What's new in cytoskeleton-organelle interactions? Relationship between microtubules and the Golgi-apparatus

Several biochemical processes in animal cells are confined to distinct membrane-bounded compartments. Segregation of specialized functions into different compartments necessitates intercompartment transfer of material. This transfer is mediated by carrier vesicles which, by precise sorting and transport mechanisms, are targetted to their correct destinations. Microtubules, major constituents of the cytoskeleton, are involved both in these intracellular transport processes and in the spatial organization of cytoplasmic organelles. Accumulating evidence suggests that various classes of membranous organelles interact with microtubules. The positioning of several organelles, including the Golgi apparatus and lysosomes, depends on an intact interphase microtubule network. Furthermore, it has been shown that many of these organelles, for example Golgi elements, tubules of the endoplasmic reticulum, exocytic or secretory vesicles and lysosomes move along microtubules. In this article we will discuss the role of microtubules in the movement and positioning of elements of the Golgi complex. The first part will summarize structural and functional aspects of microtubules and the Golgi apparatus and review evidence for their interaction. In the second part, the possible physiological relevance of this interaction will be discussed and correlated with other membrane-microtubule interactions. Finally, emerging questions and perspectives in this field are outlined.