Title: Cholesterol modulates acetylcholine receptor diffusion by tuning confinement sojourns and nanocluster stability,
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.