Date of Award

8-26-2022

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Biology

Advisor(s)

Heidi Hehnly

Subject Categories

Biology | Life Sciences

Abstract

Coordination of cell division, cellular epithelialization and ciliogenesis is necessary for tissue development in vivo. We argue that the process of epithelialization and ciliogenesis requires positioning the centrosomes to specific cellular locales. We identified that the centrosome can be repositioned to these locales in a Rab11-dependent manner towards the cytokinetic bridge during abscission and to the apical membrane for cilia formation. Rab11 is an essential GTPase that is involved in regulating abscission, cleavage of the cytokinetic bridge and cilia formation. Here we identified the role of Rab11 endosomes in regulating centrosome positioning during these processes in vivo. To study the role of Rab11 endosomes during abscission we devised an optogenetic system to acutely inhibit Rab11 mediated membrane trafficking both in human cell culture and in zebrafish embryos (Chapter 2). We found that acute inhibition of Rab11 mediated membrane trafficking results in cells being binucleated due to incomplete abscission. Using this approach, we investigated the role of Rab11 endosomes in centrosome function and movement during pre-abscission. We identified that Rab11 endosomes regulate the organization of the centrosome protein, Pericentrin, during pre-abscission that is required for centrosome placement towards the cytokinetic bridge that we argue is required for abscission completion (Chapter 3). Based on this work we examined whether Rab11 was required for centrosome positioning during Kupffer’s Vesicle (KV) development. The KV is a ciliated organ of asymmetry in zebrafish that we used as a model to study tissue formation in vivo. During KV formation, KV mesenchymal cells move their centrosome to the site of lumen formation while the cell’s centrosome is constructing a cilium intracellularly. We identified that Rab11 endosomes regulate cilia formation and centrosome movement to the site of lumen formation during KV development, independent of Rab8 (Chapter 4). Taken together, these findings identify that Rab11 endosome mediated centrosome movement is necessary to coordinate abscission and ciliogenesis during tissue morphogenesis in vivo.

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