Peroxiredoxin 2 deficiency accelerates age-related ovarian failure through the reactive oxygen species-mediated JNK pathway in mice

PINK1 modulates Prdx2 to reduce lipotoxicity-induced apoptosis and attenuate cardiac dysfunction in heart failure mice with a preserved ejection fraction

INTRODUCTION

Heart failure with preserved ejection fraction (HFpEF) is a complex condition characterized by metabolic dysfunction and myocardial lipotoxicity. The roles of PTEN-induced kinase 1 (PINK1) and peroxiredoxin-2 (Prdx2) in HFpEF pathogenesis remain unclear.

OBJECTIVE

This study aimed to investigate the interaction between PINK1 and Prdx2 to mitigate cardiac diastolic dysfunction in HFpEF.

METHODS

In vivo, PINK1-knockout mice and cardiac-specific PINK1-overexpressing transgenic mice were used to establish an HFpEF mouse model via a high-fat diet and L-NAME. Myocardial lipotoxicity was induced by palmitic acid in vitro. Immunoprecipitation, western blotting and immunofluorescence analysis were performed to elucidate the molecular mechanisms involved.

RESULTS

We determined that PINK1 and Prdx2 were downregulated in the HFpEF mouse model. In vivo, PINK1 ablation exacerbated the reduction in Prdx2 expression, worsening cardiac dysfunction in HFpEF mice. Conversely, PINK1 overexpression restored Prdx2 levels and decreased reactive oxygen species and apoptosis, thereby reducing fibrosis and inflammation and ameliorating cardiac diastolic dysfunction in HFpEF mice. In vitro, an interaction between the N-terminal region (amino acids 1-133) of PINK1 and Prdx2 was identified. The overexpression of PINK1 induced Prdx2 expression and effectively attenuated palmitic acid-induced apoptosis through the c-Jun amino-terminal kinase (JNK) and mitogen-activated protein kinase (p38) pathways, whereas siRNA-mediated Prdx2 knockdown abolished the protective effect of PINK1.

CONCLUSION

PINK1 alleviates lipotoxicity-induced myocardial apoptosis and improves diastolic dysfunction in HFpEF through Prdx2, highlighting PINK1 overexpression as a potential therapeutic strategy for HFpEF.

KEY POINTS

Our investigation discloses a pivotal relationship between PINK1 and Prdx2 in the context of HFpEF. Notably, PINK1, in addition to its role in mitochondrial autophagy, can increase Prdx2 expression, effectively remove ROS and attenuate cardiomyocyte apoptosis by modulating the JNK and p38 pathways, thereby alleviating myocardial lipotoxicity and improving HFpEF cardiac function. Our studies offer valuable insights, opening avenues for the development of innovative therapeutic strategies in the prevention and treatment of HFpEF.

Impact of DEHP on mitochondria-associated endoplasmic reticulum membranes and reproductive toxicity in ovary

Di(2-ethylhexyl) phthalate (DEHP) is a widely recognized environmental endocrine disruptor that potentially impacts female reproductive function, although the specific mechanisms leading to such impairment remain unclear. A growing body of research has revealed that the endoplasmic reticulum and mitochondrial function significantly influence oocyte quality. The structure of mitochondria-associated endoplasmic reticulum membranes (MAMs) is crucial for facilitating the exchange of Ca2+, lipids, and metabolites. This study aimed to investigate the alterations in the composition and function of MAMs after DEHP exposure and to elucidate the underlying mechanisms of ovarian toxicity. The female mice were exposed to DEHP at doses of 5 and 500 mg/kg/day for one month. The results revealed that DEHP exposure led to reduced serum anti-Müllerian hormone levels and increased atretic follicles in mice. DEHP induced endoplasmic reticulum stress and disrupted calcium homeostasis in oocytes. Furthermore, DEHP impaired the mitochondrial function of oocytes and reduced their membrane potential, and promoting apoptosis. Similar results were observed in human granulosa cells after exposure to mono-(2-ethylhexyl) phthalate (MEHP, metabolites of DEHP) in vitro. Proteomic analysis and transmission electron microscopy revealed modifications in the functional proteins and structure of the MAMs, and the suppression of oxidative phosphorylation pathways. The findings of this investigation provide a new perspective on the mechanism underlying the reproductive toxicity of DEHP in females.

c-Jun N-terminal kinase signaling in aging

Aging encompasses a wide array of detrimental effects that compromise physiological functions, elevate the risk of chronic diseases, and impair cognitive abilities. However, the precise underlying mechanisms, particularly the involvement of specific molecular regulatory proteins in the aging process, remain insufficiently understood. Emerging evidence indicates that c-Jun N-terminal kinase (JNK) serves as a potential regulator within the intricate molecular clock governing aging-related processes. JNK demonstrates the ability to diminish telomerase reverse transcriptase activity, elevate β-galactosidase activity, and induce telomere shortening, thereby contributing to immune system aging. Moreover, the circadian rhythm protein is implicated in JNK-mediated aging. Through this comprehensive review, we meticulously elucidate the intricate regulatory mechanisms orchestrated by JNK signaling in aging processes, offering unprecedented molecular insights with significant implications and highlighting potential therapeutic targets. We also explore the translational impact of targeting JNK signaling for interventions aimed at extending healthspan and promoting longevity.

Mechanisms of mitochondrial dysfunction in ovarian aging and potential interventions

Mitochondria plays an essential role in regulating cellular metabolic homeostasis, proliferation/differentiation, and cell death. Mitochondrial dysfunction is implicated in many age-related pathologies. Evidence supports that the dysfunction of mitochondria and the decline of mitochondrial DNA copy number negatively affect ovarian aging. However, the mechanism of ovarian aging is still unclear. Treatment methods, including antioxidant applications, mitochondrial transplantation, emerging biomaterials, and advanced technologies, are being used to improve mitochondrial function and restore oocyte quality. This article reviews key evidence and research updates on mitochondrial damage in the pathogenesis of ovarian aging, emphasizing that mitochondrial damage may accelerate and lead to cellular senescence and ovarian aging, as well as exploring potential methods for using mitochondrial mechanisms to slow down aging and improve oocyte quality.

Transcriptomic profiling of human granulosa cells between women with advanced maternal age with different ovarian reserve

BACKGROUND

Age-related diminished ovarian reserve (DOR) is not absolute. Some advanced maternal age (AMA) still have normal ovarian reserve (NOR) and often show better pregnancy outcomes. Exploring the transcriptomic profile of granulosa cells (GCs) in AMA could lead to new ideas for mitigating age-related diminished ovarian reserve.

AIM

This study aimed to analyze the transcriptomic profile of GCs in AMA with different ovarian reserve.

RESULTS

In total, 6273 statistically significant differential expression genes (DEGs) (|log2fc|> 1, q < 0.05) were screened from the two groups, among which 3436 genes were upregulated, and 2837 genes were downregulated in the DOR group. Through Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis, the potential functions of dysregulated genes in AMA with DOR or NOR were predicted. The GO enrichment analysis revealed that the DEGs were mainly enriched in obsolete oxidation-reduction process, mitochondrion, metal ion binding, ATP binding, etc. The KEGG pathway enrichment analysis revealed that the above-mentioned DEGs were mainly enriched in ferroptosis, regulation of actin cytoskeleton, oxidative phosphorylation, etc. Meanwhile, verification of the mRNA expression levels of DEGs revealed the possible involvement of "ferroptosis" in age-related diminished ovarian reserve.

CONCLUSIONS

From a new clinical perspective, we presented the first data showing the transcriptomic profile in GCs between AMA with different ovarian reserve. At the same time, we identified the role of ferroptosis in the GCs of AMA, providing a new biological basis for studying ovarian aging and improving pregnancy outcomes of AMA.

Overexpression of PRDX2 in Adipose-Derived Mesenchymal Stem Cells Enhances the Therapeutic Effect in a Neurogenic Erectile Dysfunction Rat Model by Inhibiting Ferroptosis

Neurogenic erectile dysfunction (NED) is a common and serious complication after pelvic surgery. The clinical translation of adipose-derived mesenchymal stem cell (ADSC) therapies in NED remains a major challenge due to their low survival rate and limited therapeutic effect. Peroxiredoxin 2 (PRDX2) is a member of the peroxidase family that exerts its therapeutic effects by inhibiting oxidative stress (OS) and ferroptosis, and PRDX2 is expected to enhance the therapeutic effect of ADSCs in treating NED. The purpose of this study was to investigate whether PRDX2 could improve the survival of ADSCs and determine whether overexpression of PRDX2 in ADSCs (PRDX2-ADSCs) could enhance the therapeutic effect of NED. This study investigated the potential role of PRDX2-ADSCs through a NED model induced by bilateral cavernous nerve injury (BCNI) and three in vitro models established by H₂O₂-stimulated ADSCs, H₂O₂-stimulated corpus cavernosum smooth muscle cells (CCSMCs), and RSL3-stimulated CCSMCs. We found that PRDX2 could significantly improve the viability of ADSCs by suppressing apoptosis and OS in H₂O₂-stimulated ADSCs. We also found that BCNI triggered ferroptosis of the corpus cavernosum, which was manifested by increased reactive oxygen species (ROS), total iron content, and MDA as well as decreased SOD and GSH. Our results further demonstrated changes in the expression of key proteins (GPX4 and ACSL4) in the ferroptosis pathway, whereas PRDX2-ADSCs ameliorated BCNI-induced erectile dysfunction and ferroptosis of the corpus cavernosum in NED rats. Consistently, PRDX2-ADSCs attenuated OS in H₂O₂-stimulated CCSMCs and inhibited ferroptosis in RSL3-stimulated CCSMCs, as evidenced by the decrease in ROS, total iron content, and MDA and the increase in SOD and GSH together with changes in ferroptosis-related protein (GPX4 and ACSL4) expression. In conclusion, overexpression of PRDX2 in ADSCs enhanced the therapeutic effect in a rat model of neurogenic erectile dysfunction by inhibiting ferroptosis via regulation of the GPX4/ACSL4 axis.

Peroxiredoxin 2 deficiency does not affect insulin resistance and oxidative stress in high-fat diet-fed obese mice

OBJECTIVE

To examine if peroxiredoxin 2 (Prx2) deficiency aggravates high-fat diet-induced insulin resistance.

MATERIAL AND METHODS

Insulin sensitivity was measured in Prx2 knockout (KO) and wild-type (WT) littermates using the hyperinsulinemic-euglycemic clamp.

RESULTS

Whole body glucose turnover, glucose uptake, and levels of glucose transporter 4 (Glut4) protein in the skeletal muscle were found to be lower. This was followed by increased expression of oxidative stress markers in Prx2 KO mice than that in WT mice in the control diet group. Although, a 12-week high-fat diet induced insulin resistance and enhanced oxidative stress in both genotypes, there was no difference between WT and Prx2 KO mice with respect to insulin sensitivity and the level of oxidative stress markers. Accordingly, the levels of phosphorylated Akt and Glut4 were similar between the two genotypes.

CONCLUSION

These results suggest that Prx2 does not affect high-fat diet-induced oxidative stress and insulin resistance in mice.

Peroxiredoxin, Senescence, and Cancer

Peroxiredoxins are multifunctional enzymes that play a key role in protecting cells from stresses and maintaining the homeostasis of many cellular processes. Peroxiredoxins were firstly identified as antioxidant enzymes that can be found in all living organisms. Later studies demonstrated that peroxiredoxins also act as redox signaling regulators, chaperones, and proinflammatory factors and play important roles in oxidative defense, redox signaling, protein folding, cycle cell progression, DNA integrity, inflammation, and carcinogenesis. The versatility of peroxiredoxins is mainly based on their unique active center cysteine with a wide range of redox states and the ability to switch between low- and high-molecular-weight species for regulating their peroxidase and chaperone activities. Understanding the molecular mechanisms of peroxiredoxin in these processes will allow the development of new approaches to enhance longevity and to treat various cancers. In this article, we briefly review the history of peroxiredoxins, summarize recent advances in our understanding of peroxiredoxins in aging- and cancer-related biological processes, and discuss the future perspectives of using peroxiredoxins in disease diagnostics and treatments.

Chronic exposure to propylparaben at the humanly relevant dose triggers ovarian aging in adult mice

Parabens, a type of endocrine-disrupting chemicals, are widely used as antibacterial preservatives in food and cosmetics in daily life. Paraben exposure has gained particular attention in the past decades, owing to its harmful effects on reproductive function. Whether low-dose paraben exposure may cause ovarian damage has been ignored recently. Here, we investigated the effects of chronic low-dose propylparaben (PrPB) exposure on ovarian function. Female C57BL/6J mice were exposed to PrPB at a humanly relevant dose for 8 months. Our results showed that chronic exposure to PrPB at a humanly relevant dose significantly altered the estrus cycle, hormone levels, and ovarian reserve, accelerating ovarian aging in adult mice. These effects are accompanied by oxidative stress enrichment, leading to steroidogenesis dysfunction and acceleration of primordial follicle recruitment. Notably, melatonin supplementation has been shown to protect against PrPB-induced steroidogenesis dysfunction in granulosa cells. Here, we report that daily chronic PrPB exposure may contribute to ovarian aging by altering oxidative stress-mediated JNK and PI3K-AKT signaling regulation, and that melatonin may serve as a pharmaceutical candidate for PrPB-associated ovarian dysfunction.

Direct Imaging of Lipid Metabolic Changes in Drosophila Ovary During Aging Using DO-SRS Microscopy

Emerging studies have shown that lipids and proteins play versatile roles in various aspects of aging. High-resolution in situ optical imaging provides a powerful approach to study the metabolic dynamics of lipids and proteins during aging. Here, we integrated D2O probing and stimulated Raman scattering (DO-SRS) microscopy to directly visualize metabolic changes in aging Drosophila ovary. The subcellular spatial distribution of de novo protein synthesis and lipogenesis in ovary was quantitatively imaged and examined. Our Raman spectra showed that early stages follicles were protein-enriched whereas mature eggs were lipid-enriched. DO-SRS imaging showed a higher protein synthesis in the earlier developing stages and an increased lipid turned over at the late stage. Aged (35 days) flies exhibited a dramatic decrease in metabolic turnover activities of both proteins and lipids, particularly, in the germ stem cell niche of germarium. We found an accumulation of unsaturated lipids in the nurse cells and oocytes in old flies, suggesting that unsaturated lipids may play an important role in the processes of oocyte maturation. We further detected changes in mitochondrial morphology and accumulation of Cytochrome c during aging. To our knowledge, this is the first study that directly visualizes spatiotemporal changes in lipid and protein metabolism in Drosophila ovary during development and aging processes. Our study not only demonstrates the application of a new imaging platform in visualizing metabolic dynamics of lipids and proteins in situ but also unravels how the metabolic activity and lipid distribution change in Drosophila ovary during aging.

Identification and functional analysis of senescence-associated secretory phenotype of premature senescent hepatocytes induced by hexavalent chromium

Hexavalent chromium [Cr(VI)] is a common heavy metal pollutant that can cause a number of human disease, including inflammation and cancer. Senescent cells can secrete a variety of molecules known as senescence-associated secretory phenotype (SASP). Our previous studies have confirmed that Cr(VI) can induce premature senescence in L02 hepatocytes, but the composition and the function of the related SASP are still unknown. In order to understand the components of SASP secreted by senescent L02 hepatocytes under the action of Cr(VI), we applied LC-MS/MS-based label-free protein quantification. We found that three SASP components including Coactosin-like protein 1 (COTL1), Alpha-enolase (ENO1), and Peroxiredoxin 2 (PRDX2) were up-regulated, which were confirmed by western blotting and qRT-PCR. Evidence suggested that SASP may promote the development of tumor through chronic inflammatory response, therefore we identified and analyzed the potential biological functions and signaling pathways of these three SASP components using GO and KEGG methods. The interaction between SASP components was analyzed by STRING, and verified by Co-IP. We also found that ENO1 and PRDX2, which have direct interaction, can inhibit the growth and proliferation of wildtype hepatocytes and premature senescent hepatocytes, but can promote the proliferation and behavioral changes of liver tumor cells. The present study provides valuable clues for elucidation of the carcinogenic mechanism of Cr(VI), especially for further prevention and targeted treatment of Cr(VI)-related cancer.

PRDX2 Protects Against Atherosclerosis by Regulating the Phenotype and Function of the Vascular Smooth Muscle Cell

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

Advances on hormone-like activity of Panax ginseng and ginsenosides

Traditional Chinese medicine (TCM) has been paid much attentions due to the prevention and treatment of steroid hormone disorders. Ginseng, the root of Panax ginseng C. A. Meyer (Araliaceae), is one of the most valuable herbs in complementary and alternative medicines around the world. A series of dammarane triterpenoid saponins, also known as phytosteroids, were reported as the primary ingredients of Ginseng, and indicated broad spectral pharmacological actions, including anti-cancer, anti-inflammation and anti-fatigue. The skeletons of the dammarane triterpenoid aglycone are structurally similar to the steroid hormones. Both in vitro and in vivo studies showed that Ginseng and its active ingredients have beneficial hormone-like role in hormonal disorders. This review thus summarizes the structural similarities between hormones and dammarane ginsenosides and integrates the analogous effect of Ginseng and ginsenosides on prevention and treatment of hormonal disorders published in recent twenty years (1998-2018). The review may provide convenience for anticipate structure-function relationship between saponins structure and hormone-like effect.

Peroxiredoxin 4, a new oxidative stress marker in follicular fluid, may predict in vitro fertilization and embryo transfer outcomes

Background

Peroxiredoxin 4 (Prdx4), a member of the Prdx family, can catalyze the reduction of reactive oxygen species. This study aims to explore whether Prdx4 can serve as an effective marker in follicular fluid (FF) for predicting in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) cycle outcomes.

Methods

In this prospective study, all participants were recruited from the center of clinical reproductive medicine from 2017 September to 2018 December. Women with tubal or male factor infertility undergoing their first IVF/ICSI cycle were recruited (n=138). FF samples from each patient were collected on the day of oocyte retrieval. Prdx4 concentrations were measured, and the correlation between Prdx4 levels and IVF outcomes was analyzed.

Results

The results showed that pregnant women had higher levels of Prdx4 than nonpregnant women. Prdx4 was positively correlated with the oocyte fertilization rate (r =0.334; P=0.011) and good quality embryo rate (r =0.326; P=0.013). Furthermore, we found that the clinical pregnancy rate was positively correlated with Prdx4 levels in a concentration-dependent manner in the Prdx4 quartiles (<13.38, 13.83–16.93, 16.93–22.93, >22.93 ng/mL). The fertilization rates, clinical pregnancy rates and live pregnancy rates were all significantly higher in the highest Prdx4 quartile group than in the lowest quartile. Moreover, the results indicated that Prdx4 had an area under the receiver operating characteristic curve (AUC) of 0.754, corresponding to an optimal cutoff point of 22.30 ng/mL.

Conclusions

Our results provide evidence that higher expression of antioxidants, such as Prdx4, in the FF of IVF patients tends to indicate a higher likelihood of pregnancy through an oocyte quality mechanism.

Tandem mass tag-based proteomic analysis reveals the treatment mechanism of Bushen Huoxue Formula on psychological stress-induced premature ovarian insufficiency

ETHNOPHARMACOLOGICAL RELEVANCE

Bushen Huoxue formula (BSHXF) is a Chinese herbal prescription composed of eleven herbs widely used to treat psychological stress-induced premature ovarian insufficiency (POI) in clinical. However, the underlying mechanism is still unclear.

AIM OF THE STUDY

The purpose of this study was to clarify the underlying molecular mechanisms of BSHXF in the treatment of psychological stress-induced POI.

MATERIALS AND METHODS

The rat model was induced by corticosterone (CORT, 40mg/kg). Drugs were administered to rats once daily for 21 days. The serum E₂, FSH and AMH levels were examined by enzyme-linked immunosorbent assays. Tandem mass tag-based proteomic analysis was used to identify differentially expressed proteins. Western blot was used to verify the results of proteomic.

RESULTS

Our results indicate that BSHXF can improve ovarian disfunction. The levels of serum FSH were signally enhanced in model group compared to control group. As respected, BSHXF treatment for 3 weeks led to the decreased FSH levels than the model group. The concentrations of AMH showed an obvious decrease in the model group and were increased by BSHXF treatment. Moreover, the size and number of follicles in the BSHXF groups were similar to those in the control group. The proteomic screened out that Np4 and Angptl4 were simultaneously enriched by GO and KEGG, thus these two proteins were chosen for further study.

CONCLUSIONS

These findings revealed that BSHXF might regulate the expression of Np4 and Angptl4 to improve psychological stress-induced POI.

Rescue role of hesperidin in 4-vinylcyclohexene diepoxide-induced toxicity in the brain, ovary and uterus of wistar rats

Background The ovotoxicity of 4-vinylcyclohexene diepoxide (VCD) has been established in several experimental models. Hesperidin (HSD) is a bi-flavonoid found in citrus fruits and has been reported to be a potent antioxidant and anti-inflammatory agent. Here, we have evaluated the rescue role of hesperidin on VCD-induced toxicity in the brain, ovary, and uterus of rats. Methods Six groups of rats containing ten rats in each group were orally given corn oil (control), hesperidin (100 mg/kg), hesperidin (200 mg/kg), VCD (250 mg/kg), VCD [(250 mg/kg)+hesperidin (100 mg/kg)] and VCD [(250 mg/kg)+hesperidin (200 mg/kg)] once a day for 30 days, respectively. Thereafter, we determined the selected biomarkers of oxidative damage, inflammation, endocrine balance, and histology of the reproductive organs. Results The data showed that hesperidin rescued VCD-induced increase in oxidative stress (hydrogen peroxide and malondialdehyde) and inflammatory (nitric oxide) biomarkers. In addition, hesperidin restored the reduction in antioxidant enzymes (catalase, glutathione S-transferase, glutathione peroxidase) activities and glutathione level in the brain, ovary, and uterus of rats (p<0.05). Lastly, hesperidin preserved the histological structure of the ovary and uterus of rats exposed to VCD. Conclusions Overall, the rescue role of hesperidin on VCD-induced toxicity in the brain and reproductive organs of female rats may be due to its antioxidative and anti-inflammatory properties.

Knockout Mouse Models for Peroxiredoxins

Peroxiredoxins (PRDXs) are members of a highly conserved peroxidase family and maintain intracellular reactive oxygen species (ROS) homeostasis. The family members are expressed in most organisms and involved in various biological processes, such as cellular protection against ROS, inflammation, carcinogenesis, atherosclerosis, heart diseases, and metabolism. In mammals, six PRDX members have been identified and are subdivided into three subfamilies: typical 2-Cys (PRDX1, PRDX2, PRDX3, and PRDX4), atypical 2-Cys (PRDX5), and 1-Cys (PRDX6) subfamilies. Knockout mouse models of PRDXs have been developed to investigate their in vivo roles. This review presents an overview of the knockout mouse models of PRDXs with emphases on the biological and physiological changes of these model mice.

Effects of Peroxiredoxin 2 in Neurological Disorders: A Review of its Molecular Mechanisms

Oxidative stress and neuroinflammation are closely related to the pathological processes of neurological disorders. Peroxiredoxin 2 (Prdx2) is an abundant antioxidant enzyme in the central nervous system. Prdx2 reduces the production of reactive oxygen species and participates in regulating various signaling pathways in neurons by catalyzing hydrogen peroxide (H₂O₂), thereby protecting neurons against oxidative stress and an inflammatory injury. However, the spillage of Prdx2, as damage-associated molecular patterns, accelerates brain damage after stroke by activating an inflammatory response. The post-translational modifications of Prdx2 also affect its enzyme activity. This review focuses on the effects of Prdx2 and its molecular mechanisms in various neurological disorders.

Systematic Characterization of Prognostic Values of Peroxiredoxin Family in Gastric Cancer

The peroxiredoxin (PRDX) gene family has been reported to participate in regulating occurrence and development of cancerous diseases, but its exact prognostic values in gastric cancer (GC) remain largely elusive. In the current research, we evaluated the prognostic value in predicting overall survival (OS) of each individual PRDX mRNA expression based on patients' cohorts from the Kaplan–Meier (KM) plotter database, which contains clinical information and gene expression data obtained from a total of 876 GC patients. Our results revealed that mRNA expressions of PRDX1, PRDX2, PRDX3, and PRDX4 were significantly associated with worse OS in GC patients, whereas PRDX5 and PRDX6 mRNA expressions were not associated with OS in GC patients. In addition, the prognostic values of PRDXs in the different clinicopathological features according to clinical stages, Lauren classifications, HER2 expression status, differentiation degree, and treatment strategies of GC patients were further evaluated in the KM plotter database. As a result, more potential beneficiaries who may benefit from prognostic assessment using PRDX mRNA expressions were identified. Our results elucidated the exact values of PRDXs in assessing GC prognosis and might provide primary evidence for further study on the mechanism of PRDXs participating in occurrence and development of GC.

Role/s of 'Antioxidant' Enzymes in Ageing

Reactive oxygen species (ROS), generated externally and during aerobic metabolism, are a potent cause of cell damage. Oxidative damage is a feature of many diseases and ageing, including age-associated diseases, such as diabetes, cancer, cardiovascular and neurodegenerative diseases. Indeed, this association helped lead to the widely expounded 'Free Radical Theory of Aging', proposing that the accumulation of ROS-induced damage is the underlying cause of ageing. In the last decade, it has become apparent that ROS play more complex roles in ageing than simply causing damage. This includes the induction of signalling pathways that protect against/repair cell damage. Cells encode a variety of enzymes that metabolise ROS, some of which reduce them to less reactive species. In this chapter, we review the evidence that manipulating the levels of these enzymes has any effect/s on ageing. We will also highlight a few examples illustrating why it is an over-simplification to describe the activities of some of these enzymes as 'antioxidants'. We discuss how these studies have helped refine our view of how ROS and ROS-metabolising enzymes contribute to the ageing process.