Semaphorin 3d and semaphorin 3e direct endothelial motility through distinct molecular signaling pathways.
Class 3 semaphorins were initially described as axonal growth cone guidance molecules that signal through plexin and neuropilin coreceptors and since then have been established to be regulators of vascular development. Semaphorin 3e (Sema3e) has been shown previously to repel endothelial cells and is the only class 3 semaphorin known to be capable of signaling via a plexin receptor without a neuropilin coreceptor. Sema3e signals through plexin D1 (Plxnd1) to regulate vascular patterning by modulating the cytoskeleton and focal adhesion structures. We showed recently that semaphorin 3d (Sema3d) mediates endothelial cell repulsion and pulmonary vein patterning during embryogenesis. Here we show that Sema3d and Sema3e affect human umbilical vein endothelial cells similarly but through distinct molecular signaling pathways. Time-lapse imaging studies show that both Sema3d and Sema3e can inhibit cell motility and migration, and tube formation assays indicate that both can impede tubulogenesis. Endothelial cells incubated with either Sema3d or Sema3e demonstrate a loss of actin stress fibers and focal adhesions. However, the addition of neuropilin 1 (Nrp1)-blocking antibody or siRNA knockdown of Nrp1 inhibits Sema3d-mediated, but not Sema3e-mediated, cytoskeletal reorganization, and siRNA knockdown of Nrp1 abrogates Sema3d-mediated, but not Sema3e-mediated, inhibition of tubulogenesis. On the other hand, endothelial cells deficient in Plxnd1 are resistant to endothelial repulsion mediated by Sema3e but not Sema3d. Unlike Sema3e, Sema3d incubation results in phosphorylation of Akt in human umbilical vein endothelial cells, and inhibition of the PI3K/Akt pathway blocks the endothelial guidance and cytoskeletal reorganization functions of Sema3d but not Sema3e.
From the Department of Cell and Developmental Biology and the Cardiovascular Institute and Institute for Regenerative Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania 19104.
Haig
H
Aghajanian
From the Department of Cell and Developmental Biology and the Cardiovascular Institute and Institute for Regenerative Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania 19104.
Connie
C
Choi
From the Department of Cell and Developmental Biology and the Cardiovascular Institute and Institute for Regenerative Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania 19104.
Vivienne C
VC
Ho
From the Department of Cell and Developmental Biology and the Cardiovascular Institute and Institute for Regenerative Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania 19104.
Mudit
M
Gupta
From the Department of Cell and Developmental Biology and the Cardiovascular Institute and Institute for Regenerative Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania 19104.
Manvendra K
MK
Singh
From the Department of Cell and Developmental Biology and the Cardiovascular Institute and Institute for Regenerative Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania 19104 epsteinj@upenn.edu.
Jonathan A
JA
Epstein
D000818:Animals; D015816:Cell Adhesion Molecules, Neuronal / Q000235:genetics / Q000378:metabolism; D002465:Cell Movement; D003598:Cytoskeletal Proteins; D003599:Cytoskeleton / Q000235:genetics / Q000378:metabolism; D042783:Endothelial Cells / Q000166:cytology* / Q000201:enzymology / Q000378:metabolism*; D005260:Female; D006023:Glycoproteins / Q000235:genetics / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008297:Male; D008562:Membrane Glycoproteins; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D009419:Nerve Tissue Proteins; D039942:Neuropilin-1 / Q000235:genetics / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics / Q000378:metabolism; D039961:Semaphorins / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D051900:Smad3 Protein / Q000235:genetics / Q000378:metabolism
D015816:Cell Adhesion Molecules, Neuronal; D003598:Cytoskeletal Proteins; D006023:Glycoproteins; D047908:Intracellular Signaling Peptides and Proteins; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D039942:Neuropilin-1; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; D039961:Semaphorins; D051900:Smad3 Protein; C473552:Plxnd1 protein, mouse; C494123:SEMA3E protein, human; C530499:Sema 3D protein, mouse; C000592402:Sema3D protein, human; C111150:Sema3e protein, mouse
Actin; Akt; Cell Motility; Endothelial Cell; Neuropilin; PI3K; Plexin; Semaphorin