Cardiac-specific overexpression of PGC-1α in transgenic mice resulted in uncontrolled mitochondrial proliferation in cardiac myocytes leading to loss of sarcomeric structure and a dilated cardiomyopathy.20 Furthermore, an increased mitochondrial respiratory capacity is intimately linked to an increased production of ROS that may further repress survival pathways, hence promoting apoptosis signaling.21 The increased number of mitochondria in PGC-1α–overexpressing neurons influences the axonal transport of these organelles thereby perturbing their normal turnover.22 This evidence concerns the gene PPARGC1A and dilated cardiomyopathy.