Expression of α‐synuclein mRNA in Parkinson's disease
15 May 2007-Movement Disorders (Wiley Subscription Services, Inc., A Wiley Company)-Vol. 22, Iss: 7, pp 1057-1059
TL;DR: The observation is consistent with the hypothesis that an increase in SNCA expression may be a contributory factor, among other factors, to the development of at least some cases of sporadic PD.
About: This article is published in Movement Disorders.The article was published on 2007-05-15. It has received 10 citations till now. The article focuses on the topics: Parkinson's disease.
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TL;DR: Brain membrane-associated, sodium dodecyl sulfate-soluble alpha-synuclein accumulations in Parkinson's disease and multiple system atrophy are regionally specific, suggesting that these sporadic alpha- Synucleinopathies, unlike familial Parkinsonism-dementia, are not associated with a simple global over-expression of the protein.
Abstract: α-Synuclein is a major component of Lewy bodies and glial cytoplasmic inclusions, pathological hallmarks of idiopathic Parkinson's disease and multiple system atrophy, and it is assumed to be aetiologically involved in these conditions. However, the quantitative status of brain α-synuclein in different Parkinsonian disorders is still unresolved and it is uncertain whether α-synuclein accumulation is restricted to regions of pathology. We compared membrane-associated, sodium dodecyl sulfate-soluble α-synuclein, both the full-length 17 kDa and high molecular weight species, by western blotting in autopsied brain of patients with Parkinson's disease (brainstem-predominant Lewy body disease: n = 9), multiple system atrophy ( n = 11), progressive supranuclear palsy ( n = 16), and of normal controls ( n = 13). Brain of a patient with familial Parkinsonism-dementia due to α-synuclein locus triplication (as positive control) showed increased membrane-associated, sodium dodecyl sulfate-soluble α-synuclein levels with abundant high molecular weight immunoreactivity. In multiple system atrophy, a massive increase in 17 kDa membrane-associated, sodium dodecyl sulfate-soluble α-synuclein was observed in highly pathologically affected regions, including putamen (+1760%, range +625–2900%), substantia nigra [+1000% (+356–1850%)], and white matter of internal capsule [+2210% (+430–6830%)] together with numerous high molecular weight species. Levels of 17 kDa membrane-associated, sodium dodecyl sulfate-soluble α-synuclein were only modestly increased in less affected areas (cerebellar cortex, +95%; caudate, +30%; with both also showing numerous high molecular weight species) and were generally normal in cerebral cortices. In both Parkinson's disease and progressive supranuclear palsy, membrane-associated, sodium dodecyl sulfate-soluble α-synuclein levels were normal in putamen and frontal cortex whereas a trend was observed for variably increased 17 kDa membrane-associated, sodium dodecyl sulfate-soluble α-synuclein concentrations [+184% (−60% to +618%)] with additional high molecular weight species in Parkinson's disease substantia nigra. No obvious correlation was observed between nigral membrane-associated, sodium dodecyl sulfate-soluble α-synuclein accumulation and Lewy body density in Parkinson's disease. Two progressive supranuclear palsy cases had membrane-associated, sodium dodecyl sulfate-soluble α-synuclein accumulation in substantia nigra similar to multiple system atrophy. Several Parkinson's disease patients had very modest high molecular weight membrane-associated, sodium dodecyl sulfate-soluble α-synuclein accumulation in putamen. Levels of 17-kDa membrane-associated, sodium dodecyl sulfate-soluble α-synuclein were generally positively correlated with those of high molecular weight membrane-associated, sodium dodecyl sulfate-soluble α-synuclein and there was a trend for a positive correlation between striatal dopamine loss and 17-kDa membrane-associated, sodium dodecyl sulfate-soluble α-synuclein concentrations in multiple system atrophy. Brain membrane-associated, sodium dodecyl sulfate-soluble α-synuclein accumulations in Parkinson's disease and multiple system atrophy are regionally specific, suggesting that these sporadic α-synucleinopathies, unlike familial Parkinsonism-dementia, are not associated with a simple global over-expression of the protein. Despite a similar extent of dopamine depletion, the magnitude of brain membrane-associated, sodium dodecyl sulfate-soluble α-synuclein changes is disease specific, with multiple system atrophy clearly having the most severe accumulation. Literature discrepancies on α-synuclein status in ‘Parkinson's disease’ might be explained by inclusion of cases not having classic brainstem-predominant Lewy body disease and by variable α-synuclein accumulation within this diagnostic classification.
178 citations
Cites background from "Expression of α‐synuclein mRNA in P..."
...Similarly, -synuclein mRNA expression data in this key pathological brain region of Parkinson’s disease are also not consistent (increased: Rockenstein et al., 2001; Chiba-Falek et al., 2006; Grundemann et al., 2008; unchanged: Tan et al., 2005; decreased: Kingsbury et al., 2004; Papapetropoulos et al., 2007; Simunovic et al., 2008; Bossers et al., 2009)....
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...…brain region of Parkinson’s disease are also not con- sistent (increased: Rockenstein et al., 2001; Chiba-Falek et al., 2006; Grundemann et al., 2008; unchanged: Tan et al., 2005; decreased: Kingsbury et al., 2004; Papapetropoulos et al., 2007; Simunovic et al., 2008; Bossers et al., 2009)....
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TL;DR: By combining optimized UV-laser microdissection- and quantitative RT–PCR-techniques with suitable PCR assays, significantly elevated α-synuclein mRNA levels in individual, surviving neuromelanin- and tyrosine hydroxylase-positive substantia nigra dopaminergic neurons from idiopathic PD brains compared to controls are detected.
Abstract: The presynaptic protein alpha-synuclein is involved in several neurodegenerative diseases, including Parkinson's disease (PD). In rare familial forms of PD, causal mutations (PARK1) as well as multiplications (PARK4) of the alpha-synuclein gene have been identified. In sporadic, idiopathic PD, abnormal accumulation and deposition of alpha-synuclein might also cause degeneration of dopaminergic midbrain neurons, the clinically most relevant neuronal population in PD. Thus, cell-specific quantification of alpha-synuclein expression-levels in dopaminergic neurons from idiopathic PD patients in comparison to controls would provide essential information about contributions of alpha-synuclein to the etiology of PD. However, a number of previous studies addressing this question at the tissue-level yielded varying results regarding alpha-synuclein expression. To increase specificity, we developed a cell-specific approach for mRNA quantification that also took into account the important issue of variable RNA integrities of the individual human postmortem brain samples. We demonstrate that PCR -amplicon size can confound quantitative gene-expression analysis, in particular of partly degraded RNA. By combining optimized UV-laser microdissection- and quantitative RT-PCR-techniques with suitable PCR assays, we detected significantly elevated alpha-synuclein mRNA levels in individual, surviving neuromelanin- and tyrosine hydroxylase-positive substantia nigra dopaminergic neurons from idiopathic PD brains compared to controls. These results strengthen the pathophysiologic role of transcriptional dysregulation of the alpha-synuclein gene in sporadic PD.
153 citations
TL;DR: Small interfering RNA against ZSCAN21 inhibits activation in the luciferase assay and diminishes SNCA protein levels in naïve and neurotrophin‐treated PC12 cells and in primary cultured cortical neurons, demonstrating that ZSCan21 is a novel transcriptional regulator of S NCA in neuronal cells.
Abstract: Alpha-synuclein (SNCA) is an abundant neuronal protein involved in synaptic neurotransmission. SNCA expression levels have been strongly implicated in Parkinson's disease pathogenesis. We have previously demonstrated that in the PC12 cell line elements in intron 1 may mediate SNCA transcriptional regulation in response to neurotrophins. We have now identified transcription factor (TF) binding sites in intron 1 and the 5'-promoter of SNCA. A binding site for the TF zinc finger and SCAN domain containing (ZSCAN)21 in the 5'-region of intron 1 is required for intron 1 transcriptional activity. Small interfering RNA against ZSCAN21 inhibits activation in the luciferase assay and diminishes SNCA protein levels in naive and neurotrophin-treated PC12 cells and in primary cultured cortical neurons, demonstrating that ZSCAN21 is a novel transcriptional regulator of SNCA in neuronal cells. The 5'-promoter of SNCA has a complex architecture, including multiple binding sites for the TF zinc finger protein (ZNF)219, which functions as both an activator and a repressor. Targeting ZSCAN21 or other TFs controlling SNCA transcriptional activity may provide novel therapeutic avenues not only for Parkinson's disease but also for other synucleopathies.
57 citations
Cites background from "Expression of α‐synuclein mRNA in P..."
...(2009) 110, 1479–1490 1479 of studies reporting both increased and decreased levels of SNCA (Rockenstein et al. 2001; Kingsbury et al. 2004; Chiba-Falek et al. 2006;Dachsel et al. 2007; Papapetropoulos et al. 2007)....
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TL;DR: Similar signal expression patterns and parallel accumulation of SEPT4 and α‐synuclein in well‐characterized postmortem PD brain are presented for the first time.
Abstract: In Parkinson's disease (PD) neuronal degeneration is associated with abnormal protein aggregation in various forms including Lewy bodies (LBs). A major component of LBs is alpha-synuclein; septin 4 (SEPT4), a polymerizing GTP-binding protein that serves as scaffold for diverse molecules has been found to colocalize with alpha-synuclein in LBs. The central role of SEPT4 in the etiopathogenesis of PD has been suggested since SEPT4 also shows a physiological association with alpha-synuclein and serves as a substrate for parkin. To this end, we studied the expression of septin 4 and alpha-synuclein in postmortem human substantia nigra (SN) and amygdala from patients with PD and healthy controls. Twenty patients (14 men : 6 women, onset 63.0 +/- 11.4 years, age 77.3 +/- 7.6 years, Hoehn and Yahr 4.05/5) and 9 neurologically healthy controls (4 men/5 women, age at death 80.1 +/- 8.6 years) were studied. Sporadic PD cases showed a statistically significant decrease of the fold change (FC) of SNCA (FC = 0.31, P = 0.00001) and SEPT4 (FC = 0.67, P = 0.054) gene expressions in the SN and the amygdala (SNCA: FC = 0.49, P = 0.02; SEPT4: FC = 0.32, P = 0.007) versus healthy controls. However, an increase of both proteins in PD versus control subjects was observed with immunoblotting. The semi-quantitative protein ratio calculations revealed more than 10-fold increases for both SEPT4 and alpha-synuclein in PD versus control subjects. We present for the first time similar signal expression patterns and parallel accumulation of SEPT4 and alpha-synuclein in well-characterized postmortem PD brain. Considering the heterogeneous etiology of sporadic PD and the variability of individual human samples, SEPT4 accumulation may be regarded as one of the common pathological changes in PD and should therefore be further explored.
41 citations
TL;DR: These findings demonstrate that the investigated Parkinson patients have markedly reduced levels of α‐synuclein in cerebellum, and that this reduction is general, rather then correlated to the investigated polymorphisms, although two of the polymorphisms also associated with disease in a Swedish material.
Abstract: Alterations of brain and plasma alpha-synuclein levels and SNCA gene variability have been implicated in the pathogenesis of Parkinson's disease (PD). We therefore measured alpha-synuclein protein levels in postmortem PD and control cerebellum tissue using Western blot and investigated whether the levels correlated to SNCA genotype. We found markedly decreased alpha-synuclein levels in PD patients (n=16) compared to gender- and age-matched controls (n=14; P=0.004) normalized to alpha-tubulin. We also performed an association study of the noncoding polymorphisms rs2737029 (A/G) and rs356204 (A/G) (intron 4), and of rs356219 (T/C) (3'-region) of SNCA in a Swedish PD case-control material. Using a two-sided chi(2) test, we found significant association of rs2737029 (P=0.003; chi(2)=9.07) and rs356204 (P=0.048; chi(2)=3.91) with disease, strengthening the involvement of SNCA polymorphisms in sporadic PD. Stratification of the human postmortem brain material by genotype of the three investigated polymorphisms, did not indicate any influence of genotype on alpha-synuclein protein levels when comparing PD with controls. Taken together, our findings demonstrate that the investigated Parkinson patients have markedly reduced levels of alpha-synuclein in cerebellum, and that this reduction is general, rather then correlated to the investigated polymorphisms, although two of the polymorphisms also associated with disease in a Swedish material.
41 citations
References
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TL;DR: The results suggest that elevated expression levels of SNCA‐mRNA are found in the affected regions of PD brain and support the hypothesis that increases in α‐synuclein expression is associated, among other factors, with the development of sporadic PD.
Abstract: Lewy bodies, the pathological hallmark of Parkinson's disease (PD), consist largely of alpha-synuclein, a 14.5-kDa presynaptic neuronal protein implicated in familial PD. An increased copy number and elevated expression of wild-type alpha-synuclein (SNCA) has been shown to cause early-onset familial PD. However, it is not clear whether increased alpha-synuclein expression also plays a role in the pathogenesis of sporadic disease. In the current study, we analyzed the levels of SNCA-mRNA in affected brains of sporadic PD patients. We compared the levels of steady state SNCA-mRNA in 7 sporadic PD brain samples and 7 normal controls using real-time polymerase chain reaction of RNA extracted from mid-brain tissue, including the substantia nigra. Despite that there is neuronal loss in the substantia nigra of PD brains, overall the SNCA-mRNA levels were increased in PD brains an average of nearly fourfold over normal control mid-brain, although there was much greater variability in samples from PD patients compared to controls. Frontal cortex samples from selected individuals were also analyzed. SNCA-mRNA levels were not significantly changed in PD frontal cortex compared to controls. These results suggest that elevated expression levels of SNCA-mRNA are found in the affected regions of PD brain and support the hypothesis that increases in alpha-synuclein expression is associated, among other factors, with the development of sporadic PD.
145 citations
TL;DR: The results suggest significant extranigral involvement in VH, and the precise etiopathologic mechanisms responsible for the development of VH need further clarification.
95 citations
46 citations
TL;DR: There is now need for a scheme for an internationally acceptable scheme for pathological diagnosis and classification so that clinical, pathological and molecular features of disease can be correlated.
Abstract: In recent years dementia histologically characterised by the presence of cortical Lewy bodies has been increasingly recognised. There is now need for a scheme for an internationally acceptable scheme for pathological diagnosis and classification so that clinical, pathological and molecular features of disease can be correlated. Recent observations made by different groups in large patient series have used slightly different pathological criteria resulting in at least seven different diagnostic terms. In some patients the only cortical pathology is the presence of Lewy bodies, while in the majority of patients there are coexisting pathological changes which either overlap with those seen in Alzheimer’s disease (AD). Cortical Lewy bodies can also be present in patients who do not have any obvious cognitive abnormality. A problem with equating studies from different groups is that different criteria have been used to define AD, so that establishing the relevance of cortical Lewy bodies themselves to cognitive decline and separating this from the contribution which may be related to the AD pathology is problematic. The lesions which appear to be of most relevance to potential cognitive decline in DLB are cortical Lewy bodies, Lewy-related neurites, senile plaques, neurofibrillary tangles, neuronal and synaptic loss, spongiform change, and cortical cholinergic deficits. It is possible to operationally classify patients with cognitive decline and cortical Lewy bodies into three main groups, Cortical Lewy body disease, Cortical Lewy body disease with plaques, and Cortical Lewy body disease with plaques and tangles. There are frequent cases which overlap these groups making operational classification difficult in practice. A descriptive classification, in which the severity of different pathological changes is rated, is easy to use in practice. As new molecular risk factors for AD or DLB are revealed they will need to be related to morphological and clinical features. A descriptive diagnostic assessment for DLB will facilitate such studies and makes no judgements as to what these relationships will be.
19 citations
TL;DR: In the post-genomic era, seven high-throughput gene array studies have attempted to identify candidate genes and biochemical pathways in Parkinson’s disease and different factors influencing optimal target and biomarker discovery with gene-expression profiling are discussed.
Abstract: In the past decade, several gene mutations have been described in families with a Mendelian inheritance pattern of Parkinson’s disease (PD), using linkage mapping. These cases represent only a small percentage (<5%) of the patients who develop PD. The current understanding of the mechanisms that underlie aspects of the neurodegenerative process of PD is based mainly on research of functional pathways related to these genes. However, even with knowledge of these pathways, the number of relevant genes may still be very large. In the post-genomic era, seven high-throughput gene array studies have attempted to identify candidate genes and biochemical pathways in PD. In this review, results from these studies and different factors influencing optimal target and biomarker discovery with gene-expression profiling are discussed.
11 citations