Recombinant Transforming Growth Factor Type β3: Biological Activities and Receptor-Binding Properties in Isolated Bone Cells

• Published in: Molecular and cellular biology 1990-09, Vol.10 (9), p.4473-4479
• Main Authors: Ten Duke, Peter, Iwata, Kenneth K., Goddard, Colin, Pieler, Christian, Canalis, Ernesto, Mccarthy, Thomas L., Centrella, Michael
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Cell physiology; Fundamental and applied biological sciences. Psychology; Molecular and cellular biology; Responses to growth factors, tumor promotors, other factors
• ISSN: 0270-7306; 1098-5549; 1098-5549
• DOI: 10.1128/mcb.10.9.4473-4479.1990

We have recently cloned the cDNA for transforming growth factor type β3 (TGF-β3), a new member of the TGF-β gene family. We examined the biological effects of recombinant TGF-β3 protein in osteoblast-enriched bone cell cultures. In this report we demonstrate that TGF-β3 is a potent regulator of functions associated with bone formation, i.e., mitogenesis, collagen synthesis, and alkaline phosphatase activity. In a direct comparison between TGF-β3 and TGF-β1, TGF-β3 appeared to be three· to fivefold more potent than TGF-β1. Our cross-linking experiments with iodinated TGF-β showed that in osteoblast-enriched bone cell cultures, both TGF-β3 and TGF-β1 associated with the same three cell surface binding sites. Scatchard analysis of receptor competition studies indicated the presence of high-affinity binding sites for TGF-β3 in the picomolar range. TGF-β3 showed an approximately fourfold-higher apparent affinity than TGF-β1 in overall binding.