Endothelial SCUBE2 Interacts With VEGFR2 and Regulates VEGF-Induced Angiogenesis.
Vascular endothelial growth factor (VEGF), a major mediator of angiogenesis, exerts its proangiogenic action by binding to VEGFR2 (VEGF receptor 2), the activity of which is further modulated by VEGFR2 coreceptors such as neuropilins. However, whether VEGFR2 is regulated by additional coreceptors is not clear. To investigate whether SCUBE2 (signal peptide-CUB-EGF domain-containing protein 2), a peripheral membrane protein expressed in vascular endothelial cells (ECs) known to bind other signaling receptors, functions as a VEGFR2 coreceptor and to verify the role of SCUBE2 in the VEGF-induced angiogenesis.



SCUBE2 lentiviral overexpression in human ECs increased and short hairpin RNA knockdown inhibited VEGF-induced EC growth and capillary-like network formation on Matrigel. Like VEGF, endothelial SCUBE2 was upregulated by hypoxia-inducible factor-1α at both mRNA and protein levels. EC-specific Scube2 knockout mice were not defective in vascular development but showed impaired VEGF-induced neovascularization in implanted Matrigel plugs and recovery of blood flow after hind-limb ischemia. Coimmunoprecipitation and ligand-binding assays showed that SCUBE2 forms a complex with VEGF and VEGFR2, thus acting as a coreceptor to facilitate VEGF binding and augment VEGFR2 signal activity. SCUBE2 knockdown or genetic knockout suppressed and its overexpression promoted the VEGF-induced activation of downstream proangiogenic and proliferating signals, including VEGFR2 phosphorylation and mitogen-activated protein kinase or AKT activation.



Endothelial SCUBE2 may be a novel coreceptor for VEGFR2 and potentiate VEGF-induced signaling in adult angiogenesis.
From the Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan (Y.-C.L., S.R.R., R.K., R.-B.Y.); Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, Taiwan (T.-Y.C., C.-T.Y.); Division of Hematology/Oncology, Department of Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan (T.-Y.C.); Department of Medical Research and Education, Shuang Ho Hospital, Taipei Medical University, Taiwan (C.-T.Y.); and Institute of Pharmacology, National Yang-Ming University, Taipei, Taiwan (R.-B.Y.).
Yuh-Charn
YC
Lin
From the Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan (Y.-C.L., S.R.R., R.K., R.-B.Y.); Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, Taiwan (T.-Y.C., C.-T.Y.); Division of Hematology/Oncology, Department of Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan (T.-Y.C.); Department of Medical Research and Education, Shuang Ho Hospital, Taipei Medical University, Taiwan (C.-T.Y.); and Institute of Pharmacology, National Yang-Ming University, Taipei, Taiwan (R.-B.Y.).
Tsu-Yi
TY
Chao
From the Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan (Y.-C.L., S.R.R., R.K., R.-B.Y.); Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, Taiwan (T.-Y.C., C.-T.Y.); Division of Hematology/Oncology, Department of Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan (T.-Y.C.); Department of Medical Research and Education, Shuang Ho Hospital, Taipei Medical University, Taiwan (C.-T.Y.); and Institute of Pharmacology, National Yang-Ming University, Taipei, Taiwan (R.-B.Y.).
Chi-Tai
CT
Yeh
From the Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan (Y.-C.L., S.R.R., R.K., R.-B.Y.); Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, Taiwan (T.-Y.C., C.-T.Y.); Division of Hematology/Oncology, Department of Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan (T.-Y.C.); Department of Medical Research and Education, Shuang Ho Hospital, Taipei Medical University, Taiwan (C.-T.Y.); and Institute of Pharmacology, National Yang-Ming University, Taipei, Taiwan (R.-B.Y.).
Steve R
SR
Roffler
From the Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan (Y.-C.L., S.R.R., R.K., R.-B.Y.); Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, Taiwan (T.-Y.C., C.-T.Y.); Division of Hematology/Oncology, Department of Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan (T.-Y.C.); Department of Medical Research and Education, Shuang Ho Hospital, Taipei Medical University, Taiwan (C.-T.Y.); and Institute of Pharmacology, National Yang-Ming University, Taipei, Taiwan (R.-B.Y.).
Reiji
R
Kannagi
From the Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan (Y.-C.L., S.R.R., R.K., R.-B.Y.); Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, Taiwan (T.-Y.C., C.-T.Y.); Division of Hematology/Oncology, Department of Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan (T.-Y.C.); Department of Medical Research and Education, Shuang Ho Hospital, Taipei Medical University, Taiwan (C.-T.Y.); and Institute of Pharmacology, National Yang-Ming University, Taipei, Taiwan (R.-B.Y.). rbyang@ibms.sinica.edu.tw.
Ruey-Bing
RB
Yang
D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D002135:Calcium-Binding Proteins; D002465:Cell Movement; D049109:Cell Proliferation; D002478:Cells, Cultured; D004195:Disease Models, Animal; D042783:Endothelial Cells / Q000187:drug effects* / Q000378:metabolism; D005838:Genotype; D006614:Hindlimb; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics / Q000378:metabolism; D036341:Intercellular Signaling Peptides and Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D007511:Ischemia / Q000235:genetics / Q000378:metabolism* / Q000503:physiopathology; D008297:Male; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D018345:Mice, Knockout; D018482:Muscle, Skeletal / Q000098:blood supply*; D018919:Neovascularization, Physiologic / Q000187:drug effects*; D010641:Phenotype; D010766:Phosphorylation; D011485:Protein Binding; D034622:RNA Interference; D015398:Signal Transduction / Q000187:drug effects; D046509:Tissue Culture Techniques; D014162:Transfection; D042461:Vascular Endothelial Growth Factor A / Q000494:pharmacology*; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000819:agonists* / Q000378:metabolism*
D048868:Adaptor Proteins, Signal Transducing; D002135:Calcium-Binding Proteins; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D036341:Intercellular Signaling Peptides and Proteins; D008565:Membrane Proteins; C469999:SCUBE2 protein, human; C432427:Scube2 protein, mouse; D042461:Vascular Endothelial Growth Factor A; C000588866:KDR protein, human; C000592875:Kdr protein, mouse; D040301:Vascular Endothelial Growth Factor Receptor-2
HIF1A protein, human; SCUBE2 protein, human; angiogenesis modulators; endothelial cells; vascular endothelial growth factor A