Transforming growth factor-beta 1 modulates basic fibroblast growth factor-induced proteolytic and angiogenic properties of endothelial cells in vitro.
Tightly controlled proteolytic degradation of the extracellular matrix by invading microvascular endothelial cells is believed to be a necessary component of the angiogenic process. We have previously demonstrated the induction of plasminogen activators (PAs) in bovine microvascular endothelial (BME) cells by three agents that induce angiogenesis in vitro: basic FGF (bFGF), PMA, and sodium orthovanadate. Surprisingly, we find that these agents also induce plasminogen activator inhibitor-1 (PAI-1) activity and mRNA in BME cells. We also find that transforming growth factor-beta 1 (TGF-beta 1), which in vitro modulates a number of endothelial cell functions relevant to angiogenesis, also increases both PAI-1 and urokinase-type PA (u-PA) mRNA. Thus, production of both proteases and protease inhibitors is increased by angiogenic agents and TGF-beta 1. However, the kinetics and amplitude of PAI-1 and u-PA mRNA induction by these agents are strikingly different. We have used the ratio of u-PA:PAI-1 mRNA levels as an indicator of proteolytic balance. This ratio is tilted towards enhanced proteolysis in response to bFGF, towards antiproteolysis in response to TGF-beta 1, and is similar to that in untreated cultures when the two agents are added simultaneously. Using an in vitro angiogenesis assay in three-dimensional fibrin gels, we find that TGF-beta 1 inhibits the bFGF-induced formation of tube-like structures, resulting in the formation of solid endothelial cell cords within the superficial parts of the gel. These results suggest that a net positive proteolytic balance is required for capillary lumen formation. A novel perspective is provided on the relationship between extracellular matrix invasion, lumen formation, and net proteolytic balance, thereby reflecting the interplay between angiogenesis-modulating cytokines such as bFGF and TGF-beta 1.
Institute of Histology and Embryology, University of Geneva Medical Center, Switzerland.
M S
MS
Pepper
D
D
Belin
R
R
Montesano
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Orci
J D
JD
Vassalli
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002417:Cattle; D002478:Cells, Cultured; D004247:DNA / Q000235:genetics / Q000302:isolation & purification; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D004790:Enzyme Induction; D005346:Fibroblast Growth Factors / Q000494:pharmacology*; D007700:Kinetics; D008969:Molecular Sequence Data; D009389:Neovascularization, Pathologic; D010447:Peptide Hydrolases / Q000235:genetics*; D010960:Plasminogen Activators / Q000096:biosynthesis / Q000235:genetics*; D015849:Plasminogen Inactivators; D011498:Protein Precursors / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics; D015183:Restriction Mapping; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014158:Transcription, Genetic / Q000187:drug effects*; D015291:Transforming Growth Factors / Q000494:pharmacology*; D014568:Urokinase-Type Plasminogen Activator / Q000096:biosynthesis / Q000235:genetics*; D014638:Vanadates / Q000494:pharmacology
D015849:Plasminogen Inactivators; D011498:Protein Precursors; D012333:RNA, Messenger; D014638:Vanadates; D005346:Fibroblast Growth Factors; D015291:Transforming Growth Factors; D004247:DNA; D010447:Peptide Hydrolases; D010960:Plasminogen Activators; D014568:Urokinase-Type Plasminogen Activator; D013755:Tetradecanoylphorbol Acetate