MPP+ induces necrostatin-1- and ferrostatin-1-sensitive necrotic death of neuronal SH-SY5Y cells

A novel NIR fluorescent probe for copper(ii) imaging in Parkinson's disease mouse brain

Abnormal copper ion (Cu2+) levels are considered to be one of the pathological factors of Parkinson's disease (PD), but the internal relationship between Cu2+ and PD progression remains elusive. Visualizing Cu2+ in the brain will be pivotal for comprehending the underlying pathophysiological processes of PD. In this work, a near-infrared (NIR) fluorescent probe, DDAO-Cu, capable of detecting Cu2+ with exceptional sensitivity (about 1.8 nM of detection limit) and selectivity, rapid response (<3 min), and deep tissue penetration, was designed for quantification and visualization of the Cu2+ level. It could detect not only Cu2+ in cells but also the changes in the Cu2+ level in the rotenone-induced cell and zebrafish PD models. Moreover, DDAO-Cu can cross the blood-brain barrier to image Cu2+ in the brain of PD model mice. The imaging result showed a significant increase in Cu2+ levels in brain regions of PD model mice, including the cerebral cortex, hippocampus, and striatum. Meanwhile, Cu2+ levels in the substantia nigra region were significantly reduced in PD model mice. It revealed the nuanced relationship of Cu2+ levels in different brain regions in the disease and indicated the pathological complexity of PD. Overall, DDAO-Cu represents a novel and practical tool for investigating Cu2+-related physiological and pathological processes underlying Parkinson's disease.

Lipid levels correlate with neuronal and dopaminergic markers during the differentiation of SH-SY5Y cells

Parkinson's Disease (PD) is characterised by the loss of dopaminergic neurons and the deposition of protein inclusions called Lewy Bodies (LBs). LBs are heterogeneous structures composed of protein and lipid molecules and their main constituent is the presynaptic protein α-synuclein. SH-SY5Y cells are neuroblastoma cells commonly used to model PD because they express dopaminergic markers and α-synuclein and they can be differentiated into neuronal cells using established protocols. Despite increasing evidence pointing towards a role of lipids in PD, limited knowledge is available on the lipidome of undifferentiated and differentiated SH-SY5Y cells. Using a combination of lipidomics, proteomics, morphological and electrophysiological measurements, we identified specific lipids, including sphingolipids, whose levels are affected by the differentiation of SH-SY5Y neuroblastoma cells and found that the levels of these lipids correlate with those of neuronal and dopaminergic markers. These results provide a quantitative characterisation of the changes in lipidome associated with the differentiation of SH-SY5Y cells into more neuronal and dopaminergic-like phenotype and serve as a basis for further characterisation of lipid disruptions in association with PD and its risk factors in this dopaminergic-like neuronal cell model.

Physical Exercise-Induced Activation of NRF2 and BDNF as a Promising Strategy for Ferroptosis Regulation in Parkinson's Disease

Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by the loss of dopaminergic neurons in the substantia nigra. Ferroptosis, an iron-dependent form of regulated cell death, may contribute to the progression of PD owing to an unbalanced brain redox status. Physical exercise is a complementary therapy that can modulate ferroptosis in PD by regulating the redox system through the activation of nuclear factor (erythroid-derived 2)-like 2 (NRF2) and brain-derived neurotrophic factor (BDNF) signaling. However, the precise effects of physical exercise on ferroptosis in PD remain unclear. In this review, we explored how physical exercise influences NRF2 and BDNF signaling and affects ferroptosis in PD. We further investigated relevant publications over the past two decades by searching the PubMed, Web of Science, and Google Scholar databases using keywords related to physical exercise, PD, ferroptosis, and neurotrophic factor antioxidant signaling. This review provides insights into current research gaps and demonstrates the necessity for future research to elucidate the specific mechanisms by which exercise regulates ferroptosis in PD, including the assessment of different exercise protocols and their long-term effects. Ultimately, exploring these aspects may lead to the development of improved exercise interventions for the better management of patients with PD.

Epigallocatechin-3-gallate confers protection against myocardial ischemia/reperfusion injury by inhibiting ferroptosis, apoptosis, and autophagy via modulation of 14-3-3η

Previous studies have demonstrated that the underlying mechanisms of myocardial ischemia/reperfusion injury (MIRI) are complex and involve multiple types of regulatory cell death, including ferroptosis, apoptosis, and autophagy. Thus, we aimed to identify the mechanisms underlying MIRI and validate the protective role of epigallocatechin-3-gallate (EGCG) and its related mechanisms in MIRI. An in vivo and in vitro models of MIRI were constructed. The results showed that pretreatment with EGCG could attenuate MIRI, as indicated by increased cell viability, reduced lactate dehydrogenase (LDH) activity and apoptosis, inhibited iron overload, abnormal lipid metabolism, preserved mitochondrial function, decreased infarct size, maintained cardiac function, decreased reactive oxygen species (ROS) level, and reduced TUNEL-positive cells. Additionally, EGCG pretreatment could attenuate ferroptosis, apoptosis, and autophagy induced by MIRI via upregulating 14-3-3η protein levels. Furthermore, the protective effects of EGCG could be abolished with pAd/14-3-3η-shRNA or Compound C11 (a 14-3-3η inhibitor) but not pAd/NC-shRNA. In conclusion, EGCG pretreatment attenuated ferroptosis, apoptosis, and autophagy by mediating 14-3-3η and protected cardiomyocytes against MIRI.

Mapping the Research of Ferroptosis in Parkinson's Disease from 2013 to 2023: A Scientometric Review

Methods

Related studies on PD and ferroptosis were searched in Web of Science Core Collection (WOSCC) from inception to 2023. VOSviewer, CiteSpace, RStudio, and Scimago Graphica were employed as bibliometric analysis tools to generate network maps about the collaborations between authors, countries, and institutions and to visualize the co-occurrence and trends of co-cited references and keywords.

Results

A total of 160 original articles and reviews related to PD and ferroptosis were retrieved, produced by from 958 authors from 162 institutions. Devos David was the most prolific author, with 9 articles. China and the University of Melbourne had leading positions in publication volume with 84 and 12 publications, respectively. Current hot topics focus on excavating potential new targets for treating PD based on ferroptosis by gaining insight into specific molecular mechanisms, including iron metabolism disorders, lipid peroxidation, and imbalanced antioxidant regulation. Clinical studies aimed at treating PD by targeting ferroptosis remain in their preliminary stages.

Conclusion

A continued increase was shown in the literature within the related field over the past decade. The current study suggested active collaborations among authors, countries, and institutions. Research into the pathogenesis and treatment of PD based on ferroptosis has remained a prominent topic in the field in recent years, indicating that ferroptosis-targeted therapy is a potential approach to halting the progression of PD.

Isolation and Bioactivity Evaluation of Sesquiterpenes from an Alcyonarian of the Genus Lemnalia from the Saudi Arabian Red Sea

Over the last decades, soft corals have been proven a rich source of biologically active compounds, featuring a wide range of chemical structures. Herein, we investigated the chemistry of an alcyonarian of the genus Lemnalia (Neptheidae), specimens of which were collected from the coral reefs near Al Lith, on the south-west coast of Saudi Arabia. A series of chromatographic separations led to the isolation of 31 sesquiterpenes, featuring mainly the nardosinane and neolemnane carbon skeletons, among which three (13, 14 and 28) are new natural products. The metabolites isolated in sufficient amounts were evaluated in vitro in human tumor and non-cancerous cell lines for a number of biological activities, including their cytotoxic, anti-inflammatory, anti-angiogenic, and neuroprotective activities, as well as for their effect on androgen receptor (AR)-regulated transcription. Among the tested metabolites, compound 12 showed comparable neuroprotective activity to the positive control N-acetylcysteine, albeit at a 10-fold lower concentration.

Necrosis Links Neurodegeneration and Neuroinflammation in Neurodegenerative Disease

The mechanisms of neuronal cell death in neurodegenerative disease remain incompletely understood, although recent studies have made significant advances. Apoptosis was previously considered to be the only mechanism of neuronal cell death in neurodegenerative diseases. However, recent findings have challenged this dogma, identifying new subtypes of necrotic neuronal cell death. The present review provides an updated summary of necrosis subtypes and discusses their potential roles in neurodegenerative cell death. Among numerous necrosis subtypes, including necroptosis, paraptosis, ferroptosis, and pyroptosis, transcriptional repression-induced atypical cell death (TRIAD) has been identified as a potential mechanism of neuronal cell death. TRIAD is induced by functional deficiency of TEAD-YAP and self-amplifies via the release of HMGB1. TRIAD is a feasible potential mechanism of neuronal cell death in Alzheimer's disease and other neurodegenerative diseases. In addition to induction of cell death, HMGB1 released during TRIAD activates brain inflammatory responses, which is a potential link between neurodegeneration and neuroinflammation.

COVID-19 related neurological manifestations in Parkinson's disease: has ferroptosis been a suspect?

A rising number of patient cases point to a probable link between SARS-CoV-2 infection and Parkinson's disease (PD), yet the mechanisms by which SARS-CoV-2 affects the brain and generates neuropsychiatric symptoms in COVID-19 patients remain unknown. Ferroptosis, a distinct iron-dependent non-apoptotic type of cell death characterized by lipid peroxidation and glutathione depletion, a key factor in neurological disorders. Ferroptosis may have a pathogenic role in COVID-19, according to recent findings, however its potential contributions to COVID-19-related PD have not yet been investigated. This review covers potential paths for SARS-CoV-2 infection of the brain. Among these putative processes, ferroptosis may contribute to the etiology of COVID-19-associated PD, potentially providing therapeutic methods.

Dopaminergic neuronal death via necroptosis in Parkinson's disease: A review of the literature

Parkinson's disease (PD) is a neurodegenerative disorder characterized by progressive dysfunction and loss of dopaminergic neurons of the substantia nigra pars compacta (SNc). Several pathways of programmed cell death are likely to play a role in dopaminergic neuron death, such as apoptosis, necrosis, pyroptosis and ferroptosis, as well as cell death associated with proteasomal and mitochondrial dysfunction. A better understanding of the molecular mechanisms underlying dopaminergic neuron death could inform the design of drugs that promote neuron survival. Necroptosis is a recently characterized regulated cell death mechanism that exhibits morphological features common to both apoptosis and necrosis. It requires activation of an intracellular pathway involving receptor-interacting protein 1 kinase (RIP1 kinase, RIPK1), receptor-interacting protein 3 kinase (RIP3 kinase, RIPK3) and mixed lineage kinase domain-like pseudokinase (MLKL). The potential involvement of this programmed cell death pathway in the pathogenesis of PD has been studied by analysing biomarkers for necroptosis, such as the levels and oligomerization of phosphorylated RIPK3 (pRIPK3) and phosphorylated MLKL (pMLKL), in several PD preclinical models and in PD human tissue. Although there is evidence that other types of cell death also have a role in DA neuron death, most studies support the hypothesis that this cell death mechanism is activated in PD tissues. Drugs that prevent or reduce necroptosis may provide neuroprotection for PD. In this review, we summarize the findings from these studies. We also discuss how manipulating necroptosis might open a novel therapeutic approach to reduce neuronal degeneration in PD.

Role of ferroptosis pathways in neuroinflammation and neurological disorders: From pathogenesis to treatment

Ferroptosis is a newly discovered non-apoptotic and iron-dependent type of cell death. Ferroptosis mainly takes place owing to the imbalance of anti-oxidation and oxidation in the body. It is regulated via a number of factors and pathways both inside and outside the cell. Ferroptosis is closely linked with brain and various neurological disorders (NDs). In the human body, the brain contains the highest levels of polyunsaturated fatty acids, which are known as lipid peroxide precursors. In addition, there is also a connection of glutathione depletion and lipid peroxidation with NDs. There is growing evidence regarding the possible link between neuroinflammation and multiple NDs, such as Alzheimer's disease, amyotrophic lateral sclerosis, Parkinson's disease, Huntington's disease, and stroke. Recent studies have demonstrated that disruptions of lipid reactive oxygen species (ROS), glutamate excitatory toxicity, iron homeostasis, and various other manifestations linked with ferroptosis can be identified in various neuroinflammation-mediated NDs. It has also been reported that damage-associated molecular pattern molecules including ROS are generated during the events of ferroptosis and can cause glial activation via activating neuroimmune pathways, which subsequently leads to the generation of various inflammatory factors that play a role in various NDs. This review summarizes the regulation pathways of ferroptosis, the link between ferroptosis as well as inflammation in NDs, and the potential of a range of therapeutic agents that can be used to target ferroptosis and inflammation in the treatment of neurological disorders.

Heat Shock Protein 90 in Parkinson's Disease: Profile of a Serial Killer

Parkinson's disease (PD) is the second most common neurodegenerative disease, characterized by abnormal α-synuclein misfolding and aggregation, mitochondrial dysfunction, oxidative stress, as well as progressive death of dopaminergic neurons in the substantia nigra. Molecular chaperones play a role in stabilizing proteins and helping them achieve their proper structure. Previous studies have shown that overexpression of heat shock protein 90 (HSP90) can lead to the death of dopaminergic neurons associated with PD. Inhibiting HSP90 is considered a potential treatment approach for neurodegenerative disorders, as it may reduce protein aggregation and related toxicity, as well as suppress various forms of regulated cell death (RCD). This review provides an overview of HSP90 and its role in PD, focusing on its modulation of proteostasis and quality control of LRRK2. The review also explores the effects of HSP90 on different types of RCD, such as apoptosis, chaperone-mediated autophagy (CMA), necroptosis, and ferroptosis. Additionally, it discusses HSP90 inhibitors that have been tested in PD models. We will highlight the under-investigated neuroprotective effects of HSP90 inhibition, including modulation of oxidative stress, mitochondrial dysfunction, PINK/PARKIN, heat shock factor 1 (HSF1), histone deacetylase 6 (HDAC6), and the PHD2-HSP90 complex-mediated mitochondrial stress pathway. By examining previous literature, this review uncovers overlooked neuroprotective mechanisms and emphasizes the need for further research on HSP90 inhibitors as potential therapeutic strategies for PD. Finally, the review discusses the potential limitations and possibilities of using HSP90 inhibitors in PD therapy.

Cartilage Destruction by Hemophilic Arthropathy Can Be Prevented by Inhibition of the Ferroptosis Pathway in Human Chondrocytes

(1) Background: Around 50% of hemophilia patients develop severe arthropathy, with even subclinical hemorrhage in childhood potentially leading to intra-articular iron deposition, synovia proliferation, neoangiogenesis, and eventual damage to articular cartilage and subchondral bone. Treatments typically include coagulation factor substitution, radiosynoviorthesis, and joint replacement for advanced cases. This study aims to elucidate programmed cell death mechanisms in hemophilic arthropathy (HA) to identify novel treatments. (2) Methods: Human chondrocytes were exposed to lysed/non-lysed erythrocytes, ferroptosis inducer ML-162, cytokines (IL-1ß, TNFα), and ferric citrate, then assessed for metabolic activity, DNA content, and cell death using Alamar Blue, cyQUANT, and Sytox assays. Three-dimensional spheroids served as a cartilage model to study the effects of erythrocytes and ML-162. (3) Results: Erythrocytes caused significant cell death in 2D cultures (p < 0.001) and damaged 3D chondrocyte spheroids. Iron citrate and erythrocytes reduced chondrocyte DNA content (p < 0.001). The ferroptosis pathway was implicated in cell death, with no effects from apoptosis and necroptosis inhibitors. (4) Conclusions: This study offers insights into HA's cell death pathway, suggesting ferroptosis inhibitors as potential therapies. Further studies are needed to evaluate their efficacy against the chronic effects of HA.

Ferroptosis: Emerging Role in Diseases and Potential Implication of Bioactive Compounds

Ferroptosis is a form of cell death that is distinguished from other types of death for its peculiar characteristics of death regulated by iron accumulation, increase in ROS, and lipid peroxidation. In the past few years, experimental evidence has correlated ferroptosis with various pathological processes including neurodegenerative and cardiovascular diseases. Ferroptosis also is involved in several types of cancer because it has been shown to induce tumor cell death. In particular, the pharmacological induction of ferroptosis, contributing to the inhibition of the proliferative process, provides new ideas for the pharmacological treatment of cancer. Emerging evidence suggests that certain mechanisms including the Xc- system, GPx4, and iron chelators play a key role in the regulation of ferroptosis and can be used to block the progression of many diseases. This review summarizes current knowledge on the mechanism of ferroptosis and the latest advances in its multiple regulatory pathways, underlining ferroptosis' involvement in the diseases. Finally, we focused on several types of ferroptosis inducers and inhibitors, evaluating their impact on the cell death principal targets to provide new perspectives in the treatment of the diseases and a potential pharmacological development of new clinical therapies.

Negative modulation of mitochondrial calcium uniporter complex protects neurons against ferroptosis

Ferroptosis is an iron- and reactive oxygen species (ROS)-dependent form of regulated cell death, that has been implicated in Alzheimer's disease and Parkinson's disease. Inhibition of cystine/glutamate antiporter could lead to mitochondrial fragmentation, mitochondrial calcium ([Ca2+]m) overload, increased mitochondrial ROS production, disruption of the mitochondrial membrane potential (ΔΨm), and ferroptotic cell death. The observation that mitochondrial dysfunction is a characteristic of ferroptosis makes preservation of mitochondrial function a potential therapeutic option for diseases associated with ferroptotic cell death. Mitochondrial calcium levels are controlled via the mitochondrial calcium uniporter (MCU), the main entry point of Ca2+ into the mitochondrial matrix. Therefore, we have hypothesized that negative modulation of MCU complex may confer protection against ferroptosis. Here we evaluated whether the known negative modulators of MCU complex, ruthenium red (RR), its derivative Ru265, mitoxantrone (MX), and MCU-i4 can prevent mitochondrial dysfunction and ferroptotic cell death. These compounds mediated protection in HT22 cells, in human dopaminergic neurons and mouse primary cortical neurons against ferroptotic cell death. Depletion of MICU1, a [Ca2+]m gatekeeper, demonstrated that MICU is protective against ferroptosis. Taken together, our results reveal that negative modulation of MCU complex represents a therapeutic option to prevent degenerative conditions, in which ferroptosis is central to the progression of these pathologies.

Ferroptosis-Related Immune Genes in Hematological Diagnosis of Parkinson's Diseases

Emerging evidence suggested that ferroptosis and immune activation, as well as their interactions, played a crucial role in the occurrence and progression of Parkinson's disease (PD). However, whether this interaction could serve as the basis for a hematological diagnosis of PD remained poorly understood. This study aimed to construct a novel hematological model for PD diagnosis based on the ferroptosis-related immune genes. The brain imaging of PD patients was obtained from the Affiliated Hospital of Nantong University. We used least absolute shrinkage and selection operator (LASSO) to identify the optimal signature ferroptosis-related immune genes based on six gene expression profile datasets of substantia nigra (SN) and peripheral blood of PD patients. Then we used the support vector machine (SVM) classifier to construct the hematological diagnostic model named Ferr.Sig for PD. Gene set enrichment analysis was utilized to execute gene functional annotation. The brain imaging and functional annotation analysis revealed prominent iron deposition and immune activation in the SN region of PD patients. We identified a total of 17 signature ferroptosis-related immune genes using LASSO method and imported them to SVM classifier. The Ferr.Sig model exhibited a high diagnostic accuracy, and its area under the curve (AUC) for distinguishing PD patients from healthy controls in the training and internal validation cohort reached 0.856 and 0.704, respectively. We also used the Ferr.Sig into other external validation cohorts, and a comparable AUC with the internal cohort was obtained, with the AUC of 0.727 in Scherzer's cohort, 0.745 in Roncagli's cohort, and 0.778 in Meiklejohn's cohort. Furthermore, the diagnostic performance of Ferr.Sig was not interfered by the other neurodegenerative diseases. This study revealed the value of ferroptosis-related immune genes in PD diagnosis, which may provide a novel direction and strategy for the development of novel biomarkers with less invasiveness, low cost, and high accuracy for PD screening and diagnosis.

Pathogenic mechanisms and potential therapeutic targets for Parkinson disease revealed by bioinformatic analysis of necroptosis and immune cell infiltration

Parkinson disease (PD) is an age-dependent neurodegenerative disease with very high prevalence by age 80 years. Necroptosis is a newly identified form of programmed cell death implicated in neurodegenerative diseases, but has not yet been conclusively associated with PD. This study examined the contributions of necroptosis to PD using bioinformatics analysis. Datasets GSE26927, GSE49036, and GSE54536 from the gene expression omnibus database were analyzed for differentially expressed genes (DEGs). These DEGs were then subjected to gene ontology and Kyoto encyclopedia of genes and genomes (KEGG) pathway enrichment analysis to identify associated functions and signaling mechanisms. Necroptosis-related differentially expressed genes (NRDEGs) were then identified by the overlap of DEGs and the necroptosis gene set hsa04217. The STRING database and Cytoscape software were then used to build and visualize a protein-protein interaction network and identify hubs and key functional modules among NRDEGs. In addition, immune cell type abundance was analyzed based on DEGs using ImmuCellAI. The identified DEGs, KEGG pathway enrichment terms, and protein-protein interaction network structures of NRDEGs were validated using an independent dataset (GSE54536). The necroptosis pathway was significantly enriched and activated in PD samples. Thirteen NRDEGs were identified in the GSE26927 and GSE49036 datasets, including receptor interacting serine/threonine kinase 1, CASP8 and FADD like apoptosis regulator, TNFRSF1A associated via death domain, and interleukin 1 beta, of which 6 were validated in the GSE54536 dataset. According to gene ontology and KEGG analyses, these NRDEGs are involved in necroptosis-related processes, apoptosis, B cell receptor signaling pathways, and NOD-like receptor signaling pathways. Analysis of DEGs also revealed significant increases in CD8 + T cell and Tex cell infiltration and significant decreases in B cell and T gamma delta cell infiltration within the PD brain. Necroptosis pathways are active in PD and associated with immune cell infiltration. The factors controlling necroptotic signaling and immune infiltration identified in this study may be valuable diagnostic markers and therapeutic targets for PD.

The Role of Cellular Defense Systems of Ferroptosis in Parkinson's Disease and Alzheimer's Disease

Parkinson's disease (PD) and Alzheimer's disease (AD) are the most common rapidly developing neurodegenerative diseases that lead to serious health and socio-economic consequences. Ferroptosis is a non-apoptotic form of cell death; there is growing evidence to support the notion that ferroptosis is involved in a variety of pathophysiological contexts, and there is increasing interest in the role of ferroptosis in PD and AD. Simultaneously, cells may have evolved four defense systems to counteract the toxic effects of ferroptosis occasioned by lipid peroxidation. This review, which focuses on the analysis of ferroptosis in the PD and AD context, outlines four cellular defense systems against ferroptosis and how each of them is involved in PD and AD.

Heme oxygenase-1 determines the cell fate of ferroptotic death of alveolar macrophages in COPD

Background

Despite an increasing understanding of chronic obstructive pulmonary disease (COPD) pathogenesis, the mechanisms of diverse cell populations in the human lung remain unknown. Using single-cell RNA sequencing (scRNA-Seq), we can reveal changes within individual cell populations in COPD that are important for disease pathogenesis and characteristics.

Methods

We performed scRNA-Seq on lung tissue obtained from donors with non-COPD and mild-to-moderate COPD to identify disease-related genes within different cell types. We testified the findings using qRT-PCR, immunohistochemistry, immunofluorescence and Western blotting from 25 additional subjects and RAW 264.7 macrophages. Targeting ferroptosis with the ferroptosis inhibitor ferrostatin-1, iron chelator deferoxamine or HO-1 inhibitor zinc protoporphyrin was administered in the experimental cigarette smoke COPD mouse model.

Results

We identified two populations of alveolar macrophages (AMs) in the human lung that were dysregulated in COPD patients. We discovered that M2-like AMs modulate susceptibility to ferroptosis by disrupting lipid and iron homeostasis both in vivo and in vitro. The discrepancy in sensitivity to ferroptosis can be determined and regulated by HO-1. In contrast, M1-like AMs showed the ability to attenuate oxidative stress and exert resistance to ferroptosis. In addition, the expression of genes within M2-like AMs is also involved in defects in phagocytosis and lysosome distortion. This ferroptotic phenotype was ameliorated by antiferroptotic compounds, iron chelators and HO-1 inhibitors. During COPD, the accumulation of lipid peroxidation drives ferroptosis-sensitive M2-like AMs, while M1-like AMs show characteristics of ferroptosis resistance. Ferroptotic M2 AMs lose their anti-inflammatory and repair functions but provoke inflammatory responses, resulting in consistent inflammation and tissue damage in the presence of M1 AMs in COPD.

Conclusion

Appropriate interventions in ferroptosis can reduce the occurrence of infections and acute onset, and delay the COPD process.

Protective effects of cell permeable Tat-PIM2 protein on oxidative stress induced dopaminergic neuronal cell death

Background

Oxidative stress is considered as one of the main causes of Parkinson's disease (PD), however the exact etiology of PD is still unknown. Although it is known that Proviral Integration Moloney-2 (PIM2) promotes cell survival by its ability to inhibit formation of reactive oxygen species (ROS) in the brain, the precise functional role of PIM2 in PD has not been fully studied yet.

Objective

We investigated the protective effect of PIM2 against apoptosis of dopaminergic neuronal cells caused by oxidative stress-induced ROS damage by using the cell permeable Tat-PIM2 fusion protein in vitro and in vivo.

Methods

Transduction of Tat-PIM2 into SH-SY5Y cells and apoptotic signaling pathways were determined by Western blot analysis. Intracellular ROS production and DNA damage was confirmed by DCF-DA and TUNEL staining. Cell viability was determined by MTT assay. PD animal model was induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and protective effects were examined using immunohistochemistry.

Results

Transduced Tat-PIM2 inhibited the apoptotic caspase signaling and reduced the production of ROS induced by 1-methyl-4-phenylpyridinium (MPP⁺) in SH-SY5Y cells. Furthermore, we confirmed that Tat-PIM2 transduced into the substantia nigra (SN) region through the blood-brain barrier and this protein protected the Tyrosine hydroxylase-positive cells by observation of immunohistostaining. Tat-PIM2 also regulated antioxidant biomolecules such as SOD1, catalase, 4-HNE, and 8-OHdG which reduce the formation of ROS in the MPTP-induced PD mouse model.

Conclusion

These results indicated that Tat-PIM2 markedly inhibited the loss of dopaminergic neurons by reducing ROS damage, suggesting that Tat-PIM2 might be a suitable therapeutic agent for PD.

HRD1 functions as a tumor suppressor in ovarian cancer by facilitating ubiquitination-dependent SLC7A11 degradation

The E3 ubiquitin ligase 3-hydroxy-3-methylglutaryl reductase degradation (HRD1) was found to be a tumor suppressor in diverse types of cancers; we aimed to explore its expression pattern and biological function in ovarian cancer (OC). HRD1 expression in OC tumor tissues was detected using quantitative real-time polymerase chain reaction (qRT-PCR) and immunohistochemistry (IHC). The overexpression plasmid of HRD1 was transfected into OC cells. Cell proliferation, colony formation, and apoptosis were analyzed using bromodeoxy uridineassay, colony formation assay, and flow cytometry, respectively. OC mice models were established to explore the effect of HRD1 on OC in vivo. Ferroptosis was evaluated by malondialdehyde, reactive oxygen species, and intracellular ferrous iron. Expressions offerroptosis-related factors were examined using qRT-PCR and western blot. Erastin and Fer-1 were, respectively, employed to promote or inhibit ferroptosis in OC cells. Online bioinformatics tool and co-immunoprecipitation assay were performed to predict and verify the interactive genes of HRD1 in OC cells, respectively. Gain-of-function studies were carried out to determine the roles of HRD1 in cell proliferation, apoptosis, and ferroptosis in vitro. HRD1 was under-expressed in OC tumor tissues. The overexpression of HRD1 inhibited OC cell proliferation and colony formation in vitro and suppressed OC tumor growth in vivo. The overexpression of HRD1 promoted cell apoptosis and ferroptosis in OC cell lines. HRD1 interacted with the solute carrier family 7 member 11 (SLC7A11) in OC cells, and HRD1 regulated the stability and ubiquitination in OC. SLC7A11 overexpression recovered the effect of HRD1 overexpression in OC cell lines. HRD1 inhibited tumor formation and promoted ferroptosis in OC through enhancing SLC7A11 degradation.

Research Models to Study Ferroptosis's Impact in Neurodegenerative Diseases

Ferroptosis is a type of regulated cell death promoted by the appearance of oxidative perturbations in the intracellular microenvironment constitutively controlled by glutathione peroxidase 4 (GPX4). It is characterized by increased production of reactive oxygen species, intracellular iron accumulation, lipid peroxidation, inhibition of system Xc-, glutathione depletion, and decreased GPX4 activity. Several pieces of evidence support the involvement of ferroptosis in distinct neurodegenerative diseases. In vitro and in vivo models allow a reliable transition to clinical studies. Several in vitro models, including differentiated SH-SY5Y and PC12 cells, among others, have been used to investigate the pathophysiological mechanisms of distinct neurodegenerative diseases, including ferroptosis. In addition, they can be useful in the development of potential ferroptosis inhibitors that can be used as disease-modifying drugs for the treatment of such diseases. On the other hand, in vivo models based on the manipulation of rodents and invertebrate animals, such as Drosophila melanogaster, Caenorhabditis elegans, and zebrafish, have been increasingly used for research in neurodegeneration. This work provides an up-to-date review of the main in vitro and in vivo models that can be used to evaluate ferroptosis in the most prevalent neurodegenerative diseases, and to explore potential new drug targets and novel drug candidates for effective disease-modifying therapies.

Scavenger receptor BI attenuates oxidized phospholipid-induced pulmonary inflammation

Damage associated molecular patterns (DAMPs) are molecules released from dead/dying cells following toxicant and/or environmental exposures that activate the immune response through binding of pattern recognition receptors (PRRs). Excessive production of DAMPs or failed clearance leads to chronic inflammation and delayed inflammation resolution. One category of DAMPs are oxidized phospholipids (oxPLs) produced upon exposure to high levels of oxidative stress, such as following ozone (O3) induced inflammation. OxPLs are bound by multiple classes of PRRs that include scavenger receptors (SRs) such as SR class B-1 (SR-BI) and toll-like receptors (TLRs). Interactions between oxPLs and PRRs appear to regulate inflammation; however, the role of SR-BI in oxPL-induced lung inflammation has not been defined. Therefore, we hypothesize that SR-BI is critical in protecting the lung from oxPL-induced pulmonary inflammation/injury. To test this hypothesis, C57BL/6J (WT) female mice were dosed with oxidized 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphatidylcholine (oxPAPC) by oropharyngeal aspiration which increased pulmonary SR-BI expression. Following oxPAPC exposure, SR-BI deficient (SR-BI-/-) mice exhibited increased lung pathology and inflammatory cytokine/chemokine production. Lipidomic analysis revealed that SR-BI-/- mice had an altered pulmonary lipidome prior to and following oxPAPC exposure, which correlated with increased oxidized phosphatidylcholines (PCs). Finally, we characterized TLR4-mediated activation of NF-κB following oxPAPC exposure and discovered that SR-BI-/- mice had increased TLR4 mRNA expression in lung tissue and macrophages, increased nuclear p65, and decreased cytoplasmic IκBα. Overall, we conclude that SR-BI is required for limiting oxPAPC-induced lung pathology by maintaining lipid homeostasis, reducing oxidized PCs, and attenuating TLR4-NF-κB activation, thereby preventing excessive and persistent inflammation.

δ-Opioid Receptor Activation Inhibits Ferroptosis by Activating the Nrf2 Pathway in MPTP-Induced Parkinson Disease Models

Introduction

Recent studies suggest the involvement of ferroptosis in the pathogenesis of Parkinson disease (PD). δ-Opioid receptors (DORs) have neuroprotective effects in PD. It is not known whether the neuroprotective effects of DORs in PD are attributable to the inhibition of ferroptosis. Therefore, we aimed to investigate the role of DORs in ferroptosis in MPTP-induced PD models.

Methods

To identify the influence of DORs on ferroptosis in MPTP-induced PD models, we measured the malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE) levels, analyzed the levels of ferroptosis-related proteins (GXP4 and SLC7a11) and Nrf2 expression by using western blotting, and assessed mitochondrial dysfunction by using JC-1 staining and transmission electron microscopy.

Results

DOR activation reduced the 4-HNE and MDA levels, increased the GXP4 and SLC7a11 levels, and ameliorated mitochondrial dysfunction in MPTP-induced PD models. These neuroprotective effects of DORs could be blocked by Nrf2-siRNA. Thus, the effects of DORs on ferroptosis in PD models were partially controlled by Nrf2, which regulated GXP4 and SLC7a11 synthesis.

Conclusion

DORs exert neuroprotective effects in PD models by inhibiting ferroptosis partially via activating the Nrf2 pathway.

An in vitro evaluation of the antioxidant activities of necroptosis and apoptosis inhibitors: the potential of necrostatin-1 and necrostatin-1i to have radical scavenging activities

BACKGROUND

Necroptosis inhibitors, including necrostatin-1 (Nec-1), are attracting attention as potential therapeutic agents against various diseases, such as acute lung injury, chronic obstructive pulmonary disease, acute kidney injury, nonalcoholic fatty liver, and neurodegenerative disease, where necroptosis is thought to act as a contributing factor. Nec-1 suppresses necroptosis by inhibiting receptor-interacting protein (RIP) 1 kinase and can also reduce reactive oxygen species (ROS) production; however, the underlying molecular mechanisms mediating ROS reduction remain unclear.

METHODS

The antioxidant effects of necroptosis inhibitors, including Nec-1 and apoptosis inhibitors, were quantified by performing a 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay. Nec-1-related compounds were subsequently assayed for cupric ion-reducing capacity and superoxide dismutase (SOD)-like activity.

RESULTS

Considering all examined apoptosis and necroptosis inhibitors, Nec-1and Nec-1i exhibited antioxidant activity in DPPH radical scavenging assay. In the cupric ion-reducing capacity assay, Nec-1i showed stronger antioxidant capacity than Nec-1. In the SOD-like activity assay, both Nec-1 and Nec-1i were found to have stronger antioxidant capacity than ascorbic acid (IC₅₀ = 4.6 ± 0.040 and 61 ± 0.54 µM, respectively).

CONCLUSION

These results suggest that Nec-1 and Nec-1i may exhibit direct radical scavenging ability against superoxide anions, independent of RIP1 inhibition.

Association between Beta Oscillations from Subthalamic Nucleus and Quantitative Susceptibility Mapping in Deep Gray Matter Structures in Parkinson's Disease

This study aimed to investigate the association between beta oscillations and brain iron deposition. Beta oscillations were filtered from the microelectrode recordings of local field potentials (LFP) in the subthalamic nucleus (STN), and the ratio of the power spectral density of beta oscillations (PSDXb) to that of the LFP signals was calculated. Iron deposition in the deep gray matter (DGM) structures was indirectly assessed using quantitative susceptibility mapping (QSM). The Unified Parkinson's Disease Rating Scale (UPDRS), part III, was used to assess the severity of symptoms. Spearman correlation coefficients were applied to assess the associations of PSDXb with QSM values in the DGM structures and the severity of symptoms. PSDXb showed a significant positive correlation with the average QSM values in DGM structures, including caudate and substantia nigra (SN) (p = 0.008 and 0.044). Similarly, the PSDXb showed significant negative correlations with the severity of symptoms, including axial symptoms and the gait in the medicine-off state (p = 0.006 for both). The abnormal iron metabolism in the SN and striatum pathways may be one of the underlying mechanisms for the occurrence of abnormal beta oscillations in the STN, and beta oscillations may serve as important pathophysiological biomarkers of PD.

Effects of Apamin on MPP+-Induced Calcium Overload and Neurotoxicity by Targeting CaMKII/ERK/p65/STAT3 Signaling Pathways in Dopaminergic Neuronal Cells

Parkinson's disease (PD), a neurodegenerative disorder, is characterized by the loss of dopaminergic (DA) neurons. The pathogenesis of PD is associated with several factors including oxidative stress, inflammation, and mitochondrial dysfunction. Ca²⁺ signaling plays a vital role in neuronal signaling and altered Ca²⁺ homeostasis has been implicated in many neuronal diseases including PD. Recently, we reported that apamin (APM), a selective antagonist of the small-conductivity Ca²⁺-activated K⁺ (SK) channel, suppresses neuroinflammatory response. However, the mechanism(s) underlying the vulnerability of DA neurons were not fully understood. In this study, we investigated whether APM affected 1-methyl-4-phenyl pyridinium (MPP⁺)-mediated neurotoxicity in SH-SY5Y cells and rat embryo primary mesencephalic neurons. We found that APM decreased Ca²⁺ overload arising from MPP⁺-induced neurotoxicity response through downregulating the level of CaMKII, phosphorylation of ERK, and translocation of nuclear factor NFκB/signal transducer and activator of transcription (STAT)3. Furthermore, we showed that the correlation of MPP⁺-mediated Ca²⁺ overload and ERK/NFκB/STAT3 in the neurotoxicity responses, and dopaminergic neuronal cells loss, was verified through inhibitors. Our findings showed that APM might prevent loss of DA neurons via inhibition of Ca²⁺-overload-mediated signaling pathway and provide insights regarding the potential use of APM in treating neurodegenerative diseases.

Pathogenesis of α-Synuclein in Parkinson's Disease: From a Neuron-Glia Crosstalk Perspective

Parkinson's disease (PD) is a progressive neurodegenerative disorder. The classical behavioral defects of PD patients involve motor symptoms such as bradykinesia, tremor, and rigidity, as well as non-motor symptoms such as anosmia, depression, and cognitive impairment. Pathologically, the progressive loss of dopaminergic (DA) neurons in the substantia nigra (SN) and the accumulation of α-synuclein (α-syn)-composed Lewy bodies (LBs) and Lewy neurites (LNs) are key hallmarks. Glia are more than mere bystanders that simply support neurons, they actively contribute to almost every aspect of neuronal development and function; glial dysregulation has been implicated in a series of neurodegenerative diseases including PD. Importantly, amounting evidence has added glial activation and neuroinflammation as new features of PD onset and progression. Thus, gaining a better understanding of glia, especially neuron-glia crosstalk, will not only provide insight into brain physiology events but also advance our knowledge of PD pathologies. This review addresses the current understanding of α-syn pathogenesis in PD, with a focus on neuron-glia crosstalk. Particularly, the transmission of α-syn between neurons and glia, α-syn-induced glial activation, and feedbacks of glial activation on DA neuron degeneration are thoroughly discussed. In addition, α-syn aggregation, iron deposition, and glial activation in regulating DA neuron ferroptosis in PD are covered. Lastly, we summarize the preclinical and clinical therapies, especially targeting glia, in PD treatments.

Neuroprotective Effects of gH625-lipoPACAP in an In Vitro Fluid Dynamic Model of Parkinson’s Disease

Parkinson’s disease (PD) is an aggressive and devastating age-related disorder. Although the causes are still unclear, several factors, including genetic and environmental, are involved. Except for symptomatic drugs, there are not, to date, any real cures for PD. For this purpose, it is necessary develop a model to better study this disease. Neuroblastoma cell line, SH-SY5Y, differentiated with retinoic acid represents a good in vitro model to explore PD, since it maintains growth cells to differentiated neurons. In the present study, SH-SY5Y cells were treated with 1-methyl-4-phenylpyridinium (MPP⁺), a neurotoxin that induces Parkinsonism, and the neuroprotective effects of pituitary adenylate cyclase-activating polypeptide (PACAP), delivered by functionalized liposomes in a blood–brain barrier fluid dynamic model, were evaluated. We demonstrated PACAP neuroprotective effects when delivered by gH625-liposome on MPP⁺-damaged SH-SY5Y spheroids.

Potential application of traditional Chinese medicine in cerebral ischemia—Focusing on ferroptosis

Traditional Chinese medicine (TCM) has attracted a great deal of attention in the treatment of cerebral ischemia is credited with the remarkable neuroprotective effects. However, the imperfect functional mechanism of TCM is a major obstacle to their application. Many studies have been conducted to illustrate the pathophysiology of post-ischemic cerebral ischemia by elucidating the neuronal cell death pathway. Meanwhile, a new type of cell death, ferroptosis, is gradually being recognized in various diseases and is becoming a new pathway of therapeutic intervention strategy to solve many health problems. Especially since ferroptosis has been found to be closely involved into the pathogenesis of cerebral ischemia, it has been considered as a key target in the treatment of cerebral ischemia. Therefore, this paper reviews the latest research findings about the treatment of cerebral ischemia with TCM focused on ferroptosis as a target. Also, in order to explores the possibility of a new approach to treat cerebral ischemia with TCM, we discusses the correlation between ferroptosis and other cell death pathways such as apoptosis and autophagy, which would provide references for the following researches.

Artemisia Leaf Extract protects against neuron toxicity by TRPML1 activation and promoting autophagy/mitophagy clearance in both in vitro and in vivo models of MPP+/MPTP-induced Parkinson's disease

BACKGROUND

Parkinson's disease (PD) is a neurodegenerative disorder involving the degeneration of dopaminergic neurons in the substantia nigra pars compacta (SNpc). Cellular clearance mechanisms, including the autophagy-lysosome pathway, are commonly affected in the pathogenesis of PD. The lysosomal Ca²⁺ channel mucolipin TRP channel 1 (TRPML1) is one of the most important proteins involved in the regulation of autophagy. Artemisia argyi Lev. et Vant., is a traditional Chinese herb, that has diverse therapeutic properties and is used to treat patients with skin diseases and oral ulcers. However, the neuroprotective effects of A. argyi are not explored yet.

HYPOTHESIS

This study aims is to investigate the neuroprotective effects of A. argyi in promoting the TRPML1-mediated autophagy/mitophagy-enhancing effect METHODS: In this study, we used 1-methyl-4-phenyl-pyridinium (MPP+)-induced PD model established in an SH-SY5Y human neuroblastoma cell line as well as in a 1-methyl-4-phenyl-1,2,3,6-tetrahydro-pyridine (MPTP)-induced PD model in C57BL/6 J mice. MTT assay was conducted to measure the cell viability and further MitoSoX and DCFDA assay were used to measure the ROS. Western blot analysis was used to access levels of TRPML1, p-DRP1 (ser616), p-AKT, PI3K, and β-catenin, Additionally, IF and IHC analysis to investigate the expression of TRPML1, LC3B, β-catenin, TH+, α-synuclein. Mitotracker stain was used to check mitophagy levels and a lysosomal intracellular activity kit was used to measure the lysosomal dysfunction. Behavioral studies were conducted by rotarod and grip strength experiments to check motor functions.

RESULTS

In our in vitro study, A. argyi rescued the MPP+-induced loss of cell viability and reduced the accumulation of mitochondrial and total reactive oxygen species (ROS). Subsequently, it increased the expression of TRPML1 protein, thereby inducing autophagy, which facilitated the clearance of toxic accumulation of α-synuclein. Furthermore, A. argyi played a neuroprotective role by activating the PI3K/AKT/β-catenin cell survival pathway. MPP+-mediated mitochondrial damage was overcome by upregulation of mitophagy and downregulation of the mitochondrial fission regulator p-DRP1 (ser616) in SH-SY5Y cells. In the in vivo study, A. argyi ameliorated impaired motor function and rescued TH+ neurons in the SNpc region. Similar to the results of the in vitro study, TRPML1, LC3B, and β-catenin expression was enhanced in the SNpc region in the A. argyi-treated mice brain.

CONCLUSION

Thus, our results first demonstrate that A. argyi can exert neuroprotective effects by stimulating TRPML1 and rescuing neuronal cells by boosting autophagy/mitophagy and upregulating a survival pathway, suggesting that A. argyi can further be exploited to slow the progression of PD.

Ferroptosis: A Novel Therapeutic Direction of Spinal Cord Injury

An injury to the spinal cord results in a crucial central nervous system event that further causes irreversible impairment or loss of motor, autonomic, and sensory functions. A progressive pathophysiological cascade following spinal cord injury (SCI) includes ischemia/reperfusion injury, oxidative stress, proapoptotic signaling, peripheral inflammatory cell infiltration, and glutamate-mediated excitotoxicity, and regulated cell death. These complex pathological and physiological changes continue to cause cell injury over the long-term and severely limit the efficacy of clinical treatment strategies in restoring the injured nervous system. Ferroptosis is a nonapoptotic, iron-regulated kind of cell death that has recently been discovered. It is distinguished by iron overload-induced toxic lipid peroxidation associated with mitochondrial morphological changes during the cell death process. For example, after SCI, iron overload activates the reactive oxygen species generation, dysregulation of glutathione/glutathione peroxidase 4 (GSH/GPX4) metabolism, and accumulation of lipid peroxides, which cause lipid membrane deterioration and ferroptosis. Conversely, knockout or differential expression of key genes and application of lipid peroxidation inhibitors and iron chelators (e.g., deferoxamine) (e.g., SRS-16-86) can block ferroptosis and promote neuronal repair for functional recovery after SCI. Although the findings of numerous investigations have been confirmed the importance of ferroptosis in several human neurologic sicknesses and its potential in SCI, the mechanism of ferroptosis and its application in SCI has not been elucidated. This review highlights current ferroptosis research and its impact on SCI, as well as the key molecular mechanism of ferroptosis in promoting the recovery from SCI. Understanding ferroptosis' process and function in SCI could provide useful insight into the treatment and avoidance of such a destructive injury.

Nigratine as dual inhibitor of necroptosis and ferroptosis regulated cell death

Nigratine (also known as 6E11), a flavanone derivative of a plant natural product, was characterized as highly specific non-ATP competitive inhibitor of RIPK1 kinase, one of the key components of necroptotic cell death signaling. We show here that nigratine inhibited both necroptosis (induced by Tumor Necrosis Factor-α) and ferroptosis (induced by the small molecules glutamate, erastin, RSL3 or cumene hydroperoxide) with EC50 in the µM range. Taken together, our data showed that nigratine is a dual inhibitor of necroptosis and ferroptosis cell death pathways. These findings open potential new therapeutic avenues for treating complex necrosis-related diseases.

Potential Role of APEX1 During Ferroptosis

Ferroptosis is a recently discovered category of programmed cell death. It is much different from other types of cell death such as apoptosis, necrosis and autophagy. The main pathological feature of ferroptosis is the accumulation of iron-dependent lipid peroxidation. The typical changes in the morphological features of ferroptosis include cell volume shrinkage and increased mitochondrial membrane area. The mechanisms of ferroptosis may be mainly related to lipid peroxidation accumulation, imbalance in amino acid antioxidant system, and disturbance of iron metabolism. Besides, hypoxia-inducible factor (HIF), nuclear factor-E2-related factor 2 (Nrf2), and p53 pathway have been demonstrated to be involved in ferroptosis. At present, the molecular mechanisms of ferroptosis pathway are still unmapped. In this review, an outlook has been put forward about the crucial role of apurinic/apyrimidinic endodeoxyribonuclease 1 (APEX1) in the regulation of ferroptosis. APEX1 plays an important role in the regulation of intracellular redox balance and can be used as a potential inhibitor of ferroptotic cell death. Bioinformatics analysis indicated that the mRNA level of APEX1 is decreased in cases of ferroptosis triggered by erastin. Besides, it was found that there was a significant correlation between APEX1 and genes in the ferroptosis pathway. We have discussed the possibility to employ APEX1 inducers or inhibitors in the regulation of ferroptosis as a new strategy for the treatment of various human diseases.

Co-exposure of polystyrene microplastics and iron aggravates cognitive decline in aging mice via ferroptosis induction

The objective of this study was to investigate the effects of co-exposure of iron and microplastics (MPs) on the cognitive function of aged humans and animals. It was already known that individual iron or MPs exposure can initiate potential neurotoxicity. However, the combined effect of MPs and iron remained to be elucidated. In this study, the toxicity of iron, MPs, co-treatment of MPs & iron, and the underlying mechanisms were evaluated in vivo. Our findings suggest that 5 µm MPs could enter the aging mice brain and accumulate in cortex and hippocampus. In addition, MPs and iron have a good binding ability, therefore, co-exposure of MPs & iron cause significant iron overload and cognitive deficits as compared to control and individual treatments of iron and MPs. Moreover, the lipid peroxidation and inflammation, which are involved in ferroptosis, get significantly elevated by co-exposure of iron and MPs. Taken together, our results provide compelling evidence that co-exposure of iron and MPs could aggravate the cognitive impairment via disturbing brain iron homeostasis and inducing ferroptosis in cognitive-related brain areas, what's more, the results warn that MPs may act as vectors of pollutants (mostly heavy metals) increasing the health burden on body.

High-Resolution Imaging of Mitochondria and Mitochondrial Nucleoids in Differentiated SH-SY5Y Cells

Mitochondria are highly dynamic organelles which form intricate networks with complex dynamics. Mitochondrial transport and distribution are essential to ensure proper cell function, especially in cells with an extremely polarised morphology such as neurons. A layer of complexity is added when considering mitochondria have their own genome, packaged into nucleoids. Major mitochondrial morphological transitions, for example mitochondrial division, often occur in conjunction with mitochondrial DNA (mtDNA) replication and changes in the dynamic behaviour of the nucleoids. However, the relationship between mtDNA dynamics and mitochondrial motility in the processes of neurons has been largely overlooked. In this chapter, we describe a method for live imaging of mitochondria and nucleoids in differentiated SH-SY5Y cells by instant structured illumination microscopy (iSIM). We also include a detailed protocol for the differentiation of SH-SY5Y cells into cells with a pronounced neuronal-like morphology and show examples of coordinated mitochondrial and nucleoid motility in the long processes of these cells.

Profiling the chemical nature of anti-oxytotic/ferroptotic compounds with phenotypic screening

Because old age is the greatest risk factor for Alzheimer's disease (AD), it is critical to target the pathological events that link aging to AD in order to develop an efficient treatment that acts upon the primary causes of the disease. One such event might be the activation of oxytosis/ferroptosis, a unique cell death mechanism characterized by mitochondrial dysfunction and lethal lipid peroxidation. Here, a comprehensive library of >900 natural compounds was screened for protection against oxytosis/ferroptosis in nerve cells with the goal of better understanding the chemical nature of inhibitors of oxytosis/ferroptosis. Although the compounds tested spanned structurally diverse chemical classes from animal, microbial, plant and synthetic origins, a small set of very potent anti-oxytotic/ferroptotic compounds was identified that was highly enriched in plant quinones. The ability of these compounds to protect against oxytosis/ferroptosis strongly correlated with their ability to protect against in vitro ischemia and intracellular amyloid-beta toxicity in nerve cells, indicating that aspects of oxytosis/ferroptosis also underly other toxicities that are relevant to AD. Importantly, the anti-oxytotic/ferroptotic character of the quinone compounds relied on their capacity to target and directly prevent lipid peroxidation in a manner that required the reducing activity of cellular redox enzymes, such as NAD(P)H:quinone oxidoreductase 1 (NQO1) and ferroptosis suppressor protein 1 (FSP1). Because some of the compounds increased the production of total reactive oxygen species while decreasing lipid peroxidation, it appears that the pro-oxidant character of a compound can coexist with an inhibitory effect on lipid peroxidation and, consequently, still prevent oxytosis/ferroptosis. These findings have significant implications for the understanding of oxytosis/ferroptosis and open new approaches to the development of future neurotherapies.

Downregulation of lncRNA MEG3 is involved in Parkinson's disease

BACKGROUND

Long non-coding RNA (lncRNA) MEG3 regulates human cancers, while its role in Parkinson's disease (PD) is unknown. The present study explored the involvement of MEG3 in PD.

METHODS

This study enrolled PD patients (n = 79) and healthy controls (n = 62) who were admitted to the Second Affiliated Hospital of Nanchang University from May 2016 to March 2018. RT-qPCR was performed to measure the expression of MEG3 and LRRK2. ROC curve analysis was performed for diagnostic analysis. Cell transfections were performed to analyze the interaction between MEG3 and LRRK2. Cell apoptosis and MTT assays were performed to evaluate the effect of cell transfections on cell apoptosis and viability.

RESULTS

MEG3 was downregulated in PD patients compared to that in the healthy controls. ROC curve analysis showed altered expression of MEG3 in PD patients. MEG3 was also down-regulated in SH-SY5Y cells treated with MPP + . Overexpression of MEG3 increased the expression levels of leucine-rich repeat kinase 2 (LRRK2) in SH-SY5Y cells. In contrast, overexpression of LRRK2 showed no significant effects on MEG3. Overexpression of MEG3 improved the viability and inhibited the apoptosis of SH-SY5Y cells pretreated with MPP + .

CONCLUSIONS

In conclusion, lncRNA MEG3 is downregulated in PD and may affect the expression of LRRK2 to regulate cell viability and apoptosis involved in PD.

Epigallocatechin-3-gallate pretreatment alleviates doxorubicin-induced ferroptosis and cardiotoxicity by upregulating AMPKα2 and activating adaptive autophagy

Reports indicate that the mechanism of doxorubicin (Dox)-induced cardiotoxicity is very complex, involving multiple regulatory cell death forms. Furthermore, the clinical intervention effect is not ideal. Iron dependence, abnormal lipid metabolism, and excess reactive oxygen species generation, three characteristics of ferroptosis, are potential therapeutic intervention targets. Here, we confirmed in vitro and in vivo that at least autophagy, apoptosis, and ferroptosis are involved in Dox cardiotoxicity-induced damage. When the neonatal rat cardiomyocytes and H9C2 cells or C57BL/6 mice were subjected to Dox-induced cardiotoxicity, epigallocatechin-3-gallate pretreatment could effectively decrease iron accumulation, inhibit oxidative stress and abnormal lipid metabolism, and thereby alleviate Dox cardiotoxicity-induced ferroptosis and protect the myocardium according to multiple functional, enzymatic, and morphological indices. The underlying mechanism was verified to involve the upregulation and activation of AMP-activated protein kinase α2, which promoted adaptive autophagy, increased energy supply, and maintained mitochondrial function. We believe that epigallocatechin-3-gallate is a candidate phytochemical against Dox-induced cardiotoxicity.

Korean red ginseng decreases 1-methyl-4-phenylpyridinium-induced mitophagy in SH-SY5Y cells

OBJECTIVE

Mitophagy is known to contribute towards progression of Parkinson's disease. Korean red ginseng (KRG) is a widely used medicinal herb in East Asia, and recent studies have reported that KRG prevents 1-methyl-4-phenylpyridinium ion (MPP⁺)-induced cell death. This study was undertaken to investigate whether KRG suppresses MPP⁺-induced apoptosis and mitophagy.

METHODS

SH-SY5Y cells were incubated with KRG for 24 h, and subsequently exposed to MPP⁺. The MPP⁺-induced cell death was confirmed with the 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay, and the terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling assay. Changes in the structure and function of mitochondria were confirmed using mitotracker, MitoSOX red mitochondrial superoxide indicator, parkin, and phosphatase and tensin homolog deleted on chromosome ten-induced putative kinase 1 (PINK1) immunofluorescent staining. Western blotting was performed to evaluate the expression of apoptosis-related factors in whole cells, including Bax, Bcl-2 and cleaved caspase-3, and mitophagy-related factors in the mitochondrial fraction, including cytochrome c, parkin, PINK1, translocase of the outer membrane 20 (TOM20), p62 and Beclin 1.

RESULTS

MPP⁺ induced cell death by cytochrome c release and caspase-3 activation; however, this effect was suppressed by KRG's regulation of the expressions of Bcl-2 and Bax. Moreover, MPP⁺ exposure increased the mitochondrial expressions of parkin, PINK1, Beclin 1 and p62, and decreased TOM20, cytochrome c and Bcl-2 expressions. These MPP⁺-induced changes in the mitochondrial fraction were attenuated by treatment with KRG.

CONCLUSION

KRG effectively prevents MPP⁺-induced SH-SY5Y cell death by regulating cytochrome c release from mitochondria and PINK1/parkin-mediated mitophagy, through regulation of the Bcl-2 family.

Preclinical Evidence for the Interplay between Oxidative Stress and RIP1-Dependent Cell Death in Neurodegeneration: State of the Art and Possible Therapeutic Implications

Neurodegenerative diseases are the most frequent chronic, age-associated neurological pathologies having a major impact on the patient’s quality of life. Despite a heavy medical, social and economic burden they pose, no causative treatment is available for these diseases. Among the important pathogenic factors contributing to neuronal loss during neurodegeneration is elevated oxidative stress resulting from a disturbed balance between endogenous prooxidant and antioxidant systems. For many years, it was thought that increased oxidative stress was a cause of neuronal cell death executed via an apoptotic mechanism. However, in recent years it has been postulated that rather programmed necrosis (necroptosis) is the key form of neuronal death in the course of neurodegenerative diseases. Such assumption was supported by biochemical and morphological features of the dying cells as well as by the fact that various necroptosis inhibitors were neuroprotective in cellular and animal models of neurodegenerative diseases. In this review, we discuss the relationship between oxidative stress and RIP1-dependent necroptosis and apoptosis in the context of the pathomechanism of neurodegenerative disorders. Based on the published data mainly from cellular models of neurodegeneration linking oxidative stress and necroptosis, we postulate that administration of multipotential neuroprotectants with antioxidant and antinecroptotic properties may constitute an efficient pharmacotherapeutic strategy for the treatment of neurodegenerative diseases.

A Compartmentalized Neuronal Cell-Culture Platform Compatible With Cryo-Fixation by High-Pressure Freezing for Ultrastructural Imaging

The human brain contains a wide array of billions of neurons and interconnections, which are often simplified for analysis in vitro using compartmentalized microfluidic devices for neuronal cell culturing, to better understand neuronal development and disease. However, such devices are traditionally incompatible for high-pressure freezing and high-resolution nanoscale imaging and analysis of their sub-cellular processes by methods including electron microscopy. Here we develop a novel compartmentalized neuronal co-culture platform allowing reconstruction of neuronal networks with high variable spatial control, which is uniquely compatible for high-pressure freezing. This cryo-fixation method is well-established to enable high-fidelity preservation of the reconstructed neuronal networks and their sub-cellular processes in a near-native vitreous state without requiring chemical fixatives. To direct the outgrowth of neurites originating from two distinct groups of neurons growing in the two different compartments, polymer microstructures akin to microchannels are fabricated atop of sapphire disks. Two populations of neurons expressing either enhanced green fluorescent protein (EGFP) or mCherry were grown in either compartment, facilitating the analysis of the specific interactions between the two separate groups of cells. Neuronally differentiated PC12 cells, murine hippocampal and striatal neurons were successfully used in this context. The design of this device permits direct observation of entire neuritic processes within microchannels by optical microscopy with high spatial and temporal resolution, prior to processing for high-pressure freezing and electron microscopy. Following freeze substitution, we demonstrate that it is possible to process the neuronal networks for ultrastructural imaging by electron microscopy. Several key features of the embedded neuronal networks, including mitochondria, synaptic vesicles, axonal terminals, microtubules, with well-preserved ultrastructures were observed at high resolution using focused ion beam - scanning electron microscopy (FIB-SEM) and serial sectioning - transmission electron microscopy (TEM). These results demonstrate the compatibility of the platform with optical microscopy, high-pressure freezing and electron microscopy. The platform can be extended to neuronal models of brain disease or development in future studies, enabling the investigation of subcellular processes at the nanoscale within two distinct groups of neurons in a functional neuronal pathway, as well as pharmacological testing and drug screening.

Necrostatin-1 Prevents Ferroptosis in a RIPK1- and IDO-Independent Manner in Hepatocellular Carcinoma

Ferroptosis is caused by the iron-mediated accumulation of lipid peroxidation, which is distinct from apoptosis and necroptosis. Necrostatin-1 inhibits receptor-interacting serine/threonine-protein kinase 1 (RIPK1) to initiate necroptosis; it also inhibits indoleamine 2,3-dioxygenase (IDO) to regulate tumor immunity. However, few studies have examined the off-target effect of necrostatin-1 on the ferroptosis pathway. The present study examined whether necrostatin-1 could interrupt ferroptosis induced by system xc- inhibitors (sulfasalazine and erastin) and a glutathione peroxidase 4 inhibitor (RSL3) in Huh7 and SK-HEP-1 cells. Necrostatin-1 completely prevented decreases in cell viability induced by sulfasalazine and erastin; it partially blunted decreases in cell viability induced by RSL3. Necrostatin-1, ferrostatin-1, and deferoxamine repressed sulfasalazine-provoked membrane permeabilization, as detected by 7-aminoactinomycin D staining and lipid peroxidation measured using a C11-BODIPY probe. However, other RIPK1 inhibitors (necrostatin-1s and GSK2982772) and an IDO inhibitor (1-methyl-D-tryptophan) did not recover the decrease in cell viability induced by sulfasalazine. Necrostatin-1 potentiated sulfasalazine-induced expression of xCT, a catalytic subunit of system xc- in these cells. These results demonstrated that necrostatin-1 blocked ferroptosis through a mechanism independent from RIPK1 and IDO inhibition in Huh7 and SK-HEP-1 cells, indicating that its antioxidant activity should be considered when using necrostatin-1 as a RIPK1 inhibitor.

Cell Death-Osis of Dopaminergic Neurons and the Role of Iron in Parkinson's Disease

Significance: There is still no cure for neurodegenerative diseases, such as Parkinson's disease (PD). Current treatments are based on the attempt to reduce dopaminergic neuronal loss, and multidisciplinary approaches have been used to provide only a temporary symptoms' relief. In addition to the difficulties of drugs developed against PD to access the brain, the specificity of those inhibitory compounds could be a concern. This because neurons might degenerate by activating distinct signaling pathways, which are often initiated by the same stimulus. Recent Advances: Apoptosis, necroptosis, and ferroptosis were shown to significantly contribute to PD progression and, so far, are the main death programs described as capable to alter brain homeostasis. Their activation is characterized by different biochemical and morphological features, some of which might even share the same molecular players. Critical Issues: If there is a pathological need to engage, in PD, multiple death programs, sequentially or simultaneously, is not clear yet. Possibly the activation of apoptosis, necroptosis, and/or ferroptosis correlates to different PD stages and symptom severities. This would imply that the efficacy of therapeutic approaches against neuronal death might depend on the death program they target and the relevance of this death pathway on a specific PD phase. Future Directions: In this review, we describe the molecular mechanisms underlying the activation of apoptosis, necroptosis, and ferroptosis in PD. Understanding the interrelationship between different death pathways' activation in PD is of utmost importance for the development of therapeutic approaches against disease progression. Antioxid. Redox Signal. 35, 453-473.

Neuroprotective Activities of Crossyne flava Bulbs and Amaryllidaceae Alkaloids: Implications for Parkinson's Disease

Parkinson’s disease (PD) is one of the most common neurodegenerative diseases and affects approximately 6.3 million people worldwide. To date, the treatment of PD remains a challenge, as available treatment options are known to be associated with serious side effects; hence, the search for new treatment strategies is critical. Extracts from the Amaryllidaceae plant family as well as their alkaloids have been reported to have neuroprotective potentials. This study, therefore, investigated the biological activities of Crossyne flava and its isolated alkaloids in an in vitro MPP⁺ (1-methyl-4-phenylpyridinium) PD model using SH-SY5Y cells. The effects of the total extract as well as the four compounds isolated from Crossyne flava (i.e., pancratinine B (1), bufanidrine (2), buphanisine (3), and epibuphanisine (4)) were evaluated for cell viability, neuroprotection, levels of reactive oxygen species (ROS), adenosine triphosphate activity (ATP), and caspase 3/7 activity in SH-SY5Y cells. The results obtained showed that pre-treatment with both the extract and the isolated compounds was effective in protecting the SH-SY5Y cells from MPP⁺-induced neurotoxicity and inhibited ROS generation, ATP depletion as well as apoptosis induction in the SH-SY5Y cells. The results of this study show that the Amaryllidaceae plant family may be a source of novel compounds for the treatment of neurodegenerative diseases, which validates the reported traditional uses.

Ferroptosis as a New Mechanism in Parkinson's Disease Therapy Using Traditional Chinese Medicine

Parkinson’s disease (PD) is one of the most common neurodegenerative diseases. To date, among medications used to treat PD, only levodopa exhibits a limited disease-modifying effect on early-onset PD, but it cannot delay the progression of the disease. In 2018, for the first time, the World Health Organization included traditional Chinese medicine (TCM) in its influential global medical compendium. The use of TCM in the treatment of PD has a long history. At present, TCM can help treat and prevent PD. Iron metabolism is closely associated with PD. Ferroptosis, which is characterized by the accumulation of lipid peroxides, is a recently discovered form of iron-dependent cell death. The research literature indicates that ferroptosis in dopaminergic neurons is an important pathogenetic mechanism of PD. TCM may thus play unique roles in the treatment of PD and provide new ideas for the treatment of PD by regulating pathways associated with ferroptosis.

Mediterranean Diet and Neurodegenerative Diseases: The Neglected Role of Nutrition in the Modulation of the Endocannabinoid System

Neurodegenerative disorders are a widespread cause of morbidity and mortality worldwide, characterized by neuroinflammation, oxidative stress and neuronal depletion. The broad-spectrum neuroprotective activity of the Mediterranean diet is widely documented, but it is not yet known whether its nutritional and caloric balance can induce a modulation of the endocannabinoid system. In recent decades, many studies have shown how endocannabinoid tone enhancement may be a promising new therapeutic strategy to counteract the main hallmarks of neurodegeneration. From a phylogenetic point of view, the human co-evolution between the endocannabinoid system and dietary habits could play a key role in the pro-homeostatic activity of the Mediterranean lifestyle: this adaptive balance among our ancestors has been compromised by the modern Western diet, resulting in a “clinical endocannabinoid deficiency syndrome”. This review aims to evaluate the evidence accumulated in the literature on the neuroprotective, immunomodulatory and antioxidant properties of the Mediterranean diet related to the modulation of the endocannabinoid system, suggesting new prospects for research and clinical interventions against neurodegenerative diseases in light of a nutraceutical paradigm.