Oxidative stress in genetic mouse models of Parkinson's disease

Brown rice attenuates iron-induced Parkinson's disease phenotypes in male wild-type drosophila: insights into antioxidant and iron metabolism modulation

Parkinson's disease (PD) is a progressive movement disorder associated with brain iron (Fe) accumulation and free radicals. Brown rice (BR) is antioxidant-rich and has been shown to ameliorate oxidative stress-induced damage. The aim of this study was to investigate the effects of BR compared to white rice (WR) on Fe-induced PD in a fruit fly model. Three-day-old male adult flies were divided into two groups: one on a normal diet and the other on Fe-diet (1 mmol/L) for 10 days to induce PD. After 10 days, the Fe-fed flies were redistributed into four groups: one on normal diet (Fe group), while the others were treated with BR (Fe + BR group), WR (Fe + WR group), or L-3,4-dihydroxyphenylalanine (L-dopa) (Fe + L-dopa group) for 5 days. Similarly, the flies initially on a normal diet were separated into four groups: one on normal diet (Control group), while the others were treated with BR (BR group), WR (WR group), or L-dopa (L-dopa group) for 5 days. Finally, Fe levels, dopamine, malonaldehyde (MDA), and antioxidant enzymes were measured, and the mRNA levels of antioxidant and Fe metabolism genes were assessed. BR significantly improved motor and cognitive functions, decreased fly head MDA and Fe levels, and increased antioxidant enzyme levels in comparison to the Fe and WR groups. Similarly, BR upregulated the mRNA levels of antioxidant genes: catalase, GPx, Nrf2, and DJ-1. The results suggest that BR could potentially reduce morbidities associated with PD possibly due to its bioactive compounds compared to WR.

Oxygen-induced stress reveals context-specific gene regulatory effects in human brain organoids

The interaction between genetic variants and environmental stressors is key to understanding the mechanisms underlying neurological diseases. In this study, we used human brain organoids to explore how varying oxygen levels expose context-dependent gene regulatory effects. By subjecting a genetically diverse panel of 21 brain organoids to hypoxic and hyperoxic conditions, we identified thousands of gene regulatory changes that are undetectable under baseline conditions, with 1,745 trait-associated genes showing regulatory effects only in response to oxygen stress. To capture more nuanced transcriptional patterns, we employed topic modeling, which revealed context-specific gene regulation linked to dynamic cellular processes and environmental responses, offering a deeper understanding of how gene regulation is modulated in the brain. These findings underscore the importance of genotype-environment interactions in genetic studies of neurological disorders and provide new insights into the hidden regulatory mechanisms influenced by environmental factors in the brain.

Distinct mechanisms underlying the therapeutic effects of low-molecular-weight heparin and chondroitin sulfate on Parkinson's disease

Parkinson's disease (PD) is a neurodegenerative disorder influenced by various factors, including age, genetics, and the environment. Current treatments provide symptomatic relief without impeding disease progression. Previous studies have demonstrated the therapeutic potential of exogenous heparin and chondroitin sulfate in PD. However, their therapeutic mechanisms and structure-activity relationships remain poorly understood. In this study, low-molecular-weight heparin (L-HP) and chondroitin sulfate (L-CS) exhibited favorable therapeutic effects in a mouse model of PD. Proteomics revealed that L-HP attenuated mitochondrial dysfunction through its antioxidant properties, whereas L-CS suppressed neuroinflammation by inhibiting platelet activation. Two glycosaminoglycan (GAG)-binding proteins, manganese superoxide dismutase (MnSOD2) and fibrinogen beta chain (FGB), were identified as potential targets of L-HP and L-CS, and we investigated their structure-activity relationships. The IdoA2S-GlcNS6S/GlcNAc6S unit in HP bound to SOD2, whereas the GlcA-GalNAc4S and GlcA-GalNAc4S6S units in CS preferred FGB. Furthermore, N-S and 2-O-S in L-HP, and 4-O-S, 6-O-S, and -COOH in L-CS contributed significantly to the binding process. These findings provide new insights and evidence for the development and use of glycosaminoglycan-based therapeutics for PD.

Sciadopitysin mitigates spermatological and testicular damage instigated by paraquat administration in male albino rats

Paraquat (PQ) is a herbicide that has ability to induce testicular toxicity by producing reactive oxygen species (ROS). Sciadopitysin (SPS) is a promising flavonoid that displays multiple pharmacological properties i.e., anti-inflammatory, anti-oxidant and anti-apoptotic. Therefore, the present study was designed to evaluate the mitigative role of SPS against PQ induced testicular toxicity in male rats. The experiment was performed on male albino rats (n = 48) that were divided into 4 groups. The group-1 was control group. Group-2 was administrated orally with PQ (5 mg/kg). Group-3 was administrated orally with PQ (5 mg/kg) and SPS (2 mg/kg). Group-4 was supplemented with SPS (2 mg/kg) through oral gavage. The experiment was conducted for 56 days. The exposure to PQ significantly lowered the activities of catalase (CAT), glutathione reductase (GSR), superoxide dismutase (SOD) as well as glutathione peroxidase (GPx). Whereas, a substantial increase was observed in dead sperms number, abnormalities in the tail, head as well as midpiece of sperms in PQ intoxicated rats. Moreover, a significant increase in the level of ROS and malondialdehyde (MDA) was noticed in PQ administrated group. Furthermore, steroidogenic enzymes expression was significantly decreased in PQ-intoxicated group, whereas the level of inflammatory markers was increased in PQ administrated rats. Besides, the expression of apoptotic markers was significantly escalated in PQ exposed rats, whereas the expression of anti-apoptotic markers was considerably reduced. A significant reduction in hormonal level was also noticed in the rats that were administrated with PQ. Moreover, the histopathological examination revealed that PQ significantly damaged the testicles. However, the supplementation of SPS with PQ significantly reduced the adverse effects of PQ in the testes of albino rats. Therefore, the current investigation demonstrated that SPS possesses a significant potential to avert PQ-induced testicular dysfunction due to its anti-apoptotic, androgenic, anti-oxidant and anti-inflammatory nature.

Analysis of ADORA2A rs5760423 and CYP1A2 rs762551 Genetic Variants in Patients with Alzheimer's Disease

Various studies have been conducted, exploring the genetic susceptibility of Alzheimer's disease (AD). Adenosine receptor subtype A2a (ADORA2A) and cytochrome P450 1A2 (CYP1A2) are implicated in pathways such as oxidative stress and caffeine metabolism, which are associated with AD. The aim of this study was to explore for any potential association between the ADORA2A rs5760423 and the CYP1A2 rs762551 genetic variants and AD. A case-control study was performed with a total of 654 subjects (327 healthy controls and 327 patients with AD). Five genetic models were assumed. We also examined the allele-allele combination of both variants. The value of 0.05 was considered as the statistical significance threshold. A statistically significant association was found between ADORA2A rs5760423 and AD, as the "T" allele was associated with increased AD risk in recessive (OR = 1.51 (1.03-2.21)) and log-additive (OR = 1.30 (1.04-1.62)) genetic modes. In the codominant model, the TT genotype was more prevalent compared to the GG genotype (OR = 1.71 (1.09-2.66)). The statistical significance was maintained after adjustment for sex. No association between CYP1A2 rs762551 or allele-allele combination and AD was detected. We provide preliminary indication for a possible association between the ADORA2A rs5760423 genetic polymorphism and AD.

ATH434 Rescues Pre-motor Hyposmia in a Mouse Model of Parkinsonism

Hyposmia is a prevalent prodromal feature of Parkinson's disease (PD), though the neuropathology that underlies this symptom is poorly understood. Unlike the substantia nigra, the status of metal homeostasis in the olfactory bulbs has not been characterized in PD. Given the increasing interest in metal modulation as a therapeutic avenue in PD, we sought to investigate bulbar metals and the effect of AT434 (formerly PBT434) an orally bioavailable, small molecule modulator of metal homeostasis on hyposmia in a mouse model of parkinsonism (the tau knockout (tau-/-) mouse). 5.5 (pre-hyposmia) and 13.5-month-old (pre-motor) mice were dosed with ATH434 (30 mg/kg/day, oral gavage) for 6 weeks. Animals then underwent behavioral analysis for olfactory and motor phenotypes. The olfactory bulbs and the substantia nigra were then collected and analyzed for metal content, synaptic markers, and dopaminergic cell number. ATH434 was able to prevent the development of hyposmia in young tau-/- mice, which coincided with a reduction in bulbar iron and copper levels, an increase in synaptophysin, and a reduction in soluble α-synuclein. ATH434 was able to prevent the development of motor impairment in aged tau-/- mice, which coincided with a reduction in iron levels and reduced neurodegeneration in the substantia nigra. These data implicate metal dyshomeostasis in parkinsonian olfactory deficits, and champion a potential clinical benefit of ATH434 in both prodromal and clinical stages of PD.

Examining the role of paraoxonase 2 in the dopaminergic system of the mouse brain

BACKGROUND

Paraoxonase 2 (PON2) is an intracellular antioxidant enzyme located at the inner mitochondrial membrane. Previous studies have found PON2 to be an important antioxidant in a variety of cellular systems, such as the cardiovascular and renal system. Recent work has also suggested that PON2 plays an important role in the central nervous system (CNS), as decreased PON2 expression in the CNS leads to higher oxidative stress and subsequent cell toxicity. However, the precise role of PON2 in the CNS is still largely unknown, and what role it may play in specific regions of the brain remains unexamined. Dopamine metabolism generates considerable oxidative stress and antioxidant function is critical to the survival of dopaminergic neurons, providing a potential mechanism for PON2 in the dopaminergic system.

METHODS

In this study, we investigated the role of PON2 in the dopaminergic system of the mouse brain by comparing transcript and protein expression of dopaminergic-related genes in wildtype (WT) and PON2 deficient (PON2-def) mouse striatum, and exposing WT cultured primary neurons to dopamine receptor agonists.

RESULTS

We found alterations in multiple key dopaminergic genes at the transcript level, however many of these changes were not observed at the protein level. In cultured neurons, PON2 mRNA and protein were increased upon exposure to quinpirole, a dopamine receptor 2/3 (DRD2/3) agonist, but not fenoldopam, a dopamine receptor 1/5 (DRD1/5) agonist, suggesting a receptor-specific role in dopamine signaling.

CONCLUSIONS

Our findings suggest PON2 deficiency significantly impacts the dopaminergic system at the transcript level and may play a role in mitigating oxidative stress in this system further downstream through dopamine receptor signaling.

Crosstalk between regulatory non-coding RNAs and oxidative stress in Parkinson’s disease

Parkinson’s disease is the second most common neurodegenerative disease after Alzheimer’s disease, which imposes an ever-increasing burden on society. Many studies have indicated that oxidative stress may play an important role in Parkinson’s disease through multiple processes related to dysfunction or loss of neurons. Besides, several subtypes of non-coding RNAs are found to be involved in this neurodegenerative disorder. However, the interplay between oxidative stress and regulatory non-coding RNAs in Parkinson’s disease remains to be clarified. In this article, we comprehensively survey and overview the role of regulatory ncRNAs in combination with oxidative stress in Parkinson’s disease. The interaction between them is also summarized. We aim to provide readers with a relatively novel insight into the pathogenesis of Parkinson’s disease, which would contribute to the development of pre-clinical diagnosis and treatment.

Peripheral blood lymphocyte phenotypes in Alzheimer and Parkinson's diseases

INTRODUCTION

Neuroinflammation is involved in the pathophysiology of various neurological disorders, in particular Alzheimer disease (AD) and Parkinson's disease (PD). Alterations in the blood-brain barrier may allow peripheral blood lymphocytes to enter the central nervous system; these may participate in disease pathogenesis.

OBJECTIVE

To evaluate the peripheral blood lymphocyte profiles of patients with AD and PD and their association with the disease and its progression.

METHODS

The study included 20 patients with AD, 20 with PD, and a group of healthy individuals. Ten of the patients with AD and 12 of those with PD were evaluated a second time 17 to 27 months after the start of the study. Lymphocyte subpopulations and their activation status were determined by flow cytometry. All patients underwent neurological examinations using internationally validated scales.

RESULTS

Compared to healthy individuals, patients with AD and PD showed significantly higher levels of activated lymphocytes, lymphocytes susceptible to apoptosis, central memory T cells, and regulatory T and B cells. As the diseases progressed, there was a significant decrease in activated cells (CD4+ CD38+ and CD8+ CD38+ in PD and AD, CD4+ CD69+ and CD8+ CD69+ in PD), T cells susceptible to apoptosis, and some regulatory populations (CD19+ CD5+ IL10+ in PD and AD, CD19+ CD5+ IL10+ FoxP3+, CD4+ FoxP3+ CD25+ CD45RO+ in PD). In patients with AD, disease progression was associated with lower percentages of CD4+ CD38+ cells and higher percentages of effector CD4 cells at the beginning of the study. Significant differences were observed between both diseases.

CONCLUSIONS

This study provides evidence of changes in peripheral blood lymphocyte phenotypes associated with AD and PD and their severity. Considering effective blood-brain communication, our results open new avenues of research into immunomodulation therapies to treat these diseases.

Peripheral blood lymphocyte phenotypes in Alzheimer and Parkinson's diseases

INTRODUCTION

Neuroinflammation is involved in the pathophysiology of various neurological disorders, in particular Alzheimer disease (AD) and Parkinson's disease (PD). Alterations in the blood-brain barrier may allow peripheral blood lymphocytes to enter the central nervous system; these may participate in disease pathogenesis.

OBJECTIVE

To evaluate the peripheral blood lymphocyte profiles of patients with AD and PD and their association with the disease and its progression.

METHODS

The study included 20 patients with AD, 20 with PD, and a group of healthy individuals. Ten of the patients with AD and 12 of those with PD were evaluated a second time 17 to 27 months after the start of the study. Lymphocyte subpopulations and their activation status were determined by flow cytometry. All patients underwent neurological examinations using internationally validated scales.

RESULTS

Compared to healthy individuals, patients with AD and PD showed significantly higher levels of activated lymphocytes, lymphocytes susceptible to apoptosis, central memory T cells, and regulatory T and B cells. As the diseases progressed, there was a significant decrease in activated cells (CD4+ CD38+ and CD8+ CD38 + in PD and AD, CD4+ CD69+ and CD8+ CD69+ in PD), T cells susceptible to apoptosis, and some regulatory populations (CD19+ CD5+ IL10+ in PD and AD, CD19+ CD5+ IL10+ FoxP3+, CD4+ FoxP3+ CD25+ CD45RO+ in PD). In patients with AD, disease progression was associated with lower percentages of CD4+ CD38+ cells and higher percentages of effector CD4 cells at the beginning of the study. Significant differences were observed between both diseases.

CONCLUSIONS

This study provides evidence of changes in peripheral blood lymphocyte phenotypes associated with AD and PD and their severity. Considering effective blood-brain communication, our results open new avenues of research into immunomodulation therapies to treat these diseases.

Attenuating effect of Prosopis cineraria against paraquat-induced toxicity in prepubertal mice, Mus musculus

Several herbicides, especially paraquat, are persistent organic pollutants which cause damage to humans and animals through reactive oxygen and nitrogen species. Prosopis cineraria (L.) Druce exhibits antioxidant activity and can effectively manage tremors. Therefore, the present research assessed the preventive effect of Prosopis cineraria (L.) Druce ethanolic extract (PCDE) against paraquat-induced toxicity in prepubertal mice. The plant extract was chemically characterized by a high-performance liquid chromatography-diode array detector (HPLC-DAD). The PCDE was orally administered to prepubertal mice for continuous 21 days, 2 h before paraquat exposure (2 mg/kg for consecutive 3 days per week for 3 weeks). The changes in behavior, motor coordination, memory, muscle movement, anxiety, and neurotransmitter levels in the brain were assessed. Histopathology and estimation of oxidative stress parameters in the brain, liver, kidney, and heart tissues were also carried out. HPLC-DAD analysis showed a high amount of quercetin, kaempferol, and ellagic acid derivatives in the plant extract. The PCDE showed improved muscle coordination, muscle movement and memory, and reduced anxiety in prepubertal mice. Moreover, levels of dopamine and noradrenaline were increased in the brain. It successfully ameliorated the oxidative stress in different organs by increasing the level of glutathione and superoxide dismutase and by reducing malondialdehyde. The histopathological assessment showed the plant extract effectively mitigated paraquat-induced pathological lesions in the neurons, neuroglia, hepatocytes, and kidney tissues. It is concluded from the present study that the treatment with PCDE had prevented the paraquat-induced toxicity in the brain, liver, kidney, and heart through the reduction of oxidative stress possibly due to the presence of phenolic compounds and flavonoids.

Animal models of Parkinson's disease: a guide to selecting the optimal model for your research

Parkinson's disease (PD) is a complex, multisystem disorder characterised by α-synuclein (SNCA) pathology, degeneration of nigrostriatal dopaminergic neurons, multifactorial pathogenetic mechanisms and expression of a plethora of motor and non-motor symptoms. Animal models of PD have already been instructive in helping us unravel some of these aspects. However, much remains to be discovered, requiring continued interrogation by the research community. In contrast with the situation for many neurological disorders, PD benefits from of a wide range of available animal models (pharmacological, toxin, genetic and α-synuclein) but this makes selection of the optimal one for a given study difficult. This is especially so when a study demands a model that displays a specific combination of features. While many excellent reviews of animal models already exist, this review takes a different approach with the intention of more readily informing this decision-making process. We have considered each feature of PD in turn - aetiology, pathology, pathogenesis, motor dysfunctions and non-motor symptoms (NMS) - highlighting those animal models that replicate each. By compiling easily accessible tables and a summary figure, we aim to provide the reader with a simple, go-to resource for selecting the optimal animal model of PD to suit their research needs.

Alpha-Synuclein as a Biomarker of Parkinson's Disease: Good, but Not Good Enough

Parkinson's disease (PD) is the second most common neurodegenerative disorder of the elderly, presenting primarily with symptoms of motor impairment. The disease is diagnosed most commonly by clinical examination with a great degree of accuracy in specialized centers. However, in some cases, non-classical presentations occur when it may be difficult to distinguish the disease from other types of degenerative or non-degenerative movement disorders with overlapping symptoms. The diagnostic difficulty may also arise in patients at the early stage of PD. Thus, a biomarker could help clinicians circumvent such problems and help them monitor the improvement in disease pathology during anti-parkinsonian drug trials. This review first provides a brief overview of PD, emphasizing, in the process, the important role of α-synuclein in the pathogenesis of the disease. Various attempts made by the researchers to develop imaging, genetic, and various biochemical biomarkers for PD are then briefly reviewed to point out the absence of a definitive biomarker for this disorder. In view of the overwhelming importance of α-synuclein in the pathogenesis, a detailed analysis is then made of various studies to establish the biomarker potential of this protein in PD; these studies measured total α-synuclein, oligomeric, and post-translationally modified forms of α-synuclein in cerebrospinal fluid, blood (plasma, serum, erythrocytes, and circulating neuron-specific extracellular vesicles) and saliva in combination with certain other proteins. Multiple studies also examined the accumulation of α-synuclein in various forms in PD in the neural elements in the gut, submandibular glands, skin, and the retina. The measurements of the levels of certain forms of α-synuclein in some of these body fluids or their components or peripheral tissues hold a significant promise in establishing α-synuclein as a definitive biomarker for PD. However, many methodological issues related to detection and quantification of α-synuclein have to be resolved, and larger cross-sectional and follow-up studies with controls and patients of PD, parkinsonian disorders, and non-parkinsonian movement disorders are to be undertaken.

Can a Micronutrient Mixture Delay the Onset and Progression of Symptoms of Single-Point Mutation Diseases?

Single-point mutation diseases in which substitution of one nucleotide with another in a gene occurs include familial Alzheimer's disease (fAD), familial Parkinson's disease (fPD), and familial Creutzfeldt-Jacob disease (fCJD) as well as Huntington's disease (HD), sickle cell anemia, and hemophilia. Inevitability of occurrence of these diseases is certain. However, the time of appearance of symptoms could be influenced by the diet, environment, and possibly other genetic factors. There are no effective approaches to delay the onset or progression of symptoms of these diseases. The fact that increased oxidative stress and inflammation significantly contribute to the initiation and progression of these point mutation diseases shows that antioxidants could be useful. The major objectives are (a) to present evidence that increased oxidative stress and chronic inflammation are associated with selected single-point mutation diseases, such as fAD, fPD, and fCJD, HD, sickle cell anemia, and hemophilia; (b) to describe limited studies on the role of individual antioxidants in experimental models of some of these diseases; and (c) to discuss a rationale for utilizing a comprehensive mixture of micronutrients, which may delay the development and progression of symptoms of above diseases by simultaneously reducing oxidative and inflammatory damages.Key teaching pointsSelected single-point mutation diseases and their pattern of inheritanceCharacteristics of each selected single-point mutation diseaseEvidence for increased oxidative stress and inflammation in each diseasePotential reasons for failure of single antioxidants in human studiesRationale for using a comprehensive mixture of micronutrients in delaying the onset and progression of single-point mutation diseases.

Characterization of nonmotor behavioral impairments and their neurochemical mechanisms in the MitoPark mouse model of progressive neurodegeneration in Parkinson's disease

Mitochondrial dysfunction has been implicated as a key player in the pathogenesis of Parkinson's disease (PD). The MitoPark mouse, a transgenic mitochondrial impairment model developed by specific inactivation of TFAM in dopaminergic neurons, spontaneously exhibits progressive motor deficits and neurodegeneration, recapitulating several features of PD. Since nonmotor symptoms are now recognized as important features of the prodromal stage of PD, we comprehensively assessed the clinically relevant motor and nonmotor deficiencies from ages 8-24 wk in both male and female MitoPark mice and their littermate controls. As expected, motor deficits in MitoPark mice began around 12-14 wk and became severe by 16-24 wk. Interestingly, MitoPark mice exhibited olfactory deficits in the novel and social scent tests as early as 10-12 wk as compared to age-matched littermate controls. Additionally, male MitoPark mice showed spatial memory deficits before female mice, beginning at 8 wk and becoming most severe at 16 wk, as determined by the Morris water maze. MitoPark mice between 16 and 24 wk spent more time immobile in forced swim and tail suspension tests, and made fewer entries into open arms of the elevated plus maze, indicating a depressive and anxiety-like phenotype, respectively. Importantly, depressive behavior as determined by immobility in forced swim test was reversible by antidepressant treatment with desipramine. Neurochemical and mechanistic studies revealed significant changes in CREB phosphorylation, BDNF, and catecholamine levels as well as neurogenesis in key brain regions. Collectively, our results indicate that MitoPark mice progressively exhibit deficits in olfactory discrimination, cognitive learning and memory, and anxiety- and depression-like behaviors as well as key neurochemical signaling associated with nonmotor deficits in PD. Thus, MitoPark mice can serve as an invaluable model for studying nonmotor deficits in addition to studying the motor deficits related to pathology in PD.

Improvement of Oxidative Stress and Mitochondrial Dysfunction by β-Caryophyllene: A Focus on the Nervous System

Mitochondrial dysfunction results in a series of defective cellular events, including decreased adenosine triphosphate (ATP) production, enhanced reactive oxygen species (ROS) output, and altered proteastasis and cellular quality control. An enhanced output of ROS may damage mitochondrial components, such as mitochondrial DNA and elements of the electron transport chain, resulting in the loss of proper electrochemical gradient across the mitochondrial inner membrane and an ensuing shutdown of mitochondrial energy production. Neurons have an increased demand for ATP and oxygen, and thus are more prone to damage induced by mitochondrial dysfunction. Mitochondrial dysfunction, damaged electron transport chains, altered membrane permeability and Ca²⁺ homeostasis, and impaired mitochondrial defense systems induced by oxidative stress, are pathological changes involved in neurodegenerative disorders. A growing body of evidence suggests that the use of antioxidants could stabilize mitochondria and thus may be suitable for preventing neuronal loss. Numerous natural products exhibit the potential to counter oxidative stress and mitochondrial dysfunction; however, science is still looking for a breakthrough in the treatment of neurodegenerative disorders. β-caryophyllene is a bicyclic sesquiterpene, and an active principle of essential oils derived from a large number of spices and food plants. As a selective cannabinoid receptor 2 (CB2) agonist, several studies have reported it as possessing numerous pharmacological activities such as antibacterial (e.g., Helicobacter pylori), antioxidant, anti-inflammatory, analgesic (e.g., neuropathic pain), anti-neurodegenerative and anticancer properties. The present review mainly focuses on the potential of β-caryophyllene in reducing oxidative stress and mitochondrial dysfunction, and its possible links with neuroprotection.

Genetic and Environmental Factors Influence the Pleomorphy of LRRK2 Parkinsonism

Missense mutations in the LRRK2 gene were first identified as a pathogenic cause of Parkinson's disease (PD) in 2004. Soon thereafter, a founder mutation in LRRK2, p.G2019S (rs34637584), was described, and it is now estimated that there are approximately 100,000 people worldwide carrying this risk variant. While the clinical presentation of LRRK2 parkinsonism has been largely indistinguishable from sporadic PD, disease penetrance and age at onset can be quite variable. In addition, its neuropathological features span a wide range from nigrostriatal loss with Lewy body pathology, lack thereof, or atypical neuropathology, including a large proportion of cases with concomitant Alzheimer's pathology, hailing LRRK2 parkinsonism as the "Rosetta stone" of parkinsonian disorders, which provides clues to an understanding of the different neuropathological trajectories. These differences may result from interactions between the LRRK2 mutant protein and other proteins or environmental factors that modify LRRK2 function and, thereby, influence pathobiology. This review explores how potential genetic and biochemical modifiers of LRRK2 function may contribute to the onset and clinical presentation of LRRK2 parkinsonism. We review which genetic modifiers of LRRK2 influence clinical symptoms, age at onset, and penetrance, what LRRK2 mutations are associated with pleomorphic LRRK2 neuropathology, and which environmental modifiers can augment LRRK2 mutant pathophysiology. Understanding how LRRK2 function is influenced and modulated by other interactors and environmental factors-either increasing toxicity or providing resilience-will inform targeted therapeutic development in the years to come. This will allow the development of disease-modifying therapies for PD- and LRRK2-related neurodegeneration.

ROS networks: designs, aging, Parkinson's disease and precision therapies

How the network around ROS protects against oxidative stress and Parkinson's disease (PD), and how processes at the minutes timescale cause disease and aging after decades, remains enigmatic. Challenging whether the ROS network is as complex as it seems, we built a fairly comprehensive version thereof which we disentangled into a hierarchy of only five simpler subnetworks each delivering one type of robustness. The comprehensive dynamic model described in vitro data sets from two independent laboratories. Notwithstanding its five-fold robustness, it exhibited a relatively sudden breakdown, after some 80 years of virtually steady performance: it predicted aging. PD-related conditions such as lack of DJ-1 protein or increased α-synuclein accelerated the collapse, while antioxidants or caffeine retarded it. Introducing a new concept (aging-time-control coefficient), we found that as many as 25 out of 57 molecular processes controlled aging. We identified new targets for "life-extending interventions": mitochondrial synthesis, KEAP1 degradation, and p62 metabolism.

Antioxidant and Anti-inflammatory Mechanisms of Neuroprotection by Ursolic Acid: Addressing Brain Injury, Cerebral Ischemia, Cognition Deficit, Anxiety, and Depression

Ursolic acid (UA) is a pentacyclic triterpene which is found in common herbs and medicinal plants that are reputed for a variety of pharmacological effects. Both as an active principle of these plants and as a nutraceutical ingredient, the pharmacology of UA in the CNS and other organs and systems has been extensively reported in recent years. In this communication, the antioxidant and anti-inflammatory axis of UA's pharmacology is appraised for its therapeutic potential in some common CNS disorders. Classic examples include the traumatic brain injury (TBI), cerebral ischemia, cognition deficit, anxiety, and depression. The pharmacological efficacy for UA is demonstrated through the therapeutic principle of one drug → multitargets → one/many disease(s). Both specific enzymes and receptor targets along with diverse pharmacological effects associated with oxidative stress and inflammatory signalling are scrutinised.

2D-DIGE as a strategy to identify serum protein biomarkers to monitor pharmacological efficacy in dopamine-dictated states of Parkinson's disease and schizophrenia

OBJECTIVES

Parkinson's disease and schizophrenia are clinical scenarios that occur due to dopaminergic deficit and hyperactivity in the midbrain, respectively. Current pharmacological interventions for these two diseases therefore aim to restore normal dopamine levels in the midbrain. But during therapy, there is a overshooting of dopamine concentrations that result in hallucinations in Parkinson's disease patients and extra-pyramidal symptoms in schizophrenic patients. This causes a lot of inconvenience to the patents and the clinicians. There are no tests currently available to monitor drug efficacy in these two neuropsychiatric diseases.

MATERIALS AND METHODS

Parkinson's disease and schizophrenic naïve patients were recruited. Serum proteins isolated from these two clinical phenotypes were labeled with fluorescent cyanine dyes and analyzed by two-dimensional difference in gel electrophoresis proteomic experiment. Differentially expressed spots that had consistent expression pattern across five sets of biological replicate gels were trypsin digested and subjected to mass spectrometric analysis for protein identification. Validation experiments were done for the identified proteins using antibody-based assay on a patient cohort that included naïve, treated, and those who had side effects.

RESULTS

Serum α- and β-globin chains were identified as differentially expressed proteins having threefold higher expressions in Parkinson's patients as compared to schizophrenia. Interestingly, concentrations of these two proteins had an inverse correlation across clinical phenotypes in the dopaminergic spectrum. RBC contamination as a source for these proteins was ruled out.

CONCLUSION

There is a clear association of free serum globin with dopaminergic clinical states. This lays a platform for protein biomarker-based monitoring of pharmacological efficacy in Parkinson's disease and schizophrenia.

P38 Mitogen-activated Protein Kinase and Parkinson's Disease

Parkinson's disease, the second major neurodegenerative disease, has created a great impact on the elder people. Although the mechanisms underlying Parkinson's disease are not fully understood, considerable evidence suggests that neuro-inflammation, oxidative stress, mitochondrial dysfunction, cell proliferation, differentiation and apoptosis are involved in the disease. p38MAPK, an important member of the mitogen-activated protein family, controls several important functions in the cell, suggesting a potential pathogenic role in PD. This review provides a brief description of the role and mechanism of p38MAPK in Parkinson's disease.

Alterations in the E3 ligases Parkin and CHIP result in unique metabolic signaling defects and mitochondrial quality control issues

E3 ligases are essential scaffold proteins, facilitating the transfer of ubiquitin from E2 enzymes to lysine residues of client proteins via isopeptide bonds. The specificity of substrate binding and the expression and localization of E3 ligases can, however, endow these proteins with unique features with variable effects on mitochondrial, metabolic and CNS function. By comparing and contrasting two E3 ligases, Parkin and C-terminus of HSC70-Interacting protein (CHIP) we seek to highlight the biophysical properties that may promote mitochondrial dysfunction, acute stress signaling and critical developmental periods to cease in response to mutations in these genes. Encoded by over 600 human genes, RING-finger proteins are the largest class of E3 ligases. Parkin contains three RING finger domains, with R1 and R2 separated by an in-between region (IBR) domain. Loss-of-function mutations in Parkin were identified in patients with early onset Parkinson's disease. CHIP is a member of the Ubox family of E3 ligases. It contains an N-terminal TPR domain and forms unique asymmetric homodimers. While CHIP can substitute for mutated Parkin and enhance survival, CHIP also has unique functions. The differences between these proteins are underscored by the observation that unlike Parkin-deficient animals, CHIP-null animals age prematurely and have significantly impaired motor function. These properties make these E3 ligases appealing targets for clinical intervention. In this work, we discuss how biophysical and metabolic properties of these E3 ligases have driven rapid progress in identifying roles for E3 ligases in development, proteostasis, mitochondrial biology, and cell health, as well as new data about how these proteins alter the CNS proteome.

Nrf2 activation attenuates the early suppression of mitochondrial respiration due to the α-synuclein overexpression

BACKGROUND

α-synuclein (SNCA) accumulation in the substantia nigra is one of the characteristic pathologies of Parkinson's disease (PD). A53T missense mutations in the SNCA gene has been proved to enhance the expression of SNCA and accelerate the onset of PD. Mitochondrial dysfunction in SNCA aggregation has been under debate for decades but the causal relationship remains uncertain. At a later stage of PD, the cellular dysfunctions are complicated and multiple factors are tangled. Our aim here is to investigate the mitochondrial functional changes and clarify the main causal mechanism at earlier-stage of PD.

METHODS

We used the mutant A53T SNCA-expressed neuro 2a (N2a) cells without detectable cell death to investigate: 1) whether SNCA overexpression impairs the mitochondrial respiration and biogenesis. 2) The role of nuclear factor (erythroid-derived 2)-like 2 (Nrf2) signal in SNCA-induced mitochondria dysfunction.

RESULTS

Accompanying with the increment of SNCA, reactive oxygen species (ROS) accumulation was increased. The maximal respiratory capacity was suppressed. Meanwhile, mitochondrial complex 1 activity and the activity of nicotinamide adenine dinucleotide (NADH) cytochrome C reductase (NCCR) were decreased. Moreover, the mitochondrial DNA (mtDNA) copy number was decreased. On the other hand, the nuclear peroxisome proliferator-activated receptor-gamma coactivator 1α (PGC-1α), Nrf2, and the cytosolic mitochondrial transcription factor A (TFAM) were increased at an early stage and declined thereafter. Above factors triggered by SNCA were reversed by tBHQ, a Nrf2 activator.

CONCLUSION

These results suggested that at an early stage, SNCA-overexpressed increase mtROS accumulation, mitochondrial dysfunction and mtDNA decrement. Nrf2, PGC-1α and TFAM were upregulated to compromise mitochondrial dysfunction. tBHQ effectively reversed the SNCA-induced mitochondrial dysfunction.

Mito-Apocynin Prevents Mitochondrial Dysfunction, Microglial Activation, Oxidative Damage, and Progressive Neurodegeneration in MitoPark Transgenic Mice

AIMS

Parkinson's disease (PD) is a neurodegenerative disorder characterized by progressive motor deficits and degeneration of dopaminergic neurons. Caused by a number of genetic and environmental factors, mitochondrial dysfunction and oxidative stress play a role in neurodegeneration in PD. By selectively knocking out mitochondrial transcription factor A (TFAM) in dopaminergic neurons, the transgenic MitoPark mice recapitulate many signature features of the disease, including progressive motor deficits, neuronal loss, and protein inclusions. In the present study, we evaluated the neuroprotective efficacy of a novel mitochondrially targeted antioxidant, Mito-apocynin, in MitoPark mice and cell culture models of neuroinflammation and mitochondrial dysfunction.

RESULTS

Oral administration of Mito-apocynin (10 mg/kg, thrice a week) showed excellent central nervous system bioavailability and significantly improved locomotor activity and coordination in MitoPark mice. Importantly, Mito-apocynin also partially attenuated severe nigrostriatal degeneration in MitoPark mice. Mechanistic studies revealed that Mito-apo improves mitochondrial function and inhibits NOX2 activation, oxidative damage, and neuroinflammation.

INNOVATION

The properties of Mito-apocynin identified in the MitoPark transgenic mouse model strongly support potential clinical applications for Mito-apocynin as a viable neuroprotective and anti-neuroinflammatory drug for treating PD when compared to conventional therapeutic approaches.

CONCLUSION

Collectively, our data demonstrate, for the first time, that a novel orally active apocynin derivative improves behavioral, inflammatory, and neurodegenerative processes in a severe progressive dopaminergic neurodegenerative model of PD. Antioxid. Redox Signal. 27, 1048-1066.

Proximate Mediators of Microvascular Dysfunction at the Blood-Brain Barrier: Neuroinflammatory Pathways to Neurodegeneration

Current projections are that by 2050 the numbers of people aged 65 and older with Alzheimer's disease (AD) in the US may increase threefold while dementia is projected to double every 20 years reaching ~115 million by 2050. AD is clinically characterized by progressive dementia and neuropathologically by neuronal and synapse loss, accumulation of amyloid plaques, and neurofibrillary tangles (NFTs) in specific brain regions. The preclinical or presymptomatic stage of AD-related brain changes may begin over 20 years before symptoms occur, making development of noninvasive biomarkers essential. Distinct from neuroimaging and cerebrospinal fluid biomarkers, plasma or serum biomarkers can be analyzed to assess (i) the presence/absence of AD, (ii) the risk of developing AD, (iii) the progression of AD, or (iv) AD response to treatment. No unifying theory fully explains the neurodegenerative brain lesions but neuroinflammation (a lethal stressor for healthy neurons) is universally present. Current consensus is that the earlier the diagnosis, the better the chance to develop treatments that influence disease progression. In this article we provide a detailed review and analysis of the role of the blood-brain barrier (BBB) and damage-associated molecular patterns (DAMPs) as well as coagulation molecules in the onset and progression of these neurodegenerative disorders.

The novel compound PBT434 prevents iron mediated neurodegeneration and alpha-synuclein toxicity in multiple models of Parkinson's disease

Elevated iron in the SNpc may play a key role in Parkinson's disease (PD) neurodegeneration since drug candidates with high iron affinity rescue PD animal models, and one candidate, deferirpone, has shown efficacy recently in a phase two clinical trial. However, strong iron chelators may perturb essential iron metabolism, and it is not yet known whether the damage associated with iron is mediated by a tightly bound (eg ferritin) or lower-affinity, labile, iron pool. Here we report the preclinical characterization of PBT434, a novel quinazolinone compound bearing a moderate affinity metal-binding motif, which is in development for Parkinsonian conditions. In vitro, PBT434 was far less potent than deferiprone or deferoxamine at lowering cellular iron levels, yet was found to inhibit iron-mediated redox activity and iron-mediated aggregation of α-synuclein, a protein that aggregates in the neuropathology. In vivo, PBT434 did not deplete tissue iron stores in normal rodents, yet prevented loss of substantia nigra pars compacta neurons (SNpc), lowered nigral α-synuclein accumulation, and rescued motor performance in mice exposed to the Parkinsonian toxins 6-OHDA and MPTP, and in a transgenic animal model (hA53T α-synuclein) of PD. These improvements were associated with reduced markers of oxidative damage, and increased levels of ferroportin (an iron exporter) and DJ-1. We conclude that compounds designed to target a pool of pathological iron that is not held in high-affinity complexes in the tissue can maintain the survival of SNpc neurons and could be disease-modifying in PD.

Behavioral Phenotyping and Pathological Indicators of Parkinson's Disease in C. elegans Models

Parkinson's disease (PD) is a neurodegenerative disorder with symptoms that progressively worsen with age. Pathologically, PD is characterized by the aggregation of α-synuclein in cells of the substantia nigra in the brain and loss of dopaminergic neurons. This pathology is associated with impaired movement and reduced cognitive function. The etiology of PD can be attributed to a combination of environmental and genetic factors. A popular animal model, the nematode roundworm Caenorhabditis elegans, has been frequently used to study the role of genetic and environmental factors in the molecular pathology and behavioral phenotypes associated with PD. The current review summarizes cellular markers and behavioral phenotypes in transgenic and toxin-induced PD models of C. elegans.

Treadmill exercise alleviates depressive symptoms in rotenone-induced Parkinson disease rats

Parkinson disease (PD) is characterized by selective loss of the dopaminergic neurons. The symptoms of depression following PD are closely associated with reduced activity of the serotonergic system in the dorsal raphe. We explored the antidepressive effect of exercise and its possible mechanism using the rotenone-induced PD rats. PD rats were induced by subcutaneously injection with rotenone for 14 days. The rats in the exercise groups were made to run on a treadmill for 30 min once a day during 14 consecutive days. Forced swimming test, immunohistochemistry for serotonin (5-hydroxytryptamine, 5-HT), tryptophan hydroxylase (TPH), and western blot for serotonin 1A (5-HT1A) receptor were conducted. Injection of rotenone induced PD rats. PD rats showed depressive state and treadmill exercise ameliorated this depressive state. 5-HT, TPH, and 5-HT1A receptor expressions in the dorsal raphe were suppressed by rotenone injection and treadmill exercise increased the expressions of 5-HT, TPH, and 5-HT1A receptor in the rotenone-injected rats. The present results show that treadmill exercise ameliorated depressive symptoms in the rotenone-induced PD rats. The antidepressive effect of treadmill exercise might be ascribed to the enhancement of serotonergic function through upregulation of 5-HT1A expression in the dorsal raphe.

Potential Role of Caffeine in the Treatment of Parkinson's Disease

Parkinson’s disease [PD] is the second most common neurodegenerative disorder after Alzheimer’s disease, affecting 1% of the population over the age of 55. The underlying neuropathology seen in PD is characterised by progressive loss of dopaminergic neurons in the substantia nigra pars compacta with the presence of Lewy bodies. The Lewy bodies are composed of aggregates of α-synuclein. The motor manifestations of PD include a resting tremor, bradykinesia, and muscle rigidity. Currently there is no cure for PD and motor symptoms are treated with a number of drugs including levodopa [L-dopa]. These drugs do not delay progression of the disease and often provide only temporary relief. Their use is often accompanied by severe adverse effects. Emerging evidence from both in vivo and in vitro studies suggests that caffeine may reduce parkinsonian motor symptoms by antagonising the adenosine A_2A receptor, which is predominately expressed in the basal ganglia. It is hypothesised that caffeine may increase the excitatory activity in local areas by inhibiting the astrocytic inflammatory processes but evidence remains inconclusive. In addition, the co-administration of caffeine with currently available PD drugs helps to reduce drug tolerance, suggesting that caffeine may be used as an adjuvant in treating PD. In conclusion, caffeine may have a wide range of therapeutic effects which are yet to be explored, and therefore warrants further investigation in randomized clinical trials.

Neuroprotective and anti-inflammatory effects of morin in a murine model of Parkinson's disease

Parkinson's disease (PD) is one of the most common neurodegenerative disorders and is characterized by loss of dopaminergic neurons in the substantia nigra (SN). Although the causes of PD are not understood, evidence suggests that oxidative stress, mitochondrial dysfunction, and inflammation are associated with its pathogenesis. Morin (3,5,7,2',4'-pentahydroxyflavone) is a flavonol found in wine and many herbs and fruits. Previous studies have suggested that morin prevents oxidative damage and inflammation and ameliorates mitochondrial dysfunction. The present study describes the neuroprotective effects of morin in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced mouse model of PD, and we report the results of our investigation into its neuroprotective mechanism in primary neurons and astrocytes. In the mouse model, morin pretreatment ameliorated motor dysfunction, protected against dopaminergic neuronal losses in SN and striatum, and alleviated MPTP-induced astrocyte activation. In vitro studies revealed that morin protected primary cultured neurons against 1-methyl-4-phenylpyridine (MPP(+) )-mediated reactive oxygen species production and mitochondrial membrane potential (MMP) disruption. In addition, morin effectively reduced MPP(+) -induced astroglial activation and nuclear translocation of nuclear factor-κB in primary cultured astrocytes. These results indicate that morin acts via multiple neuroprotective mechanisms in our mouse model and suggest that morin be viewed as a potential treatment and preventative for PD. © 2016 Wiley Periodicals, Inc.

Ganoderma Lucidum polysaccharides protect against MPP(+) and rotenone-induced apoptosis in primary dopaminergic cell cultures through inhibiting oxidative stress

Oxidative stress plays a pivotal role in the progressive neurodegeneration in Parkinson's disease (PD) which is responsible for disabling motor abnormalities in more than 6.5 million people worldwide. Polysaccharides are the main active constituents from Ganoderma lucidum which is characterized with anti-oxidant, antitumor and immunostimulant properties. In the present study, primary dopaminergic cell cultures prepared from embryonic mouse mesencephala were used to investigate the neuroprotective effects and the potential mechanisms of Ganoderma lucidum polysaccharides (GLP) on the degeneration of dopaminergic neurons induced by the neurotoxins methyl-4-phenylpyridine (MPP(+)) and rotenone. Results revealed that GLP can protect dopamine neurons against MPP(+) and rotenone at the concentrations of 100, 50 and 25 μg/ml in primary mesencephalic cultures in a dose-dependent manner. Interestingly, either with or without neurotoxin treatment, GLP treatment elevated the survival of THir neurons, and increased the length of neurites of dopaminergic neurons. The Trolox equivalent anti-oxidant capacity (TEAC) of GLP was determined to be 199.53 μmol Trolox/g extract, and the decrease of mitochondrial complex I activity induced by MPP(+) and rotenone was elevated by GLP treatment (100, 50, 25 and 12.5 μg/ml) in a dose dependent manner. Furthermore, GLP dramatically decreased the relative number of apoptotic cells and increased the declining mitochondrial membrane potential (ΔΨm) induced by MPP(+) and rotenone in a dose-dependent manner. In addition, GLP treatment reduced the ROS formation induced by MPP(+) and rotenone at the concentrations of 100, 50 and 25 μg/ml in a dose-dependent manner. Our study indicates that GLP possesses neuroprotective properties against MPP(+) and rotenone neurotoxicity through suppressing oxidative stress in primary mesencephalic dopaminergic cell culture owning to its antioxidant activities.

Organophosphate Pesticide Exposures, Nitric Oxide Synthase Gene Variants, and Gene-Pesticide Interactions in a Case-Control Study of Parkinson's Disease, California (USA)

BACKGROUND

Nitric oxide synthase (NOS) genes are candidates for Parkinson's disease (PD) because NOS enzymes produce nitric oxide (NO), a pro-oxidant that can damage neurons. Widely used organophosphate (OP) pesticides can induce oxidative stress and are reported to increase PD risk. Additionally, two single nucleotide polymorphisms (SNPs) from the PON1 (paraoxonase 1) gene influence the ability to metabolize OPs.

OBJECTIVE

Here, we investigated contributions of NOS genes and OP pesticides to PD risk, controlling for PON1 status.

METHODS

In 357 incident PD cases and 495 population controls, we investigated eight NOS SNPs and interactions with both household and ambient agricultural OP exposures assessed with geographic information system (GIS).

RESULTS

In comparing PD in homozygous variant carriers of NOS2A rs1060826 versus homozygous wild-type or heterozygotes, we estimate an adjusted odds ratio (OR) of 1.51 (95% CI: 0.95, 2.41). When considering interactions between NOS1 rs2682826 and OP exposure from household use, the OR for frequent OP use alone was 1.30 (95% CI: 0.72, 2.34) and for the CT+TT genotype alone was 0.89 (95% CI: 0.58, 1.39), and for frequent OP use combined with the CT+TT genotype the OR was 2.84 (95% CI: 1.49, 5.40) (interaction p-value 0.04). Similar results were seen for ambient OP exposure. Interactions between OP exposure and three other NOS1 SNPs and a genetic risk score combining all NOS1 SNPs reached statistical significance.

CONCLUSIONS

We found that OP pesticides were more strongly associated with PD among participants with variant genotypes in NOS1, consistent with the importance of oxidative stress-inducing mechanisms. Our data provide evidence for NOS1 modifying PD risk in OP exposed populations.

CITATION

Paul KC, Sinsheimer JS, Rhodes SL, Cockburn M, Bronstein J, Ritz B. 2016. Organophosphate pesticide exposures, nitric oxide synthase gene variants, and gene-pesticide interactions in a case-control study of Parkinson's disease, California (USA). Environ Health Perspect 124:570-577; http://dx.doi.org/10.1289/ehp.1408976.

Physical Training Regulates Mitochondrial Parameters and Neuroinflammatory Mechanisms in an Experimental Model of Parkinson's Disease

This study aimed to evaluate the effects of two different protocols for physical exercise (strength and aerobic training) on mitochondrial and inflammatory parameters in the 6-OHDA experimental model of Parkinson's disease. Six experimental groups were used (n = 12 per group): untrained + vehicle (Sham), strength training + vehicle (STR), treadmill training + vehicle (TTR), untrained + 6-OHDA (U + 6-OHDA), strength training + 6-OHDA (STR + 6-OHDA), and treadmill training + 6-OHDA (TTR + 6-OHDA). The mice were subjected to strength or treadmill training for 8 weeks. PD was induced via striatal injection of 6-OHDA 24 h after the last exercise session. Mice were euthanized by cervical dislocation and the striatum and hippocampus were homogenized to determine levels of tyrosine hydroxylase (TH), nuclear factor kappa B (NF-κB) p65, and sirtuin 1 (Sirt1) by western blot; tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), IL-17, interferon-γ (IFN-γ), and transforming growth factor β1 (TGF-β1) levels by ELISA; NO content; and complex I (CI) activity. STR + 6-OHDA mice had higher TH levels and CI activity and lower NF-κB p65 and IFN-γ levels in the striatum compared to U + 6-OHDA mice, while TTR + 6-OHDA mice had higher Sirt1 levels and CI activity in both the striatum and the hippocampus, compared to U + 6-OHDA mice. Strength training increased CI activity and TH and Sirt1 levels and reduced NO, NF-κB p65, TNF-α, IFN-γ, IL-1β, and TGF-β1 levels in 6-OHDA mice, while treadmill exercise increased CI activity and NO, TH, and Sirt1 levels and reduced NF-κB p65, TNF-α, IFN-γ, and IL-1β levels. Our results demonstrated that both treadmill training and strength training promote neuroprotection, possibly by stimulating Sirt1 activity, which may in turn regulate both mitochondrial function and neuroinflammation via deacetylation of NF-κB p65. Changes in nitric oxide levels may also be a mechanism by which 6-OHDA-induced inflammation is controlled.

CHIP Is an Essential Determinant of Neuronal Mitochondrial Stress Signaling

AIMS

Determine the mechanism by which C-terminus of HSC70-interacting protein (CHIP) induction alters neuronal survival under conditions of mitochondrial stress induced by oxygen glucose deprivation.

RESULTS

We report that animals deficient in the E3 ubiquitin ligase, CHIP, have high baseline levels of central nervous system protein oxidation and lipid peroxidation, reduced antioxidant defenses, and decreased energetic status. Stress-associated molecules typically linked to Parkinson's disease such as the mitochondrial kinase, PTEN-inducible putative kinase 1 (PINK1), and another E3 ligase, Parkin, are upregulated in brains from CHIP knockout (KO) animals. Utilizing a novel biotin-avidin capture technique, we found that the oxidation status of Parkin and the mitochondrial fission protein, dynamin-related protein 1 (Drp1), are altered in a CHIP-dependent manner. We also found that following oxygen-glucose deprivation (OGD), the expression of CHIP, PINK1, and the autophagic marker, LC3, increase and there is activation of the redox-sensitive kinase p66(shc). Under conditions of OGD, CHIP relocalizes from the cytosol to mitochondria. Mitochondria from CHIP KO mice have profound impairments in stress response induced by calcium overload, resulting in accelerated permeability transition activity. While CHIP-deficient neurons are morphologically intact, they are more susceptible to OGD consistent with a previously unknown neuroprotective role for CHIP in maintaining mitochondrial homeostasis.

INNOVATION

CHIP relocalization to the mitochondria is essential for the regulation of mitochondrial integrity and neuronal survival following OGD.

CONCLUSIONS

CHIP is an essential regulator of neuronal bioenergetics and redox tone. Altering the expression of this protein has profound effects on neuronal survival when cells are exposed to OGD.

Oxidative Stress and Antioxidant Defense in Endometriosis and Its Malignant Transformation

The aim of this study was to investigate the role of redox status in endometriosis and its malignant transformation. A search was conducted between 1990 and 2014 through the English language literature (online MEDLINE PubMed database) using the keywords endometriosis combined with malignant transformation, oxidative stress, and antioxidant defense. In benign endometriosis, autoxidation and Fenton reaction of hemoglobin from the ferrous Fe²⁺ (oxyhemoglobin) state to the ferric Fe³⁺ (methemoglobin) state lead to production of excess reactive oxygen species (ROS) such as O₂⁻ and ^∙OH. Hemoglobin, heme, and iron derivatives in endometriotic cysts cause distortion in the homeostatic redox balance. Excess oxidative stress could trigger DNA damage and cell death. In contrast, endometriosis-associated ovarian cancer (EAOC) might be associated with an effective antioxidant defense, including heme oxygenases, cytochrome P450 family, and glutathione transferase family. The pattern of redox balance supports that enhanced antioxidants may be involved in the pathogenesis of malignant transformation. In conclusion, oxidant/antioxidant balance function is a double-edged sword, promoting cell death or carcinogenesis. Upregulation of antioxidant functions in endometriotic cyst may result in restoration of cell survival and subsequent malignant transformation.

Neuroprotective Properties of the Standardized Extract from Camellia sinensis (Green Tea) and Its Main Bioactive Components, Epicatechin and Epigallocatechin Gallate, in the 6-OHDA Model of Parkinson's Disease

Camellia sinensis (green tea) is largely consumed, mainly in Asia. It possesses several biological effects such as antioxidant and anti-inflammatory properties. The objectives were to investigate the neuroprotective actions of the standardized extract (CS), epicatechin (EC) and epigallocatechin gallate (EGCG), on a model of Parkinson's disease. Male Wistar rats were divided into SO (sham-operated controls), untreated 6-OHDA-lesioned and 6-OHDA-lesioned treated for 2 weeks with CS (25, 50, or 100 mg/kg), EC (10 mg/kg), or EGCG (10 mg/kg) groups. One hour after the last administration, animals were submitted to behavioral tests and euthanized and their striata and hippocampi were dissected for neurochemical (DA, DOPAC, and HVA) and antioxidant activity determinations, as well as immunohistochemistry evaluations (TH, COX-2, and iNOS). The results showed that CS and catechins reverted behavioral changes, indicating neuroprotection manifested as decreased rotational behavior, increased locomotor activity, antidepressive effects, and improvement of cognitive dysfunction, as compared to the untreated 6-OHDA-lesioned group. Besides, CS, EP, and EGCG reversed the striatal oxidative stress and immunohistochemistry alterations. These results show that the neuroprotective effects of CS and its catechins are probably and in great part due to its powerful antioxidant and anti-inflammatory properties, pointing out their potential for the prevention and treatment of PD.

Effect of low doses of herbicide paraquat on antioxidant defense in Drosophila

Despite a high toxicity, paraquat is one of the most widely used herbicides in the world. Our study evaluated the effect of paraquat exposure on antioxidant response and locomotion activity in Drosophila melanogaster. We examined the enzymatic activity of superoxide dismutase (SOD) and catalase, and the transcript levels of both enzymes. Flies were exposed to a wide range of paraquat concentrations (0.25 μM to 25 mM) for 12 h. SOD, at both transcript and enzymatic levels, revealed a biphasic dose-response curve with the peak at 2.5 μM paraquat. A similar dose-response curve was observed at transcript levels of catalase. Males revealed higher susceptibility to paraquat exposure, displaying higher lethality, increased levels of SOD activity, and increased peroxide levels than in females. We found that the exposure of females to 2.5 μM paraquat leads to an increase in locomotion activity. Because susceptibility to paraquat was enhanced by mating, the study supports the hypothesis of elevation of stress sensitivity as a physiological cost of reproduction.

Quantitative expression proteomics and phosphoproteomics profile of brain from PINK1 knockout mice: insights into mechanisms of familial Parkinson's disease

Parkinson's disease (PD) is an age-related, neurodegenerative motor disorder characterized by progressive degeneration of dopaminergic neurons in the substantia nigra pars compacta and presence of α-synuclein-containing protein aggregates. Mutations in the mitochondrial Ser/Thr kinase PTEN-induced kinase 1 (PINK1) are associated with an autosomal recessive familial form of early-onset PD. Recent studies have suggested that PINK1 plays important neuroprotective roles against mitochondrial dysfunction by phosphorylating and recruiting Parkin, a cytosolic E3 ubiquitin ligase, to facilitate elimination of damaged mitochondria via autophagy-lysosomal pathways. Loss of PINK1 in cells and animals leads to various mitochondrial impairments and oxidative stress, culminating in dopaminergic neuronal death in humans. Using a 2-D polyacrylamide gel electrophoresis proteomics approach, the differences in expressed brain proteome and phosphoproteome between 6-month-old PINK1-deficient mice and wild-type mice were identified. The observed changes in the brain proteome and phosphoproteome of mice lacking PINK1 suggest that defects in signaling networks, energy metabolism, cellular proteostasis, and neuronal structure and plasticity are involved in the pathogenesis of familial PD. Mutations in PINK1 are associated with an early-onset form of Parkinson's disease (PD). This study examines changes in the proteome and phosphoproteome of the PINK1 knockout mouse brain. Alterations were noted in several key proteins associated with: increased oxidative stress, aberrant cellular signaling, altered neuronal structure, decreased synaptic plasticity, reduced neurotransmission, diminished proteostasis networks, and altered metabolism. 14-3-3ε, 14-3-3 protein epsilon; 3-PGDH, phosphoglycerate dehydrogenase; ALDOA, aldolase A; APT1, acyl-protein thioesterase 1; CaM, calmodulin; CBR3, carbonyl reductase [NADPH] 3; ENO2, gamma-enolase; HPRT, hypoxanthine-guanine phosphoribosyltransferase; HSP70, heat-shock-related 70 kDa protein 2; IDHc, cytoplasmic isocitrate dehydrogenase [NADP+]; MAPK1, mitogen-activated protein kinase 1; MEK1, MAP kinase kinase 1; MDHc, cytoplasmic malate dehydrogenase; NFM, neurofilament medium polypeptide; NSF, N-ethylmaleimide-sensitive fusion protein; PHB, prohibitin; PINK1, PTEN-induced putative kinase 1; PPIaseA, peptidyl-prolyl cis-trans isomerase A; PSA2, proteasome subunit alpha type-2; TK, transketolase; VDAC-2, voltage-dependent anion-selective channel protein 2.

Oxidative stress, mitochondrial damage and neurodegenerative diseases

Oxidative stress and mitochondrial damage have been implicated in the pathogenesis of several neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease and amyotrophic lateral sclerosis. Oxidative stress is characterized by the overproduction of reactive oxygen species, which can induce mitochondrial DNA mutations, damage the mitochondrial respiratory chain, alter membrane permeability, and influence Ca²⁺ homeostasis and mitochondrial defense systems. All these changes are implicated in the development of these neurodegenerative diseases, mediating or amplifying neuronal dysfunction and triggering neurodegeneration. This paper summarizes the contribution of oxidative stress and mitochondrial damage to the onset of neurodegenerative eases and discusses strategies to modify mitochondrial dysfunction that may be attractive therapeutic interventions for the treatment of various neurodegenerative diseases.

The role of the immune system in neurodegenerative disorders: Adaptive or maladaptive?

Neurodegenerative diseases share common features, including catastrophic neuronal loss that leads to cognitive or motor dysfunction. Neuronal injury occurs in an inflammatory milieu that is populated by resident and sometimes, infiltrating, immune cells - all of which participate in a complex interplay between secreted inflammatory modulators and activated immune cell surface receptors. The importance of these immunomodulators is highlighted by the number of immune factors that have been associated with increased risk of neurodegeneration in recent genome-wide association studies. One of the more difficult tasks for designing therapeutic strategies for immune modulation against neurodegenerative diseases is teasing apart beneficial from harmful signals. In this regard, learning more about the immune components of these diseases has yielded common themes. These unifying concepts should eventually enable immune-based therapeutics for treatment of Alzheimer׳s and Parkinson׳s diseases and amyotrophic lateral sclerosis. Targeted immune modulation should be possible to temper maladaptive factors, enabling beneficial immune responses in the context of neurodegenerative diseases. This article is part of a Special Issue entitled SI: Neuroimmunology in Health And Disease.

Inhibition of neuronal cell mitochondrial complex I with rotenone increases lipid β-oxidation, supporting acetyl-coenzyme A levels

Rotenone is a naturally occurring mitochondrial complex I inhibitor with a known association with parkinsonian phenotypes in both human populations and rodent models. Despite these findings, a clear mechanistic link between rotenone exposure and neuronal damage remains to be determined. Here, we report alterations to lipid metabolism in SH-SY5Y neuroblastoma cells exposed to rotenone. The absolute levels of acetyl-CoA were found to be maintained despite a significant decrease in glucose-derived acetyl-CoA. Furthermore, palmitoyl-CoA levels were maintained, whereas the levels of many of the medium-chain acyl-CoA species were significantly reduced. Additionally, using isotopologue analysis, we found that β-oxidation of fatty acids with varying chain lengths helped maintain acetyl-CoA levels. Rotenone also induced increased glutamine utilization for lipogenesis, in part through reductive carboxylation, as has been found previously in other cell types. Finally, palmitoylcarnitine levels were increased in response to rotenone, indicating an increase in fatty acid import. Taken together, these findings show that alterations to lipid and glutamine metabolism play an important compensatory role in response to complex I inhibition by rotenone.

Acupuncture mechanism and redox equilibrium

Oxidative stress participates in the pathological process of various diseases. Acupuncture is a component of the health care system in China that can be traced back for at least 3000 years. Recently, increased evidences indicate that acupuncture stimulation could reduce oxidative damage in organisms under pathological state, but the exact mechanism remains unclear. This review focuses on the emerging links between acupuncture and redox modulation in various disorders, such as vascular dementia, Parkinson's disease, and hypertension, ranging from redox system, antioxidant system, anti-inflammatory system, and nervous system to signaling pathway. Although the molecular and cellular pathways studies of acupuncture effect on oxidative stress are preliminary, they represent an important step forward in the research of acupuncture antioxidative effect.

New covalent modifications of phosphatidylethanolamine by alkanals: mass spectrometry based structural characterization and biological effects

The pathophysiology of numerous human disorders, such as atherosclerosis, diabetes, obesity and Alzheimer's disease, is accompanied by increased production of reactive oxygen species (ROS). ROS can oxidatively damage nearly all biomolecules, including lipids, proteins and nucleic acids. In particular, (poly)unsaturated fatty acids within the phospholipid (PL) structure are easily oxidized by ROS to lipid peroxidation products (LPP) carrying reactive carbonyl groups. Carbonylated LPP are characterized by high in vivo toxicity due to their reactivity with nucleophilic substrates (Lys-, Cys-and His-residues in proteins or amino groups of phosphatidylethanolamines [PE]). Adducts of unsaturated LPP with PE amino groups have been reported before, whereas less is known about the reactivity of saturated alkanals - which are significantly increased in vivo under oxidative stress conditions - towards nucleophilic groups of PLs. Here, we present a study of new alkanal-dipalmitoyl-phosphatidylethanolamine (DPPE) adducts by MS-based approaches, using consecutive fragmentation (MS(n)) and multiple reaction monitoring techniques. At least eight different DPPE-hexanal adducts were identified, including Schiff base and amide adducts, six of which have not been reported before. The structures of these new compounds were determined by their fragmentation patterns using MS(n) experiments. The new PE-hexanal adducts contained dimeric and trimeric hexanal conjugates, including cyclic adducts. A new pyridine ring containing adduct of DPPE and hexanal was purified by HPLC, and its biological effects were investigated. Incubation of peripheral blood mononuclear cells and monocytes with modified DPPE did not result in increased production of TNF-α as one selected inflammation marker. However, incorporation of modified DPPE into 1,2-dipalmitoleoyl-sn-phosphatidylethanolamine multilamellar vesicles resulted in a negative shift of the transition temperature, indicating a possible role of alkanal-derived modifications in changes of membrane structure.