Cell polarity is a fundamental feature of eukaryotic cells. The intracellular trafficking of proteins between cellular compartments and the cytoskeleton regulates the establishment and maintenance of cell polarity. These events are largely regulated by the Ras superfamily of small GTPases. Rabs (Ras-related in brain) and Arfs (ADP-ribosylation factor), subfamilies of the Ras superfamily, play a major role in coordinating vesicle formation and in mediating vesicle association with cytoskeletal components for transport of vesicles to their correct cellular compartment or membrane domain. Although these GTPases mediate membrane trafficking, how they interact with each other and effector proteins to participate in vesicle formation and transport at the trans-Golgi network (TGN) remains poorly understood. The TGN is a major sorting station for biosynthetic cargo molecules (i.e. apical and basolateral) into distinct carriers for delivery to their correct acceptor compartment. We have analyzed the role of Rab14 at the Trans-Golgi Network (TGN), apical endosomes, and in vesicle formation at the TGN by overexpressing wild type and mutant forms of Rab14 in polarized and non-polarized cells. We localized Rab14 to a domain of the TGN distinct from that of the TGN/basolateral protein, TGN38. Overexpression of inactive Rab14 causes the TGN to expand and mislocalizes the apical membrane protein VIP/MAL to the lateral membrane. Furthermore, inactive Rab14 colocalizes with Arf1-GDP at the TGN and increases the amount of COPI at the TGN. These results suggest that Rab14 is involved in the trafficking of proteins from the TGN to apical endosomes and modulates vesicle formation at the TGN by regulating Arf1 activation and COPI localization to distinct domains of the TGN. Thus, Rab14 defines a new role for COPI-mediated vesicle formation at the TGN.
| Identifer | oai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/193694 |
| Date | January 2008 |
| Creators | Kitt, Khameeka Nicole |
| Contributors | Wilson, Jean M., Gregorio, Carol, Elliott, David, St. John, Paul, Lynch, Ronald |
| Publisher | The University of Arizona. |
| Source Sets | University of Arizona |
| Language | English |
| Detected Language | English |
| Type | text, Electronic Dissertation |
| Rights | Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author. |
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