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)

We have reported a case of autosomal recessive juvenile parkinsonism PARK6 with a 30-year history. She developed tremor of right lower limb at the age of 23. At the age of 28, she received a clinical diagnosis of early-onset Parkinson's disease. She showed clinical improvements by the treatment with trihexyphenidyl, but symptoms showed slow progression over the subsequent years. L-DOPA therapy was introduced at the age of 42, and five years later, L-DOPA-induced dyskinesia developed. Dystonia, diurnal fluctuation and sleep benefit were absent. She carried a homozygous missense mutation in PINK1 gene, and was diagnosed as PARK6. The brain MRI did not show apparent abnormality. 18F-FDG-positron emission topography (PET) displayed normal uptake in the brain, suggesting normal glucose metabolism. PET imaging with a dopamine D2 receptor ligand 11C-raclopride revealed that postsynaptic 11C-raclopride uptake was normal in the bilateral putamen. After the introduction of pramipexisol, she showed clinical improvements. L-DOPA-induced dyskinesia disappeared with the gradual tapering and withdrawal of L-DOPA. In this PARK6 case, postsynaptic D2 receptors of the nigro-striatal dopaminergic neurons were thought to be maintained despite a long disease history.
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PMID:[Case of a 30-year history of PARK6 --findings from functional imaging of the brain]. 1904 50

An altered glutamatergic input at corticostriatal synapses has been shown in experimental models of Parkinson's disease (PD). In the present work, we analyzed the membrane and synaptic responses of striatal neurons to metabotropic glutamate (mGlu) receptor activation in two different mouse models of inherited PD, linked to mutations in PINK1 or Parkin genes. Both in PINK1 and Parkin knockout ((-/-)) mice, activation of group I mGlu receptors by 3,5-DHPG caused a membrane depolarization coupled to an increase in firing frequency in striatal cholinergic interneurons that was comparable to the response observed in the respective wild-type (WT) interneurons. The sensitivity to group II and III mGlu receptors was tested on cortically-evoked excitatory postsynaptic potentials (EPSPs) recorded from medium spiny neurons (MSNs). Both LY379268 and L-AP4, agonists for group II and III, respectively, had no effect on intrinsic membrane properties, but dose-dependently reduced the amplitude of corticostriatal EPSPs. However, both in PINK1(-/-) and Parkin(-/-) mice, LY379268, but not L-AP4, exhibited a greater potency as compared to WT in depressing EPSP amplitude. Accordingly, the dose-response curve for the response to LY379268 in both knockout mice was shifted leftward. Moreover, consistent with a presynaptic site of action, both LY379268 and L-AP4 increased the paired-pulse ratio either in PINK1(-/-) and Parkin(-/-) or in WT mice. Acute pretreatment with L-dopa did not rescue the enhanced sensitivity to LY379268. Together, these results suggest that the selective increase in sensitivity of striatal group II mGlu receptors represents an adaptive change in mice in which an altered dopamine metabolism has been documented.
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PMID:Enhanced sensitivity to group II mGlu receptor activation at corticostriatal synapses in mice lacking the familial parkinsonism-linked genes PINK1 or Parkin. 1907 Nov 14

Parkinson's disease (PD) is a common, disabling, neurodegenerative disease. Our knowledge of the molecular events leading to PD is being greatly enhanced by the study of relatively rare familial form of the disease. Nevertheless, the pathways leading from the genetic mutations to nigral cell degeneration and the other features in PD remain poorly understood. The identification of PINK1, a mitochondrial putative protein kinase, has helped understand the pathophysiology of mitochondria and their potential role in PD. Mutations in PINK1 are associated with the PARK6 autosomal recessive, early-onset, PD-susceptibility locus. Point mutations in another mitochondrial protein, HtrA2, are a susceptibility factor for PD (PARK13 locus). We report here the results of investigations into the interactors and pathways of these two mitochondrial molecules (PINK1 and HtrA2) in a range of models and human PD tissue.
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PMID:What have PINK1 and HtrA2 genes told us about the role of mitochondria in Parkinson's disease? 1907 28

Recently, a mutation in the mitochondrial protease Omi/HtrA2, G399S, was found in sporadic Parkinson's disease (PD) patients, leading to the designation of Omi/HtrA2 as PD locus 13 (PARK13). G399S reportedly results in reduced Omi protease activity. In vitro studies have suggested that Omi/HtrA2 acts downstream of PINK1, mutations in which mediate recessive forms of PD. We, as well as other, have previously shown that the Drosophila homologs of the familial PD genes, PINK1 (PARK6) and PARKIN (PARK2), function in a common genetic pathway to regulate mitochondrial integrity and dynamics. Whether Omi/HtrA2 regulates mitochondrial integrity and whether it acts downstream of PINK1 in vivo remain to be explored. Here, we show that Omi/HtrA2 null mutants in Drosophila, in contrast to pink1 or parkin null mutants, do not show mitochondrial morphological defects. Extensive genetic interaction studies do not provide support for models in which Omi/HtrA2 functions in the same genetic pathway as pink1, or carries out partially redundant functions with pink1, at least with respect to regulation of mitochondrial integrity and dynamics. Furthermore, Omi/HtrA2 G399S retains significant, if not full, function of Omi/HtrA2, compared with expression of protease-compromised versions of the protein. In light of recent findings showing that G399S can be found at comparable frequencies in PD patients and healthy controls, we do not favor a hypothesis in which Omi/HtrA2 plays an essential role in PD pathogenesis, at least with respect to regulation of mitochondrial integrity in the pink1/parkin pathway.
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PMID:Loss-of-function analysis suggests that Omi/HtrA2 is not an essential component of the PINK1/PARKIN pathway in vivo. 1911 85

Over the last few years, genetic findings have changed our views on Parkinson's disease (PD), as mutations in a growing number of genes are found to cause monogenic forms of the disorder. Point mutations in the gene for alpha-synuclein, as well as duplications and triplications of the wild-type gene cause a dominant form of PD in rare families, pointing towards mishandling of this protein as a crucial step in the molecular pathogenesis of the disorder. Mutations in the gene for leucine-rich repeat kinase 2 (LRRK2) have recently been identified as a much more common cause for dominant PD, while mutations in the parkin gene, in DJ-1, PINK1 and ATP13A2 all cause autosomal-recessive parkinsonism of early onset. Mutations in recessive genes probably are pathogenic through loss-of-function mechanisms, suggesting that their wild-type products protect dopaminergic cells against a variety of insults. Evidence is emerging that at least some of these genes may play a direct role in the etiology of the common sporadic form of PD. Further, it is likely that the cellular pathways identified in rare monogenic variants of the disease also shed light on the molecular pathogenesis in typical sporadic PD.
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PMID:Mendelian forms of Parkinson's disease. 1916 33

The aim of the study was to evaluate the frequency and to perform phenotypic and genotypic characterization of familial Parkinsonism and early onset Parkinson's disease (EOPD) in a Brazilian movement disorder unit. We performed a standardized clinical assessment of patients followed by sequencing of PRKN, PINK1 in EOPD cases and SNCA, LRRK2 in familial Parkinsonism individuals. During the period of study (January through December, 2006), we examined 575 consecutive patients of whom 226 (39.3%) met the diagnosis of Parkinsonism and idiopathic Parkinson's disease (IPD) was diagnosed in 202 of the latter. Of the IPD cases, 45 (22.3%) had EOPD. The age at onset in the EOPD cases (n = 45) was 34.8 +/- 5.4 years (mean +/- standard deviation). The age at onset in the familial late-onset PD patients (n = 8) was 52.3 +/- 12.2 years. In the early onset cases, we identified five known mutations in PRKN, two single heterozygous and three compound heterozygous (P153R, T240M, 255Adel, W54R, V3I); in addition, we identified one novel mutation in PINK1 (homozygous deletion of exon 7). In the familial cases (late onset), 1 patient had a novel LRRK2 variant, Q923H, but no SNCA mutations were identified. We have demonstrated that EOPD accounts for a high frequency of IPD cases in our tertiary referral center. PRKN was the most commonly mutated gene, but we also identified a novel mutation in PINK1 and a novel variant in LRRK2.
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PMID:Familial Parkinsonism and early onset Parkinson's disease in a Brazilian movement disorders clinic: phenotypic characterization and frequency of SNCA, PRKN, PINK1, and LRRK2 mutations. 1920 68

PARK2 and PINK1 gene mutations are involved in recessive early onset Parkinson's disease (EOPD). In order to determine the causative mutations in three affected sibs from a consanguineous Sudanese family with EOPD, multiplex ligation-dependent probe amplification was performed and revealed that the patients were homozygous for a deletion of PINK1 exons 4 to 8. Breakpoint analysis revealed a complex rearrangement combining a large deletion and the insertion of a sequence duplicated from the DDOST gene intron 2, located near the PINK1 gene. As breakpoint sequences displayed only three base pairs of homology, this rearrangement may result from Fork Stalling and Template Switching mechanism. This third large rearrangement of PINK1 enlarges the mutation spectrum and, together with recent published data in Tunisian patients with EOPD, points out that PINK1 gene analysis, including search for large rearrangement, should be considered in early onset recessive PD patients, particularly those from Arab origin.
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PMID:A new complex homozygous large rearrangement of the PINK1 gene in a Sudanese family with early onset Parkinson's disease. 1921 5

Recent whole genome association studies provided little evidence that polymorphisms at the familial Parkinsonism loci influence the risk for Parkinson's disease (PD). However, these studies are not designed to detect the types of subtle effects that common variants may impose. Here, we use an alternative targeted candidate gene approach to examine common variation in 11 genes related to familial Parkinsonism. PD cases (n = 331) and unaffected control subjects (n = 296) were recruited from three specialist movement disorder clinics in Brisbane, Australia and the Australian Electoral Roll. Common genetic variables (76 SNPs and 1 STR) were assessed in all subjects and haplotype, genotype, and allele associations explored. Modest associations (uncorrected P < 0.05) were observed for common variants around SNCA, UCHL1, MAPT, and LRRK2 although none were of sufficient magnitude to survive strict statistical corrections for multiple comparisons. No associations were seen for PRKN, PINK1, GBA, ATP13A2, HTRA2, NR4A2, and DJ1. Our findings suggest that common genetic variables of selected PD-related loci contribute modestly to PD risk in Australians.
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PMID:Do polymorphisms in the familial Parkinsonism genes contribute to risk for sporadic Parkinson's disease? 1922 17

Parkinson disease (PD) is characterized by the presence of ubiquitylated inclusions and the death of dopaminergic neurons. Seven in absentia homolog (SIAH) is a ubiquitin-ligase that ubiquitylates alpha-synuclein and synphilin-1 and is present in Lewy bodies of PD patients. Understanding the mechanisms that regulate the ubiquitylation of PD-related proteins might shed light on the events involved in the formation of Lewy bodies and death of neurons. We show in this study that the recently described synphilin-1 isoform, synphilin-1A, interacts in vitro and in vivo with the ubiquitin-protein isopeptide ligase SIAH and regulates its activity toward alpha-synuclein and synphilin-1. SIAH promotes limited ubiquitylation of synphilin-1A that does not lead to its degradation by the proteasome. SIAH also increases the formation of synphilin-1A inclusions in the presence of proteasome inhibitors, supporting the participation of ubiquitylated synphilin-1A in the formation of Lewy body-like inclusions. Synphilin-1A/SIAH inclusions recruit PD-related proteins, such as alpha-synuclein, synphilin-1, Parkin, PINK1, and UCH-L1. We found that synphilin-1A robustly increases the steady-state levels of SIAH by decreasing its auto-ubiquitylation and degradation. In addition, synphilin-1A blocks the ubiquitylation and degradation of the SIAH substrates synphilin-1 and deleted in colon cancer protein. Furthermore, synphilin-1A strongly decreases the monoubiquitylation of alpha-synuclein by SIAH and the formation of alpha-synuclein inclusions, supporting a role for monoubiquitylation in alpha-synuclein inclusion formation. Our results suggest a novel function for synphilin-1A as a regulator of SIAH activity and formation of Lewy body-like inclusions.
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PMID:Synphilin-1A inhibits seven in absentia homolog (SIAH) and modulates alpha-synuclein monoubiquitylation and inclusion formation. 1922 63

Protein aggregation as a result of misfolding is a common theme underlying neurodegenerative diseases. In Parkinson's disease (PD), research on protein misfolding and aggregation has taken center stage following the association of alpha-synuclein gene mutations with familial forms of the disease, and importantly, the identification of the protein as a major component of Lewy bodies, a pathological hallmark of PD. Fueling this excitement is the subsequent identification of another PD-linked gene, parkin, as a ubiquitin ligase associated with the proteasome, a major intracellular protein degradation machinery that destroys unwanted, albeit mainly soluble, proteins. Notably, a role for parkin in the clearance of insoluble protein aggregates via macroautophagy has also been implicated by more recent studies. Paradoxically, like alpha-synuclein, parkin is also prone to misfolding, especially in the presence of age-related stress. Similarly, protein misfolding can also affect the function of other key PD-linked genes such as DJ-1, PINK1, and perhaps also LRRK2. Here, we discuss the role of protein misfolding and aggregation in PD, and how impairments of the various cellular protein quality systems could precipitate these events and lead to neuronal demise. Towards the end of our discussion, we also revisited the role of Lewy body formation in PD.
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PMID:Protein misfolding and aggregation in Parkinson's disease. 1924 38


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