Ephrin-B1 transduces signals to activate integrin-mediated migration, attachment and angiogenesis.
Ephrin-B/EphB family proteins are implicated in bidirectional signaling and were initially defined through the function of their ectodomain sequences in activating EphB receptor tyrosine kinases. Ephrin-B1-3 are transmembrane proteins sharing highly conserved C-terminal cytoplasmic sequences. Here we use a soluble EphB1 ectodomain fusion protein (EphB1/Fc) to demonstrate that ephrin-B1 transduces signals that regulate cell attachment and migration. EphB1/Fc induced endothelial ephrin-B1 tyrosine phosphorylation, migration and integrin-mediated (alpha(v)beta(3) and alpha(5)beta(1)) attachment and promoted neovascularization, in vivo, in a mouse corneal micropocket assay. Activation of ephrin-B1 by EphB1/Fc induced phosphorylation of p46 JNK but not ERK-1/2 or p38 MAPkinases. By contrast, mutant ephrin-B1s bearing either a cytoplasmic deletion (ephrin-B1DeltaCy) or a deletion of four C-terminal amino acids (ephrin-B1DeltaPDZbd) fail to activate p46 JNK. Transient expression of intact ephin-B1 conferred EphB1/Fc migration responses on CHO cells, whereas the ephrin-B1DeltaCy and ephrin-B1DeltaPDZbd mutants were inactive. Thus ephrin-B1 transduces 'outside-in' signals through C-terminal protein interactions that affect integrin-mediated attachment and migration.
Vanderbilt-Ingram Cancer Center, Departments of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA.
Uyen
U
Huynh-Do
Cécile
C
Vindis
Hua
H
Liu
Douglas Pat
DP
Cerretti
Jeffrey T
JT
McGrew
Miriam
M
Enriquez
Jin
J
Chen
Thomas O
TO
Daniel
D000595:Amino Acid Sequence / Q000235:genetics; D000818:Animals; D016466:CHO Cells; D002448:Cell Adhesion / Q000235:genetics*; D002462:Cell Membrane / Q000378:metabolism*; D002465:Cell Movement / Q000235:genetics*; D003315:Cornea / Q000098:blood supply / Q000254:growth & development / Q000378:metabolism; D006224:Cricetinae; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D036387:Ephrin-B1 / Q000172:deficiency* / Q000235:genetics; D006801:Humans; D016023:Integrins / Q000235:genetics / Q000378:metabolism*; D020935:MAP Kinase Signaling System / Q000235:genetics; D008297:Male; D051379:Mice; D009154:Mutation / Q000235:genetics; D018919:Neovascularization, Physiologic / Q000235:genetics*; D009924:Organ Culture Techniques; D010766:Phosphorylation; D017434:Protein Structure, Tertiary / Q000235:genetics; D036225:Receptor, EphB1 / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins; D015398:Signal Transduction / Q000235:genetics
D036387:Ephrin-B1; D016023:Integrins; D011993:Recombinant Fusion Proteins; D036225:Receptor, EphB1