The analysis of association between <Emphasis Type="Italic">SNCA</Emphasis>, <Emphasis Type="Italic">HUSEYO</Emphasis> and <Emphasis Type="Italic">CSMD1</Emphasis> gene variants and Parkinson’s disease in Iranian population

Parkinson’s disease (PD) is the second most prevalent neurodegenerative disorder. Both genetic and environmental factors are involved in the etiology of the disease. Many studies have revealed the susceptibility genes and variations for PD which need further confirmation. Here we evaluated the association of variations in SNCA, HUSEYO and CSMD1 genes with PD. A case–control study was conducted with 489 PD patients and 489 healthy controls. DNA was extracted from peripheral blood of all subjects and rs356220 and rs11931074 in SNCA, rs2338971 in HUSEYO and rs12681349 in CSMD1 were genotyped using PCR–RFLP method. The genotypes and allele frequencies were significantly different between case and control groups for rs356220, rs11931074 and rs2338971 but not for rs12681349. We provided further evidence that rs356220 is associated with increased risk of PD supporting previous studies in Caucasian-based and Japanese populations. The association of rs11931074 with decreased risk of PD was also significant. This study revealed the first evidence of the association of rs2338971 with increased risk of PD in the Iranian population. Nevertheless, these findings need further validation via more replication studies.     

Genetic Analysis of <Emphasis Type="Italic">FBXO2</Emphasis>, <Emphasis Type="Italic">FBXO6</Emphasis>, <Emphasis Type="Italic">FBXO12</Emphasis>, and <Emphasis Type="Italic">FBXO41</Emphasis> Variants in Han Chinese Patients with Sporadic Parkinson’s Disease

Parkinson’s disease (PD) is the second most common neurodegenerative disorder and has an elusive etiology. It is likely multifactorial, and genetic defects contribute to its pathogenesis. At least 25 genetic loci and 20 monogenic genes have been identified in monogenic PD. Recessive F-box protein 7 gene (FBXO7) mutations reportedly cause hereditary parkinsonism. To explore the roles of four paralogs (FBXO2, FBXO6, FBXO12, and FBXO41) in PD development, their variants (rs9614, rs28924120, rs6442117, and rs61733550, respectively) were analyzed in 502 Han Chinese patients with PD and 556 age, gender, and ethnicity-matched normal participants in mainland China. Statistically significant differences in genotypic and allelic frequencies were detected only in the FBXO2 variant rs9614 (P = 0.001 and 0.023, respectively; odds ratio 0.819, 95% confidence interval 0.690–0.973) between patients and controls. These results suggest that the FBXO2 variant rs9614 C allele may decrease the PD risk in mainland Han Chinese and may be a biomarker for PD.     

<Emphasis Type="Italic">N</Emphasis><Superscript>ε</Superscript>-Carboxymethyllysine in diabetic and non-diabetic polyneuropathies

Increased oxidative stress and advanced glycosylation are important factors in the development of diabetic neuropathy. In non-diabetic neuropathies their influence has not been investigated in detail so far. We studied the localisation of N(epsilon)-carboxymethyllysine (CML) - a biomarker for oxidative stress - by immunohistochemistry in sural nerve biopsies of 31 patients with different polyneuropathies [diabetic polyneuropathy (n=5), alcohol-associated polyneuropathy (n=4), vitamin B12-deficient polyneuropathy (n=6), chronic inflammatory demyelinating polyneuropathy (CIDP) (n=6), vasculitic neuropathy (n=6), Charcot-Marie-Tooth disease type I (CMT I) (n=4)] and 4 normal controls. CML was detected in the perineurium of patients with diabetic, alcohol-associated, vitamin B12-deficient and vasculitic polyneuropathies. Epineurial, perineurial and endoneurial vessels were CML positive in diabetic, vitamin B12-deficient and vasculitic polyneuropathies. CML was also found in mononuclear inflammatory cells in vasculitic neuropathy. In CIDP and normal controls there was only marginal perineurial CML deposition in 2/6 and 1/4 cases. In CMT I no CML was detected. Immunohistochemical results were confirmed by immunoblot. Our data suggest a role of oxidative stress in the pathogenesis not only of diabetic but also of alcohol-associated, vitamin B12-deficient and vasculitic polyneuropathies. It may be a minor pathogenetic factor in CIDP and may not be involved in CMT I. Underlying causes for increased oxidative stress may be an elevated production of reactive oxygen species and an impairment of antioxidative defences. Therefore, an antioxidative treatment should be considered in alcohol-associated, vitamin B12-deficient and vasculitic polyneuropathy.     

<Emphasis Type="SmallCaps">l-</Emphasis>dopa modulates motor cortex excitability in Alzheimer’s disease patients

In Alzheimer's disease (AD), transcranial magnetic stimulation (TMS) studies have shown abnormalities of motor cortical excitability, such as a decreased intra-cortical inhibition (ICI) and changes in resting motor threshold (rMT). We studied the effects of L-dopa on rMT and ICI in a cohort of moderate AD patients after paired-pulse TMS. Results were compared with a control group of healthy subjects. As expected, AD patients showed a significant reduction in ICI and a lower rMT. L-dopa administration (soluble form, melevodopa 200 mg) promptly reversed the ICI impairment up to normalization. This effect was specific, since it was not mimicked in control subjects. These results indicate a possible role of dopamine in modulating AD cortical excitability, thus suggesting an interaction between dopaminergic ascending pathways and endogenous intracortical transmitters. In addition, considering that L-dopa showed a pharmacological profile similar to the one of cholinomimetics, L-dopa might represent a reliable tool to study new therapeutic perspective and strategies for AD.     

Genetic analysis of <Emphasis Type="Italic">heme oxygenase</Emphasis>-<Emphasis Type="Italic">1</Emphasis> (<Emphasis Type="Italic">HO-1</Emphasis>) in German Parkinson’s disease patients

Parkinson’s disease (PD) is characterized by the loss of dopaminergic neurons and the presence of intracytoplasmic inclusions (Lewy bodies). Iron, which is elevated in the substantia nigra (SN) of PD patients, seems to be of pivotal importance, because of its capacity to enhance the amplification of reactive-oxygen species. Therefore, it is tempting that the iron-releasing key enzyme in heme catabolism, heme oxygenase-1 (HO-1), may represent a candidate for a genetic susceptibility to PD. In the current study, we examined a (GT)n fragment length polymorphism in the promoter region, as well as three coding SNPs in the HO-1 gene in order to assess if certain genotypes are associated with PD. Furthermore, peripheral blood expression levels of HO-1 in PD patients and healthy probands were compared. However, our analyses did not reveal a significant association of these genetic markers in the HO-1 gene with an increased susceptibility to PD.     

Flibanserin attenuates <Emphasis Type="SmallCaps">l</Emphasis>-DOPA-sensitized contraversive circling in the unilaterally 6-hydroxydopamine-lesioned rat model of Parkinson’s disease

A central problem in the treatment of Parkinson’s disease (PD) is the development of motor disturbances like l-DOPA-induced dyskinesia (LID) after long-term treatment. Preclinical and clinical studies demonstrated that serotonin 5-HT_1A receptor agonists attenuate this disabling motor side effect. The aim of this study was to investigate the ability of flibanserin compared to buspirone to attenuate l-DOPA-sensitized contraversive circling in hemiparkinsonian rats, which is an animal model of LID. Both drugs have a preferential affinity for the serotonin 5-HT_1A receptors. Buspirone was in comparison because it was expected to have an effect in this model. Unilaterally 6-hydroxydopamine lesioned rats were treated twice daily intraperitoneally (ip) with l-DOPA methylester (12.5 mg/kg) and benserazide (3.25 mg/kg) for 21 days (on days 1, 3, 5, 8, 11, 14, 17 and 21). On day 24, l-DOPA-sensitized rats were treated ip 5 min prior to administration of l-DOPA methyl ester and benserazide with either saline (controls), 2.5, 5 and 10 mg/kg buspirone or flibanserin. Acute administration of both flibanserin and buspirone, dose dependently, attenuated the increased contraversive circling. An almost complete inhibition of the turning response was observed at 5 mg/kg buspirone and 10 mg/kg flibanserin. The current preclinical findings further implicate the 5-HT_1A receptor as a promising therapeutic target for the reduction of LID and predict a potential efficacy of flibanserin in the treatment of LID in PD.     

Pharmacological Effects on Ceroid Lipofuscin and Neuronal Structure in <Emphasis Type="Italic">Cln3</Emphasis><Superscript><Emphasis Type="Italic">∆ex7/8</Emphasis></Superscript> Mouse Brain Cultures

Juvenile Batten disease (JBD) is an inherited disorder that is characterized by the development of blindness, seizures, and progressive motor, psychiatric, and cognitive impairment. A model of JBD expressing the predominant human mutation (Cln3 ^?ex7/8 ) has been explored. Dissociated brain cultures from Cln3 ^?ex7/8 knock-in mice were compared to wild type (WT) for effects on granules of ceroid lipofuscin (CL) and neuronal structure. Utilizing high content image analysis of CL granules identified with antibodies to mitochondrial ATP synthase subunit c or tripeptidyl peptidase-1, significant increases in the areas for both immunoreactive granules were observed in Cln3 ^?ex7/8 cultures in comparison to WT. CL granules also exhibit autofluorescence at 488 and 560 nm, and the areas of these autofluorescent spots were found to be significantly increased in Cln3 ^?ex7/8 cultures in comparison to WT. Progressive increases in CL granule area in Cln3 ^?ex7/8 cultures were observed during culture development. Because current therapies for JBD provide only symptomatic support, a therapeutic strategy has been explored based on the observations that JBD-related tissues are deficient in β-galactosyl ceramide. Treatment of cultures for 40 h with a potent analog of β-galactosyl ceramide (SNB-4050) produced significant decreases in CL granule area in the Cln3 ^?ex7/8 cultures; whereas identical studies on WT cultures produced no detectible changes. Significant decreases in average neurite length and neurite branch point number were also observed in the Cln3 ^?ex7/8 cultures that were attenuated by treatment with 1 nM SNB-4050. These studies indicate Cln3 ^?ex7/8 brain cultures may be useful to screen therapeutic agents for treatment of JBD.     

The relation of serum uric acid levels with <Emphasis Type="SmallCaps">l</Emphasis>-Dopa treatment and progression in patients with Parkinson’s disease

In this study, we aimed to investigate the association of the serum uric acid (UA) level with disease progression and l-Dopa treatment in PD (Parkinson’s disease) patients. Serum UA levels of 80 consecutive PD patients were measured and were matched according to age and sex with 80 healthy controls. The patients were divided into two subgroups according to the pharmaceutical treatment received. First group consisted of patients treated with l-Dopa and a dopamine agonist and the second group consisted of patients treated only with a dopamine agonist. The patients were divided into two other subgroups according to Hoehn and Yahr scale. First group consisted of patients at the first two stages and the second group included patients at the third and upper stages. PD patients were found to have significantly lower levels of serum UA than controls (p = 0.000). Serum UA levels were lower in the group under l-Dopa + dopamine agonist treatment and in patients at third and upper Hoehn and Yahr stages than the patients under only dopamine agonist treatment and in the patients at the first two stages (p = 0.000 and p = 0.000). Multivariate logistic regression showed that advanced stages (OR 0.65, CI 0.50–0.79, p = 0.000) and l-Dopa treatment (OR 1.08, CI 1.03–1.16, p = 0.001) were independently associated with low UA levels. Our study supports that there is an inverse relation between UA levels and l-Dopa treatment and PD stages, and high serum UA levels may decrease the oxidative stress taking part in the pathogenesis of PD.     

The murine <Emphasis Type="Italic">Bis1</Emphasis> seizure gene and the <Emphasis Type="Italic">Kcnab2</Emphasis> gene encoding the β2-subunit of the K<Superscript>+</Superscript> channel are different

Received: April 22, 1999 / Accepted: August 30, 1999 / Published online: January 10, 2000     

Genetic variability in <Emphasis Type="Italic">SNCA</Emphasis> and Parkinson’s disease

Over the last decades, increasing knowledge about the genetic architecture of Parkinson’s disease has provided novel insights into the pathogenesis of the disorder, generating hypotheses for further research. Characterizing the role of SNCA, encoding the α-synuclein protein, has been a particularly important aspect of this development. The identification of SNCA as the first gene implicated in monogenic parkinsonism led to the recognition of α-synuclein as a key protein in the pathogenesis and a major component of pathological hallmark lesions. An association between common variants in SNCA and risk of sporadic Parkinson’s disease has been established through numerous studies. We review our current understanding of SNCA variability contributing to Parkinson’s disease, highlighting the characterization of functionally relevant susceptibility alleles as a major future challenge. We argue that new strategies will be needed to pinpoint the variants that are ultimately responsible for the signals detected in association studies, where targeted resequencing may represent an attractive initial approach.     

Lower functional connectivity of default mode network in cognitively normal young adults with mutation of <Emphasis Type="Italic">APP</Emphasis>, <Emphasis Type="Italic">presenilins</Emphasis> and <Emphasis Type="Italic">APOE ε4</Emphasis>

In this study, we used resting-state functional magnetic resonance imaging to explore the genetic effects of amyloid precursor protein (APP) or presenilins mutation and apolipoprotein E (APOE) ε4 on the default-mode network (DMN) in cognitively intact young adults (24.1 ± 2.5 years). Both the APP or presenilin-1/2 group and the APOE ε4 group had significantly lower DMN functional connectivity (FC) in the some brain regions like precuneus/middle cingulate cortices (PCu/MCC) than controls (AlphaSim corrected, P < 0.05). Only a lower FC tendency was demonstrated (control < APOE ε4 < APP or presenilin-1/2 group). Moreover, lower FC in PCu/MCC is correlated with some neuropsychological assessments such as similarity test in APOE ε4 group. These findings indicate that DMN FC alteration in APP or presenilin-1/2 or APOE ε4 subjects is prior to the occurrence of neurological alterations and clinical symptoms, and DMN FC might be a valuable biomarker to detect genetic risk in the preclinical stage.     

Expression analysis of <Emphasis Type="Italic">GRIN2B</Emphasis>, <Emphasis Type="Italic">BDNF</Emphasis>, and <Emphasis Type="Italic">IL-1β</Emphasis> genes in the whole blood of epileptic patients

Epilepsy is a brain disorder with a global prevalence of 1%. It has been attributed to genetics and environmental factors. Despite efforts to identify the molecular pathology of epilepsy, the underlying mechanism is not understood yet. This study was carried out to compare GRIN2B, BDNF, and IL-1β gene expressions in 50 patients suffering from generalized epilepsy with tonic-colonic seizures and 50 age- and sex-matched healthy subjects using TaqMan Real-time PCR. Our results demonstrated significant upregulation of these genes in people with epilepsy compared with healthy subjects. We also found a positive correlation between GRIN2B and BDNF expression (r²=0.4619, p?<?0.0001), BDNF and IL-1β expression (r²?=?0.515, p?<?0.0001), and GRIN2B and IL-1β gene expressions (r²?=?0.666, p?<?0.0001) which implies the possibility to estimate the expression level of these genes by assessment of expression of one of them. Considering the results of the previous animal studies which showed upregulation of these genes in brain tissues of epileptic animals, the expression levels of GRIN2B, BDNF, and IL-1β in blood samples might be related to their expression in brain samples. Future studies are needed to assess the role of these genes in the pathogenesis of epilepsy and evaluate whether altered expression of these genes along with imaging methods can facilitate subtyping the epilepsy.     

Attenuation of β-Amyloid Toxicity <Emphasis Type="Italic">In Vitro</Emphasis> and <Emphasis Type="Italic">In Vivo</Emphasis> by Accelerated Aggregation

Accumulation and aggregation of β-amyloid (Aβ) peptides result in neuronal death, leading to cognitive dysfunction in Alzheimer’s disease. The self-assembled Aβ molecules form various intermediate aggregates including oligomers that are more toxic to neurons than the mature aggregates, including fibrils. Thus, one strategy to alleviate Aβ toxicity is to facilitate the conversion of Aβ intermediates to larger aggregates such as fibrils. In this study, we designed a peptide named A3 that significantly enhanced the formation of amorphous aggregates of Aβ by accelerating the aggregation kinetics. Thioflavin T fluorescence experiments revealed an accelerated aggregation of Aβ monomers, accompanying reduced Aβ cytotoxicity. Transgenic Caenorhabditis elegans over-expressing amyloid precursor protein exhibited paralysis due to the accumulation of Aβ oligomers, and this phenotype was attenuated by feeding the animals with A3 peptide. These findings suggest that the Aβ aggregation-promotion effect can potentially be useful for developing strategies to reduce Aβ toxicity.     

Association between <Emphasis Type="Italic">FGF20 rs12720208</Emphasis> gene polymorphism and Parkinson’s disease: a meta-analysis

Previous studies have claimed the association of rs12720208 polymorphism in the fibroblast growth factor 20 (FGF20) gene with the increased risk of Parkinson’s disease (PD), but results from the published data were controversial. The aim of our present meta-analysis was to estimate the overall association between FGF20 rs12720208 polymorphism and the risk of PD. Case–control studies with sufficient data evaluating the association between rs12720208 C/T polymorphism and PD susceptibility were systematically identified in PubMed, OVID, SinoMed, Chinese National Knowledge Infrastructure (CNKI) up to July 10, 2015. A total of 3402 PD patients and 3739 controls from seven case–control studies were collected for this meta-analysis. The pooled odds ratio (OR) with its 95 % confidence interval (CI) was calculated to assess the genetic association between FGF20 rs12720208 polymorphism and the risk of PD. In this study, no enough proof was found to prove the association in any genetic models with random-effects model (CT+TT vs. CC: OR = 1.147, 95 % CI: 0.883–1.489, P = 0.304; TT vs. CC+CT: OR = 1.754, 95 % CI: 0.878–3.505, P = 0.112; T vs. C: OR = 1.169, 95 % CI = 0.919–1.487, P = 0.204; TT+CC vs. CT: OR = 0.906, 95 % CI = 0.694–1.182, P = 0.466). Our results suggest that there is no sufficient evidence to support the association between rs12720208 polymorphism and PD risk. Studies with larger sample size across diverse populations and subgroup analyses are necessary in the future.     

Changes in the mRNA Levels of α<Subscript>2A</Subscript> and α<Subscript>2C</Subscript> Adrenergic Receptors in Rat Models of Parkinson’s Disease and <Emphasis Type="SmallCaps">l</Emphasis>-DOPA-Induced Dyskinesia

The changes in the mRNA levels of α_2A and α_2C adrenoceptors were investigated in unilateral 6-OHDA-lesioned rat model of Parkinson’s disease and l-DOPA-induced dyskinesia using in situ hybridization. In the untreated 6-OHDA-lesioned rats, α_2A expression was elevated in the locus coeruleus (160 ± 8% and 142 ± 8% in lesioned and unlesioned sides compared to the comparable side in sham-operated rats). Following long-term (21 days, twice daily) treatment with l-DOPA (25 mg/kg l-DOPA methyl ester plus benserazide 6.25 mg/kg) in 6-OHDA-lesioned rats, levels of α_2A adrenoceptor mRNA in the locus coeruleus were decreased, compared to the 6-OHDA-lesioned rats, returning to the levels of α_2A mRNA in the sham-operated rats. α_2A adrenoceptor expression was not changed in other brain regions in any treatment group. There was no change in α_2C expression in the rostral or caudal striatum in which the highest density of α_2C mRNA is present. In conclusion, the data presented in this study demonstrate an increase in α_2A adrenoceptor mRNA in the locus coeruleus in the 6-OHDA-lesioned rat model of Parkinson’s disease. In addition, the data show that repeated treatment with l-DOPA in 6-OHDA-lesioned rats, which induces dyskinesia, restores α_2A mRNA levels. These changes of α_2A mRNA expression, observed in the locus coeruleus, might be of importance to basal ganglia transmission and motor function.     

Phenotype analysis in patients with early onset Parkinson’s disease with and without <Emphasis Type="Italic">parkin</Emphasis> mutations

The data regarding whether parkin genotype attributes phenotypic variation are conflicting. Since the incidence of parkin mutations is very low in patients with an age at onset (AAO) of >40 years, previous studies have unfairly compared phenotypes of two early onset Parkinson’s disease (EOPD) groups with different AAOs. Thus, we compared the clinical features between patients with and without parkin mutations in EOPD with an AAO of ≤40 years. Of the 124 patients with EOPD with an AAO of ≤40 years who were recruited and screened for parkin mutations, 84 completed assessments for comparison of the phenotype according to parkin genotype. Fourteen of the 84 subjects carried two parkin mutations; 6, a single mutation; and 64, no mutations. Patients with two mutations had significantly younger AAOs, longer duration of PD, and more common family history than patients without parkin mutations. Otherwise, motor and nonmotor symptoms did not differ between them. Subgroup analysis of EOPD with an AAO of ≤35 years revealed similar results. Phenotype of EOPD may depend on early AAOs rather than presence of parkin mutations.     

Broadening the phenotype of <Emphasis Type="Italic">TARDBP</Emphasis> mutations: the <Emphasis Type="Italic">TARDBP</Emphasis> Ala382Thr mutation and Parkinson’s disease in Sardinia

Mutations in the TARDBP gene are a cause of autosomal dominant amyotrophic lateral sclerosis (ALS) and of frontotemporal lobar degeneration (FTLD), but they have not been found so far in patients with Parkinson’s disease (PD). A founder TARDBP mutation (p.Ala382Thr) was recently identified as the cause of ~30% of ALS cases in Sardinia, a Mediterranean genetic isolate. We studied 327 consecutive Sardinian patients with clinically diagnosed PD (88 familial, 239 sporadic) and 578 Sardinian controls. One family with FTLD and parkinsonism was also included. The p.Ala382Thr heterozygous mutation was detected in eight unrelated PD patients (2.5%). The three patients from the FTLD/parkinsonism family also carried this mutation. Within the control group, there were three heterozygous mutation carriers. During follow-up, one of these individuals developed motoneuron disease and another, a rapidly progressive dementia; the third remains healthy at the age of 79 but two close relatives developed motoneuron disease and dementia. The eight PD patients carrying the p.Ala382Thr mutation had all sporadic disease presentation. Their average onset age was 70.0 years (SD 9.4, range 51–79), which is later but not significantly different from that of the patients who did not carry this mutation. In conclusion, we expand the clinical spectrum associated with TARDBP mutations to FTLD with parkinsonism without motoneuron disease and to clinically definite PD. The TDP-43 protein might be directly involved in a broader neurodegenerative spectrum, including not only motoneuron disease and FTLD but also PD.     

<Emphasis Type="Italic">hVMAT2</Emphasis>: A Target of Individualized Medication for Parkinson’s Disease

Vesicular monoamine transporter 2 (VMAT2) is responsible for sequestering cytosolically toxic dopamine into intracellular secretory vesicles. Animal genetic studies have suggested that reduced VMAT2 activity contributes to the genetic etiology of Parkinson’s disease (PD), but this role has not been established in humans. Based on human genetic association and meta-analysis, we first confirm the human VMAT2 (hVMAT2 or SLC18A2) promoter as a risk factor for PD in both family and unrelated US white people: marker rs363324 at –11.5 kb in the hVMAT2 promoter is reproducibly associated with PD in a cohort of nuclear families (p = 0.04506 in early-onset PD) and 3 unrelated US white people (meta-analysis p = 0.01879). In SH-SY5Y cells, low activity-associated hVMAT2 promoter confers high methylpiperidinopyrazole iodide cytotoxicity, which is likely attributed to functional polymorphisms bound by nuclear proteins. Interestingly, treatments with the dopamine neuron-protecting agent puerarin upregulates the promoter activity in a haplotype- and cell line-dependent manner. These pharmacogenetic findings suggest that hVMAT2 could be a risk factor and imply it as a target of genetic medications for PD.     

Alzheimer’s Disease Risk Variant rs2373115 Regulates <Emphasis Type="Italic">GAB2</Emphasis> and <Emphasis Type="Italic">NARS2</Emphasis> Expression in Human Brain Tissues

Genetic association studies have identified significant association between the GAB2 rs2373115 variant and Alzheimer’s disease (AD). However, it is unknown whether rs2373115 affects the regulation of nearby genes. Here, we evaluate the potential effect of rs2373115 on gene expression using multiple eQTL (expression quantitative trait loci) datasets from human brain tissues from the Mayo Clinic brain expression genome-wide association study (eGWAS), the UK Brain Expression Consortium (UKBEC), the Genotype-Tissue Expression (GTEx) project, and the Brain xQTL Serve. Our findings indicate that the rs2373115 C allele is associated with increased NARS2 expression, and both reduced and increased GAB2 expression in human tissues. Using a large-scale AD case-control expression dataset, we found increased GAB2 expression and reduced NARS2 expression in AD cases compared with controls. We believe that our findings provide important information regarding the rs2373115 variant and expression of nearby genes with respect to AD risk.