AJP - Cell Physiology, Vol 261, Issue 6 C980-C985, Copyright © 1991 by American Physiological Society
High-affinity binding of PDGF-AA and PDGF-BB to normal human osteoblastic cells and modulation by interleukin-1
R. S. Gilardetti, M. S. Chaibi, J. Stroumza, S. R. Williams, H. N. Antoniades, D. C. Carnes and D. T. Graves
Department of Oral Biology, Boston University Medical Center 02118.
Bone has the capacity for repair and regeneration. The repair process is
thought to be locally regulated by growth factors. One of the growth
factors that potentially plays a significant role in these processes is
platelet-derived growth factor (PDGF). Two different PDGF genes have been
identified, PDGF-A and PDGF-B, whose gene products give rise to
biologically active dimers. We now report that PDGF-AA and PDGF-BB exhibit
saturable binding to normal human osteoblastic cells. By Scatchard analysis
we estimate that there are approximately 43,000 PDGF-AA binding sites per
cell, with a dissociation constant (Kd) of 2.2 x 10(-10)M, and 55,000
high-affinity PDGF-BB binding sites per cell, with a Kd of 1.2 x 10(-10)M.
The functional consequence of PDGF binding was also assessed. PDGF-AA and
PDGF-BB both stimulated migration of normal human osteoblastic cells and
stimulated thymidine incorporation. To gain insight into potential
transmodulation of the PDGF response, we investigated the capacity of
interleukin-1 beta (IL-1 beta), a cytokine that induces bone resorption, to
modulate PDGF binding and PDGF-induced biological activity. IL-1 beta
significantly reduced PDGF-AA binding and significantly decreased both
PDGF-AA-mediated cell migration and thymidine incorporation. In contrast,
IL-1 beta had only a small effect of PDGF-BB binding and PDGF-BB-induced
biological activity in normal human osteoblastic cells.
