Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.697750
Title: Exploring the role of transmembrane 4 L six family member 1 (Tm4sf1) in the control of tip cell behaviour during sprouting angiogenesis
Author: Page, Donna
ISNI:       0000 0004 5993 8415
Awarding Body: University of Manchester
Current Institution: University of Manchester
Date of Award: 2015
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Abstract:
Angiogenesis is the process of new blood vessel sprouting from pre-existing vessels and is responsible for generating the majority of nascent vessels during development, tissue regeneration and disease. During angiogenesis, sprouting endothelial cells (ECs) are organised into leading 'tip' cells (TCs) and trailing 'stalk' cells (SCs). This hierarchal organisation of TCs and SCs is essential for the coordinated collective migration of ECs during sprouting. However, the precise mechanisms that define TC verses SC behaviour and identity remains uncertain. Transcriptomic analysis of sprouting vessels in zebrafish embryos led to the identification of a novel TC-associated gene, transmembrane 4 L six family member 1 (tm4sf1). We find that tm4sf1 expression is tightly spatiotemporally restricted to migrating TCs during intersegmental vessel (ISV) sprouting in zebrafish. Furthermore, TC tm4sf1 expression is controlled by the vascular endothelial growth factor receptor (Vegfr) - Notch signalling axis. Morpholino oligonucleotide (MO)-mediated knockdown of tm4sf1 reveals a subtle delay in ISV sprouting upon loss of tm4sf1 expression. Moreover, using multiplexed, real-time imaging approaches and in-depth analysis of TC and SC behaviours at single cell resolution, we reveal that the delay in ISV sprouting is specifically due to reduced TC motility. Furthermore, we find that tm4sf1 functions to induce TC motility in the leading daughter cell following TC mitosis, to rapidly re-establish post-mitotic TC behaviour. Generation of tm4sf1 mutant zebrafish lines using both transcription activator-like effector nucleases (TALENs) and clustered regularly interspaced short palindromic repeats (CRISPR) confirms that Tm4sf1 modulates TC behaviour. Additionally, mechanistic studies in human ECs reveal that tm4sf1 regulates VEGFR-mediated signalling upon VEGF-stimulation, which subsequently controls cell migration and expression of the TC determinants, DLL4 and VEGFR2. Hence, our results suggest that tm4sf1 is a novel modulator of the TC-SC hierarchy and collective EC migration during ISV sprouting. Overall, these findings have potential therapeutic implications since tm4sf1 may be a promising target for the manipulation of pathological angiogenesis in disease.
Supervisor: Not available Sponsor: Biotechnology and Biological Sciences Research Council (BBSRC)
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.697750  DOI: Not available
Keywords: Angiogenesis ; Zebrafish ; Tm4sf1 ; Tetraspanin ; Blood vessel ; Development
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