Molecular pathways of neurodegeneration in Parkinson's disease

Functional Role of DDR1 in Oligodendrocyte Signaling Mechanism in Association with Myelination and Remyelination Process in the Central Nerve System

ABSTRACT

Multiple sclerosis (MS) is a complicated, inflammatory disease that causes demyelination of the central nervous system (CNS), resulting in a variety of neurological abnormalities. Over the past several decades, different animal models have been used to replicate the clinical symptoms and neuropathology of MS. The experimental model of experimental autoimmune/allergic encephalomyelitis (EAE) and viral and toxin-induced model was widely used to investigate the clinical implications of MS. Discoidin domain receptor 1 (DDR1) signaling in oligodendrocytes (OL) brings a new dimension to our understanding of MS pathophysiology. DDR1 is effectively involved in the OL during neurodevelopment and remyelination. It has been linked to many cellular processes, including migration, invasion, proliferation, differentiation, and adhesion. However, the exact functional involvement of DDR1 in developing OL and myelinogenesis in the CNS remains undefined. In this review, we critically evaluate the current literature on DDR1 signaling in OL and its proliferation, migration, differentiation, and myelination mechanism in OL in association with the progression of MS. It increases our knowledge of DDR1 in OL as a novel target molecule for oligodendrocyte-associated diseases in the CNS, including MS.

Generation of an iPSC line from a 79-year-old female patient diagnosed with sporadic Parkinson's disease

Parkinson's disease is a common neurodegenerative disorder. Here we present a human induced pluripotent stem cells (iPSCs) derived from peripheral blood mononuclear cells (PBMCs) of a 79-year-old female patient diagnosed with sporadic Parkinson's disease using the sendai virus. Generated iPSCs maintain normal karyotype, exhibit pluripotent stem cell markers, and possess differentiation potential. The iPSCs allows for differentiation into various cell subtypes, providing conditions for the research of the pathogenesis and drug development of Parkinson's disease.

In silico study on graphene quantum dots modified with various functional groups inhibiting α‑synuclein dimerization

HYPOTHESIS

Graphene quantum dots (GQDs) with various functional groups are hypothesized to inhibit the α-synuclein (αS) dimerization, a crucial step in Parkinson's disease pathogenesis. The potential of differently functionalized GQDs is systematically explored.

EXPERIMENTS

All-atom replica-exchange molecular dynamics simulations (accumulating to 75.6 μs) in explicit water were performed to study the dimerization of the αS non-amyloid component region and the influence of GQDs modified with various functional groups. Conformation ensemble, binding behavior, and free energy analysis were conducted.

FINDINGS

All studied GQDs inhibit β-sheet and backbone hydrogen bond formation in αS dimers, leading to looser oligomeric conformations. Charged GQDs severely impede the growth of extended β-sheets by providing extra contact surface. GQD binding primarily disrupts αS inter-peptide interactions through π-π stacking, CH-π interactions, and for charged GQDs, additionally through salt-bridge and hydrogen bonding interactions. GQD-COO- showed the most optimal inhibitory effect, binding mode, and intensity, which holds promise for the development of nanomedicines targeting amyloid aggregation in neurodegenerative diseases.

Design and Synthesis of a Novel Binuclear Palladium Complex as a Turn on Fluorescent Receptor for Neurotransmitter Dopamine

A novel binuclear palladium complex has been synthesized by the reaction of tetramethylethylenediamine palladium nitrate and sodium salt of pyromellitic acid. UV vis, NMR as well as fluorescent titration techniques show that this binuclear palladium complex interacts with neurotransmitter dopamine. The fluorescence of the palladium complex in aqueous solution gets enhanced with the gradual addition of the neurotransmitter dopamine which makes this complex to act as a turn on fluorescent sensor for neurotransmitter dopamine.

Alpha-Synuclein Interaction with UBL3 Is Upregulated by Microsomal Glutathione S-Transferase 3, Leading to Increased Extracellular Transport of the Alpha-Synuclein under Oxidative Stress

Aberrant aggregation of misfolded alpha-synuclein (α-syn), a major pathological hallmark of related neurodegenerative diseases such as Parkinson's disease (PD), can translocate between cells. Ubiquitin-like 3 (UBL3) is a membrane-anchored ubiquitin-fold protein and post-translational modifier. UBL3 promotes protein sorting into small extracellular vesicles (sEVs) and thereby mediates intercellular communication. Our recent studies have shown that α-syn interacts with UBL3 and that this interaction is downregulated after silencing microsomal glutathione S-transferase 3 (MGST3). However, how MGST3 regulates the interaction of α-syn and UBL3 remains unclear. In the present study, we further explored this by overexpressing MGST3. In the split Gaussia luciferase complementation assay, we found that the interaction between α-syn and UBL3 was upregulated by MGST3. While Western blot and RT-qPCR analyses showed that silencing or overexpression of MGST3 did not significantly alter the expression of α-syn and UBL3, the immunocytochemical staining analysis indicated that MGST3 increased the co-localization of α-syn and UBL3. We suggested roles for the anti-oxidative stress function of MGST3 and found that the effect of MGST3 overexpression on the interaction between α-syn with UBL3 was significantly rescued under excess oxidative stress and promoted intracellular α-syn to extracellular transport. In conclusion, our results demonstrate that MGST3 upregulates the interaction between α-syn with UBL3 and promotes the interaction to translocate intracellular α-syn to the extracellular. Overall, our findings provide new insights and ideas for promoting the modulation of UBL3 as a therapeutic agent for the treatment of synucleinopathy-associated neurodegenerative diseases.

Decoding mitochondrial quality control mechanisms: Identifying treatment targets for enhanced cellular health

Mitochondria are singular cell organelles essential for many cellular functions, which includes responding to stress, regulating calcium levels, maintaining protein homeostasis, and coordinating apoptosis response. The vitality of cells, therefore, hinges on the optimal functioning of these dynamic organelles. Mitochondrial Quality Control Mechanisms (MQCM) play a pivotal role in ensuring the integrity and functionality of mitochondria. Perturbations in these mechanisms have been closely associated with the pathogenesis of neurodegenerative disorders such as Parkinson's disease, Alzheimer's disease, Huntington's disease, and amyotrophic lateral sclerosis. Compelling evidence suggests that targeting specific pathways within the MQCM could potentially offer a therapeutic avenue for rescuing mitochondrial integrity and mitigating the progression of neurodegenerative diseases. The intricate interplay of cellular stress, protein misfolding, and impaired quality control mechanisms provides a nuanced understanding of the underlying pathology. Consequently, unravelling the specific MQCM dysregulation in neurodegenerative disorders becomes paramount for developing targeted therapeutic strategies. This review delves into the impaired MQCM pathways implicated in neurodegenerative disorders and explores emerging therapeutic interventions. By shedding light on pharmaceutical and genetic manipulations aimed at restoring MQCM efficiency, the discussion aims to provide insights into novel strategies for ameliorating the progression of neurodegenerative diseases. Understanding and addressing mitochondrial quality control mechanisms not only underscore their significance in cellular health but also offer a promising frontier for advancing therapeutic approaches in the realm of neurodegenerative disorders.

Effect of the mGlu2 positive allosteric modulator biphenyl-indanone A as a monotherapy and as adjunct to a low dose of L-DOPA in the MPTP-lesioned marmoset

Activation of metabotropic glutamate 2 (mGlu2) receptors is a potential novel therapeutic approach for the treatment of parkinsonism. Thus, when administered as monotherapy or as adjunct to a low dose of L-3,4-dihydroxyphenylalanine (L-DOPA), the mGlu2 positive allosteric modulator (PAM) LY-487,379 alleviated parkinsonism in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-lesioned primates. Here, we sought to investigate the effect of biphenyl-indanone A (BINA), a highly selective mGlu2 PAM whose chemical scaffold is unrelated to LY-487,379, to determine if a structurally different mGlu2 PAM would also confer anti-parkinsonian benefit. In monotherapy experiments, MPTP-lesioned marmosets were injected with either vehicle, L-DOPA/benserazide (15/3.75 mg/kg, positive control) or BINA (0.1, 1, 10 mg/kg). In adjunct to a low L-DOPA dose experiments, MPTP-lesioned marmosets were injected with L-DOPA/benserazide (7.5/1.875 mg/kg) in combination with vehicle or BINA (0.1, 1, 10 mg/kg). Parkinsonism, dyskinesia and psychosis-like behaviours (PLBs) were then quantified. When administered alone, BINA 1 and 10 mg/kg decreased parkinsonism severity by ~22% (p < 0.01) and ~47% (p < 0.001), when compared with vehicle, which was comparable with the global effect of a high L-DOPA dose. When administered in combination with a low L-DOPA dose, BINA 1 and 10 mg/kg decreased global parkinsonism by ~38% (p < 0.001) and ~53% (p < 0.001). BINA 10 mg/kg decreased global dyskinesia by ~94% (p < 0.01) and global PLBs by ~92% (p < 0.01). Our results provide additional evidence that mGlu2 positive allosteric modulation elicits anti-parkinsonian effects. That this benefit is not related to a particular chemical scaffold suggests that it may be a class effect rather than the effect of a specific molecule.

Activation of mGlu 2/3 receptors with the orthosteric agonist LY-404,039 alleviates dyskinesia in experimental parkinsonism

LY-404,039 is an orthosteric agonist at metabotropic glutamate 2 and 3 (mGlu 2/3 ) receptors, with a possible additional agonist effect at dopamine D 2 receptors. LY-404,039 and its pro-drug, LY-2140023, have previously been tested in clinical trials for psychiatric indications and could therefore be repurposed if they were shown to be efficacious in other conditions. We have recently demonstrated that the mGlu 2/3 orthosteric agonist LY-354,740 alleviated L-3,4-dihydroxyphenylalanine (L-DOPA)-induced abnormal involuntary movements (AIMs) in the 6-hydroxydopamine (6-OHDA)-lesioned rat without hampering the anti-parkinsonian action of L-DOPA. Here, we seek to take advantage of a possible additional D 2 -agonist effect of LY-404,039 and see if an anti-parkinsonian benefit might be achieved in addition to the antidyskinetic effect of mGlu 2/3 activation. To this end, we have administered LY-404,039 (vehicle, 0.1, 1 and 10 mg/kg) to 6-OHDA-lesioned rats, after which the severity of axial, limbs and oro-lingual (ALO) AIMs was assessed. The addition of LY-404,039 10 mg/kg to L-DOPA resulted in a significant reduction of ALO AIMs over 60-100 min (54%, P  < 0.05). In addition, LY-404,039 significantly enhanced the antiparkinsonian effect of L-DOPA, assessed through the cylinder test (76%, P  < 0.01). These results provide further evidence that mGlu 2/3 orthosteric stimulation may alleviate dyskinesia in PD and, in the specific case of LY-404,039, a possible D 2 -agonist effect might also make it attractive to address motor fluctuations. Because LY-404,039 and its pro-drug have been administered to humans, they could possibly be advanced to Phase IIa trials rapidly for the treatment of motor complications in PD.

A sporadic Parkinson's disease model via silencing of the ubiquitin-proteasome/E3 ligase component, SKP1A

Our and other's laboratory microarray-derived transcriptomic studies in human PD substantia nigra pars compacta (SNpc) samples have opened an avenue to concentrate on potential gene intersections or cross-talks along the dopaminergic (DAergic) neurodegenerative cascade in sporadic PD (SPD). One emerging gene candidate identified was SKP1A (p19, S-phase kinase-associated protein 1A), found significantly decreased in the SNpc as confirmed later at the protein level. SKP1 is part of the Skp1, Cullin 1, F-box protein (SCF) complex, the largest known class of sophisticated ubiquitin-proteasome/E3-ligases and was found to directly interact with FBXO7, a gene defective in PARK15-linked PD. This finding has led us to the hypothesis that a targeted site-specific reduction of Skp1 levels in DAergic neuronal cell culture and animal systems may result in a progressive loss of DAergic neurons and hopefully recreate motor disabilities in animals. The second premise considers the possibility that both intrinsic and extrinsic factors (e.g., manipulation of selected genes and mitochondria impairing toxins), alleged to play central roles in DAergic neurodegeneration in PD, may act in concert as modifiers of Skp1 deficiency-induced phenotype alterations ('dual-hit' hypothesis of neurodegeneration). To examine a possible role of Skp1 in DAergic phenotype, we have initially knocked down the expression of SKP1A gene in an embryonic mouse SN-derived cell line (SN4741) with short hairpin RNA (shRNA) lentiviruses (LVs). The deficiency of SKP1A closely recapitulated cardinal features of the DAergic pathology of human PD, such as decreased expression of DAergic phenotypic markers and cell cycle aberrations. Furthermore, the knocked down cells displayed a lethal phenotype when induced to differentiate exhibiting proteinaceous round inclusion structures, which were almost identical in composition to human Lewy bodies, a hallmark of PD. These findings support a role for Skp1 in neuronal phenotype, survival, and differentiation. The identification of Skp1 as a key player in DAergic neuron function suggested that a targeted site-specific reduction of Skp1 levels in mice SNpc may result in a progressive loss of DAergic neurons and terminal projections in the striatum. The injected LV SKP1shRNA to mouse SN resulted in decreased expression of Skp1 protein levels within DAergic neurons and loss of tyrosine hydroxylase immunoreactivity (TH-IR) in both SNpc and striatum that was accompanied by time-dependent motor disabilities. The reduction of the vertical movements, that is rearing, may be reminiscent of the early occurrence of hypokinesia and axial, postural instability in PD. According to the 'dual-hit' hypothesis of neurodegenerative diseases, it is predicted that gene-gene and/or gene-environmental factors would act in concert or sequentially to propagate the pathological process of PD. Our findings are compatible with this conjecture showing that the genetic vulnerability caused by knock down of SKP1A renders DAergic SN4741 cells especially sensitive to genetic reduction of Aldh1 and exposure to the external stressors MPP+ and DA, which have been implicated in PD pathology. Future consideration should be given in manipulation SKP1A expression as therapeutic window, via its induction genetically or pharmacological, to prevent degeneration of the nigra striatal dopamine neurons, since UPS is defective.

Protein mimetic 2D FAST rescues alpha synuclein aggregation mediated early and post disease Parkinson's phenotypes

Abberent protein-protein interactions potentiate many diseases and one example is the toxic, self-assembly of α-Synuclein in the dopaminergic neurons of patients with Parkinson's disease; therefore, a potential therapeutic strategy is the small molecule modulation of α-Synuclein aggregation. In this work, we develop an Oligopyridylamide based 2-dimensional Fragment-Assisted Structure-based Technique to identify antagonists of α-Synuclein aggregation. The technique utilizes a fragment-based screening of an extensive array of non-proteinogenic side chains in Oligopyridylamides, leading to the identification of NS132 as an antagonist of the multiple facets of α-Synuclein aggregation. We further identify a more cell permeable analog (NS163) without sacrificing activity. Oligopyridylamides rescue α-Synuclein aggregation mediated Parkinson's disease phenotypes in dopaminergic neurons in early and post disease Caenorhabditis elegans models. We forsee tremendous potential in our technique to identify lead therapeutics for Parkinson's disease and other diseases as it is expandable to other oligoamide scaffolds and a larger array of side chains.

Attenuating mitochondrial dysfunction and morphological disruption with PT320 delays dopamine degeneration in MitoPark mice

BACKGROUND

Mitochondria are essential organelles involved in cellular energy production. Changes in mitochondrial function can lead to dysfunction and cell death in aging and age-related disorders. Recent research suggests that mitochondrial dysfunction is closely linked to neurodegenerative diseases. Glucagon-like peptide-1 receptor (GLP-1R) agonist has gained interest as a potential treatment for Parkinson's disease (PD). However, the exact mechanisms responsible for the therapeutic effects of GLP-1R-related agonists are not yet fully understood.

METHODS

In this study, we explores the effects of early treatment with PT320, a sustained release formulation of the GLP-1R agonist Exenatide, on mitochondrial functions and morphology in a progressive PD mouse model, the MitoPark (MP) mouse.

RESULTS

Our findings demonstrate that administration of a clinically translatable dose of PT320 ameliorates the reduction in tyrosine hydroxylase expression, lowers reactive oxygen species (ROS) levels, and inhibits mitochondrial cytochrome c release during nigrostriatal dopaminergic denervation in MP mice. PT320 treatment significantly preserved mitochondrial function and morphology but did not influence the reduction in mitochondria numbers during PD progression in MP mice. Genetic analysis indicated that the cytoprotective effect of PT320 is attributed to a reduction in the expression of mitochondrial fission protein 1 (Fis1) and an increase in the expression of optic atrophy type 1 (Opa1), which is known to play a role in maintaining mitochondrial homeostasis and decreasing cytochrome c release through remodeling of the cristae.

CONCLUSION

Our findings suggest that the early administration of PT320 shows potential as a neuroprotective treatment for PD, as it can preserve mitochondrial function. Through enhancing mitochondrial health by regulating Opa1 and Fis1, PT320 presents a new neuroprotective therapy in PD.

Effects and mechanisms of bisphenols exposure on neurodegenerative diseases risk: A systemic review

Environmental bisphenols (BPs) pose a global threat to human health because of their extensive use as additives in plastic products. BP residues are increasing in various environmental media (i.e., water, soil, and indoor dust) and biological and human samples (i.e., serum and brain). Both epidemiological and animal studies have determined an association between exposure to BPs and an increased risk of neurodegenerative diseases (e.g., Parkinson's disease, Alzheimer's disease, and amyotrophic lateral sclerosis), including cognitive abnormalities and behavioral disturbances. Hence, understanding the biological responses to different BPs is essential for prevention, and treatment. This study provides an overview of the underlying pathogenic molecular mechanisms as a valuable basis for understanding neurodegenerative disease responses to BPs, including accumulation of misfolded proteins, reduction of tyrosine hydroxylase and dopamine, abnormal hormone signaling, neuronal death, oxidative stress, calcium homeostasis, and inflammation. These findings provide new insights into the neurotoxic potential of BPs and ultimately contribute to a comprehensive health risk evaluation.

The pearl jubilee of microcin J25: thirty years of research on an exceptional lasso peptide

Covering: 1992 up to 2023Since their discovery, lasso peptides went from peculiarities to be recognized as a major family of ribosomally synthesized and post-translationally modified peptide (RiPP) natural products that were shown to be spread throughout the bacterial kingdom. Microcin J25 was first described in 1992, making it one of the earliest known lasso peptides. No other lasso peptide has since then been studied to such an extent as microcin J25, yet, previous review articles merely skimmed over all the research done on this exceptional lasso peptide. Therefore, to commemorate the 30th anniversary of its first report, we give a comprehensive overview of all literature related to microcin J25. This review article spans the early work towards the discovery of microcin J25, its biosynthetic gene cluster, and the elucidation of its three-dimensional, threaded lasso structure. Furthermore, the current knowledge about the biosynthesis of microcin J25 and lasso peptides in general is summarized and a detailed overview is given on the biological activities associated with microcin J25, including means of self-immunity, uptake into target bacteria, inhibition of the Gram-negative RNA polymerase, and the effects of microcin J25 on mitochondria. The in vitro and in vivo models used to study the potential utility of microcin J25 in a (veterinary) medicine context are discussed and the efforts that went into employing the microcin J25 scaffold in bioengineering contexts are summed up.

Neuronal-type-specific epigenome editing to decrease SNCA expression: Implications for precision medicine in synucleinopathies

Overexpression of SNCA has been implicated in the pathogenesis of synucleinopathies, particularly Parkinson's disease (PD) and dementia with Lewy bodies (DLB). While PD and DLB share some clinical and pathological similarities, each disease presents distinct characteristics, including the primary affected brain region and neuronal type. We aimed to develop neuronal-type-specific SNCA-targeted epigenome therapies for synucleinopathies. The system is based on an all-in-one lentiviral vector comprised of CRISPR-dSaCas9 and guide RNA (gRNA) targeted at SNCA intron 1 fused with a synthetic repressor molecule of Krüppel-associated box (KRAB)/ methyl CpG binding protein 2 (MeCp2) transcription repression domain (TRD). To achieve neuronal-type specificity for dopaminergic and cholinergic neurons, the system was driven by tyrosine hydroxylase (TH) and choline acetyltransferase (ChAT) promoters, respectively. Delivering the system into human induced pluripotent stem cell (hiPSC)-derived dopaminergic and cholinergic neurons from a patient with the SNCA triplication resulted in efficient and neuronal-type-specific downregulation of SNCA-mRNA and protein. Furthermore, the reduction in SNCA levels by the gRNA-dSaCas9-repressor system rescued disease-related cellular phenotypes including Ser129-phophorylated α-synuclein, neuronal viability, and mitochondrial dysfunction. We established a novel neuronal-type-specific SNCA-targeted epigenome therapy and provided in vitro proof of concept using human-based disease models. Our results support the therapeutic potential of our system for PD and DLB and provide the foundation for further preclinical studies in animal models toward investigational new drug (IND) enablement and clinical trials.

Effect of the Flavonoid Rutin on the Modulation of the Myenteric Plexuses in an Experimental Model of Parkinson's Disease

Recent discoveries have shown that enteric glial cells play an important role in different neurodegenerative disorders, such as Parkinson's disease (PD), which is characterized by motor dysfunctions caused by the progressive loss of dopaminergic neurons in the substance nigra pars compacta and non-motor symptoms including gastrointestinal dysfunction. In this study, we investigated the modulatory effects of the flavonoid rutin on the behavior and myenteric plexuses in a PD animal model and the response of enteric glia. Adult male Wistar rats were submitted to stereotaxic injection with 6-hydroxydopamine or saline, and they were untreated or treated with rutin (10 mg/kg) for 14 days. The ileum was collected to analyze tissue reactivity and immunohistochemistry for neurons (HuC/HuD) and enteric glial cells (S100β) in the myenteric plexuses. Behavioral tests demonstrated that treatment with rutin improved the motor capacity of parkinsonian animals and improved intestinal transit without interfering with the cell population; rutin treatment modulated the reactivity of the ileal musculature through muscarinic activation, reducing relaxation through the signaling pathway of nitric oxide donors, and increased the longitudinal contractility of the colon musculature in parkinsonian animals. Rutin revealed modulatory activities on the myenteric plexus, bringing relevant answers regarding the effect of the flavonoid in this system and the potential application of PD adjuvant treatment.

Transcriptome-based biomarker prediction for Parkinson's disease using genome-scale metabolic modeling

Parkinson's disease (PD) is the second most common neurodegenerative disease in the world. Identification of PD biomarkers is crucial for early diagnosis and to develop target-based therapeutic agents. Integrative analysis of genome-scale metabolic models (GEMs) and omics data provides a computational approach for the prediction of metabolite biomarkers. Here, we applied the TIMBR (Transcriptionally Inferred Metabolic Biomarker Response) algorithm and two modified versions of TIMBR to investigate potential metabolite biomarkers for PD. To this end, we mapped thirteen post-mortem PD transcriptome datasets from the substantia nigra region onto Human-GEM. We considered a metabolite as a candidate biomarker if its production was predicted to be more efficient by a TIMBR-family algorithm in control or PD case for the majority of the datasets. Different metrics based on well-known PD-related metabolite alterations, PD-associated pathways, and a list of 25 high-confidence PD metabolite biomarkers compiled from the literature were used to compare the prediction performance of the three algorithms tested. The modified algorithm with the highest prediction power based on the metrics was called TAMBOOR, TrAnscriptome-based Metabolite Biomarkers by On-Off Reactions, which was introduced for the first time in this study. TAMBOOR performed better in terms of capturing well-known pathway alterations and metabolite secretion changes in PD. Therefore, our tool has a strong potential to be used for the prediction of novel diagnostic biomarkers for human diseases.

Fibroblast growth factor-21 alleviates proteasome injury via activation of autophagy flux in Parkinson's disease

Parkinson's disease (PD) is one of the most common and complex Neurodegeneration, with an inherited metabolic disorder. Fibroblast growth factor 21 (FGF21), an endocrine hormone that belongs to the fibroblast growth factor superfamily, plays an extensive role in metabolic regulation. However, our understandings of the specific function and mechanisms of FGF21 on PD are still quite limited. Here, we aimed to elucidate the actions and the underlying mechanisms of FGF21 on dopaminergic neurodegeneration using cellular models of parkinsonism. To investigate the effects of FGF21 on dopaminergic neurodegeneration in vitro, proteasome impairment models of PD were utilized. Human dopaminergic neuroblastoma SH-SY5Y cells were treated with the proteasome inhibitor lactacystin (5 μmol/L) for 12 h, then with 50 ng/ml FGF-21 with or without 5 mmol/L of 3-methyladenine.The cells were dissected to assess alterations in autophagy using immunofluorescence, immunoblotting and electron microscopy assays. Our data indicate that FGF21 prevents dopaminergic neuron loss and shows beneficial effects against proteasome impairment induced PD syndrome, indicating it might be a potent candidate for developing novel drugs to deal with PD.

Mechanisms of microRNA-132 in central neurodegenerative diseases: A comprehensive review

MicroRNA-132 (miR-132) is a highly conserved molecule that plays a crucial regulatory role in central nervous system (CNS) disorders. The expression levels of miR-132 exhibit variability in various neurological disorders and have been closely linked to disease onset and progression. The expression level of miR-132 in the CNS is regulated by a diverse range of stimuli and signaling pathways, including neuronal migration and integration, dendritic outgrowth, and complexity, synaptogenesis, synaptic plasticity, as well as inflammation and apoptosis activation. The aberrant expression of miR-132 in various central neurodegenerative diseases has garnered widespread attention. Clinical studies have revealed altered miR-132 expression levels in both chronic and acute CNS diseases, positioning miR-132 as a potential biomarker or therapeutic target. An in-depth exploration of miR-132 holds the promise of enhancing our understanding of the mechanisms underlying CNS diseases, thereby offering novel insights and strategies for disease diagnosis and treatment. It is anticipated that this review will assist researchers in recognizing the potential value of miR-132 and in generating innovative ideas for clinical trials related to CNS degenerative diseases.

3-N-butylphthalide attenuates neuroinflammation in rotenone-induced Parkinson's disease models via the cGAS-STING pathway

Neuroinflammation is crucial in the onset and progression of dopaminergic neuron loss in Parkinson's disease (PD). We aimed to determine whether 3-N-Butylphthalide (NBP) can protect against PD by inhibiting the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway and the inflammatory response of microglia. MitoSOX/MitoTracker/Hoechst staining was used to detect the levels of mitochondrial reactive oxygen species (ROS) in BV2 cells. Quantitative Real-Time Polymerase Chain Reaction was used to measure the levels of free cytoplasmic mitochondrial DNA (mtDNA) in BV2 cells and mouse brain tissues. Behavioral impairments were assessed using rotarod, T-maze, and balance beam tests. Dopaminergic neurons and microglia were observed using immunohistochemical staining. Expression levels of cGAS, STING, nuclear factor kappa-B (NfκB), phospho- NfκB (p-NfκB), inhibitor of NfκBα (IκBα), and phospho-IκBα (p-IκBα) proteins in the substantia nigra and striatum were detected using Western Blot. NBP decreased mitochondrial ROS levels in rotenone-treated BV2 cells. NBP alleviated behavioral impairments and protected against rotenone-induced microgliosis and damage to dopaminergic neurons in the substantia nigra and striatum of rotenone-induced PD mice. NBP decreased rotenone-induced mtDNA leakage and mitigated neuroinflammation by inhibiting cGAS-STING pathway activation. NBP exhibited a protective effect in rotenone-induced PD models by significantly inhibiting the cGAS-STING pathway. Moreover, NBP can alleviate neuroinflammation, and is a potential therapeutic drug for alleviating clinical symptoms and delaying the progression of PD. This study provided insights for the potential role of NBP in PD therapy, potentially mitigating neurodegeneration, and consequently improving the quality of life and lifespan of patients with PD. The limitations are that we have not confirmed the exact mechanism by which NBP decreases mtDNA leakage, and this study was unable to observe the actual clinical therapeutic effect, so further cohort studies are required for validation.

Towards Understanding Neurodegenerative Diseases: Insights from Caenorhabditis elegans

The elevated occurrence of debilitating neurodegenerative disorders, such as amyotrophic lateral sclerosis (ALS), Huntington's disease (HD), Alzheimer's disease (AD), Parkinson's disease (PD) and Machado-Joseph disease (MJD), demands urgent disease-modifying therapeutics. Owing to the evolutionarily conserved molecular signalling pathways with mammalian species and facile genetic manipulation, the nematode Caenorhabditis elegans (C. elegans) emerges as a powerful and manipulative model system for mechanistic insights into neurodegenerative diseases. Herein, we review several representative C. elegans models established for five common neurodegenerative diseases, which closely simulate disease phenotypes specifically in the gain-of-function aspect. We exemplify applications of high-throughput genetic and drug screenings to illustrate the potential of C. elegans to probe novel therapeutic targets. This review highlights the utility of C. elegans as a comprehensive and versatile platform for the dissection of neurodegenerative diseases at the molecular level.

Importance of glucose and its metabolism in neurodegenerative disorder, as well as the combination of multiple therapeutic strategies targeting α-synuclein and neuroprotection in the treatment of Parkinson's disease

According to recent findings, Phosphoglycerate Kinase 1 (pgk-1) enzyme is linked to Parkinson's disease (PD). Mutations in the PGK-1 gene lead to decreases in the pgk-1 enzyme which causes an imbalance in the levels of energy demand and supply. An increase in glycolytic adenosine triphosphate (ATP) production would help alleviate energy deficiency and sustain the acute energetic need of neurons. Neurodegeneration is caused by an imbalance or reduction in ATP levels. Recent data suggest that medications that increase glycolysis and neuroprotection can be used to treat PD. The current study focuses on treatment options for disorders associated with the pgk-1 enzyme, GLP-1, and A2A receptor which can be utilized to treat PD. A combination of metformin and terazosin, exenatide and meclizine, istradefylline and salbutamol treatments may benefit parkinsonism. The review also looked at potential target-specific new techniques that might assist in satisfying unfulfilled requirements in the treatment of PD.

Retinal Changes in Parkinson's Disease: A Non-invasive Biomarker for Early Diagnosis

Parkinson's disease (PD) is caused due to degeneration of dopaminergic neurons in the substantia nigra pars compacta (SNpc) which leads to the depletion of dopamine in the body. The lack of dopamine is mainly due to aggregation of misfolded α-synuclein which causes motor impairment in PD. Dopamine is also required for normal retinal function and the light-dark vision cycle. Misfolded α-synuclein present in inner retinal layers causes vision-associated problems in PD patients. Hence, individuals with PD also experience structural and functional changes in the retina. Mutation in LRRK2, PARK2, PARK7, PINK1, or SNCA genes and mitochondria dysfunction also play a role in the pathophysiology of PD. In this review, we discussed the different etiologies which lead to PD and future prospects of employing non-invasive techniques and retinal changes to diagnose the onset of PD earlier.

Pathological Correlates of Cognitive Decline in Parkinson's Disease: From Molecules to Neural Networks

Parkinson's disease (PD) is a progressive neurodegenerative disorder caused by the death of dopaminergic neurons in the substantia nigra and appearance of protein aggregates (Lewy bodies) consisting predominantly of α-synuclein in neurons. PD is currently recognized as a multisystem disorder characterized by severe motor impairments and various non-motor symptoms. Cognitive decline is one of the most common and worrisome non-motor symptoms. Moderate cognitive impairments (CI) are diagnosed already at the early stages of PD, usually transform into dementia. The main types of CI in PD include executive dysfunction, attention and memory decline, visuospatial impairments, and verbal deficits. According to the published data, the following mechanisms play an essential role demonstrates a crucial importance in the decline of the motor and cognitive functions in PD: (1) changes in the conformational structure of transsynaptic proteins and protein aggregation in presynapses; (2) synaptic transmission impairment; (3) neuroinflammation (pathological activation of the neuroglia); (4) mitochondrial dysfunction and oxidative stress; (5) metabolic disorders (hypometabolism of glucose, dysfunction of glycolipid metabolism; and (6) functional rearrangement of neuronal networks. These changes can lead to the death of dopaminergic cells in the substantia nigra and affect the functioning of other neurotransmitter systems, thus disturbing neuronal networks involved in the transmission of information related to the regulation of motor activity and cognitive functions. Identification of factors causing detrimental changes in PD and methods for their elimination will help in the development of new approaches to the therapy of PD. The goal of this review was to analyze pathological processes that take place in the brain and underlie the onset of cognitive disorders in PD, as well as to describe the impairments of cognitive functions in this disease.

Multicolor colorimetric detection of dopamine based on iodide-responsive copper-gold nanoparticles

Dopamine (DA) is one of the most essential catecholamine neurotransmitters in the human body. A rapid colorimetric detection method for DA in urine and serum was established in this work using unmodified iodide-responsive copper-gold nanoparticles (Cu-Au NPs). The detection method provides a rapid response with color variability within 15 min at room temperature. In addition, the colorimetric probe has elevated stability, excellent selectivity and resistance to interference.

Crif1 deficiency in dopamine neurons triggers early-onset parkinsonism

Mitochondrial dysfunction has been implicated in Parkinson's Disease (PD) progression; however, the mitochondrial factors underlying the development of PD symptoms remain unclear. One candidate is CR6-interacting factor1 (CRIF1), which controls translation and membrane insertion of 13 mitochondrial proteins involved in oxidative phosphorylation. Here, we found that CRIF1 mRNA and protein expression were significantly reduced in postmortem brains of elderly PD patients compared to normal controls. To evaluate the effect of Crif1 deficiency, we produced mice lacking the Crif1 gene in dopaminergic neurons (DAT-CRIF1-KO mice). From 5 weeks of age, DAT-CRIF1-KO mice began to show decreased dopamine production with progressive neuronal degeneration in the nigral area. At ~10 weeks of age, they developed PD-like behavioral deficits, including gait abnormalities, rigidity, and resting tremor. L-DOPA, a medication used to treat PD, ameliorated these defects at an early stage, although it was ineffective in older mice. Taken together, the observation that CRIF1 expression is reduced in human PD brains and deletion of CRIF1 in dopaminergic neurons leads to early-onset PD with stepwise PD progression support the conclusion that CRIF1-mediated mitochondrial function is important for the survival of dopaminergic neurons.

The mGluR2/3 orthosteric agonist LY-404,039 reduces dyskinesia, psychosis-like behaviours and parkinsonism in the MPTP-lesioned marmoset

LY-404,039 is an orthosteric agonist of metabotropic glutamate 2 and 3 receptors (mGluR2/3) that may harbour additional agonist effect at dopamine D2 receptors. LY-404,039 and its pro-drug, LY-2140023, have previously entered clinical trials as treatment options for schizophrenia. They could therefore be repurposed, if proven efficacious, for other conditions, notably Parkinson's disease (PD). We have previously shown that the mGluR2/3 orthosteric agonist LY-354,740 alleviated L-3,4-dihydroxyphenylalanine (L-DOPA)-induced dyskinesia and psychosis-like behaviours (PLBs) in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-lesioned marmoset. Unlike LY-404,039, LY-354,740 does not stimulate dopamine D2 receptors, suggesting that LY-404,039 may elicit broader therapeutic effects in PD. Here, we sought to investigate the effect of this possible additional dopamine D2-agonist action of LY-404,039 by assessing its efficacy on dyskinesia, PLBs and parkinsonism in the MPTP-lesioned marmoset. We first determined the pharmacokinetic profile of LY-404,039 in the marmoset, in order to select doses resulting in plasma concentrations known to be well tolerated in the clinic. Marmosets were then injected L-DOPA with either vehicle or LY-404,039 (0.1, 0.3, 1 and 10 mg/kg). The addition of LY-404,039 10 mg/kg to L-DOPA resulted in a significant reduction of global dyskinesia (by 55%, P < 0.01) and PLBs (by 50%, P < 0.05), as well as reduction of global parkinsonism (by 47%, P < 0.05). Our results provide additional support of the efficacy of mGluR2/3 orthosteric stimulation at alleviating dyskinesia, PLBs and parkinsonism. Because LY-404,039 has already been tested in clinical trials, it could be repurposed for indications related to PD.

Targeting calcium homeostasis and impaired inter-organelle crosstalk as a potential therapeutic approach in Parkinson's disease

Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by the loss of dopaminergic neurons in the substantia nigra pars compacta, leading to motor symptoms such as tremors, rigidity, and bradykinesia. Current therapeutic strategies for PD are limited and mainly involve symptomatic relief, with no available treatment for the underlying causes of the disease. Therefore, there is a need for new therapeutic approaches that target the underlying pathophysiological mechanisms of PD. Calcium homeostasis is an essential process for maintaining proper cellular function and survival, including neuronal cells. Calcium dysregulation is also observed in various organelles, including the endoplasmic reticulum (ER), mitochondria, and lysosomes, resulting in organelle dysfunction and impaired inter-organelle communication. The ER, as the primary calcium reservoir, is responsible for folding proteins and maintaining calcium homeostasis, and its dysregulation can lead to protein misfolding and neurodegeneration. The crosstalk between ER and mitochondrial calcium signaling is disrupted in PD, leading to neuronal dysfunction and death. In addition, a lethal network of calcium cytotoxicity utilizes mitochondria, ER and lysosome to destroy neurons. This review article focused on the complex role of calcium dysregulation and its role in aggravating functioning of organelles in PD so as to provide new insight into therapeutic strategies for treating this disease. Targeting dysfunctional organelles, such as the ER and mitochondria and lysosomes and whole network of calcium dyshomeostasis can restore proper calcium homeostasis and improve neuronal function. Additionally targeting calcium dyshomeostasis that arises from miscommunication between several organelles can be targeted so that therapeutic effects of calcium are realised in whole cellular territory.

Plant derived active compounds of ayurvedic neurological formulation, Saraswatharishta as a potential dual leucine zipper kinase inhibitor: an in-silico study

Recent findings have highlighted the essential role of dual leucine zipper kinase (DLK) in neuronal degeneration. Saraswatharishta (SWRT), an ayurvedic formulation utilized in traditional Indian medicine, has demonstrated effectiveness in addressing neurodegenerative diseases. Herein, we aim to delve into the atomistic details of the mode of action of phytochemicals present in SWRT against DLK. Our screening process encompassed over 500 distinct phytochemicals derived from the main ingredients of the SWRT formulation. Through a comparative analysis of docking scores and relative poses, we successfully identified four novel compounds, which underwent further investigation via 2 × 500 ns long molecular dynamics (MD) simulations. Among the top four compounds, CID16066851 sourced from the Acorus calamus displayed the most stable complex with DLK. The molecular mechanics Poisson - Boltzmann surface area (MM-PBSA) calculations highlighted the significance of electrostatic and van der Waals interactions in the binding recognition process. Additionally, we identified key residues, namely Phe192, Leu243, Val139, and Leu141, as hotspots that predominantly govern the DLK-inhibitor interaction. Notably, the leading compounds are sourced from the Acorus calamus, Syzygium aromaticum, Zingiber officinale, and Anethum sowa plants present in the SWRT formulation. Overall, the findings of our study hold promise for future drug development endeavors combating neurodegenerative conditions.Communicated by Ramaswamy H. Sarma.

Truncation or proteolysis of α-synuclein in Parkinsonism

Posttranslational modifications of α-synuclein, such as truncation or abnormal proteolysis, are implicated in Parkinson's disease (PD), dementia with Lewy bodies (DLB), and multiple system atrophy (MSA). A key focus of this article includes the proteases responsible for inducing truncation, the specific sites susceptible to truncation, and the resultant influence of these truncated species on the seeding and aggregation of endogenous α-synuclein. We also shed light on the unique structural attributes of these truncated species, and how these modifications can lead to distinctive forms of synucleinopathies. In addition, we explore the comparative toxic potentials of various α-synuclein species. An extensive analysis of available evidence of truncated α-synuclein species in human-synucleinopathy brains is also provided. Lastly, we delve into the detrimental impact of truncated species on key cellular structures such as the mitochondria and endoplasmic reticulum. Our article discusses enzymes involved in α-synuclein truncation, including 20 S proteasome, cathepsins, asparagine endopeptidase, caspase-1, calpain-1, neurosin/kallikrein-6, matrix metalloproteinase-1/-3, and plasmin. Truncation patterns impact α-synuclein aggregation - C-terminal truncation accelerates aggregation with larger truncations correlated with shortened aggregation lag times. N-terminal truncation affects aggregation differently based on the truncation location. C-terminally truncated α-synuclein forms compact, shorter fibrils compared to the full-length (FL) protein. N-terminally truncated monomers form fibrils similar in length to FL α-synuclein. Truncated forms show distinct fibril morphologies, increased β-sheet structures, and greater protease resistance. Misfolded α-synuclein can adopt various conformations, leading to unique aggregates and distinct synucleinopathies. Fibrils, with prion-like transmission, are potentially more toxic than oligomers, though this is still debated. Different α-synuclein variants with N- and C-terminal truncations, namely 5-140, 39-140, 65-140, 66-140, 68-140, 71-140, 1-139, 1-135, 1-133, 1-122, 1-119, 1-115, 1-110, and 1-103 have been found in PD, DLB, and MSA patients' brains. In Parkinsonism, excess misfolded α-synuclein overwhelms the proteasome degradation system, resulting in truncated protein production and accumulation in the mitochondria and endoplasmic reticulum.

Zinc finger transcription factor CASZ1b is involved in the DNA damage response in live cells

Zinc finger transcription factor CASZ1b is essential for nervous system development and suppresses neuroblastoma growth. Our previous study showed that CASZ1b interacts with DNA repair proteins, however, whether CASZ1b is involved in the DNA damage response remains unclear. In this study, we investigated the kinetic recruitment of CASZ1b to sites of DNA damage upon induction by laser microirradiation. We find that CASZ1b is transiently recruited to sites of DNA damage in multiple cell lines. Mutagenesis of either the poly-(ADP-ribose) (PAR) binding motif or NuRD complex binding region in CASZ1b significantly reduces the recruitment of CASZ1b to these sites of DNA damage (∼65% and ∼30%, respectively). In addition, treatment of cells with a poly-(ADP-ribose) polymerase (PARP) inhibitor significantly attenuates the recruitment of CASZ1b to these DNA damaged sites. Loss of CASZ1 increases cell sensitivity to DNA damage induced by gamma irradiation as shown by decreased colony formation. Our studies reveal that CASZ1b is transiently recruited to DNA damage sites mainly in a PARP-dependent way and regulates cell sensitivity to DNA damage. Our results suggest that CASZ1b has a role, although perhaps a minor one, in the DNA damage response and ultimately regulating the efficiency of DNA repair during normal development and tumorigenesis.

UBL3 Interacts with Alpha-Synuclein in Cells and the Interaction Is Downregulated by the EGFR Pathway Inhibitor Osimertinib

Ubiquitin-like 3 (UBL3) acts as a post-translational modification (PTM) factor and regulates protein sorting into small extracellular vesicles (sEVs). sEVs have been reported as vectors for the pathology propagation of neurodegenerative diseases, such as α-synucleinopathies. Alpha-synuclein (α-syn) has been widely studied for its involvement in α-synucleinopathies. However, it is still unknown whether UBL3 interacts with α-syn, and is influenced by drugs or compounds. In this study, we investigated the interaction between UBL3 and α-syn, and any ensuing possible functional and pathological implications. We found that UBL3 can interact with α-syn by the Gaussia princeps based split luciferase complementation assay in cells and immunoprecipitation, while cysteine residues at its C-terminal, which are considered important as PTM factors for UBL3, were not essential for the interaction. The interaction was upregulated by 1-methyl-4-phenylpyridinium exposure. In drug screen results, the interaction was significantly downregulated by the treatment of osimertinib. These results suggest that UBL3 interacts with α-syn in cells and is significantly downregulated by epidermal growth factor receptor (EGFR) pathway inhibitor osimertinib. Therefore, the UBL3 pathway may be a new therapeutic target for α-synucleinopathies in the future.

CRISPR/Cas9 assisted stem cell therapy in Parkinson's disease

Since its discovery in 2012, CRISPR Cas9 has been tried as a direct treatment approach to correct the causative gene mutation and establish animal models in neurodegenerative disorders. Since no strategy developed until now could completely cure Parkinson's disease (PD), neuroscientists aspire to use gene editing technology, especially CRISPR/Cas9, to induce a permanent correction in genetic PD patients expressing mutated genes. Over the years, our understanding of stem cell biology has improved. Scientists have developed personalized cell therapy using CRISPR/Cas9 to edit embryonic and patient-derived stem cells ex-vivo. This review details the importance of CRISPR/Cas9-based stem cell therapy in Parkinson's disease in developing PD disease models and developing therapeutic strategies after elucidating the possible pathophysiological mechanisms.

State of the Art of microRNAs Signatures as Biomarkers and Therapeutic Targets in Parkinson's and Alzheimer's Diseases: A Systematic Review and Meta-Analysis

Identifying target microRNAs (miRNAs) might serve as a basis for developing advanced therapies for Parkinson's disease (PD) and Alzheimer's disease. This review aims to identify the main therapeutic targets of miRNAs that can potentially act in Parkinson's and Alzheimer's diseases. The publication research was conducted from May 2021 to March 2022, selected from Scopus, PubMed, Embase, OVID, Science Direct, LILACS, and EBSCO. A total of 25 studies were selected from 1549 studies evaluated. The total number of miRNAs as therapeutic targets evidenced was 90 for AD and 54 for PD. An average detection accuracy of above 84% for the miRNAs was observed in the selected studies of AD and PD. The major signatures were miR-26b-5p, miR-615-3p, miR-4722-5p, miR23a-3p, and miR-27b-3p for AD and miR-374a-5p for PD. Six miRNAs of intersection were found between AD and PD. This article identified the main microRNAs as selective biomarkers for diagnosing PD and AD and therapeutic targets through a systematic review and meta-analysis. This article can act as a microRNA guideline for laboratory research and pharmaceutical industries for treating Alzheimer's and Parkinson's diseases and offers the opportunity to evaluate therapeutic interventions earlier in the disease process.

Molecular and neural roles of sodium-glucose cotransporter 2 inhibitors in alleviating neurocognitive impairment in diabetic mice

Diabetes causes a variety of molecular changes in the brain, making it a real risk factor for the development of cognitive dysfunction. Complex pathogenesis and clinical heterogeneity of cognitive impairment makes the efficacy of current drugs limited. Sodium-glucose cotransporter 2 inhibitors (SGLT2i) gained our attention as drugs with potential beneficial effects on the CNS. In the present study, these drugs ameliorated the cognitive impairment associated with diabetes. Moreover, we verified whether SGLT2i can mediate the degradation of amyloid precursor protein (APP) and modulation of gene expression (Bdnf, Snca, App) involved in the control of neuronal proliferation and memory. The results of our research proved the participation of SGLT2i in the multifactorial process of neuroprotection. SGLT2i attenuate the neurocognitive impairment through the restoration of neurotrophin levels, modulation of neuroinflammatory signaling, and gene expression of Snca, Bdnf, and App in the brain of diabetic mice. The targeting of the above-mentioned genes is currently seen as one of the most promising and developed therapeutic strategies for diseases associated with cognitive dysfunction. The results of this work could form the basis of a future administration of SGLT2i in diabetics with neurocognitive impairment.

Small molecule-based fluorescent probes for the detection of α-Synuclein aggregation states

The formation of aggregates due to protein misfolding is encountered in various neurodegenerative diseases. α-Synuclein (α-Syn) aggregation is linked to Parkinson's disease (PD). It is one of the most prevalent neurodegenerative disorders after Alzheimer's disease. Aggregation of α-Syn is associated with Lewy body formation and degeneration of the dopaminergic neurons in the brain. These are the pathological hallmarks of PD progression. α-Syn aggregates in a multi-step process. The native unstructured α-Syn monomers combine to form oligomers, followed by amyloid fibrils, and finally Lewy bodies. Recent evidence suggests that α-Syn oligomerization and fibrils formation play major roles in PD development. α-Syn oligomeric species is the main contributor to neurotoxicity. Therefore, the detection of α-Syn oligomers and fibrils has drawn significant attention for potential diagnostic and therapeutic development. In this regard, the fluorescence strategy has become the most popular approach for following the protein aggregation process. Thioflavin T (ThT) is the most frequently used probe for monitoring amyloid kinetics. Unfortunately, it suffers from several significant drawbacks including the inability to detect neurotoxic oligomers. Researchers developed several small molecule-based advanced fluorescent probes compared to ThT for the detection/monitoring of α-Syn aggregates states. These are summarized here.

Programmable macromolecule-based RNA-targeting therapies to treat human neurological disorders

Disruptions in RNA processing play critical roles in the pathogenesis of neurological diseases. In this Perspective, we discuss recent progress in the development of RNA-targeting therapeutic modalities. We focus on progress, limitations, and opportunities in a new generation of therapies engineered from RNA binding proteins and other endogenous RNA regulatory macromolecules to treat human neurological disorders.

Tat-GSTpi Inhibits Dopaminergic Cells against MPP+-Induced Cellular Damage via the Reduction of Oxidative Stress and MAPK Activation

Glutathione S-transferase pi (GSTpi) is a member of the GST family and plays many critical roles in cellular processes, including anti-oxidative and signal transduction. However, the role of anti-oxidant enzyme GSTpi against dopaminergic neuronal cell death has not been fully investigated. In the present study, we investigated the roles of cell permeable Tat-GSTpi fusion protein in a SH-SY5Y cell and a Parkinson’s disease (PD) mouse model. In the 1-methyl-4-phenylpyridinium (MPP+)-exposed cells, Tat-GSTpi protein decreased DNA damage and reactive oxygen species (ROS) generation. Furthermore, this fusion protein increased cell viability by regulating MAPKs, Bcl-2, and Bax signaling. In addition, Tat-GSTpi protein delivered into the substantia nigra (SN) of mice brains protected dopaminergic neuronal cell death in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD animal model. Our results indicate that the Tat-GSTpi protein inhibited cell death from MPP+- and MPTP-induced damage, suggesting that it plays a protective role during the loss of dopaminergic neurons in PD and that it could help to identify the mechanism responsible for neurodegenerative diseases, including PD.

What Do Randomized Controlled Trials Inform Us About Potential Disease-Modifying Strategies for Parkinson's Disease?

Research advances have shed new insight into cellular pathways contributing to PD pathogenesis and offer increasingly compelling therapeutic targets. In this review, we made a broad survey of the published literature that report possible disease-modifying effects on PD. While there are many studies that demonstrate benefits for various therapies for PD in animal and human studies, we confined our search to human "randomised controlled trials" and with the key words "neuroprotection" or "disease-modifying". It is hoped that through studying the results of these trials, we might clarify possible mechanisms that underlie idiopathic PD. This contrasts with studying the effect of pathophysiology of familial PD, which could be carried out by gene knockouts and animal models. Randomised controlled trials indicate promising effects of MAO-B inhibitors, dopamine agonists, NMDA receptor antagonists, metabotropic glutamate receptor antagonists, therapies related to improving glucose utilization and energy production, therapies related to reduction of excitotoxicity and oxidative stress, statin use, therapies related to iron chelation, therapies related to the use of phytochemicals, and therapies related to physical exercise and brain reward pathway on slowing PD progression. Cumulatively, these approaches fall into two categories: direct enhancement of dopaminergic signalling, and reduction of neurodegeneration. Overlaps between the two categories result in challenges in distinguishing between symptomatic versus disease-modifying effects with current clinical trial designs. Nevertheless, a broad-based approach allows us to consider all possible therapeutic avenues which may be neuroprotective. While the traditional standard of care focuses on symptomatic management with dopaminergic drugs, more recent approaches suggest ways to preserve dopaminergic neurons by attenuating excitotoxicity and oxidative stress.

C/EBPβ/AEP is age-dependently activated in Parkinson's disease and mediates α-synuclein in the gut and brain

Parkinson's disease (PD) is the most common neurodegenerative motor disorder, and its pathologic hallmarks include extensive dopaminergic neuronal degeneration in the Substantia nigra associated with Lewy bodies, predominantly consisting of phosphorylated and truncated α-Synuclein (α-Syn). Asparagine endopeptidase (AEP) cleaves human α-Syn at N103 residue and promotes its aggregation, contributing to PD pathogenesis. However, how AEP mediates Lewy body pathologies during aging and elicits PD onset remains incompletely understood. Knockout of AEP or C/EBPβ from α-SNCA mice, and their chronic rotenone exposure models were used, and the mechanism of α-Syn from the gut that spread to the brain was observed. Here we report that C/EBPβ/AEP pathway, aggravated by oxidative stress, is age-dependently activated and cleaves α-Syn N103 and regulates Lewy body-like pathologies spreading from the gut into the brain in human α-SNCA transgenic mice. Deletion of C/EBPβ or AEP substantially diminished the oxidative stress, neuro-inflammation, and PD pathologies, attenuating motor dysfunctions in aged α-SNCA mice. Noticeably, PD pathologies initiate in the gut and progressively spread into the brain. Chronic gastric exposure to a low dose of rotenone initiates Lewy body-like pathologies in the gut that propagate into the brain in a C/EBPβ/AEP-dependent manner. Hence, our studies demonstrate that C/EBPβ/AEP pathway is critical for mediating Lewy body pathology progression in PD.

α-Synuclein as a Target for Metallo-Anti-Neurodegenerative Agents

The unique thermodynamic and kinetic coordination chemistry of ruthenium allows it to modulate key adverse aggregation and membrane interactions of α-synuclein (α-syn) associated with Parkinson's disease. We show that the low-toxic Ru^III complex trans-[ImH][RuCl₄ (Me₂ SO)(Im)] (NAMI-A) has dual inhibitory effects on both aggregation and membrane interactions of α-syn with submicromolar affinity, and disassembles pre-formed fibrils. NAMI-A abolishes the cytotoxicity of α-syn towards neuronal cells and mitigates neurodegeneration and motor impairments in a rat model of Parkinson's. Multinuclear NMR and MS analyses show that NAMI-A binds to residues involved in protein aggregation and membrane binding. NMR studies reveal the key steps in pro-drug activation and the effect of activated NAMI-A species on protein folding. Our findings provide a new basis for designing ruthenium complexes which could mitigate α-syn-induced Parkinson's pathology differently from organic agents.

Studying the trafficking of labeled trodusquemine and its application as nerve marker for light-sheet and expansion microscopy

Trodusquemine is an aminosterol with a variety of biological and pharmacological functions, such as acting as an antimicrobial, stimulating body weight loss and interfering with the toxicity of proteins involved in the development of Alzheimer's and Parkinson's diseases. The mechanisms of interaction of aminosterols with cells are, however, still largely uncharacterized. Here, by using fluorescently labeled trodusquemine (TRO-A594 and TRO-ATTO565), we show that trodusquemine binds initially to the plasma membrane of living cells, that the binding affinity is dependent on cholesterol, and that trodusquemine is then internalized and mainly targeted to lysosomes after internalization. We also found that TRO-A594 is able to strongly and selectively bind to myelinated fibers in fixed mouse brain slices, and that it is a marker compatible with tissue clearing and light-sheet fluorescence microscopy or expansion microscopy. In conclusion, this work contributes to further characterize the biology of aminosterols and provides a new tool for nerve labeling suitable for the most advanced microscopy techniques.

Impact of Reactive Species on Amino Acids-Biological Relevance in Proteins and Induced Pathologies

This review examines the impact of reactive species RS (of oxygen ROS, nitrogen RNS and halogens RHS) on various amino acids, analyzed from a reactive point of view of how during these reactions, the molecules are hydroxylated, nitrated, or halogenated such that they can lose their capacity to form part of the proteins or peptides, and can lose their function. The reactions of the RS with several amino acids are described, and an attempt was made to review and explain the chemical mechanisms of the formation of the hydroxylated, nitrated, and halogenated derivatives. One aim of this work is to provide a theoretical analysis of the amino acids and derivatives compounds in the possible positions. Tyrosine, methionine, cysteine, and tryptophan can react with the harmful peroxynitrite or ^•OH and ^•NO₂ radicals and glycine, serine, alanine, valine, arginine, lysine, tyrosine, histidine, cysteine, methionine, cystine, tryptophan, glutamine and asparagine can react with hypochlorous acid HOCl. These theoretical results may help to explain the loss of function of proteins subjected to these three types of reactive stresses. We hope that this work can help to assess the potential damage that reactive species can cause to free amino acids or the corresponding residues when they are part of peptides and proteins.

Nanozyme-based cascade SPR signal amplification for immunosensing of nitrated alpha-synuclein

A self-assembled nanozyme of iron porphyrin mediated supramolecular modified gold nanoparticles (FpA) was fabricated to determine nitrated alpha-synuclein as the Tyr 39 residue (nT39 α-Syn) of a potential biomarker for early diagnosis of Parkinson's disease (PD). Mechanically, localized surface plasmon resonance (LSPR) and the mass effect caused by catalytic deposition of the nanozyme contributed to a cascade signal amplification strategy. The sensor allowed a signal amplification and selective nT39 α-Syn bioanalysis with a 1.34-fold enhancement by cascade amplified SPR signal and double specific recognition. The detection limit was 1.78 ng/mL in the detection range of 7-240 ng/mL. Benefiting from the excellent immunosensor, this method can distinguish healthy people and PD patients using actual samples. Overall, this strategy provides a nanozyme-based biosensing platform for the early diagnosis of PD and can be applied to detect other protein biomarkers, such as PD-L1.

Effects of eugenol on the behavioral and pathological progression in the MPTP-induced Parkinson's disease mouse model

Parkinson's disease (PD) is the world's second most common neurological disorder. Oxidative stress and neuroinflammation play a crucial role in the pathogenesis of PD. Eugenol is a phytochemical with potent antioxidant and anti-inflammatory activity. The present investigation is aimed to study the effect of eugenol in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) induced mouse model of PD and its relationship to antioxidant effect. The effects of seven days of oral pre-treatment and post-treatment with three doses of eugenol (25, 50 and 100 mg/kg/day) were investigated against the MPTP-induced PD mouse model. In addition to the assessment of behavioural parameters using various tests (actophotometer, beam walking test, catalepsy, rearing, rotarod), biochemical parameters including lipid peroxidation and reduced glutathione levels in brain tissues, were also estimated in this study. The binding mode of eugenol in the human myeloid differentiation factor-2 (hMD-2) was also studied. Results showed that MPTP administration in mice resulted in the development of motor dysfunction (impaired motor coordination and hypo locomotion) similar to that of PD in different behavioural studies. Pre-treatment with eugenol reversed motor dysfunction caused by MPTP administration while post-treatment with eugenol at a high dose aggravated the symptoms of akinesia associated with MPTP administration. MPTP resulted in increased lipid peroxidation while decreased reduced glutathione levels in the brains of mice. MPTP-induced increased lipid peroxidation and attenuated levels of reduced glutathione were found to be alleviated with eugenol pre-treatment while augmented with eugenol post-treatment. Eugenol showed a binding affinity of -6.897 kcal/mol against the MD2 coreceptor of toll-like receptor-4 (TLR4). Biochemical, as well as neurobehavioral studies, showed that eugenol is having a protective effect, but does not have a curative effect on PD.

Polymorphism in alpha-synuclein oligomers and its implications in toxicity under disease conditions

The major hallmark of Parkinson’s disease (PD) is represented by the formation of pathological protein plaques largely consisting of α-synuclein (αSN) amyloid fibrils. Nevertheless, the implications of αSN oligomers in neuronal impairments and disease progression are more importantly highlighted than mature fibrils, as they provoke more detrimental damages in neuronal cells and thereby exacerbate α-synucleinopathy. Interestingly, although generation of oligomeric species under disease conditions is likely correlated to cytotoxicity and different cellular damages, αSN oligomers manifest varying toxicity profiles dependent on the specific environments as well as the shapes and conformations the oligomers adopt. As such, this minireview discusses polymorphism in αSN oligomers and the association of the underlying heterogeneity in regard to toxicity under pathological conditions.

Molecular dynamics simulations of an α-synuclein NAC domain fragment with a ff14IDPSFF IDP-specific force field suggest β-sheet intermediate states of fibrillation

For the discovery of treatments against synucleinopathies, it is necessary to unravel and fully understand the mechanism of fibrillation of proteins involved. Among them, α-synuclein (αS) plays a key role in the development of these diseases through its aggregation into oligomers found in Lewy bodies. However, its structural disorder as an intrinsically disordered protein (IDP) makes its characterization by experimental techniques arduously difficult. Atomistic simulations aim to provide insights into this blank canvas and, fortunately, some studies have already suggested promising mechanisms. Still, it is urgent to consider the IDP features in simulations, so recently a lot of force fields designed to deal with IDPs have been developed. In this study, we have carried out a total of 12 μs simulations of an αS core fragment using a popular ff14SB AMBER force field and the ff14IDPSFF variation that includes a grid-based energy correction map (CMAP) method. The predicted chemical shifts from the simulations and those measured from the αS protein in the NMR solution indicate that ff14IDPSFF reproduces the experimental data more accurately. Moreover, structural analysis exhibits opposite trends between secondary structure propensities. The ff14SB force field preserves the α-helices found in the micelle-bound αS structure, which is used as an initial conformation, while ff14IDPSFF stands out with increased structural disorder and the formation of β-sheets, which suggests that the IDP-specific force field can capture more suitable conformations representing the possible intermediate states of the fibrillation process.

The Relationship between Procyanidin Structure and Their Protective Effect in a Parkinson's Disease Model

This study evaluated the effect of grape seed-derived monomer, dimeric, and trimeric procyanidins on rat pheochromocytoma cell line (PC12) cells and in a zebrafish Parkinson’s disease (PD) model. PC12 cells were cultured with grape seed-derived procyanidins or deprenyl for 24 h and then exposed to 1.5 mm 1-methyl-4-phenylpyridinium (MPP⁺) for 24 h. Zebrafish larvae (AB strain) 3 days post-fertilization were incubated with deprenyl or grape seed-derived procyanidins in 400 µM 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) for 4 days. The results showed that the procyanidin dimers procyanidin B1 (B1), procyanidin B2 (B2), procyanidin B3 (B3), procyanidin B4 (B4), procyanidin B1-3-O-gallate (B1-G), procyanidin B2-3-O-gallate (B2-G), and the procyanidin trimer procyanidin C1 (C1) had a protective effect on PC12 cells, decreasing the damaged dopaminergic neurons and motor impairment in zebrafish. In PC12 cells and the zebrafish PD model, procyanidin (B1, B2, B3, B4, B1-G, B2-G, C1) treatment decreased the content of reactive oxygen species (ROS) and malondialdehyde (MDA), increased the activity of antioxidant enzymes glutathione peroxidase (GSH-Px), catalase (CAT), and superoxide dismutase (SOD), and upregulated the expression of nuclear factor-erythroid 2-related factor (Nrf2), NAD(P)H: quinone oxidoreductase 1 (NQO1), and heme oxygenase-1 (HO-1). These results suggest that in PC12 cells and the zebrafish PD model, the neuroprotective effects of the procyanidins were positively correlated with their degree of polymerization.

Garcinia morella extract confers dopaminergic neuroprotection by mitigating mitochondrial dysfunctions and inflammation in mouse model of Parkinson's disease

Dopaminergic neuroprotection is the main interest in designing novel therapeutics against Parkinson's disease (PD). In the process of dopaminergic degeneration, mitochondrial dysfunctions and inflammation are significant. While the existing drugs provide symptomatic relief against PD, a therapy conferring total neuroprotection by targeting multiple degenerative pathways is still lacking. Garcinia morella is a common constituent of Ayurvedic medication and has been used for the treatment of inflammatory disorders. The present study investigates whether administration of G. morella fruit extract (GME) in MPTP mouse model of PD protects against dopaminergic neurodegeneration, including the underlying pathophysiologies, and reverses the motor behavioural abnormalities. Administration of GME prevented the loss of dopaminergic cell bodies in the substantia nigra and its terminals in the corpus striatum of PD mice. Subsequently, reversal of parkinsonian behavioural abnormalities, viz. akinesia, catalepsy, and rearing, was observed along with the recovery of striatal dopamine and its metabolites in the experimental model. Furthermore, reduced activity of the mitochondrial complex II in the nigrostriatal pathway of brain of the mice was restored after the administration of GME. Also, MPTP-induced enhanced activation of Glial fibrillary acidic protein (GFAP) and neuronal nitric oxide synthase (nNOS) in the nigrostriatal pathway, which are the markers of inflammatory stress, were found to be ameliorated on GME treatment. Thus, our study presented a novel mode of dopaminergic neuroprotection by G. morella in PD by targeting the mitochondrial dysfunctions and neuroinflammation, which are considered to be intricately associated with the loss of dopaminergic neurons.