Keap1 is a redox-regulated substrate adaptor protein for a Cul3-dependent ubiquitin ligase complex

Cullin 3-mediated ubiquitination restricts enterovirus D68 replication and is counteracted by viral protease 3C

Enterovirus D68 (EV-D68) has emerged as a significant threat to public health because of its association with respiratory illnesses and neurological complications, including acute flaccid myelitis. However, the molecular mechanisms underlying EV-D68 replication and pathogenesis remain unclear. Here, we revealed a novel interaction between EV-D68 and the host Cullin-RING E3 ligase system, specifically Cullin 3, which was reported to restrict viral replication. We initially demonstrated that proteasome inhibition enhanced EV-D68 replication, suggesting an important role for the ubiquitin-proteasome system in viral restriction. Cullin 3 was further identified as a key factor that inhibits EV-D68 replication, and the downregulation of its expression increased viral titers. Mechanistically, Cullin 3 was observed to target the viral capsid protein VP1 for ubiquitination and degradation. However, EV-D68 was determined to utilize its protease 3C to cleave Cullin 3 at the Q681 residue, thereby inhibiting E3 ligase activity and facilitating resistance to Cullin 3-mediated VP1 degradation. This study uncovered a host-virus arms race, wherein the ubiquitin-proteasome system of the host actively targets viral proteins for degradation, and viral proteases counteract this defense mechanism. Accordingly, these findings could lead to more effective antiviral treatments.

IMPORTANCE

The ubiquitin-proteasome system (UPS) is a critical cellular pathway involved in the regulation of protein stability and has been implicated in the regulation of viral infections. However, its role in EV-D68 infection has not been extensively explored. Our study proves that the host UPS, through the scaffold protein Cullin 3, can restrict EV-D68 replication, representing a previously unrecognized antiviral mechanism. Furthermore, we describe a viral strategy used to evade this host defense mechanism comprising Cullin 3 cleavage, which has broad implications for understanding virus-host interactions and could inform the development of novel therapeutic strategies against EV-D68 and other enteroviruses.

Phenethyl Isothiocyanate (PEITC) interaction with Keap1 activates the Nrf2 pathway and inhibits lipid accumulation in adipocytes

Phenethyl isothiocyanate (PEITC) has been recognized for its potential effects in various human diseases. However, the impact of PEITC on adipocyte differentiation and its underlying molecular mechanisms is not well understood. This study investigates the effects of PEITC on adipocyte differentiation and elucidates the molecular mechanisms involved in Nrf2 activation. The effects of PEITC on adipocyte differentiation were assessed in C3H10T1/2 and 3T3-L1 cells. Nrf2-induced effects by PEITC were examined in Nrf2 knockout (KO) MEF and Keap1 KO H1299 cells. The interaction between PEITC and Keap1 was evaluated using thermal shift assays and Co-immunoprecipitation experiments. Reconstitution of cysteine mutants of Keap1 in Keap1 KO cells was used to elucidate a critical amino acid for the PEITC-induced Nrf2 stabilization. The initial stages of adipogenesis were crucial for PEITC's anti-adipogenic effects in C3H10T1/2 and 3T3-L1 cells. PEITC increased Nrf2 protein expression, but this induction was absent in Keap1 KO cells. Thermal shift assays with the purified BTB domain of Keap1 confirmed a direct interaction with PEITC. Re-expression of Keap1 in Keap1 KO cells showed that the cysteine residue at position 151 is essential for PEITC-induced Nrf2 expression and the disruption of the Nrf2-Keap1 complex. PEITC was found to activate Nrf2-mediated gene expression and inhibit adipocyte differentiation, at least partially, through Nrf2-dependent mechanisms. This study confirms the anti-adipogenic effects of PEITC. Mechanistic investigations demonstrate that PEITC interacts with Keap1 and that the cysteine residue (C151) of Keap1 is critical for PEITC's effects on Nrf2 activation.

Carotenoids in Skin Photoaging: Unveiling Protective Effects, Molecular Insights, and Safety and Bioavailability Frontiers

Skin photoaging, driven primarily by ultraviolet radiation, remains a critical dermatological concern. Carotenoids, a class of natural pigments with potent antioxidant properties, have emerged as promising agents for preventing and mitigating photoaging. This review comprehensively integrates current understanding regarding the triggers of skin photoaging, oxidative stress and their associated signal pathways, the photoprotective roles and mechanisms of carotenoids, as well as their bioavailability. Common C40 carotenoids, such as β-carotene, lycopene, astaxanthin, lutein, and zeaxanthin demonstrate remarkable antioxidant activity, primarily attributed to their conjugated double bond structures. Many studies have demonstrated that both oral and topical administration of these C40 carotenoids can effectively alleviate skin photoaging. Specifically, they play a crucial role in promoting the formation of a new skin barrier and enhancing the production of collagen and elastin, key structural proteins essential for maintaining skin integrity and elasticity. Mechanistically, these carotenoids combat photoaging by effectively scavenging reactive oxygen species and modulating oxidative stress responsive signal pathways, including MAPK, Nrf2, and NF-κB. Notably, we also anticipate the anti-photoaging potential of novel carotenoids, with a particular emphasis on bacterioruberin, a C50 carotenoid derived from halophilic archaea. Bacterioruberin exhibits a superior radical scavenging capacity, outperforming the conventional C40 carotenoids. Furthermore, when considering the application of carotenoids, aspects such as safe dosage, bioavailability, and possible long term usage issues, including allergies and pigmentation disorders, must be taken into account. This review underscores the anti-photoaging mechanism of carotenoids, providing strategies and theoretical basis for the prevention and treatment of photoaging.

Alpha-lipoic acid alleviated intermittent hypoxia-induced myocardial injury in mice by promoting autophagy through Nrf2 signaling pathway

Obstructive sleep apnea syndrome (OSAS) is a prevalent sleep-related breathing disorder characterized by intermittent hypoxia (IH). Myocardial injury is a common complication associated with OSAS. Alpha-lipoic acid (LA), a potent antioxidant, has been utilized in various disease contexts and has demonstrated significant protective effects in myocardial infarction models. Given the limited treatment options available for OSAS-related myocardial injury, this study aimed to demonstrate the potential therapeutic effects of LA and to investigate the underlying mechanisms. IH is a widely employed method to simulate the pathophysiological conditions associated with OSAS. In vivo experiments were conducted using mice placed in a specialized hypoxic chamber to replicate IH conditions. Echocardiography indicated that exposure to IH severely impaired cardiac function. Treatment with LA activated the Nrf2 pathway and autophagy, which contributed to the improvement of cardiac function in mice with OSAS. Additionally, in vitro studies demonstrated that IH induced apoptosis and decreased cell viability in H9C2 cardiomyocytes. LA enhanced Nrf2 nuclear translocation and its downstream signaling pathways, thereby promoting autophagy, inhibiting apoptosis, and alleviating injury in H9C2 cardiomyocytes. Furthermore, in vitro inhibition of Nrf2 using ML385 reduced autophagy levels and attenuated the protective effects of LA against apoptosis in H9C2 cardiomyocytes. These findings suggest that LA may provide a promising therapeutic strategy for myocardial injury associated with OSAS. By elucidating these findings, new insights into the protective mechanisms of LA against IH-induced myocardial injury are provided, highlighting its potential as a therapeutic agent for diseases associated with OSAS.

SQST-1/p62-regulated SKN-1/Nrf mediates a phagocytic stress response via transcriptional activation of lyst-1/LYST

Cells may be intrinsically fated to die to sculpt tissues during development or to maintain homeostasis. Cells can also die in response to various stressors, injury or pathological conditions. Additionally, cells of the metazoan body are often highly specialized with distinct domains that differ both structurally and with respect to their neighbors. Specialized cells can also die, as in normal brain development or pathological states and their different regions may be eliminated via different programs. Clearance of different types of cell debris must be performed quickly and efficiently to prevent autoimmunity and secondary necrosis of neighboring cells. Moreover, all cells, including those programmed to die, may be subject to various stressors. Some largely unexplored questions include whether predestined cell elimination during development could be altered by stress, if adaptive stress responses exist and if polarized cells may need compartment-specific stress-adaptive programs. We leveraged Compartmentalized Cell Elimination (CCE) in the nematode C. elegans to explore these questions. CCE is a developmental cell death program whereby three segments of two embryonic polarized cell types are eliminated differently. We have previously employed this in vivo genetic system to uncover a cell compartment-specific, cell non-autonomous clearance function of the fusogen EFF-1 in phagosome closure during corpse internalization. Here, we introduce an adaptive response that serves to aid developmental phagocytosis as a part of CCE during stress. We employ a combination of forward and reverse genetics, CRISPR/Cas9 gene editing, stress response assays and advanced fluorescence microscopy. Specifically, we report that, under heat stress, the selective autophagy receptor SQST-1/p62 promotes the nuclear translocation of the oxidative stress-related transcription factor SKN-1/Nrf via negative regulation of WDR-23. This in turn allows SKN-1/Nrf to transcribe lyst-1/LYST (lysosomal trafficking associated gene) which subsequently promotes the phagocytic resolution of the developmentally-killed internalized cell even under stress conditions.

Distinct Stress Regulators in the CRL Family: Emerging Roles of F-Box Proteins: Cullin-RING Ligases and Stress-Sensing

Cullin-RING ligases (CRLs) are central regulators of environmental and cellular stress responses, orchestrating diverse processes through the ubiquitination of substrate proteins. As modular complexes, CRLs employ substrate-specific adaptors to target proteins for degradation and other ubiquitin-mediated processes, enabling dynamic adaptation to environmental cues. Recent advances have highlighted the largest CRL subfamily SCF (Skp1-cullin-F-box) in environmental sensing, a role historically underappreciated for SCF ubiquitin ligases. Notably, emerging evidence suggests that the F-box domain, a 50-amino acid motif traditionally recognized for mediating protein-protein interactions, can act as a direct environmental sensor due to its ability to bind heavy metals. Despite these advances, the roles of many CRL components in environmental sensing remain poorly understood. This review provides an overview of CRLs in stress response regulation and emphasizes the emerging functions of F-box proteins in environmental adaptation.

Discovery of β-amino acid substituted naphthalene sulfonamide derivatives as potent Kelch-like ECH-associated protein 1-nuclear factor erythroid 2-related factor 2 (Keap1-Nrf2) protein-protein interaction inhibitors for ulcerative colitis management

The transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) is a key regulator of cellular defense system against oxidative insults. Directly inhibiting the Kelch-like ECH-associated protein 1 (Keap1)-Nrf2 protein-protein interaction (PPI) has emerged as a promising approach to activate Nrf2 for the treatment of diseases associated with oxidative stress. Herein, we identified β-amino acids as privileged structural fragments for designing novel naphthalene sulfonamide-based Keap1-Nrf2 PPI inhibitors. Comprehensive structure-activity relationship (SAR) exploration identified compound 19 as the optimal inhibitor with an IC50 of 0.55 μM for disrupting the Keap1-Nrf2 interaction and a Kd of 0.50 μM for binding to Keap1. Further studies demonstrated that 19 effectively activated the Nrf2-regulated cytoprotective system and provided protective effects against dextran sulfate sodium (DSS)-induced ulcerative colitis (UC) in both in vitro and in vivo models. These findings highlight the potential of β-amino acid substituted naphthalene sulfonamide Keap1-Nrf2 inhibitor 19 as a prospective therapeutic agent for UC via Keap1 targeting.

Rice bran extract ameliorate heavy metal mixture induced hippocampal toxicity via inhibiting oxido-inflammatory damages and modulating Hmox-1/BDNF/Occludin/Aβ40/Aβ42 in rats

The hippocampus executes the integration of memory and spatial learning information. This study evaluated the effect of rice bran extract (RBE) on heavy metal mixture (MM) induced hippocampal toxicity and its underlying mechanism in albino rats. Thirty five rats were exposed to MM alone at Pb 20 mg/kg, Al 35 mg/kg, and Mn 0.564 mg/kg body weight or co-exposed with RBE at 125, 250 and 500 mg/kg body weight, 125 RBE mg/kg b.wt only, and 500 RBE mg/kg b.wt only 5 days a wk for 13 wk (90 days). Subsequently, oxidative stress, inflammation (cyclooxygenase-2) and caspase-3, amyloid precursor proteins (Aβ40 and Aβ42), HMOX-1, occludin and BDNF and transcription factor Nrf-2 in the hippocampus were investigated. MM treatment resulted in significantly higher escape latency time than both the control and MM plus RBE group. MM exposure induced increased oxidative stress, inflammation resulting in enhanced hippocampal apoptosis. MM significantly increased bioaccumulation of Pb, Al, and Pb; increased caspase-3, Nrf-2, Aβ40 and Aβ42 and significantly decreased occludin, BDNF, HMOX-1 when compared with the control. All these effects were reversed by RBE. Collectively, RBE ameliorated MM - induced oxidative stress, neuro-inflammation and hippocampal apoptosis via attenuation of oxidative damages of cellular constituents, neuronal inflammation and subsequent down regulation of amyloid precursor proteins Aβ40, Aβ42 and up regulation of occludin, BDNF, HMOX-1 protein expression via Nrf-2 dependent pathways to abrogate hippocampal toxicity associated with spatial learning and memory deficits.

High PRMT5 levels, maintained by KEAP1 inhibition, drive chemoresistance in high-grade serous ovarian cancer

Protein arginine methyl transferases (PRMTs) are generally upregulated in cancers. However, the mechanisms leading to this upregulation and its biological consequences are poorly understood. Here, we identify PRMT5, the main symmetric arginine methyltransferase, as a critical driver of chemoresistance in high-grade serous ovarian cancer (HGSOC). PRMT5 levels and its enzymatic activity are induced in a platinum-resistant (Pt-resistant) state at the protein level. To reveal potential regulators of high PRMT5 protein levels, we optimized intracellular immunostaining conditions and performed unbiased CRISPR screening. We identified Kelch-like ECH-associated protein 1 (KEAP1) as a top-scoring negative regulator of PRMT5. Our mechanistic studies show that KEAP1 directly interacted with PRMT5, leading to its ubiquitin-dependent degradation under normal physiological conditions. At the genomic level, ChIP studies showed that elevated PRMT5 directly interacted with the promoters of stress response genes and positively regulated their transcription. Combined PRMT5 inhibition with Pt resulted in synergistic cellular cytotoxicity in vitro and reduced tumor growth in vivo in Pt-resistant patient-derived xenograft tumors. Overall, the findings from this study identify PRMT5 as a critical therapeutic target in Pt-resistant HGSOC cells and reveal the molecular mechanisms that lead to high PRMT5 levels in Pt-treated and chemo-resistant tumors.

USP37 as a novel regulator of NRF2 protein stability and chemoresistance in HCC

Chemoresistance is a prevalent issue in cancer, resulting in a poor prognosis. The transcription factor nuclear factor (erythroid-derived 2)-like 2 (NRF2), a key regulator in cellular antioxidant responses, is implicated in cell survival, proliferation, and chemoresistance. It represents a promising target for treating Hepatocellular carcinoma (HCC). The NRF2 activity has been recently revealed to be controlled by the ubiquitination process mediated by the KEAP1-CUL3 E3 ligase, highlighting the importance of deubiquitination regulation. However, the specific deubiquitinase (DUB) responsible for NRF2 in liver cancer remains unclear. In this study, we demonstrate that Ubiquitin-Specific Protease 37 (USP37) acts as a novel regulator of NRF2 protein. Mechanistically, USP37 modulates the stability of NRF2 through enzymatic activity-dependent deubiquitination. Additionally, USP37 interacts with NRF2 and facilitates its deubiquitination. Elevated USP37 levels were associated with higher levels of NRF2 protein in samples from human patients. Importantly, the knockdown of USP37 results in increased NRF2 degradation and enhances cellular sensitivity to chemotherapy. Overall, our findings manifested the significant involvement of the USP37-NRF2 axis in regulating therapeutic interventions for HCC.

Thirty years of NRF2: advances and therapeutic challenges

Over the last 30 years, NRF2 has evolved from being recognized as a transcription factor primarily involved in redox balance and detoxification to a well-appreciated master regulator of cellular proteostasis, metabolism and iron homeostasis. NRF2 plays a pivotal role in diverse pathologies, including cancer, and metabolic, inflammatory and neurodegenerative disorders. It exhibits a Janus-faced duality, safeguarding cellular integrity in normal cells against environmental insults to prevent disease onset, whereas in certain cancers, constitutively elevated NRF2 levels provide a tumour survival advantage, promoting progression, therapy resistance and metastasis. Advances in understanding the mechanistic regulation of NRF2 and its roles in human pathology have propelled the investigation of NRF2-targeted therapeutic strategies. This Review dissects the mechanistic intricacies of NRF2 signalling, its cross-talk with biological processes and its far-reaching implications for health and disease, highlighting key discoveries that have shaped innovative therapeutic approaches targeting NRF2.

Down-regulation of Selenoprotein K impairs the proliferation and differentiation of chicken skeletal muscle satellite cells by inhibiting the Nrf2 antioxidant signaling pathway

Skeletal muscle satellite cells (SMSCs) are pivotal for skeletal muscle regeneration post-injury, and their development is intricately influenced by regulatory factors. Selenoprotein K (SELENOK), an endoplasmic reticulum resident selenoprotein, is known for its crucial role in maintaining skeletal muscle redox sensing. However, the specific molecular mechanism of SELENOK in SMSCs remains unclear. In this study, a SELENOK knockdown model was established to delve into its role in SMSCs. The results revealed that SELENOK knockdown hindered SMSCs proliferation and differentiation, as evidenced by the regulation of key proteins such as Pax7, Myf5, CyclinD1, MyoD, and Myf6, and the inhibitory effects were mitigated by N-Acetyl-l-cysteine (NAC). SELENOK knockdown induced oxidative stress, further analyses uncovered that SELENOK knockdown downregulated nuclear transcription factor nuclear erythroid factor 2-like 2 (Nrf2) protein expression while upregulating cytoplasmic kelch-like ECH-associated protein 1 (Keap1) protein expression. SELENOK knockdown impeded Nestin and sequestosome 1/p62 (p62) interaction with Keap1, leading to increased Nrf2 ubiquitination. This prevented Nrf2 transportation from cytoplasm to nucleus mediated by Keap1, ultimately resulting in the downregulation of catalase (CAT), heme oxygenase-1 (HO-1), and glutathione peroxidase 4 (GPX4) protein expression. Notably, SELENOK knockdown-induced inhibition of SMSCs proliferation and differentiation was alleviated by Oltipraz, an activator of the Nrf2 pathway. This study provided novel insights, demonstrating that SELENOK is a key player in SMSCs proliferation and differentiation by influencing the Nrf2 antioxidant signaling pathway.

Regulating Nrf2 activity: ubiquitin ligases and signaling molecules in redox homeostasis

Transcription factor NF-E2 p45-related factor 2 (Nrf2) orchestrates defenses against oxidants and thiol-reactive electrophiles. It is controlled at the protein stability level by several E3 ubiquitin ligases (CRL3Keap1, CRL4DCAF11, SCFβ-TrCP, and Hrd1). CRL3Keap1 is of the greatest importance because it constitutively targets Nrf2 for proteasomal degradation under homeostatic conditions but is prevented from doing so by oxidative stressors. Repression of Nrf2 by CRL3Keap1 is attenuated by SQSTM1/p62, and this is reinforced by phosphorylation of SQSTM1/p62. Repression by SCFβ-TrCP requires phosphorylation of Nrf2 by GSK3, the activity of which is inhibited by PKB/Akt and other kinases. We discuss how Nrf2 activity is controlled by the ubiquitin ligases under different circumstances. We also describe endogenous signaling molecules that inactivate CRL3Keap1 to alleviate stress and restore homeostasis.

Primary and Acquired Resistance to Immunotherapy with Checkpoint Inhibitors in NSCLC: From Bedside to Bench and Back

Immunotherapy with checkpoint inhibitors has become the cornerstone of systemic treatment for non-oncogene addicted non-small-cell lung cancer. Despite its pivotal role, a significant proportion of patients-approximately 70-85%-either exhibit primary resistance to PD-1 blockade or develop acquired resistance following an initial benefit, even in combination with chemotherapy and/or anti-CTLA-4 agents. The phenomenon of primary and acquired resistance to immunotherapy represents a critical clinical challenge, largely based on our incomplete understanding of the mechanisms of action of immunotherapy, and the resulting lack of accurate predictive biomarkers. Here, we review the definitions and explore the proposed mechanisms of primary and acquired resistance, including those related to the tumor microenvironment, systemic factors, and intrinsic tumor characteristics. We also discuss translational data on adaptive changes within tumor cells and the immune infiltrate following exposure to checkpoint inhibitors. Lastly, we offer a comprehensive overview of current and emerging therapeutic strategies designed to prevent primary resistance and counteract acquired resistance.

Oxidative stress and NRF2 signaling in kidney injury

Oxidative stress plays a crucial role in the pathogenesis of acute kidney injury (AKI), chronic kidney disease (CKD), and the AKI-to-CKD transition. This review examines the intricate relationship between oxidative stress and kidney pathophysiology, emphasizing the potential therapeutic role of nuclear factor erythroid 2-related factor 2 (NRF2), a master regulator of cellular redox homeostasis. In diverse AKI and CKD models, diminished NRF2 activity exacerbates oxidative stress, whereas genetic and pharmacological NRF2 activation alleviates kidney damage induced by nephrotoxic agents, ischemia-reperfusion injury, fibrotic stimuli, and diabetic nephropathy. The renoprotective effects of NRF2 extend beyond antioxidant defense, encompassing its anti-inflammatory and anti-fibrotic properties. The significance of NRF2 in renal fibrosis is further underscored by its interaction with the transforming growth factor-β signaling cascade. Clinical trials using bardoxolone methyl, a potent NRF2 activator, have yielded both encouraging and challenging outcomes, illustrating the intricacy of modulating NRF2 in human subjects. In summary, this overview suggests the therapeutic potential of targeting NRF2 in kidney disorders and highlights the necessity for continued research to refine treatment approaches.

USP13 facilitates a ferroptosis-to-autophagy switch by activation of the NFE2L2/NRF2-SQSTM1/p62-KEAP1 axis dependent on the KRAS signaling pathway

Macroautophagy/autophagyis a lysosomal-regulated degradation process that participates incellular stress and then promotes cell survival or triggers celldeath. Ferroptosis was initially described as anautophagy-independent, iron-regulated, nonapoptotic cell death.However, recent studies have revealed that autophagy is positivelyassociated with sensitivity to ferroptosis. Nonetheless, themolecular mechanisms by which these two types of regulated cell death(RCD) modulate each other remain largely unclear. Here, we screened85 deubiquitinating enzymes (DUBs) and found that overexpression ofUSP13 (ubiquitin specific peptidase 13) could significantlyupregulate NFE2L2/NRF2 (NFE2 like bZIP transcription factor 2)protein levels. In addition, in 39 cases of KRAS-mutated lungadenocarcinoma (LUAD), we found that approximately 76% of USP13overexpression is positively correlated with NFE2L2 overexpression.USP13 interacts with and catalyzes the deubiquitination of thetranscription factor NFE2L2. Additionally, USP13 depletion promotesan autophagy-to-ferroptosis switch invitro andin xenograft tumor mouse models, through the activation of theNFE2L2-SQSTM1/p62 (sequestosome 1)-KEAP1 axis in KRAS mutant cellsand tumor tissues. Hence, targeting USP13 effectively switchedautophagy-to-ferroptosis, thereby inhibiting KRAS (KRASproto-oncogene, GTPase) mutant LUAD, suggesting the therapeuticpromise of combining autophagy and ferroptosis in the KRAS-mutantLUAD.Abbreviation: ACSL4: acyl-CoA synthetase long-chain family member 4; ACTB: actin beta; AL: autolysosomes; AP: autophagosomes; BCL2L1/BCL-xL: BCL2 like 1; CCK8: Cell Counting Kit-8; CQ: chloroquine; CUL3: cullin 3; DMSO: dimethyl sulfoxide; DOX: doxorubicin; DUB: deubiquitinating enzyme; Ferr-1: ferrostatin-1; GPX4: glutathione peroxidase 4; GSEA: gene set enrichment analysis; 4HNE: 4-hydroxynonenal; IKE: imidazole ketone erastin; KEAP1: kelch like ECH associated protein 1; KRAS: KRAS proto-oncogene, GTPase; LCSC: lung squamous cell carcinoma; IF: immunofluorescence; LUAD: lung adenocarcinoma; Lys05: Lys01 trihydrochloride; MAPK1/ERK2/p42: mitogen-activated protein kinase 1; MAPK3/ERK1/p44; MTOR: mechanistic target of rapamycin kinase; NFE2L2/NRF2: NFE2 like bZIP transcription factor, 2; NQO1: NAD(P)H quinone dehydrogenase 1; PG: phagophore; RCD: regulated cell death; RAPA: rapamycin; ROS: reactive oxygen species; SLC7A11/xCT: solute carrier family 7 member 11; SQSTM1/p62: sequestosome 1; TEM: transmission electron microscopy; TUBB/beta-tubulin: tubulin, beta; UPS: ubiquitin-proteasome system; USP13: ubiquitin specific peptidase 13.

KEAP1-NRF2 Interaction in Cancer: Competitive Interactors and Their Role in Carcinogenesis

An American Cancer Society report estimates the emergence of around 2 million new cancer cases in the US in 2024 [...].

CARD11-BCL10-MALT1 Complex-Dependent MALT1 Activation Facilitates Myocardial Oxidative Stress in Doxorubicin-Treated Mice via Enhancing k48-Linked Ubiquitination of Nrf2

Aims: Downregulation of nuclear factor erythroid 2-related factor 2 (Nrf2) contributes to doxorubicin (DOX)-induced myocardial oxidative stress, and inhibition of mucosa-associated lymphoid tissue lymphoma translocation protein 1 (MALT1) increased Nrf2 protein level in rat heart suffering ischemia/reperfusion, indicating a connection between MALT1 and Nrf2. This study aims to explore the role of MALT1 in DOX-induced myocardial oxidative stress and the underlying mechanisms. Results: The mice received a single injection of DOX (15 mg/kg, i.p.) to induce myocardial oxidative stress, evidenced by increases in the levels of reactive oxidative species as well as decreases in the activities of antioxidative enzymes, concomitant with a downregulation of Nrf2; these phenomena were reversed by MALT1 inhibitor. Similar phenomena were observed in DOX-induced oxidative stress in cardiomyocytes. Mechanistically, knockdown or inhibition of MALT1 notably attenuated the interaction between Nrf2 and MALT1 and decreased the k48-linked ubiquitination of Nrf2. Furthermore, inhibition or knockdown of calcium/calmodulin-dependent protein kinase II (CaMKII-δ) reduced the phosphorylation of caspase recruitment domain-containing protein 11 (CARD11), subsequently disrupted the assembly of CARD11, B cell lymphoma 10 (BCL10), and MALT1 (CBM) complex, and reduced the MALT1-dependent k48-linked ubiquitination of Nrf2 in DOX-treated mice or cardiomyocytes. Innovation and Conclusion: The E3 ubiquitin ligase function of MALT1 accounts for the downregulation of Nrf2 and aggravation of myocardial oxidative stress in DOX-treated mice, and CaMKII-δ-dependent phosphorylation of CARD11 triggered the assembly of CBM complex and the subsequent activation of MALT1. Antioxid. Redox Signal. 42, 115-132.

LRRC45 accelerates bladder cancer development and ferroptosis inhibition via stabilizing NRF2 by competitively KEAP1 interaction

Centrosomal dysregulation is closely linked to the genesis and progression of tumors. A comprehensive analysis of single-cell RNA sequencing (scRNA-seq) data has revealed that leucine-rich repeat-containing protein 45 (LRRC45), a centrosome linker protein crucial for maintaining centrosome cohesion and a member of the leucine-rich repeat-containing proteins (LRRCs) family, is significantly upregulated in bladder cancer. Notably, the elevated expression levels of LRRC45 were strongly correlated with a poor prognosis in patients. Furthermore, the depletion of LRRC45 in bladder cancer cells markedly inhibited tumorigenic proliferation and increased intracellular iron and reactive oxygen species (ROS) levels. It ultimately triggered ferroptosis, an iron-dependent form of programmed cell death characterized by lipid peroxidation. Mechanistic studies revealed that LRRC45 exerts its oncogenic effects through competitive interaction with Kelch-like ECH-associated protein 1 (KEAP1), which inhibits the ubiquitin-proteasome-mediated degradation of nuclear factor erythroid 2-related factor 2 (NRF2). This interaction enhances the nuclear translocation of NRF2 and its subsequent anti-ferroptotic activity. In conclusion, our studies highlight the critical role of LRRC45 in enhancing the stability of NRF2, thereby promoting the tumorigenic potential of bladder cancer. These insights suggest that targeting LRRC45 could serve as a promising molecular target for developing novel therapeutic interventions for bladder cancer.

Role of mitophagy in intervertebral disc degeneration: A narrative review

OBJECTIVE

The pivotal role of mitophagy in the initiation and progression of intervertebral disc (IVD) degeneration (IDD) has become increasingly apparent due to a growing body of research on its pathogenesis. This review summarizes the role of mitophagy in IDD and the therapeutic potential of targeting this process.

DESIGN

This narrative review is divided into three parts: the regulatory mechanisms of mitophagy, the role of mitophagy in IDD, and the applications and prospects of mitophagy for the treatment of IDD.

RESULTS

Mitophagy protects cells against harmful external stimuli and plays a crucial protective role by promoting extracellular matrix (ECM) production, inhibiting ECM degradation, and reducing apoptosis, senescence, and cartilage endplate calcification. However, excessive mitophagy is often detrimental to cells. Currently, the regulatory mechanisms governing appropriate and excessive mitophagy remain unclear.

CONCLUSIONS

Proper mitophagy effectively maintains IVD cell homeostasis and slows the progression of IDD. Conversely, excessive mitophagy may accelerate IDD development. Further research is needed to elucidate the regulatory mechanisms underlying appropriate and excessive mitophagy, which could provide new theoretical support for the application of mitophagy targeting to the treatment of IDD.

Crosslinking-mediated Interactome Analysis Identified PHD2-HIF1α Interaction Hotspots and the Role of PHD2 in Regulating Protein Neddylation

Prolyl Hydroxylase Domain protein 2 (PHD2) targets Hypoxia Inducible Factor alpha subunits (HIFα) for oxygen-dependent proline hydroxylation that leads to subsequent ubiquitination and degradation of HIFα. In addition to HIF proteins, growing evidence suggested that PHD2 may exert its multifaceted function through hydroxylase-dependent or independent activities. Given the critical role of PHD2 in diverse biological processes, it is important to comprehensively identify potential PHD2 interacting proteins. In this study, we engineered HeLa cells that stably express HTBH-tagged PHD2 to facilitate the identification of PHD2 interactome. Using DSSO-based cross-linking mass spectrometry (XL-MS) technology and LC-MSn analysis, we mapped PHD2-HIF1α interaction hotspots and identified over 300 PHD2 interacting proteins. Furthermore, we validated the COP9 Signalosome (CSN) complex, a major deneddylase complex, as a novel PHD2 interactor. DMOG treatment promoted interaction between PHD2 and CSN complex and enhanced the deneddylase activity of the CSN complex, resulting in increased level of free Cullin and reduced target protein ubiquitination. This mechanism may serve as a negative feedback regulation of the HIF transcription pathway.

Chaperones vs. oxidative stress in the pathobiology of ischemic stroke

As many proteins prioritize functionality over constancy of structure, a proteome is the shortest stave in the Liebig's barrel of cell sustainability. In this regard, both prokaryotes and eukaryotes possess abundant machinery supporting the quality of the proteome in healthy and stressful conditions. This machinery, namely chaperones, assists in folding, refolding, and the utilization of client proteins. The functions of chaperones are especially important for brain cells, which are highly sophisticated in terms of structural and functional organization. Molecular chaperones are known to exert beneficial effects in many brain diseases including one of the most threatening and widespread brain pathologies, ischemic stroke. However, whether and how they exert the antioxidant defense in stroke remains unclear. Herein, we discuss the chaperones shown to fight oxidative stress and the mechanisms of their antioxidant action. In ischemic stroke, during intense production of free radicals, molecular chaperones preserve the proteome by interacting with oxidized proteins, regulating imbalanced mitochondrial function, and directly fighting oxidative stress. For instance, cells recruit Hsp60 and Hsp70 to provide proper folding of newly synthesized proteins-these factors are required for early ischemic response and to refold damaged polypeptides. Additionally, Hsp70 upregulates some dedicated antioxidant pathways such as FOXO3 signaling. Small HSPs decrease oxidative stress via attenuation of mitochondrial function through their involvement in the regulation of Nrf- (Hsp22), Akt and Hippo (Hsp27) signaling pathways as well as mitophagy (Hsp27, Hsp22). A similar function has also been proposed for the Sigma-1 receptor, contributing to the regulation of mitochondrial function. Some chaperones can prevent excessive formation of reactive oxygen species whereas Hsp90 is suggested to be responsible for pro-oxidant effects in ischemic stroke. Finally, heat-resistant obscure proteins (Hero) are able to shield client proteins, thus preventing their possible over oxidation.

Reactive oxygen species control protein degradation at the mitochondrial import gate

While reactive oxygen species (ROS) have long been known to drive aging and neurodegeneration, their persistent depletion below basal levels also disrupts organismal function. Cells counteract loss of basal ROS via the reductive stress response, but the identity and biochemical activity of ROS sensed by this pathway remain unknown. Here, we show that the central enzyme of the reductive stress response, the E3 ligase Cullin 2-FEM1 homolog B (CUL2FEM1B), specifically acts at mitochondrial TOM complexes, where it senses ROS produced by complex III of the electron transport chain (ETC). ROS depletion during times of low ETC activity triggers the localized degradation of CUL2FEM1B substrates, which sustains mitochondrial import and ensures the biogenesis of the rate-limiting ETC complex IV. As complex III yields most ROS when the ETC outpaces metabolic demands or oxygen availability, basal ROS are sentinels of mitochondrial activity that help cells adjust their ETC to changing environments, as required for cell differentiation and survival.

NRF2 inhibitors: Recent progress, future design and therapeutic potential

Nuclear factor erythroid 2-related factor 2 (NRF2) is a crucial transcription factor involved in oxidative stress response, which controls the expression of various cytoprotective genes. Recent research has indicated that constitutively activated NRF2 can enhance patients' resistance to chemotherapy drugs, resulting in unfavorable prognosis. Therefore, the development of NRF2 inhibitors has emerged as a promising approach for overcoming drug resistance in cancer treatment. However, there are limited reports and reviews focusing on NRF2 inhibitors. This review aims to provide a comprehensive analysis of the structure and regulation of the NRF2 signaling pathway, followed by a comprehensive review of reported NRF2 inhibitors. Moreover, the current design strategies and future prospects of NRF2 inhibitors will be discussed, aiming to establish a foundation for the development of more effective NRF2 inhibitors.

Post-translational modification in the pathogenesis of vitiligo

Vitiligo is a chronic dermatological condition marked by the loss of skin pigmentation. Its complex etiology involves multiple factors and has not been completely elucidated. Protein post-translational modification pathways have been proven to play a significant role in inflammatory skin diseases, yet research in the context of vitiligo remains limited. This review focuses on the role of post-translational modifications in vitiligo pathogenesis, especially their impact on cellular signaling pathways related to immune response and melanocyte survival. Current therapeutic strategies targeting these pathways are discussed, emphasizing the potential for novel treatments in vitiligo management.

Ectopic USP15 expression inhibits HIV-1 transcription involving changes in YY1 deubiquitination and stability

Introduction

Protein homeostasis is maintained by the opposing action of ubiquitin ligase and deubiquitinase, two important components of the ubiquitin-proteasome pathway, and contributes to both normal physiological and pathophysiological processes. The current study aims to delineate the roles of ubiquitin-specific protease 15 (USP15), a member of the largest deubiquitinase family, in HIV-1 gene expression and replication.

Methods

We took advantage of highly selective and specific ubiquitin variants (UbV), which were recently designed and developed for USP15, and ascertained the inhibitory effects of USP15 on HIV-1 gene expression and production by transfection and Western blotting. We also used real-time RT-PCR, transcription factor profiling, subcellular fractionation, immunoprecipitation followed by Western blotting to determine the transcription factors involved and the underlying molecular mechanisms.

Results

We first confirmed the specificity of USP15-mediated HIV-1 gene expression and virus production. We then showed that the inhibition of HIV-1 production by USP15 occurred at the transcription level, associated with an increased protein level of YY1, a known HIV-1 transcription repressor. Moreover, we demonstrated that USP15 regulated YY1 deubiquitination and stability. Lastly, we demonstrated that YY1 siRNA knockdown significantly diminished the inhibition of USP15 on HIV-1 gene expression and virus production.

Conclusion

These findings together demonstrate that stabilization of YY1 protein by USP15 deubiquitinating activity contributes to USP15-mediated inhibition of HIV-1 transcription and may help the development of USP15-specific UbV inhibitors as an anti-HIV strategy.

Antioxidant and renal protective effects of Nano-selenium on adenine-induced acute renal failure in canines

Acute renal failure is a common clinical disease in canines, affecting antioxidant levels and decreasing the body's resistance. This study aims to explore the therapeutic mechanism of Nano-selenium in acute renal failure. The histopathological and imaging changes of kidney tissue were observed with the gene and protein expression levels of Keap1, Nrf2, HO-1, and NQO1 in the kidney. According to our findings, adding nano-selenium can effectively reduce the concentration of CRE and BUN in blood and kidney tissues. It increased the activity of GSH-PX and SOD by an effective reduction of MDA. Through pathological and imaging observations, it was found that adding nano-selenium could improve the kidney tissue structure of acute renal failure. The results of the RT-qPCR experiment showed that after the addition of nano-selenium, the mRNA expression of the Keap1 gene decreased significantly. In contrast, the mRNA expression of the Nrf2, HO-1, and NQO1 genes increased significantly. The experimental results were further verified by western blot and immunohistochemical analysis. Hence, the nano-selenium intervention improved kidney function and increased antioxidant levels in canines suffering from acute renal failure with the involvement of the Keap1-Nrf2/ARE signaling pathway.

Stress response regulation of mRNA translation: Implications for antioxidant enzyme expression in cancer

From tumorigenesis to advanced metastatic stages, tumor cells encounter stress, ranging from limited nutrient and oxygen supply within the tumor microenvironment to extrinsic and intrinsic oxidative stress. Thus, tumor cells seize regulatory pathways to rapidly adapt to distinct physiologic conditions to promote cellular survival, including manipulation of mRNA translation. While it is now well established that metastatic tumor cells must up-regulate their antioxidant capacity to effectively spread and that regulation of antioxidant enzymes is imperative to disease progression, relatively few studies have assessed how translation and the hijacking of RNA systems contribute to antioxidant responses of tumors. Here, we review the major stress signaling pathways involved in translational regulation and discuss how these are affected by oxidative stress to promote prosurvival changes that manipulate antioxidant enzyme expression. We describe how tumors elicit these adaptive responses and detail how stress-induced translation can be regulated by kinases, RNA-binding proteins, RNA species, and RNA modification systems. We also highlight opportunities for further studies focused on the role of mRNA translation and RNA systems in the regulation of antioxidant enzyme expression, which may be of particular importance in the context of metastatic progression and therapeutic resistance.

Nuclear factor erythroid 2-related factor-mediated signaling alleviates ferroptosis during cerebral ischemia-reperfusion injury

Cardiac arrest (CA) is a significant challenge for emergency physicians worldwide and leads to increased morbidity and mortality rates. The poor prognosis of CA primarily stems from the complexity and irreversibility of cerebral ischemia-reperfusion injury (CIRI). Ferroptosis, a form of programmed cell death characterized by iron overload and lipid peroxidation, plays a crucial role in the progression and treatment of CIRI. In this review, we highlight the mechanisms of ferroptosis within the context of CIRI, focusing on its role as a key contributor to neuronal damage and dysfunction post-CA. We explore the crucial involvement of the nuclear factor erythroid 2-related factor (Nrf2)-mediated signaling pathway in modulating ferroptosis-associated processes during CIRI. Through comprehensive analysis of the regulatory role of Nrf2 in the cellular responses to oxidative stress, we highlight its potential as a therapeutic target for mitigating ferroptotic cell death and improving the neurological prognosis of patients experiencing CA. Furthermore, we discuss interventions targeting the Kelch-like ECH-associated protein 1/Nrf2/antioxidant response element pathway, including the use of traditional Chinese medicine and Western medicine, which demonstrate potential for attenuating ferroptosis and preserving neuronal function in CIRI. Owing to the limitations in the safety, specificity, and effectiveness of Nrf2-targeted drugs, as well as the technical difficulties and ethical constraints in obtaining the results related to the brain pathological examination of patients, most of the studies focusing on Nrf2-related regulation of ferroptosis in CIRI are still in the basic research stage. Overall, this review aims to provide a comprehensive understanding of the mechanisms underlying ferroptosis in CIRI, offering insights into novel therapeutics aimed at enhancing the clinical outcomes of patients with CA.

The Complex Roles of Redox and Antioxidant Biology in Cancer

Redox reactions control fundamental biochemical processes, including energy production, metabolism, respiration, detoxification, and signal transduction. Cancer cells, due to their generally active metabolism for sustained proliferation, produce high levels of reactive oxygen species (ROS) compared to normal cells and are equipped with antioxidant defense systems to counteract the detrimental effects of ROS to maintain redox homeostasis. The KEAP1-NRF2 system plays a major role in sensing and regulating endogenous antioxidant defenses in both normal and cancer cells, creating a bivalent contribution of NRF2 to cancer prevention and therapy. Cancer cells hijack the NRF2-dependent antioxidant program and exploit a very unique metabolism as a trade-off for enhanced antioxidant capacity. This work provides an overview of redox metabolism in cancer cells, highlighting the role of the KEAP1-NRF2 system, selenoproteins, sulfur metabolism, heme/iron metabolism, and antioxidants. Finally, we describe therapeutic approaches that can be leveraged to target redox metabolism in cancer.

Moderate Hypothermia Alleviates Sepsis-Associated Acute Lung Injury by Suppressing Ferroptosis Induced by Excessive Inflammation and Oxidative Stress via the Keap1/GSK3β/Nrf2/GPX4 Signaling Pathway

Purpose

Sepsis-associated acute lung injury (SA-ALI) is a common complication in patients with sepsis, contributing to high morbidity and mortality. Excessive inflammation and oxidative stress are crucial contributors to lung injury in sepsis. This study aims to examine the protective effects of moderate hypothermia on SA-ALI and explore the underlying mechanisms.

Methods

Sepsis was induced in rats through cecal ligation and puncture followed by intervention with moderate hypothermia (32-33.9°C). Blood, bronchoalveolar lavage fluid, and lung tissues were collected 12 hours post-surgery. Inflammatory responses, oxidative injury, SA-ALI-related pathophysiological processes, and Keap1/GSK3β/Nrf2/GPX4 signaling in septic rats were observed by ELISA, lung W/D ratio, immunohistochemistry, immunofluorescence, histological staining, Western blotting, RT-qPCR, and TEM assays.

Results

Moderate hypothermia treatment alleviated lung injury in septic rats, reflected in amelioration of pathological changes in lung structure and improved pulmonary function. Further, moderate hypothermia reduced arterial blood lactate production and suppressed the expression of inflammatory factors IL-1β, IL-6, and TNF-α; downregulated ROS, MDA, and redox-active iron levels; and restored GSH and SOD content. TEM results demonstrated that moderate hypothermia could mitigate ferroptosis in PMVECs within lung tissue. The underlying mechanism may involve regulation of the Keap1/Nrf2/SLC7A11/GPX4 signaling pathway, with the insulin pathway PI3K/Akt/GSK3β also playing a partial role.

Conclusion

Collectively, we illustrated a novel potential therapeutic mechanism in which moderate hypothermia could alleviate ferroptosis induced by excessive inflammation and oxidative stress via the regulation of Keap1/GSK3β/Nrf2/GPX4 expression, hence ameliorating acute lung injury in sepsis.

NRF2 signaling and amino acid metabolism in cancer

Alterations in amino acid metabolism have emerged as a critical component in cancer biology, influencing various aspects of tumor initiation, progression, and metastasis. This review explores how amino acids, beyond their role as protein building blocks, are essential for redox balance, cell proliferation, metastasis, signaling/epigenetic regulation, and tumor microenvironment modulation in cancer. We particularly focus on the intricate relationship between amino acid metabolism and nuclear factor erythroid 2-related factor 2 (NRF2) signaling, a master regulator of oxidative stress response that frequently hyperactivated in cancer. Increasing evidence indicates that NRF2 is a key player in amino acid metabolism, orchestrating metabolism of cysteine, glutamine, and serine/glycine to promote cancer cell survival and growth. This comprehensive analysis provides insights into potential therapeutic strategies targeting the NRF2-amino acid metabolism axis, offering new avenues for cancer treatment that address multiple aspects of tumor biology.

Identification of a novel target of sulforaphane: Sulforaphane binds to acyl-protein thioesterase 2 (APT2) and attenuates its palmitoylation

Sulforaphane (SFaN) is a food-derived compound with several bioactive properties, including atherosclerosis, diabetes, and obesity treatment. However, the mechanisms by which SFaN exerts its various effects are still unclear. To elucidate the mechanisms of the various effects of SFaN, we explored novel SFaN-binding proteins using SFaN beads and identified acyl protein thioesterase 2 (APT2). We also found that SFaN binds to the APT2 via C56 residue and attenuates the palmitoylation of APT2, thereby reducing plasma membrane localization of APT2. This study reveals a novel bioactivity of SFaN as a regulator of APT2 protein palmitoylation.

The Multifaceted Protective Role of Nuclear Factor Erythroid 2-Related Factor 2 in Osteoarthritis: Regulation of Oxidative Stress and Inflammation

Osteoarthritis (OA) is a chronic degenerative joint disease characterized by the degradation of joint cartilage, subchondral bone sclerosis, synovitis, and structural changes in the joint. Recent research has highlighted the role of various genes in the pathogenesis and progression of OA, with nuclear factor erythroid 2-related factor 2 (NRF2) emerging as a critical player. NRF2, a vital transcription factor, plays a key role in regulating the OA microenvironment and slowing the disease's progression. It modulates the expression of several antioxidant enzymes, such as Heme oxygenase-1 (HO-1) and NAD(P)H oxidoreductase 1 (NQO1), among others, which help reduce oxidative stress. Furthermore, NRF2 inhibits the nuclear factor kappa-B (NF-κB) signaling pathway, thereby decreasing inflammation, joint pain, and the breakdown of cartilage extracellular matrix, while also mitigating cell aging and death. This review discusses NRF2's impact on oxidative stress, inflammation, cell aging, and various cell death modes (such as apoptosis, necroptosis, and ferroptosis) in OA-affected chondrocytes. The role of NRF2 in OA macrophages, and synovial fibroblasts was also discussed. It also covers NRF2's role in preserving the cartilage extracellular matrix and alleviating joint pain. The purpose of this review is to provide a comprehensive understanding of NRF2's protective mechanisms in OA, highlighting its potential as a therapeutic target and underscoring its significance in the development of novel treatment strategies for OA.

Lactobacilli Cell-Free Supernatants Modulate Inflammation and Oxidative Stress in Human Microglia via NRF2-SOD1 Signaling

Microglia are macrophage cells residing in the brain, where they exert a key role in neuronal protection. Through the gut-brain axis, metabolites produced by gut commensal microbes can influence brain functions, including microglial activity. The nuclear factor erythroid 2-related factor 2 (NRF2) is a key regulator of the oxidative stress response in microglia, controlling the expression of cytoprotective genes. Lactobacilli-derived cell-free supernatants (CFSs) are postbiotics that have shown antioxidant and immunomodulatory effects in several in vitro and in vivo studies. This study aimed to explore the effects of lactobacilli CFSs on modulating microglial responses against oxidative stress and inflammation. HMC3 microglia were exposed to lipopolysaccaride (LPS), as an inflammatory trigger, before and after administration of CFSs from three human gut probiotic species. The NRF2 nuclear protein activation and the expression of NRF2-controlled antioxidant genes were investigated by immunoassay and quantitative RT-PCR, respectively. Furthermore, the level of pro- and anti-inflammatory cytokines was evaluated by immunoassay. All CFSs induced a significant increase of NRF2 nuclear activity in basal conditions and upon inflammation. The transcription of antioxidant genes, namely heme oxygenase 1, superoxide dismutase (SOD), glutathione-S transferase, glutathione peroxidase, and catalase also increased, especially after inflammatory stimulus. Besides, higher SOD1 activity was detected relative to inflamed microglia. In addition, CFSs pre-treatment of microglia attenuated pro-inflammatory TNF-α levels while increasing anti-inflammatory IL-10 levels. These findings confirmed that gut microorganisms' metabolites can play a relevant role in adjuvating the microglia cellular response against neuroinflammation and oxidative stress, which are known to cause neurodegenerative diseases.

Toxic effects of dibutyl phthalate on testes of adult zebrafish: evaluation of oxidative stress parameters and histopathology

Dibutyl phthalate (DBP) is a phthalic compound and is most commonly used as a plasticizer in the polymer industry. It affects the hypothalamus-pituitary-gonadal axis and produces infertility in exposed animals. A total of 366 adult male zebrafish were used to evaluate the toxicological effects of DBP in testes following continuous exposure for 28 days. To evaluate histological changes during phase I of the study, 30 zebrafish were equally divided into five groups viz., control (RO water), vehicle control (0.01% DMSO), T0 (250 µg/L of water), T1 (500 µg/L of water), and T2 group (1000 µg/L of water). The protocol for phase II of the study was decided based on the results of phase I of the study. During phase II, for evaluation of oxidative stress parameters and gene expression profile, a total of 336 fish were equally divided into four groups viz., control, vehicle control, T1 (500 µg/L of water), and T2 (1000 µg/L of water). The activity of SOD, CAT, and TAC was significantly lower in zebrafish from the T2 group; however, a significantly increased level of MDA in the T2 group was recorded as compared to control groups. mRNA expression profile of sod, cat, and nrf2 genes was significantly downregulated in the T2 group as compared to the control group. Histopathology and proliferating cell nuclear antigen immunostaining revealed a reduction in spermatozoa with increased spermatocytes and spermatogonia in testes from T1 and T2 groups. The result indicated that DBP can induce oxidative stress and affect spermatogenesis in zebrafish testes.

A potential therapeutic strategy based on acute oxidative stress induction for wild-type NRF2/KEAP1 lung squamous cell carcinoma

Extensive efforts have been conducted in the search for new targetable drivers of lung squamous cell carcinoma (LUSC); to date, however, candidates remain mostly unsuccessful. One of the oncogenic pathways frequently found to be active in LUSC is NFE2L2 (NRF2 transcription factor), the levels of which are regulated by KEAP1. Mutations in NFE2L2 or KEAP1 trigger NRF2 activation, an essential protector against reactive oxygen species (ROS). We hypothesized that the frequency of NRF2 activation in LUSC (∼35 %) may reflect a sensitivity of LUSC to ROS. Results from this study reveal that whereas tumors containing active forms of NRF2 were protected, ROS induction in wild-type NFE2L2/KEAP1 LUSC cells triggered ferroptosis. The mechanism of ROS action in normal-NRF2 LUSC cells involved transient NRF2 activation, miR-126-3p/miR-126-5p upregulation, and reduction of p85β and SETD5 levels. SETD5 levels reduction triggered pentose pathway gene levels increase to toxic values. Simultaneous depletion of p85βPI3K and SETD5 triggered LUSC cell death, while p85βPI3K and SETD5 overexpression rescued survival of ROS-treated normal-NRF2 LUSC cells. This shows that the cascade involving NRF2 > miR-126-3p, miR-126-5p > p85βPI3K and SETD5 is responsible for ROS-induced cell death in normal-NRF2 LUSC. Transient ROS-induced cell death is shown in 3D spheroids, patient-derived organoids, and in xenografts of wild-type NFE2L2/KEAP1 LUSC cells, supporting the potential of acute local ROS induction as a therapeutic strategy for LUSC patients with normal-NRF2.

The application of alkaloids in ferroptosis: A review

Alkaloids have remarkable biological and pharmacological properties and have recently garnered extensive attention. Various alkaloids, including commercially available drugs such as berberine, substantially affect ferroptosis. In addition to the three main pathways of ferroptosis, iron metabolism, phospholipid metabolism, and the glutathione peroxidase 4-regulated pathway, novel mechanisms of ferroptosis are continuously being identified. Alkaloids can modulate the progression of various diseases through ferroptosis and exhibit the ability to exert varied effects depending on dosage and tissue type underscores their versatility. Therefore, this review comprehensively summarizes primary targets and the latest advancements of alkaloids in ferroptosis, as well as the dual roles of alkaloids in inhibiting and promoting ferroptosis.

The deubiquitinating enzyme USP35 regulates the stability of NRF2 protein

Many cancers exhibit resistance to chemotherapy, resulting in a poor prognosis. The transcription factor NRF2, activated in response to cellular antioxidants, plays a crucial role in cell survival, proliferation, and resistance to chemotherapy. This factor may serve as a promising target for therapeutic interventions in esophageal carcinoma. Recent research suggests that NRF2 activity is modulated by ubiquitination mediated by the KEAP1-CUL3 E3 ligase complex, highlighting the importance of deubiquitination. However, the specific deubiquitinase responsible for regulating NRF2 in esophageal cancer remains unknown. In this study, a novel regulator of the NRF2 protein, Ubiquitin-Specific Protease 35 (USP35), has been identified. Mechanistically, USP35 modulates NRF2 stability through enzymatic deubiquitination. USP35 interacts with NRF2 and facilitates its deubiquitination. Knockdown of USP35 leads to a notable increase in NRF2 levels and enhances the sensitivity of cells to chemotherapy. These findings suggest that the USP35-NRF2 axis is a key player in the regulation of therapeutic strategies for esophageal cancer.

Sesamolin suppresses adipocyte differentiation through Keap1-dependent Nrf2 activation in adipocytes

Sesamolin, a lignan isolated from sesame oils, has been found to possess neuroprotective, anticancer, and free radical scavenging properties. We hypothesized that sesamolin could stimulate the activity of nuclear factor erythroid-derived 2-like 2 (Nrf2) and inhibit adipocyte differentiation of preadipocytes. The objective of this study was to investigate effects of sesamolin on adipocyte differentiation and its underlying molecular mechanisms. In this study, we determined the effects of treatment with 25 to 100 µM sesamolin on adipogenesis in cell culture systems. Sesamolin inhibited lipid accumulation and suppressed the expression of adipocyte markers during adipocyte differentiation of C3H10T1/2, 3T3-L1, and primary preadipocytes. Mechanism studies revealed that sesamolin increased Nrf2 protein expression without inducing its mRNA, leading to an increase in the expression of Nrf2 target genes such as heme oxygenase 1 and NAD(P)H:quinone oxidoreductase 1 (Nqo1) in C3H10T1/2 adipocytes and mouse embryonic fibroblasts. These effects were significantly attenuated in Nrf2 knockout (KO) mouse embryonic fibroblasts, indicating that effects of sesamolin were dependent on Nrf2. In H1299 human lung cancer cells with KO of Kelch like-ECH-associated protein 1 (Keap1), a negative regulator of Nrf2, sesamolin failed to further increase Nrf2 protein expression. However, upon reexpressing Keap1 in Keap1 KO cells, the ability of sesamolin to elevate Nrf2 protein expression was restored, highlighting the crucial role of Keap1 in sesamolin-induced Nrf2 activation. Taken together, these findings show that sesamolin can inhibit adipocyte differentiation through Keap1-mediated Nrf2 activation.

The Effect of Phytocannabinoids and Endocannabinoids on Nrf2 Activity in the Central Nervous System and Periphery

The relationship between nuclear factor erythroid 2-related factor 2 (Nrf2) and phytocannabinoids/endocannabinoids (pCBs/eCBs) has been investigated in a variety of models of peripheral illnesses, with little clarification on their interaction within the central nervous system (CNS). In this context, evidence suggests that the Nrf2-pCBs/eCBS interaction is relevant in modulating peroxidation processes and the antioxidant system. Nrf2, one of the regulators of cellular redox homeostasis, appears to have a protective role toward damaging insults to neurons and glia by enhancing those genes involved in the regulation of homeostatic processes. Specifically in microglia and macroglia cells, Nrf2 can be activated, and its signaling pathway modulated, by both pCBs and eCBs. However, the precise effects of pCBs and eCBs on the Nrf2 signaling pathway are not completely elucidated yet, making their potential clinical employment still not fully understood.

Role of O-linked N-acetylglucosamine protein modification in oxidative stress-induced autophagy: a novel target for bone remodeling

O-linked N-acetylglucosamine protein modification (O-GlcNAcylation) is a dynamic post-translational modification (PTM) involving the covalent binding of serine and/or threonine residues, which regulates bone cell homeostasis. Reactive oxygen species (ROS) are increased due to oxidative stress in various pathological contexts related to bone remodeling, such as osteoporosis, arthritis, and bone fracture. Autophagy serves as a scavenger for ROS within bone marrow-derived mesenchymal stem cells, osteoclasts, and osteoblasts. However, oxidative stress-induced autophagy is affected by the metabolic status, leading to unfavorable clinical outcomes. O-GlcNAcylation can regulate the autophagy process both directly and indirectly through oxidative stress-related signaling pathways, ultimately improving bone remodeling. The present interventions for the bone remodeling process often focus on promoting osteogenesis or inhibiting osteoclast absorption, ignoring the effect of PTM on the overall process of bone remodeling. This review explores how O-GlcNAcylation synergizes with autophagy to exert multiple regulatory effects on bone remodeling under oxidative stress stimulation, indicating the application of O-GlcNAcylation as a new molecular target in the field of bone remodeling.

Itaconate as a key player in cardiovascular immunometabolism

Cardiovascular diseases (CVDs) are the leading cause of death globally, resulting in a major health burden. Thus, an urgent need exists for exploring effective therapeutic targets to block progression of CVDs and improve patient prognoses. Immune and inflammatory responses are involved in the development of atherosclerosis, ischemic myocardial damage responses and repair, calcification, and stenosis of the aortic valve. These responses can involve both large and small blood vessels throughout the body, leading to increased blood pressure and end-organ damage. While exploring potential avenues for therapeutic intervention in CVDs, researchers have begun to focus on immune metabolism, where metabolic changes that occur in immune cells in response to exogenous or endogenous stimuli can influence immune cell effector responses and local immune signaling. Itaconate, an intermediate metabolite of the tricarboxylic acid (TCA) cycle, is related to pathophysiological processes, including cellular metabolism, oxidative stress, and inflammatory immune responses. The expression of immune response gene 1 (IRG1) is upregulated in activated macrophages, and this gene encodes an enzyme that catalyzes the production of itaconate from the TCA cycle intermediate, cis-aconitate. Itaconate and its derivatives have exerted cardioprotective effects through immune modulation in various disease models, such as ischemic heart disease, valvular heart disease, vascular disease, heart transplantation, and chemotherapy drug-induced cardiotoxicity, implying their therapeutic potential in CVDs. In this review, we delve into the associated signaling pathways through which itaconate exerts immunomodulatory effects, summarize its specific roles in CVDs, and explore emerging immunological therapeutic strategies for managing CVDs.

Growth, Antioxidant Capacity, and Liver Health in Largemouth Bass (Micropterus salmoides) Fed Multi-Strain Yeast-Based Paraprobiotic: A Lab-to-Pilot Scale Evaluation

A multi-strain yeast-based paraprobiotic (MsYbP) comprising inactive cells and polysaccharides (β-glucan, mannan oligosaccharides, and oligosaccharides) derived from Saccharomyces cerevisiae and Cyberlindnera jadinii could ensure optimal growth and health in farmed fish. This study assessed the impact of an MsYbP on the growth, immune responses, antioxidant capacities, and liver health of largemouth bass (Micropterus salmoides) through lab-scale (65 days) and pilot-scale (15 weeks) experiments. Two groups of fish were monitored: one fed a control diet without the MsYbP and another fed 0.08% and 0.1% MsYbP in the lab-scale and pilot-scale studies, respectively (referred to as YANG). In the lab-scale study, four replicates were conducted, with 20 fish per replicate (average initial body weight = 31.0 ± 0.8 g), while the pilot-scale study involved three replicates with approximately 1500 fish per replicate (average initial body weight = 80.0 ± 2.2 g). The results indicate that the MsYbP-fed fish exhibited a significant increase in growth in both studies (p < 0.05). Additionally, the dietary MsYbP led to a noteworthy reduction in the liver function parameters (p < 0.05), such as alanine aminotransferase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase (AKP), and hepatic nuclear density, indicating improved liver health. Furthermore, the dietary MsYbP elevated the antioxidative capacity of the fish by reducing their malondialdehyde levels and increasing their levels and gene expressions related to antioxidative markers, such as total antioxidant ca-pacity (T-AOC), total superoxide dismutase (T-SOD), glutathione peroxidase (GSH-Px), catalase (CAT), nuclear factor erythroid 2-related factor 2 (nrf2) and kelch-1ike ech-associated protein (keap1) in both studies (p < 0.05). In terms of hepatic immune responses, the lab-scale study showed an increase in inflammation-related gene expressions, such as interleukin-1β (il-1β) and transforming growth factor β1 (tgf-β1), while the pilot-scale study significantly suppressed the expressions of genes related to inflammatory responses, such as tumor necrosis factor α (tnfα) and interleukin-10 (il-10) (p < 0.05). In summary, our findings underscore the role of dietary multi-strain yeast-based paraprobiotics in enhancing the growth and liver health of largemouth bass, potentially through increased antioxidative capacity and the modulation of immune responses, emphasizing the significance of employing yeast-based paraprobiotics in commercial conditions.

Bivalent inhibitors of the BTB E3 ligase KEAP1 enable instant NRF2 activation to suppress acute inflammatory response

Most BTB-containing E3 ligases homodimerize to recognize a single substrate by engaging multiple degrons, represented by E3 ligase KEAP1 dimer and its substrate NRF2. Inactivating KEAP1 to hinder ubiquitination-dependent NRF2 degradation activates NRF2. While various KEAP1 inhibitors have been reported, all reported inhibitors bind to KEAP1 in a monovalent fashion and activate NRF2 in a lagging manner. Herein, we report a unique bivalent KEAP1 inhibitor, biKEAP1 (3), that engages cellular KEAP1 dimer to directly release sequestered NRF2 protein, leading to an instant NRF2 activation. 3 promotes the nuclear translocation of NRF2, directly suppressing proinflammatory cytokine transcription. Data from in vivo experiments showed that 3, with unprecedented potency, reduced acute inflammatory burden in several acute inflammation models in a timely manner. Our findings demonstrate that the bivalent KEAP1 inhibitor can directly enable sequestered substrate NRF2 to suppress inflammatory transcription response and dampen various acute inflammation injuries.

PPIA dictates NRF2 stability to promote lung cancer progression

Nuclear factor erythroid 2-related factor 2 (NRF2) hyperactivation has been established as an oncogenic driver in a variety of human cancers, including non-small cell lung cancer (NSCLC). However, despite massive efforts, no specific therapy is currently available to target NRF2 hyperactivation. Here, we identify peptidylprolyl isomerase A (PPIA) is required for NRF2 protein stability. Ablation of PPIA promotes NRF2 protein degradation and blocks NRF2-driven growth in NSCLC cells. Mechanistically, PPIA physically binds to NRF2 and blocks the access of ubiquitin/Kelch Like ECH Associated Protein 1 (KEAP1) to NRF2, thus preventing ubiquitin-mediated degradation. Our X-ray co-crystal structure reveals that PPIA directly interacts with a NRF2 interdomain linker via a trans-proline 174-harboring hydrophobic sequence. We further demonstrate that an FDA-approved drug, cyclosporin A (CsA), impairs the interaction of NRF2 with PPIA, inducing NRF2 ubiquitination and degradation. Interestingly, CsA interrupts glutamine metabolism mediated by the NRF2/KLF5/SLC1A5 pathway, consequently suppressing the growth of NRF2-hyperactivated NSCLC cells. CsA and a glutaminase inhibitor combination therapy significantly retard tumor progression in NSCLC patient-derived xenograft (PDX) models with NRF2 hyperactivation. Our study demonstrates that targeting NRF2 protein stability is an actionable therapeutic approach to treat NRF2-hyperactivated NSCLC.

N -N-Butyl Haloperidol Iodide Mitigates Myocardial Ischemia/Reperfusion Injury Through Activation of SIRT1-Nrf2 Signaling Loop

ABSTRACT

N -n-butyl haloperidol iodide (F 2 ), a derivative of haloperidol developed by our group, exhibits potent antioxidative properties and confers protection against cardiac ischemia/reperfusion (I/R) injury. The protective mechanisms by which F 2 ameliorates I/R injury remain obscure. The activation of nuclear factor erythroid 2-related factor 2 (Nrf2), a key transcription factor transactivating many antioxidative genes, also attenuates I/R-induced myocardial damage. The present study investigated whether the cardioprotective effect of F 2 depends on Nrf2 using a mouse heart I/R model. F 2 (0.1, 0.2 or 0.4 mg/kg) or vehicle was intravenously injected to mice 5 minutes before reperfusion. Systemic administration of 0.4 mg/kg F 2 led to a significant reduction in I/R injury, which was accompanied by enhanced activation of Nrf2 signaling. The cardioprotection conferred by F 2 was largely abrogated in Nrf2-deficient mice. Importantly, we found F 2 -induced activation of Nrf2 is silent information regulator of transcription 1 (SIRT1)-dependent, as pharmacologically inhibiting SIRT1 by the specific inhibitor EX527 blocked Nrf2 activation. Moreover, F 2 -upregulated expression of SIRT1 was also Nrf2-dependent, as Nrf2 deficiency inhibited SIRT1 upregulation. These results indicate that SIRT1-Nrf2 signaling loop activation is indispensable for the protective effect of F 2 against myocardial I/R injury and may provide new insights for the treatment of ischemic heart disease.

Anti-Inflammatory Therapeutic Mechanisms of Isothiocyanates: Insights from Sulforaphane

Isothiocyanates (ITCs) belong to a group of natural products that possess a highly reactive electrophilic -N=C=S functional group. They are stored in plants as precursor molecules, glucosinolates, which are processed by the tyrosinase enzyme upon plant tissue damage to release ITCs, along with other products. Isolated from broccoli, sulforaphane is by far the most studied antioxidant ITC, acting primarily through the induction of a transcription factor, the nuclear factor erythroid 2-related factor 2 (Nrf2), which upregulates downstream antioxidant genes/proteins. Paradoxically, sulforaphane, as a pro-oxidant compound, can also increase the levels of reactive oxygen species, a mechanism which is attributed to its anticancer effect. Beyond highlighting the common pro-oxidant and antioxidant effects of sulforaphane, the present paper was designed to assess the diverse anti-inflammatory mechanisms reported to date using a variety of in vitro and in vivo experimental models. Sulforaphane downregulates the expression of pro-inflammatory cytokines, chemokines, adhesion molecules, cycloxyhenase-2, and inducible nitric oxide synthase. The signalling pathways of nuclear factor κB, activator protein 1, sirtuins 1, silent information regulator sirtuin 1 and 3, and microRNAs are among those affected by sulforaphane. These anti-inflammatory actions are sometimes due to direct action via interaction with the sulfhydryl structural moiety of cysteine residues in enzymes/proteins. The following are among the topics discussed in this paper: paradoxical signalling pathways such as the immunosuppressant or immunostimulant mechanisms; crosstalk between the oxidative and inflammatory pathways; and effects dependent on health and disease states.

A conserved N-terminal motif of CUL3 contributes to assembly and E3 ligase activity of CRL3KLHL22

The CUL3-RING E3 ubiquitin ligases (CRL3s) play an essential role in response to extracellular nutrition and stress stimuli. The ubiquitin ligase function of CRL3s is activated through dimerization. However, how and why such a dimeric assembly is required for its ligase activity remains elusive. Here, we report the cryo-EM structure of the dimeric CRL3KLHL22 complex and reveal a conserved N-terminal motif in CUL3 that contributes to the dimerization assembly and the E3 ligase activity of CRL3KLHL22. We show that deletion of the CUL3 N-terminal motif impairs dimeric assembly and the E3 ligase activity of both CRL3KLHL22 and several other CRL3s. In addition, we found that the dynamics of dimeric assembly of CRL3KLHL22 generates a variable ubiquitination zone, potentially facilitating substrate recognition and ubiquitination. These findings demonstrate that a CUL3 N-terminal motif participates in the assembly process and provide insights into the assembly and activation of CRL3s.

Protective effects of sodium humate and its zinc and selenium chelate on the oxidative stress, inflammatory, and intestinal barrier damage of Salmonella Typhimurium-challenged broiler chickens

The objective of this study was to investigate the protective effects and mechanisms of dietary administration of sodium humate (HNa) and its zinc and selenium chelate (Zn/Se-HNa) in mitigating Salmonella Typhimurium (S. Typhi) induced intestinal injury in broiler chickens. Following the gavage of 109 CFU S. Typhi to 240 broilers from 21-d to 23-d aged, various growth performance parameters such as body weight (BW), average daily gain (ADG), average daily feed intake (ADFI), and feed ratio (FCR) were measured before and after infection. Intestinal morphology was assessed to determine the villus height, crypt depth, and chorionic cryptologic ratio. To evaluate intestinal barrier integrity, levels of serum diamine oxidase (DAO), D-lactic acid, tight junction proteins, and the related genes were measured in each group of broilers. An analysis was conducted on inflammatory-related cytokines, oxidase activity, and Nuclear Factor Kappa B (NF-κB) and Nuclear factor erythroid2-related factor 2 (Nrf2) pathway-related proteins and mRNA expression. The results revealed a significant decrease in BW, ADG, and FCR in S. typhi-infected broilers. HNa tended to increase FCR (P = 0.056) while the supplementation of Zn/Se-HNa significantly restored BW and ADG (P < 0.05). HNa and Zn/Se-HNa exhibit favorable and comparable effects in enhancing the levels of serum DAO, D-lactate, and mRNA and protein expression of jejunum and ileal tight junction. In comparison to HNa, Zn/Se-HNa demonstrates a greater reduction in S. Typhi shedding in feces, as well as superior efficacy in enhancing the intestinal morphology, increasing serum catalase (CAT) activity, inhibiting pro-inflammatory cytokines, and suppressing the activation of the NF-κB pathway. Collectively, Zn/Se-HNa was a more effective treatment than HNa to alleviate adverse impact of S. Typhi infection in broiler chickens.