The relationship between thrombospondin 2 (TSP2) and endothelial nitric oxide synthase (eNOS) are not known. Activation of VEGFR-2 via VEGF or by fluid shear stress activates the protein kinase Akt and the endothelial specific Akt substrate, endothelial nitric oxide synthase (eNOS), leading to arteriogenesis and angiogenesis. As inferred from exciting preliminary studies from our laboratories, TSP2 serves as a negative regulator of the Akt-1/eNOS pathway. Previously, we have reported that TSP2 knockout mice (TSP2-K0) demonstrate enhanced arteriogenesis and blood flow recovery in response to limb ischemia and augmented tissue healing. Interestingly, our preliminary studies show that TSP2 levels are elevated in eNOS-KO and Akt1-KO mice, which both display marked impairments in arteriogenesis and angiogenesis and NO, per se, negatively regulates TSP2 levels. Moreover, TSP2/eN0S double knockout (DKO) mice exhibit substantial improvements in blood flow recovery and tissue repair. Thus, we hypothesize that regulation of TSP2 expression by eNOS-derived NO constitutes a previously undefined pro-arteriogenic and pro-angiogenic property of NO. To test this idea, we will: 1. test the hypothesis that the Akt1/eNOS axis mediates arteriogenic and angiogenic responses in vivo, in part, by repressing TSP2 levels;2. determine the mechanism(s) through which the Akt1/eNOS axis and crosstalk with ERK regulates TSP2 and arteriogenesis;and 3. dissect the regulation of the N0/TSP2 pathway and other endothelial cell functions during in vitro angiogenesis. Collectively, these experiments will allow us to delve deeply into the functional antagonism of arteriogenesis and angiogenesis by TSP2, and to delineate how NO regulates TSP2 gene expression and blood flow recovery after limb ischemia.

Public Health Relevance

Peripheral arterial disease is a common disease effecting 10-25% of patients over the age of 55 years old. We propose to investigate the crosstalk between the molecular and biomechanical signals that trigger vascular remodeling and the secretion of regulatory molecules that mediate these effects. Completion of this project should lead to a greater understanding of vascular remodeling and identification of novel therapeutic strategies for arterial disease.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Program Projects (P01)
Project #
5P01HL107205-03
Application #
8607983
Study Section
Heart, Lung, and Blood Initial Review Group (HLBP)
Project Start
Project End
Budget Start
2014-02-01
Budget End
2015-01-31
Support Year
3
Fiscal Year
2014
Total Cost
$427,499
Indirect Cost
$170,743
Name
Yale University
Department
Type
DUNS #
043207562
City
New Haven
State
CT
Country
United States
Zip Code
06520
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