood components iron and Prx-2 may play a role in eliciting that response. Reduction of ChP macrophages with clodronate liposomes reduced iron-induced ventriculomegaly suggesting that ChP macrophages may be a promising therapeutic target for managing IVH-induced hydrocephalus.

Catalase (CAT), glutathione peroxidase (GPx), and peroxiredoxin 2 (Prx2) can counteract the deleterious effects of oxidative stress (OS). Their binding to the red blood cell (RBC) membrane has been reported in non-immune hemolytic anemias (NIHAs). Our aim was to evaluate the relationships between CAT, GPx, and Prx2, focusing on their role at the RBC membrane, in hereditary spherocytosis (HS), sickle cell disease (SCD), β-thalassemia (β-thal), and healthy individuals. The studies were performed in plasma and in the RBC cytosol and membrane, evaluating OS biomarkers and the enzymatic activities and/or the amounts of CAT, GPx, and Prx2. The binding of the enzymes to the membrane appears to be the primary protective mechanism against oxidative membrane injuries in healthy RBCs. In HS (unsplenectomized) and β-thal, translocation from the cytosol to the membrane of CAT and Prx2, respectively, was observed, probably to counteract lipid peroxidation. RBCs from splenectomized HS patients showed the highest membrane-bound hemoglobin, CAT, and GPx amounts in the membrane. SCD patients presented the lowest amount of enzyme linkage, possibly due to structural changes induced by sickle hemoglobin. The OS-induced changes and antioxidant response were different between the studied NIHAs and may contribute to the different clinical patterns in these patients. [ABSTRACT FROM AUTHOR]

Microenvironment and transcriptional plasticity generate subpopulations within the tumor, and the use of BRAF inhibitors (BRAFis) contributes to the rise and selection of resistant clones. We stochastically isolated subpopulations (C1, C2, and C3) from naïve melanoma and found that the clones demonstrated distinct morphology, phenotypic, and functional profiles: C1 was less proliferative, more migratory and invasive, less sensitive to BRAFis, less dependent on OXPHOS, more sensitive to oxidative stress, and less pigmented; C2 was more proliferative, less migratory and invasive, more sensitive to BRAFis, less sensitive to oxidative stress, and more pigmented; and C3 was less proliferative, more migratory and invasive, less sensitive to BRAFis, more dependent on OXPHOS, more sensitive to oxidative stress, and more pigmented. Hydrogen peroxide plays a central role in oxidative stress and cell signaling, and PRDXs are one of its main consumers. The intrinsically resistant C1 and C3 clones had lower MITF, PGC-1α, and PRDX1 expression, while C1 had higher AXL and decreased pigmentation markers, linking PRDX1 to clonal heterogeneity and resistance. PRDX2 is depleted in acquired BRAFi-resistant cells and acts as a redox sensor. Our results illustrate that decreased pigmentation markers are related to therapy resistance and decreased antioxidant defense. [ABSTRACT FROM AUTHOR]

Background: Intraventricular hemorrhage (IVH) and associated hydrocephalus are significant complications of intracerebral and subarachnoid hemorrhage. Despite proximity to IVH, the immune cell response at the choroid plexus (ChP) has been relatively understudied. This study employs CX3CR-1GFP mice, which marks multiple immune cell populations, and immunohistochemistry to outline that response. Methods: This study had four parts all examining male adult CX3CR-1GFP mice. Part 1 examined naïve mice. In part 2, mice received an injection 30 µl of autologous blood into right ventricle and were euthanized at 24 h. In part 3, mice underwent intraventricular injection of saline, iron or peroxiredoxin 2 (Prx-2) and were euthanized at 24 h. In part 4, mice received intraventricular iron injection and were treated with either control or clodronate liposomes and were euthanized at 24 h. All mice underwent magnetic resonance imaging to quantify ventricular volume. The ChP immune cell response was examined by combining analysis of GFP(+) immune cells and immunofluorescence staining. Results: IVH and intraventricular iron or Prx-2 injection in CX3CR-1GFP mice all induced ventriculomegaly and activation of ChP immune cells. There were very marked increases in the numbers of ChP epiplexus macrophages, T lymphocytes and neutrophils. Co-injection of clodronate liposomes with iron reduced the ventriculomegaly which was associated with fewer epiplexus and stromal macrophages but not reduced T lymphocytes and neutrophils. Conclusion: There is a marked immune cell response at the ChP in IVH involving epiplexus cells, T lymphocytes and neutrophils. The blood components iron and Prx-2 may play a role in eliciting that response. Reduction of ChP macrophages with clodronate liposomes reduced iron-induced ventriculomegaly suggesting that ChP macrophages may be a promising therapeutic target for managing IVH-induced hydrocephalus. [ABSTRACT FROM AUTHOR]

Background: Peroxiredoxin 2 (Prx2), an intracellular protein that regulates redox reactions, released from red blood cells is involved in inflammatory brain injury after intracerebral hemorrhage (ICH). Toll‐like receptor 4 (TLR4) may be crucial in this process. This study investigated the role of the Prx2‐TLR4 inflammatory axis in brain injury following experimental ICH in mice. Methods: First, C57BL/6 mice received an intracaudate injection of autologous arterial blood or saline and their brains were harvested on day 1 to measure Prx2 levels. Second, mice received an intracaudate injection of either recombinant mouse Prx2 or saline. Third, the mice were co‐injected with autologous arterial blood and conoidin A, a Prx2 inhibitor, or vehicle. Fourth, the mice received a Prx2 injection and were treated with TAK‐242, a TLR4 antagonist, or saline (intraperitoneally). Behavioral tests, magnetic resonance imaging, western blot, immunohistochemistry/immunofluorescence staining, and RNA sequencing (RNA‐seq) were performed. Results: Brain Prx2 levels were elevated after autologous arterial blood injection. Intracaudate injection of Prx2 caused brain swelling, microglial activation, neutrophil infiltration, neuronal death, and neurological deficits. Co‐injection of conoidin A attenuated autologous arterial blood‐induced brain injury. TLR4 was expressed on the surface of microglia/macrophages and neutrophils and participated in Prx2‐induced inflammation. TAK‐242 treatment attenuated Prx2‐induced inflammation and neurological deficits. Conclusions: Prx2 can cause brain injury following ICH through the TLR4 pathway, revealing the Prx2‐TLR4 inflammatory axis as a potential therapeutic target. [ABSTRACT FROM AUTHOR]

Hepatocellular carcinoma (HCC), a common malignancy worldwide, still lacks effective clinical treatment. The study aimed to investigate the oncogenes that affect the progression of HCC and their possible mechanisms. In our study, we initially confirmed a higher level of PRDX2 in the bile of HCC patients compared to those with choledocholithiasis by 2-DE, LC-MS, and ELISA. Subsequently, we demonstrated the high expression of peroxiredoxin 2 (PRDX2) in HCC based on the TCGA database and clinical sample analysis. Furthermore, PRDX2 overexpression enhanced the viability of HCC cells. And PRDX2 silencing induced senescence of HCC cells. In vivo, knockdown of PRDX2 significantly reduced the weight of xenograft tumors. PRDX2 also was found to activate the Wnt/β-catenin pathway by inducing β-catenin nuclear translocation. Consequently, we proved that silencing PRDX2 could inhibit proliferation and Wnt/β-catenin pathway while promoting senescence in HCC cells. [ABSTRACT FROM AUTHOR]

Abstract We investigated the proteins of erythrocytes from stem cell transplantation patients and found decreased expression of band3 and C‐terminal‐truncated peroxiredoxin 2 (PRDX2) only during severe graft‐versus‐host disease (GVHD), using time‐of‐flight mass spectrometry (TOF‐MS) analysis and Western blotting. During the same period, PRDX2 dimerization and calpain‐1 activation were observed, indicating severe oxidative stress. We also found a putative cleavage site for calpain‐1 in the C‐terminal‐truncated site of PRDX2. Decreased band3 expression impairs the plasticity and stability of erythrocytes, and C‐terminal‐truncated PRDX2 induces irreversible dysfunction of antioxidant activity. These effects may exacerbate microcirculation disorders and the progression of organ dysfunction.

Both monocyte-derived macrophages (MDMs) and brain resident microglia participate in hematoma resolution after intracerebral hemorrhage (ICH). Here, we utilized a transgenic mouse line with enhanced green fluorescent protein (EGFP) labeled microglia (Tmem119-EGFP mice) combined with a F4/80 immunohistochemistry (a pan-macrophage marker) to visualize changes in MDMs and microglia after ICH. A murine model of ICH was used in which autologous blood was stereotactically injected into the right basal ganglia. The autologous blood was co-injected with CD47 blocking antibodies to enhance phagocytosis or clodronate liposomes for phagocyte depletion. In addition, Tmem119-EGFP mice were injected with the blood components peroxiredoxin 2 (Prx2) or thrombin. MDMs entered the brain and formed a peri-hematoma cell layer by day 3 after ICH and giant phagocytes engulfed red blood cells were found. CD47 blocking antibody increased the number of MDMs around and inside the hematoma and extended MDM phagocytic activity to day 7. Both MDMs and microglia could be diminished by clodronate liposomes. Intracerebral injection of Prx2 but not thrombin attracted MDMs into brain parenchyma. In conclusion, MDMs play an important role in phagocytosis after ICH which can be enhanced by CD47 blocking antibody, suggesting the modulation of MDMs after ICH could be a future therapeutic target. [ABSTRACT FROM AUTHOR]

Catalase (CAT), glutathione peroxidase (GPx), and peroxiredoxin 2 (Prx2) can counteract the deleterious effects of oxidative stress (OS). Their binding to the red blood cell (RBC) membrane has been reported in non-immune hemolytic anemias (NIHAs). Our aim was to evaluate the relationships between CAT, GPx, and Prx2, focusing on their role at the RBC membrane, in hereditary spherocytosis (HS), sickle cell disease (SCD), β-thalassemia (β-thal), and healthy individuals. The studies were performed in plasma and in the RBC cytosol and membrane, evaluating OS biomarkers and the enzymatic activities and/or the amounts of CAT, GPx, and Prx2. The binding of the enzymes to the membrane appears to be the primary protective mechanism against oxidative membrane injuries in healthy RBCs. In HS (unsplenectomized) and β-thal, translocation from the cytosol to the membrane of CAT and Prx2, respectively, was observed, probably to counteract lipid peroxidation. RBCs from splenectomized HS patients showed the highest membrane-bound hemoglobin, CAT, and GPx amounts in the membrane. SCD patients presented the lowest amount of enzyme linkage, possibly due to structural changes induced by sickle hemoglobin. The OS-induced changes and antioxidant response were different between the studied NIHAs and may contribute to the different clinical patterns in these patients.

Microenvironment and transcriptional plasticity generate subpopulations within the tumor, and the use of BRAF inhibitors (BRAFis) contributes to the rise and selection of resistant clones. We stochastically isolated subpopulations (C1, C2, and C3) from naïve melanoma and found that the clones demonstrated distinct morphology, phenotypic, and functional profiles: C1 was less proliferative, more migratory and invasive, less sensitive to BRAFis, less dependent on OXPHOS, more sensitive to oxidative stress, and less pigmented; C2 was more proliferative, less migratory and invasive, more sensitive to BRAFis, less sensitive to oxidative stress, and more pigmented; and C3 was less proliferative, more migratory and invasive, less sensitive to BRAFis, more dependent on OXPHOS, more sensitive to oxidative stress, and more pigmented. Hydrogen peroxide plays a central role in oxidative stress and cell signaling, and PRDXs are one of its main consumers. The intrinsically resistant C1 and C3 clones had lower MITF, PGC-1α, and PRDX1 expression, while C1 had higher AXL and decreased pigmentation markers, linking PRDX1 to clonal heterogeneity and resistance. PRDX2 is depleted in acquired BRAFi-resistant cells and acts as a redox sensor. Our results illustrate that decreased pigmentation markers are related to therapy resistance and decreased antioxidant defense.

Enzymatic deficiency in Gaucher disease (GD) may induce oxidative stress. Vitamin E is the nature's most effective lipid-soluble antioxidant. This prospective clinical trial assessed the oxidant-antioxidant status in Egyptian patients with GD and the efficacy and safety and of vitamin E as an adjuvant antioxidant therapy. Forty children and adolescents with GD on stable doses of enzyme replacement therapy (ERT) were enrolled. Abdominal ultrasonography and transient elastography were performed. Malondialdehyde (MDA), vitamin E, and antioxidant enzymes (reduced glutathione [GSH], superoxide dismutase [SOD], glutathione peroxidase [GPx], and peroxiredoxin 2 [PRDX2]) were assessed. Patients were compared with 40 age- and sex-matched healthy controls. Patients with GD were randomized either to receive oral vitamin E for 6 months or not. All patients with GD had significantly higher MDA levels with lower levels of vitamin E and antioxidant enzymes compared with healthy controls (p < 0.001). Vitamin E and PRDX2 were negatively correlated to severity score index (SSI), lyso GL1, and MDA. After 6 months of vitamin E supplementation, SSI and liver and spleen volumes and liver stiffness were significantly lower. Lyso GL1 and MDA were significantly decreased post-vitamin E therapy while antioxidant enzymes were significantly higher compared with baseline levels and with patients without vitamin E therapy. Oxidative stress is related to disease severity in pediatric patients with GD. A 6-month vitamin E supplementation for those patients represents a safe therapeutic adjuvant agent increasing the efficacy of ERT, reducing oxidative stress, and improving outcomes., (© 2024 SSIEM.)

Peroxiredoxin (Prx) 2 in red blood cells (RBCs) reacts with various reactive oxygen species and changes to hyperoxidized Prx2 (Prx2-SO2/3). Therefore, Prx2 may serve as an indicator of oxidative stress in vivo. This study aimed to analyze Prx2-SO2/3 levels in clinical samples to examine whether the oxidation state of Prx2 in human RBCs reflects the pathological condition of oxidative stress diseases. We first focused on obstructive sleep apnea (OSA), a hypoxic stress-induced disease of the respiratory system, and investigated the levels of Prx2-SO2/3 accumulated in the RBCs of OSA patients. In measurements on a small number of OSA patients and healthy subjects, levels of Prx2-SO2/3 accumulation in patients with OSA were clearly increased compared to those in healthy subjects. Hence, we proceeded to validate these findings with more samples collected from patients with OSA. The results revealed significantly higher levels of erythrocytic Prx2-SO2/3 in patients with OSA than in healthy subjects, as well as a positive correlation between the severity of OSA and Prx2-SO2/3 levels in the RBCs. Moreover, we performed a chromatographic study to show the structural changes of Prx2 due to hyperoxidation. Our findings demonstrated that the Prx2-SO2/3 molecules in RBCs from patients with OSA were considerably more hydrophilic than the reduced form of Prx2. These results implicate Prx2-SO2/3 as a promising candidate biomarker for OSA. [ABSTRACT FROM AUTHOR]

In Alzheimer's disease, reactive oxygen species (ROS) are generated by the deposition of amyloid-beta oligomers (AβOs), which represent one of the important causes of neuronal cell death. Additionally, AβOs are known to induce autophagy via ROS induction. Previous studies have shown that autophagy upregulation aggravates neuronal cell death. In this study, the effects of peroxiredoxin 2 (Prx2), a member of the peroxidase family of antioxidant enzymes, on regulating AβO-mediated autophagy were investigated. Prx2 decreased AβO-mediated oxidative stress and autophagy in N2a-APPswe cells. Further, we examined the relationship between the neuronal protective effect of Prx2 and a decrease in autophagy. Similar to the effects of N-acetyl cysteine, Prx2 decreased AβO-induced ROS and inhibited p62 protein expression levels by downregulating the activation of NRF2 and its translocation to the nucleus. In addition, treatment with 3-methyladenine, an autophagy inhibitor, ameliorates neuronal cell death. Overall, these results demonstrate that the Prx2-induced decrease in autophagy was associated with the inhibition of ROS via the ROS–NRF2–p62 pathway in N2a-APPswe cells. Therefore, our results revealed that Prx2 is a potential therapeutic target in anti-Alzheimer therapy. [ABSTRACT FROM AUTHOR]

We aimed to study the influence of preventing methemoglobin (metHb) formation, in the roles of peroxiredoxin 2 (Prx2), glutathione peroxidase (GPx) and catalase (CAT) on the erythrocyte antioxidant defense system. We performed in vitro assays using healthy erythrocytes, with and without inhibition of autoxidation of Hb (saturation with carbon monoxide), followed by H 2 O 2 -induced oxidative stress. We assessed the enzyme activities and amounts of CAT, GPx and Prx2 in the red blood cell (RBC) cytosol and membrane and several biomarkers of oxidative stress, such as the reduced and oxidized glutathione levels, thiobarbituric acid reactive substances (TBARS) levels, membrane bound hemoglobin and total antioxidant status. When autoxidation of Hb was inhibited, no significant changes were found for GPx and CAT; Prx2 was observed only in the monomeric form in the cytosol and none bound to the membrane. Blocking the function of Hb as a pseudo-peroxidase does not seem to have an impact on the function of the RBC peroxidases. [Display omitted] [ABSTRACT FROM AUTHOR]

A decline in mitochondrial function and increased susceptibility to oxidative stress is a hallmark of ageing. Exercise endogenously generates reactive oxygen species (ROS) in skeletal muscle and promotes mitochondrial remodelling resulting in improved mitochondrial function. It is unclear how exercise induced redox signalling results in alterations in mitochondrial dynamics and morphology. In this study, a Caenorhabditis elegans model of exercise and ageing was used to determine the mechanistic role of Peroxiredoxin 2 (PRDX-2) in regulating mitochondrial morphology. Mitochondrial morphology was analysed using transgenic reporter strains and transmission electron microscopy, complimented with the analysis of the effects of ageing and exercise on physiological activity. The redox state of PRDX-2 was altered with exercise and ageing, hyperoxidised peroxiredoxins were detected in old worms along with basally elevated intracellular ROS. Exercise generated intracellular ROS and rapid mitochondrial remodelling, which was disrupted with age. The exercise intervention promoted mitochondrial ER contact sites (MERCS) assembly and increased DAF-16/FOXO nuclear localisation. The prdx-2 mutant strain had a disrupted mitochondrial network as evidenced by increased mitochondrial fragmentation. In the prdx-2 mutant strain, exercise did not activate DAF-16/FOXO, mitophagy or increase MERCS assembly. The results demonstrate that exercise generated ROS increased DAF-16/FOXO transcription factor nuclear localisation required for activation of mitochondrial fusion events that were blunted with age. The data demonstrate the critical role of PRDX-2 in orchestrating mitochondrial remodelling in response to a physiological stress by regulating redox dependent DAF-16/FOXO nuclear localisation. [Display omitted] • Exercise generates ROS and promotes mitochondrial remodelling dependent on DAF-16. • Exercise induces mitochondrial ER contact site assembly and mitochondrial dynamics. • Ageing and loss of PRDX-2 results in disrupted mitochondrial fusion. • The redox state of PRDX-2 determines appropriate DAF-16 nuclear localisation. [ABSTRACT FROM AUTHOR]

To examine if peroxiredoxin 2 (Prx2) deficiency aggravates high-fat diet-induced insulin resistance. Insulin sensitivity was measured in Prx2 knockout (KO) and wild-type (WT) littermates using the hyperinsulinemic-euglycemic clamp. Whole body glucose turnover, glucose uptake, and levels of glucose transporter 4 (Glut4) protein in the skeletal muscle were found to be lower. This was followed by increased expression of oxidative stress markers in Prx2 KO mice than that in WT mice in the control diet group. Although, a 12-week high-fat diet induced insulin resistance and enhanced oxidative stress in both genotypes, there was no difference between WT and Prx2 KO mice with respect to insulin sensitivity and the level of oxidative stress markers. Accordingly, the levels of phosphorylated Akt and Glut4 were similar between the two genotypes. These results suggest that Prx2 does not affect high-fat diet-induced oxidative stress and insulin resistance in mice. [ABSTRACT FROM AUTHOR]

Peroxiredoxin 2 (Prx2) regulates oxidative stress response in neuronal injury. The present study examined the effects of Prx2 deletion on transient global ischemia-induced hippocampal-dependent memory impairment. First, 20-min bilateral common carotid artery occlusion (BCCAO)-reperfusion and sham-operated control procedures were conducted in 6- or 7-month-old Prx2 knockout and wild-type mice. The cognitive status of these mice was assessed using the Morris water maze task with a hidden platform and a novel object recognition task 7 days after the 20-min BCCAO. Next, to evaluate neuronal degeneration and oxidative stress in the CA1 subregion of the hippocampus critical for learning and memory, we measured immunoreactive Fluoro-jade C (FJC)-positive signals and 4-hydroxy-2- trans -nonenal (4-HNE) levels, respectively. The 20-min BCCAO induced cognitive impairments and increased the intensity of FJC-positive signals and 4-HNE levels of CA1 in Prx2 knockout mice but not in wild-type mice. These results suggest that Prx2 deficiency reduces resilience to transient global ischemia. • Effects of Prx2 deletion on the transient BCCAO-induced hippocampal impairments. • Impaired recognition memory in Prx2 knockout mice with transient BCCAO. • Impaired spatial memory in Prx2 knockout mice with transient BCCAO. • Increased oxidative stress in Prx2 knockout mice with transient BCCAO. [ABSTRACT FROM AUTHOR]

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is a prevalent condition worldwide and is caused by loss-of-function mutations in the G6PD gene. Individuals with deficiency are more susceptible to oxidative stress which leads to the classical, acute hemolytic anemia (favism). However, G6PD deficiency in newborn infants presents with an increased risk of hyperbilirubinemia, that may rapidly escalate to result in bilirubin induced neurologic dysfunction (BIND). Often with no overt signs of hemolysis, G6PD deficiency in the neonatal period appears to be different in the pathophysiology from favism. This review discusses and compares the mechanistic pathways involved in these two clinical presentations of this enzyme disorder. In contrast to the membrane disruption of red blood cells and Heinz bodies formation in favism, G6PD deficiency causing jaundice is perhaps attributed to the disruption of oxidant-antioxidant balance, impaired recycling of peroxiredoxin 2, thus affecting bilirubin clearance. Screening for G6PD deficiency and close monitoring of affected infants are important aspects in neonatal care to prevent kernicterus, a permanent and devastating neurological damage. WHO recommends screening for G6PD activity of all infants in countries with high prevalence of this deficiency. The traditional fluorescent spot test as a screening tool, although low in cost, misses a significant proportion of cases with moderate deficiency or the partially deficient, heterozygote females. Some newer and emerging laboratory tests and diagnostic methods will be discussed while developments in genomics and proteomics contribute to increasing studies that spatially profile genetic mutations within the protein structure that could predict their functional and structural effects. In this review, several known variants of G6PD are highlighted based on the location of the mutation and amino acid replacement. These could provide insights on why some variants may cause a higher degree of phenotypic severity compared to others. Further studies are needed to elucidate the predisposition of some variants toward certain clinical manifestations, particularly neonatal hyperbilirubinemia, and how some variants increase in severity when co-inherited with other blood- or bilirubin-related genetic disorders.

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Amino acid epimerization, a process of converting L -amino acids to D -amino acids, will lead to modification in the protein structure and, subsequently, its biological function. This modification causes no change in protein m/z and may be overlooked during protein analysis. Aspartic Acid Epimerization (AAE) is faster than other amino acids and could be accelerated by free radicals and peroxides. In this work, a novel and site-specific HPLC method using a chiral stationary phase for determining the AAE in the active site model peptide (AP) of Peroxiredoxin 2 has been developed and validated. The developed method showed good linearity (1 – 200 μg/mL) and recoveries of the limit of quantification (LOQ), low, medium, and high concentrations were between 85% and 115%. The Kinetics of AAE in AP were studied using the developed method, and the results showed that when ascorbic acid and Cu2+ coexisted, the AP epimerized rapidly. The AAE extent increased with time and was positively correlated with hydrogen peroxide generation. • A novel HPLC method using a chiral column for the separation of Prx2 active site peptide (AP) epimers. • The method used for the kinetics study of aspartic acid epimerization in AP. • AP epimerized rapidly in ascorbic acid and Cu2+ system. • Epimerization increased with time and positively correlated with H 2 O 2 generated from this system. • Epimerization was terminated by adding a free radical scavenger indicating that H 2 O 2 played a vital role. [ABSTRACT FROM AUTHOR]

The second most common mutation in melanoma occurs in NRAS oncogene, being a more aggressive disease that has no effective approved treatment. Besides, cellular plasticity limits better outcomes of the advanced and therapy-resistant patients. Peroxiredoxins (PRDXs) control cellular processes through direct hydrogen peroxide oxidation or by redox-relaying processes. Here, we demonstrated that PRDX2 could act as a modulator of multiple EMT markers in NRAS-mutated melanomas. PRDX2 knockdown lead to phenotypic changes towards invasion in human reconstructed skin and the treatment with a PRDX mimetic (gliotoxin), decreased migration in PRDX2-deficient cells. We also confirmed the favorable clinical outcome of patients expressing PRDX2 in a large primary melanoma cohort. This study contributes to our knowledge about genes involved in phenotype switching and opens a new perspective for PRDX2 as a biomarker and target in NRAS-mutated melanomas. [Display omitted] • NRAS-mutated melanoma cells did not express PRDX2 are more invasive. • Knockdown PRDX2 in melanoma cells increased invasion potential. • Melanoma cells did not express PRDX2 showed more EMT markers. • Mimetic of PRDX2 is able to change migration capability. • PRDX2 correlated with better prognosis in primary melanoma cohort. [ABSTRACT FROM AUTHOR]

Peroxiredoxins (Prxs) are a ubiquitously expressed family of antioxidant enzymes that either facilitate or inhibit tumorigenesis, depending on the cancer type and Prx isoform. Prx2 is a typical Prx that has a dual role in tumorigenesis and tumor progression. However, the expression of Prx2 and its precise role in cervical cancer remains to be elucidated. Therefore, the present study aimed to investigate the expression of Prx2 and its association with the progression and prognosis of cervical squamous cell cancer (CSCC). In the present study, the clinicopathological data of 105 patients diagnosed with CSCC were collected from the medical record system at Jingzhou Central Hospital, Tongji Medical College of Huazhong University of Science and Technology (Jingzhou, China). Prx2 protein was also detected in 105 CSCC tissues and 40 adjacent peri-tumoral tissues by immunohistochemical staining. The relationships between Prx2 expression and clinicopathological features, vascular endothelial growth factor A (VEGF-A) expression and micro-vessel density (MVD) in CSCC were then analyzed. Progression-free survival (PFS) was also assessed using both univariate and multivariate analyses. The results of the present study demonstrated that the expression of Prx2 was upregulated in CSCC tissues compared with the adjacent peri-tumoral tissues (P<0.001). In addition, higher Prx2 expression was associated with greater depth of stromal invasion (P=0.023) and positive lymph vascular space invasion (P=0.044), while the Prx2 expression level was not associated with age, tumor size, histological grade, lymph node (LN) metastasis or International Federation of Gynecology and Obstetrics (FIGO) stage (all P>0.05). Furthermore, increased Prx2 expression was associated with high MVD (P=0.016), while expression of VEGF-A was not associated with Prx2 expression (P>0.05). Kaplan-Meier analysis showed that patients with high Prx2 expression (log-rank test, P=0.039), high MVD (log-rank test, P=0.015), a higher FIGO stage (log-rank test, P=0.021) and LN metastasis (log-rank test, P=0.022) had a shorter PFS time than patients with low Prx2 expression, low MVD, a lower FIGO stage and without LN metastasis, respectively. Cox proportional hazard regression analysis revealed that expression of Prx2 [hazard ratio (HR), 2.551; 95% confidence interval (CI), 1.056–6.162; P=0.037], MVD (HR, 2.436; CI, 1.034–5.735; P=0.042) and FIGO stage (HR, 1.543; CI, 1.027–2.319; P=0.037) were independent factors for PFS time. In conclusion, the results of the present study suggested that Prx2 could act as a potential biomarker for predicting CSCC progression and prognosis and could be a novel target for antiangiogenic therapy of CSCC. [ABSTRACT FROM AUTHOR]

Abstract Background This study aims to investigate the expression of thioredoxin 1, peroxiredoxin 1 and peroxiredoxin 2 in bulky cervical squamous carcinoma and its predictive role in cisplatin-based neoadjuvant chemotherapy. Methods Initially, the expression of thioredoxin 1, peroxiredoxin 1 and peroxiredoxin 2 protein was analyzed in 13 human cervical squamous cancer tissues and their paired adjacent non-cancerous tissues by western-blotting and immunohistochemistry. Then, correlation between the expression of thioredoxin 1, peroxiredoxin 1, peroxiredoxin 2 and responses to cisplatin-based neoadjuvant chemotherapy was analyzed in 35 paired tumor samples (pre- and post-chemotherapy) from bulky cervical squamous cancer patients by immunohistochemistry. Results A clinical response occurred in 48.6% (17/35) of patients, including 14.3% (5/35) with a complete response and 34.3% (12/35) with a partial response. The expression of thioredoxin 1, peroxiredoxin 1 and peroxiredoxin 2 was much higher in cervical squamous cancer tissues compared with paired adjacent non-cancerous tissues by western-blotting and immunohistochemistry. Additionally, the expression of thioredoxin 1, peroxiredoxin 1 and peroxiredoxin 2 was significantly up-regulated in post-chemotherapy tissues compared to pre-chemotherapy cervical cancer tissues. High levels of thioredoxin 1, peroxiredoxin 1 and peroxiredoxin 2 were associated with a poor chemotherapy response in cervical squamous cancer patients. Conclusions Thioredoxin 1, peroxiredoxin 1 and peroxiredoxin 2 are frequently over-expressed in cervical squamous cancer. High expression levels of these proteins were related to a poor response to cisplatin-based neoadjuvant chemotherapy. The present study is the first report that thioredoxin peroxidase system may serve as a prediction of the responses to neoadjuvant chemotherapy in cervical squamous cancer.

Peroxiredoxin (Prx) 2 in red blood cells (RBCs) reacts with various reactive oxygen species and changes to hyperoxidized Prx2 (Prx2-SO2/3). Therefore, Prx2 may serve as an indicator of oxidative stress in vivo. This study aimed to analyze Prx2-SO2/3 levels in clinical samples to examine whether the oxidation state of Prx2 in human RBCs reflects the pathological condition of oxidative stress diseases. We first focused on obstructive sleep apnea (OSA), a hypoxic stress-induced disease of the respiratory system, and investigated the levels of Prx2-SO2/3 accumulated in the RBCs of OSA patients. In measurements on a small number of OSA patients and healthy subjects, levels of Prx2-SO2/3 accumulation in patients with OSA were clearly increased compared to those in healthy subjects. Hence, we proceeded to validate these findings with more samples collected from patients with OSA. The results revealed significantly higher levels of erythrocytic Prx2-SO2/3 in patients with OSA than in healthy subjects, as well as a positive correlation between the severity of OSA and Prx2-SO2/3 levels in the RBCs. Moreover, we performed a chromatographic study to show the structural changes of Prx2 due to hyperoxidation. Our findings demonstrated that the Prx2-SO2/3 molecules in RBCs from patients with OSA were considerably more hydrophilic than the reduced form of Prx2. These results implicate Prx2-SO2/3 as a promising candidate biomarker for OSA.

In Alzheimer’s disease, reactive oxygen species (ROS) are generated by the deposition of amyloid-beta oligomers (AβOs), which represent one of the important causes of neuronal cell death. Additionally, AβOs are known to induce autophagy via ROS induction. Previous studies have shown that autophagy upregulation aggravates neuronal cell death. In this study, the effects of peroxiredoxin 2 (Prx2), a member of the peroxidase family of antioxidant enzymes, on regulating AβO-mediated autophagy were investigated. Prx2 decreased AβO-mediated oxidative stress and autophagy in N2a-APPswe cells. Further, we examined the relationship between the neuronal protective effect of Prx2 and a decrease in autophagy. Similar to the effects of N-acetyl cysteine, Prx2 decreased AβO-induced ROS and inhibited p62 protein expression levels by downregulating the activation of NRF2 and its translocation to the nucleus. In addition, treatment with 3-methyladenine, an autophagy inhibitor, ameliorates neuronal cell death. Overall, these results demonstrate that the Prx2-induced decrease in autophagy was associated with the inhibition of ROS via the ROS–NRF2–p62 pathway in N2a-APPswe cells. Therefore, our results revealed that Prx2 is a potential therapeutic target in anti-Alzheimer therapy.

Peroxiredoxin 2 (PRDX2), an inhibitor of reactive oxygen species (ROS), is potentially involved in the progression of atherosclerosis (AS). The aim of this study was to explore the role and mechanism of PRDX2 in AS. The expression of PRDX2 was evaluated in 14 human carotid artery tissues with or without AS. The results showed that the positive reaction of PRDX2 was observed in the carotid artery vascular smooth muscle cells (CAVSMCs). To assess the mechanism by which PRDX2 may function in AS, the CAVSMCs were transfected with pEX4-PRDX2 and si-PRDX2. The catalase, hydrogen peroxide (H2O2) scavenger, was used to further confirm that PRDX2-induced inhibitory effects might be mediated through reducing ROS levels. Phenotype alteration and functional testing included transcription testing, immunostaining, and expression studies. The drug of MAPK signaling pathway inhibitors SB203580, SP600125, and PD98059 was used to evaluate the underlying mechanism. In this study, we found that the protein level of PRDX2 and the level of H2O2 were higher in the human AS carotid artery tissues than in the normal carotid artery tissues, accompanied with the activation of MAPK signaling pathway. The up-regulation of PRDX2 in the CAVSMCs significantly decreased the expression of ROS, collagen type I (COL I), collagen type III (COL III), vascular cell adhesion molecule-1 (VCAM-1), and intercellular adhesion molecule-1 (ICAM-1) and inhibited the proliferation, migration, and transformation of the CAVSMCs. The up-regulation of PRDX2 reversed the effect of the CAVSMCs treated with tumor necrosis factor-α (TNF-α). In addition, PRDX2 down-regulation promoted the protein levels of p-p38, p-JNK, and p-ERK, which was confirmed in relevant MAPK inhibitor treatment experiments. Our results suggest a protective role of PRDX2, as a scavenger of ROS, in AS progression through inhibiting the VSMC phenotype alteration and function via MAPK signaling pathway.

Purpose: To investigate the role of PRDX2 in esophageal carcinoma (ESCA). Methods: The expression of PRDX2 was detected in ESCA tissues. And PRDX2 expression in two ESCA cell lines was knocked down. Cell proliferation, metastasis and invasion were detected in these cells. Results: Here, we found that PRDX2 expression was significantly increased in ESCA tissues and was associated with a poor prognosis in ESCA patients. In addition, PRDX2 expression was significantly associated with pathological grading, infiltration degree and 5-year survival time in ESCA patients. Next, we knocked down PRDX2 expression by PRDX2-shRNA transfection in two ESCA cell lines, Eca-109 and TE-1. Proliferation analysis indicated that in vitro PRDX2 knockdown decreased growth and clone formation of ESCA cells. Scratch and transwell assays indicated that cell migration and invasion were significantly inhibited by PRDX2 knockdown. In addition, PRDX2 knockdown inhibited cell cycle of ESCA cells and down-regulated Cyclin D1-CDK4/6. Moreover, PRDX2 knockdown regulated proteins involved in mitochondrial-dependent apoptosis, including increased Bax and Caspase9/3 and decreased Bcl2. Mechanism investigation indicated that PRDX2 knockdown led to inactivation of Wnt/β-catenin and AKT pathways. Conclusions: Our data suggest that PRDX2 may function as an oncogene in the development of ESCA via regulating Wnt/β-catenin and AKT pathways. Our study fills a gap in the understanding of the role of PRDX2 in ESCA and provides a potential target for ESCA treatment. [ABSTRACT FROM AUTHOR]

Red blood cell (RBC) lysis within the hematoma causes brain injury following intracerebral hemorrhage. Peroxiredoxin 2 (PRX-2) is the third most abundant protein in RBCs and this study examined the potential role of PRX-2 in inducing brain injury in rats. First, adult male Sprague-Dawley rats had an intracaudate injection of lysed RBCs or saline. Brains were harvested at 1 h to measure PRX-2 levels. Second, rats had an intracaudate injection of either recombinant PRX-2, heat-inactivated PRX-2, or saline. Third, rats had intracaudate co-injection of lysed RBCs with conoidin A, a PRX-2 inhibitor, or vehicle. For the second and third parts of studies, behavioral tests were performed and all rats had magnetic resonance imaging prior to euthanasia for brain immunohistochemistry and Western blotting. We found that brain PRX-2 levels were increased after lysed RBC injection. Intracaudate injection of PRX-2 resulted in blood-brain barrier disruption, brain swelling, neutrophil infiltration, microglia activation, neuronal death, and neurological deficits. Intracerebral injection of lysed RBCs induced brain injury, which was reduced by conoidin A. These results suggest that extracellular PRX-2 released from hematoma can cause brain injury following brain hemorrhage and could be a potential therapeutic target. [ABSTRACT FROM AUTHOR]

Abstract Background Peroxiredoxin (Prx) protein family have been reported as important damage-associated molecular patterns (DAMPs) in ischemic stroke. Since peroxiredoxin 2 (Prx2) is the third most abundant protein in erythrocytes and the second most protein in the cerebrospinal fluid in traumatic brain injury and subarachnoid hemorrhage (SAH) patients, we assessed the role of extracellular Prx2 in the context of SAH. Methods We introduced a co-culture system of primary neurons and microglia. Prx2 was added to culture medium with oxyhemoglobin (OxyHb) to mimic SAH in vitro. Neuronal cell viability was assessed by lactate dehydrogenase (LDH) assay, and neuronal apoptosis was determined by TUNEL staining. Inflammatory factors in culture medium were measured by ELISA, and their mRNA levels in microglia were determined by qPCR. Toll-like receptor 4 knockout (TLR4-KO) mice were used to provide TLR4-KO microglia; ST-2825 was used to inhibit MyD88, and pyrrolidine dithiocarbamate (PDTC) was used to inhibit NF-κB. Related cellular signals were analyzed by Western blot. Furthermore, we detected the level of Prx2 in aneurysmal SAH patients’ cerebrospinal fluids (CSF) and compared its relationship with Hunt-Hess grades. Results Prx2 interacted with TLR4 on microglia after SAH and then activated microglia through TLR4/MyD88/NF-κB signaling pathway. Pro-inflammatory factors were expressed and released, eventually caused neuronal apoptosis. The levels of Prx2 in SAH patients positively correlated with Hunt-Hess grades. Conclusions Extracellular Prx2 in CSF after SAH is a DAMP which resulted in microglial activation via TLR4/MyD88/NF-κB pathway and then neuronal apoptosis. Prx2 in patients’ CSF may be a potential indicator of brain injury and prognosis.

The peroxiredoxins (PRXs) constitute a ubiquitous antioxidant. Growing evidence in neurodegenerative disorders such as Parkinson’s disease (PD) or Alzheimer’s disease (AD) has highlighted a crucial role for PRXs against neuro-oxidation. Chorea-acanthocytosis/Vps13A disease (ChAc) is a devastating, life-shortening disorder characterized by acanthocytosis, neurodegeneration and abnormal proteostasis. We recently developed a Vps13a−/− ChAc-mouse model, showing acanthocytosis, neurodegeneration and neuroinflammation which could be restored by LYN inactivation. Here, we show in our Vps13a−/− mice protein oxidation, NRF2 activation and upregulation of downstream cytoprotective systems NQO1, SRXN1 and TRXR in basal ganglia. This was associated with upregulation of PRX2/5 expression compared to wild-type mice. PRX2 expression was age-dependent in both mouse strains, whereas only Vps13a−/− PRX5 expression was increased independent of age. LYN deficiency or nilotinib-mediated LYN inhibition improved autophagy in Vps13a−/− mice. In Vps13a−/−; Lyn−/− basal ganglia, absence of LYN resulted in reduced NRF2 activation and down-regulated expression of PRX2/5, SRXN1 and TRXR. Nilotinib treatment of Vps13a−/− mice reduced basal ganglia oxidation, and plasma PRX5 levels, suggesting plasma PRX5 as a possible ChAc biomarker. Our data support initiation of therapeutic Lyn inhibition as promptly as possible after ChAc diagnosis to minimize development of irreversible neuronal damage during otherwise inevitable ChAc progression.

AimTo investigate the role of histone deacetylase 6 (HDAC6) deacetylation activity in nucleotide-binding oligomerization domain and leucine-rich repeat pyrin 3 domain (NLRP3) inflammatory response and explore the effects of pharmacological inhibition of HDAC6 with tubastatin A (TBA) on dopaminergic injury.MethodsUsing 6-OHDA-induced Parkinson’s disease (PD) models, we examined the effects of TBA on NLRP3 activation and cell injury in SH-SY5Y cells. We also investigated the effects of TBA on NLRP3 inflammatory responses and dopaminergic injury in the nigrostriatal system in mice and analyzed the acetylation levels of peroxiredoxin2 (Prx2) and oxidative stress.ResultsTBA inhibited 6-OHDA-induced NLRP3 activation, as demonstrated by decreased expressions of NLRP3 and matured caspase-1 and IL-1β, and also alleviated glial proliferation and dopaminergic neuronal degeneration. Notably, TBA recovered acetylation levels of Prx2 and reduced oxidative stress.ConclusionOur findings indicate that pharmacological inhibition of HDAC6 with TBA attenuates NLRP3 inflammation and protects dopaminergic neurons, probably through Prx2 acetylation. This study suggests that the deacetylase catalytic domain of HDAC6 is a potential target for PD treatment.

Aim: To investigate the role of histone deacetylase 6 (HDAC6) deacetylation activity in nucleotide-binding oligomerization domain and leucine-rich repeat pyrin 3 domain (NLRP3) inflammatory response and explore the effects of pharmacological inhibition of HDAC6 with tubastatin A (TBA) on dopaminergic injury. Methods: Using 6-OHDA-induced Parkinson's disease (PD) models, we examined the effects of TBA on NLRP3 activation and cell injury in SH-SY5Y cells. We also investigated the effects of TBA on NLRP3 inflammatory responses and dopaminergic injury in the nigrostriatal system in mice and analyzed the acetylation levels of peroxiredoxin2 (Prx2) and oxidative stress. Results: TBA inhibited 6-OHDA-induced NLRP3 activation, as demonstrated by decreased expressions of NLRP3 and matured caspase-1 and IL-1β, and also alleviated glial proliferation and dopaminergic neuronal degeneration. Notably, TBA recovered acetylation levels of Prx2 and reduced oxidative stress. Conclusion: Our findings indicate that pharmacological inhibition of HDAC6 with TBA attenuates NLRP3 inflammation and protects dopaminergic neurons, probably through Prx2 acetylation. This study suggests that the deacetylase catalytic domain of HDAC6 is a potential target for PD treatment. [ABSTRACT FROM AUTHOR]

Parkinson's disease (PD) is a major neurodegenerative disease. One of the known genetic contributors to PD pathogenesis is leucine-rich repeat kinase 2 (LRRK2) whose mutations with elevated kinase activity could lead to both familial and sporadic PD. However, how the pathogenic kinase activity of LRRK2 is regulated remains largely unclear. Here we report that peroxiredoxin 2 (Prx2) was identified as a novel interacting protein to LRRK2 with preferential expression in dopaminergic neurons over other Prx proteins. We also confirmed that Prx2 interacted with LRRK2 through its COR domain and its overexpression significantly decreased the kinase activity of mutant LRRK2. Functionally, overexpressed Prx2 rescued the transfected cells from LRRK2 mutant induced apoptotic processes. Importantly, overexpressed Prx2 reversed the altered subcellular distribution of cationindependent mannose 6-phosphate receptor (CI-M6PR) induced by PD-mutant LRRK2. Our results suggest that, by interacting with LRRK2, Prx2 may play an inhibitory role in the LRRK2 mediated cellular toxicity in PD by inhibiting its kinase activity. [ABSTRACT FROM AUTHOR]

Peroxiredoxins (Prxs) detoxify hydrogen peroxide (H 2 O 2), peroxynitrite, and various organic hydroperoxides. However, the differential oxidative status of Prxs reacted with each peroxide remains unclear. In the present study, we focused on the oxidative alteration of Prxs and demonstrated that, in human red blood cells (RBCs), peroxiredoxin 2 (Prx2) is readily reactive with H 2 O 2 , forming disulfide dimers, but was not easily hyperoxidized. In contrast, Prx2 was highly sensitive to the relatively hydrophobic oxidants, such as tert -butyl hydroperoxide (t -BHP) and cumene hydroperoxide. These peroxides hyperoxidized Prx2 into oxidatively damaged forms in RBCs. The t -BHP treatment formed hyperoxidized Prx2 in a dose-dependent manner. When organic hydroperoxide-treated RBC lysates were subjected to reverse-phase high performance liquid chromatography, two peaks derived from hyperoxidized Prx2 appeared along with the decrease of that corresponding to native Prx2. Liquid chromatography-tandem mass spectrometry analysis clearly showed that hyperoxidation to sulfonic acid (-SO 3 H) at Cys-51 residue was more advanced in a newfound hyperoxidized Prx2 compared to another hydrophobic hyperoxidized form previously identified. These results indicate that irreversible hyperoxidation of the Prx2 monomer in RBCs was easily caused by organic hydroperoxide but not H 2 O 2. Thus, it is important to detect the hyperoxidation of Prx2 into sulfinic or sulfonic acid derivates of Cys-51 because hyperoxidized Prx2 is a potential marker of oxidative injury caused by organic hydroperoxides in human RBCs. • Human Prx2 is oxidized by H 2 O 2 to form disulfide dimers but not easily hyperoxidized. • Native Prx2 and two hyperoxidized forms were clearly separated by reverse-phase HPLC. • Hyperoxidized Prx2 may be a marker of oxidative injury due to organic hydroperoxides. [ABSTRACT FROM AUTHOR]

Peroxiredoxin 2 (PRDX2), a characteristic 2-Cys enzyme is one of the foremost effective scavenger proteins against reactive oxygen species (ROS) and hydrogen peroxide (H 2 O 2) defending cells against oxidative stress. Dysregulation of this antioxidant raises the quantity of ROS and oxidative stress implicated in several diseases. PRDX2 lowers the generation of ROS that takes part in controlling several signalling pathways occurring in neurons, protecting them from stress caused by oxidation and an inflammatory harm. Depending on the aetiological variables, the kind of cancer, and the stage of tumour development, PRDX2 may behave either as an onco-suppressor or a promoter. However, overexpression of PRDX2 may be linked to the development of numerous cancers, including those of the colon, cervix, breast, and prostate. PRDX2 also plays a beneficial effect in inflammatory diseases. PRDX2 being a thiol-specific peroxidase, is known to control proinflammatory reactions. The spilling of PRDX2, on the other hand, accelerates cognitive impairment following a stroke by triggering an inflammatory reflex. PRDX2 expression patterns in vascular cells tend to be crucial to its involvement in cardiovascular diseases. In vascular smooth muscle cells, if the protein tyrosine phosphatase is restricted, PRDX2 could avoid the neointimal thickening which relies on platelet derived growth factor (PDGF), a vital component of vascular remodelling. A proper PRDX2 balance is therefore crucial. The imbalance causes a number of illnesses, including cancers, inflammatory diseases, cardiovascular ailments, and neurological and neurodegenerative problems which are discussed in this review. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract The events that trigger early onset of atherosclerotic lesion formation are poorly understood. Initially, microscopic atherosclerotic lesions appear in the aortic root in 10-week-old apoE-knockout mice that are fed normal chow. Using proteome and immunohistochemical analyses, we investigated proteins in aortic media whose expression changes in athero-prone regions at the beginning of lesion formation. Protein profiles of the root/arch and thoracic/abdominal regions of aortas in 10-week-old apoE-knockout mice were analyzed using 2D-gel electrophoresis. Proteins in 81 spots with different abundance were identified. Among them, we focused on proteins related to oxidative stress and smooth muscle cells (SMCs). The level of peroxiredoxin 2 (Prx2), a major cellular antioxidant enzyme that reduces hydrogen peroxide, was lower in aortic root/arch compared with thoracic/abdominal aorta. Immunohistochemical staining demonstrated that Prx2 expression in SMCs in the aortic root was high at 4 weeks and decreased at 10 weeks in apoE-knockout mice, while Prx2 expression in the aorta was unchanged in wild-type mice. The level of Prx2 expression correlated positively with the SMC differentiation markers, α-smooth muscle actin and transgelin, suggesting that a decline in Prx2 expression accompanies SMC dedifferentiation. Accumulated acrolein-modified proteins and the infiltration of macrophages in aortic media were observed in areas with low Prx2 expression. These results showed that Prx2 expression declines in athero-prone aortic root before lesion formation, and this reduction in Prx2 expression correlates with lipid peroxidation, SMC dedifferentiation, and macrophage recruitment. Graphical abstract fx1 Highlights • Peroxiredoxin 2 (Prx2) decreased at the beginning of atherosclerotic lesion formation in aortic media in apoE-KO mice. • Local aortic regions with low Prx2 expression accumulate oxidation products. • The concomitant reduction of Prx2, α-SMA and transgelin expressions suggests Prx2 relates to SMC dedifferentiation. • Infiltration of macrophages into media is observed at the site of Prx2 reduction. • Prx2 reduction at small regions is a potential triggering event at the early onset of atherogenesis. [ABSTRACT FROM AUTHOR]

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Peroxiredoxins are thiol‐dependent peroxidases that function in peroxide detoxification and H2O2 induced signaling. Among the six isoforms expressed in humans, PRDX1 and PRDX2 share 97% sequence similarity, 77% sequence identity including the active site, subcellular localization (cytosolic) but they hold different biological functions albeit associated with their peroxidase activity. Using recombinant human PRDX1 and PRDX2, the kinetics of oxidation and hyperoxidation with H2O2 and peroxynitrite were followed by intrinsic fluorescence. At pH 7.4, the peroxidatic cysteine of both isoforms reacts nearly tenfold faster with H2O2 than with peroxynitrite, and both reactions are orders of magnitude faster than with most protein thiols. For both isoforms, the sulfenic acids formed are in turn oxidized by H2O2 with rate constants of ca 2 × 103 M−1 s−1 and by peroxynitrous acid significantly faster. As previously observed, a crucial difference between PRDX1 and PRDX2 is on the resolution step of the catalytic cycle, the rate of disulfide formation (11 s−1 for PRDX1, 0.2 s−1 for PRDX2, independent of the oxidant) which correlates with their different sensitivity to hyperoxidation. This kinetic pause opens different pathways on redox signaling for these isoforms. The longer lifetime of PRDX2 sulfenic acid allows it to react with other protein thiols to translate the signal via an intermediate mixed disulfide (involving its peroxidatic cysteine), whereas PRDX1 continues the cycle forming disulfide involving its resolving cysteine to function as a redox relay. In addition, the presence of C83 on PRDX1 imparts a difference on peroxidase activity upon peroxynitrite exposure that needs further study. [ABSTRACT FROM AUTHOR]

Reactive oxygen species (ROS) produced in biological reactions have been shown to contribute to ovarian aging. Peroxiredoxin 2 (Prx2) is an antioxidant enzyme that protects cells by scavenging ROS; however, its effect on age-related, oxidative stress-associated ovarian failure has not been reported. Here, we investigated its role in age-related ovarian dysfunction and 4-vinylcyclohexene diepoxide (VCD)-induced premature ovarian failure using Prx2-deficient mice. Compared to those in wildtype (WT) mice, serum levels of anti-Müllerian hormone, 17β-estradiol, and progesterone and numbers of follicles and corpora lutea were significantly lower in 18-month-old Prx2 −/− mice. Moreover, levels of Bax, cytochrome c, cleaved caspase-3, and phosphorylated JNK proteins were higher and numbers of apoptotic (terminal deoxynucleotidyl transferase dUTP nick end labeling-positive) cells were considerably greater in 18-month-old Prx2 −/− ovaries than WT ovaries. Furthermore, the effects of the ovarian toxicant VCD in significantly enhancing ROS levels and apoptosis through activation of JNK-mediated apoptotic signaling were more pronounced in Prx2 −/− than WT mouse embryonic fibroblasts. Expression of the steroidogenic proteins StAR, CYP11A1, and 3β-HSD and serum levels of 17β-estradiol and progesterone were also reduced to a greater extent in Prx2 −/− mice than WT mice after VCD injection. This reduced steroidogenesis was rescued by addition of the Prx mimic ebselen or JNK inhibitor SP600125. This constitutes the first report that Prx2 deficiency leads to acceleration of age-related or VCD-induced ovarian failure by activation of the ROS-induced JNK pathway. These findings suggest that Prx2 plays an important role in preventing accelerated ovarian failure by inhibiting ROS-induced JNK activation. [ABSTRACT FROM AUTHOR]

Insulin signaling is essential for regulating glucose homeostasis. Numerous studies have demonstrated that reactive oxygen species (ROS) affect insulin signaling, and low ROS levels can act as a signal to regulate cellular function. Peroxiredoxins (Prxs) are highly abundant and widely expressed antioxidant enzymes. However, it is unclear whether antioxidant enzymes, such as Prx2, mediate insulin signaling. The aim of our study was to investigate the influence of Prx2 deficiency on insulin signaling. Our western blot results showed that Prx2 deficiency enhanced insulin signaling and increased oxidation of protein tyrosine phosphatase 1B (PTP1B) and phosphatase and tensin homologue (PTEN) in mouse embryonic fibroblasts (MEFs) treated with insulin. In addition, we assessed ROS levels with a Cytosol-HyPer H 2 O 2 sensor. As a result, increased ROS levels and Akt activation were decreased by N -acetyl-cysteine (Nac), which acted as an antioxidant in Prx2-deficient MEFs. Body weight measurements and glucose tolerance test (GTT) revealed significant body weight reduction and increase in glucose clearance in Prx2 -/- mice fed a high-fat diet. Interestingly, glucose transporter type 4 (GLUT4) was significantly higher in Prx2 -/- mice than in wild-type mice according to western blotting results. Western blotting also revealed that Akt phosphorylation was higher in Prx2 -/- MEFs and muscle tissue than in wild-type. Together, our findings indicate that increased ROS due to Prx2 deficiency promotes insulin sensitivity and glucose clearance in skeletal muscles by increasing protein tyrosine phosphatase (PTPs) oxidation. These results provide novel insights into the fundamental mechanisms of insulin signaling induced by Prx2 deficiency and suggest that ROS-based therapeutic strategies can be used to suppress insulin resistance. [ABSTRACT FROM AUTHOR]

Peroxiredoxin 2 (Prdx2) is a ubiquitous antioxidant enzyme in mammalian brain. Although a protective role of Prdx2 has been established in cerebral ischemia and several neurodegenerative diseases, its contribution against iron-induced neurocytotoxicity still remains to be determined. Accordingly, in this study, we aimed to investigate the effects of Prdx2 on iron-induced cytotoxicity using an in vitro model in which PC12 cells are exposed to ferrous sulfate (FS). The FS treatment increased Prdx2 expression, and promoted lactate dehydrogenase (LDH) release and cell apoptosis in PC12 cells, accompanied by the increase in the Bax/Bcl2 ratio, cytochrome c release, and caspase-3 cleavage. FS exposure also increased the malondialdehyde content (lipid peroxidation), 3′-nitrotyrosine expression (protein nitration), γ-H2A.X formation (DNA oxidation), and promoted nuclear factor kappa B nuclear translocation, cyclooxygenase-2 expression, and release of tumor necrosis factor-α and interleukin-1β. Lentivirus-mediated Prdx2 knockdown intensified the FS-induced LDH release and cell apoptosis by aggravating the oxidative and inflammatory damage. In conclusion, our findings demonstrated that Prdx2 played a vital role in the protection against iron-induced cytotoxicity in PC12 cells. [ABSTRACT FROM AUTHOR]

Sarcomas are rare and clinically diverse malignancies, and treatment optimization requires the development of suitable biomarkers. In earlier research employing proteomics analysis, we identified peroxiredoxin 2 as a biomarker of osteosarcoma (OS) that can predict response to neoadjuvant chemotherapy and verified its functional significance in the resistance of OS cells to chemotherapeutic drugs. In addition, in gastrointestinal stromal tumor (GIST), we identified pfetin as a prognostic biomarker and validated its prognostic utility in multi-institutional studies by immunohistochemistry. Here, we present an overview of our progress in sarcoma proteomics and discuss future perspectives.