METTL14 is decreased and regulates m6 A modification of α-synuclein in Parkinson's disease.

N6-methyladenosine (m6A), an emerging modification of messenger RNA, has been implicated in many biological processes. However, its role in Parkinson's disease (PD) remains largely unknown. Here, we investigated the role of m6A modification and its underlying mechanism in PD. First, 86 individuals with PD and 86 healthy controls were recruited from a pilot multicenter cohort. Levels of m6A and its modulators in peripheral blood mononuclear cells of patients with PD and controls were measured using an m6A RNA methylation quantification kit and quantitative real-time PCR. The underlying mechanism of m6A modification in PD was investigated in vitro through RNA immunoprecipitation assay, RNA stability assay, gene silencing or overexpression, western blot, and confocal immunoassay. The results show that mRNA levels of m6A, METTL3, METTL14, and YTHDF2 in patients with PD were significantly lower than in healthy controls, and METTL14 was the main factor involved in abnormal m6A modification. Area under the curve (AUC) analysis suggests METTL14 may provide excellent diagnostic capability for PD, especially when combined with plasma α-synuclein (α-syn). Spearman correlation analysis identified that METTL14 was moderately negatively correlated with plasma α-syn and the motor function of PD. Mechanistic experiments demonstrated that Mettl14 targets and regulates the expression of the α-syn gene using its methylation function. Overexpression of Mettl14 dramatically increased m6 A modification of α-syn mRNA and weakened its stability. Further results suggest that α-syn mRNA was modified by Mettl14 binding of an m6 A motif in the coding region of α-syn mRNA, while the reading protein Ythdf2 was involved in recognizing m6 A-modified α-syn mRNA. Taken together, our results reveal the potential of METTL14 as a novel diagnostic biomarker for PD and identify modification of pathogenic α-syn protein by METTL14 via an m6 A-YTHDF2-dependent mechanism.

Losigamone add-on therapy for focal epilepsy.

BACKGROUND: Epilepsy is a common neurologic disorder, affecting approximately 50 million people worldwide; nearly a third of these people have epilepsy that is not well controlled by a single antiepileptic drug (AED) and they usually require treatment with a combination of two or more AEDs. In recent years, many newer AEDs have been investigated as add-on therapy for focal epilepsy; losigamone is one of these drugs and is the focus of this systematic review. This is an update of a Cochrane Review first published in 2012 and updated in 2018. OBJECTIVES: To investigate the efficacy and tolerability of losigamone when used as an add-on therapy for focal epilepsy. SEARCH METHODS: For the latest update on 20 August 2019, we searched the Cochrane Register of Studies (CRS Web) and MEDLINE. CRS Web includes randomized or quasi-randomized, controlled studies from the Specialized Registers of Cochrane Review Groups including Cochrane Epilepsy, CENTRAL, PubMed, Embase, ClinicalTrials.gov, and the World Health Organization International Clinical Trials Registry Platform (ICTRP). Previously we searched trials registers and contacted the manufacturer of losigamone and authors of included studies for additional information. We did not impose any language restrictions. SELECTION CRITERIA: Randomized controlled, add-on studies comparing losigamone with placebo for focal epilepsy. DATA COLLECTION AND ANALYSIS: Two review authors independently assessed study quality and extracted data. The primary outcomes were 50% or greater reduction in seizure frequency and seizure freedom; the secondary outcomes were treatment withdrawal and adverse events. Results are presented as risk ratios (RRs) with 95% confidence intervals (CIs) or 99% CIs (for the individual listed adverse events to make an allowance for multiple testing). MAIN RESULTS: Two studies involving a total of 467 participants, aged over 18 years, were eligible for inclusion. Both studies assessed losigamone 1200 mg/day or 1500 mg/day as an add-on therapy for focal epilepsy. We assessed one study as being of good methodological quality while the other was of uncertain quality. For the efficacy outcomes, results showed that participants taking losigamone were significantly more likely to achieve a 50% or greater reduction in seizure frequency (RR 1.76, 95% CI 1.14 to 2.72; 2 studies, 467 participants; moderate-quality evidence), but associated with a significant increase of treatment withdrawal when compared with those taking placebo (RR 2.16, 95% CI 1.28 to 3.67; 2 studies, 467 participants; moderate-quality evidence). For the tolerability outcomes, results indicated that the proportion of participants who experienced adverse events in the losigamone group was higher than in the placebo group (RR 1.34, 95% CI 1.00 to 1.80; 2 studies, 467 participants; moderate-quality evidence). Dizziness was the only adverse event significantly reported in relation to losigamone (RR 3.82, 99% CI 1.69 to 8.64; 2 studies; 467 participants; moderate-quality evidence). Neither study reported the proportion of participants achieving seizure freedom. A subgroup analysis according to different doses of losigamone showed that a higher dose of losigamone (1500 mg/day) was associated with a greater reduction in seizure frequency than lower doses, but was also associated with more dropouts due to adverse events. AUTHORS' CONCLUSIONS: The results of this review showed that losigamone did reduce seizure frequency but was associated with more treatment withdrawals when used as an add-on therapy for people with focal epilepsy. However, the included studies were of short-term duration and uncertain quality. Future well-designed randomized, double-blind, placebo-controlled studies with a longer-term duration are needed. We did not find any new studies since the last version of this review. We judged the overall quality of the evidence for the outcomes assessed as moderate.

The emerging role of circular RNAs in Parkinson's disease.

Parkinson's disease (PD) is the second most prevalent neurodegenerative disease and the most common movement disorder. It involves a gradual loss of dopaminergic neurons in the substantia nigra. Although many studies have been conducted, the underlying molecular pathways of PD remain largely unknown. Circular RNAs (circRNAs), a novel class of non-coding RNAs with a covalently closed loop structure, are common in the brain. They are stable, conserved molecules that are widely expressed in eukaryotes in tissue-, cell-, and development-specific patterns. Many circRNAs have recently been identified in nervous system diseases, and some circRNA expression profiles have been linked to PD. Given that recent research has indicated the essential roles of various circRNAs in the development and progression of neurodegenerative diseases, the identification of individual circRNAs may be a promising strategy for finding new treatment targets for PD. Moreover, the search for circRNAs with high specificity and sensitivity will open up new avenues for the early diagnosis and treatment of PD. Herein, we address the biogenesis, properties, and roles of circRNAs and review their potential utility as biomarkers and therapeutic targets in PD.

The Potential Circular RNAs Biomarker Panel and Regulatory Networks of Parkinson's Disease.

Parkinson's disease (PD) is a progressive neurodegenerative disease. It has been reported that circular RNAs (circRNAs) play important roles in several neurological diseases. However, the role and regulatory networks of circRNAs in PD are still largely unclear. In this study, we first compared the global expression level of circRNAs from patients with PD and controls using microarray, then the candidate circRNAs were validated in another PD cohort. The possible functions of these candidate circRNAs were analyzed using Gene Ontology (GO) analyses and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses, and the regulatory networks of these candidate circRNAs were constructed through circRNA-miRNA-mRNA regulatory networks, protein-protein interaction (PPI) networks, and transcription factor-circRNA networks. The results indicated that hsa_circRNA_101275, hsa_circRNA_103730, and hsa_circRNA_038416 were significantly more highly expressed in patients with PD, while hsa_circRNA_102850 was lower expressed in patients with PD when compared with controls. A circRNA panel combining the four differentially expressed circRNA showed a high diagnostic ability to distinguish patients with PD from controls (AUC = 0.938). Furthermore, GO and KEGG analysis showed these candidate circRNAs were enriched in PI3K-Akt and MAPK signaling pathways. We established circRNA-miRNA-mRNA regulatory networks and identified 10 hub genes (ESR1, PTEN, SHC1, IGF1R, SMAD2, KRAS, MDM2, HIF1A, BMP4, and ACVR2B) were closely related to PD by using PPI network analysis. Besides, these circRNAs were predicted to be regulated through tyrosine hydroxylase (TH)-relevant transcription factors such as GATA2 and GATA3. In conclusion, our results suggest that the circRNA panel and the established circRNA-miRNA-mRNA regulation networks might provide potential novel biomarkers and therapeutic targets for PD.

Decreased soluble Nogo-B in serum as a promising biomarker for Parkinson's disease.

Background: Recently, the neurite outgrowth inhibitor-B (Nogo-B) receptor has been reported as a novel candidate gene for Parkinson's disease (PD). Nogo-B receptors need to combine with soluble Nogo-B to exert their physiological function. However, little is known about the relationship between serum soluble Nogo-B and PD. Methods: Serum levels of sNogo-B and α-Synuclein (α-Syn) were measured in a cohort of 53 patients with PD and 49 healthy controls with the ELISA kit method. Results: Serum sNogo-B level is significantly lower in the PD group than that in healthy controls and is negatively correlated with UPDRS-III score (p = 0.049), H&Y stage (p = 0.0108) as well as serum α-Syn level (p = 0.0001). The area under the curve (AUC) of serum sNogo-B in differentiating patients with PD from controls was 0.801 while the AUC of serum α-Syn was 0.93. Combining serum sNogo-B and α-Syn in differentiating patients with PD from HC presented higher discriminatory potential (AUC = 0.9534). Conclusion: Decreased serum sNogo-B may be a potential biomarker for PD. Lower Nogo-B level reflects worse motor function and disease progression of PD. Serum sNogo-B is of added value to serum α-Syn panel in distinguishing PD from controls. Future studies are needed to confirm in larger samples and different populations.

Genome-wide identification of m6A-associated single-nucleotide polymorphisms in Parkinson's disease.

N6-methyladenosine (m6A)-associated single nucleotide polymorphisms (SNPs) play a vital role in several neurological diseases. However, little is known about the relationship between m6A modification and Parkinson's disease (PD). We investigated potential functional variants of m6A-SNPs from large-scale genome-wide association studies (GWAS) in PD patients. The candidate m6A-SNPs were further assessed by expression quantitative trait loci (eQTL) analysis and differential gene expression analysis. We identified 12 m6A-SNPs that were significantly associated with PD risk. Further, eQTL and expression analyses identified five of these m6A-SNPs (rs75072999 of GAK, rs1378602, rs4924839 and rs8071834 of ALKBH5, and rs1033500 of C6orf10) that were associated with altered gene expression in PD. Our results suggest that m6A-SNPs could play a role in PD risk. Future studies are needed to confirm these PD-associated m6A-SNPs and elucidate their mechanisms.