Abstract 10: Endothelial Intracellular Adenosine Epigenetically Regulates Angiogenesis
Background and Objectives: It is well known that extracellular adenosine regulates angiogenesis. However, it is unclear whether intracellular adenosine is able to modulate endothelial angiogenesis. This study is to investigate the effect of elevated intracellular adenosine caused by adenosine kinase (ADK) deletion or knockdown on endothelial angiogenesis and further to determine the involvement of adenosine receptors and methylation pathways in this effect.
Methods and results: Human Umbilical Vein Endothelial Cells (HUVECs) were transfected with adenoviral ADK shRNA. ADK knockdown elevated the level of intracellular adenosine, and consequently increased endothelial migration and proliferation. The latter was accompanied with an increase in VEGFR2 expression and PI3K-Akt activation and a decrease of global DNA methylation. Treatment of HUVEC with S-adenosylmethionine or DNA transmethylase inhibitor 5-aza-2-deoxycytodine abolished ADK-knockdown induced VEGFR2 expression and angiogenesis. VEGFR2 expression and global DNA methylation in ADK-knockdown HUVECs were not interfered with adenosine receptor antagonists. Methylation-specific PCR assay showed the decreased methylation of the VEGFR2 promoter, which is the cause for an upregulation of VEGFR2 in ADK deficient HUVECs. Endothelial-specific ADK knockout mice had increased retinal angiogenesis, accelerated wound healing and were protected against hind-limb ischemia.
Conclusion: ADK knockdown-mediated elevation of intracellular adenosine in endothelial cells reduces DNA methylation, leading to an upregulation of VEGFR2 and enhancement of angiogenesis.
Author Disclosures: Y. Xu: None. S. Yan: None. Y. Wang: None. X. An: None. Q. Li: None. C. Wu: None. Y. Huo: None.
This research has received full or partial funding support from the American Heart Association.
- © 2015 by American Heart Association, Inc.