Membrane compartmentalisation by the neuronal membrane cytoskeleton 

ABSTRACT:

Neuronal function relies on the organised reception, integration and distribution of signals from and to other cells via a multitude of nanoscopic and microscopic structures that are highly organised towards execution of their specific function. Naturally, superresolution microscopy has received great attention in the neurosciences as it allows access to the small, highly complex and dense structures such as synapses, post-synaptic densities, dendritic spines and the axon initial segment at unprecedented scale and convenience. The best-known discovery made by these novel approaches is the repetitive, ~ 200 nm spaced pattern of actin ring structures along axons. It seems to support structural integrity of the axon, but membrane-associated actin has also been proposed to compartmentalise membranes. We have investigated a possible role of the actin ring structure in the compartmentalisation of the neuronal plasma membrane and could show that indeed the motion of membrane proteins is confined between these actin rings. Our data support the Kusumi model of membrane partitioning by the actin cytoskeleton and provide a new paradigm for the investigation of membrane protein compartmentalisation.