Platelet-derived growth factor receptor-beta constitutive activity promotes angiogenesis in vivo and in vitro.
OBJECTIVE
Knockout studies have demonstrated crucial roles for the platelet-derived growth factor-B and its cognate receptor, platelet-derived growth factor receptor-beta (PDGFR-beta), in blood vessel maturation, that is, the coverage of newly formed vessels with mural cells/pericytes. This study describes the consequences of a constitutively activating mutation of the PDGFR-beta (Pdgfrb(D849V)) introduced into embryonic stem cells with respect to vasculogenesis/angiogenesis in vitro and in vivo.


RESULTS
Embryonic stem cells were induced to either form teratomas in vivo or embryoid bodies, an in vitro model for mouse embryogenesis. Western blotting studies on embryoid bodies showed that expression of a single allele of the mutant Pdgfrb led to increased levels of PDGFR-beta tyrosine phosphorylation and augmented downstream signal transduction. This was accompanied by enhanced vascular development, followed by exaggerated angiogenic sprouting with abundant pericyte coating as shown by immunohistochemistry/immunofluorescence. Pdgfrb(D849V/+) embryoid bodies were characterized by increased expression of vascular endothelial growth factor (VEGF)-A and VEGF receptor-2; neutralizing antibodies against VEGF-A/VEGF receptor-2 blocked vasculogenesis and angiogenesis in mutant embryoid bodies. Moreover, Pdgfrb(D849V/+) embryonic stem cell-derived teratomas in nude mice were more densely vascularized than wild-type teratomas.


CONCLUSIONS
Increased PDGFR-beta kinase activity is associated with elevated expression of VEGF-A and VEGF receptor-2, acting directly on endothelial cells and resulting in increased vessel formation.
Department of Genetics and Pathology, Rudbeck Laboratory, Uppsala University, Uppsala, Sweden.
Peetra U
PU
Magnusson
Camilla
C
Looman
Aive
A
Ahgren
Yan
Y
Wu
Lena
L
Claesson-Welsh
Rainer L
RL
Heuchel
D000818:Animals; D000077214:Becaplermin; D002454:Cell Differentiation; D002460:Cell Line; D047108:Embryonic Development; D053595:Embryonic Stem Cells / Q000201:enzymology / Q000378:metabolism*; D018390:Gene Targeting; D051379:Mice; D008819:Mice, Nude; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D009389:Neovascularization, Pathologic / Q000378:metabolism*; D018919:Neovascularization, Physiologic; D020286:Pericytes / Q000378:metabolism; D010766:Phosphorylation; D010982:Platelet-Derived Growth Factor / Q000378:metabolism; D017354:Point Mutation; D020574:Proto-Oncogene Proteins c-sis; D020710:RGS Proteins / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D020797:Receptor, Platelet-Derived Growth Factor beta / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D013724:Teratoma / Q000098:blood supply / Q000378:metabolism*; D013997:Time Factors; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000378:metabolism
D010982:Platelet-Derived Growth Factor; D020574:Proto-Oncogene Proteins c-sis; D020710:RGS Proteins; D012333:RNA, Messenger; C105346:Rgs5 protein, mouse; D042461:Vascular Endothelial Growth Factor A; C467480:vascular endothelial growth factor A, mouse; D000077214:Becaplermin; D020797:Receptor, Platelet-Derived Growth Factor beta; D040301:Vascular Endothelial Growth Factor Receptor-2; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3