Metalloproteinase/Presenilin1 Processing of ephrinB Regulates EphB-induced Src Phosphorylation and Signaling

EMBO J. 2006 Mar 22;25(6):1242-52. doi: 10.1038/sj.emboj.7601031. Epub 2006 Mar 2.

Abstract

Bidirectional signaling triggered by interacting ephrinB receptors (EphB) and ephrinB ligands is crucial for development and function of the vascular and nervous systems. A signaling cascade triggered by this interaction involves activation of Src kinase and phosphorylation of ephrinB. The mechanism, however, by which EphB activates Src in the ephrinB-expressing cells is unknown. Here we show that EphB stimulates a metalloproteinase cleavage of ephrinB2, producing a carboxy-terminal fragment that is further processed by PS1/gamma-secretase to produce intracellular peptide ephrinB2/CTF2. This peptide binds Src and inhibits its association with inhibitory kinase Csk, allowing autophosphorylation of Src at residue tyr418. EphrinB2/CTF2-activated Src phosphorylates ephrinB2 and inhibits its processing by gamma-secretase. These data show that the PS1/gamma-secretase system controls Src activation and ephrinB phosphorylation by regulating production of Src activator ephrinB2/CTF2. Accordingly, gamma-secretase inhibitors prevented the EphB-induced sprouting of endothelial cells and the recruitment of Grb4 to ephrinB. PS1 FAD and gamma-secretase dominant-negative mutants inhibited the EphB-induced cleavage of ephrinB2 and Src autophosphorylation, raising the possibility that FAD mutants interfere with the functions of Src and ephrinB2 in the CNS.

Publication types

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

MeSH terms

  • Adaptor Proteins, Signal Transducing / metabolism
  • Animals
  • CSK Tyrosine-Protein Kinase
  • Cells, Cultured
  • Ephrin-B2 / metabolism*
  • Fibroblasts / cytology
  • Fibroblasts / metabolism
  • Genes, Dominant
  • Humans
  • Kidney / cytology
  • Kidney / metabolism
  • Membrane Proteins / antagonists & inhibitors
  • Membrane Proteins / genetics
  • Membrane Proteins / physiology*
  • Metalloproteases / metabolism*
  • Mice
  • Mice, Knockout
  • Oncogene Proteins / metabolism
  • Phosphorylation
  • Phosphotransferases / metabolism
  • Presenilin-1
  • Protein Processing, Post-Translational
  • Protein-Tyrosine Kinases
  • Proto-Oncogene Proteins / metabolism
  • Proto-Oncogene Proteins pp60(c-src) / metabolism*
  • Receptor, EphB2 / metabolism*
  • Signal Transduction
  • src-Family Kinases

Substances

  • Adaptor Proteins, Signal Transducing
  • Ephrin-B2
  • Membrane Proteins
  • NCK2 protein, human
  • Oncogene Proteins
  • PSEN1 protein, human
  • Presenilin-1
  • Proto-Oncogene Proteins
  • Phosphotransferases
  • Protein-Tyrosine Kinases
  • Receptor, EphB2
  • CSK Tyrosine-Protein Kinase
  • Proto-Oncogene Proteins pp60(c-src)
  • src-Family Kinases
  • CSK protein, human
  • Metalloproteases