Defense Date

2012

Document Type

Thesis

Degree Name

Master of Science

Department

Biochemistry

First Advisor

William Barton

Abstract

Many signaling pathways have been shown to be involved in the formation of the vascular system. Among them are the endothelial specific receptor families such as VEGF, Ang/Tie, as well as other signaling pathways such as semaphorins, which are also involved, in axonal guidance. It is known that the interaction between receptor tyrosine kinase, Tie2, VE-Cadherin, and VE-PTP mediate endothelial cell quiescence and adhesion. However, the structural basis of these interactions is not well understood. The aim of our study is to characterize the binding interactions between these players. Another important part of our study is describing the cross-talk between vasculature and nervous system by characterizing the Neuropilin/Plexin/Semaphorin system. VE-Cadherin along with neuropilins plays an essential role by directing VEGF signals to the appropriate location and coordinating the activation of downstream molecules. We characterize the interaction between Tie2, VE-PTP and VE-Cadherin by (FRET)-based proximity assay, fluorescence lifetime imaging, and co-immunoprecipitation assays. Our data showed a consistent localization of the protein and FRET signal for Tie2 and VE-PTP prior to ligand recognition. We showed the association between Tie2 and VE-Cadherin complex by co-immunoprecipatation. However, our FRET data was not consistent. The examination of VE-PTP and VE-Cadherin for association and localization of the protein showed a very unique, mutually exclusive localization of the protein. Our study of Neuropilin/Plexin/Semaphorin system showed changes in the protein localization, FRET signal and morphology upon stimulation of HEK293 cells expressing Nrp/plexin with Sema3D. In this system VE-Cadherin along with neuropilins plays an essential role by directing VEGF signals to the appropriate location and coordinating the activation of downstream molecules. The characterization of extracellular binding between Tie2, VE-PTP, and VE-Cadherin, will help to better understand the molecular mechanisms of normal and tumor angiogenesis to develop new anti-angiogeneic therapies.

Rights

© The Author

Is Part Of

VCU University Archives

Is Part Of

VCU Theses and Dissertations

Date of Submission

August 2012

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