Platelet miRNAs as early biomarkers for progression of idiopathic REM sleep behavior disorder to a synucleinopathy

Abstract

Individuals diagnosed with isolated REM sleep behavior disorder (IRBD) have a high risk of developing Lewy body disorders (LBD), mainly Parkinson's disease (PD) or dementia with Lewy bodies (DLB). As we have previously identified seven platelet-derived miRNAs as potential biomarkers for DLB, in this pilot study we aimed to investigate whether specific expression changes of these miRNAs are also present in IRBD. RNA was obtained from platelets of individuals with IRBD (n = 29) and controls (n = 34), and miRNA levels were determined with a miRCURY LNA miRNA Custom PCR Panel. miRNA interactomes of deregulated miRNAs were determined, and mRNA quantification of miRNA target genes was carried out using real-time PCR and the ΔΔCt method. We found that the expression of hsa-miR- 139 - 5p (p = 0.010) and hsa-miR- 142 - 3p (p = 0.017) was diminished, while hsa-miR- 191 - 5p (p = 0.023) was increased in platelets of IRBD patients compared with controls. Interactome analysis of these miRNAs showed that hsa-miR- 142 - 3p regulates genes related to the structure and maintenance of the cytoskeleton. Of the 15 genes expressed in platelets, the expression of WASL, a gene involved in actin filament organization, was increased in platelets of IRBD patients. Additionally, WASL expression correlated inversely with hsa-miR- 142 - 3p expression. Since the interactomes of hsa-miR- 139 - 5p and hsa-miR- 191 - 5p play a role in several cancer types, their expression was not addressed. Changes in hsa-miR- 142 - 3p, hsa-miR- 139 - 5p, and hsa-miR- 191 - 5p expression were found in IRBD platelets and might represent early biomarkers for LBD involving cytoskeleton dysfunction. Increased expression of WASL could indicate that altered platelet activation occurs early during the development of LBD.

Keywords: Biomarkers; Isolated REM sleep behavior disorder; Lewy body disorders; MiRNA expression; Platelets.

Fig. 1

Comparison of hsa-miR- 139 - 5p, hsa-miR- 142 - 3p and hsa-miR- 191 - 5p expression levels in platelets between IRBD and controls. P-value obtained by Wilcoxon-Mann-Whitney test.

Fig. 2

Comparison of hsa-miR- 139 - 5p, hsa-miR- 142 - 3p and hsa-miR- 191 - 5p expression levels in platelets between IRBD-IRBD, IRBD-PD and IRBD-DLB subgroups and controls. P-value obtained by Wilcoxon-Mann-Whitney test.

Fig. 3

Correlation between (A) miRNA expression and age at RBD onset, and (B) RBD duration before phenoconversion. Pearson correlation coefficient (R) is shown in each graph.

Fig. 4

The hsa-miR- 142 - 3p interactome (A) of the proteins expressed in platelets. (B) Proteins located in the cytoskeleton (blue), and involved in actin polymerization/depolarization (red) or G13 signaling (green).

Fig. 5

Distribution of Ct values of SNRPD and RDX gene expression for all samples. Each bar represents the number of patients corresponding to each Ct value. Samples of all three groups were included (n = 30). Normal distribution was tested with the Shapiro test.

Fig. 6

WASL expression in platelets. (A) Comparison of WASL expression levels between IRBD and controls; p-value obtained by Wilcoxon-Mann-Whitney test (B) Correlation between WASL and hsa-miR- 142 - 3p expression. Pearson correlation coefficient and p-value obtained by linear regression. Pearson correlation coefficient (R) and the corresponding p-value are shown.