Browsing by Subject "oxidative stress"
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Item A macrocyclic molecule with multiple antioxidative activities protects the lens from oxidative damage(Frontiers Media S.A., 2022-11-18) Zhang, Jinmin; Yu, Yu; Mekhail, Magy A.; Wu, Hongli; Green, Kayla N.Growing evidence links oxidative stress to the development of a cataract and other diseases of the eye. Treatments for lens-derived diseases are still elusive outside of the standard surgical interventions, which still carry risks today. Therefore, a potential drug molecule (OH)Py(2)N(2) was explored for the ability to target multiple components of oxidative stress in the lens to prevent cataract formation. Several pathways were identified. Here we show that the (OH)Py(2)N(2) molecule activates innate catalytic mechanisms in primary lens epithelial cells to prevent damage induced by oxidative stress. This protection was linked to the upregulation of Nuclear factor erythroid-2-related factor 2 and downstream antioxidant enzyme for glutathione-dependent glutaredoxins, based on Western Blot methods. The anti-ferroptotic potential was established by showing that (OH)Py(2)N(2) increases levels of glutathione peroxidase, decreases lipid peroxidation, and readily binds iron (II) and (III). The bioenergetics pathway, which has been shown to be negatively impacted in many diseases involving oxidative stress, was also enhanced as evidence by increased levels of Adenosine triphosphate product when the lens epithelial cells were co-incubated with (OH)Py(2)N(2). Lastly, (OH)Py(2)N(2) was also found to prevent oxidative stress-induced lens opacity in an ex vivo organ culture model. Overall, these results show that there are multiple pathways that the (OH)Py(2)N(2) has the ability to impact to promote natural mechanisms within cells to protect against chronic oxidative stress in the eye.Item Alzheimer's Fibroblasts are More Susceptible to Oxidative Stress(2001-05-01) Marshall, Pamela L.; Neeraj Agarwal; Robert GracyMarshall, Pamela L., Alzheimer’s Fibroblasts Are More Susceptible to Oxidative Stress. Master’s of Science (Biomedical Sciences). May 2001. Recent evidence indicates that oxidative stress contributes to neuronal death in Alzheimer’s disease (AD). In addition, it has been suggested that AD is a systemic illness in which the development of the disease is only visible in the brain. The aim of this research is to develop experimental procedures using a simple cell model, the fibroblast, to determine if proteins derived from AD skin fibroblasts are more sensitive to oxidation by reactive oxygen species than non-AD cells, and to assess the ability of antioxidants to prevent this oxidative damage in AD fibroblasts. Preliminary findings suggest that changes in sensitivity are already detectable in fibroblasts from AD patients, probably as a consequence of genetic component as well as other risk factors. Therefore, this biochemical marker might have the potential for identifying individuals at risk for AD.Item Androgen Modulation of CNS During Chronic Intermittent Hypoxia(2018-05) Snyder, Brina D.; Cunningham, Rebecca L.; Barber, Robert C.; Cunningham, J. Thomas; Schreihofer, Derek A.; Planz, John V.The underlying causes of age-related neurodegenerative diseases, such as Alzheimer's disease or Parkinson's disease, are unknown. It is likely conditions which contribute to an abundance of oxidative stress throughout life renders an individual more susceptible to late-life neurodegenerative processes. Sex differences are observed in the onset and prevalence of these diseases, suggesting estrogens and androgens influence these processes. This study investigates the early role of androgens under a known oxidative stressor, sleep apnea, which frequently goes untreated in the clinical population but is but is associated with an increased risk of late-life neurodegeneration. The hypoxic events of sleep apnea can be modeled in rats by the use of chronic intermittent hypoxia (CIH). Male rats are more susceptible to hypertensive effects of CIH, a key characteristic of sleep apnea. After one week of CIH treatment, they also exhibit oxidative stress and inflammation in circulation and in brain nuclei associated with early stages of Parkinson's disease or Alzheimer's disease. This led to the hypothesis that oxidative stress and inflammation would be associated with behavior deficits and these effects are mediated by androgens. Results show that oxidative stress and inflammatory dysregulation can be prevented by testosterone, but are highly exacerbated by testosterone's non-aromatizable metabolite, dihydrotestosterone (DHT). Administration of DHT also resulted in significant memory impairments under CIH. In the central nervous system, DHT significantly altered oxidative stress and pro-inflammatory signals, which may underlie its detrimental actions in an oxidative stress environment. There was also evidence of hypothalamic-pituitary-adrenal axis dysregulation, which can influence testosterone and circadian rhythms. These findings have broad implications for clinical populations with conditions which chronically increase oxidative stress and inflammation, while at the same time alter endocrine function. Conditions, such as untreated sleep apnea, may pose a latent risk for neurodegeneration and should be addressed early to prevent later detrimental effects.Item Artemisinin Prevents Glutamate-Induced Neuronal Cell Death Via Akt Pathway Activation(Frontiers Media S.A., 2018-04-20) Lin, Shao-Peng; Li, Wenjun; Winters, Ali; Liu, Ran; Yang, ShaohuaArtemisinin is an anti-malarial drug that has been in use for almost half century. Recently, novel biological effects of artemisinin on cancer, inflammation-related disorders and cardiovascular disease were reported. However, neuroprotective actions of artemisinin against glutamate-induced oxidative stress have not been investigated. In the current study, we determined the effect of artemisinin against oxidative insult in HT-22 mouse hippocampal cell line. We found that pretreatment of artemisinin declined reactive oxygen species (ROS) production, attenuated the collapse of mitochondrial membrane potential induced by glutamate and rescued HT-22 cells from glutamate-induced cell death. Furthermore, our study demonstrated that artemisinin activated Akt/Bcl-2 signaling and that neuroprotective effect of artemisinin was blocked by Akt-specific inhibitor, MK2206. Taken together, our study indicated that artemisinin prevented neuronal HT-22 cell from glutamate-induced oxidative injury by activation of Akt signaling pathway.Item Chronic Inhibition of Mitochondrial Dihydrolipoamide Dehydrogenase (DLDH) as an Approach to Managing Diabetic Oxidative Stress(MDPI, 2019-02-02) Yang, Xiaojuan; Song, Jing; Yan, Liang-JunMitochondrial dihydrolipoamide dehydrogenase (DLDH) is a redox enzyme involved in decarboxylation of pyruvate to form acetyl-CoA during the cascade of glucose metabolism and mitochondrial adenine triphosphate (ATP) production. Depending on physiological or pathophysiological conditions, DLDH can either enhance or attenuate the production of reactive oxygen species (ROS) and reactive nitrogen species. Recent research in our laboratory has demonstrated that inhibition of DLDH induced antioxidative responses and could serve as a protective approach against oxidative stress in stroke injury. In this perspective article, we postulated that chronic inhibition of DLDH could also attenuate oxidative stress in type 2 diabetes. We discussed DLDH-involving mitochondrial metabolic pathways and metabolic intermediates that could accumulate upon DLDH inhibition and their corresponding roles in abrogating oxidative stress in diabetes. We also discussed a couple of DLDH inhibitors that could be tested in animal models of type 2 diabetes. It is our belief that DLDH inhibition could be a novel approach to fighting type 2 diabetes.Item Comparative Proteomics Analysis Reveals Unique Early Signaling Response of Saccharomyces cerevisiae to Oxidants with Different Mechanism of Action(MDPI, 2020-12-26) Pandey, Prajita; Zaman, Khadiza; Prokai, Laszlo; Shulaev, VladimirThe early signaling events involved in oxidant recognition and triggering of oxidant-specific defense mechanisms to counteract oxidative stress still remain largely elusive. Our discovery driven comparative proteomics analysis revealed unique early signaling response of the yeast Saccharomyces cerevisiae on the proteome level to oxidants with a different mechanism of action as early as 3 min after treatment with four oxidants, namely H2O2, cumene hydroperoxide (CHP), and menadione and diamide, when protein abundances were compared using label-free quantification relying on a high-resolution mass analyzer (Orbitrap). We identified significant regulation of 196 proteins in response to H2O2, 569 proteins in response to CHP, 369 proteins in response to menadione and 207 proteins in response to diamide. Only 17 proteins were common across all treatments, but several more proteins were shared between two or three oxidants. Pathway analyses revealed that each oxidant triggered a unique signaling mechanism associated with cell survival and repair. Signaling pathways mostly regulated by oxidants were Ran, TOR, Rho, and eIF2. Furthermore, each oxidant regulated these pathways in a unique way indicating specificity of response to oxidants having different modes of action. We hypothesize that interplay of these signaling pathways may be important in recognizing different oxidants to trigger different downstream MAPK signaling cascades and to induce specific responses.Item Connexin 43 Contributes to Estrogen Protection against Oxidative Stress in Cortical Astrocytes(2019-05) Kubelka, Nicholas K.; Singh, Meharvan; Uht, Rosalie M.; Schreihofer, Derek A.; Yang, Shaohua; Planz, John V.Age-related brain disorders are associated with the decline in the ability of brain cells to cope with homeostatic challenge. Although all major brain cell types have the capacity to respond to homeostatic challenges, astrocytes are particularly well-equipped to counteract these challenges. Here, we focused on Connexin 43 (Cx43) as a protein that is not only highly expressed in astrocytes, but whose expression is critical to inter-cellular communication that in turn, can influence cell viability. Most studies to date have focused on the expression (i.e., abundance) of Cx43. However, a critical limitation of these studies is that they did not thoroughly examine functionality of the Cx43 channels. In particular, there is a paucity of data describing the differential contributions of Cx43-containing hemichannels versus Cx43-containing gap junctions to cellular functions. We hypothesized the astrocyte Cx43 hemichannel as a yet unreported target of androgens and estrogens based on three notions. First, our laboratory has determined that astrocytes are a relevant and important target of such gonadal steroid hormones as estrogens (e.g., 17[beta]-estradiol (abbreviated herein as estradiol or E2)) and androgens (such as DHT), through which these hormones promote healthy brain cell function. Second, oxidative stress is associated with an increase in Cx43 opening. Finally, the Cx43 gene promoter contains functional estrogen response element (ERE) half sites, and estradiol, as well as other estrogenic compounds, decrease Cx43 channel opening in peripheral (non-CNS) tissue. Based on these notions, we hypothesized that gonadal androgens and estrogens will inhibit Cx43 hemichannel opening in cortical astrocytes as well. My data revealed that while E2, dihydrotestosterone (DHT), and the estrogenic metabolite of DHT (3[beta]diol) all protect primary cortical astrocytes from the mixed metabolic/oxidative insult, iodoacetic acid (IAA), only DHT decreased astrocyte Cx43 mRNA expression. Consistent with their cytoprotective effects, however, all three steroids decrease astrocyte Cx43 hemichannel opening, and antagonized the increased opening of Cx43 hemichannels induced by IAA. In an effort to pursue the mechanism by which these steroids reduced Cx43 hemichannel opening, we evaluated the phosphorylation of Cx43 at two key residues, Ser 368 and Tyr 265. Phosphorylation at these residues is associated with channel closing, and as such, we predicted that the three hormones would increase the phosphorylation of Cx43 at one or both of these residues. Whereas Tyr265 phosphorylation was unaffected any of the three hormones, DHT significantly reduced the phosphorylation of Cx43 at Ser368. These observations may indicate that while all three steroids contribute to astrocyte protection through a mechanism that involves blocking astrocyte Cx43 hemichannel opening, DHT may induce molecular changes in the astrocytes that are distinct from those induced by estradiol or 3[beta]diol. The knowledge gained through the experiments conducted not only enhance our understanding of how Cx43 hemichannels and Cx43 gap junctions influence astrocyte function and viability but also define Cx43 hemichannels as relevant targets of gonadal steroid hormone induced regulation of cell viability. Such knowledge may facilitate the development of more precise therapeutics (i.e., selectively targeting Cx43 hemichannels without activity at Cx43 gap junctions in the same cells or tissue), the benefit of which would be to better treat age-associated neurodegenerative disorders as well as disorders of peripheral tissueItem Estrogen Signaling Protects Mitochondrial Membrane Potential Integrity from Oxidative Stress in Lens Epithelial Cells(2008-05-01) Flynn, James Martin; Cammarata, Patrick R.; Wordinger, Robert J.; Dimitrijevich, S. DanFlynn, James Martin, Estrogen Signaling Protects Mitochondrial Membrane Potential Integrity from Oxidative Stress in Lens Epithelial Cells. Doctor of Philosophy, (Cell Biology and Genetics) May, 2008, 265 pages, 36 figures, bibliography, 190 titles. Loss of mitochondrial membrane potential has been determined to be one of the initiating factors in activation of apoptosis after cellular damage. Estrogen and estrogen analogues have been shown to enhance cell survival in numerous tissues through rapid pro-survival cell signaling. This study was focused on elucidating mechanisms through which estrogen protects the cells by preventing the activation of mitochondrial permeability transition pores and the subsequent loss of mitochondrial membrane potential. It is hypothesized that the anti-apoptotic mitochondrial protein BAD, once phosphorylated by estrogen activated upstream kinases, can prevent the formation of the permeability transition pre via direct interaction. To address this, lens epithelial cells were used as a model system for the examination of mitochondrial depolarization during periods of either oxidative or hyperglycemic stress. Estrogen attenuated the loss of impermeability of the mitochondrial membrane, thus maintaining the cells during acute periods of stress. It was discovered that a number of the estrogen receptor isoforms are expressed in lens epithelium, and that the wild-type estrogen receptor-β1 isoform is localized to the mitochondria in lens epithelial cultures derived from both human males and females. siRNA treatment against estrogen receptor-β determined that is a required component to elicit estrogen’s protective abilities against oxidative stress induced mitochondrial depolarization. Furthermore, administration of exogenous estrogen rapidly activated signaling pathways, particularly ERK, which were shown to have influence over the loss of mitochondrial membrane potential. Studies using both pharmacological inhibitors of MAPK signaling, as well as siRNA of ERK2 kinase demonstrate a correlation between the activation of ERK and the severity of response to oxidative stress. Investigation of downstream substrates of ERK revealed that the mitochondrial protein BAD is phosphorylated after the administration of estrogen, yet it is not required for the prevention of mitochondrial depolarization as originally hypothesized. In conclusion, these studies have confirmed a mitochondrial targeted mechanism activated by estrogen which is rapid, gender independent, estrogen receptor-β mediated signal transduction pathway. The targeting of mitochondrial function to reduce oxidative or hyperglycemic stress, thereby preventing activation of the permeability transition pore, defines a novel concept which will contribute to innovative regimens for prevention or treatment of mitochondrial pathology.Item Folic acid-induced animal model of kidney disease(John Wiley & Sons Australia, Ltd, 2021-11-24) Yan, Liang-JunThe kidneys are a vital organ that is vulnerable to both acute kidney injury (AKI) and chronic kidney disease (CKD) which can be caused by numerous risk factors such as ischemia, sepsis, drug toxicity and drug overdose, exposure to heavy metals, and diabetes. In spite of the advances in our understanding of the pathogenesis of AKI and CKD as well AKI transition to CKD, there is still no available therapeutics that can be used to combat kidney disease effectively, highlighting an urgent need to further study the pathological mechanisms underlying AKI, CKD, and AKI progression to CKD. In this regard, animal models of kidney disease are indispensable. This article reviews a widely used animal model of kidney disease, which is induced by folic acid (FA). While a low dose of FA is nutritionally beneficial, a high dose of FA is very toxic to the kidneys. Following a brief description of the procedure for disease induction by FA, major mechanisms of FA-induced kidney injury are then reviewed, including oxidative stress, mitochondrial abnormalities such as impaired bioenergetics and mitophagy, ferroptosis, pyroptosis, and increased expression of fibroblast growth factor 23 (FGF23). Finally, application of this FA-induced kidney disease model as a platform for testing the efficacy of a variety of therapeutic approaches is also discussed. Given that this animal model is simple to create and is reproducible, it should remain useful for both studying the pathological mechanisms of kidney disease and identifying therapeutic targets to fight kidney disease.Item INCREASED EXPRESSION OF GLUTAREDOXIN 1 (Grx1) PROTECTS HUMAN RETINAL PIGMENT EPITHELIAL CELLS FROM OXIDATIVE DAMAGE(2014-03) Liu, Xiaobin; Jann, Jamieson; Wu, HongliOxidative stress is believed to contribute to the pathogenesis of many diseases, including age-related macular degeneration (AMD), in which retinal pigment epithelial (RPE) cells are considered as major targets. It is widely accepted that the RPE cells have enormous number of thiol-containing proteins, which can undergo modifications to change retinal protein functions. In contrast, the mechanism of thiol redox regulation in the retina and its association with AMD are still very poorly understood. In particular, the function of glutaredoxin 1 (Grx1), a thiol repair enzyme in cytosol, is virtually unknown. This project seeks to address this paucity in a comprehensive and physiological relevant fashion, and therefore is both novel and innovative. Furthermore, the ability to identify novel therapeutic targets for further research is the first critical step in finding new treatments for AMD. The overall success of this project will raise new hope that Grx1 or its mimic may be a potential therapeutic agent for AMD, and perhaps for other ocular diseases induced by oxidative stress. Purpose (a): The retina is constantly exposed to oxidative stress, which is countered by well-designed antioxidant systems present in retinal pigment epithelial (RPE) cells. Disruption of these systems may lead to the development of age-related macular degeneration (AMD). In this study, we explored the strategy of overexpressing glutaredoxin 1 (Grx1), a component of the endogenous antioxidant defense system, to combat oxidative damage in RPE cells. Methods (b): Human retinal pigment epithelial (ARPE-19) cells were transfected with either a Grx1-containing plasmid or an empty vector. Normal ARPE-19 cells and transfected cells were treated with or without 200 µM H2O2 for 24 h. Grx1 protein expression was detected by western blots and enzyme activity was measured by spectrophotometry. Cell viability was measured by a colorimetric assay with WST8. The morphology of nuclear chromatin was assessed by staining with Hoechst 33342. Apoptosis was quantitatively analyzed by flow cytometry. The level of protein glutathionylation (PSSG) was measured by immunoblotting using anti-PSSG antibody. Results (c): Grx1 protein level and enzyme activity in Grx1 transfected cells were significantly increased as compared to non-transfected and vector transfected cells. Grx1 overexpression protected ARPE-19 cells from H2O2-induced cell viability loss. Assessment of apoptosis indicated that cells transfected with Grx1 were relatively more resistant to H2O2 with fewer cells undergoing apoptosis as compared to vector control or non-transfected cells. Furthermore, PSSG accumulation was also dramatically attenuated by Grx1 overexpression. Conclusions (d): Grx1 can protect human retinal pigment epithelial cells against H2O2-induced cell death. The mechanism of this protection is likely associated with its ability to prevent lethal accumulation of PSSG.Item Intravenous pyruvate to protect heart and brain during closed-chest resuscitation and recovery from cardiac arrest(2014-08-01) Cherry, Brandon H.; Mallet, Robert T.; Olivencia-Yurvati, Albert H.; Raven, Peter B.Cardiac arrest is a leading cause of death in the United States and Western Europe. Cardiopulmonary resuscitation (CPR) is the only means of sustaining the victim until application of defibrillatory countershocks. Although it has been over 50 years since its advent, CPR remains a work in progress. Many initially resuscitated victims later die from the damage sustained from ischemia-reperfusion, and treatments to combat the extensive ischemia-reperfusion injury sustained during cardiac arrest-resuscitation remain elusive. The major mechanism of injury underlying ischemia-reperfusion is the intense overproduction of reactive oxygen and nitrogen species (RONS) that accumulate during reperfusion and compromise normal cell function. RONS formed during resuscitation trigger lipid peroxidation, disable enzymes vital for cell metabolism and survival and, ultimately, induce cell death within affected organs. In order to prevent extensive damage to the central nervous system culminating in permanent neurocognitive disability and death, prospective treatments must possess robust antioxidant properties, traverse the blood-brain barrier between the cerebral circulation and brain parenchyma, and be non-toxic at effective doses. Pyruvate is a natural intermediary metabolite, energy-yielding substrate and antioxidant. Pyruvate neutralizes RONS, thereby dampening oxidative stress and preventing covalent oxidative modification of enzymes and lipid membranes, and generates ATP to support brain function. Pyruvate readily traverses the blood-brain barrier and is non-toxic over a wide range of doses, including those previously demonstrated to protect the heart during cardiopulmonary bypass and the brain during stroke, thereby supporting oxygen and fuel delivery to the recovering brain. Moreover, pyruvate has been shown to promote cardiac electromechanical and metabolic recovery following cardiac arrest and open-chest CPR. This study tested whether infusion of pyruvate during, CPR and early recovery can decrease the biomarkers of oxidative stress after cardiac arrest. Isoflurane-anesthetized pigs were subjected to 6 min electrically-induced, untreated ventricular fibrillation, followed by 4 min closed-chest CPR, defibrillation and either 1 or 4 h recovery. Beginning at 5.5 min arrest, either sodium pyruvate or NaCl control were infused iv for the duration of CPR and for the first 60 min after recovery of spontaneous circulation (ROSC). Arterial blood was sampled pre-arrest and at 5, 15, 30, 60, 120, 180, and 240 min ROSC for analyses of blood gases and plasma constituents. At either 1 h (i.e. end of treatment infusion) or 4 h ROSC, a craniotomy was performed, the pig was euthanized, the brain was removed, and biopsies from hippocampus and cerebellum were snap-frozen in liquid nitrogen for biochemical analysis. The first phase of this project tested the hypothesis that intravenous administration of sodium pyruvate during precordial compressions and the first 60 min ROSC restores hemodynamic, metabolic, and electrolyte homeostasis in a closed chest porcine model of cardiac arrest. Resuscitation with pyruvate sharply decreased the incidence of lethal pulseless electrical activity (PEA) following defibrillatory countershocks, and lowered the dosage of vasoconstrictor phenylephrine required to maintain systemic arterial pressure. Pyruvate also enhanced glucose clearance, elevated arterial bicarbonate, and raised arterial pH. The second phase of this project tested the hypothesis that pyruvate prevents the decrease in activity of the brain’s antioxidant enzymes following cardiac arrest and hyperoxic (100% O2). Activities of glutathione peroxidase and glutathione reductase were decreased at 60 min ROSC vs. sham in both the hippocampus and cerebellum. Pyruvate partially preserved glutathione peroxidase activity at 1 h ROSC, but by 4 h, after 3 h of pyruvate clearance from the circulation, the enzyme’s activity fell to the same extent as in NaCl-infused pigs. Interestingly, the glutathione peroxidase/reductase activity fell sharply in non-arrested sham pigs between the time points corresponding to 1 and 4 h ROSC, suggesting that hyperoxia resulting from ventilation with 100% produced sufficient oxidative stress to inactivate the enzymes. Similarly, lactate dehydrogenase activity fell between 1 and 4 h ROSC in hippocampus and especially cerebellum. In sham pigs, lactate dehydrogenase activity decreased from the time points corresponding to 1 and 4 h ROSC, and pyruvate had no effect on lactate dehydrogenase in either region of the brain. Thus, cardiac arrest and hyperoxic ventilation disabled a critical antioxidant system in two ischemia-sensitive brain regions. Pyruvate afforded partial protection of these enzymes which waned after pyruvate cleared from the circulation. We conclude that 1) Pyruvate infusion during cardiac arrest, CPR and early recovery promotes conversion from ventricular fibrillation to a productive sinus rhythm instead of lethal PEA; 2) Pyruvate hastened glucose clearance, a prognostic measure used clinically; 3) Pyruvate elevated the arterial bicarbonate concentration and raised arterial pH, which combats the acidemia normally observed following ROSC; 4) Cardiac arrest-resuscitation and hyperoxic ventilation disabled the glutathione peroxidase-reductase system, a critical component of the brain’s antioxidant defenses, in hippocampus and cerebellum; and 5) Pyruvate delayed oxidative inactivation of glutathione peroxidase in the cerebellum, but this effect subsided as pyruvate elevated. These investigations demonstrate the therapeutic effects and limitations of pyruvate as a resuscitative treatment to hasten electrocardiographic and metabolic recovery post cardiac arrest.Item Mitochondria-associated endoplasmic reticulum membranes (MAMs) and their role in glaucomatous retinal ganglion cell degeneration-a mini review(Frontiers Media S.A., 2023-05-30) Pham, Jennifer H.; Stankowska, Dorota L.Glaucoma is a leading cause of blindness worldwide, commonly associated with elevated intraocular pressure (IOP), leading to degeneration of the optic nerve and death of retinal ganglion cells, the output neurons in the eye. In recent years, many studies have implicated mitochondrial dysfunction as a crucial player in glaucomatous neurodegeneration. Mitochondrial function has been an increasingly researched topic in glaucoma, given its vital role in bioenergetics and propagation of action potentials. One of the most metabolically active tissues in the body characterized by high oxygen consumption is the retina, particularly the retinal ganglion cells (RGCs). RGCs, which have long axons that extend from the eyes to the brain, rely heavily on the energy generated by oxidative phosphorylation for signal transduction, rendering them more vulnerable to oxidative damage. In various glaucoma models, mitochondrial dysfunction and stress from protein aggregates in the endoplasmic reticulum (ER) have been observed in the RGCs. However, it has been shown that the two organelles are connected through a network called mitochondria-associated ER membranes (MAMs); hence this crosstalk in a pathophysiological condition such as glaucoma should be evaluated. Here, we review the current literature suggestive of mitochondrial and ER stress related to glaucoma, indicating potential cross-signaling and the potential roles of MAMs.Item Mitochondrial SOS: how mtDNA may act as a stress signal in Alzheimer's disease(BioMed Central Ltd., 2023-10-12) Gorham, Isabelle K.; Barber, Robert C.; Jones, Harlan P.; Phillips, Nicole R.BACKGROUND: Alterations in mitochondrial DNA (mtDNA) levels have been observed in Alzheimer's disease and are an area of research that shows promise as a useful biomarker. It is well known that not only are the mitochondria a key player in producing energy for the cell, but they also are known to interact in other important intracellular processes as well as extracellular signaling and communication. BODY: This mini review explores how cells use mtDNA as a stress signal, particularly in Alzheimer's disease. We investigate the measurement of these mtDNA alterations, the mechanisms of mtDNA release, and the immunological effects from the release of these stress signals. CONCLUSION: Literature indicates a correlation between the release of mtDNA in Alzheimer's disease and increased immune responses, showing promise as a potential biomarker. However, several questions remain unanswered and there is great potential for future studies in this area.Item Modulation of Manganese Superoxide Dismutase by 17-Beta Estradiol(2008-05-01) Gottipati, Srinivas; Thomas YorioGottipati, Srinivas. Modulation of manganese superoxide dismutase activity by 17-beta estradiol. Master of Science (Cell Biology and Genetics), May, 2008. We have previously reported that 17β-Estradiol (17β-E2) can protect human lens epithelial cells against oxidative stress by preserving mitochondrial function, acting as a positive regulator of the MAPK signal transduction pathway. While pERK plays a significant role in stabilizing the inner mitochondrial membrane to maintain the mitochondrial membrane potential during oxidative stress, the protective mechanisms activated by 17β-E2 are probably multifactorial acting via both genomic and non genomic pathways. This study examined the effects of 17β-E2 on the expression and activity of MnSOD, which is present exclusively in the mitochondria, as a possible mechanism by which it affords protection against oxidative stress. Our results demonstrate that 17β-E2 rapidly increases the activity of MnSOD in a time dependent manner. This augmentation of activity of MnSOD by 17β-E2 is seen in the absence of a corresponding increase in the mRNA and protein expression, thereby which estrogens protect the cells against oxidative stress will help us in developing estrogens to be useful therapies for the prevention of cataract in postmenopausal women and non feminizing estrogens may provide similar protection in men.Item Molecular Mechanisms of High-Altitude Acclimatization(MDPI, 2023-01-22) Mallet, Robert T.; Burtscher, Johannes; Pialoux, Vincent; Pasha, Qadar; Ahmad, Yasmin; Millet, Gregoire P.; Burtscher, MartinHigh-altitude illnesses (HAIs) result from acute exposure to high altitude/hypoxia. Numerous molecular mechanisms affect appropriate acclimatization to hypobaric and/or normobaric hypoxia and curtail the development of HAIs. The understanding of these mechanisms is essential to optimize hypoxic acclimatization for efficient prophylaxis and treatment of HAIs. This review aims to link outcomes of molecular mechanisms to either adverse effects of acute high-altitude/hypoxia exposure or the developing tolerance with acclimatization. After summarizing systemic physiological responses to acute high-altitude exposure, the associated acclimatization, and the epidemiology and pathophysiology of various HAIs, the article focuses on molecular adjustments and maladjustments during acute exposure and acclimatization to high altitude/hypoxia. Pivotal modifying mechanisms include molecular responses orchestrated by transcription factors, most notably hypoxia inducible factors, and reciprocal effects on mitochondrial functions and REDOX homeostasis. In addition, discussed are genetic factors and the resultant proteomic profiles determining these hypoxia-modifying mechanisms culminating in successful high-altitude acclimatization. Lastly, the article discusses practical considerations related to the molecular aspects of acclimatization and altitude training strategies.Item NADH/NAD(+) Redox Imbalance and Diabetic Kidney Disease(MDPI, 2021-05-14) Yan, Liang-JunDiabetic kidney disease (DKD) is a common and severe complication of diabetes mellitus. If left untreated, DKD can advance to end stage renal disease that requires either dialysis or kidney replacement. While numerous mechanisms underlie the pathogenesis of DKD, oxidative stress driven by NADH/NAD(+) redox imbalance and mitochondrial dysfunction have been thought to be the major pathophysiological mechanism of DKD. In this review, the pathways that increase NADH generation and those that decrease NAD(+) levels are overviewed. This is followed by discussion of the consequences of NADH/NAD(+) redox imbalance including disruption of mitochondrial homeostasis and function. Approaches that can be applied to counteract DKD are then discussed, which include mitochondria-targeted antioxidants and mimetics of superoxide dismutase, caloric restriction, plant/herbal extracts or their isolated compounds. Finally, the review ends by pointing out that future studies are needed to dissect the role of each pathway involved in NADH-NAD(+) metabolism so that novel strategies to restore NADH/NAD(+) redox balance in the diabetic kidney could be designed to combat DKD.Item Neurobehavioral and biochemical consequences of chronic, low-dose methamphetamine exposure in male and female mice(2022-08) Davis, Delaney L.; Sumien, Nathalie; Huang, Ren-Qi; Gatch, Michael B.; Phillips, Nicole R.; Schreihofer, Derek A.; Ma, RongAlthough prescription psychostimulants are effective in reducing attention deficit hyperactivity disorder (ADHD) symptomology, misuse of these drugs can pose serious risks such as potential abuse, dependence, and/or neurotoxicity. Of particular concern is that young adults have the highest prevalence of prescription stimulant misuse, with almost 10% of college students admitting to using amphetamine (e.g. Adderall) or methylphenidate (e.g. Ritalin) products. Despite these drugs being widely used for therapeutic and recreational use, the long-term effects of prescription stimulants have not been systematically evaluated in controlled clinical trials. Therefore, it is critical to conduct this research because young adults may be a vulnerable, at-risk population to the potential adverse consequences of long-term amphetamine use. This dissertation research evaluates the biochemical and behavioral consequences of chronic exposure of the prototypical psychostimulant, methamphetamine (METH), in a rodent model. It is hypothesized that repeated doses of METH, within the therapeutic dosing range used in a clinical setting, will induce neurotoxicity through the interplay of biological mechanisms of oxidative stress, glutamate excitotoxicity, neuroinflammation and epigenetic alterations and increase susceptibility to addiction that will be exacerbated by aging processes. Overall, the body of results showed short-term alterations in brain biochemistry and behavioral function, that do not necessarily persist past 5 months after METH treatment. In conclusion, this dissertation highlights the importance of long-term studies in addressing prescription stimulant misuse in an adult population to better understand the safety of these widely used and prescribed psychostimulants.Item Neuroprotection of Cyperus esculentus L. orientin against cerebral ischemia/reperfusion induced brain injury(Wolters Kluwer - Medknow, 2020-03) Jing, Si-Qun; Wang, Sai-Sai; Zhong, Rui-Min; Zhang, Jun-Yan; Wu, Jin-Zi; Tu, Yi-Xian; Pu, Yan; Yan, Liang-JunOrientin is a flavonoid monomer. In recent years, its importance as a source of pharmacological active substance is growing rapidly due to its properties such as anti-myocardial ischemia, anti-apoptosis, anti-radiation, anti-tumor, and anti-aging. However, the neuroprotective effects of Orientin on stroke injury have not been comprehensively evaluated. The aim of the present study was thus to investigate the neuroprotective capacity and the potential mechanisms of Cyperus esculentus L. orientin (CLO) from Cyperus esculentus L. leaves against ischemia/reperfusion (I/R) injury using standard orientin as control. For in vitro studies, we treated HT22 cells with CoCl2 as an in vitro ischemic injury model. HT22 cells in the control group were treated with CoCl2. For in vivo studies, we used rat models of middle cerebral artery occlusion, and animals that received sham surgery were used as controls. We found that CLO protected CoCl2-induced HT22 cells against ischemia/reperfusion injury by lowering lipid peroxidation and reactive oxygen species formation as well as decreasing protein oxidation. However, CLO did not reduce the release of lactate dehydrogenase nor increase the activity of superoxide dismutase. Results showed that CLO could decrease neurological deficit score, attenuate brain water content, and reduce cerebral infarct volume, leading to neuroprotection during cerebral ischemia-reperfusion injury. Our studies indicate that CLO flavonoids can be taken as a natural antioxidant and bacteriostastic substance in food and pharmaceutical industry. The molecular mechanisms of CLO could be at least partially attributed to the antioxidant properties and subsequently inhibiting activation of casepase-3. All experimental procedures and protocols were approved on May 16, 2016 by the Experimental Animal Ethics Committee of Xinjiang Medical University of China (approval No. IACUC20160516-57).Item Neuroprotection of Rodent and Human Retinal Ganglion Cells In Vitro/Ex Vivo by the Hybrid Small Molecule SA-2(MDPI, 2022-12-12) Pham, Jennifer H.; Johnson, Gretchen A.; Rangan, Rajiv S.; Amankwa, Charles E.; Acharya, Suchismita; Stankowska, Dorota L.The mechanisms underlying the neuroprotective effects of the hybrid antioxidant-nitric oxide donating compound SA-2 in retinal ganglion cell (RGC) degeneration models were evaluated. The in vitro trophic factor (TF) deprivation model in primary rat RGCs and ex vivo human retinal explants were used to mimic glaucomatous neurodegeneration. Cell survival was assessed after treatment with vehicle or SA-2. In separate experiments, tert-Butyl hydroperoxide (TBHP) and endothelin-3 (ET-3) were used in ex vivo rat retinal explants and primary rat RGCs, respectively, to induce oxidative damage. Mitochondrial and intracellular reactive oxygen species (ROS) were assessed following treatments. In the TF deprivation model, SA-2 treatment produced a significant decrease in apoptotic and dead cell counts in primary RGCs and a significant increase in RGC survival in ex vivo human retinal explants. In the oxidative stress-induced models, a significant decrease in the production of ROS was observed in the SA-2-treated group compared to the vehicle-treated group. Compound SA-2 was neuroprotective against various glaucomatous insults in the rat and human RGCs by reducing apoptosis and decreasing ROS levels. Amelioration of mitochondrial and cellular oxidative stress by SA-2 may be a potential therapeutic strategy for preventing neurodegeneration in glaucomatous RGCs.Item Neuroprotective and Anti-Inflammatory Activities of Hybrid Small-Molecule SA-10 in Ischemia/Reperfusion-Induced Retinal Neuronal Injury Models(MDPI, 2024-03-13) Amankwa, Charles E.; Acha, Lorea G.; Dibas, Adnan; Chavala, Sai H.; Roth, Steven; Mathew, Biji; Acharya, SuchismitaEmbolism, hyperglycemia, high intraocular pressure-induced increased reactive oxygen species (ROS) production, and microglial activation result in endothelial/retinal ganglion cell death. Here, we conducted in vitro and in vivo ischemia/reperfusion (I/R) efficacy studies of a hybrid antioxidant-nitric oxide donor small molecule, SA-10, to assess its therapeutic potential for ocular stroke. METHODS: To induce I/R injury and inflammation, we subjected R28 and primary microglial cells to oxygen glucose deprivation (OGD) for 6 h in vitro or treated these cells with a cocktail of TNF-alpha, IL-1beta and IFN-gamma for 1 h, followed by the addition of SA-10 (10 microM). Inhibition of microglial activation, ROS scavenging, cytoprotective and anti-inflammatory activities were measured. In vivo I/R-injured mouse retinas were treated with either PBS or SA-10 (2%) intravitreally, and pattern electroretinogram (ERG), spectral-domain optical coherence tomography, flash ERG and retinal immunocytochemistry were performed. RESULTS: SA-10 significantly inhibited microglial activation and inflammation in vitro. Compared to the control, the compound SA-10 significantly attenuated cell death in both microglia (43% vs. 13%) and R28 cells (52% vs. 17%), decreased ROS (38% vs. 68%) production in retinal microglia cells, preserved neural retinal function and increased SOD1 in mouse eyes. CONCLUSION: SA-10 is protective to retinal neurons by decreasing oxidative stress and inflammatory cytokines.