Review Moving Mitochondria: Establishing Distribution of an Essential Organelle

Mitochondria form a dynamic network responsible for energy production, calcium homeostasis and cell signal-ing. Appropriate distribution of the mitochondrial net-work contributes to organelle function and is essential for cell survival. Highly polarized cells, including neurons and budding yeast, are particularly sensitive to defects in mitochondrial movement and have emerged as model systems for studying mechanisms that regulate organelle distribution. Mitochondria in multicellular eukaryotes move along microtubule tracks. Actin, the primary cytoskeletal component used for transport in yeast, has more subtle functions in other organisms. Kinesin, dynein and myosin isoforms drive motor-based movement along cytoskeletal tracks. Milton and synta-bulin have recently been identified as potential organelle-specific adaptor molecules for microtubule-based motors. Miro, a conserved GTPase, may function with Milton to regulate transport. In yeast, Mmr1p and Ypt11p, a Rab GTPase, are implicated in myosin V-based mitochondrial movement. These potential adaptors could regulate motor activity and therefore determine individual organ-elle movements. Anchoring of stationary mitochondria also contributes to organelle retention at specific sites in the cell. Together, movement and anchoring ultimately determinemitochondrial distribution throughout the cell. Key words: axonal transport, dynein, kinesin, mitochon-dria, myosin, organelle movement Received 3 July 2007, revised and accepted for publica-tion 23 August 2007, uncorrected manuscript publishe