H-Ras nanocluster stability regulates the magnitude of MAPK signal output

PLoS One. 2010 Aug 5;5(8):e11991. doi: 10.1371/journal.pone.0011991.

Abstract

H-Ras is a binary switch that is activated by multiple co-factors and triggers several key cellular pathways one of which is MAPK. The specificity and magnitude of downstream activation is achieved by the spatio-temporal organization of the active H-Ras in the plasma membrane. Upon activation, the GTP bound H-Ras binds to Galectin-1 (Gal-1) and becomes transiently immobilized in short-lived nanoclusters on the plasma membrane from which the signal is propagated to Raf. In the current study we show that stabilizing the H-Ras-Gal-1 interaction, using bimolecular fluorescence complementation (BiFC), leads to prolonged immobilization of H-Ras.GTP in the plasma membrane which was measured by fluorescence recovery after photobleaching (FRAP), and increased signal out-put to the MAPK module. EM measurements of Raf recruitment to the H-Ras.GTP nanoclusters demonstrated that the enhanced signaling observed in the BiFC stabilized H-Ras.GTP nanocluster was attributed to increased H-Ras immobilization rather than to an increase in Raf recruitment. Taken together these data demonstrate that the magnitude of the signal output from a GTP-bound H-Ras nanocluster is proportional to its stability.

Publication types

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

MeSH terms

  • Animals
  • Cell Line
  • Cell Membrane / metabolism
  • Cell Survival
  • Cricetinae
  • Fluorescence Recovery After Photobleaching
  • Galectin 1 / chemistry
  • Galectin 1 / metabolism
  • Guanosine Triphosphate / metabolism
  • Immobilized Proteins / chemistry
  • Immobilized Proteins / metabolism
  • MAP Kinase Signaling System*
  • Nanostructures / chemistry*
  • Protein Stability
  • Time Factors
  • raf Kinases / chemistry
  • raf Kinases / metabolism
  • ras Proteins / chemistry*
  • ras Proteins / metabolism*

Substances

  • Galectin 1
  • Immobilized Proteins
  • Guanosine Triphosphate
  • raf Kinases
  • ras Proteins