Deregulation of Plasma microRNA Expression in a TARDBP-ALS Family

TDP-43 intracellular aggregates are a pathogenic sign of most amyotrophic lateral sclerosis (ALS) cases. Familial ALS, brought on by TARDBP gene mutations, emphasizes the relevance of this altered protein in pathophysiology. Growing evidence suggests a role for dysregulated microRNA (miRNA) in ALS disease. Furthermore, several studies showed that miRNAs are highly stable in various biological fluids (CSF, blood, plasma, and serum), and they are expressed differentially by comparing ALS patients and controls. In 2011, our research group discovered a rare mutation in a TARDBP gene (G376D) in a large ALS Apulian family with affected members exhibiting a rapidly progressing disease. To identify potential non-invasive biomarkers of preclinical and clinical progression in the TARDBP-ALS family, we assessed the expression levels of plasma microRNAs in affected patients (n = 7) and asymptomatic mutation carriers (n = 7) compared with healthy controls (n = 13). Applying qPCR, we investigate 10 miRNAs that bind TDP-43 in vitro during their biogenesis or in their mature form, and the other nine are known to be deregulated in the disease. We highlight the potential of miR-132-5p, miR-132-3p, miR-124-3p, and miR-133a-3p expression levels in plasma as biomarkers of preclinical progression for G376D-TARDBP-associated ALS. Our research strongly supports the potential of plasma miRNAs as biomarkers for performing predictive diagnostics and identifying new therapeutic targets.