MilliporeSigma
  • Endothelial Kruppel-like factor 4 regulates angiogenesis and the Notch signaling pathway.

Endothelial Kruppel-like factor 4 regulates angiogenesis and the Notch signaling pathway.

The Journal of biological chemistry (2014-03-07)
Andrew T Hale, Hongmei Tian, Ejike Anih, Fernando O Recio, Mohammad A Shatat, Trent Johnson, Xudong Liao, Diana L Ramirez-Bergeron, Aaron Proweller, Masakazu Ishikawa, Anne Hamik
ABSTRACT

Regulation of endothelial cell biology by the Notch signaling pathway (Notch) is essential to vascular development, homeostasis, and sprouting angiogenesis. Although Notch determines cell fate and differentiation in a wide variety of cells, the molecular basis of upstream regulation of Notch remains poorly understood. Our group and others have implicated the Krüppel-like factor family of transcription factors as critical regulators of endothelial function. Here, we show that Krüppel-like factor 4 (KLF4) is a central regulator of sprouting angiogenesis via regulating Notch. Using a murine model in which KLF4 is overexpressed exclusively in the endothelium, we found that sustained expression of KLF4 promotes ineffective angiogenesis leading to diminished tumor growth independent of endothelial cell proliferation or cell cycling effects. These tumors feature increased vessel density yet are hypoperfused, leading to tumor hypoxia. Mechanistically, we show that KLF4 differentially regulates expression of Notch receptors, ligands, and target genes. We also demonstrate that KLF4 limits cleavage-mediated activation of Notch1. Finally, we rescue Notch target gene expression and the KLF4 sprouting angiogenesis phenotype by supplementation of DLL4 recombinant protein. Identification of this hitherto undiscovered role of KLF4 implicates this transcription factor as a critical regulator of Notch, tumor angiogenesis, and sprouting angiogenesis.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Chromatin Immunoprecipitation (ChIP) Assay Kit, Contains all necessary reagents to perform 22 individual chromatin immunoprecipitation (ChIP) reactions using inexpensive protein A agarose beads.
Sigma-Aldrich
Anti-NG2 Chondroitin Sulfate Proteoglycan Antibody, Chemicon®, from rabbit
Sigma-Aldrich
Anti-KLF4 antibody produced in rabbit, Prestige Antibodies® Powered by Atlas Antibodies, affinity isolated antibody, buffered aqueous glycerol solution