The pathophysiology of mitochondrial biogenesis: Towards four decades of mitochondrial DNA research

Mitochondria are with very few exceptions ubiquitous organelles in eukaryot ic cells where they are essential for cell life and death. Mitochondria pla y a central role not only in a variety of metabolic pathways including the supply of the bulk of cellular ATP through oxidative phosphorylation (OXPHO S), but also in complex processes such as development, apoptosis, and aging . Mitochondria contain their own genome that is replicated and expressed wi thin the organelle. It encodes 13 polypeptides all of them components of th e OXPHOS system, and thus, the integrity of the mitochondrial DNA (mtDNA) i s critical for cellular energy supply. In the past 12 years more than 50 po int mutations and around 100 rearrangements in the mtDNA have been associat ed with human diseases. Also in recent years, several mutations in nuclear genes that encode structural or regulatory factors of the OXPHOS system or the mtDNA metabolism have been described. The development of increasingly p owerful techniques and the use of cellular and animal models are opening ne w avenues in the study of mitochondrial medicine. The detailed molecular ch aracterization of the effects produced by different mutations that cause mi tochondrial cytopathies will be critical for designing rational therapeutic strategies for this group of devastating diseases. (C) 2000 Academic Press .