TGF-beta1, -beta2 and -beta3 cooperate to facilitate tubulogenesis in the explanted quail heart.
BACKGROUND
Transforming growth factor-beta (TGF-beta) isoforms have been implicated as both pro- and anti-angiogenic modulators. In this study we addressed the roles of TGF-beta isoforms on coronary tubulogenesis.


METHODS
Embryonic (E6) quail ventricular specimens were explanted onto collagen gels allowing endothelial cells to migrate and form vascular tubes. Growth factors and/or neutralizing growth factor antibodies were added to the cultures. Endothelial cells were identified using a quail endothelial cell marker, QH1. Image analysis was used to quantify aggregate tube length.


RESULTS
Addition of any isoform (TGF-beta(1), TGF-beta(2) or TGF-beta(3)) virtually prevented tubulogenesis (>95% inhibition), while stimulation of tubulogenesis occurred by adding neutralizing antibodies to TGF-beta(3), but not to TGF-beta(1) or -beta(2). When all three isoforms were added, tubulogenesis was enhanced, indicating the key role of TGF-beta(3). Documentation of the inhibitory effect of TGF-beta isoforms on tubulogenesis is further supported by our experiments in which the marked enhancement of tube formation by bFGF and VEGF was negated when exogenous TGF-beta(1), -beta(2), or -beta(3) were added to the cultures.


CONCLUSIONS
(1) TGF-beta(1), -beta(2) and -beta(3) each inhibits angiogenesis; (2) cooperation between the three TGF-beta isoforms and other angiogenic factors is essential for the regulation of normal tubulogenesis and (3) the stimulatory effect of VEGF or bFGF on tubulogenesis is negated by exogenous TGB-betas.
Holifield
Jennifer S
JS
Department of Anatomy and Cell Biology and Cardiovascular Center, University of Iowa, Iowa City, IA 52242, USA.
Arlen
Angela M
AM
Runyan
Raymond B
RB
Tomanek
Robert J
RJ
D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D003370:Coturnix; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology; D006321:Heart / Q000187:drug effects* / Q000196:embryology* / Q000502:physiology; D018919:Neovascularization, Physiologic / Q000187:drug effects*; D009924:Organ Culture Techniques; D016212:Transforming Growth Factor beta / Q000276:immunology / Q000494:pharmacology*; D053773:Transforming Growth Factor beta1; D053781:Transforming Growth Factor beta2; D053782:Transforming Growth Factor beta3; D042461:Vascular Endothelial Growth Factor A / Q000494:pharmacology
D000906:Antibodies; C508960:TGFB1 protein, human; C509041:TGFB2 protein, human; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D053781:Transforming Growth Factor beta2; D053782:Transforming Growth Factor beta3; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; D016222:Fibroblast Growth Factor 2