DOI
https://doi.org/10.25772/ZSEK-DG96
Defense Date
2010
Document Type
Dissertation
Degree Name
Doctor of Philosophy
Department
Biochemistry
First Advisor
Willliam A Barton
Abstract
The primary function of the vascular system is the maintenance of oxygen homeostasis for all metazoan tissue. Angiogenesis, the remodeling and maintenance of new blood vessels from an existing vessel, is primarily controlled through the endothelial specific receptor tyrosine kinase Tie2, and the orphan receptor tyrosine kinase, Tie1. Although these receptors share highly conserved, genetic and biochemical analysis has shown these receptors have distinct and essential roles in angiogenesis. Tie2 activation typically results in vessel stability and quiescences and has further been shown to interact with all four sub-types of the angiopoietin signaling factors, Ang1-4. Conversely, Tie1 is involved in vascular remodeling and has no known ligands. The aim of this study is to resolve the molecular mechanism in which Tie1 modulates Angiopoietin-induced Tie2 signaling. Using biophysical, structural, and biochemical assays we show Tie1 directly interacts with Tie2 via electrostatic interactions housed within the extracellular domains. The binding of Tie1 to Tie2 attenuates Tie2 phosphorylation. We further show the constitutive agonist of Tie2, Ang-1, is capable of excluding Tie1 initiating Tie2 activation. Whereas the antagonist, Ang-2, is in incapable of excluding Tie1. Finally, we identify a region within the angiopoietin receptor-binding domain that is capable of including or excluding Tie1 from Tie2. Based upon the available data, we provide a model for Angiopoietin-induced Tie2 signaling.
Rights
© The Author
Is Part Of
VCU University Archives
Is Part Of
VCU Theses and Dissertations
Date of Submission
May 2010