Abstract 18337: The Role of NANOG in Regulating Fetal Liver Kinase-1 (FLK1) Expression in Angiogenesis
Rationale: Fetal Liver Kinase-1 (FLK1) has a recognized role in endothelial cell (EC) formation, migration, and angiogenesis; although, its mechanism of action is not well known.
Hypothesis: NANOG regulates FLK1 expression and therefore EC proliferation and angiogenesis.
Results: We demonstrate that the transcription factor NANOG is expressed in cultured human umbilical cord endothelial cells (HUVECs) and a subset of tumor cell lines. NANOG and FLK1 expression are increased in response to WNT3A stimulation. Chromatin immunoprecipitation (ChIP) and electrophoretic mobility shift assays (EMSA) revealed three NANOG binding sites in the FLK1-promoter DNA sequence. We propose that NANOG binding to these sites activate the FLK1-promoter, thereby its expression in a subset of ECs. Accordingly, FLK1-promoter luciferase assay showed the ability for WNT to activate these three sites and consequently up-regulate EC proliferation. NANOG knockdown resulted in a decrease in FLK1 mediated EC proliferation in vitro and angiogenesis in vivo, seen using Matrigel plug assays. Re-expression of FLK1 into NANOG-depleted HUVECs partially restored the proliferative and angiogenic deficiencies in these cells caused by the NANOG knockdown.
Conclusion: These results indicate that NANOG transcriptionally regulates FLK1 expression leading to a role in controlling the proliferative and angiogenic activities of endothelial cells. *This work was supported by National Institutes of Health (R01HL079356; HL079356-03S1) and by the University of Illinois at Chicago (UIC) Center for Clinical and Translational Science (CCTS) Award Number UL1RR029879 from the National Center for Research Resources to K.K.W. E.E.K. was supported by T32GM070388 NIH training grant.
- © 2010 by American Heart Association, Inc.