Autophagy in Parkinson's Disease

Current Perspective and Mechanistic Insights on α-Hederin for the Prevention and Treatment of Several Noncommunicable Diseases

α-Hederin, a naturally occurring compound found in various plant sources, has remarkable properties and therapeutic potential for human health. One notable attribute is its potent anti-inflammatory activity, such as in arthritis, asthma, and inflammatory bowel disease. In addition, it exhibits notable antioxidant effects implicated in the development of chronic diseases, including cardiovascular disorders and certain types of cancer. According to research, it may limit the growth and proliferation of cancer cells, making it a possible candidate for future cancer treatments. Moreover, it is a promising neuroprotective agent and enhances cognitive function, suggesting its potential in the treatment of neurodegenerative illnesses like Alzheimer's and Parkinson's disease. The multifaceted benefits of α-hederin make it an intriguing compound with significant therapeutic implications. As research progresses, exploring its mechanisms of action and clinical applications is warranted. Harnessing the potential of α-hederin may pave the way for innovative treatment strategies and improved outcomes in the battle against various chronic diseases.

Altered Mitochondrial Bioenergetics and Calcium Kinetics in Young-Onset PLA2G6 Parkinson's Disease iPSCs

Parkinson's disease (PD) has emerged as a multisystem disorder affecting multiple cellular and organellar systems in addition to the dopaminergic neurons. Disease-specific induced pluripotent stem cells (iPSCs) model early developmental changes and cellular perturbations that are otherwise inaccessible from clinical settings. Here, we report the early changes in patient-derived iPSCs carrying a homozygous recessive mutation, R741Q, in the PLA2G6 gene. A gene-edited R747W iPSC line mirrored these phenotypes, thus validating our initial findings. Bioenergetic dysfunction and hyperpolarization of mitochondrial membrane potentials were hallmarks of the PD iPSCs. Further, a concomitant increase in glycolytic activity indicated a possible compensation for mitochondrial respiration. Elevated basal reactive oxygen species (ROS) and decreased catalase expression were also observed in the disease iPSCs. No change in autophagy was detected. These inceptive changes could be potential targets for early intervention of prodromal PD in the absence of disease-modifying therapies. However, additional investigations are crucial to delineate the cause-effect relationships of these observations.

Modulation of autophagy by melatonin and its receptors: implications in brain disorders

Autophagy plays a crucial role in maintaining neuronal homeostasis and function, and its disruption is linked to various brain diseases. Melatonin, an endogenous hormone that primarily acts through MT1 and MT2 receptors, regulates autophagy via multiple pathways. Growing evidence indicates that melatonin's ability to modulate autophagy provides therapeutic and preventive benefits in brain disorders, including neurodegenerative and affective diseases. In this review, we summarize the key mechanisms by which melatonin affects autophagy and explore its therapeutic potential in the treatment of brain disorders.

Beyond amyloid plaque, targeting α-synuclein in Alzheimer disease: The battle continues

Alzheimer's disease (AD) is the most common neurodegenerative brain disease and represents the most frequent type of dementia characterized by cognitive impairment and amnesia. AD neuropathology is connected to the development of synaptic dysfunction and loss of synaptic homeostasis due to an imbalance in the production and clearance of β-amyloid (Aβ) and intracellular neurofibrillary tangles (NFTs). However, AD neuropathology is complex and may relate to the deposition of other misfolded proteins, such as alpha-synuclein (α-Syn). Of note, α-Syn, which is involved in the pathogenesis of Parkinson disease (PD) and Lewy body (LB) dementia, is also implicated in AD neuropathology. However, the potential role of α-Syn in AD neuropathology is elusive. Therefore, this review aims to discuss the pathological role of α-Syn in AD and how targeting α-Syn aggregates may be effective in treating AD.

The role of Apolipoprotein E4 on cognitive impairment in Parkinson's disease and Parkinsonisms

Cognitive impairment is a prevalent non-motor symptom of Parkinson's disease (PD), increasing the risk of dementia as the disease progresses. Despite its clinical significance, the etiology of cognitive impairment in PD remains unclear. Apolipoprotein E4 (APOE4), a well-known genetic risk factor of Alzheimer's disease, has been studied for its potential role in PD-related cognitive impairment. However, findings have been conflicting and thus inconclusive, highlighting a need to critically evaluate the current research. Several studies using neuroimaging modalities have explored the brains of individuals with PD and atypical parkinsonian disorders who have APOE4. Some of these studies have identified distinct neuropathological changes that have been previously reported to be associated with cognitive impairments in those with Parkinsonisms. Here, we review the role of APOE4 on cognitive impairment in PD and atypical Parkinsonisms using neuroimaging evidence. We will examine how APOE4 may contribute to pathological changes within the brain and its association with cognitive impairment.

α-Synuclein Iron-Responsive-Element RNA and Iron Regulatory Protein Affinity Is Specifically Reduced by Iron in Parkinson's Disease

α-Synuclein (α-Syn) is implicated in the pathophysiology of Parkinson's disease (PD) and plays a significant role in neuronal degeneration. Iron response proteins (IRPs) bind to iron response elements (IREs) found in the 5'-untranslated regions (5'-UTRs) of the messenger RNA that encode the α-Syn gene. This study used multi-spectroscopic approach techniques to investigate the impact of iron on α-Syn IRE RNA binding to IRP1. The formation of a stable complex between α-Syn RNA and IRP1 was suggested by fluorescence quenching results. Fluorescence measurements showed that α-Syn RNA and IRP1 had a strong interaction, with a binding constant (Ka) of 21.0 × 106 M-1 and 1:1 binding stoichiometry. About one binding site per IRP1 molecule was suggested by the α-Syn RNA binding. The Ka for α-Syn RNA•IRP1 with added Fe2+ (50 μM) was 6.4 μM-1. When Fe2+ was added, the Ka of α-Syn RNA•IRP1 was reduced by 3.3 times. These acquired Ka values were used to further understand the thermodynamic characteristics of α-Syn RNA•IRP1 interactions. The thermodynamic properties clearly suggested that α-Syn RNA binding to IRP1 was an entropy-favored and enthalpy-driven event, with significant negative ΔH and small positive ΔS. For α-Syn RNA•IRP1, the Gibbs free energy (ΔG) was -43.7 ± 2.7 kJ/mol, but in the presence of Fe2+, it was -36.3 ± 2.1 kJ/mol. These thermodynamic calculations indicated that hydrogen bonding as well as van der Waals interactions might help to stabilize the complex formation. Additionally, far-UV CD spectra verified α-Syn RNA•IRP1 complex formation, and α-Syn RNA and Fe2+ induce secondary structural alteration of IRP1. According to our findings, iron alters the hydrogen bonding in α-Syn RNA•IRP1 complexes and induces a structural change in IRP1. This suggests that iron selectively affects the thermodynamics of these RNA-protein interactions.

Ginsenosides Rg1, Rb1 and rare ginsenosides: Promising candidate agents for Parkinson's disease and Alzheimer's disease and network pharmacology analysis

Ginseng has been commonly used as a traditional Chinese medicine in Asian countries for thousands of years. Ginsenosides are the main pharmacologically active ingredients isolated from ginseng and have neuroprotective effects in the treatment of neurodegenerative disorders, such as Parkinson's disease (PD) and Alzheimer's disease (AD). To summarise and investigate the protective roles of ginsenosides and their underlying mechanisms in PD and AD, we used ''Ginsenoside", ''Parkinson's disease", ''Alzheimer's disease", ''anti-inflammatory", ''antioxidant", and ''apoptosis" as keywords to search and extract relevant literature information from scientific databases such as Elsevier, PubMed, and Google Scholar databases. In particular, we used network pharmacology to identify the potential targets of ginsenosides Rg1 and Rb1 in PD and AD. By analysing the existing research advances and network pharmacology results, we found that the neuroprotective effects of ginsenosides, primarily mediated through anti-inflammation, anti-apoptosis and anti-oxidative stress, etc, may be associated with the PI3K/Akt, BDNF/TrkB, MAPKs, NF-κB, Nrf2 and Wnt/β-catenin signalling pathways. This review systematically summarises the different roles and mechanisms of ginsenosides Rg1, Rb1, and rare ginsenosides in PD and AD and provides new strategies for the treatment of neurodegenerative disorders. Network pharmacology provides a new research paradigm for the treatment of PD and AD using Rg1 and Rb1.

Ginsenoside Rg1 ameliorates stress-exacerbated Parkinson's disease in mice by eliminating RTP801 and α-synuclein autophagic degradation obstacle

Emerging evidence shows that psychological stress promotes the progression of Parkinson's disease (PD) and the onset of dyskinesia in non-PD individuals, highlighting a potential avenue for therapeutic intervention. We previously reported that chronic restraint-induced psychological stress precipitated the onset of parkinsonism in 10-month-old transgenic mice expressing mutant human α-synuclein (αSyn) (hαSyn A53T). We refer to these as chronic stress-genetic susceptibility (CSGS) PD model mice. In this study we investigated whether ginsenoside Rg1, a principal compound in ginseng notable for soothing the mind, could alleviate PD deterioration induced by psychological stress. Ten-month-old transgenic hαSyn A53T mice were subjected to 4 weeks' restraint stress to simulate chronic stress conditions that worsen PD, meanwhile the mice were treated with Rg1 (40 mg· kg-1 ·d-1, i.g.), and followed by functional magnetic resonance imaging (fMRI) and a variety of neurobehavioral tests. We showed that treatment with Rg1 significantly alleviated both motor and non-motor symptoms associated with PD. Functional MRI revealed that Rg1 treatment enhanced connectivity between brain regions implicated in PD, and in vivo multi-channel electrophysiological assay showed improvements in dyskinesia-related electrical activity. In addition, Rg1 treatment significantly attenuated the degeneration of dopaminergic neurons and reduced the pathological aggregation of αSyn in the striatum and SNc. We revealed that Rg1 treatment selectively reduced the level of the stress-sensitive protein RTP801 in SNc under chronic stress conditions, without impacting the acute stress response. HPLC-MS/MS analysis coupled with site-directed mutation showed that Rg1 promoted the ubiquitination and subsequent degradation of RTP801 at residues K188 and K218, a process mediated by the Parkin RING2 domain. Utilizing αSyn A53T+; RTP801-/- mice, we confirmed the critical role of RTP801 in stress-aggravated PD and its necessity for Rg1's protective effects. Moreover, Rg1 alleviated obstacles in αSyn autophagic degradation by ameliorating the RTP801-TXNIP-mediated deficiency of ATP13A2. Collectively, our results suggest that ginsenoside Rg1 holds promise as a therapeutic choice for treating PD-sensitive individuals who especially experience high levels of stress and self-imposed expectations.

Melatonin attenuates MPP+-induced autophagy via heat shock protein in the Parkinson's disease mouse model

Background

This study investigates the protective properties of melatonin in an in vivo Parkinson's disease (PD) model, focusing on the underlying mechanisms involving heat shock proteins (HSPs).

Methods

Twelve adult male C57BL/6 mice were randomly divided into four groups (normal control, melatonin control, Parkinson's model, and melatonin treatment; n = 3 per group) and housed in a single cage. 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) was injected intraperitoneally in the Parkinson's model and treatment groups to establish a subacute PD model, while controls received saline. Limb motor ability was assessed 1 h after the final injection using behavioral tests, including the open field test to evaluate central zone entries and average movement. Dopamine transporter (DAT) expression in the striatum was analyzed by immunohistochemistry, and Western blot was used to measure autophagy proteins and HSP70 levels.

Results

The PD mouse model was successfully established through MPTP stimulation. Compared to the normal control group, the model group showed a significant reduction in the frequency of entering the central zone and average movement. The number of DAT-positive cells in the brain also decreased significantly. The expression levels of HSP70 and CDK5 were significantly lower, while the expression levels of LC3 II /LC3I and p62 increased significantly. In the MT treatment group, both the frequency of entering the central zone and the average movement were significantly higher compared to the model group. DAT-positive cells in the midbrain also increased significantly. The expression levels of HSP70 and CDK5 were significantly elevated, while the expression levels of LC3 II /LC3I and p62 protein were significantly decreased.

Conclusion

Melatonin exerts a protective effect against MPP+-induced damage to dopaminergic neurons, presumably by upregulating HSP70, which inhibits neuronal autophagy.

Targeting the Interplay Between Autophagy and the Nrf2 Pathway in Parkinson's Disease with Potential Therapeutic Implications

Parkinson's disease (PD) is a prevalent neurodegenerative disorder marked by the progressive degeneration of midbrain dopaminergic neurons and resultant locomotor dysfunction. Despite over two centuries of recognition as a chronic disease, the exact pathogenesis of PD remains elusive. The onset and progression of PD involve multiple complex pathological processes, with dysfunctional autophagy and elevated oxidative stress serving as critical contributors. Notably, emerging research has underscored the interplay between autophagy and oxidative stress in PD pathogenesis. Given the limited efficacy of therapies targeting either autophagy dysfunction or oxidative stress, it is crucial to elucidate the intricate mechanisms governing their interplay in PD to develop more effective therapeutics. This review overviews the role of autophagy and nuclear factor erythroid 2-related factor 2 (Nrf2), a pivotal transcriptional regulator orchestrating cellular defense mechanisms against oxidative stress, and the complex interplay between these processes. By elucidating the intricate interplay between these key pathological processes in PD, this review will deepen our comprehensive understanding of the multifaceted pathological processes underlying PD and may uncover potential strategies for its prevention and treatment.

Gut Microbiota-Based Interventions for Parkinson's Disease: Neuroprotective Mechanisms and Current Perspective

Recent evidence links gut microbiota alterations to neurodegenerative disorders, including Parkinson's disease (PD). Replenishing the abnormal composition of gut microbiota through gut microbiota-based interventions "prebiotics, probiotics, synbiotics, postbiotics, and fecal microbiota transplantation (FMT)" has shown beneficial effects in PD. These interventions increase gut metabolites like short-chain fatty acids (SCFAs) and glucagon-like peptide-1 (GLP-1), which may protect dopaminergic neurons via the gut-brain axis. Neuroprotective effects of these interventions are mediated by several mechanisms, including the enhancement of neurotrophin and activation of the PI3K/AKT/mTOR signaling pathway, GLP-1-mediated gut-brain axis signaling, Nrf2/ARE pathway, and autophagy. Other pathways, such as free fatty acid receptor activation, synaptic plasticity improvement, and blood-brain and gut barrier integrity maintenance, also contribute to neuroprotection. Furthermore, the inhibition of the TLR4/NF-кB pathway, MAPK pathway, GSK-3β signaling pathway, miR-155-5p-mediated neuroinflammation, and ferroptosis could account for their protective effects. Clinical studies involving gut microbiota-based interventions have shown therapeutic benefits in PD patients, particularly in improving gastrointestinal dysfunction and some neurological symptoms. However, the effectiveness in alleviating motor symptoms remains mild. Large-scale clinical trials are still needed to confirm these findings. This review emphasizes the neuroprotective mechanisms of gut microbiota-based interventions in PD as supported by both preclinical and clinical studies.

Lipid Oxidation at the Crossroads: Oxidative Stress and Neurodegeneration Explored in Caenorhabditis elegans

Lipid metabolism plays a critical role in maintaining cellular integrity, especially within the nervous system, where lipids support neuronal structure, function, and synaptic plasticity. However, this essential metabolic pathway is highly susceptible to oxidative stress, which can lead to lipid peroxidation, a damaging process induced by reactive oxygen species. Lipid peroxidation generates by-products that disrupt many cellular functions, with a strong impact on proteostasis. In this review, we explore the role of lipid oxidation in protein folding and its associated pathological implications, with a particular focus on findings in neurodegeneration from Caenorhabditis elegans studies, an animal model that remains underutilized. Additionally, we highlight the effectiveness of different methodologies applied in this nematode to deepen our understanding of this intricate process. In the nervous system of any animal, including mammals and invertebrates, lipid oxidation can disturb the delicate balance of cellular homeostasis, leading to oxidative stress, the build-up of toxic by-products, and protein misfolding, key factors in neurodegenerative diseases. This disruption contributes to the pathogenesis of neurodegenerative disorders such as Alzheimer's, Parkinson's, or Huntington's disease. The findings from Caenorhabditis elegans studies offer valuable insights into these complex processes and highlight potential avenues for developing targeted therapies to mitigate neurodegenerative disease progression.

Proteostasis disruption and senescence in Alzheimer's disease pathways to neurodegeneration

Alzheimer's Disease (AD) is a progressive neurological disease associated with behavioral abnormalities, memory loss, and cognitive impairment that cause major causes of dementia in the elderly. The pathogenetic processes cause complex effects on brain function and AD progression. The proper protein homeostasis, or proteostasis, is critical for cell health. AD causes the buildup of misfolded proteins, particularly tau and amyloid-beta, to break down proteostasis, such aggregates are toxic to neurons and play a critical role in AD pathogenesis. The rise of cellular senescence is accompanied by aging, marked by irreversible cell cycle arrest and the release of pro-inflammatory proteins. Senescent cell build-up in the brains of AD patients exacerbates neuroinflammation and neuronal degeneration. These cells senescence-associated secretory phenotype (SASP) also disturbs the brain environment. When proteostasis failure and cellular senescence coalesce, a cycle is generated that compounds each other. While senescent cells contribute to proteostasis breakdown through inflammatory and degradative processes, misfolded proteins induce cellular stress and senescence. The principal aspects of the neurodegenerative processes in AD are the interaction of cellular senescence and proteostasis failure. This review explores the interconnected roles of proteostasis disruption and cellular senescence in the pathways leading to neurodegeneration in AD.

Novel prospects in targeting neurodegenerative disorders via autophagy

Protein aggregation occurs as a consequence of dysfunction in the normal cellular proteostasis, which leads to the accumulation of toxic fibrillar aggregates of certain proteins in the cell. Enhancing the activity of proteolytic pathways may serve as a way of clearing these aggregates in a cell, and consequently, autophagy has surfaced as a promising target for the treatment of neurodegenerative disorders. Several strategies involving small molecule compounds that stimulate autophagic pathway of cell have been discovered. However, despite many compounds having demonstrated favorable outcomes in experimental disease models, the translation of these findings into clinical benefits for patient's remains limited. Consequently, alternative strategies are actively being explored to effectively target neurodegeneration via autophagy modulation. Recently, newer approaches such as modulation of expression of autophagic genes have emerged as novel and interesting areas of research in this field, which hold promising potential in neuroprotection. Similarly, as discussed for the first time in this review, the use of autophagy-inducing nanoparticles by utilizing their physicochemical properties to stimulate the autophagic process, rather than relying on their role as drug carriers, offers a completely fresh avenue for targeting neurodegeneration without the risk of drug-associated adverse effects. This review provides fresh perspectives on developing autophagy-targeted therapies for neurodegenerative disorders. Additionally, it discusses the challenges and impediments of implementing these strategies to alleviate the pathogenesis of neurodegenerative disorders in clinical settings and highlights the prospects and directions of future research in this context.

The Effectiveness and Safety Analysis of Duloxetine in Treating Comorbid Depression in Parkinson's Disease: A Retrospective Study

BACKGROUND

Parkinson's disease (PD) is a neurodegenerative disorder characterized by both motor and non-motor symptoms, including depression, which significantly impacts the quality of life of affected individuals. This study aims to investigate the real-world effectiveness and safety of duloxetine in treating comorbid depression in patients with Parkinson's disease and to compare its outcomes with traditional treatment approaches.

METHODS

This study included adult patients diagnosed with Parkinson's disease combined with depression from December 2020 to December 2023. Based on the use of duloxetine, the cohort was divided into a traditional treatment group and a duloxetine group (traditional treatment combined with duloxetine). Patients with incomplete medical records, concurrent antidepressant therapy, or major psychiatric or neurological disorders were excluded. Retrospective data, including demographic information, treatment adherence, and various assessment scores, were collected from medical records by trained research staff.

RESULTS

In total, 106 patients were analyzed, with 50 patients receiving traditional treatment and 56 patients receiving duloxetine. The duloxetine group exhibited significantly lower scores than the traditional treatment group in the Unified PD Rating Scale (p = 0.015), Hamilton Depression Rating Scale (p = 0.013), Beck Depression Inventory (p = 0.031), Parkinson's disease Questionnaire-39 (p = 0.006), and Clinical Global Impression-Improvement (p < 0.001) scores. In motor function assessment, the duloxetine group demonstrated improvements in kinetic tremor scores (p = 0.017), gait speed (p < 0.001), Timed Up and Go Test performance (p < 0.001), dyskinesia severity (p = 0.017), and rigidity (p = 0.019) compared to the traditional treatment group. Additionally, the duloxetine group exhibited better cognitive function across various assessments, including the Symbol Digit Modalities Test (p = 0.024), Stroop Color-Word Test (p = 0.048), and Montreal Cognitive Assessment (p = 0.024).

CONCLUSION

Duloxetine is associated with superior efficacy in improving motor and non-motor symptoms, overall clinical status, and cognitive function. These findings support the potential utility of duloxetine as a comprehensive treatment option for comorbid depression in Parkinson's disease.

The role of polo-like kinases 2 in the proteasomal and lysosomal degradation of alpha-synuclein in neurons

Parkinson's disease (PD) is a neurodegenerative disorder caused by the degeneration of dopaminergic neurons in the brain stem. PD is mostly sporadic, but familial PD (FPD) cases are recorded in different studies. The first gene mutation that is linked to FPD is α-synuclein (α-syn). It was then found that α-syn is also accumulated in Lewy body (LB), a classical pathological hallmark in PD patients. Different studies have shown that α-syn accumulation and aggregation can be a crucial factor contributing to the degeneration of dopaminergic neurons in PD. α-syn has been found to be degraded by the ubiquitin proteasomal system (UPS) and autophagy-lysosomal pathway (ALP). In this study, we initially explored how α-syn phosphorylation by GRK6, PLK2 and CK2α would facilitate its degradation in relation to the UPS or ALP. Unexpectedly, we found that the degradation of α-syn through PLK2 phosphorylation could be modulated by UPS and ALP in a novel mechanism. Specially, attenuation of UPS could increase the amount of PLK2 and then could facilitate the phosphorylation and degradation of α-syn through ALP. To test this further in vivo, we attenuate the proteasomal activity in a well-established A53T α-syn transgenic PD mouse model. We found that attenuation of proteasomal activity in the A53T α-syn transgenic mice could reduce the accumulation of α-syn in the striatum and midbrain. Based on our results, this study provides a new insight into how α-syn is degraded through the UPS and ALP.

Clinical, mechanistic, biomarker, and therapeutic advances in GBA1-associated Parkinson's disease

Parkinson's disease (PD) is the second most common neurodegenerative disease. The development of PD is closely linked to genetic and environmental factors, with GBA1 variants being the most common genetic risk. Mutations in the GBA1 gene lead to reduced activity of the coded enzyme, glucocerebrosidase, which mediates the development of PD by affecting lipid metabolism (especially sphingolipids), lysosomal autophagy, endoplasmic reticulum, as well as mitochondrial and other cellular functions. Clinically, PD with GBA1 mutations (GBA1-PD) is characterized by particular features regarding the progression of symptom severity. On the therapeutic side, the discovery of the relationship between GBA1 variants and PD offers an opportunity for targeted therapeutic interventions. In this review, we explore the genotypic and phenotypic correlations, etiologic mechanisms, biomarkers, and therapeutic approaches of GBA1-PD and summarize the current state of research and its challenges.

The GBA1 K198E Variant Is Associated with Suppression of Glucocerebrosidase Activity, Autophagy Impairment, Oxidative Stress, Mitochondrial Damage, and Apoptosis in Skin Fibroblasts

Parkinson's disease (PD) is a multifactorial, chronic, and progressive neurodegenerative disorder inducing movement alterations as a result of the loss of dopaminergic (DAergic) neurons of the pars compacta in the substantia nigra and protein aggregates of alpha synuclein (α-Syn). Although its etiopathology agent has not yet been clearly established, environmental and genetic factors have been suggested as the major contributors to the disease. Mutations in the glucosidase beta acid 1 (GBA1) gene, which encodes the lysosomal glucosylceramidase (GCase) enzyme, are one of the major genetic risks for PD. We found that the GBA1 K198E fibroblasts but not WT fibroblasts showed reduced catalytic activity of heterozygous mutant GCase by -70% but its expression levels increased by 3.68-fold; increased the acidification of autophagy vacuoles (e.g., autophagosomes, lysosomes, and autolysosomes) by +1600%; augmented the expression of autophagosome protein Beclin-1 (+133%) and LC3-II (+750%), and lysosomal-autophagosome fusion protein LAMP-2 (+107%); increased the accumulation of lysosomes (+400%); decreased the mitochondrial membrane potential (∆Ψm) by -19% but the expression of Parkin protein remained unperturbed; increased the oxidized DJ-1Cys106-SOH by +900%, as evidence of oxidative stress; increased phosphorylated LRRK2 at Ser935 (+1050%) along with phosphorylated α-synuclein (α-Syn) at pathological residue Ser129 (+1200%); increased the executer apoptotic protein caspase 3 (cleaved caspase 3) by +733%. Although exposure of WT fibroblasts to environmental neutoxin rotenone (ROT, 1 μM) exacerbated the autophagy-lysosomal system, oxidative stress, and apoptosis markers, ROT moderately increased those markers in GBA1 K198E fibroblasts. We concluded that the K198E mutation endogenously primes skin fibroblasts toward autophagy dysfunction, OS, and apoptosis. Our findings suggest that the GBA1 K198E fibroblasts are biochemically and molecularly equivalent to the response of WT GBA1 fibroblasts exposed to ROT.

High frequency electrical stimulation reduces α-synuclein levels and α-synuclein-mediated autophagy dysfunction

Accumulation of α-synuclein (α-Syn) has been implicated in proteasome and autophagy dysfunction in Parkinson's disease (PD). High frequency electrical stimulation (HFS) mimicking clinical parameters used for deep brain stimulation (DBS) in vitro or DBS in vivo in preclinical models of PD have been found to reduce levels of α-Syn and, in certain cases, provide possible neuroprotection. However, the mechanisms by which this reduction in α-Syn improves cellular dysfunction associated with α-Syn accumulation remains elusive. Using HFS parameters that recapitulate DBS in vitro, we found that HFS led to a reduction of mutant α-Syn and thereby limited proteasome and autophagy impairments due to α-Syn. Additionally, we observed that HFS modulates via the ATP6V0C subunit of V-ATPase and mitigates α-Syn mediated autophagic dysfunction. This study highlights a role for autophagy in reduction of α-Syn due to HFS which may prove to be a viable approach to decrease pathological protein accumulation in neurodegeneration.

ncRNAs and their impact on dopaminergic neurons: Autophagy pathways in Parkinson's disease

Parkinson's Disease (PD) is a complex neurological illness that causes severe motor and non-motor symptoms due to a gradual loss of dopaminergic neurons in the substantia nigra. The aetiology of PD is influenced by a variety of genetic, environmental, and cellular variables. One important aspect of this pathophysiology is autophagy, a crucial cellular homeostasis process that breaks down and recycles cytoplasmic components. Recent advances in genomic technologies have unravelled a significant impact of ncRNAs on the regulation of autophagy pathways, thereby implicating their roles in PD onset and progression. They are members of a family of RNAs that include miRNAs, circRNA and lncRNAs that have been shown to play novel pleiotropic functions in the pathogenesis of PD by modulating the expression of genes linked to autophagic activities and dopaminergic neuron survival. This review aims to integrate the current genetic paradigms with the therapeutic prospect of autophagy-associated ncRNAs in PD. By synthesizing the findings of recent genetic studies, we underscore the importance of ncRNAs in the regulation of autophagy, how they are dysregulated in PD, and how they represent novel dimensions for therapeutic intervention. The therapeutic promise of targeting ncRNAs in PD is discussed, including the barriers that need to be overcome and future directions that must be embraced to funnel these ncRNA molecules for the treatment and management of PD.

Dose-Dependent Alterations of Lysosomal Activity and Alpha-Synuclein in Peripheral Blood Monocyte-Derived Macrophages and SH-SY5Y Neuroblastoma Cell Line by upon Inhibition of MTOR Protein Kinase - Assessment of the Prospects of Parkinson's Disease Therapy

To date, the molecular mechanisms of the common neurodegenerative disorder Parkinson's disease (PD) are unknown and, as a result, there is no neuroprotective therapy that may stop or slow down the process of neuronal cell death. The aim of the current study was to evaluate the prospects of using the mTOR molecule as a potential target for PD therapy due to the dose-dependent effect of mTOR kinase activity inhibition on cellular parameters associated with, PD pathogenesis. The study used peripheral blood monocyte-derived macrophages and SH-SY5Y neuroblastoma cell line. As a result, we have for the first time showed that inhibition of mTOR by Torin1 only at a concentration of 100 nM affects the level of the lysosomal enzyme glucocerebrosidase (GCase), encoded by the GBA1 gene. Mutations in GBA1 are considered a high-risk factor for PD development. This concentration led a decrease in pathological phosphorylated alpha-synuclein (Ser129), an increase in its stable tetrameric form with no changes in the lysosomal enzyme activities and concentrations of lysosphingolipids. Our findings suggest that inhibition of the mTOR protein kinase could be a promising approach for developing therapies for PD, particularly for GBA1-associated PD.

The role of autophagy in Parkinson's disease: a gender difference overview

Recent studies have demonstrated dysregulation of the autophagy pathway in patients with Parkinson's disease (PD) and in animal models of PD, highlighting its emerging role in disease. In particular, several studies indicate that autophagy, which is an essential degradative process for the damaged protein homeostasis and the management of cell balance, can manifest significant variations according to gender. While some evidence suggests increased autophagic activation in men with PD, women may have distinct regulatory patterns. In this review, we examined the existing literature on gender differences in PD-associated autophagic processes, focusing on the autophagy related proteins (ATGs) and leucine rich repeat kinase 2 (LRRK2) genes. Also, this review would suggest that an in-depth understanding of these gender differences in autophagic processes could open new perspectives for personalized therapeutic strategies, promoting more effective and targeted management of PD.

Targets to Search for New Pharmacological Treatment in Idiopathic Parkinson's Disease According to the Single-Neuron Degeneration Model

One of the biggest problems in the treatment of idiopathic Parkinson's disease is the lack of new drugs that slow its progression. L-Dopa remains the star drug in the treatment of this disease, although it induces severe side effects. The failure of clinical studies with new drugs depends on the use of preclinical models based on neurotoxins that do not represent what happens in the disease since they induce rapid and expansive neurodegeneration. We have recently proposed a single-neuron degeneration model for idiopathic Parkinson's disease that requires years to accumulate enough lost neurons for the onset of motor symptoms. This single-neuron degeneration model is based on the excessive formation of aminochrome during neuromelanin synthesis that surpass the neuroprotective action of the enzymes DT-diaphorase and glutathione transferase M2-2, which prevent the neurotoxic effects of aminochrome. Although the neurotoxic effects of aminochrome do not have an expansive effect, a stereotaxic injection of this endogenous neurotoxin cannot be used to generate a preclinical model in an animal. Therefore, the aim of this review is to evaluate the strategies for pharmacologically increasing the expression of DT diaphorase and GSTM2-2 and molecules that induce the expression of vesicular monoamine transporter 2, such as pramipexole.

Protective effect of phenylpropionamides in the seed of Cannabis Sativa L. on Parkinson's disease through autophagy

Parkinson's disease (PD) is the second most common neurodegenerative disease in the world. As one of the major degradation pathways, autophagy plays a pivotal role in maintaining the effective turnover of proteins and damaged organelles in cells. Lewy bodies composed of α-synuclein (α-syn) abnormally aggregated in the substantia nigra are important pathological features of PD, and autophagy dysfunction is considered to be an important factor leading to abnormal aggregation of α-syn. Phenylpropionamides (PHS) in the seed of Cannabis sativa L. have a protective effect on neuroinflammation and antioxidant activity. However, the therapeutic role of PHS in PD is unclear. In this study, the seeds of Cannabis sativa L. were extracted under reflux with 60% EtOH-H2O, and the 60% EtOH-H2O elution fraction was identified as PHS with the UPLC-QTOF-MS. The 1-methyl-4-phenyl-1,2,3,6-tetrahydro-pyridine (MPTP)-induced PD model in C57BL/6 J mice was used for behavioral and pharmacodynamic experiments. Behavioral symptoms were improved, Nissl-stained and TH-positive neurons in the substantia nigra were significantly increased in PHS-treated MPTP-induced PD model mice. Compared with the model group, PHS treatment reduced the expression level of α-syn, and the expression of TH increased significantly by western blotting, compared with the model group, the PHS group suppressed Caspase 3 and Bax expression and promoted Bcl-2 expression and levels of p62 decreased significantly, the ratio of LC3-II/I and p-mTOR/mTOR in the PHS group had a downward trend, suggesting that the therapeutic effect of PHS on MPTP-induced PD model mice may be triggered by the regulation of autophagy.

Corydaline alleviates Parkinson's disease by regulating autophagy and GSK-3β phosphorylation

BACKGROUND

Jitai tablet, a traditional Chinese medicine, has a neuroprotective effect on 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP)-induced Parkinson's disease (PD) mice. As one of the main active ingredients in the Jitai tablet, corydaline (Cory) has analgesic and anti-allergic effects, but it has not been studied in PD. Here, we investigated the role and mechanism of Cory in PD.

METHODS

The PD model was induced by MPTP. Cell viability was measured by 3-(4, 5)-dimethylthiahiazo (-z-y1)-3, 5-di-phenytetrazoliumromide assay. The Pole test and traction test were performed to detect the behaviors of mice. The expression of tyrosine hydroxylase (Th) was detected by immunohistochemistry and Western blot. Immunofluorescence staining, monodansylcadaverine staining, and Western blot were conducted to assess autophagy. A lactic dehydrogenase release assay was used to detect cytotoxicity. Network pharmacology was used to screen the targets.

RESULTS

There existed cytotoxicity when the concentration of Cory reached 40 μg/mL. Cory (not exceeding 20 μg/mL) could alleviate MPTP-induced cell damage. In vivo experiments indicated that Cory could improve the motor coordination of mice with PD. Besides, Cory could increase LC3-II/LC3-I levels both in vivo and in vitro. In addition, the Th levels reduced in the striatum and middle brain tissues of Parkinson's mice were recovered by Cory injection. We also found that Cory decreased the phosphorylation of glucogen synthase kinase-3 beta (GSK-3β) at Tyr216 and increased the phosphorylation of GSK-3β at Ser9 not only in primary neurons and SH-SY5Y cells but also in the striatum and middle brain tissues. Furthermore, Cory increased LC3-II/LC3-I levels and decreased p62 levels by regulating GSK-3β.

CONCLUSION

Cory enhanced autophagy, attenuated MPTP-induced cytotoxicity, and alleviated PD partly through the regulation of GSK-3β phosphorylation.

Ablation of Mitochondrial RCC1-L Induces Nigral Dopaminergic Neurodegeneration and Parkinsonian-like Motor Symptoms

Mitochondrial dysfunction has been linked to both idiopathic and familial forms of Parkinson's disease (PD). We have previously identified RCC1-like (RCC1L) as a protein of the inner mitochondrial membrane important to mitochondrial fusion. Herein, to test whether deficits in RCC1L mitochondrial function might be involved in PD pathology, we have selectively ablated the Rcc1l gene in the dopaminergic (DA) neurons of mice. A PD-like phenotype resulted that includes progressive movement abnormalities, paralleled by progressive degeneration of the nigrostriatal tract. Experimental and control groups were examined at 2, 3-4, and 5-6 months of age. Animals were tested in the open field task to quantify anxiety, exploratory drive, locomotion, and immobility; and in the cylinder test to quantify rearing behavior. Beginning at 3-4 months, both female and male Rcc1l knockout mice show rigid muscles and resting tremor, kyphosis and a growth deficit compared with heterozygous or wild type littermate controls. Rcc1l knockout mice begin showing locomotor impairments at 3-4 months, which progress until 5-6 months of age, at which age the Rcc1l knockout mice die. The progressive motor impairments were associated with progressive and significantly reduced tyrosine hydroxylase immunoreactivity in the substantia nigra pars compacta (SNc), and dramatic loss of nigral DA projections in the striatum. Dystrophic spherical mitochondria are apparent in the soma of SNc neurons in Rcc1l knockout mice as early as 1.5-2.5 months of age and become progressively more pronounced until 5-6 months. Together, the results reveal the RCC1L protein to be essential to in vivo mitochondrial function in DA neurons. Further characterization of this mouse model will determine whether it represents a new model for in vivo study of PD, and the putative role of the human RCC1L gene as a risk factor that might increase PD occurrence and severity in humans.

Neuroinflammation and Neurodegenerative Diseases: How Much Do We Still Not Know?

The term "neuroinflammation" defines the typical inflammatory response of the brain closely related to the onset of many neurodegenerative diseases (NDs). Neuroinflammation is well known, but its mechanisms and pathways are not entirely comprehended. Some progresses have been achieved through many efforts and research. Consequently, new cellular and molecular mechanisms, diverse and conventional, are emerging. In listing some of those that will be the subject of our description and discussion, essential are the important roles of peripheral and infiltrated monocytes and clonotypic cells, alterations in the gut-brain axis, dysregulation of the apelinergic system, alterations in the endothelial glycocalyx of the endothelial component of neuronal vascular units, variations in expression of some genes and levels of the encoding molecules by the action of microRNAs (miRNAs), or other epigenetic factors and distinctive transcriptional factors, as well as the role of autophagy, ferroptosis, sex differences, and modifications in the circadian cycle. Such mechanisms can add significantly to understanding the complex etiological puzzle of neuroinflammation and ND. In addition, they could represent biomarkers and targets of ND, which is increasing in the elderly.