The SH-SY5Y cell line in Parkinson's disease research: a systematic review

cPGA hydrolase assay of DJ-1 in crude cell lysates: Implications for sensing of oxidative stress

Cyclic 3-phosphosphoglyceric anhydride (cPGA), a side product of glycolysis, acylates cellular amines and thiols to form amides and thioesters, respectively. Since these acylation reactions are harmful, organisms rely on a protein, known as DJ-1 in humans, to inactivate cPGA. Inactivation of cPGA likely plays a significant role in cytoprotection by DJ-1, but further progress in this direction is hampered by the lack of quantitative assays to measure the cPGA hydrolase activity of DJ-1 in biological samples. Here we report an optimized procedure for preparation of cPGA which is then used as a substrate to quantify enzymatic activity of DJ-1. The end-point assay for cPGA hydrolase uses dilute cell lysates to hydrolyze cPGA for 0.5-3.5 min followed by conversion of the remaining cPGA into thioester for spectrophotometric quantitation. We illustrate the utility of this assay by showing that higher levels of cPGA hydrolase activity result in better protection from acylation by cPGA. Moreover, the decrease of cPGA hydrolase activity due to oxidation of the catalytic cysteine of DJ-1 under oxidative stress and its subsequent recovery can be monitored using the assay. This relatively simple assay allows functional characterization of DJ-1 in biological samples through quantitative assessment of its cPGA hydrolase activity.

Retinoic acid in Parkinson's disease: Molecular insights, therapeutic advances, and future prospects

Parkinson's disease (PD) is a common and progressively worsening neurodegenerative disorder characterized by abnormal protein homeostasis and the degeneration of dopaminergic neurons, particularly in the substantia nigra pars compacta. The prevalence of PD has doubled in the past 25 years, now affecting over 8.5 million individuals worldwide, underscoring the need for effective management strategies. While current pharmacological therapies provide symptom relief, they face challenges in treating advanced PD stages. Recent research highlights the therapeutic benefits of retinoic acid (RA) in PD, demonstrating its potential to mitigate neuroinflammation and oxidative stress, regulate brain aging, promote neuronal plasticity, and influence circadian rhythm gene expression and retinoid X receptor heterodimerization. Additionally, RA helps maintain intestinal homeostasis and modulates the enteric nervous system, presenting significant therapeutic potential for managing PD. This review explores RA as a promising alternative to conventional therapies by summarizing the molecular mechanisms underlying its role in PD pathophysiology and presenting up-to-date insights into both preclinical and clinical studies of RA in PD treatment. It also delves into cutting-edge formulations incorporating RA, highlighting ongoing efforts to refine therapeutic strategies by integrating RA into novel treatments. This comprehensive overview aims to advance progress in the field, contribute to the development of effective, targeted treatments for PD, and enhance patient well-being. Further research is essential to fully explore RA's therapeutic potential and validate its efficacy in PD treatment.

Novel neuroprotective 5,6-dihydropyrido[2',1':2,3]imidazo[4,5-c]quinoline derivatives acting through cholinesterase inhibition and CB2 signaling modulation

A novel group of 5,6-dihydropyrido [2',1':2,3]imidazo [4,5-c]quinolines was prepared via a microwave assisted one-pot telescopic approach. The synthetic sequence involves the formation of an amine precursor of imidazo [1,2-a]pyridine via condensation and reduction under microwave irradiation. Subsequently, the Pictet-Spengler cyclisation reaction occurs with ketones (cyclic or acyclic) to obtain substituted 5,6-dihydropyrido [2',1':2,3]imidazo [4,5-c]quinolines in excellent yields. The compounds were tested as neuroprotective agents. Observed protection of neuron-like cells, SH-SY5Y differentiated with ATRA, in Parkinson's and Huntington's disease models inspired further mechanistic studies of protective activity against damage induced by 1-methyl-4-phenylpyridinium (MPP+), a compound causing Parkinson's disease. The novel compounds exhibit similar or higher potency than ebselen, an established drug with antioxidant activity, in the cells against MPP + -induced total cellular superoxide production and cell death. However, they exhibit a significantly higher capacity to reduce mitochondrial superoxide and preserve mitochondrial membrane potential. We also observed marked differences between a selected derivative and ebselen in terms of normalizing MPP + -induced phosphorylation of Akt and ERK1/2. The cytoprotective activity was abrogated when signaling through cannabinoid receptor CB2 was blocked. The compounds also inhibit both acetylcholine and butyrylcholine esterases. Overall the data show that novel 5,6-dihydropyrido [2',1':2,3]imidazo [4,5-c]quinoline have a broad cytoprotective activity which is mediated by several mechanisms including mitoprotection.

Experimental models of Parkinson's disease: Challenges and Opportunities

Parkinson's disease (PD) is a widespread neurodegenerative disorder occurs due to the degradation of dopaminergic neurons present in the substantia nigra pars compacta (SNpc). Millions of people are affected by this devastating disorder globally, and the frequency of the condition increases with the increase in the elderly population. A significant amount of progress has been made in acquiring more knowledge about the etiology and the pathogenesis of PD over the past decades. Animal models have been regarded to be a vital tool for the exploration of complex molecular mechanisms involved in PD. Various animals used as models for disease monitoring include vertebrates (zebrafish, rats, mice, guinea pigs, rabbits and monkeys) and invertebrate models (Drosophila, Caenorhabditis elegans). The animal models most relevant for study of PD are neurotoxin induction-based models (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), 6-Hydroxydopamine (6-OHDA) and agricultural pesticides (rotenone, paraquat), pharmacological models (reserpine or haloperidol treated rats), genetic models (α-synuclein, Leucine-rich repeat kinase 2 (LRRK2), DJ-1, PINK-1 and Parkin). Several non-mammalian genetic models such as zebrafish, Drosophila and Caenorhabditis elegance have also gained popularity in recent years due to easy genetic manipulation, presence of genes homologous to human PD, and rapid screening of novel therapeutic molecules. In addition, in vitro models (SH-SY5Y, PC12, Lund human mesencephalic (LUHMES) cells, Human induced pluripotent stem cell (iPSC), Neural organoids, organ-on-chip) are also currently in trend providing edge in investigating molecular mechanisms involved in PD as they are derived from PD patients. In this review, we explain the current situation and merits and demerits of the various animal models.

Effective lowering of α-synuclein expression by targeting G-quadruplex structures within the SNCA gene

Alpha-synuclein, encoded by the SNCA gene, is a pivotal protein implicated in the pathogenesis of synucleinopathies, including Parkinson's disease. Current approaches for modulating alpha-synuclein levels involve antisense nucleotides, siRNAs, and small molecules targeting SNCA's 5'-UTR mRNA. Here, we propose a groundbreaking strategy targeting G-quadruplex structures to effectively modulate SNCA gene expression and lowering alpha-synuclein amount. Novel G-quadruplex sequences, identified on the SNCA gene's transcription starting site and 5'-UTR of SNCA mRNAs, were experimentally confirmed for their stability through biophysical assays and in vitro experiments on human genomic DNA. Biological validation in differentiated SH-SY5Y cells revealed that well-known G-quadruplex ligands remarkably stabilized these structures, inducing the modulation of SNCA mRNAs expression, and the effective decrease in alpha-synuclein amount. Besides, a novel peptide nucleic acid conjugate, designed to selectively disrupt of G-quadruplex within the SNCA gene promoter, caused a promising lowering of both SNCA mRNA and alpha-synuclein protein. Altogether our findings highlight G-quadruplexes' key role as intriguing biological targets in achieving a notable and successful reduction in alpha-synuclein expression, pointing to a novel approach against synucleinopathies.

Spastin regulates ER-mitochondrial contact sites and mitochondrial homeostasis

Mitochondria-endoplasmic reticulum (ER) contact sites (MERCs) emerged to play critical roles in numerous cellular processes, and their dysregulation has been associated to neurodegenerative disorders. Mutations in the SPG4 gene coding for spastin are among the main causes of hereditary spastic paraplegia (HSP). Spastin binds and severs microtubules, and the long isoform of this protein, namely M1, spans the outer leaflet of ER membrane where it interacts with other ER-HSP proteins. Here, we showed that overexpressed M1 spastin localizes in ER-mitochondria intersections and that endogenous spastin accumulates in MERCs. We demonstrated in different cellular models that downregulation of spastin enhances the number of MERCs, alters mitochondrial morphology, and impairs ER and mitochondrial calcium homeostasis. These effects are associated with reduced mitochondrial membrane potential, oxygen species levels, and oxidative metabolism. These findings extend our knowledge on the role of spastin in the ER and suggest MERCs deregulation as potential causes of SPG4-HSP disease.

Putative Adverse Outcome Pathway for Parkinson's Disease-like Symptoms Induced by Silicon Quantum Dots based on In Vivo/Vitro Approaches

Given the commercial proliferation of silicon quantum dots (SiQDs) and their inevitable environmental dispersal, this study critically examines their biological and public health implications, specifically regarding Parkinson's disease. The study investigated the toxicological impact of SiQDs on the onset and development of PD-like symptoms through the induction of ferroptosis, utilizing both in vivo [Caenorhabditis elegans (C. elegans)] and in vitro (SH-SY5Y neuroblastoma cell line) models. Our findings demonstrated that SiQDs, characterized by their stable and water-soluble physicochemical properties, tended to accumulate in neuronal tissues. This accumulation precipitated dopaminergic neurodegeneration, manifested as diminished dopamine-dependent behaviors, and escalated the expression of PD-specific genes in C. elegans. Importantly, the results revealed that SiQDs induced ferritinophagy, a selective autophagy pathway that triggered ferroptosis and resulted in PD-like symptoms, even exacerbating disease progression in biological models. These insights were incorporated into a putatively qualitative and quantitative adverse outcome pathway framework, highlighting the serious neurodegenerative risks posed by SiQDs through ferroptosis pathways. This study provides a multidisciplinary analysis critical for informing policy on the regulation of SiQDs exposure to safeguard susceptible populations and guiding the responsible development of nanotechnologies impacting environmental and public health.

Inflammation-free electrochemical in vivo sensing of dopamine with atomic-level engineered antioxidative single-atom catalyst

Electrochemical methods with tissue-implantable microelectrodes provide an excellent platform for real-time monitoring the neurochemical dynamics in vivo due to their superior spatiotemporal resolution and high selectivity and sensitivity. Nevertheless, electrode implantation inevitably damages the brain tissue, upregulates reactive oxygen species level, and triggers neuroinflammatory response, resulting in unreliable quantification of neurochemical events. Herein, we report a multifunctional sensing platform for inflammation-free in vivo analysis with atomic-level engineered Fe single-atom catalyst that functions as both single-atom nanozyme with antioxidative activity and electrode material for dopamine oxidation. Through high-temperature pyrolysis and catalytic performance screening, we fabricate a series of Fe single-atom nanozymes with different coordination configurations and find that the Fe single-atom nanozyme with FeN4 exhibits the highest activity toward mimicking catalase and superoxide dismutase as well as eliminating hydroxyl radical, while also featuring high electrode reactivity toward dopamine oxidation. These dual functions endow the single-atom nanozyme-based sensor with anti-inflammatory capabilities, enabling accurate dopamine sensing in living male rat brain. This study provides an avenue for designing inflammation-free electrochemical sensing platforms with atomic-precision engineered single-atom catalysts.

RIT2 regulates autophagy lysosomal pathway induction and protects against α-synuclein pathology in a cellular model of Parkinson's disease

Substantial work has been devoted to better understand the contribution of the myriad of genes that may underly the development of Parkinson's disease (PD) and their role in disease etiology. The small GTPase Ras-like without CAAX2 (RIT2) is one such genetic risk factor, with one single nucleotide polymorphism in the RIT2 locus, rs12456492, having been associated with PD risk in multiple populations. While RIT2 has previously been shown to influence signaling pathways, dopamine transporter trafficking, and LRRK2 activity, its cellular function remains unclear. In the current study, we have situated RIT2 to be upstream of various diverse processes associated with PD. In cellular models, we have shown that RIT2 is necessary for activity-dependent changes in the expression of genes related to the autophagy-lysosomal pathway (ALP) by regulating the nuclear translocation of MiT/TFE3-family transcription factors. RIT2 is also associated with lysosomes and can regulate autophagic flux and clearance by regulating lysosomal hydrolase expression and activity. Interestingly, upregulation of RIT2 can augment ALP flux and protect against α-synuclein aggregation in cortical neurons. Taken together, the present study suggests that RIT2 can regulates gene expression upstream of ALP function and that enhancing RIT2 activity may provide therapeutic benefit in PD.

Enriched Environment Contributes to the Recovery from Neurotoxin-Induced Parkinson's Disease Pathology

Parkinson's disease (PD) is a neurological disorder that affects dopaminergic neurons. The lack of understanding of the underlying molecular mechanisms of PD pathology makes treating it a challenge. Several pieces of evidence support the protective role of enriched environment (EE) and exercise on dopaminergic neurons. The specific aspect(s) of neuroprotection after exposure to EE have not been identified. Therefore, we have investigated the protective role of EE on dopamine dysregulation and subsequent downregulation of DJ1 protein using in vitro and in vivo models of PD. Our study for the first time demonstrated that DJ1 expression has a direct correlation with dopamine downregulation in PD models and exposure to EE has a significant impact on improving the behavioral changes in PD mice. This research provides evidence that exercise in EE has a positive effect on PD without interfering with the current line of therapy.

Proliferation of SH-SY5Y neuroblastoma cells on confined spaces

BACKGROUND

Microfluidics offers precise drug delivery and continuous monitoring of cell functions, which is crucial for studying the effects of toxins and drugs. Ensuring proper cell growth in these space-constrained systems is essential for obtaining consistent results comparable to standard Petri dishes.

NEW METHOD

We investigated the proliferation of SH-SY5Y cells on circular polycarbonate chambers with varying surface areas. SH-SY5Y cells were chosen for their relevance in neurodegenerative disease research.

RESULTS

Our study demonstrates a correlation between the chamber surface area and SH-SY5Y cell growth rates. Cells cultured in chambers larger than 10 mm in diameter exhibited growth comparable to standard 60-mm dishes. In contrast, smaller chambers significantly impeded growth, even at identical seeding densities. Similar patterns were observed for HeLaGFP cells, while 16HBE14σ cells proliferated efficiently regardless of chamber size. Additionally, SH-SY5Y cells were studied in a 12-mm diameter sealed chamber to assess growth under restricted gas exchange conditions.

COMPARISON WITH EXISTING METHODS

Our findings underscore the limitations of small chamber sizes in microfluidic systems for SH-SY5Y cells, an issue not typically addressed by conventional methods.

CONCLUSIONS

SH-SY5Y cell growth is highly sensitive to spatial constraints, with markedly reduced proliferation in chambers smaller than 10 mm. This highlights the need to carefully consider chamber size in microfluidic experiments to achieve cell growth rates comparable to standard culture dishes. The study also shows that while SH-SY5Y and HeLaGFP cells are affected by chamber size, 16HBE14σ cells are not. These insights are vital for designing effective microfluidic systems for bioengineering research.

Both Enantiomers of 2-Hydroxyglutarate Modulate the Metabolism of Cultured Human Neuroblastoma Cells

Elevated levels of D-2-hydroxyglutarate (D-2HG) and L-2-hydroxyglutarate (L-2HG) in the brain are associated with various pathological conditions, potentially contributing to neurological symptoms and neurodegeneration. Previous studies on animal models have revealed their capability to interfere with several cellular processes, including mitochondrial metabolism. Both enantiomers competitively inhibit the enzymatic activity of 2-oxoglutarate-dependent dioxygenases. These enzymes also execute several signaling cascades and regulate the level of covalent modifications on nucleic acids or proteins, e.g., methylation, hydroxylation, or ubiquitination, with an effect on epigenetic regulation of gene expression, protein stability, and intracellular signaling. To investigate the potential impact of 2HG enantiomers on human neuronal cells, we utilized the SH-SY5Y human neuroblastoma cell line as a model. We employed proton nuclear magnetic resonance (1H-NMR) spectroscopy of culture media that provided high-resolution insights into the changes in the content of metabolites. Concurrently, we performed biochemical assays to complement the 1H-NMR findings and to estimate the activities of lactate and 3-hydroxybutyrate dehydrogenases. Our results reveal that both 2HG enantiomers can influence the cellular metabolism of human neuroblastoma cells on multiple levels. Specifically, both enantiomers of 2HG comparably stimulate anaerobic metabolism of glucose and inhibit the uptake of several essential amino acids from the culture media. In this respect, both 2HG enantiomers decreased the catabolism capability of cells to incorporate the leucine-derived carbon atoms into their metabolism and to generate the ketone bodies. These results provide evidence that both enantiomers of 2HG have the potential to influence the metabolic and molecular aspects of human cells. Furthermore, we may propose that increased levels of 2HG enantiomers in the brain parenchyma may alter brain metabolism features, potentially contributing to the etiology of neurological symptoms in patients.

Diverse effects of synthetic glucocorticoid species on cell viability and stress response of neuroblastoma cells

Glucocorticoids (GCs) are widely used as powerful anti-inflammatory and immunosuppressive therapeutics in multiple pathological conditions. However, compelling evidence indicates that they might promote neurodegeneration by altering mitochondrial homeostatic processes. Although the effect of dexamethasone on cell survival and homeostasis has been widely investigated, the effect of other glucocorticoids needs to be explored in more detail. In this report, we have compared the neurotoxicity induced by dexamethasone, prednisolone, betamethasone, and hydrocortisone in cultured neuroblastoma cells, through the analysis of several parameters such as cell viability, ER stress, oxidative stress, and mitochondrial fusion and fission markers. Interestingly, we have found that synthetic glucocorticoids may impact neuronal viability by affecting different cellular responses, suggesting that their therapeutic use should be consciously decided after careful consideration of benefits and detrimental effects.

Distinct In Vitro Differentiation Protocols Differentially Affect Cytotoxicity Induced by Heavy Metals in Human Neuroblastoma SH-SY5Y Cells

The SH-SY5Y cell line is widely used in neurotoxicity studies. However, the effects of inducing cell differentiation on the cytotoxic effects of heavy metals are unclear. Therefore, we investigated the effects of mercuric chloride (HgCl2), cadmium chloride (CdCl2), arsenic trioxide (As2O3), and methylmercury (MeHg) on SH-SY5Y cells differentiated in the presence of insulin-like growth factor-I (IGF-I) or all-trans retinoic acid (ATRA). Neurite outgrowth with distinct changes in neuronal marker expression, phenotype, and cell cycle was induced in SH-SY5Y cells by IGF-I treatment for 1 day or ATRA treatment for up to 7 days. The cytotoxic effects of HgCl2 decreased at lower concentrations and increased at higher concentrations in both IGF-I- and ATRA-differentiated cells compared with those in undifferentiated cells. Differentiation with IGF-I, but not with ATRA, increased the cytotoxic effects of CdCl2. Decreased cytotoxic effects of As2O3 and MeHg were observed at lower concentrations in IGF-I-differentiated cells, whereas increased cytotoxic effects of As2O3 and MeHg were observed at higher concentrations in ATRA-differentiated cells. Changes in the cytotoxic effects of heavy metals were observed even after 1 day of ATRA exposure in SH-SY5Y cells. Our results demonstrate that the differentiation of SH-SY5Y cells by IGF-I and ATRA induces different cellular characteristics, resulting in diverse changes in sensitivity to heavy metals, which depend not only on the differentiation agents and treatment time but also on the heavy metal species and concentration.

Aquilaria crassna Extract Exerts Neuroprotective Effect against Benzo[a]pyrene-Induced Toxicity in Human SH-SY5Y Cells: An RNA-Seq-Based Transcriptome Analysis

Benzo[a]pyrene (B[a]P) is known to inhibit neurodifferentiation and induce neurodegeneration. Agarwood or Aquilaria crassna (AC), a plant with health-promoting properties, may counteract the neurotoxic effects of B[a]P by promoting neuronal growth and survival. This study investigated the protective effect of AC leaf ethanolic extract (ACEE) on the B[a]P-induced impairment of neuronal differentiation. A transcriptomic analysis identified the canonical pathway, the biological network, and the differentially expressed genes (DEGs) that are changed in response to neuronal differentiation and neurogenesis. Several genes, including CXCR4, ENPP2, GAP43, GFRA2, NELL2, NFASC, NSG2, NGB, BASP1, and NEUROD1, in B[a]P-treated SH-SY5Y cells were up-regulated after treatment with ACEE. Notably, a Western blot analysis further confirmed that ACEE increased the protein levels of GAP43 and neuroglobin. B[a]P treatment led to decreased phosphorylation of Akt and increased phosphorylation of ERK in SH-SY5Y cells; however, ACEE was able to reverse these effects. Clionasterol and lupenone were identified in ACEE. Molecular docking showed that these two phytochemicals had significant interactions with CXCR4, GDNF family receptor alpha (GFRA), and retinoid X receptors (RXRs). In conclusion, ACEE may be a potential alternative medicine for the prevention of impaired neuronal differentiation and neurodegenerative diseases.

A marine-derived antioxidant astaxanthin as a potential neuroprotective and neurotherapeutic agent: A review of its efficacy on neurodegenerative conditions

Astaxanthin is a potent lipid-soluble carotenoid produced by several different freshwater and marine microorganisms, including microalgae, bacteria, fungi, and yeast. The proven therapeutic effects of astaxanthin against different diseases have made this carotenoid popular in the nutraceutical market and among consumers. Recently, astaxanthin is also receiving attention for its effects in the co-adjuvant treatment or prevention of neurological pathologies. In this systematic review, studies evaluating the efficacy of astaxanthin against different neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, multiple sclerosis, cerebrovascular diseases, and spinal cord injury are analyzed. Based on the current literature, astaxanthin shows potential biological activity in both in vitro and in vivo models. In addition, its preventive and therapeutic activities against the above-mentioned diseases have been emphasized in studies with different experimental designs. In contrast, none of the 59 studies reviewed reported any safety concerns or adverse health effects as a result of astaxanthin supplementation. The preventive or therapeutic role of astaxanthin may vary depending on the dosage and route of administration. Although there is a consensus in the literature regarding its effectiveness against the specified diseases, it is important to determine the safe intake levels of synthetic and natural forms and to determine the most effective forms for oral intake.

DNA tetrahedral nanocages as a promising nanocarrier for dopamine delivery in neurological disorders

Dopamine is a neurotransmitter in the central nervous system that is essential for many bodily and mental processes, and a lack of it can cause Parkinson's disease. DNA tetrahedral (TD) nanocages are promising in bio-nanotechnology, especially as a nanocarrier. TD is highly programmable, biocompatible, and capable of cell differentiation and proliferation. It also has tissue and blood-brain barrier permeability, making it a powerful tool that could overcome potential barriers in treating neurological disorders. In this study, we used DNA TD as a carrier for dopamine to cells and zebrafish embryos. We investigated the mechanism of complexation between TD and dopamine hydrochloride using gel electrophoresis, fluorescence and circular dichroism (CD) spectroscopy, atomic force microscopy (AFM), and molecular dynamic (MD) simulation tools. Further, we demonstrate that these dopamine-loaded DNA TD nanostructures enhanced cellular uptake and differentiation ability in SH-SY5Y neuroblastoma cells. Furthermore, we extended the study to zebrafish embryos as a model organism to examine survival and uptake. The research provides valuable insights into the complexation mechanism and cellular uptake of dopamine-loaded DNA tetrahedral nanostructures, paving the way for further advancements in nanomedicine for Parkinson's disease and other neurological disorders.

NOX2-TRPM2 coupling promotes Zn2+ inhibition of complex III to exacerbate ROS production in a cellular model of Parkinson's disease

Reactive oxygen species (ROS) serve vital physiological functions, but aberrant ROS production contributes to numerous diseases. Unfortunately, therapeutic progress targeting pathogenic ROS has been hindered by the limited understanding of whether the mechanisms driving pathogenic ROS differ from those governing physiological ROS generation. To address this knowledge gap, we utilised a cellular model of Parkinson's disease (PD), as an exemplar of ROS-associated diseases. We exposed SH-SY5Y neuroblastoma cells to the PD-toxin, MPP+ (1-methyl-4-phenylpyridinium) and studied ROS upregulation leading to cell death, the primary cause of PD. We demonstrate: (1) MPP+ stimulates ROS production by raising cytoplasmic Ca2+ levels, rather than acting directly on mitochondria. (2) To raise the Ca2+, MPP+ co-stimulates NADPH oxidase-2 (NOX2) and the Transient Receptor Potential Melastatin2 (TRPM2) channel that form a positive feedback loop to support each other's function. (3) Ca2+ exacerbates mitochondrial ROS (mtROS) production not directly, but via Zn2+. (4) Zn2+ promotes electron escape from respiratory complexes, predominantly from complex III, to generate mtROS. These conclusions are drawn from data, wherein inhibition of TRPM2 and NOX2, chelation of Ca2+ and Zn2+, and prevention of electron escape from complexes -all abolished the ability of MPP+ to induce mtROS production and the associated cell death. Furthermore, calcium ionophore mimicked the effects of MPP+, while Zn2+ ionophore replicated the effects of both MPP+ and Ca2+. Thus, we unveil a previously unrecognized signalling circuit involving NOX2, TRPM2, Ca2+, Zn2+, and complex III that drives cytotoxic ROS production. This circuit lies dormant in healthy cells but is triggered by pathogenic insults and could therefore represent a safe therapeutic target for PD and other ROS-linked diseases.

Undifferentiated versus retinoic acid-differentiated SH-SY5Y cells in investigation of markers of neural function in toxicological research

The SH-SY5Y human neuroblastoma cell line is a standard in vitro experimental model of neuronal-like cells used in neuroscience and toxicological research. These cells can be differentiated into mature neurons, most commonly using retinoic acid (RA). Despite differences in characteristics, both undifferentiated and differentiated SH-SY5Y cells are used in research. However, due to uncertainties regarding the expression of specific markers of neural function in each culture, there is no definite conclusion on which culture is better suited for (neuro)toxicological and/or neuroscience investigations. To address this dilemma, we investigated the basal expression/activity of the key elements of acetylcholine, dopamine, serotonin, and GABA neurotransmitter pathways, along with the elements involved in exocytosis of neurotransmitters, and neuron electrophysiological activity in undifferentiated and in RA-differentiated SH-SY5Y cells using a six-day differentiation protocol. Our findings revealed that both SH-SY5Y cell types are functionally active. While undifferentiated SH-SY5Y cells exhibited greater multipotency in the expression of tested markers, most of those markers expressed in both cell types showed higher expression levels in RA-differentiated SH-SY5Y cells. Our results suggest that the six-day differentiation protocol with RA induces maturation, but not differentiation of the cells into specific neuron phenotype. The greater multipotency of undifferentiated cells in neural markers expression, together with their higher sensitivity to xenobiotic exposure and more simple cultivation protocols, make them a better candidate for high throughput toxicological screenings. Differentiated neurons are better suited for neuroscience researches that require higher expression of more specific neural markers and the specific types of neural cells.

Neuroprotective and Neurite Outgrowth Stimulating Effects of New Low-Basicity 5-HT7 Receptor Agonists: In Vitro Study in Human Neuroblastoma SH-SY5Y Cells

There is some evidence that the serotonin receptor subtype 7 (5-HT7) could be new therapeutic target for neuroprotection. The aim of this study was to compare the neuroprotective and neurite outgrowth potential of new 5-HT7 receptor agonists (AH-494, AGH-238, AGH-194) with 5-CT (5-carboxyamidotryptamine) in human neuroblastoma SH-SY5Y cells. The results revealed that 5-HT7 mRNA expression was significantly higher in retinoic acid (RA)-differentiated cells when compared to undifferentiated ones and it was higher in cell cultured in neuroblastoma experimental medium (DMEM) compared to those placed in neuronal (NB) medium. Furthermore, the safety profile of compounds was favorable for all tested compounds at concentration used for neuroprotection evaluation (up to 1 μM), whereas at higher concentrations (above 10 μM) the one of the tested compounds, AGH-194 appeared to be cytotoxic. While we observed relatively modest protective effects of 5-CT and AH-494 in UN-SH-SY5Y cells cultured in DMEM, in UN-SH-SY5Y cells cultured in NB medium we found a significant reduction of H2O2-evoked cell damage by all tested 5-HT7 agonists. However, 5-HT7-mediated neuroprotection was not associated with inhibition of caspase-3 activity and was not observed in RA-SH-SY5Y cells exposed to H2O2. Furthermore, none of the tested 5-HT7 agonists altered the damage induced by 6-hydroxydopamine (6-OHDA), 1-methyl-4-phenylpyridinium ion (MPP +) and doxorubicin (Dox) in UN- and RA-SH-SY5Y cells cultured in NB. Finally we showed a stimulating effect of AH-494 and AGH-194 on neurite outgrowth. The obtained results provide insight into neuroprotective and neurite outgrowth potential of new 5-HT7 agonists.

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

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

The biphasic role of Hspb1 on ferroptotic cell death in Parkinson's disease

Rationale: Ferroptosis-driven loss of dopaminergic neurons plays a pivotal role in the pathogenesis of Parkinson's disease (PD). In PD patients, Hspb1 is commonly observed at abnormally high levels in the substantia nigra. The precise consequences of Hspb1 overexpression in PD, however, have yet to be fully elucidated. Methods: We used human iPSC-derived dopaminergic neurons and Coniferaldehyde (CFA)-an Nrf2 agonist known for its ability to cross the blood-brain barrier-to investigate the role of Hspb1 in PD. We examined the correlation between Hspb1 overexpression and Nrf2 activation and explored the transcriptional regulation of Hspb1 by Nrf2. Gene deletion techniques were employed to determine the necessity of Nrf2 and Hspb1 for CFA's neuroprotective effects. Results: Our research demonstrated that Nrf2 can upregulate the transcription of Hspb1 by directly binding to its promoter. Deletion of either Nrf2 or Hspb1 gene abolished the neuroprotective effects of CFA. The Nrf2-Hspb1 pathway, newly identified as a defense mechanism against ferroptosis, was shown to be essential for preventing neurodegeneration progression. Additionally, we discovered that prolonged overexpression of Hspb1 leads to neuronal death and that Hspb1 released from ruptured cells can trigger secondary cell death in neighboring cells, exacerbating neuroinflammatory responses. Conclusions: These findings highlight a biphasic role of Hspb1 in PD, where it initially provides neuroprotection through the Nrf2-Hspb1 pathway but ultimately contributes to neurodegeneration and inflammation when overexpressed. Understanding this dual role is crucial for developing therapeutic strategies targeting Hspb1 and Nrf2 in PD.

A dual target molecular magnetic resonance imaging probe for noninvasive profiling of pathologic alpha-synuclein and microgliosis in a mouse model of Parkinson's disease

The pathogenesis of Parkinson's disease (PD) is characterized by progressive deposition of alpha-synuclein (α-syn) aggregates in dopaminergic neurons and neuroinflammation. Noninvasive in vivo imaging of α-syn aggregate accumulation and neuroinflammation can elicit the underlying mechanisms involved in disease progression and facilitate the development of effective treatment as well as disease diagnosis and prognosis. Here we present a novel approach to simultaneously profile α-syn aggregation and reactive microgliosis in vivo, by targeting oligomeric α-syn in cerebrospinal fluid with nanoparticle bearing a magnetic resonance imaging (MRI), contrast payload. In this proof-of-concept report we demonstrate, in vitro, that microglia and neuroblastoma cell lines internalize agglomerates formed by cross-linking the nanoparticles with oligomeric α-syn. Delayed in vivo MRI scans following intravenous administration of the nanoparticles in the M83 α-syn transgenic mouse line show statistically significant MR signal enhancement in test mice versus controls. The in vivo data were validated by ex-vivo immunohistochemical analysis which show strong correlation between in vivo MRI signal enhancement, Lewy pathology distribution, and microglia activity in the treated brain tissue. Furthermore, neuronal and microglial cells in brain tissue from treated mice display strong cytosolic signal originating from the nanoparticles, attributed to in vivo cell uptake of nanoparticle/oligomeric α-syn agglomerates.

Assessment of the therapeutic potential of Hsp70 activator against prion diseases using in vitro and in vivo models

Introduction

Prion diseases are deadly neurodegenerative disorders in both animals and humans, causing the destruction of neural tissue and inducing behavioral manifestations. Heat shock proteins (Hsps), act as molecular chaperones by supporting the appropriate folding of proteins and eliminating the misfolded proteins as well as playing a vital role in cell signaling transduction, cell cycle, and apoptosis control. SW02 is a potent activator of Hsp 70 kDa (Hsp70).

Methods

In the current study, the protective effects of SW02 against prion protein 106-126 (PrP106-126)-induced neurotoxicity in human neuroblastoma cells (SH-SY5Y) were investigated. In addition, the therapeutic effects of SW02 in ME7 scrapie-infected mice were evaluated.

Results

The results showed that SW02 treatment significantly increased Hsp70 mRNA expression levels and Hsp70 ATPase activity (p < 0.01). SW02 also significantly inhibited cytotoxicity and apoptosis induced by PrP106-126 (p < 0.01) and promoted neurite extension. In vivo, intraperitoneal administration of SW02 did not show a statistically significant difference in survival time (p = 0.16); however, the SW02-treated group exhibited a longer survival time of 223.6 ± 6.0 days compared with the untreated control group survival time of 217.6 ± 5.4 days. In addition, SW02 reduced the PrPSc accumulation in ME7 scrapie-infected mice at 5 months post-injection (p < 0.05). A significant difference was not observed in GFAP expression, an astrocyte marker, between the treated and untreated groups.

Conclusion

In conclusion, the potential therapeutic role of the Hsp70 activator SW02 was determined in the present study and may be a novel and effective drug to mitigate the pathologies of prion diseases and other neurodegenerative diseases. Further studies using a combination of two pharmacological activators of Hsp70 are required to maximize the effectiveness of each intervention.

Differentiation of SH-SY5Y neuroblastoma cells using retinoic acid and BDNF: a model for neuronal and synaptic differentiation in neurodegeneration

There has been much interest in the use of cell culture models of neurones, to avoid the animal welfare and cost issues of using primary and human-induced pluripotent stem cell (hiPSC)-derived neurones respectively. The human neuroblastoma cell line, SH-SY5Y, is extensively used in laboratories as they can be readily expanded, are of low cost and can be differentiated into neuronal-like cells. However, much debate remains as to their phenotype once differentiated, and their ability to recapitulate the physiology of bona fide neurones. Here, we characterise a differentiation protocol using retinoic acid and BDNF, which results in extensive neurite outgrowth/branching within 10 days, and expression of key neuronal and synaptic markers. We propose that these differentiated SH-SY5Y cells may be a useful substitute for primary or hiPSC-derived neurones for cell biology studies, in order to reduce costs and animal usage. We further propose that this characterised differentiation timecourse could be used as an in vitro model for neuronal differentiation, for proof-of principle studies on neurogenesis, e.g. relating to neurodegenerative diseases. Finally, we demonstrate profound changes in Tau phosphorylation during differentiation of these cells, suggesting that they should not be used for neurodegeneration studies in their undifferentiated state.

Synthesis, biological evaluation and metadynamics simulations of novel N-methyl β-sheet breaker peptides as inhibitors of Alzheimer's β-amyloid fibrillogenesis

Several scientific evidences report that a central role in the pathogenesis of Alzheimer's disease is played by the deposition of insoluble aggregates of β-amyloid proteins in the brain. Because Aβ is self-assembling, one possible design strategy is to inhibit the aggregation of Aβ peptides using short peptide fragments homologous to the full-length wild-type Aβ protein. In the past years, several studies have reported on the synthesis of some short synthetic peptides called β-sheet breaker peptides (BSBPs). Herein, we present the synthesis of novel (cell-permeable) N-methyl BSBPs, designed based on literature information on the structural key features of BSBPs. Three-dimensional GRID-based pharmacophore peptide screening combined with PT-WTE metadynamics was performed to support the results of the design and microwave-assisted synthesis of peptides 2 and 3 prepared and analyzed for their fibrillogenesis inhibition activity and cytotoxicity. An HR-MS-based cell metabolomic approach highlighted their cell permeability properties.

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.

Exploring the Regulation of Cytochrome P450 in SH-SY5Y Cells: Implications for the Onset of Neurodegenerative Diseases

Human individual differences in brain cytochrome P450 (CYP) metabolism, including induction, inhibition, and genetic variation, may influence brain sensitivity to neurotoxins and thus participate in the onset of neurodegenerative diseases. The aim of this study was to explore the modulation of CYPs in neuronal cells. The experimental approach was focused on differentiating human neuroblastoma SH-SY5Y cells into a phenotype resembling mature dopamine neurons and investigating the effects of specific CYP isoform induction. The results demonstrated that the differentiation protocols using retinoic acid followed by phorbol esters or brain-derived neurotrophic factor successfully generated SH-SY5Y cells with morphological neuronal characteristics and increased neuronal markers (NeuN, synaptophysin, β-tubulin III, and MAO-B). qRT-PCR and Western blot analysis showed that expression of the CYP 1A1, 3A4, 2D6, and 2E1 isoforms was detectable in undifferentiated cells, with subsequent increases in CYP 2E1, 2D6, and 1A1 following differentiation. Further increases in the 1A1, 2D6, and 2E1 isoforms following β-naphthoflavone treatment and 1A1 and 2D6 isoforms following ethanol treatment were evident. These results demonstrate that CYP isoforms can be modulated in SH-SY5Y cells and suggest their potential as an experimental model to investigate the role of CYPs in neuronal processes involved in the development of neurodegenerative diseases.

Durian fruit pulp extract enhances intracellular glutathione levels, mitigating oxidative stress and inflammation for neuroprotection

Durian (Durio zibethinus L.) fruit pulp is a rich source of γ-glutamylcysteine (γ-EC), a direct precursor to the antioxidant glutathione (GSH). This study elucidated the in vitro neuroprotective potential of unripe durian fruit pulp extract (UDE) against H2O2-induced neurotoxicity in SH-SY5Y cells and neuroinflammation in lipopolysaccharide (LPS)-stimulated BV-2 cells. Treatments with γ-EC, GSH standards, or UDE exhibited no cytotoxicity in SH-SY5Y and BV-2 cells, except at high concentrations. A 4-h pretreatment with 100 µM γ-EC or UDE containing 100 µM γ-EC significantly increased SH-SY5Y cell viability post H2O2 induction. Moreover, a similar pretreatment reduced LPS-stimulated production of proinflammatory cytokines in BV-2 cells. The neuroprotective effect of UDE is primarily attributed to γ-EC provision and the promotion of GSH synthesis, which in turn elevates intracellular GSH levels and reduces proinflammatory cytokines. This study identifies γ-EC in UDE as a potential neuroprotective biomarker boosting intracellular GSH levels, providing insights into UDE's therapeutic potential.

More than a number: Incorporating the aged phenotype to improve in vitro and in vivo modeling of neurodegenerative disease

Age is the number one risk factor for developing a neurodegenerative disease (ND), such as Alzheimer's disease (AD) or Parkinson's disease (PD). With our rapidly ageing world population, there will be an increased burden of ND and need for disease-modifying treatments. Currently, however, translation of research from bench to bedside in NDs is poor. This may be due, at least in part, to the failure to account for the potential effect of ageing in preclinical modelling of NDs. While ageing can impact upon physiological response in multiple ways, only a limited number of preclinical studies of ND have incorporated ageing as a factor of interest. Here, we evaluate the aged phenotype and highlight the critical, but unmet, need to incorporate aspects of this phenotype into both the in vitro and in vivo models used in ND research. Given technological advances in the field over the past several years, we discuss how these could be harnessed to create novel models of ND that more readily incorporate aspects of the aged phenotype. This includes a recently described in vitro panel of ageing markers, which could help lead to more standardised models and improve reproducibility across studies. Importantly, we cannot assume that young cells or animals yield the same responses as seen in the context of ageing; thus, an improved understanding of the biology of ageing, and how to appropriately incorporate this into the modelling of ND, will ensure the best chance for successful translation of new therapies to the aged patient.

Structural insights into the recognition of the A/T-rich motif in target gene promoters by the LMX1a homeobox domain

LIM homeodomain transcription factor 1-alpha (LMX1a) is a neuronal lineage-specific transcription activator that plays an essential role during the development of midbrain dopaminergic (mDA) neurons. LMX1a induces the expression of multiple key genes, which ultimately determine the morphology, physiology, and functional identity of mDA neurons. This function of LMX1a is dependent on its homeobox domain. Here, we determined the structures of the LMX1a homeobox domain in complex with the promoter sequences of the Wnt family member 1 (WNT1) or paired like homeodomain 3 (Pitx3) gene, respectively. The complex structures revealed that the LMX1a homeobox domain employed its α3 helix and an N-terminal loop to achieve specific target recognition. The N-terminal loop (loop1) interacted with the minor groove of the double-stranded DNA (dsDNA), whereas the third α-helix (α3) was tightly packed into the major groove of the dsDNA. Structure-based mutations in the α3 helix of the homeobox domain significantly reduced the binding affinity of LMX1a to dsDNA. Moreover, we identified a nonsyndromic hearing loss (NSHL)-related mutation, R199, which yielded a more flexible loop and disturbed the recognition in the minor groove of dsDNA, consistent with the molecular dynamics (MD) simulations. Furthermore, overexpression of Lmx1a promoted the differentiation of SH-SY5Y cells and upregulated the transcription of WNT1 and PITX3 genes. Hence, our work provides a detailed elucidation of the specific recognition between the LMX1a homeobox domain and its specific dsDNA targets, which represents valuable information for future investigations of the functional pathways that are controlled by LMX1a during mDA neuron development.

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.

Near-Infrared Ratiometric Fluorescent Probe for Detecting Endogenous Cu2+ in the Brain

Copper participates in a range of critical functions in the nervous system and human brain. Disturbances in brain copper content is strongly associated with neurological diseases. For example, changes in the level and distribution of copper are reported in neuroblastoma, Alzheimer's disease, and Lewy body disorders, such as Parkinson disease and dementia with Lewy bodies (DLB). There is a need for more sensitive techniques to measure intracellular copper levels to have a better understanding of the role of copper homeostasis in neuronal disorders. Here, we report a reaction-based near-infrared (NIR) ratiometric fluorescent probe CyCu1 for imaging Cu2+ in biological samples. High stability and selectivity of CyCu1 enabled the probe to be deployed as a sensor in a range of systems, including SH-SY5Y cells and neuroblastoma tumors. Furthermore, it can be used in plant cells, reporting on copper added to Arabidopsis roots. We also used CyCu1 to explore Cu2+ levels and distribution in post-mortem brain tissues from patients with DLB. We found significant decreases in Cu2+ content in the cytoplasm, neurons, and extraneuronal space in the degenerating substantia nigra in DLB compared with healthy age-matched control tissues. These findings enhance our understanding of Cu2+ dysregulation in Lewy body disorders. Our probe also shows promise as a photoacoustic imaging agent, with potential for applications in bimodal imaging.

Downregulation of Protease Cathepsin D and Upregulation of Pathologic α-Synuclein Mediate Paucity of DNAJC6-Induced Degeneration of Dopaminergic Neurons

A homozygous mutation of the DNAJC6 gene causes autosomal recessive familial type 19 of Parkinson's disease (PARK19). To test the hypothesis that PARK19 DNAJC6 mutations induce the neurodegeneration of dopaminergic cells by reducing the protein expression of functional DNAJC6 and causing DNAJC6 paucity, an in vitro PARK19 model was constructed by using shRNA-mediated gene silencing of endogenous DANJC6 in differentiated human SH-SY5Y dopaminergic neurons. shRNA targeting DNAJC6 induced the neurodegeneration of dopaminergic cells. DNAJC6 paucity reduced the level of cytosolic clathrin heavy chain and the number of lysosomes in dopaminergic neurons. A DNAJC6 paucity-induced reduction in the lysosomal number downregulated the protein level of lysosomal protease cathepsin D and impaired macroautophagy, resulting in the upregulation of pathologic α-synuclein or phospho-α-synucleinSer129 in the endoplasmic reticulum (ER) and mitochondria. The expression of α-synuclein shRNA or cathepsin D blocked the DNAJC6 deficiency-evoked degeneration of dopaminergic cells. An increase in ER α-synuclein or phospho-α-synucleinSer129 caused by DNAJC6 paucity activated ER stress, the unfolded protein response and ER stress-triggered apoptotic signaling. The lack of DNAJC6-induced upregulation of mitochondrial α-synuclein depolarized the mitochondrial membrane potential and elevated the mitochondrial level of superoxide. The DNAJC6 paucity-evoked ER stress-related apoptotic cascade, mitochondrial malfunction and oxidative stress induced the degeneration of dopaminergic neurons via activating mitochondrial pro-apoptotic signaling. In contrast with the neuroprotective function of WT DNAJC6, the PARK19 DNAJC6 mutants (Q789X or R927G) failed to attenuate the tunicamycin- or rotenone-induced upregulation of pathologic α-synuclein and stimulation of apoptotic signaling. Our data suggest that PARK19 mutation-induced DNAJC6 paucity causes the degeneration of dopaminergic neurons via downregulating protease cathepsin D and upregulating neurotoxic α-synuclein. Our results also indicate that PARK19 mutation (Q789X or R927G) impairs the DNAJC6-mediated neuroprotective function.

The Effect of Neuronal CoQ10 Deficiency and Mitochondrial Dysfunction on a Rotenone-Induced Neuronal Cell Model of Parkinson's Disease

Parkinson's disease (PD) is the second most prevalent neurodegenerative disorder currently affecting the ageing population. Although the aetiology of PD has yet to be fully elucidated, environmental factors such as exposure to the naturally occurring neurotoxin rotenone has been associated with an increased risk of developing PD. Rotenone inhibits mitochondrial respiratory chain (MRC) complex I activity as well as induces dopaminergic neuronal death. The aim of the present study was to investigate the underlying mechanisms of rotenone-induced mitochondrial dysfunction and oxidative stress in an in vitro SH-SY5Y neuronal cell model of PD and to assess the ability of pre-treatment with Coenzyme Q10 (CoQ10) to ameliorate oxidative stress in this model. Spectrophotometric determination of the mitochondrial enzyme activities and fluorescence probe studies of reactive oxygen species (ROS) production was assessed. Significant inhibition of MRC complex I and II-III activities was observed, together with a significant loss of neuronal viability, CoQ10 status, and ATP synthesis. Additionally, significant increases were observed in intracellular and mitochondrial ROS production. Remarkably, CoQ10 supplementation was found to reduce ROS formation. These results have indicated mitochondrial dysfunction and increased oxidative stress in a rotenone-induced neuronal cell model of PD that was ameliorated by CoQ10 supplementation.

Ergothioneine-Mediated Neuroprotection of Human iPSC-Derived Dopaminergic Neurons

Cell death involving oxidative stress and mitochondrial dysfunction is a major cause of dopaminergic neuronal loss in the substantia nigra (SN) of Parkinson's disease patients. Ergothioneine (ET), a natural dietary compound, has been shown to have cytoprotective functions, but neuroprotective actions against PD have not been well established. 6-Hydroxydopamine (6-OHDA) is a widely used neurotoxin to simulate the degeneration of dopaminergic (DA) neurons in Parkinson's disease. In this study, we investigated the protective effect of ET on 6-OHDA treated iPSC-derived dopaminergic neurons (iDAs) and further confirmed the protective effects in 6-OHDA-treated human neuroblastoma SH-SY5Y cells. In 6-OHDA-treated cells, decreased mitochondrial membrane potential (ΔΨm), increased mitochondrial reactive oxygen species (mROS), reduced cellular ATP levels, and increased total protein carbonylation levels were observed. 6-OHDA treatment also significantly decreased tyrosine hydroxylase levels. These effects were significantly decreased when ET was present. Verapamil hydrochloride (VHCL), a non-specific inhibitor of the ET transporter OCTN1 abrogated ET's cytoprotective effects, indicative of an intracellular action. These results suggest that ET could be a potential therapeutic for Parkinson's disease.

Lymphocyte antigen 96: A new potential biomarker and immune target in Parkinson's disease

BACKGROUND

Lymphocyte antigen 96 (LY96) plays an important role in innate immunity and has been reported to be associated with various neurological diseases. However, its role in Parkinson's disease (PD) remains unclear.

METHODS

Transcriptome data from a total of 49 patients with PD and 34 healthy controls were downloaded from the Gene Expression Omnibus (GEO) database to analyse the expression pattern of LY96 and its relationship with gene function and immune-related markers. In addition, peripheral blood samples were collected from clinical patients to validate LY96 mRNA expression levels. Finally, an in vitro cell model of PD based on highly differentiated SH-SY5Y cells was constructed, with small interfering RNA-silenced LY96 expression, and LY96 mRNA level, cell viability, flow cytometry, and mitochondrial membrane potential assays were performed.

RESULTS

The results of the analyses of the GEO database and clinical samples revealed significantly abnormally high LY96 expression in patients with PD compared with healthy controls. The results of cell experiments showed that inhibiting LY96 expression alleviated adverse cellular effects by increasing cell viability, reducing apoptosis, and reducing oxidative stress. Gene set enrichment analysis showed that LY96 was positively correlated with T1 helper cells, T2 helper cells, neutrophils, natural killer T cells, myeloid-derived suppressor cells, macrophages, and activated CD4 cells, and may participate in PD through natural killer cell-mediated cytotoxicity pathways and extracellular matrix receptor interaction pathways.

CONCLUSION

These findings suggested that LY96 might be a novel potential biomarker for PD, and offer insights into its immunoregulatory role.

Mechanistic Evaluation of miRNAs and Their Targeted Genes in the Pathogenesis and Therapeutics of Parkinson's Disease

MicroRNA (miRNA) are usually 18-25 nucleotides long non-coding RNA targeting post-transcriptional regulation of genes involved in various biological processes. The function of miRNA is essential for maintaining a homeostatic cellular condition, regulating autophagy, cellular motility, and inflammation. Dysregulation of miRNA is responsible for multiple disorders, including neurodegeneration, which has emerged as a severe problem in recent times and has verified itself as a life-threatening condition that can be understood by the continuous destruction of neurons affecting various cognitive and motor functions. Parkinson's disease (PD) is the second most common, permanently debilitating neurodegenerative disorder after Alzheimer's, mainly characterized by uncontrolled tremor, stiffness, bradykinesia or akinesia (slowness in movement), and post-traumatic stress disorder. PD is mainly caused by the demolition of the primary dopamine neurotransmitter secretory cells and dopaminergic or dopamine secretory neurons in the substantia nigra pars compacta of the midbrain, which are majorly responsible for motor functions. In this study, a systematic evaluation of research articles from year 2017 to 2022 was performed on multiple search engines, and lists of miRNA being dysregulated in PD in different body components were generated. This study highlighted miR-7, miR-124, miR-29 family, and miR-425, showing altered expression levels during PD's progression, further regulating the expression of multiple genes responsible for PD.

Exploring differentiation-dependent responses to 532 nm green laser photobiomodulation in SHSY5Y neuroblastoma cells

Photobiomodulation (PBM) holds promise as a therapy modality, but its applicability is hindered by the lack of a quantitative model to predict the optimal dose for all forms of PBM. This study investigated the optimal PBM parameters for 532 nm green laser irradiation on SHSY5Y neuroblastoma cells, a commonly used in vitro model for neurodegenerative disease studies. A two-tailed, two sample t-test with equal variance was used to obtain the p-values and statistical significance. There are 3 sets of parameters showing significant ( p < 0 . 01 ) positive percentage biostimulation. 160 m W , 15 m i n produce a percentage biostimulation of ( 9 ± 10 ) % ; 180 m W , 5 m i n produce a percentage biostimulation of ( 19 ± 7 ) % ; and ( 200 m W , 5 m i n ) produce a percentage biostimulation of ( 9 ± 2 ) % . The highest significant ( p < 0 . 01 ) percentage bioinhibition observed is for 220 m W , 15 m i n (dose: 1008 J / c m 2 ) producing a bioinhibition of ( 54 ± 1 ) % . After identifying several parameters that produce noticeable photobiological effects (biostimulation and bioinhibition), this study compared the reaction of undifferentiated and differentiated SHSY5Y cells to laser irradiation and found that undifferentiated SHSY5Y cells shows greater photobiological effect from 532 nm laser irradiation ( p < 0 . 01 ) . This study demonstrated the differentiation-dependant photobiological effect of SHSY5Y in 532 nm laser PBM. This shows that considerations on the differentiation state of cells is important in PBM studies. The hypothesis of difference in intracellular reactive oxygen species (ROS) accumulation from laser irradiation can serve as a versatile explanation of the observed difference in photobiological effect. Further investigation into the role of ROS as a mediator of various photobiological effects from laser of different wavelengths is warranted.

A novel APP splice variant-dependent marker system to precisely demarcate maturity in SH-SY5Y cell-derived neurons

SH-SY5Y, a neuroblastoma cell line, can be converted into mature neuronal phenotypes, characterized by the expression of mature neuronal and neurotransmitter markers. However, the mature phenotypes described across multiple studies appear inconsistent. As this cell line expresses common neuronal markers after a simple induction, there is a high chance of misinterpreting its maturity. Therefore, sole reliance on common neuronal markers is presumably inadequate. The Alzheimer's disease (AD) central gene, amyloid precursor protein (APP), has shown contrasting transcript variant dynamics in various cell types. We differentiated SH-SY5Y cells into mature neuron-like cells using a concise protocol and observed the upregulation of total APP throughout differentiation. However, APP transcript variant-1 was upregulated only during the early to middle stages of differentiation and declined in later stages. We identified the maturity state where this post-transcriptional shift occurs, terming it "true maturity." At this stage, we observed a predominant expression of mature neuronal and cholinergic markers, along with a distinct APP variant pattern. Our findings emphasize the necessity of using a differentiation state-sensitive marker system to precisely characterize SH-SY5Y differentiation. Moreover, this study offers an APP-guided, alternative neuronal marker system to enhance the accuracy of the conventional markers.

Neuronal DAMPs exacerbate neurodegeneration via astrocytic RIPK3 signaling

Astrocyte activation is a common feature of neurodegenerative diseases. However, the ways in which dying neurons influence the activity of astrocytes is poorly understood. Receptor interacting protein kinase-3 (RIPK3) signaling has recently been described as a key regulator of neuroinflammation, but whether this kinase mediates astrocytic responsiveness to neuronal death has not yet been studied. Here, we used the 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine model of Parkinson's disease to show that activation of astrocytic RIPK3 drives dopaminergic cell death and axon damage. Transcriptomic profiling revealed that astrocytic RIPK3 promoted gene expression associated with neuroinflammation and movement disorders, and this coincided with significant engagement of damage-associated molecular pattern signaling. In mechanistic experiments, we showed that factors released from dying neurons signaled through receptor for advanced glycation endproducts to induce astrocytic RIPK3 signaling, which conferred inflammatory and neurotoxic functional activity. These findings highlight a mechanism of neuron-glia crosstalk in which neuronal death perpetuates further neurodegeneration by engaging inflammatory astrocyte activation via RIPK3.

Single-cell ICP-MS for evaluating the Se-protective effect against MeHg+-induced neurotoxicity in human neuroblastoma cell line (SH-SY5Y)

The protective effect of selenium (Se) against Hg-induced neurotoxicity has been widely investigated; however, the mechanisms behind this interaction have not been fully elucidated yet. In the current work, the role of Se against MeHg+-induced cytotoxicity in the human neuroblastoma cell line (SH-SY5Y) is reported for the first time by tracking Hg uptake and accumulation at the single-cell level by inductively coupled plasma-mass spectrometry in single-cell mode (SC-ICP-MS). The influence of different Se species (SeMet, SeMeSeCys, citrate-SeNPs, and chitosan-SeNPs) on MeHg+ cytotoxicity was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays. SeMet and SeMeSeCys exhibited protective effects against MeHg+-induced cell death, particularly at high MeHg+ concentrations (LC50). In addition, chitosan-SeNPs showed greater protection compared to citrate-SeNPs when co-exposed with MeHg+. Interestingly, SC-ICP-MS unveiled the heterogeneous distribution of Hg uptake by SH-SY5Y cells. Co-exposure of SeMet and SeMeSeCys with MeHg+ led to a reduction of the amount of Hg accumulated per individual cell, which decreased the maximum level of Hg per cell by half (from 60 fg Hg cell-1 to 30 fg Hg cell-1) when SeMet was present, along with a decrease in the percentage of cells that accumulated the highest quantity of MeHg+. All these data corroborate the protective role of Se against Hg toxicity at the cellular level.

Human neural stem cells promote mitochondrial genesis to alleviate neuronal damage in MPTP-induced cynomolgus monkey models

Currently, there is no effective treatment for Parkinson's disease (PD), and the regenerative treatment of neural stem cells (NSCs) is considered the most promising method. This study aimed to investigate the protective effect and mechanism of NSCs on neurons in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) induced cynomolgus monkey (Macaca fascicularis) model of PD. We first found that injecting NSCs into the subarachnoid space relieved motor dysfunction in PD cynomolgus monkeys, as well as reduced dopaminergic neuron loss and neuronal damage in the substantia nigra (SN) and striatum. Besides, NSCs decreased 17-estradiol (E2) level, an estrogen, in the cerebrospinal fluid (CSF) of PD cynomolgus monkeys, which shows NSCs may provide neuro-protection by controlling estrogen levels in the CSF. Furthermore, NSCs elevated proliferator-activated receptor gamma coactivator-1 alpha (PGC-1a), mitofusin 2 (MFN2), and optic atrophy 1 (OPA1) expression, three genes mediating mitochondrial biogenesis, in the SN and striatum of PD monkeys. In addition, NSCs suppress reactive oxygen species (ROS) production caused by MPTP, as well as mitochondrial autophagy, therefore preserving dopaminergic neurons. In summary, our findings show that NSCs may preserve dopaminergic and neuronal cells in an MPTP-induced PD cynomolgus monkey model. These protective benefits might be attributed to NSCs' ability of modulating estrogen balance, increasing mitochondrial biogenesis, and limiting oxidative stress and mitochondrial autophagy. These findings add to our understanding of the mechanism of NSC treatment and shed light on further clinical treatment options.

α-Synuclein triggers cofilin pathology and dendritic spine impairment via a PrPC-CCR5 dependent pathway

Cognitive dysfunction and dementia are critical symptoms of Lewy Body dementias (LBD). Specifically, alpha-synuclein (αSyn) accumulation in the hippocampus leading to synaptic dysfunction is linked to cognitive deficits in LBD. Here, we investigated the pathological impact of αSyn on hippocampal neurons. We report that either αSyn overexpression or αSyn pre-formed fibrils (PFFs) treatment triggers the formation of cofilin-actin rods, synapse disruptors, in cultured hippocampal neurons and in the hippocampus of synucleinopathy mouse models and of LBD patients. In vivo, cofilin pathology is present concomitantly with synaptic impairment and cognitive dysfunction. Rods generation prompted by αSyn involves the co-action of the cellular prion protein (PrPC) and the chemokine receptor 5 (CCR5). Importantly, we show that CCR5 inhibition, with a clinically relevant peptide antagonist, reverts dendritic spine impairment promoted by αSyn. Collectively, we detail the cellular and molecular mechanism through which αSyn disrupts hippocampal synaptic structure and we identify CCR5 as a novel therapeutic target to prevent synaptic impairment and cognitive dysfunction in LBD.

Mitophagy Upregulation Occurs Early in the Neurodegenerative Process Mediated by α-Synuclein

Parkinson's disease (PD) is a progressive neurogenerative movement disorder characterized by dopaminergic cell death within the substantia nigra pars compacta (SNpc) due to the aggregation-prone protein α-synuclein. Accumulation of α-synuclein is implicated in mitochondrial dysfunction and disruption of the autophagic turnover of mitochondria, or mitophagy, which is an essential quality control mechanism proposed to preserve mitochondrial fidelity in response to aging and stress. Yet, the precise relationship between α-synuclein accumulation, mitochondrial autophagy, and dopaminergic cell loss remains unresolved. Here, we determine the kinetics of α-synuclein overexpression and mitophagy using the pH-sensitive fluorescent mito-QC reporter. We find that overexpression of mutant A53T α-synuclein in either human SH-SY5Y cells or rat primary cortical neurons induces mitophagy. Moreover, the accumulation of mutant A53T α-synuclein in the SNpc of rats results in mitophagy dysregulation that precedes the onset of dopaminergic neurodegeneration. This study reveals a role for mutant A53T α-synuclein in inducing mitochondrial dysfunction, which may be an early event contributing to neurodegeneration.

Exploring Neuronal Differentiation Profiles in SH-SY5Y Cells through Magnetic Levitation Analysis

Magnetic levitation (MagLev) is a powerful and versatile technique that can sort objects based on their density differences. This paper reports the sorting of SH-SY5Y cells for neuronal differentiation by the MagLev technique. Herein, SH-SY5Y cells were differentiated with retinoic acid (RA) and brain-derived neurotrophic factor (BDNF). Neuronal differentiation was confirmed by neurite extension measurement and the immunostaining assay. Neurites reached the maximum length on day 9 after sequential treatment with RA-BDNF. Neuronal marker expression of un-/differentiated cells was investigated by β-III tubulin and neuronal nuclei (NeuN) and differentiated cells exhibited a higher fluorescence intensity compared to un-/differentiated cells. MagLev results revealed that the density of differentiated SH-SY5Y cells gradually increased from 1.04 to 1.06 g/mL, while it remained stable at 1.05 g/mL for un-/differentiated cells. These findings signified that cell density would be a potent indicator of neuronal differentiation. Overall, it was shown that MagLev methodology can provide rapid, label-free, and easy sorting to analyze the differentiation of cells at a single-cell level.

High-throughput discovery of highly selective reversible hMAO-B inhibitors based on at-line nanofractionation

Human monoamine oxidase B (hMAO-B) has emerged as a pivotal therapeutic target for Parkinson's disease. Due to adverse effects and shortage of commercial drugs, there is a need for novel, highly selective, and reversible hMAO-B inhibitors with good blood-brain barrier permeability. In this study, a high-throughput at-line nanofractionation screening platform was established with extracts from Chuanxiong Rhizoma, which resulted in the discovery of 75 active compounds, including phenolic acids, volatile oils, and phthalides, two of which were highly selective novel natural phthalide hMAO-B inhibitors that were potent, selective, reversible and had good blood‒brain permeability. Molecular docking and molecular dynamics simulations elucidated the inhibition mechanism. Sedanolide (IC50 = 103 nmol/L; SI = 645) and neocnidilide (IC50 = 131 nmol/L; SI = 207) demonstrated their excellent potential as hMAO-B inhibitors. They offset the limitations of deactivating enzymes associated with irreversible hMAO-B inhibitors such as rasagiline. In SH-SY5Y cell assays, sedanolide (EC50 = 0.962 μmol/L) and neocnidilide (EC50 = 1.161 μmol/L) exhibited significant neuroprotective effects, comparable to the positive drugs rasagiline (EC50 = 0.896 μmol/L) and safinamide (EC50 = 1.079 μmol/L). These findings underscore the potential of sedanolide as a novel natural hMAO-B inhibitor that warrants further development as a promising drug candidate.

Diving into the proteomic atlas of SARS-CoV-2 infected cells

The COVID-19 pandemic was initiated by the rapid spread of a SARS-CoV-2 strain. Though mainly classified as a respiratory disease, SARS-CoV-2 infects multiple tissues throughout the human body, leading to a wide range of symptoms in patients. To better understand how SARS-CoV-2 affects the proteome from cells with different ontologies, this work generated an infectome atlas of 9 cell models, including cells from brain, blood, digestive system, and adipocyte tissue. Our data shows that SARS-CoV-2 infection mainly trigger dysregulations on proteins related to cellular structure and energy metabolism. Despite these pivotal processes, heterogeneity of infection was also observed, highlighting many proteins and pathways uniquely dysregulated in one cell type or ontological group. These data have been made searchable online via a tool that will permit future submissions of proteomic data ( https://reisdeoliveira.shinyapps.io/Infectome_App/ ) to enrich and expand this knowledgebase.

High OXPHOS efficiency in RA-FUdr-differentiated SH-SY5Y cells: involvement of cAMP signalling and respiratory supercomplexes

Neurons are highly dependent on mitochondria to meet their bioenergetic needs and understanding the metabolic changes during the differentiation process is crucial in the neurodegeneration context. Several in vitro approaches have been developed to study neuronal differentiation and bioenergetic changes. The human SH-SY5Y cell line is a widely used cellular model and several differentiation protocols have been developed to induce a neuron-like phenotype including retinoic acid (RA) treatment. In this work we obtained a homogeneous functional population of neuron-like cells by a two-step differentiation protocol in which SH-SY5Y cells were treated with RA plus the mitotic inhibitor 2-deoxy-5-fluorouridine (FUdr). RA-FUdr treatment induced a neuronal phenotype characterized by increased expression of neuronal markers and electrical properties specific to excitable cells. In addition, the RA-FUdr differentiated cells showed an enrichment of long chain and unsaturated fatty acids (FA) in the acyl chain composition of cardiolipin (CL) and the bioenergetic analysis evidences a high coupled and maximal respiration associated with high mitochondrial ATP levels. Our results suggest that the observed high oxidative phosphorylation (OXPHOS) capacity may be related to the activation of the cyclic adenosine monophosphate (cAMP) pathway and the assembly of respiratory supercomplexes (SCs), highlighting the change in mitochondrial phenotype during neuronal differentiation.

Protective effects of amphetamine and methylphenidate against dopaminergic neurotoxicants in SH-SY5Y cells

Full treatment of the second most common neurodegenerative disorder, Parkinson's disease (PD), is still considered an unmet need. As the psychostimulants, amphetamine (AMPH) and methylphenidate (MPH), were shown to be neuroprotective against stroke and other neuronal injury diseases, this study aimed to evaluate their neuroprotective potential against two dopaminergic neurotoxicants, 6-hydroxydopamine (6-OHDA) and paraquat (PQ), in differentiated human dopaminergic SH-SY5Y cells. Neither cytotoxicity nor mitochondrial membrane potential changes were seen following a 24-hour exposure to either therapeutic concentration of AMPH or MPH (0.001-10 μM). On the other hand, a 24-hour exposure to 6-OHDA (31.25-500 μM) or PQ (100-5000 μM) induced concentration-dependent mitochondrial dysfunction, assessed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay, and lysosomal damage, evaluated by the neutral red uptake assay. The lethal concentrations 25 and 50 retrieved from the concentration-toxicity curves in the MTT assay were 99.9 µM and 133.6 µM for 6-OHDA, or 422 µM and 585.8 µM for PQ. Both toxicants caused mitochondrial membrane potential depolarization, but only 6-OHDA increased reactive oxygen species (ROS). Most importantly, PQ-induced toxicity was partially prevented by 1 μM of AMPH or MPH. Nonetheless, neither AMPH nor MPH could prevent 6-OHDA toxicity in this experimental model. According to these findings, AMPH and MPH may provide some neuroprotection against PQ-induced neurotoxicity, but further investigation is required to determine the exact mechanism underlying this protection.