Heterodimers of placenta growth factor/vascular endothelial growth factor. Endothelial activity, tumor cell expression, and high affinity binding to Flk-1/KDR.
Here we show that the Escherichia coli expressed monomers of placenta growth factor (PLGF)129 and vascular endothelial growth factor (VEGF)165 can be re-folded in vitro to form PLGF/VEGF heterodimers. The purified recombinant PLGF/VEGF heterodimers and VEGF homodimers have potent mitogenic and chemotactic effects on endothelial cells. However, PLGF/VEGF heterodimers display 20-50-fold less mitogenic activity than VEGF165 homodimers. In contrast, PLGF129 homodimers have little or no effect in these in vitro assays. We also demonstrate the presence of natural PLGF/VEGF heterodimers in the conditioned media of various human tumor cell lines. While PLGF/VEGF heterodimers bind with high affinity to a soluble Flk-1/KDR receptor, PLGF129 homodimers fail to bind to this receptor. Cross-linking of 125I-ligands to human umbilical vein endothelial cells reveals that PLGF/VEGF heterodimers and VEGF165 homodimers, but not PLGF129 homodimers, form complexes with membrane receptors. VEGF165 homodimers and PLGF/VEGF heterodimers stimulate tyrosine phosphorylation of a 220-kDa protein, the expected size for the KDR receptor in human umbilical vein endothelial cells, whereas PLGF129 homodimers are unable to induce tyrosine phosphorylation of this protein. These data indicate that PLGF may modulate VEGF-induced angiogenesis by the formation of PLGF/VEGF heterodimers in cells producing both factors.
Cao
Y
Y
Department of Surgery, Harvard Medical School, Boston, Massachusetts 02115, USA.
Chen
H
H
Zhou
L
L
Chiang
M K
MK
Anand-Apte
B
B
Weatherbee
J A
JA
Wang
Y
Y
Fang
F
F
Flanagan
J G
JG
Tsang
M L
ML
D043925:Angiogenesis Inducing Agents / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D003001:Cloning, Molecular; D017077:Culture Media, Conditioned; D016228:Endothelial Growth Factors / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology*; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D004797:Enzyme-Linked Immunosorbent Assay; D004926:Escherichia coli; D005260:Female; D015870:Gene Expression; D006367:HeLa Cells; D006801:Humans; D007700:Kinetics; D008222:Lymphokines / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology*; D008961:Models, Structural; D018919:Neovascularization, Physiologic; D010920:Placenta; D000072483:Placenta Growth Factor; D011247:Pregnancy; D011257:Pregnancy Proteins / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology*; D017510:Protein Folding; D055503:Protein Multimerization; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism*; D017978:Receptors, Growth Factor / Q000378:metabolism*; D040262:Receptors, Vascular Endothelial Growth Factor; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D014471:Umbilical Veins; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors
D043925:Angiogenesis Inducing Agents; D017077:Culture Media, Conditioned; D016228:Endothelial Growth Factors; D008222:Lymphokines; C000608036:PGF protein, human; D011257:Pregnancy Proteins; D017978:Receptors, Growth Factor; D011994:Recombinant Proteins; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D000072483:Placenta Growth Factor; D020794:Receptor Protein-Tyrosine Kinases; D040262:Receptors, Vascular Endothelial Growth Factor