Nrf2 is a direct PERK substrate and effector of PERK-dependent cell survival

Crosstalk between ferroptosis and endoplasmic reticulum stress: A potential target for ovarian cancer therapy (Review)

Ferroptosis is a unique mode of cell death driven by iron‑dependent phospholipid peroxidation, and its mechanism primarily involves disturbances in iron metabolism, imbalances in the lipid antioxidant system and accumulation of lipid peroxides. Protein processing, modification and folding in the endoplasmic reticulum (ER) are closely related regulatory processes that determine cell function, fate and survival. The uncontrolled proliferative capacity of malignant cells generates an unfavorable microenvironment characterized by high metabolic demand, hypoxia, nutrient deprivation and acidosis, which promotes the accumulation of misfolded or unfolded proteins in the ER, leading to ER stress (ERS). Ferroptosis and ERS share common pathways in several diseases, and the two interact to affect cell survival and death. Additionally, cell death pathways are not linear signaling cascades, and different pathways of cell death may be interrelated at multiple levels. Ferroptosis and ERS in ovarian cancer (OC) have attracted increasing research interest; however, both are discussed separately regarding OC. The present review aims to summarize the associations and potential links between ferroptosis and ERS, aiming to provide research references for the development of therapeutic approaches for the management of OC.

Unraveling the functional and molecular interplay between cellular senescence and the unfolded protein response

Senescence is a complex cellular state that can be considered as a stress response phenotype. A decade ago, we suggested the intricate connections between unfolded protein response (UPR) signaling and the development of the senescent phenotype. Over the past ten years, significant advances have been made in understanding the multifaceted role of the UPR in regulating cellular senescence, highlighting its contribution to biological processes such as oxidative stress and autophagy. In this updated review, we expand these interconnections with the benefit of new insights, and we suggest that targeting specific components of the UPR could provide novel therapeutic strategies to mitigate the deleterious effects of senescence, with significant implications for age-related pathologies and geroscience.

Repurposing Sigma-1 Receptor-Targeting Drugs for Therapeutic Advances in Neurodegenerative Disorders

Neurodegenerative disorders, such as Alzheimer's, Parkinson's, and Huntington's disease, due to their multifaced and complicated nature, remain uncurable and impose substantial financial and human burdens on society. Therefore, developing new innovative therapeutic strategies is vital. In this context, drug repurposing has emerged as a promising avenue to expedite the development of treatments for these challenging conditions. One particularly compelling target in this regard is the chaperone protein sigma-1 receptor (S1R), which has garnered significant attention for its neuroprotective properties. Interestingly, several medications, including fluvoxamine (an antidepressant), dextromethorphan (a cough suppressant), and amantadine (an antiviral), which were initially developed for unrelated indications, have shown encouraging results in neurodegenerative therapy through S1R activation. These findings suggest that existing drugs in pharmacopeias can play an essential role in alleviating neurodegenerative symptoms by modulating S1R, thereby offering a faster route and cost-effective path to clinical applications compared to the de novo development of entirely new compounds. Furthermore, as a synergistic benefit, combining S1R-targeting drugs with other therapeutic agents may also improve treatment efficacy. In this review, we highlight key repurposed drugs targeting S1R and explore their mechanisms of action, shedding light on their emerging therapeutic potential in the fight against neurodegeneration.

Keap1-independent Nrf2 regulation: A novel therapeutic target for treating kidney disease

The transcription factor NF-E2-related factor 2 (Nrf2) is a master regulator of antioxidant responses in mammals, where it plays a critical role in detoxification, maintaining cellular homeostasis, combating inflammation and fibrosis, and slowing disease progression. Kelch-like ECH-associated protein 1 (Keap1), an adaptor subunit of Cullin 3-based E3 ubiquitin ligase, serves as a critical sensor of oxidative and electrophilic stress, regulating Nrf2 activity by sequestering it in the cytoplasm, leading to its proteasomal degradation and transcriptional repression. However, the clinical potential of targeting the Keap1-dependent Nrf2 regulatory pathway has been limited. This is evidenced by early postnatal lethality in Keap1 knockout mice, as well as significant adverse events after pharmacological blockade of Keap1 in human patients with Alport syndrome as well as in those with type 2 diabetes mellitus and chronic kidney disease. The exact underlying mechanisms remain elusive, but may involve non-specific and systemic activation of the Nrf2 antioxidant response in both injured and normal tissues. Beyond Keap1-dependent regulation, Nrf2 activity is modulated by Keap1-independent mechanisms, including transcriptional, epigenetic, and post-translational modifications. In particular, GSK3β has emerged as a critical convergence point for these diverse signaling pathways. Unlike Keap1-dependent regulation, GSK3β-mediated Keap1-independent Nrf2 regulation does not affect basal Nrf2 activity but modulates its response at a delayed/late phase of cellular stress. This allows fine-tuning of the inducibility, magnitude, and duration of the Nrf2 response specifically in stressed or injured tissues. As one of the most metabolically active organs, the kidney is a major source of production of reactive oxygen and nitrogen species and also a vulnerable organ to oxidative damage. Targeting the GSK3β-mediated Nrf2 regulatory pathway represents a promising new approach for the treatment of kidney disease.

Targeting Endoplasmic Reticulum Stress by Natural and Chemical Compounds Ameliorates Cisplatin-Induced Nephrotoxicity: A Review

Cisplatin is a chemotherapeutic that dose-dependently causes renal complications such as decreased kidney function and acute kidney injury. The endoplasmic reticulum (ER) is responsible for calcium homeostasis and protein folding and plays a major part in cisplatin's nephrotoxicity. The current article reviews how chemical and natural compounds modulate cisplatin-induced apoptosis, autophagy, and inflammation by inhibiting ER stress signaling pathways. The available evidence indicates that natural compounds (Achyranthes aspera water-soluble extract, morin hydrate, fucoidan, isoliquiritigenin, leonurine, epigallocatechin-3-gallate, grape seed proanthocyanidin, and ginseng polysaccharide) and chemicals (Sal003, NSC228155, TUG891, dorsomorphin (compound C), HC-030031, dexmedetomidine, and recombinant human erythropoietin (rHuEpo)) can alleviate cisplatin nephrotoxicity by suppression of ER stress signaling pathways including IRE1α/ASK1/JNK, PERK-eIF2α-ATF4, and ATF6, as well as PI3K/AKT signaling pathway. Since ER and related signaling pathways are important in cisplatin nephrotoxicity, agents that can inhibit the abovementioned signaling pathways may hold promise in alleviating this untoward adverse effect.

Exploring the links between polyphenols, Nrf2, and diabetes: A review

Diabetes mellitus, a complex metabolic disorder, is marked by chronic hyperglycemia that drives oxidative stress and inflammation, leading to complications such as neuropathy, retinopathy, and cardiovascular disease. The Nrf2 pathway, a key regulator of cellular antioxidant defenses, plays a vital role in mitigating oxidative damage and maintaining glucose homeostasis. Dysfunction of Nrf2 has been implicated in the progression of diabetes and its related complications. Polyphenols, a class of plant-derived bioactive compounds, have shown potential in modulating the Nrf2 pathway. Numerous compounds have been found to activate Nrf2 through mechanisms including Keap1 interaction, transcriptional regulation, and epigenetic modification. Preclinical studies indicate their ability to reduce reactive oxygen species (ROS), improve insulin sensitivity, and attenuate inflammation in diabetic models. Clinical trials with certain polyphenols, such as resveratrol, have demonstrated improvements in glycemic parameters, though results remain inconsistent. While polyphenols show promise as a component of non-pharmacological approaches to diabetes management, challenges such as bioavailability, individual variability in response, and limited clinical evidence highlight the need for further investigation. Continued research could enhance understanding of their mechanisms and improve their practical application in mitigating diabetes-related complications.

Diroximel Fumarate Acts Through Nrf2 to Attenuate Methylglyoxal-Induced Nociception in Mice and Decrease ISR Activation in DRG Neurons

Diabetic neuropathic pain is associated with elevated plasma levels of methylglyoxal (MGO). MGO is a metabolite of glycolysis that causes pain hypersensitivity in mice by stimulating the phosphorylation of eukaryotic initiation factor 2α (p-eIF2α) and subsequently activating the integrated stress response (ISR). We first established that Zucker diabetic fatty rats have enhanced MGO signaling, engage ISR, and develop pain hypersensitivity. Since nuclear factor erythroid 2-related factor 2 (Nrf2) regulates the expression of antioxidant proteins that neutralize MGO, we hypothesized that fumarates, like diroximel fumarate (DRF), will stimulate Nrf2 signaling, and prevent MGO-induced ISR and pain hypersensitivity. DRF (100 mg/kg) treated animals were protected from developing MGO (20 ng) induced mechanical and cold hypersensitivity. Mechanistically, DRF treatment protected against MGO-induced increase in p-eIF2α levels in the sciatic nerve and reduced loss of intraepidermal nerve fiber density. Using Nrf2 knockout mice, we demonstrate that Nrf2 is necessary for the antinociceptive effects of DRF. Cotreatment of MGO (1 µmol/L) with monomethyl fumarate (10, 20, and 50 µmol/L), the active metabolite of DRF, prevented ISR in both mouse and human dorsal root ganglia neurons. Our data show that targeting Nrf2 with DRF is a strategy to potentially alleviate pain associated with elevated MGO levels.

ARTICLE HIGHLIGHTS

Phosphorylation of eIF2α suppresses the impairment of GSH/NADPH homeostasis and mitigates the activation of cell death pathways, including ferroptosis, during ER stress

eIF2α Phosphorylation helps maintain cellular homeostasis and overcome endoplasmic reticulum (ER) stress through transcriptional and translational reprogramming. This study aims to elucidate the transcriptional regulation of glutathione (GSH) and nicotinamide adenine dinucleotide phosphate hydrogen (NADPH) homeostasis through eIF2α phosphorylation and its impact on cell death during ER stress. eIF2α phosphorylation-deficient (A/A) cells exhibited decreased expression of multiple genes involved in GSH synthesis and NADPH production, leading to an exacerbated depletion of both cellular and mitochondrial GSH, as well as mitochondrial NADPH, during ER stress. Impaired GSH homeostasis resulted from deficient expression of ATF4 and/or its dependent factor, Nrf2, which are key transcription factors in the antioxidant response during ER stress. In contrast, the exacerbation of NADPH depletion may primarily be attributed to the dysregulated expression of mitochondrial serine-driven 1-carbon metabolism pathway genes, which are regulated by an unidentified eIF2α phosphorylation-dependent mechanism during ER stress. Moreover, the eIF2α phosphorylation-ATF4 axis was responsible for upregulation of ferroptosis-inhibiting genes and downregulation of ferroptosis-activating genes upon ER stress. Therefore, ER stress strongly induced ferroptosis of A/A cells, which was significantly inhibited by treatments with cell-permeable GSH and the ferroptosis inhibitor ferrostatin-1. ATF4 overexpression suppressed impairment of GSH homeostasis in A/A cells during ER stress by promoting expression of downstream target genes. Consequently, ATF4 overexpression mitigated ferroptosis as well as apoptosis of A/A cells during ER stress. Our findings underscore the importance of eIF2α phosphorylation in maintaining GSH/NADPH homeostasis and inhibiting ferroptosis through ATF4 and unidentified eIF2α phosphorylation-dependent target(s)-mediated transcriptional reprogramming during ER stress.

Tetracera asiatica flavonoids attenuate alcohol-induced liver injury by suppressing oxidative stress and inflammation mediated by the Keap-1/Nrf2/HO-1, NF-κB/MAPK and PERK/Nrf2 signaling pathways in alcoholic liver injury rats

Alcoholic liver disease is regarded as a leading reason for liver cirrhosis. This study aimed to investigate the protective effect of tetracera asiatica flavonoids (TAF) on alcoholic liver injury (ALI) and explore the associated mechanisms. An ALI rat model was established and then divided into four groups, including ALI group, low-dose TAF (l-TAF) group, medium-dose TAF (m-TAF) group, and high-dose TAF (h-TAF) group. Levels of ALT, AST, ALB, SOD, MDA, NO, CAT, TG, TNF-α, IL-1β, Nrf2, Keap1, HO-1, NQO-1, and GSH-Px were measured in ALI rats in different groups. Pathological changes and inflammatory infiltration were examined using HE staining. Western blot was used to detect expressions of Nrf2, MAPK p38, PERK, NF-κB, ERK1/2 and anti-JNK1/2/3. The results showed that TAF protected against alcoholic liver injury in ALI rats by decreasing ALT and AST levels and inhibiting inflammatory response. TAF significantly reversed alcohol-induced increase in NO (P < 0.05), and remarkably decreased levels of TNF-α (P < 0.001) and IL-1β (P < 0.01), compared with the ALI group. TAF significantly increased the transcription of Nrf2, Keap1, HO-1, NQO-1 and GSH-Px gene (all P < 0.05) and inhibited the alcohol-induced upregulation of MAPK p38 expression (P < 0.001), p-NF-κB/NF-κB ratio (P < 0.001), p-ERK/1/2/ERK1/2 ratio (P < 0.05), and p-JNK1/2/3/JNK1/2/2 ratio (P < 0.05), compared with the ALI group (all P < 0.001). TAF obviously reversed effects of ALI modeling, and remarkably downregulated the expression of PERK and upregulated Nrf2 (all P < 0.001) compared with the ALI rats. In conclusion, TAF attenuates alcohol-induced livery injury through suppressing Keap-1/Nrf2/HO-1, NF-κB/MAPK and PERK/Nrf2 signaling pathways mediated oxidative stress and inflammation in ALI rats.

Activation of the PERK Branch of the UPR as a Strategy for Improving Outcomes in Acute Ischemic Stroke

Brain ischemia disrupts endoplasmic reticulum (ER) dynamics, causes ER stress, and triggers the unfolded protein response (UPR). During the UPR, protein kinase RNA-like ER kinase (PERK) phosphorylates eIF2α, shutting down global protein synthesis, inhibits protein synthesis, and provides neuroprotection during acute ischemic stroke. Herein, middle cerebral artery occlusion/reperfusion (MCAO/R) and PERK neuron-specific deletion conditional knockout mice were employed to observe the function and mechanisms of PERK. CCT020312, a novel selective PERK activator, specifically activates PERK and provides neuroprotection both in vivo and in vitro stroke models. Additionally, CCT020312 enhanced neuronal survival and cerebral microvessels and decreased the level of astrogliosis in acute ischemic stroke mice. Furthermore, in vivo experiments demonstrated that CCT020312 not only prevented apoptosis but also enhanced the PERK/p-eIF2α/LC3-II autophagy signaling pathway in MCAO/R mice. In conclusion, our study supports the potential therapeutic value of targeting PERK in acute ischemic stroke, offering a promising strategy for enhancing stroke outcomes through the modulation of protein synthesis and the autophagy pathway.

Schwann Cell Protein Kinase RNA-like ER Kinase (PERK) Is Not Necessary for the Development of Diabetic Peripheral Neuropathy but Negates the Efficacy of Cemdomespib Therapy

Diabetic peripheral neuropathy (DPN) is a common complication of diabetes arising in part from glycemic damage to neurons and Schwann cells (SC). While the pathogenic mechanisms of DPN are complex, mitochondrial dysfunction and endoplasmic reticulum (ER) stress contribute to the development of DPN and serve as therapeutic targets for disease modification. Cemdomespib is an orally bioavailable small molecule which alleviates clinical indices of DPN that correlate with improvements in neuronal oxidative stress and mitochondrial bioenergetics. However, the contribution of SC ER stress in the onset of DPN and the therapeutic efficacy of cemdomespib remains unknown. To address this issue, mice expressing a conditional deletion of protein kinase RNA-like ER kinase (PERK) in myelinating SCs (SC-cPERK KO) and control SC-PERKf/f mice were rendered diabetic with streptozotocin. Diabetic SC-PERKf/f and SC-cPERK KO mice developed a similar magnitude of DPN as quantified by the onset of a thermal/mechanical hypoalgesia, decreases in nerve conduction velocity (NCV) and intraepidermal fiber density (iENFD). After 8 weeks of diabetes, daily treatment with 1 mg/kg cemdomespib for an additional 8 weeks significantly improved thermal/mechanical hypoalgesia, NCV, iENFD and decreased markers of ER stress in diabetic SC-PERKf/f mice, but the drug had no effect in diabetic SC-cPERK KO mice. Nrf2 is a PERK substrate and studies using rat SCs subjected to ER stress demonstrated that cemdomespib increased Nrf2 activity. Collectively, these data suggest that activation of SC PERK by diabetes is not necessary for the onset of DPN, but serves as a target in the action of cemdomespib, potentially by increasing Nrf2 activity.

The molecular determinants regulating redox signaling in diabetic endothelial cells

Oxidation and reduction are vital for keeping life through several prime mechanisms, including respiration, metabolism, and other energy supplies. Mitochondria are considered the cell's powerhouse and use nutrients to produce redox potential and generate ATP and H2O through the process of oxidative phosphorylation by operating electron transfer and proton pumping. Simultaneously, mitochondria also produce oxygen free radicals, called superoxide (O2 -), non-enzymatically, which interacts with other moieties and generate reactive oxygen species (ROS), such as hydrogen peroxide (H2O2), peroxynitrite (ONOO-), and hydroxyl radical (OH-). These reactive oxygen species modify nucleic acids, proteins, and carbohydrates and ultimately cause damage to organs. The nutrient-sensing kinases, such as AMPK and mTOR, function as a key regulator of cellular ROS levels, as loss of AMPK or aberrant activation of mTOR signaling causes ROS production and compromises the cell's oxidant status, resulting in various cellular injuries. The increased ROS not only directly damages DNA, proteins, and lipids but also alters cellular signaling pathways, such as the activation of MAPK or PI3K, the accumulation of HIF-1α in the nucleus, and NFkB-mediated transcription of pro-inflammatory cytokines. These factors cause mesenchymal activation in renal endothelial cells. Here, we discuss the biology of redox signaling that underlies the pathophysiology of diabetic renal endothelial cells.

Polysaccharides with antioxidant activity: Extraction, beneficial roles, biological mechanisms, structure-function relationships, and future perspectives: A review

Polysaccharides are valuable macromolecules due to their multiple bioactivities, safety, and a wide range of sources. Recently, a series of polysaccharides with antioxidant activity have been intensively reported. In this review, the latest advances in polysaccharides with antioxidant activity have been reviewed, primarily based on the investigations of polysaccharides regarding advanced extraction methods, roles in oxidative stress-related diseases, intracellular signaling pathways associated with antioxidant responses, activating pathways in the gut, structure-function relationships, and methods to improve antioxidant activity. The summarized information highlighted that much work needs to be conducted, from laboratory to industry, to understand and fully utilize the antioxidant potential of polysaccharides. Finally, future perspectives, including scaling-up of advanced extraction methods, standardizing the protocols for assessing and screening polysaccharides, bridging gaps on the biological mechanisms underlying antioxidant activity, performing clinical trials, and elucidating structure-antioxidant relationships, have been addressed. The information present in this review will be helpful to the scientific community when studying on polysaccharides with antioxidant potential and provides research directions for a better understanding of the polysaccharides and promotes their successful applications in functional foods and nutraceuticals.

IRE1 is a promising therapeutic target in pancreatic cancer

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Less is better: various means to reduce protein load in the endoplasmic reticulum

The endoplasmic reticulum (ER) is an important organelle that controls the intracellular and extracellular environments. The ER is responsible for folding almost one-third of the total protein population in the eukaryotic cell. Disruption of ER-protein folding is associated with numerous human diseases, including metabolic disorders, neurodegenerative diseases, and cancer. During ER perturbations, the cells deploy various mechanisms to increase the ER-folding capacity and reduce ER-protein load by minimizing the number of substrates entering the ER to regain homeostasis. These mechanisms include signaling pathways, degradation mechanisms, and other processes that mediate the reflux of ER content to the cytosol. In this review, we will discuss the recent discoveries of five different ER quality control mechanisms, including the unfolded protein response (UPR), ER-associated-degradation (ERAD), pre-emptive quality control, ER-phagy and ER to cytosol signaling (ERCYS). We will discuss the roles of these processes in decreasing ER-protein load and inter-mechanism crosstalk.

Homeostasis control in health and disease by the unfolded protein response

Cells rely on the endoplasmic reticulum (ER) to fold and assemble newly synthesized transmembrane and secretory proteins - essential for cellular structure-function and for both intracellular and intercellular communication. To ensure the operative fidelity of the ER, eukaryotic cells leverage the unfolded protein response (UPR) - a stress-sensing and signalling network that maintains homeostasis by rebalancing the biosynthetic capacity of the ER according to need. The metazoan UPR can also redirect signalling from cytoprotective adaptation to programmed cell death if homeostasis restoration fails. As such, the UPR benefits multicellular organisms by preserving optimally functioning cells while removing damaged ones. Nevertheless, dysregulation of the UPR can be harmful. In this Review, we discuss the UPR and its regulatory processes as a paradigm in health and disease. We highlight important recent advances in molecular and mechanistic understanding of the UPR that enable greater precision in designing and developing innovative strategies to harness its potential for therapeutic gain. We underscore the rheostatic character of the UPR, its contextual nature and critical open questions for its further elucidation.

PERK-Olating Through Cancer: A Brew of Cellular Decisions

The type I protein kinase PERK is an endoplasmic reticulum (ER) transmembrane protein that plays a multifaceted role in cancer development and progression, influencing tumor growth, metastasis, and cellular stress responses. The activation of PERK represents one of the three signaling pathways induced during the unfolded protein response (UPR), which is triggered, in particular, in tumor cells that constitutively experience various intracellular and extracellular stresses that impair protein folding within the ER. PERK activation can lead to both pro-survival and proapoptotic outcomes, depending on the cellular context and the extent of ER stress. It helps the reprogramming of the gene expression in cancer cells, thereby ensuring survival in the face of oncogenic stress, such as replicative stress and DNA damage, and also microenvironmental challenges, including hypoxia, angiogenesis, and metastasis. Consequently, PERK contributes to tumor initiation, transformation, adaptation to the microenvironment, and chemoresistance. However, sustained PERK activation in cells can also impair cell proliferation and promote apoptotic death by various interconnected processes, including mitochondrial dysfunction, translational inhibition, the accumulation of various cellular stresses, and the specific induction of multifunctional proapoptotic factors, such as CHOP. The dual role of PERK in promoting both tumor progression and suppression makes it a complex target for therapeutic interventions. A comprehensive understanding of the intricacies of PERK pathway activation and their impact is essential for the development of effective therapeutic strategies, particularly in diseases like cancer, where the ER stress response is deregulated in most, if not all, of the solid and liquid tumors. This article provides an overview of the knowledge acquired from the study of animal models of cancer and tumor cell lines cultured in vitro on PERK's intracellular functions and their impact on cancer cells and their microenvironment, thus highlighting potential new therapeutic avenues that could target this protein.

eIF2α phosphorylation-ATF4 axis-mediated transcriptional reprogramming mitigates mitochondrial impairment during ER stress

Eukaryotic translation initiation factor 2α (eIF2α) phosphorylation, which regulates all 3 unfolded protein response pathways, helps maintain cellular homeostasis and overcome endoplasmic reticulum (ER) stress through transcriptional and translational reprogramming. However, transcriptional regulation of mitochondrial homeostasis by eIF2α phosphorylation during ER stress is not fully understood. Here, we report that the eIF2α phosphorylation-activating transcription factor 4 (ATF4) axis is required for the expression of multiple transcription factors, including nuclear factor erythroid 2-related factor 2 and its target genes responsible for mitochondrial homeostasis during ER stress. eIF2α phosphorylation-deficient (A/A) cells displayed dysregulated mitochondrial dynamics and mitochondrial DNA replication, decreased expression of oxidative phosphorylation complex proteins, and impaired mitochondrial functions during ER stress. ATF4 overexpression suppressed impairment of mitochondrial homeostasis in A/A cells during ER stress by promoting the expression of downstream transcription factors and their target genes. Our findings underscore the importance of the eIF2α phosphorylation-ATF4 axis for maintaining mitochondrial homeostasis through transcriptional reprogramming during ER stress.

Reinforcing Nrf2 Signaling: Help in the Alzheimer's Disease Context

Oxidative stress plays a role in various pathophysiological diseases, including neurogenerative diseases, such as Alzheimer's disease (AD), which is the most prevalent neuro-pathology in the aging population. Oxidative stress has been reported to be one of the earliest pathological alterations in AD. Additionally, it was demonstrated that in older adults, there is a loss of free radical scavenging ability. The Nrf2 transcription factor is a key regulator in antioxidant defense systems, but, with aging, both the amount and the transcriptional activity of Nrf2 decrease. With the available treatments for AD being poorly effective, reinforcing the antioxidant defense systems via the Nrf2 pathway may be a way to prevent and treat AD. To highlight the predominant role of Nrf2 signaling in defending against oxidative stress and, therefore, against neurotoxicity, we present an overview of the natural compounds that exert their own neuroprotective roles through the activation of the Nrf2 pathway. This review is an opportunity to promote a holistic approach in the treatment of AD and to highlight the need to further refine the development of new potential Nrf2-targeting drugs.

Targeting the Interplay Between Autophagy and the Nrf2 Pathway in Parkinson's Disease with Potential Therapeutic Implications

Parkinson's disease (PD) is a prevalent neurodegenerative disorder marked by the progressive degeneration of midbrain dopaminergic neurons and resultant locomotor dysfunction. Despite over two centuries of recognition as a chronic disease, the exact pathogenesis of PD remains elusive. The onset and progression of PD involve multiple complex pathological processes, with dysfunctional autophagy and elevated oxidative stress serving as critical contributors. Notably, emerging research has underscored the interplay between autophagy and oxidative stress in PD pathogenesis. Given the limited efficacy of therapies targeting either autophagy dysfunction or oxidative stress, it is crucial to elucidate the intricate mechanisms governing their interplay in PD to develop more effective therapeutics. This review overviews the role of autophagy and nuclear factor erythroid 2-related factor 2 (Nrf2), a pivotal transcriptional regulator orchestrating cellular defense mechanisms against oxidative stress, and the complex interplay between these processes. By elucidating the intricate interplay between these key pathological processes in PD, this review will deepen our comprehensive understanding of the multifaceted pathological processes underlying PD and may uncover potential strategies for its prevention and treatment.

Proteostasis Decline and Redox Imbalance in Age-Related Diseases: The Therapeutic Potential of NRF2

Nuclear factor erythroid 2-related factor 2 (NRF2) is a master regulator of cellular homeostasis, overseeing the expression of a wide array of genes involved in cytoprotective processes such as antioxidant and proteostasis control, mitochondrial function, inflammation, and the metabolism of lipids and glucose. The accumulation of misfolded proteins triggers the release, stabilization, and nuclear translocation of NRF2, which in turn enhances the expression of critical components of both the proteasomal and lysosomal degradation pathways. This process facilitates the clearance of toxic protein aggregates, thereby actively maintaining cellular proteostasis. As we age, the efficiency of the NRF2 pathway declines due to several factors including increased activity of its repressors, impaired NRF2-mediated antioxidant and cytoprotective gene expression, and potential epigenetic changes, though the precise mechanisms remain unclear. This leads to diminished antioxidant defenses, increased oxidative damage, and exacerbated metabolic dysregulation and inflammation-key contributors to age-related diseases. Given NRF2's role in mitigating proteotoxic stress, the pharmacological modulation of NRF2 has emerged as a promising therapeutic strategy, even in aged preclinical models. By inducing NRF2, it is possible to mitigate the damaging effects of oxidative stress, metabolic dysfunction, and inflammation, thus reducing protein misfolding. The review highlights NRF2's therapeutic implications for neurodegenerative diseases and cardiovascular conditions, emphasizing its role in improving proteostasis and redox homeostasis Additionally, it summarizes current research into NRF2 as a therapeutic target, offering hope for innovative treatments to counteract the effects of aging and associated diseases.

The Role of Protein Disulfide Isomerase Inhibitors in Cancer Therapy

Protein disulfide isomerase (PDI) is a member of the mercaptan isomerase family, primarily located in the endoplasmic reticulum (ER). At least 21 PDI family members have been identified. PDI plays a key role in protein folding, correcting misfolded proteins, and catalyzing disulfide bond formation, rearrangement, and breaking. It also acts as a molecular chaperone. Dysregulation of PDI activity is thus linked to diseases such as cancer, infections, immune disorders, thrombosis, neurodegenerative diseases, and metabolic disorders. In particular, elevated intracellular PDI levels can enhance cancer cell proliferation, metastasis, and invasion, making it a potential cancer marker. Cancer cells require extensive protein synthesis, with disulfide bond formation by PDI being a critical producer. Thus, cancer cells have higher PDI levels than normal cells. Targeting PDI can induce ER stress and activate the Unfolded Protein Response (UPR) pathway, leading to cancer cell apoptosis. This review discusses the structure and function of PDI, PDI inhibitors in cancer therapy, and the limitations of current inhibitors, proposing especially future directions for developing new PDI inhibitors.

Oleanolic acid inhibits aldo-keto reductase family 1 member B10-induced cancer stemness and avoids cisplatin-based chemotherapy resistance via the Snail signaling pathway in oral squamous cell carcinoma cell lines

Background/purpose

Oral squamous cell carcinoma (OSCC) is a common malignancy often associated with poor prognosis due to chemoresistance. In this study, we investigated whether arecoline, a major alkaloid in betel nuts, can stimulate aldo-keto reductase family 1 member B10 (AKR1B10) levels in OSCC, promoting cancer stemness and leading to resistance to cisplatin (CDDP)-based chemotherapy.

Materials and methods

Gain- and Loss- of AKR1B10 functions were analyzed using WB and q-PCR of OSCC cells. Stemness, epithelial mesenchymal transition (EMT) markers, and CDDP drug resistance in overexpressed AKR1B10 were also identified.

Results

Upregulated AKR1B10 in OSCC significantly increased cell motility and aggregation. The results also showed that the canonical TGF-β1-Smad3 pathway was involved in arecoline-induced AKR1B10 expression, further increasing cancer stemness with CDDP resistance via the Snail-dependent EMT pathway. Moreover, oleanolic acid (OA) and ROS/RNS (reactive oxygen/nitrogen species) inhibitors effectively reversed AKR1B10-induced CDDP-resistance.

Conclusion

Arecoline-induced ROS/RNS to hyper-activate AKR1B10 in tumor sphere cells via the TGF-β1-Smad3 pathway. Furthermore, AKR1B10 enhanced CDDP resistance in OSCC cells via EMT-inducing markers. Finally, Finally, OA may efficiently target CDDP resistance, reverse stemness in OSCC cells, and have the potential as a novel anticancer drug.

Propolis extract nanoparticles alleviate diabetes-induced reproductive dysfunction in male rats: antidiabetic, antioxidant, and steroidogenesis modulatory role

Diabetes can affect male fertility via oxidative stress and endocrine system disruption. Nanomedicine based on natural products is employed to address diabetes complications. The current study aims to investigate the potential beneficial effect of propolis extract nanoparticles against diabetes-induced testicular damage in male rats. Sixty male rats were randomly allocated to six groups (n = 10). The first group served as a control group. The second and third received propolis extract (Pr) and propolis extract nanoparticles (PrNPs). The fourth group is the diabetic group that received streptozotocin (STZ) (55 mg kg/bwt) single-dose i/p. The fifth and sixth groups are diabetic rats treated with Pr and PrNPs. Both Pr and PrNPs were received at a dose (100 mg/kg bwt) orally. After 60 days, animals were euthanized, then pancreatic and testicular tissues were collected for redox status evaluation, gene expression analysis, and histopathological examination. Also, hormonal analysis (Insulin, total testosterone, and luteinizing hormone (LH) ) along with semen quality evaluation were done. Results showed that the induction of diabetes led to testicular and pancreatic redox status deterioration showing a reduction in reduced glutathione (GSH) as well as elevation of malondialdehyde (MDA), and nitric oxide (NO) levels. Also, relative transcript levels of testicular cytochrome P450 family 11 subfamily A member 1 (CYP11A1), 3β-Hydroxysteroid dehydrogenase (HSD-3β), and nuclear factor (erythroid-derived 2)-like 2 (NFE2L2) were significantly down-regulated, While the advanced glycation end-product receptor (AGER) relative gene expression was significantly upregulated. Furthermore, hormonal and semen analysis disturbances were observed. Upon treatment with Pr and PrNPs,  a marked upregulation of testicular gene expression of CYP11A1, HSD-3β, and NFE2L2 as well as a downregulation of AGER, was observed. Hormones and semen analysis were improved. In addition, the testicular and pancreatic redox status was enhanced. Results were confirmed via histopathological investigations. PrNPs outperformed Pr in terms of steroidogenesis pathway improvement, testicular antioxidant defense mechanism augmentation, and prospective antidiabetic activity.

PGRN protects against serum deprivation-induced cell death by promoting the ROS scavenger system in cervical cancer

Progranulin (PGRN), an autocrine growth factor with tumorigenic roles in a variety of tumors, is a putative survival factor for normal and cancer cells in vitro. However, the fundamental mechanism of PGRN-mediated survival of cancer cells suffering from various types of microenvironmental stresses, such as serum deprivation, remains unknown. We show here that serum deprivation decreases intracellular PGRN protein levels in cervical cancer cells. PGRN protects cervical cancer cells against serum deprivation-induced apoptosis, limits reactive oxygen species (ROS) levels, maintains mitochondria integrity, and reduces oxidative damage of protein, lipid and DNA. PGRN enhances the ROS scavenger system, as evidenced by increased superoxide dismutase (SOD), catalase protein expression and activity, elevated GSH and NADPH levels and increased phase II detoxification enzyme expression in cervical cancer cells after serum withdrawal. The role of PGRN in ROS clearance is mediated by the PGRN-stimulated nuclear factor erythroid-derived 2-like 2 (NFE2L2)-antioxidant response element (ARE) pathway. Our study reveals an antioxidant role of PGRN in supporting the survival of cervical cancer cells under oxidative stress. This insight provides a new perspective on the how cervical cancer cells adapt to microenvironmental stress, contributing to cell viability and other malignant characteristics.

Itaconate transporter SLC13A3 impairs tumor immunity via endowing ferroptosis resistance

Immune checkpoint blockade (ICB) triggers tumor ferroptosis. However, most patients are unresponsive to ICB. Tumors might evade ferroptosis in the tumor microenvironment (TME). Here, we discover SLC13A3 is an itaconate transporter in tumor cells and endows tumor ferroptosis resistance, diminishing tumor immunity and ICB efficacy. Mechanistically, tumor cells uptake itaconate via SLC13A3 from tumor-associated macrophages (TAMs), thereby activating the NRF2-SLC7A11 pathway and escaping from immune-mediated ferroptosis. Structural modeling and molecular docking analysis identify a functional inhibitor for SLC13A3 (SLC13A3i). Deletion of ACOD1 (an essential enzyme for itaconate synthesis) in macrophages, genetic ablation of SLC13A3 in tumors, or treatment with SLC13A3i sensitize tumors to ferroptosis, curb tumor progression, and bolster ICB effectiveness. Thus, we identify the interplay between tumors and TAMs via the SLC13A3-itaconate-NRF2-SLC7A11 axis as a previously unknown immune ferroptosis resistant mechanism in the TME and SLC13A3 as a promising immunometabolic target for treating SLC13A3+ cancer.

Filbertone-Induced Nrf2 Activation Ameliorates Neuronal Damage via Increasing BDNF Expression

Neurotrophic factors are endogenous proteins that promote the survival of various neuronal cells. Increasing evidence has suggested a key role for brain-derived neurotrophic factor (BDNF) in the dopaminergic neurotoxicity associated with Parkinson's Disease (PD). This study explores the therapeutic potential of filbertone, a bioactive compound found in hazelnuts, in neurodegeneration, focusing on its effects on neurotrophic factors and the nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway. In our study, filbertone markedly elevated the expression of neurotrophic factors, including BDNF, Glial cell line-Derived Neurotrophic Factor (GDNF), and Nerve Growth Factor (NGF), in human neuroblastoma SH-SY5Y cells, mouse astrocyte C8-D1A cells, and mouse hypothalamus mHypoE-N1 cells. Moreover, filbertone effectively countered neuroinflammation and reversed the decline in neurotrophic factors and Nrf2 activation induced by a high-fat diet (HFD) in neurodegeneration models. The neuroprotective effects of filbertone were further validated in models of neurotoxicity induced by palmitic acid (PA) and the neurotoxin MPTP/MPP+, where it was observed to counteract PA and MPTP/MPP+-induced decreases in cell viability and neuroinflammation, primarily through the activation of Nrf2 and the subsequent upregulation of BDNF and heme oxygenase-1 expression. Nrf2 deficiency negated the neuroprotective effects of filbertone in MPTP-treated mice. Consequently, our finding suggests that filbertone is a novel therapeutic agent for neurodegenerative diseases, enhancing neuronal resilience through the Nrf2 signaling pathway and upregulation of neurotrophic factors.

Effects of dietary methionine on the growth and protein synthesis of juvenile Chinese mitten crabs (Eriocheir sinensis) fed fish meal-free diets

This study investigated the effects of dietary methionine (Met) on growth performance and protein synthesis in juvenile Chinese mitten crabs (Eriocheir sinensis) fed fish meal (FM)-free diets. Three diets free of FM containing 0.48% (LM), 1.05% (MM), and 1.72% (HM) Met were assessed, and the cysteine content in all the diets was adjusted to 0.46%. The control diet contained 35% FM without Met supplementation. Extra lysine was added to all of the FM-free diets to match the lysine level in the control diet. Juvenile E. sinensis (800 crabs weighing 0.74 ± 0.01 g each) were fed these four diets for eight weeks, with five replicates for each treatment. Both the LM and HM groups presented lower weight gain than all the other groups did (P = 0.002). The survival of the crabs was lower in the LM and HM groups than in the MM group (P = 0.005). Compared with those in the other groups, the growth performance of the crabs in the MM group improved, and lipid deposition and protein accumulation increased. These positive outcomes are associated with high protein expression linked to the mammalian target of the rapamycin (mTOR) pathway and low expression of genes and proteins linked to the PRKR-like endoplasmic reticulum kinase (PERK) pathway. The study of Met supplementation has explored the response of the PERK pathway through reducing glutathione (GSH) levels to promote protein synthesis. The injection of Met and L-buthionine-sulfoximine (BSO), an inhibitor of GSH synthesis, suppressed GSH production and altered the expression of genes and proteins related to protein synthesis pathways. This study suggests that Met supplementation in FM-free diets can increase the growth and protein synthesis of E. sinensis by modulating specific cellular pathways, particularly the mTOR and PERK pathways.

The Integrated Stress Response in Pancreatic Development, Tissue Homeostasis, and Cancer

Present in all eukaryotic cells, the integrated stress response (ISR) is a highly coordinated signaling network that controls cellular behavior, metabolism, and survival in response to diverse stresses. The ISR is initiated when any 1 of 4 stress-sensing kinases (protein kinase R-like endoplasmic reticulum kinase [PERK], general control non-derepressible 2 [GCN2], double-stranded RNA-dependent protein kinase [PKR], heme-regulated eukaryotic translation initiation factor 2α kinase [HRI]) becomes activated to phosphorylate the protein translation initiation factor eukaryotic translation initiation factor 2α (eIF2α), shifting gene expression toward a comprehensive rewiring of cellular machinery to promote adaptation. Although the ISR has been shown to play an important role in the homeostasis of multiple tissues, evidence suggests that it is particularly crucial for the development and ongoing health of the pancreas. Among the most synthetically dynamic tissues in the body, the exocrine and endocrine pancreas relies heavily on the ISR to rapidly adjust cell function to meet the metabolic demands of the organism. The hardwiring of the ISR into normal pancreatic functions and adaptation to stress may explain why it is a commonly used pro-oncogenic and therapy-resistance mechanism in pancreatic ductal adenocarcinoma and pancreatic neuroendocrine tumors. Here, we review what is known about the key roles that the ISR plays in the development, homeostasis, and neoplasia of the pancreas.

SMAR1 and p53-regulated lncRNA RP11-431M3.1 enhances HIF1A translation via miR-138 in colorectal cancer cells under oxidative stress

Eukaryotic cells respond to stress by altering coding and non-coding gene expression programs. Alongside many approaches and regulatory mechanisms, long non-coding RNAs (lncRNA) are finding a significant place in gene regulation, suggesting an involvement in various cellular processes and pathophysiology. LncRNAs are regulated by many transcription factors, including SMAR1 and p53, which are tumor suppressor genes. SMAR1 inhibits cancer cell metastasis and invasion and is also known to inhibit apoptosis during low-dose stress in coordination with p53. Data mining analysis suggested that these tumor suppressor genes might coregulate the lncRNA RP11-431M3.1 in colon cancer cells. Importantly, RP11-431M3.1 expression was found to be negatively correlated with patient survival rates in a number of cancers. Oxidative stress occurs when an imbalance in the body is caused by reactive oxygen species (ROS). This imbalance is known to be important in the development/pathogenesis of colon cancer. We are researching the role and control of this lncRNA in HCT116 cells under conditions of oxidative stress. We observed a dose-dependent differential expression of lncRNA upon H2O2 treatment and found that p53 and SMAR1 bind differentially to the promoter in response to the dose of stress inducer used. RP11-431M3.1 was observed to sponge miR-138 which has an important target gene, hypoxia-inducible factor (HIF1A). miR-138 was observed to bind differentially to RP11-431M3.1 and HIF1A RNA depending on the dose of oxidative stress. Furthermore, the knockdown of RP11-431M3.1 decreased the migration and proliferation of colon cancer cells. Our results suggest a previously undescribed regulatory mechanism through which RP11-431M3.1 is transcriptionally regulated by SMAR1 and p53, target HIF1A through miR-138, and highlight its potential as a therapeutic and diagnostic marker for cancer.

Unlocking peak performance: The role of Nrf2 in enhancing exercise outcomes and training adaptation in humans

Since the discovery of the nuclear factor erythroid-derived 2-like 2 (Nrf2) transcription factor thirty years ago, it has been shown that it regulates more than 250 genes involved in a multitude of biological processes, including redox balance, mitochondrial biogenesis, metabolism, detoxification, cytoprotection, inflammation, immunity, autophagy, cell differentiation, and xenobiotic metabolism. In skeletal muscle, Nrf2 signalling is primarily activated in response to perturbation of redox balance by reactive oxygen species or electrophiles. Initial investigations into human skeletal muscle Nrf2 responses to exercise, dating back roughly a decade, have consistently indicated that exercise-induced ROS production stimulates Nrf2 signalling. Notably, recent studies employing Nrf2 knockout mice have revealed impaired skeletal muscle contractile function characterised by reduced force output and increased fatigue susceptibility compared to wild-type counterparts. These deficiencies partially stem from diminished basal mitochondrial respiratory capacity and an impaired capacity to upregulate specific mitochondrial proteins in response to training, findings corroborated by inducible muscle-specific Nrf2 knockout models. In humans, baseline Nrf2 expression in skeletal muscle correlates with maximal oxygen uptake and high-intensity exercise performance. This manuscript delves into the mechanisms underpinning Nrf2 signalling in response to acute exercise in human skeletal muscle, highlighting the involvement of ROS, antioxidants and Keap1/Nrf2 signalling in exercise performance. Furthermore, it explores Nrf2's role in mediating adaptations to chronic exercise and its impact on overall exercise performance. Additionally, the influence of diet and certain supplements on basal Nrf2 expression and its role in modulating acute and chronic exercise responses are briefly addressed.

TMED4 facilitates regulatory T cell suppressive function via ROS homeostasis in tumor and autoimmune mouse models

Endoplasmic reticulum stress (ERS) plays crucial roles in maintaining Treg stability and function, yet the underlying mechanism remains largely unexplored. Here, we demonstrate that (Tmed4ΔTreg) mice with Treg-specific KO of ERS-related protein transmembrane p24 trafficking protein 4 (TMED4) had more Tregs with impaired Foxp3 stability, Treg signatures, and suppressive activity, which led to T cell hyperactivation and an exacerbated inflammatory phenotype and boosted antitumor immunity in mice. Mechanistically, loss of Tmed4 caused defects in ERS and a nuclear factor erythroid 2-related factor 2-related (NRF2-related) antioxidant response, which resulted in excessive ROS that reduced the Foxp3 stability and suppressive function of Tregs in an IRE1α/XBP1 axis-dependent manner. The abnormalities could be effectively rescued by the ROS scavenger, NRF2 inducer, or by forcible expression of IRE1α. Moreover, TMED4 suppressed IRE1α proteosome degradation via the ER-associated degradation (ERAD) system including the ER chaperone binding immunoglobulin protein (BIP). Our study reveals that TMED4 maintained the stability of Tregs and their suppressive function through IRE1α-dependent ROS and the NRF2-related antioxidant response.

Exploring Endocannabinoid System: Unveiling New Roles in Modulating ER Stress

The endoplasmic reticulum (ER) is the organelle mainly involved in maintaining cellular homeostasis and driving correct protein folding. ER-dependent defects or dysfunctions are associated with the genesis/progression of several pathological conditions, including cancer, inflammation, and neurodegenerative disorders, that are directly or indirectly correlated to a wide set of events collectively named under the term "ER stress". Despite the recent increase in interest concerning ER activity, further research studies are needed to highlight all the mechanisms responsible for ER failure. In this field, recent discoveries paved the way for the comprehension of the strong interaction between ER stress development and the endocannabinoid system. The activity of the endocannabinoid system is mediated by the activation of cannabinoid receptors (CB), G protein-coupled receptors that induce a decrease in cAMP levels, with downstream anti-inflammatory effects. CB activation drives, in most cases, the recovery of ER homeostasis through the regulation of ER stress hallmarks PERK, ATF6, and IRE1. In this review, we focus on the CB role in modulating ER stress, with particular attention to the cellular processes leading to UPR activation and oxidative stress response extinguishment, and to the mechanisms underlying natural cannabinoids' modulation of this complex cellular machine.

Isoliquiritigenin as a modulator of the Nrf2 signaling pathway: potential therapeutic implications

Nuclear factor erythroid-2-related factor 2 (Nrf2), a transcription factor responsible for cytoprotection, plays a crucial role in regulating the expression of numerous antioxidant genes, thereby reducing reactive oxygen species (ROS) levels and safeguarding cells against oxidative stress. Extensive research has demonstrated the involvement of Nrf2 in various diseases, prompting the exploration of Nrf2 activation as a potential therapeutic approach for a variety of diseases. Consequently, there has been a surge of interest in investigating the Nrf2 signaling pathway and developing compounds that can modulate its activity. Isoliquiritigenin (ISL) (PubChem CID:638278) exhibits a diverse range of pharmacological activities, including antioxidant, anticancer, and anti-tumor properties. Notably, its robust antioxidant activity has garnered significant attention. Furthermore, ISL has been found to possess therapeutic effects on various diseases, such as diabetes, cardiovascular diseases, kidney diseases, and cancer, through the activation of the Nrf2 pathway. This review aims to evaluate the potential of ISL in modulating the Nrf2 signaling pathway and summarize the role of ISL in diverse diseases prevention and treatment through modulating the Nrf2 signaling pathway.

Mechanistic Insights and Potential Therapeutic Implications of NRF2 in Diabetic Encephalopathy

Diabetic encephalopathy (DE) is a complication of diabetes, especially type 2 diabetes (T2D), characterized by damage in the central nervous system and cognitive impairment, which has gained global attention. Despite the extensive research aimed at enhancing our understanding of DE, the underlying mechanism of occurrence and development of DE has not been established. Mounting evidence has demonstrated a close correlation between DE and various factors, such as Alzheimer's disease-like pathological changes, insulin resistance, inflammation, and oxidative stress. Of interest, nuclear factor erythroid 2-related factor 2 (NRF2) is a transcription factor with antioxidant properties that is crucial in maintaining redox homeostasis and regulating inflammatory responses. The activation and regulatory mechanisms of NRF2 are a relatively complex process. NRF2 is involved in the regulation of multiple metabolic pathways and confers neuroprotective functions. Multiple studies have provided evidence demonstrating the significant involvement of NRF2 as a critical transcription factor in the progression of DE. Additionally, various molecules capable of activating NRF2 expression have shown potential in ameliorating DE. Therefore, it is intriguing to consider NRF2 as a potential target for the treatment of DE. In this review, we aim to shed light on the role and the possible underlying mechanism of NRF2 in DE. Furthermore, we provide an overview of the current research landscape and address the challenges associated with using NRF2 activators as potential treatment options for DE.

The Role of Endoplasmic Reticulum Stress on Reducing Recombinant Protein Production in Mammalian Cells

Therapeutic recombinant protein production relies on industrial scale culture of mammalian cells to produce active proteins in quantities sufficient for clinical use. The combination of stresses from industrial cell culture environment and recombinant protein production can overwhelm the protein synthesis machinery in the endoplasmic reticulum (ER). This leads to a buildup of improperly folded proteins which induces ER stress. Cells respond to ER stress by activating the Unfolded Protein Response (UPR). To restore proteostasis, ER sensor proteins reduce global protein synthesis and increase chaperone protein synthesis, and if that is insufficient the proteins are degraded. If proteostasis is still not restored, apoptosis is initiated. Increasing evidence suggests crosstalk between ER proteostasis and DNA damage repair (DDR) pathways. External factors (e.g., metabolites) from the cellular environment as well as internal factors (e.g., transgene copy number) can impact genome stability. Failure to maintain genome integrity reduces cell viability and in turn protein production. This review focuses on the association between ER stress and processes that affect protein production and secretion. The processes mediated by ER stress, including inhibition of global protein translation, chaperone protein production, degradation of misfolded proteins, DNA repair, and protein secretion, impact recombinant protein production. Recombinant protein production can be reduced by ER stress through increased autophagy and protein degradation, reduced protein secretion, and reduced DDR response.

Arsenic induced cardiotoxicity: An approach for molecular markers, epigenetic predictors and targets

Arsenic, a ubiquitous environmental toxicant, has been acknowledged as a significant issue for public health due to its widespread pollution of drinking water and food supplies. The present review aimed to study the toxicity associated with the cardiac system. Prolonged exposure to arsenic has been associated with several harmful health outcomes, especially cardiotoxicity. Arsenic-induced cardiotoxicity encompasses a range of cardiovascular abnormalities, including cardiac arrhythmias, ischemic heart disease, and cardiomyopathy. To tackle this toxicity, understanding the molecular markers, epigenetic predictors, and targets involved in arsenic-induced cardiotoxicity is essential for creating preventative and therapeutic approaches. For preventive measures against this heavy metal poisoning of groundwater, it is crucial to regularly monitor water quality, re-evaluate scientific findings, and educate the public about the possible risks. This review thoroughly summarised what is currently known in this field, highlighting the key molecular markers, epigenetic modifications, and potential therapeutic targets associated with arsenic-induced cardiotoxicity.

NRF2 signaling pathway and telomere length in aging and age-related diseases

The transcription factor nuclear factor erythroid 2-related factor 2 (NRF2) is well recognized as a critical regulator of redox, metabolic, and protein homeostasis, as well as the regulation of inflammation. An age-associated decline in NRF2 activity may allow oxidative stress to remain unmitigated and affect key features associated with the aging phenotype, including telomere shortening. Telomeres, the protective caps of eukaryotic chromosomes, are highly susceptible to oxidative DNA damage, which can accelerate telomere shortening and, consequently, lead to premature senescence and genomic instability. In this review, we explore how the dysregulation of NRF2, coupled with an increase in oxidative stress, might be a major determinant of telomere shortening and age-related diseases. We discuss the relevance of the connection between NRF2 deficiency in aging and telomere attrition, emphasizing the importance of studying this functional link to enhance our understanding of aging pathologies. Finally, we present a number of compounds that possess the ability to restore NRF2 function, maintain a proper redox balance, and preserve telomere length during aging.

The role of Keap1-Nrf2 signaling pathway in the treatment of respiratory diseases and the research progress on targeted drugs

Lungs are exposed to external oxidants from the environment as in harmful particles and smog, causing oxidative stress in the lungs and consequently respiratory ailment. The NF-E2-related factor 2 (Nrf2) is the one with transcriptional regulatory function, while its related protein Kelch-like ECH-associated protein 1 (Keap1) inhibits Nrf2 activity. Together, they form the Keap1-Nrf2 pathway, which regulates the body's defense against oxidative stress. This pathway has been shown to maintain cellular homeostasis during oxidative stressing, inflammation, oncogenesis, and apoptosis by coordinating the expression of cytoprotective genes and making it a potential therapeutic target for respiratory diseases. This paper summarizes this point in detail in Chapter 2. In addition, this article summarizes the current drug development and clinical research progress related to the Keap1-Nrf2 signaling pathway, with a focus on the potential of Nrf2 agonists in treating respiratory diseases. Overall, the article reviews the regulatory mechanisms of the Keap1-Nrf2 signaling pathway in respiratory diseases and the progress of targeted drug research, aiming to provide new insights for treatment.

Exploring the neuroprotective potential of Nrf2-pathway activators against annonacin toxicity

Modulation of the Nrf2 pathway, a master regulator of the antioxidant response and cellular metabolism, has been suggested as a promising therapeutic strategy in tauopathies, a heterogeneous group of neurodegenerative disorders characterized by intracellular proteinaceous inclusions of abnormally phosphorylated tau. Here, we explored the neuroprotective potential of different Nrf2-pathway activators in human immortalized dopaminergic neurons against annonacin-induced toxicity, a mitochondrial inhibitor associated with a PSP-like syndrome and capable of mimicking tauopathy-like features. Interestingly, we observed heterogenous and compound-dependent neuroprotective effects among the different Nrf2-pathway activators. With the exception of Fyn inhibitors, all the selected Nrf2-pathway activators improved cell viability and the oxidative status, and reduced the annonacin-induced tau hyperphosphorylation and neurite degeneration, particularly the p62-activators. However, improvement of the impaired mitochondrial function was only observed by the Bach-1 inhibitor. Surprisingly, we found evidence that ezetimibe, an approved drug for hypercholesterolemia, prevents the transcriptional upregulation of 4R-tau triggered by annonacin insult. Overall, our results suggest that the neuroprotective effects of the Nrf2-pathway activators against annonacin toxicity may rely on the specific mechanism of action, intrinsic to each compound, and possibly on the concomitant modulation of additional signaling pathways. Further research will be needed to fully understand how synergistic modulation of metabolic adaptation and cell survival can be exploit to develop new therapeutical strategies for tauopathies and eventually other neurodegenerative diseases.

Luteolin, apigenin, and chrysin inhibit lipotoxicity-induced NLRP3 inflammasome activation and autophagy damage in macrophages by suppressing endoplasmic reticulum stress

Lipotoxicity leads to numerous metabolic disorders such as nonalcoholic steatohepatitis. Luteolin, apigenin, and chrysin are three flavones with known antioxidant and anti-inflammatory properties, but whether they inhibit lipotoxicity-mediated NLRP3 inflammasome activation was unclear. To address this question, we used J774A.1 macrophages and Kupffer cells stimulated with 100 μM palmitate (PA) in the presence or absence of 20 μM of each flavone. PA increased p-PERK, p-IRE1α, p-JNK1/2, CHOP, and TXNIP as well as p62 and LC3-II expression and induced autophagic flux damage. Caspase-1 activation and IL-1β release were also noted after 24 h of exposure to PA. In the presence of the PERK inhibitor GSK2656157, PA-induced CHOP and TXNIP expression and caspase-1 activation were mitigated. Compared with PA treatment alone, Bcl-2 coupled to beclin-1 was elevated and autophagy was reversed by the JNK inhibitor SP600125. With luteolin, apigenin, and chrysin treatment, PA-induced ROS production, ER stress, TXNIP expression, autophagic flux damage, and apoptosis were ameliorated. Moreover, TXNIP binding to NLRP3 and IL-1β release in response to LPS/PA challenge were reduced. These results suggest that luteolin, apigenin, and chrysin protect hepatic macrophages against PA-induced NLRP3 inflammasome activation and autophagy damage by attenuating endoplasmic reticulum stress.

Revisiting the role of hypoxia-inducible factors and nuclear factor erythroid 2-related factor 2 in regulating macrophage inflammation and metabolism

The recent birth of the immunometabolism field has comprehensively demonstrated how the rewiring of intracellular metabolism is critical for supporting the effector functions of many immune cell types, such as myeloid cells. Among all, the transcriptional regulation mediated by Hypoxia-Inducible Factors (HIFs) and Nuclear factor erythroid 2-related factor 2 (NRF2) have been consistently shown to play critical roles in regulating the glycolytic metabolism, redox homeostasis and inflammatory responses of macrophages (Mφs). Although both of these transcription factors were first discovered back in the 1990s, new advances in understanding their function and regulations have been continuously made in the context of immunometabolism. Therefore, this review attempts to summarize the traditionally and newly identified functions of these transcription factors, including their roles in orchestrating the key events that take place during glycolytic reprogramming in activated myeloid cells, as well as their roles in mediating Mφ inflammatory responses in various bacterial infection models.

Targeting the AMPK/Nrf2 Pathway: A Novel Therapeutic Approach for Acute Lung Injury

ALI(acute lung injury) is a severe respiratory dysfunction caused by various intrapulmonary and extrapulmonary factors. It is primarily characterized by oxidative stress and affects the integrity of the pulmonary barrier. In severe cases, ALI can progress to ARDS(acute respiratory distress syndrome), a condition that poses a serious threat to the lives of affected patients. To date, the etiological mechanisms underlying ALI remain elusive, and available therapeutic options are quite limited. AMPK(AMP-activated protein kinase), an essential serine/threonine protein kinase, performs a pivotal function in the regulation of cellular energy levels and cellular regulatory mechanisms, including the detection of redox signals and mitigating oxidative stress. Meanwhile, Nrf2(nuclear factor erythroid 2-related factor 2), a critical transcription factor, alleviates inflammation and oxidative responses by interacting with multiple signaling pathways and contributing to the modulation of oxidative enzymes associated with inflammation and programmed cell death. Indeed, AMPK induces the dissociation of Nrf2 from Keap1(kelch-like ECH-associated protein-1) and facilitates its translocation into the nucleus to trigger the transcription of downstream antioxidant genes, ultimately suppressing the expression of inflammatory cells in the lungs. Given their roles, AMPK and Nrf2 hold promise as novel treatment targets for ALI. This study aimed to summarise the current status of research on the AMPK/Nrf2 signaling pathway in ALI, encompassing recently reported natural compounds and drugs that can activate the AMPK/Nrf2 signaling pathway to alleviate lung injury, and provide a theoretical reference for early intervention in lung injury and future research on lung protection.

Navigating the landscape of the unfolded protein response in CD8+ T cells

Endoplasmic reticulum stress occurs due to large amounts of misfolded proteins, hypoxia, nutrient deprivation, and more. The unfolded protein is a complex intracellular signaling network designed to operate under this stress. Composed of three individual arms, inositol-requiring enzyme 1, protein kinase RNA-like ER kinase, and activating transcription factor-6, the unfolded protein response looks to resolve stress and return to proteostasis. The CD8+ T cell is a critical cell type for the adaptive immune system. The unfolded protein response has been shown to have a wide-ranging spectrum of effects on CD8+ T cells. CD8+ T cells undergo cellular stress during activation and due to environmental insults. However, the magnitude of the effects this response has on CD8+ T cells is still understudied. Thus, studying these pathways is important to unraveling the inner machinations of these powerful cells. In this review, we will highlight the recent literature in this field, summarize the three pathways of the unfolded protein response, and discuss their roles in CD8+ T cell biology and functionality.

Long non-coding RNA-mediated modulation of endoplasmic reticulum stress under pathological conditions

Endoplasmic reticulum (ER) stress, which ensues from an overwhelming protein folding capacity, activates the unfolded protein response (UPR) in an effort to restore cellular homeostasis. As ER stress is associated with numerous diseases, it is highly important to delineate the molecular mechanisms governing the ER stress to gain insight into the disease pathology. Long non-coding RNAs, transcripts with a length of over 200 nucleotides that do not code for proteins, interact with proteins and nucleic acids, fine-tuning the UPR to restore ER homeostasis via various modes of actions. Dysregulation of specific lncRNAs is implicated in the progression of ER stress-related diseases, presenting these molecules as promising therapeutic targets. The comprehensive analysis underscores the importance of understanding the nuanced interplay between lncRNAs and ER stress for insights into disease mechanisms. Overall, this review consolidates current knowledge, identifies research gaps and offers a roadmap for future investigations into the multifaceted roles of lncRNAs in ER stress and associated diseases to shed light on their pivotal roles in the pathogenesis of related diseases.

Mitochondrial mechanisms in Cerebral Ischemia-Reperfusion Injury: Unravelling the intricacies

Cerebral ischemic stroke is a major contributor to physical impairments and premature death worldwide. The available reperfusion therapies for stroke in the form of mechanical thrombectomy and intravenous thrombolysis increase the risk of cerebral ischemia-reperfusion (I-R) injury due to sudden restoration of blood supply to the ischemic region. The injury is manifested by hemorrhagic transformation, worsening of neurological impairments, cerebral edema, and progression to infarction in surviving patients. A complex network of multiple pathological processes has been known to be involved in the pathogenesis of I-R injury. Primarily, 3 major contributors namely oxidative stress, neuroinflammation, and mitochondrial failure have been well studied in I-R injury. A transcription factor, Nrf2 (Nuclear factor erythroid 2-related factor 2) plays a crucial defensive role in resisting the deleterious effects of I-R injury and potentiating the cellular protective mechanisms. In this review, we delve into the critical function of mitochondria and Nrf2 in the context of cerebral I-R injury. We summarized how oxidative stress, neuroinflammation, and mitochondrial anomaly contribute to the pathophysiology of I-R injury and further elaborated the role of Nrf2 as a pivotal guardian of cellular integrity. The review further highlighted Nrf2 as a putative therapeutic target for mitochondrial dysfunction in cerebral I-R injury management.

Ferroptosis: An important mechanism of disease mediated by the gut-liver-brain axis

AIMS

As a unique iron-dependent non-apoptotic cell death, Ferroptosis is involved in the pathogenesis and development of many human diseases and has become a research hotspot in recent years. However, the regulatory role of ferroptosis in the gut-liver-brain axis has not been elucidated. This paper summarizes the regulatory role of ferroptosis and provides theoretical basis for related research.

MATERIALS AND METHODS

We searched PubMed, CNKI and Wed of Science databases on ferroptosis mediated gut-liver-brain axis diseases, summarized the regulatory role of ferroptosis on organ axis, and explained the adverse effects of related regulatory effects on various diseases.

KEY FINDINGS

According to our summary, the main way in which ferroptosis mediates the gut-liver-brain axis is oxidative stress, and the key cross-talk of ferroptosis affecting signaling pathway network is Nrf2/HO-1. However, there were no specific marker between different organ axes mediate by ferroptosis.

SIGNIFICANCE

Our study illustrates the main ways and key cross-talk of ferroptosis mediating the gut-liver-brain axis, providing a basis for future research.

Endoplasmic reticulum stress and quality control in relation to cisplatin resistance in tumor cells

The endoplasmic reticulum (ER) is a crucial organelle that orchestrates key cellular functions like protein folding and lipid biosynthesis. However, it is highly sensitive to disturbances that lead to ER stress. In response, the unfolded protein response (UPR) activates to restore ER homeostasis, primarily through three sensors: IRE1, ATF6, and PERK. ERAD and autophagy are crucial in mitigating ER stress, yet their dysregulation can lead to the accumulation of misfolded proteins. Cisplatin, a commonly used chemotherapy drug, induces ER stress in tumor cells, activating complex signaling pathways. Resistance to cisplatin stems from reduced drug accumulation, activation of DNA repair, and anti-apoptotic mechanisms. Notably, cisplatin-induced ER stress can dualistically affect tumor cells, promoting either survival or apoptosis, depending on the context. ERAD is crucial for degrading misfolded proteins, whereas autophagy can protect cells from apoptosis or enhance ER stress-induced apoptosis. The complex interaction between ER stress, cisplatin resistance, ERAD, and autophagy opens new avenues for cancer treatment. Understanding these processes could lead to innovative strategies that overcome chemoresistance, potentially improving outcomes of cisplatin-based cancer treatments. This comprehensive review provides a multifaceted perspective on the complex mechanisms of ER stress, cisplatin resistance, and their implications in cancer therapy.

Anticancer Therapies Based on Oxidative Damage: Lycium barbarum Inhibits the Proliferation of MCF-7 Cells by Activating Pyroptosis through Endoplasmic Reticulum Stress

Lycium barbarum, commonly recognized as goji berry or wolfberry, is highly appreciated not only for its organoleptic and nutritional properties but also as an important source of bioactive compounds such as polysaccharides, carotenoids, phenolics, and various other non-nutritive compounds. These constituents give it a multitude of health benefits, including antioxidant, anti-inflammatory, and anticancer properties. However, the precise biochemical mechanisms responsible for its anticancer effects remain unclear, and the comprehensive composition of goji berry extracts is often insufficiently explored. This study aimed to investigate the biochemical pathways modulated in breast cancer cells by an ethanolic extract of Lycium barbarum fruit (LBE). Following metabolomic profiling using UHPLC-HRMS/MS, we assessed the antitumoral properties of LBE on different breast cancer cell lines. This investigation revealed that LBE exhibited cytotoxic effects, inducing a pro-oxidant effect that triggered pyroptosis activation through endoplasmic reticulum (ER) stress and subsequent activation of the P-IRE1α/XBP1/NLRP3 axis in MCF-7 cells. In addition, LBE did not display cytotoxicity toward healthy human cells but demonstrated antioxidant properties by neutralizing ROS generated by doxorubicin. These findings underscore the potential of LBE as a highly promising natural extract in cancer therapy.

Redox regulation of UPR signalling and mitochondrial ER contact sites

Mitochondria and the endoplasmic reticulum (ER) have a synergistic relationship and are key regulatory hubs in maintaining cell homeostasis. Communication between these organelles is mediated by mitochondria ER contact sites (MERCS), allowing the exchange of material and information, modulating calcium homeostasis, redox signalling, lipid transfer and the regulation of mitochondrial dynamics. MERCS are dynamic structures that allow cells to respond to changes in the intracellular environment under normal homeostatic conditions, while their assembly/disassembly are affected by pathophysiological conditions such as ageing and disease. Disruption of protein folding in the ER lumen can activate the Unfolded Protein Response (UPR), promoting the remodelling of ER membranes and MERCS formation. The UPR stress receptor kinases PERK and IRE1, are located at or close to MERCS. UPR signalling can be adaptive or maladaptive, depending on whether the disruption in protein folding or ER stress is transient or sustained. Adaptive UPR signalling via MERCS can increase mitochondrial calcium import, metabolism and dynamics, while maladaptive UPR signalling can result in excessive calcium import and activation of apoptotic pathways. Targeting UPR signalling and the assembly of MERCS is an attractive therapeutic approach for a range of age-related conditions such as neurodegeneration and sarcopenia. This review highlights the emerging evidence related to the role of redox mediated UPR activation in orchestrating inter-organelle communication between the ER and mitochondria, and ultimately the determination of cell function and fate.