Cholesterol depletion inhibits epidermal growth factor receptor transactivation by angiotensin II in vascular smooth muscle cells: role of cholesterol-rich microdomains and focal adhesions in angiotensin II signaling

J Biol Chem. 2001 Dec 21;276(51):48269-75. doi: 10.1074/jbc.M105901200. Epub 2001 Oct 3.


Angiotensin II (Ang II) induces transactivation of the epidermal growth factor (EGF) receptor (EGF-R), which serves as a scaffold for various signaling molecules in vascular smooth muscle cells (VSMCs). Cholesterol and sphingomyelin-enriched lipid rafts are plasma membrane microdomains that concentrate various signaling molecules. Caveolae are specialized lipid rafts that are organized by the cholesterol-binding protein, caveolin, and have been shown to be associated with EGF-Rs. Angiotensin II stimulation promotes a rapid movement of AT(1) receptors to caveolae; however, their functional role in angiotensin II signaling has not been elucidated. Here we show that cholesterol depletion by beta-cyclodextrin disrupts caveolae structure and concomitantly inhibits tyrosine phosphorylation of the EGF-R and subsequent activation of protein kinase B (PKB)/Akt induced by angiotensin II. Similar inhibitory effects were obtained with other cholesterol-binding agents, filipin and nystatin. In contrast, EGF-R autophosphorylation and activation of Akt/PKB in response to EGF are not affected by cholesterol depletion. The early Ang II-induced upstream signaling events responsible for transactivation of the EGF-R, such as the intracellular Ca(2+) increase and c-Src activation, also remain intact. The EGF-R initially binds caveolin, but these two proteins rapidly dissociate following angiotensin II stimulation during the time when EGF-R transactivation is observed. The activated EGF-R is localized in focal adhesions together with tyrosine-phosphorylated caveolin. These findings suggest that 1) a scaffolding role of caveolin is essential for EGF-R transactivation by angiotensin II and 2) cholesterol-rich microdomains as well as focal adhesions are important signal-organizing compartments required for the spatial and temporal organization of angiotensin II signaling in VSMCs.

Publication types

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

MeSH terms

  • Angiotensin II / physiology*
  • Animals
  • Caveolin 1
  • Caveolins / metabolism
  • Cell Membrane / drug effects
  • Cell Membrane / metabolism
  • Cells, Cultured
  • Cholesterol / metabolism*
  • Cyclodextrins / pharmacology
  • Enzyme Activation
  • Epidermal Growth Factor / physiology
  • ErbB Receptors / chemistry
  • ErbB Receptors / genetics*
  • Fluorescent Antibody Technique
  • Male
  • Microscopy, Electron
  • Muscle, Smooth, Vascular / drug effects
  • Muscle, Smooth, Vascular / physiology*
  • Muscle, Smooth, Vascular / ultrastructure
  • Phosphorylation
  • Protein Binding
  • Protein Serine-Threonine Kinases*
  • Proto-Oncogene Proteins / metabolism
  • Proto-Oncogene Proteins c-akt
  • Rats
  • Rats, Sprague-Dawley
  • Signal Transduction
  • Transcriptional Activation*
  • Tyrosine / metabolism
  • beta-Cyclodextrins*


  • Cav1 protein, rat
  • Caveolin 1
  • Caveolins
  • Cyclodextrins
  • Proto-Oncogene Proteins
  • beta-Cyclodextrins
  • Angiotensin II
  • Tyrosine
  • Epidermal Growth Factor
  • Cholesterol
  • ErbB Receptors
  • Akt1 protein, rat
  • Protein Serine-Threonine Kinases
  • Proto-Oncogene Proteins c-akt
  • betadex