Premium
Exploring Membrane Microdomain Organization by Electron Microscopy
Author(s) -
Wilson Bridget S,
Yang Shujie,
Hsieh Genie,
RaymondStintz Mary Ann,
Oliver Janet M
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.4.a521-c
Subject(s) - lipid microdomain , lipid raft , microbiology and biotechnology , receptor , signal transduction , erbb , cell surface receptor , phosphorylation , biology , internalization , cell signaling , membrane , biophysics , cell membrane , chemistry , biochemistry
The flow of information through cells requires the constant remodeling of cell signaling and trafficking networks. To observe events associated with receptor activation, we have generated and analyzed high resolution topographical maps of colloidal gold nanoprobes marking receptors and signaling proteins in native membranes. Here we present the first topographical data comparing the distributions of ErbB family members in SKBR3 breast cancer cells at nanometer scale resolution. These cells express high levels of ErbB2, intermediate levels of EGFR and modest levels of ErbB3. We show that EGFR and ErbB2 are strongly co‐clustered in serum‐starved cells, indicating preferential residency in the same membrane microdomain prior to ligand‐mediated stimulus. We track the redistributions of receptors after EGF or heregulin, as well as recruitment of signaling partners to receptor clusters. These dynamic events are correlated with measured rates of phosphorylation and other readouts of signal tranduction. We also consider the relationship between the signaling complexes that we define by electron microscopy and the “lipid rafts” defined by others as detergent‐resistant membrane fractions that are enriched in cholesterol, glycosphingolipids, and lipid‐anchored proteins. Although our results are broadly consistent with contemporary concepts about the mosaic organization of cell membranes, we find that “raft markers” correlate poorly with either signaling complexes or with each other. We present preliminary results of a multi‐scale mathematical model designed to simulate and predict spatial and temporal aspects of interactions between receptors and signaling proteins within a 2‐dimensional space representing the cell membrane.