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Factor-inhibiting hypoxia-inducible factor (HIF)-1 (FIH-1) is an asparaginyl β-hydroxylase enzyme that was initially found to hydroxylate the HIF-α, preventing its transcriptional activity and leading to adaptive responses to hypoxia. More recently, other substrates, such as neurogenic locus notch homolog (Notch), have been found to be alternative FIH targets, but the biologic relevance of this regulation was never investigated. Given the key function of Notch in angiogenesis, we here investigate the role of FIH/Notch signaling in endothelial cells. We report that FIH-1 silencing in HUVECs results in reduced growth and increased apoptosis. The knockdown of FIH is associated with increased Notch2 activity, leading to enhanced expression of the Notch target hairy/enhancer-of-split related with YRPW motif protein 1 (Hey-1). Consistent with recent findings showing that Notch2 suppresses survivin (a key inhibitor of apoptosis), FIH targeting in HUVECs leads to selective repression of survivin in endothelial cells, thus promoting cell apoptosis and growth arrest. Our data support the concept that FIH-1 may interact with Notch2 and repress its activity, thereby playing a critical role in controlling the survival of vascular endothelial cells. These findings might pave the way toward novel, antiangiogenic strategies in disorders that are characterized by excessive vascular growth, such as cancer and rheumatoid arthritis.

Original publication




Journal article


FASEB journal : official publication of the Federation of American Societies for Experimental Biology

Publication Date





2814 - 2827


*Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, Kennedy Institute of Rheumatology, University of Oxford, United Kingdom; Laboratory of Molecular Oncology and Angiogenesis, Vesalius Research Center, Vlaams Instituut voor Biotechnologie (VIB), Leuven, Belgium; Laboratory of Molecular Oncology and Angiogenesis, Vesalius Research Center, Department of Oncology, Katholieke Universiteit (KU) Leuven, Belgium; and Department of Chemistry, Section of Organic Chemistry and Biochemistry, University of Ioannina, Greece


Endothelial Cells, Humans, Mixed Function Oxygenases, Cell Cycle Proteins, Repressor Proteins, RNA, Messenger, Signal Transduction, Apoptosis, Cell Proliferation, Cell Hypoxia, Cell Survival, RNA Interference, Inhibitor of Apoptosis Proteins, Basic Helix-Loop-Helix Transcription Factors, Hypoxia-Inducible Factor 1, alpha Subunit, Receptor, Notch2, Gene Knockdown Techniques, Human Umbilical Vein Endothelial Cells