Regulation of endothelial cell differentiation and transformation by H-Ras.
Angiogenesis is regulated by growth factors which activate tyrosine kinase receptors leading to the activation of a number of intracellular signaling pathways. The specific function of H-Ras during FGF-2 stimulated endothelial cell differentiation, defined as invasive growth and formation of branching networks in fibrin gels, was investigated by using conditionally immortalized endothelial cell lines induced to express H-Ras mutants. Expression of inhibitory N17Ras did not impair differentiation in response to FGF-2 and TNF-alpha. The farnesyltransferase inhibitor FTI-277 inhibited farnesylation of Ras but did not inhibit differentiation of human microvascular endothelial cells or mouse brain endothelial cells. In contrast, activated V12Ras inhibited endothelial cell differentiation and cells displayed a transformed phenotype with an increased rate of proliferation and loss of contact inhibited growth. Furthermore, V12Ras expressing endothelial cells grew as solid tumors when injected subcutaneously into mice. Our data suggest that, in endothelial cells, H-Ras activity is not required for differentiation. However, this activity must be tightly regulated as aberrant activity can disturb the ability of endothelial cells to undergo differentiation.
Department of Genetics and Pathology, Vascular Biology Unit, The Rudbeck Laboratory, Uppsala University, S-751 85 Uppsala, Sweden.
Emma
E
Rennel
Michael J
MJ
Cross
Peter
P
Klint
Xianhe
X
Bai
Jack L
JL
Arbiser
Pär
P
Gerwins
D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects / Q000235:genetics*; D002455:Cell Division / Q000187:drug effects / Q000235:genetics; D002461:Cell Line, Transformed; D002471:Cell Transformation, Neoplastic; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016222:Fibroblast Growth Factor 2 / Q000378:metabolism / Q000494:pharmacology; D011905:Genes, ras / Q000235:genetics*; D006394:Hemangiosarcoma / Q000235:genetics; D006801:Humans; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000235:genetics; D009154:Mutation / Q000187:drug effects / Q000235:genetics; D009361:Neoplasm Invasiveness / Q000235:genetics; D009389:Neovascularization, Pathologic / Q000235:genetics; D018919:Neovascularization, Physiologic / Q000187:drug effects / Q000235:genetics*; D017368:Protein Prenylation / Q000187:drug effects; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism / Q000494:pharmacology; D018631:ras Proteins / Q000235:genetics*
D004791:Enzyme Inhibitors; D014409:Tumor Necrosis Factor-alpha; D016222:Fibroblast Growth Factor 2; D018631:ras Proteins