Elena V. Filatova

N1-acetyl-N2-formyl-5-methoxykynuramine is a product of melatonin oxidation in rats

Abstract: The product of melatonin oxidation, N1‐acetyl‐N2‐formyl‐5‐methoxykynuramine (AFMK), was synthesized and a method for its determination in biological samples was developed. High performance liquid chromatography (HPLC) with fluorescence detection provided good sensitivity and selectivity. Wavelengths of 350 and 480 nm were used for excitation and emission, respectively. Serum and retinal homogenates were extracted with chloroform prior to analysis by HPLC. Endogenous AFMK was detected in the retina of rats but the serum concentration of this melatonin metabolite was below the detection limit of the method for measurement. Retinal AFMK concentration was higher during the dark phase of the light/dark cycle, when the retinal melatonin content is maximal. Intraperitoneal administration of melatonin significantly increased serum and retinal AFMK levels. Formation of AFMK from melatonin was also confirmed by in vivo microdialysis with the probe implanted into the brain lateral ventricle. The study shows that AFMK is indeed a product of melatonin oxidation in vivo. The possible physiological significance of melatonin oxidation metabolic pathway is discussed.

MicroRNAs: Possible role in pathogenesis of Parkinson’s disease

Parkinson’s disease is one of the most common human neurodegenerative disorders caused by the loss of dopaminergic neurons from the substantia nigra pars compacta of human brain. However, causes and mechanisms of the progression of the disease are not yet fully clarified. To date, investigation of the role of miRNAs in norm and pathology is one of the most intriguing and actively developing areas in molecular biology. MiRNAs regulate expression of a variety of genes and can be implicated in pathogenesis of various diseases. Possible role of miRNAs in pathogenesis of Parkinson’s disease is discussed in this review.

miRNA expression is highly sensitive to a drug therapy in Parkinson's disease.

BACKGROUND miRNAs may play a role in the pathogenesis of Parkinsons disease. It is necessary to continue the search for new miRNAs that may affect the development of neurodegeneration in Parkinsons disease. METHODS 20 untreated patients with Parkinsons disease and 18 treated patients with Parkinsons disease (Hoehn and Yahr scores 1-2) were studied. An analysis of the levels of 11 miRNAs in the peripheral blood lymphocytes of patients was carried out using reverse transcription followed by real-time PCR. RESULTS The levels of miR-7, miR-9-3p, miR-9-5p, miR-129, and miR-132 were increased by more than three times in treated patients with Parkinsons disease compared with those of the controls. CONCLUSIONS It is probable that miRNAs are very sensitive to drug therapy and that the effects of therapy observed may be associated with changes in the levels of these miRNAs and their target genes in patients with Parkinsons disease.

Involvement of endocytosis and alternative splicing in the formation of the pathological process in the early stages of Parkinson's disease.

Parkinsons disease (PD) is the one of most widespread neurodegenerative pathologies. Because of the impossibility of studying the endogenous processes that occur in the brain of patients with PD in the presymptomatic stage, the mechanisms that trigger the disease remain unknown. Thus, the identification of the processes that play an important role in the early stages of the disease in these patients is extremely difficult. In this context, we performed a whole-transcriptome analysis of the peripheral blood of untreated patients with stage 1 PD (Hoehn-Yahr scale). We demonstrated a significant change in the levels of transcripts included in the large groups of processes associated with the functioning of the immune system and cellular transport. Moreover, a significant change in the splicing of genes involved in cellular-transport processes was shown in our study.

Expression analysis of suppression of tumorigenicity 13 gene in patients with Parkinson's disease.

Parkinsons disease (PD) is the second most common progressive neurodegenerative disorder characterized by the degeneration of dopaminergic neurons. Detecting changes in gene expression in untreated de novo patients with PD is important for understanding disease pathogenesis and for identifying biomarkers for preclinical stage of PD. In this study we investigate ST13 gene expression in the peripheral blood of different groups of patients with neurological diseases using reverse transcription reaction and real-time polymerase chain reaction (PCR). Our results suggest that the expression levels of ST13 cannot serve as a biomarker for early stages of PD.

Transcriptome Profile Changes in Mice with MPTP-Induced Early Stages of Parkinson's Disease.

Parkinson’s disease (PD) is one of the most common neurodegenerative diseases. Despite progress in the study of the molecular, genetic, and pathogenic mechanisms of PD, it is unclear which processes trigger the development of the pathology associated with PD. Models of the presymptomatic and early symptomatic stages of PD induced by MPTP have been used to analyze changes in transcriptome profile in brain tissues, to identify specific patterns and mechanisms underlying neurodegeneration in PD. The whole-transcriptome analysis in the brain tissues of the mice with MPTP-induced PD showed that striatum is involved in the pathogenesis in the earliest stages and the processes associated with vesicular transport may be altered. The expression profiles of the genes studied in the substantia nigra and peripheral blood confirm that lymphocytes from peripheral blood may reflect processes occurring in the brain. These data suggest that messenger RNA (mRNA) levels in peripheral blood may provide potential biomarkers of the neurodegeneration occurring in PD. The changes in expression at the mRNA and protein levels suggest that Snca may be involved in neurodegeneration and Drd2 may participate in the development of the compensatory mechanisms in the early stages of PD pathogenesis. Our data suggest that the brain cortex may be involved in the pathological processes in the early stages of PD, including the presymptomatic stage.

Polymorphisms in the SNCA Gene: Association with the Risk of Development of the Sporadic Form of Parkinson's Disease and the Level of SNCA Gene Expression in Peripheral Blood of Patients from Russia

Parkinson’s disease (PD) is one of the most common human neurodegenerative disorders caused by the loss of dopaminergic neurons in the brain. The α-synuclein (SNCA) gene is one of the most studied genes involved in the pathogenesis of PD. In our study, we conducted a genetic analysis of promoter and intron single-nucleotide polymorphisms (SNPs) in the SNCA gene. We also analyzed the association of genotypes of these SNPs with expression levels of SNCA mRNA. One of four SNPs in the SNCA gene, and the rs2736990 polymorphism, associates with the risk of the sporadic form of PD in Russian population. The risk of PD was increased almost twofold in carriers of allele C (odds ratios = 1.9, 95% confidence interval: 1.2-2.91, p = 0.003). However, no association was found between any of the genotypes of SNPs tested (rs2583988, rs2619363, rs2619364 and rs2736990) and alterations in SNCA levels. Our findings support the hypothesis that the rs2736990 polymorphism is associated with PD. SNPs rs2583988, rs2619363 and rs2619364 in the promoter region of the SNCA gene themselves do not significantly influence the expression of SNCA. Most likely, SNCA gene expression is a very complex process that is affected by different genetic and epigenetic factors.

Potential Biomarkers of the Earliest Clinical Stages of Parkinson's Disease.

Parkinsons disease (PD) is a widespread neurodegenerative disorder. Despite the intensive studies of this pathology, in general, the picture of the etiopathogenesis has still not been clarified fully. To understand better the mechanisms underlying the pathogenesis of PD, we analyzed the expression of 10 genes in the peripheral blood of treated and untreated patients with PD. 35 untreated patients with PD and 12 treated patients with Parkinsons disease (Hoehn and Yahr scores 1-2) were studied. An analysis of the mRNA levels of ATP13A2, PARK2, PARK7, PINK1, LRRK2, SNCA, ALDH1A1, PDHB, PPARGC1A, and ZNF746 genes in the peripheral blood of patients was carried out using reverse transcription followed by real-time PCR. A statistically significant and specific increase by more than 1.5-fold in the expression of the ATP13A2, PARK7, and ZNF746 genes was observed in patients with PD. Based on these results, it can be suggested that the upregulation of the mRNA levels of ATP13A2, PARK7, and ZNF746 in untreated patients in the earliest clinical stages can also be observed in the preclinical stages of PD, and that these genes can be considered as potential biomarkers of the preclinical stage of PD.

Analysis of mutations in patients with suspected autosomal dominant forms of Parkinson’s disease

Parkinson’s disease (PD) is a severe neurological disorder pathogenesis of which involves various genetic systems and environmental factors. However, despite extensive research on this disease, its causes remain incompletely elucidated and the exact range of genes and mutations involved in pathogenesis of the hereditary forms of PD has not yet been fully clarified. The present work is devoted to the analysis of mutations that lead to development of monogenic forms of PD in patients with the suspected autosomal dominant form of PD using multiplex ligation-dependent probe amplification (MLPA). We have identified several mutations (G2019S in LRRK2, heterozygous deletions of 2–3, 3–4 exons and heterozygous duplication of 2–4 exons in the PARK2 gene, deletion of the 3 exon in the PARK7 gene) that lead to development in only 7 people out of 70 (18.4%), which suggests the need for further research on new mutations, for example, using exome sequencing. In the future, this will help in developing molecular genetic tests for early preclinical diagnostics and risk evaluation of PD and understanding the causes and mechanisms of this disease better.

Expression of GSK3B in peripheral blood of patients with Parkinson’s disease

Parkinson’s disease (PD) is the second most common progressive neurodegenerative disorder characterized by the degeneration of dopaminergic neurons. Detecting changes in gene expression in untreated de novo patients with PD is important for understanding the disease pathogenesis and for identifying biomarkers of the preclinical stage of PD. In this study, the expression of the glycogen synthase kinase-3 beta gene (GSK3B) was investigated in the peripheral blood of several groups of neurological patients using reverse transcription reaction and real-time PCR. Our results suggest that the GSK3B expression level cannot serve as a biomarker for early stages of PD.