Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0030567 (Parkinson's disease)
 63,064 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A mild heat shock preconditioning has been shown to induce thermotolerance and protection against a number of cytotoxic agents that may induce cell death by either apoptosis or necrosis. 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) is a neurotoxin that selectively targets dopaminergic cells of the substantia nigra and, as such, it is often used to induce neuronal cell death in models of Parkinson's disease. PC12 cells were heat-shocked for 1 h at 41.5 degrees C. This led to a rapid induction of Hsp25 and Hsp70. Levels of these proteins remained elevated for at least 24 h post heat shock. Treatment of PC12 cells with 1-methyl-4-phenylpyridinium (MPP(+)), the active metabolite of MPTP, resulted in cell death. Morphological analysis and the lack of caspase activity suggested that cell death was by necrosis. Heat shocking the cells 6 h prior to addition of MPP(+) significantly inhibited the induction of cell death by MPP(+). These results indicated that heat shock is protective against MPP(+) neurotoxicity in PC12 cells.
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PMID:Heat shock protects PC12 cells against MPP+ toxicity. 1464 38

Parkinson's disease is characterized by dopaminergic neuronal death and the presence of Lewy bodies. alpha-Synuclein is a major component of Lewy bodies, but the process of its accumulation and its relationship to dopaminergic neuronal death has not been resolved. Although the pathogenesis has not been clarified, mitochondrial complex I is suppressed, and caspase-3 is activated in the affected midbrain. Here we report that a combination of 1-methyl-4-phenylpyridinium ion (MPP(+)) or rotenone and proteasome inhibition causes the appearance of alpha-synuclein-positive inclusion bodies. Unexpectedly, however, proteasome inhibition blocked MPP(+)- or rotenone-induced dopaminergic neuronal death. MPP(+) elevated proteasome activity, dephosphorylated mitogen-activating protein kinase (MAPK), and activated caspase-3. Proteasome inhibition reversed the MAPK dephosphorylation and blocked caspase-3 activation; the neuroprotection was blocked by a p42 and p44 MAPK kinase inhibitor. Thus, the proteasome plays an important role in both inclusion body formation and dopaminergic neuronal death but these processes form opposite sides on the proteasome regulation in this model.
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PMID:Proteasome mediates dopaminergic neuronal degeneration, and its inhibition causes alpha-synuclein inclusions. 1467 49

The established or potentially toxic agents implicated in the nigral cell death in Parkinson's disease, dopamine, 1-methyl-4-phenylpyridinium (MPP(+)), iron, and manganese, were examined as to their effects on the viability of cells overexpressing alpha-synuclein. SK-N-MC neuroblastoma cells stably expressing the human dopamine transporter were transfected with human alpha-synuclein and cell clones with and without alpha-synuclein immunoreactivity were obtained. Cells were exposed for 24-72 h to 1-10 microM dopamine, 0.1-3 microM MPP(+), 0.1-1 mM FeCl(2) or 30-300 microM MnCl(2) added to the culture medium. There was no difference between cells expressing alpha-synuclein and control cells after exposure to dopamine, MPP(+) or FeCl(2). However, MnCl(2) resulted in a significantly stronger decreased viability of cells overexpressing alpha-synuclein after 72 h. These findings suggest that manganese may co-operate with alpha-synuclein in triggering neuronal cell death such as seen in manganese parkinsonism. The relevance of our observations for the pathoetiology of Parkinson's disease proper remains to be determined.
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PMID:alpha-Synuclein selectively increases manganese-induced viability loss in SK-N-MC neuroblastoma cells expressing the human dopamine transporter. 1469 76

1-Methyl-4-phenyl-1,2,5,6-tetrahydropyridine (MPTP) is a dopaminergic toxin which produces Parkinson's disease-like symptoms in primates and dopaminergic cell loss in mice. MPTP is bioactivated through monoamine oxidase to MPP(+) and detoxified by cytochrome P450 to nor-MPTP. We have examined metabolisms of MPTP to nor-MPTP by mouse brain microsomes and compared it with corresponding activity in liver. In brain, but not in liver, this biotransformation was completely abolished by quinidine, an inhibitor of P4502D. Northern blotting experiments demonstrated constitutive expression of cytochrome P4502D mRNA predominantly in neuronal cells within the cortex, hippocampus, thalamus, Purkinje and granule cell layers of the cerebellum and in the reticular neurons of midbrain. Striatal neurons were sparsely stained indicating a relative paucity of expression. These studies demonstrate for the first time that detoxification of MPTP to nor-MPTP occurs in mouse brain through cytochrome P4502D which is primarily localized in neuronal cells. Cytochrome P4502D6 is known to exhibit genetic polymorphism in humans, and a defect in this isoform could potentially lead to decreased detoxification of neurotoxins in certain neuronal sub-population, which in turn may have implications in pathogenesis of Parkinson's disease.
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PMID:Characterization and localization of cytochrome P450 mediated metabolism of MPTP to nor-MPTP in mouse brain: relevance to Parkinson's disease. 1471 67

1-Methyl-4-phenylpyridinium (MPP(+)) is a neurotoxin that causes Parkinson's disease in experimental animals and humans. Despite the fact that intracellular iron was shown to be crucial for MPP(+)-induced apoptotic cell death, the molecular mechanisms for the iron requirement remain unclear. We investigated the role of transferrin receptor (TfR) and iron in modulating the expression of alpha-synuclein (alpha-syn) in MPP(+)-induced oxidative stress and apoptosis. Results show that MPP(+) inhibits mitochondrial complex-1 and aconitase activities leading to enhanced H(2)O(2) generation, TfR expression and alpha-syn expression/aggregation. Pretreatment with cell-permeable iron chelators, TfR antibody (that inhibits TfR-mediated iron uptake), or transfection with glutathione peroxidase (GPx1) enzyme inhibits intracellular oxidant generation, alpha-syn expression/aggregation, and apoptotic signaling as measured by caspase-3 activation. Cells overexpressing alpha-syn exacerbated MPP(+) toxicity, whereas antisense alpha-syn treatment totally abrogated MPP(+)-induced apoptosis in neuroblastoma cells without affecting oxidant generation. The increased cytotoxic effects of alpha-syn in MPP(+)-treated cells were attributed to inhibition of mitogen-activated protein kinase and proteasomal function. We conclude that MPP(+)-induced iron signaling is responsible for intracellular oxidant generation, alpha-syn expression, proteasomal dysfunction, and apoptosis. Relevance to Parkinson's disease is discussed.
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PMID:Alpha-synuclein up-regulation and aggregation during MPP+-induced apoptosis in neuroblastoma cells: intermediacy of transferrin receptor iron and hydrogen peroxide. 1474 48

1-Methyl-4-phenylpyridinium (MPP(+)) ion, a toxic metabolite of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, is produced by monoamine oxidase B in astrocytes. MPP(+) causes a selective dopaminergic neurodegeneration, the pathophysiologic hallmark of Parkinson disease. However, the toxic effect of MPP(+) on astrocytes remains unclear. Here, we examined the effect of MPP(+) on human astrocytoma U373MG cells, with particular attention to the temporal interaction of glutathione (GSH) and reactive oxygen species (ROS) (H2O2 and O). MPP(+) induced astrocyte apoptosis in a dose-dependent manner 48 hr after treatment. Distinctive early (<6 hr) and late (24-48 hr) responses were observed. ROS production and the oxidized GSH (GSSG)/GSH ratio, indicators of oxidative stress, rose dramatically after 24 hr of MPP(+) exposure, whereas the H2O2 level transiently decreased at 6 hr. ROS overproduction and GSH dysfunction were concomitantly associated with caspase-3 activation and finally led to cell apoptosis. Moreover, GSH depletion by diethyl maleate, but not buthionine sulfoximine, caused cells to die quickly and potentiated the cytotoxicity of MPP(+). Co-treatment with melatonin, a known antioxidant secreted by the pineal gland, significantly prevented cell apoptosis by inhibiting oxidative stress and caspase-3 activation, but it did not affect that the early changes due to MPP(+) treatment. Our results demonstrate that in astrocytes, GSH is involved in the early decrease and late increase in ROS levels induced by MPP(+) treatment. Melatonin remedies the dysfunction of GSH system to block caspase-3 activation and cell apoptosis induced by oxidative stress during the long-term exposure of MPP(+).
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PMID:Effect of melatonin on temporal changes of reactive oxygen species and glutathione after MPP(+) treatment in human astrocytoma U373MG cells. 1496 63

The neuropathology of Parkinson's Disease has been modeled in experimental animals following MPTP treatment and in dopaminergic cells in culture treated with the MPTP neurotoxic metabolite, MPP(+). MPTP through MPP(+) activates the stress-activated c-Jun N-terminal kinase (JNK) pathway in mice and SH-SY5Y neuroblastoma cells. Recently, it was demonstrated that CEP-1347/KT7515 attenuated MPTP-induced nigrostriatal dopaminergic neuron degeneration in mice, as well as MPTP-induced JNK phosphorylation. Presumably, CEP-1347 acts through inhibition of at least one upstream kinase within the mixed lineage kinase (MLK) family since it has been shown to inhibit MLK 1, 2 and 3 in vitro. Activation of the MLK family leads to JNK activation. In this study, the potential role of MLK and the JNK pathway was examined in MPP(+)-induced cell death of differentiated SH-SY5Y cells using CEP-1347 as a pharmacological probe and dominant negative adenoviral constructs to MLKs. CEP-1347 inhibited MPP(+)-induced cell death and the morphological features of apoptosis. CEP-1347 also prevented MPP(+)-induced JNK activation in SH-SY5Y cells. Endogenous MLK 3 expression was demonstrated in SH-SY5Y cells through protein levels and RT-PCR. Adenoviral infection of SH-SY5Y cells with a dominant negative MLK 3 construct attenuated the MPP(+)-mediated increase in activated JNK levels and inhibited neuronal death following MPP(+) addition compared to cultures infected with a control construct. Adenoviral dominant negative constructs of two other MLK family members (MLK 2 and DLK) did not protect against MPP(+)-induced cell death. These studies show that inhibition of the MLK 3/JNK pathway attenuates MPP(+)-mediated SH-SY5Y cell death in culture and supports the mechanism of action of CEP-1347 as an MLK family inhibitor.
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PMID:Inhibition of mixed lineage kinase 3 attenuates MPP+-induced neurotoxicity in SH-SY5Y cells. 1501 67

The cellular mechanisms underlying the neurodegenerative process in Parkinson's disease are not well understood. Using RNA interference (RNAi), we demonstrate that caspase-3-dependent proteolytic activation of protein kinase Cdelta (PKCdelta) contributes to the degenerative process in dopaminergic neurons. The Parkinsonian toxin MPP(+) activated caspase-3 and proteolytically cleaved PKCdelta into catalytic and regulatory subunits, resulting in persistent kinase activation in mesencephalic dopaminergic neuronal cells. The caspase-3 inhibitor Z-DEVD-FMK and the caspase-9 inhibitor Z-LEHD-FMK effectively blocked MPP(+)-induced PKCdelta proteolytic activation. To characterize the functional role of PKCdelta activation in MPP(+)-induced dopaminergic cell death, RNAi-mediated gene knockdown was performed. Among four siRNAs designed against PKCdelta, two specifically suppressed PKCdelta expression. The application of siRNA abolished the MPP(+)-induced PKCdelta activation, DNA fragmentation, and tyrosine hydroxylase (TH)-positive neuronal loss. Together, these results suggest that proteolytic activation of PKCdelta may be a critical downstream event in the degenerative process of Parkinson's disease.
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PMID:Suppression of caspase-3-dependent proteolytic activation of protein kinase C delta by small interfering RNA prevents MPP+-induced dopaminergic degeneration. 1503 69

The present study aims to study sequential alterations occurring in both dopaminergic neurons and microglia in substantia nigra (SN) following intrastriatal injection of 1-methyl-4-phenylpridium ion (MPP+) in rats. Heme oxygenase-1 (HO-1), a marker of oxidative stress, first appeared in dopaminergic neurons in SN at 1 day post-lesion. Subsequently, microglia in SN exhibited morphological changes indicative of activation. At 7 days post-lesion, those findings increased severity and 7a significant reduction in the number of dopaminergic neurons was observed. The present finding suggests that extensive oxidative stress and secondary-induced neuroinflammation play a relevant role in MPP(+)-induced retrograde dopaminergic neuron degeneration. We hope that this model will be useful in developing a disease modifying therapy of Parkinson's disease.
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PMID:Oxidative stress and microglial activation in substantia nigra following striatal MPP+. 1507 30

Endogenous or exogenous beta-carboline (betaC) derivatives structurally related to the selective dopaminergic neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and its active metabolite 1-methyl-4-phenylpyridinium (MPP(+)) may contribute to dopaminergic neurodegeneration in Parkinson's disease (PD). We addressed the importance of the dopamine transporter (DAT) for selective dopaminergic toxicity by testing the differential cytotoxicity and cellular uptake of 12 betaCs in human embryonic kidney HEK-293 cells ectopically expressing the DAT gene. Cell death was measured using [4,5-Dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) and trypan blue exclusion assays, and uptake by a fluorescence-based uptake assay. All betaCs and MPP(+) showed general cytotoxicity in parental HEK-293 cells after 72 h with half-maximal toxic concentrations (TC(50) values) in the upper micromolar range. Besides MPP(+), only 2[N]-methylated compounds showed enhanced cytotoxicity in DAT expressing HEK-293 cells with 1.3- to 4.5-fold reduction of TC(50) values compared with parental cell line. The rank order of selectivity was: MPP(+) >> 2[N],9[N]-dimethyl-harminium > 2[N]-methyl-harminium > 2[N],9[N]-dimethyl-harmanium = 2[N]-methyl-norharmanium > 2[N]-methyl-harmanium > 2[N],9[N]-dimethyl-norharminium. Consistently, only 2[N]-methylated betaCs were transported into the cell through the DAT with up to five times greater K(m) and 12-220 times smaller V(max) values compared with dopamine and MPP(+). There was a weak relation of DAT-mediated selectivity with the affinity of betaCs at the DAT (K(m)), but not with V(max). Our data suggest that DAT-mediated cellular uptake of 2[N]-methylated betaCs represents a potential mechanism for selective toxicity towards dopaminergic neurons and may be relevant for the pathogenesis of Parkinson's disease.
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PMID:Dopamine transporter-mediated cytotoxicity of beta-carbolinium derivatives related to Parkinson's disease: relationship to transporter-dependent uptake. 1508 25


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