Oxidative Stress-induced Cell Death Research Articles

Nicotinamide Mononucleotide Prevents Retinal Dysfunction in a Mouse Model of Retinal Ischemia/Reperfusion Injury.

Retinal ischemia/reperfusion (I/R) injury can cause severe vision impairment. Retinal I/R injury is associated with pathological increases in reactive oxygen species and inflammation, resulting in retinal neuronal cell death. To date, effective therapies have not been developed. Nicotinamide mononucleotide (NMN), a key nicotinamide adenine dinucleotide (NAD+) intermediate, has been shown to exert neuroprotection for retinal diseases. However, it remains unclear whether NMN can prevent retinal I/R injury. Thus, we aimed to determine whether NMN therapy is useful for retinal I/R injury-induced retinal degeneration. One day after NMN intraperitoneal (IP) injection, adult mice were subjected to retinal I/R injury. Then, the mice were injected with NMN once every day for three days. Electroretinography and immunohistochemistry were used to measure retinal functional alterations and retinal inflammation, respectively. The protective effect of NMN administration was further examined using a retinal cell line, 661W, under CoCl2-induced oxidative stress conditions. NMN IP injection significantly suppressed retinal functional damage, as well as inflammation. NMN treatment showed protective effects against oxidative stress-induced cell death. The antioxidant pathway (Nrf2 and Hmox-1) was activated by NMN treatment. In conclusion, NMN could be a promising preventive neuroprotective drug for ischemic retinopathy.

The effect of dopaminergic neuron transplantation and melatonin co-administration on oxidative stress-induced cell death in Parkinson’s disease

A gradual degeneration of the striatum and loss of nigral dopamine cells are characteristic of Parkinson's disease. Nowadays, combination therapy for neurodegenerative disease is considered. This study aimed to investigate the effects of melatonin and dopaminergic neurons derived from adipose tissue stem cells (ADSCs) in a rat model of Parkinson’s disease. Parkinson’s disease was induced in rats using neurotoxin 6-Hydroxydopamine. The treatment was performed using melatonin and dopaminergic neurons transplantation. Subsequently, behavioral tests, western blot analysis for Caspase-3 expression, GSH (Glutathione) content and stereology analysis for the volume and cell number of substantia nigra and striatum were performed. Treatment with melatonin and dopaminergic neuron transplantation increased the number of neurons in substantia nigra and striatum while the number of glial cell and the volume of substantia nigra and striatum did not show significant change between groups. Western blot analysis for caspase 3 indicated the significant differences between groups. The results also indicated the increased level of glutathione (GSH) content in treatment groups. this study showed that combination therapy with melatonin and dopaminergic neurons could greatly protect the neurons, reduce oxidative stress and improve the symptoms of PD.

Overexpression of nucleotide metabolic enzyme DUT in hepatocellular carcinoma potentiates a therapeutic opportunity through targeting its dUTPase activity

Uracil misincorporation during DNA replication is a major cell toxic event, of which cancer cells overcome by activating the dUTPase enzyme. The DUT gene is the only known dUTPase in human. Despite reports on common upregulations in cancers, the role of DUT in human hepatocellular carcinoma (HCC) remains largely undetermined. In this study, we investigated the mechanism underlying DUT biology in HCC and tumor susceptibility to drug targeting dUTPase. Overexpression of DUT was found in 42% of HCC tumors and correlated with advanced stage HCC. Knockout of DUT in HCC cell lines showed suppressed proliferation through cell cycle arrest and a spontaneous induction of DNA damage. A protective effect from oxidative stress was also demonstrated in both knockout and overexpression DUT assays. Transcriptome analysis highlighted the NF-κB survival signaling as the downstream effector pathway of DUT in overriding oxidative stress-induced cell death. Interestingly, stably expressed DUT in liver progenitor organoids conferred drug resistance to TKI Sorafenib. Targeting dUTPase activity by TAS-114, could potentiate suppression of HCC growth that synergized with Sorafenib for better treatment sensitivity. In conclusion, upregulated DUT represents a nucleotide metabolic weakness and therapeutic opportunity in HCC.

Licochalcone B, a Natural Autophagic Agent for Alleviating Oxidative Stress-Induced Cell Death in Neuronal Cells and Caenorhabditis elegans Models.

Autophagy has been implicated in the regulation of neuroinflammation and neurodegenerative disorders. Licochalcone B (LCB), a chalcone from Glycyrrhiza inflata, has been reported to have anti-cancer, anti-oxidation and anti-β–amyloid fibrillation effects; however, its effect in autophagy remain un-investigated. In the current study, the potential neuro-protective role of LCB in terms of its anti-oxidative, anti-apoptotic, and autophagic properties upon oxidative stress-induced damage in neuronal cells was investigated. With the production of reactive oxygen species (ROS) as a hallmark of neuroinflammation and neurodegeneration, hydrogen peroxide (H2O2) was adopted to stimulate ROS-induced cell apoptosis in PC-12 cells. Our findings revealed that LCB reduced cell cytotoxicity and apoptosis of PC-12 cells upon H2O2-stimulation. Furthermore, LCB increased the level of the apoptosis-associated proteins caspase-3 and cleaved caspase-3 in H2O2-induced cells. LCB effectively attenuated the level of oxidative stress markers such as MDA, SOD, and ROS in H2O2-induced cells. Most importantly, LCB was confirmed to possess its anti-apoptotic effects in H2O2-induced cells through the induction of ATG7-dependent autophagy and the SIRT1/AMPK signaling pathway. As a novel autophagic inducer, LCB increased the level of autophagy-related proteins LC3–II and decreased p62 in both neuronal cells and Caenorhabditis elegans (C. elegans) models. These results suggested that LCB has potential neuroprotective effects on oxidative damage models via multiple protective pharmacological mechanisms.

Targeting phosphoglycerate kinase 1 with terazosin improves motor neuron phenotypes in multiple models of amyotrophic lateral sclerosis.

SummaryBackgroundAmyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder with heterogeneous aetiology and a complex genetic background. Effective therapies are therefore likely to act on convergent pathways such as dysregulated energy metabolism, linked to multiple neurodegenerative diseases including ALS.MethodsActivity of the glycolysis enzyme phosphoglycerate kinase 1 (PGK1) was increased genetically or pharmacologically using terazosin in zebrafish, mouse and ESC-derived motor neuron models of ALS. Multiple disease phenotypes were assessed to determine the therapeutic potential of this approach, including axon growth and motor behaviour, survival and cell death following oxidative stress.FindingsWe have found that targeting a single bioenergetic protein, PGK1, modulates motor neuron vulnerability in vivo. In zebrafish models of ALS, overexpression of PGK1 rescued motor axon phenotypes and improved motor behaviour. Treatment with terazosin, an FDA-approved compound with a known non-canonical action of increasing PGK1 activity, also improved these phenotypes. Terazosin treatment extended survival, improved motor phenotypes and increased motor neuron number in Thy1-hTDP-43 mice. In ESC-derived motor neurons expressing TDP-43M337V, terazosin protected against oxidative stress-induced cell death and increased basal glycolysis rates, while rescuing stress granule assembly.InterpretationOur data demonstrate that terazosin protects motor neurons via multiple pathways, including upregulating glycolysis and rescuing stress granule formation. Repurposing terazosin therefore has the potential to increase the limited therapeutic options across all forms of ALS, irrespective of disease cause.FundingThis work was supported by project grant funding from MND Scotland, the My Name’5 Doddie Foundation, Medical Research Council Doctoral Student Training Fellowship [Ref: BST0010Z] and Academy of Medical Sciences grant [SGL023\\1100].

Azithromycin Protects Retinal Glia Against Oxidative Stress-Induced Morphological Changes, Inflammation, and Cell Death.

The reactivity of retinal glia in response to oxidative stress has a significant effect on retinal pathobiology. The reactive glia change their morphology and secret cytokines and neurotoxic factors in response to oxidative stress associated with retinal neurovascular degeneration. Therefore, pharmacological intervention to protect glial health against oxidative stress is crucial for maintaining homeostasis and the normal function of the retina. In this study, we explored the effect of azithromycin, a macrolide antibiotic with antioxidant, immunomodulatory, anti-inflammatory, and neuroprotective properties against oxidative stress-induced morphological changes, inflammation, and cell death in retinal microglia and Müller glia. Oxidative stress was induced by H2O2, and the intracellular oxidative stress was measured by DCFDA and DHE staining. The change in morphological characteristics such as the surface area, perimeter, and circularity was calculated using ImageJ software. Inflammation was measured by enzyme-linked immunosorbent assays for TNF-α, IL-1β, and IL-6. Reactive gliosis was characterized by anti-GFAP immunostaining. Cell death was measured by MTT assay, acridine orange/propidium iodide, and trypan blue staining. Pretreatment of azithromycin inhibits H2O2-induced oxidative stress in microglial (BV-2) and Müller glial (MIO-M1) cells. We observed that azithromycin inhibits oxidative stress-induced morphological changes, including the cell surface area, circularity, and perimeter in BV-2 and MIO-M1 cells. It also inhibits inflammation and cell death in both the glial cells. Azithromycin could be used as a pharmacological intervention on maintaining retinal glial health during oxidative stress.

Hypoxia aggravates ferroptosis in RPE cells by promoting the Fenton reaction

Oxidative stress and hypoxia in the retinal pigment epithelium (RPE) have long been considered major risk factors in the pathophysiology of age-related macular degeneration (AMD), but systematic investigation of the interplay between these two risk factors was lacking. For this purpose, we treated a human RPE cell line (ARPE-19) with sodium iodate (SI), an oxidative stress agent, together with dimethyloxalylglycine (DMOG) which leads to stabilization of hypoxia-inducible factors (HIFs), key regulators of cellular adaptation to hypoxic conditions. We found that HIF stabilization aggravated oxidative stress-induced cell death by SI and iron-dependent ferroptosis was identified as the main cell death mechanism. Ferroptotic cell death depends on the Fenton reaction where H2O2 and iron react to generate hydroxyl radicals which trigger lipid peroxidation. Our findings clearly provide evidence for superoxide dismutase (SOD) driven H2O2 production fostering the Fenton reaction as indicated by triggered SOD activity upon DMOG + SI treatment as well as by reduced cell death levels upon SOD2 knockdown. In addition, iron transporters involved in non-transferrin-bound Fe2+ import as well as intracellular iron levels were also upregulated. Consequently, chelation of Fe2+ by 2’2-Bipyridyl completely rescued cells. Taken together, we show for the first time that HIF stabilization under oxidative stress conditions aggravates ferroptotic cell death in RPE cells. Thus, our study provides a novel link between hypoxia, oxidative stress and iron metabolism in AMD pathophysiology. Since iron accumulation and altered iron metabolism are characteristic features of AMD retinas and RPE cells, our cell culture model is suitable for high-throughput screening of new treatment approaches against AMD.

Cystathionine-β-synthase is essential for AKT-induced senescence and suppresses the development of gastric cancers with PI3K/AKT activation.

Hyperactivation of oncogenic pathways downstream of RAS and PI3K/AKT in normal cells induces a senescence-like phenotype that acts as a tumor-suppressive mechanism that must be overcome during transformation. We previously demonstrated that AKT-induced senescence (AIS) is associated with profound transcriptional and metabolic changes. Here, we demonstrate that human fibroblasts undergoing AIS display upregulated cystathionine-β-synthase (CBS) expression and enhanced uptake of exogenous cysteine, which lead to increased hydrogen sulfide (H2S) and glutathione (GSH) production, consequently protecting senescent cells from oxidative stress-induced cell death. CBS depletion allows AIS cells to escape senescence and re-enter the cell cycle, indicating the importance of CBS activity in maintaining AIS. Mechanistically, we show this restoration of proliferation is mediated through suppressing mitochondrial respiration and reactive oxygen species (ROS) production by reducing mitochondrial localized CBS while retaining antioxidant capacity of transsulfuration pathway. These findings implicate a potential tumor-suppressive role for CBS in cells with aberrant PI3K/AKT pathway activation. Consistent with this concept, in human gastric cancer cells with activated PI3K/AKT signaling, we demonstrate that CBS expression is suppressed due to promoter hypermethylation. CBS loss cooperates with activated PI3K/AKT signaling in promoting anchorage-independent growth of gastric epithelial cells, while CBS restoration suppresses the growth of gastric tumors in vivo. Taken together, we find that CBS is a novel regulator of AIS and a potential tumor suppressor in PI3K/AKT-driven gastric cancers, providing a new exploitable metabolic vulnerability in these cancers.

Single-cell sequencing analysis reveals gastric cancer microenvironment cells respond vastly different to oxidative stress

Gastric cancer is a common type of gastrointestinal malignant tumor in China. The mechanism of the development and progression of gastric cancer remains the continuing research focus. The tumor microenvironment plays an important role in the development and progression of tumors. The present study used single-cell sequencing data to characterize the microenvironment of gastric cancer, investigate the effects of oxidative stress on gastric cancer microenvironmental cells through the comparison between cancer tissue and normal tissue, and identify the key genes associated with gastric cancer patients’ survival. The results showed that compared with normal gastric tissue, gastric cancer tissue had a decreased oxidative stress response, weaker oxidative detoxification ability, and increased oxidative stress-induced cell death. In the different types of single cells of gastric cancer microenvironment, the oxidative stress response of T cell was increased, the ability of oxidative detoxification was enhanced, and the oxidative stress-induced cell death was exacerbate. Mucous cell showed the same trend as gastric cancer cells: decreased oxidative stress response, weak oxidative detoxification ability, and weakened oxidative stress-induced cell death. Moreover, TRIM62, MET, and HBA1, which were significantly associated with oxidative stress, may be biomarkers for the prognosis of gastric cancer. High expression of TRIM62 indicated a good prognosis, while MET and HBA1 indicated a poor prognosis, which will be confirmed by further clinical studies.

In vitro comparison of various antioxidants and flavonoids from Rooibos as beta cell protectants against lipotoxicity and oxidative stress-induced cell death.

Oxidative stress and lipotoxicity effects on pancreatic β cells play a major role in the pathogenesis of type 2 diabetes (T2D). Flavonoids and antioxidants are under study for their cytoprotective effects and antidiabetic potential. In this study, we aimed to compare the protective effect of the Rooibos components aspalathin, isoorientin, 3-hydroxyphloretin (3-OH) and green Rooibos extract (GRT) itself, and exendin-4 and N-acetylcysteine (NAC) as reference molecules, against lipotoxicity and oxidative stress. The insulin-producing β cell line INS1E was exposed to hydrogen peroxide or streptozotocin (STZ) to induce oxidative stress, and palmitate to induce lipotoxicity. Cell viability was assessed by a MTS cell viability assay. Antioxidant response and antiapoptotic gene expression was performed by qRT-PCR. Glucose transporter 2 (GLUT 2) transporter inhibition was assessed through 2-NBDG uptake. GRT and the flavonoids aspalathin and 3-hydroxyphloretin offered significant protection against oxidative stress and lipotoxicity. GRT downregulated expression of pro-apoptotic genes Txnip and Ddit3. The flavonoids aspalathin and 3-hydroxyphloretin also downregulated these genes and in addition upregulated expression of antioxidant response genes Hmox1, Nqo1 and Sod1. Isoorientin gave no cytoprotection. Cytoprotection by Rooibos components was significantly higher than by NAC or exendin-4. Rooibos components strongly protect INS1E β cells against diabetogenic stress. Cytoprotection was associated with the upregulation of antioxidant response genes of the NRF2/KEAP1 pathway or suppression of the TXN system. The Rooibos molecules offered better protection against these insults than exendin-4 and NAC, making them interesting candidates as β cell cytoprotectants for therapeutic or nutraceutical applications.

5HTR1E receptor interacts with Neurotrophic factor‐α1 and serotonin to activate two distinct signaling pathways

Neurotrophic factor‐α1/Carboxypeptidase E (NFα1/CPE) is a prohormone processing enzyme intracellularly and as a neurotrophic factor, extracellularly. Previously we showed that extracellular treatment of hippocampal neurons with NFα1/CPE protected them from oxidative stress‐induced cell death through ERK/BCL2 signaling. Based on these results, we hypothesized that NFα1/CPE activation of the ERK/BCL2 pathway to mediate neuroprotection should involve interaction with receptors at the cell membrane. We have identified 5‐hydroxytryptamine receptor 1E (5HTR1E), a Gi coupled serotonin receptor, as an extracellular binding partner of NFα1/CPE. This interaction was confirmed by co‐IP and pull‐down experiments followed by radioligand binding studies in HEK293‐5HTR1E overexpressing cells. Molecular modeling studies also predicted that NFα1/CPE interacted with HTR1E, not at the serotonin binding pocket, but via the extracellular loop 2 (ECL2) of 5HTR1E, forming 3 stable salt bridges with specific amino acid residues in NFα1/CPE. To identify the HTR1E downstream signaling pathways, we used HEK293 cells stably expressing 5HTR1E. First, we tested the dose dependent effect of both serotonin and NFα1/CPE on ERK, and cAMP signaling and found that both can increase ERK phosphorylation while cAMP pathway activation is serotonin dependent only. To further dissect the 5HTR1E mediated functions of both serotonin and NFα1/CPE we tested Gi, Gq, PKA, and PI3K inhibitors and observed that these proteins are not involved in NFα1/CPE mediated ERK phosphorylation, while serotonin‐stimulated ERK activation was Gi‐PKA dependent. We then explored the involvement of β‐arrestin, an alternative coupling mechanism with GPCRs for ERK activation. Studies in 5HTR1E expressing‐HEK293‐β‐arrestin KO cells revealed that NFα1/CPE‐5HTR1E complex was unable to induce ERK signaling in the absence of β‐arrestin proteins. Furthermore, molecular docking studies revealed a very strong coupling of b‐arrestin to intracellular loop (ICL) 2 and ICL3 of HTR1E. Using LDH cytotoxicity assay we demonstrated that NF‐α1/CPE was able to protect HEK‐293‐5HTR1E expressing cells against H2O2‐induced cytotoxicity, via increasing pro‐survival protein BCL2 expression; however, this protective effect of NFα1/CPE was diminished in the β‐arrestin KO cells. Our study identified two ligands for HTR1E: NFα1/CPE which interacts with HTR1E to activate β‐arrestin/ERK/BCL2 signaling pathway for protecting cells against oxidative stress; and serotonin which activated a Gi‐cAMP‐dependent pathway, the physiological role is under investigation.

Overexpression of V-ATPase B2 attenuates lung injury/fibrosis by stabilizing lysosomal membrane permeabilization and increasing collagen degradation

Excessive oxidative stress causes lysosomal membrane permeabilization (LMP), which leads to cell death. Vacuolar ATPase (V-ATPase) is the enzyme responsible for pumping H+ into the cytosol and thus maintaining intracellular pH. Previously, we reported that V-ATPase B2 subunit expression is upregulated in the TiO2-exposed lung epithelium. We investigated the role of the lysosomal V-ATPase B2 subunit in oxidative stress-induced alveolar epithelial cell death and in an experimental lung injury/fibrosis model. Overexpression of V-ATPase B2 increased lysosomal pH and lysosomal activities in the cells. In the presence of H2O2, overexpression of V-ATPase B2 increased survival, and silencing of V-ATPase B2 dramatically increased cell death. Overexpression of V-ATPase B2 diminished H2O2-triggered LMP, as evidenced by a reduction in acridine orange staining and leakage of cathepsin D from the lysosome to the cytoplasm. In addition, V-ATPase B2-overexpressing macrophages exhibited significantly enhanced uptake and degradation of collagen. V-ATPase B2-overexpressing transgenic mice showed significant inhibition of the bleomycin-induced increases in lung inflammation and fibrosis. We conclude that V-ATPase B2 is critical for maintaining lysosomal activities against excessive oxidative stress by stabilizing LMP. Our findings reveal a previously unknown role of this V-ATPase subunit in a lung injury and fibrosis model.

The E3 Ligase RNF157 Inhibits Lens Epithelial Cell Apoptosis by Negatively Regulating p53 in Age-Related Cataracts.

PurposeAge-related cataract (ARC) is a major cause of vision impairment worldwide. The E3 ubiquitin ligase RING finger protein 157 (RNF157) is involved in regulating cell survival and downregulated in human cataractous lens samples. However, the function of RNF157 in cataracts remains unclear. This study aimed to determine the role of RNF157 in ARC.MethodsReal-time polymerase chain reaction (PCR) and Western blotting were used to analyze the expression of RNF157 in clinical lens capsules, rat cataract models, and oxidative stress cell models. Western blot analysis and flow cytometry were used to evaluate cell apoptosis. Co-IP assay, protein stability assay, and ubiquitination assay were used to detect the interaction between RNF157 and its substrate p53.ResultsThe expression of RNF157 was downregulated in human cataract samples, UVB-induced rat cataract model, and H2O2-treated human lens epithelial cells (LECs). Ectopic expression of RNF157 protected LECs from H2O2-induced apoptosis. In contrast, knockdown of RNF157 enhanced oxidative stress-induced apoptotic cell death. Moreover, silence of RNF157 in the rat ex vivo lens model exacerbated lens opacity. Mechanistically, RNF157 causes ubiquitination and degradation of the tumor antigen p53. Overexpression of p53 eliminated the antiapoptotic effects of RNF157, whereas p53 knockdown rescued RNF157 silencing-induced cell death.ConclusionsOur findings revealed that reduced RNF157 expression promoted LEC apoptosis by upregulating p53 in cataracts, suggesting that the regulation of RNF157 expression may serve as a potential therapeutic strategy for cataracts.

Docosahexaenoic Acid Suppresses Oxidative Stress-Induced Autophagy and Cell Death via the AMPK-Dependent Signaling Pathway in Immortalized Fischer Rat Schwann Cells 1.

Autophagy is the process by which intracellular components are degraded by lysosomes. It is also activated by oxidative stress; hence, autophagy is thought to be closely related to oxidative stress, one of the major causes of diabetic neuropathy. We previously reported that docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) induced antioxidant enzymes and protected Schwann cells from oxidative stress. However, the relationship between autophagy and oxidative stress-induced cell death in diabetic neuropathy has not been elucidated. Treatment with tert-butyl hydroperoxide (tBHP) decreased the cell survival rate, as measured by an MTT assay in immortalized Fischer rat Schwann cells 1 (IFRS1). A DHA pretreatment significantly prevented tBHP-induced cytotoxicity. tBHP increased autophagy, which was revealed by the ratio of the initiation markers, AMP-activated protein kinase, and UNC51-like kinase phosphorylation. Conversely, the DHA pretreatment suppressed excessive tBHP-induced autophagy signaling. Autophagosomes induced by tBHP in IFRS1 cells were decreased to control levels by the DHA pretreatment whereas autolysosomes were only partially decreased. These results suggest that DHA attenuated excessive autophagy induced by oxidative stress in Schwann cells and may be useful to prevent or reduce cell death in vitro. However, its potentiality to treat diabetic neuropathy must be validated in in vivo studies.

Molecular delineation, expression profiling, immune response, and anti-apoptotic function of a novel clusterin homolog from big-belly seahorse (Hippocampus abdominalis)

Clusterin (CLU) is a glycoprotein that contains α- and β-chains. CLU exerts multifunctional activities and plays a role in different cell signaling pathways that are associated with various diseases such as proteotoxic and oxidative stress, as well as cell death and survival. However, its role in marine teleost fish remains unclear. Therefore, the present study was carried out to characterize and investigate the immune responses and anti-apoptotic effects of CLU of the big-belly seahorse (Hippocampus abdominalis) (HaCLU) on oxidative stress-induced cell death. The HaCLU open reading frame was 1389 bp long and encoded a protein with 462 amino acids, a molecular weight of 51.28 kDa and an isoelectric point of 5.41. In-silico results demonstrated that HaCLU has a signal peptide in the 1–29 amino acid region, while the α- and β-chains were in the 34–227 and 228–455 amino acid regions, respectively. Multiple sequence alignment clarified the low homology of the α-chain with other orthologs. The highest HaCLU mRNA expression level was observed in the liver, followed by the heart, spleen, and brain tissues of healthy big-belly seahorses. Further, HaCLU mRNA expression level was elevated in the liver in response to different stimuli, including lipopolysaccharides, polyinosinic:polycytidylic acid, Edwardsiella tarda, and Streptococcus iniae. HaCLU potentiates cell viability and weakens chromatin condensation in the nucleus of FHM cells following H2O2-induced oxidative stress and subsequent cell death. HaCLU overexpression resulted in a reduced Bax/Bcl-2 mRNA expression ratio. This study revealed the role of HaCLU in immune regulation against pathogenic infections and its anti-apoptotic effects on oxidative stress-induced cell death.

Protocatechualdehyde Rescues Oxygen-Glucose Deprivation/Reoxygenation-Induced Endothelial Cells Injury by Inducing Autophagy and Inhibiting Apoptosis via Regulation of SIRT1

Background: Oxidative stress-induced endothelial cell death, such as apoptosis and autophagy, plays a critical role in ischemia-reperfusion injury. Protocatechualdehyde (PCA) is a major bioactive component of the traditional Chinese medicine Salvia miltiorrhiza Bunge (Lamiaceae), and it has been proved to be effective in the prevention and treatment of ischemic cardiovascular and cerebrovascular diseases. However, its role in oxidative stress-induced endothelial cell death and its underlying mechanisms remains unclear. This study aims to investigate the effects and mechanisms of PCA on endothelial cell apoptosis and autophagy induced by oxygen-glucose deprivation/reoxygenation (OGD/R) injury. Methods: After OGD/R induction, human umbilical vein endothelial cells (HUVECs) were treated with different concentrations of PCA. Cell viability, apoptosis, and autophagy were detected by Cell Counting Kit-8 assay, flow cytometry, and monodansylcadaverine assay, respectively. Western blot was applied to explore the effects of PCA on the expression levels of relevant protein factors. Results: The results show that PCA significantly promoted cell survival rate and cell proliferation and enhanced the antioxidant activity in OGD/R-induced HUVECs. PCA inhibited HUVECs apoptosis, as evidenced by decreased expression of cleaved-caspase-3, Bcl2-associated X (BAX), and increased expression of Bcl-2. PCA induced autophagy by reducing the expression of P62 while increasing the expression of Beclin-1 and LC3 II/I. Meanwhile, PCA enhanced the expression of Sirtuin 1 (SIRT1) and suppressed the expression of P53. When SIRT1 was inhibited by selisistat or SIRT1 small-interfering RNA, the anti-apoptotic and pro-autophagy abilities of PCA were attenuated. Conclusion: These results demonstrated that PCA rescued HUVECs from OGD/R-induced injury by promoting autophagy and inhibiting apoptosis through SIRT1 and could be developed as a potential therapeutic agent against ischemic diseases.

Hepatitis B virus X protein promotes hepatocarcinogenesis via the activation of HMGA2/STC2 signaling to counteract oxidative stress-induced cell death

Chronic hepatitis B virus (HBV) infection can cause oxidative stress and induce cell death. The mechanisms by which cells overcome oxidative stress to survive remain largely unknown. Here, we used human sera, liver tissues and cell lines to study how HBV modulates cellular pathways to counteract oxidative stress-induced cell death. We found high-mobility group AT-hook 2 (HMGA2), an architectural transcription factor is upregulated in hepatocellular carcinoma (HCC) tissues and cell lines. Elevated serum HMGA2 is significantly associated with viral load in HBV carriers, and HBV-related HCC. We showed that HBV X protein (HBx) encoded by HBV-induced cell growth via HMGA2 activation. The growth-promoting effect is abolished when HMGA2 is suppressed. Ectopic HBx expression induced DNA damage and oxidative stress. HMGA2 silencing reduced oxidative stress in HBx-expressing cells. Cytoprotective stanniocalcin 2 (STC2) protein is a downstream target of HMGA2. Consistent with the findings in HMGA2, STC2 mRNA and protein expression are upregulated in HCC tissues. Elevated serum STC2 is also associated with viral load in HBV carriers, and HCC. STC2 is transcriptionally upregulated by HBx and HMGA2 to elicit cytoprotection against apoptosis. STC2 knockdown disrupted Bax/Bcl-2 balance that increased cytochrome c release, caspase 3/7 activity and apoptosis, and thus abolished the growth-promoting effect of HMGA2. Clinical relevance of HBx/HMGA2/STC2 signaling is evidenced by the significant correlation of serum HMGA2/STC2 in active HBV infection and HCC. These findings reveal a novel HBx regulatory HMGA2/STC2 pathway in counteracting reactive oxygen species-induced cell death. HMGA2 and STC2 may be therapeutic targets for prevention of hepatocarcinogenesis in chronic HBV infection.

Exploration of the Specific Pathology of HXMM Tablet Against Retinal Injury Based on Drug Attack Model to Network Robustness.

Retinal degenerative diseases are related to retinal injury because of the activation of the complement cascade, oxidative stress-induced cell death mechanisms, dysfunctional mitochondria, chronic neuroinflammation, and production of the vascular endothelial growth factor. Anti-VEGF therapy demonstrates remarkable clinical effects and benefits in retinal degenerative disease patients. Hence, new drug development is necessary to treat patients with severe visual loss. He xue ming mu (HXMM) tablet is a CFDA-approved traditional Chinese medicine (TCM) for retinal degenerative diseases, which can alleviate the symptoms of age-related macular degeneration (AMD) and diabetic retinopathy (DR) alone or in combination with anti-VEGF agents. To elucidate the mechanisms of HXMM, a quantitative evaluation algorithm for the prediction of the effect of multi-target drugs on the disturbance of the disease network has been used for exploring the specific pathology of HXMM and TCM precision positioning. Compared with anti-VEGF agents, the drug disturbance of HXMM on the functional subnetwork shows that HXMM reduces the network robustness on the oxidative stress subnetwork and inflammatory subnetwork to exhibit the anti-oxidation and anti-inflammation activity. HXMM provides better protection to ARPE-19 cells against retinal injury after H2O2 treatment. HXMM can elevate GSH and reduce LDH levels to exhibit antioxidant activity and suppress the expression of IL-6 and TNF-α for anti-inflammatory activity, which is different from the anti-VEGF agent with strong anti-VEGF activity. The experimental result confirmed the accuracy of the computational prediction. The combination of bioinformatics prediction based on the drug attack on network robustness and experimental validation provides a new strategy for precision application of TCM.

Identification of Novel Oxindole Compounds That Suppress ER Stress-Induced Cell Death as Chemical Chaperones.

Endoplasmic reticulum (ER) stress and oxidative stress lead to protein misfolding, and the resulting accumulation of protein aggregates is often associated with the pathogenesis of neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, and prion disease. Small molecules preventing these pathogenic processes may be effective interventions for such neurodegenerative disorders. In this paper, we identify several novel oxindole compounds that can prevent ER stress- and oxidative stress-induced cell death. Among them, derivatives of the lead compound GIF-0726-r in which a hydrogen atom at the oxindole ring 5 position is substituted with a methyl (GIF-0852-r), bromine (GIF-0854-r), or nitro (GIF-0856-r) group potently suppressed global ER stress. Furthermore, GIF-0854-r and -0856-r prevented protein aggregate accumulation in vitro and in cultured hippocampal HT22 neuronal cells, indicating that these two compounds function effectively as chemical chaperones. In addition, GIF-0852-r, -0854-r, and -0856-r prevented glutamate-induced oxytosis and erastin-induced ferroptosis. Collectively, these results suggest that the novel oxindole compounds GIF-0854-r and -0856-r may be useful therapeutics against protein-misfolding diseases as well as valuable research tools for studying the molecular mechanisms of ER and oxidative stress.

Modulatory Effects of Alpha-Mangostin Mediated by SIRT1/3-FOXO3a Pathway in Oxidative Stress-Induced Neuronal Cells.

Backgroundalpha-Mangostin, a polyphenolic xanthone, is primarily found in the pericarp of mangosteen throughout Southeast Asia and is considered as the “Queen of Fruit” in Thailand. Nonetheless, it is not clarified how alpha-mangostin protects neuronal cells against oxidative stress.ObjectiveIn this study, molecular mechanisms underlying the neuroprotective effect of alpha-mangostin in defending hydrogen peroxide (H2O2)-induced neurotoxicity was explored.Methodscytotoxicity, reactive oxygen species (ROS) generation, apoptotic cascades, and protein expression profiles were performed incorporation of molecular docking.ResultsHuman SH-SY5Y cells were pretreated with 1 μM alpha-mangostin for 3 h prior to exposure to 400 μM H2O2. alpha-Mangostin significantly inhibited oxidative stress-induced cell death in neuronal cells by reducing BAX protein, decreasing caspase-3/7 activation, and increasing anti-apoptotic BCL-2 protein. Collectively, alpha-mangostin was demonstrated to be a prominent ROS suppressor which reversed the reduction of antioxidant enzymes (CAT and SOD2). Surprisingly, alpha-mangostin significantly promoted the expression of the sirtuin family and the FOXO3a transcription factor exerting beneficial effects on cell survival and longevity. A molecular docking study predicted that alpha-mangostin is directly bound to the active site of SIRT1.ConclusionFindings from this study suggest that alpha-mangostin potentially serves as a promising therapeutic compound against oxidative stress by activation of the SIRT1/3-FOXO3a pathway comparable to the effect of memantine, an anti-AD drug used for the treatment of moderate to severe dementia.