Abstract 17055: Kruppel Like Factor 4 is a Regulator of Angiogenesis Through Direct Inhibition of the Notch Transcription Factor Complex
Introduction: Angiogenesis is a multistep process that requires a highly regulated endothelial cell behavior. Notch signaling is one of the crucial regulators of sprouting angiogenesis, but the upstream of Notch is not clear yet. Krüppel-like factor 4 is a critical regulator of endothelial cells function. We have recently shown that Krüppel-like factor 4 is a regulator of tumor angiogenesis by mediating the expression of members of the VEGF and Notch pathways.
Hypothesis: Determine the role of Krüppel-like factor 4 in developmental angiogenesis and the precise molecular mechanism for Krüppel-like factor 4’s ability to inhibit the Delta-like 4 expression.
Methods: To determinate the role of Krüppel-like factor 4 in developmental angiogenesis we used a retinal angiogenesis model on mice with overexpression and inducible knockdown of Krüppel-like factor 4. The standard protocol for oxygen-induced retinopathy, immunostaining were used. The vascular characteristics of the retina were analyzed using AngioTool software. In vitro, we used standard protocols for chromatin immunoprecipitation assays, western blotting, and immunoprecipitation.
Results: We found that endothelial-specific overexpression of KLF4 in transgenic mice leads to increased vessel branching, density and number of tip cell filopodia as assessed on a postnatal day 6. The hypertrophic vasculature in the Krüppel-like factor 4 overexpression group is not stable and undergoes more prominent remodeling during postnatal day 7-12. With regards to normal sprouting angiogenesis, we found that Krüppel-like factor 4 inhibits delta-like 4 expression. We further confirmed this by demonstrating a protective effect of Krüppel-like factor 4 in the mouse model with oxygen-induced retinopathy. Mechanistically, Krüppel-like factor 4 inhibits the Delta-like 4 expression by directly binding with the transcription factor RBP-J.
Conclusions: Sustained overexpression Krüppel-like factor 4 results in increased vessels density with overgrowth tip cells phenotype. The phenotype is the result of direct inhibition of Delta-like 4 transcription by directly binding with RBP-J.
Author Disclosures: E. Boriushkin: None.
- © 2016 by American Heart Association, Inc.