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The SH2/SH3 adaptor Grb4 transduces B-ephrin reverse signals.

Bidirectional signals mediated by membrane-anchored ephrins and Eph receptor tyrosine kinases have important functions in cell-cell recognition events, including those that occur during axon pathfinding and hindbrain segmentation. The reverse signal that is transduced into B-ephrin-expressing cells is thought to involve tyrosine phosphorylation of the signal's short, conserved carboxy-terminal cytoplasmic domain. The Src-homology-2 (SH2) domain proteins that associate with activated tyrosine-phosphorylated B-subclass ephrins have not been identified, nor has a defined cellular response to reverse signals been described. Here we show that the SH2/SH3 domain adaptor protein Grb4 binds to the cytoplasmic domain of B ephrins in a phosphotyrosine-dependent manner. In response to B-ephrin reverse signalling, cells increase FAK catalytic activity, redistribute paxillin, lose focal adhesions, round up, and disassemble F-actin-containing stress fibres. These cellular responses can be blocked in a dominant-negative fashion by expression of the isolated Grb4 SH2 domain. The Grb4 SH3 domains bind a unique set of other proteins that are implicated in cytoskeletal regulation, including the Cbl-associated protein (CAP/ponsin), the Abl-interacting protein-1 (Abi-1), dynamin, PAK1, hnRNPK and axin. These data provide a biochemical pathway whereby cytoskeletal regulators are recruited to Eph-ephrin bidirectional signalling complexes.

Pubmed ID: 11557983

Authors

  • Cowan CA
  • Henkemeyer M

Journal

Nature

Publication Data

September 13, 2001

Associated Grants

None

Mesh Terms

  • Adaptor Proteins, Signal Transducing
  • Amino Acid Sequence
  • Animals
  • Axin Protein
  • Cell Line
  • Cell Membrane
  • Cytoskeletal Proteins
  • Cytoskeleton
  • Ephrin-B1
  • Glutathione Transferase
  • Humans
  • Membrane Proteins
  • Mice
  • Microfilament Proteins
  • Molecular Sequence Data
  • Neurons
  • Oncogene Proteins
  • Phosphotyrosine
  • Protein Binding
  • Proteins
  • Receptor Protein-Tyrosine Kinases
  • Receptor, EphB4
  • Receptors, Eph Family
  • Recombinant Fusion Proteins
  • Repressor Proteins
  • Signal Transduction
  • Two-Hybrid System Techniques
  • src Homology Domains