Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease that rapidly affects motor neurons in the brain and spinal cord. This disease, up to date, has no cure. In about 90% of cases the origin of the disease is unknown, but in 10% it is caused by Mendelian inherited genetic mutations in more than 20 genes, among which TARDBP, which codes for TDP-43, and FUS stand out. Recent findings have questioned the neurogenic origin of the disease to place it in the supporting cells of the motor neurons within the neuromuscular junction (NMJ), such as glia cells and myoblasts from skeletal muscle. In this seminar, I will present early preliminary results of my PhD project based on the study of the role of the NMJ in ALS by using Drosophila Melanogaster as animal model, with the aim of trying to clarify the pathogenic origin of the ALS disease.