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)

6-Hydroxydopamine (6-OHDA) is widely used to produce animal models of Parkinson's disease (PD) by selectively destroying the nigro-striatal dopaminergic systems, but selective toxicity of 6-OHDA towards dopaminergic cells in vitro remains controversial. Mutant (A30P and A53T) alpha-synuclein isoforms cause increased vulnerability of cells towards various toxic insults and enhance dopamine transporter (DAT)-mediated toxicity of the selective dopaminergic neurotoxin and mitochondrial complex I inhibitor MPP(+) in vitro. Here we extend our recent studies on DAT-mediated toxicity to elucidate the mechanisms involved in selective dopaminergic toxicity of 6-OHDA. We studied the cytotoxicity as well as the toxic mechanisms of 6-OHDA in human embryonic kidney HEK-293 cells ectopically co-expressing mutant alpha-synucleins and the human DAT protein. 6-OHDA showed half-maximal toxic concentration (TC(50)) of 88 microM in HEK-hDAT cells without alpha-synuclein expression after 24 h, whereas the TC(50) values significantly decreased to 58 and 39 microM by expression of A30P and A53T alpha-synuclein, respectively. alpha-Synuclein expression did not affect 6-OHDA toxicity in HEK-293 cells not expressing the DAT. Analysis of intracellular parameters of cellular energy metabolism revealed that the co-expression of mutant alpha-synucleins in HEK-hDAT cells accelerates the reduction of intracellular net ATP levels and ATP/ADP ratios induced by 6-OHDA. Uptake function of the DAT was not altered by expression of alpha-synuclein isoforms. Our data suggest a mechanism of 6-OHDA-induced dopaminergic toxicity involving an interaction of mutant alpha-synucleins with the DAT molecule and subsequent acceleration of cellular energy depletion that might be relevant for the pathogenesis of PD.
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PMID:Dopamine transporter-mediated cytotoxicity of 6-hydroxydopamine in vitro depends on expression of mutant alpha-synucleins related to Parkinson's disease. 1640 46

beta-Carbolines structurally related to the selective dopaminergic neurotoxin 1-methyl-4- phenylpyridinium (MPP(+)) may contribute to dopaminergic neurodegeneration in Parkinson's disease. The chloral-derived mammalian alkaloid derivative 1-trichloromethyl-1,2,3,4-tetrahydro-beta-carboline (TaClo) is formed endogenously by a Pictet-Spengler condensation from the biogenic amine tryptamine (Ta) and the hypnotic aldehyde chloral (Clo). Here we examine the dopaminergic toxicity of TaClo and related compounds by testing their differential cytotoxicities in dopaminergic SH-SY5Y and non-dopaminergic murine Neuro2A neuroblastoma cell lines as well as in heterologous expression systems of the dopamine transporter (DAT) using both HEK-293 and Neuro2A cells. All TaClo derivatives showed significant cytotoxicity in all cell lines after 72 hours with the following rank order of toxic potency: 1-Tribromomethyl-1,2,3,4-tetrahydro-beta-carboline (TaBro) > TaClo > MPP(+) > 1,2,3,4-tetrahydro-beta-carboline (THbetaC) > 2[N]-methyl-TaClo > 2[N]-methyl-THbetaC. In contrast to MPP(+), there was no selectivity towards dopaminergic cells or cells ectopically expressing the DAT in vitro. Our results suggest that TaClo and related analogs are strong cytotoxins without selectivity towards dopaminergic cells.
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PMID:Cytotoxicity of chloral-derived beta-carbolines is not specific towards neuronal nor dopaminergic cells. 1686 95

It has been suggested that L-DOPA-induced hyperhomocysteinemia can increase the risk of stroke, heart disease, and dementia and is an additional pathogenetic factor involved in the progression of Parkinson's disease. In Chinese hamster ovary (CHO) cells stably cotransfected with adenosine A(2A) and dopamine D2 receptors, homocysteine selectively decreased the ability of D2 receptor stimulation to internalize adenosine A(2A)-dopamine D2 receptor complexes. Radioligand-binding experiments in the same cell line demonstrated that homocysteine acts as an allosteric D2 receptor antagonist, by selectively reducing the affinity of D2 receptors for agonists but not for antagonists. Mass spectrometric analysis showed that, by means of an arginine (Arg)-thiol electrostatic interaction, homocysteine forms noncovalent complexes with the two Arg-rich epitopes of the third intracellular loop of the D2 receptor, one of them involved in A(2A)-D2 receptor heteromerization. However, homocysteine was unable to prevent or disrupt A(2A)-D2 receptor heteromerization, as demonstrated with Fluorescence Resonance Energy Transfer (FRET) experiments in stably cotransfected HEK cells. The present results could have implications for Parkinson's disease.
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PMID:Allosteric modulation of dopamine D2 receptors by homocysteine. 1708 Oct 59

The C-terminus Hsp70 interacting protein (CHIP) has dual function as both co-chaperone and ubiquitin ligase. CHIP is increasingly implicated in the biology of polyglutamine expansion disorders, Parkinson's disease and tau protein in Alzheimer's disease. We investigated the involvement of CHIP in the metabolism of the beta-amyloid precursor protein and its derivative beta-amyloid (Abeta). Using immunoprecipitation, fluorescence localization and crosslinking methods, endogenous CHIP and betaAPP interact in brain and cultured skeletal myotubes as well as when they are expressed in stable HEK cell lines. Their interaction is confined to Golgi and ER compartments. In the presence of the proteasome inhibitor with MG132, endogenous and expressed betaAPP levels are significantly increased and accordingly, the interaction with CHIP enhanced. Concurrently, levels of Hsp70 were most consistently induced by proteasome inhibition among the various heat shock proteins (HSPs) tested. Thus, complexes of CHIP, Hsp70 and holo-betaAPP (as well as C-terminal fragments) were stabilized by the action of MG132. Moreover, CHIP itself is shown to both increase cellular holo-betaAPP levels and protect it from oxidative stress and degradation. Interestingly, CHIP also promotes the association of ubiquitin with betaAPP, implying that a smaller pool of betaAPP is destined for proteasomal processing. In neuronal cultures, CHIP and Hsp70/90 expression reduce steady-state cellular Abeta levels and hasten its degradation in pulse-chase experiments. The functional significance of CHIP and HSP interactions, especially with Hsp70, was tested using siRNA and in neuronal cells where protection from Abeta-induced toxicity is shown. We conclude that CHIP, as a bimolecular switch, interacts with HSP to stabilize normal holo-betaAPP on the one hand while also assisting in the ubiquitination of a subpopulation of betaAPP molecules that are destined for proteasome degradation. CHIP also hastens the clearance of Abeta in a manner consistent with its known neuroprotective properties.
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PMID:CHIP and HSPs interact with beta-APP in a proteasome-dependent manner and influence Abeta metabolism. 1731 85

Normal Cdk5 activity, conferred mainly by association with its primary activator p35, is critical for normal function of the cell and must be tightly regulated. During neurotoxicity, p35 is cleaved to form p25, which becomes a potent and mislocalized hyperactivator of Cdk5, resulting in a deregulation of Cdk5 activity. p25 levels have been found to be elevated in Alzheimer's disease (AD) brain and overexpression of p25 in a transgenic mouse results in the formation of phosphorylated tau, neurofibrillary tangles and cognitive deficits that are pathological hallmarks of AD. p25/Cdk5 also hyperphosphorylates neurofilament proteins that constitute pathological hallmarks found in Parkinson's disease and amyotrophic lateral sclerosis. The selective targeting of p25/Cdk5 activity without affecting p35/Cdk5 activity has been unsuccessful. In this review we detail our recent studies of selective p25/Cdk5 inhibition without affecting p35/Cdk5 or mitotic Cdk activities. We found that a further truncation of p25 to yield a Cdk5 inhibitory peptide (CIP) can specifically inhibit p25/Cdk5 activity in transfected HEK cells and primary cortical neurons. CIP was able to reduce tau hyperphosphorylation and neuronal death induced caused by p25/Cdk5 and further studies with CIP may develop a specific Cdk5 inhibition strategy in the treatment of neurodegeneration.
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PMID:Peptides derived from Cdk5 activator p35, specifically inhibit deregulated activity of Cdk5. 1752 58

In this paper, we describe the development of a fluorogenic substrate for 17beta-hydroxysteroid-dehydrogenase type 10 (17beta-HSD10), which is a multifunctional metabolic enzyme fulfilling several metabolic roles (beta-oxidation of fatty acids, catabolism of isoleucine, and metabolism of steroids). In recent years, it has emerged as an important stress and pathological marker in neurons and glial cells (expression down-regulation in Parkinson's disease, up-regulation and association with beta-amyloid peptide in Alzheimer's disease). Through the iterative molecular design and chemical synthesis described herein, compound 1 was developed, which possesses all required properties for a selective optical reporter substrate: alcohol-ketone optical switching, the ability to function as a good enzyme substrate (expressed in kinetic parameters), cell permeability, and cell retention. Probe 1 provides a blue-to-green/yellow bright switch and enables non-invasive, real-time imaging of 17beta-HSD10 in live human cells. The selectivity of reporter 1 was established by the quantitative correlation of metabolic activity to protein expression in human kidney cell line HEK-293T.
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PMID:Harnessing functional plasticity of enzymes: a fluorogenic probe for imaging 17beta-HSD10 dehydrogenase, an enzyme involved in Alzheimer's and Parkinson's diseases. 1795 19

In the current report, we extend the SAR study on our hybrid structure 7-{[2-(4-phenyl-piperazin-1-yl)ethyl]propylamino}-5,6,7,8-tetrahydronaphthalen-2-ol further to include heterocyclic bioisosteric analogues. Binding assays were carried out with HEK-293 cells expressing either D2 or D3 receptors with tritiated spiperone to evaluate inhibition constants (Ki). Functional activity of selected compounds in stimulating GTPgammaS binding was assessed with CHO cells expressing human D2 receptors and AtT-20 cells expressing human D3 receptors. The highest binding affinity and selectivity for D3 receptors were exhibited by (-)-34 (Ki=0.92 nM and D2/D3=253). In the functional GTPgammaS binding assay, (-)-34 exhibited full agonist activity with picomolar affinity for D3 receptor with high selectivity (EC50=0.08 nM and D2/D3=248). In the in vivo rotational study, (-)-34 exhibited potent rotational activity in 6-OH-DA unilaterally lesioned rats with long duration of action, which indicates its potential application in neuroprotective treatment of Parkinson's disease.
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PMID:Bioisosteric heterocyclic versions of 7-{[2-(4-phenyl-piperazin-1-yl)ethyl]propylamino}-5,6,7,8-tetrahydronaphthalen-2-ol: identification of highly potent and selective agonists for dopamine D3 receptor with potent in vivo activity. 1841 82

Low voltage activation of Ca(V)1.3 L-type Ca(2+) channels controls excitability in sensory cells and central neurons as well as sinoatrial node pacemaking. Ca(V)1.3-mediated pacemaking determines neuronal vulnerability of dopaminergic striatal neurons affected in Parkinson disease. We have previously found that in Ca(V)1.4 L-type Ca(2+) channels, activation, voltage, and calcium-dependent inactivation are controlled by an intrinsic distal C-terminal modulator. Because alternative splicing in the Ca(V)1.3 alpha1 subunit C terminus gives rise to a long (Ca(V)1.3(42)) and a short form (Ca(V)1.3(42A)), we investigated if a C-terminal modulatory mechanism also controls Ca(V)1.3 gating. The biophysical properties of both splice variants were compared after heterologous expression together with beta3 and alpha2delta1 subunits in HEK-293 cells. Activation of calcium current through Ca(V)1.3(42A) channels was more pronounced at negative voltages, and inactivation was faster because of enhanced calcium-dependent inactivation. By investigating several Ca(V)1.3 channel truncations, we restricted the modulator activity to the last 116 amino acids of the C terminus. The resulting Ca(V)1.3(DeltaC116) channels showed gating properties similar to Ca(V)1.3(42A) that were reverted by co-expression of the corresponding C-terminal peptide C(116). Fluorescence resonance energy transfer experiments confirmed an intramolecular protein interaction in the C terminus of Ca(V)1.3 channels that also modulates calmodulin binding. These experiments revealed a novel mechanism of channel modulation enabling cells to tightly control Ca(V)1.3 channel activity by alternative splicing. The absence of the C-terminal modulator in short splice forms facilitates Ca(V)1.3 channel activation at lower voltages expected to favor Ca(V)1.3 activity at threshold voltages as required for modulation of neuronal firing behavior and sinoatrial node pacemaking.
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PMID:Modulation of voltage- and Ca2+-dependent gating of CaV1.3 L-type calcium channels by alternative splicing of a C-terminal regulatory domain. 1848 79

Alpha-synuclein (alpha-syn) is implicated in the pathogenesis of Parkinson's disease (PD). Mutations in alpha-syn gene or alpha-syn locus (SNCA) triplication are associated with mitochondrial abnormalities and early onset of familial PD. The goals of the present study were to examine whether alpha-syn is localized in the mitochondria of alpha-syn overexpressing cells (HEK-syn cells); and whether alpha-syn overexpression causes cells to be more vulnerable to mitochondrial toxin, rotenone. Western blotting and confocal microscopy techniques were employed to assess localization of alpha-syn in the mitochondria of HEK-293 cells that were stably transfected with human wild-type alpha-syn. The results demonstrated that the mitochondrial fractions that were isolated from HEK-syn cells showed the presence of alpha-syn, whereas, no alpha-syn was detected in the mitochondrial fractions of control HEK cells. The mitochondria of HEK-syn cells were found to be more susceptible to rotenone-induced toxicity when compared to control HEK cells. The intracellular ATP levels were significantly decreased in HEK-syn cells in response to sub toxic concentrations of rotenone. These results suggest that under overexpression conditions, alpha-syn may translocate to mitochondria and cause enhanced toxicity in response to sub toxic concentrations of mitochondrial toxins. This study has implications to the pathogenesis of familial PD where alpha-syn overexpression is mainly involved.
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PMID:Mitochondrial localization of alpha-synuclein protein in alpha-synuclein overexpressing cells. 1851 18

Adenosine A2A receptors belong to the heptaspanning membrane receptors family A, also known as G protein-coupled receptors. In human brain they are highly expressed in striatum, where they co-exist and co-function with adenosine A1, glutamate mGlu5 and dopamine D2 receptors. As glutaminergic neurotransmission modulators in GABAergic enkephalinergic neurons, adenosine A2A receptors are attractive targets for new, alternative therapies of neurodegenerative disorders, like Parkinson's disease and Huntington's disease. The aim of the research was to obtained fluorescently tagged adenosine A2A receptors. Gene encoding human adenosine A2A receptor was inserted into plasmid pEYFP-N1, bearing enhanced yellow fluorescent protein (EYFP). The construct was expressed in HEK 293 cells. Fluorescence was observed by flow cytometry and epifluorescence microscopy. Functional ligand binding properties were investigated by saturation binding analysis of adenosine A2A receptors specific agonist [3H] CGS 21680.
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PMID:Flow cytometry application for studies on adenosine A2A receptors expression. 1853 75


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