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

Loss of motor function in Parkinson's disease is due in part to degeneration of dopamine (DA) neurons. Pharmacological evidence suggests that the mitogen-activated protein kinase signaling pathways involving extracellular signal-regulated kinases (ERKs) play important roles in neuroprotection of DA neurons. However, the relative roles of the several ERK isoforms in the viability of DA neurons have not yet been determined. In the present study, we investigated the contributions of ERK5, as well as ERK1/2, to MN9D cell survival under basal conditions and in response to 6-hydroxydopamine (6-OHDA). We observed that U0126, an inhibitor of ERK activation, decreased basal survival of these cells. To differentiate between ERK1/2 and ERK5, cells were transfected with a dominant negative form of either ERK5 or MEK1, the upstream activator of ERK1/2. Transfection of MN9D cells with either dominant negative construct mimicked U0126, reducing cell survival. Moreover, transfection of the cells in such a way as to increase ERK5 or ERK1/2 activity inhibited 6-OHDA-induced cell death, although this effect was significant only in the case of ERK1/2 activation. These studies suggest that activations of ERK5 and ERK1/2 both promote basal DA cell survival and that ERK1/2 also protects DA cells from oxidative stress. These are the first studies to demonstrate a role for ERK5 in DA neuronal survival and to investigate the relative roles of ERK1/2 and ERK5 in basal DA survival and neuroprotection from oxidative stress.
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PMID:Neuroprotective role of ERK1/2 and ERK5 in a dopaminergic cell line under basal conditions and in response to oxidative stress. 1694 94

Autosomal dominant Parkinson disease (PD) is caused by duplication or triplication of the alpha-synuclein gene as well as by the A30P, E46K, and A53T mutations. The mechanisms are unknown. Reactive astrocytes in the substantia nigra of PD and MPTP-treated monkeys display high levels of the inflammatory mediator intercellular adhesion molecule-1 (ICAM-1), indicating that chronic inflammation contributes to the degeneration. Here we report that alpha-synuclein strongly stimulates human astrocytes as well as human U-373 MG astrocytoma cells to up-regulate both interleukin (IL)-6 and ICAM-1 (ED50=5 microg ml(-1)). The mutated forms are more potent stimulators than wild-type (WT) alpha-synuclein in these assays. We demonstrate by immunoblotting analysis that this up-regulation is associated with activation of the major mitogen-activated protein kinase (MAPK) pathways. It is also attenuated by PD 98059, an inhibitor of the MAPK/extracellular-regulated kinase kinase MEK1/2, SP 600125, an inhibitor of c-Jun N-terminal kinase (JNK), and SB 202190, an inhibitor of p38 MAPK. The inhibitory effects on human astrocytes have IC50 values of 2, 5, and 1.5 microM respectively. We hypothesize that the neuroinflammation stimulated by release of an excess of normal alpha-synuclein or by release of its mutated forms can be involved in the pathobiology of PD.
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PMID:Alpha-synuclein and its disease-causing mutants induce ICAM-1 and IL-6 in human astrocytes and astrocytoma cells. 1701 52

Both rotenone and manganese are possible neurotoxins for a wide variety of cell and neuronal types including dopaminergic neurons and induce apoptosis in various cells. Neurotrophic factors have the potential for therapeutic development when used to prevent Parkinson's disease. In this paper, we focused on the differences between rotenone and manganese as toxins, and characterized the influence of neurotrophic factors on toxin-induced apoptosis in PC12 cells. There were distinct differences in intracellular mechanisms between rotenone- and manganese-induced apoptosis such as the production of reactive oxygen species, the response to antioxidants, and the activation of the c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (MAPK). Nerve growth factor (NGF) almost completely prevented rotenone-induced but not manganese-induced caspase activation and DNA fragmentation. The differential effect of NGF was found to be mainly due to the down-regulation of the Trk tyrosine kinase receptor by manganese but not by rotenone. Prevention of rotenone-induced apoptosis by NGF was attenuated by the phosphatidylinositol 3-kinase (PI 3-kinase) inhibitor, LY294002, but not MAPK kinase (MEK) inhibitors, PD98059 or U0126. These results demonstrate that the potential neurotoxins for dopaminergic cells exert their toxic effect by activation of different signaling pathways of apoptosis and that NGF prevents rotenone-induced apoptosis through the activation of the PI 3-kinase pathway not MAPK pathway.
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PMID:Differential effect of nerve growth factor on dopaminergic neurotoxin-induced apoptosis. 1702 96

Parkinson's disease (PD), a neurodegenerative disorder, causes severe motor impairment due to loss of dopaminergic neurons in substantia nigra pars compacta (SNpc). MPTP, a neurotoxin that causes dopaminergic cell loss in mice, was used in an animal model to study the pathogenic mechanisms leading to neurodegeneration. We observed the activation of apoptosis signal regulating kinase (ASK1, MAPKKK) and phosphorylation of its downstream targets MKK4 and JNK, 12 h after administration of a single dose of MPTP. Further, Daxx, the death-associated protein, translocated to the cytosol selectively in SNpc neurons seemingly due to MPTP mediated down-regulation of DJ-1, the redox-sensitive protein that binds Daxx in the nucleus. Coadministration of alpha-lipoic acid (ALA), a thiol antioxidant, abolished the activation of ASK1 and phosphorylation of downstream kinases, MKK4, and JNK and prevented the down-regulation of DJ-1 and translocation of Daxx to the cytosol seen after MPTP. ALA also attenuated dopaminergic cell loss in SNpc seen after subchronic MPTP treatment. Our studies demonstrate for the first time that MPTP triggers death signaling pathway by activating ASK1 and translocating Daxx, in vivo, in dopaminergic neurons in SNpc of mice and thiol antioxidants, such as ALA terminate this cascade and afford neuroprotection.
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PMID:Activation of apoptosis signal regulating kinase 1 (ASK1) and translocation of death-associated protein, Daxx, in substantia nigra pars compacta in a mouse model of Parkinson's disease: protection by alpha-lipoic acid. 1736 8

The molecular basis of L-3,4-dihydroxyphenylalanine (L-DOPA)-induced dyskinesia (LID), one of the major hindrances in the current therapy for Parkinson's disease, is still unclear. We show that attenuation of cAMP signaling in the medium spiny neurons of the striatum, achieved by genetic inactivation of the dopamine and cAMP-regulated phosphoprotein of 32 kDa (DARPP-32), reduces LID. We also show that, in dyskinetic mice, sensitized cAMP/cAMP-dependent protein kinase/DARPP-32 signaling leads to phosphorylation/activation of the extracellular signal-regulated protein kinases 1 and 2 (ERK1/2). The increase in ERK1/2 phosphorylation associated with dyskinesia results in activation of mitogen- and stress-activated kinase-1 (MSK-1) and phosphorylation of histone H3, two downstream targets of ERK involved in transcriptional regulation. In line with these observations, we found that c-Fos expression is abnormally elevated in the striata of mice affected by LID. Persistent enhancement of the ERK signaling cascade is implicated in the generation of LID. Thus, pharmacological inactivation of ERK1/2 achieved using SL327 (alpha-[amino[(4-aminophenyl)thio]methylene]-2-(trifluoromethyl)benzeneacetonitrile), an inhibitor of the mitogen-activated kinase/ERK kinase, MEK, during chronic L-DOPA treatment counteracts the induction dyskinesia. Together, these results indicate that a significant proportion of the abnormal involuntary movements developed in response to chronic L-DOPA are attributable to hyperactivation in striatal medium spiny neurons of a signaling pathway including sequential phosphorylation of DARPP-32, ERK1/2, MSK-1, and histone H3.
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PMID:Critical involvement of cAMP/DARPP-32 and extracellular signal-regulated protein kinase signaling in L-DOPA-induced dyskinesia. 1759 48

Nurr1 is an orphan nuclear receptor essential for development and survival of dopaminergic neurons. Mutations in Nurr1 are associated with Parkinson's disease (PD) and there is a correlation between Nurr1 and tyrosine hydroxylase (TH) expression in PD brain. Two domains, activation function 1 (AF1) at the N-terminus and AF2 at the C-terminus of Nurr1, are important for Nurr1 activation. AF1 domain is conserved in NGFI-B/Nurr1/Nor-1 family members and MAPK signal pathway is involved in AF1 activity. Using in vitro phoshorylation assays, we have shown that ERK2 is a kinase to phosphorylate Nurr1 on multiple sites. S126 and T132, which are located near AF1 core of Nurr1, are dominant sites phosphorylated by ERK2. Moreover, using GST pull-down and co-IP assays, we identified that both the N-terminus of Nurr1 containing three ERK docking domains and another ERK docking domain in Nurr1 DNA binding domain are able to bind to ERK2. Furthermore, overexpression of a constitutively active form of MEK1, together with Nurr1 and mouse ERK2, greatly increases the tyrosine hydroxylase expression in SH-SY5Y cells. Reporter gene assays show that Nurr1Delta124-133/T185A, an ERK2 phospho-site mutant form, could not further increase its transcriptional activity on TH promoter, suggesting that Nurr1 phosphorylation by ERK2 may regulate its transcriptional activity on TH promoter. Thus, our results indicate that Nurr1 phosphorylation by ERK2 may play a role in regulating the TH expression.
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PMID:Nurr1 is phosphorylated by ERK2 in vitro and its phosphorylation upregulates tyrosine hydroxylase expression in SH-SY5Y cells. 1768 92

It is well documented that the mitogen-activated protein kinase pathway plays a pivotal role in rats with 6-hydroxydopamine (6-OHDA)-induced unilateral lesion in the nigrostriatal system. Our recent studies have shown that mixed-lineage kinase 3 (MLK3) and apoptosis-inducing kinase 1 (ASK1) are all involved in neuronal cell death induced by ischemia, which is mediated by the MLK3/c-Jun NH2-terminal kinase 3 (JNK3) and ASK1/JNK signaling pathway. To investigate whether these pathways are correlated with 6-OHDA-induced lesion as well, we examined the phosphorylation of MLK3, ASK1, and JNK3 in 6-OHDA rats. The results showed that both MLK3 and ASK1 could activate JNK3 and then subsequently enhance the neuronal death through its downstream pathways (i.e., nuclear and non-nuclear pathway). K252a have wide-range effects including Trk inhibition, MLK3 inhibition, and activation of phosphatidylinositol 3 kinase and mitogen-activated protein kinase kinase signaling pathways through interactions with distinct targets and is a well known neuroprotective compound. We found that K252a could protect dopaminergic neurons against cell program death induced by 6-OHDA lesion, and the phenotypes of 6-OHDA rat model treated with K252a were partial rescued. The inhibition of K252a on the activation of MLK3/JNK3 and ASK1/JNK3 provided a link between 6-OHDA lesion and stress-activated kinases. It suggested that both proapoptotic MLK3/JNK3 and ASK1/JNK3 cascade may play an important role in dopaminergic neuronal death in 6-OHDA insult. Thus, the JNK3 signaling may eventually emerge as a prime target for novel therapeutic approaches to treatment of Parkinson disease, and K252a may serve as a potential and important neuroprotectant in therapeutic aspect in Parkinson disease.
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PMID:K252a prevents nigral dopaminergic cell death induced by 6-hydroxydopamine through inhibition of both mixed-lineage kinase 3/c-Jun NH2-terminal kinase 3 (JNK3) and apoptosis-inducing kinase 1/JNK3 signaling pathways. 1785 52

The orphan nuclear receptor NURR1 is critical for the development of mesencephalic dopamine neurons and directly regulates tyrosine hydroxylase (TH) via specific NGFI-B response elements (NBRE). We identified a Parkinson's disease patient with a NURR1 mutation, resulting in a p.Ser125Cys change, immediately adjacent to the putative ERK1/2 phosphorylation site. Here we show, in dopaminergic SK-N-AS human neuroblastoma cells, that this substitution markedly attenuated NURR1-induced transcriptional activation through a human TH promoter NBRE. Furthermore, in SK-N-AS cells co-transfected with the dopamine-D2S receptor and NURR1, the dopamine-D2 agonist quinpirole stimulated ERK1/2 phosphorylation and enhanced transcriptional activation by wild-type NURR1 but not the p.Ser125Cys NURR1 mutant, and these actions were blocked by the specific MEK1/2 inhibitor PD98059. These results indicate that Ser125 is critical for basal and ERK1/2-induced NURR1 activity and suggest a role for this and other NURR1 mutations in the regulation of dopamine synthesis and predisposition to Parkinson's disease.
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PMID:A Nurr1 point mutant, implicated in Parkinson's disease, uncouples ERK1/2-dependent regulation of tyrosine hydroxylase transcription. 1789 97

The death of midbrain dopaminergic neurons in sporadic Parkinson disease is of unknown etiology but may involve altered growth factor signaling. The present study showed that leptin, a centrally acting hormone secreted by adipocytes, rescued dopaminergic neurons, reversed behavioral asymmetry, and restored striatal catecholamine levels in the unilateral 6-hydroxydopamine (6-OHDA) mouse model of dopaminergic cell death. In vitro studies using the murine dopaminergic cell line MN9D showed that leptin attenuated 6-OHDA-induced apoptotic markers, including caspase-9 and caspase-3 activation, internucleosomal DNA fragmentation, and cytochrome c release. ERK1/2 phosphorylation (pERK1/2) was found to be critical for mediating leptin-induced neuroprotection, because inhibition of the MEK pathway blocked both the pERK1/2 response and the pro-survival effect of leptin in cultures. Knockdown of the downstream messengers JAK2 or GRB2 precluded leptin-induced pERK1/2 activation and neuroprotection. Leptin/pERK1/2 signaling involved phosphorylation and nuclear localization of CREB (pCREB), a well known survival factor for dopaminergic neurons. Leptin induced a marked MEK-dependent increase in pCREB that was essential for neuroprotection following 6-OHDA toxicity. Transfection of a dominant negative MEK protein abolished leptin-enhanced pCREB formation, whereas a dominant negative CREB or decoy oligonucleotide diminished both pCREB binding to its target DNA sequence and MN9D survival against 6-OHDA toxicity. Moreover, in the substantia nigra of mice, leptin treatment increased the levels of pERK1/2, pCREB, and the downstream gene product BDNF, which were reversed by the MEK inhibitor PD98059. Collectively, these data provide evidence that leptin prevents the degeneration of dopaminergic neurons by 6-OHDA and may prove useful in the treatment of Parkinson disease.
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PMID:Leptin protects against 6-hydroxydopamine-induced dopaminergic cell death via mitogen-activated protein kinase signaling. 1789 42

3-methyl-6-chloro-7,8-hydroxy-1-(3-methylphenyl)-2,3,4,5-tetrahydro-1H-3-benzazepine (SKF83959), a selective agonist for the putative phosphatidylinositol (PI)-linked dopamine receptor (DAR), has been shown to possess potent anti-Parkinson disease effects but produces less dyskinesia and motor fluctuation that are frequently observed in Parkinson disease drug therapies. The present study was designed to detect the neuroprotection of SKF83959 and its potential mechanism for the effect in cultured rat cortical cells. The presence of SKF83959 with a dose range of 0.1-30 micromol/L improved H2O2-reduced cell viability in a dose-dependent manner. The anti-apoptotic action of SKF83959 was partially abolished by pre-application of the D1 antagonist SCH23390 (30 micromol/L) and the PI 3-kinase (PI 3-K) inhibitor LY294002 but not by the MEK1/2 inhibitor PD98059 (30 micromol/L). Moreover, SKF83959 treatment significantly inhibited H2O2-activated glycogen synthase kinase-3beta (GSK-3beta) which was associated with the drug's neuroprotective effect, but this inhibition was attenuated by SCH23390 and a selective PI 3-K inhibitor. Moreover, the application of either SKF83959 or a pharmacological inhibitor of GSK-3beta attenuated the inhibition by H2O2 on the expression of inducible NO synthase and production of NO. This indicates that D1-like receptor, presumably PI-linked D1 receptor, -mediated alteration of PI 3-K/Akt/GSK-3beta pathway is involved in the neuroprotection by SKF83959. In addition, SKF83959 also effectively decreased the level of the lipid peroxidation and increased the activity of GSH-peroxidase altered by H2O2. These results suggest that SKF83959 exerts its neuroprotective effect through both receptor-dependent and independent mechanisms: Inhibition of GSK-3beta and consequently increasing the expression of inducible NO synthase via putative PI-linked DAR; and its anti-oxidative activity which is independent of DAR.
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PMID:Neuroprotective effects of atypical D1 receptor agonist SKF83959 are mediated via D1 receptor-dependent inhibition of glycogen synthase kinase-3 beta and a receptor-independent anti-oxidative action. 1800 41


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