Fluorescence lifetime imaging: association of cortical actin with a PIP3-rich membrane compartment

Eur J Cell Biol. 2008 Sep;87(8-9):735-41. doi: 10.1016/j.ejcb.2008.02.002. Epub 2008 Mar 28.

Abstract

We have used fluorescence lifetime imaging (FLIM) to study actin and plasma membrane dynamics in B16-F1 melanoma cells. In the absence of a FRET acceptor, significant changes in the fluorescence lifetime of GFP were induced simply by linking the fluorophore to different functional probes, including beta-actin, the PH domains of PLCdelta and Akt, the Ras farnesylation signal, and the neuromodulin palmitoylation signal (MEM). In contrast, the lifetime of GFP-actin was constant despite the many different local environments of G- and F-actin within the cell. Treatment with cytochalasin D but not latrunculin A significantly shortened the lifetime of GFP-beta-actin in the absence of a FRET acceptor. Robust lifetime shifts were observed using either a GFP-RFP chimera or co-transfection of GFP-MEM with RFP-MEM. In contrast to previous reports we observed a photobleaching-dependent change in the lifetime of GFP which could complicate the interpretation of FRET experiments. Of the membrane probes tested only the fluorescence lifetime of GFP-Akt was influenced by the presence of mRFP-actin, suggesting that the cortical actin meshwork is associated with a PIP3-enriched compartment of the plasma membrane. These results will aid in the design of new FRET-based approaches to study cytoskeletal interactions at the molecular level.

Publication types

  • Evaluation Study

MeSH terms

  • Actin Cytoskeleton / metabolism
  • Actin Cytoskeleton / ultrastructure*
  • Animals
  • Cell Membrane / chemistry
  • Cell Membrane / metabolism
  • Cell Membrane / ultrastructure*
  • Fluorescence Resonance Energy Transfer / methods*
  • Green Fluorescent Proteins / metabolism
  • Membrane Microdomains / metabolism
  • Membrane Microdomains / ultrastructure
  • Mice
  • Microscopy, Fluorescence*
  • Phosphatidylinositol Phosphates / analysis

Substances

  • Phosphatidylinositol Phosphates
  • Green Fluorescent Proteins