Pathological angiogenesis is a key process that drives vascular remodeling in numerous cardiovascular and metabolic diseases including diabetic retinopathy and cancer. However, due to the lack of appropriate targets, limited effective medicines or therapies to treat this pathological process are available. Epsins were originally identified by the PI as a family of important endocytic adaptor proteins. We recently showed that epsins, via their ubiquitin-interacting motifs (UIM), are critical for activated VEGFR2 internalization, degradation and signal attenuation. Intriguingly, endocytosis of activated VEGFR2 by a different endocytic adaptor protein, Dab2, results in enhanced VEGF signaling. How VEGFR2 internalization differentially modulates VEGF signaling is a highly significant and open question. Our latest study shows that epsins and Dab2 competitively interact with VEGFR2. Furthermore, a synthetic UIM peptide inhibitor interferes with epsin-VEGFR2 association, heightens VEGF signaling and impedes tumor growth. Conversely, a synthetic peptide derived from Dab2 phospho-tyrosine binding (PTB) domain disrupts Dab2-VEGFR2 binding, reduces VEGF signaling and inhibits retinal angiogenesis. Therefore, we hypothesize that epsins and Dab2 differentially modulate VEGF signaling by competitively binding VEGFR2, and that targeting epsins and Dab2 may offer therapeutic potential in pathological angiogenesis. The roles of epsins and Dab2 in pathological angiogenesis and the molecular mechanisms underlying their differential regulation of VEGF signaling will be characterized using both in vitr and in vivo model systems.
In Aim 1, we will utilize multifactorial approaches to investigate molecular mechanisms by which epsin UIM specifically interacts with VEGFR2 to control VEGF signaling and angiogenic responses.
In Aim 2, we will employ biochemical characterization, dynamic imaging and immunofluorescence to determine how epsins and Dab2 differentially regulate VEGF signaling. These studies mechanistically link the differential regulations of VEGF signaling and function of epsins and Dab2.
In Aim 3, we will determine whether targeting epsins and Dab2 disrupts tumor angiogenesis and inhibits neovascular proliferative retinopathy. These studies will advance understanding of new pathways and new targets that differentially modulate VEGF signaling and may lead to new therapies targeting the pathological angiogenesis associated with cancer and diabetes.

Public Health Relevance

Pathological angiogenesis ensures tumor development, progression, and spread to other parts of body, which is the most common cause of death in the United States. Pathological angiogenesis also plays a leading role in the pathogenesis of diabetic retinopathy, which is the most common microvascular complication of diabetes and one of the major causes of blindness worldwide. In current application, we will define how a novel signaling adaptor protein, epsin and Dab2, another prominent endocytic sorting protein, control the development of pathological angiogenesis by regulating VEGF signaling. The findings will provide useful information on developing key reagents to advance the epsin- or Dab2-based targeting strategy for therapeutic intervention of pathological angiogenesis.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
2R01HL093242-06
Application #
8769267
Study Section
Vascular Cell and Molecular Biology Study Section (VCMB)
Program Officer
Gao, Yunling
Project Start
2008-07-01
Project End
2018-06-30
Budget Start
2014-08-01
Budget End
2015-06-30
Support Year
6
Fiscal Year
2014
Total Cost
$427,500
Indirect Cost
$177,500
Name
Oklahoma Medical Research Foundation
Department
Type
DUNS #
077333797
City
Oklahoma City
State
OK
Country
United States
Zip Code
73104
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Rahman, H N Ashiqur; Wu, Hao; Dong, Yunzhou et al. (2016) Selective Targeting of a Novel Epsin-VEGFR2 Interaction Promotes VEGF-Mediated Angiogenesis. Circ Res 118:957-69
Dong, Yunzhou; Wu, Hao; Rahman, H N Ashiqur et al. (2015) Motif mimetic of epsin perturbs tumor growth and metastasis. J Clin Invest 125:4349-64
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Chen, Hong; Griffin, Courtney; Xia, Lijun et al. (2014) Molecular and cellular mechanisms of lymphatic vascular maturation. Microvasc Res 96:16-22
Pan, Yanfang; Yago, Tadayuki; Fu, Jianxin et al. (2014) Podoplanin requires sialylated O-glycans for stable expression on lymphatic endothelial cells and for interaction with platelets. Blood 124:3656-65

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