Gamma-glutamylcysteine Synthetase Research Articles

Dihydromyricetin attenuates cisplatin-induced acute kidney injury by reducing oxidative stress, inflammation and ferroptosis

BackgroundCisplatin is effective against various types of cancers. However, its clinical application is limited owing to its adverse effects, especially acute kidney injury (AKI). Dihydromyricetin (DHM), a flavonoid derived from Ampelopsis grossedentata, has varied pharmacological activities. This research aimed to determine the molecular mechanism for cisplatin-induced AKI. MethodsA murine model of cisplatin-induced AKI (22 mg/kg, I.P.) and a HK-2 cell model of cisplatin-induced damage (30 μM) were established to evaluate the protective function of DHM. Renal dysfunction markers, renal morphology and potential signaling pathways were investigated. ResultsDHM decreased the levels of renal function biomarkers (blood urea nitrogen and serum creatinine), mitigated renal morphological damage, and downregulated the protein levels of kidney injury molecule-1 and neutrophil gelatinase-associated lipocalin. It upregulated the expression levels of antioxidant enzymes (superoxide dismutase and catalase expression), nuclear factor-erythroid-2-related factor 2 (Nrf2) and its downstream proteins, including heme oxygenase-1 (HO-1), glutamate-cysteine ligase catalytic (GCLC) and modulatory (GCLM) subunits, thus eventually reducing cisplatin-induced reactive oxygen species (ROS) production. Moreover, DHM partially inhibited the phosphorylation of the active fragments of caspase-8 and -3 and mitogen-activated protein kinase and restored glutathione peroxidase 4 expression, which attenuated renal apoptosis and ferroptosis in cisplatin-treated animals. DHM also mitigated the activation of NLRP3 inflammasome and nuclear factor (NF)-κB, attenuating the inflammatory response. In addition, it reduced cisplatin-induced HK-2 cell apoptosis and ROS production, both of which were blocked by the Nrf2 inhibitor ML385. ConclusionsDHM suppressed cisplatin-induced oxidative stress, inflammation and ferroptosis probably through regulating of Nrf2/HO-1, MAPK and NF-κB signaling pathways.

REST contributes to AKI-to-CKD transition through inducing ferroptosis in renal tubular epithelial cells.

Ischemic-reperfusion injury (IRI) is a major pathogenic factor in acute kidney injury (AKI), which directly leads to the hypoxic injury of renal tubular epithelial cells (RTECs). Although emerging studies suggest repressor element 1-silencing transcription factor (REST) as a master regulator of gene repression under hypoxia, its role in AKI remains elusive. Here, we found that REST was upregulated in AKI patients, mice, and RTECs, which was positively associated with the degree of kidney injury, while renal tubule-specific knockout of Rest significantly alleviated AKI and its progression to chronic kidney disease (CKD). Subsequent mechanistic studies indicated that suppression of ferroptosis was responsible for REST-knockdown-induced amelioration of hypoxia-reoxygenation injury, during which process Cre-expressing adenovirus-mediated REST downregulation attenuated ferroptosis through upregulating glutamate-cysteine ligase modifier subunit (GCLM) in primary RTECs. Further, REST transcriptionally repressed GCLM expression via directly binding to its promoter region. In conclusion, our findings revealed the involvement of REST, a hypoxia regulatory factor, in AKI-to-CKD transition and identified the ferroptosis-inducing effect of REST, which may serve as a promising therapeutic target for ameliorating AKI and its progression to CKD.

Polymorphisms of the GCLC Gene Are Novel Genetic Markers for Susceptibility to Psoriasis Associated with Alcohol Abuse and Cigarette Smoking.

The aim of this pilot study was to investigate whether single nucleotide polymorphisms (SNP) in the gene encoding the catalytic subunit of glutamate cysteine ligase (GCLC) are associated with the risk and clinical features of psoriasis. A total of 944 unrelated individuals, including 474 patients with a diagnosis of psoriasis and 470 healthy controls, were recruited for the study. Six common SNPs in the GCLC gene were genotyped using the MassArray-4 system. Polymorphisms rs648595 (OR = 0.56, 95% CI 0.35-0.90; Pperm = 0.017) and rs2397147 (OR = 0.54, 95% CI 0.30-0.98; Pperm = 0.05) were associated with susceptibility to psoriasis in males. In the male group, diplotype rs2397147-C/C × rs17883901-G/G was associated with a decreased risk of psoriasis (FDR-adjusted p = 0.014), whereas diplotype rs6933870-G/G × rs17883901-G/G (FDR-adjusted p = 0.045) showed an association with an increased disease risk in females. The joint effects of SNPs with tobacco smoking (rs648595 and rs17883901) and alcohol abuse (rs648595 and rs542914) on psoriasis risk were observed (Pperm ≤ 0.05). We also found multiple sex-independent associations between GCLC gene polymorphisms and various clinical features such as earlier disease onset, the psoriatic triad, and specific localizations of skin lesions. The present study is the first to show that polymorphisms of the GCLC gene are significantly associated with the risk of psoriasis and related to its clinical features.

Alliin enriched standardized fraction of Allium hookeri regulates the glucose homeostasis via upregulating hepatic glutathione pool

IntroductionAllium hookeri is a source of organosulfur compounds including alliin which is an antihyperglycemic phytochemical. PurposeThis study tested the effect of methanolic extract (ME) of A. hookeri on glucose uptake and glutathione biosynthesis using sodium palmitate (0.75 mM) induced insulin resistant cultured hepatocytes. MethodThe plant extract was prepared following standard protocol followed by bioactivity- guided fractionation. The plant extract and fractions were tested for glucose uptake assay, cellular glutathione level. Further, immunoblotting study was carried out to check the protein expression of the genes involved in glutathione biosynthesis and glucose metabolism. ResultsBioactivity-guided fractionation showed that the aqueous fraction from the methanolic A. hookeri extract (ME) was rich in alliin and the alliin-enriched standardized fraction (EFr) appeared to regulate glucose homeostasis as the cellular glutathione pool in the palmitate treated hepatocytes remained unaltered. Alteration in cellular glutathione level affects glucose homeostasis. We also observed that expressions of glutamate cysteine ligase (GCLC), glutathione reductase (GR), genes involved in hepatic glutathione biosynthesis were downregulated in palmitate and upregulated in EFr treated hepatocytes. GLUT2 protein expression was upregulated in the palmitate treated and downregulated in the EFr treated hepatocytes, but no change was observed in the protein expression of the gene glutathione synthase (GS). ConclusionsOur results show that EFr of A. hookeri leaves may be a potent botanical drug against type2 diabetes due to its role in the regulation of hepatic glutathione pool.

(090) Hydrogen Sulfide Therapy Stimulates Cellular Antioxidant Defense and Reverses Erectile Dysfunction in Western Diet-fed Mice

Abstract Introduction Hydrogen sulfide (H2S) is an endogenously produced gaseous cellular signaling molecule with vasodilatory, anti-inflammatory, and antioxidant-like properties. H2S is thought to protect against oxidative stress through activation of transcription factor(s) that transcribe genes involved cellular detoxification and antioxidant defense. We have previously used a Western diet (WD) high in fat and sugar to induce erectile dysfunction (ED) in rodents, in which excessive penile reactive oxygen species (ROS) have been implicated in ED pathogenesis. We have recently observed a reduction in protein content and activity of cystathionine γ-lyase, a major enzymatic source of H2S, in the corpus cavernosum of mice fed the WD for 12 weeks. Objective The objective of this study was to determine if chronic consumption of an orally active, slow releasing H2S prodrug (SG1002) can restore erectile function and alleviate WD-induced penile redox burden. Methods Young male C57Bl/6J mice (n = 120) were fed a control diet (CD) or WD ad libitum for 18 weeks. For the final six weeks of the dietary intervention, half of the mice were switched to an equivalent diet containing SG1002 at a concentration designed to deliver approximately 20 mg/kg/day. Following the intervention, erectile function was assessed by measuring intracavernosal pressure (ICP) and mean arterial pressure (MAP) during cavernous nerve stimulation (1, 2, 4 volts). In separate mice, in vivo ROS production was measured in the penis utilizing a microdialysis approach. Microdialysis probes were inserted into the penis of anesthetized mice and perfused with saline containing 100 μM Amplex Ultrared, 1 U/ml horseradish peroxidase, and 10 U/ml superoxide dismutase. ROS convert the reagents to a fluorescent byproduct resorufin, which was measured in the outflowing dialysate. In separate mice, naïve corpus cavernosum tissue was harvested for quantitative expression of 18 genes related to cellular antioxidant defense by qRT-PCR. Significant differences between groups were determined by two-way ANOVA with Tukey’s multiple comparisons post-hoc analysis, with an alpha level of 0.05. Results Erectile function was significantly impaired in the untreated WD-fed mice (CD: 64.8±8.4 vs. WD: 27.1±2.3; cumulative ICP area/MAP; p<0.01), while SG1002 induced a 74% functional restoration in WD mice (WD+SG1002: 51.0±2.8; p<0.05 vs. WD). Penile production of the ROS hydrogen peroxide and superoxide were elevated in the WD mice (CD: 0.71±0.07 vs. WD: 1.09 ±0.15; p<0.01), which were normalized by SG1002 treatment (WD+SG1002: 0.83±0.07; p<0.01 vs. WD). SG1002 had a positive stimulatory effect (p<0.05) on expression of ten of the antioxidant genes, including catalase, glutamate-cysteine ligase (gclc), glutathione peroxidase 1, glutathione peroxidase 4, peroxiredoxin 3, peroxiredoxin 5, thioredoxin reductase 1, heme oxygenase 1, sirtuin 1, and sirtuin 3. Conclusions H2S therapy with chronic SG1002 administration provides protection to the corpus cavernosum against an excessive ROS burden induced by the high-fat/high-sugar environment of the Western diet, likely through augmentation of the cellular antioxidant defense system. H2S therapy may be a promising strategy for treatment of early stage, obesity-associated erectile dysfunction. Disclosure No

Protective effects of ferulic acid against ionizing radiation-induced oxidative damage in rat lens through activating Nrf2 signal pathway.

To examine the protection of ferulic acid (FA) against ionizing radiation (IR)-induced lens injury in rats, as well as the underlying mechanisms. FA (50 mg/kg) was administered to rats for 4 consecutive days before they were given 10 Gy γ-radiation, as well as for 3 consecutive days afterward. Two weeks after radiation, the eye tissues were collected. Histological alterations were evaluated by hematoxylin-eosin staining. Enzyme linked immunosorbent assay (ELISA) was utilized to assess the activities of glutathione reductase (GR) and superoxide dismutase (SOD), as well as the levels of glutathione (GSH) and malondialdehyde (MDA) in the lenses. The protein and mRNA levels of Bcl-2, caspase-3, Bax, heme oxygenase-1 (HO-1), and glutamate-cysteine ligase catalytic subunit (GCLC) were quantified using Western blot and quantitative reverse transcription polymerase chain reaction, respectively. With nuclear extracts, the nuclear factor erythroid-2 related factor (Nrf2) protein expressions in the nuclei were also measured. Rats exposed to IR showed lens histological alterations which could be alleviated by FA. FA treatment reversed apoptosis-related markers in IR-induced lens, as evidenced by lower levels of Bax and caspase-3 and higher level of Bcl-2. Furthermore, IR induced oxidative damage manifested by decreased GSH level, increased MDA level, and decreased SOD and GR activities. FA boosted nuclear translocation of Nrf2 and increased the expressions of HO-1 and GCLC to inhibit oxidative stress, as evidenced by an increase in GSH, a decrease in MDA, and an increase in GR and SOD activities. FA may work well in preventing and treating IR-induced cataract through promoting the Nrf2 signal pathway to attenuate oxidative damage and cell apoptosis.

Immunisation with Transgenic L. tarentolae Expressing Gamma Glutamyl Cysteine Synthetase from Pathogenic Leishmania Species Protected against L. major and L. donovani Infection in a Murine Model.

Leishmaniasis is a protozoan disease responsible for significant morbidity and mortality. There is no recommended vaccine to protect against infection. In this study, transgenic Leishmania tarentolae expressing gamma glutamyl cysteine synthetase (γGCS) from three pathogenic species were produced and their ability to protect against infection determined using models of cutaneous and visceral leishmaniasis. The ability of IL-2-producing PODS® to act as an adjuvant was also determined in L. donovani studies. Two doses of the live vaccine caused a significant reduction in L. major (p < 0.001) and L. donovani (p < 0.05) parasite burdens compared to their respective controls. In contrast, immunisation with wild type L. tarentolae, using the same immunisation protocol, had no effect on parasite burdens compared to infection controls. Joint treatment with IL-2-producing PODS® enhanced the protective effect of the live vaccine in L. donovani studies. Protection was associated with a Th1 response in L. major and a mixed Th1/Th2 response in L. donovani, based on specific IgG1 and IgG2a antibody and cytokine production from in vitro proliferation assays using antigen-stimulated splenocytes. The results of this study provide further proof that γGCS should be considered a candidate vaccine for leishmaniasis.

Cystine/Glutamate Xc- Antiporter Induction Compensates for Transsulfuration Pathway Repression by 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) to Ensure Cysteine for Hepatic Glutathione Biosynthesis.

Exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) has been associated with the induction of oxidative stress and the progression of steatosis to steatohepatitis with fibrosis. It also disrupts metabolic pathways including one-carbon metabolism (OCM) and the transsulfuration pathway with possible consequences on glutathione (GSH) levels. In this study, complementary RNAseq and metabolomics data were integrated to examine the hepatic transsulfuration pathway and glutathione biosynthesis in mice following treatment with TCDD every 4 days for 28 days. TCDD dose-dependently repressed hepatic cystathionine β-synthase (CBS) and cystathionine γ-lyase (CTH) mRNA and protein levels. Reduced CBS and CTH levels are also correlated with dose-dependent decreases in hepatic extract hydrogen sulfide (H2S). In contrast, cysteine levels increased consistent with the induction of Slc7a11, which encodes for the cystine/glutamate Xc- antiporter. Cotreatment of primary hepatocytes with sulfasalazine, a cystine/glutamate Xc- antiporter inhibitor, decreased labeled cysteine incorporation into GSH with a corresponding increase in TCDD cytotoxicity. Although reduced and oxidized GSH levels were unchanged following treatment due to the induction of GSH/GSSG efflux transporter by TCDD, the GSH:GSSG ratio decreased and global protein S-glutathionylation levels in liver extracts increased in response to oxidative stress along with the induction of glutamate-cysteine ligase catalytic subunit (Gclc), glutathione synthetase (Gss), glutathione disulfide reductase (Gsr), and glutathione transferase π (Gstp). Furthermore, levels of ophthalmic acid, a biomarker of oxidative stress indicating GSH consumption, were also increased. Collectively, the data suggest that increased cystine transport due to cystine/glutamate Xc- antiporter induction compensated for decreased cysteine production following repression of the transsulfuration pathway to support GSH synthesis in response to TCDD-induced oxidative stress.

Mechanisms of Yajieshaba in the treatment of liver fibrosis through the Keap1-Nrf2 signaling pathway.

Yajieshaba (YJSB), a traditional Dai medicine formula containing botanical drugs, is commonly employed in Yunnan due to its significant therapeutic effects on liver protection. Consequently, to determine the efficacy of YJSB and the mechanism of action of Kelch-like ECH-associated protein 1 (Keap1)-nuclear factor erythroid 2-related factor 2 (Nrf2) pathway against liver fibrosis. We wanted to see if YJSB could treat CCl4-induced liver fibrosis by regulating the Keap1-Nrf2 signaling pathway. YJSB significantly improved liver function biochemical indices, liver fibrosis quadruple, hydroxyproline (Hyp), and transforming growth factor-β1 (TGF-β1) levels. The staining results demonstrated that the degree of liver fibrosis was significantly reduced. YJSB reduced the content of malondialdehyde (MDA) and elevated the content of superoxide dismutase (SOD) in the liver, exhibiting antioxidant effects; meanwhile, it regulated the expression of Keap1-Nrf2 pathway protein, increased the expression of NAD(P)H: Quinone oxidoreductase (NQO1), Heme Oxygenase 1 (HO-1), Glutamate cysteine ligase modifier subunit (GCLM), and Glutamate cysteine ligase catalytic subunit (GCLC) expression in the liver decreased while Nrf2 expression increased. Fluorescence immunoassay studies demonstrated that YJSB promoted the trans-nuclearization of Nrf2. YJSB possesses anti-liver fibrosis pharmacological effects that improve liver function and effectively counteract CCl4-induced liver fibrosis damage. The mechanism of action might be related to the regulation of protein expression of the Keap1-Nrf2 pathway, increasing the ability of the body to resist oxidative stress and reduce oxidative stress injury.

The interplay between tauopathy and aging through interruption of UPR/Nrf2/autophagy crosstalk in the Alzheimer’s disease transgenic experimental models

Purpose Alzheimer’s disease (AD) is the most common form of tauopathy that usually occursduring aging and unfolded protein response (UPR), oxidative stress and autophagy play a crucialrole in tauopathy-induced neurotoxicity. The aim of this study was to investigate the effects oftauopathy on normal brain aging in a Drosophila model of AD. Method We investigated the interplay between aging (10, 20, 30, and 40 days) and human tauR406W (htau)-induced cell stress in transgenic fruit flies. Results Tauopathy caused significant defects in eye morphology, a decrease in motor function and olfactory memory performance (after 20 days), and an increase in ethanol sensitivity (after 30 days). Our results showed a significant increase in UPR (GRP78 and ATF4), redox signalling (p-Nrf2, total GSH, total SH, lipid peroxidation, and antioxidant activity), and regulatory associated protein of mTOR complex 1 (p-Raptor) activity in the control group after 40 days, while the tauopathy model flies showed an advanced increase in the above markers at 20 days of age. Interestingly, only the control flies showed reduced autophagy by a significant decrease in the autophagosome formation protein (dATG1)/p-Raptor ratio at 40 days of age. Our results were also confirmed by bioinformatic analysis of microarray data from tauPS19 transgenic mice (3, 6, 9, and 12 months), in which tauopathy increased expression of heme oxygenase 1, and glutamate-cysteine ligase catalytic subunit and promote aging in transgenic animals. Conclusions Overall, we suggest that the neuropathological effects of tau aggregates may be accelerated brain aging, where redox signaling and autophagy efficacy play an important role.

Docosahexaenoic Acid Alleviates Trimethylamine-N-oxide-mediated Impairment of Neovascularization in Human Endothelial Progenitor Cells

Background: Human endothelial progenitor cells (hEPCs), originating from hemangioblasts in bone marrow (BM), migrate into the blood circulation, differentiate into endothelial cells, and could act as an alternative tool for tissue regeneration. In addition, trimethylamine-N-oxide (TMAO), one of the gut microbiota metabolites, has been identified as an atherosclerosis risk factor. However, the deleterious effects of TMAO on the neovascularization of hEPCs have not been studied yet. Results: Our results demonstrated that TMAO dose-dependently impaired human stem cell factor (SCF)-mediated neovascularization in hEPCs. The action of TMAO was through the inactivation of Akt/endothelial nitric oxide synthase (eNOS), MAPK/ERK signaling pathways, and an upregulation of microRNA (miR)-221. Docosahexaenoic acid (DHA) could effectively inhibit the cellular miR-221 level and induce the phosphorylation level of Akt/eNOS, MAPK/ERK signaling molecules, and neovascularization in hEPCs. DHA enhanced cellular amounts of reduced form glutathione (GSH) through an increased expression of the gamma-glutamylcysteine synthetase (γ-GCS) protein. Conclusions: TMAO could significantly inhibit SCF-mediated neovascularization, in part in association with an upregulation of miR-221 level, inactivation of Akt/eNOS and MAPK/ERK cascades, suppression of γ-GCS protein, and decreased levels of GSH and GSH/GSSG ratio. Furthermore, the DHA could alleviate the detrimental effects of TMAO and induce neovasculogenesis through suppression of miR-221 level, activation of Akt/eNOS and MAPK/ERK signaling cascades, increased expression of γ-GCS protein, and increment of cellular GSH level and GSH/GSSG ratio in hEPCs.

Toxicity attenuation processing technology and mechanism of Rhizoma Dioscoreae Bulbiferae stir-fried with Paeoniae Radix Alba decoction

This study explored toxicity attenuation processing technology of Rhizoma Dioscoreae Bulbiferae stir-fried with Paeoniae Radix Alba decoction for the first time, and further explored its detoxification mechanism. Nine processed products of Rhizoma Dioscoreae Bulbiferae stir-fried with Paeoniae Radix Alba decoction were prepared by orthogonal experiment with three factors and three levels. Based on the decrease in the content of the main hepatotoxic component diosbulbin B before and after processing of Rhizoma Dioscoreae Bulbiferae by high-performance liquid chromatography, the toxicity attenuation technology was preliminarily screened out. On this basis, the raw and representative processed products of Rhizoma Dioscoreae Bulbiferae were given to mice by gavage with 2 g·kg~(-1)(equival to clinical equivalent dose) for 21 d. The serum and liver tissues were collected after the last administration for 24 h. The serum biochemical indexes reflecting liver function and liver histopathology were combined to further screen out and verify the proces-sing technology. Then, the lipid peroxidation and antioxidant indexes of liver tissue were detected by kit method, and the expressions of NADPH quinone oxidoreductase 1(NQO1) and glutamate-cysteine ligase(GCLM) in mice liver were detected by Western blot to further explore detoxification mechanism. The results showed that the processed products of Rhizoma Dioscoreae Bulbiferae stir-fried with Paeoniae Radix Alba decoction reduced the content of diosbulbin B and improved the liver injury induced by Rhizoma Dioscoreae Bul-biferae to varying degrees, and the processing technology of A_2B_2C_3 reduced the excessive levels of alanine transaminase(ALT) and aspartate transaminase(AST) induced by raw Rhizoma Dioscoreae Bulbiferae by 50.2% and 42.4%, respectively(P&lt;0.01, P&lt;0.01). The processed products of Rhizoma Dioscoreae Bulbiferae stir-fried with Paeoniae Radix Alba decoction reversed the decrease protein expression levels of NQO1 and GCLM in the liver of mice induced by raw Rhizoma Dioscoreae Bulbiferae to varying degrees(P&lt;0.05 or P&lt;0.01), and it also reversed the increasing level of malondialdehyde(MDA) and the decreasing levels of glutathione(GSH), glutathione peroxidase(GPX), and glutathione S-transferase(GST) in the liver of mice(P&lt;0.05 or P&lt;0.01). In summary, this study shows that the optimal toxicity attenuation processing technology of Rhizoma Dioscoreae Bulbiferae stir-fried with Paeoniae Radix Alba decoction is A_2B_2C_3, that is, 10% of Paeoniae Radix Alba decoction is used for moistening Rhizoma Dioscoreae Bulbiferae and processed at 130 ℃ for 11 min. The detoxification mechanism involves enhancing the expression levels of NQO1 and GCLM antio-xidant proteins and related antioxidant enzymes in the liver.

Protective Effect of Chinese Bayberry (Myrica rubra Sieb. et Zucc.) Pomace Wine on Oxidative Stress of Hydrogen Peroxide by Regulating Keap1/Nrf2 Pathway in HepG2 Cells.

Chinese bayberry (Myrica rubra Sieb. et Zucc.) pomace wine (CPW) is fruity and rich in bioactive compounds, with high nutritional value and antioxidant activities. This study aims to investigate the protective effect of CPW on the oxidative damage induced by hydrogen peroxide in human hepatocellular carcinoma (HepG2) cells and CPW's possible underlying mechanism. The fluorescence assay results revealed that CPW pre-treatment inhibited intracellular reactive oxygen species (ROS) accumulation in H2O2-induced HepG2 cells and cell membrane injury. Meanwhile, CPW remarkably enhanced the activity of antioxidant enzymes including superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), and the content of glutathione (GSH). Moreover, CPW pretreatment significantly regulated the expression of Kelch-like ECH-associated protein 1 (Keap1)/nuclear factor erythroid 2-related factor 2 (Nrf2) pathway-associated genes (Keap1, Nrf2, NADPH quinone oxidoreductase I (NQO1), and heme oxygenase-1 (HO-1)) and its downstream antioxidant genes (SOD, CAT, GSH, and the glutamate-cysteine ligase catalytic (GCLC) subunit) in HepG2 cells. These data demonstrated that CPW prevented H2O2-induced oxidative stress by regulating the Keap1/Nrf2 signaling pathway.

α-Synuclein Attenuates Maneb Neurotoxicity through the Modulation of Redox-Sensitive Transcription Factors.

The accumulation and aggregation of α-synuclein is a pathognomonic sign of Parkinson's disease (PD). Maneb (MB) exposure has also been reported as one environmental triggering factor of this multifactorial neurodegenerative disease. In our laboratory, we have previously reported that mild overexpression of α-synuclein (200% increase with respect to endogenous neuronal levels) can confer neuroprotection against several insults. Here, we tested the hypothesis that α-synuclein can modulate the neuronal response against MB-induced neurotoxicity. When exposed to MB, cells with endogenous α-synuclein expression displayed increased reactive oxygen species (ROS) associated with diminished glutamate-cysteine ligase catalytic subunit (GCLc) and hemeoxygenase-1 (HO-1) mRNA expressions and upregulation of the nuclear factor erythroid 2-related factor 2 (NRF2) repressor, BTB domain and CNC homolog 1 (BACH1). We found that α-synuclein overexpression (wt α-syn cells) attenuated MB-induced neuronal damage by reducing oxidative stress. Decreased ROS found in MB-treated wt α-syn cells was associated with unaltered GCLc and HO-1 mRNA expressions and decreased BACH1 expression. In addition, the increased SOD2 expression and catalase activity were associated with forkhead box O 3a (FOXO3a) nuclear compartmentalization. Cytoprotective effects observed in wt α-syn cells were also associated with the upregulation of silent information regulator 1 (SIRT1). In control cells, MB-treatment downregulated glutathione peroxidase 4 mRNA levels, which was coincident with increased ROS content, lipid peroxidation, and mitochondrial alterations. These deleterious effects were prevented by ferrostatin-1, an inhibitor of ferroptosis, under conditions of endogenous α-synuclein expression. The overexpression of α-synuclein attenuated MB toxicity by the activation of the same mechanisms as ferrostatin-1. Overall, our findings suggest that mild overexpression of α-synuclein attenuates MB-induced neurotoxicity through the modulation of NRF2 and FOXO3a transcription factors and prevents cell death probably by intervening in mechanisms associated with ferroptosis. Thus, we postulate that early stages of α-synuclein overexpression could be potentially neuroprotective against MB neurotoxicity.

Simulation modeling of glutamate cysteine ligase activity

L-Y-glutamyl-L-cysteinyl glycine, or glutathione, as one of the basic intracellular antioxidants, plays a vital role in cellular metabolism. In mammalian cells, glutathione is synthesized via two steps. The first step that is considered rate limiting is catalyzed by glutamate cysteine ligase. In this work, a stochastic algorithm based on continuous-time Markov chains was used to simulate the activity of glutamate-cysteine ligase. Several different mechanisms of enzymatic activity including reversible inhibition of glutathione, and an ATP binding motif have been considered. Based on physiological metabolite measurements made for human erythrocytes, the activity of glutamate cysteine ligase was determined. There are many possible ways for substrates to bind to an active site of the studied enzyme, but, only the mechanism by which primary binding to ATP can occur makes it possible to obtain the catalytic rate value similar to that of the experimentally measured glutamatecysteine ligase activity relative to physiological concentrations of substrates. In other cases, the values differ by more than one order of magnitude. The performed analysis allows the conclusion that when models for glutathione biosynthesis are constructed in vivo conditions, the ATP concentration and reversible inhibition of glutathione should be taken into account.

Abstract 4886: PARP-1 and γ-GCS inhibitors enhance platinum sensitivity in ovarian cancer

Abstract Background: Ovarian cancer is the most important cause of gynaecological cancer-related mortality globally. Approximately 80% of patients are diagnosed with advanced stage (FIGO stage III-IV) of ovarian cancer. The standard treatment approach for advanced EOC is primary debulking surgery followed by adjuvant chemotherapy using taxanes plus platinum. Resistance to platinum based chemo remains a key reason for treatment failure in advanced epithelial ovarian cancer (EOC). Therapeutic efficacy of Poly [ADP-ribose] polymerase 1 (PARP1) and Gamma-glutamyl cysteine Synthetase (γ-GCS)inhibitors in ovarian cancer remains undefined, either as a single agent or in combination with cisplatin. Material and Methods: We determined the combined effect of PJ34 (PARP1 inhibitor) and BSO (Buthionine-sulfoximine- (γ-GCS inhibitor) with cisplatin in ovarian cancer cell lines (OVSAHO, KURAMOCHI, and IGROV1) by MTT assay. PARP1 and GCS levels were analyzed by western blotting. We employed flow cytometry for cell cycle analysis as well as for apoptosis studies. Analysis was done using Graph Pad Prism-6. Results were considered to be statistically significant when p value was &amp;lt; 0.05. Results and Conclusion: Combination of cisplatin with PJ34 and BSO augmented cisplatin toxicity in vitro by decreasing cell proliferation and enhancing cell cycle block and cell death when compared with either single agent. A significant cell death (p= &amp;lt;0.05) was observed with the combination of cisplatin, BSO and PJ34. Conclusion: In conclusion, our study provide experimental evidence on the combined effect of PARP-1 and GCS inhibition on CDDP-induced cytotoxicity in epithelial ovarian cancer cells. We propose that PARP-1and BSO inhibitors can be combined with cytotoxic chemotherapeutic agents such as CDDP to enhance the cytotoxicity of chemotherapeutic agents and inhibit key signalling pathways involved in cell proliferation and apoptosis. Future comprehensive studies are needed to demonstrate further validation of above combination. Keywords: Ovarian Cancer, cisplatin, PARP-1, PJ34, γ -GCS, β-actin, Glutathione. Abbreviations: Epithelial Ovarian Cancer (EOC), cisplatin (CDDP), Glutathione (GSH), Gamma Glutamyl Cysteine Synthetase (γ-GCS), Poly (ADP ribosyl) polymerase-1 (PARP1), Nucleotide excision repair (NER),homologous repair (HR), Enzyme-linked immunosorbent assay (ELISA), Buthionine Sulfoximine (BSO), Quantitative Polymerase Chain Reaction (qPCR), Peripheral Blood (PB). Propidium Iodide(PI). Citation Format: Luxmi Devi, Ashok Sharma, Lalit Kumar. PARP-1 and γ-GCS inhibitors enhance platinum sensitivity in ovarian cancer. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4886.

Abstract 6038: KDM2B regulates Serine-Glycine-One Carbon (SGOC) metabolism by targeting the SGOC enzyme genes via a combination of direct and indirect epigenetic mechanisms

Abstract Our earlier studies had shown that overexpression of the JmjC domain histone demethylase KDM2B renders mouse embryo fibroblasts (MEFs) resistant to oxidative stress due to the role of KDM2B in the regulation of antioxidant mechanisms. Here we present evidence that the knockdown of KDM2B in basal-like breast cancer cell lines results in a decrease of Glutathione (GSH) levels, a secondary increase of intracellular ROS levels and in enhanced sensitivity to deubiquitinase inhibitors. The expression of the Glutamate-Cystine antiporter, the Glutamate-Cysteine Ligase GCLC/GCLM and the Glutathione Peroxidase GPX4, all of which regulate GSH abundance was not affected. To address the mechanism of the GSH regulation we carried out RNA-Seq, quantitative proteomics and metabolomics analyses in shKDM2B- and empty vector-transduced MDA-MB-231 cells. The results showed that the KD of KDM2B causes major shifts in metabolism and that one of the metabolic pathways whose activity depends on KDM2B is the SGOC pathway, which has a major role in GSH biosynthesis. Experiments in cultured cells confirmed the importance of KDM2B in the regulation of this pathway and they also showed that the inhibition of the pathway via the KD of KDM2B is partly responsible for the shKDM2B-induced inhibition of cell proliferation in culture and in xenograft experiments in NSG mice. More important, the transcriptomic signature of the SGOC pathway correlates with the expression of KDM2B in basal like mammary adenocarcinomas in the TCGA database. The genes encoding the majority of the enzymes in the SGOC pathway are known to be regulated by MYC and ATF4 and our data show that both MYC and ATF4 are under the regulatory control of KDM2B. ATAC-Seq and ChIP-Seq experiments in shKDM2B and control MDA-MB-231 cells also showed that KDM2B binds the promoter region of not only MYC and ATF4, but also of the genes encoding the SGOC enzymes and that it regulates chromatin accessibility and the abundance of H3K4me3/H3K27Ac active histone marks in these promoters. Overall, our data indicate that KDM2B regulates the SGOC pathway by targeting MYC and ATF4 and by making the promoters of the genes encoding the SGOC enzymes accessible to these regulators. Overall, our data provide new evidence on SGOC regulation, and identify novel KDM2B-dependent metabolic vulnerabilities in basal like breast cancer. Citation Format: Evangelia Chavdoula, Vollter Anastas, Allesandro La Ferlita, Julian Aldana, Giuseppe Carota, Mariarita Spampinato, Sameer Parashar, Ilaria Cosentini, Burak Soysal, Giovanni Nigita, Michael Freitas, Philip Tsichlis. KDM2B regulates Serine-Glycine-One Carbon (SGOC) metabolism by targeting the SGOC enzyme genes via a combination of direct and indirect epigenetic mechanisms. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6038.

Abstract 1088: Acquired radiation resistance induces thiol-dependent cisplatin cross-resistance

Abstract Purpose. Resistance to radiation, both intrinsic and acquired, remains a significant clinical challenge. It is therefore import to identify the underlying molecular and cellular features involved in this resistance. Materials and Methods. We generated genetically-matched counterparts of various degrees of radiation sensitivity in non-small cell lung carcinoma (NSCLC) tumor models to define characteristics of acquired resistance through repeated exposures to conventional X-ray radiation. Results. As assessed by cell viability and clonogenic assays murine Lewis lung carcinoma (LLC) and human A549 cell lines acquired an approximate 1.5 - 2-fold increase in radiation resistance (RR) as compared to its parental counterpart. Morphologically, we found that A549-RR exhibited a greater nucleus-to-cytosol (N/C) ratio as compared to its respective counterpart. Since the N/C ratio has been linked to the differentiation state, we next investigated the epithelial-to-mesenchymal transition (EMT) phenotype and cellular plasticity. We found that A549 have a greater radiation-induced plasticity, as measured by E-cadherin, vimentin and double positive (DP) modulation, as compared to LLC. Additionally, migration was suppressed in A549-RR, as compared to A549. Subsequently, we confirmed that the LLC-RR and A549-RR are also more resistant to radiotherapy than their isogenic-matched counterpart in vivo. Remarkably, we found that the acquired radiation resistance also induced resistance to first-line chemotherapeutic cisplatin, but not carboplatin or oxaliplatin. This cross-resistance was attributed to induced elevated thiol levels. Decreasing the amount of thiols with buthionine sulfoximine (BSO), a gamma-glutamylcysteine synthetase inhibitor, sensitized the resistant cells to cisplatin, to levels similar as parental cells. Conclusions. By generating genetically-matched radiation resistant NSCLC tumor models we were able to identify and overcome cisplatin cross-resistance. This is an important finding arguing for multi-modality treatment regimens with the potential of improving clinical outcomes in the future. Citation Format: Samir V. Jenkins, Shruti Shah, Azemat Jamshidi-Parsian, Amir Mortazavi, Gunnar Boysen, Kieng B. Vang, Robert J. Griffin, Narasimhan Rajaram, Ruud P. Dings. Acquired radiation resistance induces thiol-dependent cisplatin cross-resistance [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1088.

Essential Oil Composition, Antioxidant Activity and Leaf Micromorphology of Five Tunisian Eucalyptus Species.

Eucalyptus species have been widely employed in the projects of reforestation in Tunisia. Although their ecological functions are controversial, these plants are indeed important to counteract soil erosion, and represent a fast-growing source of fuelwood and charcoal wood. In the present study, we considered five Eucalyptus species, namely Eucalyptus alba, E. eugenioides, E. fasciculosa, E. robusta, and E. stoatei cultivated in the Tunisian Arboreta. The aim was to carry out the micromorphological and anatomical characterization of the leaves, the extraction and phytochemical profile of the essential oils (EOs), and the evaluation of their biological properties. Four of the EOs showed the prevalence of eucalyptol (1,8-cineole) varying from 64.4 to 95.9%, whereas a-pinene predominated in E. alba EO (54.1%). These EOs showed in vitro antioxidant activity, and reduced the oxidative cellular stress as shown by their activity on reactive oxygen species (ROS) production, and modulation of the expression of antioxidant enzymes, such as glutamate-cysteine ligase (GCL) and heme oxygenase-1 (Hmox-1). Moreover, the EOs inhibited the production of nitric oxide (NO), showing anti-inflammatory activity. The data collected suggest that these EOs may be considered a promising therapeutic strategy for inflammation-based diseases and may represent an additional value for the economy of Tunisia.

Effects of Exhaustive Exercise on Inflammatory, Apoptotic, and Antioxidative Signaling Pathways in Human Peripheral Blood Mononuclear Cells.

In the present study, we investigated the effects of exhaustive exercise and recovery on inflammatory, pro-apoptotic, and anti-oxidative responses in human peripheral blood mononuclear cells (PBMCs). Sixteen volunteers participated in a guided physical activity program in which they were subjected to progressive exercise on the treadmill until they were exhausted followed by an 1-hour recovery period. Isolated human PBMCs were collected before exercise, immediately after exercise, and after 1-hour recovery. Exhaustive exercise induced expression of heme oxygenase-1 and glutamate cysteine ligase catalytic subunit and activation of NF-κB and NF-E2 related factor 2 (Nrf2). Apoptosis, as measured by activity and cleavage of caspase-3 and its substrate PARP also significantly increased. However, induction of redox signaling and the pro-apoptotic response fully returned to the baseline level during the 1-hour recovery period. On the other hand, COX-2 expression was continuously elevated after exercise cessation throughout the 1-hour recovery period. Taking all these findings into account, we conclude that exhaustive exercise transiently induces Nrf2-mediated antioxidant gene expression and eliminates damaged cells through apoptosis as part of an adaptive cytoprotective response against oxidative and inflammatory stress.