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Important discoveries in the last decades have changed our view of the plasma membrane organisation. Specifically, the cortical cytoskeleton has emerged as a key modulator of the lateral diffusion of membrane proteins. Cytoskeleton-dependent compartmentalised lipid diffusion has been proposed, but this concept remains controversial because this phenomenon has thus far only been observed with artefact-prone probes in combination with a single technique: single particle tracking. In this paper, we report the first direct observation of compartmentalised phospholipid diffusion in the plasma membrane of living cells using a minimally invasive, fluorescent dye labelled lipid analogue. These observations were made using optical STED nanoscopy in combination with fluorescence correlation spectroscopy (STED-FCS), a technique which allows the study of membrane dynamics on a sub-millisecond time-scale and with a spatial resolution of down to 40 nm. Specifically, we find that compartmentalised phospholipid diffusion depends on the cortical actin cytoskeleton, and that this constrained diffusion is directly dependent on the F-actin branching nucleator Arp2/3. These findings provide solid evidence that the Arp2/3-dependent cortical actin cytoskeleton plays a pivotal role in the dynamic organisation of the plasma membrane, potentially regulating fundamental cellular processes.

Original publication

DOI

10.1038/srep11454

Type

Journal article

Journal

Sci Rep

Publication Date

29/06/2015

Volume

5

Keywords

Actin-Related Protein 2-3 Complex, Actins, Animals, Cell Line, Cell Membrane, Computer Simulation, Diffusion, Embryo, Mammalian, Fibroblasts, Gene Knockdown Techniques, Mice, Phospholipids, Rats, Reproducibility of Results, Spatio-Temporal Analysis, Spectrometry, Fluorescence