CHARACTERIZATION OF THE MOLECULAR MECHANISMS LEADING TO ELAVL4/HUD ALTERED LEVELS IN OXIDATIVE STRESS CONDITIONS WITH POSSIBLE IMPLICATIONS FOR SPORADIC ALS

ELAVL4/HuD is an RNA-Binding Protein (RBP) expressed in the nervous system that plays a key role in neuronal development. It has been documented the existence of multiple Transcription Start Sites and alternative first exons in ELAVL4 gene, potentially leading to the expression of more than one transcriptional isoform through alternative splicing.
Recent works showed the involvement of HuD in the context of Amyotrophic Lateral Sclerosis (ALS), a neurodegenerative disease characterized by death of Motor Neurons (MNs). Evidence shows how in sporadic ALS patients with a signature of oxidative stress, HuD is upregulated both at mRNA and protein levels.
Previous works highlighted that cell cultures placed in oxidative stress conditions show an increase in HuD levels. Based on this evidence, it is likely that one or more HuD transcriptional isoforms may be involved in a specific oxidative stress response.
This study aims to characterize the mechanisms leading to HuD’s upregulation in sALS and investigate the potential role of the mRNA isoforms.
We tested protocols for chronic stress treatments using Sodium Arsenite on iPSC-derived co-cultures of Skeletal Muscle Cells and MNs, observing a variation in the expression levels of specific isoforms.
Interestingly, bioinformatic analyses revealed a decrease of the reads in the first intron of HuD’s transcript in acute oxidative stress conditions.
These findings suggest the existence of two different regulatory mechanisms: one acting on the splicing of the first intron under acute oxidative stress; and a second one acting on the transcription of HuD isoforms under chronic oxidative stress.