Animal mitochondrial biogenesis and function: a regulatory cross-talk between two genomes

Mitochondria play a pivotal role in cell physiology, producing the cellular energy and other essential metabolites as well as controlling apoptosis by integrating numerous death signals. The biogenesis of the oxidative phosph orylation system (OXPHOS) depends on the coordinated expression of two geno mes, nuclear and mitochondrial. As a consequence, the control of mitochondr ial biogenesis and function depends on extremely complex processes that req uire a variety of well orchestrated regulatory mechanisms. It is now clear that in order to provide cells with the correct number of structural and fu nctional differentiated mitochondria, a variety of intracellular and extrac ellular signals including hormones and environmental stimuli need to be int egrated. During the last few years a considerable effort has been devoted t o study the factors that regulate mtDNA replication and transcription as we ll as the expression of nuclear-encoded mitochondrial genes in physiologica l and pathological conditions. Although still in their infancy, these studi es are starting to provide the molecular basis that will allow to understan d the mechanisms involved in the nucleo-mitochondrial communication, a cros s-talk essential for cell life and death. (C) 2001 Elsevier Science Inc. Al l rights reserved.