Expression Of Nrf2 Target Genes Research Articles

Apo-12′-capsorubinal exhibits anti-inflammatory effects and activates nuclear factor erythroid 2-related factor 2 in RAW264.7 macrophages

Apocarotenoids have short carbon chain structures cleaved at a polyene-conjugated double bond. They can be biosynthesized in plants and microorganisms. Animals ingest carotenoids through food and then metabolize them into apocarotenoids. Although several apocarotenoids have been identified in the body, their precise health functions are still poorly understood. This study investigated the anti-inflammatory activities of apo-12′-capsorubinal in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages. It was confirmed that apo-12′-capsorubinal was not cytotoxic to the macrophages at the concentrations tested. Apo-12′-capsorubinal treatment led to a marked downregulation of interleukin (IL)-6 protein and Il6 mRNA levels. This apocarotenoid exhibited more potent inhibitory effects than its parent carotenoids, capsanthin and capsorubin. Furthermore, apo-12′-capsorubinal, but not its parent carotenoids, promoted the nuclear accumulation of nuclear factor erythroid 2-related factor 2 (Nrf2) and upregulated the expression of Nrf2-target genes, such as heme oxygenase 1 (HO-1) and NAD(P)H:quinone oxidoreductase 1 (NQO-1), in a dose-dependent manner. Furthermore, a comparison using apo-12′-zeaxanthinal and 7,8-dihydro-8-oxo-apo-12′-zeaxanthinal revealed that the α, β-unsaturated carbonyl group on the polyene linear chain mediated the enhanced nuclear Nrf2 translocation, HO-1 expression, and inhibition of IL-6 production. In contrast, apo-12′-mytiloxanthinal, which harbored a hydroxyl group at C-8 of apo-12′-capsorubinal, did not exhibit any of these activities. These results indicated that the β carbon of the α, β-unsaturated carbonyl group in the linear part of the polyene chain is crucial to the Nrf2-activating and anti-inflammatory effects of apo-12′-capsorubinal. This study will advance our knowledge of the physiological significance of xanthophyll-derived apocarotenoids and their potential use as nutraceuticals and pharmaceuticals.

Phosphocreatine attenuates doxorubicin-induced nephrotoxicity through inhibition of apoptosis, and restore mitochondrial function via activation of Nrf2 and PGC-1α pathways

Doxorubicin (DOX), a chemotherapy drug widely recognized for its efficacy in cancer treatment, unfortunately, has significant nephrotoxic effects leading to kidney damage. This study explores the nephroprotective potential of Phosphocreatine (PCr) in rats, specifically examining its influence on Nrf2 (Nuclear factor erythroid 2-related factor 2) and PGC-1α (Peroxisome proliferator-activated receptor gamma coactivator 1-alpha) pathways, its role in apoptosis inhibition, and effectiveness in preserving mitochondrial function. The research employed in vivo experiments in rats, focusing on PCr's capacity to protect renal function against doxorubicin-induced damage. The study entailed evaluating Nrf2 and PGC-1α pathway activation, apoptosis rates, and mitochondrial health in renal tissues. A significant aspect of this research was the use of high-resolution respirometry (HRR) to assess the function of isolated kidney mitochondria, providing in-depth insights into mitochondrial bioenergetics and respiratory efficiency under the influence of PCr and doxorubicin. Results demonstrated that PCr treatment significantly enhanced the activation of Nrf2 and PGC-1α pathways, reduced apoptosis, and preserved mitochondrial structure in doxorubicin-affected kidneys. Observations included upregulated expression of Nrf2 and PGC-1α target genes, stabilization of mitochondrial membranes, and a notable improvement in cellular antioxidant defense, evidenced by the activities of enzymes like superoxide dismutase (SOD), glutathione (GSH), malondialdehyde (MDA) This study positions phosphocreatine as a promising agent in mitigating doxorubicin-induced kidney damage in rats. The findings, particularly the insights from HRR on isolated kidney mitochondria, highlight PCr's potential in enhancing mitochondrial function and reducing nephrotoxic side effects of chemotherapy. These encouraging results pave the way for further research into PCr's applications in cancer treatment, aiming to improve patient outcomes by managing chemotherapy-related renal injuries.

Sesamin Exerts an Antioxidative Effect by Activating the Nrf2 Transcription Factor in the Glial Cells of the Central Nervous System in Drosophila Larvae.

Sesame seeds are abundant in sesamin, which exerts health-promoting effects such as extending the lifespan of adult Drosophila and suppressing oxidative stress by activating the Nrf2 transcription factor. Here, we investigated whether sesamin activated Nrf2 in larval tissues and induced the expression of Nrf2 target genes. In the sesamin-fed larvae, Nrf2 was activated in the central nervous system (CNS), gut, and salivary glands. The ectopic expression of Keap1 in glial cells inhibited sesamin-induced Nrf2 activation in the whole CNS more than in the neurons, indicating that sesamin activates Nrf2 in glia efficiently. We labeled the astrocytes as well as cortex and surface glia with fluorescence to identify the glial cell types in which Nrf2 was activated; we observed their activation in both cell types. These data suggest that sesamin may stimulate the expression of antioxidative genes in glial cells. Among the 17 candidate Nrf2 targets, the mRNA levels of Cyp6a2 and Cyp6g1 in cytochrome P450 were elevated in the CNS, gut, and salivary glands of the sesamin-fed larvae. However, this elevation did not lead to resistance against imidacloprid, which is detoxified by these enzymes. Our results suggest that sesamin may exert similar health-promoting effects on the human CNS and digestive tissues.

Activation of Nrf2 inhibits atherosclerosis in ApoE−/− mice through suppressing endothelial cell inflammation and lipid peroxidation

BackgroundNuclear erythroid 2-related factor 2 (Nrf2), a transcription factor, is critically involved in the regulation of oxidative stress and inflammation. However, the role of endothelial Nrf2 in atherogenesis has yet to be defined. In addition, how endothelial Nrf2 is activated and whether Nrf2 can be targeted for the prevention and treatment of atherosclerosis is not explored. MethodsRNA-sequencing and single-cell RNA sequencing analysis of mouse atherosclerotic aortas were used to identify the differentially expressed genes. In vivo endothelial cell (EC)-specific activation of Nrf2 was achieved by injecting adeno-associated viruses into ApoE−/− mice, while EC-specific knockdown of Nrf2 was generated in Cdh5CreCas9floxed-stopApoE−/− mice. ResultsEndothelial inflammation appeared as early as on day 3 after feeding of a high cholesterol diet (HCD) in ApoE−/− mice, as reflected by mRNA levels, immunostaining and global mRNA profiling, while the immunosignal of the end-product of lipid peroxidation (LPO), 4-hydroxynonenal (4-HNE), started to increase on day 10. TNF-α, 4-HNE, and erastin (LPO inducer), activated Nrf2 signaling in human ECs by increasing the mRNA and protein expression of Nrf2 target genes. Knockdown of endothelial Nrf2 resulted in augmented endothelial inflammation and LPO, and accelerated atherosclerosis in Cdh5CreCas9floxed-stopApoE−/− mice. By contrast, both EC-specific and pharmacological activation of Nrf2 inhibited endothelial inflammation, LPO, and atherogenesis. ConclusionsUpon HCD feeding in ApoE−/− mice, endothelial inflammation is an earliest event, followed by the appearance of LPO. EC-specific activation of Nrf2 inhibits atherosclerosis while EC-specific knockdown of Nrf2 results in the opposite effect. Pharmacological activators of endothelial Nrf2 may represent a novel therapeutic strategy for the treatment of atherosclerosis.

Melatonin ameliorates multiorgan injuries induced by severe acute pancreatitis in mice by regulating the Nrf2 signaling pathway

Severe acute pancreatitis (SAP) is a complicated inflammatory reaction that impacts the pancreas, often resulting in damage to numerous organs. This disorder encompasses a range of processes such as inflammation, oxidative stress, and pancreatitis. The hormone melatonin (MT) is primarily secreted by the pineal gland and plays a crucial role in mitigating inflammation, countering the harmful effects of free radicals, and regulating oxidative stress. The aim of this research was to investigate the potential protective impact and the underlying mechanism of melatonin in mice afflicted with SAP. The biochemical and histological assessments unequivocally demonstrated that melatonin effectively inhibited necrosis, infiltration, edema and cell death in pancreatic tissues, thereby suppressing acute pancreatitis. Notably, melatonin also alleviated the consequent harm to distant organs, notably the lungs, liver, and kidneys. Furthermore, both preventive and therapeutic administration of melatonin prompted nuclear factor E2-related factor 2 (Nrf2) activation followed by Nrf2 target gene expression. Nrf2 initiates the activation of antioxidant genes, thereby providing defense against oxidative stress. Conversely, Nrf2 reduction may contribute to impaired antioxidant protection in SAP. The beneficial impact of Nrf2 on antioxidants was absent in Nrf2-knockout mice, leading to the accumulation of LDH and exacerbation of cell death. This deterioration in both pancreatitis and injuries in distant organs intensified significantly. The results indicate that melatonin has an enhanced ability to protect against multiorgan damage caused by SAP, which is accomplished through the increase in Nrf2 expression. Additionally, Nrf2 initiates the activation of antioxidant genes that offer defense against cell death.

The impact of chitooligosaccharides with a certain degree of polymerization on diabetic nephropathic mice and high glucose-damaged HK-2 cells.

Diabetic nephropathy (DN) is a primary diabetic complication ascribed to the pathological changes in renal microvessels. This study investigated the nuclear factor erythroid 2-related factor 2 (Nrf2)/Kelch ECH associating protein (Keap1)/antioxidant response element (ARE) signaling pathway impact of chitooligosaccharides (COS) with a certain degree of polymerization (DP) on DN mouse models and high glucose-damaged human kidney 2 (HK-2) cells. The findings indicated that COS effectively reduced the renal function indexes (uric acid [UA], urinary albumin excretion rate [UAER], urine albumin-to-creatinine ratio [UACR], blood urea nitrogen [BUN], and creatinine [Cre]) of DN mice. It increased (p < .05) the superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) antioxidant enzyme activity in the serum and kidneys, and decreased (p < .05) the malondialdehyde (MDA) content. The mechanistic investigation showed that COS significantly increased (p < .05) Nrf2 and downstream target gene (GCLM, GCLC, HO-1, and NQO-1) expression, and substantially decreased (p < .05) Keap1 expression. The protein level was consistent with the messenger RNA (mRNA) level in invitro and invivo models. The docking data indicated that COS and Keap1 protein binding included six hydrogen bond formation processes (Gly364, Arg415, Arg483, His436, Ser431, and Arg380). The COS intervention mechanism may be related to the Nrf2/Keap1/ARE antioxidant pathway. Therefore, it provides a scientific basis for COS application in developing special medical food for DN patients.

Induction of Oxidative Stress and Ferroptosis in Triple-Negative Breast Cancer Cells by Niclosamide via Blockade of the Function and Expression of SLC38A5 and SLC7A11.

The amino acid transporters SLC38A5 and SLC7A11 are upregulated in triple-negative breast cancer (TNBC). SLC38A5 transports glutamine, methionine, glycine and serine, and therefore activates mTOR signaling and induces epigenetic modifications. SLC7A11 transports cystine and increases the cellular levels of glutathione, which protects against oxidative stress and lipid peroxidation via glutathione peroxidase, a seleno (Se)-enzyme. The primary source of Se is dietary Se-methionine (Se-Met). Since SLC38A5 transports methionine, we examined its role in Se-Met uptake in TNBC cells. We found that SLC38A5 interacts with methionine and Se-Met with comparable affinity. We also examined the influence of Se-Met on Nrf2 in TNBC cells. Se-Met activated Nrf2 and induced the expression of Nrf2-target genes, including SLC7A11. Our previous work discovered niclosamide, an antiparasitic drug, as a potent inhibitor of SLC38A5. Here, we found SLC7A11 to be inhibited by niclosamide with an IC50 value in the range of 0.1-0.2 μM. In addition to the direct inhibition of SLC38A5 and SLC7A11, the pretreatment of TNBC cells with niclosamide reduced the expression of both transporters. Niclosamide decreased the glutathione levels, inhibited proliferation, suppressed GPX4 expression, increased lipid peroxidation, and induced ferroptosis in TNBC cells. It also significantly reduced the growth of the TNBC cell line MB231 in mouse xenografts.

Hepatoprotective effects of Elaeagnus latifolia fruit extract against acetaminophen-induced hepatotoxicity in mice: Mechanistic insights

Elaeagnus latifolia fruit extract (EE) has been reported to contain antioxidant and anti-inflammatory phytochemicals. The present study aimed to examine the anti-hepatotoxic effects of EE in acetaminophen (APAP)-injected mice. Pretreatment with EE for 7 days in APAP mice showed significant reductions in the levels of AST and ALT and necrotic area, accompanied by decreases in liver oxidative stress, nitric oxide, and infiltrating inflammatory cells, compared to the APAP-only group. EE markedly down-regulated expression of CYP2E1, JNK, Bax, NOX subunit, and NF-κB target genes, and up-regulated expression of Bcl-2 and Nrf2 target genes in the livers. Furthermore, EE effectively lowered serum and hepatic lipids, and down-regulated expression of SREBP-1c/2 genes. EE was found to contain phenolic compounds, flavonoids, and proanthocyanidins. Therefore, mechanistic insights into EE's anti-hepatotoxic effects may be associated with preventing the abnormal expression of genes involved in toxic metabolite generation, hepatotoxic signaling, apoptosis, oxidative stress, inflammation, and lipid synthesis.

A new mouse strain with mutation in the NFE2L2 (NRF2 gene

The transcription factor NRF2 is involved in inflammatory reactions, maintenance of redox balance, metabolism of xenobiotics, and is of particular interest for aging studies. In the present work, CRISPR/Cas9 genome editing technology was used to generate NRF2ΔNeh2 mice containing a substitution of eight amino acid residues at the N-terminus of the NRF2 protein, upstream of the functional Neh2 domain, which ensures binding of NRF2 to its inhibitor KEAP1. Heterozygote NRF2wt/ΔNeh2 mice gave birth to homozygous mice with lower than expected frequency, accompanied by their increased embryonic lethality and visual signs of anemia. Mouse embryonic fibroblasts (MEFs) from NRF2ΔNeh2/ΔNeh2 homozygotes showed impaired resistance to oxidative stress compared to wild-type MEFs. The tissues of homozygous NRF2ΔNeh2/ΔNeh2 animals had a decreased expression of NRF2 target genes: NAD(P)H: Quinone oxidoreductase-1 (Nqo1); aldehyde oxidase-1 (Aox1); glutathione-S-transferase A4 (Gsta4); while the relative mRNA level of monocyte chemoattractant protein 1 (Ccl2), vascular cell adhesion molecule 1 (Vcam1) and chemokine Cxcl8 was increased. Thus, the resulting mutation in the Nfe2l2 gene partially impaired the function of this transcription factor, expanding the insights into the functional role of the unstructured N-terminus of NRF2. The obtained NRF2ΔNeh2 mouse line can be used as a model object for studying various pathologies associated with oxidative stress and inflammation.

Abstract PR011: Discovery of VVD-065, a first-in-class allosteric molecular glue of the Keap1-Cul3 E3-ligase complex for the treatment of NRF2-activated cancers

Abstract Somatic gain of function mutations in nuclear factor erythroid 2-related factor 2 (NRF2) transcription factor or loss of function mutations in Kelch-like ECH Associated Protein 1 (KEAP1) E3 ligase, which regulates NRF2 protein levels, are frequently identified in many solid cancers such as non-small cell lung cancer (NSCLC), esophageal squamous cell carcinoma (ESCC), and head and neck squamous cell carcinoma (HNSCC). These genomic alterations drive the activation of cytoprotective NRF2 transcriptional programs. In addition to mutational activation, NRF2 pathway activation has been documented with high frequency in patients without mutations in the pathway. Since tumor cells with hyperactivated NRF2 have been demonstrated to be dependent on this pathway for survival, targeting NRF2 represents an attractive therapeutic approach in tumors with aberrant NRF2 activation. Here, we report the identification of VVD-065, a first-in-class NRF2 inhibitor that acts via an unprecedented mechanism of action. Covalent modification of sensor cysteines on KEAP1 during electrophilic or oxidative stress is known to inhibit KEAP1 mediated NRF2 degradation. In complete contrast, covalent modification of a KEAP1 sensor cysteine by VVD-065 dramatically enhances NRF2 degradation. At low nM concentrations, VVD-065 covalently targets KEAP1 E3 ligase, and allosterically increases the affinity between KEAP1 and CUL3, thereby promoting the formation of active KEAP1-CUL3 E3 ligase complexes and increasing the rate of NRF2 degradation. VVD-065 profoundly reduces NRF2 protein levels in WT KEAP1/NRF2 settings, as well as various KEAP1 and NRF2 mutant settings. Consequently, VVD-065 substantially inhibits NRF2-dependent gene expression and proliferation of NRF2-dependent cell lines. In vivo, oral administration of VVD-065 results in robust degradation of NRF2 and decreased expression of NRF2 target genes. Tumor growth inhibition studies with cell-line derived, and patient derived NSCLC/ESCC xenograft (CDX/PDX) models revealed robust dose-dependent tumor growth inhibition and tumor regression in the absence of any overt toxicity. Since constitutive NRF2 activation often contributes to chemotherapeutic resistance, we also conducted TGI studies with 100+ PDX models to assess combination opportunities with chemotherapeutic agents. A marked combination response was achieved with cisplatin and nab-paclitaxel in various solid tumor types such as NSCLC, ESCC, HNSCC, and uterine cancers. Combination with chemotherapy was safe and well-tolerated in these mouse studies. In summary, we have identified VVD-065, a potent and selective KEAP1 activator that promotes the degradation of NRF2. Degradation of NRF2 led to robust monotherapy response in NRF2-activated cancers and also chemo-sensitized chemo-refractory tumors. A related molecule, acting through the same mechanism of action has now entered into Phase I clinical trials. Citation Format: Nil Roy, Tine Wyseure, I-Chung Lo, Jordon Inloes, Aaron Snead, Steffen Bernard, Justine Metzger, Jonathan Pollock, Stephanie Grabow, Christie Eissler, Melaminah Williams, Sarah Jacinto, Gabe Simon, Todd Kinsella, David Weinstein, Matt Patricelli. Discovery of VVD-065, a first-in-class allosteric molecular glue of the Keap1-Cul3 E3-ligase complex for the treatment of NRF2-activated cancers [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr PR011.

Nrf2 activator Diethyl Maleate attenuates ROS mediated NLRP3 inflammasome activation in murine microglia.

Microglia are the tissue-resident immune cells of the central nervous system. As a part of the innate immune response, NLR Family Pyrin Domain Containing Protein 3 (NLRP3) inflammasome activation leads to cleavage of caspase-1 and triggers secretion of proinflammatory cytokines and may also result in pyroptotic cell death. Inflammasome activation plays a crucial role in inflammatory conditions; aberrant activation of inflammasome contributes to the pathogenesis of neurodegenerative diseases. Diethyl Maleate (DEM) is a promising antiinflammatory chemical to alleviate inflammasome activation. In this study, NLRP3 inflammasome was activated in N9 murine microglia via 1µg/ml LPS (Lipopolysaccharide) for 4h and 5 mM ATP (Adenosine 5'-triphosphate) for 1h, respectively. We demonstrated that 1h pretreatment of DEM attenuated NLRP3 inflammasome activation in microglial cells. Besides, mitochondrial ROS decreased upon DEM pretreatment in inflammasome-induced cells. Likewise, it ameliorated pyroptotic cell death in microglia. DEM is a potent activator of Nrf2 transcription factor, the key regulator of the antioxidant response pathway. Nrf2 has been a significant target to decrease aberrant inflammasome activation through the antioxidant compounds, including DEM. Here, we have shown that DEM increased Nrf2 translocation to the nucleus, resulting in Nrf2 target gene expression in microglia. In conclusion, DEM is a promising protective agent against NLRP3 inflammasome activation.

Abstract 17696: Perm1 Stabilizes Nrf2 via Keap1 Oxidation to Protect the Heart Against Reperfusion Injury

Introduction: Reperfusion after ischemia (IR) produces reactive oxygen species (ROS) that promote myocardial injury. Nrf2 is a transcription factor that promotes transcription of antioxidant enzymes. Keap1 is a negative regulator of Nrf2. When oxidated by ROS, Keap1 releases Nrf2, leading to Nrf2 activation. Perm1 (PPARGC-1 and ESRR-induced regulator, muscle specific 1) is a scaffold or adaptor protein that maintains cellular metabolism. However, whether and how Perm1 protects the heart against IR injury via Nrf2 remains unknown. Methods: We used systemic Perm1 knockout (KO) mice and adeno-associated virus (AAV)-induced cardiac-specific Perm1 overexpression to investigate the pathological role of Perm1 in IR injury. Results: IR-induced myocardial infarction was greater in Perm1KO mice than in control mice. Consistently, infarction was smaller in mice with Perm1 overexpression (Infarction size/area at risk (AAR): AAV-GFP as a control 0.41 and AAV-Perm1 0.28*; p&lt;0.05). Myocardial oxidative stress, evaluated via increases in dityrosine, 4HNE and GSSG/GSH, after IR was greater in Perm1KO but less in Perm1 overexpression mice. Expression of IR-induced Nrf2 target genes, such as catalase, superoxide dismutase 2, heme oxygenase 1, NADH quinone dehydrogenase 1 and thioredoxin 1, was inhibited in Perm1KO but promoted in overexpression mice. The detrimental effects observed in Perm1KO mice were normalized by ML334, an inhibitor of Keap1-Nrf2 interaction (Infarction size/AAR: Wild 0.42; Perm1KO 0.58; Wild with ML334 0.37 and Perm1KO with ML334 0.42*; p&lt;0.05 vs. Perm1KO), suggesting that Perm1 protects the heart via Nrf2. In primary cultured rat cardiomyocytes, Perm1 was bound to Keap1 and promoted its oxidation, thereby stabilizing and activating Nrf2. Perm1-induced Nrf2 activation was verified with reporter gene assays using a consensus binding sequence of Nrf2, termed antioxidant response element. In an in vitro system using recombinant proteins, Perm1 directly bound to Keap1. Conclusions: These results suggest that Perm1 is a novel regulator of cellular redox homeostasis through Nrf2 activation via Keap1 oxidation that protects the heart against IR injury.

Wnt5a/Ror2 promotes Nrf2-mediated tissue protective function of astrocytes after brain injury.

Astrocytes, a type of glial cells, play critical roles in promoting the protection and repair of damaged tissues after brain injury. Inflammatory cytokines and growth factors can affect gene expression in astrocytes in injured brains, but signaling pathways and transcriptional mechanisms that regulate tissue protective functions of astrocytes are still poorly understood. In this study, we investigated the molecular mechanisms regulating the function of reactive astrocytes induced in mouse models of stab wound (SW) brain injury and collagenase-induced intracerebral hemorrhage (ICH). We show that basic fibroblast growth factor (bFGF), whose expression is up-regulated in mouse brains after SW injury and ICH, acts synergistically with inflammatory cytokines to activate E2F1-mediated transcription of a gene encoding the Ror-family protein Ror2, a receptor for Wnt5a, in cultured astrocytes. We also found that subsequent activation of Wnt5a/Ror2 signaling in astrocytes results in nuclear accumulation of antioxidative transcription factor Nrf2 at least partly by increased expression of p62/Sqstm1, leading to promoted expression of several Nrf2 target genes, including heme oxygenase 1. Finally, we provide evidence demonstrating that enhanced activation of Wnt5a/Ror2 signaling in astrocytes reduces cellular damage caused by hemin, a degradation product of hemoglobin, and promotes repair of the damaged blood brain barrier after brain hemorrhage.

Regulation of anti-inflammatory and antioxidant responses by methanol extract of Mikania cordata (Burm. f.) B. L. Rob. leaves via the inactivation of NF-κB and MAPK signaling pathways and activation of Nrf2 in LPS-induced RAW 264.7 macrophages

Mikania cordata (Burm. f.) B.L. Rob. has been traditionally used in tropical countries throughout Asia and Africa to treat gastric ulcers, dyspepsia, and dysentery. However, the mechanisms responsible for its anti-inflammatory and antioxidant activities are not fully understood. Therefore, this study sought to investigate the anti-inflammatory and antioxidant effects of methanol extracts of M. cordata (MMC) on inflammation and oxidative stress in lipopolysaccharide (LPS)-stimulated murine RAW 264.7 macrophages and elucidate its underlying regulatory mechanism. MMC significantly suppressed the production of nitric oxide (NO) and prostaglandin E2 (PGE2) in LPS-stimulated RAW 264.7 macrophages by downregulating the expression of inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2) at both the mRNA and protein levels. Moreover, MMC effectively reduced the mRNA expression levels and production of pro-inflammatory cytokines, including interleukin-6 (IL-6), IL-1β, and tumor necrosis factor-α (TNF-α). These suppressive effects of MMC on pro-inflammatory mediators and cytokines were mediated through the inhibition of transforming growth factor beta-activated kinase 1 (TAK1), which subsequently blocked the activation of nuclear factor-κB (NF-κB) and mitogen-activated protein kinases (MAPKs). MMC also upregulated the nuclear factor erythroid-2-related factor 2 (Nrf2) by inducing the degradation of Kelch-like ECH-related protein 1 (Keap1), an Nrf2-specific E3 ligase. Accordingly, MMC enhanced Nrf2 target gene expression of anti-oxidative regulators such as heme oxygenase-1 (HO-1) and NAD(P)H quinone oxidoreductase 1 (NQO1). However, it had minimal effect on the DPPH radical scavenging capacity in vitro. Collectively, these findings demonstrate that MMC holds promise as a potential therapeutic agent for alleviating inflammation-related diseases and oxidative stress.

Hepatocyte-specific deletion of small heterodimer partner protects mice against acetaminophen-induced hepatotoxicity via activation of Nrf2.

Acetaminophen (APAP) overdose stands as the primary cause of acute liver failure in the United States. APAP hepatotoxicity involves hepatic glutathione (GSH) depletion and mitochondrial damage. To counteract the toxicity of APAP, the nuclear factor erythroid 2 like 2 (Nrf2) activates the expression of genes responsible for drug detoxification and GSH synthesis. In this study, we present evidence that the elimination of hepatocyte small heterodimer partner, a critical transcriptional repressor for liver metabolism, results in Nrf2 activation and protects mice from APAP-induced acute liver injury. Initial investigations conducted on wildtype (WT) mice revealed a swift downregulation of Shp mRNA within the first 24 h after APAP administration. Subsequent treatment of hepatocyte-specific Shp knockout (ShpHep-/-) mice with 300 mg/kg APAP for 2 h exhibited comparable bioactivation of APAP with that observed in the WT controls. However, a significant reduction in liver injury was observed in ShpHep-/- after APAP treatment for 6 and 24 h. The decreased liver injury correlated with a faster recovery of GSH, attributable to heightened expression of Nrf2 target genes involved in APAP detoxification and GSH synthesis. Moreover, in vitro studies revealed that SHP protein interacted with NRF2 protein, inhibiting the transcription of Nrf2 target genes. These findings hold relevance for humans, as overexpression of SHP hindered APAP-induced NRF2 activation in primary human hepatocytes. In conclusion, our studies have unveiled a novel regulatory axis involving SHP and NRF2 in APAP-induced acute liver injury, emphasizing SHP as a promising therapeutic target in APAP overdose-induced hepatotoxicity.

AMPK-Mediated Phosphorylation of Nrf2 at S374/S408/S433 Favors Its βTrCP2-Mediated Degradation in KEAP1-Deficient Cells.

Nrf2 is a transcription factor facilitating cells' resilience against redox and various other forms of stress. In the absence of stressors, KEAP1 and/or βTrCP mediate the ubiquitination of Nrf2 and prevent Nrf2-dependent gene expression and detoxification. AMPK regulates cellular energy homeostasis and redox balance. Previous studies indicated a potential Nrf2-AMPK cooperativity. In line with this, our lab had previously identified three AMPK-dependent phosphorylation sites (S374/408/433) in Nrf2. Given their localization in or near the Neh6 domain, known to regulate βTrCP-mediated degradation, we examined whether they may influence the βTrCP-driven degradation of Nrf2. By employing expression plasmids for WT and triple mutant (TM)-Nrf2 (Nrf2S374/408/433→A), (co)immunoprecipitation, proximity ligation, protein half-life, knockdown, ubiquitination experiments, and qPCR in Keap1-null mouse embryonic fibroblasts, we show that TM-Nrf2S→A374/408/433 had enhanced stability due to impeded interaction with βTrCP2 and reduced ubiquitination in comparison to WT-Nrf2. In addition, TM-Nrf2 elicited higher expression of the Nrf2 target gene Gclc, potentiated in the presence of a pharmacological AMPK activator. Overall, we propose that AMPK-dependent phospho-sites of Nrf2 can favor its βTrCP2-mediated degradation and dampen the extent of Nrf2 target gene expression. Therefore, targeting AMPK might be able to diminish Nrf2-mediated responses in cells with overactive Nrf2 due to KEAP1 deficiency.

Inositol polyphosphate multikinase modulates redox signaling through nuclear factor erythroid 2-related factor 2 and glutathione metabolism

Maintenance of redox balance plays central roles in a plethora of signaling processes. Although physiological levels of reactive oxygen and nitrogen species are crucial for functioning of certain signaling pathways, excessive production of free radicals and oxidants can damage cell components. The nuclear factor erythroid 2-related factor 2 (Nrf2) signaling cascade is the key pathway that mediates cellular response to oxidative stress. It is controlled at multiple levels, which serve to maintain redox homeostasis within cells. We show here that inositol polyphosphate multikinase (IPMK) is a modulator of Nrf2 signaling. IPMK binds Nrf2 and attenuates activation and expression of Nrf2 target genes. Furthermore, depletion of IPMK leads to elevated glutathione and cysteine levels, resulting in increased resistance to oxidants. Accordingly, targeting IPMK may restore redox balance under conditions of cysteine and glutathione insufficiency.

Development of KEAP1-targeting PROTAC and its antioxidant properties: In vitro and in vivo

Oxidative stress due to abnormal accumulation of reactive oxygen species (ROS) is an initiator of a large number of human diseases, and thus, the elimination and prevention of excessive ROS are important aspects of preventing the development of such diseases. Nuclear factor erythroid 2-related factor 2 (NRF2) is an essential transcription factor that defends against oxidative stress, and its function is negatively controlled by Kelch-like ECH-associated protein 1 (KEAP1). Therefore, activating NRF2 by inhibiting KEAP1 is viewed as a strategy for combating oxidative stress-related diseases. Here, we generated a cereblon (CRBN)-based proteolysis-targeting chimera (PROTAC), which we named SD2267, that induces the proteasomal degradation of KEAP1 and leads to NRF2 activation. As was intended, SD2267 bound to KEAP1, recruited CRBN, and induced the degradation of KEAP1. Furthermore, the KEAP1 degradation efficacy of SD2267 was diminished by MG132 (a proteasomal degradation inhibitor) but not by chloroquine (an autophagy inhibitor), which suggested that KEAP1 degradation by SD2267 was proteasomal degradation-dependent and autophagy-independent. Following KEAP1 degradation, SD2267 induced the nuclear translocation of NRF2, which led to the expression of NRF2 target genes and attenuated ROS accumulation induced by acetaminophen (APAP) in hepatocytes. Based on in vivo pharmacokinetic study, SD2267 was injected intraperitoneally at 1 or 3 mg/kg in APAP-induced liver injury mouse model. We observed that SD2267 degraded hepatic KEAP1 and attenuated APAP-induced liver damage. Summarizing, we described the synthesis of a KEAP1-targeting PROTAC (SD2267) and its efficacy and mode of action in vitro and in vivo. The results obtained suggest that SD2267 could be used to treat hepatic diseases related to oxidative stress.

Characterizing evolutionary dynamics reveals strategies to exhaust the spectrum of subclonal resistance in EGFR-mutant lung cancer.

The emergence of resistance to targeted therapies restrains their efficacy. The development of rational-ly guided drug combinations could overcome this currently insurmountable clinical challenge. However, our limited understanding of the trajectories that drive the outgrowth of resistant clones in cancer cell populations precludes design of drug combinations to forestall resistance. Here, we propose an iterative treatment strategy coupled with genomic profiling and genome-wide CRISPR activation screening to systematically extract and define pre-existing resistant subpopulations in an EGFR-driven lung cancer cell line. Integrating these modalities identifies several resistance mechanisms, including activation of YAP/TAZ signaling by WWTR1 amplification, and estimated the associated cellular fitness for mathematical population modeling. These observations led to the development of a combina-tion therapy that eradicated resistant clones in large cancer cell line populations by exhausting the spectrum of genomic resistance mechanisms. However, a small fraction of cancer cells was able to enter a reversible non-proliferative state of drug tolerance. This sub-population exhibited mesenchy-mal properties, NRF2 target gene expression and sensitivity to ferroptotic cell death. Exploiting this induced collateral sensitivity by GPX4 inhibition clears drug tolerant populations and led to tumor cell eradication. Overall, this experimental in vitro data and theoretical modeling demonstrate why targeted mono- and dual therapies will likely fail in sufficiently large cancer cell populations to limit long-term efficacy. Our approach is not tied to a particular driver mechanism and can be used to systematically assess and ideally exhaust the resistance landscape for different cancer types to rationally design com-bination therapies.

LncRNA Tuna is activated in cadmium-induced placental insufficiency and drives the NRF2-mediated oxidative stress response.

Cadmium (Cd) is a toxic heavy metal found throughout the environment and one of the top ten toxicants of major public health concern identified by the World Health Organization. In utero Cd exposure causes fetal growth restriction, malformation, and spontaneous abortion; however, the mechanisms by which Cd impacts these outcomes are poorly understood. Cd accumulates in the placenta, suggesting that these negative outcomes may be a consequence of disrupted placental function and placental insufficiency. To understand the impact of Cd on gene expression within the placenta, we developed a mouse model of Cd-induced fetal growth restriction through maternal consumption of CdCl2 and performed RNA-seq on control and CdCl2 exposed placentae. The top differentially expressed transcript was the Tcl1 Upstream Neuron-Associated (Tuna) long non-coding RNA, which was upregulated over 25-fold in CdCl2 exposed placentae. Tuna has been shown to be critical for neural stem cell differentiation. However, within the placenta, there is no evidence that Tuna is normally expressed or functional at any developmental stage. To determine the spatial expression of Cd-activated Tuna within the placenta, we used in situ hybridization as well as placental layer-specific RNA isolation and analysis. Both methods confirmed the absence of Tuna expression in control samples and determined that Cd-induced Tuna expression is specific to the junctional zone. Since many lncRNAs regulate gene expression, we hypothesized that Tuna forms part of the mechanism of Cd-induced transcriptomic changes. To test this, we over-expressed Tuna in cultured choriocarcinoma cells and compared gene expression profiles to those of control and CdCl2 exposed cells. We demonstrate significant overlap between genes activated by Tuna overexpression and genes activated by CdCl2 exposure, with enrichment in the NRF2-mediated oxidative stress response. Herein we analyze the NRF2 pathway and show that Tuna increases NRF2/NRF2 both at the transcript and protein levels. Tuna drives increased NRF2 target gene expression, a result that is abrogated with the use of an NRF2 inhibitor, confirming that Tuna activates oxidative stress response genes through this pathway. This work identifies the lncRNA Tuna as a potential novel player in Cd-induced placental insufficiency.