Cellular Model Of Parkinson's Disease Research Articles

Tetramethylpyrazine Analogue T-006 Promotes the Clearance of Alpha-synuclein by Enhancing Proteasome Activity in Parkinson's Disease Models.

Parkinson's disease (PD) is the second most common neurodegenerative disorder worldwide and is characterized in part by the degeneration of dopaminergic neurons in the substantia nigra pars compacta (SNc). The main pathological hallmark of PD is the intraneuronal accumulation of misfolded α-synuclein (α-syn) aggregates. Mutations in the SNCA gene (encoding α-syn) and variations in its copy number are associated with some forms of familial PD. In the present study, T-006, a new tetramethylpyrazine (TMP) derivative with recently reported anti-Alzheimer activity, is shown to significantly promote α-syn degradation in a cellular PD model. Moreover, we illustrate that T-006 inhibits the accumulation of both Triton-soluble and -insoluble forms of α-syn and protects against α-syn-induced neurotoxicity in A53T-α-syn transgenic mice. The mechanism of action of T-006 was verified by evaluation of a potential protein degradation pathway. We found that T-006 promotes α-syn degradation in a proteasome-dependent and autophagy-independent manner. We further confirmed that T-006 enhances proteasome activity by upregulating 20S proteasome subunit β5i (LMP7) protein expression. A functional study revealed that T-006 activates the PKA/Akt/mTOR/p70S6K pathway to trigger LMP7 expression and enhance chymotrypsin-like proteasomal activity. These findings indicate that T-006 is a potent proteasome activator and a potential therapeutic agent for the prevention and treatment of PD and related diseases.

Cistanche extracts ameliorates the neurotoxicity induced by hydrogen peroxide in new mutant DJ-1-transfected neuroblastoma cellular models.

Introduction DJ‐1 mutation is a causative reason for familial Parkinson's disease (PD). Leucine166Proline (L166P) and C106S are two important DJ‐1 mutations. In this study, we established hydrogen peroxide (H2O2) induced L166P and C106S DJ‐1‐transfected neuroblastoma (SH‐SY5Y) cellular models of PD and investigated the effects of Cistanche extracts and key bioactive compounds, including acteoside, echinacoside, caffeic acid, and Cistanche total glycosides on these two models.MethodsAfter expressing FLAG‐tagged L166P and C106S DJ‐1 plasmids in Escherichia coli, the expressed plasmids were collected, treated with restriction enzyme, and identified using DNA electrophoresis. After purification, the L166P DJ‐1 and C106S DJ‐1 plasmids were separately transfected into SH‐SY5Y cells using liposomes. Transfected SH‐SY5Y cells were detected by western blotting and immunocytochemistry. Cell viability was determined using MTT assay.ResultsBoth western blotting and immunocytochemistry showed that L166P and C106S DJ‐1 were highly expressed in the transfected SH‐SY5Y cells. MTT assays showed that transfection with L166P or C106S DJ‐1 reduced the viability of SH‐SY5Y cells exposed to H2O2, as compared to untransfected SH‐SY5Y cells. In addition, Cistanche extracts and key bioactive compounds, including acteoside, echinacoside, caffeic acid, and Cistanche total glycosides, significantly inhibited the decreases of cell viability caused by H2O2 in L166P and C106S DJ‐1‐transfected SH‐SY5Y cells.ConclusionsThese findings suggest that we successfully established sensitive and stable H2O2 induced L166P DJ‐1‐ and C106S DJ‐1‐transfected SH‐SY5Y cell models of PD and Cistanche extracts may thus be useful for treating PD.

Curcumin-Activated Mesenchymal Stem Cells Derived from Human Umbilical Cord and Their Effects on MPTP-Mice Model of Parkinson's Disease: A New Biological Therapy for Parkinson's Disease

The aim of this study was to investigate the effects of human umbilical cord mesenchymal stem cell activated by curcumin (hUC-MSCs-CUR) on Parkinson's disease (PD). The hUC-MSCs-CUR was transplanted into the MPTP-induced PD mouse models via the tail vein. We found that hUC-MSCs-CUR significantly improved the motor ability, increased the tyrosine hydroxylase (TH), dopamine (DA), and Bcl-2 levels, and reduced nitric oxide synthase, Bax, and cleaved-caspase 3 expression in PD mice. The supernatant of hUC-MSCs-CUR (CM-CUR) was used to stimulate the SH-SY5Y cellular model of PD; cell proliferation, differentiation, TH, and neuronal-specific marker microtubular associated protein 2 (MAP2) expressions were examined. Results showed that CM-CUR significantly promoted cell proliferation and gradually increased TH and MAP2 expression in SH-SY5Y PD cells. The beneficial effects could be associated with significant increase of rough endoplasmic reticulum in the hUC-MSCs-CUR, which secrete many cytokines and growth factors beneficial for PD treatment. Therefore, transplantation of hUC-MSCs-CUR could show promise for improving the motor recovery of PD. Funding Statement: This study was supported by Shangdong province nature and science funding, ZR2019MH065. Declaration of Interests: The authors declare no competing financial interests. Ethics Approval Statement: All the animal experiments described in this study and umbilical cord tissue collection were approved by the Ethics Committee of the 148th Hospital and the second affiliated hospital of Zhengzhou University.

AMPK mediates the neurotoxicity of iron oxide nanoparticles retained in mitochondria or lysosomes.

Environmental factors may play a critical role in the etiology and pathogenesis of Parkinson's disease (PD). However, the association of PD with specific chemical species remains largely unknown. Here we prepared three kinds of iron oxide nanoparticles and examined their cytotoxicity in a cellular model of PD. We found that lysosome-targeted nanoparticles showed significant cytotoxicity in SH-SY5Y cells. Inhibition of AMPK could aggravate the neurotoxicity of lysosome-targeted nanoparticles as well as mitochondrion-targeted nanoparticles. Alteration of mitochondrial membrane potentials was found to be in agreement with the neurotoxicity of iron nanoparticles. These results suggested an important role of AMPK in regulating iron nanoparticle-associated neurotoxicity.

MiR-410 exerts neuroprotective effects in a cellular model of Parkinson's disease induced by 6-hydroxydopamine via inhibiting the PTEN/AKT/mTOR signaling pathway

Parkinson's disease (PD) is a chronic neurodegenerative disease characterized by loss of dopaminergic neurons in the substantia nigra. Recently, microRNAs (miRNAs) were emerging as important mediators in dopaminergic neuron biology. This study determined miR-410 expression in the 6-hydroxydopamine (6-OHDA)-induced in vitro cellular model of PD and explored the mechanistic role of miR-410 in the modulation of neuronal cell viability and apoptosis. Our data showed that 6-OHDA concentration-dependently suppressed neuronal cell viability and miR-410 expression in SH-SY5Y and PC12 cells. Overexpression of miR-410 partially restored the effects of 6-OHDA on neuronal cell viability, apoptosis, capsase-3 activity as well as reactive oxygen species (ROS) production. On the other hand, inhibition of miR-410 decreased neuronal cell viability and increased apoptotic rates, capase-3 activity as well as ROS production. Furthermore, the potential targets of miR-410 were predicted by TargetScan tool, and we verified that phosphatase and tensin homolog (PTEN) was a target of miR-410 as confirmed by the dual-luciferase reporter assay. MiR-410 overexpression attenuated PTEN expression and mediated the effects in the 6-OHDA-treated cells via targeting PTEN in SH-SY5Y and PC12 cells. Furthermore, 6-OHDA treatment suppressed the protein expression of phosphorylated AKT and phosphorylated mTOR, which was partially attenuated by miR-410 overexpression in SH-SY5Y and PC12 cells. MiR-410 overexpression increased phosphorylated AKT and phosphorylated mTOR protein expression, and this effect was attenuated by PTEN overexpression in both SH-SY5Y and PC12 cells. Collectively, this is the first study to demonstrate the neuroprotective effects of miR-410 in a 6-OHDA-induced cellular model of PD, and our data implied that miR-410 exerted its neuroprotective effects via regulating PTEN/AKT/mTOR signaling axis. The present study may suggest new paradigm to study the pathology of PD.

Inhibition of SIRT2 by Targeting GSK3β-Mediated Phosphorylation Alleviates SIRT2 Toxicity in SH-SY5Y Cells.

Sirtuin 2 (SIRT2) is thought to be important in the pathogenesis of Parkinson’s disease (PD), and the inhibition of SIRT2 rescues α-synuclein toxicity in a cellular model of PD. Recent studies have focused on identifying inhibitors of SIRT2, but little is known about the processes that directly regulate its function. GSK3β is a serine/threonine protein kinase that affects a wide range of biological functions, and it is localized in Lewy bodies (LBs). Therefore, we investigated whether SIRT2 is regulated by GSK3β and enhances cell death in PD. In the present study, Western blot showed that total SIRT2 levels did not change noticeably in a cellular model of PD but that SIRT2 phosphorylation was increased, and GSK3β activity was elevated. In addition, mass spectrometry (MS) studies indicated that SIRT2 was phosphorylated by GSK3β at three specific sites. Phospho- or dephospho-mimicking studies demonstrated that this postmodification (phosphorylation) increased SIRT2 toxicity in SH-SY5Y cells. Collectively, our findings identify a posttranslational mechanism that controls SIRT2 function in PD and provide evidence for a novel regulatory pathway involving GSK3β, SIRT2, and α-synuclein.

Mitochondrion-Targeting Fluorescence Probe via Reduction Induced Charge Transfer for Fast Methionine Sulfoxide Reductases Imaging.

Methionine sulfoxide reductases (Msrs) play essential roles in maintaining mitochondrial function and are recognized as potential therapeutic targets. However, current probes for Msrs fail to target mitochondria and exhibit a relatively slow response and limited sensitivity. Here we develop a novel turn-on fluorescence probe that facilitates imaging of mitochondrial Msrs in living cells. The probe is constructed by conjugating a methyl phenyl sulfoxide, a mimic Msrs substrate, to an electron-withdrawing hydrophobic cation, methylpyridinium. The probe of acceptor-acceptor structure is initially nonemissive. Msrs catalyzed reduction of sulfoxide to sulfide generated a fluorophore of distinct donor-acceptor structure. The probe is demonstrated to exhibit high sensitivity, fast response, and high selectivity toward MsrA in vitro. Furthermore, the probe is successfully introduced to detect and image Msrs in living cells with excellent mitochondrial-targeting capability. Moreover, the probe also reveals decreased Msrs activity in a cellular Parkinson's disease model. Our probe affords a powerful tool for detecting and visualizing mitochondrial Msrs in living cells.

The neuroprotective effect of BSA-based nanocurcumin against 6-OHDA-induced cell death in SH-SY5Y cells.

Parkinson's disease (PD) is regarded as the second most common neurodegenerative disease affecting elderly population. There is a tendency toward finding natural cures to suppress the initiation and progression of this disease. Some epidemiological studies indicated lower incidence of PD in populations that consume curry. Curcumin, as the main ingredient of turmeric, has been supposed to have a protective role against PD progression. However, low bioavailability of curcumin is still a challenge in evaluation of the therapeutic potential of this substance. In this study, we aimed to produce a BSA-based nanocurcumin to assess its effect on 6-hydroxydopamine (6-OHDA)-induced death and Akt signaling disruption in SH-SY5Y cells. BSA-based nanocurcumin was produced using desolvation method. Human neuroblastoma cells were treated with OHDA with/without different doses of nanocurcumin and MTT test was used to assess their viability besides observing cells morphological changes. The protective doses of nanocurcumine were chosen according to MTT results and western blot studies were done to assess p-Akt/t-Akt ratio. 6-OHDA exposure led to decreased cell viability, while nanocurcumin at doses of 400 and 500 nM prevented cell death. Moreover, this nanoformulation of curcumin restored p-Akt/t-Akt decrement induced by 6-OHDA. The protective effect of BSA-based nanocurcumin was estimated to be at least 4 time higher than that of natural curcumin according to the MTT results. It seems that BSA-based nanocurcumin can be regarded as a potent substitute for natural curcumin in protecting SH-SY5Y cell as a cellular model of PD.

Fisetin protects against rotenone-induced neurotoxicity through signaling pathway.

The present study was designed to evaluate the protective effect of fisetin against rotenone induced toxicity in SH-SY5Y neuroblastoma cellular modelof Parkinson's disease (PD). SH-SY5Y neuroblastoma cells were treated with fisetin (5µM) 2 hr prior to being treated with rotenone (100 nM). Following the exposure ofSH-SY5Ycells torotenone, there was marked decreased cell viability, increased oxidative stress, activation of caspase-3 and apoptosis (dual staining, expressions of pro-apoptotic and anti-apoptotic indices). However pretreatment with fisetin significantly and dose-dependently alleviated rotenone induced cytotoxicity and oxidative stress inSH-SY5Ycells. Moreover, fisetin attenuatedrotenoneinduced toxicity by down-regulatingBax, caspases-3 protein expression and up-regulating protein expression of Bcl-2, p38/JNK-MAPK and PI3K, Akt, GSK-3β pathways. Collectively, these results suggest that fisetin could prevent therotenone-induced neurotoxicity via various signaling pathways.

Orexin-A Exerts Neuroprotective Effects via OX1R in Parkinson's Disease.

Parkinson’s disease (PD) is a common neurodegenerative disorder characterized by progressive and selective death of dopaminergic neurons. Orexin-A is involved in many biological effects of the body. It has been reported that orexin-A has protective effects in cellular models of PD. However, little is known about the protective effects of orexin-A in animal parkinsonian models and the cellular mechanism has not yet been fully clarified. The aim of this study was to evaluate the effects of orexin-A in MPTP mice model of PD as well as the possible neuroprotective mechanisms of orexin-A on dopaminergic neurons. The results from animal experiments demonstrated that orexin-A attenuated the loss of dopaminergic neurons and the decrease of tyrosine hydroxylase (TH) expression in the substantia nigra, normalized the striatal dopaminergic fibers, and prevented the depletion of dopamine and its metabolites in the striatum. MPTP-treated mice showed cognitive impairments accompanied with significant motor deficiency. Orexin-A improved MPTP-induced impairments in both motor activity and spatial memory. Importantly, orexin-A increased the protein level of brain-derived neurotrophic factor (BDNF) in dopaminergic neurons of the substantia nigra. Furthermore, the protective effects of orexin-A on MPTP parkinsonian mice could be blocked by orexinergic receptor 1 (OX1R) antagonist, SB334867. In another set of experiments with SH-SY5Y dopaminergic cells, orexin-A significantly induced the expression of BDNF in a dose and time-dependent manner. The upregulation of BDNF is mainly concerned with PI3K and PKC signaling pathways via OX1R. The present study demonstrated that orexin-A exerted neuroprotective effects on MPTP parkinsonian mice, which may imply orexin-A as a potential therapeutic target for PD.

Ubiquitin ligase HMG-CoA reductase degradation 1 (HRD1) prevents cell death in a cellular model of Parkinson's disease

Endoplasmic reticulum (ER) stress may play a role in the etiology of Parkinson's disease (PD). We have previously reported that ubiquitin ligase 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase degradation 1 (HRD1) involved in ER stress degrades unfolded protein that accumulates in the ER due to loss of function of Parkin, which is a causative factor in familial PD. We have also demonstrated that cell death is suppressed by the degradation of unfolded proteins. These findings indicate that HRD1 may serve as a compensatory mechanism for the loss of function of Parkin in familial PD patients. However, the role of HRD1 in sporadic PD has not yet been identified. This study aimed to reveal the roles of HRD1 and associated molecules in a cellular model of PD. We demonstrated that expressions of HRD1 and Suppressor/Enhancer Lin12 1-like (SEL1L: a HRD1 stabilizer) increased in SH-SY5Y human neuroblastoma cells upon exposure to 6-hydroxydopamine (6-OHDA). The 6-OHDA-induced cell death was suppressed in cells overexpressing wt-HRD1, whereas cell death was enhanced in cells with knockdown of HRD1 expression. These results suggest that HRD1 is a key molecule involved in 6-OHDA-induced cell death. By contrast, suppression of SEL1L expression decreased the amount of HRD1 protein. As a result, 6-OHDA-induced cell death was enhanced in cells suppressing SEL1L expression, and this cell death was much more evident than that in cells with suppression of HRD1 expression. These findings strongly indicate that SEL1L is necessary for maintaining and stabilizing the amount of HRD1 protein, and stabilizing the amount of HRD1 protein through SEL1L may serve to protect against 6-OHDA-induced cell death. Furthermore, the expression of Parkin was reinforced when HRD1 mRNA had been suppressed in cells, but was not observed when SEL1L mRNA had been restrained. It is possible that Parkin expression is induced as a compensatory mechanism when HRD1 mRNA decreases. This intracellular transduction may suppress the enhancement of 6-OHDA-induced cell death caused by the loss of HRD1. Taken together with these results, it is suggested that HRD1 and its stabilizer (SEL1L) are key molecules for elucidating the pathogenesis and treatment of PD.

Angiotensin II induces oxidative stress and upregulates neuroprotective signaling from the NRF2 and KLF9 pathway in dopaminergic cells

Nuclear factor-E2-related factor 2 (NRF2) is a transcription factor that activates the antioxidant cellular defense in response to oxidative stress, leading to neuroprotective effects in Parkinson's disease (PD) models. We have previously shown that Angiotensin II (AngII) induces an increase in reactive oxygen species (ROS) via AngII receptor type 1 and NADPH oxidase (NOX), which may activate the NRF2 pathway. However, controversial data suggest that AngII induces a decrease in NRF2 signaling leading to an increase in oxidative stress. We analyzed the effect of AngII and the dopaminergic neurotoxin 6-hydroxydopamine (6-OHDA) in culture and in vivo, and examined the effects on the expression of NRF2-related genes. Treatment of neuronal cell lines Mes23.5, N27 and SH-SY5Y with AngII, 6-OHDA or a combination of both increased ROS production and reduced cell viability. Simultaneously, these treatments induced an increase in expression in the NRF2-regulated genes heme oxygenase 1 (Hmox1), NAD(P)H quinone dehydrogenase 1 (Nqo1) and Kruppel like factor 9 (Klf9). Moreover, overexpression of KLF9 transcription factor caused a reduction in the production of ROS induced by treatment with AngII or 6-OHDA and improved the survival of these neuronal cells. Rats treated with AngII, 6-OHDA or a combination of both also showed an increased expression of NRF2 related genes and KLF9. In conclusion, our data indicate that AngII induces a damaging effect in neuronal cells, but also acts as a signaling molecule to activate NRF2 and KLF9 neuroprotective pathways in cellular and animal models of PD.

MFN2 ameliorates cell apoptosis in a cellular model of Parkinson's disease induced by rotenone.

A number of studies indicated that apoptosis, a specific type of programmed cell death, contributed to the loss of dopaminergic neurons during progression of Parkinson's disease (PD). Previously, the authors of the present study demonstrated that apoptosis of dopaminergic neurons was mainly achieved via the mitochondria-mediated apoptosis pathway, however, the precise molecular mechanisms remain to be elucidated. The present study aimed to determine whether mitofusin-2 (MFN2), a mitochondrial protein, participated in the apoptosis of dopaminergic neurons in a cellular model of PD induced by rotenone. The present study demonstrated that the expression of MFN2 was relatively stable following treatment with rotenone. Lentiviral knockdown and overexpression experiments for the first time, to the best of the authors knowledge, revealed that MFN2 prevented rotenone-induced cell death by amelioration of apoptosis. These results revealed a protective role of MFN2 against apoptosis in an in vitro model of PD and may be used to establish MFN2 as a potential therapeutic target for the treatment of this disease.

Bioactive constituents from cinnamon, hemp seed and polygonum cuspidatum protect against H2O2 but not rotenone toxicity in a cellular model of Parkinson's disease

Mitochondrial dysfunction and oxidative stress are two factors that are thought to contribute to the pathogenesis of Parkinson's disease (PD), a debilitating progressive neurodegenerative disorder that results in the loss of catecholamine producing cells throughout specific regions of the brain. In this study we aimed to compare the effects of hydrogen peroxide (H2O2) and rotenone (a pesticide and mitochondrial complex 1 inhibitor) on cell viability and the expression of tyrosine hydroxylase (TH) in a cellular model of PD. We also sought to investigate the potential neuroprotective benefits of bioactive constituents from cinnamon, hemp seed and polygonum cuspidatum. To create a model, SH-SY5Y cells transfected with human TH isoform 1 were treated with varying concentrations of H2O2 and rotenone, in the presence or absence of bioactive constituents. The effect of these toxins and constituents on cell viability, apoptosis and protein expression was assessed using MTT viability assays and western blotting. Rotenone treatment caused a significant decrease in cell viability but a significant increase in TH in the remaining cells. H2O2 treatment caused a significant decrease in cell viability but had no significant effect on TH expression. Curcumin, cinnamaldehyde, caffeoyltyramide (hemp seed extract) and piceatannol glucoside (polygonum cuspidatum extract) were unable to attenuate rotenone induced cell death, however they were able to provide protection against H2O2 induced cell death. This is the first study to demonstrate the neuroprotective properties of cinnamaldehyde, caffeoyltyramide and piceatannol glucoside in a dopaminergic cell line in response to H2O2.

Mitochondrial alterations in Parkinson's disease human samples and cellular models

Mitochondrial impairment is one of the most important hallmarks of Parkinson's disease (PD) pathogenesis. In this work, we wanted to verify the molecular basis of altered mitochondrial dynamics and disposal in Substantia nigra specimens of sporadic PD patients, by the comparison with two cellular models of PD. Indeed, SH-SY5Y cells were treated with either dopamine or 1-methyl-4-phenylpyridinium (MPP+) in order to highlight the effect of altered dopamine homeostasis and of complex I inhibition, respectively. As a result, we found that fusion impairment of the inner mitochondrial membrane is a common feature of both PD human samples and cellular models. However, the effects of dopamine and MPP+ treatments resulted to be different in terms of the mitochondrial damage induced. Opposite changes in the levels of two mitochondrial protein markers (voltage-dependent anion channels (VDACs) and cytochrome c oxidase subunit 5β (COX5β)) were observed. In this case, dopamine treatment better recapitulated the molecular picture of patients' samples. Moreover, the accumulation of PTEN-induced putative kinase 1 (PINK1), a mitophagy marker, was not observed in both PD patients samples and cellular models. Eventually, in transmission electron microscopy images, small electron dense deposits were observed in mitochondria of PD subjects, which are uniquely reproduced in dopamine-treated cells. In conclusion, our study suggests that the mitochondrial molecular landscape of Substantia nigra specimens of PD patients can be mirrored by the impaired dopamine homeostasis cellular model, thus supporting the hypothesis that alterations in this process could be a crucial pathogenetic event in PD.

The Neuroprotection of Low-Dose Morphine in Cellular and Animal Models of Parkinson's Disease Through Ameliorating Endoplasmic Reticulum (ER) Stress and Activating Autophagy.

Parkinson’s disease (PD) is a common neurodegenerative disease characterized the progressive loss of dopaminergic (DA) neurons in the substantia nigra pars compacta (SNc). Brain endogenous morphine biosynthesis was reported to be impaired in PD patients and exogenous morphine attenuated 6-hydroxydopamine (6-OHDA)-induced cell death in vitro. However, the mechanisms underlying neuroprotection of morphine in PD are still unclear. In the present study, we investigated the neuroprotective effects of low-dose morphine in cellular and animal models of PD and the possible underlying mechanisms. Herein, we found 6-OHDA and rotenone decreased the mRNA expression of key enzymes involved in endogenous morphine biosynthesis in SH-SY5Y cells. Incubation of morphine prevented 6-OHDA-induced apoptosis, restored mitochondrial membrane potential, and inhibited the accumulation of intracellular reactive oxygen species (ROS) in SH-SY5Y cells. Furthermore, morphine attenuated the 6-OHDA-induced endoplasmic reticulum (ER) stress possible by activating autophagy in SH-SY5Y cells. Finally, oral application of low-dose morphine significantly improved midbrain tyrosine hydroxylase (TH) expression, decreased apomorphine-evoked rotation and attenuated pain hypersensitivity in a 6-OHDA-induced PD rat model, without the risks associated with morphine addiction. Feeding of low-dose morphine prolonged the lifespan and improved the motor function in several transgenic Drosophila PD models in gender, genotype, and dose-dependent manners. Overall, our results suggest that neuroprotection of low-dose morphine may be mediated by attenuating ER stress and oxidative stress, activating autophagy, and ameliorating mitochondrial function.

Transmission Mechanism of Lewy Body-Like α-Synucleinopathies in Dopaminergic Neurons Derived from Human Induced Pluripotent Stem Cells

Grafting of cells in Parkinson's disease (PD) results in a prion-like infection, exhibiting a Lewy body-like pathology, caused by the recipient cells. The transmission mechanism of Lewy bodies is not completely understood. Therefore, a research idea with a novel experimental strategy is proposed to investigate the transmission mechanism of α-synuclein pathology using PD patient-derived human induced pluripotent stem cells (hiPSC) in an in vitro human cellular and molecular PD model and in vivo mouse PD model for dopaminergic neuron transplantation.

Pramipexole and Fingolimod exert neuroprotection in a mouse model of Parkinson's disease by activation of sphingosine kinase 1 and Akt kinase

Parkinson's disease (PD) is one of the most severe neurodegenerative diseases with unknown pathogenesis and currently unsuccessful therapies. Recently, neuroprotection via sphingosine-1-phosphate (S1P)-dependent signalling has become a promising target for the treatment of neurodegenerative disorders. Our previous study demonstrated down-regulation and inhibition of the S1P-synthesizing enzyme sphingosine kinase 1 (SPHK1) in a PD cellular model. Moreover, we have previously identified a neuroprotective effect of fingolimod (FTY720), a first S1P receptor modulator utilized in the clinic. This study focused on the effects of FTY720 and the dopamine D2/D3 receptor agonist pramipexole (PPX) in a PD mouse model, induced by administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Administration of FTY720, similar to PPX, abolished an observed loss of tyrosine hydroxylase (TH) immunoreactivity in MPTP-lesioned brain regions. Moreover, significant changes in SPHK1 expression/activity in MPTP-lesioned mouse midbrain were identified. PPX, but not FTY720 treatment, significantly protected against these alterations. Both drugs activate another pro-survival enzyme, Akt kinase, which is a crucial protein downstream of S1PR(s). FTY720 increased BAD protein phosphorylation and in this way may protect mitochondria against the BAD-induced apoptotic signalling pathway. Both FTY720 and PPX enhanced the locomotor activity of PD mice in the rotarod tests. Our data suggest a neuroprotective role for FTY720 related to the S1PR/Akt kinase signalling pathways as a beneficial treatment target in planning new PD therapeutic options. Moreover, our findings have shed new light on a neuroprotective mechanism of PPX action associated with SPHK1 activation, which provides an opportunity for evaluating multi-target (SPHK1/S1P/S1PR) effects in the context of PD.

The delta opioid peptide D-Alanine 2, Leucine 5 Enkephaline (DADLE)-induces neuroprotection through cross-talk between the UPR and pro-survival MAPK-NGF-Bcl2 signaling pathways via modulation of several micro-RNAs in SH-SY5Y cells subjected to ER stress.

Parkinson's disease (PD) is the second most progressive neurodegenerative disease characterized by the loss of dopaminergic neurons and accumulation of misfolded proteins in endoplasmic reticulum (ER) leading to activation of the unfolded protein response (UPR). In the present study, we aimed to determine the potential survival effect of the delta opioid neuro-peptide D-Alanine 2, Leucine 5 Enkephaline (DADLE), and its mechanism in dopaminergic SH-SY5Y cells which were subjected to ER stress. In this cellular model of PD, enhanced cell survivability was observed on DADLE treatment (but not with μ and κ opioid agonists) along with concomitant down regulation of the UPR stress sensors and protein aggregates. The study found increased phosphorylation of MEK-1, which leads to activation of MAP kinase as well as enhanced expression of the pro-survival gene nerve growth factor and anti-apoptotic marker Bcl2. DADLE treatment could also significantly inhibit expression of the pro-apoptotic marker BIM. Next-generation sequence analysis revealed 93 micro (mi) RNAs to be differentially regulated following DADLE treatment in cells subjected to ER stress. Pathway prediction and previously published reports revealed that out of these 93 miRNAs, 34 can play a role in promoting cell survival. Specific modulation of two such miRNAs, namely miR-30c-2-3p and miR-200c, could partially reverse the positive survival effect induced by DADLE. Apart from the known miRNAs, various novel miRNAs were also observed following DADLE treatment which could also play a role in enhancing the survival of SH-SY5Y cells under ER stress.

Novel biomolecular information in rotenone-induced cellular model of Parkinson's disease

In order to uncover the remarkable pathogenic genes or molecular pathological process in Parkinson's disease (PD), we employed a microarray analysis upon the cellular PD model induced by rotenone. Compared to the control group, 2174 genes were screened out to be expressed differently in the rotenone-induced group by certain criterion. GO analysis and the pathways analysis showed the significant enrichment of genes that were associated with the biological process of cell cycle, apoptotic process, organelle fusion, mitochondrial lesion, endoplasmic reticulum stress and so on. Among these significant DE genes, some were sorted out to be involved in cell cycle and protein processing in endoplasmic reticulum. As the PPI network analysis showed, the interaction relationship of the DEGs involved in the process of protein generation in endoplasmic reticulum(ER) was clearly showed up. As a prediction, we emphasized the genes EDEM1, ATF4, TRAF2 might play central roles in the protein misfolding process during the progression of Parkinson's disease and these new-found genes might be the future research focus and therapeutic targets in PD.