Alves, Ana Mafalda Laranjo2026-02-132026-02-132025http://hdl.handle.net/10400.5/117062Tese de mestrado, Biologia Molecular e Genética, 2025, Universidade de Lisboa, Faculdade de CiênciasLAMA2-Congenital Muscular Dystrophy (LAMA2-CMD) is characterized by mutations in the LAMA2 gene, coding for the laminin α2 chain, an important component of the skeletal muscle extracellular matrix (ECM). Previous work from the host laboratory and colleagues showed that LAMA2-CMD has phenotypic alterations, already at embryonic day 17.5 (E17.5) in dyW fetuses, a wellestablished mouse model for LAMA2-CMD. However, whether cellular/molecular alterations start earlier and if other unexplored pathways involved in muscle development are altered and contribute to LAMA2-CMD onset remain unknown. In muscle development, there are different pathways linking ECM to cells, promoting signaling cascades. One example is the AKT pathway, which is involved in proliferation and differentiation processes. Thus, we aimed at investigating whether AKT contributes to the muscle defects at E17.5. AKT activation was also evaluated in Lama2-deficient C2C12 myoblasts. In addition, we complemented the analysis in E17.5 by determining whether AKT activation was compromised at an earlier stage (E16.5). The results showed no alterations in AKT activation neither at E16.5 nor at E17.5 in dyW embryos when compared to WT counterparts. Similarly, Lama2-deficient C2C12 myoblasts showed similar AKT activation when compared to WT cells. To broaden the analysis of E17.5 phenotype, an immunofluorescence protocol was established, and proliferation was evaluated in E17.5 dyW embryos. The results indicated no differences in proliferation between WT and dyW fetuses, but more samples need to be added. Finally, to answer the question of when LAMA2-CMD starts, several markers altered at E17.5 were analyzed in E16.5 dyW fetuses. This analysis revealed no significant differences between WT and dyW fetuses, concluding that phenotypic and cellular/molecular alterations start at E17.5. Overall, understanding the mechanisms underlying LAMA2-CMD will allow the scientific community to advance in the study of novel therapeutic approaches and clinical consensus guidelines to implement standards of care.application/pdfengLAMA2-CMDAKTMuscle DevelopmentDisease OnsetExtracellular Matrixmaster thesis204172926