Mechanisms of vascular angiotensin II surface receptor regulation by epidermal growth factor

J Cell Physiol. 2004 Sep;200(3):451-7. doi: 10.1002/jcp.20027.


We investigated mechanisms by which epidermal growth factor (EGF) reduces angiotensin II (AngII) surface receptor density and stimulated actions in vascular smooth muscle cells (VSMC). EGF downregulated specific AngII radioligand binding in intact cultured rat aortic smooth muscle cells but not in cell membranes and also inhibited AngII-stimulated contractions of aortic segments. Inhibitors of cAMP-dependent kinases, PI-3 kinase, MAP kinase, cyclooxygenase, and calmodulin did not prevent EGF-mediated downregulation of AngII receptor binding, whereas the EGF receptor kinase inhibitor AG1478 did. Total cell AngII AT1a receptor protein content of EGF-treated and untreated cells, measured by immunoblotting, did not differ. Actinomycin D or cytochalasin D, which interacts with the cytoskeleton, but not the protein synthesis inhibitor cycloheximide, prevented EGF from downregulating AngII receptor binding. Consistently, EGF inhibited AngII-stimulated formation of inositol phosphates in the presence of cycloheximide but not in the presence of actinomycin D or cytochalasin D. In conclusion, EGF needs an intact signal transduction pathway to downregulate AngII surface receptor binding, possibly by altering cellular location of the receptors.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Angiotensin II / metabolism*
  • Angiotensin II / pharmacology
  • Animals
  • Aorta, Thoracic / cytology
  • Cells, Cultured
  • Cytochalasin D / pharmacology
  • Dactinomycin / pharmacology
  • Down-Regulation / drug effects*
  • Enzyme Inhibitors / pharmacology
  • Epidermal Growth Factor / pharmacology*
  • ErbB Receptors / drug effects
  • Ligands
  • Muscle, Smooth, Vascular / cytology
  • Muscle, Smooth, Vascular / drug effects
  • Muscle, Smooth, Vascular / metabolism*
  • Quinazolines
  • Rats
  • Rats, Sprague-Dawley
  • Receptors, Angiotensin / metabolism*
  • Tyrphostins / pharmacology


  • Enzyme Inhibitors
  • Ligands
  • Quinazolines
  • Receptors, Angiotensin
  • Tyrphostins
  • Angiotensin II
  • RTKI cpd
  • Dactinomycin
  • Cytochalasin D
  • Epidermal Growth Factor
  • ErbB Receptors