Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.685045
Title: Trafficking of VEGFR2 in angiogenesis : the role of myosin Vb
Author: Allen, Jennifer L.
ISNI:       0000 0004 5923 8275
Awarding Body: University of Bristol
Current Institution: University of Bristol
Date of Award: 2015
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Abstract:
Angiogenesis is the formation of new blood vessels from existing vasculature. It is a process fundamental to normal development and tissue repair, and is implicated in many pathological conditions. The major pro-angiogenic factor is VEGF, for which the major receptor is VEGFR2. Blood vessels are lined with endothelial cells that express VEGFR2 to detect VEGF in surrounding tissue. This detection mediates cell responses to initiate fOlmation of angiogenic sprouts. VEGFR2 belongs to the family of receptor tyrosine kinases. Ligand binding to the extracellular domain results in receptor dimerisation and autophosphorylation of the intracellular kinase domain. This activates multiple downstream signalling cascades, which in the case of VEGFR2 have four main outcomes: proliferation, migration, permeability and survival. Receptor activation is often followed by internalisation and degradation to downregulate signalling pathways. VEGFR2 has unusual trafficking kinetics for a receptor tyrosine kinase because it constitutively internalises and recycles back to the cell surface in the absence of VEGF. It is distributed such that a significant proportion is localised to an intracellular endosomal storage pool. Moreover, the behaviour of VEGFR2 during angiogenesis depends on the location of the endothelial cell within the growing sprout. The importance of this unusual trafficking in relation to signal transduction is poorly understood. My aim was to elucidate how VEGFR2 trafficking controls angiogenic signalling. I worked to identify sorting proteins required for VEGFR2 trafficking. I investigated proteins that are known to mediate the trafficking of other cargoes. Using an ELISA-based screen, I discovered several potential regulators of VEGFR2, including the motor protein myosin Vb. Myosin Vb traffics organelles along actin filaments and has been described in the recycling of many receptors. I used biochemical methods to establish an essential role for myosin Vb in VEGFR2 recycling in unstimulated conditions. I show that myosin Vb depletion impairs vessel formation in an organotypic angiogenesis assay and disrupts phosphorylation of several kinases activated upon VEGF stimulation in endothelial cells. Furthermore, I show that myosin Vb is required for the polarised distribution of VEGFR2 in endothelial cells to enable chemotactic migration towards VEGF. My data suggest that myosin Vb-dependent constitutive trafficking of inactive VEGFR2 is necessary for angiogenesis.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.685045  DOI: Not available
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