Effect of vascular endothelial growth factor on RANK gene expression in osteoclast precursors and on osteoclastogenesis.
OBJECTIVE
The aim of this study was to determine if vascular endothelial growth factor (VEGF) can upregulate the gene expression of receptor activator of nuclear factor kappa B (RANK) in osteoclast precursors, as does CSF-1. A secondary aim was to determine if VEGF can promote osteoclastogenesis in vitro comparable to CSF-1.


METHODS
Osteoclast precursors (mononuclear cells) were incubated with different concentrations of VEGF, CSF-1, or a combination of the two, and the gene expression of RANK was determined by RT-PCR. A TRAP assay also was conducted to determine their effect on osteoclastogenesis. An Alamar blue assay was done to analyse the effect of the molecules on proliferation of the osteoclast precursors.


RESULTS
VEGF upregulated RANK expression in osteoclast precursors as effectively as CSF-1. VEGF did not promote osteoclastogenesis, as did CSF-1. A combination of the two did. CSF-1 enhanced proliferation of the osteoclast precursors but VEGF did not. However, VEGF in combination with CSF-1 did increase proliferation.


CONCLUSIONS
At the time of the secondary burst of osteoclastogenesis prior to tooth eruption, VEGF expression in the dental follicle is high but the expression of CSF-1 is low. This study demonstrates that VEGF can fully substitute for CSF-1 to upregulate the RANK expression in osteoclast precursors that is needed for osteoclastogenesis. However, VEGF alone neither can promote osteoclastogenesis nor stimulate proliferation of the osteoclast precursors in vitro. For proliferation and osteoclastogenesis, a low dose of CSF-1 in combination with VEGF is needed.
Yao
Shaomian
S
Department of Comparative Biomedical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA 70803, USA.
Liu
Dawen
D
Pan
Fenghui
F
Wise
Gary E
GE
D000818:Animals; D039481:CD11b Antigen / Q000032:analysis; D049109:Cell Proliferation; D015870:Gene Expression; D006041:Goats; D006801:Humans; D016173:Macrophage Colony-Stimulating Factor / Q000494:pharmacology*; D008297:Male; D051379:Mice; D010010:Osteoclasts / Q000187:drug effects* / Q000378:metabolism; D051381:Rats; D053246:Receptor Activator of Nuclear Factor-kappa B / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D013154:Spleen / Q000166:cytology; D014078:Tooth Eruption / Q000502:physiology; D015854:Up-Regulation / Q000187:drug effects; D042461:Vascular Endothelial Growth Factor A / Q000494:pharmacology*
D039481:CD11b Antigen; D053246:Receptor Activator of Nuclear Factor-kappa B; D042461:Vascular Endothelial Growth Factor A; D016173:Macrophage Colony-Stimulating Factor