Endothelial cells communicate with each other via cell-cell interactions during development and in stable vessels. One important structure is the adherens junction, which links the actin cytoskeleton of individual cells via cadherin-based interactions. Although endothelial adherens junctions are important in vascular development, surprisingly little is known about their formation and regulation. In mature vessels, adherens junctions are required to form a barrier that controls the movement of fluids and macromolecules between blood and tissue sites. The second messenger diacylglycerol (DAG) promotes vascular permeability and disrupts endothelial barrier function, and phorbol esters mimic DAG activity. The goal of this proposal is to determine how a novel endothelial DAG/phorbol ester receptor we recently identified, RasGRPS, affects adherens junctions developmentally and impacts on vessel permeability in adult vessels. RasGRP3 activates the small GTPases Ras and/or Rap, and our preliminary data point to a crucial role for RasGRP3 irf the response of developing vessels to DAG/phorbol esters, via a mechanism similar to the permeability response of adult vessels. Thus we hypothesize that RasGRP3-mediated Ras/Rap signaling is a critical endothelial control point for the regulation of adherens junctions, in situations where cellular signaling through DAG is dominant. We set this up experimentally by exogenous administration of phorbol esters, but we posit that this scenario is recapitulated in disease states that are characterized by elevated DAG levels, such as diabetes. We propose that the vascular complications of diabetes in both adults and developing fetuses can be ameliorated by blockade of RasGRP3 activity. These hypotheses will be tested in three aims that fully characterize the RasGRP3-dependent response of developing vessels and endothelial cells to DAG/phorbol esters at the cellular and molecular levels, and examine the consequences of genetic manipulation of RasGRP3 on endothelial barrier function and the vascular complications of diabetes in embryos and adults. ? ?

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL083262-02
Application #
7184378
Study Section
Cardiovascular Differentiation and Development Study Section (CDD)
Program Officer
Srinivas, Pothur R
Project Start
2006-02-15
Project End
2010-01-31
Budget Start
2007-02-01
Budget End
2008-01-31
Support Year
2
Fiscal Year
2007
Total Cost
$351,367
Indirect Cost
Name
University of North Carolina Chapel Hill
Department
Biochemistry
Type
Schools of Medicine
DUNS #
608195277
City
Chapel Hill
State
NC
Country
United States
Zip Code
27599
Randhawa, Paramjeet K; Rylova, Svetlana; Heinz, Jessica Y et al. (2011) The Ras activator RasGRP3 mediates diabetes-induced embryonic defects and affects endothelial cell migration. Circ Res 108:1199-208
Zeng, Gefei; Bautch, Victoria L (2009) Differentiation and dynamic analysis of primitive vessels from embryonic stem cells. Methods Mol Biol 482:333-44
Rylova, Svetlana N; Randhawa, Paramjeet K; Bautch, Victoria L (2008) In vitro differentiation of mouse embryonic stem cells into primitive blood vessels. Methods Enzymol 443:103-17