A novel endocytic mechanism of epidermal growth factor receptor sequestration and internalization.
Cells form transient, circular dorsal ruffles or "waves" in response to stimulation of receptor tyrosine kinases, including epidermal growth factor receptor (EGFR) or platelet-derived growth factor receptor. These dynamic structures progress inward on the dorsal surface and disappear, occurring concomitantly with a marked reorganization of F-actin. The cellular function of these structures is largely unknown. Here we show that EGF-induced waves selectively sequester and internalize approximately 50% of ligand-bound EGFR from the cell surface. This process requires receptor phosphorylation, active phosphatidylinositol 3-kinase, and dynamin 2, although clathrin-coated pits or caveolae are not required. Epithelial and fibroblast cells stimulated with EGF sequestered EGFR rapidly into waves that subsequently generated numerous receptor-positive tubular-vesicular structures. Electron microscopy confirmed that waves formed along the dorsal membrane surface and extended numerous tubules into the cytoplasm. These findings characterize a structure that selectively sequesters large numbers of activated EGFR for their subsequent internalization, independent of traditional endocytic mechanisms such as clathrin pits or caveolae.
Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine, 200 First Street SW, Rochester, MN 55905, USA.
James D
JD
Orth
Eugene W
EW
Krueger
Shaun G
SG
Weller
Mark A
MA
McNiven
D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D004705:Endocytosis / Q000187:drug effects / Q000502:physiology*; D004815:Epidermal Growth Factor / Q000494:pharmacology; D066246:ErbB Receptors / Q000378:metabolism*; D005347:Fibroblasts / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D010190:Pancreatic Neoplasms / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation
D004815:Epidermal Growth Factor; D066246:ErbB Receptors; D019869:Phosphatidylinositol 3-Kinases