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

Nitric oxide contributes to protein homeostasis by S-nitrosylations of the chaperone HSPA8 and the ubiquitin ligase UBE2D

Upregulations of neuronal nitric oxide synthase (nNOS) in the rodent brain have been associated with neuronal aging. To address underlying mechanisms we generated SH-SY5Y neuronal cells constitutively expressing nNOS at a level similar to mouse brain (nNOS+ versus MOCK). Initial experiments revealed S-nitrosylations (SNO) of key players of protein homeostasis: heat shock cognate HSC70/HSPA8 within its nucleotide-binding site, and UBE2D ubiquitin conjugating enzymes at the catalytic site cysteine. HSPA8 is involved in protein folding, organelle import/export and chaperone-mediated LAMP2a-dependent autophagy (CMA). A set of deep redox and full proteome analyses, plus analysis of autophagy, CMA and ubiquitination with rapamycin and starvation as stimuli confirmed the initial observations and revealed a substantial increase of SNO modifications in nNOS+ cells, in particular targeting protein networks involved in protein catabolism, ubiquitination, carbohydrate metabolism and cell cycle control. Importantly, NO-independent reversible oxidations similarly occurred in both cell lines. Functionally, nNOS caused an accumulation of proteins, including CMA substrates and loss of LAMP2a. UBE2D activity and proteasome activity were impaired, resulting in dysregulations of cell cycle checkpoint proteins. The observed changes of protein degradation pathways caused an expansion of the cytoplasm, large lysosomes, slowing of the cell cycle and suppression of proliferation suggesting a switch of the phenotype towards aging, supported by downregulations of neuronal progenitor markers but increase of senescence-associated proteins. Hence, upregulation of nNOS in neuronal cells imposes aging by SNOing of key players of ubiquitination, chaperones and of substrate proteins leading to interference with crucial steps of protein homeostasis.

Altered Expression of Phox2 Transcription Factors in the Locus Coeruleus in Major Depressive Disorder Mimicked by Chronic Stress and Corticosterone Treatment In Vivo and In Vitro

Phox2a and Phox2b are two homeodomain transcription factors playing a pivotal role in the development of noradrenergic neurons during the embryonic period. However, their expression and function in adulthood remain to be elucidated. Using human postmortem brain tissues, rat stress models and cultured cells, this study aimed to examine the alteration of Phox2a and Phox2b expression. The results show that Phox2a and Phox2b are normally expressed in the human locus coeruleus (LC) in adulthood. Furthermore, the levels of Phox2a protein and mRNA and protein levels of Phox2b were significantly elevated in the LC of brain donors that suffered from the major depressive disorder, as compared to age-matched and psychiatrically normal control donors. Fischer 344 rats subjected to chronic social defeat showed higher mRNA and protein levels of Phox2a and Phox2b in the LC, as compared to non-stressed control rats. In rats chronically administered oral corticosterone, mRNA and protein levels of Phox2b, but not Phox2a, in the LC were significantly increased. In addition, the corticosterone-induced increase in Phox2b protein was reversed by simultaneous treatment with either mifepristone or spironolactone. Exposing SH-SY5Y cells to corticosterone significantly increased expression of Phox2a and Phox2b, which was blocked by corticosteroid receptor antagonists. Taken together, these experiments reveal that Phox2 genes are expressed throughout the lifetime in the LC of humans and Fischer 344 rats. Alterations in their expression may play a role in major depressive disorder and possibly other stress-related disorders through their modulatory effects on the noradrenergic phenotype.

Silica nanoparticles induce conformational changes of tau protein and oxidative stress and apoptosis in neuroblastoma cell line

The adverse effects of SiO₂ NPs on the biological systems like nervous system have not been well explored. This study aimed to evaluate the toxicity of SiO₂ NPs on the nervous system in vitro. Therefore, human tau protein and neuroblastoma cell line (SH-SY5Y) were used as targets. In this study we examined the side effects of SiO₂ NPs on tau protein structure using several techniques including CD, ANS fluorescence, UV-vis (360 nm), Congo red absorbance, TEM, and molecular dynamic. Also, the cytotoxicity effects of SiO₂ NPs against SH-SY5Y cell line were evaluated using MTT, ROS and apoptotic assays. Spectroscopic and molecular dynamic investigations indicated that natively unfolded structure of tau in the presence of SiO₂ NPs experienced a partially folded and amorphous aggregated structure. Cellular assay demonstrated that SiO₂ NPs exerted cytotoxic effect on SH-SY5Y cells through ROS accumulation and induction of apoptosis. Overall, these findings proved that SiO₂ NPs could induce adverse effects on tau structure and SH-SY5Y cell integrity. Moreover, further studies are required to elucidate the molecular mechanism of SiO₂ NPs-induced side effects in vivo.

A critical role of the transient receptor potential melastatin 2 channel in a positive feedback mechanism for reactive oxygen species-induced delayed cell death

Transient receptor potential melastatin 2 (TRPM2) channel activation by reactive oxygen species (ROS) plays a critical role in delayed neuronal cell death, responsible for postischemia brain damage via altering intracellular Zn²⁺ homeostasis, but a mechanistic understanding is still lacking. Here, we showed that H₂ O₂ induced neuroblastoma SH-SY5Y cell death with a significant delay, dependently of the TRPM2 channel and increased [Zn²⁺ ]_i , and therefore used this cell model to investigate the mechanisms underlying ROS-induced TRPM2-mediated delayed cell death. H₂ O₂ increased concentration-dependently the [Zn²⁺ ]_i and caused lysosomal dysfunction and Zn²⁺ loss and, furthermore, mitochondrial Zn²⁺ accumulation, fragmentation, and ROS generation. Such effects were suppressed by preventing poly(adenosine diphosphate ribose, ADPR) polymerase-1-dependent TRPM2 channel activation with PJ34 and 3,3',5,5'-tetra-tert-butyldiphenoquinone, inhibiting the TRPM2 channel with 2-aminoethoxydiphenyl borate (2-APB) and N-(p-amylcinnamoyl)anthranilic acid, or chelating Zn²⁺ with N,N,N,N-tetrakis(2-pyridylmethyl)-ethylenediamine (TPEN). Bafilomycin-induced lysosomal dysfunction also resulted in mitochondrial Zn²⁺ accumulation, fragmentation, and ROS generation that were inhibited by PJ34 or 2-APB, suggesting that these mitochondrial events are TRPM2 dependent and sequela of lysosomal dysfunction. Mitochondrial TRPM2 expression was detected and exposure to ADPR-induced Zn²⁺ uptake in isolated mitochondria, which was prevented by TPEN. H₂ O₂ -induced delayed cell death was inhibited by apocynin and diphenyleneiodonium, nicotinamide adenine dinucleotide phosphate hydrogen (NADPH) oxidase (NOX) inhibitors, GKT137831, an NOX1/4-specific inhibitor, or Gö6983, a protein kinase C (PKC) inhibitor. Moreover, inhibition of PKC/NOX prevented H₂ O₂ -induced ROS generation, lysosomal dysfunction and Zn²⁺ release, and mitochondrial Zn²⁺ accumulation, fragmentation and ROS generation. Collectively, these results support a critical role for the TRPM2 channel in coupling PKC/NOX-mediated ROS generation, lysosomal Zn²⁺ release, and mitochondrial Zn²⁺ accumulation, and ROS generation to form a vicious positive feedback signaling mechanism for ROS-induced delayed cell death.

Glycyrrhizic Acid Alleviates 6-Hydroxydopamine and Corticosterone-Induced Neurotoxicity in SH-SY5Y Cells Through Modulating Autophagy

Recent researches have shown that autophagy is associated with the pathogenesis of neurodegenerative disorders, but there is no paper to investigate the effects of autophagy modulation on Parkinson's disease depression (PDD). In addition, glycyrrhizic acid (GA), the major bioactive ingredient of Radix glycyrrhizae, can induce autophagy and ease rotenone-induced Parkinson's disease (PD). However, there is also no paper to study the action and molecular mechanisms of GA on PDD. In this research, we built the injury model of SH-SY5Y cells through 6-hydroxydopamine (6-OHDA) and corticosterone (CORT). Then, our results showed that GA markedly increased the viability and decreased the apoptosis in SH-SY5Y cells after pre-treating with 6-OHDA and CORT. Moreover, GA notably decreased the expressions of α-Syn and p-S1292-LRRK2 proteins, and significantly increased the levels of CREB and BDNF proteins. Previous papers have suggested that CORT contributed to dopaminergic neurodegeneration via the glucocorticoid (GC)/glucocorticoid receptor (GR) interaction, and our results showed that GA reduced GC level and hypothalamic-pituitary-adrenal (HPA) activity in SH-SY5Y cells by regulating GR signaling pathway. Furthermore, mechanism investigations also showed that GA had the ability to up-regulate the conversion of LC3B II/I and the expression of Beclin-1, and induce autophagy in SH-SY5Y cells, which were reversed by the autophagy inhibitor 3-methyladenine (3-MA). Collectively, these findings proved that GA exerted efficient activity against neurotoxicity in SH-SY5Y cells induced by 6-OHDA and CORT via activation of autophagy, which should be developed as an efficient candidate for treating PDD in the future.

LGK974, a PORCUPINE inhibitor, mitigates cytotoxicity in an in vitro model of Parkinson's disease by interfering with the WNT/β-CATENIN pathway

Paraquat (PQ) as an herbicide has been demonstrated to impair dopaminergic (DAergic) neurons and highly correlate with the etiology of Parkinson's disease (PD). WNT/β-CATENIN signaling is known for the specification and neurogenesis of midbrain DAergic neurons and implicated as a therapeutic target in treating many diseases, such as cancer and degenerative diseases. LGK974, a WNT pathway inhibitor, is currently under clinical trial for patients with malignancies. Since the exact role of WNT/β-CATENIN signaling in mediating PD is undetermined, LGK974 was used to examine its effect on the PQ-induced cell model of PD. LGK974 attenuated PQ-induced apoptosis and released mitochondrial pro-poptotic molecules in human neuroblastoma SH-SY5Y cell. PQ increased the levels of β-CATENIN, non-phosphorylated (Ser33/37/Thr41) β-CATENIN, and phosphorylated glycogen synthase kinase (GSK)-3α/β. PQ also increased the nuclear translocation of β-CATENIN, which can be attenuated by LKG974. Furthermore, LGK974 attenuated the PQ-induced release of mitochondrial proapoptotic factors and WNT agonist 1-induced cell death. Taken together, we have shown for the first time that LGK974 mediated through the WNT/β-CATENIN pathway to prevent PQ-induced cell death.

Model systems for analysis of dopamine transporter function and regulation

The dopamine transporter (DAT) plays a critical role in dopamine (DA) homeostasis by clearing transmitter from the extraneuronal space after vesicular release. DAT serves as a site of action for a variety of addictive and therapeutic reuptake inhibitors, and transport dysfunction is associated with transmitter imbalances in disorders such as schizophrenia, attention deficit hyperactive disorder, bipolar disorder, and Parkinson disease. In this review, we describe some of the model systems that have been used for in vitro analyses of DAT structure, function and regulation, and discuss a potential relationship between transporter kinetic values and membrane cholesterol.

Punicalagin Exerts Beneficial Functions in 6-Hydroxydopamine-Treated SH-SY5Y Cells by Attenuating Mitochondrial Dysfunction and Inflammatory Responses

Background

Parkinson’s disease (PD) is a common age-related neurodegenerative disorder, but effective therapeutic agents for PD remain largely limited.

Material/Methods

In the present study, we evaluated the beneficial effects and underlying mechanisms of punicalagin (PN) in human neuroblastoma SH-SY5Y cells treated with 6-hydroxydopamine (6-OHDA) to mimic PD in vitro. Cell viability was monitored by MTT assay and LDH release assay. Cell apoptosis was assayed by Annexin V-FITC/PI double-staining. Intracellular ROS production was assessed by DCFH-DA staining. The expression levels of protein and mRNA were determined by Western blotting and qRT-PCR analysis, respectively.

Results

The results showed that pretreatment of SH-SY5Y cells with PN (50, 100, and 200 μM) prior to exposure to 200 μM 6-OHDA for 2 h resulted in increased cell viability and decreased cell apoptosis. PN also inhibited excessive oxidative stress in 6-OHDA-treated SH-SY5Y cells. Moreover, PN treatment effectively restored mitochondrial function and enhanced phosphorylation of AMPK. Furthermore, PN blocked 6-OHDA-induced NF-κB activation and IL-1β expression.

Conclusions

Our study shows that PN exhibited neuroprotective effects on the 6-OHDA-treated SH-SY5Y cells, thus providing a potential theoretical insight for the clinical application of PN against PD.

Positive Regulation of Transcription by Human ZMYND8 through Its Association with P-TEFb Complex

Although human ZMYND8 has been implicated as a transcriptional co-repressor of multiple targets, global association of ZMYND8 with active genes and enhancer regions predicts otherwise. Here, we report an additional function of ZMYND8 in transcriptional activation through its association with the P-TEFb complex. Biochemical reconstitution analyses show that human ZMYND8, through direct association with CylcinT1, forms a minimal ZMYND8-P-TEFb complex. The importance of ZMYND8 in target gene activation, through P-TEFb complex recruitment, is demonstrated on chromosomally integrated reporter gene as well as native target genes in vivo. Physiologically, we further show that the ZMYND8-P-TEFb complex-mediated transcriptional activation is required for all-trans retinoic acid (ATRA)-mediated differentiation of neuronal precursor cells. Finally, to detail the dual activator and repressor nature, mechanistically we show that, through its putative coiled-coil domain, ZMYND8 forms a homodimer that preferentially associates with the activator P-TEFb complex, whereas the monomer associates with the CHD4 subunit of repressor NuRD complex.

Necrosis in human neuronal cells exposed to paraquat

Paraquat (PQ) is an herbicide that was once used worldwide, but is now prohibited in many nations due to its high toxicity to humans. However, there are still rare cases of the fetal intoxication of PQ, which was purchased prior to the prohibition in Japan. In this study, several cell death pathways, the mitochondrial stress response, and autophagy were examined in SH-SY5Y cells exposed to PQ. The results reveal the decrease of a mitochondrial stress sensitive-BNIP3 (Bcl-2/adenovirus E1B 19-kDa-interacting protein 3) protein, the suppression of autophagic flux, and the lack of apoptosis as well as other regulated forms of necrosis, such as necroptosis and ferroptosis. Taken together, our preliminary survey of cellular responses against PQ shows that, although responses of mitochondria and autophagy are observed, subsequent cell death is necrosis. Mechanism of PQ-induced SH-SY5Y cell death should be complicated and cannot be explained thoroughly by already-known mechanisms.

Evaluation of the Antioxidant and Neuroprotectant Activities of New Asymmetrical 1,3-Diketones

A series of fourteen new asymmetrical 1,3-diketone derivatives have been synthesized and evaluated in the ABTS, FRAP and DPPH assays as a new chemotype with antioxidant and drug-like properties. All the compounds displayed low cytotoxicity in comparison to curcumin against the human neuroblastoma SH-SY5Y cell line. Among them, (3Z,5E)-6-(2,5-difluoro-4-hydroxy-phenyl)-1,1,1-trifluoro-4-hydroxyhexa-3,5-dien-2-one (6b) and (3Z,5E)-6-(2,3-difluoro-4-hydroxy-phenyl)-1,1,1-trifluoro-4-hydroxyhexa-3,5-dien-2-one (7b) with excellent solubility and chemical stability in biorelevant media, have also shown a similar Fe+2 chelation behavior to that of curcumin. Additionally, both derivatives 6b and 7b have afforded good neuroprotection activity against H₂O₂ induced oxidative stress in the same neuronal cell line, with a significant reduction of intracellular ROS levels, in parallel with a good recovery of the Mitochondrial Membrane Potential (ΔΨm). Compounds 6b and 7b with a promising antioxidant and drug-like profile, with low cytotoxic and good neuroprotectant activity, constitute a new interesting chemical class with high potential as new therapeutic agents against neurodegenerative diseases.

On-chip Detection of Single Vesicle Release from Neuroblastoma Cells using Monolithic CMOS Bioelectronics

Neuroblastoma cells are often used as a cell model to study Parkinson's disease, which causes reduced dopamine release in substantia nigra, the midbrain that controls movements. In this paper, we developed a 1024-ch monolithic CMOS sensor array that has the spatiotemporal resolution as well as low-noise performance to monitor single vesicle release of dopamine from neuroblastoma cells. The CMOS device integrates 1024 on-chip electrodes with an individual size of $15 \mu \mathrm{m}\times 15 \mu \mathrm{m}$ and 1024 transimpedance amplifiers for each electrode, which are each capable of measuring sub-pA current. Thus, this device can be used to study the detailed molecular dynamics of dopamine secretion at single vesicle resolution.

NCX1 and NCX3 as potential factors contributing to neurodegeneration and neuroinflammation in the A53T transgenic mouse model of Parkinson's Disease

Na⁺-Ca²⁺ exchanger (NCX) isoforms constitute the major cellular Ca²⁺ extruding system in neurons and microglia. We herein investigated the role of NCX isoforms in the pathophysiology of Parkinson's disease (PD). Their expression and activity were evaluated in neurons and glia of mice expressing the human A53T variant of α-synuclein (A53T mice), an animal model mimicking a familial form of PD. Western blotting revealed that NCX3 expression in the midbrain of 12-month old A53T mice was lower than that of wild type (WT). Conversely, NCX1 expression increased in the striatum. Immunohistochemical studies showed that glial fibrillary acidic protein (GFAP)-positive astroglial cells significantly increased in the substantia nigra pars compacta (SNc) and in the striatum. However, the number and the density of tyrosine hydroxylase (TH)-positive neurons decreased in both brain regions. Interestingly, ionized calcium binding adaptor molecule 1 (IBA-1)-positive microglial cells increased only in the striatum of A53T mice compared to WT. Double immunostaining studies showed that in A53T mice, NCX1 was exclusively co-expressed in IBA-1-positive microglial cells in the striatum, whereas NCX3 was solely co-expressed in TH-positive neurons in SNc. Beam walking and pole tests revealed a reduction in motor performance for A53T mice compared to WT. In vitro experiments in midbrain neurons from A53T and WT mice demonstrated a reduction in NCX3 expression, which was accompanied by mitochondrial overload of Ca²⁺ ions, monitored with confocal microscopy by X-Rhod-1 fluorescent dye. Collectively, in vivo and in vitro findings suggest that the reduction in NCX3 expression and activity in A53T neurons from midbrain may cause mitochondrial dysfunction and neuronal death in this brain area, whereas NCX1 overexpression in microglial cells may promote their proliferation in the striatum.

Protective Effects of Donepezil Against Alcohol-Induced Toxicity in Cell Culture: Role of Caspase-3

Ethanol (EtOH) is one of the most frequently abused drugs with heavy health, economic, and societal burdens. Although moderate to low EtOH may have some neuroprotective effects, heavy EtOH consumption associated with high blood alcohol level (BAL) can be quite detrimental. The brain is particularly vulnerable to the damaging effects of high BAL, leading to neuronal loss, cognitive, and behavioral deficits. Although the exact causes of these detriments are not fully elucidated, it is believed that damage to the cholinergic system is at least partially responsible for the cognitive impairment. Thus, high BAL may result in selective apoptotic damage to the cholinergic neurons. Donepezil (DON), a centrally acting, reversible and non-competitive acetylcholinesterase (AChE) inhibitor, approved for use in Alzheimer's disease (AD), may also attenuate EtOH-induced cognitive impairment. Cognitive effects of DON might be due to an anti-apoptotic activity as some AChE inhibitors have been shown to have this property. The aim of this study was to determine whether DON might protect against EtOH-induced toxicity and whether such protection might be apoptotically mediated. We exposed the human neuroblastoma-derived, SH-SY5Y cells to a relatively high concentration of EtOH (500 mM) for 24 h and evaluated the effects of two concentrations of DON (0.1 and 1.0 μM) on alcohol-induced toxicity and caspase-3, an apoptotic marker. We found a dose-dependent protection of DON against EtOH-induced toxicity as well as dose-dependent attenuation of EtOH-induced increases in caspase-3 levels. Thus, DON may inhibit apoptosis as well as alcohol-induced toxicity.

Differentiation-Induced Remodelling of Store-Operated Calcium Entry Is Independent of Neuronal or Glial Phenotype but Modulated by Cellular Context

Neurogenesis is a complex process leading to the generation of neuronal networks and glial cell types from stem cells or intermediate progenitors. Mapping subcellular and molecular changes accompanying the switch from proliferation to differentiation is vital for developing therapeutic targets for neurological diseases. Neuronal (N-type) and glial (S-type) phenotypes within the SH-SY5Y neuroblastoma cell line have distinct differentiation responses to 9-cis-retinoic acid (9cRA). In both cell phenotypes, these were accompanied at the single cell level by an uncoupling of Ca²⁺ store release from store-operated Ca²⁺ entry (SOCE), mediated by changes in the expression of calcium release-activated calcium pore proteins. This remodelling of calcium signalling was moderated by the predominant cell phenotype within the population. N- and S-type cells differed markedly in their phenotypic stability after withdrawal of the differentiation inducer, with the phenotypic stability of S-type cells, both morphologically and with respect to SOCE properties, in marked contrast to the lability of the N-type phenotype. Furthermore, the SOCE response of I-type cells, a presumed precursor to both N- and S-type cells, varied markedly in different cell environments. These results demonstrate the unique biology of neuronal and glial derivatives of common precursors and suggest that direct or indirect interactions between cell types are vital components of neurogenesis that need to be considered in experimental models.

Silver Nanoparticles: Two-Faced Neuronal Differentiation-Inducing Material in Neuroblastoma (SH-SY5Y) Cells

We have previously demonstrated the potential of biologically synthesized silver nanoparticles (AgNP) in the induction of neuronal differentiation of human neuroblastoma, SH-SY5Y cells; we aimed herein to unveil its molecular mechanism in comparison to the well-known neuronal differentiation-inducing agent, all-trans-retinoic acid (RA). AgNP-treated SH-SY5Y cells showed significantly higher reactive oxygen species (ROS) generation, stronger mitochondrial membrane depolarization, lower dual-specificity phosphatase expression, higher extracellular-signal-regulated kinase (ERK) phosphorylation, lower AKT phosphorylation, and lower expression of the genes encoding the antioxidant enzymes than RA-treated cells. Notably, pretreatment with N-acetyl-l-cysteine significantly abolished AgNP-induced neuronal differentiation, but not in that induced by RA. ERK inhibition, but not AKT inhibition, suppresses neurite growth that is induced by AgNP. Taken together, our results uncover the pivotal contribution of ROS in the AgNP-induced neuronal differentiation mechanism, which is different from that of RA. However, the negative consequence of AgNP-induced neurite growth may be high ROS generation and the downregulation of the expression of the genes encoding the antioxidant enzymes, which prompts the future consideration and an in-depth study of the application of AgNP-differentiated cells in neurodegenerative disease therapy.

Network Analysis of UBE3A/E6AP-Associated Proteins Provides Connections to Several Distinct Cellular Processes

Perturbations in activity and dosage of the UBE3A ubiquitin-ligase have been linked to Angelman syndrome and autism spectrum disorders. UBE3A was initially identified as the cellular protein hijacked by the human papillomavirus E6 protein to mediate the ubiquitylation of p53, a function critical to the oncogenic potential of these viruses. Although a number of substrates have been identified, the normal cellular functions and pathways affected by UBE3A are largely unknown. Previously, we showed that UBE3A associates with HERC2, NEURL4, and MAPK6/ERK3 in a high-molecular-weight complex of unknown function that we refer to as the HUN complex (HERC2, UBE3A, and NEURL4). In this study, the combination of two complementary proteomic approaches with a rigorous network analysis revealed cellular functions and pathways in which UBE3A and the HUN complex are involved. In addition to finding new UBE3A-associated proteins, such as MCM6, SUGT1, EIF3C, and ASPP2, network analysis revealed that UBE3A-associated proteins are connected to several fundamental cellular processes including translation, DNA replication, intracellular trafficking, and centrosome regulation. Our analysis suggests that UBE3A could be involved in the control and/or integration of these cellular processes, in some cases as a component of the HUN complex, and also provides evidence for crosstalk between the HUN complex and CAMKII interaction networks. This study contributes to a deeper understanding of the cellular functions of UBE3A and its potential role in pathways that may be affected in Angelman syndrome, UBE3A-associated autism spectrum disorders, and human papillomavirus-associated cancers.

A brain targeting functionalized liposomes of the dopamine derivative N-3,4-bis(pivaloyloxy)-dopamine for treatment of Parkinson's disease

Parkinson's disease (PD) remains one of the most common neurodegenerative movement disorders with limited treatment options available. A dopamine derivative N-3,4-bis(pivaloyloxy)-dopamine (BPD) previously developed in our group has demonstrated superior therapeutic outcome compared to levodopa in a PD mice model. To further improve the therapeutic performance of BPD, a brain targeted drug delivery system was designed using a 29 amino-acid peptide (RVG29) derived from rabies virus glycoprotein as the targeting ligand. RVG29 functionalized liposomes (RVG29-lip) showed significantly higher uptake efficiency in murine brain endothelial cells and dopaminergic cells, and high penetration efficiency across the blood brain barrier (BBB) in vitro. In vivo and ex vivo distribution studies demonstrated RVG29-lip selectively distributed to the brain, striatum and substantia nigra. Furthermore, BPD loaded RVG29-lip (BPD-RVG29-lip) exhibited improved therapeutic efficacy in a PD mouse model, while causing no obvious systemic toxicity after intravenous administration. Thus, BPD-RVG29-lip represents a highly promising approach for the brain targeted treatment of PD.

Different Conformational Subensembles of the Intrinsically Disordered Protein α-Synuclein in Cells

The intrinsically disordered protein α-synuclein (αS) is thought to play an important role in cellular membrane processes. Although in vitro experiments indicate that this initially disordered protein obtains structure upon membrane binding, NMR and EPR studies in cells could not single out any conformational subensemble. Here we microinjected small amounts of αS, labeled with a Förster resonance energy transfer (FRET) pair, into SH-SY5Y cells to investigate conformational changes upon membrane binding. Our FRET studies show a clear conformational difference between αS in the cytosol and when bound to small vesicles. The identification of these different conformational subensembles inside cells resolves the apparent contradiction between in vitro and in vivo experiments and shows that at least two different conformational subensembles of αS exist in cells. The existence of conformational subensembles supports the idea that αS can obtain different functions which can possibly be dynamically addressed with changing intracellular physicochemical conditions.

Deciphering the pathways that protect from IL-13-mediated potentiation of oxidative stress-induced dopaminergic nerve cell death

The majority of Parkinson's disease (PD) cases are sporadic with only about 10% of PD patients having a family history of the disease suggesting that this neurodegenerative disorder is the result of both environmental and genetic factors. Both oxidative stress and neuroinflammation are thought to contribute to PD. Previously, we showed that the activation of interleukin 13 receptor alpha 1 (IL-13Rα1) increases the sensitivity of dopaminergic neurons to oxidative damage both in cultured cells and in animals. In this study, we investigated the pathways involved in the IL-13-mediated potentiation of oxidative stress-induced dopaminergic cell death using a combination of cell survival assays and Western blotting with appropriate antibodies. In addition, siRNA was used to examine the role of 4E-BP1 in this cell toxicity paradigm. We show that activation of both the Jak-Stat and PI3 kinase-mTOR pathways play key roles in the promotion of cell death by IL-13 in the presence of mild oxidative stress. The Jak 1/2 inhibitor ruxolitinib, the mTOR inhibitor rapamycin and the PI3 kinase inhibitor LY294002 all prevented the potentiation of cell death by IL-13. Moreover, 4E-BP1, a target of mTOR, appeared to mediate the protective effects of rapamycin. Together, these results indicate that multiple signaling pathways downstream of IL-13Rα1 activation play a role in the toxic effects of IL-13 in dopaminergic neurons in the presence of mild oxidative stress and suggest that any of these pathways might provide potential targets for the treatment of PD.

Drp-1 dependent mitochondrial fragmentation and protective autophagy in dopaminergic SH-SY5Y cells overexpressing alpha-synuclein

Parkinson's disease is a neurodegenerative movement disorder caused by the loss of dopaminergic neurons from substantia nigra. It is characterized by the accumulation of aggregated α-synuclein as the major component of the Lewy bodies. Additional common features of this disease are the mitochondrial dysfunction and the activation/inhibition of autophagy both events associated to the intracellular accumulation of α-synuclein. The mechanism by which these events contribute to neural degeneration remains unknown. In the present work we investigated the effect of α-synuclein on mitochondrial dynamics and autophagy/mitophagy in SH-SY5Y cells, an in vitro model of Parkinson disease. We demonstrated that overexpression of wild type α-synuclein causes moderated toxicity, ROS generation and mitochondrial dysfunction. In addition, α-synuclein induces the mitochondrial fragmentation on a Drp-1-dependent fashion. Overexpression of the fusion protein Opa-1 prevented both mitochondrial fragmentation and cytotoxicity. On the other hand, cells expressing α-synuclein showed activated autophagy and particularly mitophagy. Employing a genetic strategy we demonstrated that autophagy is triggered in order to protect cells from α-synuclein-induced cell death. Our results clarify the role of Opa-1 and Drp-1 in mitochondrial dynamics and cell survival, a controversial α-synuclein research issue. The findings presented point to the relevance of mitochondrial homeostasis and autophagy in the pathogenesis of PD. Better understanding of the molecular interaction between these processes could give rise to novel therapeutic methods for PD prevention and amelioration.

Inhibition of miR-181a promotes midbrain neuronal growth through a Smad1/5-dependent mechanism: implications for Parkinson's disease

Parkinson's disease (PD) is the second most common neurodegenerative disease, and is characterized by the progressive degeneration of nigrostriatal dopaminergic (DA) neurons. Current PD treatments are symptomatic, wear off over time and do not protect against DA neuronal loss. Finding a way to re-grow midbrain DA (mDA) neurons is a promising disease-modifying therapeutic strategy for PD. However, reliable biomarkers are required to allow such growth-promoting approaches to be applied early in the disease progression. miR-181a has been shown to be dysregulated in PD patients, and has been identified as a potential biomarker for PD. Despite studies demonstrating the enrichment of miR-181a in the brain, specifically in neurites of postmitotic neurons, the role of miR-181a in mDA neurons remains unknown. Herein, we used cell culture models of human mDA neurons to investigate a potential role for miR-181a in mDA neurons. We used a bioninformatics analysis to identify that miR-181a targets components of the bone morphogenetic protein (BMP) signalling pathway, including the transcription factors Smad1 and Smad5, which we find are expressed by rat mDA neurons and are required for BMP-induced neurite growth. We also found that inhibition of neuronal miR-181a, resulted in increased Smad signalling, and induced neurite growth in SH-SY5Y cells. Finally, using embryonic rat cultures, we demonstrated that miR-181a inhibition induces ventral midbrain (VM) and cortical neuronal growth. These data describe a new role for miR-181a in mDA neurons, and provide proof of principle that miR-181a dysresgulation in PD may alter the activation state of signalling pathways important for neuronal growth in neurons affected in PD.

Genome-Edited, TH-expressing Neuroblastoma Cells as a Disease Model for Dopamine-Related Disorders: A Proof-of-Concept Study on DJ-1-deficient Parkinsonism

Impairment of the dopaminergic (DA) system is a common cause of several movement disorders including Parkinson's disease (PD), however, little is known about the underlying disease mechanisms. The recent development of stem-cell-based protocols for the generation of DA neurons partially solved this issue, however, this technology is costly and time-consuming. Commonly used cell lines, i.e., neuroblastoma (SHSY5Y) and PC12 cells are still widely used to investigate PD and significantly contributed to our understanding of mechanisms involved in development of the disease. However, they either do not express DA at all or require additional, only partially efficient differentiations in order to produce DA. Here we generated and characterized transgenic SH-SY5Y cells, ectopically expressing tyrosine hydroxylase (SH^TH+), that can be used as a homogenous, DA-producing model to study alterations in DA metabolism and oxidative stress. We demonstrated that SH^TH+ produce high levels of DA, 3,4-dihydroxyphenylacetic acid (DOPAC), and homovanillic acid (HVA) making this model suitable to investigate not only alterations in DA synthesis but also its turnover. We also provide evidence for the presence of other enzymes involved in DA synthesis and its turnover in these cells. Finally, we showed that these cells can easily be genetically modified using CRISPR/Cas9 technology in order to study genetically defined forms of movement disorders using DJ1-linked PD as a model.

B, Norma RF, Jorge A. LR, Perla Y. LC, Gustavo BI. Fullerenemalonates inhibit amyloid beta aggregation, in vitro and in silico evaluation

The onset of Alzheimer's disease (AD) is associated with the presence of neurofibrillary pathology such as amyloid β (Aβ) plaques. Different therapeutic strategies have focused on the inhibition of Aβ aggregate formation; these pathological structures lead to neuronal disorder and cognitive impairment. Fullerene C₆₀ has demonstrated the ability to interact and prevent Aβ fibril development; however, its low solubility and toxicity to cells remain significant problems. In this study, we synthesized, characterized and compared diethyl fullerenemalonates and the corresponding sodium salts, adducts of C₆₀ bearing 1 to 3 diethyl malonyl and disodium malonyl substituents to evaluate the potential inhibitory effect on the aggregation of Aβ₄₂ and their biocompatibility. The dose-dependent inhibitory effect of fullerenes on Aβ₄₂ aggregation was studied using a thioflavin T fluorescent assay, and the IC₅₀ value demonstrated a low range of fullerene concentration for inhibition, as confirmed by electron microscopy. The exposure of neuroblastoma to fullerenemalonates showed low toxicity, primarily in the presence of the sodium salt-adducts. An isomeric mixture of bisadducts, trisadducts and a C₃-symetrical trisadduct demonstrated the highest efficacy among the tests. In silico calculations were performed to complement the experimental data, obtaining a deeper understanding of the Aβ inhibitory mechanism; indicating that C₃-symetrical trisadduct interacts mainly with 1D to 16K residues of Aβ₄₂ peptide. These data suggest that fullerenemalonates require specific substituents designed as sodium salt molecules to inhibit Aβ fibrillization and perform with low toxicity. These are promising molecules for developing future therapies involving Aβ aggregates in diseases such as AD and other types of dementia.

Synthesis of new non toxic nanomaterials, with high anti-amyloid fibrils formation effect, in vitro and in silico.

Parkinson's Disease Model

Parkinson's disease (PD) is the second most common neurodegenerative disease worldwide. It is known that there are many factors, either genetic or environmental factors, involved in PD, but the mechanism of PD is still not fully understood. Several animal models have been established to study the mechanisms of PD. Among these models, Drosophila melanogaster has been utilized as a valuable model to get insight into important features of PD. Drosophila melanogaster possesses a well-developed dopaminergic (DA) neuron system which is known to play an important role in PD pathogenesis. The well understanding of DA neurons from early larval through adult stage makes Drosophila as a powerful model for investigating the progressive neurodegeneration in PD. Besides, the short life cycle of Drosophila melanogaster serves an advantage in studying epidemiological features of PD. Most of PD symptoms can be mimicked in Drosophila model such as progressive impairment in locomotion, DA neuron degeneration, and some other non-motor symptoms. The Drosophila models of PD, therefore, show a great potential in application for PD genetic and drug screening.

Compressional-Puffing Pretreatment Enhances Neuroprotective Effects of Fucoidans from the Brown Seaweed Sargassum hemiphyllum on 6-Hydroxydopamine-Induced Apoptosis in SH-SY5Y Cells

In this study, a compressional-puffing process (CPP) was used to pretreat Sargassum hemiphyllum (SH) and then fucoidan was extracted from SH by hot water. Three fucoidan extracts, namely SH1 (puffing at 0 kg/cm²); SH2 (puffing at 1.7 kg/cm²); and SH3 (puffing at 10.0 kg/cm²) were obtained, and their compositions and biological activities were evaluated. The results indicate that CPP increased the extraction yield, total sugar content, and molar ratios of sulfate/fucose of fucoidan and decreased molecular weight and impurities of fucoidan. The SH1-SH3 extracts exhibited characteristics of fucoidan as demonstrated by the analyses of composition, FTIR spectroscopy, NMR spectroscopy, and molecular weight. All SH1-SH3 extracts showed antioxidant activities. The SH1-SH3 extracts protected SH-SY5Y cells from 6-hydroxydopamine (6-OHDA)-induced apoptosis as illustrated by cell cycle distribution, cytochrome c release, activation of caspase-8, -9, and -3, and DNA fragmentation analyses. Additional experiments revealed that phosphorylation of Akt is involved in the opposing effects of SH1-SH3 on 6-OHDA-induced neurotoxicity. SH3 exhibited a relatively high extraction yield, the lowest levels of impurities, and was the most effective at reversing the 6-OHDA-induced neurotoxicity of SH-SY5Y cells among SH1-SH3, which taken together indicate that it may have potential as a candidate therapeutic agent for the preventive therapy of neurodegenerative diseases.

Curcumin nanocapsules stabilized by bovine serum albumin-capped gold nanoclusters (BSA-AuNCs) for drug delivery and theranosis

Nanotechnology plays an important role in the development of drug delivery, imaging, and diagnosis. In this study, nanocapsules containing protein-functionalized gold nanoclusters (AuNCs) as the shell and hydrophobic drug curcumin as the core were prepared as a tumor cell theranostic agent. After the nanocapsules were added into tumor cell media, they entered the cells with high efficiency and exhibited strong fluorescence within the cells. The results indicated that the nanocapsules were broken up in the cells and curcumin was released. Simultaneously, the nanocapsules exhibited significant inhibition effect against tumor cell proliferation in a concentration- and time-dependent manner, and the images of atomic force microscopy (AFM) showed that the cell morphology underwent obvious changes after the capsule treatment. Additionally, cell membrane appeared wrinkles after the cells treated with the nanocapsules, resulting in a rough cell surface, implying that the cytoskeleton would involve in the cell uptake of nanocapsules. Moreover, the AuNCs and curcumin in the system could exert synergistic effect on the inhibition of tumor cell growth and induction of cell apoptosis. The study highlights the potential of the system as a promising agent for drug delivery and tumor cell theranosis.

Development of an iron-selective antioxidant probe with protective effects on neuronal function

Iron accumulation, oxidative stress and calcium signaling dysregulation are common pathognomonic signs of several neurodegenerative diseases, including Parkinson´s and Alzheimer’s diseases, Friedreich ataxia and Huntington’s disease. Given their therapeutic potential, the identification of multifunctional compounds that suppress these damaging features is highly desirable. Here, we report the synthesis and characterization of N-(1,3-dihydroxy-2-(hydroxymethyl)propan-2-yl)-2-(7-hydroxy-2-oxo-2H-chromen-4-yl)acetamide, named CT51, which exhibited potent free radical neutralizing activity both in vitro and in cells. CT51 bound Fe²⁺ with high selectivity and Fe³⁺ with somewhat lower affinity. Cyclic voltammetric analysis revealed irreversible binding of Fe³⁺ to CT51, an important finding since stopping Fe²⁺/Fe³⁺ cycling in cells should prevent hydroxyl radical production resulting from the Fenton-Haber-Weiss cycle. When added to human neuroblastoma cells, CT51 freely permeated the cell membrane and distributed to both mitochondria and cytoplasm. Intracellularly, CT51 bound iron reversibly and protected against lipid peroxidation. Treatment of primary hippocampal neurons with CT51 reduced the sustained calcium release induced by an agonist of ryanodine receptor-calcium channels. These protective properties of CT51 on cellular function highlight its possible therapeutic use in diseases with significant oxidative, iron and calcium dysregulation.

Protective effects of γ-mangostin on 6-OHDA-induced toxicity in SH-SY5Y cells

γ-Mangostin is a xanthone with hydroxyl groups that confer the substance-free radical scavenging effects. As opposed to the other more extensively studied mangostins, scarce research has been conducted on neuroprotective effects of γ-mangostin on models of Parkinson's disease (PD). Therefore, this investigation aimed to elucidate its antioxidant and neuroprotective effects on 6-OHDA-induced toxicity in SH-SY5Y cells. 6-OHDA treatment, an inducer of PD pathology in vitro studies, decreased cell viability and increased the level of intracellular ROS production. Furthermore, the substance-induced the expression of phosphorylated p38 MAPK, negatively affected the Bax/Bcl-2 ratio and increased caspase-3 activity; all of which were factors that are associated with apoptosis. Pretreatment of cells with γ-mangostin at concentrations of 0.5, 1, and 2.5μM markedly increased cell survival and reduced the level of intracellular ROS formation as shown by DPPH radical scavenging activity of the compound. Furthermore, a significant suppression of p-p38, improved Bax/Bcl-2 ratio expression, and reduced caspase-3 activity was exhibited in the cells after γ-mangostin pretreatment. The reduction of apoptosis was further supported by the reduction of pyknotic nuclei indicated by Hoescht 33342 staining. These findings indicate that γ-mangostin could attenuate 6-OHDA-induced neuronal cell death and that the protective effect of γ-mangostin is associated with its antioxidative potential and through the modulation of the apoptotic signalling pathway. Therefore, γ-mangostin may be an effective xanthone among other mangostins for preventing neurodegeneration in PD caused by oxidative stress.

In situ fibrillizing amyloid-beta 1-42 induces neurite degeneration and apoptosis of differentiated SH-SY5Y cells

The progression of Alzheimer’s disease is causatively linked to the accumulation of amyloid-β aggregates in the brain, however, it is not clear how the amyloid aggregates initiate the death of neuronal cells. The in vitro toxic effects of amyloid peptides are most commonly examined using the human neuroblastoma derived SH-SY5Y cell line and here we show that differentiated neuron-like SH-SY5Y cells are more sensitive to amyloid peptides than non-differentiated cells, because the latter lack long neurites. Exogenous soluble amyloid-β 1–42 covered cell bodies and whole neurites in differentiated cells with dense fibrils, causing neurite beading and fragmentation, whereas preformed amyloid-β 1–42 fibrils had no toxic effects. Importantly, spontaneously fibrillizing amyloid-β 1–42 peptide exhibited substantially higher cellular toxicity than amyloid-β 1–40, which did not form fibrils under the experimental conditions. These results support the hypothesis that peptide toxicity is related to the active fibrillization process in the incubation mixture.

(-)-Phenserine inhibits neuronal apoptosis following ischemia/reperfusion injury

Stroke commonly leads to adult disability and death worldwide. Its major symptoms are spastic hemiplegia and discordant motion, consequent to neuronal cell death induced by brain vessel occlusion. Acetylcholinesterase (AChE) is upregulated and allied with inflammation and apoptosis after stroke. Recent studies suggest that AChE inhibition ameliorates ischemia-reperfusion injury and has neuroprotective properties. (-)-Phenserine, a reversible AChE inhibitor, has a broad range of actions independent of its AChE properties, including neuroprotective ones. However, its protective effects and detailed mechanism of action in the rat middle cerebral artery occlusion model (MCAO) remain to be elucidated. This study investigated the therapeutic effects of (-)-phenserine for stroke in the rat focal cerebral ischemia model and oxygen-glucose deprivation/reperfusion (OGD/RP) damage model in SH-SY5Y neuronal cultures. (-)-Phenserine mitigated OGD/PR-induced SH-SY5Y cell death, providing an inverted U-shaped dose-response relationship between concentration and survival. In MCAO challenged rats, (-)-phenserine reduced infarction volume, cell death and improved body asymmetry, a behavioral measure of stoke impact. In both cellular and animal studies, (-)-phenserine elevated brain-derived neurotrophic factor (BDNF) and B-cell lymphoma 2 (Bcl-2) levels, and decreased activated-caspase 3, amyloid precursor protein (APP) and glial fibrillary acidic protein (GFAP) expression, potentially mediated through the ERK-1/2 signaling pathway. These actions mitigated neuronal apoptosis in the stroke penumbra, and decreased matrix metallopeptidase-9 (MMP-9) expression. In synopsis, (-)-phenserine significantly reduced neuronal damage induced by ischemia/reperfusion injury in a rat model of MCAO and cellular model of OGD/RP, demonstrating that its anti-apoptotic/neuroprotective/neurotrophic cholinergic and non-cholinergic properties warrant further evaluation in conditions of brain injury.

Zeb2 is a negative regulator of midbrain dopaminergic axon growth and target innervation

Neural connectivity requires neuronal differentiation, axon growth, and precise target innervation. Midbrain dopaminergic neurons project via the nigrostriatal pathway to the striatum to regulate voluntary movement. While the specification and differentiation of these neurons have been extensively studied, the molecular mechanisms that regulate midbrain dopaminergic axon growth and target innervation are less clear. Here we show that the transcription factor Zeb2 cell-autonomously represses Smad signalling to limit midbrain dopaminergic axon growth and target innervation. Zeb2 levels are downregulated in the embryonic rodent midbrain during the period of dopaminergic axon growth, when BMP pathway components are upregulated. Experimental knockdown of Zeb2 leads to an increase in BMP-Smad-dependent axon growth. Consequently there is dopaminergic hyperinnervation of the striatum, without an increase in the numbers of midbrain dopaminergic neurons, in conditional Zeb2 (Nestin-Cre based) knockout mice. Therefore, these findings reveal a new mechanism for the regulation of midbrain dopaminergic axon growth during central nervous system development.

Mimicking Parkinson's Disease in a Dish: Merits and Pitfalls of the Most Commonly used Dopaminergic In Vitro Models

Parkinson's disease (PD) is the second most common neurodegenerative disorder and has both unknown etiology and non-curative therapeutic options. Patients begin to present the classic motor symptoms of PD-tremor at rest, bradykinesia and rigidity-once 50-70% of the dopaminergic neurons of the nigrostriatal pathway have degenerated. As a consequence of this, it is difficult to investigate the early-stage events of disease pathogenesis. In vitro experimental models are used extensively in PD research because they present a controlled environment that enables the direct investigation of the early molecular mechanisms that are potentially involved with dopaminergic degeneration, as well as for the screening of potential therapeutic drugs. However, the establishment of PD in vitro models is a controversial issue for neuroscience research not only because it is challenging to mimic, in isolated cell systems, the physiological neuronal environment, but also the pathophysiological conditions experienced by human dopaminergic cells in vivo during the progression of the disease. Since no previous work has attempted to systematically review the literature regarding the establishment of an optimal in vitro model, and/or the features presented by available models used in the PD field, this review aims to summarize the merits and limitations of the most widely used dopaminergic in vitro models in PD research, which may help the PD researcher to choose the most appropriate model for studies directed at the elucidation of the early-stage molecular events underlying PD onset and progression.

Impact of Vital Dyes on Cell Viability and Transduction Efficiency of AAV Vectors Used in Retinal Gene Therapy Surgery: An In Vitro and In Vivo Analysis

Purpose

Treatment of inherited retinal degenerations using adeno-associated viral (AAV) vectors involves delivery by subretinal injection. In the latter stages, alteration of normal anatomy may cause difficulty in visualizing the retinotomy, retinal detachment extension, and vector diffusion. Vital dyes may be useful surgical adjuncts, but their safety and impact on AAV transduction are largely unknown.

Methods

The effects of Sodium Fluorescein (SF), Membrane Blue (MB), and Membrane Blue Dual (DB) at a range of dilutions were assessed on human embryonic kidney cells in vitro using an AAV2-green fluorescent protein (GFP) reporter at different multiplicities of infection. Flow cytometry analysis was performed to assess both cell viability and transduction efficiency. The effect on quantitative (q)PCR titer was determined. Balanced salt solution (BSS) or dilute DB (1:5 in BSS) were delivered subretinally into left/right eyes of C57BL/6J mice (n = 12). Retinal structure and function were analyzed by optical coherence tomography, autofluorescence, dark-and light-adapted full-field electroretinography.

Results

DB and MB were not toxic at any concentration tested, SF only when undiluted. The presence of dyes did not adversely affect the genomic titer. DB even increased the values, due to presence of surfactant in the formulation. AAV2-GFP transduction efficiency was not reduced by the dyes. No structural and functional toxic effects were observed following subretinal delivery of DB.

Conclusions

Only undiluted SF affected cell viability. No effects on qPCR titer and transduction efficiency were observed. DB does not appear toxic when delivered subretinally and improves titer accuracy. DB may therefore be a safe and helpful adjunct during gene therapy surgery.

Translational Relevance

This paper might be of interest to the retinal gene therapy community: it is a “bench to bedside” research paper about the potential use of dyes as a surgical adjunct during the gene therapy surgery. We have tested the potential toxicity and impact on transduction efficiency in an in vitro and in vivo model.

Identification of potential therapeutic compounds for Parkinson's disease using Drosophila and human cell models

Parkinson's disease (PD) is the second most common neurodegenerative disorder after Alzheimer's disease. It is caused by a loss of dopaminergic neurons in the substantia nigra pars compacta, leading to a decrease in dopamine levels in the striatum and thus producing movement impairment. Major physiological causes of neurodegeneration in PD are oxidative stress (OS) and mitochondrial dysfunction; these pathophysiological changes can be caused by both genetic and environmental factors. Although most PD cases are sporadic, it has been shown that 5-10% of them are familial forms caused by mutations in certain genes. One of these genes is the DJ-1 oncogene, which is involved in an early-onset recessive PD form. Currently, PD is an incurable disease for which existing therapies are not sufficiently effective to counteract or delay the progression of the disease. Therefore, the discovery of alternative drugs for the treatment of PD is essential. In this study we used a Drosophila PD model to identify candidate compounds with therapeutic potential for this disease. These flies carry a loss-of-function mutation in the DJ-1β gene, the Drosophila ortholog of human DJ-1, and show locomotor defects reflected by a reduced climbing ability. A pilot modifier chemical screen was performed, and several candidate compounds were identified based on their ability to improve locomotor activity of PD model flies. We demonstrated that some of them were also able to reduce OS levels in these flies. To validate the compounds identified in the Drosophila screen, a human cell PD model was generated by knocking down DJ-1 function in SH-SY5Y neuroblastoma cells. Our results showed that some of the compounds were also able to increase the viability of the DJ-1-deficient cells subjected to OS, thus supporting the use of Drosophila for PD drug discovery. Interestingly, some of them have been previously proposed as alternative therapies for PD or tested in clinical trials and others are first suggested in this study as potential drugs for the treatment of this disease.

Comparison of neurons derived from mouse P19, rat PC12 and human SH-SY5Y cells in the assessment of chemical- and toxin-induced neurotoxicity

Background

Exposure to chemicals might be toxic to the developing brain. There is a need for simple and robust in vitro cellular models for evaluation of chemical-induced neurotoxicity as a complement to traditional studies on animals. In this study, neuronally differentiated mouse embryonal carcinoma P19 cells (P19 neurons) were compared with human neuroblastoma SH-SY5Y cells and rat adrenal pheochromocytoma PC12 cells for their ability to detect toxicity of methylmercury (MeHg), okadaic acid and acrylamide.

Methods

Retinoic acid-treated P19 and SH-SY5Y cells and nerve growth factor-stimulated PC12 cells, allowed to differentiate for 6 days, were exposed to MeHg, okadaic acid and acrylamide for 48 h. Cell survival and neurite outgrowth were assessed with the calcein-AM assay and fluorescence detection of antibodies against the cytoskeletal neuron-specific protein βIII-tubulin, respectively. The effects of glutathione (GSH) and the potent inhibitor of GSH synthesis buthionine sulfoximine (BSO) on the MeHg induced-toxicity were assessed using the PrestoBlue™ cell viability assay and the TMRE mitochondrial membrane potential assay.

Results

Differentiated P19 cells developed the most extensive neuronal network among the three cell models and were the most sensitive neuronal model to detect neurotoxic effects of the test compounds. MeHg produced a concentration-dependent toxicity in differentiated P19 cells and SH-SY5Y cells, with statistically significant effects at concentrations from 0.1 μM in the P19 neurons and 1 μM in the SH-SY5Y cells. MeHg induced a decrease in the cellular metabolic activity and mitochondrial membrane potential (ΔΨm) in the differentiated P19 cells and SH-SY5Y cells, that were attenuated by GSH. Okadaic acid and acrylamide also showed statistically significant toxicity in the P19 neurons, but not in the SH-SY5Y cells or the P12 cells.

Conclusions

P19 neurons are more sensitive to detect cytotoxicity of MeHg, okadaic acid and acrylamide than retinoic acid-differentiated SH-SY5Y cells and nerve growth factor-treated PC12 cells. P19 neurons are at least as sensitive as differentiated SH-SY5Y cells to detect the loss of mitochondrial membrane potential produced by MeHg and the protective effects of extracellular GSH on MeHg toxicity. P19 neurons may be a useful model to study neurotoxic effects of chemicals.

Cellular models as tools for the study of the role of alpha-synuclein in Parkinson's disease

Neurodegenerative diseases are highly debilitating conditions characterised primarily by progressive neuronal loss and impairment of the nervous system. Parkinson's disease (PD) is one of the most common of these disorders, affecting 1-2% of the population above the age of 65. Although the underlying mechanisms of PD have been extensively studied, we still lack a full understanding of the molecular underpinnings of the disease. Thus, the in vitro and in vivo models currently used are able to only partially recapitulate the typical phenotypes of the disease. Here, we review various cell culture models currently used to study the molecular basis of PD, with a focus on alpha-synuclein-associated molecular pathologies. We also discuss how different cell models may constitute powerful tools for high-throughput screening of molecules capable of modulating alpha-synuclein toxicity.

Using an NMR metabolomics approach to investigate the pathogenicity of amyloid-beta and alpha-synuclein

INTRODUCTION

The pathogenicity at differing points along the aggregation pathway of many fibril-forming proteins associated with neurodegenerative diseases is unclear. Understanding the effect of different aggregation states of these proteins on cellular processes is essential to enhance understanding of diseases and provide future options for diagnosis and therapeutic intervention.

OBJECTIVES

To establish a robust method to probe the metabolic changes of neuronal cells and use it to monitor cellular response to challenge with three amyloidogenic proteins associated with neurodegenerative diseases in different aggregation states.

METHOD

Neuroblastoma SH-SY5Y cells were employed to design a robust routine system to perform a statistically rigorous NMR metabolomics study into cellular effects of sub-toxic levels of alpha-synuclein, amyloid-beta 40 and amyloid-beta 42 in monomeric, oligomeric and fibrillar conformations.

RESULTS

This investigation developed a rigorous model to monitor intracellular metabolic profiles of neuronal cells through combination of existing methods. This model revealed eight key metabolites that are altered when neuroblastoma cells are challenged with proteins in different aggregation states. Metabolic pathways associated with lipid metabolism, neurotransmission and adaptation to oxidative stress and inflammation are the predominant contributors to the cellular variance and intracellular metabolite levels. The observed metabolite changes for monomer and oligomer challenge may represent cellular effort to counteract the pathogenicity of the challenge, whereas fibrillar challenge is indicative of system shutdown. This implies that although markers of stress are more prevalent under oligomeric challenge the fibrillar response suggests a more toxic environment.

CONCLUSION

This approach is applicable to any cell type that can be cultured in a laboratory (primary or cell line) as a method of investigating how protein challenge affects signalling pathways, providing additional understanding as to the role of protein aggregation in neurodegenerative disease initiation and progression.