4-Oxo-2-Nonenal- and Agitation-Induced Aggregates of α-Synuclein and Phosphorylated α-Synuclein with Distinct Biophysical Properties and Biomedical Applications.

α-Synuclein (α-syn) can form oligomers, protofibrils, and fibrils, which are associated with the pathogenesis of Parkinson's disease and other synucleinopathies. Both the lipid peroxidation product 4-oxo-2-nonenal (ONE) and agitation can induce aggregation of α-syn and phosphorylated α-syn. Thus, clarification of the characteristics of different α-syn species could help to select suitable aggregates for diagnosis and elucidate the pathogenesis of diseases. Here, we characterized ONE-induced wild-type (WT) α-syn aggregates (OW), ONE-induced phosphorylated α-syn (p-α-syn) aggregates (OP), agitation-induced α-syn preformed fibrils (PFF), and agitation-induced p-α-syn preformed fibrils (pPFF). Thioflavin T (ThT) dying demonstrated that OW and OP had fewer fibrils than the PFF and pPFF. Transmission electron microscopy revealed that the lengths of PFF and pPFF were similar, but the diameters differed. OW and OP had more compact structures than PFF and pPFF. Aggregation of p-α-syn was significantly faster than WT α-syn. Furthermore, OW and OP were more sodium dodecyl sulfate-stable and proteinase K-resistant, suggesting greater stability and compactness, while aggregates of PFF and pPFF were more sensitive to proteinase K treatment. Both ONE- and agitation-induced aggregates were cytotoxic when added exogenously to SH-SY5Y cells with increasing incubation times, but the agitation-induced aggregates caused cell toxicity in a shorter time and more p-α-syn inclusions. Similarly, p-proteins were more cytotoxic than non-p-proteins. Finally, all four aggregates were used as standard antigens to establish sandwich enzyme-linked immunosorbent assay (ELISA). The results showed that the recognition efficiency of OW and OP was more sensitive than that of PFF and pPFF. The OW- and OP-specific ELISA for detection of p-α-syn and α-syn in plasma samples of Thy1-α-syn transgenic mice showed that the content of aggregates could reflect the extent of disease. ONE and agitation induced the formation of α-syn aggregates with distinct biophysical properties and biomedical applications.

Plasma exosomes impair microglial degradation of α-synuclein through V-ATPase subunit V1G1.

INTRODUCTION: Microglia are the main phagocytes in the brain and can induce neuroinflammation. Moreover, they are critical to alpha-synuclein (α-syn) aggregation and propagation. Plasma exosomes derived from patients diagnosed with Parkinson's disease (PD-exo) reportedly evoked α-syn aggregation and inflammation in microglia. In turn, microglia internalized and released exosomal α-syn, enhancing α-syn propagation. However, the specific mechanism through which PD-exo influences α-syn degradation remains unknown. METHODS: Exosomes were extracted from the plasma of patients with PD by differential ultracentrifugation, analyzed using electron microscopy (EM) and nanoparticle flow cytometry, and stereotaxically injected into the unilateral striatum of the mice. Transmission EM was employed to visualize lysosomes and autophagosomes in BV2 cells, and lysosome pH was measured with LysoSensor Yellow/Blue DND-160. Cathepsin B and D, lysosomal-associated membrane protein 1 (LAMP1), ATP6V1G1, tumor susceptibility gene 101 protein, calnexin, α-syn, ionized calcium binding adaptor molecule 1, and NLR family pyrin domain containing 3 were evaluated using quantitative polymerase chain reaction or western blotting, and α-syn, LAMP1, and ATP6V1G1 were also observed by immunofluorescence. Small interfering ribonucleic acid against V1G1 was transfected into BV2 cells and primary microglia using Lipofectamine® 3000. A PD mouse model was established via injection with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) into mice. A lentiviral-mediated strategy to overexpress ATP6V1G1 in the brain of MPTP-treated mice was employed. Motor coordination was assessed using rotarod and pole tests, and neurodegeneration in the mouse substantia nigra and striatum tissues was determined using immunofluorescence histochemical and western blotting of tyrosine hydroxylase. RESULTS: PD-exo decreased the expression of V1G1, responsible for the acidification of intra- and extracellular milieu. This impairment of lysosomal acidification resulted in the accumulation of abnormally swollen lysosomes and decreased lysosomal enzyme activities, impairing lysosomal protein degradation and causing α-syn accumulation. Additionally, V1G1 overexpression conferred the mice neuroprotection during MPTP exposure. CONCLUSION: Pathogenic protein accumulation is a key feature of PD, and compromised V-type ATPase dysfunction might participate in PD pathogenesis. Moreover, V1G1 overexpression protects against neuronal toxicity in an MPTP-based PD mouse model, which may provide opportunities to develop novel therapeutic interventions for PD treatment.

Adenosine A2A Receptor Blockade Provides More Effective Benefits at the Onset Rather than after Overt Neurodegeneration in a Rat Model of Parkinson's Disease.

Adenosine A2A receptor (A2AR) antagonists are the leading nondopaminergic therapy to manage Parkinson's disease (PD) since they afford both motor benefits and neuroprotection. PD begins with a synaptic dysfunction and damage in the striatum evolving to an overt neuronal damage of dopaminergic neurons in the substantia nigra. We tested if A2AR antagonists are equally effective in controlling these two degenerative processes. We used a slow intracerebroventricular infusion of the toxin MPP+ in male rats for 15 days, which caused an initial loss of synaptic markers in the striatum within 10 days, followed by a neuronal loss in the substantia nigra within 30 days. Interestingly, the initial loss of striatal nerve terminals involved a loss of both dopaminergic and glutamatergic synaptic markers, while GABAergic markers were preserved. The daily administration of the A2AR antagonist SCH58261 (0.1 mg/kg, i.p.) in the first 10 days after MPP+ infusion markedly attenuated both the initial loss of striatal synaptic markers and the subsequent loss of nigra dopaminergic neurons. Strikingly, the administration of SCH58261 (0.1 mg/kg, i.p. for 10 days) starting 20 days after MPP+ infusion was less efficacious to attenuate the loss of nigra dopaminergic neurons. This prominent A2AR-mediated control of synaptotoxicity was directly confirmed by showing that the MPTP-induced dysfunction (MTT assay) and damage (lactate dehydrogenase release assay) of striatal synaptosomes were prevented by 50 nM SCH58261. This suggests that A2AR antagonists may be more effective to counteract the onset rather than the evolution of PD pathology.

RVG29 Peptide-Modified Exosomes Loaded with Mir-133b Mediate the RhoA-ROCK Pathway to Improve Motor and Neurological Symptoms in Parkinson's Disease.

Parkinson's disease (PD) is the second most common neurodegenerative disorder worldwide. Drug delivery to the brain through the blood-brain barrier (BBB) is a significant challenge in PD treatment. Exosomes, which can efficiently traverse the BBB, which many drugs cannot penetrate, are ideal natural carriers for drug delivery. In this study, the BBB shuttle peptide was modified on the exosome surfaces. Three types of exosomes were constructed, each modified with a distinct peptide (RVG29, TAT, or Ang2) and loaded with miR-133b. The safety and brain-targeting capabilities of these peptide-modified exosomes were then evaluated. Finally, the mechanism by which RVG29-Exo-133b regulates the RhoA-ROCK signaling pathway was investigated. The findings indicate that the three peptide-modified exosomes were adequately tolerated, safe, and effectively assimilated in vivo and ex vivo, with RVG29 exhibiting superior targeting to the brain. Furthermore, RVG29-Exo-133b decreased the phosphorylation level of the Tau protein by targeting the RhoA-ROCK signaling pathway. It also enhanced the motor function in mice with PD, thereby reducing the degree of depression, improving dopaminergic neuron function, and attenuating 6-OHDA-induced nerve damage. In this study, we developed a stable drug delivery mechanism that targets the intracerebral region using exosomes. Furthermore, a novel strategy was developed to manage PD and can potentially serve as a preclinical basis for utilizing exosomes in the diagnosis and treatment of neurodegenerative conditions.

Effects of electroacupuncture on Sirt3/NLRP3/GSDMD signaling pathway in the substantia nigra of midbrain of rats with Parkinson's disease. / ç”µé’ˆå¯¹å¸•é‡‘æ£®ç— å¤§é¼ ä¸­è„‘é»‘è´¨Sirt3/NLRP3/GSDMD信号通路的影响.

OBJECTIVES: To observe the effects on tyrosine hydroxylase (TH), α-synaptic nucleoprotein (α-syn), sirtuin 3 (Sirt3), NOD-like receptor 3 (NLRP3) and gasdermin-D (GSDMD) in the substantia nigra of midbrain after electroacupuncture (EA) at "Fengfu"(GV16), "Taichong" (LR3) and "Zusanli" (ST36) in rats of Parkinson's disease (PD), so as to explore the mechanism of EA in treatment of PD. METHODS: SD rats were randomly divided into control, model and EA groups, with 10 rats in each group. The PD model was established by injecting rotenone into the neck and back, lasting 28 days. In the EA group, EA was applied to GV16, LR3 and ST36, 30 min each time, once daily, consecutively for 28 days. The open-field test was adopted to detect the total distance of autonomic movement of rats, and the pole climbing test was used to detect the body coordination ability of rats. In the substania nigra of midbrain, the positive expression of TH was determined using immunohistochemistry, the mRNA expression levels of α - syn, Sirt3, NLRP3 and GSDMD were detected by quantitative real-time fluorescence PCR, and the protein expression levels of NLRP3, apoptosis-associated speck-like protein containing a caspase-recruitment domain (ASC) and cysteinyl aspartate specific proteinase (Caspase)-1 were detected by Western blot. RESULTS: Compared with the control group, the total distance of autonomous movement was decreased (P<0.01) in the model group, and the score of pole climbing experiment was increased (P<0.01)；in the midbrain substantia nigra the positive expression of TH was decreased (P<0.01)；the mRNA expression level of Sirt3 was decreased (P<0.01), and those of α-syn, NLRP3 and GSDMD were increased (P<0.01)；while the protein expression levels of NLRP3, ASC and Caspase-1 were increased (P<0.01). When compared with the model group, the total distance of autonomous movement in open field experiment was increased (P<0.01) in the EA group and the score of pole climbing experiment was lower (P<0.05)；in the midbrain substantia nigra the positive expression of TH was increased (P<0.01)；the mRNA expression level of Sirt3 in the midbrain substantia nigra was increased (P<0.01), and those of α-syn, NLRP3 and GSDMD were reduced (P<0.01)；while the protein expression levels of NLRP3, ASC and Caspase-1 decreased (P<0.01, P<0.05). CONCLUSIONS: EA at "GV16" "LR3" and "ST36" can repair the neuronal injury, clear the abnormal accumulation of α-syn in the substania nigra of midbrain, and ameliorate mitochondrial damage in PD rats, which may be obtained by regulating Sirt3/NLRP3/GSDMD signaling pathway, so as to delay the occurrence and development of Parkinson's disease.

Real-Time Monitoring of Tyrosine Hydroxylase Activity with a Ratiometric Fluorescent Probe.

Parkinson's disease (PD) represents the second most widespread neurodegenerative disease, and early monitoring and diagnosis are urgent at present. Tyrosine hydroxylase (TH) is a key enzyme for producing dopamine, the levels of which can serve as an indicator for assessing the severity and progression of PD. This renders the specific detection and visualization of TH a strategically vital way to meet the above demands. However, a fluorescent probe for TH monitoring is still missing. Herein, three rationally designed wash-free ratiometric fluorescent probes were proposed. Among them, TH-1 exhibited ideal photophysical properties and specific dual-channel bioimaging of TH activity in SH-SY5Y nerve cells. Moreover, the probe allowed for in vivo imaging of TH activity in zebrafish brain and living striatal slices of mice. Overall, the ratiometric fluorescent probe TH-1 could serve as a potential tool for real-time monitoring of PD in complex biosystems.

[Microglia differential genes and their functions in paraquat-induced Parkinson's disease-like in mice's brains based on single-cell RNA sequencing].

Objective: To analyze the differential genes and related signaling pathways of microglia subpopulations in Parkinson's disease (PD) -like mouse brains induced by paraquat (PQ) based on single-cell RNA sequencing, and provide clues to elucidate the mechanism of PQ-induced PD-like changes in the brain of animals. Methods: In September 2021, six male 6-week-old C57BL/6 mice were randomly divided into control group and experimental group (three mice in each group) . The mice were injected with saline, 10.0 mg/kg PQ intraperitoneally, once every three days, and 10 consecutive injections were used for modeling. After infection, the brains of mice were taken and 10×Genomics single-cell RNA sequencing was performed. Microglia subpopulations were screened based on gene expression characteristics, and Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed. The differential genes of microglia subpopulations between the experimental group and control group were further screened, and functional enrichment analysis was performed using bioinformatics tools. Mouse microglia (BV2 cells) were treated with 0, 60, 90 µmol/L PQ solution, respectively. And real-time fluorescence quantitative PCR experiments were conducted to validate the expressions of differential genes hexokinase 2 (Hk2) , ATPase H+ Transporting V0 Subunit B (Atp6v0b) and Neuregulin 1 (Nrg1) . Results: Cluster 7 and Cluster 20 were identified as microglia subpopulations based on the signature genes inositol polyphosphate-5-phosphatase d, Inpp5d (Inpp5d) and transforming growth factor beta receptor 1 (Tgfbr1) , and they reflected the microglia-activated M2 phenotype. The bioinformatics analysis showed that the characteristic genes of identified microglia subpopulations were enriched in endocytosis. In terms of molecular function, it mainly enriched in transmembrane receptor protein kinase activity and cytokine binding. The up-regulated genes of Cluster 7 were mainly enriched in lysosomal pathway, endocytosis pathway, and down-regulated genes were mainly enriched in neurodegenerative disease and other signaling pathways. The up-regulated genes of Cluster 20 were mainly enriched in signaling pathways related to PD, and down-regulated genes were mainly enriched in cyclic adenosine 3', 5'-monophosphate (cAMP) signaling pathways, neurological development, synaptic function and other signaling pathways. The results of real-time fluorescence quantitative PCR showed that the expressions of Hk2 mRNA and Atp6v0b mRNA increased and the expression of Nrg1 mRNA decreased in the 90 µmol/L PQ-treated BV2 cells compared with the 0 µmol/L, and the differences were statistically significant (P<0.05) . Conclusion: Microglia are activated in the PQ-induced PD-like mouse model and polarized toward the M2 phenotype. And their functions are associated with lysosomal (endocytosis) , synaptic functions and the regulation of PD-related pathways.

In vitro inhibition of α-Synuclein aggregation and disaggregation of preformed fibers by polyphenol hybrids with 2-conjugated benzothiazole.

The misfolding and aggregation of α-Syn play a pivotal role in connecting diverse pathological pathways in Parkinson's disease (PD). Preserving α-Syn proteostasis and functionality by inhibiting its aggregation or disaggregating existing aggregates using suitable inhibitors represents a promising strategy for PD prevention and treatment. In this study, a series of benzothiazole-polyphenol hybrids was designed and synthesized. Three identified compounds exhibited notable inhibitory activities against α-Syn aggregation in vitro, with IC50 values in the low micromolar range. These inhibitors demonstrated sustained inhibitory effects throughout the entire aggregation process, stabilizing α-Syn proteostasis conformation. Moreover, the compounds effectively disintegrated preformed α-Syn oligomers and fibers, potentially by binding to specific domains within the fibers, inducing fibril instability, collapse, and ultimately resulting in smaller-sized aggregates and monomers. These findings offer valuable insights into the therapeutic potential of polyphenol hybrids with 2-conjugated benzothiazole targeting α-Syn aggregation in the treatment of PD.

Therapeutic role of PTEN in tissue regeneration for management of neurological disorders: stem cell behaviors to an in-depth review.

Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) represents the initial tumor suppressor gene identified to possess phosphatase activity, governing various cellular processes including cell cycle regulation, migration, metabolic pathways, autophagy, oxidative stress response, and cellular senescence. Current evidence suggests that PTEN is critical for stem cell maintenance, self-renewal, migration, lineage commitment, and differentiation. Based on the latest available evidence, we provide a comprehensive overview of the mechanisms by which PTEN regulates activities of different stem cell populations and influences neurological disorders, encompassing autism, stroke, spinal cord injury, traumatic brain injury, Alzheimer's disease and Parkinson's disease. This review aims to elucidate the therapeutic impacts and mechanisms of PTEN in relation to neurogenesis or the stem cell niche across a range of neurological disorders, offering a foundation for innovative therapeutic approaches aimed at tissue repair and regeneration in neurological disorders. This review unravels novel therapeutic strategies for tissue restoration and regeneration in neurological disorders based on the regulatory mechanisms of PTEN on neurogenesis and the stem cell niche.

Single cell analysis reveals the roles and regulatory mechanisms of type-I interferons in Parkinson's disease.

The pathogenesis of Parkinson's disease (PD) is strongly associated with neuroinflammation, and type I interferons (IFN-I) play a crucial role in regulating immune and inflammatory responses. However, the specific features of IFN in different cell types and the underlying mechanisms of PD have yet to be fully described. In this study, we analyzed the GSE157783 dataset, which includes 39,024 single-cell RNA sequencing results for five PD patients and six healthy controls from the Gene Expression Omnibus database. After cell type annotation, we intersected differentially expressed genes in each cell subcluster with genes collected in The Interferome database to generate an IFN-I-stimulated gene set (ISGs). Based on this gene set, we used the R package AUCell to score each cell, representing the IFN-I activity. Additionally, we performed monocle trajectory analysis, and single-cell regulatory network inference and clustering (SCENIC) to uncover the underlying mechanisms. In silico gene perturbation and subsequent experiments confirm NFATc2 regulation of type I interferon response and neuroinflammation. Our analysis revealed that microglia, endothelial cells, and pericytes exhibited the highest activity of IFN-I. Furthermore, single-cell trajectory detection demonstrated that microglia in the midbrain of PD patients were in a pro-inflammatory activation state, which was validated in the 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD mouse model as well. We identified transcription factors NFATc2, which was significantly up-regulated and involved in the expression of ISGs and activation of microglia in PD. In the 1-Methyl-4-phenylpyridinium (MPP+)-induced BV2 cell model, the suppression of NFATc2 resulted in a reduction in IFN-ß levels, impeding the phosphorylation of STAT1, and attenuating the activation of the NF-κB pathway. Furthermore, the downregulation of NFATc2 mitigated the detrimental effects on SH-SY5Y cells co-cultured in conditioned medium. Our study highlights the critical role of microglia in type I interferon responses in PD. Additionally, we identified transcription factors NFATc2 as key regulators of aberrant type I interferon responses and microglial pro-inflammatory activation in PD. These findings provide new insights into the pathogenesis of PD and may have implications for the development of novel therapeutic strategies.

A High-Throughput Screening of a Natural Products Library for Mitochondria Modulators.

Mitochondria, the energy hubs of the cell, are progressively becoming attractive targets in the search for potent therapeutics against neurodegenerative diseases. The pivotal role of mitochondrial dysfunction in the pathogenesis of various diseases, including Parkinson's disease (PD), underscores the urgency of discovering novel therapeutic strategies. Given the limitations associated with available treatments for mitochondrial dysfunction-associated diseases, the search for new potent alternatives has become imperative. In this report, we embarked on an extensive screening of 4224 fractions from 384 Australian marine organisms and plant samples to identify natural products with protective effects on mitochondria. Our initial screening using PD patient-sourced olfactory neurosphere-derived (hONS) cells with rotenone as a mitochondria stressor resulted in 108 promising fractions from 11 different biota. To further assess the potency and efficacy of these hits, the 11 biotas were subjected to a subsequent round of screening on human neuroblastoma (SH-SY5Y) cells, using 6-hydroxydopamine to induce mitochondrial stress, complemented by a mitochondrial membrane potential assay. This rigorous process yielded 35 active fractions from eight biotas. Advanced analysis using an orbit trap mass spectrophotometer facilitated the identification of the molecular constituents of the most active fraction from each of the eight biotas. This meticulous approach led to the discovery of 57 unique compounds, among which 12 were previously recognized for their mitoprotective effects. Our findings highlight the vast potential of natural products derived from Australian marine organisms and plants in the quest for innovative treatments targeting mitochondrial dysfunction in neurodegenerative diseases.

Dopamine- and Grape-Seed-Extract-Loaded Solid Lipid Nanoparticles: Interaction Studies between Particles and Differentiated SH-SY5Y Neuronal Cell Model of Parkinson's Disease.

Parkinson's disease (PD) is a prevalent neurodegenerative disorder, primarily associated with dopaminergic neuron depletion in the Substantia Nigra. Current treatment focuses on compensating for dopamine (DA) deficiency, but the blood-brain barrier (BBB) poses challenges for effective drug delivery. Using differentiated SH-SY5Y cells, we investigated the co-administration of DA and the antioxidant Grape Seed Extract (GSE) to study the cytobiocompability, the cytoprotection against the neurotoxin Rotenone, and their antioxidant effects. For this purpose, two solid lipid nanoparticle (SLN) formulations, DA-co-GSE-SLNs and GSE-ads-DA-SLNs, were synthesized. Such SLNs showed mean particle sizes in the range of 187-297 nm, zeta potential values in the range of -4.1--9.7 mV, and DA association efficiencies ranging from 35 to 82%, according to the formulation examined. The results showed that DA/GSE-SLNs did not alter cell viability and had a cytoprotective effect against Rotenone-induced toxicity and oxidative stress. In addition, this study also focused on the evaluation of Alpha-synuclein (aS) levels; SLNs showed the potential to modulate the Rotenone-mediated increase in aS levels. In conclusion, our study investigated the potential of SLNs as a delivery system for addressing PD, also representing a promising approach for enhanced delivery of pharmaceutical and antioxidant molecules across the BBB.

Vincamine alleviates brain injury by attenuating neuroinflammation and oxidative damage in a mouse model of Parkinson's disease through the NF-κB and Nrf2/HO-1 signaling pathways.

Parkinson's disease (PD) is a neurodegenerative disease featured by progressive loss of nigrostriatal dopaminergic neurons, the etiology of which is associated with the existence of neuroinflammatory response and oxidative stress. Vincamine is an indole alkaloid that was reported to exhibit potent anti-inflammatory and antioxidant properties in many central and/or peripheral diseases. Nevertheless, the specific role of vincamine in PD development remains unknown. In our study, dopaminergic neuron loss was determined through immunohistochemistry staining and western blot analysis of tyrosine hydroxylase (TH) expression in the substantia nigra (SN) of PD mice. Reactive oxygen species (ROS) production and malondialdehyde (MDA), superoxide dismutase (SOD), and glutathione (GSH) levels were detected through DHE staining and commercially available kits to assess oxidative stress. Pro-inflammatory cytokine (TNF-α, IL-1ß, and IL-6) levels in the SN were measured via RT-qPCR and western blot analysis. Microglial and astrocyte activation was examined through immunofluorescence staining of Iba-1 (microglia marker) and GFAP (astrocyte marker) in the SN. The regulation of vincamine on the NF-κB and Nrf2/HO-1 pathway was estimated through western blot analysis. Our results showed that vincamine treatment decreased TNF-α, IL-1ß, and IL-6 mRNA and protein levels, reduced GFAP and Iba-1 expression, decreased ROS production and MDA level, and increased SOD activity and GSH level in the SN of PD mice. Mechanically, vincamine repressed the phosphorylation levels of p65, IKKß, and IκBα but enhanced the protein levels of Nrf2 and HO-1 in PD mice. Collectively, vincamine plays a neuroprotective role in PD mouse models by alleviating neuroinflammation and oxidative damage via suppressing the NF-κB pathway and activating the Nrf2/HO-1 pathway.

Macrophages and Natural Killers Degrade α-Synuclein Aggregates.

Amyloid oligomers and fibrils are protein aggregates that exert a high cell toxicity. Efficient degradation of these protein aggregates can minimize the spread and progression of neurodegeneration. In this study, we investigate the properties of natural killer (NK) cells and macrophages in the degradation of α-synuclein (α-Syn) aggregates grown in a lipid-free environment and in the presence of phosphatidylserine and cholesterol (PS/Cho), which are lipids that are directly associated with the onset and progression of Parkinson's disease. We found that both types of α-Syn aggregates were endocytosed by neurons, which caused strong damage to cell endosomes. Our results also indicated that PS/Cho vesicles drastically increased the toxicity of α-Syn fibrils formed in their presence compared to the toxicity of α-Syn aggregates grown in a lipid-free environment. Both NK cells and macrophages were able to degrade α-Syn and α-Syn/Cho monomers, oligomers, and fibrils. Quantitative analysis of protein degradation showed that macrophages demonstrated substantially more efficient internalization and degradation of amyloid aggregates in comparison to NK cells. We also found that amyloid aggregates induced the proliferation of macrophages and NK cells and significantly changed the expression of their cytokines and chemokines.

Mitochondrial complex I deficiency stratifies idiopathic Parkinson's disease.

Idiopathic Parkinson's disease (iPD) is believed to have a heterogeneous pathophysiology, but molecular disease subtypes have not been identified. Here, we show that iPD can be stratified according to the severity of neuronal respiratory complex I (CI) deficiency, and identify two emerging disease subtypes with distinct molecular and clinical profiles. The CI deficient (CI-PD) subtype accounts for approximately a fourth of all cases, and is characterized by anatomically widespread neuronal CI deficiency, a distinct cell type-specific gene expression profile, increased load of neuronal mtDNA deletions, and a predilection for non-tremor dominant motor phenotypes. In contrast, the non-CI deficient (nCI-PD) subtype exhibits no evidence of mitochondrial impairment outside the dopaminergic substantia nigra and has a predilection for a tremor dominant phenotype. These findings constitute a step towards resolving the biological heterogeneity of iPD with implications for both mechanistic understanding and treatment strategies.

Targeting NKAα1 to treat Parkinson's disease through inhibition of mitophagy-dependent ferroptosis.

Dysfunction of the Na+/K+-ATPase (NKA) has been documented in various neurodegenerative diseases, yet the specific role of NKAα1 in Parkinson's disease (PD) remains incompletely understood. In this investigation, we utilized NKAα1 haploinsufficiency (NKAα1+/-) mice to probe the influence of NKAα1 on dopaminergic (DA) neurodegeneration induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Our findings reveal that NKAα1+/- mice displayed a heightened loss of DA neurons and more pronounced motor dysfunction compared to the control group when exposed to MPTP. Intriguingly, this phenomenon coincided with the activation of ferroptosis and impaired mitophagy both in vivo and in vitro. To scrutinize the role and underlying mechanism of NKAα1 in PD, we employed DR-Ab, an antibody targeting the DR-region of the NKA α subunit. Our study demonstrates that the administration of DR-Ab effectively reinstated the membrane abundance of NKAα1, thereby mitigating MPTP-induced DA neuron loss and subsequent improvement in behavioral deficit. Mechanistically, DR-Ab heightened the formation of the surface NKAα1/SLC7A11 complex, inhibiting SLC7A11-dependent ferroptosis. Moreover, DR-Ab disrupted the cytosolic interaction between NKAα1 and Parkin, facilitating the translocation of Parkin to mitochondria and enhancing the process of mitophagy. In conclusion, this study establishes NKAα1 as a key regulator of ferroptosis and mitophagy, identifying its DR-region as a promising therapeutic target for PD.

Long-term benefits of hematopoietic stem cell-based macrophage/microglia delivery of GDNF to the CNS in a mouse model of Parkinson's disease.

Glial cell line-derived neurotrophic factor (GDNF) protects dopaminergic neurons in various models of Parkinson's disease (PD). Cell-based GDNF gene delivery mitigates neurodegeneration and improves both motor and non-motor functions in PD mice. As PD is a chronic condition, this study aims to investigate the long-lasting benefits of hematopoietic stem cell (HSC)-based macrophage/microglia-mediated CNS GDNF (MMC-GDNF) delivery in an MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) mouse model. The results indicate that GDNF treatment effectively ameliorated MPTP-induced motor deficits for up to 12 months, which coincided with the protection of nigral dopaminergic neurons and their striatal terminals. Also, the HSC-derived macrophages/microglia were recruited selectively to the neurodegenerative areas of the substantia nigra. The therapeutic benefits appear to involve two mechanisms: (1) macrophage/microglia release of GDNF-containing exosomes, which are transferred to target neurons, and (2) direct release of GDNF by macrophage/microglia, which diffuses to target neurons. Furthermore, the study found that plasma GDNF levels were significantly increased from baseline and remained stable over time, potentially serving as a convenient biomarker for future clinical trials. Notably, no weight loss, altered food intake, cerebellar pathology, or other adverse effects were observed. Overall, this study provides compelling evidence for the long-term therapeutic efficacy and safety of HSC-based MMC-GDNF delivery in the treatment of PD.

LncRNA NEAT1 promotes MPP+ induced injury of PC12 cells and accelerates the progression of Parkinson's disease in mice through FUS mediated inhibition of PI3K/AKT/mTOR signalling pathway.

Long noncoding RNA nuclear-enriched abundant transcript 1 (NEAT1) is involved in the progression of Parkinson's disease (PD), but the specific regulatory role needs further exploration. This study showed that the expression of NEAT1 was upregulated in the cerebrospinal fluid (CSF) and peripheral blood of patients with different stages of PD. 1-Methyl-4-phenylpyridine (MPP)-treated PC 12 cells were transfected with si-NEAT1, and MPP treatment promoted cell apoptosis, oxidative stress and inflammatory factor secretion. Si-NEAT1 reversed the effects of MPP. NEAT1 silencing eliminated the effect of MPP on the protein expression levels of LC3-II and p62/SQSTM1. By using an online bioinformatics database, Fused in Sarcoma (FUS) was confirmed to be an RNA binding protein of NEAT1, and it was highly expressed in the CSF and peripheral blood of patients with PD. Si-FUS was transfected into MPP-treated PC 12 cells to detect cell apoptosis, oxidative stress, inflammatory factor secretion and autophagy, and the results were the same as those of transfection of si-NEAT1. Furthermore, MPP treatment reduced the phosphorylation levels of PI3K, Akt and mTOR, whereas si-FUS reversed the effects of MPP. In vivo, compared with the model group, the PD mice showed reduced NEAT1 and FUS expression levels and activated PI3K pathway after being injected with si-NEAT1. The brain tissue of NEAT1-silenced PD mice had decreased inflammatory infiltration and apoptosis and increased neurological scores. In conclusion, NEAT1 is involved in PD progression through FUS-mediated inhibition of the PI3K/AKT/mTOR signalling pathway.

α-synuclein regulates Cyclin D1 to promote abnormal initiation of the cell cycle and induce apoptosis in dopamine neurons.

The etiology of Parkinson's disease (PD) is characterized by the death of dopamine neurons in the substantia nigra pars compacta, while misfolding and abnormal aggregation of α-synuclein (α-syn) are core pathological features. Previous studies have suggested that damage to dopamine neurons may be related to cell cycle dysregulation, but the specific mechanisms remain unclear. In this study, a PD mouse model was induced by stereotactic injection of α-syn into the nucleus, and treated with the cell cycle inhibitor, roscovitine (Rosc). The results demonstrated that Rosc improved behavioral disorders caused by α-syn, increased TH protein expression, inhibited α-syn and p-α-syn protein expression, and reduced the expression levels of G1/S phase cell cycle genes Cyclin D1, Cyclin E, CDK2, CDK4, E2F and pRB. Additionally, Rosc decreased Bax and Caspase-3 expression caused by α-syn, while increasing Bcl-2 protein expression. Meanwhile, we observed that α-syn can influence neuronal cell autophagy by decreasing the expression level of Beclin 1 and increasing the expression level of P62. However, Rosc can improve this phenomenon. In a cell model induced by α-syn in dopamine neuron injury cells, knockdown of Cyclin D1 led to similar results as those observed in animal experiments: Knocking down Cyclin D1 improved the abnormal initiation of the cell cycle caused by α-syn and regulated cellular autophagy, resulting in a reduction of apoptosis in dopamine neurons. In summary, exogenous α-syn can lead to the accumulation of α-syn and phosphorylated α-syn in dopamine neurons, increase key factors of the G1/S phase cell cycle such as Cyclin D1, and regulate downstream related indicators, causing the cell cycle to restart and leading to apoptosis of dopamine neurons. This exacerbates PD symptoms. However, knockdown of Cyclin D1 inhibits the progression of the cell cycle and can reverse this situation. These findings suggest that a Cyclin D inhibitor may be a novel therapeutic target for treating PD.

Nicotinic Acetylcholine Receptors in Glial Cells as Molecular Target for Parkinson's Disease.

Parkinson's disease (PD) is a progressive neurodegenerative disease characterized by resting tremor, bradykinesia, rigidity, and postural instability that also includes non-motor symptoms such as mood dysregulation. Dopamine (DA) is the primary neurotransmitter involved in this disease, but cholinergic imbalance has also been implicated. Current intervention in PD is focused on replenishing central DA, which provides remarkable temporary symptomatic relief but does not address neuronal loss and the progression of the disease. It has been well established that neuronal nicotinic cholinergic receptors (nAChRs) can regulate DA release and that nicotine itself may have neuroprotective effects. Recent studies identified nAChRs in nonneuronal cell types, including glial cells, where they may regulate inflammatory responses. Given the crucial role of neuroinflammation in dopaminergic degeneration and the involvement of microglia and astrocytes in this response, glial nAChRs may provide a novel therapeutic target in the prevention and/or treatment of PD. In this review, following a brief discussion of PD, we focus on the role of glial cells and, specifically, their nAChRs in PD pathology and/or treatment.