Characterization of the Activation of Latent TGF-β by Co-Cultures of Endothelial Cells and Pericytes or Smooth Muscle Cells: A Self-Regulating System

The conversion of latent transforming growth factor beta (LTGF-β) to the active species, transforming growth factor beta (TGF-β), has been characterized in heterotypic cultures of bovine aortic endothelial (BAE) cells and bovine smooth muscle cells (SMCs). The formation of TGF-β in co-cultures of BA...

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Bibliographic Details
Published in:The Journal of cell biology 1990-08, Vol.111 (2), p.757-763
Main Authors: Sato, Y., Tsuboi, R., Lyons, R., Moses, H., Rifkin, D. B.
Format: Article
Language:English
Subjects:
Analytical, structural and metabolic biochemistry
Animals
Antibodies
Biological and medical sciences
Cattle
Cell Communication
Cell culture techniques
Cell growth
Cell Movement - drug effects
Cells
Cells, Cultured
Coculture techniques
Cultured cells
Endothelial cells
endothelium
Endothelium, Vascular - cytology
Endothelium, Vascular - physiology
Fibroblast growth factors
Fundamental and applied biological sciences. Psychology
Human growth
Kinetics
Macromolecular Substances
Muscle, Smooth - cytology
Muscle, Smooth - physiology
Muscle, Smooth, Vascular - cytology
Muscle, Smooth, Vascular - physiology
Poly A - isolation & purification
Protein hormones. Growth factors. Cytokines
Protein Processing, Post-Translational
Proteins
Receptors, Cell Surface - metabolism
Receptors, Transforming Growth Factor beta
RNA - isolation & purification
RNA, Messenger - genetics
RNA, Messenger - isolation & purification
transforming growth factor- beta
Transforming growth factors
Transforming Growth Factors - genetics
Transforming Growth Factors - metabolism
Transforming Growth Factors - pharmacology
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Summary:The conversion of latent transforming growth factor beta (LTGF-β) to the active species, transforming growth factor beta (TGF-β), has been characterized in heterotypic cultures of bovine aortic endothelial (BAE) cells and bovine smooth muscle cells (SMCs). The formation of TGF-β in co-cultures of BAE cells and SMCs was documented by a specific radioreceptor competition assay, while medium from homotypic cultures of BAE cells or SMCs contained no active TGF-β as determined by this assay. The concentration of TGF-β in the conditioned medium of heterotypic co-cultures was estimated to be 400-1,200 pg/ml using the inhibition of BAE cell migration as an assay. Northern blotting of poly A+ RNA extracted from both homotypic and heterotypic cultures of BAE cells and SMCs revealed that BAE cells produced both TGF-β1 and TGF-β2, while SMCs produced primarily TGF-β1. No change in the expression of these two forms of TGF-β was apparent after 24 h in heterotypic cultures. Time course studies on the appearance of TGF-β indicated that most of the active TGF-β was generated within the first 12 h after the establishment of co-cultures. The generation of TGF-β in co-cultures stimulated the production of the protease inhibitor plasminogen activator inhibitor-1 (PAI-1). The inclusion of neutralizing antibodies to TGF-β in the co-culture medium blocked the observed increase in PAI-1 levels. The increased expression of PAI-1 subsequent to TGF-β formation blocked the activation of the protease required for conversion of LTGF-β to TGF-β as the inclusion of neutralizing antibodies to PAI-1 in the co-culture medium resulted in prolonged production of TGF-β. This effect was lost upon removal of the PAI-1 antibodies. Thus, the activation of LTGF-β appears to be a self-regulating system.
ISSN:0021-9525
1540-8140
DOI:10.1083/jcb.111.2.757