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Full-Text Articles in Cell Biology

The Role Of The Exocyst In Exocytosis And Cell Migration, Jianglan Liu Aug 2010

The Role Of The Exocyst In Exocytosis And Cell Migration, Jianglan Liu

Publicly Accessible Penn Dissertations

The exocyst, an evolutionarily conserved octameric protein complex, plays a crucial role in the tethering of post-Golgi secretory vesicles to the plasma membrane for exocytosis and cell migration. How the exocyst is targeted to sites of exocytosis and how this complex regulates cell migration are poorly understood. I have carried out experiments to characterize Exo70, a component of the exocyst complex. Firstly, I found that Exo70 directly interacts with phosphatidylinositol 4,5-bisphosphate through positively charged residues at its C-terminus, and this interaction is critical for the plasma membrane targeting of Exo70. Using the ts045 vesicular stomatitis virus glycoprotein trafficking assay ...


Mechanisms Of The Downregulation Of Prolactin Receptor And Their Role In Cell Proliferation, Bentley J. Varghese May 2010

Mechanisms Of The Downregulation Of Prolactin Receptor And Their Role In Cell Proliferation, Bentley J. Varghese

Publicly Accessible Penn Dissertations

Cells react to diverse stimuli by expressing specific receptors that recognize these stimuli and initiate specific signaling pathways that enable a cell to change with the environment. Downregulation of these signaling receptors represents the most direct method for limiting the magnitude and duration of downstream signal transduction. For cell surface transmembrane receptors, ligand-stimulated endocytosis is a major mechanism by which the ability of a cell to react to a ligand is restricted. In order to investigate the downregulation of the prolactin receptor (PRLr), we investigated the mechanism and key determinants in the endocytosis and downregulation of PRLr. In Chapter 2 ...


Control Of Denticle Diversity In The Drosophila Embryo, Stacie A. Dilks May 2010

Control Of Denticle Diversity In The Drosophila Embryo, Stacie A. Dilks

Publicly Accessible Penn Dissertations

Screening for mutations that affect the epidermal cuticle pattern has been used as a powerful approach to identify genes involved in developmental decisions and signaling pathways (Luschnig et al., 2004; Mayer and Nusslein-Volhard, 1988; Nusslein- Volhard and Wieschaus, 1980). Some years ago, it became clear that the finer details of cuticle pattern, specifically the column-specific differences in denticle shape and hook orientation, occurred as a result of differential activation of the signaling pathways that pattern the epidermis (Alexandre et al., 1999). Since that time, no downstream targets have been identified that selectively affect denticle shape or hooking, and the mechanism ...


A Microfabrication Approach To Multicellular Mechanics, Zhijun Liu May 2010

A Microfabrication Approach To Multicellular Mechanics, Zhijun Liu

Publicly Accessible Penn Dissertations

To address the question of how cell-generated forces regulate the organization and function of endothelial cells, I investigated the mechanical forces in a simple model of cell-cell contact: paired cells contacting each other via a single cell-cell junction. To study the responsiveness of AJs to force, I adapted a system of microfabricated force sensors to quantitatively report both the cell-cell tugging force and the size of adherens junctions (AJ). I observed that AJ size was modulated by tugging force: AJs and tugging force grew or decayed with myosin activation or inhibition, respectively. This myosin-dependent regulation operated in concert with a ...