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1.
Apoptosis is a contributing cause of dopaminergic neuron loss in Parkinson disease. Recent work has shown that erythropoietin
(EPO) offers protection against apoptosis in a wide variety of tissues. We demonstrate that exposure of PC12 cells to 1-methyl-4-phenylpyridinium
ion (MPP +) with recombinant human EPO, significantly decreased apoptosis as measured by TUNEL and caspase-3 activity when compared
to MPP + treatment alone. EPO induced sustained phosphorylation of Akt and its substrate, GSK-3β, reduced caspase-3 activities in
PC12 cells. The anti-apoptotic effect of EPO was abrogated by co-treatment with LY294002, the specific blocker of phosphatidylinositol
3-kinase (PI3K). The effects of EPO on GSK-3β and caspase-3 activities were also blocked by LY294002. LiCl, the inhibitor
of GSK-3β, downregulated the caspase-3 activity and blocked the apoptosis induced by MPP +. Finally, we determined that EPO transiently activated the ERK signaling pathway, but PD98059, a specific inhibitor of ERK,
does not alter the survival effect of EPO in this model system. Thus, these findings indicate that EPO protects against apoptosis
in PC12 cells exposed to MPP +, through the Akt/GSK-3β/caspase-3 signaling pathway, but the ERK pathway is not involved in the EPO-dependent survival enhancing
effect in this model system.
The authors Yan Wu and You Shang are equally contributed to this work. 相似文献
2.
Cochlear outer hair cells (OHCs) terminally differentiate prior to the onset of hearing. During this time period, thyroid
hormone (TH) dramatically influences inner ear development. It has been shown recently that TH enhances the expression of
the motor protein prestin via liganded TH receptor β (TRβ) while in contrast the expression of the potassium channel KCNQ4
is repressed by unliganded TRα1. These different mechanisms of TH regulation by TRα1 or TRβ prompted us to analyse other ion
channels that are required for the final differentiation of OHCs. We analysed the onset of expression of the Ca 2+ channel Ca V1.3, and the K + channels SK2 and BK and correlated the results with the regulation via TRα1 or TRβ. The data support the hypothesis that
proteins expressed in rodents prior to or briefly after birth like Ca V1.3 and prestin are either independent of TH (e.g. Ca V1.3) or enhanced through TRβ (e.g. prestin). In contrast, proteins expressed in rodents later than P6 like KCNQ4 (∼P6), SK2
(∼P9) and BK (∼P11) are repressed through TRα1. We hypothesise that the precise regulation of expression of the latter genes
requires a critical local TH level to overcome the TRα1 repression.
Harald Winter and Claudia Braig contributed equally to this work. 相似文献
3.
Parkinson's disease (PD) is a typical neurodegenerative disease. α-Lipoic acid (α-LA) can reduce the incidence of neuropathy. The present study explored the role and mechanism of α-LA in 1-methyl-4-phenylpyridinium (MPP +)-induced cell model of PD. The PD model was induced via treating PC12 cells with MPP + at different concentrations. MPP + and α-LA effects on PC12 cells were assessed from cell viability and ferroptosis. Cell viability was detected using the cell counting kit-8 assay. Malondialdehyde (MDA), 4-hydroxynonenal (4-HNE), iron, reactive xygen species (ROS), and glutathione (GSH) concentrations, and ferroptosis-related protein SLC7A11 and GPx4 expressions were used for ferroptosis evaluation. p-PI3K, p-Akt, and nuclear factor erythroid 2-related factor 2 (Nrf2) protein levels were detected. The PI3K/Akt/Nrf2 pathway inhibitors were applied to verify the role of the PI3K/Akt/Nrf2 pathway in α-LA protection against MPP +-induced decreased cell viability and ferroptosis. MPP +-reduced cell viability and induced ferroptosis as presented by increased MDA, 4-HNE, iron, and ROS concentrations, and reduced levels of GSH and ferroptosis marker proteins (SLC7A11 and GPx4). α-LA attenuated MPP +-induced cell viability decline and ferroptosis. The PI3K/Akt/Nrf2 pathway was activated after α-LA treatment. Inhibiting the PI3K/Akt/Nrf2 pathway weakened the protection of α-LA against MPP + treatment. We highlighted that α-LA alleviated MPP +-induced cell viability decrease and ferroptosis in PC12 cells via activating the PI3K/Akt/Nrf2 pathway. 相似文献
4.
The selective loss of dopaminergic neurons in the substantia nigra pars compacta is a feature of Parkinson’s disease (PD). 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced neurotoxicity is the most common experimental model used to investigate the pathogenesis of PD. Administration of MPTP in mice produces neuropathological defects as observed in PD and 1-methyl-4-pyridinium (MPP +) induces cell death when neuronal cell cultures are used. AMP-activated protein kinase (AMPK) is a key regulator of energy homeostasis. In the present study, we demonstrated that AMPK is activated by MPTP in mice and MPP + in SH-SY5Y cells. The inhibition of AMPK by compound C resulted in an increase in MPP +-induced cell death. We further showed that overexpression of AMPK increased cell viability after exposure to MPP + in SH-SY5Y cells. Based on these results, we suggest that activation of AMPK might prevent neuronal cell death and play a role as a survival factor in PD. 相似文献
5.
Disturbances in Ca 2+ homeostasis have been implicated in a variety of neuropathological conditions including Parkinson's disease (PD). However, the importance of store-operated Ca 2+ entry (SOCE) channels in PD remains to be investigated. In the present study, we have scrutinized the significance of TRPC1 in 1-methyl-4-phenyl-1,2,3,6-tetrahyrdro-pyridine (MPTP)-induced PD using C57BL/6 animal model and PC12 cell culture model. Both sub-acute and sub-chronic treatments of MPTP significantly reduced TRPC1, and tyrosine hydroxylase levels, but not TRPC3, along with increased neuronal death. Furthermore, MPTP induces mitochondrial dysfunction, which was associated with reduced mitochondrial membrane potential, decreased level of Bcl 2, Bcl-xl, and an altered Bcl-xl/Bax ratio thereby initiating apoptosis. Importantly, TRPC1 overexpression in PC12 cells showed significant protection against MPP + induced neuronal apoptosis, which was attributed to the restoration of cytosolic Ca 2+ and preventing loss of mitochondrial membrane potential. Silencing of TRPC1 or addition of TRPC1 channel blockers decreased mitochondrial membrane potential, whereas activation of TRPC1 restored mitochondrial membrane potential in cells overexpressing TRPC1. TRPC1 overexpression also inhibited Bax translocation to the mitochondria and thereby prevented cytochrome c release and mitochondrial-mediated apoptosis. Overall, these results provide compelling evidence for the role of TRPC1 in either onset/progression of PD and restoration of TRPC1 levels could limit neuronal degeneration in MPTP mediated PD. 相似文献
6.
DNA polymerase-β (DNA pol-β) plays a crucial role in the pathogenesis of Parkinson’s disease (PD). The aim of this study was to investigate the neuroprotective effects of a DNA polymerase-β inhibitor 2′,3′-dideoxycytidine (DDC) in PD models. In the in vitro studies, primary cultured neurons were challenged with 1-methyl-4-phenylpyridinium ion (MPP+). The expression of DNA pol-β was assessed using western blot. The neuroprotective effect of DNA pol-β knockdown and DNA pol-β inhibitor DDC was determined using cell viability assay and caspase-3 activity assay. We found that MPP+ induced neuronal death and the activation of caspase-3 in a dose-dependent manner. The expression of DNA pol-β increased after the neurons were exposed to MPP+. DNA pol-β siRNA or DNA pol-β inhibitor DDC attenuated neuronal death induced by MPP+. In the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced mouse model of PD, MPTP treatment triggered behavioral deficits and nigrostriatal lesions. Pretreatment with DDC attenuated MPTP-induced behavioral deficits, dopaminergic neuronal death and striatal dopamine depletion in the MPTP mouse model. These results indicate that DNA pol-β inhibitors may present a novel promising therapeutic option for the neuroprotective treatment of PD. 相似文献
7.
Parkinson’s disease (PD) is primarily caused by severe degeneration and loss of dopamine neurons in the substantia nigra pars
compacta. Thus, preventing the death of dopaminergic neurons is thought to be a potential strategy to interfere with the development
of PD. In the present work, we studied the effect of insulin-like growth factor-1 (IGF-1) on 1-methyl-4-phenylpyridinium (MPP +)-induced apoptosis in human neuroblastoma SH-EP1 cells. We found that the PI3K/AKT pathway plays a central role in IGF-mediated
cell survival against MPP + neurotoxicity. Furthermore, we demonstrated that the protective effect of AKT is largely dependent on the inactivation of
GSK-3β, since inhibition of GSK-3β by its inhibitor, BIO, could mimic the protective effect of IGF-1 on MPP +-induced cell death in SH-EP1 cells. Interestingly, the IGF-1 potentiated PI3K/AKT activity is found to negatively regulate
the JNK related apoptotic pathway and this negative regulation is further shown to be mediated by AKT-dependent GSK-3β inactivation.
Thus, our results demonstrated that IGF-1 protects SH-EP1 cells from MPP +-induced apoptotic cell death via PI3K/AKT/GSK-3β pathway, which in turn inhibits MPP +-induced JNK activation. 相似文献
8.
We are currently developing amino-substituted MPTP analogues as useful probes for understanding the mechanism of MPTP toxicity and Parkinson's disease. One analogue, 4′-amino MPTP, induces a loss of striatal dopamine and is thus a suitable substitute for MPTP. This probe will be used as a histologically fixable MPTP which can be used to answer detailed anatomical questions concerning the sites of MPTP, MPP + uptake and storage. In addition, antibodies have been raised against MPTP and MPP + in rabbits using diazo-linked bovine serum albumin conjugates. The antibodies have been characterized with regard to their recognition of relevant structural analogues using an enzymelinked immunoassay (ELISA) procedure. Antibodies to MPTP detected MPTP in mouse brain extracts derived from as little as 5 μg of tissue. The antibodies will be used for immunohistochemical localization of 4′-NH 2-MPTP and 4′-NH 2-MPP + in brain, as well as probes for the screening of parkinsonian brain tissue for any MPTP- or MPP +-like materials which might exist. 相似文献
9.
Changes in homospecific activity (unit of enzyme activity per unit of enzyme protein; Rush, Kindler and Udenfriend, 1974. Biochem. Biophys. Res. Commun., 61, 38) of tyrosine hydroxylase (TH) in the striatum of the brain were examined in MPTP-treated mice and parkinsonian patients. After a single injection of MPTP to mice, TH activity was acutely inhibited only in situ without changes in in vitro TH activity (Vmax) and TH protein; TH homospecific activity (TH Vmax/TH protein) did not change. After repeated injection of MPTP to mice for 8 days, in situ TH activity, in vitro TH Vmax, and TH protein were decreased in parallel, and TH homospecific activity did not change The result indicates that the decreases in in situ TH activity and in TH Vmax are due to the decrease in TH protein by nerve degeneration of dopaminergic neurons in MPTP treated mice. However, when MPP + was infused in the striatum of rats for 3 hours, in vitro TH activity (Vmax) was decreased without changes in TH protein. Thus, TH homospecific activity was decreased. The results indicate that MPP + inactivates TH protein in the striatum after continued infusion. In contrast, the homospecific activity of TH in post-mortem parkinsonian striatum was increased 3-fold. The increase in homospecific activity of residual TH in parkinsonian brain suggests such molecular changes in TH molecules as result in a compensatory increase in TH activity.Special issue dedicated to Dr. Sidney Udenfriend. 相似文献
10.
The cDNA clones encoding rabbit lung phosphatidylinositol transfer protein (PI-TP) were isolated and sequenced. The putative polypeptide consisted of 270 amino acid (aa) residues, the same as human PI-TP, but one aa residue less than the PI-TP of rat and mouse. PI-TP RNA expression in various tissues of a pregnant rabbit was analyzed by Northern blot. Brain, placenta and fallopian tube had the highest PI-TP RNA expression. PI-TP RNA expression in alveolar epithelial type-II cells isolated from rabbit lung markedly increased after a 24-h culture, suggesting that PITP RNA expression in type-II cells can be modified by ambient factors. 相似文献
11.
Amyloid fibril formation is associated with diseases such as Alzheimer’s, Parkinson’s, and prion diseases. Inhibition of amyloid
fibril formation by molecular chaperone proteins, such as the small heat-shock protein αB-crystallin, may play a protective
role in preventing the toxicity associated with this form of protein misfolding. Reduced and carboxymethylated κ-casein (RCMκ-CN),
a protein derived from milk, readily and reproducibly forms fibrils at physiological temperature and pH. We investigated the
toxicity of fibril formation by RCMκ-CN using neuronal model PC12 cells and determined whether the inhibition of fibril formation
altered its cell toxicity. To resolve ambiguities in the literature, we also investigated whether fibril formation by amyloid-β1–40
(Aβ 1–40), the peptide associated with Alzheimer’s disease, was inhibited by αB-crystallin and if this affected the toxicity of Aβ.
To this end, either RCMκ-CN or Aβ 1–40 was incubated at neutral pH to induce fibril formation before treating PC12 cells and assessing cell viability. Incubated
(fibrillar) RCMκ-CN was more toxic to PC12 cells than native RCMκ-CN with the highest level of toxicity being associated with
mature fibrils and protofibrils. Furthermore, the toxicity of RCMκ-CN was attenuated when its fibril formation was inhibited,
either through the chaperone action of αB-crystallin or when it interacted with its natural binding partners in milk, α S- and β-casein. Likewise, incubating Aβ 1–40 with αB-crystallin inhibited both Aβ 1–40 fibril formation and the associated cell toxicity. Importantly, by inhibiting fibril formation, αB-crystallin prevents the
cell toxicity associated with protein misfolding. 相似文献
12.
Asymmetric dimethylarginine (ADMA), an endogenous nitric oxide synthase (NOS) inhibitor, is profoundly protective against
1-methy-4-phenylpyridinium ion (MPP +)-induced neurotoxicity. Reactive oxygen species (ROS) overproduction contributes to the neurotoxicity of MPP +; while hydrogen sulfide (H 2S) is a pivotal endogenous antioxidant. This study is to assess the potential role of endogenous H 2S in the neuroprotection of ADMA against MPP +-induced toxicity in PC12 cells. We showed that ADMA prevented MPP +-induced inhibition of endogenous H 2S generation through inhibiting the down-regulation of cystathionine-β-synthetase (CBS, the major enzyme responsible for endogenous
H 2S generation in PC12 cells) expression and activity elicited by MPP +. ADMA obviously attenuated MPP +-triggered accumulation of intracellular ROS, dissipation of mitochondrial membrane potential (MMP), release of cytochrome
c (Cyt-c), and downregulation of Bcl-2 protein expression in PC12 cells. Inhibition of CBS activity by amino-oxyacetate and
CBS silencing with a short hairpin RNA vector targeting rat CBS gene reversed the protective action of ADMA against MPP +-caused cytotoxicity, ROS overproduction, and MMP loss in PC12 cells. These results indicate that the protection of ADMA against
MPP +-mediated neurotoxicity involves the melioration of MPP +-induced inhibition of endogenous H 2S generation. Our findings suggest that modulation of H 2S production provide new therapeutic targets for the treatment of neurodegenerative disease, such as Parkinson’s disease. 相似文献
13.
Guanosine exerts neuroprotective effects in the central nervous system. Apoptosis, a morphological form of programmed cell
death, is implicated in the pathophysiology of Parkinson’s disease (PD). MPP +, a dopaminergic neurotoxin, produces in vivo and in vitro cellular changes characteristic of PD, such as cytotoxicity, resulting
in apoptosis. Undifferentiated human SH-SY5Y neuroblastoma cells had been used as an in vitro model of Parkinson’s disease.
We investigated if extracellular guanosine affected MPP +-induced cytotoxicity and examined the molecular mechanisms mediating its effects. Exposure of neuroblastoma cells to MPP + (10 μM–5 mM for 24–72 h) induced DNA fragmentation in a time-dependent manner ( p < 0.05). Administration of guanosine (100 μM) before, concomitantly with or, importantly, after the addition of MPP + abolished MPP +-induced DNA fragmentation. Addition of MPP + (500 μM) to cells increased caspase-3 activity over 72 h ( p < 0.05), and this was abolished by pre- or co-treatment with guanosine. Exposure of cells to pertussis toxin prior to MPP + eliminated the anti-apoptotic effect of guanosine, indicating that this effect is dependent on a Gi protein-coupled receptor,
most likely the putative guanosine receptor. The protection by guanosine was also abolished by the selective inhibitor of
the enzyme PI-3-K/Akt/PKB (LY294002), confirming that this pathway plays a decisive role in this effect of guanosine. Neither
MPP + nor guanosine had any significant effect on α-synuclein expression. Thus, guanosine antagonizes and reverses MPP +-induced cytotoxicity of neuroblastoma cells via activation of the cell survival pathway, PI-3-K/Akt/PKB. Our results suggest
that guanosine may be an effective pharmacological intervention in PD. 相似文献
14.
The aim of present study is to explore the cytoprotection of curcumin against 1-methyl-4-phenylpridinium ions (MPP +)-induced apoptosis and the molecular mechanisms underlying in PC12 cells. Our findings indicated that MPP + significantly reduced the cell viability and induced apoptosis of PC12 cells. Curcumin protected PC12 cells against MPP +-induced cytotoxicity and apoptosis not only by inducing overexpression of Bcl-2, but also reducing the loss of mitochondrial
membrane potential (MMP), an increase in intracellular reactive oxygen species (ROS) and overexpression of inducible nitric
oxide synthase (iNOS). The selective iNOS inhibitor AG partly blocked MPP +-induced apoptosis of PC12 cells. The results of present study suggested that the cytoprotective effects of curcumin might
be mediated, at least in part, by the Bcl-2-mitochondria-ROS-iNOS pathway. Because of its non-toxic property, curcumin could
be further developed to treat the neurodegenerative diseases which are associated with oxidative stress, such as Parkinson’s
disease (PD).
J. Chen and X. Q. Tang are contributed equally to this work. 相似文献
15.
The hematopoietic cytokines erythropoietin (Epo) and granulocyte-colony stimulating factor (G-CSF) provide neuroprotection in several in vitro and in vivo models of Parkinson’s disease (PD). The molecular mechanism by which Epo and G-CSF signals reduce the neuronal death in PD is not clear. Here, we show that in rat pheochromocytoma PC12 cells, Epo and G-CSF efficiently repressed the 1-methyl-4-phenylpyridinium (MPP +)-induced expression of the proapoptotic protein PUMA (p53 up-regulated modulator of apoptosis). Accordingly, Epo and G-CSF treatment reduced the PC12 cell fraction that underwent apoptosis by MPP + treatment and thus improved cell viability. Downregulation of PUMA expression by Epo and G-CSF in MPP +-treated PC12 cells seems to be mediated by repression of p53, as the expression of p53 was increased by MPP +-treatment and reduced by Epo and G-CSF. Together, these results suggest that the neuroprotective activities of Epo and G-CSF in an experimental model of PD involve the repression of the apoptosis-inducing action of PUMA. 相似文献
16.
(1) The present study was designed to investigate whether histamine is involved in the protective effect of carnosine on Aβ42-induced
impairment in differentiated PC12 cells. (2) PC12 cells were exposed to Aβ42 (5 μM) for 24 h after carnosine (5 mM) applied
for 18 h. Histamine receptor antagonists (diphenhydramine, zolantidine, thioperamide, clobenpropit) or histidine decarboxylase
inhibitor (α-fluoromethylhistidine) were added 15 min before carnosine. Cell viability, glutamate release or cell surface
expression of NMDA receptor was examined. (3) Aβ42 caused a concentration-dependent reduction of viability in PC12 cells and
pretreatment with carnosine ameliorated this impairment. This amelioration was reversed by the H 3 receptor antagonists thioperamide and clobenpropit, but not by either the H 1 receptor antagonist diphenhydramine or the H 2 receptor antagonist zolantidine. Further, α-fluoromethylhistidine, an irreversible inhibitor of histidine decarboxylase,
also had no effect. In the presence of Aβ42, carnosine significantly decreased glutamate release and carnosine increased the
surface expression of NMDA receptor. (4) These results indicate that the mechanism by which carnosine attenuates Aβ42-induced
neurotoxicity is independent of the carnosine–histidine–histamine pathway, but may act through regulation of glutamate release
and NMDA receptor trafficking. 相似文献
17.
The α 1 subunit coding for the human brain type E calcium channel (Schneider et al., 1994) was expressed in Xenopus oocytes in the absence, and in combination with auxiliary α 2δ and β subunits. α 1E channels directed with the expression of Ba 2+ whole-cell currents that completely inactivated after a 2-sec membrane pulse. Coexpression of α 1E with α 2bδ shifted the peak current by +10 mV but had no significant effect on whole-cell current inactivation. Coexpression of α 1E with β 2a shifted the peak current relationship by −10 mV, and strongly reduced Ba 2+ current inactivation. This slower rate of inactivation explains that a sizable fraction (40 ± 10%, n= 8) of the Ba 2+ current failed to inactivate completely after a 5-sec prepulse. Coinjection with both the cardiac/brain β 2a and the neuronal α 2bδ subunits increased by ≈10-fold whole-cell Ba 2+ currents although coinjection with either β 2a or α 2bδ alone failed to significantly increase α 1E peak currents. Coexpression with β 2a and α 2bδ yielded Ba 2+ currents with inactivation kinetics similar to the β 2a induced currents, indicating that the neuronal α 2bδ subunit has little effect on α 1E inactivation kinetics. The subunit specificity of the changes in current properties were analyzed for all four β subunit
genes. The slower inactivation was unique to α 1E/β 2a currents. Coexpression with β 1a, β 1b, β 3, and β 4, yielded faster-inactivating Ba 2+ currents than currents recorded from the α 1E subunit alone. Furthermore, α 1E/α 2bδ/β 1a; α 1E/α 2bδ/β 1b; α 1E/α 2bδ/β 3; α 1E/α 2bδ/β 4 channels elicited whole-cell currents with steady-state inactivation curves shifted in the hyperpolarized direction. The
β subunit-induced changes in the properties of α 1E channel were comparable to modulation effects reported for α 1C and α 1A channels with β 3≈β 1b > β 1a≈β 4≫β 2a inducing fastest to slowest rate of whole-cell inactivation.
Received: 27 March 1997/Revised: 10 July 1997 相似文献
18.
The aim of this study was to determine whether changes in the circulating thyroid hormone (TH) and brain synaptosomal TH content
affected the relative levels of mRNA encoding different thyroid hormone receptor (TR) isoforms in adult rat brain. Northern
analysis of polyA +RNA from cerebral cortex, hippocampus and cerebellum of control and hypothyroid adult rats was performed in order to determine
the relative expression of all TR isoforms. Circulating and synaptosomal TH concentrations were determined by radioimmunoassay.
Region-specific quantitative differences in the expression pattern of all TR isoforms in euthyroid animals and hypothyroid
animals were recorded. In hypothyroidism, the levels of TRα2 mRNA (non-T 3-binding isoform) were decreased in all brain regions examined. In contrast the relative expression of TRα1 was increased
in cerebral cortex and hippocampus, whereas in cerebellum remained unaffected. The TRβ1 relative expression in cerebral cortex
and hippocampus of hypothyroid animals was not affected, whereas this TR isoform was not detectable in cerebellum. The TR
isoform mRNA levels returned to control values following T 4 intraperitoneal administration to the hypothyroid rats. The obtained results show that in vivo depletion of TH regulates TR gene expression in adult rat brain in a region-specific manner. (Mol Cell Biochem 278: 93–100, 2005) 相似文献
19.
Ganglioside GM1 was shown to increase the viability of PC12 cells exposed to hydrogen peroxide or amyloid β-peptide (Aβ 25–35). The PC12 cells transfected with mutant gene (expressing APP SW) were found to be more sensitive to oxidative stress than the cells transfected with wild type gene (expressing APP WT) or vector-transfected cells, GM1 being effective in enhancing the viability of the cells transfected with mutant gene. The
exposure to hydrogen peroxide or Aβ 25–35 results in a partial inactivation of Na +,K +-ATPase in PC12 cells, H 2O 2 increases MDA accumulation in these cells. But these effects could be partially prevented or practically abolished by GM1
ganglioside. In the presence of the inhibitor of tyrosine kinase of Trk receptors (K-252a) the protective and metabolic effects
of GM1 on PC12 cells in conditions of oxidative stress caused by hydrogen peroxide are not observed or are markedly diminished. 相似文献
20.
Aberrant mitochondrial function appears to play a central role in dopaminergic neuronal loss in Parkinson''s disease (PD). 1-methyl-4-phenylpyridinium iodide (MPP +), the active metabolite of N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), is a selective inhibitor of mitochondrial complex I and is widely used in rodent and cell models to elicit neurochemical alterations associated with PD. Recent findings suggest that Glycogen Synthase Kinase-3β (GSK-3β), a critical activator of neuronal apoptosis, is involved in the dopaminergic cell death. In this study, the role of GSK-3β in modulating MPP +-induced mitochondrial dysfunction and neuronal death was examined in vivo, and in two neuronal cell models namely primary cultured and immortalized neurons. In both cell models, MPTP/MPP + treatment caused cell death associated with time- and concentration-dependent activation of GSK-3β, evidenced by the increased level of the active form of the kinase, i.e. GSK-3β phosphorylated at tyrosine 216 residue. Using immunocytochemistry and subcellular fractionation techniques, we showed that GSK-3β partially localized within mitochondria in both neuronal cell models. Moreover, MPP + treatment induced a significant decrease of the specific phospho-Tyr216-GSK-3β labeling in mitochondria concomitantly with an increase into the cytosol. Using two distinct fluorescent probes, we showed that MPP + induced cell death through the depolarization of mitochondrial membrane potential. Inhibition of GSK-3β activity using well-characterized inhibitors, LiCl and kenpaullone, and RNA interference, prevented MPP +-induced cell death by blocking mitochondrial membrane potential changes and subsequent caspase-9 and -3 activation. These results indicate that GSK-3β is a critical mediator of MPTP/MPP +-induced neurotoxicity through its ability to regulate mitochondrial functions. Inhibition of GSK-3β activity might provide protection against mitochondrial stress-induced cell death. 相似文献
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