Article abstract
Nature Cell Biology
Published online: 20 July 2008 | doi:10.1038/ncb1755
Actin restricts Fc
RI diffusion and facilitates antigen-induced receptor immobilization
Nicholas L. Andrews1,4, Keith A. Lidke2,3,4, Janet R. Pfeiffer1, Alan R. Burns3, Bridget S. Wilson1, Janet M. Oliver1 & Diane S. Lidke1
Abstract
The actin cytoskeleton has been implicated in restricting diffusion of plasma membrane components. Here, simultaneous observations of quantum dot-labelled Fc
RI motion and GFP-tagged actin dynamics provide direct evidence that actin filament bundles define micron-sized domains that confine mobile receptors. Dynamic reorganization of actin structures occurs over seconds, making the location and dimensions of actin-defined domains time-dependent. Multiple FcRI often maintain extended close proximity without detectable correlated motion, suggesting that they are co-confined within membrane domains. FcRI signalling is activated by crosslinking with multivalent antigen. We show that receptors become immobilized within seconds of crosslinking. Disruption of the actin cytoskeleton results in delayed immobilization kinetics and increased diffusion of crosslinked clusters. These results implicate actin in membrane partitioning that not only restricts diffusion of membrane proteins, but also dynamically influences their long-range mobility, sequestration and response to ligand binding.
- Department of Pathology and Cancer Research and Treatment Center, University of New Mexico, Albuquerque, New Mexico 87131, USA.
- Department of Physics and Astronomy, University of New Mexico, Albuquerque, New Mexico 87131, USA.
- Sandia National Laboratories, Albuquerque, New Mexico 87185-0351, USA.
- These authors contributed equally to this work.
Correspondence to: Diane S. Lidke1 e-mail: dlidke@salud.unm.edu