"Mitochondrial diseases are now considered to be among the most common forms of genetic disorders, with a minimum prevalence of 1 in 5000 individuals. They can be caused by mutations in either the nuclear or the mitochondrial DNA (mtDNA). One of the most well characterized clinical presentations is neuromuscular dysfunction, followed by cardiomyopathy, generally in the form of hypertrophic cardiomyopathy. Nowadays there are several clinical treatments approved for mitochondrial diseases. However true treatment is, with some exception, unavailable due to the complexity of the disease and the side effects observed.Several mutations involving mt-tRNA genes (mainly Leu1, Lys and Ile), mt-encoded protein and nuclear encoded protein genes have been associated with cardiomyopathy. Some of these mutations have been deeply studied in a cybrid cell culture model at the biochemistry level. However, very little is known about the signalling pathways that could lead to the development of cardiomyopathy. Mitochondrial physiology and biogenesis are deeply involved in the initiation and progression of the disease, through reactive oxygen species (ROS) production, energy deficiency and decrease in mitochondrial respirasome formation, as initial steps in the formation of the plaques. Recently, it as been demonstrated the role of some mitochondrial biogenesis-related genes, such as PGC1a, in mitochondrial fusion, pointing to the importance of the balance between mitochondrial fusion-fission in the progression of the disease. Interestingly, some of the mutations described in cardiomyopathy are very ROSgenic, strongly pointing to ROS and mitochondrial deficiency as an initial step in the onset of the cardiomyopathy.The aim of this project is to better understand the involvement of mitochondria in cardiomyopathies using different models of mitochondrial diseases that curse with increase ROS production."