Peroxiredoxin Research Articles

Anti-Oxidant and Pro-Oxidant Effects of Peroxiredoxin 6: A Potential Target in Respiratory Diseases.

Peroxiredoxin 6 (PRDX6) is widely distributed in several organs, especially the lungs. The role of PRDX6 in oxidative stress is controversial and even contradictory, as indicated by research conducted over the past 20 years. PRDX6 has anti-oxidant or pro-oxidant effects on oxidative stress in different diseases. It can even exhibit both anti-oxidant and pro-oxidant effects in the same disease. These findings are attributed to the fact that PRDX6 is a multifunctional enzyme. The peroxidase and phospholipase A2 activity of PRDX6 is closely related to its anti-oxidant and pro-oxidant effects, which leads to the conflicting regulatory effects of PRDX6 on oxidative stress in respiratory diseases. Moreover, PRDX6 interacts with multiple redox signaling pathways to interfere with cell proliferation and apoptosis. PRDX6 has become a new target in respiratory disease research due to its important regulatory role in oxidative stress. In this paper, the role of PRDX6 in oxidative stress in respiratory diseases and the research progress in targeting PRDX6 are reviewed.

Peroxiredoxin 6 alleviates high glucose-induced inflammation and apoptosis in HK-2 cells by inhibiting TLR4/NF-κB signaling.

This research sought to elucidate the effects of peroxiredoxin 6 (PRDX6) on the biological processes in diabetic nephropathy (DN) and to identify the underlying regulatory mechanism related to toll-like receptor 4 (TLR4)/nuclear factor-kappa B (NF-κB) signaling. To induce an in vitro DN cellular model, human kidney 2 (HK-2) cells were treated with high glucose (HG). The mitochondrial membrane potential, adenosine triphosphate level, reactive oxygen species generation, and oxidative stress of the cells were then evaluated. After the PRDX6 level had been determined, the effects of its overexpression on the mitochondrial membrane potential, adenosine triphosphate level, reactive oxygen species generation, and oxidative stress of the cells were assessed. Next, cytochrome c expression, cell viability, cell apoptosis, the inflammatory level, and the TLR4/NF-κB signaling-related factors were assessed. After the addition of the TLR4 activator CRX-527 or the NF-κB activator phorbol 12-myristate 13-acetate (PMA), cell viability, cell apoptosis and the inflammatory level were evaluated again. The results revealed that HG exposure triggered mitochondrial dysfunction and oxidative stress and decreased PRDX6 expression in the HK-2 cells. PRDX6 elevation exacerbated cell viability while alleviating mitochondrial membrane potential loss, oxidative stress, apoptosis, and inflammation in the HG-treated HK-2 cells. Further, PRDX6 inhibited HG-induced TLR4/NF-κB activation. The administration of CRX-527 or PMA reversed the effects of PRDX6 on the cell viability, apoptosis, and inflammation of the HG-exposed HK-2 cells. To conclude, PRDX6 appears to protect HG-exposed HK-2 cells against inflammation and apoptosis by inhibiting TLR4/NF-κB signaling.

Conoidin A Abrogates Growth of Anchorage-Dependent and Anchorage-Independent SKOV3 Ovarian Cancer Cells

Ovarian cancer is one of the leading causes of cancer death in the United States with only 49% of women surviving 5 years after initial diagnosis. Poor screening methods, chemoresistance, and its high metastatic capacity make this disease difficult to treat. Thus, improved treatment methodologies are necessary to improve survival rates and quality of life for ovarian cancer patients. Conoidin A is a water-soluble covalent inhibitor of peroxiredoxin 1 (PRDX1) and peroxiredoxin 2 (PRDX2). While its effects have been primarily studied on parasites, recent studies also begin to elucidate the impacts of conoidin A in other human health conditions, including anticancer effects. However, the anticancer effects and potential utility of conoidin A as a therapeutic, specifically in ovarian cancer, has yet to be investigated. Here, we report that conoidin A eliminates growth of anchorage-dependent and anchorage-independent SKOV3 cells. Furthermore, analyses of clinical samples show increased expression of PRDX1 and PRDX2 in ovarian cancerous tissue, which are the targets of conoidin A. These data identify conoidin A as a potential therapeutic for early and late-stage ovarian cancer and warrants further investigation. (First Online: December 31, 2022)

Peroxiredoxin-3 plays a neuroprotective role in early brain injury after experimental subarachnoid hemorrhage in rats

Subarachnoid hemorrhage (SAH), a type of hemorrhagic stroke, is a neurological emergency associated with a high morbidity and mortality rate. After SAH, early brain injury (EBI) is the leading cause of poor prognosis in SAH patients. Peroxiredoxins (PRDXs) are a family of sulphhydryl-dependent peroxidases. Peroxiredoxin-3 (PRDX3) is mainly located in the mitochondria of neurons, which can remove hydrogen peroxide (H2O2); however, the effect of PRDX3 on EBI after SAH remains unclear. In this study, an endovascular perforation model was used to mimic SAH in Sprague Dawley rats in vivo. The results revealed that after SAH, PRDX3 levels decreased in the neurons. PRDX3 overexpression by neuron-specific adeno-associated viruses upregulated PRDX3 levels. Furthermore, PRDX3 overexpression improved long- and short-term behavioral outcomes and alleviated neuronal impairment in rats. Nissl staining revealed that the upregulation of PRDX3 promoted cortical neuron survival. PRDX3 overexpression decreased the H2O2 content and downregulated caspase-9 expression. In conclusion, PRDX3 participates in neuronal protection by inhibiting the neuronal mitochondria-mediated death pathway; PRDX3 may be an important target for EBI intervention after SAH.

Integrated single-cell transcriptome analysis of CD34 + enriched leukemic stem cells revealed intra- and inter-patient transcriptional heterogeneity in pediatric acute myeloid leukemia

To gain insights into the idiosyncrasies of CD34 + enriched leukemic stem cells, we investigated the nature and extent of transcriptional heterogeneity by single-cell sequencing in pediatric AML. Whole transcriptome analysis of 28,029 AML single cells was performed using the nanowell cartridge-based barcoding technology. Integrated transcriptional analysis identified unique leukemic stem cell clusters of each patient and intra-patient heterogeneity was revealed by multiple LSC-enriched clusters differing in their cell cycle processes and BCL2 expression. All LSC-enriched clusters exhibited gene expression profile of dormancy and self-renewal. Upregulation of genes involved in non-coding RNA processing and ribonucleoprotein assembly were observed in LSC-enriched clusters relative to HSC. The genes involved in regulation of apoptotic processes, response to cytokine stimulus, and negative regulation of transcription were upregulated in LSC-enriched clusters as compared to the blasts. Validation of top altered genes in LSC-enriched clusters confirmed upregulation of TCF7L2, JUP, ARHGAP25, LPAR6, and PRDX1 genes, and serine/threonine kinases (STK24, STK26). Upregulation of LPAR6 showed trend towards MRD positive status (Odds ratio = 0.126; 95% CI = 0.0144-1.10; p = 0.067) and increased expression of STK26 significantly correlated with higher RFS (HR = 0.231; 95% CI = 0.0506-1.052; p = 0.04). Our findings addressed the inter- and intra-patient diversity within AML LSC and potential signaling and chemoresistance-associated targets that warrant investigation in larger cohort that may guide precision medicine in the near future.

Gut microbiota-derived nicotinamide mononucleotide alleviates acute pancreatitis by activating pancreatic SIRT3 signalling.

Gut microbiota dysbiosis induced by acute pancreatitis (AP) exacerbates pancreatic injury and systemic inflammatory responses. The alleviation of gut microbiota dysbiosis through faecal microbiota transplantation (FMT) is considered a potential strategy to reduce tissue damage and inflammation in many clinical disorders. Here, we aim to investigate the effect of gut microbiota and microbiota-derived metabolites on AP and further clarify the mechanisms associated with pancreatic damage and inflammation. AP rat and mouse models were established by administration of caerulein or sodium taurocholate in vivo. Pancreatic acinar cells were exposed to caerulein and lipopolysaccharide in vitro to simulate AP. Normobiotic FMT alleviated AP-induced gut microbiota dysbiosis and ameliorated the severity of AP, including mitochondrial dysfunction, oxidative damage and inflammation. Normobiotic FMT induced higher levels of NAD+ (nicotinamide adenine dinucleotide)-associated metabolites, particularly nicotinamide mononucleotide (NMN). NMN administration mitigated AP-mediated mitochondrial dysfunction, oxidative damage and inflammation by increasing pancreatic NAD+ levels. Similarly, overexpression of the NAD+ -dependent mitochondrial deacetylase sirtuin 3 (SIRT3) alleviated the severity of AP. Furthermore, SIRT3 deacetylated peroxiredoxin 5 (PRDX5) and enhanced PRDX5 protein expression, thereby promoting its antioxidant and anti-inflammatory activities in AP. Importantly, normobiotic FMT-mediated NMN metabolism induced SIRT3-PRDX5 pathway activation during AP. Gut microbiota-derived NMN alleviates the severity of AP by activating the SIRT3-PRDX5 pathway. Normobiotic FMT could be served as a potential strategy for AP treatment.

PRDX3 promotes resistance to cisplatin in gastric cancer cells.

This study aims to investigate peroxiredoxin 3 (PRDX3) expression in gastric cancer tissue and its effects on cisplatin resistance in gastric cancer cells and its possible mechanism. PRDX3 expression in human gastric cancer tissue microarrays was detected via immunohistochemistry. The PRDX3 small interfering RNA (siPRDX3 group) and the negative control siNC (siNC group) were transfected into AGS and MKN-74 cell lines, respectively, whereas a blank control group was set up. Each group was treated with different cisplatin concentrations (0, 5, 10, 15, 20, 25, and 30 μg/ml), and the half-inhibitory concentration (IC50) of each group of the two cell lines was calculated using the CCK8 assay. The corresponding IC50 concentration of the siPRDX3 group in the two cell lines was used to treat cells of each group. Flow cytometry was used to detect cell apoptosis, and Western blotting was used to detect the expression levels of cleaved caspase-3 and Bax in each group. PRDX3 was overexpressed in gastric adenocarcinoma tissue compared with adjacent noncancer tissue (P = 0.0053). After cisplatin treatment, the IC50 in the siPRDX3 group of AGS cells (5.91 ± 0.18 μg/ml) and the siPRDX3 group of MKN-74 cells (3.48 ± 0.30 μg/ml) was significantly lower than in the corresponding siNC groups (10.01 ± 0.99 and 6.39 ± 0.70 μg/ml; P = 0.0022 and 0.0027, respectively). AGS cells (38.81% ± 1.69%) and MKN-74 cells (25.03% ± 2.80%) in the siPRDX3 group showed significantly higher apoptosis rates than in the corresponding siNC groups (23.17% ± 1.43% and 16.7% ± 1.39%; P = 0.0003 and 0.0099, respectively). The expression levels of cleaved caspase-3 and Bax were significantly higher in the siPRDX3 group of both cell lines than in the siNC group (P < 0.0001). PRDX3 increases the gastric cancer cell resistance to cisplatin by reducing apoptosis and thus may serve as a target to overcome cisplatin resistance.

OXIDATIVE STRESS AND REPRODUCTIVE FUNCTION: The protection of mammalian spermatozoa against oxidative stress.

This review focuses on the enzymatic antioxidant mechanisms to fight oxidative stress by spermatozoa, highlighting the differences among mammalian species. We discuss recent evidence about players that promote and fight oxidative stress and the need for novel strategies to diagnose and treat cases of male infertility associated with oxidative damage of the spermatozoon. The spermatozoon is very sensitive to high reactive oxygen species (ROS) levels due to its limited antioxidant system. A consortium of antioxidant enzymes, including superoxide dismutase (SOD), glutathione peroxidases (GPXs), peroxiredoxins (PRDXs), thioredoxins, and glutathione-S-transferases, is necessary to produce healthy spermatozoa and to maintain sperm quality to ensure motility, capacitation, and DNA integrity. A delicate balance between ROS production and antioxidant enzymes is needed to ensure ROS-dependent sperm capacitation. GPX4 is an essential component of the mitochondrial sheath in mammalian spermatozoa, and GPX5 is a crucial antioxidant defence in the mouse epididymis to protect the sperm genome during the maturation of the spermatozoon. The mitochondrial superoxide (O2·-) production is controlled by SOD2, and the hydrogen peroxide (H2O2) generated by SOD2 activity and peroxynitrite (ONOO-) are scavenged mainly by PRDXs in human spermatozoa. PRDXs regulate the redox signalling necessary for sperm motility and capacitation, particularly by PRDX6. This enzyme is the first line of defence against oxidative stress to prevent lipid peroxidation and DNA oxidation by scavenging H2O2 and ONOO- through its peroxidase activity and repairing oxidized membranes by its calcium-independent phospholipase A2 activity. The success of antioxidant therapy in treating infertility resides in the proper diagnosis of the presence of oxidative stress and which type of ROS are produced. Thus, more research on the molecular mechanisms affected by oxidative stress, the development of novel diagnostic tools to identify infertile patients with oxidative stress, and randomized controlled trials are of paramount importance to generate personalized antioxidant therapy to restore male fertility.

Peroxiredoxin 6 Regulates Glia Toxicity in Tau Mediated Neurodegeneration

AbstractBackgroundIn Alzheimer’s disease (AD) neurons, which accumulate hyperphosphorylated tau (p‐tau) are associated with neurodegenerative phenotype microglia (MGnD) and A1 neurotoxic astrocytes. MGnD display reduced ability to phagocytose p‐tau aggregates and neuronal remnants, while their pro‐inflammatory character furthers p‐tau accumulation and neuronal demise. Likewise, A1 astrocytes lose their neuron‐supporting function and promote neurodegeneration. Importantly, MGnD and A1 astrocytes reciprocally stimulate their pathological phenotypes. Factors protecting astrocytes form A1 phenotype transformation are unknown. In this work we explored the role of peroxiredoxin (PRDX) 6 in tau mediated neurodegeneration. PRDX6 is an enzymatic protein which in the CNS is unique to astrocytes. It possesses independent glutathione peroxidase and phospholipase 2 enzymatic activities, which confer ability to repair oxidatively damaged cell membranes and cell‐to‐cell signaling.Method MAPT P301S mutant mice (PS19/Prdx6 +/+) were once crossed to Prdx6 ‐/‐ mice and mice homozygous for the knock‐in of the Prdx6 129X1/SvJ allele overexpressing wild‐type PRDX6 to generate novel PS19/Prdx6 +/‐ and PS19/Prdx6 Tg lines, respectively. Eight weeks old PS19/Prdx6 +/‐, PS19/Prdx6 +/+, and PS19/Prdx6 Tg animals show 0.4:1:2 ratio of Prdx6 brain mRNA level, while levels of hTau and Gfap mRNA remain unchanged. Male mice were neuropathologically characterized at the age of 9.5 months.Result PS19/Prdx6 +/‐ mice feature increased hippocampal atrophy and ventricular enlargement and greater p‐tau accumulation compared to PS19/Prdx6 +/+ mice. Contrariwise, PS19/Prdx6 Tg animals show attenuated brain atrophy and p‐tau accumulation. The GFAP+ load used as a marker of global astrocytic activation and the C3+/GFAP+ ratio, used as a surrogate A1 phenotype marker, vary inversely with the Prdx6 gene dose. Likewise, the load of IBA1+ microglia vary inversely with the Prdx6 gene dose, while the CD68+/IBA1+ index, which determines relative microglia phagocytic activity, directly correlates with the Prdx6 expression.ConclusionExacerbation of the pathological phenotype in PS19/Prdx6 +/‐ mice reveals a neuroprotective effect of PRDX6 in tau mediated neurodegeneration, while attenuation of pathology in PS19/Prdx6 Tg mice suggests a merit of therapeutic PRDX6 upregulation. PRDX6 endows astrocytes with resistance to A1 phenotype transition. Astrocytic PRDX6 also reprograms microglia by downregulating their global activation level and selectively promoting phagocytic properties. Comparative analysis of astrocytic and microglia transcriptomic markers across PS19/Prdx6 +/‐, PS19/Prdx6 +/+, and PS19/Prdx6 Tg genotypes is underway.

Brain Tissue-Derived Extracellular Vesicles in Alzheimer's Disease Display Altered Key Protein Levels Including Cell Type-Specific Markers.

Brain tissue-derived extracellular vesicles (bdEVs) play neurodegenerative and protective roles, including in Alzheimer's disease (AD). Extracellular vesicles (EVs) may also leave the brain to betray the state of the CNS in the periphery. Only a few studies have profiled the proteome of bdEVs and source brain tissue. Additionally, studies focusing on bdEV cell type-specific surface markers are rare. We aimed to reveal the pathological mechanisms inside the brain by profiling the tissue and bdEV proteomes in AD patients. In addition, to indicate targets for capturing and molecular profiling of bdEVs in the periphery, CNS cell-specific markers were profiled on the intact bdEV surface. bdEVs were separated and followed by EV counting and sizing. Brain tissue and bdEVs from age-matched AD patients and controls were then proteomically profiled. Total tau (t-tau), phosphorylated tau (p-tau), and antioxidant peroxiredoxins (PRDX) 1 and 6 were measured by immunoassay in an independent bdEV separation. Neuron, microglia, astrocyte, and endothelia markers were detected on intact EVs by multiplexed ELISA. Overall, concentration of recovered bdEVs was not affected by AD. Proteome differences between AD and control were more pronounced for bdEVs than for brain tissue. Levels of t-tau, p-tau, PRDX1, and PRDX6 were significantly elevated in AD bdEVs compared with controls. Release of certain cell-specific bdEV markers was increased in AD. Several bdEV proteins are involved in AD mechanisms and may be used for disease monitoring. The identified CNS cell markers may be useful tools for peripheral bdEV capture.

Mitochondria-originated redox signalling regulates KLF-1 to promote longevity in Caenorhabditis elegans

Alternations of redox metabolism have been associated with the extension of lifespan in roundworm Caenorhabditis elegans, caused by moderate mitochondrial dysfunction, although the underlying signalling cascades are largely unknown. Previously, we identified transcriptional factor Krüppel-like factor-1 (KLF-1) as the main regulator of cytoprotective longevity-assurance pathways in the C. elegans long-lived mitochondrial mutants. Here, we show that KLF-1 translocation to the nucleus and the activation of the signalling cascade is dependent on the mitochondria-derived hydrogen peroxide (H2O2) produced during late developmental phases where aerobic respiration and somatic mitochondrial biogenesis peak. We further show that mitochondrial-inducible superoxide dismutase-3 (SOD-3), together with voltage-dependent anion channel-1 (VDAC-1), is required for the life-promoting H2O2 signalling that is further regulated by peroxiredoxin-3 (PRDX-3). Increased H2O2 release in the cytoplasm activates the p38 MAPK signalling cascade that induces KLF-1 translocation to the nucleus and the activation of transcription of C. elegans longevity-promoting genes, including cytoprotective cytochrome P450 oxidases. Taken together, our results underline the importance of redox-regulated signalling as the key regulator of longevity-inducing pathways in C. elegans, and position precisely timed mitochondria-derived H2O2 in the middle of it.

The deubiquitinase OTUD1 regulates immunoglobulin production and proteasome inhibitor sensitivity in multiple myeloma

Serum monoclonal immunoglobulin (Ig) is the main diagnostic factor for patients with multiple myeloma (MM), however its prognostic potential remains unclear. On a large MM patient cohort (n = 4146), we observe no correlation between serum Ig levels and patient survival, while amount of intracellular Ig has a strong predictive effect. Focused CRISPR screen, transcriptional and proteomic analysis identify deubiquitinase OTUD1 as a critical mediator of Ig synthesis, proteasome inhibitor sensitivity and tumor burden in MM. Mechanistically, OTUD1 deubiquitinates peroxiredoxin 4 (PRDX4), protecting it from endoplasmic reticulum (ER)-associated degradation. In turn, PRDX4 facilitates Ig production which coincides with the accumulation of unfolded proteins and higher ER stress. The elevated load on proteasome ultimately potentiates myeloma response to proteasome inhibitors providing a window for a rational therapy. Collectively, our findings support the significance of the Ig production machinery as a biomarker and target in the combinatory treatment of MM patients.

Abstract 13422: Sotagliflozin, a Dual SGLT-1/2 Inhibitor, Modulated Expression of Endothelial Proteins That Inhibit Reactive Oxygen Species During Inflammation Compared With Empagliflozin

Background: Reactive oxygen species (ROS) generated during endothelial cell (EC) dysfunction contributes to progression of atherosclerosis. The SGLT1/2 inhibitor sotagliflozin (sota) reduced atherothrombotic events and hospitalization for worsening heart failure in patients with diabetes (SCORED, SOLOIST). Unlike selective SGLT2 inhibitors, sotagliflozin significantly reduced ischemic events, including myocardial infarction and stroke. We compared the effects of sota and empagliflozin (empa) on expression of ROS signaling proteins in human vein ECs (HUVECs) challenged with interleukin-6 (IL-6) or lipopolysaccharide (LPS). Methods: HUVECs were treated with sota or empa (100 nM) for 30 minutes and the challenged with IL-6 (12 ng/mL) or LPS (100 ng/mL) for 24 hours. Global proteomic analysis was performed using LC/MS to measure relative expression levels of &gt;1,000 proteins. Only significant (p&lt;0.05) changes in expression between treatment groups &gt;1-fold were included in gene set enrichment analysis (GSEA) of biological pathways. Results: Sota significantly changed expression of 166 and 274 proteins in ECs challenged with IL-6 and LPS, respectively. Empa significantly modulated fewer proteins - 122 and 93 proteins - following challenge with IL-6 and LPS, respectively. GSEA revealed that sota, not empa, modulated proteins related to ROS detoxification within the “cellular response to oxidative stress” pathway (GO:0034599) compared to both IL-6 and LPS (pathway adjusted p-values = 0.0016 and 0.036, respectively). Within this pathway, sota increased expression of peroxiredoxin (PRDX) 5 and PRDX6 (1.2 and 1.1-fold) and glutathione peroxidase-1 (GPX1, 1.1-fold) relative to IL-6 alone. Relative to LPS, sota decreased expression GPX1 (1.2-fold), PRDX1 (1.1-fold), and increased thioredoxin (1.1-fold). None of these proteins were modulated significantly by empa. Conclusions: Sota significantly modulated expression of proteins linked to ROS detoxification and signaling in human ECs during inflammation compared to a selective SGLT2 inhibitor. These favorable effects of dual SGLT1/2 inhibition may have implications for inflammation and reduced atherothrombotic risk as demonstrated in outcome trials.

Plant thiol peroxidases as redox sensors and signal transducers in abiotic stress acclimation.

The temporal and spatial patterns of reactive oxygen species (ROS) in cells and tissues decisively determine the plant acclimation response to diverse abiotic and biotic stresses. Recent progress in developing dynamic cell imaging probes provides kinetic information on changes in parameters like H2O2, glutathione (GSH/GSSG) and NAD(P)H/NAD(P)+, that play a crucial role in tuning the cellular redox state. Central to redox-based regulation is the thiol-redox regulatory network of the cell that integrates reductive information from metabolism and oxidative ROS signals. Sensitive proteomics allow for monitoring changes in redox-related posttranslational modifications. Thiol peroxidases act as sensitive peroxide and redox sensors and play a central role in this signal transduction process. Peroxiredoxins (PRX) and glutathione peroxidases (GPX) are the two main thiol peroxidases and their function in ROS sensing and redox signaling in plants is emerging at present and summarized in this review. Depending on their redox state, PRXs and GPXs act as redox-dependent binding partners, direct oxidants of target proteins and oxidants of thiol redox transmitters that in turn oxidize target proteins. With their versatile functions, the multiple isoforms of plant thiol peroxidases play a central role in plant stress acclimation, e.g. to high light or osmotic stress, but also in ROS-mediated immunity and development.

Dihydromyricetin ameliorates social isolation-induced anxiety by modulating mitochondrial function, antioxidant enzymes, and BDNF

Stress has been implicated in the etiology of neurological and psychological illnesses. Chronic social isolation (SI) is a psychological stressor that provokes neurobehavioral changes associated with psychiatric disorders, including anxiety disorders. Mitochondria dysfunction and oxidative stress are hallmarks of anxiety pathogenesis. Here we demonstrate the effects of SI-induced stress on mitochondrial function, antioxidative enzymes, autophagy, and brain derivative neurotrophic factor (BDNF). SI induced a reduction in electron transport chain subunits C–I, C-II, and C-VI and an increase in hydrogen peroxide. Treatment with dihydromyricetin (DHM), extracted from Ampelopsis grossedentata, counteracted these changes. A dramatic increase in several primary mitochondrial antioxidative enzymes such as superoxide dismutase 2 (SOD2), heme oxygenase-1 (HO-1), peroxiredoxin-3 (PRDX3), and glutathione peroxidase 4 (GPX4) was observed after SI and a repeated episode of SI. Both SI and repeated SI induced a reduction in sequestosome 1 (SQSTM1/p62). However, only repeated SI modulated autophagy primary protein beclin-1 (Bcl-1). In addition, SI and repeated SI modulated the BDNF-TrkB signaling pathway and the phosphorylation of the downstream extracellular signal-regulated MAP kinase1/2 (p-Erk p42 and p-Erk p44) cascade. DHM treatment ameliorated these changes. Collectively, we demonstrated that DHM treatment counteracted the effects of SI and repeated SI on antioxidative enzymes, autophagy, and the BDNF-TrkB signaling pathway. These findings highlight the molecular mechanisms that partially explain the anxiolytic effects of DHM.

PRDX6 inhibits hepatic stellate cells activation and fibrosis via promoting MANF secretion

Hepatic fibrosis is a chronic inflammatory process with hepatic stellate cells (HSCs) activation. Peroxiredoxin 6 (PRDX6), a multifunctional protein, was reported to protect against liver injury induced by ischemia/reperfusion and high-fat diet. However, the effect of PRDX6 on hepatic fibrosis remains unclear. Male Sprague-Dawley rats were treated with carbon tetrachloride (CCl4) for 4–8 weeks to induce hepatic fibrosis. Here, we found that PRDX6 was mainly expressed in hepatocytes and significantly upregulated in CCl4-induced liver fibrosis. To clarify the impact of PRDX6 in hepatic fibrosis, we constructed a PRDX6 knockout (PRDX6-/-) rat model by using CRISPR/Cas9 method. We found that PRDX6 deficiency accelerated CCl4-induced liver fibrosis. Furthermore, we found that PRDX6 knockout promoted α-SMA expression in normal and fibrotic conditions, especially in hepatic fibrosis. PRDX6 knockout significantly upregulated Col1α1 and Col3α1 in fibrotic tissues. To explore the underlying mechanisms, we identified mesencephalic astrocyte-derived neurotrophic factor (MANF), a suppressor for hepatic fibrosis and NF-κB pathway, as an interacting protein of PRDX6. PRDX6 promoted MANF secretion by binding to the C-terminus of MANF, which did not depend on its peroxidase and PLA2 activities. Similarly, MANF increased PRDX6 protein level and promoted its secretion. Additionally, PRDX6 knockout increased p65 level either in cytoplasm or nuclei in HSCs under fibrotic condition. In conclusion, PRDX6 is an effective inhibitor for hepatic fibrosis through a non-enzymic dependent interacting with MANF, which will offer a potential target for hepatic fibrosis therapy.

Telomere shortening in hypertensive heart disease depends on NOX2-mediated loss of PRDX1 and oxidative DNA damage

Abstract Background Heart failure (HF) coincides with cardiomyocyte telomere shortening. Arterial hypertension is the most prominent risk factor for HF. Both HF and arterial hypertension are associated with dysregulation of the neurohormonal axis and increased ROS. However, how neurohormonal activation is linked to telomere shortening in the pathogenesis of HF is incompletely understood. Further, recent findings suggest that peroxiredoxin 1 (PRDX1) can act as a telomere specific antioxidant. Methods To induce hypertensive HF, male C57BL/6J mice were subjected to AngII-infusion, uninephrectomy and high-salt (AngII++) for 5 weeks. Cardiac function was assessed by ultrasound. Mouse adult cardiomocytes (CMs) isolated from C57BL/6J mice and mice lacking the NADPH-oxidase (NOX) 2/gp91phox as well as rat ventricular CM-derived cells (H9C2) were stimulated with AngII. Telomere length was quantified by Q-FISH after staining with a C-rich telomere probe (TelC). DNA/RNA-damage was evaluated after staining for Oxo-8-Gua (8-oxo-7,8-dihydroguanine) and Oxo-8-G (8-oxo-7,8-dihydroguanosine). Superoxide (O2-) was quantified by 2-hydroxyethidium (2-HE) using HPLC analysis. Colocalization of Oxo-8-Gua and TelC was quantified by automated image analysis. (Sub)cellular and tissue expression of gp91phox/Nox2 and PRDX1 was evaluated by ICC/IHC. All image quantification was conducted semiautomatically. Results In mice subjected to hypertensive HF, CM telomere shortening correlated significantly with both left ventricular (LV) dilatation and impairment of LV systolic function, paralleled by a significant loss of myocardial PRDX1 and significantly increased myocardial DNA/RNA-damage. Similarly, CMs stimulated with AngII exhibited significant telomere shortening, significant loss of PRDX1 and significantly increased DNA/RNA-damage, together with significantly increased CM superoxide production and significantly increased expression of the superoxide generating enzyme gp91phox/NOX2. Correspondingly, deficiency of gp91phox/NOX2 significantly prevented AngII-induced CM telomere shortening, DNA/RNA-damage and PRDX1-depletion. A similar effect could be observed upon stimulation of CMs with the specific histone deacetylase (HDAC) 6-inhibitor tubastatin, which prevents deacetylation of PRDX1. Conclusion We could provide first evidence that in heart failure, ROS originating from increased NOX2-activity leads to depletion of the telomere-targeted antioxidant and repair-protein PRDX1, which results in damage to the telomeric DNA. Both depletion of NOX2 as well as harnessing the intrinsic antioxidant defense by stabilizing PRDX1 via HDAC6-inhibition prevented CM telomere shortening and could be further evaluated as potential therapeutic targets to address heart failure. Funding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): German Federal Ministry for Education and Research

MiR-375 suppresses the growth and metastasis of esophageal squamous cell carcinoma by targeting PRDX1.

Esophageal cancer (EC) is one of the most lethal cancers. Esophageal squamous cell carcinoma (ESCC) is the most common histological subtype in Asian people. Diverse microRNAs, such as miR-375, have been confirmed to be involved in the process of tumorigenesis and metastasis. However, the underlying mechanism through which miR-375 acts in ESCC patients remains unknown. We used The Cancer Genome Atlas (TCGA) database to analyze the association between miR-375 and the survival rate in patients with esophageal squamous cell carcinoma. Real Time quantitative PCR (RT-qPCR) analysis was performed to evaluate the level of miR-375 in EC tissues and cells. A luciferase reporter assay was used to confirm the target gene of miR-375. A colony formation assay as well as flow cytometric and transwell invasion experiments were employed to examine the effects of miR-375 and peroxiredoxin 1 (PRDX1) on ESCC cells. A tumor xenograft mouse model was then used to investigate the role of miR-375 on tumor growth in vivo. Moreover, we performed rescue experiments to evaluate the effect of PRDX1 on ESCC progression. miR-375 expression was significantly downregulated in both ESCC clinical tissues and serum, and the reduction of miR-375 was remarkably linked to a poor prognosis in ESCC. Further investigation illustrated that aberrant expression of miR-375 dampened the growth and infiltration of ESCC cells both in vitro and in vivo. Bioinformatics and luciferase reporter analysis verified that the transcript of PRDX1 is a direct target of miR-375 and its expression in ESCC cells was found to be inversely modulated by miR-375. Moreover, the tumor formation experiment in nude mice confirmed that miR-375 can effectively dampen tumor growth in xenograft tumor mice models. Notably, over-expression of PRDX1 effectively counteracted the tumor-suppressing capabilities of miR-375. We demonstrated the antitumor effect of miR-375 on ESCC by targeting PRDX1 both in vitro and in vivo.

Telomere Shortening in Hypertensive Heart Disease Depends on Oxidative DNA Damage and Predicts Impaired Recovery of Cardiac Function in Heart Failure.

Heart failure (HF) coincides with cardiomyocyte telomere shortening. Arterial hypertension is the most prominent risk factor for HF. Both HF and arterial hypertension are associated with dysregulation of the neurohormonal axis. How neurohormonal activation is linked to telomere shortening in the pathogenesis of HF is incompletely understood. Cardiomyocyte telomere length was assessed in a mouse model of hypertensive HF induced by excess neurohormonal activation (AngII [angiotensin II] infusion, high salt diet, and uninephrectomy), in AngII-stimulated cardiomyocytes and in endomyocardial biopsies from patients with HF. Superoxide production, expression of NOX2 (NADPH oxidase 2) and PRDX1 (peroxiredoxin 1) and HDAC6 (histone deacetylase 6) activity were assessed. Telomere shortening occurred in vitro and in vivo, correlating with both left ventricular (LV) dilatation and LV systolic function impairment. Telomere shortening coincided with increased superoxide production, increased NOX2 expression, increased HDAC6 activity, loss of the telomere-specific antioxidant PRDX1, and increased oxidative DNA-damage. NOX2 knockout prevented PRDX1 depletion, DNA-damage and telomere shortening confirming this enzyme as a critical source of reactive oxygen species. Cotreatment with the NOX inhibitor apocynin ameliorated hypertensive HF and telomere shortening. Similarly, treatment with the HDAC6 inhibitor tubastatin A, which increases PRDX1 bioavailability, prevented telomere shortening in adult cardiomyocytes. To explore the clinical relevance of our findings, we examined endomyocardial biopsies from an all-comer population of patients with HF with reduced ejection fraction. Here, cardiomyocyte telomere length predicted the recovery of cardiac function. Cardiomyocyte telomere shortening and oxidative damage in heart failure with reduced ejection fraction induced by excess neurohormonal activation depends on NOX2-derived superoxide and may help to stratify HF therapy.

Identification of differentially expressed ferroptosis-related genes in abdominal aortic aneurysm: Bioinformatics analysis.

PurposeFerroptosis plays a crucial role in the development and progression of abdominal aortic aneurysm (AAA). The aim of this study was to identify differentially expressed genes associated with ferroptosis in AAA through bioinformatics analysis combined with experimental validation.Materials and methodsFirstly, the mRNA expression profile datasets GSE57691 and GSE47472 from Gene Expression Omnibus database were screened, and principal component analysis was carried out. Next, the R software (version 4.0.0) was used to analyze potentially differentially expressed genes associated with AAA and ferroptosis. Subsequently, protein–protein interaction analysis, gene ontology enrichment analysis, and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis were performed on the selected candidate genes. Finally, quantitative real-time polymerase chain reaction (qRT-PCR) was used to detect the expression levels of the first five selected abnormal ferroptosis-related genes in clinical samples obtained from patients with AAA and healthy controls.ResultsBased on the information contained in the two datasets, a total of 20 differentially expressed ferroptosis-related genes (three upregulated genes and 17 downregulated genes) were selected. Protein–protein interaction analysis demonstrated interaction between these genes, while gene ontology enrichment analysis of ferroptosis genes with differential expression indicated that some enrichment items were associated with oxidative stress. The qRT-PCR results showed that the expression levels of interleukin-6 (IL-6), peroxiredoxin 1 (PRDX1), and stearoyl-CoA desaturase (SCD) were consistent with the bioinformatics prediction results obtained from the mRNA chip.ConclusionBioinformatics analysis identified 20 potential ferroptosis-related differentially expressed genes in AAA. Further verification by qRT-PCR showed that IL-6, PRXD1, and SCD might affect the process of AAA by regulating ferroptosis. Our results might assist in further understanding the pathogenesis of AAA and guiding treatment.