Differential Expression of miRNAs in Amyotrophic Lateral Sclerosis Patients

Abstract

Amyotrophic lateral sclerosis (ALS) is a progressive motor neuron disease that affects nerve cells in the brain and spinal cord, causing loss of muscle control, muscle atrophy and in later stages, death. Diagnosis has an average delay of 1 year after symptoms onset, which impairs early management. The identification of a specific disease biomarker could help decrease the diagnostic delay. MicroRNA (miRNA) expression levels have been proposed as ALS biomarkers, and altered function has been reported in ALS pathogenesis. The aim of this study was to assess the differential expression of plasma miRNAs in ALS patients and two control populations (healthy controls and ALS-mimic disorders). For that, 16 samples from each group were pooled, and then 1008 miRNAs were assessed through reverse transcription-quantitative polymerase chain reaction (RT-qPCR). From these, ten candidate miRNAs were selected and validated in 35 ALS patients, 16 ALS-mimic disorders controls and 15 healthy controls. We also assessed the same miRNAs in two different time points of disease progression. Although we were unable to determine a miRNA signature to use as disease or condition marker, we found that miR-7-2-3p, miR-26a-1-3p, miR-224-5p and miR-206 are good study candidates to understand the pathophysiology of ALS.

Keywords: Amyotrophic lateral sclerosis; Biomarkers; Epigenetics; MicroRNAs.

Fig. 1

Venn diagram showing the miRNAs expression distribution in ALS, ALS-mimic and healthy controls populations (a) and miRNAs selected for individual analysis (b). FC, fold change

Fig. 2

Box and whisker plots of relative expression of the 8 miRNAs detected in ALS (N = 35), ALS-mimic disorders (N = 16) and healthy controls (N = 15). Dots represent mean relative expression values of each sample. Statistical significance calculated using Kruskal-Wallis test and Dunn’s multiple comparisons test. ***p value < 0.001

Fig. 3

Box and whisker plots of relative expression of the 8 miRNAs detected in ALS longitudinal samples. Dots represent mean relative expression values of each sample. Statistical significance calculated using Kruskal-Wallis test and Dunn’s multiple comparisons test. *p value < 0.05

Fig. 4

Box and whisker plots of relative expression of the statistically differently expressed miRNAs detected in a spinal (N = 26) and bulbar (N = 9) onset patients, b spinal onset patients and control groups, where HC and MD stand for healthy and ALS-mimic diseases control groups respectively, c progression rate (N (slow) = 20, N (average fast) = 15) and d slow progression patients and control groups. Dots represent mean relative expression values of each sample. Statistical significance calculated using Kruskal-Wallis test and Dunn’s multiple comparisons test. *p value < 0.05

Fig. 5

Enriched KEGG pathways of miR-224-5p, miR-26a-1-3p and miR-7-2-3p using mirPath v.3.0 package from DIANA tools. All pathways showed are significantly enriched (p value < 0.05)