APOPTOSIS IN METABOLIC MYOPATHIES

DNA fragmentation, the hallmark of apoptosis, has been recently invest igated with contradictory results in several skeletal muscle disorders . Using in situ labeling of nuclear DNA fragmentation, we have tested the possibility that apoptosis might occur in muscles from patients wi th mitochondrial respiratory chain defects and other types of metaboli c myopathies. A high proportion of apoptotic myonuclei were found in a ll of 10 patients with mitochondrial myopathies and in one patient wit h multiple acyl-CoA dehydrogenase deficiency, a disease also affecting mitochondrial metabolism. These findings can be related to the intrig uing link existing between apoptosis and mitochondria. It has been dem onstrated that a fall of mitochondrial membrane potential constitutes a critical early event in the apoptotic process, and that mitochondria l bcl-2 protein, which protects from apoptosis, apparently functions a s an endogenous permeability transition inhibitor. NeuroReport 9: 2431 -2435 (C) 1998 Rapid Science Ltd.