Ras and its signals diffuse through the cell on randomly moving nanoparticles

Cancer Res. 2006 Feb 15;66(4):1974-81. doi: 10.1158/0008-5472.CAN-05-3791.

Abstract

Spatiotemporal modulation of Ras signaling from different intracellular compartments requires mechanisms allowing Ras and its signals to navigate across cells. Here, we describe one mechanism by which clusters of palmitoylated H-Ras and N-Ras isoforms but not nonpalmitoylated K-Ras diffuse through the cytoplasm, independently of ATP, on fast, randomly moving, small cytosolic nanoparticles ("rasosomes"). Rasosomes forced to diffuse out of live cells and trapped by Ras antibody beads appear as round structures of 80- to 100-nm diameter. Association of H-Ras with rasosomes requires Ras palmitoylation and the hypervariable sequence (hvr) upstream of the palmitoylated cysteines. H-Ras hvr mutants that fail to interact with rasosomes are biologically inactive. Epidermal growth factor stimulation rapidly increases active H-Ras-GTP and phosphorylated extracellular signal-regulated kinase (ERK) on rasosomes. Similarly, rasosomes carrying H-Ras(G12V) but not H-Ras are loaded with active ERK. Thus, the rasosome represents a hitherto unknown particle that enables Ras signal information to spread rapidly across cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphate / metabolism
  • Animals
  • Antibodies / chemistry
  • COS Cells
  • Cell Membrane / metabolism
  • Chlorocebus aethiops
  • Cytoplasm / metabolism
  • Diffusion
  • Fatty Acids, Monounsaturated / chemistry
  • Fatty Acids, Monounsaturated / metabolism
  • Fatty Acids, Monounsaturated / pharmacokinetics
  • Green Fluorescent Proteins / chemistry
  • Green Fluorescent Proteins / genetics
  • Green Fluorescent Proteins / metabolism
  • Green Fluorescent Proteins / pharmacokinetics
  • Microscopy, Fluorescence
  • Mitogen-Activated Protein Kinase Kinases / metabolism
  • Nanostructures*
  • Protein Isoforms
  • Signal Transduction
  • Transfection
  • ras Proteins / chemistry*
  • ras Proteins / genetics
  • ras Proteins / metabolism
  • ras Proteins / pharmacokinetics*

Substances

  • Antibodies
  • Fatty Acids, Monounsaturated
  • Protein Isoforms
  • Green Fluorescent Proteins
  • palmitoleic acid
  • Adenosine Triphosphate
  • Mitogen-Activated Protein Kinase Kinases
  • ras Proteins