Hypoxia Inducible Factor (HIF) is a critical sensor of tissue O2 levels and governs angiogenic gene expression programs operating during embryogenesis as well as in post-natal pathologies including wound healing and ischemia. In principle, HIF contributes to important genetic programs responsible for moderating and controlling vascular growth. Mice deficient in HIF display developmental arrest due to multiple cardiovascular anomalies. However, the significance of a specific role for the HIF-canonical pathway in vascular endothelial cells (ECs) is lacking. The long-term research objective of this application is to determine how HIF, in response to the hypoxic (low oxygen) environment, regulates vascular growth necessary for maintaining tissue homeostasis. It has been demonstrated the specific activity of HIF is cell- and context- dependent. This proposal addresses the general hypothesis that EC- HIF activates distinct genes regulating specific types of vessel growth at various stages of vascular development and in post-natal angiogenesis. We will further determine whether HIF, in response to hypoxia, moderates the temporal expression of VEGF receptors that are important in mediating specific signals in ECs including their survival, proliferation, and behavior. The experimental design utilizes an Arnt-conditional (HIF-? obligatory subunit in vessels) mouse genetic system that completely inactivates HIF-transcriptional activity in ECs at various stages of embryonic development as well as in the adult vasculature enabling the investigations of HIF's requirement(s) and role(s) within ECs during the establishment, maturation, and maintenance of blood vessels as well as in response to vascular injury.
Specific Aim 1 will examine how HIF inactivation in ECs at critical stages of embryonic development lead to specific angiogenic defects.
Aim 2 addresses the requirement(s) for HIF in adult vessel homeostasis and various types of vascular responses (neoangiogenesis, angiogenesis, and arteriogenesis). Finally, Aim 3 will examine the intrinsic requirements of HIF within ECs and test the hypothesis that HIF is important in promoting EC survival in part by regulating the expression of VEGF receptors. The studies proposed herein intend to expand our understanding of the mechanisms by which hypoxia regulates vessel generation and homeostasis in both normal and pathological settings.

Public Health Relevance

Defective vessel development and/or maintenance is a feature of multiple human pathological vascular diseases including tumorigenesis and tissue ischemia. By using in vivo genetic approaches, we can methodically investigate the biological and molecular vascular processes driven by endothelial HIF transcriptional responses. This work will provide a molecular framework aimed at understanding the biological significance of HIF activity in endothelial cells during physiological and pathological vascular responses observed in embryos and adults. Such investigation is of clinical importance since it can provide new directions for the development of therapeutic agents targeting vascular growth processes.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL096597-04
Application #
8606233
Study Section
Vascular Cell and Molecular Biology Study Section (VCMB)
Program Officer
Gao, Yunling
Project Start
2011-02-01
Project End
2016-01-31
Budget Start
2014-02-01
Budget End
2015-01-31
Support Year
4
Fiscal Year
2014
Total Cost
$374,801
Indirect Cost
$129,978
Name
Case Western Reserve University
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
077758407
City
Cleveland
State
OH
Country
United States
Zip Code
44106
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Hale, Andrew T; Tian, Hongmei; Anih, Ejike et al. (2014) Endothelial Kruppel-like factor 4 regulates angiogenesis and the Notch signaling pathway. J Biol Chem 289:12016-28
Han, Yu; Tao, Jiayi; Gomer, Alla et al. (2014) Loss of endothelial-ARNT in adult mice contributes to dampened circulating proangiogenic cells and delayed wound healing. Vasc Med 19:429-41
Tao, Jiayi; Doughman, Yongqiu; Yang, Ke et al. (2013) Epicardial HIF signaling regulates vascular precursor cell invasion into the myocardium. Dev Biol 376:136-49
Han, Yu; Yang, Ke; Proweller, Aaron et al. (2012) Inhibition of ARNT severely compromises endothelial cell viability and function in response to moderate hypoxia. Angiogenesis 15:409-20