Thesis (Ph. D.)--Case Western Reserve University, 2006. / [School of Medicine] Department of Molecular Biology and Microbiology. Includes bibliographical references. Available online via OhioLINK's ETD Center.

Thesis (Ph.D.) -- University of Texas Southwestern Medical Center at Dallas, 2005. / Embargoed. Vita. Bibliography: 91-96.

Thesis (Ph.D.)--McMaster University, 2004. / Advisor: Professor J. P. Capone. Includes bibliographical references (leaves 168-189). Also available via World Wide Web.

Thesis (Ph. D.)--University of Washington, 2005. / Vita. Includes bibliographical references (leaves 128-153).

Thesis (Ph. D.)--Case Western Reserve University, 2006. / [School of Medicine] Department of Environmental Health Sciences. Includes bibliographical references. Available online via OhioLINK's ETD Center.

Thesis (Ph.D. in Molecular Biology) -- University of Colorado, 2006. / Typescript. Includes bibliographical references (leaves 126-147). Free to UCDHSC affiliates. Online version available via ProQuest Digital Dissertations;

The work presented here describes novel functions for centrosome proteins, specifically for pericentrin and centriolin. The first chapter describes the involvement of pericentrin in ciliogenesis. Cells with reduced pericentrin levels were unable to form primary cilia in response to serum starvation. In addition we showed novel interactions between pericentrin, intraflagellar transport (IFT) proteins and polycystin 2 (PC2). Pericentrin was co-localized with IFT proteins and PC2 to the base of primary cilia and motile cilia. Ciliary function defects have been shown to be involved in many human diseases and IFT proteins and PC2 have been implicated in these diseases. We conclude that pericentrin is required for assembly of primary cilia possibly as an anchor for other proteins involved in primary cilia assembly. The second chapter describes identification of centriolin, a novel centriolar protein that localizes to subdistal appendages and is involved in cytokinesis and cell cycle progression. Depletion of centriolin leads to defects in the final stages of cytokinesis, where cells remain connected by thin intercellular bridges and are unable to complete abscission. The cytokinesis defects seemed to precede the G0/G1 p53 dependant cell cycle arrest. Finally, the third chapter is a continuation of the cytokinesis study and it identifies pericentrin as an interacting partner for centriolin. Like centriolin, pericentrin knockdown induces defects in the final stages of cytokinesis and leads to G0/G1 arrest. Moreover, pericentrin and centriolin interact biochemically and show codependency in their centrosome localization. We conclude that pericentrin and centriolin are members of the same pathway and are necessary for the final stages of cytokinesis.

Although much progress has been made in understanding the events that lead to successful cell division, many details of this process remain a mystery. This dissertation presents findings which help to explain events that occur in the latest stages of cytokinesis, with an emphasis on the role of centrosome proteins. The first chapter introduces the novel centrosome protein centriolin. We show that this protein is localized specifically to the subdistal appendages of the maternal centriole in interphase, and it localizes to the midbody during cytokinesis. Disruption of this protein results in a unique cytokinesis defect in which cleavage furrow formation and ingression appear normal, but the cells remain connected by a thin intracellular bridge for extended periods of time. These results lead us to the conclusion that centriolin has an important function in cytokinesis. The second chapter describes our attempt to identify centriolin interacting partners. A yeast two hybrid screen was performed, and the results of this screen revealed an interaction between centriolin and proteins involved in vesicle target specificity and fusion. Further studies of these proteins revealed a novel localization to the midbody in cycling cells and a novel function in the final stages of cytokinesis, similar to centriolin. The third chapter discusses my attempts to clone and characterize a novel GTPase Activating Protein (GAP), which was also discovered in the screen for centriolin interacting proteins.

This work addresses the mechanism of cell cycle specific actin reorganization in Drosophila syncytial blastoderm embryos. During mitosis in typical animal cells after chromosome segregation is complete, daughter cells are separated in a process called cytokinesis. Cytokinesis is ordinarily driven by constriction of an actin ring that physically pinches the cell in two. The early Drosophila embryo is a syncytium; nuclei divide in a single cell without intervening cytokinesis. During the later syncytial divisions, nuclei are arranged in a monolayer at the cortex of the embryo. This stage of embryogenesis is characterized by cycles of actin reorganization that are coordinated with the nuclear division cycles. Since several components of typical cleavage furrows function in this cell cycle driven actin reorganization, the syncytial blastoderm has been used as a model system to better understand cell cycle driven actin reorganization in typical cells. The syncytial Drosophila embryo is easily manipulated genetically, cytoskeletal structures can be visualized in both fixed and living embryos, and large quantities of embryos are attainable for biochemical analysis. We have therefore chosen this model system to study actin reorganization. We show that actin reorganization in syncytial embryos is coordinated by cell cycle cues similar to those utilized in typical cells. Drosophila embryo actin reorganization has several unique features, however. For instance, actin reorganization appears to be associated with centrosomes in a process that does not require microtubules. In addition, the driving force for formation of Drosophila cleavage structures may be actin filament polymerization, rather than contraction of an acto-myosin ring. Whether these characteristics of Drosophila embryo actin reorganization typifies actin reorganization in other cells remains to be seen.

Diss. (sammanfattning) Stockholm : Karol inst., 2004. / Härtill 4 uppsatser.