Identification of diagnostic biomarkers through analysis of peripheral blood mononuclear cells from amyotrophic lateral sclerosis patients

Amyotrophic lateral sclerosis (ALS) is a complex neurodegenerative disorder influenced by genetic, epigenetic, and environmental factors, leading to widespread dysfunction of cellular and molecular pathways. As a motor neuron disease (MND), ALS is characterized by the progressive degeneration of motor neurons in the brain and spinal cord. However, the mechanisms underlying the selective vulnerability of motor neurons remain poorly understood. This highlights an urgent need for the identification of early disease markers and common pathogenic mechanisms to develop targeted therapies, which are currently unavailable. TAR DNA-binding protein 43 (TDP-43) is a highly conserved RNA/DNA-binding protein implicated in RNA processing, including splicing, stability, and transport. In ALS, TDP-43 undergoes mislocalization from the nucleus to the cytoplasm, where it forms cytotoxic aggregates. These aggregates are thought to disrupt RNA biogenesis, contributing to disease pathogenesis. To investigate the role of TDP-43 aggregation in RNA biogenesis, we conducted a transcriptome analysis using an animal model. Specifically, total RNA from the motor cortex of five TDP-43 infused rats, and five healthy controls was subjected to RNA sequencing (RNA-seq). Comparative transcriptomic analysis revealed five differentially expressed genes (DEGs): Mctp1, Penk, Mt2A, Drd1, and Rasgrp2. To validate these findings, reverse transcription quantitative PCR (RT-qPCR) was performed. The deregulation of the identified DEGs was also confirmed in both peripheral blood mononuclear cells (PBMCs) from TDP-43 animal model and ALS patients, suggesting their potential relevance as biomarkers. Given the emerging roles of alternative splicing and microRNAs (miRNAs) in ALS pathophysiology, we further investigated these mechanisms. Alternative splicing analysis of the DEGs did not reveal any significant splicing dysregulation. However, computational analysis identified seven miRNAs, conserved in both rats and humans, that target the identified DEGs. Ongoing studies aim to validate these miRNAs as potential future disease-specific biomarkers for modulating and improving the poor diagnose of ALS patients.