Cellular Model Of Parkinson's Disease Research Articles

JWA binding to NCOA4 alleviates degeneration in dopaminergic neurons through suppression of ferritinophagy in Parkinson's disease

Parkinson's disease (PD) poses a significant challenge in neurodegenerative disorders, characterized by the progressive loss of dopaminergic (DA) neurons in the substantia nigra pars compacta (SNc). The intricate mechanisms orchestrating DA neurodegeneration in PD are not fully understood, necessitating the exploration of innovative therapeutic approaches. Recent studies have implicated ferroptosis as a major contributor to the loss of DA neurons, revealing a complex interplay between iron accumulation and neurodegeneration. However, the sophisticated nature of this process challenges the conventional belief that mere iron removal could effectively prevent DA neuronal ferroptosis. Here, we report JWA, alternatively referred to as ARL6IP5, as a negative regulator of ferroptosis, capable of ameliorating DA neuronal loss in the context of PD. In this study, synchronized expression patterns of JWA and tyrosine hydroxylase (TH) in PD patients and mice were observed, underscoring the importance of JWA for DA neuronal survival. Screening of ferroptosis-related genes unraveled the engagement of iron metabolism in the JWA-dependent inhibition of DA neuronal ferroptosis. Genetic manipulation of JWA provided compelling evidence linking its neuroprotective effects to the attenuation of NCOA4-mediated ferritinophagy. Molecular docking, co-immunoprecipitation, and immunofluorescence studies confirmed that JWA mitigated DA neuronal ferroptosis by occupying the ferritin binding site of NCOA4. Moreover, the JWA-activating compound, JAC4, demonstrated promising neuroprotective effects in cellular and animal PD models by elevating JWA expression, offering a potential avenue for neuroprotection in PD. Collectively, our work establishes JWA as a novel regulator of ferritinophagy, presenting a promising therapeutic target for addressing DA neuronal ferroptosis in PD.

MiR-29a efficiently suppresses the generation of reactive oxygen species and α-synuclein in a cellular model of Parkinson's disease by potentially targeting GSK-3β

MicroRNA-29a (miR-29a) has been suggested to serve a potential protective function against Parkinson's disease (PD); however, the exact molecular mechanisms remain elusive. This study explored the protective role of miR-29a in a cellular model of PD using SH-SY5Y cell lines through iTRAQ-based quantitative proteomic and biochemistry analysis. The findings showed that using a miR-29a mimic in SH-SY5Y cells treated with 1-methyl-4-phenylpyridinium (MPP+) significantly decreased cell death and increased mitochondrial membrane potential. It also reduced mitochondrial reactive oxygen species (ROS) and the production of α-synuclein. Subsequent heatmap analysis using iTRAQ-based quantitative proteomics revealed remarkably contrasting protein expression profiles for 882 genes when comparing the groups treated with miR-29a mimic plus MPP + against the control group treated solely with MPP+. The KEGG pathway analysis of these 882 genes indicated the substantial role of miR-29a in the PD pathway (P = 1.58x10−5) and highlighted its function in mitochondrial genes. Furthermore, treatment with a miR-29a mimic in SH-SY5Y cells reduced the levels of GSK-3β, phosphorylated GSK-3β, and cleaved caspase-7 following exposure to MPP+. The miR-29a mimic also upregulated the expressions of α-synuclein clearance proteins FYCO1 and Rab7 in this cellular PD model, thereby inhibiting the production of α-synuclein. Luciferase activity analysis confirmed the specific binding of miR-29a to the 3′ untranslated region (3′UTR) of GSK-3β, leading to its repression. Our findings demonstrated miR-29a′s neuroprotective role in mitochondrial function and highlighted its potential to inhibit ROS and α-synuclein production, offering possible therapeutic avenues for PD treatment.

Sitagliptin elevates plasma and CSF incretin levels following oral administration to nonhuman primates: relevance for neurodegenerative disorders.

The endogenous incretins glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) possess neurotrophic, neuroprotective, and anti-neuroinflammatory actions. The dipeptidyl peptidase 4 (DPP-4) inhibitor sitagliptin reduces degradation of endogenous GLP-1 and GIP, and, thereby, extends the circulation of these protective peptides. The current nonhuman primate (NHP) study evaluates whether human translational sitagliptin doses can elevate systemic and central nervous system (CNS) levels of GLP-1/GIP in naive, non-lesioned NHPs, in line with our prior rodent studies that demonstrated sitagliptin efficacy in preclinical models of Parkinson's disease (PD). PD is an age-associated neurodegenerative disorder whose current treatment is inadequate. Repositioning of the well-tolerated and efficacious diabetes drug sitagliptin provides a rapid approach to add to the therapeutic armamentarium for PD. The pharmacokinetics and pharmacodynamics of 3 oral sitagliptin doses (5, 20, and 100mg/kg), equivalent to the routine clinical dose, a tolerated higher clinical dose and a maximal dose in monkey, were evaluated. Peak plasma sitagliptin levels were aligned both with prior reports in humans administered equivalent doses and with those in rodents demonstrating reduction of PD associated neurodegeneration. Although CNS uptake of sitagliptin was low (cerebrospinal fluid (CSF)/plasma ratio 0.01), both plasma and CSF concentrations of GLP-1/GIP were elevated in line with efficacy in prior rodent PD studies. Additional cellular studies evaluating human SH-SY5Y and primary rat ventral mesencephalic cultures challenged with 6-hydroxydopamine, established cellular models of PD, demonstrated that joint treatment with GLP-1 + GIP mitigated cell death, particularly when combined with DPP-4 inhibition to maintain incretin levels. In conclusion, this study provides a supportive translational step towards the clinical evaluation of sitagliptin in PD and other neurodegenerative disorders for which aging, similarly, is the greatest risk factor.

Neuronal exosomal miRNAs modulate mitochondrial functions and cell death in bystander neuronal cells under Parkinson’s disease stress conditions

Parkinson’s Disease (PD) is a chronic neurodegenerative disorder characterized by progressive loss of midbrain dopaminergic neurons in the substantia nigra part of the brain. Pathology spread to numerous brain regions and cell types suggests that intercellular communication is essential to PD progression. Exosomes mediate intercellular communication between neurons, glia, and other cell types throughout PD-relevant brain regions. However, the mechanism remains unclear, and its implication in PD pathology, is not well understood. In the current study, we explored the role of exosomes in modulating the response to PD-relevant toxicants. In cellular models of PD, neuronal cell-derived exosomes are readily internalized by recipient neuronal cells as intact vesicles. Internalized exosomes in bystander neuronal cells localize to mitochondria and dysregulate mitochondrial functions, leading to cell death under PD stress conditions. NGS analysis of exosomes released by neuronal cells subjected to PD stress conditions showed that levels of specific miRNAs were altered in exosomes under PD stress conditions. Bioinformatic analysis of the miRNA targets revealed enriched pathways related to neuronal processes and morphogenesis, apoptosis and ageing. Levels of two miRNAs, hsa-miR-30a-5p and hsa-miR-181c-5p, were downregulated in exosomes under PD stress conditions. Expression of the identified miRNAs in neuronal cells led to their enrichment in exosomes, and exosome uptake in neuronal cells ameliorated mitochondrial dysfunction induced by PD stress conditions and rescued cell death. In conclusion, loss of enrichment of specific miRNAs, including miR-30a-5p and miR-181c-5p, under PD stress conditions causes mitochondrial dysfunction and neuronal death, and hence may lead to progression of PD.

Biological Activity of Novel Pyrrole Derivatives as Antioxidant Agents Against 6-OHDA Induced Neurotoxicity in PC12 Cells.

Neuroinflammation and oxidative stress are critical factors involved in the pathogenesis of Parkinson's disease (PD), the second most common progressive neurodegenerative disease. Additionally, lipid peroxidation end products contribute to inflammatory responses by activating pro-inflammatory genes. Lipid peroxidation occurs as a result of either the overproduction of intracellular reactive oxygen species (ROS) or the reaction of cyclooxygenases (COXs). In this study, we examined the role of 1,5-diaryl pyrrole derivatives against the neurotoxic effects of 6-hydroxydopamine (6-OHDA) in a cellular model of PD. PC12 cells were pre-treated with compounds 2-(4-chlorophenyl)-5-methyl-1-(4-(trifluoromethoxy)phenyl)-1H-pyrrole (A), 2-(4-chlorophenyl)-1-(4-methoxyphenyl)-5-methyl-1H-pyrrole (B), and 1-(2-chlorophenyl)-2-(4-chlorophenyl)-5-methyl-1H-pyrrole (C), respectively, 24 h before exposure to 6-OHDA. We conducted various assays, including 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazoliumbromide (MTT), ROS, and lipid peroxidation assays, Hoechst staining, Annexin V/PI, Western blotting analysis and ELISA method, to assess the neuroprotective effects of pyrrole derivatives on 6-OHDA-induced neurotoxicity. Our results demonstrated that apoptosis induction was inhibited by controlling the lipid peroxidation process in the in vitro model following pre-treatment with compounds A, B, and, somehow, C. Furthermore, compounds A and C likely act by suppressing the COX-2/PGE2 pathway, a mechanism not attributed to compound B. These findings suggest that the novel synthetic pyrrolic derivatives may be considered promising neuroprotective agents that can potentially prevent the progression of PD.

Enhanced mTORC1 signaling and protein synthesis in pathologic α-synuclein cellular and animal models of Parkinson's disease.

Pathologic α-synuclein plays an important role in the pathogenesis of α-synucleinopathies such as Parkinson's disease (PD). Disruption of proteostasis is thought to be central to pathologic α-synuclein toxicity; however, the molecular mechanism of this deregulation is poorly understood. Complementary proteomic approaches in cellular and animal models of PD were used to identify and characterize the pathologic α-synuclein interactome. We report that the highest biological processes that interacted with pathologic α-synuclein in mice included RNA processing and translation initiation. Regulation of catabolic processes that include autophagy were also identified. Pathologic α-synuclein was found to bind with the tuberous sclerosis protein 2 (TSC2) and to trigger the activation of the mammalian target of rapamycin (mTOR) complex 1 (mTORC1), which augmented mRNA translation and protein synthesis, leading to neurodegeneration. Genetic and pharmacologic inhibition of mTOR and protein synthesis rescued the dopamine neuron loss, behavioral deficits, and aberrant biochemical signaling in the α-synuclein preformed fibril mouse model and Drosophila transgenic models of pathologic α-synuclein-induced degeneration. Pathologic α-synuclein furthermore led to a destabilization of the TSC1-TSC2 complex, which plays an important role in mTORC1 activity. Constitutive overexpression of TSC2 rescued motor deficits and neuropathology in α-synuclein flies. Biochemical examination of PD postmortem brain tissues also suggested deregulated mTORC1 signaling. These findings establish a connection between mRNA translation deregulation and mTORC1 pathway activation that is induced by pathologic α-synuclein in cellular and animal models of PD.

MiR-15b-5p transcription mediated by CREB1 protects against inflammation and apoptosis in Parkinson disease models by inhibiting AXIN2 and activating Wnt/β-catenin.

Parkinson disease (PD) is a major neurodegenerative disease that greatly undermines people's health and for which effective therapeutic strategies are currently limited. This study dissected the effects of expression changes of AXIN2, a modulator of the Wnt/beta-catenin signaling pathway, the transcription factor CREB1, and of the microRNA miR-15b-5p on apoptosis and the inflammatory response in a PD mouse model in vivo and in a cellular PD model in vitro. The analyses demonstrated low CREB1 and miR-15b-5p expression and high AXIN2 expression in both models. miR-15b-5p overexpression or AXIN2 knockdown alleviated the inflammatory response indicated by decreased levels of TNF-α, IL-6, and IL-1β and apoptosis indicated by decreased levels of cleaved caspase-3 and Bax and elevated Bcl-2. Protection by miR-15b-5p upregulation was counteracted by the simultaneous overexpression of AXIN2. miR-15b-5p targeted AXIN2. CREB1 promoted miR-15b-5p expression, which activated the Wnt/β-catenin pathway by inhibiting AXIN2. Collectively, the data indicate that transcriptional expression of miR-15b-5p can be promoted by CREB1 to inhibit AXIN2 and activate Wnt/β-catenin, thereby reducing the inflammatory response and apoptosis in these PD models. These data suggest the CREB1/miR-15b-5p/AXIN2 axis is a potential therapeutic target in PD patients.

Vinpocetine Exerts Neuroprotective Effects via Downregulating α-Syn in Rotenone-induced Cellular Models of Parkinson’s Disease

Objective: Vinpocetine (Vinp), a derivative of alkaloid vincristine with anti-inflammatory and antioxidant effects, has been shown to have neuroprotective effects in Parkinson's disease (PD). Its role and mechanisms, however, are not fully understood. Therefore, the aim of this study was to investigate the effects and possible mechanisms of Vinp on PD cells. Methods: SH-SY5Y cells were treated with Vinp and then with rotenone to induce a cellular model of PD. The proliferation level and apoptosis rate of SH-SY5Y cells after different treatments were detected by MTT and flow cytometry assays, respectively. Western blot was used to determine the relative protein expression of α-Synuclein (α-Syn) in differently treated cells. Additionally, commercial kits and ELISA were used to determine oxidative stress-related indicators (superoxide dismutase [SOD], malondialdehyde [MDA], and reactive oxygen species [ROS]) and inflammatory factors (tumor necrosis factor α [TNF-α], interleukin-5 [IL-5], and interleukin-1β [IL-1β]) in SH-SY5Y cells after different treatments, respectively. Results: Vinp at different concentrations (5, 10, and 50 µM) had no significant effect on the proliferation and apoptosis of SH-SY5Y cells. For rotenone-induced SH-SY5Y cells, Vinp pretreatment could significantly reduce α-Syn expression, increased cell viability and decreased apoptosis, oxidative stress (downregulation of ROS and MDA levels and upregulation of SOD activity) and inflammation (increased levels of TNF-α, IL-5, and IL-1β). In contrast, overexpression of α-Syn in SHSY5Y cells with Vinp pretreatment and rotenone induction partially reversed the aforementioned protective effects of Vinp, causing a decrease in proliferation, an increase in apoptosis rate, inflammation, and oxidative stress. Conclusion: Vinp exerted neuroprotective effects by downregulating α-Syn to promote proliferation, inhibit apoptosis, and inhibit oxidative stress and inflammation in rotenone-induced SH-SY5Y cells.

Mesenchymal stem cell exosomes rich in miR-23b-3p affect the Wnt signaling pathway and promote neuronal autophagy to alleviate PD symptoms

This study aims to elucidate the role of miR-23b-3p in mesenchymal stem cell exosomes in regulating the Wnt signaling pathway to promote autophagy of neurons and alleviate Parkinson's disease (PD) symptoms. We generated rat and cellular PD models with 6-OHDA, treated them with mesenchymal stem cell exosomes rich in miR-23b-3p and determined the expression of α-syn and Wnt/β-catenin pathway and autophagy-related genes. In the plasma of PD patients, the levels of miR-23b-3p and the Wnt/β-catenin pathway-related genes β-catenin and DAT were low, while α-syn expression was high. In the PD cell model, miR-23b-3p was downregulated, the Wnt pathway was inhibited, α-syn was upregulated, neuron autophagy was inhibited, and the revitalization of the Wnt/β-catenin pathway could promote the autophagy of neurons. Coculture of miR-23b-3p-enriched exosomes with MN9D cells confirmed that miR-23b-3p-enriched exosomes could promote autophagy in MN9D cells in a PD cell model. Moreover, animal experiments confirmed the results of the cell experiments. Therefore, miR-23b-3p-enriched mesenchymal stem cell exosomes promote neuronal autophagy by regulating the Wnt signaling pathway, thus alleviating PD progression and providing an important basis for the clinical treatment of PD.

ErbB2pY -1248 as a predictive biomarker for Parkinson's disease based on research with RPPA technology and in vivo verification.

This study aims to reveal a promising biomarker for Parkinson's disease (PD) based on research with reverse phase protein array (RPPA) technology for the first time and in vivo verification, which gains time for early intervention in PD, thus increasing the effectiveness of treatment and reducing disease morbidity. We employed RPPA technology which can assess both total and post-translationally modified proteins to identify biomarker candidates of PD in a cellular PD model. As a result, the phosphorylation (pY-1248) of the epidermal growth factor receptor (EGFR) ErbB2 is a promising biomarker candidate for PD. In addition, lapatinib, an ErbB2 tyrosine kinase inhibitor, was used to verify this PD biomarker candidate in vivo. We found that lapatinib-attenuated dopaminergic neuron loss and PD-like behavior in the zebrafish PD model. Accordingly, the expression of ErbB2pY-1248 significantly increased in the MPTP-induced mouse PD model. Our results suggest that ErbB2pY-1248 is a predictive biomarker for PD. In this study, we found that ErbB2pY-1248 is a predictive biomarker of PD by using RPPA technology and in vivo verification. It offers a new perspective on PD diagnosing and treatment, which will be essential in identifying individuals at risk of PD. In addition, this study provides new ideas for digging into biomarkers of other neurodegenerative diseases.

Phenotypic Profiling of Human Stem Cell-Derived Midbrain Dopaminergic Neurons.

Parkinson's disease (PD) is linked to a range of cell biological processes that cause midbrain dopaminergic (mDA) neuron loss. Many current in vitro PD cellular models lack complexity and do not take multiple phenotypes into account. Phenotypic profiling in human induced pluripotent stem cell (iPSC)-derived mDA neurons can address these shortcomings by simultaneously measuring a range of neuronal phenotypes in a PD-relevant cell type in parallel. Here, we describe a protocol to obtain and analyze phenotypic profiles from commercially available human mDA neurons. A neuron-specific fluorescent staining panel is used to visualize the nuclear, α-synuclein, Tyrosine hydroxylase (TH), and Microtubule-associated protein 2 (MAP2) related phenotypes. The described phenotypic profiling protocol is scalable as it uses 384-well plates, automatic liquid handling and high-throughput microscopy. The utility of the protocol is exemplified using healthy donor mDA neurons and mDA neurons carrying the PD-linked G2019S mutation in the Leucine-rich repeat kinase 2 (LRRK2) gene. Both cell lines were treated with the LRRK2 kinase inhibitor PFE-360 and phenotypic changes were measured. Additionally, we demonstrate how multidimensional phenotypic profiles can be analyzed using clustering or machine learning-driven supervised classification methods. The described protocol will particularly interest researchers working on neuronal disease modeling or studying chemical compound effects in human neurons.

Dyshomeostasis of Iron and Its Transporter Proteins in Cypermethrin-Induced Parkinson's Disease.

The etiology of Parkinson's disease (PD) is highly complex and is still indefinable. However, a number of studies have indicated the involvement of pesticides and transition metals. Copper, magnesium, iron, and zinc have emerged as important metal contributors. Exposure to pesticides causes an accumulation of transition metals in the substantia nigra (SN) region of the brain. The cypermethrin model of PD is characterized by mitochondrial dysfunction, autophagy impairment, oxidative stress, etc. However, the effect of cypermethrin on metal homeostasis is not yet explored. The study was designed to delineate the role of metals and their transporter proteins in cypermethrin-induced animal and cellular models of PD. The level of copper, magnesium, iron, and zinc was checked in the nigrostriatal tissue and serum by atomic absorption spectroscopy. Since cypermethrin consistently increased iron content in the nigrostriatal tissue and serum after 12weeks of exposure, the level of iron transporter proteins, such as divalent metal transporter-1 (DMT-1), ceruloplasmin, transferrin, ferroportin, and hepcidin, and their in silico interaction with cypermethrin were checked. 3,3'-Diaminobenzidine-enhanced Perl's staining showed an elevated number of iron-positive cells in the SN of cypermethrin-treated rats. Molecular docking studies revealed a strong binding affinity between cypermethrin and iron transporter protein receptors of humans and rats. Furthermore, cypermethrin increased the expression of DMT-1 and hepcidin while reducing the expression of transferrin, ceruloplasmin, and ferroportin in the nigrostriatal tissue and human neuroblastoma cells. These observations suggest that cypermethrin alters the expression of iron transporter proteins leading to iron dyshomeostasis, which could contribute to dopaminergic neurotoxicity.

The mitochondrial uncoupling effects of nitazoxanide enhances cellular autophagy and promotes the clearance of α-synuclein: Potential role of AMPK-JNK pathway

Upregulation and aggregation of the pre-synaptic protein, α-synuclein plays a key role in Parkinson's disease (PD) and mitochondrial dysfunction was surmised to be an upstream event in the disease pathogenesis. Emerging reports identified the role of nitazoxanide (NTZ), an anti-helminth drug, in enhancing mitochondrial oxygen consumption rate (OCR) and autophagy. In the present study, we have examined the mitochondrial effects of NTZ in mediating cellular autophagy and subsequent clearance of both endogenous and pre-formed aggregates of α-synuclein in cellular model of PD. Our results demonstrate that the mitochondrial uncoupling effects of NTZ results in the activation of AMPK and JNK, which in-turn leads to the enhancement of cellular autophagy. Also,1-methyl-4-phenylpyridinium (MPP+) mediated decrease in autophagic flux with a concomitant increase in the α-synuclein levels were ameliorated in cells treated with NTZ. However, in cells lacking functional mitochondria (ρ0 cells), NTZ did not mitigate MPP+ mediated alterations in the autophagic clearance of α-synuclein, indicating that the mitochondrial effects of NTZ play a crucial role in the clearance of α-synuclein by autophagy. Also, the ability of AMPK inhibitor, compound C, in abrogating NTZ mediated enhancement in the autophagic flux and α-synuclein clearance highlight the pivotal role of AMPK in NTZ mediated autophagy. Further, NTZ per se enhanced the clearance of preformed α-synuclein aggregates that were exogenously added to the cells. Overall, the results of our present study suggest that NTZ activates macroautophagy in cells due to its uncoupling effects on mitochondrial respiration via activation of AMPK-JNK pathway resulting in the clearance of both endogenous and pre-formed α-synuclein aggregates. As NTZ happens to possess good bioavailability and safety profile, considering this drug for PD based on its mitochondrial uncoupling and autophagy enhancing properties for mitigating mitochondrial reactive oxygen species (ROS) and α-synuclein toxicity appears to be a promising therapeutic option.

Retinoic Acid Prevents α-Synuclein Preformed Fibrils-Induced Toxicity via Inhibiting STAT1-PARP1 Signaling.

Parkinson's disease (PD), the second-most prevalent neurodegenerative disorder, is characterized by the aberrant deposition of α-synuclein (α-Syn) aggregation in neurons. Recent reports have shown that retinoic acid (RA) ameliorates motor deficits. However, the underlying molecular mechanisms remain unclear. In this article, we investigated the effects of RA on cellular and animal models of PD. We found that RA is beneficial for neuronal survival in PD-associated models. In α-Syn preformed fibrils-treated mice, RA administration relieved the formation of intracellular inclusions, dopaminergic neuronal loss, and behavioral deficits. α-Syn preformed fibrils-treated SH-SY5Y cells manifested decreased cell viability, apoptosis, α-Syn aggregation, and autophagy defects. All these negative phenomena were alleviated by RA. More importantly, RA could inhibit the neurotoxicity via inhibiting α-Syn preformed fibrils-induced STAT1-PARP1 signaling, which could also be antagonized by IFN-γ. In conclusion, RA could hinder α-Syn preformed fibrils-induced toxicity by inhibiting STAT1-PARP1 signaling. Thus, we present new insight into RA in PD management.

Neuroprotection of Andrographolide against Neurotoxin MPP+-Induced Apoptosis in SH-SY5Y Cells via Activating Mitophagy, Autophagy, and Antioxidant Activities.

Parkinson's disease (PD) is associated with dopaminergic neuron loss and alpha-synuclein aggregation caused by ROS overproduction, leading to mitochondrial dysfunction and autophagy impairment. Recently, andrographolide (Andro) has been extensively studied for various pharmacological properties, such as anti-diabetic, anti-cancer, anti-inflammatory, and anti-atherosclerosis. However, its potential neuroprotective effects on neurotoxin MPP+-induced SH-SY5Y cells, a cellular PD model, remain uninvestigated. In this study, we hypothesized that Andro has neuroprotective effects against MPP+-induced apoptosis, which may be mediated through the clearance of dysfunctional mitochondria by mitophagy and ROS by antioxidant activities. Herein, Andro pretreatment could attenuate MPP+-induced neuronal cell death that was reflected by reducing mitochondrial membrane potential (MMP) depolarization, alpha-synuclein, and pro-apoptotic proteins expressions. Concomitantly, Andro attenuated MPP+-induced oxidative stress through mitophagy, as indicated by increasing colocalization of MitoTracker Red with LC3, upregulations of the PINK1-Parkin pathway, and autophagy-related proteins. On the contrary, Andro-activated autophagy was compromised when pretreated with 3-MA. Furthermore, Andro activated the Nrf2/KEAP1 pathway, leading to increasing genes encoding antioxidant enzymes and activities. This study elucidated that Andro exhibited significant neuroprotective effects against MPP+-induced SH-SY5Y cell death in vitro by enhancing mitophagy and clearance of alpha-synuclein through autophagy, as well as increasing antioxidant capacity. Our results provide evidence that Andro could be considered a potential supplement for PD prevention.

The Parkinson's disease-associated protein α-synuclein inhibits hepatoma by exosome delivery.

Numerous epidemiological studies suggest a link between Parkinson's disease (PD) and cancer. However, their relevant pathogenesis is not clear. In the present study, we investigated the potential role of exosome-delivered α-synuclein (α-syn) in the regulation between PD and liver cancer. We cultured hepatocellular carcinoma (HCC) cells with exosomes derived from conditioned medium of the PD cellular model, and injected exosomes enriched with α-syn into the striatum of a liver cancer rat model. We found that α-syn-contained exosomes from the rotenone-induced cellular model of PD suppressed the growth, migration, and invasion of HCC cells. Integrin αVβ5 in exosomes from the rotenone-induced PD model was higher than that in the control, resulting in more α-syn-contained exosomes being taken up by HCC cells. Consistently, in vivo experiments with rat models also confirmed exosome-delivered α-syn inhibited liver cancer. These findings illustrate the important role of PD-associated protein α-syninhibiting hepatoma by exosome delivery, suggesting a new mechanism underlying the link between these two diseases and therapeutics of liver cancer.

Activation of neuronal NADPH oxidase NOX2 promotes inflammatory neurodegeneration.

Strong evidence indicates critical roles of NADPH oxidase (a key superoxide-producing enzyme complex during inflammation) in activated microglia for mediating neuroinflammation and neurodegeneration. However, little is known about roles of neuronal NADPH oxidase in neurodegenerative diseases. This study aimed to investigate expression patterns, regulatory mechanisms and pathological roles of neuronal NADPH oxidase in inflammation-associated neurodegeneration. The results showed persistent upregulation of NOX2 (gp91phox; the catalytic subunit of NADPH oxidase) in both microglia and neurons in a chronic mouse model of Parkinson's disease (PD) with intraperitoneal LPS injection and LPS-treated midbrain neuron-glia cultures (a cellular model of PD). Notably, NOX2 was found for the first time to exhibit a progressive and persistent upregulation in neurons during chronic neuroinflammation. While primary neurons and N27 neuronal cells displayed basal expression of NOX1, NOX2 and NOX4, significant upregulation only occurred in NOX2 but not NOX1 or NOX4 under inflammatory conditions. Persistent NOX2 upregulation was associated with functional outcomes of oxidative stress including increased ROS production and lipid peroxidation. Neuronal NOX2 activation displayed membrane translocation of cytosolic p47phox subunit and was inhibited by apocynin and diphenyleneiodonium chloride (two widely-used NADPH oxidase inhibitors). Importantly, neuronal ROS production, mitochondrial dysfunction and degeneration induced by inflammatory mediators in microglia-derived conditional medium were blocked by pharmacological inhibition of neuronal NOX2. Furthermore, specific deletion of neuronal NOX2 prevented LPS-elicited dopaminergic neurodegeneration in neuron-microglia co-cultures separately grown in the transwell system. The attenuation of inflammation-elicited upregulation of NOX2 in neuron-enriched and neuron-glia cultures by ROS scavenger N-acetylcysteine indicated a positive feedback mechanism between excessive ROS production and NOX2 upregulation. Collectively, our findings uncovered crucial contribution of neuronal NOX2 upregulation and activation to chronic neuroinflammation and inflammation-related neurodegeneration. This study reinforced the importance of developing NADPH oxidase-targeting therapeutics for neurodegenerative diseases.

Progesterone exerts a neuroprotective action in a Parkinson's disease human cell model through membrane progesterone receptor α (mPRα/PAQR7).

Parkinson's disease (PD) is the second most common neurodegenerative disease worldwide, and current treatment options are unsatisfactory on the long term. Several studies suggest a potential neuroprotective action by female hormones, especially estrogens. The potential role of progestogens, however, is less defined, and no studies have investigated the potential involvement of membrane progesterone receptors (mPRs). In the present study, the putative neuroprotective role for mPRs was investigated in SH-SY5Y cells, using two established pharmacological treatments for cellular PD models, 6-hydroxydopamine (6-OHDA) and 1-methyl-4-phenylpyridinium (MPP+). Our results show that both the physiologic agonist progesterone and the specific mPR agonist Org OD 02-0 were effective in reducing SH-SY5Y cell death induced by 6-OHDA and MPP+, whereas the nuclear PR agonist promegestone (R5020) and the GABAA receptor agonist muscimol were ineffective. Experiments performed with gene silencing technology and selective pharmacological agonists showed that mPRα is the isoform responsible for the neuroprotective effects we observed. Further experiments showed that the PI3K-AKT and MAP kinase signaling pathways are involved in the mPRα-mediated progestogen neuroprotective action in SH-SY5Y cells. These findings suggest that mPRα could play a neuroprotective role in PD pathology and may be a promising target for the development of therapeutic strategies for PD prevention or management.

Upregulation of Formaldehyde in Parkinson's Disease Found by a Near-Infrared Lysosome-Targeted Fluorescent Probe.

Parkinson's disease (PD) is one of the major neurodegenerative diseases caused by complex pathological processes. As a signal molecule, formaldehyde is closely linked to nervous systems, but the relationship between PD and formaldehyde levels remains largely unclear. We speculated that formaldehyde might be a potential biomarker for PD. To prove it, we constructed the first near-infrared (NIR) lysosome-targeted formaldehyde fluorescent probe (named NIR-Lyso-FA) to explore the relationship between formaldehyde and PD. The novel fluorescent probe achieves formaldehyde detection in vitro and in vivo, thanks to its excellent properties such as NIR emission, large Stokes shift, and fast response to formaldehyde. Crucially, utilizing the novel probe NIR-Lyso-FA, formaldehyde overexpression was discovered for the first time in cellular, zebrafish, and mouse PD models, supporting our guess that formaldehyde can function as a possible biomarker for PD. We anticipate that this finding will offer insightful information for PD pathophysiology, diagnosis, medication development, and treatment.

The role of the endolysosomal pathway in α-synuclein pathogenesis in Parkinson's disease.

Parkinson's disease (PD) is a chronic neurodegenerative disease that is characterized by a loss of dopaminergic neurons in the substantia nigra pars compacta of the midbrain (SNpc). Extensive studies into genetic and cellular models of PD implicate protein trafficking as a prominent contributor to the death of these dopaminergic neurons. Considerable evidence also suggests the involvement of α-synuclein as a central component of the characteristic cell death in PD and it is a major structural constituent of proteinaceous inclusion bodies (Lewy bodies; LB). α-synuclein research has been a vital part of PD research in recent years, with newly discovered evidence suggesting that α-synuclein can propagate through the brain via prion-like mechanisms. Healthy cells can internalize toxic α-synuclein species and seed endogenous α-synuclein to form large, pathogenic aggregates and form LBs. A better understanding of how α-synuclein can propagate, enter and be cleared from the cell is vital for therapeutic strategies.