Perturbation of redox balance after thioredoxin reductase deficiency interrupts autophagy-lysosomal degradation pathway and enhances cell death in nutritionally stressed SH-SY5Y cells

Thioredoxin-1 protein interactions in neuronal survival and neurodegeneration

Neuronal cell death remains the principal pathophysiologic hallmark of neurodegenerative diseases and the main challenge for treatment strategies. Thioredoxin1 (Trx1) is a major cytoplasmic thiol oxidoreductase protein involved in redox signaling, hence a crucial player in maintaining neuronal health. Trx1 levels are notably reduced in neurodegenerative diseases including Alzheimer's and Parkinson's diseases, however, the impact of this decrease on neuronal physiology remains largely unexplored. This is mainly due to the nature of Trx1 redox regulatory role which is afforded by a rapid electron transfer to its oxidized protein substrates. During this reaction, Trx1 forms a transient bond with the oxidized disulfide bond in the substrate. This is a highly fast reaction which makes the identification of Trx1 substrates a technically challenging task. In this project, we utilized a transgenic mouse model expressing a Flag-tagged mutant form of Trx1 that can form stable disulfide bonds with its substrates, hence allowing identification of the Trx1 target proteins. Autophagy is a vital housekeeping process in neurons that is critical for degradation of damaged proteins under oxidative stress conditions and is interrupted in neurodegenerative diseases. Given Trx1's suggested involvement in autophagy, we aimed to identify potential Trx1 substrates following pharmacologic induction of autophagy in primary cortical neurons. Treatment with rapamycin, an autophagy inducer, significantly reduced neurite outgrowth and caused cytoskeletal alterations. Using immunoprecipitation and mass spectrometry, we have identified 77 Trx1 target proteins associated with a wide range of cellular functions including cytoskeletal organization and neurodegenerative diseases. Focusing on neuronal cytoskeleton organization, we identified a novel interaction between Trx1 and RhoB which was confirmed in genetic models of Trx1 downregulation in primary neuronal cultures and HT22 mouse immortalized hippocampal neurons. The applicability of these findings was also tested against the publicly available proteomic data from Alzheimer's patients. Our study uncovers a novel role for Trx1 in regulating neuronal cytoskeleton organization and provides a mechanistic explanation for its multifaceted role in the physiology and pathology of the nervous system, offering new insights into the molecular mechanisms underlying neurodegeneration.

Inhibition of thioredoxin reductase and upregulation of apoptosis genes for effective anti-tumor sono-chemotherapy using a meso-organosilica nanomedicine

The thioredoxin system is involved in cancer development and therefore is a promising target for cancer chemotherapy. Thioredoxin reductase (TrxR) is a key component of the thioredoxin (Trx) system, and is overexpressed in many cancers to inhibit apoptosis-related proteins. Alternatively, inhibition of thioredoxin reductase and upregulation of apoptosis factors provide a therapeutic strategy for anti-tumor treatment. In this study, an ultrasound-activatable meso-organosilica nanomedicine was prepared by integrating chloroquine (CQ) into hollow mesoporous organosilica (CQ@MOS). The meso-organosilica nanomedicine can inhibit the activity of thioredoxin reductase, elevate cellular reactive oxygen species (ROS) levels, upregulate the pro-apoptotic factors in the c-Jun N-terminal kinase (JNK) apoptosis pathway and induce autophagy inhibition, further resulting in mitochondrial membrane potential (MMP) depolarization and cellular ATP content decrease, ultimately causing significant damage to tumor cells. Moreover, CQ@MOS can efficiently deliver chloroquine into cancer cells and promote an enhanced sonodynamic effect for effective anti-tumor chemotherapy and sonodynamic therapy. This study may enlighten us on a new anti-tumor strategy and suggest its promising applications in cancer treatments.

Progress in Research on the Role of the Thioredoxin System in Chemical Nerve Injury

(1) Background: Various factors, such as oxidative stress, mitochondrial dysfunction, tumors, inflammation, trauma, immune disorders, and neuronal toxicity, can cause nerve damage. Chemical nerve injury, which results from exposure to toxic chemicals, has garnered increasing research attention. The thioredoxin (Trx) system, comprising Trx, Trx reductase, nicotinamide adenine dinucleotide phosphate, and Trx-interacting protein (TXNIP; endogenous Trx inhibitor), helps maintain redox homeostasis in the central nervous system. The dysregulation of this system can cause dementia, cognitive impairment, nerve conduction disorders, movement disorders, and other neurological disorders. Thus, maintaining Trx system homeostasis is crucial for preventing or treating nerve damage. (2) Objective: In this review study, we explored factors influencing the homeostasis of the Trx system and the involvement of its homeostatic imbalance in chemical nerve injury. In addition, we investigated the therapeutic potential of the Trx system-targeting active substances against chemical nerve injury. (3) Conclusions: Chemicals such as morphine, metals, and methylglyoxal interfere with the activity of TXNIP, Trx, and Trx reductase, disrupting Trx system homeostasis by affecting the phosphatidylinositol-3-kinase/protein kinase B, extracellular signal-regulated kinase, and apoptotic signaling-regulated kinase 1/p38 mitogen-activated protein kinase pathways, thereby leading to neurological disorders. Active substances such as resveratrol and lysergic acid sulfide mitigate the symptoms of chemical nerve injury by regulating the Ras/Raf1/extracellular signal-regulated kinase pathway and the miR-146a-5p/TXNIP axis. This study may guide the development of Trx-targeting modulators for treating neurological disorders and chemical nerve injuries.

Unraveling the genetics of arsenic toxicity with cellular morphology QTL

The health risks that arise from environmental exposures vary widely within and across human populations, and these differences are largely determined by genetic variation and gene-by-environment (gene-environment) interactions. However, risk assessment in laboratory mice typically involves isogenic strains and therefore, does not account for these known genetic effects. In this context, genetically heterogenous cell lines from laboratory mice are promising tools for population-based screening because they provide a way to introduce genetic variation in risk assessment without increasing animal use. Cell lines from genetic reference populations of laboratory mice offer genetic diversity, power for genetic mapping, and potentially, predictive value for in vivo experimentation in genetically matched individuals. To explore this further, we derived a panel of fibroblast lines from a genetic reference population of laboratory mice (the Diversity Outbred, DO). We then used high-content imaging to capture hundreds of cell morphology traits in cells exposed to the oxidative stress-inducing arsenic metabolite monomethylarsonous acid (MMAIII). We employed dose-response modeling to capture latent parameters of response and we then used these parameters to identify several hundred cell morphology quantitative trait loci (cmQTL). Response cmQTL encompass genes with established associations with cellular responses to arsenic exposure, including Abcc4 and Txnrd1, as well as novel gene candidates like Xrcc2. Moreover, baseline trait cmQTL highlight the influence of natural variation on fundamental aspects of nuclear morphology. We show that the natural variants influencing response include both coding and non-coding variation, and that cmQTL haplotypes can be used to predict response in orthogonal cell lines. Our study sheds light on the major molecular initiating events of oxidative stress that are under genetic regulation, including the NRF2-mediated antioxidant response, cellular detoxification pathways, DNA damage repair response, and cell death trajectories.

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.

Functional diversity of microbial eukaryotes in a meromictic lake: Coupling between metatranscriptomic and a trait-based approach

The advent of high-throughput sequencing has led to the discovery of a considerable diversity of microbial eukaryotes in aquatic ecosystems, nevertheless, their function and contribution to the trophic food web functioning remain poorly characterized especially in freshwater ecosystems. Based on metabarcoding data obtained from a meromictic lake ecosystem (Pavin, France), we performed a morpho-physio-phenological traits-based approach to infer functional groups of microbial eukaryotes. Metatranscriptomic data were also analysed to assess the metabolic potential of these groups across the diel cycle, size fraction, sampling depth, and periods. Our analysis highlights a huge microbial eukaryotic diversity in the monimolimnion characterized by numerous saprotrophs expressing transcripts related to sulfur and nitrate metabolism as well as dissolved and particulate organic matter degradation. We also describe strong seasonal variations of microbial eukaryotes in the mixolimnion, especially for parasites and mixoplankton. It appears that the water mixing (occurring during spring and autumn) which benefits photosynthetic host communities also promotes parasitic fungi dissemination and over-expression of genes involved in the zoospore phototaxis and stage transition in the parasitic cycle. Mixoplanktonic haptophytes over-expressing photosynthesis-, endocytosis- and phagosome-linked genes under nutrient limitation also suggest that phagotrophy may provide them an advantage over non-phagotrophic phytoplankton.

Cell morphology QTL reveal gene by environment interactions in a genetically diverse cell population

Genetically heterogenous cell lines from laboratory mice are promising tools for population-based screening as they offer power for genetic mapping, and potentially, predictive value for in vivo experimentation in genetically matched individuals. To explore this further, we derived a panel of fibroblast lines from a genetic reference population of laboratory mice (the Diversity Outbred, DO). We then used high-content imaging to capture hundreds of cell morphology traits in cells exposed to the oxidative stress-inducing arsenic metabolite monomethylarsonous acid (MMAIII). We employed dose-response modeling to capture latent parameters of response and we then used these parameters to identify several hundred cell morphology quantitative trait loci (cmQTL). Response cmQTL encompass genes with established associations with cellular responses to arsenic exposure, including Abcc4 and Txnrd1, as well as novel gene candidates like Xrcc2. Moreover, baseline trait cmQTL highlight the influence of natural variation on fundamental aspects of nuclear morphology. We show that the natural variants influencing response include both coding and non-coding variation, and that cmQTL haplotypes can be used to predict response in orthogonal cell lines. Our study sheds light on the major molecular initiating events of oxidative stress that are under genetic regulation, including the NRF2-mediated antioxidant response, cellular detoxification pathways, DNA damage repair response, and cell death trajectories.

Mancozeb-induced cytotoxicity in human erythrocytes: enhanced generation of reactive species, hemoglobin oxidation, diminished antioxidant power, membrane damage and morphological changes

Mancozeb is an ethylene bis-dithiocarbamate fungicide extensively used in agriculture to safeguard crops from various fungal diseases. The general population is exposed to mancozeb through consumption of contaminated food or water. Here, we have investigated the effect of mancozeb on isolated human erythrocytes under in vitro conditions. Erythrocytes were treated with different concentrations of mancozeb (0, 5, 10, 25, 50, 100 μM) and incubated for 24 h at 37 °C. Analysis of biochemical parameters and cell morphology showed dose-dependent toxicity of mancozeb in human erythrocytes. Mancozeb treatment caused hemoglobin oxidation and heme degradation. Protein and lipid oxidation were enhanced, while a significant decrease was seen in reduced glutathione and total sulfhydryl content. A significant increase in the generation of reactive oxygen and nitrogen species was detected in mancozeb-treated erythrocytes. The antioxidant capacity and the activity of key antioxidant enzymes were greatly diminished, while crucial metabolic pathways were inhibited in erythrocytes. Damage to the erythrocyte membrane on mancozeb treatment was apparent from increased cell lysis and osmotic fragility, along with the impairment of the plasma membrane redox system. Mancozeb also caused morphological alterations and transformed the normal discoid-shaped erythrocytes into echinocytes and stomatocytes. Thus, mancozeb induces oxidative stress in human erythrocytes, impairs the antioxidant defense system, oxidizes cellular components, that will adversely affect erythrocyte structure and function.

Integrated insight into the molecular mechanisms of selenium-modulated, MPP+-induced cytotoxicity in a Parkinson's disease model

OBJECTIVE

Parkinson's disease (PD) is a neurodegenerative disease that is associated with oxidative stress. Due to the anti-inflammatory and antioxidant functions of Selenium (Se), this molecule may have neuroprotective functions in PD; however, the involvement of Se in such a protective function is unclear.

METHODS

1-methyl-4-phenylpyridinium (MPP⁺), which inhibits mitochondrial respiration, is generally used to produce a reliable cellular model of PD. In this study, a MPP⁺-induced PD model was used to test if Se could modulate cytotoxicity, and we further capture gene expression profiles following PC12 cell treatment with MPP⁺ with or without Se by genome wide high-throughput sequencing.

RESULTS

We identified 351 differentially expressed genes (DEGs) and 14 differentially expressed long non-coding RNAs (DELs) in MPP⁺-treated cells when compared to controls. We further document 244 DEGs and 27 DELs in cells treated with MPP⁺ and Se vs. cells treated with MPP⁺ only. Functional annotation analysis of DEGs and DELs revealed that these groups were enriched in genes that respond to reactive oxygen species (ROS), metabolic processes, and mitochondrial control of apoptosis. Thioredoxin reductase 1 (Txnrd1) was also identified as a biomarker of Se treatment.

CONCLUSIONS

Our data suggests that the DEGs Txnrd1, Siglec1 and Klf2, and the DEL AABR07044454.1 which we hypothesize to function in cis on the target gene Cdkn1a, may modulate the underlying neurodegenerative process, and act a protective function in the PC12 cell PD model. This study further systematically demonstrated that mRNAs and lncRNAs induced by Se are involved in neuroprotection in PD, and provides novel insight into how Se modulates cytotoxicity in the MPP⁺-induced PD model.

GTP energy dependence of endocytosis and autophagy in the aging brain and Alzheimer's disease

Increased interest in the aging and Alzheimer's disease (AD)-related impairments in autophagy in the brain raise important questions about regulation and treatment. Since many steps in endocytosis and autophagy depend on GTPases, new measures of cellular GTP levels are needed to evaluate energy regulation in aging and AD. The recent development of ratiometric GTP sensors (GEVALS) and findings that GTP levels are not homogenous inside cells raise new issues of regulation of GTPases by the local availability of GTP. In this review, we highlight the metabolism of GTP in relation to the Rab GTPases involved in formation of early endosomes, late endosomes, and lysosomal transport to execute the autophagic degradation of damaged cargo. Specific GTPases control macroautophagy (mitophagy), microautophagy, and chaperone-mediated autophagy (CMA). By inference, local GTP levels would control autophagy, if not in excess. Additional levels of control are imposed by the redox state of the cell, including thioredoxin involvement. Throughout this review, we emphasize the age-related changes that could contribute to deficits in GTP and AD. We conclude with prospects for boosting GTP levels and reversing age-related oxidative redox shift to restore autophagy. Therefore, GTP levels could regulate the numerous GTPases involved in endocytosis, autophagy, and vesicular trafficking. In aging, metabolic adaptation to a sedentary lifestyle could impair mitochondrial function generating less GTP and redox energy for healthy management of amyloid and tau proteostasis, synaptic function, and inflammation.

The neuronal nucleus: a new battlefield in fight against neurodegeneration

Aging is an inevitable fact of life which brings along a series of age-associated diseases. Although medical innovations and patient care improvement have increased our life expectancy, the rate of age-associated diseases have also increased. Nervous system is specifically prone to these diseases that cause neuronal loss in different anatomical regions. Alzheimer's disease is the best-known example of age-associated illnesses and is diagnosed by accumulation of intracellular Neurofibrillary tangles and extracellular Amyloid Plaques resulting in dementia. However, therapeutic attempts aiming at the removal of these plaques and tangles to reverse the cognitive decline have generally failed in human patients and may compromise the patient's health. We have learnt that interruption of neuronal housekeeping systems such as autophagy contributes to formation of these aggregates, and therefore understanding the underlying mechanisms that lead to failure of these endogenous protective systems may provide valuable information and novel therapies. The house keeping systems are delicately regulated through gene expression and chromatin modifications in the nucleus, however, the contribution of this largest cellular organelle in pathophysiology of the disease has been overlooked. During the last few years, a wealth of information on neuronal nucleus has emerged that provides a strong rationale for examining its contribution to the pathophysiology of the disease. In this research perspective, I have attempted to summarize the latest research on neuronal nucleus, with a special focus on nuclear lamina damage and its downstream events to rationalize the need for focusing on the neuronal nucleus as a therapeutic target.

Temozolomide, Simvastatin and Acetylshikonin Combination Induces Mitochondrial-Dependent Apoptosis in GBM Cells, Which Is Regulated by Autophagy

Glioblastoma multiforme (GBM) is one of the deadliest cancers. Temozolomide (TMZ) is the most common chemotherapy used for GBM patients. Recently, combination chemotherapy strategies have had more effective antitumor effects and focus on slowing down the development of chemotherapy resistance. A combination of TMZ and cholesterol-lowering medications (statins) is currently under investigation in in vivo and clinical trials. In our current investigation, we have used a triple-combination therapy of TMZ, Simvastatin (Simva), and acetylshikonin, and investigated its apoptotic mechanism in GBM cell lines (U87 and U251). We used viability, apoptosis, reactive oxygen species, mitochondrial membrane potential (MMP), caspase-3/-7, acridine orange (AO) and immunoblotting autophagy assays. Our results showed that a TMZ/Simva/ASH combination therapy induced significantly more apoptosis compared to TMZ, Simva, ASH, and TMZ/Simva treatments in GBM cells. Apoptosis via TMZ/Simva/ASH treatment induced mitochondrial damage (increase of ROS, decrease of MMP) and caspase-3/7 activation in both GBM cell lines. Compared to all single treatments and the TMZ/Simva treatment, TMZ/Simva/ASH significantly increased positive acidic vacuole organelles. We further confirmed that the increase of AVOs during the TMZ/Simva/ASH treatment was due to the partial inhibition of autophagy flux (accumulation of LC3β-II and a decrease in p62 degradation) in GBM cells. Our investigation also showed that TMZ/Simva/ASH-induced cell death was depended on autophagy flux, as further inhibition of autophagy flux increased TMZ/Simva/ASH-induced cell death in GBM cells. Finally, our results showed that TMZ/Simva/ASH treatment potentially depends on an increase of Bax expression in GBM cells. Our current investigation might open new avenues for a more effective treatment of GBM, but further investigations are required for a better identification of the mechanisms.

Advances in the Functions of Thioredoxin System in Central Nervous System Diseases

Significance: The thioredoxin system comprises thioredoxin (Trx), thioredoxin reductase (TrxR), and nicotinamide adenine dinucleotide phosphate, besides an endogenous Trx inhibitor, the thioredoxin-interacting protein (TXNIP). The Trx system plays critical roles in maintaining the redox homeostasis in the central nervous system (CNS), in which oxidative stress damage is prone to occurrence due to its high-energy demand. Recent Advances: Increasing studies have demonstrated that the expression or activity of Trx/TrxR is usually decreased and that TXNIP expression is increased in patients with CNS diseases, including neurodegenerative diseases, cerebral ischemia, traumatic brain injury, and depression, as well as in their cellular and animal models. The compromise of Trx/TrxR enhances the susceptibility of neurons to related pathological state. Increased TXNIP not only enhances the inhibition of Trx activity, but also activates the NOD-like receptor protein 3 inflammasome, resulting in neuroinflammation in the brain. Critical Issues: In this review, we highlight the sources of oxidative stress in the CNS. The expression and function of the Trx system are summarized in different CNS diseases. This review also mentions that some inducers of Trx show neuroprotection in CNS diseases. Future Directions: Accumulating evidence has demonstrated the important roles of the Trx system in CNS diseases, suggesting that the Trx system may be a promising therapeutic target for CNS diseases. Further study should aim to develop the most effective inducers of Trx and specific inhibitors of TXNIP and to apply them in the clinical trials for the treatment of CNS diseases. Antioxid. Redox Signal. 38, 425-441.

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.

Effect of sub-lethal ammonia and nitrite stress on autophagy and apoptosis in hepatopancreas of Pacific whiteleg shrimp Litopenaeusvannamei

Oxidative stress caused by ammonia and nitrite, affect the health and growth of aquaculture animals, results in oxidative damages. However, the toxic mechanism and pathogenesis of ammonia and nitrite to aquatic invertebrates are not completely clear. The present study was conducted to investigate the effects of sub-lethal ammonia and nitrite on autophagy and apoptosis in hepatopancreas of Pacific whiteleg shrimp Litopenaeus vannamei. Shrimps were exposed to sub-lethal ammonia (20 mg/L) and nitrite (20 mg/L) for 72 h, respectively. Hepatopancreas was collected for investigating the autophagy and apoptosis under stress conditions. The results showed that ammonia stress could induce up-regulated of autophagy (ATG3, ATG4, ATG10 and ATG12) and apoptosis (Caspase3 and P53) genes transcription. Nitrite stress could also induce up-regulated of autophagy (ATG3, ATG4, ATG5 and ATG10) and apoptosis (Caspase3) genes transcription. The expression of the autophagy related genes increased at first and then decreased with increasing exposure time. The atrophy, lysis, vacuolation of cell and other tissue damages in hepatopancreas were observed after 72h exposure to ammonia and nitrite. The results indicated that ammonia and nitrite stress could induce autophagy and apoptosis, and results in oxidative damage.

Oxidative Stress and Mitochondrial Dysfunction Associated with Peripheral Neuropathy in Type 1 Diabetes

Significance: This review highlights the many intracellular processes generating reactive oxygen species (ROS) in the peripheral nervous system in the context of type 1 diabetes. The major sources of superoxide and hydrogen peroxide (H₂O₂) are described, and scavenging systems are explained. Important roles of ROS in regulating normal redox signaling and in a disease setting, such as diabetes, contributing to oxidative stress and cellular damage are outlined. The primary focus is the role of hyperglycemia in driving elevated ROS production and oxidative stress contributing to neurodegeneration in diabetic neuropathy (within the dorsal root ganglia [DRG] and peripheral nerve). Recent Advances: Contributors to ROS production under high intracellular glucose concentration such as mitochondria and the polyol pathway are discussed. The primarily damaging impact of ROS on multiple pathways including mitochondrial function, endoplasmic reticulum (ER) stress, autophagy, and epigenetic signaling is covered. Critical Issues: There is a strong focus on mechanisms of diabetes-induced mitochondrial dysfunction and how this may drive ROS production (in particular superoxide). The mitochondrial sites of superoxide/H₂O₂ production via mitochondrial metabolism and aerobic respiration are reviewed. Future Directions: Areas for future development are highlighted, including the need to clarify diabetes-induced changes in autophagy and ER function in neurons and Schwann cells. In addition, more clarity is needed regarding the sources of ROS production at mitochondrial sites under high glucose concentration (and lack of insulin signaling). New areas of study should be introduced to investigate the role of ROS, nuclear lamina function, and epigenetic signaling under diabetic conditions in peripheral nerve.

Epigenetic regulation of autophagy in gastrointestinal cancers

The development of novel therapeutic approaches is necessary to manage gastrointestinal cancers (GICs). Considering the effective molecular mechanisms involved in tumor growth, the therapeutic response is pivotal in this process. Autophagy is a highly conserved catabolic process that acts as a double-edged sword in tumorigenesis and tumor inhibition in a context-dependent manner. Depending on the stage of malignancy and cellular origin of the tumor, autophagy might result in cancer cell survival or death during the GICs' progression. Moreover, autophagy can prevent the progression of GIC in the early stages but leads to chemoresistance in advanced stages. Therefore, targeting specific arms of autophagy could be a promising strategy in the prevention of chemoresistance and treatment of GIC. It has been revealed that autophagy is a cytoplasmic event that is subject to transcriptional and epigenetic regulation inside the nucleus. The effect of epigenetic regulation (including DNA methylation, histone modification, and expression of non-coding RNAs (ncRNAs) in cellular fate is still not completely understood. Recent findings have indicated that epigenetic alterations can modify several genes and modulators, eventually leading to inhibition or promotion of autophagy in different cancer stages, and mediating chemoresistance or chemosensitivity. The current review focuses on the links between autophagy and epigenetics in GICs and discusses: 1) How autophagy and epigenetics are linked in GICs, by considering different epigenetic mechanisms; 2) how epigenetics may be involved in the alteration of cancer-related phenotypes, including cell proliferation, invasion, and migration; and 3) how epidrugs modulate autophagy in GICs to overcome chemoresistance.

Autophagy Is Involved in the Viability of Overexpressing Thioredoxin o1 Tobacco BY-2 Cells under Oxidative Conditions

Autophagy is an essential process for the degradation of non-useful components, although the mechanism involved in its regulation is less known in plants than in animal systems. Redox regulation of autophagy components is emerging as a possible key mechanism with thioredoxins (TRXs) proposed as involved candidates. In this work, using overexpressing PsTRXo1 tobacco cells (OEX), which present higher viability than non-overexpressing cells after H₂O₂ treatment, we examine the functional interaction of autophagy and PsTRXo1 in a collaborative response. OEX cells present higher gene expression of the ATG (Autophagy related) marker ATG4 and higher protein content of ATG4, ATG8, and lipidated ATG8 as well as higher ATG4 activity than control cells, supporting the involvement of autophagy in their response to H₂O₂. In this oxidative situation, autophagy occurs in OEX cells as is evident from an accumulation of autolysosomes and ATG8 immunolocalization when the E-64d autophagy inhibitor is used. Interestingly, cell viability decreases in the presence of the inhibitor, pointing to autophagy as being involved in cell survival. The in vitro interaction of ATG4 and PsTRXo1 proteins is confirmed by dot-blot and co-immunoprecipitation assays as well as the redox regulation of ATG4 activity by PsTRXo1. These findings extend the role of TRXs in mediating the redox regulation of the autophagy process in plant cells.

Reactive oxygen species prevent lysosome coalescence during PIKfyve inhibition

Lysosomes are terminal, degradative organelles of the endosomal pathway that undergo repeated fusion-fission cycles with themselves, endosomes, phagosomes, and autophagosomes. Lysosome number and size depends on balanced fusion and fission rates. Thus, conditions that favour fusion over fission can reduce lysosome numbers while enlarging their size. Conversely, favouring fission over fusion may cause lysosome fragmentation and increase their numbers. PIKfyve is a phosphoinositide kinase that generates phosphatidylinositol-3,5-bisphosphate to modulate lysosomal functions. PIKfyve inhibition causes an increase in lysosome size and reduction in lysosome number, consistent with lysosome coalescence. This is thought to proceed through reduced lysosome reformation and/or fission after fusion with endosomes or other lysosomes. Previously, we observed that photo-damage during live-cell imaging prevented lysosome coalescence during PIKfyve inhibition. Thus, we postulated that lysosome fusion and/or fission dynamics are affected by reactive oxygen species (ROS). Here, we show that ROS generated by various independent mechanisms all impaired lysosome coalescence during PIKfyve inhibition and promoted lysosome fragmentation during PIKfyve re-activation. However, depending on the ROS species or mode of production, lysosome dynamics were affected distinctly. H2O2 impaired lysosome motility and reduced lysosome fusion with phagosomes, suggesting that H2O2 reduces lysosome fusogenecity. In comparison, inhibitors of oxidative phosphorylation, thiol groups, glutathione, or thioredoxin, did not impair lysosome motility but instead promoted clearance of actin puncta on lysosomes formed during PIKfyve inhibition. Additionally, actin depolymerizing agents prevented lysosome coalescence during PIKfyve inhibition. Thus, we discovered that ROS can generally prevent lysosome coalescence during PIKfyve inhibition using distinct mechanisms depending on the type of ROS.

Full-coverage regulations of autophagy by ROS: from induction to maturation

Macroautophagy/autophagy is an evolutionarily well-conserved recycling process in response to stress conditions, including a burst of reactive oxygen species (ROS) production. High level of ROS attack key cellular macromolecules. Protein cysteinyl thiols or non-protein thiols as the major redox-sensitive targets thus constitute the first-line defense. Autophagy is unique, because it removes not only oxidized/damaged proteins but also bulky ROS-generating organelles (such as mitochondria and peroxisome) to restrict further ROS production. The oxidative regulations of autophagy occur in all processes of autophagy, from induction, phagophore nucleation, phagophore expansion, autophagosome maturation, cargo delivery to the lysosome, and finally to degradation of the cargo and recycling of the products, as well as autophagy gene transcription. Mechanically, these regulations are achieved through direct or indirect manners. Direct thiol oxidation of key proteins such as ATG4, ATM and TFEB are responsible for specific regulations in phagophore expansion, cargo recognition and autophagy gene transcription, respectively. Meanwhile, oxidation of certain redox-sensitive chaperone-like proteins (e.g. PRDX family members and PARK7) may impair a nonspecifically local reducing environment in the phagophore membrane, and influence BECN1-involved phagophore nucleation and mitophagy recognition. However, ROS do exhibit some inhibitory effects on autophagy through direct oxidation of key autophagy regulators such as ATG3, ATG7 and SENP3 proteins. SQSTM1 provides an alternative antioxidant mechanism when autophagy is unavailable or impaired. However, it is yet to be unraveled how cells evolve to equip proteins with different redox susceptibility and in their correct subcellular positions, and how cells fine-tune autophagy machinery in response to different levels of ROS.Abbreviations: AKT1/PKB: AKT serine/threonine kinase 1; AMPK: AMP-activated protein kinase; ATG: autophagy related; ATM: ATM serine/threonine kinase; BAX: BCL2 associated X, apoptosis regulator; BECN1: beclin 1; BH3: BCL2-homology-3; CAV1: caveolin 1; CCCP: carbonyl cyanide m-chlorophenylhydrazone; CTSB: cathepsin B; CTSL: cathepsin L; DAPK: death associated protein kinase; ER: endoplasmic reticulum; ETC: electron transport chain; GSH: glutathione; GSTP1: glutathione S-transferase pi 1; H₂O₂: hydrogen peroxide; HK2: hexokinase 2; KEAP1: kelch like ECH associated protein 1; MAMs: mitochondria-associated ER membranes; MAP1LC3B/LC3: microtubule associated protein 1 light chain 3 beta; MAPK8/JNK1: mitogen-activated protein kinase 8; MAP3K5/ASK1: mitogen-activated protein kinase kinase kinase 5; MCOLN1: mucolipin 1; MMP: mitochondrial membrane potential; MTOR: mechanistic target of rapamycin kinase; NFE2L2/NRF2: nuclear factor, erythroid 2 like 2; NFKB1: nuclear factor kappa B subunit 1; NOX: NADPH oxidase; O^2-: superoxide radical anion; p-Ub: phosphorylated Ub; PARK7/DJ-1: Parkinsonism associated deglycase; PE: phosphatidylethanolamine; PEX5: peroxisomal biogenesis factor 5; PINK1: PTEN induced kinase 1; PPP3CA/calcineurin: protein phosphatase 3 catalytic subunit beta; PRDX: peroxiredoxin; PRKAA1: protein kinase AMP-activated catalytic subunit alpha 1; PRKD/PKD: protein kinase D; PRKN/parkin: parkin RBR E3 ubiquitin protein ligase; PtdIns3K: class III phosphatidylinositol 3-kinase; PtdIns3P: phosphatidylinositol-3-phosphate; PTEN: phosphatase and tensin homolog; ROS: reactive oxygen species; SENP3: SUMO specific peptidase 3; SIRT1: sirtuin 1; SOD1: superoxide dismutase 1; SQSTM1/p62: sequestosome 1; SUMO: small ubiquitin like modifier; TFEB: transcription factor EB; TRAF6: TNF receptor associated factor 6; TSC2: TSC complex subunit 2; TXN: thioredoxin; TXNRD1: thioredoxin reductase 1; TXNIP: thioredoxin interacting protein; Ub: ubiquitin; ULK1: unc-51 like autophagy activating kinase 1.

A Signature of Autophagy-Related Long Non-coding RNA to Predict the Prognosis of Breast Cancer

Background: A surge in newly diagnosed breast cancer has overwhelmed the public health system worldwide. Joint effort had beed made to discover the genetic mechanism of these disease globally. Accumulated research has revealed autophagy may act as a vital part in the pathogenesis of breast cancer.

Objective: Aim to construct a prognostic model based on autophagy-related lncRNAs and investigate their potential mechanisms in breast cancer.

Methods: The transcriptome data and clinical information of patients with breast cancer were obtained from The Cancer Genome Atlas (TCGA) database. Autophagy-related genes were obtained from the Human Autophagy Database (HADb). Long non-coding RNAs (lncRNAs) related to autophagy were acquired through the Pearson correlation analysis. Univariate Cox regression analysis as well as the least absolute shrinkage and selection operator (LASSO) regression analysis were used to identify autophagy-related lncRNAs with prognostic value. We constructed a risk scoring model to assess the prognostic significance of the autophagy-related lncRNAs signatures. The nomogram was then established based on the risk score and clinical indicators. Through the calibration curve, the concordance index (C-index) and receiver operating characteristic (ROC) curve analysis were evaluated to obtain the model's predictive performance. Subgroup analysis was performed to evaluate the differential ability of the model. Subsequently, gene set enrichment analysis was conducted to investigate the potential functions of these lncRNAs.

Results: We attained 1,164 breast cancer samples from the TCGA database and 231 autophagy-related genes from the HAD database. Through correlation analysis, 179 autophagy-related lncRNAs were finally identified. Univariate Cox regression analysis and LASSO regression analysis further screened 18 prognosis-associated lncRNAs. The risk scoring model was constructed to divide patients into high-risk and low-risk groups. It was found that the low-risk group had better overall survival (OS) than those of the high-risk group. Then, the nomogram model including age, tumor stage, TNM stage and risk score was established. The evaluation index (C-index: 0.78, 3-year OS AUC: 0.813 and 5-year OS AUC: 0.785) showed that the nomogram had excellent predictive power. Subgroup analysis showed there were difference in OS between high-risk and low-risk patients in different subgroups (stage I-II, ER positive, Her-2 negative and non-TNBC subgroups; all P < 0.05). According to the results of gene set enrichment analysis, these lncRNAs were involved in the regulation of multicellular organismal macromolecule metabolic process in multicellular organisms, nucleotide excision repair, oxidative phosphorylation, and TGF-β signaling pathway.

Conclusions: We identified 18 autophagy-related lncRNAs with prognostic value in breast cancer, which may regulate tumor growth and progression in multiple ways.

The Potential Roles of Redox Enzymes in Alzheimer's Disease: Focus on Thioredoxin

Alzheimer's disease (AD) is the most common neurodegenerative diseases. Increasing studies have demonstrated the critical importance for redox proteins mediating neuronal protection in models of AD. This review briefly describes some of the risk factors contributing to AD, specifically highlighting the important roles of oxidative stress in the pathology of AD. Then this article concisely introduces the dysregulation and functions of two main redox enzymes, peroxiredoxins and glutaredoxins, in AD models. This review emphasizes the neuroprotective role of the third redox enzyme thioredoxin (Trx), an important multifunctional protein regulating cellular redox status. This commentary not only summarizes the alterations of Trx expression in AD patients and models, but also reviews the potential effects and mechanisms of Trx, Trx-related molecules and Trx-inducing compounds against AD. In conclusion, Trx has a potential neuroprotection in AD and may be very promising for clinical therapy of AD in the future.

Cathepsin B is an executioner of ferroptosis

Ferroptosis is a necrotic form of cell death caused by inactivation of the glutathione system and uncontrolled iron-mediated lipid peroxidation. Increasing evidence implicates ferroptosis in a wide range of diseases from neurotrauma to cancer, highlighting the importance of identifying an executioner system that can be exploited for clinical applications. In this study, using pharmacological and genetic models of ferroptosis, we observed that lysosomal membrane permeabilization and cytoplasmic leakage of cathepsin B unleashes structural and functional changes in mitochondria and promotes a not previously reported cleavage of histone H3. Inhibition of cathepsin-B robustly rescued cellular membrane integrity and chromatin degradation. We show that these protective effects are independent of glutathione peroxidase-4 and are mediated by preventing lysosomal membrane damage. This was further confirmed when cathepsin B knockout primary fibroblasts remained unaffected in response to various ferroptosis inducers. Our work identifies new and yet-unrecognized aspects of ferroptosis and identifies cathepsin B as a mediator of ferroptotic cell death.

Autophagy and the Wnt signaling pathway: A focus on Wnt/β-catenin signaling

Cellular homeostasis and adaptation to various environmental conditions are importantly regulated by the sophisticated mechanism of autophagy and its crosstalk with Wnt signaling and other developmental pathways. Both autophagy and Wnt signaling are involved in embryogenesis and differentiation. Autophagy is responsible for degradation and recycling of cytosolic materials by directing them to lysosomes through the phagophore compartment. A dual feedback mechanism regulates the interface between autophagy and Wnt signaling pathways. During nutrient deprivation, β-catenin and Dishevelled (essential Wnt signaling proteins) are targeted for autophagic degradation by LC3. When Wnt signaling is activated, β-catenin acts as a corepressor of one of the autophagy proteins, p62. In contrast, another key Wnt signaling protein, GSK3β, negatively regulates the Wnt pathway and has been shown to induce autophagy by phosphorylation of the TSC complex. This article reviews the interplay between autophagy and Wnt signaling, describing how β-catenin functions as a key cellular integration point coordinating proliferation with autophagy, and it discusses the clinical importance of the crosstalk between these mechanisms.

Novel Phenylmethylenecyclohexenone Derivatives as Potent TrxR Inhibitors Display High Antiproliferative Activity and Induce ROS, Apoptosis, and DNA Damage

The natural product piperlonguminine (PL) has been shown to exert potential anticancer activity against several types of cancer via elevation of reactive oxidative species (ROS). However, the application of PL has been limited due to its poor water solubility and moderate activity. To improve PL's potency, we designed and synthesized a series of 17 novel phenylmethylenecyclohexenone derivatives and evaluated their pharmacological properties. Most of them exerted antiproliferative activities against four cancer cell lines with IC₅₀ values lower than PL. Among these, compound 10 e not only showed good water solubility and exerted the most potent antiproliferative activity against HGC27 cells (IC₅₀ =0.76 μM), which was 10-fold lower than PL (IC₅₀ =7.53 μM), but also exhibited lower cytotoxicity in human normal gastric epithelial cells GES-1 compared with HGC27 cells. Mechanistically, compound 10 e inhibited thioredoxin reductase (TrxR) activity, increased ROS levels, and diminished mitochondrial transmembrane potential (MTP) in HGC27 cells. Furthermore, 10 e also induced G₂ /M cell-cycle arrest, and triggered cancer cell apoptosis through the regulation of apoptotic proteins. Finally, 10 e promoted DNA damage in HGC27 cells via the activation of the H2AX(S139ph) and p53 signaling. In conclusion, 10 e, with prominent tumor selectivity and water solubility, could be a promising candidate for the treatment of cancer and, as such, warrants further investigation.

Oxidative damage of lysosomes in regulated cell death systems: Pathophysiology and pharmacologic interventions

Lysosomes are small specialized organelles containing a variety of different hydrolase enzymes that are responsible for degradation of all macromolecules, entering the cells through the endosomal system or originated from the internal sources. This allows for transport and recycling of nutrients and internalization of surface proteins for antigen presentation as well as maintaining cellular homeostasis. Lysosomes are also important storage compartments for metal ions and nutrients. The integrity of lysosomal membrane is central to maintaining their normal function, but like other cellular membranes, lysosomal membrane is subject to damage mediated by reactive oxygen species. This results in spillage of lysosomal enzymes into the cytoplasm, leading to proteolytic damage to cellular systems and organelles. Several forms of lysosomal dependent cell death have been identified in diseases. Examination of these events are important for finding treatment strategies relevant to cancer or neurodegenerative diseases as well as autoimmune deficiencies. In this review, we have examined the current literature on involvement of lysosomes in induction of programed cell death and have provided an extensive list of therapeutic approaches that can modulate cell death. Exploitation of these mechanisms can lead to novel therapies for cancer and neurodegenerative diseases.

Thioredoxin system as a gatekeeper in caspase-6 activation and nuclear lamina integrity: Implications for Alzheimer's disease

Recent reports in pathophysiology of neurodegenerative diseases (ND) have linked nuclear lamina degradation/deficits to neuronal cell death. Lamin-B1 damage is specifically involved in this process leading to nuclear envelope invagination and heterochromatin rearrangement. The underlying mechanisms involved in these events are not yet defined. In this study, while examining the effect of Thioredoxin-1(Trx1) inhibition on cell death in a model of oxidative stress, we noted robust nuclear invagination in SH-SY5Y cells. Evaluation of nuclear lamina proteins revealed lamin-B1 cleavage that was prevented by caspase-6 (CASP6) inhibitor and exacerbated after pharmacologic/genetic inhibition of Trx1 system, but not after glutathione depletion. Activation of CASP6 was upstream of CASP3/7 activation and its inhibition was sufficient to prevent cell death in our system. The effect of Trx1 redox status on CASP6 activation was assessed by administration of reduced/oxidized forms in cell-free nuclei preparation and purified enzymatic assays. Although reduced Trx1 decreased CASP6 enzymatic activity and lamin-B1 cleavage, the fully oxidized Trx1 showed opposite effects. The enhanced CASP6 activation was also associated with lower levels of DJ-1, a neuroprotective and master regulator of cellular antioxidants. The implication of our findings in ND pathophysiology was strengthened with detection of lower Trx1 levels in the hippocampi tissue of a mouse model of Alzheimer's disease. This coincided with higher CASP6 activation resulting in increased lamin-B1 and DJ-1 depletion. This study provides a first mechanistic explanation for the key regulatory role of Trx1 as a gatekeeper in activation of CASP6 and induction of nuclear invagination, an important player in ND pathophysiology.

Inhibition of VDAC1 Protects Against Glutamate-Induced Oxytosis and Mitochondrial Fragmentation in Hippocampal HT22 Cells

The involvement of glutamate in neuronal cell death in neurodegenerative diseases and neurotrauma is mediated through excitotoxicity or oxytosis. The latter process induces oxidative stress via glutamate-mediated inhibition of cysteine transporter xCT, leading to depletion of the cellular glutathione pool. Mitochondrial damage, loss of mitochondrial membrane potential (MMP), and depletion of energy metabolites have been shown in this process. The Voltage-Dependent Anion Channel-1 (VDAC1) is one of the main components of the mitochondrial outer membrane and plays a gatekeeping role in mitochondria-cytoplasm transport of metabolites. In this study, we explored the possible participation of VDAC-1 in the pathophysiology of oxytosis. Administration of glutamate in HT22 cells that lack the glutamate ionotropic receptors induced an upregulation and oligomerization of VDAC1. This was associated with an increase in ROS and loss of cell survival. Glutamate-mediated oxytosis in this model also decreased MMP and promoted ATP depletion, resulting in translocation of cytochrome c (cyt C) and apoptosis inducing factor (AIF) from mitochondria into the cytosol. This was also accompanied by cleavage of AIF to form truncated AIF. Inhibition of VDAC1 oligomerization using 4,4'-Diisothiocyanatostilbene-2,2'-disulfonate (DIDS), significantly improved the cell survival, decreased the ROS levels, improved mitochondrial functions, and decreased the mitochondrial damage. Notably, DIDS also inhibited the mitochondrial fragmentation caused by glutamate, indicating the active role of VDAC1 oligomerization in the process of mitochondrial fragmentation in oxytosis. These results suggest a critical role for VDAC1 in mitochondrial fragmentation and its potential therapeutic value against glutamate-mediated oxidative neurotoxicity.

MECP2 Mutation Interrupts Nucleolin-mTOR-P70S6K Signaling in Rett Syndrome Patients

Rett syndrome (RTT) is a severe and rare neurological disorder that is caused by mutations in the X-linked MECP2 (methyl CpG-binding protein 2) gene. MeCP2 protein is an important epigenetic factor in the brain and in neurons. In Mecp2-deficient neurons, nucleoli structures are compromised. Nucleoli are sites of active ribosomal RNA (rRNA) transcription and maturation, a process mainly controlled by nucleolin and mechanistic target of rapamycin (mTOR)-P70S6K signaling. Currently, it is unclear how nucleolin-rRNA-mTOR-P70S6K signaling from RTT cellular model systems translates into human RTT brain. Here, we studied the components of nucleolin-rRNA-mTOR-P70S6K signaling in the brain of RTT patients with common T158M and R255X mutations. Immunohistochemical examination of T158M brain showed disturbed nucleolin subcellular localization, which was absent in Mecp2-deficient homozygous male or heterozygote female mice, compared to wild type (WT). We confirmed by Western blot analysis that nucleolin protein levels are altered in RTT brain, but not in Mecp2-deficient mice. Further, we studied the expression of rRNA transcripts in Mecp2-deficient mice and RTT patients, as downstream molecules that are controlled by nucleolin. By data mining of published ChIP-seq studies, we showed MeCP2-binding at the multi-copy rRNA genes in the mouse brain, suggesting that rRNA might be a direct MeCP2 target gene. Additionally, we observed compromised mTOR-P70S6K signaling in the human RTT brain, a molecular pathway that is upstream of rRNA-nucleolin molecular conduits. RTT patients showed significantly higher phosphorylation of active mTORC1 or mTORC2 complexes compared to age- and sex-matched controls. Correlational analysis of mTORC1/2-P70S6K signaling pathway identified multiple points of deviation from the control tissues that may result in abnormal ribosome biogenesis in RTT brain. To our knowledge, this is the first report of deregulated nucleolin-rRNA-mTOR-P70S6K signaling in the human RTT brain. Our results provide important insight toward understanding the molecular properties of human RTT brain.

Thioredoxin-related protein of 14 kDa as a modulator of redox signalling pathways

Thioredoxin-related protein of 14 kDa (TRP14; also named TXNDC17 for thioredoxin domain-containing protein 17) is a highly conserved and ubiquitously expressed oxidoreductase. It is expressed in parallel with thioredoxin 1 (Trx1, TXN; TXN1), an efficient substrate for the mammalian cytosolic selenoprotein thioredoxin reductase 1 (TrxR1; TXNRD1). However, TRP14, in sharp contrast to Trx1, cannot support the activities of ribonucleotide reductase, peroxiredoxins or methionine sulfoxide reductases, thus is unable to directly support cell proliferation or antioxidant defence through these pathways. However, TRP14 has been shown to efficiently reduce l-cystine, which thereby indirectly supports glutathione synthesis. TRP14 can also suppress NF-κB signalling, is functionally linked to STAT3 signalling, and can directly reactivate oxidized protein-tyrosine phosphatase PTP1B. Furthermore, TRP14 can efficiently reduce persulfidated or nitrosylated cysteine residues in many proteins, thereby having the capacity to modulate signalling through hydrogen sulfide or NO. Additional bioinformatics analyses and observations suggest further roles for TRP14; therefore, further studies of its functions are warranted. Collectively, the results available suggest that TRP14 is a member of the thioredoxin system dedicated to the control of cellular redox signalling pathways. LINKED ARTICLES: This article is part of a themed section on Chemical Biology of Reactive Sulfur Species. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.4/issuetoc.

Pre-drug Self-assembled Nanoparticles: Recovering activity and overcoming glutathione-associated cell antioxidant resistance against photodynamic therapy

In photodynamic therapy (PDT), the elevated glutathione (GSH) of cancer cells have two sides for treatment efficacy, activation pre-drug by removing activity suppressor part (advantages) and consumption reactive oxygen species (ROS) to confer PDT resistance (disadvantages). Preparation all-in-one system by simple method to make best use of the advantages and bypass the disadvantages still were remains a technical challenge. Herein, we report a robust PDT nanoparticle with above function based on a self-assembled pyridine modified Zinc phthalocyanine (ZnPc-DTP). The activity suppressor and active part of ZnPc-DTP were linked by disulfide bond. After targeting cancer cells, GSH can react with ZnPc-DTP nanoparticles by cutting disulfide bond to release its active part (ZnPc-SH) and oxidize GSH. In vitro and in vivo results indicated that ZnPc-SH can effective suppress tumor growth under the low antioxidant tumor microenvironment (TME).

Autophagy-A key pathway for cardiac health and longevity

As average life expectancy continues to rise in the developed world, age-associated pathologies are increasing in prevalence. The hallmarks of cardiac ageing include cardiomyocyte loss, fibrosis and hypertrophy, all of which contribute to an increased incidence of cardiac disease. At the molecular level, cellular ageing is characterized by increased ROS production, mitochondrial dysfunction and the accumulation of damaged proteins and organelles. Cardiomyocytes and other senescent cell types rely upon autophagy, a lysosome-mediated degradation pathway, to remove potentially toxic protein aggregates and damaged organelles from the cellular milieu. However, increasing lines of evidence point to an age-associated decrease in cardiomyocyte autophagy, with predictably negative consequences for cardiac function and health. Conversely, stimulation of autophagy has been shown to improve cellular health and cardiac function and to increase lifespan in numerous model organisms. Clearly, autophagy represents a critical pathway for cellular vitality, as well as a promising therapeutic target for the treatment of age-related cardiac pathologies. In this review, we will discuss the mechanism of autophagy and its regulation in the cell, the role of autophagy in the ageing heart, and how the autophagy pathway might be targeted to improve cardiac health.

Gold-Based Medicine: A Paradigm Shift in Anti-Cancer Therapy?

A new era of metal-based drugs started in the 1960s, heralded by the discovery of potent platinum-based complexes, commencing with cisplatin [(H₃N)₂PtCl₂], which are effective anti-cancer chemotherapeutic drugs. While clinical applications of gold-based drugs largely relate to the treatment of rheumatoid arthritis, attention has turned to the investigation of the efficacy of gold(I) and gold(III) compounds for anti-cancer applications. This review article provides an account of the latest research conducted during the last decade or so on the development of gold compounds and their potential activities against several cancers as well as a summary of possible mechanisms of action/biological targets. The promising activities and increasing knowledge of gold-based drug metabolism ensures that continued efforts will be made to develop gold-based anti-cancer agents.

Glucocorticoid Upregulates Thioredoxin-interacting Protein in Cultured Neuronal Cells

Previous studies have shown that chronic stress and chronic stress hormone treatment induce oxidative damage in rodents. Thioredoxin (Trx) is a small redox protein that plays an important role in regulation of oxidative protein cysteine modification. A Trx reduced state is maintained by thioredoxin reductase (TrxR), and the thioredoxin-interacting protein (Txnip) is an endogenous inhibitor of Trx. The purpose of this study was to investigate the effects of chronic treatment with stress hormone corticosterone on Trx, TrxR and Txnip in cultured neuronal cells. Using immunoblotting analysis we found that although chronic corticosterone treatment had no effect on Trx and TrxR protein levels, this treatment significantly increased Txnip protein levels. Using immunocytochemistry we also found that chronic corticosterone treatment increased Txnip in both nucleus and cytosol, while glucocorticoid receptor inhibitor RU486 can block corticosterone-increased Txnip protein levels. Using biotin switch, dimedone conjugation and CRISPR/Cas9 methods we found that chronic corticosterone treatment increased protein nitrosylation and sulfenylation, while knocking out Txnip blocked corticosterone-induced protein nitrosylation and sulfenylation. Since Trx can reduce cysteine oxidative protein modification such as nitrosylation and sulfenylation, our findings suggest that chronic corticosterone treatment may upregulate Txnip by targeting glucocorticoid receptor, subsequently inhibiting Trx activity and enhancing oxidative protein cysteine modification, which contributes to corticosterone-caused oxidative damage.

Overexpression of HO-1 assisted PM2.5-induced apoptosis failure and autophagy-related cell necrosis

Severe smog/haze events accompanied by extremely high concentrations of airborne fine particulate matter (PM2.5) have emerged frequently in China and the potential health risks have attracted ever-growing attention. During these episodes, a surge in hospital visits for acute respiratory symptoms and respiratory diseases exacerbation has been reported to be associated with acute exposure to high-levels of particulate matters. To investigate cell fate determination and the underlying pathogenic mechanisms during severe haze episodes or smog events, we exposed human lung epithelial cells (BEAS-2B) to PM2.5 (0-400μg/mL) for 24h and found that high doses of PM2.5 caused cell necrosis and autophagy dysfunction, while co-treatment with the autophagy inhibitor 3-MA could partially reduce PM2.5-induced cell necrosis. Exposure to PM2.5 also increased the expression and mitochondrial transposition of heme oxygenase 1 (HO-1), which consequently reduced the release of cytochrome C from mitochondria to cytosol. Knockdown of HO-1 by siRNA attenuated the mitochondrial accumulation of HO-1, reversed HO-1-induced the reduction of cytochrome C release and promoted PM2.5-induced cell apoptosis. In contrast to necrosis, PM2.5-induced autophagy was independent of HO-1. In conclusion, our results demonstrate that acute exposure to high PM2.5 concentrations causes autophagy-related cell necrosis. The decrease in cytochrome C release and apoptosis by upregulation of HO-1 maybe assist PM2.5-induced autophagy-related cell necrosis. Further, this study reveals dual roles for HO-1 in PM2.5-induced cytotoxicity and presents a possible explanation for the onset of acute respiratory symptoms under extreme particulate air pollution.

Regulatory Role of Redox Balance in Determination of Neural Precursor Cell Fate

In 1990s, reports of discovery of a small group of cells capable of proliferation and contribution to formation of new neurons in the central nervous system (CNS) reversed a century-old concept on lack of neurogenesis in the adult mammalian brain. These cells are found in all stages of human life and contribute to normal cellular turnover of the CNS. Therefore, the identity of regulating factors that affect their proliferation and differentiation is a highly noteworthy issue for basic scientists and their clinician counterparts for therapeutic purposes. The cues for such control are embedded in developmental and environmental signaling through a highly regulated tempo-spatial expression of specific transcription factors. Novel findings indicate the importance of reactive oxygen species (ROS) in the regulation of this signaling system. The elusive nature of ROS signaling in many vital processes from cell proliferation to cell death creates a complex literature in this field. Here, we discuss the emerging thoughts on the importance of redox regulation of proliferation and maintenance in mammalian neural stem and progenitor cells under physiological and pathological conditions. The current knowledge on ROS-mediated changes in redox-sensitive proteins that govern the molecular mechanisms in proliferation and differentiation of these cells is reviewed.

Differential redox sensitivity of cathepsin B and L holds the key to autophagy-apoptosis interplay after Thioredoxin reductase inhibition in nutritionally stressed SH-SY5Y cells

Reactive oxygen species (ROS) are essential for induction of protective autophagy, however unexpected rise in cellular ROS levels overpowers the cellular defense and therefore promotes the programmed apoptotic cell death. We recently reported that inhibition of thioredoxin reductase (TrxR) in starving SH-SY5Y cells interrupted autophagy flux by induction of lysosomal deficiency and promoted apoptosis. (Free Radic Biol Med. 2016: 101:53-70). Here, we aimed to elucidate the underlying mechanisms during autophagy-apoptosis interplay, and focused on regulation of cathepsin B (CTSB) and L (CTSL), the pro-apoptotic and pro-autophagy cathepsins respectively. Inhibition of TrxR by Auranofin, caused lysosomal membrane permeabilization (LMP) that was associated with a significant upregulation of CTSB activity, despite no significant changes in CTSB protein level. Conversely, a significant rise in CTSL protein levels was observed without any apparent change in CTSL activity. Using thiol-trapping techniques to examine the differential sensitivity of cathepsins to oxidative stress, we discovered that Auranofin-mediated oxidative stress interferes with CTSL processing and thereby interrupts its pro-autophagy function. No evidence of CTSB susceptibility to oxidative stress was observed. Our data suggest that cellular fate in these conditions is mediated by two concurrent systems: while oxidative stress prevents the protective autophagy by inhibition of CTSL processing, concomitantly, apoptosis is induced by increasing lysosomal membrane permeability and leakage of CTSB into cytoplasm. Inhibition of CTSB in these conditions inhibited apoptosis and increased cell viability. To our knowledge this is the first report uncovering the impact of redox environment on autophagy-apoptosis interplay in neuronal cells.