Specific epidermal growth factor receptor autophosphorylation sites promote mouse colon epithelial cell chemotaxis and restitution

Am J Physiol Gastrointest Liver Physiol. 2011 Aug;301(2):G368-76. doi: 10.1152/ajpgi.00327.2010. Epub 2011 May 26.

Abstract

Upon ligand binding, epidermal growth factor (EGF) receptor (R) autophosphorylates on COOH-terminal tyrosines, generating docking sites for signaling partners that stimulate proliferation, restitution, and chemotaxis. Specificity for individual EGFR tyrosines in cellular responses has been hypothesized but not well documented. Here we tested the requirement for particular tyrosines, and associated downstream pathways, in mouse colon epithelial cell chemotactic migration. We compared these requirements to those for the phenotypically distinct restitution (wound healing) migration. Wild-type, Y992/1173F, Y1045F, Y1068F, and Y1086F EGFR constructs were expressed in EGFR(-/-) cells; EGF-induced chemotaxis or restitution were determined by Boyden chamber or modified scratch wound assay, respectively. Pharmacological inhibitors of p38, phospholipase C (PLC), Src, MEK, JNK/SAPK, phosphatidylinositol 3-kinase (PI 3-kinase), and protein kinase C (PKC) were used to block EGF-stimulated signaling. Pathway activation was determined by immunoblot analysis. Unlike wild-type EGFR, Y992/1173F and Y1086F EGFR did not stimulate colon epithelial cell chemotaxis toward EGF; Y1045F and Y1068F EGFR partially stimulated chemotaxis. Only wild-type EGFR promoted colonocyte restitution. Inhibition of p38, PLC, and Src, or Grb2 knockdown, blocked chemotaxis; JNK, PI 3-kinase, and PKC inhibitors or c-Cbl knockdown blocked restitution but not chemotaxis. All four EGFR mutants stimulated downstream signaling in response to EGF, but Y992/1173F EGFR was partially defective in PLCγ activation whereas both Y1068F and Y1086F EGFR failed to activate Src. We conclude that specific EGFR tyrosines play key roles in determining cellular responses to ligand. Chemotaxis and restitution, which have different migration phenotypes and physiological consequences, have overlapping but not identical EGFR signaling requirements.

Publication types

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

MeSH terms

  • Animals
  • Binding Sites / physiology
  • Cell Line
  • Chemotaxis / drug effects
  • Chemotaxis / physiology*
  • Colon / metabolism
  • Epidermal Growth Factor / metabolism
  • Epidermal Growth Factor / physiology*
  • Epithelial Cells / metabolism
  • Epithelial Cells / physiology*
  • ErbB Receptors / deficiency
  • ErbB Receptors / genetics
  • ErbB Receptors / metabolism*
  • ErbB Receptors / physiology
  • GRB2 Adaptor Protein / deficiency
  • GRB2 Adaptor Protein / physiology
  • Mice
  • Mutation
  • Phospholipase C gamma / physiology
  • Phosphorylation
  • Proto-Oncogene Proteins c-cbl / deficiency
  • Proto-Oncogene Proteins c-cbl / physiology
  • RNA, Small Interfering
  • Signal Transduction / physiology*
  • Transfection
  • Tyrosine / physiology*
  • Wound Healing / drug effects
  • Wound Healing / physiology
  • p38 Mitogen-Activated Protein Kinases / physiology
  • src Homology Domains / physiology
  • src-Family Kinases

Substances

  • GRB2 Adaptor Protein
  • RNA, Small Interfering
  • Tyrosine
  • Epidermal Growth Factor
  • Proto-Oncogene Proteins c-cbl
  • ErbB Receptors
  • src-Family Kinases
  • p38 Mitogen-Activated Protein Kinases
  • Phospholipase C gamma
  • CBL protein, human