ANALYSIS OF AMYLOID PRECURSOR PROTEIN (APP) LEVELS IN VITRO AND IN VIVO MODELS OF AMYOTROPHIC LATERAL SCLEROSIS

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease associated to progressive degeneration of motor neurons. Evidence points to a possible correlation between amyloid precursor protein (APP) proteolytic products and ALS pathogenesis. Most studies correlating APP metabolism with ALS have been performed in a classic in vivo model, SOD1-G93A transgenic mice. In this context, induced pluripotency stem cells (iPSCs) emerge as an innovative approach to in vitro specific genetic profiling of ALS patients. In the present work, we sought to analyze the levels of APP in in vivo and in vitro models of ALS. For in vitro analysis, neural stem cells (NSCs) obtained from iPSCs derived from Brazilian ALS patients and controls subjects were differentiated into neurons (CAAE: 60531516.0.0000.5257). For in vivo analysis, samples of regions of interest from the central nervous system of 17-week-old SOD1-G93A transgenic mice and wild-type animals were collected (CEUA: 057/23). The levels of APP were analyzed by western blotting and immunocytochemistry in both models. In vitro, our results indicate that we have an efficient protocol to differentiate NSCs from Brazilian patients with ALS into neurons and analyzes of APP levels show that this protein is higly expressed both in NSCs and neurons differentiated from iPSCs. In vivo, we showed that APP levels are increased in the cervical spinal cord of mice in the symptomatic phase of the disease, while no significative difference was detected in lumbar spinal cord or in sensorymotor cortex. This could point to an increase in APP cleavage through the amyloidogenic pathway in lower motor neurons. We have an efficient protocol for in vitro analyzes using iPSCs from Brazilian patients with ALS, that represents a tool of great relevance for future studies. In the in vivo model, we demonstrated that the levels of APP and its metabolites are altered, suggesting a possible contribution of this protein to motor degeneration in ALS.