UC Irvine

Abstract of dissertation

Re-evaluating the Functional Significance of Golgi Ribbon Structure and Pericentrosomal Positioning

By

Kati Tormanen

Doctor of Philosophy in Biological Sciences, University of California, Irvine

Professor Christine Sütterlin, Chair

This study examines the significance of Golgi ribbon structure and pericentrosomal positioning for microtubule organization and higher cellular functions such as protein transport, directional migration and primary cilia formation. Because the centrosome and Golgi are both microtubule organizing centers (MTOCs), and the structure and protein composition of both organelles is dependent on microtubules, it has been challenging to determine the exact role of each organelle. We took two approaches to dissect the relationship between microtubules and Golgi ribbon structure and positioning. In the first approach we attempted to determine if Golgi ribbon structure is necessary for microtubule organization and function by disrupting the Golgi ribbon. This work identified a novel component in the microtubule nucleation and organization pathway. In the second approach, we selectively disconnected the close association between the Golgi and the centrosome without disrupting Golgi or microtubule organization to determine the significance of this unique association in mammalian cells. We found that cells with a loss of Golgi-centrosome proximity had apparently normal microtubule organization, were able migrate directionally and form a primary cilium. This suggests that Golgi-centrosome proximity is not necessary for cell homeostasis.