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• The DEHP was detected in serum and hair of M. berezovskii in captivity in some farms. • MA fed female M. berezovskii improved the survival rate of M. berezovskii pups. • DEHP induces oxidative stress and apoptosis of PMCs by reducing PRDX6 expression. • MA prevents DEHP inducing apoptosis via upregulating PRDX6 in PMCs. Chinese forest musk deer (FMD), an endangered species, have exhibited low reproductive rates even in captivity due to stress conditions. Investigation revealed the presence of di(2-ethylhexyl) phthalate (DEHP), an environmental endocrine disruptor, in the serum and skin of captive FMDs. Feeding FMDs with maslinic acid (MA) has been observed to alleviate the stress response and improve reproductive rates, although the precise molecular mechanisms remain unclear. Therefore, this study aims to investigate the molecular mechanisms underlying the alleviation of DEHP-induced oxidative stress and cell apoptosis in primary peritubular myoid cells (PMCs) through MA intake. Primary PMCs were isolated and exposed to DEHP in vitro. The results demonstrated that DEHP significantly suppressed antioxidant levels and promoted cell apoptosis in primary PMCs. Moreover, interfering with the expression of PRDX6 was found to induce excessive reactive oxygen species (ROS) production and cell apoptosis in primary PMCs. Supplementation with MA significantly upregulated the expression of PRDX6, thereby attenuating DEHP-induced oxidative stress and cell apoptosis in primary PMCs. These findings provide a theoretical foundation for mitigating stress levels and enhancing reproductive capacity of in captive FMDs. [Display omitted] [ABSTRACT FROM AUTHOR]

Introduction: This study aimed to demonstrate the potential of activated leukocyte cell adhesion molecule (ALCAM), hemopexin (HPX), and peroxiredoxin 6 (PRDX6) as urine biomarkers for systemic lupus erythematosus (SLE). Methods: Urine samples were collected from 138 Korean patients with SLE from the Ajou Lupus Cohort and 39 healthy controls (HC). The concentrations of urine biomarkers were analyzed using enzyme-linked immunosorbent assay kits specific for ALCAM, HPX, and PRDX6, respectively. Receiver operating characteristic (ROC) curve analysis was performed to evaluate the diagnostic utility, and Pearson's correlation analysis was conducted to assess the relationships between the disease activity and urine biomarkers. Results: Patients with SLE and patients with lupus nephritis (LN) showed significantly elevated ALCAM, HPX, and PRDX6 levels compared with HCs. ALCAM, HPX, and PRDX6 showed significant diagnostic values, especially for lupus nephritis (LN), with areas under the receiver operating characteristic curve for LN was 0.850 for ALCAM (95% CI, 0.778-0.921), 0.781 for HPX (95% CI, 0.695-0.867), and 0.714 for PRDX6 (95% CI, 0.617-0.812). Correlation analysis revealed that all proteins were significantly associated with anti-double stranded DNA antibody (ALCAM, r = 0.350, p < 0.001; HPX, r = 0.346, p < 0.001; PRDX6, r = 0.191, p = 0.026) and SLEDAI (ALCAM, r = 0.526, p < 0.001; HPX, r = 0.479, p < 0.001; PRDX6, r = 0.262, p = 0.002). Results from the follow-up of the three biomarker levels in these patients revealed a significant decrease, showing a positive correlation with changes in SLEDAI-2k scores (ALCAM, r = 0.502, p < 0.001; HPX, r = 0.475, p < 0.001; PRDX6, r = 0.245, p = 0.026), indicating their potential as indicators for tracking disease activity. Discussions: Urinary ALCAM, HPX, and PRDX6 levels have diagnostic value and reflect disease activity in Korean patients with SLE, emphasizing their potential for non-invasive monitoring and treatment response evaluation. [ABSTRACT FROM AUTHOR]

Peroxiredoxin 6 (Prdx6), a unique 1-Cys member of the peroxiredoxin family, exhibits peroxidase activity, phospholipase activity, and lysophosphatidylcholine acyltransferase (LPCAT) activity. Prdx6 has been known to be an important enzyme for the maintenance of lipid peroxidation repair, cellular metabolism, inflammatory signaling, and antioxidant damage. Growing research has demonstrated that the altered activity of this enzyme is linked with various pathological processes including central nervous system (CNS) disorders. This review discusses the distinctive structure, enzyme activity, and function of Prdx6 in different CNS disorders, as well as emphasizing the significance of Prdx6 in neurological disorders. [ABSTRACT FROM AUTHOR]

Peroxiredoxin 6 (PRDX6) is a protective biomarker associated with ferroptosis in heart failure (HF). This study investigated the specific mechanism of PRDX6 on doxorubicin (DOX)–induced ferroptosis in HF. Wistar rats and H9c2 cells were induced by DOX to construct HF models. Pathological changes and collagen deposition in myocardium were investigated using HE and Masson staining. PRDX6 levels, indexes of ferroptosis, and JAK2/STAT1 pathway were detected by qRT-PCR, Western blot, and biochemical kits. DOX promoted heart weight/body weight, increased inflammation and collagen deposition, increased PTGS2 and MDA levels, and decreased SLC7A11, GPX4, FTH1, and PRDX6 levels in myocardium. PRDX6 overexpression reduced PTGS2, MDA, Fe2+, and LDH levels, inhibited JAK2 and STAT1 phosphorylation, and increased SLC7A11, GPX4, and FTH1 levels in DOX-added H9c2 cells. RO8191 and erastin reversed the inhibition of PRDX6 on ferroptosis through the JAK2/STAT1 pathway. Overall, PRDX6 alleviated HF by inhibiting DOX-induced ferroptosis through the JAK2/STAT1 pathway inactivation. [ABSTRACT FROM AUTHOR]

Silicosis is the most common type of pneumoconiosis, having a high incidence in workers chronically exposed to crystalline silica (CS). No specific medication exists for this condition. GHK, a tripeptide naturally occurring in human blood and urine, has antioxidant effects. We aimed to investigate the therapeutic effect of GHK-Cu on silicosis and its potential underlying molecular mechanism. An experimental silicosis mouse model was established to observe the effects of GHK-Cu on lung inflammation and fibrosis. Moreover, the effects of GHK-Cu on the alveolar macrophages (AM) were examined using the RAW264.7 cell line. Its molecular target, peroxiredoxin 6 (PRDX6), has been identified, and GHK-Cu can bind to PRDX6, thus attenuating lung inflammation and fibrosis in silicosis mice without significant systemic toxicity. These effects were partly related to the inhibition of the CS-induced oxidative stress in AM induced by GHK-Cu. Thus, our results suggest that GHK-Cu acts as a potential drug by attenuating alveolar macrophage oxidative stress. This, in turn, attenuates the progression of pulmonary inflammation and fibrosis, which provides a reference for the treatment of silicosis.

Vechur is a unique but threatened indigenous cattle breed of Kerala. The use of cryopreserved semen serves long term conservation and improvement of the breed. The fertility of the cryopreserved sperm depends on the ability to withstand the freeze thaw cycle. Oxidative stress and reactive oxygen species (ROS) generated in the spermatozoa during freezing and thawing of frozen semen is considered a major factor responsible for causing infertility due to decrease in sperm quality parameters. Semen ejaculates from 20 Vechur bulls were collected. Bulls consistently producing semen with 70 per cent progressive motility were selected and analysed for cryotolerant sperm. Using conventional liquid Nitrogen method, six bulls exhibiting differential post thaw motility were grouped into Good Freezability Rate (GFR) (40 per cent) and Poor Freezability Rate (PFR) (<40 per cent) Three ejaculates from three bulls in each group were collected and cryopreserved. RNA was isolated from fresh and post thaw semen from two groups. Three candidate genes HSP90AA1, PRDX6 and SOD1 were selected for expression profiling. These genes were reported to be involved in the protection of the sperm from temperature changes, molecular folding (HSP90AA1) and oxidative stress (PRDX6 and SOD1). Relative quantification was performed by qPCR with PPIA as internal control gene. Statistical analysis revealed a significant (p<0.05) downregulation of HSP90AA1 and PRDX6 from fresh to GFR semen. While, there was no significant difference between fresh and GFR in case of SOD1 and a significant (p<0.05) downregulation in PFR from GFR for all the three selected candidate genes were revealed. The current study suggests the three candidate genes can be considered for selecting bulls based on sperm parameters. [ABSTRACT FROM AUTHOR]

Aim: Oxidative stress caused by hyperglycemia, which is the most important complication of diabetes mellitus, causes liver damage. Hydroxytyrosol is a polyphenolic compound abundant in olive oil that protects the liver against oxidative damage. Peroxiredoxin 6 (Prdx6) is an anti-oxidative enzyme known to exist in the liver. The aim of this study was to investigate the effect of hydroxytyrosol on Prdx6 expression in diabetes-induced liver injury. Material and Methods: Male Wistar rats were grouped into four as the control group (n=10), hydroxytyrosol group (n=10), streptozotocin group (n=10), and hydroxytyrosol+streptozotocin group (n=10). Blood glucose levels of the animals were measured after streptozotocin injection and at the end of the experiment. The general structure of the liver was examined with a hematoxylin-eosin stain. Prdx6 protein expression was determined with an immunohistochemical method. Results: In the streptozotocin+hydroxytyrosol group, blood glucose level was found to be lower when compared with the streptozotocin group (p

Abstract Background To explore the relationship of peroxiredoxin6 (PRDX6) tag‐single nucleotide polymorphisms (SNPs) with susceptibility to chronic obstructive pulmonary disease (COPD) in the Chinese Han population. Methods A total of 502 patients with COPD and 481 healthy controls from nine hospitals in China were enrolled in this study. The PRDX6 tag‐SNPs were identified by linkage disequilibrium (LD) analysis in 30 healthy controls. The associations between identified tag‐SNPs and COPD risk were further evaluated. Results Four PRDX6 tag‐SNPs, including rs7314, rs34619706, rs33951697, and rs4382766, were identified in 30 healthy controls. Moreover, in the allele model, there was no statistical difference in locus in PRDX6 between patients with COPD and healthy controls (P > 0.05). However, in the recessive model, rs33951697 locus in PRDX6 gene carrier with T/T had an increased risk of COPD (odds ratio [OR] = 2.59, 95% CI = 1.06–6.33, P = 0.028). Furthermore, in the relevance analysis between genetic polymorphisms and smoking behavior and lung function indexes, we found that the number of smoked cigarettes per day and FEV1/FVC differed among different genotypes of PRDX6, rs4382766, and rs7314 (P

Non-alcoholic fatty liver disease or steatosis is an accumulation of fat in the liver. Increased amounts of non-esterified fatty acids, calcium deficiency, or insulin resistance may disturb endoplasmic reticulum (ER) homeostasis, which leads to the abnormal accumulation of misfolded proteins, activating the unfolded protein response. The ER is the primary location site for chaperones like thioredoxin domain-containing 5 (TXNDC5). Glutathione participates in cellular oxidative stress, and its interaction with TXNDC5 in the ER may decrease the disulfide bonds of this protein. In addition, glutathione is utilized by glutathione peroxidases to inactivate oxidized lipids. To characterize proteins interacting with TXNDC5, immunoprecipitation and liquid chromatography–mass spectrometry were used. Lipid peroxidation, reduced glutathione, inducible phospholipase A2 (iPLA2) and hepatic transcriptome were assessed in the AML12 and TXNDC5-deficient AML12 cell lines. The results showed that HSPA9 and PRDX6 interact with TXNDC5 in AML12 cells. In addition, TXNDC5 deficiency reduced the protein levels of PRDX6 and HSPA9 in AML12. Moreover, lipid peroxidation, glutathione and iPLA2 activities were significantly decreased in TXNDC5-deficient cells, and to find the cause of the PRDX6 protein reduction, proteasome suppression revealed no considerable effect on it. Finally, hepatic transcripts connected to PRDX6 and HSPA9 indicated an increase in the Dnaja3, Mfn2 and Prdx5 and a decrease in Npm1, Oplah, Gstp3, Gstm6, Gstt1, Serpina1a, Serpina1b, Serpina3m, Hsp90aa1 and Rps14 mRNA levels in AML12 KO cells. In conclusion, the lipid peroxidation system and glutathione mechanism in AML12 cells may be disrupted by the absence of TXNDC5, a novel protein–protein interacting partner of PRDX6 and HSPA9. [ABSTRACT FROM AUTHOR]

As one of the common plasticizers, di-n-butyl phthalate (DBP) has been using in various daily consumer products worldwide. Since it is easily released from products and exists in the environment for a long time, it has a lasting impact on human health, especially male reproductive health. However, the detailed mechanism of testicular damage from DBP and the protection strategy are still not clear enough. In this study, we found that DBP could induce dose-dependent ferroptosis in testicular tissue. Mechanism dissection indicates that DBP can upregulate SP1 expression, which could directly transcriptionally upregulate PRDX6, a negative regulator of ferroptosis. Overexpression of PRDX6 or adding SP1 agonist curcumin could suppress the DBP-induced ferroptosis on testicular cells. In vivo, rats were given 500 mg/kg/day DBP orally for 3 weeks; elevated levels of ferroptosis were detected in testicular tissue. When the above-mentioned doses of DBP and curcumin at a dose of 300 mg/kg/day were administered intragastrically simultaneously, the testicular ferroptosis induced by DBP was alleviated. Immunohistochemistry and quantitative real-time PCR of testis tissue showed that the expression of PRDX6 was upregulated under the action of DBP and curcumin. These findings suggest a spontaneous self-protection mechanism of testicular tissue from DBP damage by upregulating SP1 and PRDX6. However, it is not strong enough to resist the DBP-induced ferroptosis. Curcumin can strengthen this self-protection mechanism and weaken the level of ferroptosis induced by DBP. This study may help us to develop a novel therapeutic option with curcumin to protect the testicular tissue from ferroptosis and function impairment by DBP. [ABSTRACT FROM AUTHOR]

Abstract Background Semen cryopreservation is a critical tool for breed improvement and preservation of biodiversity. However, instability of sperm freezability affects its application. The Mediterranean buffalo is one of the river-type buffaloes with the capacity for high milk production. Until now, there is no specific cryopreservation system for Mediterranean buffalo, which influences the promotion of excellent cultivars. To improve the semen freezing extender used in cryopreservation of Mediterranean buffalo, different protein datasets relating to freezability sperm were analyzed by iTRAQ-based proteomics. This study will be beneficial for further understanding the sperm freezability mechanism and developing new cryopreservation strategy for buffalo semen. Results 2652 quantified proteins were identified, including 248 significantly differentially expressed proteins (DEP). Gene Ontology (GO) analysis indicated that many these were mitochondrial proteins, enriched in the molecular function of phospholipase A2 activity and enzyme binding, and biological processes of regulation of protein kinase A signaling and motile cilium assembly. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis identified 17 significant pathways, including oxidative phosphorylation (OXPHOS). Furthermore, 7 DEPs were verified using parallel reaction monitoring or western blot, which confirmed the accuracy of the iTRAQ data. Peroxiredoxin 6 (PRDX6), which expressed 1.72-fold higher in good freezability ejaculate (GFE) compared to poor freezability ejaculate (PFE) sperms, was selected to explore the function in sperm freezability by adding recombinant PRDX6 protein into the semen freezing extender. The results showed that the motility, mitochondrial function and in vitro fertilization capacity of frozen-thawed sperm were significantly increased, while the oxidation level was significantly decreased when 0.1 mg/L PRDX6 was added compared with blank control. Conclusions Above results revealed the metabolic pattern of freezability of Mediterranean buffalo sperms was negatively associated with OXPHOS, and PRDX6 had protective effect on cryo-damage of frozen-thawed sperms.

Background: Accumulating evidences suggest that date palm pollen (DPP) induces antioxidant activity and improvessemen parameters in male rats. However, there is a few scientific evidences in support of the DPP effects on humanmale fertility. Hence, the effect of oral consumption of DPP on sperm parameters and expression pattern of Peroxiredoxin-1 (PRDX1) and Peroxiredoxin-6 (PRDX6) genes was evaluated in men with infertility.Materials and Methods: The current controlled clinical trial included 40 men with infertility (DPP group) and 10 normospermicfertile men as controls. The DPP group received gelatinous capsules of DPP (400 mg/kg) for 74 days. Semensampling was done before and after treatment in the both groups. Semen analysis and 8-isoprostane concentration assessmentswere performed by computer-assisted sperm analysis and ELISA methods, respectively. Quantitative reverse transcriptionpolymerase chain reaction (qRT-PCR) assays were employed to explore expression of PRDX1 and PRDX6 genes.Results: DPP consumption significantly improved semen volume (P=0.030), count (P

Peroxiredoxin 6 (Prdx6), a unique 1-Cys member of the peroxiredoxin family, exhibits peroxidase activity, phospholipase activity, and lysophosphatidylcholine acyltransferase (LPCAT) activity. Prdx6 has been known to be an important enzyme for the maintenance of lipid peroxidation repair, cellular metabolism, inflammatory signaling, and antioxidant damage. Growing research has demonstrated that the altered activity of this enzyme is linked with various pathological processes including central nervous system (CNS) disorders. This review discusses the distinctive structure, enzyme activity, and function of Prdx6 in different CNS disorders, as well as emphasizing the significance of Prdx6 in neurological disorders.

The NADPH oxidase 1 (NOX1) complex formed by proteins NOX1, p22phox, NOXO1, NOXA1, and RAC1 plays an important role in the generation of superoxide and other reactive oxygen species (ROS) which are involved in normal and pathological cell functions due to their effects on diverse cell signaling pathways. Cell migration and invasiveness are at the origin of tumor metastasis during cancer progression which involves a process of cellular de-differentiation known as the epithelial-mesenchymal transition (EMT). During EMT cells lose their polarized epithelial phenotype and express mesenchymal marker proteins that enable cytoskeletal rearrangements promoting cell migration, expression and activation of matrix metalloproteinases (MMPs), tissue remodeling, and cell invasion during metastasis. In this work, we explored the importance of the peroxiredoxin 6 (PRDX6)-NOX1 enzyme interaction leading to NOXA1 protein stabilization and increased levels of superoxide produced by NOX in hepatocarcinoma cells. This increase was accompanied by higher levels of N-cadherin and MMP2, correlating with a greater capacity for cell migration and invasiveness of SNU475 hepatocarcinoma cells. The increase in superoxide and the associated downstream effects on cancer progression were suppressed when phospholipase A2 or peroxidase activities of PRDX6 were abolished by site-directed mutagenesis, reinforcing the importance of these catalytic activities in supporting NOX1-based superoxide generation. Overall, these results demonstrate a clear functional cooperation between NOX1 and PRDX6 catalytic activities which generate higher levels of ROS production, resulting in a more aggressive tumor phenotype.

Diabetes mellitus is a widespread endocrine disease worldwide, accompanying chronic hyperglycemia. In this study, we investigated the effect of hydroxytyrosol, which exerts an antioxidant effect, on the expressions of insulin and peroxiredoxin-6 (Prdx6), which protect cells against oxidative injury in diabetic rat pancreas. This experimental study had four groups with ten animals in each group: control (nondiabetic) group, hydroxytyrosol group [10 mg/kg/day intraperitoneal injection (ip) hydroxytyrosol for 30 days], streptozotocin group (single ip injection of 55 mg/kg streptozotocin), and streptozotocin + hydroxytyrosol group (single ip injection of streptozotocin and ip injection of 10 mg/kg/day hydroxytyrosol for 30 days). During the experiment, blood glucose levels were measured at regular intervals. Insulin expression was determined by immunohistochemistry and Prdx6 expression was determined by immunohistochemistry and western blot. Immunohistochemistry and western blot results were analyzed by one-way ANOVA with applied Holm–Sidak multiple comparison test, and blood glucose results were analyzed by two-way repeated measures ANOVA with applied Tukey's multiple comparison test. Blood glucose levels on days 21 and 28 were significantly lower in the streptozotocin + hydroxytyrosol group compared with the streptozotocin group (day 21, p = 0.049 and day 28, p = 0.003). Expression of both insulin and Prdx6 were lower in the streptozotocin and the streptozotocin + hydroxytyrosol groups compared with the control and hydroxytyrosol groups (p < 0.001). Insulin and Prdx6 expression in the streptozotocin + hydroxytyrosol group were higher compared with the streptozotocin group (p < 0.001). The immunohistochemical findings of Prdx6 and western blot were the same. In conclusion, hydroxytyrosol, which is an antioxidant compound, increased Prdx6 and insulin expression in diabetic rats. Insulin increased by hydroxytyrosol may have been effective in reducing blood glucose levels. Furthermore, hydroxytyrosol may exert its effect on insulin by increasing Prdx6 expression. Thus, hydroxytyrosol may decrease or prevent several hyperglycemia-dependent complications by increasing the expression of these proteins. [ABSTRACT FROM AUTHOR]

Background: To explore the relationship of peroxiredoxin6 (PRDX6) tag‐single nucleotide polymorphisms (SNPs) with susceptibility to chronic obstructive pulmonary disease (COPD) in the Chinese Han population. Methods: A total of 502 patients with COPD and 481 healthy controls from nine hospitals in China were enrolled in this study. The PRDX6 tag‐SNPs were identified by linkage disequilibrium (LD) analysis in 30 healthy controls. The associations between identified tag‐SNPs and COPD risk were further evaluated. Results: Four PRDX6 tag‐SNPs, including rs7314, rs34619706, rs33951697, and rs4382766, were identified in 30 healthy controls. Moreover, in the allele model, there was no statistical difference in locus in PRDX6 between patients with COPD and healthy controls (P > 0.05). However, in the recessive model, rs33951697 locus in PRDX6 gene carrier with T/T had an increased risk of COPD (odds ratio [OR] = 2.59, 95% CI = 1.06–6.33, P = 0.028). Furthermore, in the relevance analysis between genetic polymorphisms and smoking behavior and lung function indexes, we found that the number of smoked cigarettes per day and FEV1/FVC differed among different genotypes of PRDX6, rs4382766, and rs7314 (P < 0.05). Conclusion: PRDX6 gene polymorphism with smoking status may contribute to the etiology of COPD in the Chinese Han population. [ABSTRACT FROM AUTHOR]

Background: Accumulating evidences suggest that date palm pollen (DPP) induces antioxidant activity and improves semen parameters in male rats. However, there is a few scientific evidences in support of the DPP effects on human male fertility. Hence, the effect of oral consumption of DPP on sperm parameters and expression pattern of Peroxiredoxin- 1 (PRDX1) and Peroxiredoxin-6 (PRDX6) genes was evaluated in men with infertility. Materials and Methods: The current controlled clinical trial included 40 men with infertility (DPP group) and 10 normospermic fertile men as controls. The DPP group received gelatinous capsules of DPP (400 mg/kg) for 74 days. Semen sampling was done before and after treatment in the both groups. Semen analysis and 8-isoprostane concentration assessments were performed by computer-assisted sperm analysis and ELISA methods, respectively. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) assays were employed to explore expression of PRDX1 and PRDX6 genes. Results: DPP consumption significantly improved semen volume (P=0.030), count (P<0.001) and morphology of sperm (P=0.023). Concentration of 8-isoprostane was significantly decreased after intervention in the DPP group (P<0.001). DPP consumption led to a significant elevation in the expression of PRDX1 and PRDX6 genes (P<0.001). Elevated gene expression of PRDX6 and PRDX1 was positively correlated with improved parameters of sperm including count, volume, motility and morphology. Conclusion: Taken together, DPP seems to promote sperm quality through a decrease in reactive oxygen species (ROS) by increasing expression of antioxidant genes. Further large-scale studies are required to challenge this hypothesis (registration number: IRCT2015021221014N2) [ABSTRACT FROM AUTHOR]

Aims: Nonalcoholic fatty liver disease (NAFLD) is becoming the most common chronic liver disease globally, which is defined as an excess accumulation of fat caused by the imbalance of lipogenesis and lipid catabolism. Recently, increasing evidence suggests that peroxiredoxin 6 (PRDX6) is involved in the pathogenesis and progression of NAFLD. However, little is known regarding its role in liver lipid catabolism. Results: We found that PRDX6 level was significantly increased in liver tissues after high-fat diet (HFD) treatment. PRDX6 knockout (KO) exacerbated HFD-induced hepatic steatosis. PRDX6 KO did not affect messenger RNA (mRNA) and protein levels of peroxisome proliferator-activated receptor alpha (PPARα). However, PRDX6 KO decreased the mRNA and protein levels of carnitine palmitoyltransferase-1alpha (CPT-1α) and acyl-CoA oxidase 1 (ACOX1), the target genes of PPARα. PRDX6 KO also did not activate AMP-activated protein kinase (AMPK)α/proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α), the upstream signal of PPARα. However, PRDX6 KO reduces the levels of PPARα activators, the oxidized fatty acids (9- and 13-hydroxyoctadecadienoic acid) in HFD rats. More interestingly, PRDX6 promoted the production of oxidized fatty acids by hydrolyzing oxidized low-density lipoprotein (Ox-LDL), which depends on its phospholipase A2 (PLA2) activity. PRDX6 mutation on its PLA2 and its competitive phospholipase inhibitor inhibited the production of the oxidized fatty acids as well as the activation of PPARα. Furthermore, PRDX6 overexpression enhanced the transcriptional activation of PPARα. Innovation and Conclusion: This study elucidates for the first time the role of PLA2 enzyme activity of PRDX6 in fatty acid oxidation and reveals a novel mechanism of PRDX6 involved in liver steatosis. Antioxid. Redox Signal. 38, 1184–1200. [ABSTRACT FROM AUTHOR]

Aim: Oxidative stress caused by hyperglycemia, which is the most important complication of diabetes mellitus, causes liver damage. Hydroxytyrosol is a polyphenolic compound abundant in olive oil that protects the liver against oxidative damage. Peroxiredoxin 6 (Prdx6) is an anti-oxidative enzyme known to exist in the liver. The aim of this study was to investigate the effect of hydroxytyrosol on Prdx6 expression in diabetes-induced liver injury. Material and Methods: Male Wistar rats were grouped into four as the control group (n=10), hydroxytyrosol group (n=10), streptozotocin group (n=10), and hydroxytyrosol+streptozotocin group (n=10). Blood glucose levels of the animals were measured after streptozotocin injection and at the end of the experiment. The general structure of the liver was examined with a hematoxylin-eosin stain. Prdx6 protein expression was determined with an immunohistochemical method. Results: In the streptozotocin+hydroxytyrosol group, blood glucose level was found to be lower when compared with the streptozotocin group (p<0.001), and histopathological findings in hepatocytes were found to decrease. Prdx6 expression was found to be similar in the control and hydroxytyrosol groups (p=0.590). However, it was found to be higher in streptozotocin and streptozotocin+hydroxytyrosol groups (p<0.001). Prdx6 expression of the streptozotocin+hydroxytyrosol group was found lower than the streptozotocin group (p<0.001). Conclusion: Hydroxytyrosol, the anti-oxidative activity of which has been proven in many studies, was found to relieve blood glucose levels in diabetic rats, cause histopathological changes in hepatocytes, and decrease anti-oxidative Prdx6 expression. This decrease suggested that instead of inhibiting Prdx6, hydroxytyrosol reduced oxidative stress irrespective of Prdx6. [ABSTRACT FROM AUTHOR]

Mammalian peroxiredoxin class 6 (Prdx6) are bifunctional enzymes. Non-mammalian Prdx6 enzymes display Cys-based peroxidase activity, but to date their putative phospholipase A₂ (PLA₂ activities) has not been experimentally investigated. Initially, we observed that five non-mammalian Prdx6 enzymes (enzymes from Arabidopsis thaliana (AtPER1), Triticum aestivum (TaPER1), Pseudomonas aeruginosa (PaLsfA) and Aspergillus fumigatus (AfPrx1 and AfPrxC)) present features compatible with PLA₂ activities in mammalian Prdx6 by amino acid sequences alignment and tertiary structure modeling. Employing unilamellar liposomes with tracer amounts of [³H]-1,2-Dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and thin layer chromatography, all the tested non-mammalian Prdx6 enzymes displayed PLA₂ activities, with values ranging from 3.4 to 6.1 nmol/min/mg protein. It was previously shown that Thr177 phosphorylation of human Prdx6 increases its PLA₂ activity, especially at neutral pH. Therefore, we investigated if human Erk2 kinase could also phosphorylate homologous Thr residues in non-mammalian Prdx6 proteins. We observed phosphorylation of the conserved Thr in three out of the five non-mammalian Prdx enzymes by mass spectrometry. In the case of the mitochondrial Prdx6 from A. fumigatus (AfPrxC), we also observed phosphorylation by western blot, and as a consequence, the PLA₂ activity was increased in acidic and neutral conditions by the human Erk2 kinase treatment. The possible physiological meanings of these PLA₂ activities described open new fields for future research.

PurposeTo compare the levels of gene expression for enzymes involved in production and elimination of reactive oxygen/nitrogen species (ROS/RNS) in normal human corneal cells (NL cells) with those in human corneal cells with keratoconus (KC cells) in vitro.MethodsPrimary NL and KC stromal fibroblast cultures were incubated with apocynin (an inhibitor of NADPH oxidase) or N-nitro-L-arginine (N-LLA; an inhibitor of nitric oxide synthase). ROS/RNS levels were measured using an H2 DCFDA fluorescent assay. The RT2 Profiler™ PCR Array for Oxidative Stress and Antioxidant Defense was used for initial screening of the NL and KC cultures. Transcription levels for genes related to production or elimination of ROS/RNS were analyzed using quantitative PCR. Immunohistochemistry was performed on 10 intact human corneas using antibodies against SCARA3 and CPSF3.ResultsArray screening of 84 antioxidant-related genes identified 12 genes that were differentially expressed between NL and KC cultures. Compared with NL cells, quantitative PCR showed that KC cells had decreased expression of antioxidant genes SCARA3 isoform 2 (0.59-fold, P = 0.02) and FOXM1 isoform 1 (0.61-fold, P = 0.03). KC cells also had downregulation of the antioxidant genes SOD1 (0.4-fold, P = 0.0001) and SOD3 (0.37-fold, P = 0.02) but increased expression of SOD2 (3.3-fold, P < 0.0001), PRDX6 (1.47-fold, P = 0.01), and CPSF3 (1.44-fold, P = 0.02).ConclusionThe difference in expression of antioxidant enzymes between KC and NL suggests that the oxidative stress imbalances found in KC are caused by defects in ROS/RNS removal rather than increased ROS/RNS production.

Ferroptosis is type of programmed cell death, which is known to be involved in certain cancers. Notch3 signaling is reported to be involved in the tumorigenesis of non‐small‐cell lung cancer (NSCLC) and regulates iron metabolism, lipid synthesis, and oxidative stress in some tissues. However, whether Notch3 signaling regulates ferroptosis is unclear. In this study, we found that ferroptosis inhibitors, ferrostatin‐1 and liproxstatin‐1, protected against cell death induced by Notch3 knockdown and that Notch3 knockdown initiated ferroptosis in NSCLC cells by increasing reactive oxygen species (ROS) levels, lipid peroxidation, and Fe2+ levels, accompanied by downregulation of glutathione peroxidase 4 (GPX4) and peroxiredoxin6 (PRDX6). Conversely, Notch3 intracellular domain overexpression suppressed erastin‐induced ferroptosis, which was synergistically enhanced by MJ33 in H1299 cells via a decrease in ROS levels and lipid peroxidation, accompanied by upregulation of GPX4 and PRDX6. Moreover, Notch3 knockdown decreased tumorigenesis in vivo with downregulation of GPX4 and PRDX6. In summary, here we have identified Notch3 as a potential negative regulator of ferroptosis in NSCLC.

Intrahepatic cholangiocarcinoma (ICC) has a poor prognosis. The bifunctional protein peroxiredoxin 6 (PRDX6), which has both calcium-independent phospholipase A2 (iPLA2) and glutathione peroxidase (GPx) activity, participates in the development of multiple tumors. However, the function and clinical significance of PRDX6 in ICC remain unclear. In this study, we characterized PRDX6 in both human ICC and thioacetamide (TAA)-induced rat ICC. We found PRDX6 was significantly increased in ICC tissues, compared with the peritumoral tissues, and PRDX6 expression level was positively correlated with the malignant phenotype in ICC patients. Furthermore, PRDX6 genetic knockout significantly inhibited the tumor progression in rats. By using RNA sequencing analysis, we found 127 upregulated genes and 321 downregulated genes after PRDX6 knockout. In addition, we noticed a significant repression in the Wnt7a/b cascade, which has been shown to play an important role in the occurrence of ICC. We confirmed that gene expressions in the Wnt7a/b cascade were inhibited in ICC tissues after PRDX6 knockout by using qRT-PCR and immunohistochemistry analysis. Collectively, our findings suggest that PRDX6 may promote ICC by regulating the Wnt7a/b pathway, which could be a novel therapeutic target for ICC. [ABSTRACT FROM AUTHOR]

The H Ferritin subunit (FTH1), as well as regulating the homeostasis of intracellular iron, is involved in complex pathways that might promote or inhibit carcinogenesis. This function may be mediated by its ability to interact with different molecules. To gain insight into the FTH1 interacting molecules, we analyzed its interactome in HEK293T cells. Fifty-one proteins have been identified, and among them, we focused our attention on a member of the peroxiredoxin family (PRDX6), an antioxidant enzyme that plays an important role in cell proliferation and in malignancy development. The FTH1/PRDX6 interaction was further supported by co-immunoprecipitation, in HEK293T and H460 cell lines and by means of computational methods. Next, we demonstrated that FTH1 could inhibit PRDX6-mediated proliferation and migration. Then, the results so far obtained suggested that the interaction between FTH1/PRDX6 in cancer cells might alter cell proliferation and migration, leading to a less invasive phenotype. [ABSTRACT FROM AUTHOR]

Diabetic neuropathy is regarded as one of the most debilitating outcomes of diabetes. It can affect both the peripheral and central nervous systems, leading to pain, decreased motility, cognitive decline, and dementia. S-palmitoylation is a reversible posttranslational lipid modification, and its dysregulation has been implicated in metabolic syndrome, cancers, neurological disorders, and infections. However, the role of S-palmitoylation in diabetic neuropathy remains unclear. Here we demonstrate a potential association between activating protein palmitoylation and diabetic neuropathy. We compared the proteomic data of lumbar dorsal root ganglia (DRG) of diabetes mice and palmitoylome profiling data of the HUVEC cell line. The mapping results identified peroxiredoxin-6 (PRDX6) as a novel target in diabetic neuropathy, whose biological mechanism was associated with S-palmitoylation. Bioinformatic prediction revealed that PRDX6 had two palmitoylation sites, Cys47 and Cys91. Immunofluorescence results indicated PRDX6 translocating between the cytoplasm and cell membrane. Protein function analysis proposed that increased palmitoylation could competitively inhibit the formation of disulfide-bond between Cys47 and Cys91 and change the spatial topology of PRDX6 protein. Cl-HCO3-anion exchanger 3 (AE3) was one of the AE family members, which was proved to express in DRG. AE3 activity evoked Cl-influx in neurons which was generally associated with increased excitability and susceptibility to pain. We demonstrated that the S-palmitoylation status of Cys47 could affect the interaction between PRDX6 and the C-terminal domain of AE3, thereby regulating the activity of AE3 anion exchanger enzyme in the nervous system. The results highlight a central role for PRDX6 palmitoylation in protection against diabetic neuropathy. [ABSTRACT FROM AUTHOR]

Introduction. Peroxiredoxin 6 (Prdx6) is widely expressed in mammalian tissues. Our previous study demonstrated that Prdx6 was expressed in human epididymis, present in human seminal fluid, and in spermatozoa. The protective role of Prdx6 in maintaining the viability and DNA integrity of human spermatozoa was also detected. Here, we demonstrate the potential role and mechanism of Prdx6 in human epididymis epithelial cells (HEECs). Material and methods. Western blotting was used to measure expression levels of key proteins in the Janus kinase//signal transducer and activator of transcription (JAK/STAT) signaling pathway. The malonaldehyde (MDA) levels and antioxidant capacity in HEECs were detected with the commercial kits. Digital gene expression analysis (DGE) was used to identify gene expression patterns in control and Prdx6-interference HEECs. Reverse transcriptase-polymerase chain reaction (RT-PCR) was used to validate the DGE findings. Results. Compared to control HEECs, the expression levels of JAK1, STAT1, phosphorylated JAK1 and STAT1 were significantly increased, while the expression level of SOCS3 was significantly decreased in Prdx6-interference HEECs. The MDA level and total antioxidant capacity in Prdx6-interference HEECs were significantly increased and decreased compared to that of control, respectively. DGE analysis identified 589 up-regulated and 314 down-regulated genes (including Prdx6) in Prdx6-interference HEECs. Thirteen significantly different pathways were identified between the two groups, with the majority of genes belonging to the CCL, CXCL, IL, and IFIT family of proteins and were related to immunity. In particular, the expression levels of IL6, IL6ST, and eighteen IFN-related genes were significantly increased in Prdx6-interference HEECs compared to control HEECs. Conclusions. We found that reduced Prdx6 expression induced higher ROS levels in HEECs, which resulted in the activation of the IL-6 receptor and IFNγ expression to induce the JAK1/STAT1 signaling pathway. (Folia Histochemica et Cytobiologica 2022, Vol. 60, No. 3, 226-236). [ABSTRACT FROM AUTHOR]

Abstract Background Peroxiredoxins (PRDXs) are an antioxidant enzymes protein family involved in several biological functions such as differentiation, cell growth. In addition, previous studies report that PRDXs play critical roles in the occurrence and development of carcinomas. However, few studies have conducted systematic analysis of PRDXs in cancers. Therefore, the present study sought to explore the molecular characteristics and potential clinical significance of PRDX family members in pan cancer and further validate the function of PRDX6 in bladder urothelial carcinoma (BLCA). Methods A comprehensive analysis of PRDXs in 33 types of cancer was performed based on the TCGA database. This involved an analysis of mRNA expression profiles, genetic alterations, methylation, prognostic values, potential biological pathways and target drugs. Moreover, both the gain and loss of function strategies were used to assess the importance and mechanism of PRDX6 in the cell cycle of BLCA. Result Analysis showed abnormal expression of PRDX1-6 in several types of cancer compared to normal tissues. Univariate Cox proportional hazard regression analysis showed that expression levels of PRDX1, PRDX4 and PRDX6 were mostly associated with poor survival of OS, DSS and PFI, and PRDX2 and PRDX3 with favorable survival. In addition, the expression of PRDX genes were positively correlated with CNV and negatively with methylation. Moreover, analysis based on PharmacoDB dataset showed that the augmented levels of PRDX1, PRDX3 and PRDX6 were significantly correlated with EGFR/VEGFR inhibitor drugs. Furthermore, knocking down of PRDX6 inhibited growth of cancer cells through the JAK2-STAT3 in bladder cell lines. Conclusions PRDXs are potential biomarkers and therapeutic targets for several carcinomas, especially for BLCA. In addition, PRDX6 could regulate proliferation of cancer cell via JAK2-STAT3 pathway and involve into the process of cell cycle in BLCA.

Changes in intracellular reactive oxygen species (ROS) levels due to remodeling of antioxidant defense can affect the status of biological homeostasis in aging/oxidative stress. Peroxiredoxin 6 (Prdx6), an antioxidant gene downstream target for the Nrf2 pathway, plays a role in regulating ROS homeostasis. Using aging human (h) lens epithelial cells (LECs) or Prdx6-deficient (Prdx6−/−) mouse (m) LECs, here we showed that dichlorofluorescein (DCF) oxidation or H2O2 were strictly controlled by Prdx6. We observed that a moderate degree of oxidative stress augmented Nrf2-mediated Prdx6 expression, while higher doses of H2O2 (≥100 µM) caused a dramatic loss of Prdx6 expression, resulting in increased DCF oxidation and H2O2 amplification and cell death. Mechanistically, at increased oxidative stress, Nrf2 upregulated transcriptional factor Klf9, and that Klf9 bound to the promoter and repressed the Prdx6 gene. Similarly, cells overexpressing Klf9 displayed Klf9-dependent Prdx6 suppression and DCF oxidation with H2O2 amplification, while ShKlf9 reversed the process. Our data revealed that H2O2 and DCF oxidation levels play a hormetical role, and the Nrf2-Klf9-Prdx6 pathway is pivotal for the phenomena under the conditions of oxidative load/aging. On the whole, the results demonstrate that oxidative hormetical response is essentially based on levels of oxidative triggering and the status of Klf9-Prdx6 pathway activation; thus, Klf9 can be considered as a therapeutic target for hormetic shifting of cellular defense to improve protective resilience to oxidative stress. [ABSTRACT FROM AUTHOR]

Hao Li,1,* Donghua Zhang,2,* Bo Li,3 Honghua Zhen,4 Wenping Chen,4 Qingjuan Men5 1Department of Blood Transfusion, Shandong Provincial Hospital Affiliated with Shandong First Medical University, Shandong, 271016, People’s Republic of China; 2Department of Oncology, Zhangqiu People’s Hospital Shandong Province, Shandong, 250200, People’s Republic of China; 3Department of Orthopaedics, Central Hospital of XinWen Mining Group Co., Ltd., Shandong, 271233, People’s Republic of China; 4Department of Cardiothoracic Surgery, Zhangqiu District People’s Hospital, Jinan City, Shandong Province, 250200, People’s Republic of China; 5Clinical Laboratory, People’s Hospital of Juxian, Shandong, 276500, People’s Republic of China*These authors contributed equally to this workCorrespondence: Qingjuan MenClinical Laboratory, People’s Hospital of Juxian, No. 151 Shennong Road, Ju County, Rizhao City, Shandong, 276500, People’s Republic of ChinaTel +86 633-6889864Email qingjuanmen2020@163.comPurpose: Peroxiredoxin-6 (PRDX6) is frequently found in various cancers. However, its expression and relevance to proliferation, invasion, and migration in human non-small-cell lung cancer (NSCLC) remain unclear. This study investigated the role and novel mechanism of PRDX6 in progression in an NSCLC cell line (A549).Methods: We analyzed the expression of PRDX6 in NSCLC and adjacent normal tissues and explored the proliferation, migration, and invasion of A549 cells using either a PRDX6 plasmid or PRDX6 small interfering RNA (siRNA). We also assessed the effects of PRDX6 on the epithelial–mesenchymal transition (EMT) and β-catenin-mediated transcription of target genes.Results: PRDX6 expression was markedly higher in NSCLC tissues than in adjacent tissues. Proliferation, invasion, and migration of A549 cells were promoted by overexpression of PRDX6 but inhibited by its silencing. PRDX6 overexpression inhibited the protein expression of both phosphorylated β-catenin and E-cadherin, as well as the expression of vimentin, TWIST, and downstream targets of β-catenin including c-MYC, TCF-4, and MMP14. Conversely, PRDX6 silencing markedly decreased the expression of c-MYC, TCF-4, and MMP14, and inhibited EMT in A549 cells. Overexpression of PRDX6 in vivo notably increased the volume and weight of tumors.Conclusion: PRDX6 overexpression promotes the proliferation, invasion, and migration of A549 cells in vitro and in vivo.Keywords: PRDX6, non-small-cell lung cancer, β-catenin, metastasis, epithelial–mesenchymal transition

Background and Aims: The exosomal long noncoding RNAs (lncRNAs) have been reported to have cardioprotective effects on ischemia-reperfusion (I/R) injury by hindering ferroptosis, but the role of lncRNA Mir9-3 host gene (Mir9-3hg) in cardiac I/R injury remains unclear.Methods and Results: Exosomes were extracted from mouse bone marrow mesenchymal stem cells (BMSCs) and identified by detecting the exosome specific marker levels, and the results showed that Mir9-3hg was highly expressed in BMSCs-Exo. Hypoxia/reoxygenation (H/R)-treated HL-1 mouse cardiomyocytes were incubated with exosomes extracted from BMSCs transfected with Mir9-3hg siRNA. BMSCs-Exo incubation observably facilitated cell proliferation, increased glutathione (GSH) content, and reduced iron ion concentration, reactive oxygen species (ROS) level and ferroptosis marker protein levels in H/R-treated cells, while interfering Mir9-3hg reversed these effects. RNA binding protein immunoprecipitation assay was found that Mir9-3hg bound with pumilio RNA binding family member 2 (Pum2) protein and downregulated Pum2 expression. Silence of Pum2 reversed the effects of Mir9-3hg inhibition on cell functions. Chromatin immunoprecipitation assay was revealed that Pum2 bound with peroxiredoxin 6 (PRDX6) promoter and restrained PRDX6 expression. Silence of PRDX6 reversed the improved effects of Pum2 downregulation on cell functions. Additionally, BMSCs-Exo treatment ameliorated cardiac function in I/R-treated mice by inhibiting cardiomyocyte ferroptosis.Conclusions: BMSCs-Exo treatment attenuates I/R-induced cardiac injury by inhibiting cardiomyocyte ferroptosis through modulating the Pum2/PRDX6 axis, thereby ameliorating cardiac function. [ABSTRACT FROM AUTHOR]

Silicosis is the most common type of pneumoconiosis, having a high incidence in workers chronically exposed to crystalline silica (CS). No specific medication exists for this condition. GHK, a tripeptide naturally occurring in human blood and urine, has antioxidant effects. We aimed to investigate the therapeutic effect of GHK-Cu on silicosis and its potential underlying molecular mechanism. An experimental silicosis mouse model was established to observe the effects of GHK-Cu on lung inflammation and fibrosis. Moreover, the effects of GHK-Cu on the alveolar macrophages (AM) were examined using the RAW264.7 cell line. Its molecular target, peroxiredoxin 6 (PRDX6), has been identified, and GHK-Cu can bind to PRDX6, thus attenuating lung inflammation and fibrosis in silicosis mice without significant systemic toxicity. These effects were partly related to the inhibition of the CS-induced oxidative stress in AM induced by GHK-Cu. Thus, our results suggest that GHK-Cu acts as a potential drug by attenuating alveolar macrophage oxidative stress. This, in turn, attenuates the progression of pulmonary inflammation and fibrosis, which provides a reference for the treatment of silicosis., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Satellite cell‐dependent skeletal muscle regeneration declines during aging. Disruptions within the satellite cells and their niche, together with alterations in the myofibrillar environment, contribute to age‐related dysfunction and defective muscle regeneration. In this study, we demonstrated an age‐related decline in satellite cell viability and myogenic potential and an increase in ROS and cellular senescence. We detected a transient upregulation of miR‐24 in regenerating muscle from adult mice and downregulation of miR‐24 during muscle regeneration in old mice. FACS‐sorted satellite cells were characterized by decreased levels of miR‐24 and a concomitant increase in expression of its target: Prdx6. Using GFP reporter constructs, we demonstrated that miR‐24 directly binds to its predicted site within Prdx6 mRNA. Subtle changes in Prdx6 levels following changes in miR‐24 expression indicate miR‐24 plays a role in fine‐tuning Prdx6 expression. Changes in miR‐24 and Prdx6 levels were associated with altered mitochondrial ROS generation, increase in the DNA damage marker: phosphorylated‐H2Ax and changes in viability, senescence, and myogenic potential of myogenic progenitors from mice and humans. The effects of miR‐24 were more pronounced in myogenic progenitors from old mice, suggesting a context‐dependent role of miR‐24 in these cells, with miR‐24 downregulation likely a part of a compensatory response to declining satellite cell function during aging. We propose that downregulation of miR‐24 and subsequent upregulation of Prdx6 in muscle of old mice following injury are an adaptive response to aging, to maintain satellite cell viability and myogenic potential through regulation of mitochondrial ROS and DNA damage pathways. [ABSTRACT FROM AUTHOR]

Background: Peroxiredoxins (PRDXs) are an antioxidant enzymes protein family involved in several biological functions such as differentiation, cell growth. In addition, previous studies report that PRDXs play critical roles in the occurrence and development of carcinomas. However, few studies have conducted systematic analysis of PRDXs in cancers. Therefore, the present study sought to explore the molecular characteristics and potential clinical significance of PRDX family members in pan cancer and further validate the function of PRDX6 in bladder urothelial carcinoma (BLCA). Methods: A comprehensive analysis of PRDXs in 33 types of cancer was performed based on the TCGA database. This involved an analysis of mRNA expression profiles, genetic alterations, methylation, prognostic values, potential biological pathways and target drugs. Moreover, both the gain and loss of function strategies were used to assess the importance and mechanism of PRDX6 in the cell cycle of BLCA. Result: Analysis showed abnormal expression of PRDX1-6 in several types of cancer compared to normal tissues. Univariate Cox proportional hazard regression analysis showed that expression levels of PRDX1, PRDX4 and PRDX6 were mostly associated with poor survival of OS, DSS and PFI, and PRDX2 and PRDX3 with favorable survival. In addition, the expression of PRDX genes were positively correlated with CNV and negatively with methylation. Moreover, analysis based on PharmacoDB dataset showed that the augmented levels of PRDX1, PRDX3 and PRDX6 were significantly correlated with EGFR/VEGFR inhibitor drugs. Furthermore, knocking down of PRDX6 inhibited growth of cancer cells through the JAK2-STAT3 in bladder cell lines. Conclusions: PRDXs are potential biomarkers and therapeutic targets for several carcinomas, especially for BLCA. In addition, PRDX6 could regulate proliferation of cancer cell via JAK2-STAT3 pathway and involve into the process of cell cycle in BLCA. [ABSTRACT FROM AUTHOR]

Abstract Background Brucellosis is a worldwide zoonotic infectious disease that is transmitted in various ways and causes great harm to humans and animals. The brucellosis pathogen is Brucella, which mainly resides in macrophage cells and survives and replicates in host cells. However, the mechanisms underlying Brucella survival in macrophage cells have not been thoroughly elucidated to date. Peroxiredoxin 6 (Prdx6) is a bifunctional protein that shows not only GSH peroxidase activity but also phospholipase A2 activity and plays important roles in combating oxidative damage and regulating apoptosis. Results Recombinant mouse (Mus musculus) Prdx6 (MmPrdx6) was expressed and purified, and monoclonal antibodies against MmPrdx6 were prepared. Using the Brucella suis S2 strain to infect RAW264.7 murine macrophages, the level of intracellular Prdx6 expression first decreased and later increased following infection. Overexpressing Prdx6 in macrophages resulted in an increase in B. suis S2 strain levels in RAW264.7 cells, while knocking down Prdx6 reduced the S2 levels in cells. Conclusions Host Prdx6 can increase the intracellular survival of B. suis S2 strain and plays a role in Brucella infection.

Hereditary retinal disease (HRD) is the primary retinal degeneration that leads to severe visual impairments and refractory blindness, and the therapy of HRD was most important in ophthalmology. The apoptosis of retinal cells plays important roles in HRD progression. Therefore, in this study, we explore the mechanism of H2O2 and blue light-induced apoptosis of ARPE-19 cells. Co-immunoprecipitation (Co-IP) is employed to test the interactions between proteins, and western blotting is used to detect the protein levels. Apoptosis is analyzed by Flow cytometry. Our results found that PRDX6 could interact with RARA in ARPE-19 cells, and H2O2 and blue light could significantly reduce the RARA protein expression, and also could inhibit the interaction between PRDX6 and RARA. Using a rescue experiment, we further elucidated that H2O2 and blue light reduced the RARA expression via down-regulating PRDX6. And H2O2 and blue light induced the ARPE-19 cell apoptosis via decreasing the expression of PRDX6. Our results suggested that the interaction between PRDX6 and RARA played important roles in the apoptosis of ARPE-19 cells.

Purpose: To compare the levels of gene expression for enzymes involved in production and elimination of reactive oxygen/nitrogen species (ROS/RNS) in normal human corneal cells (NL cells) with those in human corneal cells with keratoconus (KC cells) in vitro. Methods: Primary NL and KC stromal fibroblast cultures were incubated with apocynin (an inhibitor of NADPH oxidase) or N-nitro-L-arginine (N-LLA; an inhibitor of nitric oxide synthase). ROS/RNS levels were measured using an H2DCFDA fluorescent assay. The RT2 Profiler™ PCR Array for Oxidative Stress and Antioxidant Defense was used for initial screening of the NL and KC cultures. Transcription levels for genes related to production or elimination of ROS/RNS were analyzed using quantitative PCR. Immunohistochemistry was performed on 10 intact human corneas using antibodies against SCARA3 and CPSF3. Results: Array screening of 84 antioxidant-related genes identified 12 genes that were differentially expressed between NL and KC cultures. Compared with NL cells, quantitative PCR showed that KC cells had decreased expression of antioxidant genes SCARA3 isoform 2 (0.59-fold, P = 0.02) and FOXM1 isoform 1 (0.61-fold, P = 0.03). KC cells also had downregulation of the antioxidant genes SOD1 (0.4-fold, P = 0.0001) and SOD3 (0.37-fold, P = 0.02) but increased expression of SOD2 (3.3-fold, P < 0.0001), PRDX6 (1.47-fold, P = 0.01), and CPSF3 (1.44-fold, P = 0.02). Conclusion: The difference in expression of antioxidant enzymes between KC and NL suggests that the oxidative stress imbalances found in KC are caused by defects in ROS/RNS removal rather than increased ROS/RNS production.

Background: Neurotoxicity induced by local anesthetics (LAs) is potentially life threatening, especially for patients with underlying diseases like diabetes. The anesthetic bupivacaine (Bup) has been reported to induce neurotoxicity mediated by reactive oxygen species (ROS), which is aggravated by hyperglycemia. Krüppel-like factor 9 (KLF9), an axon growth-suppressing transcription factor, plays a key role in neuronal maturation and promotes oxidative stress. This study was designed to investigate whether and how KLF9 regulates ROS levels related to LA neurotoxicity under hyperglycemic conditions. Methods: Klf9/GFP ShRNA (LV Sh-Klf9) was used to achieve stable Klf9 knockdown in the SH-SY5Y cell line. KLF9-deficient and normal cells were cultured under normal or high-glucose (HG) culture conditions and then exposed to Bup. Cell viability, intracellular and mitochondrial ROS, and mitochondrial membrane potential (ΔΨm) were detected to examine the role of KLF9. Thereafter, KLF9-deficient and normal cells were pretreated with small-interfering RNA targeting peroxiredoxin 6 (siRNA-Prdx6) to determine if PRDX6 was the target protein in HG-aggravated Bup neurotoxicity. Results: The mRNA and protein levels of KLF9 were increased after Bup and hyperglycemia treatment. In addition, cell survival and mitochondrial function were significantly improved, and ROS production was decreased after Sh-Klf9 treatment compared with Sh-Ctrl. Furthermore, the expression of PRDX6 was suppressed by Bup in hyperglycemic cultures and was upregulated in the Sh-Klf9 group. Moreover, the protection provided by KLF9 deficiency for cell survival, the increase in ROS production in cells and mitochondria, and the disruption of mitochondrial function were abolished by Prdx6 knockdown. Conclusions: The results of this study demonstrated that hyperglycemia aggravated Bup neurotoxicity by upregulating KLF9 expression, which repressed the antioxidant PRDX6 and led to mitochondrial dysfunction, ROS burst, and cell death. Understanding this mechanism may, thus, offer valuable insights for the prevention and treatment of neurotoxicity induced by LAs, especially in diabetic patients. [ABSTRACT FROM AUTHOR]

Changes in intracellular reactive oxygen species (ROS) levels due to remodeling of antioxidant defense can affect the status of biological homeostasis in aging/oxidative stress. Peroxiredoxin 6 (Prdx6), an antioxidant gene downstream target for the Nrf2 pathway, plays a role in regulating ROS homeostasis. Using aging human (h) lens epithelial cells (LECs) or Prdx6-deficient (Prdx6−/−) mouse (m) LECs, here we showed that dichlorofluorescein (DCF) oxidation or H2O2 were strictly controlled by Prdx6. We observed that a moderate degree of oxidative stress augmented Nrf2-mediated Prdx6 expression, while higher doses of H2O2 (≥100 µM) caused a dramatic loss of Prdx6 expression, resulting in increased DCF oxidation and H2O2 amplification and cell death. Mechanistically, at increased oxidative stress, Nrf2 upregulated transcriptional factor Klf9, and that Klf9 bound to the promoter and repressed the Prdx6 gene. Similarly, cells overexpressing Klf9 displayed Klf9-dependent Prdx6 suppression and DCF oxidation with H2O2 amplification, while ShKlf9 reversed the process. Our data revealed that H2O2 and DCF oxidation levels play a hormetical role, and the Nrf2-Klf9-Prdx6 pathway is pivotal for the phenomena under the conditions of oxidative load/aging. On the whole, the results demonstrate that oxidative hormetical response is essentially based on levels of oxidative triggering and the status of Klf9-Prdx6 pathway activation; thus, Klf9 can be considered as a therapeutic target for hormetic shifting of cellular defense to improve protective resilience to oxidative stress.

Hypoxia and reperfusion produces overproduction of ROS (reactive oxygen species), which may lead to mitochondrial dysfunction leading to cell death and apoptosis. Here, we explore the hypothesis that Prdx6 protects the spinal cord white matter from hypoxia-reperfusion injury and elucidate the possible mechanism by which Prdx6 elicits its protective effects. Briefly, rats were deeply anesthetized with isoflurane. A 30-mm section of the spinal cord was rapidly removed and placed in cold Ringer's solution (2–4 °C). The dissected dorsal column was exposed to hypoxia with 95% N2 and 5% CO2 and reperfusion with 95% O2 and 5% CO2. The expression of Prdx6 significantly upregulated in white matter after hypoxia compared to the sham group, whereas reperfusion caused a gradual decrease in Prdx6 expression after reperfusion injury. For the first time, our study revealed the novel expression and localized expression of Prdx6 in astrocytes after hypoxia, and possible communication of astrocytes and axons through Prdx6. The gradual increase in Nrf2 expression suggests a negative regulation of Prdx6 through Nrf2 signaling. Furthermore, inhibition of aiPLA2 activity of Prdx6 by MJ33 shows that the regulation of Prdx6 by Nrf2 is mediated through aiPLA2 activity. The present study uncovers a differential distribution of Prdx6 in axons and astrocytes and regulation of Prdx6 in hypoxia-reperfusion injury. The low levels of Prdx6 in reperfusion injury lead to increased inflammation and apoptosis in the white matter; therefore, the results of this study suggest that Prdx6 has a protective role in spinal hypoxia-reperfusion injury. [ABSTRACT FROM AUTHOR]

Introduction: This study aimed to demonstrate the potential of activated leukocyte cell adhesion molecule (ALCAM), hemopexin (HPX), and peroxiredoxin 6 (PRDX6) as urine biomarkers for systemic lupus erythematosus (SLE)., Methods: Urine samples were collected from 138 Korean patients with SLE from the Ajou Lupus Cohort and 39 healthy controls (HC). The concentrations of urine biomarkers were analyzed using enzyme-linked immunosorbent assay kits specific for ALCAM, HPX, and PRDX6, respectively. Receiver operating characteristic (ROC) curve analysis was performed to evaluate the diagnostic utility, and Pearson's correlation analysis was conducted to assess the relationships between the disease activity and urine biomarkers., Results: Patients with SLE and patients with lupus nephritis (LN) showed significantly elevated ALCAM, HPX, and PRDX6 levels compared with HCs. ALCAM, HPX, and PRDX6 showed significant diagnostic values, especially for lupus nephritis (LN), with areas under the receiver operating characteristic curve for LN was 0.850 for ALCAM (95% CI, 0.778-0.921), 0.781 for HPX (95% CI, 0.695-0.867), and 0.714 for PRDX6 (95% CI, 0.617-0.812). Correlation analysis revealed that all proteins were significantly associated with anti-double stranded DNA antibody (ALCAM, r = 0.350, p < 0.001; HPX, r = 0.346, p < 0.001; PRDX6, r = 0.191, p = 0.026) and SLEDAI (ALCAM, r = 0.526, p < 0.001; HPX, r = 0.479, p < 0.001; PRDX6, r = 0.262, p = 0.002). Results from the follow-up of the three biomarker levels in these patients revealed a significant decrease, showing a positive correlation with changes in SLEDAI-2k scores (ALCAM, r = 0.502, p < 0.001; HPX, r = 0.475, p < 0.001; PRDX6, r = 0.245, p = 0.026), indicating their potential as indicators for tracking disease activity., Discussions: Urinary ALCAM, HPX, and PRDX6 levels have diagnostic value and reflect disease activity in Korean patients with SLE, emphasizing their potential for non-invasive monitoring and treatment response evaluation., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision., (Copyright © 2024 Kim, Baek, Jung, Kim, Lee and Suh.)

Background/Aims: Colorectal cancer (CRC) is the third most common type of cancer and the second leading cause of cancer-related deaths worldwide. PRDXs are antioxidant enzymes that play an important role in cell differentiation, proliferation and apoptosis and have diverse functions in malignancy development. However, the mechanism of aberrant overexpression of PRDX6 in CRC remains unclear. Methods: Boyden chamber assay, flow cytometry and a lentiviral shRNA targeting PRDX6 and transient transfection with pCMV-6-PRDX6 plasmid were used to examine the role of PRDX6 in the proliferation capacity and invasiveness of CRC cells. Immunohistochemistry (IHC) with tissue array containing 40 paraffin- embedded CRC tissue specimens and Western blot assays were used to detect target proteins. Results: PRDX6 was significantly up-expressed in different comparisons of metastasis of colorectal adenomas in node-positive CRC (P = 0.03). In in vitro HCT-116, PRDX6 silencing markedly suppressed CRC cell migration and invasiveness while also inducing cell cycle arrest as well as the generation of reactive oxygen species (ROS); specific overexpression of PRDX6 had the opposite effect. Mechanistically, the PRDX6 inactivation displayed decreased levels of PRDX6, N-cadherin, β-catenin, Vimentin, Slug, Snail and Twist-1 through the activation of the PI3K/ AKT/p38/p50 pathways, but they were also significantly inhibited by PRDX6 transfectants. There was also increased transcriptional activation of dimethylation of histone H3 lysine 4 (H3K4me3) of PRDX6 promoter via the activation of the PI3K/Akt/NFkB pathways. Conclusion: Our findings demonstrated that PRDX6 expression plays a characteristic growth-promoting role in CRC metastasis. This study suggests that PRDX6 may serve as a biomarker of node-positive status and may have a role as an important endogenous regulator of cancer cell tumorigenicity in CRC. PRDX6 may also be an effective therapeutic target.

Background and Objectives: Alzheimer's disease is the most common form of dementia. KAT2B (Lysine Acetyltransferase 2B) is a mitochondrial protein known as mitochondria clearing control organ by mitophagy. PRDX6 (Peroxiredoxin 6) is a key regulator of mitophagy and plays a critical role in maintaining mitochondrial ROS (Reactive oxygen species) homeostasis. Therefore, the purpose of this study was to investigate the effect of swimming endurance training on expression of PRDX6 and KAT2B genes in male hippocampus model of Wistar rat after induction of Alzheimer's. Materials and Methods: In this experimental study, 18 rats were randomly divided into 3 groups including control, Alzheimer's and exercise-Alzheimer's groups. The Alzheimer's model was created by injecting beta 42-1 amyloid into the CA1 hippocampus region, and the training group rats participated in the swimming 30 min/day for a period of 3 weeks. In order to confirm the Alzheimer's model, thioflavin staining was used, and Real Time PCR method was used to determine the expression of the desired genes. One-way ANOVA with Tukey's post-hoc test was used for data analysis. Results: There was a significant difference between the amount of beta-amyloid plaques in the two groups of Alzheimer's and control (p<0.001). Alzheimer's disease significantly reduced the expression of PRDX6 and KAT2B genes in the Alzheimer's rats hippocampus (p<0.001), and also following the endurance exercise, the PRDX6 gene expression increased compared with the Alzheimer's group (p=0.027). Conclusion: Endurance training can possibly maintain oxidative balance and improve mitochondrial hemostasis in Alzheimer's disease. [ABSTRACT FROM AUTHOR]

Objective To investigate the effects of peroxidase 6(Prdx6) on the proliferation and differentiation of neural stem cells. Methods(1) Neural stem cells were isolated from the brain of newborn SD rats by suspension culture and passed to the third generation for immunofluorescence detection of specific protein nestin(Nestin). (2) Cell experiment group: solvent, Prdx6 1 ng/mL, 10 ng/ mL, 100 ng/mL and 1 μg/mL groups. (3) The number of cells on the first day,the second day, the third day, the fourth day, and the fifth day of each group of cells was counted by trypan blue cell counting method and a growth curve was drawn. (4) In the proliferation experiment, the diameter of the neurospheres were compared between the cells of the cell and The Cell Counting kit-8(CCK-8) was used to compare the absorbance at 450 nm of each group of cells. (5) In the cell differentiation experiment, the number of neuronal marker protein neuron specific enolase(NSE) and glial cell marker protein glial fibrillary acidic protein(GFAP) positive cells was compared by immunofluorescence staining. Results(1) In vitro cultured neural stem cell spheres were obtained. The specific marker protein Nestin was positive for immunofluorescence staining. (2) When the concentration of Prdx6 was 100 ng/mL and 1 μg/mL, the neurosphere diameter, absorbance value and the number of differentiated NSE and GFAP positive cells in the neural stem cells were statistically significant compared with the solvent group（all P＜0.05）. ConclusionThe proper concentration of Prdx6 can promote the proliferation and differentiation of neural stem cells. [ABSTRACT FROM AUTHOR]

Similar to humans, the normal aged rat population is not homogeneous in terms of cognitive function. Two distinct subpopulations of aged Sprague–Dawley rats can be identified on the basis of spatial memory performance in the hole-board paradigm. It was the aim of the study to reveal protein changes relevant to aging and spatial memory performance. Aged impaired (AI) and unimpaired (AU) male rats, 22–24 months old were selected from a large cohort of 160 animals; young animals served as control. Enriched synaptosomal fractions from dentate gyrus from behaviorally characterized old animals were used for isobaric tags labeling based quantitative proteomic analysis. As differences in peroxiredoxin 6 (PRDX6) levels were a pronounced finding, PRDX6 levels were also quantified by immunoblotting. AI showed impaired spatial memory abilities while AU performed comparably to young animals. Our study demonstrates substantial quantitative alteration of proteins involved in energy metabolism, inflammation and synaptic plasticity during aging. Moreover, we identified protein changes specifically coupled to memory performance of aged rats. PRDX6 levels clearly differentiated AI from AU and levels in AU were comparable to those of young animals. In addition, it was observed that stochasticity in protein levels increased with age and discriminate between AI and AU groups. Moreover, there was a significantly higher variability of protein levels in AI. PRDX6 is a member of the PRDX family and well-defined as a cystein-1 PRDX that reduces and detoxifies hydroxyperoxides. It is well-known and documented that the aging brain shows increased active oxygen species but so far no study proposed a potential target with antioxidant activity that would discriminate between impaired and unimpaired memory performers. Current data, representing so far the largest proteomics data set in aging dentate gyrus (DG), provide the first evidence for a probable role of PRDX6 in memory performance.

Objective: To explore the levels of expression and clinical role of peroxiredoxin 6 ( PRDX6 ) in lung adenocarcinoma., Methods: This retrospective study used a series of bioinformatics methods to detect the levels of expression of and mutations in the PRDX6 gene in a range of cancers and lung adenocarcinoma. Immunohistochemistry was used to verify the levels of expression of PRDX6 protein in samples of lung adenocarcinoma compared with normal adjacent tissue. The effect of PRDX6 gene knockdown on the in vitro proliferation of a lung adenocarcinoma cell line was measured. Bioinformatics methods were used to determine the diagnostic value and impact on survival of the PRDX6 gene in patients with lung adenocarcinoma., Results: The results showed that the PRDX6 gene was highly expressed in lung adenocarcinoma and there were five mutations at different sites on the gene. PRDX6 promoted the proliferation of the lung adenocarcinoma cell line. The survival duration of lung adenocarcinoma patients with high levels of PRDX6 gene expression was significantly shorter than that of patients with low PRDX6 gene expression., Conclusion: PRDX6 is highly expressed in lung adenocarcinoma and higher levels of expression of the PRDX6 gene were associated with a poorer prognosis., Competing Interests: Declaration of conflicting interestThe authors declare that there are no conflicts of interest.

Aims: Nonalcoholic fatty liver disease (NAFLD) is accompanied by excessive reactive oxygen species (ROS) production, which has been suggested in several studies to link with mitochondrial function. However, the mechanistic role of ROS-mediated regulation of mitochondrial function in NAFLD has not been elucidated. Since peroxiredoxin 6 (PRDX6) is the only member of the antioxidant PRDX family that translocates to damaged mitochondria, we investigated the PRDX6-mediated antisteatotic mechanism using genetically modified mice and cells. Results: PRDX6 mice were more protective to lipid accumulation, liver injury, and insulin resistance after a high-fat diet. Mechanistically, PRDX6 is required for induction of mitochondrial antioxidant action and beta-oxidation through maintaining mitochondrial integrity and subsequently prevents ROS-induced lipogenesis. Interestingly, oxidative stress-induced Notch signaling was suppressed in PRDX6 mice compared with wild-type mice, and genetic and pharmacological inhibition of Notch signaling improved lipid accumulation. Finally, PRDX knockdown or Notch inhibition reduced induction of mitophagy. PRDX6 antagonizes positive feedback loop between lipid accumulation and ROS production through regulation of mitochondrial function. Innovation: For the first time, we demonstrate that PRDX6 maintains mitochondria integrity under oxidative stress and protects against NAFLD progression by inhibition of Notch signaling. Conclusion: This study describes a novel molecular mechanism underlying the antisteatotic activity of PRDX6, which may be a new therapeutic strategy for the treatment of NAFLD. [ABSTRACT FROM AUTHOR]

Similar to humans, the normal aged rat population is not homogeneous in terms of cognitive function. Two distinct subpopulations of aged Sprague–Dawley rats can be identified on the basis of spatial memory performance in the hole-board paradigm. It was the aim of the study to reveal protein changes relevant to aging and spatial memory performance. Aged impaired (AI) and unimpaired (AU) male rats, 22–24 months old were selected from a large cohort of 160 animals; young animals served as control. Enriched synaptosomal fractions from dentate gyrus from behaviorally characterized old animals were used for isobaric tags labeling based quantitative proteomic analysis. As differences in peroxiredoxin 6 (PRDX6) levels were a pronounced finding, PRDX6 levels were also quantified by immunoblotting. AI showed impaired spatial memory abilities while AU performed comparably to young animals. Our study demonstrates substantial quantitative alteration of proteins involved in energy metabolism, inflammation and synaptic plasticity during aging. Moreover, we identified protein changes specifically coupled to memory performance of aged rats. PRDX6 levels clearly differentiated AI from AU and levels in AU were comparable to those of young animals. In addition, it was observed that stochasticity in protein levels increased with age and discriminate between AI and AU groups. Moreover, there was a significantly higher variability of protein levels in AI. PRDX6 is a member of the PRDX family and well-defined as a cystein-1 PRDX that reduces and detoxifies hydroxyperoxides. It is well-known and documented that the aging brain shows increased active oxygen species but so far no study proposed a potential target with antioxidant activity that would discriminate between impaired and unimpaired memory performers. Current data, representing so far the largest proteomics data set in aging dentate gyrus (DG), provide the first evidence for a probable role of PRDX6 in memory performance. [ABSTRACT FROM AUTHOR]

Aims: Peroxiredoxins (PRDXs) are thiol-specific antioxidant enzymes that regulate redox balance that are critical for maintaining the cellular potential for self-renewal and stemness. Stem cell-based regenerative medicine is a promising approach in tissue reconstruction. However, to obtain functional cells for use in clinical applications, stem cell technology still requires improvements. Results: In this study, we found that PRDX6 levels were decreased during osteogenic differentiation in human dental pulp stem cells (hDPSCs). hDPSCs stably expressing Myc-PRDX6 (hDPSC/myc-PRDX6) inhibited cell growth in hDPSCs during osteogenic differentiation and impaired osteogenic phenotypes such as alkaline phosphatase (ALP) activity, mineralized nodule formation, and osteogenic marker genes [ALP and osteocalcin (OCN)]. hDPSC cell lines stably expressing mutant glutathione peroxidase (PRDX6(C47S)) and independent phospholipase A2 (PRDX6(S32A)) were also generated. Each mutant form of PRDX6 abolished the impaired osteogenic phenotypes, the transforming growth factor-β-mediated Smad2 and p38 pathways, and RUNX2 expression. Furthermore, in vivo experiments revealed that hDPSC/myc-PRDX6 suppressed hDPSC-based bone regeneration in calvarial defect mice, and newborn PRDX6 transgenic mice exhibited delayed bone development and reduced RUNX2 expression. Innovation and Conclusion: These findings illuminate the effects of PRDX6 during osteogenic differentiation of hDPSCs, and also suggest that regulating PRDX6 may improve the clinical utility of stem cell-based regenerative medicine for the treatment of bone diseases. Antioxid. Redox Signal. 30, 1969–1982. [ABSTRACT FROM AUTHOR]