SNCA Methylation Research Articles

Protective effect of plastrum testudinis extract on dopaminergic neurons in a Parkinson's disease model through DNMT1 nuclear translocation and SNCA's methylation

The pathological characteristics of Parkinson's disease (PD) include dopaminergic neuron damage, specifically disorders caused by dopamine synthesis, in vivo. Plastrum testudinis extract (PTE) and its bioactive ingredient ethyl stearate (PubChem CID: 8122) were reported to be correlated with tyrosine hydroxylase (TH), which is a biomarker of dopaminergic neurons. This suggests that PTE and its small-molecule active ingredient ethyl stearate have potential for development as a therapeutic drug for PD. In this study, we treated 6-hydroxydopamine (6-OHDA)-induced model rats and PC12 cells with PTE. The mechanism of action of PTE and ethyl stearate was investigated by western blotting, bisulfite sequencing PCR (BSP), real-time PCR, immunofluorescence and siRNA transfection. PTE effectively upregulated the TH expression and downregulated the alpha-synuclein expression in both the substantia nigra and the striatum of the midbrain in a PD model rat. The PC12 cell model showed that both PTE and its active monomer ethyl stearate significantly promoted TH expression and blocked alpha-synuclein, agreeing with the in vivo results. BSP showed that PTE and ethyl stearate increased the methylation level of the Snca intron 1 region. These findings suggest that some of the protective effects of PTE on dopaminergic neurons are mediated by ethyl stearate. The mechanism of ethyl stearate may involve disrupting the abnormal aggregation of DNA (cytosine-5)-methyltransferase 1 (DNMT1) with alpha-synuclein by releasing DNMT1, upregulating Snca intron 1 CpG island methylation, and ultimately, reducing the expression of alpha-synuclein.

SNCA Hypomethylation in Rapid Eye Movement Sleep Behavior Disorder Is a Potential Biomarker for Parkinson's Disease.

α-Synuclein has been related to the pathogenesis of Parkinson's disease (PD), but it has not thoroughly been investigated in idiopathic rapid eye movement sleep behavior disorder (iRBD). We aimed to explore whether there were different distributions of α-synuclein at a genetic and/or protein level in patients with iRBD. We included 30 patients with iRBD, 30 patients with PD, and 30 age- and sex-matched healthy controls (HCs) in this study. The SNCA methylation and mRNA levels were determined using bisulfite sequencing and quantitative reverse transcription polymerase chain reaction. The plasma levels of exosome α-synuclein were measured using Meso Scale Discovery. SNCA methylation showed different distribution among HC, iRBD and PD groups (HC vs RBD: p = 0.011; HC vs PD: p < 0.001; RBD vs PD: p = 0.027). However, plasma exosomal α-synuclein levels were only elevated in patients with PD compared to those in HCs (p = 0.027), and were associated with the SNCA methylation only in the PD group (p = 0.030, r = -0.397). SNCA hypomethylation in leukocytes existed both in patients with iRBD and those with PD, indicating that SNCA methylation could be a potential biomarker for early PD diagnosis.

Epigenetic Modifications of the α-Synuclein Gene and Relative Protein Content Are Affected by Ageing and Physical Exercise in Blood from Healthy Subjects.

Epigenetic regulation may contribute to the beneficial effects of physical activity against age-related neurodegeneration. For example, epigenetic alterations of the gene encoding for α-synuclein (SNCA) have been widely explored in both brain and peripheral tissues of Parkinson's disease samples. However, no data are currently available about the effects of physical exercise on SNCA epigenetic regulation in ageing healthy subjects. The present paper explored whether, in healthy individuals, age and physical activity are related to blood intron1-SNCA (SNCAI1) methylation, as well as further parameters linked to such epigenetic modification (total, oligomeric α-synuclein and DNA methyltransferase concentrations in the blood). Here, the SNCAI1 methylation status increased with ageing, and consistent with this result, low α-synuclein levels were found in the blood. The direct relationship between SNCAI1 methylation and α-synuclein levels was observed in samples characterized by blood α-synuclein concentrations of 76.3 ng/mg protein or lower (confidence interval (CI) = 95%). In this selected population, higher physical activity reduced the total and oligomeric α-synuclein levels. Taken together, our data shed light on ageing- and physical exercise-induced changes on the SNCA methylation status and protein levels of α-synuclein.

Identification the potential of stool-based SNCA methylation as a candidate biomarker for early colorectal cancer detection

Background: Stool-based DNA methylation are emerging as promising biomarkers for colorectal cancer (CRC), but their capability for detecting curable stages (adenomas) remains unclear. This study aims to explore the potential of selected candidate biomarkers (SNCA, SPG20 and FBN1) in stool samples for identifying patients with adenomas or CRC. Methods: Thirty-one patients with CRC, 49 patients with adenomas, and 64 normal controls were selected. Stool samples were processed by the stool intestinal mucosal cells collector and analyzed by quantitative methylation-specific polymerase chain reaction (qMSP). Results: Promoter methylation status of genes was denoted as percentage of methylated reference (PMR) values. The SNCA PMR values were significantly higher in CRC and adenomas groups than normal controls. The area under the ROC curve (AUC) for SNCA was 0.836 and 0.772 for detection of CRC and adenomas, respectively. The sensitivity of stool-based SNCA methylation was 83.9% for CRC and 75.5% for adenomas, with the specificity of 75% for both. The odds ratio (OR) for CRC and adenomas with stool SNCA hypermethylation was 11.291 and 9.234, respectively, after adjustment for patients’ age and sex. Though there was a trend of increase of SNCA promoter methylation with disease progression, the difference was not significant. No significant difference in stool-based SNCA methylation was found between proximal and distal lesions. SNCA methylation significantly reduced after tumor resection compared to the initial status. The SPG20 and FBN1 methylation status was not significantly different among groups. Conclusions: The results validated the capability of SNCA methylation in stool samples for the identification of patients with adenomas or CRC.

Identification the potential of stool-based SNCA methylation as a candidate biomarker for early colorectal cancer detection

Identification the potential of stool-based SNCA methylation as a candidate biomarker for early colorectal cancer detection

Elevated mRNA Expression and Low Methylation of SNCA in Japanese Alzheimer's Disease Subjects.

Despite the continuing debate about the amyloid hypothesis in Alzheimer's disease (AD), the precise pathogenesis is still unclear. Mixed pathology is common and multiple different protein aggregates are seen in human postmortem brains. Aggregates consisting of the alpha-synuclein protein encoded by the Synuclein Alpha gene (SCNA) are common in both dementia with Lewy bodies and AD. We examined SNCA mRNA expression and methylation rates of the CpG island at intron 1 of SNCA in peripheral leukocytes in 50 AD and age- and sex-matched control subjects to verify whether alpha-synuclein pathology affects the AD pathogenesis. SNCA mRNA expression in AD subjects was significantly higher than that in control subjects (1.62±0.73 versus 0.98±0.50, p < 0.001). We found significant differences between AD and control subjects at seven CpG sites (average rate; 8.8±2.7 versus 9.5±2.5, respectively: p = 0.027). The methylation rates tended to be lower in AD subjects at all CpG sites. We conclude that mRNA expression and methylation of SNCA intron 1 are altered in AD, which may be caused by Lewy body pathology in AD.

The rs3756063 polymorphism is associated with SNCA methylation in the Chinese Han population

Parkinson's disease (PD) is the second most common neurodegenerative disorder. Genome-wide association studies have confirmed the association of single nucleotide polymorphisms (SNPs) located in the SNCA gene with the risk of PD. While hypomethylation of the SNCA intron-1 was observed in patients with sporadic PD, an association between SNCA SNPs and SNCA methylation levels has been identified. To investigate whether these SNPs are associated with the level of SNCA methylation in the Chinese population, we genotyped SNCA SNPs and analyzed the relationship between SNCA SNPs and SNCA DNA methylation status from peripheral blood mononuclear cells of Chinese Han PD patients. Our results revealed that the rs3756063 polymorphism could contribute to the risk of PD in the Chinese Han population and confirmed the effect of this polymorphism on SNCA DNA methylation. Further studies will be needed to gain a better understanding of the mechanisms underlying the associations between SNPs, methylation and PD pathogenesis.

Screening and diagnostic value of the molecular markers of DNA methylation in colorectal neoplasma

To screen the molecular markers of DNA methylation with potential diagnostic value, and to explore their methylation features in Chinese colorectal neoplasma in order to find out ones with higher diagnostic value. Tissue samples of colorectal cancer and normal adjacent mucosa(>10 cm distance to tumors) from 10 colorectal cancer patients undergoing operation, and tissue samples of colorectal adenoma from 10 patients undergoing endoscopic resection in our center from June to August 2013 were collected respectively. Methylation status of 8 genes, such as SNCA, MAL, INA, SPG20, FBN1, CNRIP1, TFPI2, OSMR, was detected by BSP and qMSP to screen genes with potential diagnostic valua. ROC curve was drawn to analyze its diagnostic value. BSP measurement showed that the rate of DNA methylation of SNCA, SPG20 and FBN1 was 100% in colorectal cancer and adenoma, while no methylation was found in normal adjacent mucosa. The other 5 genes expressed in different extent in cancer, adenoma and normal adjacent mucosa. Among 10 cancer tissues and normal adjacent mucosa detected by qMSP method, positive SNCA methylation was found in 5 cases and 1 case respectively; positive SPG20 in 8 cases and 1 case respectively; positive FBN1 in 7 cases and 0 cases respectively, whose differences were significant (P=0.070, P=0.003 and P=0.007). The area under curve(AUC) of SNCA, SPG20, and FBN1 methylation for diagnosing colorectal cancer was 0.890, 0.730 and 0.880 respectively. SNCA, SPG20 and FBN1 are potential genes with screening value for colorectal neoplasma.

DNA methylation levels of α-synuclein intron 1 in the aging brain

DNA methylation patterns change with age, and aging itself is a major confounding risk factor for Parkinson's disease (PD). Duplication and triplication, that is, increased expression of the α-synuclein (SNCA) gene, cause familial PD, and demethylation of SNCA intron 1 has been shown to result in increased expression of SNCA. We thus hypothesized that age-related alterations of SNCA methylation might underly the increased susceptibility toward PD in later life. The present study sought to determine (1) whether alterations of SNCA intron 1 methylation occurred during aging, (2) whether the methylation pattern differed between men and women, and (3) whether purified neurons compared with non-neuronal cells exhibited different methylation patterns. The analysis of DNA from brain tissue and fluorescence activated cell sorting-sorted purified neurons of 41 individuals revealed only a minor increase of SNCA intron 1 DNA methylation levels in presumably healthy individuals during aging but no significant difference between men and women. Interestingly enough, methylation of SNCA intron 1 was higher in neurons compared with non-neuronal cells, although non-neuronal cells express lower levels of SNCA. Therefore, the normal pattern of SNCA methylation during aging should not result in increased expression of α-synuclein protein. It is thus likely that additional, yet not identified, mechanisms contribute to the tissue specificity of SNCA expression and the presumed dysregulation in PD.

Detection of SNCA and FBN1 methylation in the stool as a biomarker for colorectal cancer.

Aim. We examined the methylation status of SNCA and FBN1 genes in patients' paired tissue and stool samples for detection of colorectal cancer (CRC). Patients and Methods. 89 DNA tissue samples (normal/cancer) and corresponding stool samples were analyzed in our study. In addition, 30 stool samples were collected as healthy controls. Results. The methylation level of those samples was measured by methylation-specific polymerase chain reaction (MSP). The result shows that compared with the paired controls, both SNCA and FBN1 were significantly hypermethylated in CRC patients in tissue samples (P < 0.001). In the stool samples, hypermethylated SNCA and FBN1 were detected to be significantly higher than that in normal stool samples (P < 0.001). The combined sensitivity of at least one positive among the two markers in stool samples was 84.3%, with a specificity of 93.3%. In addition, our experiment suggested that the positive rates of SNCA and FBN1 in Dukes A stage were significantly higher than that of FOBT (P = 0.039; P = 0.006, resp.). Conclusion. We concluded that methylation testing of SNCA and FBN1 genes in stool sample may offer a good alternative in a simple, promising, and noninvasive detection of colorectal cancer.

Parkinson's disease correlates with promoter methylation in the α-synuclein gene.

Genome-wide association studies have demonstrated association between SNCA variability and susceptibility to Parkinson's disease, but causal mechanisms are unclear. We hypothesized that risk variants affect methylation of a putative promoter in SNCA intron 1, previously highlighted in epigenetic studies of Parkinson's disease. We analyzed sample sets from blood (n = 72) and cerebral cortex (n = 24) in Parkinson's disease patients and healthy controls. We genotyped SNCA single-nucleotide polymorphisms, examined messenger RNA (mRNA) expression and assessed intron 1 methylation levels by methylation-sensitive restriction enzyme digestion and quantitative polymerase chain reaction (PCR). Patients showed significant hypomethylation as compared with controls in the blood sample set. In addition, rs3756063 was associated with SNCA methylation level in both blood (P = 5.9 × 10(-5)) and brain (P = 0.023). Our findings support a link between SNCA variability, promoter methylation, and Parkinson's disease risk and indicate that methylation patterns in brain are mirrored in the blood. SNCA methylation warrants further investigation as a potential biomarker.

Pyrosequencing analysis of SNCA methylation levels in leukocytes from Parkinson's disease patients

DNA methylation of a CpG island located in intron 1 of the α-synuclein gene (SNCA) has been reported to play an essential role in the regulation of α-synuclein transcription, and probably has a close association with Parkinson's disease (PD). However, there is no simple and cost effective method to quantify DNA methylation in this region. Additionally, whether this CpG island is hypomethylated in peripheral blood in PD and can be used as PD biomarker is still under debate. In the present study, we developed a set of bisulfite pyrosequencing assays which can be used to examine the DNA methylation level of 13 CpG sites in intron 1 of SNCA. We compared DNA methylation levels at these sites in leukocytes from 50 PD patients and 50 healthy controls. Our results indicated that there were no significant differences in DNA methylation between PD patients and controls.

Colorectal cancer DNA methylation marker panel validated with high performance in Non-Hodgkin lymphoma

Genes with altered DNA methylation can be used as biomarkers for cancer detection and assessment of prognosis. Here we analyzed the methylation status of a colorectal cancer biomarker panel (CNRIP1, FBN1, INA, MAL, SNCA, and SPG20) in 97 cancer cell lines, derived from 17 different cancer types. Interestingly, the genes were frequently methylated also in hematological cancer types and were therefore subjected to analyses in primary tumor samples from the major types of non-Hodgkin lymphomas (NHL) and in healthy controls. In total, the genes CNRIP1, FBN1, INA, MAL, SNCA, and SPG20 were methylated in 53%, 23%, 52%, 69%, 97%, and 92% of the tumor samples, respectively, and were unmethylated in all healthy controls. With the exception of a single tumor sample, a correct prediction of lymphoma or normal sample was made in a blinded analysis of the validation series using a combination of SNCA and SPG20. The combined ROC-curve analysis of these genes resulted in an area under the curve of 0.999 (P = 4.2 × 10−18), and a sensitivity and specificity of 98% and 100%, respectively, across the test and validation series. Interestingly, the promoter methylation of CNRIP1 was associated with decreased overall survival in diffuse large B-cell lymphoma (DLBCL) (P = 0.03). In conclusion, our results demonstrate that SNCA and SPG20 methylation might be suitable for early detection and monitoring of NHL. Furthermore, CNRIP1 could potentially be used as a prognostic factor in DLBCL.