Alpha-synuclein mRNA Levels Research Articles

Honokiol decreases alpha-synuclein mRNA levels and reveals novel targets for modulating alpha-synuclein expression.

Intracytoplasmic inclusions comprised of aggregated alpha-synuclein (αsyn) represent a key histopathological feature of neurological disorders collectively termed "synucleinopathies," which includes Parkinson's disease (PD). Mutations and multiplications in the SNCA gene encoding αsyn cause familial forms of PD and a large body of evidence indicate a correlation between αsyn accumulation and disease. Decreasing αsyn expression is recognized as a valid target for PD therapeutics, with down-regulation of SNCA expression potentially attenuating downstream cascades of pathologic events. Here, we evaluated if Honokiol (HKL), a polyphenolic compound derived from magnolia tree bark with demonstrated neuroprotective properties, can modulate αsyn levels in multiple experimental models. Human neuroglioma cells stably overexpressing αsyn, mouse primary neurons, and human iPSC-derived neurons were exposed to HKL and αsyn protein and SNCA messenger RNA levels were assessed. The effect of HKL on rotenone-induced overexpression of αsyn levels was further assessed and transcriptional profiling of mouse cortical neurons treated with HKL was performed to identify potential targets of HKL. We demonstrate that HKL can successfully reduce αsyn protein levels and SNCA expression in multiple in vitro models of PD with our data supporting a mechanism whereby HKL acts by post-transcriptional modulation of SNCA rather than modulating αsyn protein degradation. Transcriptional profiling of mouse cortical neurons treated with HKL identifies several differentially expressed genes (DEG) as potential targets to modulate SNCA expression. This study supports a HKL-mediated downregulation of SNCA as a viable strategy to modify disease progression in PD and other synucleinopathies. HKL has potential as a powerful tool for investigating SNCA gene modulation and its downstream effects.

Экспрессия гена альфа-синуклеина и генов мембранных белков и ферментов лизосом в патогенезе болезни Паркинсона, ассоциированной с мутациями в гене GBA

Мутации в гене, кодирующем лизосомный фермент глюкоцереброзидазу (GBA), являются фактором высокого риска болезни Паркинсона (БП). Остается неясным, почему не у всех носителей мутаций в данном гене в течение жизни развивается БП. Предполагается, что дисфункция мембранных белков и ферментов лизосом может способствовать развитию БП у носителей мутаций в гене GBA. В данном исследовании была оценена экспрессия генов альфа-синуклеина и LAMP2, GLA, GALNS, SCARB2 в CD45+ клетках периферической крови у пациентов с GBA-БП, бессимптомных носителей мутаций в гене GBA (GBA-носителей), а также в у пациентов с БП и в контроле. Выявлена повышенная экспрессия гена альфа-синуклеина на фоне снижения уровня экспрессии генов мембранных белков лизосом (LAMP2, SCARB2) у пациентов с GBA-БП и GBA-носителей, что может свидетельствовать о вовлеченности этих генов в патогенез GBA-БП. Пониженная экспрессия гена LAMP2 может рассматриваться в качестве одного из триггеров развития БП у носителей мутаций в гене GBA. Mutations in the gene GBA that are encoding the lysosomal enzyme glucocerebrosidase are the most common genetic risk factor for PD. Not every carrier of GBA mutations will develop PD. Probably the dysfunction of lysosomal enzymes and membrane proteins may contribute or protect to the development of PD among carriers of GBA mutations. In the current study LAMP2, GLA, GALNS, SCARB2 and alpha-synuclein mRNA levels in CD45+ blood cells were estimated in patients with GBA-associated PD (GBA-PD), non-manifesting GBA carriers(GBA-Carriers), PD patients and controls. This is the first report estimating LAMP2, GLA, GALNS, SCARB2 and alpha-synuclein expressions in CD45+ blood cells in GBA-PD patients and GBA-Carriers. We revealed increased SNCA expression and changing expression of lysosomal genes (LAMP2, GALNS, SCARB2) that may contribute role these genes in pathogenesis of GBA-PD. Decreased of LAMP2 may be considered as trigger of GBA-PD.

Systemic Exosomal Delivery of shRNA Minicircles Prevents Parkinsonian Pathology.

The development of new therapies to slow down or halt the progression of Parkinson's disease is a health care priority. A key pathological feature is the presence of alpha-synuclein aggregates, and there is increasing evidence that alpha-synuclein propagation plays a central role in disease progression. Consequently, the downregulation of alpha-synuclein is a potential therapeutic target. As a chronic disease, the ideal treatment will be minimally invasive and effective in the long-term. Knockdown of gene expression has clear potential, and siRNAs specific to alpha-synuclein have been designed; however, the efficacy of siRNA treatment is limited by its short-term efficacy. To combat this, we designed shRNA minicircles (shRNA-MCs), with the potential for prolonged effectiveness, and used RVG-exosomes as the vehicle for specific delivery into the brain. We optimized this system using transgenic mice expressing GFP and demonstrated its ability to downregulate GFP protein expression in the brain for up to 6weeks. RVG-exosomes were used to deliver anti-alpha-synuclein shRNA-MC therapy to the alpha-synuclein preformed-fibril-induced model of parkinsonism. This therapy decreased alpha-synuclein aggregation, reduced the loss of dopaminergic neurons, and improved the clinical symptoms. Our results confirm the therapeutic potential of shRNA-MCs delivered by RVG-exosomes for long-term treatment of neurodegenerative diseases.

Analyses of copy number and mRNA expression level of the alpha-synuclein gene in multiple system atrophy.

Multiple system atrophy (MSA) is a sporadic neurodegenerative disease manifested clinically by progressive ataxia, parkinsonism, and autonomic dysfunction. Its cause is unknown, and there is no curative therapy. Alpha-synuclein is an important protein forming aggregations called glial cytoplasmic inclusions (GCIs) in oligodendroglia; these aggregations are considered important in MSA pathogenesis. Overexpression of the human alpha-synuclein gene in mice induces the formation of GCI-like aggregations in oligodendrocytes, leading mice to exhibit neurological signs similar to those in MSA patients. However, previous studies have excluded mutations within the coding region of the alpha-synuclein gene in MSA patients. To determine whether alteration in the expression level of the alpha-synuclein gene is associated with MSA pathogenesis, we used TaqMan quantitative PCR assay to analyze the alpha-synuclein gene copy number in patients' genomes. We also used quantitative RT-PCR and in situ hybridization to analyze alpha-synuclein mRNA expression in MSA patients' brain tissues. We found no alteration in the alpha-synuclein gene copy number in the patients' genomes (n = 50). Quantitative analysis for alpha-synuclein mRNA by the TaqMan method showed that alpha-synuclein mRNA levels were comparable between control (n = 3) and MSA (n = 3) cerebella. On in situ hybridization, the number of neurons with alpha-synuclein mRNA expression was no greater in the cerebella of MSA patients (n = 3) than in the controls (n = 3). However, GCIs were seen in these MSA specimens on immunohistochemistry for alpha-synuclein. These results suggest that alpha-synuclein gene expression is not the fundamental cause of MSA.

α-Synuclein Suppression by Targeted Small Interfering RNA in the Primate Substantia Nigra

The protein α-synuclein is involved in the pathogenesis of Parkinson's disease and other neurodegenerative disorders. Its toxic potential appears to be enhanced by increased protein expression, providing a compelling rationale for therapeutic strategies aimed at reducing neuronal α-synuclein burden. Here, feasibility and safety of α-synuclein suppression were evaluated by treating monkeys with small interfering RNA (siRNA) directed against α-synuclein. The siRNA molecule was chemically modified to prevent degradation by exo- and endonucleases and directly infused into the left substantia nigra. Results compared levels of α-synuclein mRNA and protein in the infused (left) vs. untreated (right) hemisphere and revealed a significant 40–50% suppression of α-synuclein expression. These findings could not be attributable to non-specific effects of siRNA infusion since treatment of a separate set of animals with luciferase-targeting siRNA produced no changes in α-synuclein. Infusion with α-synuclein siRNA, while lowering α-synuclein expression, had no overt adverse consequences. In particular, it did not cause tissue inflammation and did not change (i) the number and phenotype of nigral dopaminergic neurons, and (ii) the concentrations of striatal dopamine and its metabolites. The data represent the first evidence of successful anti-α-synuclein intervention in the primate substantia nigra and support further development of RNA interference-based therapeutics.

Alpha-Synuclein mRNA Levels Correspond to Beck Depression Inventory Scores in Females with Eating Disorders

α-Synuclein (α-Syn) is a neuronal protein involved in the regulation of brain serotonin and dopamine levels. We analyzed the peripheral expression of α-Syn mRNA and Beck Depression Inventory scores in female patients suffering from anorexia nervosa (n = 18) or bulimia nervosa (n = 24). We found a significant positive association between α-Syn mRNA expression and the total scores of the Beck Depression Inventory (linear regression; R² = 0.20; p = 0.003). α-Syn may play a pathophysiological role in depressive symptoms associated with eating disorders. Further investigations in patients with depression as a sole diagnosis are needed to support its role in the pathogenesis of major depression.

Elevated α-synuclein mRNA levels in individual UV-laser-microdissected dopaminergic substantia nigra neurons in idiopathic Parkinson's disease

The presynaptic protein α-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 α-synuclein gene have been identified. In sporadic, idiopathic PD, abnormal accumulation and deposition of α-synuclein might also cause degeneration of dopaminergic midbrain neurons, the clinically most relevant neuronal population in PD. Thus, cell-specific quantification of α-synuclein expression-levels in dopaminergic neurons from idiopathic PD patients in comparison to controls would provide essential information about contributions of α-synuclein to the etiology of PD. However, a number of previous studies addressing this question at the tissue-level yielded varying results regarding α-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 α-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 α-synuclein gene in sporadic PD.

P.6.b.002 Peripheral blood alpha-synuclein mRNA levels are elevated in patients with alcoholism

P.6.b.002 Peripheral blood alpha-synuclein mRNA levels are elevated in patients with alcoholism

Elevated alpha synuclein mRNA levels are associated with craving in patients with alcoholism

Alpha synuclein has been found elevated in dopamine neurons of cocaine abusers and in rats whose alcohol preference is inbred. The alpha synuclein mRNA expression level was measured by quantitative polymerase chain reaction in the blood of 75 male alcoholics and 69 nondrinking healthy control subjects. Alcohol craving was assessed by the Obsessive-Compulsive Drinking Scale total score, including subscales for obsessive and compulsive craving. The alpha synuclein expression in patients with alcoholism (2.79 DeltaCT; SD = 1.69; p = .021) was significantly higher when compared with healthy control subjects (2.20 DeltaCT; SD = 1.59). Increased alpha synuclein levels significantly predict Obsessive-Compulsive Drinking Scale total score (odds ratio = 1.44, 95% confidence interval: 1.01-2.06, p = .042) and especially Obsessive-Compulsive Drinking Scale obsessive subscale (odds ratio = 1.74, 95% confidence interval: 1.18-2.58, p = .005) but not Obsessive-Compulsive Drinking Scale compulsive subscale alcohol craving. Higher levels of alpha synuclein are associated with an increase in alcohol craving. The present results provide a novel pathophysiological approach to the explanation of craving mechanisms.

Analysis of the expression level of alpha-synuclein mRNA using postmortem brain samples from pathologically confirmed cases of multiple system atrophy.

To determine whether multiple system atrophy (MSA) is associated with altered expression levels of the alpha-synuclein messenger RNA (mRNA), we performed quantitative reverse transcription polymerase chain reaction for alpha-synuclein mRNA using postmortem brain samples from 11 cases of MSA and 14 age-matched control subjects. The brain specimens used in this study contained both the gray matter and white matter, which were dissected from the frontal, temporal or occipital lobe. The expression levels of alpha-synuclein mRNA in the brain specimens of MSA cases were not different from those of the control subjects. These results suggest that the transcriptional regulation of the alpha-synuclein gene is unlikely to be affected in MSA brains.

Alpha-synuclein expression in substantia nigra and cortex in Parkinson's disease.

Mutations in the human alpha-synuclein gene have been identified in several families of European descent with early-onset Parkinson's disease (PD). We sequenced the complete alpha-synuclein cDNA from substantia nigra and cortex from nine patients with PD and eight control subjects. No mutations were found. We then analyzed alpha-synuclein mRNA levels using a ribonuclease protection assay. Two major protected bands of alpha-synuclein mRNA, possibly representing two splice variants of the gene, were observed. Alpha-synuclein mRNA was significantly diminished in the substantia nigra of patients with PD compared with control subjects but not in the cortex. Our findings suggest that decreased synuclein mRNA may be an early alteration in the SN in PD, and imply that decreased levels of the protein may play a role in the pathogenesis of sporadic cases of the disease.

The cDNA cloning and ontogeny of mouse alpha-synuclein.

Alpha-synuclein has been implicated in the pathogenesis of Parkinson's disease. To investigate the role of alpha-synuclein in the brain, the cDNA clone encoding the mouse cognate of the human alpha-synuclein was isolated from a mouse brain cDNA library. The open reading frame coded for 140 amino acids that share 95% identity with human alpha-synuclein. Northern blot analysis showed that alpha-synuclein mRNA was primarily expressed in brain and spleen of adult mouse. In situ hybridization histochemistry revealed the highest expression of alpha-synuclein mRNA in the hippocampal formation and neocortex of the adult mouse. alpha-Synuclein mRNA expression in the brain was first observed in the hippocampus and neocortex on postnatal day 1. Levels of alpha-synuclein mRNA in these forebrain areas were nearly maximal at postnatal day 7 and remained relatively high until the adult stage. alpha-Synuclein mRNA was expressed in the liver transiently during embryogenesis.