title: Role of TGF-beta1 and JNK signaling in capillary tube patterning.
abstract: The transforming growth factor (TGF) family of secretory polypeptides comprises signaling proteins involved in numerous physiological processes, including vascular development and vessel wall integrity. Both pro- and anti-angiogenic effects of TGF-beta1 have also been documented. To study the intracellular mechanisms involved in capillary tube morphogenesis, endothelial cell aggregates were cultured in a fibrin matrix. It was found that the pattern of capillary tubes formed in a fibrin matrix was altered in response to TGF-beta1 treatment such that the capillary-like structures displayed a bipolarized pattern. In contrast, in untreated control and fibroblast growth factor-2-treated cells, the pattern of capillary tubes formed was random. TGF-beta1 also downregulated urokinase-type plasminogen activator (uPA) activity while upregulating PA inhibitor (PAI)-1 and thrombospondin (TSP)1 gene expression. To investigate the signaling cascade mediating the phenotypic changes observed, pharmacological inhibitors of p38 MAPK, Sp1 transcription factor, c-Jun NH(2)-terminal kinase (JNK), and the cytokine TNF-alpha were used. The p38 MAPK inhibitor SB203580 reversed the TGF-beta1-dependent inhibition of uPA activity but not its morphogenetic effect. In contrast, the DNA intercalator WP631 and TNF-alpha counteracted the TGF-beta1-induced morphogenetic effect while the JNK inhibitor SP600125 effectively inhibited capillary tube formation. These results indicate that the TGF-beta1-induced capillary tube pattern is independent of the p38 MAPK-activated PAI-1 and TSP1 expression, but the mechanism involves Sp1-dependent transcriptional regulation. The results also raise the possibility that the JNK pathway, which controls convergent extension in Xenopus, may be involved in vessel wall patterning in mammalian systems.
authors.affiliation: Dartmouth-Hitchcock Medical Center, 1 Medical Center Drive, Borwell Research Bldg., 550W, Lebanon, NH 03756, USA. Kiflai.Bein@Dartmouth.Edu
authors.forename: Kiflai
authors.initials: K
authors.lastname: Bein
authors.forename: Elizabeth T
authors.initials: ET
authors.lastname: Odell-Fiddler
authors.forename: Mary
authors.initials: M
authors.lastname: Drinane
mesh_terms: D000818:Animals; D015152:Blotting, Northern; D015153:Blotting, Western; D019521:Body Patterning; D002196:Capillaries / Q000187:drug effects / Q000378:metabolism*; D002417:Cattle; D002449:Cell Aggregation; D002465:Cell Movement; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism*; D005337:Fibrin; D007091:Image Processing, Computer-Assisted; D048031:JNK Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D018919:Neovascularization, Physiologic; D017395:Plasminogen Activator Inhibitor 1 / Q000378:metabolism; D011494:Protein Kinases / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000502:physiology*; D019700:Thrombospondin 1 / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000494:pharmacology*; D053773:Transforming Growth Factor beta1; D048051:p38 Mitogen-Activated Protein Kinases
chemical_list: D017395:Plasminogen Activator Inhibitor 1; D019700:Thrombospondin 1; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D005337:Fibrin; D011494:Protein Kinases; C065999:Sp1 kinase; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D020929:Mitogen-Activated Protein Kinase Kinases