Expression of vascular endothelial growth factors and their receptors during osteoblast differentiation.
Endochondral bone formation is regulated by systemically and locally acting growth factors. A role for vascular endothelial growth factor (VEGF) in this process has recently been proposed, because inactivation of VEGF inhibits endochondral bone formation via inhibition of angiogenesis. Despite the known effect of VEGF as specific endothelial growth factor, its effects on osteoblast differentiation have not been studied. We, therefore, examined the expression of VEGF-A, -B, -C, and -D and their receptors in a model of osteoblast differentiation using the mouse preosteoblast-like cell line KS483. Early in differentiation, KS483 cells express low levels VEGF-A, -B, and -D messenger RNA, whereas during mineralization, KS483 cells express high levels. In addition, expression of the VEGF receptors, VEGFR1, VEGFR2, and VEGF165R/neuropilin, coincided with expression of their ligands, being maximally expressed during mineralization. VEGF-A production during osteoblast differentiation was stimulated by insulin-like growth factor I that enhances osteoblast differentiation and was inhibited by PTH-related peptide that inhibits osteoblast differentiation. Furthermore, continuous treatment of KS483 cells with recombinant human VEGF-A stimulated nodule formation. Although treatment of KS483 cells with soluble FLT1, an agent that blocks binding of VEGF-A and -B to VEGFR1, did not inhibit nodule formation, this observation does not exclude involvement of VEGFR2 in the regulation of osteoblast differentiation. As it is known that VEGF-A, -C, and -D can act through activation of VEGFR2, other isoforms might compensate for VEGF-A loss. The expression pattern of VEGFs and their receptors shown here suggests that VEGFs play an important role in the regulation of bone remodeling by attracting endothelial cells and osteoclasts and by stimulating osteoblast differentiation.
Deckers
M M
MM
Department of Endocrinology and Metabolic Diseases, Leiden University Medical Center, The Netherlands. m.m.l.deckers@lumc.nl
Karperien
M
M
van der Bent
C
C
Yamashita
T
T
Papapoulos
S E
SE
Löwik
C W
CW
D000818:Animals; D002454:Cell Differentiation; D002460:Cell Line; D004591:Electrophoresis, Polyacrylamide Gel; D016228:Endothelial Growth Factors / Q000096:biosynthesis* / Q000235:genetics; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology; D008222:Lymphokines / Q000096:biosynthesis*; D051379:Mice; D010006:Osteoblasts / Q000502:physiology*; D044162:Parathyroid Hormone-Related Protein; D016133:Polymerase Chain Reaction; D011506:Proteins / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D020794:Receptor Protein-Tyrosine Kinases / Q000096:biosynthesis*; D011956:Receptors, Cell Surface / Q000096:biosynthesis; D017978:Receptors, Growth Factor / Q000096:biosynthesis*; D040262:Receptors, Vascular Endothelial Growth Factor; D042461:Vascular Endothelial Growth Factor A; D042561:Vascular Endothelial Growth Factor B; D042582:Vascular Endothelial Growth Factor C; D042643:Vascular Endothelial Growth Factor D; D040321:Vascular Endothelial Growth Factor Receptor-3; D042442:Vascular Endothelial Growth Factors
D016228:Endothelial Growth Factors; D008222:Lymphokines; C470121:PTHLH protein, human; D044162:Parathyroid Hormone-Related Protein; D011506:Proteins; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D017978:Receptors, Growth Factor; D042461:Vascular Endothelial Growth Factor A; D042561:Vascular Endothelial Growth Factor B; D042582:Vascular Endothelial Growth Factor C; D042643:Vascular Endothelial Growth Factor D; D042442:Vascular Endothelial Growth Factors; D007334:Insulin-Like Growth Factor I; D020794:Receptor Protein-Tyrosine Kinases; D040262:Receptors, Vascular Endothelial Growth Factor; D040321:Vascular Endothelial Growth Factor Receptor-3