Perlecan coordinates developmental angiogenesis
Development of the vertebrate vascular system into a complex blood vessel network occurs via vasculogenesis and angiogenesis. Vasculogenesis describes the de novo formation of primary blood vessels through the coalescence of angioblasts. Angiogenesis describes the formation, development and growth of new blood vessels from the pre-existing vasculature. The specific events underlying both processes of blood vessel formation are influenced by components of the extracellular matrix. The major focus of the research presented in my thesis explored the pro-angiogenic role of the heparan sulfate proteoglycan perlecan during vascular development. The work applied the zebrafish, Danio rerio, as a model system to study cardiovascular development. My thesis characterized zebrafish perlecan and applied a morpholino knockdown strategy to define perlecan function. In this thesis, I identified a central role for perlecan during developmental angiogenesis. Perlecan knockdown inhibited angiogenic blood vessel development of the intersegmental and sub-intestinal vessels, but did not affect the formation of the dorsal aorta and posterior cardinal vein both which form by vasculogenesis. At the individual cell level, perlecan knockdown blocked endothelial cell migration and or proliferation events necessary for proper vessel formation. Live video microscopy confirmed vessels in the perlecan morphant embryos were largely non-functional, as evidenced by the lack of red blood cell circulation. I have established perlecan function through VEGF-VEGFR2 modulation during the process of angiogenic blood vessel formation. Accordingly, I was able to rescue the perlecan morphant phenotype with VEGF-A165 indicating a functional link between perlecan and VEGF. Additional investigations revealed perlecan knockdown results in an abnormal redistribution and accumulation of VEGF protein, implying perlecan was required for the proper localization of VEGF. Human translational validation in vitro, using human endothelial cells and human proteins, revealed perlecan and VEGF interact, via the attached heparan sulfate chains, with functional consequences defined as enhanced VEGFR2 activation. Overall, my thesis research indicates perlecan coordinates developmental angiogenesis. A minor focus of my thesis research explored the anti-angiogenic nature of perlecan by investigating the influence of perlecan domain V/endorepellin on the endothelium. Through an extensive comparative proteomics approach, I identified five key proteins with altered expression profiles in response to endorepellin treatment. Each protein, β-actin, calreticulin, chaperonin/Hsp60, vimentin and prolyl 4-hydroxylase β, can be linked to endorepellin function.
Zoeller, Jason Joseph, "Perlecan coordinates developmental angiogenesis" (2009). ETD Collection for Thomas Jefferson University. AAI3415761.