Can endogenous gaseous messengers control mitochondrial biogenesis in mammalian cells?

Mitochondria have been identified as the site of oxidative energy metabolism and of numerous biosynthetic and degradative reactions, which depend on a distinctive mitochondrial structure, with different enzymes and reactions localised in discrete membranes and aqueous compartments. Synthesis and import of mitochondrial components are required for mitochondrial proliferation, but rather than producing new organelles, these processes may facilitate the growth of preexisting mitochondria. Recent evidence indicates that these events are regulated in a complex way by several agonists and environmental conditions, through activation of specific transcription factors and signaling pathways. Some of these are now being elucidated. Generation of nitric oxide (NO) appears to be a novel player in this scenario, possibly acting as a unifying molecular switch to trigger the whole process of the mitochondrial biogenesis. (C) 2004 Elsevier Inc. All rights reserved.