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)

Oxidative stress links diverse neuropathological conditions that include stroke, Parkinson's disease, and Alzheimer's disease and has been modeled in vitro with various paradigms that lead to neuronal cell death following the increased accumulation of reactive oxygen species. For example, immortalized neurons and immature primary cortical neurons undergo cell death in response to depletion of the antioxidant glutathione, which can be elicited by administration of glutamate at high concentrations. We have demonstrated previously that this glutamate-induced oxidative toxicity requires activation of the mitogen-activated protein kinase member ERK1/2, but the mechanisms by which this activation takes place in oxidatively stressed neurons are still not fully known. In this study, we demonstrate that during oxidative stress, ERK-directed phosphatases of both the serine/threonine- and tyrosine-directed classes are selectively and reversibly inhibited via a mechanism that is dependent upon the oxidation of cysteine thiols. Furthermore, the impact of ERK-directed phosphatases on ERK1/2 activation and oxidative toxicity in neurons was tested in a neuronal cell line and in primary cortical cultures. Overexpression of the highly ERK-specific phosphatase MKP3 and its catalytic mutant, MKP3 C293S, were neuroprotective in transiently transfected HT22 cells and primary neurons. The neuroprotective effect of the MKP3 C293S mutant, which enhances ERK1/2 phosphorylation but blocks its nuclear translocation, demonstrates the necessity for active ERK1/2 nuclear localization for oxidative toxicity in neurons. Together, these data implicate the inhibition of endogenous ERK-directed phosphatases as a mechanism that leads to aberrant ERK1/2 activation and nuclear accumulation during oxidative toxicity in neurons.
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PMID:Reversible oxidation of ERK-directed protein phosphatases drives oxidative toxicity in neurons. 1557 67

Nigrostriatal dopamine depletion disrupts striatal medium spiny neuron morphology in Parkinson's disease and modulates striatal synaptic plasticity in animal models of parkinsonism. We demonstrate that long-term nigrostriatal dopamine depletion in the rat induces evolving changes in the phosphorylation of striatal proteins critical for synaptic plasticity. Dopamine depletion increased the phosphorylation of the alpha isoform of calcium-calmodulin-dependent protein kinase II (CaMKIIalpha) at Thr286, a site associated with enhanced autonomous kinase activity, but did not alter total levels of CaMKIIalpha or other synaptic proteins. Dopamine depletion decreased CaMKIIalpha levels in postsynaptic density-enriched fractions without significant changes in other proteins. The activity of protein phosphatase 1 (PP1), a postsynaptic phosphatase that dephosphorylates CaMKII, is regulated by DARPP-32 (dopamine- and cAMP-regulated phosphoprotein of 32 kDa). Dopamine depletion had no effect on DARPP-32 phosphorylation at Thr34, but increased DARPP-32 phosphorylation at Thr75. Levodopa administration reversed the increased phosphorylation of both CaMKIIalpha and DARPP-32. Normal ageing increased the levels of PP1(gamma1 isoform) but decreased levels of the PP1gamma1-targeting proteins spinophilin and neurabin. Elevated phosphorylations of CaMKIIalpha and DARPP-32 were maintained for up to 20 months after dopamine depletion. However, phosphorylation of the CaMKII-PP1 substrate, Ser831 in the glutamate receptor GluR1 subunit, was increased only after sustained (9-20 months) dopamine depletion. Interaction of ageing-related changes in PP1 with the dopamine depletion-induced changes in CaMKIIalpha may account for enhanced GluR1 phosphorylation only after long-term dopamine depletion. These evolving changes may impact striatal synaptic plasticity, Parkinson's disease progression and the changing efficacy and side-effects associated with dopamine replacement therapy.
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PMID:Dopamine depletion alters phosphorylation of striatal proteins in a model of Parkinsonism. 1602 14

Oxidative stress plays crucial role in the pathogenesis of neurodegenerative diseases. However, the precise mechanism for an increased production of reactive oxygen species (ROS) under pathological conditions is not yet fully understood. We have recently demonstrated an implication of phosphatase and tensin homologue deleted on chromosome 10 (PTEN), a tumor suppressor, in ROS generation and neuronal apoptosis induced by staurosporine. These findings raised further interest whether PTEN functions as a common mediator of oxidative stress in neurodegenerative processes. To address this issue, neural cells were exposed to oxygen-glucose deprivation (OGD) and to the neurotoxin 1-methyl-4-phenylpyridinium iodide (MPP(+)), which mimic cerebral ischemia and Parkinson's disease, respectively. OGD for 4 h followed by 16 h of reoxygenation or incubation with MPP(+) (250 microM) for 48 h induced 33% and 45% neuronal death in rat hippocampal and in human dopaminergic SH-SY5Y neurons, respectively, accompanied by a gradual increase in the intracellular level of ROS. The increase in ROS by OGD and by MPP(+) did not cause oxidative inactivation of PTEN and thus, PTEN remains constitutively active. In support, the protein level of PTEN was not reduced in both cell cultures after challenging with OGD or MPP(+). Importantly, the elevated intracellular ROS levels and the neuronal death caused by OGD or by MPP(+) toxicity were significantly inhibited when PTEN was downregulated by a specific antisense oligonucleotide or by siRNA. Because SOD2 protein level is not altered either by knockdown of PTEN nor by an inhibition of the PI3K/Akt signalling, we suggest that SOD2 do not contribute to the pathomechanism of oxidative stress induced by PTEN or by inhibiting the related Akt signalling. The present study highlights PTEN as a crucial and common mediator of ROS generation and neuronal death and suggests that PTEN could become a potential therapeutic target for interfering with neurodegeneration.
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PMID:Implication of PTEN in production of reactive oxygen species and neuronal death in in vitro models of stroke and Parkinson's disease. 1716 62

Dopamine receptor signaling exhibits prominent plasticity that is important for the pathogenesis of both addictive and movement disorders. Psychoactive stimulants that activate the dopamine D(1) receptor (Drd1a) induce the rapid phosphorylation and activation of extracellular signal-regulated kinase 1/2 (ERK1/2) in neurons of the nucleus accumbens and ventral striatum. This response is known to be dependent on the phosphatase inhibitor dopamine- and cAMP-regulated phosphoprotein-32 (DARPP-32) and appears critical for the sensitization of Drd1a responses that contributes to addiction. Loss of dopamine input to the striatum, as in models of Parkinson's disease (PD), also results in a sensitization of responses to dopamine agonists that is manifest by increased activation of ERK1/2 in the dorsal striatum. Here, we test whether DARPP-32 is required for sensitization of Drd1a responses in a PD model. In the normal dorsal striatum, there is minimal Drd1a-mediated activation of ERK1/2; however, in the PD model there is robust Drd1a-mediated activation of ERK1/2. In both wild-type and DARPP-32 knock-out mice, Drd1a robustly induces pERK1/2 throughout the dopamine-depleted striatum. These findings indicate that Drd1a sensitization relevant for PD occurs by a novel mechanism that does not require DARPP-32.
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PMID:Differences between dorsal and ventral striatum in Drd1a dopamine receptor coupling of dopamine- and cAMP-regulated phosphoprotein-32 to activation of extracellular signal-regulated kinase. 1861 80

Parkinson's disease (PD) is the second most prevalent neurodegenerative disorder in the Western world. PTEN (phosphatase/tensin homolog on chromosome 10)-induced putative kinase 1 (PINK1), a putative kinase that is mutated in autosomal recessive forms of PD, is also implicated in sporadic cases of the disease. Although the mutations appear to result in a loss of function, the roles of this protein and the pathways involved in PINK1 PD are poorly understood. Here, we generated a vertebrate model of PINK1 insufficiency using morpholino oligonucleotide knockdown in zebrafish (Danio rerio). PINK1 knockdown results in a severe developmental phenotype that is rescued by wild-type human PINK1 mRNA. Morphants display a moderate decrease in the numbers of central dopaminergic neurons and alterations of mitochondrial function, including increases in caspase-3 activity and reactive oxygen species (ROS) levels. When the morphants were exposed to several drugs with antioxidant properties, ROS levels were normalized and the associated phenotype improved. In addition, GSK3beta-related mechanisms can account for some of the effects of PINK1 knockdown, as morphant fish show elevated GSK3beta activity and their phenotype is partially abrogated by GSK3beta inhibitors, such as LiCl and SB216763 [3-(2,4-dichlorophenyl)-4-(1-methyl-1H-indol-3-yl)1H-pyrrole-2,5-dione]. This provides new insights into the biology of PINK1 and a possible therapeutic avenue for further investigation.
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PMID:Loss of PINK1 function affects development and results in neurodegeneration in zebrafish. 1870 82

Loss-of-function mutations of phosphatase/tensin homolog deleted on chromosome 10 (PTEN)-induced putative kinase 1 (Pink1) (also known as Park6) identified in familial forms of Parkinson's disease (PD) are associated with compromised mitochondrial function. Emerging data suggest that Pink1 is an essential pro-survival factor that is induced in response to oxidative stress. However, the mechanisms regulating Pink1 expression under stress conditions remain unknown. Forkhead box, subgroup O (FOXO) transcription factors carry out distinct biological functions in response to different extracellular signals. Notably, FOXO factors possess evolutionarily conserved roles in protecting cells from oxidative stress-induced death. Here we report that the FOXO family member FOXO3a controls Pink1 transcription in both mouse and human cells subjected to growth factor deprivation and that this regulation is exerted through evolutionarily conserved FOXO binding elements. Induction of Pink1 by FOXO3a is crucial for survival signals in lymphocytes, as depletion of Pink1 sensitizes these cells to death induced by deprivation of an essential growth factor. Our data reveal that the role of FOXO factors in protecting cells from growth factor deprivation-triggered apoptosis has been underestimated and that FOXOs mediate this protection by transactivating anti-apoptotic effectors like Pink1. Given the essential role of Pink1 in combating cell death, our findings may help to dissect the mechanisms by which FOXO proteins function as anti-oxidative stress factors.
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PMID:FOXO3a-dependent regulation of Pink1 (Park6) mediates survival signaling in response to cytokine deprivation. 1927 13

Parkinson disease (PD) is the most common movement disorder and is characterized by dopaminergic dysfunction. The majority of PD cases are sporadic; however, the discovery of genes linked to rare familial forms of the disease has provided crucial insight into the molecular mechanisms of disease pathogenesis. Multiple genes mediating familial forms of Parkinson's disease (PD) have been identified, such as parkin (PARK2) and phosphatase and tensin homologue deleted on chromosome ten (PTEN)-induced putative kinase 1: PINK1 (PARK6). Here, we showed that Parkin directly interacts with PINK1, but did not bind to pathogenic PINK1 mutants. Parkin, but not its pathogenic mutants, stabilizes PINK1 by interfering with its degradation via the ubiquitin-mediated proteasomal pathway. In addition, the interaction between Parkin and PINK1 resulted in reciprocal reduction of their solubility. Our results indicate that Parkin regulates PINK1 stabilization via direct interaction with PINK1, and operates through a common pathway with PINK1 in the pathogenesis of early-onset PD.
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PMID:Parkin stabilizes PINK1 through direct interaction. 1935 26

striatum of rodents in experimental models of Parkinson's disease. Interestingly, immunohistochemical studies have shown increased levels of PTN expression in the substantia nigra of patients with Parkinson's disease. Since, in other contexts, PTN has been shown to be critical in repair processes in the injured nervous system, the antecedents suggest that PTN could exhibit protective effects in Parkinson's disease. This hypothesis was confirmed when PTN was shown to support survival of dopaminergic neurons and to promote the differentiation of neural stem cells to dopaminergic neurons. These findings suggest a new therapeutic approach in the treatment of Parkinson's disease based on the molecular mechanism of action of PTN. Pleiotrophin receptor, receptor protein tyrosine phosphatase (RPTP) beta/zeta, is found active in monomeric form in neurons and glia within the central nervous system. Pleiotrophin induces dimerization of RPTPbeta/zeta inactivating its phosphatase activity, thus increasing the phosphorylation levels of its substrates such as beta-catenin, Fyn and beta-adducin. These substrates have been shown to be critical for the proliferation of dopaminergic progenitors and the survival and differentiation of dopaminergic neurons. This review summarizes the strong scientific basis to consider blocking RPTPbeta/zeta as a potentially novel therapeutic strategy in the treatment of Parkinson's disease and discusses various starting points to design antagonists of this receptor.
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PMID:Blocking receptor protein tyrosine phosphatase beta/zeta: a potential therapeutic strategy for Parkinson's disease. 1954 69

Tyrosine hydroxylase (TH) is a rate-limiting enzyme for the biosynthesis of catecholamines including dopamine. The relationship between proteasomal dysfunction and the etiology of Parkinson's disease has been suggested, but it is unknown if TH protein is affected by proteasomal dysfunctions. Here, we examined the effect of inhibition of ubiquitin-proteasomal pathway on biochemical characteristics of TH protein in the neuronal cells. Inhibition of 20S or 26S proteasome by proteasome inhibitor I, or MG-132 in NGF-differentiated PC12D cells induced dot-like immunoreactivities with the anti-(40)Ser-phosphorylated TH (p40-TH) antibody. These dots were tightly co-localized with ubiquitin and positive to Thioflavine-S staining. These dot-like immunoreactivities were not obvious when immunostaining was performed against total-TH or choline acetyltransferase. Western blotting analysis showed time-dependent increase of p40-TH in the Triton-insoluble fractions. We also examined the effect of okadaic acid, an inhibitor of protein phosphatase 2A, which is a phosphatase acting on p40-TH. Okadaic acid increased the amount of insoluble p40-TH. These data suggest that p40-TH is prone to be insolubilized and aggregated by dysfunction of an ubiquitin-proteasome system in PC12D cells.
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PMID:Accumulation of phosphorylated tyrosine hydroxylase into insoluble protein aggregates by inhibition of an ubiquitin-proteasome system in PC12D cells. 1975 65

DJ-1 is an oncogene and also a causative gene for a familial form of Parkinson's disease. DJ-1 has multiple functions, including anti-oxidative stress reaction and cysteine 106 (C106) of DJ-1 is an essential amino acid for DJ-1 to exert its function. While increased expression and secretion of DJ-1 into serum in patients with various cancers and regulation of p53 and PTEN by DJ-1 have been reported, the molecular mechanism underlying oncogenicity of DJ-1 is poorly understood. Here, we analyzed the function of DJ-1 in the PI3'K signaling pathway under an oxidative stress condition, focusing on the interaction of DJ-1 with PTEN. We found that both wild-type (wt) and C106S-DJ-1, a substitution mutant of DJ-1, directly bound to PTEN and inhibited PTEN phosphatase activity but that C106S-DJ-1 more strongly inhibited the activity than did wt-DJ-1. When NIH3T3 cells were treated with H2O2, oxidation of C106 of wt-DJ-1 occurred, accompanied by increased binding of wt-DJ-1 to PTEN, decreased PTEN activity and increased phosphorylation of AKT. C106S-DJ-1 transformed cells more strongly than did wt-DJ-1 and the transforming activity of DJ-1 was enhanced by H2O2 treatment of cells in which increased binding of DJ-1 to PTEN and decreased PTEN activity were observed. Furthermore, TOF-MS analysis of the oxidative status of C106 suggested that DJ-1 activity requires the presence of the reduced form of C106, which accounts for >50% of the total form. These results suggest that the oxidative status of DJ-1 regulates PTEN activity, leading to cell proliferation and transformation.
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PMID:Oxidation of DJ-1-dependent cell transformation through direct binding of DJ-1 to PTEN. 1988 56


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