Angiogenic vessels form sprouts that migrate outward and interconnect with other vessels or sprouts to form a vessel network. Sprouts eventually are guided by cues such as VEGF from distant target sites, but it is not clear how sprouts initially move away from the parent vessel. Moreover, vessel networks often form in the absence of a strong VEGF gradient, yet sprouts still migrate outward from the parent vessel. An emerging concept is that angiogenic vessels are heterogeneous for endothelial phenotypes;for example both tip cells and stalk cells are required to form a sprout. We propose that endothelial cells adjacent to newly forming sprouts are also heterogeneous, and that the sprout phenotype is elaborated with input from cells in these "lateral base areas". Thus we propose a unique role for the parent vessel in local sprout guidance. Preliminary data supports our central hypothesis that forming sprouts and their filopodia sensors are guided outward by cues from endothelial cells adjacent to the sprout in the vessel, and that Flt-1 (VEGFR-1) has a critical role in this local sprout guidance. Loss of this guidance mechanism leads to vessel dysmorphogenesis and perturbed vessel function. In this renewal application we will determine the molecular requirements for this novel local sprout guidance, and we will determine how endothelial cells cross-talk in developing vessels to integrate signals from the Notch pathway and the VEGF signaling pathway to set up localized and distinct endothelial cell phenotypes. We present three aims organized to elucidate molecular and cellular mechanisms responsible for this guidance, and experiments that will critically test the role of Flt-1 and Notch signaling in this process, both in fixed samples and via dynamic image analysis. We will take advantage of the strengths of a developmental model using stem cell-derived blood vessels, and we will complement these experiments with in vivo experiments in the yolk sac and the retina. This information is important to our ability to reconstitute a vascular plexus for therapeutic purposes. )

Public Health Relevance

Blood vessel networks are required to deliver oxygen and nutrients to tissues, yet the earliest stages of blood network formation are poorly understood. We will determine how groups of cells that sprout from a parent blood vessel know to move outward and away from the parent and toward potential new interconnections. We hypothesize that a protein, Flt-1, is secreted right next to the forming sprout on each side. This molecule soaks up a local positive signal, so that only the area directly ahead of the sprout has the positive signal for forward movement. Thus the Flt-1 protein forms a barrier or chute that constrains the moving sprout to a particular track. If this process is disrupted the vessel network does not form properly and the tissue (and organism) dies.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL043174-23
Application #
8469879
Study Section
Cardiovascular Differentiation and Development Study Section (CDD)
Program Officer
Gao, Yunling
Project Start
1989-07-01
Project End
2014-05-31
Budget Start
2013-06-01
Budget End
2014-05-31
Support Year
23
Fiscal Year
2013
Total Cost
$346,162
Indirect Cost
$110,542
Name
University of North Carolina Chapel Hill
Department
Biology
Type
Schools of Arts and Sciences
DUNS #
608195277
City
Chapel Hill
State
NC
Country
United States
Zip Code
27599
Pelton, John C; Wright, Catherine E; Leitges, Michael et al. (2014) Multiple endothelial cells constitute the tip of developing blood vessels and polarize to promote lumen formation. Development 141:4121-6
Kushner, Erich J; Ferro, Luke S; Liu, Jie-Yu et al. (2014) Excess centrosomes disrupt endothelial cell migration via centrosome scattering. J Cell Biol 206:257-72
Kushner, Erich J; Bautch, Victoria L (2013) Building blood vessels in development and disease. Curr Opin Hematol 20:231-6
Chappell, John C; Mouillesseaux, Kevin P; Bautch, Victoria L (2013) Flt-1 (vascular endothelial growth factor receptor-1) is essential for the vascular endothelial growth factor-Notch feedback loop during angiogenesis. Arterioscler Thromb Vasc Biol 33:1952-9
Ruhrberg, Christiana; Bautch, Victoria L (2013) Neurovascular development and links to disease. Cell Mol Life Sci 70:1675-84
Peirce, Shayn M; Mac Gabhann, Feilim; Bautch, Victoria L (2012) Integration of experimental and computational approaches to sprouting angiogenesis. Curr Opin Hematol 19:184-91
Chappell, John C; Wiley, David M; Bautch, Victoria L (2012) How blood vessel networks are made and measured. Cells Tissues Organs 195:94-107
Sweet, Daniel Timothy; Chen, Zhongming; Wiley, David M et al. (2012) The adaptor protein Shc integrates growth factor and ECM signaling during postnatal angiogenesis. Blood 119:1946-55
Chappell, John C; Wiley, David M; Bautch, Victoria L (2011) Regulation of blood vessel sprouting. Semin Cell Dev Biol 22:1005-11
Bautch, Victoria L (2011) Stem cells and the vasculature. Nat Med 17:1437-43

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