Suppression of DNA-PKcs enhances FGF-2 dependent human endothelial cell proliferation via negative regulation of Akt.
Angiogenesis initiation is crucially dependent on endothelial proliferation and can be stimulated by the fibroblast growth factor 2 (FGF-2). The DNA dependent protein kinase (DNA-PK), long known for its importance in repairing DNA double strand breaks, belongs to the phosphatidylinositol-3 kinase (PI3-K) super family and has recently been identified as one of the enzymes phosphorylating and activating Akt. Due to its similarity with PI3-K, we hypothesized that DNA-PK may have similar effects on endothelial angiogenic processes and signalling. We used primary endothelial cells (HUVEC and PAEC) and human microvascular endothelial cells (HMEC) to study the role of DNA-PK in endothelial proliferation and signalling. DNA-PKcs suppression with the compound NU7026 or with siRNA induced basal endothelial cell proliferation as well as enhanced FGF-2 dependent proliferation. This was associated with an increase in phosphorylated Akt. Tube formation was not affected by DNA-PKcs clearly showing that the role of DNA-PK in endothelial processes differs from that of PI3-K. Our findings indicate DNA-PK as an important enzyme maintaining the quiescent endothelial phenotype by actively inhibiting Akt thus restraining endothelial cell proliferation preventing excessive growth.
Cardiology, Medical Policlinic, Ludwig-Maximilians-University, Ziemssenstrasse 1, 80336 Munich, Germany.
Hanna
H
Mannell
Ariane
A
Hammitzsch
Ramona
R
Mettler
Ulrich
U
Pohl
Florian
F
Krötz
D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D002867:Chromones / Q000494:pharmacology; D051747:DNA-Activated Protein Kinase / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D042783:Endothelial Cells / Q000166:cytology* / Q000378:metabolism*; D016222:Fibroblast Growth Factor 2 / Q000378:metabolism*; D006801:Humans; D009025:Morpholines / Q000494:pharmacology; D009687:Nuclear Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D010768:Phosphoserine / Q000378:metabolism; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics
C479235:2-(morpholin-4-yl)benzo(h)chromen-4-one; D002867:Chromones; D009025:Morpholines; D009687:Nuclear Proteins; D047428:Protein Kinase Inhibitors; D034741:RNA, Small Interfering; D016222:Fibroblast Growth Factor 2; D010768:Phosphoserine; D051747:DNA-Activated Protein Kinase; C497263:PRKDC protein, human; D051057:Proto-Oncogene Proteins c-akt