Cholesterol modulates acetylcholine receptor diffusion by tuning confinement sojourns and nanocluster stability

TL;DR

This study uses superresolution microscopy and tracking to reveal how cholesterol influences the diffusion, confinement, and nanocluster stability of acetylcholine receptors, affecting synaptic receptor dynamics.

Contribution

It provides new insights into how cholesterol modulates receptor confinement and nanocluster stability, linking membrane composition to receptor mobility and clustering behavior.

Findings

Cholesterol affects confinement duration and nanocluster stability.

Receptor diffusion exhibits heterogeneous modes including subdiffusive, Brownian, and superdiffusive.

Nanoclusters form and disassemble in bursts influenced by cholesterol levels.

Abstract

Translational motion of neurotransmitter receptors is key for determining receptor number at the synapse and hence, synaptic efficacy. We combine live-cell STORM superresolution microscopy of nicotinic acetylcholine receptor (nAChR) with single-particle tracking, mean-squared displacement (MSD), turning angle, ergodicity, and clustering analyses to characterize the lateral motion of individual molecules and their collective behaviour. nAChR diffusion is highly heterogeneous: subdiffusive, Brownian and, less frequently, superdiffusive. At the single-track level, free walks are transiently interrupted by ms-long confinement sojourns occurring in nanodomains of ~36 nm radius. Cholesterol modulates the time and the area spent in confinement. Turning angle analysis reveals anticorrelated steps with time-lag dependence, in good agreement with the permeable fence model. At the ensemble level, nanocluster assembly occurs in second-long bursts separated by periods of cluster disassembly. Thus, millisecond-long confinement sojourns and second-long reversible nanoclustering with similar cholesterol sensitivities affect all trajectories; the proportion of the two regimes determines the resulting macroscopic motional mode and breadth of heterogeneity in the ensemble population.