Abstract
Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease that a ects the motorsystem leading to generalized paralysis and death of patients. The understanding of early pathogenic mechanisms will help to de ne early diagnostics criteria that will eventually provide basis for e cient therapeutics. Early symptoms of ALS usually include muscle weakness or sti ness. Therefore, mechanical response of di erentiated myotubes from primary cultures of mice, expressing the ALS- causing SOD1G93A mutation, was examined by atomic force microscopy. Simultaneous acquisition of topography and cell elasticity of ALS myotubes was performed by force mapping method, compared with healthy myotubes and supplemented with immuno uorescence and qRT-PCR studies. Wildtype myotubes reveal a signi cant di erence in elasticity between a narrow and a wide population, consistent with maturation occurring with higher actin expression relative to myosin together with larger myotube width. However, this is not true for SOD1G93A expressing myotubes, where a signi cant shift of thin population towards higher elastic modulus values was observed. We provide evidence that SOD1 mutant induces structural changes that occurs very early in muscle development and well before symptomatic stage of the disease. These ndings could signi cantly contribute to the understanding of the role of skeletal muscle in ALS pathogenesis.