Modulation of signaling mechanisms in the heart by thioredoxin 1

Disulfide stress and its role in cardiovascular diseases

Cardiovascular disease (CVD) is one of the leading causes of mortality in humans, and oxidative stress plays a pivotal role in disease progression. This phenomenon typically arises from weakening of the cellular antioxidant system or excessive accumulation of peroxides. This review focuses on a specialized form of oxidative stress-disulfide stress-which is triggered by an imbalance in the glutaredoxin and thioredoxin antioxidant systems within the cell, leading to the accumulation of disulfide bonds. The genesis of disulfide stress is usually induced by extrinsic pathological factors that disrupt the thiol-dependent antioxidant system, manifesting as sustained glutathionylation of proteins, formation of abnormal intermolecular disulfide bonds between cysteine-rich proteins, or irreversible oxidation of thiol groups to sulfenic and sulfonic acids. Disulfide stress not only precipitates the collapse of the antioxidant system and the accumulation of reactive oxygen species, exacerbating oxidative stress, but may also initiate cellular inflammation, autophagy, and apoptosis through a cascade of signaling pathways. Furthermore, this review explores the detrimental effects of disulfide stress on the progression of various CVDs including atherosclerosis, hypertension, myocardial ischemia-reperfusion injury, diabetic cardiomyopathy, cardiac hypertrophy, and heart failure. This review also proposes several potential therapeutic avenues to improve the future treatment of CVDs.

Plasma concentrations of thioredoxin, thioredoxin reductase and peroxiredoxin-4 can identify high risk patients and predict outcome in patients with acute coronary syndrome: A clinical observation

BACKGROUND

Oxidative stress is a pathological feature of acute coronary syndrome (ACS), a complex disease with varying clinical outcomes. Surrogate biomarkers of oxidative stress including, peroxiredoxin-2 (PRDX2), PRDX4, thioredoxin (TRX) and thioredoxin reductase (TRXR) were measured in ACS patients at presentation and follow-up, to assess their clinical utility in diagnosis and risk stratification.

METHODS

Plasma from 145 participants (80 ACS and 65 healthy) at diagnosis, 1-3 month (first) and 6-month follow-up (second) was analysed by ELISA. ACS patients were monitored for 12-months.

RESULTS

ACS patients at diagnosis had significantly higher concentrations of TRX (p < 0.05), TRXR (p < 0.01) and PRDX4 (p < 0.01), compared to healthy donors. This was increase was driven by non-ST elevated myocardial infarction for TRX (p < 0.01) and PRDX4 (p < 0.05). For TRXR, ACS females were significantly higher than males (p < 0.05). TRX was also higher in older females (>55 years) at diagnosis (p < 0.05). At first follow-up, TRX had lowered, whereas PRDX4 remained significantly high (p < 0.05). Stratification of ACS patients according to percutaneous coronary intervention (PCI) revealed that TRXR was significantly higher in patients receiving PCI to the right coronary artery (p < 0.05). Whereas both TRXR (p < 0.01) and PRDX4 (p < 0.01) were significantly higher in patients receiving PCI to the left anterior descending (LAD) artery. ACS patients who had plasma TRX >13.40 ng/ml at second follow-up were at high risk of readmission (p < 0.05), as were patients with TRXR of <1000 pg/ml at diagnosis having PCI to the LAD (p < 0.05).

CONCLUSION

This study indicates that TRX, TRXR and PRDX4 may have clinical utility for ACS stratification.

Thioredoxin1 Binding Metastasis-Associated Lung Adenocarcinoma Transcript 1 Attenuates Inflammation and Apoptosis after Intracerebral Hemorrhage

Post-transcriptional regulation and RNA-binding proteins (RBPs) play vital roles in the occurrence of secondary injury after intracerebral hemorrhage (ICH). Therefore, we identified RBPs distinctively expressed after ICH by screening and determined thioredoxin1 (Txn1) as one of the most distinctive RBPs. We employed an ICH model and in vitro experiments to investigate the role of Txn1 in ICH. Firstly, we found that Txn1 was mainly expressed in microglia and neurons in the central nervous system, and its expression was significantly reduced in perihematomal tissue. Additionally, adeno-associated virus (AAV) carrying Txn1 was injected into the ICH rat model. Our results showed that overexpression of Txn1 reduced secondary injury and improved outcome in the ICH rat model. Moreover, to understand the therapeutic mechanism of Txn1 after ICH, we performed RNA immunoprecipitation combined with high-throughput sequencing. The results showed that Txn1 binds to inflammation- and apoptosis-related mRNAs and affects gene expression through RNA splicing and translation. Finally, RNA pull-down assays and in vitro experiments confirmed that Txn1 binds to metastasis-associated lung adenocarcinoma transcript 1 (MALAT1), leading to reduced inflammation and apoptosis. Our study suggests that Txn1 is a potential therapeutic target for alleviating ICH-induced brain injury.

Hydrocortisone cardioprotection in ischaemia/reperfusion injury involves antioxidant mechanisms

BACKGROUND

Glucocorticoid (GR) and mineralocorticoid (MR) receptors are highly expressed in cardiac tissue, and both can be activated by corticosteroids. MR activation, in acute myocardial infarction (AMI), worsens cardiac function, and increase NHE activity contributing to the deleterious process. In contrast, effects of GR activation are not fully understood, probably because of the controversial scenario generated by using different doses or potencies of corticosteroids.

AIMS

We tested the hypothesis that an acute dose of hydrocortisone (HC), a low-potency glucocorticoid, in a murine model of AMI could be cardioprotective by regulating NHE1 activity, leading to a decrease in oxidative stress.

MATERIALS AND METHODS

Isolated hearts from Wistar rats were subjected to regional ischemic protocol. HC (10 nmol/L) was added to the perfusate during early reperfusion. Infarct size and oxidative stress were determined. Isolated papillary muscles from non-infarcted hearts were used to evaluate HC effect on sodium-proton exchanger 1 (NHE1) by analysing intracellular pH recovery from acute transient acidosis.

RESULTS

HC treatment decreased infarct size, improved cardiac mechanics, reduced oxidative stress after AMI, while restoring the decreased level of the pro-fusion mitochondrial protein MFN-2. Co-treatment with the GR-blocker Mifepristone avoided these effects. HC reduced NHE1 activity by increasing the NHE1 pro-inhibiting Ser648 phosphorylation site and its upstream kinase AKT. HC restored the decreased AKT phosphorylation and anti-apoptotic BCL-2 protein expression detected after AMI.

CONCLUSIONS

Our results provide the first evidence that acute HC treatment during early reperfusion induces cardioprotection against AMI, associated with a non-genomic HC-triggered NHE1 inhibition by AKT and antioxidant action that might involves mitochondrial dynamics improvement.

Thioredoxin (Trx): A redox target and modulator of cellular senescence and aging-related diseases

Thioredoxin (Trx) is a compact redox-regulatory protein that modulates cellular redox state by reducing oxidized proteins. Trx exhibits dual functionality as an antioxidant and a cofactor for diverse enzymes and transcription factors, thereby exerting influence over their activity and function. Trx has emerged as a pivotal biomarker for various diseases, particularly those associated with oxidative stress, inflammation, and aging. Recent clinical investigations have underscored the significance of Trx in disease diagnosis, treatment, and mechanistic elucidation. Despite its paramount importance, the intricate interplay between Trx and cellular senescence-a condition characterized by irreversible growth arrest induced by multiple aging stimuli-remains inadequately understood. In this review, our objective is to present a comprehensive and up-to-date overview of the structure and function of Trx, its involvement in redox signaling pathways and cellular senescence, its association with aging and age-related diseases, as well as its potential as a therapeutic target. Our review aims to elucidate the novel and extensive role of Trx in senescence while highlighting its implications for aging and age-related diseases.

Insights into the Multifaceted Roles of Thioredoxin-1 System: Exploring Knockout Murine Models

Redox balance is increasingly identified as a major player in cellular signaling. A fundamentally simple reaction of oxidation and reduction of cysteine residues in cellular proteins is the central concept in this complex regulatory mode of protein function. Oxidation of key cysteine residues occurs at the physiological levels of reactive oxygen species (ROS), but they are reduced by a supply of thiol antioxidant molecules including glutathione, glutaredoxin, and thioredoxin. While these molecules show complex compensatory roles in experimental conditions, transgenic animal models provide a comprehensive picture to pinpoint the role of each antioxidant. In this review, we have specifically focused on the available literature on thioredoxin-1 system transgenic models that include thioredoxin and thioredoxin reductase proteins. As the identification of thioredoxin protein targets is technically challenging, the true contribution of this system in maintaining cellular balance remains unidentified, including the role of this system in the brain.

Middle-age abolishes cardioprotection conferred by thioredoxin-1 in mice

Thioredoxin-1 (Trx1) has cardioprotective effects on ischemia/reperfusion (I/R) injury, although its role in ischemic postconditioning (PostC) in middle-aged mice is not understood. This study aimed to evaluate if combining two cardioprotective strategies, such as Trx1 overexpression and PostC, could exert a synergistic effect in reducing infarct size in middle-aged mice. Young or middle-aged wild-type mice (Wt), transgenic mice overexpressing Trx1, and dominant negative (DN-Trx1) mutant of Trx1 mice were used. Mice hearts were subjected to I/R or PostC protocol. Infarct size, hydrogen peroxide (H2O2) production, protein nitration, Trx1 activity, mitochondrial function, and Trx1, pAkt and pGSK3β expression were measured. PostC could not reduce infarct size even in the presence of Trx1 overexpression in middle-aged mice. This finding was accompanied by a lack of Akt and GSK3β phosphorylation, and Trx1 expression (in Wt group). Trx1 activity was diminished and H2O2 production and protein nitration were increased in middle-age. The respiratory control rate dropped after I/R in Wt-Young and PostC restored this value, but not in middle-aged groups. Our results showed that Trx1 plays a key role in the PostC protection mechanism in young but not middle-aged mice, even in the presence of Trx1 overexpression.

Aldehyde Dehydrogenase 2 Preserves Mitochondrial Function in the Ischemic Heart: A Redox-dependent Mechanism for AMPK Activation by Thioredoxin-1

ABSTRACT

Aldehyde dehydrogenase 2 (ALDH2) protects the ischemic heart by activating adenosine 5'-monophosphate-activated protein kinase (AMPK) signaling. However, the molecular mechanisms linking ALDH2 and AMPK signaling are not fully understood. This study aimed to explore the potential mechanisms linking ALDH2 and AMPK in myocardial ischemic injury. An ischemic model was established by ligating the left anterior descending coronary artery in rats. The overexpression or knockdown of ALDH2 in H9c2 cells treated with oxygen-glucose deprivation was obtained through lentivirus infection. Transferase-mediated dUTP nick-end labeling was used to evaluate apoptosis in an ischemic rat model and oxygen-glucose deprivation cells. ALDH2 activity, mitochondrial oxidative stress markers, adenosine triphosphate, respiratory control ratio, and cell viability in H9c2 cells were evaluated using a biological kit and 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyl tetrazolium bromide. Protein expression of ALDH2 , 4-hydroxynonenal, thioredoxin-1 (Trx-1), and AMPK-proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α) signaling pathway was detected through Western blotting. ALDH2 activation reduced ischemic-induced myocardial infarct size and apoptosis. ALDH2 protected mitochondrial function by enhancing mitochondrial respiratory control ratio and adenosine triphosphate production, alleviated mitochondrial oxidative stress, and suppressed myocardial apoptosis. Moreover, ALDH2 attenuated ischemia-induced oxidative stress and maintained Trx-1 levels by reducing 4-hydroxynonenal, thereby promoting AMPK-PGC-1α signaling activation. Inhibiting Trx-1 or AMPK abolished the cardioprotective effect of ALDH2 on ischemia. ALDH2 alleviates myocardial injury through increased mitochondrial biogenesis and reduced oxidative stress, and these effects were achieved through Trx1-mediating AMPK-PGC1-α signaling activation.

Fluorescent Probes for Mammalian Thioredoxin Reductase: Mechanistic Analysis, Construction Strategies, and Future Perspectives

The modulation of numerous signaling pathways is orchestrated by redox regulation of cellular environments. Maintaining dynamic redox homeostasis is of utmost importance for human health, given the common occurrence of altered redox status in various pathological conditions. The cardinal component of the thioredoxin system, mammalian thioredoxin reductase (TrxR) plays a vital role in supporting various physiological functions; however, its malfunction, disrupting redox balance, is intimately associated with the pathogenesis of multiple diseases. Accordingly, the dynamic monitoring of TrxR of live organisms represents a powerful direction to facilitate the comprehensive understanding and exploration of the profound significance of redox biology in cellular processes. A number of classic assays have been developed for the determination of TrxR activity in biological samples, yet their application is constrained when exploring the real-time dynamics of TrxR activity in live organisms. Fluorescent probes offer several advantages for in situ imaging and the quantification of biological targets, such as non-destructiveness, real-time analysis, and high spatiotemporal resolution. These benefits facilitate the transition from a poise to a flux understanding of cellular targets, further advancing scientific studies in related fields. This review aims to introduce the progress in the development and application of TrxR fluorescent probes in the past years, and it mainly focuses on analyzing their reaction mechanisms, construction strategies, and potential drawbacks. Finally, this study discusses the critical challenges and issues encountered during the development of selective TrxR probes and proposes future directions for their advancement. We anticipate the comprehensive analysis of the present TrxR probes will offer some glitters of enlightenment, and we also expect that this review may shed light on the design and development of novel TrxR probes.

A Rare Case of Coexisting Mutation in Desmin and Thioredoxin Reductase 2 Genes Causing Dilated Cardiomyopathy

Desmin (DES) maintains the overall structure of cardiomyocytes and cytoskeletal organization within striated muscle cells. Mitochondrial thioredoxin reductase 2 (TXNRD-2) is essential for mitochondrial oxygen radical scavenging. We describe a rare case of dilated cardiomyopathy (DCM) in an 18-year-old female with a heterozygous mutation involving both DES and TXNRD-2 genes.

TXNRD1 knockdown inhibits the proliferation of endothelial cells subjected to oscillatory shear stress via activation of the endothelial nitric oxide synthase/apoptosis pathway

Atherosclerosis is the main cause of cardiovascular disease, and fluid shear stress is a key factor regulating its occurrence and development. Oscillatory shear stress (Oss) is an important pro-atherosclerosis factor. Oss mainly occurs in areas that are susceptible to atherosclerosis, but the exact mechanism of atherosclerosis induction remains unclear. Therefore, starting from the atheroprone phenotype that Oss stimulates abnormal vascular endothelial cell proliferation, this study aimed to reveal the underlying mechanism of Oss-induced atherosclerosis formation and to identify new targets for the prevention and treatment of atherosclerosis. In this study, the gene encoding thioredoxin reductase 1 (TXNRD1), which is closely related to atherosclerosis development and cell proliferation, was screened by analyzing the transcriptome sequencing data of static and Oss-treated human aortic endothelial cells (HAECs). Moreover, this study successfully verified that TXNRD1 mRNA and protein were significantly upregulated in Oss-treated HAECs. Oss significantly promoted the proliferation, migration, and tube formation of HAECs, whereas TXNRD1 knockdown impaired the proliferation, migration, and tube formation of Oss-treated HAECs, and this process was mainly achieved via activation of the apoptosis pathway. To further clarify whether Oss-sensitive TXNRD1 affects the apoptosis rate and proliferative ability of HAECs by regulating the endothelial nitric oxide synthase (eNOS) pathway, we used NG-nitro-L-arginine methyl ester (L-NAME) to inhibit eNOS activity and nitric oxide (NO) production. L-NAME significantly reversed the promoting effect of TXNRD1 knockdown on Oss-treated HAEC apoptosis, and it also abolished the inhibitory effect of TXNRD1 knockdown on the proliferation and S + G2 phase cell mass of Oss-treated HAECs. In conclusion, this study showed that TXNRD1 knockdown inhibited the proliferation of HAECs exposed to Oss by activating the eNOS/apoptosis pathway, revealing that TXNRD1 is involved in the dysregulation of Oss-induced endothelial cell proliferation. These findings provide new directions and insights into the prevention and treatment of atherosclerosis.

Modulation of Nrf2/HO-1 by Natural Compounds in Lung Cancer

Oxidative stresses (OSs) are considered a pivotal factor in creating various pathophysiological conditions. Cells have been able to move forward by modulating numerous signaling pathways to moderate the defects of these stresses during their evolution. The company of Kelch-like ECH-associated protein 1 (Keap1) as a molecular sensing element of the oxidative and electrophilic stress and nuclear factor erythroid 2 (NF-E2)-related factor 2 (Nrf2) as a master transcriptional regulator of the antioxidant response makes a master cytoprotective antioxidant pathway known as the Keap1/Nrf2 pathway. This pathway is considered a dual-edged sword with beneficial features for both normal and cancer cells by regulating the gene expression of the array of endogenous antioxidant enzymes. Heme oxygenase-1 (HO-1), a critical enzyme in toxic heme removal, is one of the clear state indicators for the duality of this pathway. Therefore, Nrf2/HO-1 axis targeting is known as a novel strategy for cancer treatment. In this review, the molecular mechanism of action of natural antioxidants on lung cancer cells has been investigated by relying on the Nrf2/HO-1 axis.

Decreased thioredoxin reductase 3 expression promotes nickel-induced damage to cardiac tissue via activating oxidative stress-induced apoptosis and inflammation

Thioredoxin reductase 3 (Txnrd3) plays a crucial role in antioxidant and anti-cancer activities, and sperm maturation. The damage of heavy metals, including Nickel (Ni), is the most prominent harm in social development, and hampering Txnrd3 might exacerbate Ni-induced cardiac damage. In this study, a total of 160 8-week-old C57BL/N male mice with 25-30 g weight of Txnrd3+/+ wild-type and Txnrd3-/- homozygote-type were randomly divided into eight groups. The mice in the control and Ni groups were gavaged with distilled water and a freshly prepared 10 mg/kg NiCl₂ solution. Melatonin (Mel) groups were administered at a concentration of 2 mg/kg for 21 days at the mice's 0.1 ml/10 g body weight. Ni exposure up-regulated the messenger RNA (mRNA) levels of mitochondrial apoptosis (caspase-3, caspase-9, cytochrome c, p53, and BAX), autophagy (LC3, ATG 1, ATG 7, and Beclin-1), and inflammation (TNF-α, COX 2, IL-1β, IL-2, IL-6, and IL-7)-related markers, but down-regulated the mRNA levels of BCL-2, p62 and mTOR (p < .05). Ni exposure decreased the expression of BCL-2 and p62 protein but increased the expression levels of caspase-3, caspase-9, cytochrome c, p53, BAX, ATG 7, Beclin-1, TNF-α, COX 2, IL-1β and IL-2 protein (p < .05). Ni increased the contents of glutathione disulfide (GSSG) and malondialdehyde (MDA) and decreased the activities of catalase (CAT) and total superoxide dismutase (T-SOD) (p < .05). Decreased Txnrd3 expression significantly exacerbated changes compared to the Ni exposure (p < .05). Mel significantly attenuated these changes, but the effect decreased when Txnrd3 was inhibited (p < .05). In conclusion, decreased Txnrd3 expression promoted Ni-induced mitochondrial apoptosis and inflammation via oxidative stress and aggravated heart damage in mice. Decreased Txnrd3 expression significantly reduced the protective effect of Mel to Ni exposure.

Thioredoxin 1 promotes autophagy through transnitrosylation of Atg7 during myocardial ischemia

Modification of cysteine residues by oxidative and nitrosative stress affects structure and function of proteins, thereby contributing to the pathogenesis of cardiovascular disease. Although the major function of thioredoxin 1 (Trx1) is to reduce disulfide bonds, it can also act as either a denitrosylase or transnitrosylase in a context-dependent manner. Here we show that Trx1 transnitrosylates Atg7, an E1-like enzyme, thereby stimulating autophagy. During ischemia, Trx1 was oxidized at Cys32-Cys35 of the oxidoreductase catalytic center and S-nitrosylated at Cys73. Unexpectedly, Atg7 Cys545-Cys548 reduced the disulfide bond in Trx1 at Cys32-Cys35 through thiol-disulfide exchange and this then allowed NO to be released from Cys73 in Trx1 and transferred to Atg7 at Cys402. Experiments conducted with Atg7 C402S-knockin mice showed that S-nitrosylation of Atg7 at Cys402 promotes autophagy by stimulating E1-like activity, thereby protecting the heart against ischemia. These results suggest that the thiol-disulfide exchange and the NO transfer are functionally coupled, allowing oxidized Trx1 to mediate a salutary effect during myocardial ischemia through transnitrosylation of Atg7 and stimulation of autophagy.

Free Radicals and Oxidative Stress: Signaling Mechanisms, Redox Basis for Human Diseases, and Cell Cycle Regulation

Free radicals contain one or more unpaired electrons in their valence shell, thus making them unstable, short-lived, and highly reactive species. Excessive generation of these free radicals ultimately leads to oxidative stress causing oxidation and damage to significant macromolecules in the living system and essentially disrupting signal transduction pathways and antioxidants equilibrium. At lower concentrations, ROS serves as "second messengers," influencing many physiological processes in the cell. However, higher concentrations beyond cell capacity cause oxidative stress, contributing to human pathologies such as diabetes, cancer, Parkinson's disease, cardiovascular diseases, cataract, asthma, hypertension, atherosclerosis, arthritis, and Alzheimer's disease. Signaling pathways such as NF-κB, MAPKs, PI3K/Akt/ mTOR, and Keap1-Nrf2- ARE modulate the detrimental effects of oxidative stress by increasing the expression of cellular antioxidant defenses, phase II detoxification enzymes, and decreased production of ROS. Free radicals such as H2O2 are indeed needed for the advancement of the cell cycle as these molecules influence DNA, proteins, and enzymes in the cell cycle pathway. In the course of cell cycle progression, the cellular redox environment becomes more oxidized, moving from the G1 phase, becoming higher in G2/M and moderate in the S phase. Signals in the form of an increase in cellular pro-oxidant levels are required, and these signals are often terminated by a rise in the amount of antioxidants and MnSOD with a decrease in the level of cyclin D1 proteins. Therefore, understanding the mechanism of cell cycle redox regulation will help in the therapy of many diseases.

S-Denitrosylation: A Crosstalk between Glutathione and Redoxin Systems

S-nitrosylation of proteins occurs as a consequence of the derivatization of cysteine thiols with nitric oxide (NO) and is often associated with diseases and protein malfunction. Aberrant S-nitrosylation, in addition to other genetic and epigenetic factors, has gained rapid importance as a prime cause of various metabolic, respiratory, and cardiac disorders, with a major emphasis on cancer and neurodegeneration. The S-nitrosoproteome, a term used to collectively refer to the diverse and dynamic repertoire of S-nitrosylated proteins, is relatively less explored in the field of redox biochemistry, in contrast to other covalently modified versions of the same set of proteins. Advancing research is gradually unveiling the enormous clinical importance of S-nitrosylation in the etiology of diseases and is opening up new avenues of prompt diagnosis that harness this phenomenon. Ever since the discovery of the two robust and highly conserved S-nitrosoglutathione reductase and thioredoxin systems as candidate denitrosylases, years of rampant speculation centered around the identification of specific substrates and other candidate denitrosylases, subcellular localization of both substrates and denitrosylases, the position of susceptible thiols, mechanisms of S-denitrosylation under basal and stimulus-dependent conditions, impact on protein conformation and function, and extrapolating these findings towards the understanding of diseases, aging and the development of novel therapeutic strategies. However, newer insights in the ever-expanding field of redox biology reveal distinct gaps in exploring the crucial crosstalk between the redoxins/major denitrosylase systems. Clarifying the importance of the functional overlap of the glutaredoxin, glutathione, and thioredoxin systems and examining their complementary functions as denitrosylases and antioxidant enzymatic defense systems are essential prerequisites for devising a rationale that could aid in predicting the extent of cell survival under high oxidative/nitrosative stress while taking into account the existence of the alternative and compensatory regulatory mechanisms. This review thus attempts to highlight major gaps in our understanding of the robust cellular redox regulation system, which is upheld by the concerted efforts of various denitrosylases and antioxidants.

Role of Oxidative Stress in Cardiac Dysfunction and Subcellular Defects Due to Ischemia-Reperfusion Injury

Ischemia-reperfusion (I/R) injury is well-known to be associated with impaired cardiac function, massive arrhythmias, marked alterations in cardiac metabolism and irreversible ultrastructural changes in the heart. Two major mechanisms namely oxidative stress and intracellular Ca²⁺-overload are considered to explain I/R-induced injury to the heart. However, it is becoming apparent that oxidative stress is the most critical pathogenic factor because it produces myocardial abnormalities directly or indirectly for the occurrence of cardiac damage. Furthermore, I/R injury has been shown to generate oxidative stress by promoting the formation of different reactive oxygen species due to defects in mitochondrial function and depressions in both endogenous antioxidant levels as well as regulatory antioxidative defense systems. It has also been demonstrated to adversely affect a wide variety of metabolic pathways and targets in cardiomyocytes, various resident structures in myocardial interstitium, as well as circulating neutrophils and leukocytes. These I/R-induced alterations in addition to myocardial inflammation may cause cell death, fibrosis, inflammation, Ca²⁺-handling abnormalities, activation of proteases and phospholipases, as well as subcellular remodeling and depletion of energy stores in the heart. Analysis of results from isolated hearts perfused with or without some antioxidant treatments before subjecting to I/R injury has indicated that cardiac dysfunction is associated with the development of oxidative stress, intracellular Ca²⁺-overload and protease activation. In addition, changes in the sarcolemma and sarcoplasmic reticulum Ca²⁺-handling, mitochondrial oxidative phosphorylation as well as myofibrillar Ca²⁺-ATPase activities in I/R hearts were attenuated by pretreatment with antioxidants. The I/R-induced alterations in cardiac function were simulated upon perfusing the hearts with oxyradical generating system or oxidant. These observations support the view that oxidative stress may be intimately involved in inducing intracellular Ca²⁺-overload, protease activation, subcellular remodeling, and cardiac dysfunction as a consequence of I/R injury to the heart.

Dynamics of Metabolic Pathways and Stress Response Patterns during Human Neural Stem Cell Proliferation and Differentiation

Understanding early nervous system stress response mechanisms is crucial for studying developmental neurotoxicity and devising neuroprotective treatments. We used hiPSC-derived long-term self-renewing neuroepithelial stem (lt-NES) cells differentiated for up to 12 weeks as an in vitro model of human neural development. Following a transcriptome analysis to identify pathway alterations, we induced acute oxidative stress (OS) using tert-butyl hydroperoxide (TBHP) and assessed cell viability at different stages of neural differentiation. We studied NRF2 activation, autophagy, and proteasomal function to explore the contribution and interplay of these pathways in the acute stress response. With increasing differentiation, lt-NES cells showed changes in the expression of metabolic pathway-associated genes with engagement of the pentose phosphate pathway after 6 weeks, this was accompanied by a decreased susceptibility to TBHP-induced stress. Microarray analysis revealed upregulation of target genes of the antioxidant response KEAP1–NRF2–ARE pathway after 6 weeks of differentiation. Pharmacological inhibition of NRF2 confirmed its vital role in the increased resistance to stress. While autophagy was upregulated alongside differentiation, it was not further increased upon oxidative stress and had no effect on stress-induced cell loss and the activation of NRF2 downstream genes. In contrast, proteasome inhibition led to the aggravation of the stress response resulting in decreased cell viability, derangement of NRF2 and KEAP1 protein levels, and lacking NRF2-pathway activation. Our data provide detailed insight into the dynamic regulation and interaction of pathways involved in modulating stress responses across defined time points of neural differentiation.

Redox signaling, mitochondrial metabolism, epigenetics and redox active phytochemicals

Biological redox signaling plays an important role in many diseases. Redox signaling involves reductive and oxidative mechanisms. Oxidative stress occurs when reductive mechanism underwhelms oxidative challenges. Cellular oxidative stress occurs when reactive oxygen/nitrogen species (RO/NS) exceed the cellular reductive/antioxidant capacity. Endogenously produced RO/NS from mitochondrial metabolic citric-acid-cycle coupled with electron-transport-chain or exogenous stimuli trigger cellular signaling events leading to homeostatic response or pathological damage. Recent evidence suggests that RO/NS also modulate epigenetic machinery driving gene expression. RO/NS affect DNA methylation/demethylation, histone acetylation/deacetylation or histone methylation/demethylation. Many health beneficial phytochemicals possess redox capability that counteract RO/NS either by directly scavenging the radicals or via inductive mechanism of cellular defense antioxidant/reductive enzymes. Amazingly, these phytochemicals also possess epigenetic modifying ability. This review summarizes the latest advances on the interactions between redox signaling, mitochondrial metabolism, epigenetics and redox active phytochemicals and the future challenges of integrating these events in human health.

Genome-wide methylation patterns in Marfan syndrome

Background

Marfan syndrome (MFS) is a connective tissue disorder caused by mutations in the Fibrillin-1 gene (FBN1). Here, we undertook the first epigenome-wide association study (EWAS) in patients with MFS aiming at identifying DNA methylation loci associated with MFS phenotypes that may shed light on the disease process.

Methods

The Illumina 450 k DNA-methylation array was used on stored peripheral whole-blood samples of 190 patients with MFS originally included in the COMPARE trial. An unbiased genome-wide approach was used, and methylation of CpG-sites across the entire genome was evaluated. Additionally, we investigated CpG-sites across the FBN1-locus (15q21.1) more closely, since this is the gene defective in MFS. Differentially Methylated Positions (DMPs) and Differentially Methylated Regions (DMRs) were identified through regression analysis. Associations between methylation levels and aortic diameters and presence or absence of 21 clinical features of MFS at baseline were analyzed. Moreover, associations between aortic diameter change, and the occurrence of clinical events (death any cause, type-A or -B dissection/rupture, or aortic surgery) and methylation levels were analyzed.

Results

We identified 28 DMPs that are significantly associated with aortic diameters in patients with MFS. Seven of these DMPs (25%) could be allocated to a gene that was previously associated with cardiovascular diseases (HDAC4, IGF2BP3, CASZ1, SDK1, PCDHGA1, DIO3, PTPRN2). Moreover, we identified seven DMPs that were significantly associated with aortic diameter change and five DMP’s that associated with clinical events. No significant associations at p < 10^–8 or p < 10^–6 were found with any of the non-cardiovascular phenotypic MFS features. Investigating DMRs, clusters were seen mostly on X- and Y, and chromosome 18–22. The remaining DMRs indicated involvement of a large family of protocadherins on chromosome 5, which were not reported in MFS before.

Conclusion

This EWAS in patients with MFS has identified a number of methylation loci significantly associated with aortic diameters, aortic dilatation rate and aortic events. Our findings add to the slowly growing literature on the regulation of gene expression in MFS patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13148-021-01204-4.

Application of Bulky NHC-Rhodium Complexes in Efficient S-Si and S-S Bond Forming Reactions

The efficient and straightforward syntheses of silylthioethers and disulfides are presented. The synthetic methodologies are based on new rhodium complexes containing bulky N-heterocyclic carbene (NHC) ligands that turned out to be efficient catalysts in thiol and thiol-silane coupling reactions. These green protocols, which use easily accessible reagents, allow obtaining compounds containing S-Si and S-S bonds in solvent-free conditions. Additionally, preliminary tests on coupling of mono- and octahydro-substituted spherosilicates with selected thiols have proved to be very promising and showed that these catalytic systems can be used for the synthesis of a novel class of functionalized silsesquioxane derivatives.

Thioredoxin system activation is associated with the progression of experimental pulmonary arterial hypertension

In addition to being an antioxidant, thioredoxin (Trx) is known to stimulate signaling pathways involved in cell proliferation and to inhibit apoptosis. The aim of this study was to explore the role of Trx in some of these pathways along the progression of monocrotaline (MCT)-induced pulmonary arterial hypertension (PAH). Male rats were first divided into two groups: monocrotaline (MCT - 60 mg/kg i.p.) and control (received saline), that were further divided into three groups: 1, 2, and 3 weeks. Animals were submitted to echocardiographic analysis. Right and left ventricles were used for the measurement of hypertrophy, through morphometric and histological analysis. The lung was prepared for biochemical and molecular analysis. One week after MCT injection, there was an increase in thioredoxin reductase (TrxR) activity, a reduction in glutathione reductase (GR) activity, and an increase in Trx-1 and vitamin D3 up-regulated protein-1 (VDUP-1) expression. Two weeks after MCT injection, there was an increase in VDUP-1, Akt and cleaved caspase-3 activation, and a decrease in Trx-1 and Nrf2 expression. PAH-induced by MCT promoted a reduction in Nrf2 and Trx-1 expression as well as an increase in Akt and VDUP-1 expression after three weeks. The increase in pulmonary vascular resistance was accompanied by increased TrxR activity, suggesting an association between the Trx system and functional changes in the progression of PAH. It seems that Trx-1 activation was an adaptive response to MCT administration to cope with pulmonary remodeling and disease progression, suggesting a potential new target for PAH therapeutics.

Redox signaling in heart failure and therapeutic implications

Heart failure is a growing health burden worldwide characterized by alterations in excitation-contraction coupling, cardiac energetic deficit and oxidative stress. While current treatments are mostly limited to antagonization of neuroendocrine activation, more recent data suggest that also targeting metabolism may provide substantial prognostic benefit. However, although in a broad spectrum of preclinical models, oxidative stress plays a causal role for the development and progression of heart failure, no treatment that targets reactive oxygen species (ROS) directly has entered the clinical arena yet. In the heart, ROS derive from various sources, such as NADPH oxidases, xanthine oxidase, uncoupled nitric oxide synthase and mitochondria. While mitochondria are the primary source of ROS in the heart, communication between different ROS sources may be relevant for physiological signalling events as well as pathologically elevated ROS that deteriorate excitation-contraction coupling, induce hypertrophy and/or trigger cell death. Here, we review the sources of ROS in the heart, the modes of pathological activation of ROS formation as well as therapeutic approaches that may target ROS specifically in mitochondria.

Thiol-based redox-active proteins as cardioprotective therapeutic agents in cardiovascular diseases

Thiol-based redox compounds, namely thioredoxins (Trxs), glutaredoxins (Grxs) and peroxiredoxins (Prxs), stand as a pivotal group of proteins involved in antioxidant processes and redox signaling. Glutaredoxins (Grxs) are considered as one of the major families of proteins involved in redox regulation by removal of S-glutathionylation and thereby reactivation of other enzymes with thiol-dependent activity. Grxs are also coupled to Trxs and Prxs recycling and thereby indirectly contribute to reactive oxygen species (ROS) detoxification. Peroxiredoxins (Prxs) are a ubiquitous family of peroxidases, which play an essential role in the detoxification of hydrogen peroxide, aliphatic and aromatic hydroperoxides, and peroxynitrite. The Trxs, Grxs and Prxs systems, which reversibly induce thiol modifications, regulate redox signaling involved in various biological events in the cardiovascular system. This review focuses on the current knowledge of the role of Trxs, Grxs and Prxs on cardiovascular pathologies and especially in cardiac hypertrophy, ischemia/reperfusion (I/R) injury and heart failure as well as in the presence of cardiovascular risk factors, such as hypertension, hyperlipidemia, hyperglycemia and metabolic syndrome. Further studies on the roles of thiol-dependent redox systems in the cardiovascular system will support the development of novel protective and therapeutic strategies against cardiovascular diseases.

Nampt Potentiates Antioxidant Defense in Diabetic Cardiomyopathy

[Figure: see text].

Thioredoxin-1 Is a Target to Attenuate Alzheimer-Like Pathology in Diabetic Encephalopathy by Alleviating Endoplasmic Reticulum Stress and Oxidative Stress

Varying degrees of central nervous system neuropathy induced by diabetes mellitus (DM) contribute to a cognitive disorder known as diabetic encephalopathy (DE), which is also one of the independent risk factors for Alzheimer's disease (AD). Endoplasmic reticulum stress (ERS) plays a critical role in the occurrence and development of DE and AD. However, its molecular mechanism remains largely unknown. This study aims to investigate whether thioredoxin-1 (Trx-1) could alleviate DE and AD through ERS, oxidative stress (OS) and apoptosis signaling pathways. Mice were randomly divided into a wild-type group (WT-NC), a streptozotocin (STZ)-treated DM group (WT-DM), a Trx-1-TG group (TG-NC) and a Trx-1-TG DM group (TG-DM). Diabetic animals showed an increase in the time spent in the target quadrant and the number of platform crossings as well as AD-like behavior in the water maze experiment. The immunocontent of the AD-related protein Tau and the levels of cell apoptosis, β-amyloid (Aβ) plaque formation and neuronal degeneration in the hippocampus of the diabetic group were increased. Some key factors associated with ERS, such as protein disulfide isomerase (PDI), glucose-regulated protein 78 (GRP78), inositol-requiring enzyme 1α (IRE1α), tumor necrosis factor receptor-associated factor 2 (TRAF2), apoptosis signal-regulating kinase-1 (ASK1), c-Jun N-terminal kinase (JNK), protein kinase RNA (PKR)-like ER kinase (PERK), and C/EBP homologous protein (CHOP), were upregulated, and other factors related to anti-oxidant stress, such as nuclear factor erythroid 2-related factor (Nrf2), were downregulated in the DM group. Moreover, DM caused an increase in the immunocontents of caspase-3 and caspase-12. However, these changes were reversed in the Trx-1-tg DM group. Therefore, we conclude that Trx-1 might be a key factor in alleviating DE and AD by regulating ERS and oxidative stress response, thus preventing apoptosis.

Enzymatic modifications of gluten protein: Oxidative enzymes

Oxidative enzymes treat weak flours in order to restore the gluten network of damaged wheat flour and reduce the economic and technological losses. The present review concentrates on oxidative exogenous enzymes (transglutaminase, laccase, glucose oxidase, hexose oxidase) and oxidative endogenous enzymes (tyrosinase, peroxidase, catalase, sulfhydryl oxidase, lipoxygenase, lipase, protein disulfide isomerase, NAD(P)H-dependent dehydrogenase, thioredoxin reductase and glutathione reductase) and their effects on the rheological, functional, and conformational features of gluten and its subunits. Overall, transglutaminase is used in wheat-based foods through introducing isopeptide bonds (ε-γ glutamyl-lysine). Glucose oxidase, hexose oxidase, peroxidase, sulfhydryl oxidase, lipase, and lipoxygenase form disulfide and nondisulfide bonds through producing hydrogen peroxide. Laccase, tyrosinase, and protein disulfide isomerase form cross-links between tyrosine and cysteine residues by generating radicals. Thioredoxin reductase and glutathione reductase create new inter disulfide bonds. The effect of oxidative enzymes on the formation of covalent cross-linkages were substantially more than non-covalent bonds in gluten structure.

In situ formation of tetraphenylethylene nano-structures on microgels inside living cells via reduction-responsive self-assembly

Controlling the assembly of synthetic molecules in living systems is of significance for their adaptive applications. However, it is difficult to achieve, especially for composite self-assemblies, due to the complexity and dynamic change of the intracellular environment, and there exist technical difficulties for the direct visualization of organic and polymer self-assemblies. Herein, we demonstrate a novel strategy for the in situ formation of self-assembled micro-nano composite structures in a cell milieu using reduction-responsive microgels (MGs) as a platform. The MGs were prepared by a templating and crosslinking method using a synthetic amphiphlic polymer as the basic material and porous CaCO3 microparticles as the template. The aggregation-induced emission (AIE) tetraphenylethylene moieties and reduction-labile disulfide bonds in the MGs were employed as the self-assembly building blocks and triggering sites for the intracellular self-assembly, respectively. In the presence of reductive agents such as glutathione, nano-spikes were gradually formed on the MGs. After the MGs were internalized by cells, the in situ formation of microgel/nano-spike composite structures was evidenced by the enhanced fluorescence intensity and was further confirmed by direct transmission electron microscopy observation. This work provides an effective strategy to cope with the challenging task of achieving and probing controlled self-assembly in a cell milieu, leading to new insights into investigating biological self-assembly and promoting the development of micro-/nanomaterials by learning from nature.

Dexmedetomidine Protects against Myocardial Ischemia/Reperfusion Injury by Ameliorating Oxidative Stress and Cell Apoptosis through the Trx1-Dependent Akt Pathway

Dexmedetomidine (Dex) was reported to reduce oxidative stress and protect against myocardial Ischemia/Reperfusion (I/R) injury. However, the molecular mechanism involved in its antioxidant property is not fully elucidated. The present study was aimed at investigating whether the Trx1/Akt pathway participated in the cardioprotective effect of Dex. In the present study, I/R-induced myocardial injury in isolated rat hearts and OGD/R-induced injury in H9c2 cardiomyocytes were established. Our findings suggested that Dex ameliorated myocardial I/R injury by improving cardiac function, reducing myocardial apoptosis and oxidative stress, which was manifested by increased GSH and SOD contents, decreased ROS level, and MDA generation in both the isolated rat hearts and OGD/R-treated H9C2 cells. More importantly, it was found that the level of Trx1 was preserved, and Akt phosphorylation was significantly upregulated by Dex treatment. However, these effects of Dex were abolished by PX-12 (a specific Trx1 inhibitor) administration. Taken together, this study suggests that Dex plays a protective role in myocardial I/R injury, improves cardiac function, and relieves oxidative stress and cell apoptosis. Furthermore, our results present a novel signaling mechanism that the cardioprotective effect of Dex is at least partly achieved through the Trx1-dependent Akt pathway.

Thioredoxin 1 is upregulated in the bone and bone marrow following experimental myocardial infarction: evidence for a remote organ response

Ischemia and reperfusion events, such as myocardial infarction (MI), are reported to induce remote organ damage severely compromising patient outcomes. Tissue survival and functional restoration relies on the activation of endogenous redox regulatory systems such as the oxidoreductases of the thioredoxin (Trx) family. Trxs and peroxiredoxins (Prxs) are essential for the redox regulation of protein thiol groups and for the reduction of hydrogen peroxide, respectively. Here, we determined whether experimental MI induces changes in Trxs and Prxs in the heart as well as in secondary organs. Levels and localization of Trx1, TrxR1, Trx2, Prx1, and Prx2 were analyzed in the femur, vertebrae, and kidneys of rats following MI or sham surgery. Trx1 levels were significantly increased in the heart (P = 0.0017) and femur (P < 0.0001) of MI animals. In the femur and lumbar vertebrae, Trx1 upregulation was detected in bone-lining cells, osteoblasts, megakaryocytes, and other hematopoietic cells. Serum levels of Trx1 increased significantly 2 days after MI compared to sham animals (P = 0.0085). Differential regulation of Trx1 in the bone was also detected by immunohistochemistry 1 month after MI. N-Acetyl-cysteine treatment over a period of 1 month induced a significant reduction of Trx1 levels in the bone of MI rats compared to sham and to MI vehicle. This study provides first evidence that MI induces remote organ upregulation of the redox protein Trx1 in the bone, as a response to ischemia-reperfusion injury in the heart.

Free Thiol β2-GPI (β-2-Glycoprotein-I) Provides a Link Between Inflammation and Oxidative Stress in Atherosclerotic Coronary Artery Disease

Objective:

Atherosclerotic coronary artery disease is well recognised as an inflammatory disorder that is also influenced by oxidative stress. β2-GPI (β-2-glycoprotein-I) is a circulating plasma protein that undergoes post-translational modification and exists in free thiol as well as oxidized forms. The aim of this study was to assess the association between these 2 post-translational redox forms of β2-GPI and atherosclerotic coronary artery disease.

Approach and Results:

Stable patients presenting for elective coronary angiography or CT coronary angiography were prospectively recruited. A separate group of patients after reperfused ST-segment–elevation myocardial infarction formed an acute coronary syndrome subgroup. All patients had collection of fasting serum and plasma for quantification of total and free thiol β2-GPI. Coronary artery disease extent was quantified by the Syntax and Gensini scores. A total of 552 patients with stable disease and 44 with acute coronary syndrome were recruited. While total β2-GPI was not associated with stable coronary artery disease, a higher free thiol β2-GPI was associated with its presence and extent. This finding remained significant after correcting for confounding variables, and free thiol β2-GPI was a better predictor of stable coronary artery disease than hs-CRP (high-sensitivity C-reactive protein). Paradoxically, there were lower levels of free thiol β2-GPI after ST-segment–elevation myocardial infarction.

Conclusions:

Free thiol β2-GPI is a predictor of coronary artery disease presence and extent in stable patients. Free thiol β2-GPI was a better predictor than high-sensitivity C-reactive protein.

ndufa7 plays a critical role in cardiac hypertrophy

Cardiac hypertrophy is a common pathological change in patients with progressive cardiac function failure, which can be caused by hypertrophic cardiomyopathy (HCM), dilated cardiomyopathy (DCM) or arterial hypertension. Despite years of study, there is still limited knowledge about the underlying molecular mechanisms for cardiac hypertrophy. NDUFA7, a subunit of NADH:ubiquinone oxidoreductase (complex I), has been reported to be a novel HCM associated gene. However, the biological role of NDUFA7 in heart remains unknown. In this study, we found that NDUFA7 exhibited high expression in the heart, and its level was significantly decreased in mice model of cardiac hypertrophy. Moreover, we demonstrated that ndufa7 knockdown in developing zebrafish embryos resulted in cardiac development and functional defects, associated with increased expression of pathological hypertrophy biomarkers nppa (ANP) and nppb (BNP). Mechanistic study demonstrated that ndufa7 depletion promoted ROS production and calcineurin signalling activation. Moreover, NDUFA7 depletion contributed to cardiac cell hypertrophy. Together, these results report for the first time that ndufa7 is implicated in pathological cardiac hypertrophy.

Up-regulation of Thioredoxin 1 by aerobic exercise training attenuates endoplasmic reticulum stress and cardiomyocyte apoptosis following myocardial infarction

Exercise training (ET) has been reported to reduce oxidative stress and endoplasmic reticulum (ER) stress in the heart following myocardial infarction (MI). Thioredoxin 1 (Trx1) plays a protective role in the infarcted heart. However, whether Trx1 regulates ER stress of the infarcted heart and participates in ET-induced cardiac protective effects are still not well known. In this work, H9c2 cells were treated with hydrogen peroxide (H₂O₂) and recombinant human Trx1 protein (TXN), meanwhile, adult male C57B6L mice were used to establish the MI model, and subjected to a six-week aerobic exercise training (AET) with or without the injection of Trx1 inhibitor, PX-12. Results showed that H₂O₂ significantly increased reactive oxygen species (ROS) level and the expression of TXNIP, CHOP and cleaved caspase12, induced cell apoptosis; TXN intervention reduced ROS level and the expression of CHOP and cleaved caspase12, and inhibited cell apoptosis in H₂O₂-treated H9c2 cells. Furthermore, AET up-regulated endogenous Trx1 protein expression and down-regulated TXNIP expression, restored ROS level and the expression of ER stress-related proteins, inhibited cell apoptosis as well as improved cardiac fibrosis and heart function in mice after MI. PX-12 partly inhibited the AET-induced beneficial effects in the infarcted heart. This study demonstrates that Trx1 attenuates ER stress-induced cell apoptosis, and AET reduces MI-induced ROS overproduction, ER stress and cell apoptosis partly through up-regulating of Trx1 expression in mice with MI.

Thioredoxin-1 maintains mitochondrial function via mechanistic target of rapamycin signalling in the heart

AIMS

Thioredoxin 1 (Trx1) is an evolutionarily conserved oxidoreductase that cleaves disulphide bonds in oxidized substrate proteins such as mechanistic target of rapamycin (mTOR) and maintains nuclear-encoded mitochondrial gene expression. The cardioprotective effect of Trx1 has been demonstrated via cardiac-specific overexpression of Trx1 and dominant negative Trx1. However, the pathophysiological role of endogenous Trx1 has not been defined with a loss-of-function model. To address this, we have generated cardiac-specific Trx1 knockout (Trx1cKO) mice.

METHODS AND RESULTS

Trx1cKO mice were viable but died with a median survival age of 25.5 days. They developed heart failure, evidenced by contractile dysfunction, hypertrophy, and increased fibrosis and apoptotic cell death. Multiple markers consistently indicated increased oxidative stress and RNA-sequencing revealed downregulation of genes involved in energy production in Trx1cKO mice. Mitochondrial morphological abnormality was evident in these mice. Although heterozygous Trx1cKO mice did not show any significant baseline phenotype, pressure-overload-induced cardiac dysfunction, and downregulation of metabolic genes were exacerbated in these mice. mTOR was more oxidized and phosphorylation of mTOR substrates such as S6K and 4EBP1 was impaired in Trx1cKO mice. In cultured cardiomyocytes, Trx1 knockdown inhibited mitochondrial respiration and metabolic gene promoter activity, suggesting that Trx1 maintains mitochondrial function in a cell autonomous manner. Importantly, mTOR-C1483F, an oxidation-resistant mutation, prevented Trx1 knockdown-induced mTOR oxidation and inhibition and attenuated suppression of metabolic gene promoter activity.

CONCLUSION

Endogenous Trx1 is essential for maintaining cardiac function and metabolism, partly through mTOR regulation via Cys1483.

Inhibition of TGFβ-activated protein kinase 1 ameliorates myocardial ischaemia/reperfusion injury via endoplasmic reticulum stress suppression

Transforming growth factor β-activated protein kinase 1 (TAK1) involves in various biological responses and is a key regulator of cell death. However, the role of TAK1 on acute myocardial ischaemia/reperfusion (MI/R) injury is unknown. We observed that TAK1 activation increased significantly after MI/R and hypoxia/reoxygenation (H/R), and we hypothesized that TAK1 has an important role in MI/R injury. Mice (TAK1 inhibiting by 5Z-7-oxozeaenol or silencing by AAV9 vector) were exposed to MI/R injury. Primary cardiomyocytes (TAK1 silencing by siRNA; and overexpressing TAK1 by adenovirus vector) were used to induce H/R injury model in vitro. Inhibition of TAK1 significantly decreased MI/R-induced myocardial infarction area, reduced cell death and improved cardiac function. Mechanistically, TAK1 silencing suppressed MI/R-induced myocardial oxidative stress and attenuated endoplasmic reticulum (ER) stress both in vitro and in vivo. In addition, the inhibition of ROS by NAC partially reversed the damage of TAK1 in vitro. Our study presents the first direct evidence that inhibition of TAK1 mitigated MI/R injury, and TAK1 mediated ROS/ER stress/apoptosis signal pathway is important for the pathogenesis of MI/R injury.

CD38: A Potential Therapeutic Target in Cardiovascular Disease

Substantial research has demonstrated the association between cardiovascular disease and the dysregulation of intracellular calcium, ageing, reduction in nicotinamide adenine dinucleotide NAD+ content, and decrease in sirtuin activity. CD38, which comprises the soluble type, type II, and type III, is the main NADase in mammals. This molecule catalyses the production of cyclic adenosine diphosphate ribose (cADPR), nicotinic acid adenine dinucleotide phosphate (NAADP), and adenosine diphosphate ribose (ADPR), which stimulate the release of Ca²⁺, accompanied by NAD+ consumption and decreased sirtuin activity. Therefore, the relationship between cardiovascular disease and CD38 has been attracting increased attention. In this review, we summarize the structure, regulation, function, targeted drug development, and current research on CD38 in the cardiac context. More importantly, we provide original views about the as yet elusive mechanisms of CD38 action in certain cardiovascular disease models. Based on our review, we predict that CD38 may serve as a novel therapeutic target in cardiovascular disease in the future.

Sex differences in inflammation, redox biology, mitochondria and autoimmunity

Autoimmune diseases are characterized by circulating antibodies and immune complexes directed against self-tissues that result in both systemic and organ-specific inflammation and pathology. Most autoimmune diseases occur more often in women than men. One exception is myocarditis, which is an inflammation of the myocardium that is typically caused by viral infections. Sex differences in the immune response and the role of the sex hormones estrogen and testosterone are well established based on animal models of autoimmune viral myocarditis as well as in mitochondrial function leading to reactive oxygen species production. RNA viruses like coxsackievirus B3, the primary cause of myocarditis in the US, activate the inflammasome through mitochondrial antiviral signaling protein located on the mitochondrial outer membrane. Toll-like receptor 4 and the inflammasome are the primary signaling pathways that increase inflammation during myocarditis, which is increased by testosterone. This review describes what is known about sex differences in inflammation, redox biology and mitochondrial function in the male-dominant autoimmune disease myocarditis and highlights gaps in the literature and future directions.

Pterostilbene improves cardiac function in a rat model of right heart failure through modulation of calcium handling proteins and oxidative stress

This study explored the effect of pterostilbene (PTS) complexed with hydroxypropyl-β-cyclodextrin (HPβCD) on right heart function, glutathione and glutaredoxin systems, and the expression of redox-sensitive proteins involved with regulation calcium levels in the experimental model of pulmonary arterial hypertension (PAH) induced by monocrotaline (MCT). After 7 days of PAH induction, rats received daily doses of the PTS:HPβCD complex (corresponding to 25, 50, or 100 mg·kg^-1 of PTS) or vehicle (control group, CTR0) (an aqueous solution containing HPβCD; CTR0 and MCT0 (MCT group that did not receive PTS treatment)) via oral administration for 2 weeks. The results showed that the PTS:HPβCD complex increased the content of reduced glutathione and the activity of glutathione-S-transferase and glutaredoxin in the right ventricle (RV) of MCT-treated rats in a dose-dependent manner. Additionally, at higher doses, it also prevented the reduction of stroke volume and cardiac output, prevented myocardial performance index (MPI) increase, reduced lipoperoxidation, reduced total phospholamban, and increased the expression of sarcoplasmic reticulum calcium ATPase in the RV of MCT-treated rats. These results demonstrate that the PTS:HPβCD complex has a dose-dependent antioxidant mechanism that results in improved cardiac function in experimental right heart failure. Our results open a field of possibilities to PTS administration as new therapeutic approach to conventional therapy for right ventricular dysfunction. Novelty Pterostilbene complexed with hydroxypropyl-β-cyclodextrin could be a new therapeutic approach. Pterostilbene complexed with hydroxypropyl-β-cyclodextrin reestablishes redox homeostasis through glutathione metabolism modulation, leading to an improved MPI in pulmonary arterial hypertension-provoked right heart failure.

[Selenium compounds in redox regulation of inflammation and apoptosis]

Monocytes and macrophages play a key role in the development of inflammation: under the action of lipopolysaccharides (LPS), absorbed from the intestine, monocytes and macrophages form reactive oxygen species (ROS) and cytokines, this leads to the development of oxidative stress, inflammation and/or apoptosis in all types of tissues. In the cells LPS induce an "internal" TLR4-mediated MAP-kinase inflammatory signaling pathway and cytokines through the superfamily of tumor necrosis factor receptor (TNFR) and the "death domain" (DD) initiate an "external" caspase apoptosis cascade or necrosis activation that causes necroptosis. Many of the proteins involved in intracellular signaling cascades (MYD88, ASK1, IKKa/b, NF-kB, AP-1) are redox-sensitive and their activity is regulated by antioxidants thioredoxin, glutaredoxin, nitroredoxin, and glutathione. Oxidation of these signaling proteins induced by ROS enhances the development of inflammation and apoptosis, and their reduction with antioxidants, on the contrary, stabilizes the signaling cascades speed, preventing the vicious circle of oxidative stress, inflammation and apoptosis that follows it. Antioxidant (AO) enzymes thioredoxin reductase (TRXR), glutaredoxin reductase (GLRXR), glutathione reductase (GR) are required for reduction of non-enzymatic antioxidants (thioredoxin, glutaredoxin, nitroredoxin, glutathione), and AO enzymes (SOD, catalase, GPX) are required for ROS deactivation. The key AO enzymes (TRXR and GPX) are selenium-dependent; therefore selenium deficiency leads to a decrease in the body's antioxidant defense, the development of oxidative stress, inflammation, and/or apoptosis in various cell types. Nrf2-Keap1 signaling pathway activated by selenium deficiency and/or oxidative stress is necessary to restore redox homeostasis in the cell. In addition, expression of some genes is changed with selenium deficiency. Consequently, growth and proliferation of cells, their movement, development, death, and survival, as well as the interaction between cells, the redox regulation of intracellular signaling cascades of inflammation and apoptosis, depend on the selenium status of the body. Prophylactic administration of selenium-containing preparations (natural and synthetic (organic and inorganic)) is able to normalize the activity of AO enzymes and the general status of the body. Organic selenium compounds have a high bioavailability and, depending on their concentration, can act both as selenium donors to prevent selenium deficiency and as antitumor drugs due to their toxicity and participation in the regulation of signaling pathways of apoptosis. Known selenorganic compounds diphenyldiselenide and ethaselen share similarity with the Russian organo selenium compound, diacetophenonylselenide (DAPS-25), which serves as a source of bioavailable selenium, exhibits a wide range of biological activity, including antioxidant activity, that governs cell redox balance, inflammation and apoptosis regulation.

Hyperosmotic Stress Initiates AMPK-Independent Autophagy and AMPK- and Autophagy-Independent Depletion of Thioredoxin 1 and Glyoxalase 2 in HT22 Nerve Cells

Background

Hyperosmotic stress is an important pathophysiologic condition in diabetes, severe trauma, dehydration, infection, and ischemia. Furthermore, brain neuronal cells face hyperosmotic stress in ageing and Alzheimer's disease. Despite the enormous importance of knowing the homeostatic mechanisms underlying the responses of nerve cells to hyperosmotic stress, this topic has been underrepresented in the literature. Recent evidence points to autophagy induction as a hallmark of hyperosmotic stress, which has been proposed to be controlled by mTOR inhibition as a consequence of AMPK activation. We previously showed that methylglyoxal induced a decrease in the antioxidant proteins thioredoxin 1 (Trx1) and glyoxalase 2 (Glo2), which was mediated by AMPK-dependent autophagy. Thus, we hypothesized that hyperosmotic stress would have the same effect.

Methods

HT22 hippocampal nerve cells were treated with NaCl (37, 75, or 150 mM), and the activation of the AMPK/mTOR pathway was investigated, as well as the levels of Trx1 and Glo2. To determine if autophagy was involved, the inhibitors bafilomycin (Baf) and chloroquine (CQ), as well as ATG5 siRNA, were used. To test for AMPK involvement, AMPK-deficient mouse embryonic fibroblasts (MEFs) were used.

Results

Hyperosmotic stress induced a clear increase in autophagy, which was demonstrated by a decrease in p62 and an increase in LC3 lipidation. AMPK phosphorylation, linked to a decrease in mTOR and S6 ribosomal protein phosphorylation, was also observed. Deletion of AMPK in MEFs did not prevent autophagy induction by hyperosmotic stress, as detected by decreased p62 and increased LC3 II, or mTOR inhibition, inferred by decreased phosphorylation of P70 S6 kinase and S6 ribosomal protein. These data indicating that AMPK was not involved in autophagy activation by hyperosmotic stress were supported by a decrease in p^S555-ULK1, an AMPK phosphorylation site. Trx1 and Glo2 levels were decreased at 6 and 18 h after treatment with 150 mM NaCl. However, this decrease in Trx1 and Glo2 in HT22 cells was not prevented by autophagy inhibition by Baf, CQ, or ATG5 siRNA. AMPK-deficient MEFs under hyperosmotic stress presented the same Trx1 and Glo2 decrease as wild-type cells.

Conclusion

Hyperosmotic stress induced AMPK activation, but this was not responsible for its effects on mTOR activity or autophagy induction. Moreover, the decrease in Trx1 and Glo2 induced by hyperosmotic stress was independent of both autophagy and AMPK activation.

Redox Proteomic Analysis Reveals Oxidative Modifications of Proteins by Increased Levels of Intracellular Reactive Oxygen Species during Hypoxia Adaptation of Aspergillus fumigatus

Aspergillus fumigatus faces abrupt changes in oxygen concentrations at the site of infection. An increasing number of studies has demonstrated that elevated production of intracellular reactive oxygen species (ROS) under low oxygen conditions plays a regulatory role in modulating cellular responses for adaptation to hypoxia. To learn more about this process in A. fumigatus, intracellular ROS production during hypoxia has been determined. The results confirm increased amounts of intracellular ROS in A. fumigatus exposed to decreased oxygen levels. Moreover, nuclear accumulation of the major oxidative stress regulator AfYap1 is observed after low oxygen cultivation. For further analysis, iodoTMT labeling of redox-sensitive cysteine residues is applied to identify proteins that are reversibly oxidized. This analysis reveals that proteins with important roles in maintaining redox balance and protein folding, such as the thioredoxin Asp f 29 and the disulfide-isomerase PdiA, undergo substantial thiol modification under hypoxia. The data also show that the mitochondrial respiratory complex IV assembly protein Coa6 is significantly oxidized by hypoxic ROS. Deletion of the corresponding gene results in a complete absence of hypoxic growth, indicating the importance of complex IV during adaptation of A. fumigatus to oxygen-limiting conditions.

Stilbenoid pterostilbene complexed with cyclodextrin preserves left ventricular function after myocardial infarction in rats: possible involvement of thiol proteins and modulation of phosphorylated GSK-3β

Oxidative stress alters signalling pathways for survival and cell death favouring the adverse remodelling of postmyocardial remnant cardiomyocytes, promoting functional impairment. The administration of pterostilbene (PTS), a phytophenol with antioxidant potential, can promote cardioprotection and represents a therapeutic alternative in acute myocardial infarction (AMI). The present study aims to explore the effects of oral administration of PTS complexed with hydroxypropyl-β-cyclodextrin HPβCD (PTS:HPβCD complex) on the glutathione cycle, thiol protein activities and signalling pathways involving the protein kinase B (AKT) and glycogen synthase kinase-3β (GSK-3β) proteins in the left ventricle (LV) of infarcted rats. Animals were submitted to acute myocardial infarction through surgical ligation of the descending anterior branch of the left coronary artery and received over 8 days, by gavage, PTS:HPβCD complex at dose of 100 mg kg^-1 day^-1 (AMI + PTS group) or vehicle (aqueous solution with HPβCD) divided into Sham-operated (SHAM) and infarcted (AMI) groups. The results showed that the PBS: HPβCD complex decreased lipid peroxidation, prevented the decrease in thioredoxin reductase (TRxR) activity, and increased the activity of glutathione-S-transferase (GST) and glutaredoxin (GRx). Additionally, the expression of nuclear factor-erythroid two (Nrf2) and p-GSK-3β was increased, whereas the p-GSK-3β/GSK-3β ratio was reduced in the LV of the infarcted animals. Overall, the PTS:HPβCD complex modulates activity of thiol-dependent enzymes and induces to the expression of antioxidant proteins, improving systolic function and mitigating the adverse cardiac remodelling post infarction.

Mitochondria "THE" target of myocardial conditioning

Several interventions, such as ischemic preconditioning, remote pre/perconditioning, or postconditioning, are known to decrease lethal myocardial ischemia-reperfusion injury. While several signal transduction pathways become activated by such maneuvers, they all have a common end point, namely, the mitochondria. These organelles represent an essential target of the cardioprotective strategies, and the preservation of mitochondrial function is central for the reduction of ischemia-reperfusion injury. In the present review, we address the role of mitochondria in the different conditioning strategies; in particular, we focus on alterations of mitochondrial function in terms of energy production, formation of reactive oxygen species, opening of the mitochondrial permeability transition pore, and mitochondrial dynamics induced by ischemia-reperfusion.

The role of the thioredoxin/thioredoxin reductase system in the metabolic syndrome: towards a possible prognostic marker?

Mammalian thioredoxin reductase (TrxR) is a selenoprotein with three existing isoenzymes (TrxR1, TrxR2, and TrxR3), which is found primarily intracellularly but also in extracellular fluids. The main substrate thioredoxin (Trx) is similarly found (as Trx1 and Trx2) in various intracellular compartments, in blood plasma, and is the cell's major disulfide reductase. Thioredoxin reductase is necessary as a NADPH-dependent reducing agent in biochemical reactions involving Trx. Genetic and environmental factors like selenium status influence the activity of TrxR. Research shows that the Trx/TrxR system plays a significant role in the physiology of the adipose tissue, in carbohydrate metabolism, insulin production and sensitivity, blood pressure regulation, inflammation, chemotactic activity of macrophages, and atherogenesis. Based on recent research, it has been reported that the modulation of the Trx/TrxR system may be considered as a new target in the management of the metabolic syndrome, insulin resistance, and type 2 diabetes, as well as in the treatment of hypertension and atherosclerosis. In this review evidence about a possible role of this system as a marker of the metabolic syndrome is reported.