Endothelial cell activation in a VEGF-A gradient: relevance to cell fate decisions

Microvasc Res. 2010 Jul;80(1):65-74. doi: 10.1016/j.mvr.2010.02.001. Epub 2010 Feb 6.

Abstract

Distribution of vascular endothelial cell growth factor A (VEGF-A) as a gradient determines microvascular endothelial cell (EC) fate during organogenesis. While much is understood about mechanisms of differential distribution, less is known about how EC perceive and interpret a graded VEGF-A signal to generate positional target gene activation. Using microvascular EC, we analyzed the effect of time and graded VEGF-A input on VEGFR2 autophosphorylation, signal kinase activation and induction of immediate-early genes. The threshold and time to peak activation of VEGFR2 were dependent on signal strength over a 50-fold range in concentration with 3-fold concentration differences readily distinguished. Longer duration of exposure did not compensate for low concentration of VEGF-A, suggesting intensity and duration of signal were not interpreted equivalently. With the same conditions, graded and time-sensitive information was transduced through the PLCgamma/p44/p42MAPK signal pathway but not the parallel AKT pathway. Analysis of MAPK-induced angiogenic immediate-early genes determined that EGR-1, EGR-3, and NR4A1 were dependent on graded input while NR4A2 and DSCR1 were independent with 'switch-like' induction. These data demonstrate rapid, linear integration of VEGF-A levels but independent interpretation of duration of signal and identify potential nodes for segregation of gradient-dependent and -independent responses. These results describe how microvascular EC fate decisions can be determined by comparatively moderate changes in VEGF signal strength, resulting in combinatorial changes in the repertoire of immediate-early genes for transcription effectors.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Cell Movement / drug effects
  • Cell Proliferation / drug effects
  • Cells, Cultured
  • DNA-Binding Proteins
  • Dose-Response Relationship, Drug
  • Early Growth Response Protein 1 / genetics
  • Early Growth Response Protein 3 / genetics
  • Embryo, Mammalian / cytology
  • Embryo, Mammalian / metabolism
  • Endothelial Cells / cytology*
  • Endothelial Cells / drug effects
  • Endothelial Cells / metabolism*
  • Epithelial Cells / cytology
  • Epithelial Cells / metabolism
  • Female
  • Gene Expression / drug effects
  • Gene Expression / genetics
  • Gene Expression Regulation, Developmental / physiology*
  • Humans
  • Intracellular Signaling Peptides and Proteins / genetics
  • Kinetics
  • Lung / cytology
  • Lung / metabolism
  • Mice
  • Mice, Inbred Strains
  • Mice, Transgenic
  • Mitogen-Activated Protein Kinase 1 / metabolism
  • Mitogen-Activated Protein Kinase 3 / metabolism
  • Muscle Proteins / genetics
  • Nuclear Receptor Subfamily 4, Group A, Member 1 / genetics
  • Nuclear Receptor Subfamily 4, Group A, Member 2 / genetics
  • Phospholipase C gamma / metabolism
  • Phosphorylation / drug effects
  • Proto-Oncogene Proteins c-akt / metabolism
  • Tyrosine / metabolism
  • Vascular Endothelial Growth Factor A / genetics
  • Vascular Endothelial Growth Factor A / pharmacology*
  • Vascular Endothelial Growth Factor Receptor-2 / metabolism

Substances

  • DNA-Binding Proteins
  • EGR1 protein, human
  • Early Growth Response Protein 1
  • Intracellular Signaling Peptides and Proteins
  • Muscle Proteins
  • NR4A1 protein, human
  • NR4A2 protein, human
  • Nuclear Receptor Subfamily 4, Group A, Member 1
  • Nuclear Receptor Subfamily 4, Group A, Member 2
  • RCAN1 protein, human
  • VEGFA protein, human
  • Vascular Endothelial Growth Factor A
  • vascular endothelial growth factor A, mouse
  • Early Growth Response Protein 3
  • Tyrosine
  • Vascular Endothelial Growth Factor Receptor-2
  • Proto-Oncogene Proteins c-akt
  • Mitogen-Activated Protein Kinase 1
  • Mitogen-Activated Protein Kinase 3
  • Phospholipase C gamma