Resveratrol attenuates hypoxia-induced neuronal cell death, inflammation and mitochondrial oxidative stress by modulation of TRPM2 channel

Gastrodin alleviates NTG-induced migraine-like pain via inhibiting succinate/HIF-1α/TRPM2 signaling pathway in trigeminal ganglion

BACKGROUND

Increasing evidence highlights the involvement of metabolic disorder and calcium influx mediated by transient receptor potential channels in migraine; however, the relationship between these factors in the pathophysiology of migraine remains unknown. Gastrodin is the major component of the traditional Chinese medicine Tianma, which is extensively used in migraine therapy.

PURPOSE

Our work aimed to explore the analgesic action of gastrodin and its regulatory mechanisms from a metabolic perspective.

METHODS/RESULTS

After being treated with gastrodin, the mice were given nitroglycerin (NTG) to induce migraine. Gastrodin treatment significantly raised the threshold of sensitivity in response to both mechanical and thermal stimulus evidenced by von Frey and hot plate tests, respectively, and decreased total contact numbers in orofacial operant behavioral assessment. We found that the expression of transient receptor potential melastatin 2 (TRPM2) channel was increased in the trigeminal ganglion (TG) of NTG-induced mice, resulting in a sustained Ca2+ influx to trigger migraine pain. The content of succinate, a metabolic biomarker, was elevated in blood samples of migraineurs, as well as in the serum and TG tissue from NTG-induced migraine mice. Calcium imaging assay indicated that succinate insult elevated TRPM2-mediated calcium flux signal in TG neurons. Mechanistically, accumulated succinate upregulated hypoxia inducible factor-1α (HIF-1α) expression and promoted its translocation into nucleus, where HIF-1α enhanced TRPM2 expression through transcriptional induction in TG neurons, evidenced by luciferase reporter measurement. Gastrodin treatment inhibited TRPM2 expression and TRPM2-dependent Ca2+ influx by attenuating succinate accumulation and downstream HIF-1α signaling, and thereby exhibited analgesic effect.

CONCLUSION

This work revealed that succinate was a critical metabolic signaling molecule and the key mediator of migraine pain through triggering TRPM2-mediated calcium overload. Gastrodin alleviated NTG-induced migraine-like pain via inhibiting succinate/HIF-1α/TRPM2 signaling pathway in TG neurons. These findings uncovered the anti-migraine effect of gastrodin and its regulatory mechanisms from a metabolic perspective and provided a novel theoretical basis for the analgesic action of gastrodin.

TRPM2 knockdown attenuates myocardial apoptosis and promotes autophagy in HFD/STZ-induced diabetic mice via regulating the MEK/ERK and mTORC1 signaling pathway

Diabetic cardiomyopathy (DCM) is a major complication of diabetes. Transient receptor potential melastatin 2 (TRPM2) activity increases in diabetic oxidative stress state, and it is involved in myocardial damage and repair. We explore the protective effect of TRPM2 knockdown on the progression of DCM. A type 2 diabetes animal model was established in C57BL/6N mice by long-term high-fat diet (HFD) feeding combined with a single injection of 100-mg/kg streptozotocin (STZ). Genetic knockdown of TRPM2 in heart was accomplished by the intravenous injection via the tail vein of adeno-associated virus type 9 carrying TRPM2 shRNA. Neonatal rat ventricular myocytes was exposed to 45 mM of high-glucose (HG) stimulation for 72 h in vitro to mimic the in vivo conditions. Western blot, real-time quantitative PCR (RT-qPCR), immunohistochemistry and fluorescence, electron, CCK-8, and flow cytometry were used to evaluate the phenotype of cardiac inflammation, fibrosis, apoptosis, and autophagy. Mice with HFD/STZ-induced diabetes exhibited systolic and diastolic dysfunction, as demonstrated by increased myocardial apoptosis and autophagy inhibition in the heart. Compared to control group, the protein expression of TRPM2, bax, cleaved caspase-3, and P62 was significantly elevated, and the protein expression of bcl-2 and LC3-II was significantly decreased in the myocardial tissues of the HFD/STZ-induced diabetes group. Knockdown of TRPM2 significantly reversed the HFD/STZ-induced myocardial apoptosis and autophagy inhibition. TRPM2 silencing attenuated HG-induced apoptosis and autophagy inhibition in primary cardiomyocytes via regulating the MEK/ERK mTORC1 signaling pathway. TRPM2 knockdown attenuates hyperglycemia-induced myocardial apoptosis and promotes autophagy in HFD/STZ-induced diabetic mice or HG-stimulated cardiomyocytes via regulating the MEK/ERK and mTORC1 signaling pathway.

The Combination of 5-FU and Resveratrol Can Suppress the Growth of Glioblastoma Cells Through Downregulation of TRPM2 and β-Catenin

Glioblastoma multiforme (GBM) is the most common as well as the most fatal primary malignant tumor of the central nervous system (CNS), which still lacks a definitive cure. 5-FU is an anti-metabolite anti-cancer agent which has shown promising results for GBM treatment. Resveratrol (Res) is a phytochemical anti-oxidant that has also been effective in suppressing the progression of GBM. The combination of 5-FU and Res has been studied in a variety of cancers, but no study has assessed this combination in GBM. In this study, we investigated how 5-FU and Res, in combination and alone, may affect the growth and apoptosis of GBM cells and also the potential of TRPM2 and β-catenin as the mediator of their effects. U87 cells were cultured as the in vitro model. MTT assay was used for measuring cellular growth, and RT-qPCR was used to measure the level of caspase-3, TRPM2, and β-catenin; caspase-3 level served as the indicator of apoptotic rate. 5-FU and Res, in combination and alone, suppressed the growth while promoting the apoptosis of U87 cells; these effects were significantly greater when they were used in combination. RT-qPCR showed downregulation of TRPM-2 and β-catenin in response to this combination, which suggested that these two molecules may mediate the cited anti-oncogenic effects. In conclusion, our study confirmed the synergism between 5-FU and Res in suppressing the progression of GBM and suggested the putative axis of TRPM2/ β-catenin as the downstream mediator of this therapeutic regime. Future studies may be able to approve the eligibility of this therapeutic regime for GBM treatment and also the underlying mechanism.

Arginine-methylated c-Myc affects mitochondrial mitophagy in mouse acute kidney injury via Slc25a24

The transcription factor methylated c-Myc heterodimerizes with MAX to modulate gene expression, and plays an important role in energy metabolism in kidney injury but the exact mechanism remains unclear. Mitochondrial solute transporter Slc25a24 imports ATP into mitochondria and is central to energy metabolism. Gene Expression Omnibus data analysis reveals Slc25a24 and c-Myc are consistently upregulated in all the acute kidney injury (AKI) cells. Pearson correlation analysis also shows that Slc25a24 and c-Myc are strongly correlated (⍴ > 0.9). Mutant arginine methylated c-Myc (R299A and R346A) reduced its combination with MAX when compared with the wild type of c-Myc. On the other hand, the Slc25a24 levels were also correspondingly reduced, which induced the downregulation of ATP production. The results promoted reactive oxygen species (ROS) production and mitophagy generation. The study revealed that the c-Myc overexpression manifested the most pronounced mitochondrial DNA depletion. Additionally, the varied levels of mitochondrial proteins like TIM23, TOM20, and PINK1 in each group, particularly the elevated levels of PINK1 in AKI model groups and lower levels of TIM23 and TOM20 in the c-Myc overexpression group, suggest potential disruptions in mitochondrial dynamics and homeostasis, indicating enhanced mitophagy or mitochondrial loss. Therefore, arginine-methylated c-Myc affects mouse kidney injury by regulating mitochondrial ATP and ROS, and mitophagy via Slc25a24.

Exploring the Role of Drug Repurposing in Bridging the Hypoxia-Depression Connection

High levels of oxidative stress are implicated in hypoxia, a physiological response to low levels of oxygen. Evidence supports a connection between this response and depression. Previous studies indicate that tryptophan hydroxylase can be negatively affected in hypoxia, impairing serotonin synthesis and downstream pathways. Some studies also hypothesize that increasing hypoxia-inducible factor-1 (HIF-1) levels may be a new therapeutic modality for depression. Hence, this study delved into the influence of hypoxia on the cellular response to drugs designed to act in depression. By the induction of hypoxia in SH-SY5Y cells through a hypoxia incubator chamber or Cobalt Chloride treatment, the effect of Mirtazapine, an antidepressant, and other drugs that interact with serotonin receptors (TCB-2, Dextromethorphan, Ketamine, Quetiapine, Scopolamine, Celecoxib, and Lamotrigine) on SH-SY5Y cellular viability and morphology was explored. The selection of drugs was initially conducted by literature search, focusing on compounds with established potential for employment in depression therapy. Subsequently, we employed in silico approaches to forecast their ability to traverse the blood-brain barrier (BBB). This step was particularly pertinent as we aimed to assess their viability for inducing potential antidepressant effects. The effect of these drugs in hypoxia under the inhibition of HIF-1 by Echinomycin was also tested. Our results revealed that all the potential repurposed drugs promoted cell viability, especially when hypoxia was chemically induced. When combined with Echinomycin, all drugs decreased cellular viability, possibly by the inability to interact with HIF-1.

Antioxidant potentials of furanodihydrobenzoxanthones from Artocarpus elasticus and their protection against oxLDL induced injury in SH-SY5Y cells

Exposure to reactive oxygen species (ROS) leads to the oxidation of low-density lipoproteins (LDL), converting them into oxidized ones (oxLDL), which are involved in the pathogenesis of Alzheimer's disease, suggesting a potential link between lipid dysregulation and neurodegenerative processes. Phenolic metabolites derived from Artocarpus elasticus root bark were found to possess significant antioxidant properties at three different radical scavenging assays, including 2,2-diphenyl-1-picrylhydrazyl (DPPH), oxygen radical absorbance capacity (ORAC), and thiobarbituric acid reactive substances (TBARS). Among them, furanodihydrobenzoxanthones (1-3) demonstrated notable protection against Cu2+ induced LDL oxidation, with IC50 values ranging from 0.9 to 2.9 μM in measurement of the malondialdehyde (MDA) production at TBARS and prolonged lag times (>180 min) in the generation of conjugated diene (CD). At a concentration of 10 μM, all three compounds (1-3) effectively protected against LDL oxidation as determined by relative electrophoretic mobility (REM). The most potent compound 1 defended human neuroblastoma SH-SY5Y cells from oxLDL-mediated dysfunction, including oxLDL-induced cytotoxicity, inhibited reactive oxygen species (ROS) formation, and enhancing mitochondrial membrane potential (ΔΨm). Individual components annotation in the ethylacetate extract was performed using LC-ESI-QTOF/MS, which serves as a chemotaxonomic marker for A. elasticus root barks.

Antioxidant potential of nanomaterials

Background/aim

The novel field of nanomaterials allows infinite possibilities in order to create antioxidant therapies. The present review is aimed to describe the state of art concerning on nanomaterials and their effects on reactive oxygen species (ROS) production. A wide range of nanoparticles has been designed for this purpose, and each one possesses some particular characteristics which allow these significant antioxidant results. Several in vivo and in vitro works state the ability of these nanoparticles to mimic the redox systems of the cells, and thus, the potential role of nanoparticles as antioxidant treatment for several diseases.

Materials and methods

This paper was written after a review of the articles published on the field, using the "PubMed" and "Research Gate" databases.

Results

The main types of nanoparticles are listed and explained below, offering a global vision of the field with great interest for research. Antitumor chemo- and radiotherapies have been found to improve efficacy by enhancing the selectivity of cytocidal effects and minimizing systemic adverse effects when such materials are used. Furthermore, catalytic nanomaterials can execute energy-free antioxidant cycles that scavenge the most harmful reactive oxygen species via SOD- and catalase-like activities.

Conclusion

This unique method is projected to result in significant gains in the long run. However, due to a lack of understanding of potential adverse body reactions to these novel strategies, caution must be exercised. Analyzing the biocompatibility of these nanomaterials carefully, particularly in terms of biokinetics and the problems that could arise from long-term retention of nonbiodegradable inorganic nanomaterials, is required.

Protective Effects and Mechanisms of Pectolinarin against H2O2-Induced Oxidative Stress in SH-SY5Y Neuronal Cells

This study aims to investigate the protective effects and mechanisms of pectolinarin against oxidative stress-induced cell damage in SH-SY5Y cells. Neurodegenerative diseases-such as Alzheimer's disease-are potentially associated with oxidative stress, which causes excessive production of reactive oxygen species (ROS) that damage DNA and proteins in neuronal cells. The results of this study demonstrate that pectolinarin can scavenge hydroxyl and nitric oxide radicals in a concentration-dependent manner. Moreover, pectolinarin significantly increased cell viability while reducing ROS production and LDH release in the hydrogen peroxide (H2O2)-induced control group. Additionally, Pectolinarin recovered protein expression from H2O2-altered levels back to close-to-normal SH-SY5Y cell levels for components of the oxidative stress, inflammation, and apoptosis pathways-such as nuclear factor erythroid 2-related factor 2 (Nrf2), kelch-like ECH-associated protein (Keap1), anti-heme oxygenase 1 (HO-1), inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), interleukin-1β (IL-1β), B-cell lympho-ma-2 (Bcl-2) protein, and Bcl-2-associated X protein (Bax). These findings suggest that pectolinarin has the potential to be used as a plant material for functional foods to be applied in the treatment of neurodegenerative diseases, such as Alzheimer's disease, by mitigating oxidative stress-induced damage to neuronal cells.

Analysis of gene expression profiles and experimental validations of a rat chronic cervical cord compression model

Cervical spondylotic myelopathy (CSM) is a severe non-traumatic spinal cord injury (SCI) wherein the spinal canal and cervical cord are compressed due to the degeneration of cervical tissues. To explore the mechanism of CSM, the ideal model of chronic cervical cord compression in rats was constructed by embedding a polyvinyl alcohol polyacrylamide hydrogel in lamina space. Then, the RNA sequencing technology was used to screen the differentially expressed genes (DEGs) and enriched pathways among intact and compressed spinal cords. A total of 444 DEGs were filtered out based on the value of log₂(Compression/Sham); these were associated with IL-17, PI3K-AKT, TGF-β, and Hippo signaling pathways according to the GSEA, KEGG, and GO analyses. Transmission electron microscopy indicated the changes in mitochondrial morphology. Western blot and immunofluorescent staining revealed neuronal apoptosis, astrogliosis and microglial neuroinflammation in the lesion area. Specifically, the expression of apoptotic indicators, such as Bax and cleaved caspase-3, and inflammatory cytokines, such as IL-1β, IL-6, and TNF-α, were upregulated. The activation of IL-17 signaling pathways was observed in microglia instead of neurons or astrocytes, the activation of TGF-β and inhibition of Hippo signaling pathways were detected in astrocytes instead of neurons or microglia, and the inhibition of PI3K-AKT signaling pathway was discovered in neurons rather than microglia of astrocytes in the lesion area. In conclusion, this study indicated that neuronal apoptosis was accompanied by inhibiting of the PI3K-AKT pathway. Then, the activation of microglia IL-17 pathway and NLRP3 inflammasome effectuated the neuroinflammation, and astrogliosis was ascribed to the activation of TGF-β and the inhibition of the Hippo pathway in the chronic cervical cord of compression. Therefore, therapeutic methods targeting these pathways in nerve cells could be promising CSM treatments.

SIRTUINS MODULATORS COUNTERACT MITOCHONDRIAL DYSFUNCTION IN CELLULAR MODELS OF HYPOXIA: RELEVANCE TO SCHIZOPHRENIA

Schizophrenia (SZ) is a neurodevelopmental-associated disorder strongly related to environmental factors, such as hypoxia. Because there is no cure for SZ or any pharmacological approach that could revert hypoxia-induced cellular damages, we evaluated whether modulators of sirtuins could abrogate hypoxia-induced mitochondrial deregulation as a neuroprotective strategy. Firstly, astrocytes from control (Wistar) and Spontaneously Hypertensive Rats (SHR), a model of both SZ and neonatal hypoxia, were submitted to chemical hypoxia. Then, cells were exposed to different concentrations of Nicotinamide (NAM), Resveratrol (Resv), and Sirtinol (Sir) for 48hrs. Our data indicate that sirtuins modulation reduces cell death increasing the acetylation of histone 3. This outcome is related to the rescue of loss of mitochondrial membrane potential, changes in mitochondrial calcium buffering capacity, decreased O₂^-• levels and increased expression of metabolic regulators (Nrf-1 and Nfe2l2) and mitochondrial content. Such findings are relevant not only for hypoxia-associated conditions, named pre-eclampsia but also for SZ since prenatal hypoxia is a relevant environmental factor related to this burdensome neuropsychiatric disorder.

Intravitreal Administration of AAV2-SIRT1 Reverses Diabetic Retinopathy in a Mouse Model of Type 2 Diabetes

Purpose

The expression of silent information regulator (SIRT) 1 is reduced in diabetic retinopathy (DR). Previous studies showed that alterations in SIRT1 messenger RNA (mRNA) and protein expression are implicated in progressive inflammation and formation of retinal acellular capillaries. Treatment with the SIRT1 agonist, SRT1720, improved visual response by restoration of a- and b-wave responses on electroretinogram scotopic measurements in diabetic (db/db) mice. In this study, we investigated the effects of intravitreal SIRT1 delivery on diabetic retinal pathology.

Methods

Nine-month-old db/db mice received one intravitreal injection of either AAV2-SIRT1 or AAV2-GFP control virus, and after 3 months, electroretinography and optomotor responses were measured. Their eyes were then removed and analyzed by immunohistochemistry and flow cytometry.

Results

SIRT1 mRNA and protein levels were increased following AAV2-SIRT1 administration compared to control virus AAV2-GFP injected mice. IBA1+ and caspase 3 expression were decreased in retinas of db/db mice injected with AAV2-SIRT1, and reductions in scotopic a- and b-waves and high spatial frequency in optokinetic response were prevented. Retinal hypoxia inducible factor 1α (HIF-1α) protein levels were reduced in the AAV2-SIRT1-injected mice compared to control-injected mice. Using flow cytometry to assess changes in intracellular HIF-1α levels, endothelial cells (CD31+) from AAV-2 SIRT1 injected mice demonstrated reduced HIF-1α expression compared to db/db mice injected with the control virus.

Conclusions

Intravitreal AAV2-SIRT1 delivery increased retina SIRT1 and transduced neural and endothelial cells, thus reversing functional damage and improving overall visual function.

Translational Relevance

AAV2-SIRT1 gene therapy represents a beneficial approach for the treatment of chronic retinal conditions such as DR.

MITOCHONDRIA: The dual function of the transient receptor potential melastatin 2 channels from cytomembrane to mitochondria

Mitochondria are closely related to oxidative stress and play an important role in maintaining cell functional homeostasis and meeting cell energy demand. The transient receptor potential melastatin 2 (TRPM2) channel affects the occurrence and progression of diseases by regulating mitochondrial function. TRPM2 channel promotes Ca²⁺ influx to affect 18 kDa translocator protein (TSPO), mitochondrial membrane potential (MMP), reactive oxygen species (ROS), adenosine triphosphate (ATP) production, and mitochondrial autophagy. The mechanism of Ca²⁺ influx into the mitochondria by TRPM2 is abundant. Interestingly, the TRPM2 channel inhibits the production of mitochondrial ROS in cancer cells and promotes the production of mitochondrial ROS in normal cells, which induces cell death in normal cells but proliferation in cancer cells. TRPM2 can be a potential target for the treatment of various diseases due to its role as a molecular link between mitochondria and Ca²⁺ signals.

Resveratrol alleviated neuroinflammation induced by pseudorabies virus infection through regulating microglial M1/M2 polarization

BACKGROUND

Pseudorabies virus (PRV) infections in susceptible non-porcine species trigger uncontrolled inflammations and eventually fatal encephalitis. Resveratrol (Res) has broad pharmacological functions including anti-virus, anti-inflammation, and neuroprotective.

PURPOSE

We attempted to investigate the potential of Res in ameliorating PRV infection pathology in mice and decipher the mechanism of Res in treating PRV.

METHODS

The mice were infected by PRV to investigate the protective effect of Res. Blood-brain barrier (BBB) permeability, H&E/Nissl/TUNEL staining, Real-time PCR and ELISA analyses were performed. Primary microglia and neuron were isolated from mice and cultured. The co-culture model of microglia and neuron was established by transwell. Immunofluorescence assay and flow cytometry were used.

RESULTS

In this study, we showed that Res ameliorated brain damage by reducing BBB permeability in PRV-infected mice, and diminished the expressions of MMP-2, MMP-9 and ZO-1 in the cortex. Pathological changes of neurons by H&E/Nissl/TUNEL staining suggested that Res could alleviate neuronal lesions. Moreover, Res inhibited the expressions of pro-inflammatory factors (IL-6, TNF-α) and chemokines (CCL3, CXCL10, MCP-1), but increased the expressions of anti-inflammatory factors (IL-4, IL-10) and neurotrophic factor (TGF-β, NGF and GDNF) in brain. In vitro cultured microglia cells, Res could suppress M1 microglia polarization and activate M2 microglia polarization. Co-culture of PRV-infected microglia with neuron cells by transwell system indicated that Res alleviated inflammatory response and neuronal apoptosis.

CONCLUSION

This study provided evidence that Res could protect mice from PRV-induced encephalitis through regulation of microglia polarization and neuronal apoptosis suggesting the potential for treatment of viral encephalitis.

Lysosomal Ca2+ as a mediator of palmitate-induced lipotoxicity

While the mechanism of lipotoxicity by palmitic acid (PA), an effector of metabolic stress in vitro and in vivo, has been extensively investigated, molecular details of lipotoxicity are still not fully characterized. Since recent studies reported that PA can exert lysosomal stress in addition to well-known ER and mitochondrial stress, we studied the role of lysosomal events in lipotoxicity by PA, focusing on lysosomal Ca²⁺. We found that PA induced accumulation of mitochondrial ROS and that mitochondrial ROS induced release of lysosomal Ca²⁺ due to lysosomal Ca²⁺ exit channel activation. Lysosomal Ca²⁺ release led to increased cytosolic Ca²⁺ which induced mitochondrial permeability transition (mPT). Chelation of cytoplasmic Ca²⁺ or blockade of mPT with olesoxime or decylubiquinone (DUB) suppressed lipotoxicity. Lysosomal Ca²⁺ release led to reduced lysosomal Ca²⁺ content which was replenished by ER Ca²⁺, the largest intracellular Ca²⁺ reservoir (ER → lysosome Ca²⁺ refilling), which in turn activated store-operated Ca²⁺ entry (SOCE). Inhibition of ER → lysosome Ca²⁺ refilling by blockade of ER Ca²⁺ exit channel using dantrolene or inhibition of SOCE using BTP2 inhibited lipotoxicity in vitro. Dantrolene or DUB also inhibited lipotoxic death of hepatocytes in vivo induced by administration of ethyl palmitate together with LPS. These results suggest a novel pathway of lipotoxicity characterized by mPT due to lysosomal Ca²⁺ release which was supplemented by ER → lysosome Ca²⁺ refilling and subsequent SOCE, and also suggest the potential role of modulation of ER → lysosome Ca²⁺ refilling by dantrolene or other blockers of ER Ca²⁺ exit channels in disease conditions characterized by lipotoxicity such as metabolic syndrome, diabetes, cardiomyopathy or nonalcoholic steatohepatitis.

NMDA Receptor Activation Stimulates Hypoxia-Induced TRPM2 Channel Activation, Mitochondrial Oxidative Stress, and Apoptosis in Neuronal Cell Line: Modular Role of Memantine

TRPM2 channel is activated by the increase of hypoxia (HYP)-mediated excessive mitochondrial (mROS) and cytosolic (cROS) free reactive oxygen species generation and intracellular free Ca²⁺ ([Ca²⁺]_i) influx. The stimulations of the N-methyl-d-aspartate(NMDA) receptor and TRPM2 channel induce mROS and apoptosis in the neurons, although their inhibitions via the treatments of memantine (MEM) and MK-801 decrease mROS and apoptosis. However, the molecular mechanisms underlying MEM treatment and NMDA inhibition' neuroprotection via TRPM2 inhibition in the HYP remain elusive. We investigated the modulator role of MEM and NMDA via the modulation of TRPM2 on oxidative neurodegeneration and apoptosis in SH-SY5Y neuronal cells. Six groups were induced in the SH-SY5Y and HEK293 cells as follows: Control, MEM, NMDA blocker (MK-801), HYP (CoCl₂), HYP + MEM, and HYP + MK-801. The HYP caused to the increases of TRPM2 and PARP-1 expressions, and TRPM2 agonist (H₂O₂ and ADP-ribose)-induced TRPM2 current density and [Ca²⁺]_i concentration via the upregulation of mitochondrial membrane potential, cROS, and mROS generations. The alterations were not observed in the absence of TRPM2 in the HEK293 cells. The increase of cROS, mROS, lipid peroxidation, cell death (propidium iodide/Hoechst) rate, apoptosis, caspase -3, caspase -8, and caspase -9 were restored via upregulation of glutathione and glutathione peroxidase by the treatments of TRPM2 antagonists (ACA or 2-APB), MEM, and MK-801. In conclusion, the inhibition of NMDA receptor via MEM treatment modulated HYP-mediated mROS, apoptosis, and TRPM2-induced excessive [Ca²⁺]_i and may provide an avenue for protecting HYP-mediated neurodegenerative diseases associated with the increase of mROS, [Ca²⁺]_i, and apoptosis.

Non-prophylactic resveratrol-mediated protection of neurite integrity under chronic hypoxia is associated with reduction of Cav1.2 channel expression and calcium overloading

Cellular hypoxia is a major cause of oxidative stress, culminating in neuronal damage in neurodegenerative diseases. Numerous ex vivo studies have implicated that hypoxia episodes leading to disruption of Ca²⁺ homeostasis and redox status contribute to the progression of various neuropathologies and cell death. Isolation and maintenance of primary cell culture being cost-intensive, the details of the time course relationship between Ca²⁺ overload, L-type Ca²⁺ channel function, and neurite retraction under chronic and long-term hypoxia remain undefined. In order to explore the effect of oxidative stress and Ca²⁺ overload on neurite length, first, we developed a 5-day-long neurite outgrowth model using N2a cell line. Second, we propose a chronic hypoxia model to investigate the modulation of the L-type Ca²⁺ channel (Cav1.2) and oxidative resistance gene (OXR1) expression level during the process of neurite retraction and neuronal damage over 32 h. Thirdly, we developed a framework for quantitative analysis of cytosolic Ca²⁺, superoxide formation, neurite length, and constriction formation in individual cells using live imaging that provides an understanding of molecular targets. Our findings suggest that an increase in cytosolic Ca²⁺ is a feature of an early phase of hypoxic stress. Further, we demonstrate that augmentation in the L-type channel leads to amplification in Ca²⁺ overload, ROS accumulation, and a reduction in neurite length during the late phase of hypoxic stress. Next, we demonstrated that non-prophylactic treatment of resveratrol leads to the reduction of calcium overloading under chronic hypoxia via lowering of L-type channel expression. Finally, we demonstrate that resveratrol-mediated reduction of Cav1.2 channel and STAT3 expression are associated with retention of neurite integrity. The proposed in vitro model assumes significance in the context of drug designing and testing that demands monitoring of neurite length and constriction formations by imaging before animal testing.

The Significance of COVID-19 Diseases in Lipid Metabolism Pregnancy Women and Newborns

Coronavirus disease (COVID-19) is an infectious disease caused by SARS-CoV-2. Elderly people, people with immunodeficiency, autoimmune and malignant diseases, as well as people with chronic diseases have a higher risk of developing more severe forms of the disease. Pregnant women and children can becomesick, although more often they are only the carriers of the virus. Recent studies have indicated that infants can also be infected by SARS-CoV-2 and develop a severe form of the disease with a fatal outcome. Acute Respiratory Distress Syndrome (ARDS) ina pregnant woman can affect the supply of oxygen to the fetus and initiate the mechanism of metabolic disorders of the fetus and newborn caused by asphyxia. The initial metabolic response of the newborn to the lack of oxygen in the tissues is the activation of anaerobic glycolysis in the tissues and an increase in the concentration of lactate and ketones. Lipid peroxidation, especially in nerve cells, is catalyzed by iron released from hemoglobin, transferrin and ferritin, whose release is induced by tissue acidosis and free oxygen radicals. Ferroptosis-inducing factors can directly or indirectly affect glutathione peroxidase through various pathways, resulting in a decrease in the antioxidant capacity and accumulation of lipid reactive oxygen species (ROS) in the cells, ultimately leading to oxidative cell stress, and finally, death. Conclusion: damage to the mitochondria as a result of lipid peroxidation caused by the COVID-19 disease can cause the death of a newborn and pregnant women as well as short time and long-time sequelae.

Valproic Acid Attenuated PTZ-induced Oxidative Stress, Inflammation, and Apoptosis in the SH-SY5Y Cells via Modulating the TRPM2 Channel

Valproic acid (VPA) is one of the most widely used antiepileptic drugs. The protective role of VPA and the role of the TRPM2 channel in this mechanism in developing neuronal damage due to increased pentylenetetrazol (PTZ)-induced neurotoxicity in SH-SY5Y cells were not clarified. Here, we investigated the role of VPA via modulation of TRPM2 channel on cell death and oxidative neurotoxicity in SH-SY5Y cells. The SH-SY5Y cell toxicity model was constructed by treating SH-SY5Y cells with PTZ. The VPA and TRPM2 channel antagonist N-(p-amylcinnamoyl) anthranilic acid (ACA) were added to prevent neurotoxicity in PTZ-induced SH-SY5Y cells. The role of the VPA and TRPM2 channel was evaluated using an ELISA kit and patch-clamp. Primarily, antioxidant (GSH and GSH-Px) and oxidative stress (MDA and ROS) levels and inflammatory factors (IL-1β, IL-6, and TNF-α) in cells were determined by ELISA kits. Then, TRPM2 channel activation in cells was detected using both the ELISA kit and patch-clamp methods. In addition, apoptosis and cell viability levels in cells were determined by performing PARP1, caspase-3, caspase-9, and CCK-8 assays by ELISA kits. Our results showed that the TRPM2 channel is vital in damage formation in PTZ-induced cells. Furthermore, we observed that VPA attenuated PTZ-induced neurotoxicity by suppressing cells' oxidative stress and inflammation, and reducing TRPM2 channel activation. In our study, in which the protective effect of VPA and the role of the TRPM2 channel in PTZ-induced SH-SY5Y cells were investigated for the first time, we can conclude that VPA treatment and TRPM2 channel blockade can suppress PTZ-induced neurotoxicity.

Resveratrol Mitigates Oxygen and Glucose Deprivation-Induced Inflammation, NLRP3 Inflammasome, and Oxidative Stress in 3D Neuronal Culture

Oxygen glucose deprivation (OGD) can produce hypoxia-induced neurotoxicity and is a mature in vitro model of hypoxic cell damage. Activated AMP-activated protein kinase (AMPK) regulates a downstream pathway that substantially increases bioenergy production, which may be a key player in physiological energy and has also been shown to play a role in regulating neuroprotective processes. Resveratrol is an effective activator of AMPK, indicating that it may have therapeutic potential as a neuroprotective agent. However, the mechanism by which resveratrol achieves these beneficial effects in SH-SY5Y cells exposed to OGD-induced inflammation and oxidative stress in a 3D gelatin scaffold remains unclear. Therefore, in the present study, we investigated the effect of resveratrol in 3D gelatin scaffold cells to understand its neuroprotective effects on NF-κB signaling, NLRP3 inflammasome, and oxidative stress under OGD conditions. Here, we show that resveratrol improves the expression levels of cell viability, inflammatory cytokines (TNF-α, IL-1β, and IL-18), NF-κB signaling, and NLRP3 inflammasome, that OGD increases. In addition, resveratrol rescued oxidative stress, nuclear factor-erythroid 2 related factor 2 (Nrf2), and Nrf2 downstream antioxidant target genes (e.g., SOD, Gpx GSH, catalase, and HO-1). Treatment with resveratrol can significantly normalize OGD-induced changes in SH-SY5Y cell inflammation, oxidative stress, and oxidative defense gene expression; however, these resveratrol protective effects are affected by AMPK antagonists (Compounds C) blocking. These findings improve our understanding of the mechanism of the AMPK-dependent protective effect of resveratrol under 3D OGD-induced inflammation and oxidative stress-mediated cerebral ischemic stroke conditions.

The Utilization of Physiologically Active Molecular Components of Grape Seeds and Grape Marc

Nutritional interventions may highly contribute to the maintenance or restoration of human health. Grapes (Vitis vinifera) are one of the oldest known beneficial nutritional components of the human diet. Their high polyphenol content has been proven to enhance human health beyond doubt in statistics-based public health studies, especially in the prevention of cardiovascular disease and cancer. The current review concentrates on presenting and classifying polyphenol bioactive molecules (resveratrol, quercetin, catechin/epicatechin, etc.) available in high quantities in Vitis vinifera grapes or their byproducts. The molecular pathways and cellular signaling cascades involved in the effects of these polyphenol molecules are also presented in this review, which summarizes currently available in vitro and in vivo experimental literature data on their biological activities mostly in easily accessible tabular form. New molecules for different therapeutic purposes can also be synthesized based on existing polyphenol compound classes available in high quantities in grape, wine, and grape marc. Therefore an overview of these molecular structures is provided. Novel possibilities as dendrimer nanobioconjugates are reviewed, too. Currently available in vitro and in vivo experimental literature data on polyphenol biological activities are presented in easily accessible tabular form. The scope of the review details the antidiabetic, anticarcinogenic, antiviral, vasoprotective, and neuroprotective roles of grape-origin flavonoids. The novelty of the study lies in the description of the processing of agricultural by-products (grape seeds and skins) of industrial relevance, and the detailed description of the molecular mechanisms of action. In addition, the review of the clinical therapeutic applications of polyphenols is unique as no summary study has yet been done.

Effect of drying methods on nutritional constitutes of fermented grape residue

One of the biggest hurdles faced by the wine industry is the disposal of residual biomass generated after vinification. Although this residue is biodegradable, it constitutes a potential source of environmental pollutants. To alleviate this issue, this biomass may be used in alternative applications; for example, it may be transformed into an enriched flour that can be used to improve the nutrient content in different foods. In this study, were evaluated the effects of drying processes on the relevant nutritional components in dry extracts obtained from the residue of fermented grape pomace. The concentrations of phenolic compounds and anthocyanins were higher when drying the flour by the traditional oven procedure than by freeze-drying. The highest difference (approximately 40%) was observed for tannin compounds. Therefore, drying in an oven is recommended due to the lower loss of bioactive compounds, in addition to being simple and cheap.

Synthesis, Antioxidant, and Antihypoxia Activities of 6,7,8,4′-Tetrahydroxyisoflavone and 6,7,8,3′,4′-Pentahydroxyisoflavone

In the present study, 6,8-dihydroxydaidzein (6,8-DHD or 6,7,8,4′-tetrahydroxyisoflavone) and 6,8,3′-trihydroxydaidzein (6,8,3′-THD or 6,7,8,3′,4′-pentahydroxyisoflavone) were synthesized via a facile and efficient way using commercially available formononetin as starting material. Their structures were confirmed using spectroscopic analyses (infrared, nuclear magnetic resonance, and mass spectrometry). The purity was checked by ultra-high performance liquid chromatography. Their antioxidant activities were evaluated via 1,1-diphenyl-2-picrylhydrazyl radical scavenging assay and reducing power assay using ascorbic acid (vitamin C) as a reference compound. The antihypoxia capacity was determined by a hypoxia injury model in PC12 cells. Our study revealed that 6,8-DHD and 6,8,3′-THD exhibited higher antioxidant activities than that of vitamin C and could protect PC12 cells against hypoxia-induced damage. These results indicate that 6,8-DHD and 6,8,3′-THD are excellent antioxidant agents and could be used for alleviating injury induced by hypoxia.

Protective Effect of Resveratrol against Hypoxia-Induced Neural Oxidative Stress

Oxidative stress plays an important role in brain aging and in neurodegenerative diseases. New therapeutic agents are necessary to cross the blood–brain barrier and target disease pathogenesis without causing disagreeable side effects. Resveratrol (RSV) may act as a neuroprotective compound, but little is known about its potential in improving the cognitive and metabolic aspects that are associated with neurodegenerative diseases. The objective of this study was to investigate the protective effects and the underlying mechanisms of RSV against hypoxia-induced oxidative stress in neuronal PC12 cells. For the induction of the hypoxia model, the cells were exposed to oxygen-deprived gas in a hypoxic chamber. Cell cycle and apoptosis were analyzed by a fluorescence activated cell sorting (FACS) analysis. The intracellular reactive oxygen species (ROS) level was analyzed by using dichlorodihydrofluorescein diacetate (DCFDA) and 5-(and-6)-chloromethyl-2’,7’-dichlorodihydrofluorescein diacetate, acetyl ester (CM-H2DCFDA) tests. The expression of activated caspase-3, -9, Bcl-2, Bax, p53, and SOD was investigated by a Western blot analysis. We found that hypoxia reduced PC12 viability by inducing apoptosis, while RSV treatment attenuated the ROS-induced damage by reducing caspase-3, -9, and the Bax/Bcl-2 ratio. The RSV treated groups were found to improve cellular health, with a 7.41% increase in the S phase population in the 10 µM group, compared to the control. Hence, RSV has a protective effect in neuronal cells and may halt the cell cycle in the G1/S phase to repair the intracellular damage. Therefore, RSV could be a good candidate to act as an antioxidant and promising preventive therapeutic agent in neurodegenerative diseases for personalized medicine.

Selenium and Resveratrol Attenuated Diabetes Mellitus-Mediated Oxidative Retinopathy and Apoptosis via the Modulation of TRPM2 Activity in Mice

Diabetes mellitus induces optic nerve injury via the excessive generation of mitochondria reactive free oxygen radical (mitROS). TRPM2 channel is activated by mitROS, although it is inhibited by selenium (Se) and resveratrol (RSV). The activation of TRPM2 induces apoptosis and oxidative injury in the optic nerve. The inhibition of TRPM2 may decrease the optic nerve injury action of diabetes mellitus after the treatments of Se and RSV. Present study aimed to investigate the protective actions of Se and RSV on the excessive Ca²⁺ influx and mitROS generation-mediated optic nerve oxidative injury via the modulation of TRPM2. Fifty-six C57BL/6j male mice were divided into seven groups as control, Se, RSV, streptozotocin (STZ), STZ + Se, STZ + RSV, and STZ + Se + RSV. The STZ-mediated stimulation of TRPM2 increased the cytosolic Ca²⁺, lipid peroxidation, mitROS, cytosolic ROS, apoptosis, caspase-3, caspase-8, and caspase-9 concentrations in the mice, although their concentrations were decreased in the optic nerve by the treatments of Se and RSV. The STZ-induced decrease of optic nerve viability, glutathione, glutathione peroxidase, vitamin A, and vitamin E concentrations was also upregulated by the treatments of Se and RSV. The STZ-induced increase of TRPM2, PARP-1, caspase-3, and caspase-9 protein band expressions was diminished by the treatments of Se and RSV. In conclusion, STZ induced the optic nerve oxidative injury and apoptosis via the upregulation of TRPM2 stimulation, although the treatments of Se and RSV decreased the injury and apoptosis via the downregulation of TRPM2 activity.

A novel antagonist of TRPM2 and TRPV4 channels: Carvacrol

The overload cytosolic free Ca²⁺ (cCa²⁺) influx-mediated excessive generation of oxidative stress in the pathophysiological conditions induces neuronal and cellular injury via the activation of cation channels. TRPM2 and TRPV4 channels are activated by oxidative stress, and their specific antagonists have not been discovered yet. The antioxidant and anti-Covid-19 properties of carvacrol (CARV) were recently reported. Hence, I suspected possible antagonist properties of CARV against oxidative stress (OS)/ADP-ribose (ADPR)-induced TRPM2 and GSK1016790A (GSK)-mediated TRPV4 activations in neuronal and kidney cells. I investigated the antagonist role of CARV on the activations of TRPM2 and TRPV4 in SH-SY5Y neuronal, BV-2 microglial, and HEK293 cells. The OS/ADPR and GSK in the cells caused to increase of TRPM2/TRPV4 current densities and overload cytosolic free Ca²⁺ (cCa²⁺) influx with an increase of mitochondrial membrane potential, cytosolic (cROS), and mitochondrial (mROS) ROS. The changes were not observed in the absence of TRPM2 and TRPV4 or the presence of Ca²⁺ free extracellular buffer and PARP-1 inhibitors (PJ34 and DPQ). When OS-induced TRPM2 and GSK-induced TRPV4 activations were inhibited by the treatment of CARV, the increase of cROS, mROS, lipid peroxidation, apoptosis, cell death, cCa²⁺ concentration, caspase -3, and caspase -9 levels were restored via upregulation of glutathione and glutathione peroxidase. In conclusion, the treatment of CARV modulated the TRPM2 and TRPV4-mediated overload Ca²⁺ influx and may provide an avenue for protecting TRPM2 and TRPV4-mediated neurodegenerative diseases associated with the increase of mROS and cCa²⁺. The possible TRPM2 and TRPV4 blocker action of carvacrol (CARV) via the modulation oxidative stress and apoptosis in the SH-SY5Y neuronal cells. TRPM2 is activated by DNA damage-induced (via PARP-1 activation) ADP-ribose (ADPR) and reactive oxygen species (ROS) (H₂O₂), although it is inhibited by nonspecific inhibitors (ACA and 2-APB). TRPV4 is activated by the treatments of GSK1016790A (GSK), although it is inhibited by a nonspecific inhibitor (ruthenium red, RuRe). The treatment of GSK induces excessive generation of ROS. The accumulation of free cytosolic Ca²⁺ (cCa²⁺) via the activations of TRPM2 and TRPV4 in the mitochondria causes the increase of mitochondrial membrane depolarization (ΔΨm). In turn, the increase of ΔΨm causes the excessive generation of ROS. The TRPM2 and TRPV4-induced the excessive generations of ROS result in the increase of apoptosis and cell death via the activations of caspase -3 (Casp-3) and caspase -9 (Casp-9) in the neuronal cells, although their oxidant actions decrease the glutathione (GSH) and glutathione peroxidase (GSHPx) levels. The oxidant and apoptotic adverse actions of TRPM2 and TRPV4 are modulated by the treatment of CARV.

Pharmacological Modulation of TRPM2 Channels via PARP Pathway Leads to Neuroprotection in MPTP-induced Parkinson's Disease in Sprague Dawley Rats

Transient receptor potential melastatin-2 (TRPM2) channels are cation channels activated by oxidative stress and ADP-ribose (ADPR). Role of TRPM2 channels has been postulated in several neurological disorders, but, it has not been explored in animal models of Parkinson's disease (PD). Thus, the role of TRPM2 and its associated poly (ADPR) polymerase (PARP) signaling pathways were investigated in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD rat model using TRPM2 inhibitor, 2-aminoethyl diphenyl borinate (2-APB), and PARP inhibitor, N-(6-Oxo-5,6-dihydrophenanthridin-2-yl)-(N,N-dimethylamino) acetamide hydrochloride (PJ-34). PD was induced by using a bilateral intranigral administration of MPTP in rats, and different parameters were evaluated. An increase in oxidative stress was observed, leading to locomotor and cognitive deficits in the PD rats. PD rats also showed an increased TRPM2 expression in the striatum and mid-brain accompanied by reduced expression of tyrosine hydroxylase (TH) in comparison to sham animals. Intraperitoneal administration of 2-APB and PJ-34 led to an improvement in the locomotor and cognitive deficits in comparison to MPTP-induced PD rats. These improvements were accompanied by a reduction in the levels of oxidative stress and an increase in TH levels in the striatum and mid-brain. In addition, these pharmacological interventions also led to a decrease in the expression of TRPM2 in PD in the striatum and mid-brain. Our results provide a rationale for the development of potent pharmacological agents targeting the TRPM2-PARP pathway to provide therapeutic benefits for the treatment of neurological diseases like PD.

Reduction of Deuterium Level Supports Resistance of Neurons to Glucose Deprivation and Hypoxia: Study in Cultures of Neurons and on Animals

The effect of a reduced deuterium (D) content in the incubation medium on the survival of cultured neurons in vitro and under glucose deprivation was studied. In addition, we studied the effect of a decrease in the deuterium content in the rat brain on oxidative processes in the nervous tissue, its antioxidant protection, and training of rats in the T-shaped maze test under hypoxic conditions. For experiments with cultures of neurons, 7-8-day cultures of cerebellar neurons were used. Determination of the rate of neuronal death in cultures was carried out using propidium iodide. Acute hypoxia with hypercapnia was simulated in rats by placing them in sealed vessels with a capacity of 1 L. The effect on oxidative processes in brain tissues was assessed by changes in the level of free radical oxidation and malondialdehyde. The effect on the antioxidant system of the brain was assessed by the activity of catalase. The study in the T-maze was carried out in accordance with the generally accepted methodology, the skill of alternating right-sided and left-sided loops on positive reinforcement was developed. This work has shown that a decrease in the deuterium content in the incubation medium to a level of -357‱ has a neuroprotective effect, increasing the survival rate of cultured neurons under glucose deprivation. When exposed to hypoxia, a preliminary decrease in the deuterium content in the rat brain to -261‱ prevents the development of oxidative stress in their nervous tissue and preserves the learning ability of animals in the T-shaped maze test at the level of the control group. A similar protective effect during the modification of the 2H/1H internal environment of the body by the consumption of DDW can potentially be used for the prevention of pathological conditions associated with the development of oxidative stress with damage to the central nervous system.

Intracellular hydrogen peroxide produced by 6-hydroxydopamine is a trigger for nigral dopaminergic degeneration of rats via rapid influx of extracellular Zn2

To elucidate the mechanism and significance of 6-hydroxydopamine (6-OHDA)-induced Zn²⁺ toxicity, which is involved in neurodegeneration in the substantia nigra pars compacta (SNpc) of rats, we postulated that intracellular hydrogen peroxide (H₂O₂) produced by 6-OHDA is a trigger for intracellular Zn²⁺ dysregulation in the SNpc. Intracellular H₂O₂ level elevated by 6-OHDA in the SNpc was completely inhibited by co-injection of GBR 13069 dihydrochloride (GBR), a dopamine reuptake inhibitor, suggesting that 6-OHDA taken up through dopamine transporters produces H₂O₂ in the intercellular compartment of dopaminergic neurons. When the SNpc was perfused with H₂O₂, glutamate accumulated in the extracellular compartment and the accumulation was inhibited in the presence of N-(p-amylcinnamoyl)anthranilic acid (ACA), a blocker of the transient receptor potential melastatin 2 (TRPM2) channels. In addition to 6-OHDA, H₂O₂ also induced intracellular Zn²⁺ dysregulation via AMPA receptor activation followed by nigral dopaminergic degeneration. Furthermore, 6-OHDA-induced nigral dopaminergic degeneration was completely inhibited by co-injection of either HYDROP, an intracellular H₂O₂ scavenger or GBR into the SNpc. The present study indicates that H₂O₂ is produced by 6-OHDA taken up through dopamine transporters in the SNpc, is retrogradely transported to presynaptic glutamatergic terminals, activates TRPM2 channels, accumulates glutamate in the extracellular compartment, and induces intracellular Zn²⁺ dysregulation via AMPA receptor activation, resulting in nigral dopaminergic degeneration prior to movement disorder. It is likely that intracellular H₂O₂, but not extracellular H₂O₂, is a key trigger for nigral dopaminergic degeneration via intracellular Zn²⁺ dysregulation.

Olive oil and wine as source of multi-target agents in the prevention of Alzheimer disease

Olive oil and wine are consumed daily worldwide and they constitute the fundamental pillars of the healthy Mediterranean diet. Polyphenolic compounds, naturally present in both olive oil and wine, are responsible for their beneficial properties. Current studies have shown the neuroprotective effects of polyphenols independently of their well-known antioxidant action. In this work, we have focused on reviewing the protective effect of polyphenols from extra virgin olive oil and wine in Alzheimer´s disease (AD), to emphasize that both food could be a possible therapeutic tool. Beneficial effects have been described in β-aggregation, neurofibrillary tangles, autophagy and mitochondrial function, as well as in cerebral insulin resistance. Furthermore, to date a harmful dose has not been described. Both preclinical and clinical works demonstrate that polyphenols act on neuropathological and cognitive disorders of AD, preventing or stopping the onset of this devastating disease. However, there are certain limitations in these studies, since it is very difficult to research diseases that lead to cognitive impairment. Although all the findings obtained are very encouraging, more studies should be carried out to use the polyphenols from olive oil and wine as therapeutic agents in the progression of AD. Therefore, more longitudinal studies in humans with a homogeneous cohort of patients are necessary to corroborate the efficacy of these nutraceuticals, as well as analyze which is the most appropriate dose for this purpose.

Design, synthesis and biological activities of benzo[d]imidazo[1,2-a]imidazole derivatives as TRPM2-specfic inhibitors

Transient receptor potential melastatin 2 (TRPM2) channel is associated with ischemia/reperfusion injury, inflammation, cancer and neurodegenerative diseases. However, the lack of specific inhibitors impedes the development of TRPM2 targeted therapeutic agents. To develop a selective TRPM2 inhibitor, three-dimensional similarity-based screening strategy was employed using the energy-minimized conformation of non-selective TRPM2 inhibitor 2-APB as the query structure, which resulted in the discovery of a novel tricyclic TRPM2 inhibitor Z-4 with benzo[d]imidazo[1,2-a]imidazole skeleton. A series of Z-4 derivatives were subsequently synthesized and evaluated using calcium imaging and electrophysiology approaches. Among them, preferred compounds ZA10 and ZA18 inhibited the TRPM2 channel with micromolar half-maximal inhibitory concentration values and exhibited TRPM2 selectivity over the TRPM8 channel, TRPV1 channel, InsP₃ receptor and Orai channel. The analysis of structure-activity relationship provides valuable insights for further development of selective TRPM2 inhibitors. Neuroprotection assay showed that ZA10 and ZA18 could effectively reduce the mortality of SH-SY5Y cells induced by H₂O₂. These findings enrich the structure types of existing TRPM2 inhibitors and might provide a new tool for the study of TRPM2 function in Reactive oxygen species (ROS) -related diseases.

Knockdown of transient receptor potential melastatin 2 reduces renal fibrosis and inflammation by blocking transforming growth factor-β1-activated JNK1 activation in diabetic mice

BACKGROUND

Diabetic nephropathy is a major complication of diabetes. We explore the protective effect of TRPM2 knockdown on the progression of diabetic nephropathy.

METHODS

A type 2 diabetes animal model was established in C57BL/6N mice by long-term high-fat diet (HFD) feeding combined with a single injection of 100 mg/kg streptozotocin (STZ). Genetic knockdown of TRPM2 in mouse kidneys was accomplished by the intravenous injection via the tail vein of adeno-associated virus type 2 carrying TRPM2 shRNA.

RESULTS

Mice with HFD/STZ-induced diabetes exhibited kidney dysfunction, as demonstrated by increased blood creatinine and urea nitrogen levels, accompanied by glomerulus derangement, tubule damage and extracellular matrix deposition in the interstitium. The protein expression of TRPM2, transforming growth factor-β1 (TGF-β1), connective tissue growth factor, α-smooth muscles actin, fibronectin, collagen I and collagen III, and the mRNA expression and contents of inflammatory factors, including interleukin-1β, interleukin-6, interferon-α, tumour necrosis factor -α and monocyte chemotactic protein -1, were significantly elevated in the renal tissues of the HFD/STZ-induced diabetes group compared to those of the two control groups. Furthermore, fluorescent staining of TRPM2 was markedly increased in the renal tubular epithelial cells from diabetic mice. Knockdown of TRPM2 significantly attenuated HFD/STZ-induced renal inflammatory responses and fibrosis, which was accompanied by activation of TGF-β1-activated c-Jun N-terminal protein kinase-1 (JNK1) signalling. JNK1 inactivation reversed hyperglycaemia-induced fibrosis and inflammation in HK-2 cells.

CONCLUSION

TRPM2 silencing significantly attenuated fibrosis and inflammation in the kidneys of mice with HFD/STZ-induced diabetes, which was largely achieved via the inhibition of TGF-β1-activated JNK1 activation.

Resveratrol Mitigates Cerebral Ischemic Injury by Altering Levels of Trace Elements, Toxic Metal, Lipid Peroxidation, and Antioxidant Activity

Cerebral ischemia causes increased oxidative stress due to the overproduction of reactive oxygen species. The polyphenol compound resveratrol exerts neuroprotective effects through its antioxidant and anti-inflammatory abilities. The trace elements magnesium (Mg), zinc (Zn), and selenium (Se) also exert antioxidant properties. This study mainly investigates whether the neuroprotective effect of resveratrol during cerebral ischemia is related to its modulation of the concentrations of trace element and toxic metal lead (Pb). Experimental rats were administered resveratrol (20 mg/kg) once daily for 10 consecutive days. Cerebral ischemia was surgically induced via ligation of the right middle cerebral artery and right common carotid artery for 1 h. Brain cortex tissues were homogenized, and the supernatants were harvested for biochemical analysis. Experimental results showed that rats pretreated with resveratrol before cerebral ischemia had significantly higher trace element concentrations of Mg, Zn, and Se and higher antioxidant activity (superoxide dismutase and catalase) in the brain cortex as compared to untreated cerebral ischemia rats. Conversely, resveratrol pretreatment markedly attenuated lipid peroxidation and concentrations of the toxic metal Pb as compared to untreated cerebral ischemic rats. Altogether, the findings of this study highlight that the mechanism underlying the neuroprotective effect of resveratrol involves modulation of the brain levels of trace elements, toxic metal lead, lipid peroxidation, and antioxidant activity.

The involvement of TRPV4 on the hypoxia-induced oxidative neurotoxicity and apoptosis in a neuronal cell line: Protective role of melatonin

The hypoxia (HYPX)-mediated excessive generation of mitochondrial free reactive oxygen species (mROS) and the overload Ca²⁺ influx via the inhibition of TRPV4 are controlled by the treatment of antioxidants. However, the molecular mechanisms underlying melatonin (MLT)'s neuroprotection remains elusive. We investigated the role of MLT via modulation of TRPV4 on oxidative neurodegeneration and death in SH-SY5Y neuronal cells. The SH-SY5Y cells were divided into five groups as follows: control, MLT (1 mM for 2 h), HYPX (200 μM CoCl₂ for 24 h), HYPX + MLT, and HYPX + TRPV4 blockers (ruthenium red-1 μM for 30 min). The HYPX caused to the increase of TRPV4 current density and overload Ca²⁺ influx with an increase of mitochondrial membrane potential and mROS generation. The changes were not observed in the absence of TRPV4. When HYPX exposure and TRPV4 agonist (GSK1016790A)-induced TRPV4 activity were inhibited by the treatment of ruthenium red or MLT, the increase of mROS, lipid peroxidation, apoptosis, Zn²⁺ concentrations, TRPV4, caspase -3, caspase -9, Bax, and Bcl-2 expressions were restored via upregulation of reduced glutathione, glutathione peroxidase, and total antioxidant status. The levels of apoptosis and cell death in the cells were enriched with increases of caspase -3 and -9 activations, although they were decreased by MLT treatment. In conclusion, the treatment of MLT modulates HYPX-mediated mROS, apoptosis, and TRPV4-mediated overload Ca²⁺ influx and may provide an avenue for protecting HYPX-mediated neurological diseases associated with the increase of mROS, Ca²⁺, and Zn²⁺ concentration.

Resveratrol Protects against Cerebral Ischemic Injury via Restraining Lipid Peroxidation, Transition Elements, and Toxic Metal Levels, but Enhancing Anti-Oxidant Activity

Cerebral ischemia is related to increased oxidative stress. Resveratrol displays anti-oxidant and anti-inflammatory properties. The transition elements iron (Fe) and copper (Cu) are indispensable for the brain but overload is deleterious to brain function. Aluminum (Al) and arsenic (As) are toxic metals that seriously threaten brain health. This study was conducted to elucidate the correlation of the neuroprotective mechanism of resveratrol to protect cerebral ischemic damage with modulation of the levels of lipid peroxidation, anti-oxidants, transition elements, and toxic metals. Experimentally, 20 mg/kg of resveratrol was given once daily for 10 days. The cerebral ischemic operation was performed via occlusion of the right common carotid artery together with the right middle cerebral artery for 60 min followed by homogenization of the brain cortex and collection of supernatants for biochemical analysis. In the ligation group, levels of malondialdehyde, Fe, Cu, Al, and As increased but those of the anti-oxidants superoxide dismutase and catalase decreased. Pretreating rats with resveratrol before ischemia significantly reversed these effects. Our findings highlight the association of overload of Fe, Cu, As, and Al with the pathophysiology of cerebral ischemia. In conclusion, resveratrol protects against cerebral ischemic injury via restraining lipid peroxidation, transition elements, and toxic metals, but increasing anti-oxidant activity.

Hypoxia-inducible factor 1-alpha acts as a bridge factor for crosstalk between ERK1/2 and caspases in hypoxia-induced apoptosis of cementoblasts

Hypoxia‐induced apoptosis of cementoblasts (OCCM‐30) may be harmful to orthodontic treatment. Hypoxia‐inducible factor 1‐alpha (HIF‐1α) mediates the biological effects during hypoxia. Little is known about the survival mechanism capable to counteract cementoblast apoptosis. We aimed to investigate the potential roles of HIF‐1α, as well as the protein‐protein interactions with ERK1/2, using an in‐vitro model of chemical‐mimicked hypoxia and adipokines. Here, OCCM‐30 were co‐stimulated with resistin, visfatin or ghrelin under CoCl₂‐mimicked hypoxia. In‐vitro investigations revealed that CoCl₂‐induced hypoxia triggered activation of caspases, resulting in apoptosis dysfunction in cementoblasts. Resistin, visfatin and ghrelin promoted the phosphorylated ERK1/2 expression in OCCM‐30 cells. Furthermore, these adipokines inhibited hypoxia‐induced apoptosis at different degrees. These effects were reversed by pre‐treatment with ERK inhibitor (FR180204). In cells treated with FR180204, HIF‐1α expression was inhibited despite the presence of three adipokines. Using dominant‐negative mutants of HIF‐1α, we found that siHIF‐1α negatively regulated the caspase‐8, caspase‐9 and caspase‐3 gene expression. We concluded that HIF‐1α acts as a bridge factor in lengthy hypoxia‐induced apoptosis in an ERK1/2‐dependent pathway. Gene expressions of the caspases‐3, caspase‐8 and caspase‐9 were shown to be differentially regulated by adipokines (resistin, visfatin and ghrelin). Our study, therefore, provides evidence for the role of ERK1/2 and HIF‐1α in the apoptotic response of OCCM‐30 cells exposed to CoCl₂‐mimicked hypoxia, providing potential new possibilities for molecular intervention in obese patients undergoing orthodontic treatment.

The Potential Role of Polyphenols in Oxidative Stress and Inflammation Induced by Gut Microbiota in Alzheimer's Disease

Gut microbiota (GM) play a role in the metabolic health, gut eubiosis, nutrition, and physiology of humans. They are also involved in the regulation of inflammation, oxidative stress, immune responses, central and peripheral neurotransmission. Aging and unhealthy dietary patterns, along with oxidative and inflammatory responses due to gut dysbiosis, can lead to the pathogenesis of neurodegenerative diseases, especially Alzheimer's disease (AD). Although the exact mechanism between AD and GM dysbiosis is still unknown, recent studies claim that secretions from the gut can enhance hallmarks of AD by disturbing the intestinal permeability and blood-brain barrier via the microbiota-gut-brain axis. Dietary polyphenols are the secondary metabolites of plants that possess anti-oxidative and anti-inflammatory properties and can ameliorate gut dysbiosis by enhancing the abundance of beneficial bacteria. Thus, modulation of gut by polyphenols can prevent and treat AD and other neurodegenerative diseases. This review summarizes the role of oxidative stress, inflammation, and GM in AD. Further, it provides an overview on the ability of polyphenols to modulate gut dysbiosis, oxidative stress, and inflammation against AD.

The Role of TRPM2 in Endothelial Function and Dysfunction

The transient receptor potential (TRP) melastatin-like subfamily member 2 (TRPM2) is a non-selective calcium-permeable cation channel. It is expressed by many mammalian tissues, including bone marrow, spleen, lungs, heart, liver, neutrophils, and endothelial cells. The best-known mechanism of TRPM2 activation is related to the binding of ADP-ribose to the nudix-box sequence motif (NUDT9-H) in the C-terminal domain of the channel. In cells, the production of ADP-ribose is a result of increased oxidative stress. In the context of endothelial function, TRPM2-dependent calcium influx seems to be particularly interesting as it participates in the regulation of barrier function, cell death, cell migration, and angiogenesis. Any impairments of these functions may result in endothelial dysfunction observed in such conditions as atherosclerosis or hypertension. Thus, TRPM2 seems to be an attractive therapeutic target for the conditions connected with the increased production of reactive oxygen species. However, before the application of TRPM2 inhibitors will be possible, some issues need to be resolved. The main issues are the lack of specificity, poor membrane permeabilization, and low stability in in vivo conditions. The article aims to summarize the latest findings on a role of TRPM2 in endothelial cells. We also show some future perspectives for the application of TRPM2 inhibitors in cardiovascular system diseases.

The effects of neuronal cell differentiation on TRPM7, TRPM8 and TRPV1 channels in the model of Parkinson's disease

Transient Receptor Potential Melastatin-like 7 (TRPM7), Transient Receptor Potential Melastatin-like 8 (TRPM8) and Transient Receptor Potential Vanilloid-like 1 (TRPV1) channels are expressed in neurological tissues such as brain cortex, dorsal root ganglion and hippocampal neurons and involved in several neurological diseases. The SH-SY5Y neuronal cell line is frequently used as a cellular model of neurodegenerative diseases including Parkinson's disease. The differentiated SH-SY5Y cells have much neuronal structure, function and exaggerated neuronal marker expression. However, we have less data about how differentiation induces TRP channel expression and how TRP channels have a role in cellular functions in Parkinson's disease model in SH-SY5Y cells. Hence, we aimed to investigate the effects of differentiation phenomena on TRPM7, TRPM8 and TRPV1 cation channel expression and related Ca²⁺ signaling. We also made some other analysis to elucidate TRP channels' function in MPP induced apoptosis, mitochondrial membrane potential levels, intracellular reactive oxygen species production, caspase 3 and caspase 9 enzyme activities in differentiated or undifferentiated SH-SY5Y neuronal cells. Herein we concluded that TRPM7, TRPM8 and TRPV1 cation channels have pivotal effects on differentiation and MPP induced Parkinson's disease model in SH-SY5Y cells.

TRP channels in COVID-19 disease: Potential targets for prevention and treatment

Coronavirus disease 2019 [COVID-19] is a global health threat caused by severe acute respiratory syndrome coronavirus 2 [SARS-CoV2] that requires two proteins for entry: angiotensin-converting enzyme 2 [ACE2] and -membrane protease serine 2 [TMPRSS2]. Many patients complain from pneumonia, cough, fever, and gastrointestinal (GI) problems. Notably, different TRP channels are expressed in various tissues infected by SARS-CoV-2. TRP channels are cation channels that show a common architecture with high permeability to calcium [Ca²⁺] in most sub-families. Literature review shed light on the possible role of TRP channels in COVID-19 disease. TRP channels may take part in inflammation, pain, fever, anosmia, ageusia, respiratory, cardiovascular, GI and neurological complications related to COVID-19. Also, TRP channels could be the targets for many active compounds that showed effectiveness against SARS-CoV-2. Desensitization or blocking TRP channels by antibodies, aptamers, small molecules or venoms can be an option for COVID-19 prevention and future treatment. This review provides insights into the involvement of TRP channels in different symptoms and mechanisms of SARS-CoV-2 , potential treatments targeting these channels and highlights missing gaps in literature.

Impact of dietary polyphenols on neuroinflammation-associated disorders

Neurodegenerative disorders like Alzheimer's, Parkinson's, and associated dementia typically originate with altered protein folding and aggregation of their β structures in the neurons. This self-aggregation leads to glial activation in the brain, causing neuroinflammation and leads to neuronal death. According to statistics provided by WHO, there are around 50 million people with dementia worldwide and every year, 10 million more cases are projected to increase. Also, around 5-8 percentage of people who are aged above 60 globally has dementia or associated disorders. Over 82 million in 2030 and 152 in 2050 are expected to have dementia. Most of these patients fall into low-middle-income countries which makes it even more essential to find an affordable and effective treatment method. Polyphenols of different origin are studied for their potential role as anti-neuro-inflammatory molecules. This review would summarize recent advances in three widely researched dietary polyphenols projected as potential therapeutic agents for disorders like Alzheimer's, Parkinson's, etc. They are Resveratrol, Catechins, and Tannins. The review would discuss the recent advances and challenges in using these polyphenols using specific examples as potential therapeutic agents against neuroinflammation associated disorders. An abstract of neuroinflammation-associated events and the effects by selected polyphenols.

Pregabalin reduces oxaliplatin-induced oxidative neurotoxicity through modulation of TRPV1 channels in DBTRG neuronal cell line

As a member of the platinum drug group, oxaliplatin (OXAL) is used to treat brain tumors, although its use is limited through excessive calcium ion (Ca) influx and reactive oxygen species (ROS) production in neurons. The Ca permeable transient receptor potential vanilloid 1 (TRPV1) channel is activated by ROS, and its activity might be reduced by the antioxidant property of pregabalin (PREGAB). This study aimed to investigate the protective action of PREGAB against OXAL-induced oxidative neurotoxicity in human glioblastoma (DBTRG) cells. The DBTRG cells were divided into four treatment groups: control, PREGAB (500 µM for 1 h), OXAL (25 µM for 24 h), and PREGAB + OXAL. In the laser confocal microscope and plate reader analyses, apoptosis, mitochondrial membrane depolarization (JC-1), cell death (propidium iodide/Hoechst rate), and ROS-level production increased by activating TRPV1 in the cells using the OXAL treatment, although the cell viability values decreased. However, these values were recovered in the PREGAB + OXAL group using PREGAB and TRPV1 inhibitor (capsazepine) treatments. In the patch-clamp analyses, OXAL-induced TRPV1 channel activation in the OXAL group also decreased in the PREGAB + OXAL group using the PREGAB and capsazepine treatments. In conclusion, the apoptosis and oxidant actions of OXAL were increased by activation of the TRPV1 channel, but this effect was diminished by the PREGAB treatment. PREGAB treatment has the potential to be an effective strategy in the treatment of OXAL-induced oxidative neurotoxicity.

Deletion of Mitochondrial Translocator Protein (TSPO) Gene Decreases Oxidative Retinal Pigment Epithelial Cell Death via Modulation of TRPM2 Channel

Simple Summary

18 kDa mitochondrial translocator protein (TSPO) is a mitochondria protein of the cellular outer membrane in the mitochondria of several cells, including ARPE19 is TSPO. Accumulating evince indicates that the presence of TSPO participated the modulations of Ca²⁺ homeostasis and mitochondrial free reactive oxygen species (fROS) generation. The deletion of TSPO gene provides to study the action of TSPO on the levels of apoptosis, ADP-ribose (ADPR), mitochondria-fROS (Mito-fROS), and apoptosis via the stimulation of Ca²⁺ permeable channels in the models of cell culture. The stimulations of oxidative stress and ADPR induce the activation of TRPM2 in the ARPE19. For clarifying the involvement of TSPO in retinal human diseases, we used the ARPE19 human cell culture model. The current results demonstrated that the deletion of TSPO induces the regulation of TRPM2 in the TSPO gene knockout ARPE19 (ARPE19-KO) In fact, the present results show that the presence of TSPO increased the upregulations of apoptosis and mitochondria oxidative cytotoxicity values via stimulation of TRPM2 in the ARPE19. Nevertheless, the blockages of PARP-1 (PJ34 and DPQ) and TRPM2 (2APB and ACA) downregulated the values of cell death and oxidative cytotoxicity in the ARPE19. In summary, present results clearly demonstrate that the deletion of TSPO decreases mitochondrial oxidative cytotoxicity-mediated cell death via the modulation of TRPM2 in the ARPE19.

Abstract

The current results indicated the possible protective actions of 18 kDa mitochondrial translocator protein (TSPO) deletion on TRPM2 stimulation, mitochondrial free ROS (Mito-fROS) and apoptotic harmful actions in the cells of adult retinal pigment epithelial19 (ARPE19). There was a direct relationship between TSPO and the disease of age-related macular degeneration. The nature of TSPO implicates upregulation of Mito-fROS and apoptosis via the activation of Ca²⁺ channels in ARPE19, although deletion of TSPO gene downregulates the activation. The decrease of oxidative cytotoxicity and apoptosis might induce in TSPO gene deleted cells by the inhibition of Mito-fROS and PARP-1 activation-induced TRPM2 cation channel activation. The ARPE19 cells were divided into two main groups as TSPO expressing (ARPE19) and non-expressing cells (ARPE19-KO). The levels of caspase -3 (Casp -3), caspase -9 (Casp -9), apoptosis, Mito-fROS, TRPM2 current and intracellular free Ca²⁺ were upregulated in the ARPE19 by the stimulations of H₂O₂ and ADP-ribose, although their levels were downregulated in the cells by the modulators of PARP-1 (DPQ and PJ34), TRPM2 (ACA and 2APB) and glutathione. However, the H₂O₂ and ADP-ribose-mediated increases were not observed in the ARPE19-KO. The expression levels of Bax, Casp -3, Casp -9 and PARP-1 were higher in the ARPE19 group as compared to the ARPE19-KO group. In summary, current results confirmed that TRPM2-mediated cell death and oxidative cytotoxicity in the ARPE19 cells were occurred by the presence of TSPO. The deletion of TSPO may be considered as a therapeutic way to TRPM2 activation-mediated retinal oxidative injury.

Interferon Gamma-Mediated Oxidative Stress Induces Apoptosis, Neuroinflammation, Zinc Ion Influx, and TRPM2 Channel Activation in Neuronal Cell Line: Modulator Role of Curcumin

Host defenses in the brain are modulated by the activation of several factors such as oxygen free radical species (ROS), Ca²⁺ influx, and TRPM2 activation, and they are well-known adverse factors in neurotoxicity and neurodegenerative diseases. Importantly, recent data indicated a protective action of curcumin (CRC) via inhibition of TRPM2 on the inflammation factors, ROS, and apoptosis in hypoxia-induced SH-SY5Y neuronal cells. However, the relationship between interferon gamma (IFNg) exposure and TRPM2 activation in the SH-SY5Y cells are not fully identified. The SH-SY5Y cells as a neuronal cell line model were used in several neuroinflammation studies. Hence, we used the SH-SY5Y cells in the current study, and they were divided into four main groups as control, CRC, IFNg, and IFNg+CRC. The data presented here indicate that IFNg induced excessive Ca²⁺ influx via activation of TRPM2. The IFNg treatment further increased cell death, cell debris amount, apoptosis, and cytokine generations (IL-1β, IL-6, and TNF-α) which were due to increased cytosolic and mitochondrial ROS generations as well as increased activations of caspase-3 and caspase-9. The expression levels of TRPM2, PARP-1, Bax, caspase-3, and caspase-9 were increased in the cells by the IFNg treatment. However, CRC treatment reduced the increase of expression levels, cytokine generations, caspase activations, ROS release, Ca²⁺ influx, cell death, and apoptosis levels via inhibition of TRPM2 in the SH-SY5Y cells that were treated with IFNg. Moreover, the treatment of TRPM2 blockers (ACA and 2-APB) potentiated the modulator effects of CRC. In conclusion, these results suggest that neuroinflammation via IFNg lead to the TRPM2 activation in the SH-SY5Y cells, whereas CRC prevents IFNg-mediated TRPM2 activation, cell death, and cytokine generations.

Involvement of TRPM2 Channel on Hypoxia-Induced Oxidative Injury, Inflammation, and Cell Death in Retinal Pigment Epithelial Cells: Modulator Action of Selenium Nanoparticles

Hypoxia (HYPX) in several eye diseases such as glaucoma and diabetic retinopathy causes oxidative cell death and inflammation. TRPM2 cation channel is activated by HYPX-induced ADP-ribose (ADPR) and oxidative stress. The protective role of selenium via inhibition of TRPM2 on the HYPX-induced oxidative cytotoxicity and inflammation values in the human kidney cell line was recently reported. However, the protective role of selenium nanoparticles (SeNP) on the values in the retinal pigment epithelial (ARPE-19) cells has not been clarified yet. In the current study, we investigated two subjects. First, we investigated the involvement of TRPM2 channel on the HYPX-induced oxidative injury, inflammation, and apoptosis in the ARPE-19 cells. Second, we investigated the protective role of SeNP via inhibition of TRPM2 channel on the HYPX-induced oxidative injury and apoptosis in the ARPE-19 cells. For the aims, the ARPE-19 cells were divided into four main groups as follows: Control (Ctr), SeNP (2.5 μg/ml for 24 h), HYPX (200 μM CoCl₂ for 24 h), and HYPX+SeNP. The TRPM2 current density and Ca²⁺ fluorescence intensity with an increase of mitochondrial membrane depolarization and oxygen free radical (OFR) generations were increased in the ARPE-19 cells by the treatment of HYPX. There was no increase of Ca²⁺ fluorescence intensity in the pre-treated cells with PARP-1 inhibitors (DPQ and PJ34) or in the presence of Ca²⁺-free extracellular buffer. When HYPX-induced TRPM2 activity was treated by SeNP and TRPM2 (2-APB and ACA) blockers, the increases of OFR generation, cytokine (TNF-α and IL-1β) levels, TRPM2, and PARP-1 expressions were restored. In conclusion, the exposure of HYPX caused mitochondrial oxidative cell cytotoxicity and cell death via TRPM2-mediated Ca²⁺ signaling and may provide an avenue for treating HYPX-induced retinal diseases associated with the excessive OFR and Ca²⁺ influx.

Nucleoredoxin Knockdown in SH-SY5Y Cells Promotes Cell Renewal

Nucleoredoxin (NXN) is a redox regulator of Disheveled and thereby of WNT signaling. Deficiency in mice leads to cranial dysmorphisms and defects of heart, brain, and bone, suggesting defects of cell fate determination. We used shRNA-mediated knockdown of NXN in SH-SY5Y neuroblastoma cells to study its impact on neuronal cells. We expected that shNXN cells would easily succumb to redox stress, but there were no differences in viability on stimulation with hydrogen peroxide. Instead, the proliferation of naïve shNXN cells was increased with a higher rate of mitotic cells in cell cycle analyses. In addition, basal respiratory rates were higher, whereas the relative change in oxygen consumption upon mitochondrial stressors was similar to control cells. shNXN cells had an increased expression of redox-sensitive heat shock proteins, Hsc70/HSPA8 and HSP90, and autophagy markers suggested an increase in autophagosome formation upon stimulation with bafilomycin and higher flux under low dose rapamycin. A high rate of self-renewal, autophagy, and upregulation of redox-sensitive chaperones appears to be an attractive anti-aging combination if it were to occur in neurons in vivo for which SH-SY5Y cells are a model.

Bevacizumab induces oxidative cytotoxicity and apoptosis via TRPM2 channel activation in retinal pigment epithelial cells: Protective role of glutathione

PURPOSE

Bevacizumab (BEV) is a blocker of circulating VEGF A generation. However, BEV has adverse apoptotic and cytotoxic effects via upregulation of mitochondrial reactive oxygen species (ROS) and TRPM2 activation, and downregulation of cytosolic glutathione (GSH) in neuronal cells. We investigated the possible protective effects of GSH treatment on BEV-induced oxidant and apoptotic adverse actions in the TRPM2 expressing adult retinal pigment epithelial-19 (ARPE-19) and SH-SY5Y neuronal cells.

MATERIAL AND METHODS

The ARPE-19 and SH-SY5Y cells were divided into five main groups: Control, GSH (10 mM for 2 h), BEV (0.25 mg/ml for 24 h), BEV+GSH, and BEV+TRPM2 channel blockers (ACA or 2-APB). In the SH-SY5Y cells, the Ca²⁺ analyses (Fluo-3) were performed only, although Fluo-3 and the remaining analyses were performed in the ARPE-19 cells.

RESULTS

The levels of apoptosis, cell death, mitochondrial ROS, lipid peroxidation, caspase-3, caspase-9, ADP-ribose-induced TRPM2 current density, cytosolic-free Zn²⁺, and Ca²⁺ were increased by BEV, although their levels were diminished by the treatments of GSH and TRPM2 blockers. The BEV-induced decreases of cell viability, GSH levels, and glutathione peroxidase activities were increased by the treatment of GSH. BEV-induced increase of TRPM2 expression was decreased by the treatment of GSH, although BEV-induced decrease of VEGF A expression was further decreased by the treatment of GSH.

CONCLUSION

Our data confirmed that BEV-induced mitochondrial ROS and apoptosis in the human retinal epithelial cells were modulated by GSH and TRPM2 inhibition. The treatment of GSH may be considered as a therapeutic approach to BEV-induced ARPE-19 cell injury.

The Role of TRP Channels and PMCA in Brain Disorders: Intracellular Calcium and pH Homeostasis

Brain disorders include neurodegenerative diseases (NDs) with different conditions that primarily affect the neurons and glia in the brain. However, the risk factors and pathophysiological mechanisms of NDs have not been fully elucidated. Homeostasis of intracellular Ca²⁺ concentration and intracellular pH (pH_i) is crucial for cell function. The regulatory processes of these ionic mechanisms may be absent or excessive in pathological conditions, leading to a loss of cell death in distinct regions of ND patients. Herein, we review the potential involvement of transient receptor potential (TRP) channels in NDs, where disrupted Ca²⁺ homeostasis leads to cell death. The capability of TRP channels to restore or excite the cell through Ca²⁺ regulation depending on the level of plasma membrane Ca²⁺ ATPase (PMCA) activity is discussed in detail. As PMCA simultaneously affects intracellular Ca²⁺ regulation as well as pH_i, TRP channels and PMCA thus play vital roles in modulating ionic homeostasis in various cell types or specific regions of the brain where the TRP channels and PMCA are expressed. For this reason, the dysfunction of TRP channels and/or PMCA under pathological conditions disrupts neuronal homeostasis due to abnormal Ca²⁺ and pH levels in the brain, resulting in various NDs. This review addresses the function of TRP channels and PMCA in controlling intracellular Ca²⁺ and pH, which may provide novel targets for treating NDs.

TRPM2 in ischemic stroke: Structure, molecular mechanisms, and drug intervention

Ischemic stroke has a high lethality rate worldwide, and novel treatments are limited. Calcium overload is considered to be one of the mechanisms of cerebral ischemia. Transient receptor potential melastatin 2 (TRPM2) is a reactive oxygen species (ROS)-sensitive calcium channel. Cerebral ischemia-induced TRPM2 activation triggers abnormal intracellular Ca²⁺ accumulation and cell death, which in turn causes irreversible brain damage. Thus, TRPM2 has emerged as a new therapeutic target for ischemic stroke. This review provides data on the expression, structure, and function of TRPM2 and illustrates its cellular and molecular mechanisms in ischemic stroke. Natural and synthetic TRPM2 inhibitors (both specific and nonspecific) are also summarized. The three-dimensional protein structure of TRPM2 has been identified, and we speculate that molecular simulation techniques will be essential for developing new drugs that block TRPM2 channels. These insights about TRPM2 may be the key to find potent therapeutic approaches for the treatment of ischemic stroke.